JP2010260174A - Method of manufacturing composite material of metal alloy and fiber-reinforced plastic - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide the technique for rigidly adhering metal alloy to CFRP with an epoxy adhesive. <P>SOLUTION: Roughness of micron order is produced on the surface 31 of the metal alloy, a super-fine ruggedness is formed in a ruggedness of the roughness, the surface layer of the super-fine ruggedness is formed as a thin layer of metal oxide or metal-phosphorus oxide. On the surface of the surface layer, a first adhesive (one-component epoxy adhesive) which contains inorganic filler having a particle size center of 5-20 μm and super-fine inorganic filler having a particle size of 100 nm or less is applied, the metal alloy is enclosed in an air-tight container, decompression and compression are performed, thereafter, the adhesive is cured and, further, the layer of the cured adhesive is roughened. On the other hand, the CFRP 32 is cured and the surface of the CFRP is roughened. To both of the roughened metal alloy and the CFRP, a second adhesive (one-component or two-component epoxy adhesive) containing inorganic filler is applied, both members are enclosed in the air-tight container, decompression and compression are performed, thereafter, the both members are fixed, the second adhesive is cured and, thereby, the both are integrated. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a mobile machine, an electric device, a medical device, a general machine, and other general manufacturing fields. The present invention relates to a method for manufacturing a new basic part, and is a composite in which a metal part and fiber reinforced plastic (hereinafter referred to as “FRP (Fiber reinforced plastics)”) are firmly bonded and integrated with an epoxy adhesive. It relates to body manufacturing technology.

  Technology for integrating metal alloys and resins is required from various parts and materials manufacturing industries such as aircraft, automobiles, home appliances, and industrial equipment, and many adhesives have been developed for this purpose. Among these are very good adhesives. For example, an adhesive exhibiting a function at room temperature or by heating is used for joining to integrate a metal alloy and a synthetic resin, and this method is now a common bonding technique.

  On the other hand, bonding methods that do not use an adhesive have also been studied. An example is a method in which a high-strength thermoplastic engineering resin is integrated by injection or the like without using an adhesive to light metals such as magnesium, aluminum, and alloys thereof, and iron alloys such as stainless steel. For example, as a method of joining simultaneously with resin molding by a method such as injection (hereinafter referred to as “injection joining”), polybutylene terephthalate resin (hereinafter referred to as “PBT”) or polyphenylene sulfide resin which is a thermoplastic resin for an aluminum alloy Manufacturing techniques for injection joining (hereinafter referred to as “PPS”) have been developed (see, for example, Patent Documents 1 and 2). In addition, it has been demonstrated that magnesium alloy, copper alloy, titanium alloy, stainless steel, and the like can be injection-bonded by using the same type of resin (see Patent Documents 3, 4, 5, and 6).

  The principle of injection joining in Patent Documents 1 and 2 is shown below. The aluminum alloy is immersed in a dilute aqueous solution of a water-soluble amine compound, and the aluminum alloy is finely etched by the weak basicity of the aqueous solution. In this immersion treatment, ultrafine irregularities are formed on the surface of the aluminum alloy, and at the same time, adsorption of amine compound molecules on the surface of the aluminum alloy occurs. The surface-treated aluminum alloy is inserted into an injection mold, and the molten thermoplastic resin is injected at a high pressure. At this time, a chemical reaction occurs when the thermoplastic resin and the amine compound molecules adsorbed on the aluminum alloy surface are encountered. This chemical reaction suppresses a physical reaction in which the thermoplastic resin is rapidly cooled in contact with an aluminum alloy maintained at a low mold temperature to crystallize and solidify. As a result, the resin is delayed in crystallization and solidification, and in the meantime, enters the ultra-fine irregularities on the aluminum alloy surface. This makes it difficult for the thermoplastic resin to peel off from the aluminum alloy surface even when subjected to external force. That is, the resin molded product formed with the aluminum alloy is firmly bonded. In other words, the chemical reaction and the physical reaction are in a competitive relationship, and in this case, the chemical reaction is prioritized, so it can be said that strong injection joining occurs. In fact, it has been confirmed that PBT and PPS that can chemically react with an amine compound can be injection-bonded with the aluminum alloy. The inventors called this injection joining mechanism “NMT” (abbreviation of Nano molding technology).

  In addition, as shown in Patent Documents 3, 4, 5, and 6, the present inventors obtain special exothermic reaction or assistance of some chemical reaction without chemical adsorption of the amine compound to the metal alloy surface. We have found a condition that enables injection joining without any problem. That is, for metal alloys other than aluminum alloys, a condition was found that allows the metal alloy and thermoplastic resin to be firmly joined by injection joining, and the mechanism of injection joining based on this condition was referred to as “new NMT”. .

  All of these inventions are attributed to the inventors. As described above, the present inventors refer to the joining theory relating to the aluminum alloy as “NMT” theory, and the injection theory relating to all metal alloys as “new NMT” theory. The theoretical hypothesis of “new NMT” that can be used more widely is related to the present invention and will be described in detail below. That is, in order to obtain injection bonding with strong bonding strength, there are conditions on both the metal alloy side and the injection resin side. First, the following three conditions are necessary on the metal alloy side.

[Conditions on the metal alloy side in the new NMT theory]
The first condition is that the metal alloy surface has irregularities with a period of 1 to 10 μm by a chemical etching method, and the irregularity height difference is about half of the period, that is, a rough rough surface of 0.5 to 5 μm. That is. However, in actuality, it is difficult to accurately cover the entire surface with the rough surface, and it is difficult to perform a chemical reaction that is not constant. Specifically, when viewed with a roughness meter, it is not within the range of 0.2 to 20 μm. It is necessary to be able to draw a roughness curve having irregularities with a regular cycle and a maximum height difference of 0.2 to 5 μm. Further, when the surface of the metal alloy is scanned with the latest dynamic mode scanning probe microscope, if the roughness surface is RSm of 0.8 to 10 μm and Rz of 0.2 to 5 μm, the roughness described above is used. The degree condition is substantially satisfied. Here, RSm is the average length of contour curve elements defined in Japanese Industrial Standard (JIS B 0601: 2001, ISO 4287: 1997), and Rz is Japanese Industrial Standard (JIS B 0601: 2001, ISO 4287: 1997). The inventors of the present invention called the “surface having a roughness on the order of microns” as an easy-to-understand term because the ideal rough surface irregularity period is approximately 1 to 10 μm as described above.

  The second condition is that ultrafine irregularities having a period of 5 nm or more are further formed on the surface of the metal alloy having a roughness on the order of microns. In other words, it needs to be rough when viewed with microscopic eyes. In order to satisfy the conditions, fine etching is performed on the surface of the metal alloy, and the inner wall surface of the concave portion having the above-mentioned micron-order roughness is 5 to 500 nm, preferably 10 to 300 nm, more preferably 30 to 100 nm (optimum A value of 50 to 70 nm) is formed.

  Describing the ultra-fine irregularities, if the irregular period is a period of 10 nm or less, it is clearly difficult to enter the resin component. Further, in this case, since the unevenness height difference is usually small, the surface becomes smooth as viewed from the resin side. As a result, it no longer serves as a spike. If the period is about 300 to 500 nm or longer (in that case, the diameter and period of the concave part having a micron order roughness is estimated to be close to 10 μm), the spike in the micron order concave part Because the number of slashes, the effect becomes difficult to work. Therefore, in principle, it is necessary that the period of the ultra fine irregularities is in the range of 10 to 300 nm. However, depending on the shape of the ultra-fine irregularities, the resin may enter between them even if it has a period of 5 nm to 10 nm. For example, this is the case when rod-like crystals having a diameter of 5 to 10 nm are complicated. Even with a period of 300 nm to 500 nm, the shape of the ultra-fine irregularities may easily cause an anchor effect. For example, this corresponds to a shape like a pearlite structure in which steps having a height and depth of several hundred to 500 nm and a width of several hundred to several thousand nm are infinitely continuous. Including such a case, the required period of ultra fine irregularities was specified to be 5 nm to 500 nm.

  Here, conventionally, regarding the first condition, the RSm range is defined as 1 to 10 μm and the Rz range is defined as 0.5 to 5 μm, but the RSm is 0.8 to 1 μm and the Rz is 0.2 to 0.2 μm. Even if it is the range of 0.5 micrometer, if the uneven | corrugated period of an ultra fine unevenness | corrugation exists in the especially preferable range (generally 30-100 nm), joining force can be maintained highly. Therefore, we decided to expand the range of RSm slightly to a smaller one. That is, RSm was in the range of 0.8 to 10 μm and Rz was in the range of 0.2 to 5 μm.

  Furthermore, the third condition is that the surface layer of the metal alloy is ceramic. Specifically, with respect to the metal alloy type that originally has corrosion resistance, the surface layer needs to be a metal oxide layer having a thickness equal to or greater than that of the natural oxide layer, and the metal alloy type having relatively low corrosion resistance ( For example, in the case of a magnesium alloy or a general steel material, the third condition is that the surface layer is a thin layer of metal oxide or metal phosphorous oxide generated by chemical conversion treatment or the like.

  These are schematically illustrated as shown in FIG. Concave portions (C) having a roughness on the order of microns are formed on the surface of the metal alloy 40, and ultra fine irregularities (A) are formed on the inner walls of the concave portions, and the surface layer is a ceramic layer 41. In addition, a part of the cured adhesive layer 42 penetrates into the ultra-fine irregularities. When the liquid resin composition penetrates into the surface of the metal alloy thus formed and is cured after the penetration, the metal alloy and the cured resin composition are joined together very firmly.

[Conditions on the resin side in the new NMT theory]
Next, the conditions on the resin side will be described. As the resin, it is possible to use a hard, highly crystalline thermoplastic resin that has a reduced crystallization rate during quenching by compounding another polymer suitable for this. Actually, a resin composition compounded with another polymer suitable for PBT or PPS, which is a crystalline hard resin, and glass fiber can be used.

[Injection joining based on the new NMT theory]
The metal alloy and the resin can be used for injection joining with a general injection molding machine or injection mold. This process will be described according to “New NMT”. The injected molten resin is introduced into a mold having a temperature of about 150 ° C. lower than the melting point, but is cooled in this flow path, and is considered to be a temperature below the melting point. That is, when the melted crystalline resin is quenched, even if the melting point is lower than the melting point, crystals are formed in zero time and do not change to a solid. In short, a melted state below the melting point, that is, a supercooled state exists for a very short time. As described above, this supercooling time can be lengthened a little by applying a special compound to PBT or PPS. This was used to allow the microcrystals to penetrate into the concave portions of the metal surface having a roughness on the order of microns before the viscosity rapidly increased due to the generation of a large amount of microcrystals. Since it continues to cool after intrusion, the number of microcrystals increases rapidly and the viscosity increases rapidly. However, whether or not the resin can reach the depth of the recess depends on the size and shape of the recess.

  According to the experimental results of the present inventors, the metal alloy type is not selected, and the concave portion having a diameter of 1 to 10 μm according to the roughness of the micron order is sufficient if the depth is up to about half of the period. It was speculated that microcrystals invaded deeply. Furthermore, if the inner wall surface of the recess is a rough surface as seen in the second condition as described above, a part of the resin also penetrates into the ultra-fine irregularities, and as a result, a pulling force is exerted on the resin side. It is presumed that even if it is added, it will be caught and difficult to come off. And if this rough surface is covered with metal oxide or metal phosphorous oxide as shown in the third condition, the hardness is high, and the catch between the resin and the concave portion related to the ultra fine unevenness is effective as a spike. Become.

  A specific example is shown. For example, in the case of a magnesium alloy, the corrosion resistance of a magnesium alloy that is still covered with a natural oxide layer is low, so by converting this into a metal oxide, metal carbonate, or metal phosphate, The surface can be covered with a ceramic material having high hardness. When the surface-treated magnesium alloy is inserted into an injection mold, the mold and the inserted magnesium alloy are kept at a temperature lower than the melting point of the resin to be injected by at least 100 ° C. As soon as it enters the flow path in the mold, it is rapidly cooled, and when it approaches the magnesium alloy, there is a high possibility that it is below the melting point.

  When the diameter of the concave portion on the surface of the magnesium alloy is relatively large, such as about 1 to 10 μm, the resin can enter within a limited time during which microcrystals are generated by supercooling. Further, even when the number density of the generated polymer microcrystal group is still small, the resin can penetrate if it is the concave portion. Because the size of a microcrystal, that is, a crystallite having a shape when an alignment state occurs from a molecular chain that has been moving irregularly to a molecular chain, is estimated to be a size of several to 10 nm when estimated from a molecular model. It is. Therefore, it is difficult to say that microcrystals can easily penetrate into ultrafine irregularities with a diameter of 10 nm. However, if the ultrafine irregularities have a period of several tens of nm, there is a possibility that the tip of the resin flow slightly enters. However, since innumerable microcrystals are generated at the same time, the viscosity of the resin flow rapidly rises at the point where it is in contact with the tip of the injection resin or the metal mold surface. When the surface of the magnesium alloy that has been subjected to chemical conversion treatment is observed with an electron microscope, an ultrafine uneven surface with a period of 10 to 50 nm is observed, and if this is an ultrafine unevenness with a period of this level, the head is thrust before the viscosity of the resin flow suddenly rises. obtain.

  Further, when the surface of a metal alloy such as a copper alloy, a titanium alloy or a steel material is oxidized or subjected to a chemical conversion treatment to form a ceramic crystallite group such as a metal oxide or an amorphous layer, an improved PPS ( When a PPS compound having a reduced PPS molecular crystallization rate at the time of rapid cooling was injection joined, a considerably strong joining force was generated.

Here, the bonding itself is a problem of the resin component and the surface of the metal alloy. However, if the resin composition contains reinforcing fibers or inorganic fillers, the linear expansion coefficient of the entire resin can be made closer to that of the metal alloy. It becomes easy to maintain the bonding force. In accordance with such a hypothesis, for example, a composite obtained by injection-bonding PBT or PPS resin to magnesium alloy, copper alloy, titanium alloy, stainless steel or the like has a shear breaking force of 20 to 30 MPa (about 200 to 300 kgf / cm ² ) or more, and a tensile breaking force of 30 to 40 MPa (about 300 to 400 kgf / cm ² ) or more, which is confirmed to be a strong composite.

[NAT theory (adhesive bonding)]
The present inventors considered that “new NMT” can also be applied to adhesive bonding, and confirmed whether high-strength bonding based on a similar theory is possible. And it tried to obtain the joined body with higher adhesive force by using the commercially available general-purpose one-component epoxy adhesive and devising the surface structure of the metal alloy.

  The procedure regarding the experimental method of adhesive bonding is shown below. Based on the “new NMT”, a metal alloy having the same surface as that used in the injection joining experiment (that is, a metal alloy satisfying the above three conditions) was prepared. Then, apply a liquid one-component epoxy adhesive to a predetermined range of the metal alloy, put it in a desiccator, place it under vacuum, and then return it to normal pressure. Invade. That is, the adhesive is sufficiently infiltrated into the metal alloy surface. Thereafter, the adherend is bonded to the predetermined range and heated to be cured.

  In such a case, an epoxy adhesive having a certain viscosity can penetrate into the concave portion (roughness concave portion in the first condition) on the surface of the metal alloy having a roughness on the micron order because of the liquid. And the epoxy adhesive which penetrate | invaded hardens | cures in this recessed part by subsequent heating. Actually, an ultra fine unevenness is further formed on the inner wall surface of the recess (the second condition described above), and the ultra fine unevenness is a thin ceramic-like thin film (the third condition described above). Since it is covered, the epoxy resin that has entered the inside of the recess and solidified is difficult to come out by being gripped by ultra-fine irregularities such as spikes.

  By applying “New NMT”, the present inventors are capable of high-strength bonding between metal alloys and between metal alloys and CFRP (abbreviation of carbon fiber reinforced plastics) with a one-component epoxy adhesive. Proved. As an example, as a result of joining A7075 aluminum alloys with a commercially available one-component epoxy adhesive, a joined body having an intense shear breaking force and tensile breaking force as high as 70 MPa could be obtained (Patent Document 7).

  In fact, such high-strength adhesive joints have been demonstrated by the present inventors in magnesium alloys, copper alloys, titanium alloys, stainless steels, and general steel materials after aluminum alloys (Patent Document 7, 8, 9, 10, 11, and 12). In any case, various metal alloys could be bonded with unprecedented strength by controlling the state of the metal alloy surface. The present inventors have applied the “new NMT” technology for such adhesive bonding as “NAT (abbreviation of nano adhesion technology)”.

WO 03/064150 A1 (aluminum alloy) WO 2004/041532 A1 (Aluminum alloy) WO 2008/069252 A1 (magnesium alloy) WO 2008/047811 A1 (copper alloy) WO 2008/078714 A1 (titanium alloy) WO 2008/081933 A1 (stainless steel) WO 2008/114669 A1 (aluminum alloy) WO 2008/133096 A1 (magnesium alloy) WO 2008/126812 A1 (copper alloy) WO 2008/133030 A1 (titanium alloy) WO 2008/133296 A1 (stainless steel) WO 2008/146833 A1 (general steel)

  As described above, the present inventors used a commercially available one-part epoxy adhesive, and based on “NAT”, conducted an experiment to bond and bond metal alloys to each other or a metal alloy and CFRP. Regarding the bonding of CFRP, the shear breaking force and the tensile breaking force tended to be lower than when metal alloys were bonded to each other. Strong adhesion between a metal alloy and CFRP is expected in various fields such as aircraft and ships. However, when a metal alloy and CFRP are bonded with a one-component epoxy adhesive, an adhesive force equivalent to that of metal alloys cannot be stably obtained. Specifically, a composite in which a metal alloy and CFRP are bonded has a large variation between the composites in terms of shear breaking force and tensile breaking force, and has a problem in practical use. By improving the adhesive, it was possible to reduce the variation in adhesive strength between the composites somewhat, but it did not lead to a fundamental solution. In addition, when this variation is reduced, there is a problem that the adhesive strength itself is lowered.

  The present invention has been made based on such a background, and an object thereof is to stably obtain a high adhesive force when a metal alloy and a fiber reinforced plastic are bonded together with an adhesive.

  Initially, the present inventors applied a one-component epoxy adhesive to the surface of a metal alloy that meets the first to third conditions of “NAT”, soaked this adhesive on the surface, and then applied the adhesive. An uncured CFRP prepreg was brought into close contact with the range and the whole was heated to obtain a composite in which the metal alloy and CFRP were bonded. That is, the curing of the adhesive and the curing of the CFRP prepreg were performed simultaneously. Here, in the comparison between the adhesion between the metal alloys and the adhesion between the metal alloy and CFRP, the cause of the difference in the adhesion force and its stability was initially unknown. However, from the subsequent experiments conducted by the present inventors and observation of the fracture surface, it has been found that the cause is the CFRP prepreg itself. That is, the adhesive force between the cured matrix resin and the cured adhesive on the cured CFRP prepreg surface layer exceeded the adhesive force between the cured matrix resin and the carbon fiber inside the cured CFRP prepreg. Thereby, at the time of a fracture | rupture, peeling may arise previously between the hardened matrix resin and carbon fiber, and this appeared as a low adhesive force.

  A bonding method in which the CFRP prepreg and the adhesive are cured almost simultaneously is called a co-curing method. In this adhesion by the co-curing method, the CFRP prepreg curing conditions specified by the manufacturer were used as they were, but these conditions did not necessarily optimize the adhesion between the matrix resin and the carbon fibers. In other words, the curing conditions specified by the manufacturer are conditions for the CFRP member obtained by curing the CFRP prepreg to reach the desired strength, and the CFRP member supports high-strength bonding. Whether it can be done is a different issue.

  The present inventors have determined that the co-curing method of simultaneously curing both of the matrix resin of CFRP and the epoxy adhesive is optimal for bonding the metal alloy and CFRP. However, as described above, at the time of rupture, since there is a problem that separation occurs first between the cured matrix resin and the carbon fiber, in order to further improve the adhesion, the matrix resin and It can be said that it is necessary to improve the adhesion between the carbon fibers. The present inventors once cured the CFRP prepreg, and then bonded the obtained CFRP member (cured product of CFRP prepreg) and the metal alloy with an epoxy adhesive. That is, a co-bonding method was adopted in which an epoxy adhesive was applied to both the metal alloy and the CFRP member, and these were bonded together and heated to cure the epoxy adhesive to bond both. In this cobond method, unlike the cocure method, the curing of the CFRP prepreg and the curing of the adhesive are separate steps. In the present invention, the adhesive force is improved by bonding the metal alloy and CFRP by the co-bonding method. The present invention relates to a bonding technique of a metal alloy and CFRP by a co-bonding method, and provides a new bonding technique different from the co-curing method.

  Here, when joining metal alloys with an adhesive, it is optimal to use “NAT” developed by the present inventors. That is, an epoxy adhesive is applied to the surface of the metal alloy having the first to third conditions described above, the adhesive application ranges are brought into close contact with each other, and heated to obtain a joined body of the metal alloys. The present inventors newly developed an epoxy adhesive suitable for the “NAT”. In the present invention, an epoxy adhesive suitable for “NAT” is used as an adhesive I described later. This adhesive I has both adhesive strength and heat resistance. In the present invention, the adhesive I suitable for “NAT” is applied to the surface of the metal alloy and heated to cure the adhesive I. Thereby, the adhesive hardened | cured material layer integrated very firmly with the metal alloy surface is formed.

  On the other hand, the present inventors also developed an adhesive applied to the CFRP member to be bonded to the metal alloy. This adhesive exhibits a strong adhesive force in an experiment in which the present inventors adhere CFRP members (cured products of CFRP prepreg) to each other. In the present invention, the adhesive is used to bond a metal alloy and CFRP. Used as Agent II.

  An outline of the present invention will be briefly described. First, the surface of the metal alloy is etched to satisfy the first to third conditions described above. Then, adhesive I is applied to the surface of the metal alloy. This adhesive I is an epoxy adhesive, and a one-component epoxy adhesive is preferable. The adhesive I is soaked into the surface of the metal alloy and treated I, and then heated to cure the adhesive I. In short, adhesive I is used like paint. Next, the cured adhesive layer formed so as to cover the surface of the metal alloy is roughened. On the other hand, the CFRP prepreg is cured before bonding with the metal alloy described above to prepare a CFRP member. The CFRP member (cured product of CFRP prepreg) obtained here is preferably subjected to a second heat treatment. Here, it is particularly preferable to perform the heat treatment again at a temperature higher than the temperature required for curing. In the present invention, a total of three heat treatments were performed. Thereby, the adhesive force between CFRP matrix resin and carbon fiber was improved in the already cured CFRP member. Next, the surface of the CFRP member was roughened.

  By these steps, both a metal alloy having a roughened adhesive-cured material layer and a roughened CFRP member are obtained. After the adhesive II is applied to both of these roughened portions, it is soaked and processed II, so that the roughened portion is soaked with the adhesive II. Thereafter, the metal alloy and the CFRP member are bonded and fixed so that the areas where the adhesive II is applied are in close contact with each other, and the adhesive II is cured by heating. As a result, a composite of the metal alloy and CFRP is obtained.

  Here, an epoxy adhesive is used as the adhesive II, but either a one-component epoxy adhesive or a two-component epoxy adhesive may be used. Here, if this final bonding work can be performed with a simple heating device without using equipment such as a large hot air dryer or a large autoclave, it will be a technology with excellent practicality, and the site where the bonding work will be performed It can be said that this is an extremely useful technique. From such a viewpoint, it can be said that the adhesive II is preferably a one-component epoxy adhesive that can be cured almost completely by heating at a temperature of 100 to 120 ° C. for about 1 hour. The present inventors have developed an adhesive that meets these conditions as the adhesive II. Its composition will be described later. The adhesive strength and heat resistance are not as high as those of the one-component epoxy adhesive, but a two-component epoxy adhesive that facilitates the bonding operation can also be used as the adhesive II.

  When the metal alloy and the CFRP member were bonded according to the present invention, the shear fracture strength at room temperature was high (for example, A7075 aluminum alloy), which was 60 MPa or more, indicating extremely high adhesive strength. In addition, there was little variation in the adhesive strength between the composites, and stable and high adhesive strength was exhibited. The adhesive force between the metal alloy and the cured product layer of the adhesive I is about 60 to 70 MPa in terms of the shear breaking force at room temperature. On the other hand, the adhesion force between the CFRP member and the cured material layer of the adhesive II is 50 to 60 MPa in terms of the shear breaking force at normal temperature. The adhesive strength between the cured product layer of the adhesive I and the cured product layer of the adhesive II is also in the order of 60 MPa when expressed in terms of shear breaking force at room temperature. From these values, the composite of the finally obtained metal alloy and CFRP member was expected to have a shear breaking force exceeding 50 MPa at room temperature, and the results agreed with this. In addition, the shear fracture | rupture force under 100 degreeC was also high, showed about 50 Mpa, and became a composite which has very high heat resistance. This result is due to the hardened matrix resin and carbon fiber being firmly bonded in the CFRP member.

Hereafter, each element which comprises this invention is demonstrated in detail.
[Metal alloy]
The kind of metal alloy in the present invention, that is, a metal alloy having a surface structure based on the above-mentioned “NAT” is not particularly limited in theory. However, “NAT” can actually be applied to hard and practical metal alloys. The present inventors have exemplified metal alloy species mainly composed of aluminum, magnesium, copper, titanium, and iron as metal alloy species to which “NAT” can be applied. Hereinafter, these will be described. However, since “NAT” aims to improve the adhesive force by the anchor effect, it is not limited to at least the following metal alloy types. Patent Document 7 describes an aluminum alloy. Patent Document 8 describes a magnesium alloy. Patent Document 9 describes a copper alloy. Patent Document 10 describes a titanium alloy. Patent Document 11 described stainless steel. Patent Document 12 describes general steel materials. These various metal alloys will be described in detail.

(Aluminum alloy)
There is no restriction | limiting in the aluminum alloy used by this invention. A1000 series to 7000 series (corrosion-resistant aluminum alloy, high-strength aluminum alloy, heat-resistant aluminum alloy, etc.), which are aluminum alloys for extension specified in Japanese Industrial Standard (JIS), can be used. Any one of ADC 1 to 12 types (aluminum alloy for die casting) can also be used.

(Magnesium alloy)
For example, a magnesium alloy for extension (for example, A31B) and a magnesium alloy for casting (for example, AZ91D) specified by the International Standard Organization (ISO), Japanese Industrial Standard (JIS), American Society for Testing and Materials (ASTM), or the like can be used.

(Copper alloy)
The copper alloy used in the present invention refers to copper, brass, phosphor bronze, Western night, aluminum bronze and the like. All copper, including pure copper alloys such as C1020 and C1100, C2600 brass alloys, C5600 copper white alloys and other iron-based copper alloys for connectors as defined in Japanese Industrial Standards (JIS H 3000 series) Alloys are the target.

(Titanium alloy)
The titanium alloy used in the present invention is a pure titanium alloy, an α-type titanium alloy, a β-type titanium alloy, an α-β-type titanium alloy, etc. defined by the International Organization for Standardization (ISO), Japanese Industrial Standards (JIS), etc. All titanium alloys are targeted.

(Stainless steel)
The stainless steel in the present invention is a Cr-based stainless steel obtained by adding chromium (Cr) to iron, a Cr-Ni-based stainless steel added by combining nickel (Ni) with chromium (Cr), A known corrosion-resistant iron alloy called stainless steel is the object. SUS405, SUS429, SUS403, and other Cr-based stainless steels standardized by the International Organization for Standardization (ISO), Japanese Industrial Standards (JIS), American Material Testing Association (ASTM), etc., SUS301, SUS304, SUS305, SUS316, etc. Cr—Ni stainless steel is included.

(Steel)
The steel materials used in the present invention refer to steel materials such as carbon steels (so-called general steel materials) such as general structural rolled steel materials, high-tensile steels (high-tension steels), low-temperature steels, and reactor steel plates. Specifically, cold rolled steel (hereinafter referred to as “SPCC”), hot rolled steel (hereinafter referred to as “SPHC”), hot rolled steel sheet for automobile structure (hereinafter referred to as “SAPH”). Structural steel materials such as hot-rolled high-tensile steel plate materials for automobile processing (hereinafter referred to as “SPFH”) and steel materials mainly used for machining (hereinafter referred to as “SS material”) are included. Moreover, the steel materials referred to in the present invention are not limited to the above steel materials, but include all steel materials standardized by the Japanese Industrial Standard (JIS), the International Organization for Standardization (ISO), and the like.

[Chemical etching]
The purpose of chemical etching in the present invention is to produce a roughness on the order of microns on the surface of a metal alloy. There are various types of corrosion, such as general corrosion, pitting corrosion, and fatigue corrosion, but it is possible to select an appropriate etching agent by selecting a chemical species that causes general corrosion for the metal alloy and trial and error. According to literature records (for example, “Chemical Engineering Handbook (edited by the Chemical Engineering Association)”), aluminum alloys are basic aqueous solutions, magnesium alloys are acidic aqueous solutions, stainless steel and general steel materials in general are hydrohalic acid such as hydrochloric acid, sulfurous acid, There is a record that the entire surface is corroded by an aqueous solution of sulfuric acid or a salt thereof. In addition, copper alloys with strong corrosion resistance are totally corroded by strong oxidizing agents such as hydrogen peroxide, and titanium alloys can be corroded entirely with oxalic acid or hydrofluoric acid-based special acids. And from the patent literature. The metal alloys that are actually sold in the market, such as pure copper-based copper alloys and pure titanium-based titanium alloys, have a purity of 99.9% or more and are hardly called alloys. Included in the alloy. Most of the metal alloys that are actually used are mixed with a wide variety of elements in order to obtain characteristic physical properties, and there are few pure metal materials, and they are substantially alloys.

  That is, most metal alloys are alloyed from pure metal for the purpose of improving corrosion resistance without deteriorating the original metal properties. Therefore, depending on the metal alloy, even if the acid / base or a specific chemical substance is used, the target chemical etching is often not possible. In practice, appropriate chemical etching is performed by trial and error while devising the concentration of the acid / base aqueous solution to be used, the liquid temperature, the immersion time, and, in some cases, the additive. Regarding the chemical etching method, Patent Document 7 describes an aluminum alloy, Patent Document 8 describes a magnesium alloy, Patent Document 9 describes a copper alloy, Patent Document 10 describes a titanium alloy, and Patent Document 11 describes a stainless steel. And Patent Document 12 described general steel materials.

  The points that are generally common in the work actually performed will be described. After shaping the metal alloy into a predetermined shape, the metal alloy is degreased by immersing it in an aqueous solution in which a degreasing agent for the metal alloy is dissolved and washed with water. This process is a process for removing most of the machine oil and finger grease adhering in the process of shaping the metal alloy, and it is preferably always performed. Then, it is preferably immersed in a thinly diluted acid / base aqueous solution and washed with water. This is a process that the present inventors have referred to as preliminary acid cleaning and preliminary base cleaning. In the case of a metal alloy that corrodes with an acid such as a general steel material, it is immersed in a basic aqueous solution and washed with water. Further, in the case of a metal alloy that is particularly rapidly corroded with a basic aqueous solution such as an aluminum alloy, it is immersed in a dilute acid aqueous solution and washed with water. These are processes in which a solution opposite to the aqueous solution used for chemical etching is attached (adsorbed) to the metal alloy in advance, and the subsequent chemical etching starts without an induction period, so that the reproducibility of the process is remarkably improved. . Therefore, the preliminary acid cleaning and preliminary base cleaning steps are not essential, but are preferably employed in practice. After these steps, a chemical etching step is performed.

[Fine etching / Surface hardening]
The purpose of fine etching in the present invention is to form ultra-fine irregularities on the surface of a metal alloy. Moreover, the surface hardening process in this invention aims at making the surface layer of a metal alloy into a thin layer of a metal oxide or a metal phosphate. Depending on the type of metal alloy, nano-order fine etching may be performed at the same time by performing the chemical etching, and ultra-fine irregularities may be formed. Furthermore, depending on the type of metal alloy, the surface natural oxidation layer may be thicker than the original and the surface hardening process may be completed. For example, a pure titanium-based titanium alloy is subjected only to chemical etching, so that the surface has a roughness on the order of microns and ultra-fine irregularities are also formed. That is, fine etching is performed together with chemical etching. However, in many cases, it is necessary to carry out fine etching or surface hardening treatment after forming a large uneven surface on the order of microns by chemical etching.

  Even at this time, we are often hit by unpredictable chemical phenomena. That is, when a metal alloy after chemical etching is reacted with an oxidizing agent or chemical conversion treatment for the purpose of surface hardening treatment or surface stabilization treatment, ultra fine irregularities may be formed on the resulting surface by chance. The surface layer that appears to be manganese oxide formed when a magnesium alloy is subjected to chemical conversion treatment with a potassium permanganate aqueous solution is a complex of rod-like crystals having a diameter of 5 to 10 nm that can be finally identified with a 100,000-fold electron microscope. Although this sample was analyzed by XRD (X-ray diffractometer), diffraction lines derived from manganese oxides could not be detected, but it is clear by XPS analysis that the surface was covered with manganese oxide. The reason why XRD could not be detected is that the crystal was a thin layer exceeding the detection limit. In short, the magnesium alloy was subjected to a chemical conversion treatment as a surface hardening treatment, so that fine etching was also completed. The same applies to copper alloys. When surface hardening treatment was performed to change the surface to cupric oxide by oxidation under basic conditions, the surface of pure copper-based copper alloys was covered with an elliptical hole opening. It becomes an ultra fine uneven surface. On the other hand, in the case of a copper alloy that is not pure copper-based, not a concave shape but a particle size or an indefinite polygonal shape having a diameter of 10 to 150 nm is continuous, and an ultrafine uneven surface in a form of being partially melted and stacked. Even in this case, most of the surface is covered with cupric oxide, and the hardening of the surface and the formation of ultrafine irregularities occur simultaneously.

  For general steel materials, although further verification is required, ultra-fine irregularities are often formed only by chemical etching to form micron-order roughness, and originally the surface layer (natural oxide layer) However, it was considered that “NAT” can be applied without performing a surface hardening process or a fine etching process again. The problem is that the corrosion resistance of the natural oxide layer is not sufficient, so that corrosion starts before the bonding process, or the adhesive force decreases in a short time depending on the environment after bonding. These can be prevented by chemical conversion treatment. For example, regarding a joined body in which general steel materials (SPCC: cold rolled steel materials) not subjected to chemical conversion treatment are bonded with a phenol resin adhesive, the adhesive strength rapidly decreased in a short period of 4 weeks. On the other hand, regarding the joined body in which the general steel materials (SPCC) subjected to the chemical conversion treatment were bonded to each other with the phenol resin-based adhesive, they did not decrease from the initial adhesive force in the same period.

  In addition, the present inventors have generally confirmed that the adhesive force often decreases when the film (chemical conversion film) formed on the surface of the metal alloy by chemical conversion treatment is thick. A strong adhesive force can be obtained when the thin layer is such that a diffraction line is not detected by XRD, such as the thin layer of manganese oxide adhered to the magnesium alloy. When metal alloys having a thick chemical conversion film are bonded to each other with an epoxy adhesive and subjected to a destructive test, most of the fracture surface is between the chemical conversion film and the metal alloy layer. In experiments conducted by the present inventors, the bonding force between the thick chemical conversion film and the cured epoxy adhesive was always stronger than the bonding force between the chemical conversion film and the metal alloy. That is, even with a general steel material, it is considered that the adhesive strength does not decrease for a long period of time if the chemical conversion treatment time is further increased to increase the thickness of the chemical conversion treatment layer. However, if the chemical conversion film is thickened, the adhesive strength itself is reduced. Therefore, the degree of balance depends on the purpose of use and application. Hereinafter, the surface treatment method of various metal alloys will be described in detail.

[Specific examples of surface treatment]
(Surface treatment of aluminum alloy)
In the surface treatment of the aluminum alloy, first degreasing treatment is performed. The degreasing treatment unique to the present invention is not necessary, and a commercially available aqueous solution of a degreasing material for aluminum alloy is used. That is, the degreasing treatment commonly used for aluminum alloys may be used. Although it differs depending on the degreasing material, in a general commercial product, the concentration is 5 to 10%, the liquid temperature is 50 to 80 ° C., and the aluminum alloy is immersed in this for 5 to 10 minutes.

  In the subsequent steps, the treatment method is different between an alloy containing a relatively large amount of silicon in an aluminum alloy and an alloy containing few components. Here, a method for treating an aluminum alloy having a low silicon content will be described. That is, the following treatment methods are preferred for aluminum alloys for drawing such as A1050, A1100, A2014, A2024, A3003, A5052, and A7075. That is, it is preferable that the aluminum alloy is immersed in an acidic aqueous solution for a short time and washed with water, and the acid component is adsorbed on the surface layer of the aluminum alloy in order to proceed the next chemical etching with good reproducibility. This treatment is referred to as a preliminary pickling step, and a dilute aqueous solution having a concentration of 1% to several percent of an inexpensive mineral acid such as nitric acid, hydrochloric acid, sulfuric acid or the like can be used. Subsequently, after performing chemical etching immersed in a strongly basic aqueous solution, it is washed with water. In this chemical etching, a 1% to several percent concentration of caustic soda aqueous solution is preferably set to 30 to 40 ° C., and the aluminum alloy is preferably immersed in this for several minutes.

  By this chemical etching, oils and dirt remaining on the surface of the aluminum alloy are peeled off together with the surface layer of the aluminum alloy. Simultaneously with this peeling, the surface has a roughness on the order of microns. That is, the uneven surface has an RSm of 0.8 to 10 μm and an Rz of 0.2 to 5.0 μm. Next, it is preferable to remove sodium ions by immersing again in an acidic aqueous solution and washing with water. The inventors refer to this as a neutralization step. As this acidic aqueous solution, a nitric acid aqueous solution having a concentration of several percent is particularly preferable.

  Fine etching, which is the final treatment, is performed on the aluminum alloy that has undergone the neutralization step. In the fine etching, the aluminum alloy is immersed in an aqueous solution containing one or more of hydrated hydrazine, ammonia, and a water-soluble amine compound. Thereafter, it is preferably washed with water and dried at 70 ° C. or lower. This is also a measure for reviving the rough surface with respect to the fact that the surface is slightly changed by the sodium removal ion treatment performed in the neutralization step and the roughness is maintained, but the surface becomes slightly smooth. Fine etching is performed by dipping in a weakly basic aqueous solution such as a hydrated hydrazine aqueous solution for a short time. It is particularly preferable that a large number of ultrafine irregularities with a period of 40 to 50 nm are formed on the inner wall surface of the concave portion having a roughness on the order of microns.

  Here, when the drying temperature after washing with water is set to a high temperature of, for example, 100 ° C. or higher, if the inside of the dryer is sealed, a hydroxylation reaction occurs between boiling water and aluminum, and the surface changes to form a boehmite layer. The This is not preferable because it cannot be said to be a strong surface layer. In order to prevent boehmite formation on the surface, it is preferable to dry with hot air at 90 ° C. or lower, preferably 70 ° C. or lower. When dried at 70 ° C. or lower, only aluminum (trivalent) can be detected from the aluminum peak by surface elemental analysis by XPS, and aluminum (zero valent) that can be detected by XPS analysis of commercially available A5052, A7075 aluminum alloy sheet, etc. disappears. . The XPS analysis can detect elements present at a depth of 1 to 2 nm from the metal surface. From this result, it is immersed in an aqueous solution of hydrated hydrazine or an amine compound, and then washed with water and dried with warm air to obtain aluminum. It was confirmed that the original natural oxide layer (a thin aluminum oxide layer having a thickness of about 1 nm) that the alloy had became thicker by fine etching. Unlike at least the natural oxide layer, it was confirmed that the thickness was 2 nm or more.

(Surface treatment of magnesium alloy)
In the surface treatment of the magnesium alloy, first, degreasing treatment is performed. Specifically, a commercially available aqueous solution of a degreasing material for magnesium alloy is used. In a general commercial product, the concentration is 5 to 10%, the liquid temperature is 50 to 80 ° C., and the magnesium alloy is immersed in this for 5 to 10 minutes.

  Next, chemical etching in which the magnesium alloy is immersed in an acidic aqueous solution for a short time is performed and washed with water. The surface layer of the magnesium alloy including the dirt that cannot be removed in the degreasing process is peeled off, and at the same time, a roughness on the order of microns is generated. That is, when scanning with a scanning probe microscope, irregularities with RSm of 0.8 to 10 μm and Rz of 0.2 to 5 μm are detected. As the aqueous solution for chemical etching, an aqueous solution of carboxylic acid or mineral acid having a concentration of 1% to several percent can be used. Particularly preferred are aqueous solutions of citric acid, malonic acid, acetic acid, nitric acid and the like. In chemical etching, aluminum and zinc contained in a magnesium alloy usually do not dissolve and remain on the surface of the magnesium alloy as a black smut. Then, the aluminum smut is removed by soaking in a weakly basic aqueous solution. It is preferable to dissolve the zinc smut by immersing it in a strong base aqueous solution.

  In this way, the magnesium alloy from which the smut is dissolved and eliminated is subjected to chemical conversion treatment. That is, since magnesium is a metal with a very high ionization tendency, the oxidation rate by moisture and oxygen in air is faster than other metals. Magnesium alloys have a natural oxide film, but are not strong enough from the viewpoint of corrosion resistance, and oxidative corrosion easily proceeds even in a normal environment. Therefore, in general, magnesium alloys are soaked in an aqueous solution such as chromic acid or potassium dichromate to cover the entire surface with a thin layer of chromium oxide (called chromate treatment), or a manganese salt containing phosphoric acid. A treatment for covering the entire surface with a manganese phosphate compound is performed by dipping in an aqueous solution of the above, and a corrosion prevention treatment is performed. These treatments are called chemical treatments in the magnesium industry.

  In short, the chemical conversion treatment performed on the magnesium alloy refers to a treatment in which the magnesium alloy is immersed in an aqueous solution containing a metal salt and the surface thereof is covered with a thin layer of metal oxide and / or metal phosphate. At present, the chromate-type chemical conversion treatment using a hexavalent chromium compound is avoided from the viewpoint of environmental pollution. The chemical conversion treatment using a metal salt other than chromium, which is called non-chromate treatment, is actually described above. Manganese phosphate chemical conversion treatment or silicon chemical conversion treatment is performed. In the present invention, unlike these methods, it is particularly preferable to use a weakly acidic aqueous solution of potassium permanganate as the aqueous solution for chemical conversion treatment. In this case, a coating covering the surface (referred to as a chemical conversion coating) is manganese dioxide.

  As a specific treatment method, as described above, the magnesium alloy excluding the smut is immersed in a very dilute acidic aqueous solution for a short time, and then washed with water to remove the basic component of the surface layer. The method of immersing in the aqueous solution for chemical conversion treatment after that, washing with water, and drying is preferable. A citric acid or malonic acid aqueous solution having a concentration of 0.1 to 0.3% is used as the dilute acidic aqueous solution. It is preferable to immerse in this aqueous solution at around room temperature for about 1 minute. As the chemical conversion treatment aqueous solution, it is preferable to use an aqueous solution containing 1.5 to 3% potassium permanganate, about 1% acetic acid and about 0.5% sodium acetate at a temperature of 40 to 50 ° C. In this aqueous solution, the immersion time is preferably about 1 minute. By these operations, the magnesium alloy is covered with a chemical conversion film of manganese dioxide, and the surface thereof has a roughness on the order of microns and has nano-order ultrafine irregularities formed thereon.

  FIGS. 3A and 3B are 100,000 times electron micrographs of the surface of the magnesium alloy subjected to the above treatment. Although it is difficult to express these ultra-fine concavo-convex shapes with sentences, from an electron micrograph of FIG. 3 (a), a rod-like or spherical object having a diameter of 5 to 20 nm and a length of 20 to 200 nm. It can be said that the surface is covered with infinitely complex irregularities. From the electron micrograph of FIG. 3 (b), this ultra fine concavo-convex shape is irregularly shaped by a rod having a diameter of 5 to 20 nm and a length of 10 to 30 nm, or a spherical object having a diameter of 80 to 120 nm with an infinite number of spherical protrusions. It can be said that the shape is stacked on top of each other. The rod-like (needle-like) substance having a diameter of about 10 nm can be said to be completely crystalline from the result of observation with an electron microscope, but the diffraction line seen in manganese oxide by analysis with an X-ray diffractometer (XRD). Was not recognized.

  Since an X-ray diffractometer (XRD) cannot detect if the amount of crystals is small, it cannot be determined whether these are crystals at present. At least, these are too amorphous to be amorphous (non-crystalline), so it is determined that they are not amorphous. From XPS analysis, large peaks of manganese (which is an ion and not zero-valent manganese) and oxygen are recognized, and there is no doubt that the surface layer is a manganese oxide. This surface has a dark color tone and is a manganese oxide mainly composed of manganese dioxide.

(Surface treatment of copper alloy)
In the surface treatment of the copper alloy, degreasing treatment is first performed. Specifically, a commercially available aqueous solution of a degreasing material for copper alloy is used. Commercially available degreasing agents for iron, stainless steel, or aluminum alloy can also be used. Furthermore, an aqueous solution in which a neutral detergent for industrial use or general household is dissolved can be used. Usually, a commercially available degreasing agent or neutral detergent is dissolved in water to a concentration of several% to 5%, the temperature of this aqueous solution is 50 to 70 ° C., and the copper alloy is immersed in this for 5 to 10 minutes and washed with water. .

  Next, it is preferable to perform preliminary base washing in which the copper alloy is immersed in a caustic soda solution having a concentration of several percent maintained at around 40 ° C. and then washed with water. Further, chemical etching is performed by immersing the copper alloy in an aqueous solution containing hydrogen peroxide and sulfuric acid, followed by washing with water. This chemical etching is preferably performed using an aqueous solution containing several percent of both sulfuric acid and hydrogen peroxide at 20 ° C. to around room temperature. Although the immersion time at this time changes with alloy types, it is several minutes-20 minutes. In this chemical etching process, a roughness on the order of microns is obtained with most copper alloys. That is, when analyzed with a scanning probe microscope, RSm is 0.8 to 10 μm and Rz is 0.2 to 5 μm.

  Next, the surface hardening process which oxidizes the surface of the copper alloy which passed through the said chemical etching process is performed. Although a method called blackening treatment is known in the electronic component industry, the surface effect treatment carried out in the present invention is different from the blackening treatment in its purpose and degree of oxidation, but the content of the treatment itself is the same. It is. Chemically speaking, the surface layer of the copper alloy is oxidized with an oxidizing agent under strong basicity. When copper atoms are ionized with an oxidizing agent, if the surroundings are strongly basic, they are not dissolved in an aqueous solution and become black cupric oxide. When a copper alloy part is used as a heat sink or a heat generating material part, the surface is blackened to improve the efficiency of heat radiation and heat absorption. This processing is called blackening processing in the electronic component industry using copper. This blackening treatment can also be used for the surface hardening treatment of the present invention. However, the purpose of the surface hardening treatment in the present invention is to form nano-order ultra-fine irregularities on the surface of a copper alloy having a certain roughness and harden the surface layer (that is, fine etching and surface hardening treatment). Literally not blackening.

  In the present invention, similarly to the blackening treatment, a commercially available blackening agent is used at a concentration and temperature indicated by a commercial manufacturer. However, the immersion time in the present invention is extremely short compared to the blackening treatment in the electronic component industry. The surface hardening treatment was performed with different immersion times, and the surface of the copper alloy after each surface hardening treatment was observed with an electron microscope to identify a suitable immersion time. As specific conditions, it is preferable to use an aqueous solution containing about 5% sodium chlorite and 5 to 10% caustic soda at 60 to 70 ° C., in which case the immersion time is 0.5 to 1.0 minutes. The degree is preferred. By these operations, the copper alloy is covered with a thin layer of cupric oxide. When the surface is observed with an electron microscope, the surface has a roughness on the order of microns, and a circular hole having a diameter of 10 to 150 nm and an elliptic hole having a major axis or a minor axis of 10 to 150 nm are formed on the surface. . And this circular hole and elliptical hole become the ultra fine uneven | corrugated shape which exists in the whole surface with a 30-300 nm period (this example was shown with the photograph of FIG.4 (b)). In short, when this surface hardening treatment is performed, both ultra-fine irregularities and a surface hardened layer can be obtained simultaneously. In the surface hardening treatment, when the immersion time in the treatment liquid was set to 2 to 3 minutes, the adhesive strength with the adherend was reduced. From this, it was confirmed that performing the surface curing treatment for a long time weakens the adhesive strength, and is not preferable.

  Here, in a pure copper-based copper alloy (for example, C1020), the rough surface obtained as a result of the above-described chemical etching often has an RSm of more than 10 μm. Moreover, even if RSm was 10 μm or less, the RSm was clearly larger than copper alloys other than pure copper. Rz is obviously small for a large RSm (for example, RSm is 8 μm, Rz is 0.4 μm, etc.). In particular, when the metal crystal grain size is large, such as C1020 (oxygen-free copper) having a high copper content, the RSm is clearly increased as described above, and the irregularity period and the metal crystal grain size are large. Was estimated to have a direct correlation. In chemical etching of pure copper-based copper alloys, it was possible to identify from the observation results that copper erosion occurred from the metal crystal grain boundaries. In any case, if the range of RSm is larger than 10 μm, the first condition of the present invention is not satisfied. Even if the range of RSm is 10 μm or less, the anchor effect is difficult to occur and the effect of the present invention is hardly exhibited if Rz is clearly small compared to the RSm. Even when the adhesion experiment was actually performed, a material having a particularly large crystal grain size, such as oxygen-free copper (for example, C1020), could not exert a strong adhesive force only by performing the above-described chemical etching and surface hardening treatment.

  Therefore, the present inventors once again performed chemical etching and re-curing the surface of the pure copper-based copper alloy that had been subjected to the surface-curing treatment, for which it was determined that Rz was relatively small. The second chemical etching may be performed in a shorter time than the first chemical etching. As a result, RSm was 10 μm or less, and Rz was several μ or more. Further, according to observation with an electron microscope, the ultra-fine irregularities are the same as when the repeated treatment is not performed.

(Titanium alloy surface treatment)
In the surface treatment of the titanium alloy, first, degreasing treatment is performed. There is no need for special ones. Specifically, general degreasing agents such as commercially available iron degreasing agents, stainless steel degreasing agents, aluminum alloy degreasing materials, magnesium alloy degreasing agents and the like can be used. Moreover, the aqueous solution which melt | dissolved the industrial neutral detergent marketed can also be used. Usually, a commercially available degreasing agent or neutral detergent is dissolved in water to a concentration of several percent, the temperature of this aqueous solution is set to around 60 ° C., a titanium alloy is immersed therein, and then washed with water. Thereafter, it is preferably immersed in a basic aqueous solution and washed with water, followed by preliminary base washing.

  Next, it is preferable to perform chemical etching by dipping in an aqueous solution of a reducing acid. Specifically, oxalic acid, sulfuric acid, hydrofluoric acid, or the like can be used as the reducing acid that can corrode the titanium alloy. Of these, hydrofluoric acid has the highest etching rate. Therefore, hydrofluoric acid is used when efficiency is important. However, hydrofluoric acid can invade human skin and lead to bones, which can last for several days. In short, there are problems different from hydrochloric acid and the like, and it is preferable to avoid the use of hydrofluoric acid from the viewpoint of the working environment.

  Preference is given to ammonium hydrofluoride, a half-neutralized product of hydrofluoric acid which can be handled much more safely than hydrofluoric acid. A treatment method in which an aqueous solution of about 1% of 1 hydrogen difluoride ammonium is immersed in this solution for several minutes at a temperature of 50 to 60 ° C. and then washed with water is preferable. Chemical etching with 1 hydrogen di-ammonium difluoride aqueous solution was performed to obtain micron-order roughness. However, in electron microscopic observation and observation with the latest analytical equipment, the surface of the titanium alloy is washed and dried after chemical etching. It turned out that it became a mysterious shape of ultra fine irregularities, and the surface was covered with a thin layer of titanium oxide. In short, separate fine etching and surface hardening treatment were unnecessary.

  An analysis example of a titanium alloy that has been etched with an aqueous solution of 1 hydrogen diammonium difluoride, washed with water, and then dried is shown. First, a scanning analysis result by a scanning probe microscope was obtained. In this case, a 20 μm square area was scanned, and RSm was 1.8 μm and Rz was 0.9 μm. Further, examples of 10,000 times and 100,000 times electron micrographs of the same processed materials are shown in FIG. 8 ((a): 10,000 times, (b): 100,000 times). Here, a very unique and mysterious ultra-fine concavo-convex shape in which a mountain-shaped or mountain-shaped (mountain) -shaped convex part having a height and width of 10 to 300 nm and a length of 10 nm or more is present on the entire surface with a period of 10 to 350 nm is shown. It was done.

  According to XPS analysis, large oxygen and titanium peaks were obtained, and the surface compound was clearly titanium oxide. However, the surface color tone was dark brown, and it was seen as a thin film of titanium (trivalent) oxide or a mixed oxide of titanium (trivalent) and titanium (tetravalent). That is, the surface was a metal color before etching, and this surface was a natural oxidation layer of titanium. This titanium oxide layer was etched by 10 to several tens of nm with an argon ion beam, and the etched surface was subjected to XPS analysis. This XPS analysis revealed the thickness of the titanium oxide layer, which is clearly thicker than the natural oxide layer, and when pure titanium-based titanium alloy was etched with an aqueous solution of 1 hydrogen difluoride ammonium. It was considered to be 50 nm or more.

  Moreover, the valence of titanium ions decreases from the surface to the inside, the divalence increases from the tetravalent or trivalent and tetravalent mixed state on the surface toward the inside, and further the divalent decreases to zero. It turns out that it leads to metal. In short, the oxide film that is titanium oxide is not a simple titanium oxide layer, but a continuously changing layer in which the titanium valence continuously decreases from the surface and reaches zero. As it penetrated from the surface, the surface was a continuously changing layer that became darker and thinner toward the inside. Since there is no clear boundary between such a metal oxide film and a metal alloy, the bonding force between the oxide film layer and the metal alloy layer is extremely strong. Therefore, it can be said that it has sufficient resistance to the force to peel off both.

  The specific treatment method for titanium alloys other than pure titanium-based titanium alloys is the same as the treatment method described above, but is included as a small amount of additive by the nascent hydrogen gas generated during etching with a reducing strong acid aqueous solution. In some cases, other metals may be reduced to produce insoluble matter, so-called smut. Most of the smut can be dissolved and removed by immersing in a nitric acid aqueous solution of several percent concentration. However, depending on the alloy, smut that does not dissolve in the aqueous nitric acid solution may be generated. In that case, it is preferable to wash by applying ultrasonic waves during washing with water.

  The surface shape of an alloy other than a pure titanium-based titanium alloy etched with ammonium monohydrogen difluoride and smut-removed is a surface shape whose language is difficult to express in comparison with the above-mentioned photograph of FIG. become. An example of an α-β type titanium alloy containing aluminum is shown in the photograph of FIG. 9 ((a): 10,000 times, (b): 100,000 times). Here, a smooth dome-like part without ultra-fine irregularities (similar to FIG. 8) that looks like a titanium alloy is observed, but a mysterious shape like a dead leaf of a plant was observed. The entire surface is not covered with ultrafine irregularities having a period of 10 to 300 nm, which is preferable as the second condition described above, but a surface with a longer period (called “fine irregularities”) is observed. The unevenness itself was smooth.

  However, apart from the smooth dome-shaped portion in this surface, the dead leaf shape portion is thin and curved, and if it has hardness, it becomes a strong spike shape. The surface of the α-β type titanium alloy has almost no portion that does not meet the above-mentioned second condition (ultra-fine irregularities with a period of 5 nm to 500 nm) in the NAT theory. It is thought that it can play the role of unevenness. Since the surface spike shape is large, it is also related to the micron-order roughness (surface roughness) required under the first condition required by NAT. With this spike shape, a roughness surface that satisfies the first condition (RSm is 0.8 to 10 μm, Rz is 0.2 to 5 μm) as viewed with a scanning probe microscope is formed. In addition, since it slightly deviates from the second condition and the concavo-convex period is large, the whole surface image cannot be grasped with an electron micrograph of 100,000 times. The surface was observed by taking a magnification photograph of 10,000 times or less. That is, as shown in FIG. 9 (a), an area of at least a 10 μm square or more is viewed with a 10,000 × electron microscope. By doing so, a fine uneven shape in which both a smooth dome shape and a curved dead leaf shape are present is observed.

(Stainless steel surface treatment)
In the surface treatment of stainless steel, first, degreasing treatment is performed. A special degreasing agent is not required, and a commercially available general degreasing agent for stainless steel, a degreasing agent for iron, a degreasing agent for aluminum alloy, or a commercially available neutral detergent can be used. Usually, a commercially available degreasing agent or neutral detergent is dissolved in water to a concentration of several percent, the temperature of this aqueous solution is 40 to 70 ° C., stainless steel is immersed in this for 5 to 10 minutes, and then washed with water. Next, it is preferable to immerse this stainless steel in a caustic soda aqueous solution having a concentration of several percent for a short time, and then wash with water to adsorb basic ions on this surface. This is because the preliminary chemical cleaning improves the reproducibility of the next chemical etching.

  Stainless steel corrodes entirely with aqueous solutions of hydrohalic acid such as hydrochloric acid, sulfurous acid, sulfuric acid, and metal halide salts. When chemical etching is performed, the immersion conditions may be changed depending on the type of stainless steel. Here, in the case where the hardness is lowered by annealing or the like to structurally increase the metal crystal grain size, the crystal grain boundaries are reduced, and it is difficult to obtain a micron-order roughness by corroding the entire surface. In such a case, it is necessary to devise such as adding some kind of additive without the chemical etching progressing to the intended level simply by setting the immersion conditions so that corrosion proceeds. In any case, chemical etching is performed so as to obtain a surface in which a portion having a roughness on the order of microns is predominant.

  In the case of SUS304, a method in which an aqueous sulfuric acid solution having a concentration of about 10% is set to a temperature of 60 to 70 ° C. and is immersed in the solution for several minutes is preferable. Moreover, in SUS316, it is preferable to immerse a sulfuric acid aqueous solution of about 10% concentration at a temperature of 60 to 70 ° C. for 5 to 10 minutes. Hydrohalic acid, such as aqueous hydrochloric acid, is also suitable for chemical etching, but if this aqueous solution is heated to high temperatures, part of the acid may volatilize and corrode surrounding iron structures. Some processing is required for the gas. In that sense, the use of an aqueous sulfuric acid solution is preferable in terms of cost. However, depending on the steel material, the progress of overall corrosion may be too slow with an aqueous solution of sulfuric acid alone. In such a case, it is effective to add hydrohalic acid to the sulfuric acid aqueous solution. In stainless steel, fine etching is achieved at the same time by performing chemical etching.

  After the chemical etching, the surface of the stainless steel is naturally oxidized by sufficiently washing with water, and returns to the surface layer that can resist corrosion. However, in order to make the metal oxide layer on the stainless steel surface thicker and stronger, an oxidizing acid such as nitric acid such as nitric acid, ie nitric acid, hydrogen peroxide, potassium permanganate, sodium chlorate, etc. After immersing in an aqueous solution, it is preferably washed with water.

  FIG. 10 shows an example in which stainless steel is actually chemically etched with an aqueous sulfuric acid solution. A micron-order roughness is formed on the surface by appropriate etching. When the surface is observed with an electron microscope, it can be seen that the surface is covered with ultrafine irregularities. In short, in stainless steel, fine etching is achieved at the same time by chemical etching alone. In FIG. 10, a shape in which particles having a diameter of 20 to 70 nm, indefinite polygonal shapes, and the like are stacked is recognized, and this 10,000 times photograph (FIG. 10A) and 100,000 times photograph (FIG. 10B). Both of them were very similar to the lava field on the slope of the lava plateau formed by lava flowing around the volcano. When XPS analysis was performed on the surface of stainless steel covered with ultra-fine irregularities, large peaks of oxygen and iron and small peaks of nickel, chromium, carbon, and molybdenum were recognized. In short, the surface is an oxide of a metal having exactly the same composition as that of ordinary stainless steel, and is covered with a similar corrosion resistant surface.

(Surface treatment of steel materials)
In the surface treatment of the steel material, first, degreasing treatment is performed. In steel materials that are commercially available, such as SPCC, SPHC, SAPH, SPFH, SS material, etc., degreasing agents that are commercially available for these steel materials, degreasing agents for stainless steel, degreasing agents for aluminum alloys, or commercially available A general-purpose neutral detergent can be used. Usually, a commercially available degreasing agent or neutral detergent is dissolved in water to a concentration of several percent, the temperature of this aqueous solution is set to 40 to 70 ° C., the steel material is immersed in this for 5 to 10 minutes, and then washed with water. Next, after immersing in a dilute caustic soda aqueous solution for a short time, it is preferably washed with water. This is because the preliminary chemical cleaning improves the reproducibility of the next chemical etching.

  All steel materials are corroded entirely with aqueous solutions of hydrohalic acid such as hydrochloric acid, sulfurous acid, sulfuric acid, and their salts. When chemical etching is performed, the immersion conditions may be changed depending on the type of steel material. In the case of SPCC, it is preferable to immerse the sulfuric acid aqueous solution of about 10% concentration at 50 ° C. for several minutes. This is a chemical etching process for obtaining roughness on the order of microns. For SPHC, SAPH, SPFH, and SS materials, it is preferable to increase the temperature of the sulfuric acid aqueous solution by 10 to 20 ° C. from the former and perform chemical etching. Hydrohalic acid, such as aqueous hydrochloric acid, is also suitable for chemical etching, but has the problems described above. Therefore, the use of an aqueous sulfuric acid solution is preferable in terms of cost.

<Surface treatment method I: Chemical etching only>
After the chemical etching described above, it is washed with water, dried, and observed with an electron micrograph. Ultra fine irregularities with a height and depth of 50 to 500 nm and a width of several hundred to several thousand nm followed by infinite steps. Often, the shape covers almost the entire surface. This seems to have exposed the pearlite structure that steel materials generally have. Specifically, when an aqueous sulfuric acid solution is used under appropriate conditions in the chemical etching step, an uneven surface having a micron-order roughness can be obtained, and at the same time, stepped ultrafine unevenness can be formed simultaneously. Many. When the formation of micron-order roughness and ultra-fine irregularities is made at once, the water that has been sufficiently washed after the chemical etching and then drained and rapidly dried at a high temperature of 90 to 100 ° C. Can be used as is. No rust discolored on the surface, resulting in a beautiful natural oxide layer.

  However, it is considered that the corrosion resistance in a general environment is insufficient with only the natural oxide layer. In addition to being stored in a dry state, a bonded body in which an adherend is bonded to the steel material cannot maintain an adhesive force over a long period of time. When a joined body in which steel materials after chemical etching were bonded together with a one-component epoxy adhesive was left for 1 month and then subjected to a break test, the adhesive strength was lower than that at the beginning of bonding. From this, it was confirmed that the surface stabilization treatment was necessary.

<Surface treatment method II: Adsorption of amine-based molecules>
After the chemical etching described above, the substrate is washed with water, immersed in an aqueous solution of ammonia, hydrazine, or a water-soluble amine compound, washed with water, and dried. A broad amine-based substance such as ammonia remains in the steel material. When the steel material after drying is analyzed by XPS, nitrogen atoms are confirmed. Therefore, it was estimated that amines in a broad sense including ammonia and hydrazine were chemically adsorbed on the steel material surface. According to the result of observation with a 100,000-fold electron microscope, a thin film-like foreign substance is adhered to the surface, and thus an iron-based complex of iron may be generated.

  In any case, the adsorption or reaction of these amine-based molecules seems to have priority over the adsorption of water molecules and the iron hydroxide formation reaction. In that sense, at least several days to several weeks until the application of the epoxy adhesive can suppress the generation of rust due to moisture adsorption and reaction. In addition, the maintenance of the adhesive strength after the adhesion was also superior to “Surface treatment method I”, and there was no reduction in the bonding strength when the joined body was left for 4 weeks.

  The concentration and temperature of the aqueous ammonia, the aqueous hydrazine solution, or the aqueous solution of the water-soluble amine to be used hardly require strict condition setting. Specifically, an effect can be obtained by using an aqueous solution having a concentration of 0.5 to several percent at room temperature, immersing for 0.5 to several minutes, washing with water and drying. Industrially, ammonia water having a concentration of about 1%, which is slightly odorous but inexpensive, or a 1% to several percent aqueous solution of hydrated hydrazine having a small odor and a stable effect is preferable.

<Surface treatment method III: chemical conversion treatment>
The steel material that has undergone chemical etching or the steel material that has been subjected to chemical etching and adsorption of the amine-based molecules is washed with water, and then immersed in an aqueous solution containing a hexavalent chromium compound, a permanganate, or a zinc phosphate-based compound. Wash with water. By this chemical conversion treatment, the steel material surface is covered with metal oxides such as chromium oxide, manganese oxide, and zinc phosphorus oxide, and metal phosphorus oxide, thereby improving the corrosion resistance. This is a well-known method for improving the corrosion resistance of steel materials. However, the purpose of the chemical conversion treatment in the present invention is not to ensure complete corrosion resistance, but has at least sufficient corrosion resistance until the application of the adhesive, and it is difficult for the adhesive application part to cause trouble over time even after bonding. It is to be. In short, when the chemical conversion film is thickened, it is preferable from the viewpoint of corrosion resistance, but not preferable from the viewpoint of bonding strength. Although a chemical conversion film is necessary, since it has a property of being hard but brittle, if it is too thick, the bonding force is weakened.

  When a steel material is immersed in a dilute aqueous solution of chromium trioxide, washed with water, and dried, the surface is covered with chromium (III) oxide. The surface was not covered with a uniform film-like object, and protrusions having a diameter of 10 to 30 nm and an equivalent height were generated at a distance of about 100 nm. Further, an aqueous solution of potassium permanganate having a concentration of several percent adjusted to weak acidity could be preferably used. In order to obtain a high adhesive force on the surface of the steel material, it is necessary to make the chemical conversion film thin. As a result of searching for the conditions for that, even if any aqueous solution is used, an aqueous solution having a concentration of several percent is set to a temperature of 45 to 60 ° C., and the steel material is immersed in this for 0.5 to several minutes. there were.

[Epoxy adhesive]
Epoxy adhesives are classified into one-component epoxy adhesive and two-component epoxy adhesive, and are classified into either one depending on the curing agent used. When an aliphatic polyamine compound is used as a curing agent, polymerization and gelation can be started at around room temperature. Therefore, this curing agent cannot be marketed in a state mixed with an epoxy resin. In this case, it cannot be a one-component epoxy adhesive and is supplied as a two-component epoxy adhesive. In other words, the two-component epoxy adhesive is hardened by leaving it to stand for several tens of minutes or several hours at room temperature depending on the curing agent. It can be said that there is. On the other hand, the curing agent used in the one-component epoxy adhesive is an amine that is not an aliphatic amine or an amine compound in a broad sense. Specifically, dicyandiamide, imidazoles, and aromatic diamines are used. Acid anhydrides and phenol resins can also be used. When these are used as curing agents, they can be stored in a mixed and kneaded state at room temperature (excluding summer) for several months, and if stored refrigerated, they can be stored for over a year. It is.

(Epoxy resin)
A standard epoxy adhesive contains at least three components: (1) an epoxy resin, (2) a curing agent, and (3) an inorganic filler. Various types of epoxy adhesives are commercially available, but since the raw materials for epoxy adhesives are readily available from the city, they can be made by themselves. For example, bisphenol-type epoxy resins, polyfunctional polyphenol-type epoxy resins, alicyclic epoxy resins, and the like are commercially available as epoxy resins that serve as raw materials for adhesives. In addition, various polyfunctional epoxy resins in which an epoxy group is bonded to a polyfunctional compound (for example, a polyfunctional compound or oligomer having a plurality of hydroxyl groups or amino groups) are commercially available. Usually, these are used by mixing them appropriately. In ordinary commercial adhesives, the majority of all epoxy resins are liquid and low viscosity bisphenol A type epoxy resin monomer types. Add multimer type of bisphenol type epoxy resin with large molecular weight to give quickness, add phenol type epoxy resin to give heat resistance, and add compound with polyfunctional type epoxy group to gain strength. There is a way. Also in the present invention, an epoxy resin was prepared according to this method.

(Inorganic filler)
Commercially available structural adhesives may contain classified inorganic fillers having a particle size distribution center of 5 to 20 μm. Specifically, it is a powder classification such as talc, clay (clay, kaolin), calcium carbonate, silica, glass and the like. These inorganic fillers have a function of preventing microcracks generated in the cured adhesive from being linked to chain breakage. That is, it has a role of improving the adhesive force by keeping the local fracture locally. As shown in Tables 1 and 2, an inorganic filler is also added to the adhesives I and II of the present invention. Hereinafter, the composition of the adhesive I and the adhesive II used in the present invention will be described in detail.

[Composition of adhesive I]
The adhesive I is an adhesive that is applied to the surface of a metal alloy that has been subjected to a surface treatment based on NAT. In the present invention, the adhesive I is a one-component epoxy adhesive. This is because nano-order ultrafine irregularities are formed on the surface of the metal alloy, and it is necessary to allow the adhesive I to penetrate into the ultrafine irregularities. The temperature of the metal alloy coated with the adhesive I is raised to lower the viscosity of the adhesive to 15 Pa seconds or less, preferably 10 Pa seconds or less. Once this is reduced to a pressure close to vacuum, the pressure is about 1 atmosphere or more. The adhesive I penetrates into the ultra-fine irregularities by pressurizing up to. In order for the adhesive I to smoothly enter the ultra-fine irregularities, it is important that the adhesive molecules are not too large. Therefore, a two-part epoxy adhesive that can start polymerization and gelation from the moment when the curing agent is mixed with the epoxy resin is not suitable. The operation of depressurization and pressurization after the adhesive I is applied to the surface of the metal alloy is referred to as “soaking treatment I”. In the case of using a two-component epoxy adhesive, polymerization and gelation start before performing the soaking and treatment I, so that the adhesive molecules become large and it is difficult to penetrate into the ultra-fine irregularities. Therefore, it is not preferable to use a two-component epoxy adhesive as the adhesive I.

(Curing agent)
Usually, the curing agent used for the one-component epoxy adhesive is an amine compound other than aliphatic amines, such as amine compounds in a broad sense, acid anhydrides, and phenol resins. Specifically, dicyandiamide, imidazoles, aromatic diamines, acid anhydrides, phenol resins and the like can be used. In order to obtain an adhesive with good workability, it is also necessary that the finally obtained adhesive composition be in the form of a high-viscosity liquid or paste. Including the conditions, dicyandiamide, imidazoles, acid anhydrides and Become. Furthermore, in the present invention, since the CFRP matrix resin that adheres to the metal alloy is an epoxy thermosetting resin composition that uses aromatic diamines as a curing agent, it is used as a one-component epoxy adhesive that becomes the adhesive I. As the curing agent to be used, dicyandiamide or imidazoles which are amine compounds in a broad sense are preferable.

(Ultra fine inorganic filler)
In the present invention, an ultrafine inorganic filler having a particle size of 100 nm or less was added to the one-component epoxy adhesive used as the adhesive I. There is no example of an ultrafine inorganic filler added to a commercially available adhesive. Applying an adhesive containing an ultrafine inorganic filler to the surface of a metal alloy that has been surface-treated to conform to NAT and bonding it to the adherend will greatly improve the heat resistance of the adhesive. This was confirmed by experiments by the inventors. Specifically, fumed silica is preferably used, and the amount used is preferably 0.3 to 3.0% by mass of the adhesive. When this is added, it also penetrates into the concave part on the surface of the metal alloy having a roughness on the order of microns, and when it is placed under high temperature and the hardness of the resin content in the cured adhesive is lowered, that is, the spike in the concave part. When the effect is lowered, there is an effect of keeping the shape of the cured adhesive in the concave portion and preventing the cured adhesive from easily coming out. For this reason, on the contrary, no effect is observed when used at room temperature. Therefore, if it is not used at high temperature, or if there is no actual harm as a product even if the adhesive strength is reduced at high temperature, there is not much meaning to add it, but there is a possibility of raising the temperature to 80-100 ° C in practical products Should always be considered, the addition of ultrafine inorganic fillers plays a very important role.

  There are two types of fumed silica. One is ultra-fine fused silica recovered from the exhaust gas in the reduction process that uses silica (silicon oxide) sand as a raw material to obtain metallic silicon. The other is vaporized and combusted silicon tetrachloride to form ultrafine fused silica, which is commercially available under the trademark “Aerosil”. The inventors used Aerosil in search of stable properties. Aerosil that has been surface-treated is also commercially available, and the present inventors have used a hydrophobic treatment. The fumed silica obtained by the combustion treatment is not necessarily highly hydrophilic, but the hydrophobic treatment is considered to have better affinity with the epoxy resin.

  Normally, powders with particle sizes smaller than micron order are agglomerated, and Aerosil is actually an agglomerated product. The agglomeration force becomes stronger as the powder becomes ultrafine powder, and the agglomeration cannot be solved and the dispersed state assumed in the present invention cannot be achieved as long as it is put into an adhesive and kneaded in an automatic mortar. Therefore, it is necessary to apply to a high performance disperser after addition to the epoxy resin. From the experimental results, the addition amount of the ultrafine inorganic filler is preferably 0.3% by mass or more, particularly preferably 0.3 to 3.0% by mass of the adhesive. When added over 3.0% by mass, not only was the viscosity increased and it was difficult to use, but when used, the adhesive strength was equal or decreased.

(Thermoplastic resin powder)
In the present invention, an elastomer component is added as a thermoplastic resin powder to the one-component epoxy adhesive used as the adhesive I. Addition of an elastomer component to at least adhesive I did not significantly reduce the adhesive strength. This was the same when the elastomer component was added to the adhesive II. Depending on the environment in which the composite is used, there are situations where such an elastomer component needs to be added. For example, when used for a metal alloy that easily deforms, it is preferable to add an elastomer component. In addition, for a composite used in an environment where vibration or impact is applied, the elasticization of the adhesive contributes to the performance improvement of the composite as a whole. Therefore, the fact that at least the adhesive strength does not decrease is important. Various vulcanized rubbers, powder rubbers modified on the surface of various vulcanized rubbers, various raw rubbers, modified rubbers modified from various raw rubbers, vinyl chloride resin (hereinafter “PVC”), vinyl acetate resin (hereinafter “PVA”), polyvinyl formal Resin (hereinafter “PVF”), ethylene vinyl acetate resin (hereinafter “EVA”), polyolefin resin, polyethylene terephthalate resin (hereinafter “PET”), various polyamide resins (hereinafter “PA”), polyethersulfone resin (hereinafter referred to as “PET”) “PES”), polyurethane resin, thermoplastic polyester elastomer (hereinafter “TPEE”), thermoplastic polyurethane elastomer (hereinafter “TPU”), thermoplastic polyamide elastomer (hereinafter “TPA”), thermoplastic polyolefin elastomer (hereinafter “TPO”). )) Etc. are elastomer components as referred to in the present invention. .

  Some of these are generally not defined as elastomers, but the cured epoxy resin is hard. Compared to this, the thermoplastic resins are all soft. Therefore, when added to the adhesive I, the thermoplastic resin functions as an elastomer component. By adding the thermoplastic resin, the toughness of the cured product is enhanced by the softness of the elastomer component. It is preferable to add fine powder having a particle size of 5 to 30 μm and further improve the surface to a parent epoxy resin mold. Since it is an amino group or a hydroxyl group that reacts with the epoxy resin at a high temperature, it is an effective modification treatment to have these at the ends of the elastomer. In the present invention, since an adhesive that exhibits a strong adhesive force not only at room temperature but also at a relatively high temperature is required, an excessively soft material is not preferable. Listed here are those that are easy to obtain while taking these into consideration: PVF that easily forms hydroxyl groups, urethane resins with hydroxyl groups at the ends, PAs with countless amino groups, and PES with intentionally hydroxyl groups. is there.

  Considering elastomeric properties, vulcanized rubber powder is considered to be most suitable as a filler, but a particle size of 5 to 30 μm is difficult to obtain. There are also thermoplastic resins that can produce particles in this range, so they are selected from the group. SBR, NBR (nitrile rubber), urethane resin, and other soft thermoplastic resins (including thermoplastic elastomers) are commercially available as parts and elastic paints. Is suitable. In addition, as a main application of the adhesive composite of the metal alloy and CFRP, since it is a structure of a mobile machine or the like, reliability in a high temperature environment is also required. Therefore, a thermoplastic resin having elasticity that is not excessively softened at a high temperature of about 100 to 150 ° C. is suitable. In this respect, a polyethersulfone resin (hereinafter referred to as “PES”) having a high softening point is preferable. PES has a use as a filler for heat resistant elastic coatings, and since fine pulverization is industrially performed, a product having a particle size distribution center of 10 to 20 μm can be easily obtained. A preferable addition amount of the thermoplastic resin powder is 0 to 5% by mass of the adhesive.

(Carbon nanotube (1))
Further, carbon nanotube (Carbon Nanotube: hereinafter referred to as “CNT”) may be added to the adhesive I as a filler. The inventors conducted an experiment in which metal alloys having surfaces compatible with NAT are bonded to each other with an adhesive added with CNTs. As a result, the addition of CNT had the effect of increasing the adhesive strength at room temperature. That is, if the CNTs can be appropriately dispersed in the adhesive, the entire cured adhesive layer has high strength. In the case of a joined body of metal alloys surface-treated so as to conform to NAT, when the joined body was forcibly broken in a temperature range of about 100 ° C., the breakage clearly occurred in the cured adhesive layer. Therefore, the addition of CNT is effective. However, if the bonded body is forcibly broken in an environment where the adhesive cured product is softened at a high temperature around 150 ° C., some destruction occurs in the adhesive cured product layer, but most of the adhesive cured product layer itself is It breaks by falling off the rough surface of the metal alloy surface. Therefore, even if CNT is added to the adhesive, the effect of clearly improving the adhesive strength at high temperatures cannot be obtained.

  Here, when the cured epoxy resin cured layers are bonded to each other with an epoxy adhesive, the portion having the weakest bonding force is an interface between the epoxy resin cured layer and a new adhesive cured layer. Even if the surface of the cured epoxy resin layer is roughened to improve the adhesive force, it remains the most easily broken at the interface portion. When such a breakage occurs, there is a possibility that the adhesive force is improved by adding CNT to the epoxy adhesive. At least the addition of CNTs does not reduce the adhesive strength. In this case, it is a three-layer structure in which an adhesive-cured material layer exists between two types of cured epoxy resin layers, which is a sandwich-like structure. When two types of cured epoxy resin layers positioned above and below the cured adhesive layer are pulled up and down respectively, the problem is where the fracture occurs. If the cured adhesive layer is the weakest and rupture occurs inside this layer, the addition of CNT makes the adhesive cured product layer less likely to break itself (prevents the expansion of minute cracks). ) So effective.

  On the other hand, if rupture occurs in the upper or lower epoxy resin cured product layer, even if CNT is added to the epoxy adhesive, there is no effect of improving the adhesive force. From this, when adding CNT to the adhesive II mentioned later, there exists a possibility that an adhesive force may be improved, but even if CNT was added to the adhesive I, it was judged that an adhesive force was not improved. This is because as a result of observing the fracture surface, the fracture often occurred inside the cured product layer of the adhesive II. That is, it was judged that there were many cases where adding CNT to the adhesive I had no effect, and this could be confirmed from the experimental results. Therefore, the addition of CNT to the adhesive I was not a necessary condition. However, when CNT was added to Adhesive II, it was judged that it would work effectively, and when an experiment was conducted, a certain effect was observed in improving the adhesive strength (Table 4).

In the experimental examples to be described later, as a one-component epoxy adhesive used as the adhesive I, in addition to (1) epoxy resin, (2) curing agent, and (3) inorganic filler, (4) ultrafine inorganic filling “A, DICY, 2PI” to which the material was added was prepared (Experimental Example 15 in Table 1).
Furthermore, in addition to (1), (2), (3), and (4), (5) “A, PES, DICY, and 2PI” to which thermoplastic resin powder was added was prepared (Experimental Example 13 in Table 1).
In addition, “PES, DICY, 2PI” was prepared by adding (5) thermoplastic resin powder in addition to (1), (2) and (3) (Experimental Example 14 in Table 1).

[Composition of Adhesive II]
The adhesive II is an adhesive that is applied to the roughened portion of the metal alloy having the roughened adhesive cured layer and the roughened portion of the roughened cured CFRP member. Therefore, it is not necessary to penetrate into the ultra-fine irregularities of the metal alloy having a surface compatible with NAT. That is, since the adhesive II does not need to penetrate into the unevenness of the order of several tens of nm, not only the one-component epoxy adhesive but also the two-component epoxy adhesive may be used.

[One-part epoxy adhesive as Adhesive II]
The one-component epoxy adhesive used as the adhesive II has the same composition as the one-component epoxy adhesive described above. However, since it is not applied to the surface of a metal alloy conforming to NAT, it is not necessary to add an ultrafine inorganic filler. On the other hand, the addition of CNT improved the adhesion. This is based on the reason shown in the explanation of CNT in the adhesive I. The present invention relates to adhesion between a metal alloy and a CFRP member, but this phenomenon (improvement of adhesion by adding CNT) was the same in adhesion between CFRP members. Moreover, it is preferable that the adhesive used as the adhesive II is that whose curing conditions are relaxed for the following reasons.

(Curing agent)
If at least one of the metal alloy or CFRP member to be bonded is a large part, and if the curing temperature of the adhesive used for bonding the two is as high as about 150 ° C., a large autoclave or a large size that can accommodate them as a whole Installation of a hot air dryer is required. Therefore, such a bonding method cannot be adopted when the cost becomes a problem. From such a viewpoint, it is technically important to set the curing temperature of the adhesive II as low as possible. This is because the metal alloy and the CFRP member can be bonded without a large facility.

  In order to be able to perform bonding without requiring large equipment, use a room temperature curing type two-component epoxy adhesive, or heat it with a simple device at the site where the bonding work is performed. A one-part epoxy adhesive that completely cures the adhesive will be used. The present inventors made it possible to stably heat at 100 to 120 ° C. for 1 to 2 hours by winding a band heater around the adhesive application part and heating. In addition, it is possible to stably heat at 100 to 120 ° C. for 1 to 2 hours by installing a container-shaped jig so as to surround the adhesive application part and sending hot air from the hot blaster inside the jig. (FIG. 16). Based on these technologies, trial and error concerning a curing agent and a curing aid were performed in order to develop an adhesive that completely cures at a temperature of 120 ° C. or less and a heating time of 2 hours or less. As a result, the inventors have found that the following combinations of curing agents and curing aids are suitable.

(1) The first combination is a combination of dicyandiamide fine powder as a curing agent and 3- (3,4-dichlorophenyl) -1,1-dimethylurea fine powder as a curing aid. Using this curing agent and curing aid, the adhesive was almost completely cured by heating at 100 ° C. for 1.5 hours.
(2) The second combination is a combination using dicyandiamide fine powder as a curing agent and 1,4-dimethylpiperazine as a curing aid. When this curing agent and curing aid were used, the adhesive was almost completely cured by heating at 110 ° C. for 1 hour.
(3) The third combination is a combination in which dicyandiamide fine powder is used as a curing agent and 2-phenylimidazole or 2-methylimidazole fine powder is used as a curing aid. When this curing agent and curing aid were used, the adhesive was almost completely cured by heating at 120 ° C. for 1 hour.

(Carbon nanotube (2))
In the present invention, when CNT was added as a filler to the adhesive II, the adhesive force was clearly improved (Table 4). Moreover, it showed a high shear breaking force stably. Various manufacturing methods have been developed for CNTs. There are single-walled carbon nanotubes with a diameter of about 1 nm, double-walled carbon nanotubes with a diameter of several nanometers, and triple-walled carbon nanotubes. Then, CNT (multi-walled carbon nanotubes, also abbreviated as “MCNT” for short) having a very large number of layers and having a diameter close to 90 nm can be produced. Although this MCNT has been studied for use in adhesives, no practical examples have been heard yet. On the other hand, practical application utilizing the conductivity of CNTs is progressing. That is, the use as a conductive substance precedes the use as a structural reinforcement. However, in the present invention, attention is paid to physical properties as a structural reinforcing material.

(Dispersion method of carbon nanotube)
The improvement of the adhesive force by addition of CNT mentioned above is achieved when CNT is fully disperse | distributed in an adhesive agent. However, there is a circumstance that the dispersion is actually difficult. Research started immediately after the CNT was expected to increase the adhesive strength and resin strength if mixed with various adhesives and resins. However, a remarkable effect has not yet been recognized. As a result of being able to disperse CNTs in the resin, effects such as a significant improvement in conductivity have been obtained, and while commercialization has been realized for specific applications, the adhesive strength and resin strength that should originally be expected are clearly defined. There are no reports of improvement. The reason is that it is difficult to disperse CNTs.

  Many techniques have already been introduced for the dispersion method of CNTs. Many of these dispersion methods employ a means in which CNT, a special solvent, and a special dispersion stabilizer are added to a ball mill or the like to break and disperse the CNT in the solvent. This is because it was found that the CNTs immediately after production were finely entangled, and in order to be dispersed, it was confirmed that they had to be broken to some extent.

  However, after the solvent and dispersion stabilizer suitable for the dispersion of CNT are used and the adhesive composition and CNT are mixed, the solvent and dispersion stabilizer cannot be completely removed. That is, the solvent component newly added to the adhesive composition may reduce the adhesive performance. In fact, the present inventors also obtained several kinds of solvents and several kinds of dispersion stabilizers used in the above dispersion method, and conducted an experiment in which each was mixed in a one-component epoxy resin adhesive and the adhesive strength was measured. went. As a result, all the adhesive strength decreased.

  For the above reasons, the present inventors tried to develop a new CNT dispersion method. As a result, in the present invention, by using a sand grind mill type wet pulverizer, CNT was successfully dispersed in the epoxy resin without using a solvent or a dispersant. Although described again, there are many methods for producing CNTs, but any method can produce a product in which many individual CNT molecules are entangled. Therefore, using a high-performance wet pulverizer, the entangled CNT molecules in the epoxy resin are destroyed to make the CNT molecules scattered and dispersed.

  However, there are limitations on dispersible CNTs. In the present invention, multilayer CNTs having a diameter of 20 nm or more can be dispersed in an epoxy resin, contributing to an improvement in adhesive strength. The present inventors used the latest sand grind mill type wet pulverizer, but it was difficult to disperse fine CNTs having a diameter of less than 20 nm in the epoxy resin. In the case of a single-layer, two-layer, or three-layer thin CNT having a diameter of about several nanometers, the fibers were too flexible to be broken or dispersed even when a high-performance wet pulverizer was used. On the other hand, CNTs having a diameter of 20 nm or more were dispersible by a sand grind mill, and showed the highest adhesive force particularly when CNTs having a diameter of 40 to 60 nm were added. Such CNTs are commercially available in Japan, and the addition amount is preferably 0.04 to 0.2% by mass of the adhesive.

In the experimental examples to be described later, as the one-component epoxy adhesive used as the adhesive II, (1) epoxy resin, (2) curing agent (dicyandiamide fine powder and 3- (3,4-dichlorophenyl) -1, 1-dimethylurea fine powder), and (3) “MCNT, DICY, DCMU” added with (6) CNT in addition to the inorganic filler (Experimental Example 20 in Table 2).
Furthermore, in addition to (1) (2) (3) (6), (5) “MCNT, hydroxyl group PES, DICY, DCMU” was prepared by adding thermoplastic resin powder (hydroxyl group-containing PES) (Table 2). Experimental Example 21).
In addition, (6) “DICY, DCMU” composed of (1), (2) and (3) was prepared without adding CNT (Experimental Example 22 in Table 2).

In addition to (1) epoxy resin, (2) curing agent (dicyandiamide fine powder and 2-phenylimidazole), and (3) inorganic filler (6) ) “MCNT, DICY, 2PI” to which CNT was added was prepared (Experimental Example 23 in Table 2).
In addition to (1) epoxy resin, (2) curing agent (dicyandiamide fine powder and 1,4-dimethylpiperazine), and (3) inorganic filler as one-component epoxy adhesive used as adhesive II (6) “MCNT, DICY, DMP” to which CNT was added was prepared (Experimental Example 24 in Table 2).

[Two-component epoxy adhesive as adhesive II]
The two-component epoxy adhesive is composed of a main liquid composed of an epoxy resin and a filler, and a curing agent liquid composed of an aliphatic polyamine or acid anhydrides. There are also commercially available adhesives, but the raw materials can be easily obtained from the city and made by yourself. Epoxy resins and fillers (inorganic fillers, ultrafine inorganic fillers, thermoplastic resin powders, and CNTs) used for the two-part epoxy adhesive in the present invention are used as the adhesive II. It is the same as the adhesive.

(Curing agent)
The curing agent is added to the main liquid and used after mixing. Curing agents for two-component epoxy adhesives include chain aliphatic polyamines such as diethylenetriamine, triethylenetetramine, and diethylaminopropylamine, alicyclic polyamines such as mensendiamine, and aromatics such as m-xylylenediamine. Examples include polyamines and modified aliphatic polyamines. Any curing agent can be used, but the curing agent varies depending on what adhesive effect is expected. A chain aliphatic polyamine is preferred for rapid curing at room temperature. On the other hand, there is a curing agent type that takes half day to one day for solidification at room temperature and takes about one week for complete curing. Such a curing agent is completely cured in 1 to 2 hours if the temperature is raised to about 100 ° C. Specifically, alicyclic polyamine, m-xylylenediamine, and the like correspond to this. Adhesion using these curing agents has higher heat resistance than adhesives using a chain aliphatic polyamine as a curing agent.

  In the experimental examples described later, the two-component epoxy adhesive used as the adhesive II includes (1) an epoxy resin, (2) a curing agent (m-xylylenediamine and 2-phenylimidazole), and (3). In addition to the inorganic filler, (6) “MCNT, mXy, 2PI” in which CNT was added was prepared (Experimental Example 25 in Table 2).

[Wet grinding machine]
When fumed silica is added and dispersed in an epoxy resin, it is preferable to use a state-of-the-art wet pulverizer. And as mentioned above, when adding and dispersing CNT in an epoxy resin, it is a necessary condition to use the latest wet pulverizer. In other words, when adding other than CNT and fumed silica, the latest wet pulverizer need not necessarily be used. In fact, with regard to the dispersion of inorganic filler and thermoplastic resin powder, even when using a sand grind mill, which is the latest wet pulverizer, a clear difference can be recognized as compared with kneading with a kneader or automatic mortar. There wasn't. However, judging that there is no problem of a decrease in adhesive force due to insufficient dispersion of the filler, the present inventors decided to disperse all the filler by a sand grind mill. This ensured that the filler was dispersed in the epoxy resin.

  However, even when preparing a one-part epoxy adhesive, the filler should not be mixed and dispersed by applying an epoxy resin with a curing agent added to a sand grind mill. This is the same when the curing temperature is high. Even if the grinding chamber is cooled, the temperature becomes quite high, so when the sand grind mill is operated with a hardener and epoxy resin mixed, a high temperature region is generated in the grinding chamber, which causes gelation and solidification to progress dramatically. This is because there is a risk of running away. This high temperature range can easily occur due to human error or accident. As a result, the expensive sand grind mill is damaged. That is, it is necessary to disperse the filler by applying an epoxy resin added with a filler other than the curing agent to a sand grind mill without adding a curing agent. And a hardening | curing agent and hardening adjuvant are mixed with the epoxy resin after disperse | distributing a filler. For mixing at that time, a kneader or an automatic mortar is used as usual.

[Soaking treatment I and curing of adhesive I]
A one-component epoxy adhesive is applied as the adhesive I to the surface of the metal alloy satisfying the first to third conditions suitable for NAT. Since the cured adhesive layer is polished, it needs to be applied slightly thicker. Specifically, it is preferable that the thickness of the cured adhesive layer is 0.05 mm or more after the adhesive I is cured. If necessary, the metal alloy coated with the adhesive I is put in a container such as a desiccator and sealed, and the inside of the container is once depressurized with a vacuum pump or the like and then returned to normal pressure. Specifically, the inside of the container is depressurized to about several tens of mmHg and left for a certain period of time (approximately several seconds to several minutes), and then air is returned to normal pressure (or pressure is increased to a pressure of several atmospheres or more). preferable. The time in which the pressure is reduced is adjusted according to the degree of penetration of the adhesive I into the ultra-fine irregularities. This depressurization / return to normal pressure operation is preferably repeated several times. It is preferable that the container used for this decompression / normal pressure return operation, for example, a desiccator, is warmed to 50 to 70 ° C. before use. This is to reduce the viscosity of the applied adhesive I so that it can easily penetrate into the ultra-fine irregularities on the surface. By setting the adhesive viscosity of the adhesive I to 15 Pa seconds or less, preferably 10 Pa seconds or less, the ultra fine unevenness is caused to enter. The pressure reduction / normal pressure return operation after applying the adhesive I in this way is referred to as “soaking treatment I”. The metal alloy soaked and treated I is taken out of the container and placed in a hot air dryer to cure the adhesive I.

  Here, when the viscosity of the adhesive I to be applied to the surface of the metal alloy is low (for example, 10 Pa seconds or less), it is not necessary to perform the above-described decompression / normal pressure return operation, and the adhesive I becomes super fine unevenness. Intrusion may occur. In this case, of course, the soaking process I is unnecessary. Further, even if the viscosity of the adhesive I to be applied is high, by warming the metal alloy, the viscosity of the adhesive I may be lowered after the application and may penetrate into the ultra-fine irregularities. In this case, the soaking process I is not necessary. The heating of the metal alloy before the application of the adhesive I and the soaking process I may be performed according to the degree of penetration of the adhesive I into the ultra-fine irregularities.

  All the one-component epoxy adhesives used as the adhesive I in the present invention were cured under the following conditions. First, the inside of the hot air dryer is set to 90 ° C., the metal alloy coated with the adhesive I is put, heated at 90 ° C. for 10 minutes, then heated up to 135 ° C., heated at 135 ° C. for 50 minutes, and then heated up. The temperature was 165 ° C., and the mixture was heated at 165 ° C. for 30 minutes.

[Roughening and cleaning of the cured adhesive layer]
After the adhesive I is cured, the metal alloy is taken out from the hot air dryer, and the cured adhesive layer covering the surface of the metal alloy is roughened. As will be described later, since the CFRP member after curing is also roughened, the cured layer of the adhesive on the metal alloy side where the adhesive II comes into contact with, and the matrix resin (epoxy resin) covering the CFRP member Both of the cured products will be roughened. These roughenings are treatments aimed at allowing the adhesive II to penetrate into the irregularities generated by the roughening.

  Specifically, the surface of the cured adhesive is reciprocally polished 10 to 20 times with the No. 240 to No. 800 polishing paper defined in JIS R6252. In the experimental example to be described later, reciprocal polishing was carried out more than ten times. Since this operation is performed for the purpose of roughening the adhesive layer, polishing is performed so that the metal alloy surface is not exposed due to excessive polishing. This is not a difficult task. The finest abrasive paper that is readily available is No. 2000, and when this abrasive paper is used, it will not be excessively polished even if it is considerably hardened. However, when No. 2000 polishing paper was used, the adhesive strength was inferior to that when No. 240-800 polishing paper was used. That is, the recesses on the surface polished by No. 2000 polishing paper are too shallow and do not contribute to the improvement of the adhesive strength. On the other hand, when No. 80 polishing paper was used, the metal alloy surface was exposed by strongly reciprocating and polishing 10 times. Therefore, 80 is too rough. In the work of the present inventors, preferable results were obtained by using abrasive papers of 240-800.

  The roughened metal alloy is preferably dipped in a so-called degreasing solution in which a surfactant is dissolved in hot water to remove dirt. As the surfactant, various metal degreasing agents can be used, and the use of an aluminum degreasing agent is particularly preferable. It is appropriate to dissolve these in water at a concentration as instructed by the degreasing agent manufacturer, and to use the solution at the temperature specified by the manufacturer. At this time, it is better to apply ultrasonic waves. The inventors set the commercially available degreasing agent for aluminum to a concentration and liquid temperature (60 ° C.) as instructed by the manufacturer, and immersed the roughened metal alloy for 5 minutes while applying ultrasonic waves thereto. Subsequently, it washed with water and dried with the warm air dryer which was 80 degreeC. Tests were performed using ion-exchanged water, industrial water, and tap water as flush water, but there was no difference in adhesive strength when any of them was used. However, since industrial water may be mixed with river water, tap water or ion-exchanged water is preferably used.

  Moreover, equivalent cleaning is possible without using a degreasing agent as described above. By applying high-pressure running water to the roughened portion, dirt could be removed without using a surfactant, and an adhesive force close to that obtained when a surfactant was used could be obtained. This was verified by experiment. Specifically, sufficient cleaning can be achieved by making tap water into a thin rod flow with its water pressure applied to a roughened portion. This cleaning method is effective when the metal alloy does not completely enter the degreasing tank. It is only necessary to perform cleaning with running water only on the roughened area of the metal alloy. No special equipment is required and can be easily cleaned. However, since the degreasing layer is usually used for the surface treatment of the metal alloy, the use of the degreasing layer is not a burden if the same material is used.

[About CFRP]
FRP whose carbon fiber is reinforced fiber is CFRP, the one using glass fiber is GFRP (short for Glass-fiber reinforced plastics), and the one using aramid fiber is AFRP (short for Aramid-fiber reinforced plastics). And KFRP (Kevler-fiber reinforced plastics). FRP is also a generic name for these. Although the present invention discusses FRP using an epoxy resin as a matrix resin, CFRP is generally used as the FRP using an epoxy resin as a matrix resin. Therefore, a CFRP member will be described below.

  In general, the shaped CFRP is a product obtained by heat-curing a multilayer CFRP prepreg while being compressed by an overlapping jig or the like. In particular, a prepreg utilization method is standard as a high-strength CFRP production method, which will be described. Past CFRP prepregs used a sticky liquid thermosetting epoxy resin similar to the current adhesive for the matrix resin. Therefore, it is a sticky sheet-like material, supplied as a sheet sandwiched between polyethylene films and the like, cut as it is in use, and then peeled off and used the polyethylene film. However, the current prepreg is a non-adhesive sheet because it sometimes uses a large amount of aromatic diamine as a curing agent to increase the heat resistance of the cured product. There are many 0.2mm thick products, which are standardized and easy to use.

  The manufacturing process of the CFRP member is automated so that the three-dimensional shape becomes an expected one by cutting the prepreg while changing the shape one by one with a computer-controlled automatic cutting machine and stacking the cut pieces. The laminate is placed in a jig so that the shape can be maintained, and then tightened with bolts or springs so that pressure is applied between the prepreg sheets, and the whole is put in a sealed bag or an autoclave and sealed and decompressed. When the temperature is raised with the pressure reduced, it once melts and then gelation and curing begin. On the contrary, when the pressure is increased after melting, the gap where the air that has escaped from between the prepregs is crushed and the integration proceeds. When the curing is completed, the product is allowed to cool, and a jig or the like is removed to complete the CFRP member.

[Refiring of CFRP members]
The present inventors cut a small piece of 45 mm × 15 mm from a commercially available prepreg to produce a large number of prepreg pieces. These were laminated to a thickness of 3 mm and cured under curing conditions (temperature, time) specified by the manufacturer to obtain CFRP pieces. This is called a once-baked product. The once-baked product was heated again at a high temperature (a maximum of 180 to 190 ° C.) higher than the temperature necessary for curing. That is, refiring was performed. This is called a twice-baked product. Further, the twice-baked product was heated again under the same conditions. This is called a three-time baked product. A plurality of bonded CFRP pieces in which the single-baked products were bonded to each other with a one-component epoxy adhesive by a co-bonding method were obtained. Similarly, a plurality of joined bodies each obtained by bonding two-baked products and three-baked products with a one-component epoxy adhesive were obtained. In the CFRP pieces used by the present inventors, the average shear fracture strength at room temperature was high in the double-baked product and the triple-baked product, and the single-baked product was clearly low. This indicates that the adhesive strength between the carbon fiber and the matrix resin is improved by re-baking at a high temperature.

  The idea of improving the adhesive force between matrix resin and carbon fiber by reheating has not been made so far. Conventionally, there is no technique for bonding a CFRP member and a metal alloy with an extremely strong adhesive force (adhesive strength showing a shear breaking force of 50 MPa or more) as in the present invention, and between a matrix resin and a carbon fiber. This is because there was almost no fact that peeling occurred. That is, it can be said that the necessity of improving the adhesive force between the matrix resin and the carbon fiber did not occur. However, as described above, the adhesive technology developed by the present inventors has resulted in an extremely high adhesive force between the cured matrix resin and the cured adhesive on the surface of the CFRP member. A situation has occurred where the adhesive strength between the cured matrix resin and the carbon fiber is exceeded. As a result, there was a problem in that peeling occurred first between the cured matrix resin and the carbon fiber at the time of breakage, and this appeared as a low adhesive force, so the necessity to increase the adhesive force between the two occurred. . Therefore, it is preferable to perform not only reheating but also a treatment for increasing the adhesive force between the cured matrix resin and the carbon fiber.

  The present inventors use a one-component epoxy adhesive for the one-time baked product, the two-time baked product, and the three-time baked product of the CFRP piece prepared in Experimental Example 18 to be described later, and conform to NAT. A CFRP / A7075 composite was obtained by bonding with an aluminum alloy “A7075” having a surface shape and a surface structure. When the shear breaking force was measured for each composite, the average of the single-baked product / A7075 composite was 49.0 MPa, the average of the double-baked product / A7075 composite was 58.8 MPa, and the average of the triple-baked product / A7075 composite was 62.5 MPa. From this example and the example of bonding between the above-mentioned CFRP pieces (the result that the adhesive strength of the double-baked product and the triple-baked product is high), it is preferable to reheat the cured CFRP member. Then, the CFRP member whose adhesion between the carbon fiber and the matrix resin is improved by re-firing is used to bond the metal alloy.

[Roughening and cleaning of CFRP members]
Since the cured surface of the matrix resin covers the surface of the CFRP member, the CFRP member itself is a cured epoxy resin as viewed from the surface. Therefore, the roughening of the CFRP member surface can be performed in the same manner as the roughening of the cured adhesive layer on the metal alloy surface described above. As a result of trial and error by the present inventors, the surface of the CFRP member polished with a slightly coarse abrasive paper of No. 80 to No. 480, preferably No. 120 to No. 240 defined in JIS R6252, is stable. It became an adherend exhibiting high adhesive strength. However, the appropriate level of roughness of the abrasive paper depends on the composition of the matrix resin, and should be determined by trial and error while measuring the adhesion between the final metal alloy and the CFRP member. .

  The roughened CFRP member is preferably cleaned by immersing it in a so-called degreasing solution in which a surfactant is dissolved in hot water. As the surfactant, various metal degreasing agents can be used, and the use of an aluminum degreasing agent is particularly preferable. It is appropriate to dissolve these in water at a concentration as instructed by the degreasing agent manufacturer, and to use the solution at the temperature specified by the manufacturer. At this time, it is better to apply ultrasonic waves. The inventors set the commercially available aluminum degreasing agent to a concentration and liquid temperature (60 ° C.) according to the manufacturer's instructions, and immersed the roughened CFRP member for 5 minutes while applying ultrasonic waves thereto. Subsequently, it washed with water and dried with the warm air dryer which was 80 degreeC. Tests were performed using ion-exchanged water, industrial water, and tap water as flush water, but there was no difference in adhesive strength when any of them was used. However, since industrial water may be mixed with river water, tap water or ion-exchanged water is preferably used.

  Moreover, equivalent cleaning is possible without using a degreasing agent as described above. By applying high-pressure running water to the roughened portion, it was possible to remove dirt without using a surfactant, and it was possible to obtain an adhesive force equivalent to that obtained when a surfactant was used. This was verified by experiment. Specifically, sufficient cleaning can be achieved by making tap water into a thin rod flow with its water pressure applied to a roughened portion. This cleaning method is effective when the CFRP member does not fully enter the degreasing tank. There are many cases where large CFRP members are bonded to small metal alloys. In this case, only the roughened area of the CFRP member is washed with running water without using a large degreasing tank. Just do it. No special equipment is required and can be easily cleaned.

[Adhesion between metal alloy and CFRP member]
Both the metal alloy having a roughened adhesive-cured material layer and the CFRP member having a roughened surface are bonded by an adhesive II. As the adhesive II, either a one-component epoxy adhesive or a two-component epoxy adhesive can be used.

(Adhesion method using one-component epoxy adhesive)
A one-component epoxy adhesive as an epoxy adhesive II at a predetermined position on each of a roughened metal alloy adhesive cured layer and a roughened matrix resin covering the surface of a CFRP member. Apply. Brush painting or spatula painting may be used. If necessary, the metal alloy coated with the adhesive II and CFRP are placed in a container such as a desiccator and sealed, and the inside of the container is once depressurized with a vacuum pump or the like, and then returned to normal pressure. Specifically, the inside of the container is depressurized to about several tens of mmHg and left for a certain period of time (approximately several seconds to several minutes), and then air is returned to normal pressure (or pressure is increased to a pressure of several atmospheres or more). preferable. The time for placing the pressure-reduced state is adjusted according to the degree of intrusion into the irregularities related to the roughened portion of the adhesive II. The decompression / normal pressure return operation after the application of the epoxy resin II is referred to as “soaking treatment II”. The impregnation treatment II is intended to cause the adhesive II to penetrate into the irregularities of the cured adhesive layer produced by the roughening, and to cause the adhesive II to penetrate into the irregularities of the CFRP member surface caused by the roughening. . That is, the adhesive II, which is an epoxy adhesive, is impregnated into the cured epoxy resin layer covering the metal alloy and the cured epoxy resin obtained by curing the CFRP matrix resin. When the viscosity of the adhesive II after mixing the curing agent is as high as several tens of Pa seconds or more, the container that is soaked and used for the treatment II is heated to 50 to 70 ° C. in advance. Thereby, the viscosity of the epoxy adhesive II is set to 15 Pa seconds or less, preferably 10 Pa seconds or less.

  The metal alloy and CFRP member soaked and treated II are taken out from the containers and bonded together. It fixes with a clip in the state which adhered both adhesive application ranges. If the clip cannot be fixed, fix it with a jig that applies pressure to the bonding surface. When storing and fixing in a jig or the like without using a clip, gravity, a spring, a clamp, or the like is used as the pressing force. The adhesive is heat-cured using a hot air dryer or an autoclave while both are fixed. When curing by heating to about 120 ° C. or lower using a band heater or a hot blaster at the bonding site, a simple curing method shown in FIG. 16 is used.

(Adhesion method using two-component epoxy adhesive)
A two-part epoxy adhesive is prepared by adding a curing agent to the main liquid in which the filler is dispersed and kneading the mixture well. A two-component epoxy adhesive as an epoxy adhesive II at a predetermined location on each of a roughened metal alloy adhesive hardened layer and a roughened matrix resin hardened material covering the surface of a CFRP member. Apply. After that, the same impregnation treatment II as that of the one-component epoxy adhesive is performed. Note that in the case of a two-part epoxy adhesive, work is performed at room temperature after adding a curing agent, and the process II is completed within 4 hours, preferably within 1 hour after the addition. To do. Work should not be interrupted along the way. In the case of a two-component epoxy adhesive, since the viscosity after kneading is not so high, it is not necessary to soak the container used for the treatment II.

  The metal alloy and CFRP member soaked and treated II are taken out from the containers and bonded together. It fixes with a clip in the state which adhered both adhesive application ranges. If the clip cannot be fixed, fix it with a jig that applies pressure to the bonding surface. When storing and fixing in a jig or the like without using a clip, gravity, a spring, a clamp, or the like is used as the pressing force. When a two-component epoxy adhesive is used, the clamp can be removed in about 24 hours at room temperature, and is completely cured in at least one week to 10 days. If the operation of heating to 100 to 110 ° C. is performed instead of leaving it at room temperature, it can be almost completely cured in 1 to 2 hours.

(About soaking process II)
Here, when the viscosity of the adhesive II to be applied to the cured adhesive layer and the CFRP member is low (for example, 15 Pa seconds or less), there is no need to perform the above-described decompression / normal pressure return operation, and the adhesive II May intrude into the irregularities of the roughened portion. In this case, naturally, the soaking process II is unnecessary. Moreover, even if the viscosity of the adhesive II to be applied is high, by warming the metal alloy and the CFRP member, the viscosity of the adhesive II may decrease after application and penetrate into the irregularities of the roughened portion. is there. In this case, the soaking process II is not necessary. The heating of the metal alloy and the CFRP member before the application of the adhesive II and the soaking process II may be performed according to the degree of penetration of the adhesive II into the unevenness. Since the roughened portion of the cured adhesive layer and the CFRP member has a surface rougher than the ultra fine unevenness in the treatment I, the importance of the soaking treatment II is infiltrated and does not reach the processing I. When a two-component epoxy adhesive is used as the adhesive II, the curing agent is a low-viscosity liquid and the amount of addition increases, so that the adhesive itself has a low viscosity. Therefore, the effect of the impregnation treatment II is small as compared with the one-component epoxy adhesive.

(Simple curing method for adhesive)
In general, the CFRP member is large and has a simple shape. This is because it is often used for the purpose of reducing the weight of large-sized parts, and manufacturing is facilitated by adopting a simple shape in consideration of the lamination of prepregs. On the other hand, metal alloys are suitable for processing complicated shapes. Therefore, there is a demand for firmly bonding a small metal alloy component to a large CFRP member.

  FIG. 16 is an apparatus for bonding a large CFRP plate material 50 and a small metal alloy component 51 without using a hot air dryer. An adhesive is applied to the top surface (roughened) of the CFRP plate material 50 and the bottom surface (roughened) of the metal alloy component 51, and after soaking and processing, the two are brought into close contact with each other. The adhesive layer is shown as 52. The CFRP plate member 50 is provided with a plurality of holes 53 penetrating the top and bottom surfaces. The metal alloy component 51 is also provided with a plurality of holes 54 penetrating up and down the edge. By passing the wire 55 through the hole 53 and the hole 54, the CFRP plate material 50 and the metal alloy component 51 are fixed. The wire 55 is a stainless steel wire having a diameter of about 1 mm. The wire 55 is curved and fixed on the upper surface side of the edge of the metal alloy component 51. On the other hand, the upper end of the spring material 56 is fixed to the bottom surface of the CFRP plate material 50, and the lower end of the spring material 56 is fixed to the upper surface of the plate material 57. The plate material 57 is also provided with a plurality of holes 58 through which the wire 55 passes, and the wire 55 that has passed through the holes 54 and 53 passes through the hole 58 and is fixed by being bent on the bottom surface side of the plate material 57. Has been. At this time, the spring material 56 is contracted more than usual. As a result, the metal alloy component 51 is pressed against the CFRP plate 50 by the spring pressure of the spring material 56.

  Further, the adhesive layer 52 is enclosed by the rubber cover 60. A thermocouple 61 is inserted from a window provided in the cover 60. The cover 60 is provided with a large air hole 62, and an air outlet 63 is also provided on the opposite side. The edge of the cover 60 is fixed with a fixing weight (not shown). Hot air near 200 ° C. is blown from a hot blaster 64 close to the air hole 62. As a result, the adhesive layer 52 is cured. Here, when heat cannot be stably heated due to heat radiation from the bottom surface side of the CFRP plate material 50, a heat insulating cover 70 may be provided on the back surface side. A vacuum cock 71 is installed on the top of the heat insulating cover 70, and this vacuum cock 71 is connected to a vacuum line 72. By these, the part covered with the heat insulating cover 70 can be depressurized, and the heat insulating cover 70 sticks to the back surface side of the CFRP plate member 50 by this depressurization, and heat dissipation is suppressed. Thus, temperature control is performed by the combination of the thermocouple 61 and the hot blaster 64, and heating at about 100 to 120 ° C. for about 1 to 2 hours is enabled.

[Measurement of adhesive strength]
The composite of a metal alloy and a CFRP member is obtained by the above method. In an experimental example to be described later, a composite 30 of the metal alloy piece 31 and the CFRP piece 32 shown in FIG. 14 was obtained. This is a test piece. Both ends of this composite were pulled and broken with a tensile tester, and the obtained breaking force was divided by the adhesion area to measure the shear breaking force (MPa (Kgf / cm ² )).

  According to the present invention, a metal alloy and CFRP can be bonded extremely firmly. In the present invention, a co-bonding method in which CFRP after curing is bonded to a metal alloy is employed. In particular, the co-bonding method of the present invention is suitable for a small quantity product that requires high reliability, such as an aircraft or a competitive vehicle, in order to stably exhibit high adhesive strength. In addition, by adopting the cobond method, it is possible to diversify the manufacturing process of the composite of the metal alloy and CFRP. Specifically, it is also possible to perform all three steps, that is, application of an adhesive to a metal alloy, curing of CFRP, and adhesion of the metal alloy and CFRP at another factory. In addition, storage and distribution in the state of the intermediate material are facilitated by using the metal alloy having the cured adhesive layer and the CFRP after curing as the intermediate material.

  More specifically, an epoxy adhesive is applied to a metal alloy and cured, and after the surface of the cured adhesive layer is roughened, the product washed with water and dried can be stored for a long period of time if it is covered with a film. And can be easily transported in this state. In addition, the CFRP (that is, the CFRP member) after curing is roughened, washed with water, and dried, and can be stored for a long period of time if it is covered with a film, and transportation in this state is easy. In this respect, the intermediate material can be easily stored and distributed.

  On the other hand, when a metal alloy and CFRP are bonded by a cocure method, a one-component epoxy adhesive is applied to the surface of a metal alloy that conforms to NAT, and is soaked and processed. Then, a CFRP prepreg is laminated in a range where the one-component epoxy adhesive on the surface of the metal alloy is applied, and the whole is heated. As a result, the curing of the one-component epoxy adhesive and the curing of CFRP are achieved at the same time. In order to go through such a process, when applying the adhesive to the metal alloy and bonding the metal alloy and CFRP in another factory, the metal alloy that has been soaked and processed is stored at room temperature or lower. Must. In addition, when transporting the metal alloy to a factory that bonds with CFRP, a refrigerated vehicle is required for transport in summer to keep it below room temperature, and the temperature during storage and storage until final bonding work is performed. You must keep in mind. Further, in this case, since the adhesive is in a state before curing and has a viscosity, care must be taken in handling. If the cocure method is adopted, a metal alloy having a surface conforming to NAT is transported in a state where no adhesive is applied, and the adhesive is applied when the final bonding operation with the CFRP member is performed. However, there are the following problems. First, the metal alloy surface conforming to NAT is chemically stable, but the ultra-fine irregularities are as small as several tens of nanometers. The effect is completely lost. Therefore, when storing and distributing such a metal alloy on the surface, it is necessary to store and distribute it in a complete packing form so as not to come into contact with it and to prevent fine dust from adhering. Further, if the final adhering operation must be soaked and processed, it is not suitable for the case where it is desired to simplify the final adhering operation as much as possible (for example, when manufacturing a composite in a foreign factory).

  From such a point, the problem of the cocure method was solved by adopting the cobond method of the present invention. By storing and distributing the surface of the metal alloy that conforms to NAT in a state where it is covered with the cured adhesive layer, the complexity of management can be avoided and the final process can be simplified. In addition, since the CFRP is circulated in a cured state, the final process can be simplified.

  In the present invention, the heat resistance can be improved by adding an ultrafine inorganic filler (fumed silica) to the one-component epoxy adhesive applied to the metal alloy surface. In the present invention, the adhesive force is improved by adding CNT to the second adhesive for bonding the metal alloy and CFRP. Moreover, since the second adhesive can be cured at a low temperature of 120 ° C. or less and a heating time of 2 hours or less, the bonding equipment can be simplified. Further, a two-component epoxy adhesive can be used as the second adhesive. In this case, complete curing can be achieved even by heating at a low temperature for a short time, but there is also an advantage that no curing equipment is required because the adhesive is completely cured by leaving it at room temperature.

  The present invention can be applied to a fiber reinforced plastic using an epoxy resin as a matrix resin. Therefore, the present invention can be applied to GFRP (abbreviation of Glass Fiber Reinforced Plastics), which is not limited to CFRP, but the reinforcing fiber is glass fiber, and the matrix resin is epoxy resin. The present invention can also be applied to KFRP (abbreviation of Kevlar Fiber Reinforced Plastics) and AFRP (abbreviation of Aramid Fiber Reinforced Plastics) in which the fiber is an aramid fiber and the matrix resin is an epoxy resin. In addition, the present invention is not limited to a CFRP member in which prepregs are laminated, and can also be applied to a CFRP member obtained by a filament winding method. This is because the matrix resin is still an epoxy resin.

FIG. 1 is an electron micrograph ((a): 10,000 times, (b): 100,000 times) of a surface obtained by chemically etching an A7075 aluminum alloy with a caustic soda aqueous solution and finely etching with a hydrated hydrazine aqueous solution. FIG. 2 is an electron micrograph ((a): 10,000 times, (b): 100,000 times) of a surface obtained by chemically etching an A5052 aluminum alloy with an aqueous caustic soda solution and finely etching with an aqueous hydrazine solution. FIG. 3 is a 100,000 times electron micrograph (100% magnification of (a) and (b)) of a surface obtained by chemically etching an AZ31B magnesium alloy with a citric acid aqueous solution and chemical conversion treatment with a potassium permanganate aqueous solution. FIG. 4 is an electron micrograph of a surface obtained by chemically etching a C1100 copper alloy with an aqueous solution of sulfuric acid and hydrogen peroxide and surface-treating with an aqueous solution of sodium chlorite ((a): 10,000 times, (b): 100,000 times) ). FIG. 5 is an electron micrograph ((a): 10,000 times, (b): 100,000) of a surface obtained by chemically etching a C5191 phosphor bronze alloy with sulfuric acid / hydrogen peroxide aqueous solution and surface hardening treatment with sodium chlorite aqueous solution. Times). Fig. 6 shows electron micrographs of the surface of KFC copper alloy chemically etched with sulfuric acid / hydrogen peroxide solution and surface hardened with sodium chlorite solution ((a): 10,000 times, (b): 100,000 times) ). FIG. 7 is an electron micrograph of a surface obtained by chemically etching a KLF5 copper alloy with sulfuric acid / hydrogen peroxide aqueous solution and surface-hardening with sodium chlorite aqueous solution ((a): 10,000 times, (b): 100,000 times) ). FIG. 8 is an electron micrograph ((a): 10,000 times, (b): 100,000 times) of a surface obtained by chemically etching a KS40 pure titanium-based titanium alloy with an aqueous hydrogen difluoride ammonium solution. FIG. 9 is an electron micrograph ((a): 10,000 times, (b): 100,000 times) of a surface obtained by chemically etching a KSTi-9α-β titanium alloy with an aqueous solution of 1 hydrogen difluoride ammonium fluoride. FIG. 10 is an electron micrograph ((a): 10,000 times, (b): 100,000 times) of a surface obtained by chemically etching SUS304 stainless steel with a sulfuric acid aqueous solution. FIG. 11 is an electron micrograph ((a): 10,000 times, (b): 100,000 times) of a surface obtained by etching a SPCC cold rolled steel material with a sulfuric acid aqueous solution. FIG. 12 is an electron micrograph ((a): 10,000 times, (b): 100,000 times) of the surface of SPHC hot-rolled steel material etched with a sulfuric acid aqueous solution. FIG. 13 is a cross-sectional view of a firing jig for making CFRP pieces by overlapping CFRP prepregs and curing them in a hot air dryer. FIG. 14 shows a test piece obtained by bonding a metal alloy piece and a CFRP piece. FIG. 15 is a schematic cross-sectional view showing a surface structure when a metal alloy and a one-component epoxy adhesive are joined. FIG. 16 is a cross-sectional view showing the structure of an apparatus for curing an adhesive without using a hot air dryer.

Hereinafter, embodiments of the present invention will be described by experimental examples.
The equipment used for measurement etc. is shown below.
(A) X-ray surface observation (XPS observation)
An ESCA “AXIS-Nova (Kraitos (USA) / Shimadzu Corporation (Kyoto Prefecture, Japan))” that observes constituent elements on a surface having a diameter of several μm in a depth range of 1 to 2 nm was used.
(B) Electron microscope observation Using SEM type electron microscopes “S-4800 (manufactured by Hitachi, Ltd.)” and “JSM-6700F (manufactured by JEOL Ltd. (Tokyo, Japan))” at 1-2 KV Observed.
(C) Scanning Probe Microscope Observation A dynamic force scanning probe microscope “SPM-9600 (manufactured by Shimadzu Corporation)” was used.
(D) X-ray diffraction analysis (XRD analysis)
“XRD-6100 (manufactured by Shimadzu Corporation)” was used.
(E) Measurement of joint strength of composites Using a tensile tester “AG-10kNX (manufactured by Shimadzu Corporation)”, the shear breaking strength was measured at a pulling speed of 10 mm / min.
(F) Dispersion of filler (use of wet pulverizer)
A sand grind mill “Minitsu Air (manufactured by Ashizawa Finetech Co., Ltd.)” using zirconia beads having a diameter of 0.1 to 0.5 mm as sand was used.
Next, the surface treatment of the metal alloy will be described.

[Experimental Example 1] (A7075 aluminum alloy piece surface treatment)
A commercially available aluminum alloy sheet “A7075” having a thickness of 3 mm was obtained and cut to produce a large number of 45 mm × 15 mm rectangular A7075 pieces. A commercially available aluminum alloy degreasing agent “NE-6 (manufactured by Meltex Co., Ltd. (Tokyo, Japan))” was added to the water in the tank to prepare an aqueous solution (60 ° C.) having a concentration of 7.5%. The A7075 pieces were immersed in this for 7 minutes and washed thoroughly with water. Subsequently, a 1% hydrochloric acid aqueous solution (40 ° C.) was prepared in another tank, and the A7075 piece was immersed in the tank for 1 minute and washed with water. Next, a 1.5% strength aqueous caustic soda solution (40 ° C.) was prepared in another tank, and the A7075 pieces were immersed in this for 4 minutes and washed with water. Subsequently, a 3% nitric acid aqueous solution (40 ° C.) was prepared in another tank, and the A7075 pieces were immersed in the tank for 1 minute and washed with water. Next, an aqueous solution (60 ° C.) containing 3.5% monohydric hydrazine was prepared in another tank, and the A7075 pieces were immersed in this for 2 minutes and washed with water. Next, a 5% hydrogen peroxide aqueous solution (40 ° C.) was prepared, and the A7075 piece was immersed in the solution for 5 minutes and washed with water. Next, the A7075 pieces were dried in a hot air dryer at 67 ° C. for 15 minutes.

  When the A7075 piece treated in the same manner as described above was observed with an electron microscope, it was found that the A7075 piece was covered with a recess having a diameter of 40 to 100 nm. A photograph of the electron microscope observed at 10,000 times and 100,000 times is shown in FIG. 1 ((a): 10,000 times, (b): 100,000 times). The roughness data was obtained by scanning probe microscope. According to this, RSm was 3-4 μm, and Rz was 1-2 μm.

[Experimental Example 2] (Surface treatment of A5052 aluminum alloy piece)
A commercially available 1.6 mm-thick aluminum alloy sheet “A5052” was obtained and cut to produce a large number of 45 mm × 15 mm rectangular A5052 pieces. A commercially available degreasing agent “NE-6” for aluminum alloy was added to the water in the tank to prepare an aqueous solution (60 ° C.) having a concentration of 7.5%. The A5052 piece was immersed in this for 7 minutes and washed thoroughly with water. Subsequently, a 1% hydrochloric acid aqueous solution (40 ° C.) was prepared in another tank, and the A5052 pieces were immersed in this for 1 minute and washed with water. Next, a 1.5% strength aqueous sodium hydroxide solution (40 ° C.) was prepared in another tank, and the A5052 pieces were immersed in this for 2 minutes and washed with water. Subsequently, a 3% nitric acid aqueous solution (40 ° C.) was prepared in another tank, and the A5052 pieces were immersed in this for 1 minute and washed with water. Next, an aqueous solution (60 ° C.) containing 3.5% monohydric hydrazine was prepared in another tank, and the A5052 pieces were immersed in this for 2 minutes and washed with water. Next, the A5052 pieces were dried in a hot air dryer set at 67 ° C. for 15 minutes.

  When the A5052 piece treated in the same manner as described above was observed with an electron microscope, it was found that the A5052 piece was covered with a recess having a diameter of 30 to 100 nm. A photograph when the electron microscope is observed at 10,000 times and 100,000 times is shown in FIG. 2 ((a): 10,000 times, (b): 100,000 times). The roughness data was obtained by scanning probe microscope. According to this, RSm was 2.0 to 3.4 μm, and Rz was 0.2 to 0.5 μm.

[Experimental Example 3] (Surface treatment of AZ31B magnesium alloy piece)
A commercially available magnesium alloy sheet “AZ31B” having a thickness of 1 mm was obtained and cut to produce a large number of 45 mm × 15 mm rectangular AZ31B pieces. A commercially available magnesium alloy degreasing agent “Cleaner 160 (manufactured by Meltex Co., Ltd.)” was added to the water in the tank to prepare an aqueous solution (65 ° C.) having a concentration of 7.5%. The AZ31B piece was immersed in this for 5 minutes and washed thoroughly with water. Subsequently, a 1% strength aqueous hydrated citric acid solution (40 ° C.) was prepared in another tank, and the AZ31B piece was dipped in this for 6 minutes and washed with water. Next, an aqueous solution (65 ° C.) containing 1% concentration sodium carbonate and 1% concentration sodium hydrogen carbonate was prepared in another tank, and the AZ31B piece was immersed in this for 5 minutes and washed with water. Subsequently, a 15% strength aqueous caustic soda solution (65 ° C.) was prepared in another tank, and the AZ31B piece was immersed in this for 5 minutes and washed with water. Next, a 0.25% strength aqueous hydrated citric acid solution (40 ° C.) was prepared in another tank, and the AZ31B piece was immersed in this for 1 minute and washed with water. Next, an aqueous solution (45 ° C.) containing 2% potassium permanganate, 1% acetic acid and 0.5% hydrated sodium acetate was prepared, and the AZ31B piece was immersed in this for 1 minute and washed with water for 15 seconds. Next, the AZ31B piece was placed in a hot air dryer set at 90 ° C. for 15 minutes and dried.

  When the AZ31B piece treated in the same manner as described above was observed with an electron microscope, 5 to 20 nm diameter rod-shaped crystals were intertwined into a lump with a diameter of about 100 nm, and the lump was covered with a super fine uneven shape forming a surface. There was a place. 3A and 3B show photographs when the electron microscope is observed at a magnification of 100,000. Further, when the roughness was observed by scanning with a scanning probe microscope, RSm was 2 to 3 μm and Rz was 1 to 1.5 μm.

[Experimental Example 4] (Surface treatment of C1100 copper alloy piece)
A commercially available tough pitch copper plate material “C1100”, which is a pure copper-based copper alloy with a thickness of 1.5 mm, was obtained and cut to create a large number of 45 mm × 15 mm rectangular C1100 pieces. An aqueous solution (60 ° C.) containing 7.5% of a commercially available aluminum alloy degreasing agent “NE-6” was prepared in a tank, and the C1100 pieces were immersed in this for 5 minutes and washed with water. Next, the base was washed by immersing the C1100 piece in a 1.5% strength aqueous caustic soda solution (40 ° C.) for 1 minute and washing with water. Next, an aqueous solution (25 ° C.) containing 20% of an etching material for copper alloy “CB-5002 (MEC Co., Ltd., Hyogo, Japan)” and 18% of 30% hydrogen peroxide was prepared as an aqueous solution for etching. The C1100 piece was immersed in 10 minutes and washed with water. Next, an aqueous solution (65 ° C.) containing 10% caustic soda and 5% sodium chlorite was prepared as an oxidizing aqueous solution in another tank, and the C1100 pieces were immersed in this for 1 minute and washed with water. Next, the C1100 piece was again immersed in the aqueous solution for etching for 1 minute and washed with water, then immersed in the aqueous solution for oxidation for 1 minute, and thoroughly washed with water. Thereafter, the C1100 piece was placed in a warm air dryer at 90 ° C. for 15 minutes and dried.

  A piece of C1100 treated in the same manner as described above was applied to a scanning probe microscope. As a result, RSm was 3 to 7 μm, and Rz was 3 to 5 μm. A photograph of the electron microscope observed at 10,000 times and 100,000 times is shown in FIG. 4 ((a): 10,000 times, (b): 100,000 times). When observed with an electron microscope of 100,000 times, the hole or opening having a diameter or an average of a major axis and a minor axis having an average of 10 to 150 nm is covered with an ultrafine irregular shape having irregular intervals of 30 to 300 nm. It was broken.

[Experimental Example 5] (Surface treatment of C5191 copper alloy piece)
A commercially available phosphor bronze plate material “C5191” having a thickness of 1 mm was obtained and cut to produce a large number of rectangular C5191 pieces of 45 mm × 15 mm. An aqueous solution (60 ° C.) containing 7.5% of a commercially available aluminum alloy degreasing agent “NE-6” was prepared in a tank, and this was used as a degreasing aqueous solution. The C5191 piece was immersed in this degreasing aqueous solution for 5 minutes for degreasing and thoroughly washed with water. Subsequently, an aqueous solution (25 ° C.) containing 20% of the copper alloy etching material “CB-5002” and 18% of 30% hydrogen peroxide was prepared as an aqueous solution for etching in another tank, and the C5191 piece was added thereto. Was immersed for 15 minutes and washed with water. Next, an aqueous solution (65 ° C.) containing 10% caustic soda and 5% sodium chlorite was prepared as an oxidizing aqueous solution in another tank, and the C5191 pieces were immersed in this for 1 minute and washed with water. Next, the C5191 piece was again immersed in the etching aqueous solution for 1 minute and washed with water, and then immersed in the oxidizing aqueous solution for 1 minute and washed with water. Thereafter, the C5191 pieces were placed in a hot air dryer at 90 ° C. for 15 minutes and dried.

  A C5191 piece treated in the same manner as described above was applied to a scanning probe microscope. As a result, RSm was 1 to 3 μm and Rz was 0.3 to 0.4 μm. A photograph when the electron microscope is observed at 10,000 times and 100,000 times is shown in FIG. 5 ((a): 10,000 times, (b): 100,000 times). When observed with a 100,000-fold electron microscope, a convex or concave portion having an average diameter or major axis and minor axis of 10 to 200 nm is mixed and is present on the entire surface. What is the microstructure of tough pitch copper that is pure copper? It was a completely different shape.

[Experimental Example 6] (Surface treatment of KFC copper alloy piece)
A commercially available iron-containing copper alloy sheet “KFC (manufactured by Kobe Steel, Ltd.)” having a thickness of 0.9 mm was obtained and cut to prepare a large number of 45 mm × 15 mm rectangular KFC pieces. An aqueous solution (60 ° C.) containing 7.5% of a commercially available aluminum alloy degreasing agent “NE-6” was prepared in a tank, and the KFC pieces were immersed in this for 5 minutes and washed with water. Next, the KFC pieces were immersed in a 1.5% strength aqueous caustic soda solution (40 ° C.) for 1 minute and washed with water to perform preliminary base washing. Next, an aqueous solution (25 ° C.) containing 20% of an etching material for copper alloy “CB5002” and 18% of 30% hydrogen peroxide is prepared as an aqueous solution for etching. The KFC piece is immersed in this for 8 minutes and washed with water. did. Next, an aqueous solution (65 ° C.) containing 10% caustic soda and 5% sodium chlorite was prepared as an oxidizing aqueous solution in another tank, and the KFC pieces were immersed in this for 1 minute and washed with water. Next, the KFC piece was again immersed in the etching aqueous solution for 1 minute and washed with water, and then immersed in the oxidizing aqueous solution for 1 minute and washed with water. Thereafter, the KFC pieces were placed in a hot air dryer at 90 ° C. for 15 minutes and dried.

  A KFC piece treated in the same manner as described above was applied to a scanning probe microscope. As a result, RSm was 1 to 3 μm and Rz was 0.3 to 0.5 μm. The photograph when observing the electron microscope at 10,000 times and 100,000 times is shown in FIG. 6 ((a): 10,000 times, (b): 100,000 times). When observed with a 100,000-fold electron microscope, the entire surface was covered with an ultrafine uneven shape in which convex portions having an average diameter or major axis and minor axis of 10 to 200 nm were mixed and present on the entire surface.

[Experimental Example 7] (Surface treatment of KLF5 copper alloy)
Commercially available 0.4 mm thick special copper alloy sheet “KLF5 (manufactured by Kobe Steel, Ltd.)” was obtained and cut to produce a large number of 45 mm × 15 mm rectangular KLF5 pieces. An aqueous solution (60 ° C.) containing 7.5% of a commercially available aluminum alloy degreasing agent “NE-6” was prepared in a tank, and the KLF5 pieces were immersed in this for 5 minutes and washed with water. Subsequently, the KLF5 pieces were immersed in a 1.5% strength aqueous sodium hydroxide solution (40 ° C.) for 1 minute and washed with water to perform preliminary base washing. Next, an aqueous solution (25 ° C.) containing 20% of an etching material for copper alloy “CB5002” and 18% of 30% hydrogen peroxide is prepared as an aqueous solution for etching. did. Next, an aqueous solution (65 ° C.) containing 10% caustic soda and 5% sodium chlorite was prepared as an oxidizing aqueous solution in another tank, and the KLF5 pieces were immersed in this for 1 minute and washed with water. Subsequently, the KLF5 piece was again immersed in the etching aqueous solution for 1 minute and washed with water, and then immersed in the oxidizing aqueous solution for 1 minute and washed with water. Thereafter, the KLF5 pieces were placed in a hot air dryer at 90 ° C. for 15 minutes and dried.

  A KLF5 piece treated in the same manner as described above was applied to a scanning probe microscope. As a result, RSm was 1 to 3 μm and Rz was 0.3 to 0.5 μm. A photograph when the electron microscope is observed at 10,000 times and 100,000 times is shown in FIG. 7 ((a): 10,000 times, (b): 100,000 times). When observed with a 100,000-fold electron microscope, the shape is a mixture of 10 to 20 nm diameter particles and 50 to 150 nm indefinite polygonal shapes mixed together, in other words, a lava plateau slope-like ultra-fine uneven shape. The entire surface was covered.

[Experimental Example 8] (Surface treatment of KS40 titanium alloy piece)
A commercially available pure titanium type titanium alloy plate “KS40 (manufactured by Kobe Steel, Ltd.)” having a thickness of 1 mm was obtained and cut to produce a large number of 45 mm × 15 mm rectangular KS40 pieces. An aqueous solution (60 ° C.) containing 7.5% of a commercially available aluminum alloy degreasing agent “NE-6” was prepared in a tank, and this was used as a degreasing aqueous solution. The KS40 pieces were immersed in this degreasing aqueous solution for 5 minutes to degrease and washed thoroughly with water. Next, an aqueous solution (60 ° C.) containing 2% of a universal etching material “KA-3 (manufactured by Metallurgy Engineering Laboratory (Tokyo, Japan))” containing 40% ammonium difluoride 40% in a separate tank is prepared. Then, the KS40 piece was immersed in this for 3 minutes and washed thoroughly with ion-exchanged water. Next, the KS40 piece was immersed in a 3% strength aqueous nitric acid solution for 1 minute and washed with water. Thereafter, the KS40 pieces were placed in a hot air dryer at 90 ° C. for 15 minutes and dried.

  A KS40 piece treated in the same manner as described above was observed with a scanning probe microscope. As a result, RSm was 1 to 3 μm and Rz was 0.8 to 1.5 μm. Photographs obtained by observing the electron microscope at 10,000 times and 100,000 times are shown in FIG. 8 ((a): 10,000 times, (b): 100,000 times). From observation with an electron microscope, a curved continuous mountain-like projection having a width and height of 10 to several hundred nm and a length of several hundred to several μm stands on the surface with an interval period of 10 to several hundred nm. It was found to be an uneven shape. Furthermore, from the analysis by XPS, a large amount of oxygen and titanium were observed on the surface, and a small amount of carbon was observed. From these, it was found that the surface layer was composed mainly of titanium oxide, and because it was dark, it was estimated to be a trivalent titanium oxide.

[Experimental Example 9] (Surface treatment of KSTi-9 titanium alloy piece)
A commercially available α-β type titanium alloy plate “KSTi-9 (manufactured by Kobe Steel, Ltd.)” having a thickness of 1 mm was obtained and cut to produce a large number of 45 mm × 15 mm rectangular KSTi-9 pieces. An aqueous solution (60 ° C.) containing 7.5% of a commercially available aluminum alloy degreasing agent “NE-6” was prepared in a tank, and this was used as a degreasing aqueous solution. The KSTi-9 pieces were immersed in this degreasing aqueous solution for 5 minutes for degreasing and thoroughly washed with water. Next, an aqueous solution (40 ° C.) having a caustic soda concentration of 1.5% was prepared in another tank, and the KSTi-9 pieces were immersed in this for 1 minute and washed with water. Next, an aqueous solution (60 ° C.) in which 2% by weight of a commercially available general-purpose etching reagent “KA-3” was dissolved was prepared in another tank, and the KSTi-9 piece was immersed in this for 3 minutes and washed thoroughly with ion-exchanged water. . Since this KSTi-9 piece had a black smut attached, it was immersed in a 3% nitric acid aqueous solution (40 ° C.) for 3 minutes, and then immersed in ion-exchanged water subjected to ultrasonic waves for 5 minutes. Then, it was again immersed in a 3% nitric acid aqueous solution for 0.5 minutes and washed with water. Next, the KSTi-9 pieces were placed in a warm air dryer at 90 ° C. for 15 minutes and dried. The dried KSTi-9 pieces had a dark brown color with no metallic luster.

  The KSTi-9 piece treated in the same manner as described above was observed with a scanning probe microscope. According to scanning analysis, RSm was 4-6 μm and Rz was 1-2 μm. A photograph of the electron microscope observed at 10,000 times and 100,000 times is shown in FIG. 9 ((a): 10,000 times, (b): 100,000 times). In addition to the part very similar to FIG. 8 of Experimental Example 8, many dead leaf-like parts that are difficult to express were seen.

[Experimental Example 10] (Surface treatment of SUS304 stainless steel piece)
A commercially available stainless steel plate “SUS304” having a thickness of 1 mm was obtained and cut to produce a large number of 45 mm × 15 mm rectangular SUS304 pieces. An aqueous solution (60 ° C.) containing 7.5% of a commercially available aluminum alloy degreasing agent “NE-6” was prepared in a tank, and this was used as a degreasing aqueous solution. The SUS304 pieces were immersed in this degreasing aqueous solution for 5 minutes to degrease and washed thoroughly with water. Subsequently, an aqueous solution (65 ° C.) containing 1% ammonium difluoride 1% and 98% sulfuric acid 5% was prepared in another tank, and the SUS304 piece was immersed in this for 4 minutes and washed thoroughly with ion-exchanged water. . Next, the SUS304 piece was immersed in a 3% nitric acid aqueous solution (40 ° C.) for 3 minutes and washed with water. Next, the SUS304 pieces were placed in a hot air dryer at 90 ° C. for 15 minutes and dried.

  A SUS304 piece treated in the same manner as described above was observed with a scanning probe microscope. According to scanning analysis, RSm was 1-2 μm and Rz was 0.3-0.4 μm. A photograph of the electron microscope observed at 10,000 times and 100,000 times is shown in FIG. 10 ((a): 10,000 times, (b): 100,000 times). From observation with an electron microscope, the surface was covered with a shape in which particle diameters having a diameter of 20 to 70 nm and indefinite polygonal shapes were stacked, in other words, a lava plateau slope-like ultra fine uneven shape. Another one was subjected to XPS analysis. From this XPS analysis, a large amount of oxygen and iron was observed on the surface, and a small amount of nickel, chromium, carbon, a very small amount of molybdenum and silicon were observed. From these, it was found that the surface layer was mainly composed of metal oxide. This analysis pattern was almost the same as SUS304 before etching.

[Experimental Example 11] (SPCC steel piece surface treatment)
A commercially available cold rolled steel sheet material “SPCC” having a thickness of 1.6 mm was obtained and cut to produce a large number of 45 mm × 15 mm rectangular SPCC pieces. An aqueous solution (60 ° C.) containing 7.5% of an aluminum alloy degreasing agent “NE-6” was prepared in a tank, and the SPCC pieces were immersed in this for 5 minutes and washed with tap water (Ota City, Gunma Prefecture). . Next, a 1.5% caustic soda aqueous solution (40 ° C.) was prepared in another tank, and the SPCC pieces were immersed in this for 1 minute and washed with water. Next, an aqueous solution (50 ° C.) containing 10% of 98% sulfuric acid was prepared in another tank, and the SPCC pieces were immersed in this for 6 minutes and sufficiently washed with ion-exchanged water. Next, the SPCC piece was immersed in 1% aqueous ammonia (25 ° C.) for 1 minute and washed with water. The SPCC pieces were then immersed in an aqueous solution (45 ° C.) containing 2% potassium permanganate, 1% acetic acid, and 0.5% sodium hydrate acetate for 1 minute and thoroughly washed with water. Thereafter, the SPCC piece was placed in a warm air dryer at 90 ° C. for 15 minutes and dried.

  The SPCC piece treated in the same manner as described above was observed with a scanning probe microscope. According to scanning analysis, RSm was 1 to 3 μm and Rz was 0.3 to 1.0 μm. Photographs obtained by observing the electron microscope at 10,000 times and 100,000 times are shown in FIG. 11 ((a): 10,000 times, (b): 100,000 times). From the observation result with a 100,000 times electron microscope, it is found that the entire surface is almost covered with an ultra fine uneven shape having a height and depth of 80 to 200 nm and a width of several hundred to several thousand nm that is infinitely continuous. I understand. It can be seen that the pearlite structure is exposed and the chemical conversion treatment layer is very thin.

[Experimental example 12] (Surface treatment of SPHC steel piece)
A commercially available 1.6 mm thick hot rolled steel “SPHC” was obtained and cut to produce a large number of 45 mm × 15 mm rectangular SPHC pieces. An aqueous solution (60 ° C.) containing 7.5% of an aluminum alloy degreasing agent “NE-6” was prepared in a tank, and the SPHC pieces were immersed in this for 5 minutes and washed with tap water (Ota City, Gunma Prefecture). . Next, a 1.5% caustic soda aqueous solution (40 ° C.) was prepared in another tank, and the SPHC pieces were immersed in this for 1 minute and washed with water. Next, an aqueous solution (65 ° C.) containing 10% 98% sulfuric acid and 1% ammonium hydrogen fluoride in a separate tank was prepared, and the SPHC pieces were immersed in this for 2 minutes and thoroughly washed with ion-exchanged water. . Next, the SPHC pieces were immersed in 1% aqueous ammonia (25 ° C.) for 1 minute and washed with water. Next, the SPHC piece was an aqueous solution (55 ° C.) containing 80% orthophosphoric acid 1.5%, zinc white 0.21%, sodium silicofluoride 0.16% and basic nickel carbonate 0.23%. For 1 minute and thoroughly washed with water. Thereafter, the SPHC pieces were placed in a warm air dryer at 90 ° C. for 15 minutes and dried.

  After drying, the SPHC pieces were observed with a scanning probe microscope. According to scanning analysis, RSm was 1 to 3 μm and Rz was 0.3 to 1.0 μm. Photographs obtained by observing the electron microscope at 10,000 times and 100,000 times are shown in FIG. 12 ((a): 10,000 times, (b): 100,000 times). According to the result of observation with an electron microscope of 100,000 times, it was found that the entire surface was covered with an ultra-fine concavo-convex shape having an infinite number of steps having a height and depth of 80 to 500 nm and a width of several hundred to several tens of thousands of nm. Okay, this was also a pearlite structure.

[Experimental Example 13] (Preparation of adhesive)
An epoxy resin “JER828 (manufactured by Japan Epoxy Resin Co., Ltd.)” whose main component is a monomer type of bisphenol type epoxy resin, and a multimeric bisphenol type epoxy resin “JER1003 (Japan Epoxy Resin) having a molecular weight of about 1300 which is a solid. Co., Ltd.), multifunctional phenol novolac type epoxy resin “JER154 (Japan Epoxy Resin Co., Ltd.)”, aniline type trifunctional epoxy resin “JER630 (Japan Epoxy Resin Co., Ltd.)”, and average particle size PES powder “PES4100MP (manufactured by Sumitomo Chemical Co., Ltd.)” having an average particle diameter of about 10 μm, PES powder with a hydroxyl group having an average particle diameter of about 20 μm “Ultrazone E2020-SRMicro (manufactured by BASF)”, and an average particle diameter of 8 ~ 12μm fine talc "Hi-micro HE5 (manufactured by Takehara Chemical Industry Co., Ltd. (Hyogo, Japan)) ”, multi-walled carbon nanotube“ MCNT (manufactured by Nanocarbon Technologies, Inc., Tokyo, Japan) ”having a diameter of about 50 nm, fumed silica“ Aerosil R805 ” (Nippon Aerosil Co., Ltd.) ”, fine powder type dicyandiamide“ DICY7 (Japan Epoxy Resin Co., Ltd.) ”which is a curing agent for epoxy resin, 2-methylimidazole fine powder“ 2MI (manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) ”, 2-phenylimidazole “2PI (manufactured by Nippon Synthetic Chemical Industry Co., Ltd.)”, 1,4-dimethylpiperazine “1,4-dimethylpiperazine (manufactured by Showa Chemical Co., Ltd. (Tokyo, Japan))”, and 3- ( Fine powder of 3,4-dichlorophenyl) -1,1-dimethylurea “DCMU99 (Hodogaya Chemical Industry) It was obtained a formula company (Tokyo, Japan) Ltd.) ". Various other amine compounds were obtained.

  Among the obtained drugs, “2PI” was not a powder but a granule. Therefore, 200 g was put in a ceramic ball mill having a diameter of 150 mm, pulverized for 30 minutes, and the balls were sieved. Stored as.

[Adhesive I: Preparation of 1-component epoxy adhesive "A, PES, DICY, 2PI"]
Take 60 parts by weight of "JER828", 20 parts by weight of "JER1003", 10 parts by weight of "JER154", and 10 parts by weight of "JER630" in a beaker and leave in a hot air drier at 150 ° C to heat. The solid type “JER1003” was melted and stirred at the same time to make the whole uniform. Then, it stood to cool and stored as an epoxy resin liquid.

  A sand grind mill “Tuea (made by Ashizawa Finetech Co., Ltd.)” filled with zirconia beads with a diameter of 0.3 mm and filled with 80% of the grinding chamber capacity is prepared. It is. On the other hand, the exit of the sand grind mill was opened to an open tank. The above epoxy resin liquid was reheated to 60 ° C. to lower the viscosity, 100 parts by mass (350 g) was charged into an open tank, and the mill was started after the grinding chamber was completely filled with a circulation pump. Since the mill has a water cooling line, water flow was adjusted so that the inside of the grinding chamber was 50-60 ° C. The peripheral speed of the mill rotor was set to 11 to 12 m / sec.

  Then, 1.75 g (0.5 parts by mass) of fumed silica “Aerosil R805” was added to the open tank, and the circulating pulverization proceeded. Then, 3 parts by mass (10.5 g) of fine talc “Hymicron HE5” was gradually added. Then, after cyclic pulverization, 4 parts by mass (14 g) of PES powder “PES4100MP” was gradually added, wet pulverization (substantially dispersing filler in the epoxy resin) for 60 minutes. Continued. Thereafter, the outlet of the mill was directed from the open tank to the polyethylene bottle, and a mixture was obtained in the polyethylene bottle. 107.5 parts by weight of this mixture includes 100 parts by weight of epoxy resin, 3 parts by weight of inorganic filler “Himicron HE5”, 0.5 parts by weight of ultrafine inorganic filler “Aerosil R805”, and thermoplastic resin powder “ 4 parts by mass of “PES4100MP” are included.

  Next, 107.5 parts by mass of the mixture, 5.4 parts by mass of fine dicyandiamide “DICY7” as a curing agent, and 2.7 parts by mass of 2-phenylimidazole powder “2PI” as a curing aid were taken in a mortar. The mortar was placed in a warm air dryer at 40 ° C. for 30 minutes to warm, and then kneaded well with a pestle. This was taken up in a polyethylene bottle, left aged indoors for 1 day, and then stored in a refrigerator at 5 ° C. The name of the adhesive was “A, PES, DICY, 2PI”. The composition of this adhesive is shown in Table 1 (Experimental Example 13).

[Experimental Example 14] (Adhesive I: Preparation of one-part epoxy adhesive “PES, DICY, 2PI”)
An adhesive was prepared in the same manner as in Experimental Example 13 except that fumed silica “Aerosil R805” was not added. The name of this adhesive was “PES, DICY, 2PI”. The composition of this adhesive is shown in Table 1 (Experimental Example 14).

[Experimental Example 15] (Adhesive I: Preparation of one-component epoxy adhesive “A, DICY, 2PI”)
An adhesive was prepared in the same manner as in Experimental Example 13 except that “PES4100MP” was not added. The name of this adhesive was “A, DICY, 2PI”. The composition of this adhesive is shown in Table 1 (Experimental Example 15).

[Experimental Example 16] (Application of adhesive I, soaking treatment I, and curing)
90 pieces of A7075 pieces prepared in Experimental Example 1 were prepared. The one-component epoxy adhesive “A, PES, DICY, 2PI” prepared in Experimental Example 13 was applied to 30 end portions. The other 30 ends were coated with the one-component epoxy adhesive “PES, DICY, 2PI” prepared in Experimental Example 14. The remaining 30 edges were coated with the one-component epoxy adhesive “A, DICY, 2PI” prepared in Experimental Example 15. These A7075 pieces were put in a desiccator that had been heated in a hot air dryer set at 60 ° C. in advance and covered. The inside of the desiccator was depressurized with a vacuum pump and allowed to return to normal pressure after about 3 minutes. This depressurization / return to normal pressure operation was performed three times in total (this is the soaking process I). Then, A7075 piece was taken out from the desiccator, the inside of a hot air dryer was 90 degreeC, it put into this hot air dryer, and it heated for 10 minutes. Thereafter, the inside of the hot air dryer was heated to 135 ° C. and heated at 135 ° C. for 50 minutes. Further, the inside of the hot air dryer was heated to 165 ° C. and heated at 165 ° C. for 30 minutes. Then it was allowed to cool. In this way, the adhesive I was cured. As a result, an A7075 piece formed with an adhesive cured product layer of the adhesive "A, PES, DICY, 2PI", an A7075 piece formed with an adhesive cured product layer of the adhesive "PES, DICY, 2PI", and adhesion Thirty A7075 pieces each formed with the cured adhesive layer of the agent “A, DICY, 2PI” were obtained.

[Experimental Example 17] (Roughening, cleaning, and drying of the cured adhesive layer)
The surface of the cured A7075 adhesive layer produced in Experimental Example 16 was roughened by reciprocating firmly and dozens of times with No. 800 polishing paper defined in JIS R6252. The roughened A7075 piece was immersed in the degreasing solution used in Experimental Example 1 ("NE-6" 7.5% aqueous solution (60 ° C)). At this time, the temperature of the degreasing solution was set to 60 ° C., and a strong ultrasonic wave was applied to the degreasing solution for 5 minutes. Then, it was immersed in three washing tanks filled with tap water sequentially. At this time, the A7075 pieces were immersed while shaking in water. Thereafter, the A7075 piece was taken out and placed in a hot air drier at 80 ° C. for 15 minutes for drying.

[Experiment 18] (Creation of CFRP piece)
In this experimental example, a CFRP piece is created as an example of a CFRP member. This CFRP piece is constituted by laminating a plurality of CFRP prepreg pieces. A CFRP prepreg “Pyrofil TR3110 (manufactured by Mitsubishi Rayon Co., Ltd.)” was obtained, and a large number of 45 mm × 15 mm pieces were cut out. A rectangular CFRP piece is created using the firing jig 1 shown in FIG. When the mold body 2 and the mold bottom plate 5 are combined, a mold recess is formed by the side wall of the mold body 2 and the upper surface of the mold bottom plate 5. A release film 17 having a thickness of 0.05 mm was laid so as to cover the mold recess. Spacers 11 and 16 made of polytetrafluoroethylene resin (hereinafter referred to as “PTFE”) were placed on the release film 17. A small piece of a 45 mm × 15 mm CFRP prepreg that had been cut was laminated on the upper surfaces of the spacers 11 and 16 by a thickness of 3 mm (the laminate is shown as 12 in FIG. 13 and becomes a CFRP piece 12 after curing). ). In order to fill the gap between the laminate and the side wall of the mold body 2, a PTFE spacer 13 was installed, and a release film 14 was laid so as to cover them.

  A PTFE block 15 was placed on the release film 14 and placed in a hot air dryer. Further, an iron 5 kg weight 18 was placed on the block 15 and the dryer was energized. The inside of the hot air dryer is heated to 90 ° C. and heated at 90 ° C. for 30 minutes, then heated to 120 ° C. and heated at 120 ° C. for 30 minutes, then heated to 135 ° C. and heated at 135 ° C. for 30 minutes. Then, the temperature was raised to 165 ° C., heated at 165 ° C. for 30 minutes, further heated to 180 ° C. and heated at 180 ° C. for 30 minutes, and then the electricity was turned off and the door was allowed to cool with the door closed. The next day, when the weight 18, the block 15, and the pedestal 8 are removed and the mold body 2 is pressed against the floor, the bottom plate protrusion 6 that protrudes below the mold bottom surface 7 from the mold through hole 4 of the mold body 2 is formed. Then, the mold bottom plate 5 is pushed upward. Thereby, the CFRP piece 12 which is a molded product covered with the release films 14 and 17 can be taken out from the firing jig 1. This operation was repeated to obtain many CFRP pieces 12. The CFRP piece 12 thus obtained is referred to as a once-baked product.

  Three days later, the CFRP piece 12 obtained as described above was put into the hot air dryer again, the inside of the hot air dryer was heated to 90 ° C., heated at 90 ° C. for 30 minutes, and then heated to 135 ° C. to 135 The resulting mixture was heated to 165 ° C. for 30 minutes, then heated to 165 ° C., heated at 165 ° C. for 30 minutes, further heated to 190 ° C., heated at 190 ° C. for 30 minutes, and then allowed to cool. That is, it was refired. The CFRP piece 12 thus obtained is referred to as a twice-baked product. This twice-baked product was baked again under the same conditions after 3 days. The CFRP piece 12 thus obtained is referred to as a three-time baked product. All CFRP pieces used in the following experimental examples are baked three times.

[Experimental Example 19] (Roughening and cleaning of CFRP piece)
The ends of the CFRP pieces obtained in Experimental Example 18 were roughened by reciprocating firmly and dozens of times with No. 80 polishing paper defined in JIS R6252. 250 liters of tap water was placed in a water tank with an ultrasonic vibration end, and 20 kg of aluminum alloy degreasing agent “NE-6 (manufactured by Meltex Co., Ltd.)” was added thereto as a degreasing solution. The degreasing liquid was heated to 60 ° C. and subjected to ultrasonic waves, and the roughened CFRP piece was immersed in this for 5 minutes. Thereafter, the CFRP pieces were sequentially immersed in three washing tanks overflowing with tap water and sufficiently washed with water. Next, the CFRP piece was placed in a hot air dryer set at 80 ° C. for 15 minutes, dried, wrapped in aluminum foil and stored.

[Experimental Example 20] (Adhesive II: Preparation of one-part epoxy adhesive “MCNT, DICY, DCMU”)
Take 60 parts by weight of "JER828", 20 parts by weight of "JER1003", 10 parts by weight of "JER154", and 10 parts by weight of "JER630" in a beaker and leave in a hot air drier at 150 ° C to heat. The solid type “JER1003” was melted and stirred at the same time to make the whole uniform. Then, it stood to cool and stored as an epoxy resin liquid.

  A sand grind mill “Tuea (made by Ashizawa Finetech Co., Ltd.)” filled with zirconia beads with a diameter of 0.3 mm and filled with 80% of the grinding chamber capacity is prepared. It is. On the other hand, the exit of the sand grind mill was opened to an open tank. The above epoxy resin liquid was reheated to 60 ° C. to lower the viscosity, 100 parts by mass (350 g) was charged into an open tank, and the mill was started after the grinding chamber was completely filled with a circulation pump. Since the mill has a water cooling line, water flow was adjusted so that the inside of the grinding chamber was 50-60 ° C. The peripheral speed of the mill rotor was set to 11 to 12 m / sec.

  Thereafter, 0.35 g (0.1 part by mass) of “MCNT” was put into an open tank, and circulation pulverization was proceeded. Then, 3 parts by mass (10.5 g) of fine talc “Hymicron HE5” was gradually added, for 60 minutes. Wet grinding (substantially the operation of dispersing the filler in the epoxy resin) was continued. Thereafter, the outlet of the mill was directed from the open tank to the polyethylene bottle, and a mixture was obtained in the polyethylene bottle. 103.1 parts by mass of the mixture includes 100 parts by mass of an epoxy resin, 3 parts by mass of an inorganic filler “HIMICRON HE5”, and 0.1 part by mass of “MCNT”.

  Next, 103.1 parts by mass of the mixture, 5.2 parts by mass of fine powder dicyandiamide “DICY7” as a curing agent, and 3- (3,4-dichlorophenyl) -1,1-dimethylurea as a curing aid are placed in a mortar. 2.6 parts by weight of fine powder “DCMU99” was taken. The mortar was placed in a warm air dryer at 40 ° C. for 30 minutes to warm, and then kneaded well with a pestle. This was taken up in a polyethylene bottle, left aged indoors for 1 day, and then stored in a refrigerator at 5 ° C. The name of the adhesive was “MCNT, DICY, DCMU”. The composition of this adhesive is shown in Table 2 (Experimental Example 20).

[Experimental Example 21] (Adhesive II: Preparation of one-part epoxy adhesive “MCNT, hydroxyl group PES, DICY, DCMU”)
In addition to “MCNT” and “Hi-micron HE5” as a filler, in addition to the addition of 4 parts by mass of PES powder “Ultrazone E2020-SRMicro” with a hydroxyl group, adhesion was performed in the same manner as in Experimental Example 20. An agent was created. However, the addition amount of the curing agent “DICY7” was 5.4 parts by mass, and the addition amount of the curing aid “DCMU99” was 2.7 parts by mass. The name of this adhesive was “MCNT, hydroxyl group PES, DICY, DCMU”. The composition of this adhesive is shown in Table 2 (Experimental example 21).

[Experimental Example 22] (Adhesive II: Preparation of one-component epoxy adhesive “DICY, DCMU”)
An adhesive was prepared in the same manner as in Experimental Example 20, except that “MCNT” was not added. The name of the adhesive was “DICY, DCMU”. The composition of this adhesive is shown in Table 2 (Experimental Example 22).

[Experimental Example 23] (Adhesive II: Preparation of one-part epoxy adhesive “MCNT, DICY, 2PI”)
An adhesive was prepared in the same manner as in Experimental Example 20, except that “DCMU” was not added and the same mass of 2-phenylimidazole “2PI” was added instead. The name of the adhesive was “MCNT, DICY, 2PI”. The composition of this adhesive is shown in Table 2 (Experimental Example 23).

[Experimental Example 24] (Adhesive II: Preparation of one-part epoxy adhesive “MCNT, DICY, DMP”)
An adhesive was prepared in the same manner as in Experimental Example 20, except that “DCMU” was not added, but instead the same mass of “1,4-dimethylpiperazine” was added. The name of the adhesive was “MCNT, DICY, DMP”. The composition of this adhesive is shown in Table 2 (Experimental Example 24).

[Experimental Example 25] (Adhesive II: Preparation of two-component epoxy adhesive “MCNT, mXy, 2PI”)
In the same manner as in Experimental Example 20, an epoxy resin solution was obtained. Further, a mixture was obtained in the same manner as in Experimental Example 20. That is, 103.1 parts by mass of the mixture includes 100 parts by mass of an epoxy resin, 3 parts by mass of an inorganic filler “HIMICRON HE5”, and 0.1 part by mass of “MCNT”.

  Next, 2.7 parts by mass of 2-phenylimidazole “2PI” as a curing aid was added to 103.1 parts by mass of the mixture in a mortar, kneaded well, and allowed to stand for 1 day, and then kneaded again. Next, 26 parts by mass of the curing agent “m-xylylenediamine” was added to the mixture after kneading and well kneaded with a glass rod. The two-component epoxy adhesive after kneading was used immediately. This adhesive contains 2.3% by mass of talc, 0.08% by mass of MCNT, 19.7% by mass of m-xylylenediamine, and 2.0% by mass of 2-phenylimidazole. The name of this adhesive was “MCNT, mXy, 2PI”. The composition of this adhesive is shown in Table 2 (Experimental Example 25).

[Experimental Example 26] (Adhesion between A7075 piece and CFRP piece with roughened surface of "A, PES, DICY, 2PI" adhesive cured product layer)
Each of the roughened A7075 pieces obtained by roughening the “A, PES, DICY, 2PI” adhesive cured product layer obtained in Experimental Example 17 and the roughened CFRP pieces obtained in Experimental Example 19 were obtained. Adhesive II was applied to the surface area. As this adhesive II, “MCNT, DICY, DCMU” prepared in Experimental Example 20 was used. The A7075 piece and the CFRP piece to which the adhesive II was applied were put in a desiccator previously heated to 60 ° C. and covered. The inside of the desiccator was depressurized with a vacuum pump and allowed to return to normal pressure after about 3 minutes. This decompression / return to normal pressure operation was performed a total of 3 times (this is impregnation treatment II). Thereafter, the A7075 piece and the CFRP piece are taken out from the desiccator, and the adhesive application ranges are brought into close contact with each other. At that time, the adhesion area is set to 0.7 to 0.8 cm ² . This pair was fixed with a clip to obtain the shape of the test piece shown in FIG. The inside of the hot air dryer was set to 90 ° C., and A7075 pieces and CFRP pieces were put into the hot air dryer and heated for 10 minutes. Next, the inside of the hot air dryer was heated to 135 ° C. and heated at 135 ° C. for 50 minutes. Next, the temperature inside the hot air dryer was raised to 165 ° C. and heated at 165 ° C. for 30 minutes. Thereafter, it was allowed to cool to obtain a test piece which was an A7075 / CFRP composite. On the next day, the test piece was broken by a tensile tester. The shear breaking force (average value of 3 pairs) at that time is shown in Table 3 (Experimental Example 26).

[Experimental Example 27] (Adhesion between A7075 piece and CFRP piece with roughened "PES, DICY, 2PI" adhesive cured layer)
The A7075 piece with the roughened “PES, DICY, 2PI” adhesive cured product layer obtained in Experimental Example 17 and the roughened CFRP piece obtained in Experimental Example 19 were the same as in Experimental Example 26. Bonded by the method. This obtained the test piece which is an A7075 / CFRP composite_body | complex. Table 3 shows the shear breaking force (average value of three pairs) when this test piece was broken by a tensile tester (Experimental Example 27).

[Experimental example 28] (Adhesion between A7075 piece and CFRP piece with roughened surface of "A, DICY, 2PI" adhesive cured product layer)
The A7075 piece with the roughened “A, DICY, 2PI” adhesive cured product layer obtained in Experimental Example 17 and the roughened CFRP piece obtained in Experimental Example 19 were the same as in Experimental Example 26. Bonded by the method. This obtained the test piece which is an A7075 / CFRP composite_body | complex. Table 3 shows the shear breaking force (average value of three pairs) when this test piece was broken by a tensile tester (Experimental Example 28).

  As shown in Table 3, in Experimental Example 27 using the adhesive I to which no Aerosil was added, the shear breaking strength at 100 ° C. was 32.7 MPa. This is a clearly lower value compared with Experimental Example 26 (51.9 MPa) and Experimental Example 28 (49.9 MPa) using the adhesive I to which Aerosil was added. This indicates that heat resistance is improved by adding an ultrafine inorganic filler to the adhesive I. However, even when the adhesive I to which no Aerosil is added is used at room temperature, a high shear breaking force of 57.0 MPa is exhibited, which is equivalent to the case where Aerosil is added. From this, it can be said that the addition of Aerosil is not necessarily required when heat resistance is not required. Further, from the results of Table 3, there is no significant difference between the results of Experimental Example 26 using the adhesive I to which PES4100MP was added and Experimental Example 28 using the adhesive I to which no PES4100MP was added. Even when the thermoplastic resin powder was added to I, it was confirmed that at least the adhesive strength was not greatly reduced.

[Experimental example 29] (Adhesion between A7075 piece and CFRP piece with roughened surface of "A, PES, DICY, 2PI" adhesive cured product layer)
A7075 pieces (made in Experimental Example 16) on which an adhesive hardened layer of the adhesive “A, PES, DICY, 2PI” is formed are firmly and ten times with the 800th abrasive paper defined in JIS R6252. The surface was roughened by reciprocal polishing. A 6 mm diameter copper pipe was directly connected to the water supply (Ota City, Gunma Prefecture), and the tip was squeezed to create a high-speed flow of tap water. This high velocity flow was applied to the roughened portion of each A7075 piece for 2 minutes. Then, it was dried with a hair dryer, wrapped in aluminum foil and stored.

  On the other hand, the end of the CFRP piece obtained in Experimental Example 18 was roughened by reciprocating firmly and dozens of times with No. 80 polishing paper defined in JIS R6252. A 6mm diameter copper tube was directly connected to the water supply (Ota City, Gunma Prefecture), and the tip was squeezed to create a high-speed flow of tap water. This high velocity flow was applied to the roughened portion of each CFRP piece for 2 minutes. Then, it was dried with a hair dryer, wrapped in aluminum foil and stored. The A7075 pieces and CFRP pieces subjected to these treatments were bonded in the same manner as in Experimental Example 26. Thereby, a test piece which is an A7075 / CFRP composite was obtained. Table 1 shows the shear breaking force (average value of three pairs) when this test piece was broken by a tensile tester (Experimental Example 29). It differs from Experimental Example 26 only in the cleaning method of the A7075 piece and the CFRP piece. Compared with Experimental Example 26 using a degreasing solution, although a decrease in adhesive strength of several MPa is observed at room temperature and 100 ° C., there is no practical difference and a sufficiently high adhesive strength is recognized. From this, it can be said that the roughened portion may be washed with running water and not necessarily with a degreasing solution.

[Experimental Example 30] (Adhesion using “MCNT, hydroxyl group PES, DICY, DCMU”)
Each of the roughened A7075 pieces obtained by roughening the “A, PES, DICY, 2PI” adhesive cured product layer obtained in Experimental Example 17 and the roughened CFRP pieces obtained in Experimental Example 19 were obtained. Adhesive II was applied to the surface area. As this adhesive II, “MCNT, hydroxyl group PES, DICY, DCMU” prepared in Experimental Example 21 was used. The A7075 piece and the CFRP piece to which the adhesive II was applied were put in a desiccator previously heated to 60 ° C. and covered. The inside of the desiccator was depressurized with a vacuum pump and allowed to return to normal pressure after about 3 minutes. This decompression / return to normal pressure operation was performed a total of 3 times (this is impregnation treatment II). Thereafter, the A7075 piece and the CFRP piece are taken out from the desiccator, and the adhesive application ranges are brought into close contact with each other. At that time, the adhesion area is set to 0.7 to 0.8 cm ² . This pair was fixed with a clip to obtain the shape of the test piece shown in FIG. The inside of the hot air dryer was set to 90 ° C., and A7075 pieces and CFRP pieces were put into the hot air dryer and heated for 10 minutes. Next, the inside of the hot air dryer was heated to 135 ° C. and heated at 135 ° C. for 50 minutes. Next, the temperature inside the hot air dryer was raised to 165 ° C. and heated at 165 ° C. for 30 minutes. Thereafter, it was allowed to cool to obtain a test piece which was an A7075 / CFRP composite. On the next day, the test piece was broken by a tensile tester. The shear breaking force (average value of three pairs) at that time is shown in Table 4 (Experimental Example 30).

[Experimental Example 31] (Adhesion using “DICY, DCMU”)
A test piece that was an A7075 / CFRP composite was obtained in the same manner as in Experimental Example 30, except that “DICY, DCMU” prepared in Experimental Example 22 was used as the adhesive II. Table 4 shows the shear breaking force (average value of three pairs) when this test piece was broken by a tensile tester (Experimental Example 31).

[Experiment 32] (Adhesion using “MCNT, DICY, 2PI”)
A test piece that was an A7075 / CFRP composite was obtained in the same manner as in Experimental Example 30, except that “MCNT, DICY, 2PI” prepared in Experimental Example 23 was used as the adhesive II. Table 4 shows the shear breaking force (average value of three pairs) when the specimen was broken by a tensile tester (Experimental Example 32).

[Experimental Example 33] (Adhesion using “MCNT, DICY, DMP”)
A test piece that was an A7075 / CFRP composite was obtained in the same manner as in Experimental Example 30, except that “MCNT, DICY, DMP” prepared in Experimental Example 24 was used as the adhesive II. Table 4 shows the shear breaking force (average value of three pairs) when the specimen is broken by a tensile tester (Experimental Example 33).

[Experimental Example 34] (Adhesion using “MCNT, mXy, 2PI”)
A test piece which is an A7075 / CFRP composite is obtained in the same manner as in Experimental Example 30, except that the two-component epoxy adhesive “MCNT, mXy, 2PI” prepared in Experimental Example 25 is used as the adhesive II. It was. Table 4 shows the shear breaking force (average value of three pairs) when this test piece was broken by a tensile tester (Experimental Example 34).

  Table 4 shows the difference in adhesive strength and heat resistance of the adhesive II. When a two-component epoxy adhesive was used (Experimental Example 34), the shear breaking strength was 43.7 MPa at room temperature and 33.2 MPa at 100 ° C., and a one-component epoxy adhesive added with MCNT was used. It was clearly lower than the results used (Experimental Examples 26, 30, 32, and 33). It was as low as 15 MPa to 20 MPa at room temperature and as low as 13 MPa to 22 MPa even at 100 ° C. However, since it still exhibits a shear breaking force of 40 MPa or higher at room temperature and 30 MPa or higher even at 100 ° C., it can be sufficiently used for applications other than those requiring extremely high reliability. And even if it does not heat at all, since complete hardening is achieved by leaving it to stand at normal temperature for 1 week or more, there exists a big advantage of a process reduction.

  Moreover, the shear breaking force of Experimental Example 31 to which MCNT is not added is 52.1 MPa at room temperature and 40.0 MPa at 100 ° C. These values are clearly lower than those of Experimental Examples 26, 30, 32, and 33 in which MCNT was added. In particular, in comparison with Experimental Example 26 in which the conditions other than the addition of MCNT were the same, a difference of 10 MPa or more occurred at both room temperature and 100 ° C. From this, it can be said that adding MCNT to the adhesive II has an effect of improving the adhesive strength at normal temperature and high temperature. However, even when MCNT is not added, it is possible to obtain a sufficiently high adhesive force. Therefore, it is not necessary to add CNT to the adhesive II as an essential condition. In addition, when the PES powder with a hydroxyl group was added (Experimental Example 30), the shear breaking force at room temperature and 100 ° C. was slightly reduced as compared with the result of not adding (Experimental Example 26). . However, a decrease in the adhesive strength that causes a problem in practical use is not recognized, and it can be said that there is no problem in adding the PES powder when it is necessary to make the adhesive elastic.

[Experimental Example 35] (Reduction of curing time of adhesive II “MCNT, DICY, DCMU”)
A test piece which is an A7075 / CFRP composite was obtained in the same manner as in Experimental Example 26 except for the method of curing the adhesive II. In this experimental example, the adhesive II “MCNT, DICY, DCMU” was heated at 110 ° C. for 1 hour. Specifically, the inside of the hot air dryer was set to 110 ° C., and a pair of A7075 pieces and CFRP pieces was put into the hot air dryer, and then the hot air dryer was taken out one hour and allowed to cool. At this time, a test piece was placed on cardboard paper and allowed to cool, but the time until the sample dropped from high temperature to room temperature was 5 minutes or less. Although rapid cooling of the adhesive is usually not preferable, it may be difficult to cool the adhesive in an environment where the bonding operation is actually performed. That is, at the site where the bonding work is performed, the adhesive may be cured by heating with hot air from a hot blaster, but when the bonding work is finished and the blowing of hot air is finished, the adhesive is allowed to cool at high speed. So, I tried to reproduce that situation. Table 5 shows the shear breaking force (average value of three pairs) when this test piece was broken by a tensile tester (Experimental Example 35).

[Experimental example 36] (Reduction of curing time of adhesive II “MCNT, DICY, 2PI”)
A test piece which was an A7075 / CFRP composite was obtained in the same manner as in Experimental Example 32 except for the method of curing the adhesive II. In this experimental example, the adhesive II “MCNT, DICY, 2PI” was heated at 120 ° C. for 1 hour. Specifically, the inside of the hot air dryer was set to 120 ° C., and after putting a pair of A7075 pieces and CFRP pieces into this hot air dryer, it was taken out one hour later and allowed to cool. The cooling is the same as in Experimental Example 35. Table 5 shows the shear breaking force (average value of three pairs) when this specimen was broken by a tensile tester (Experimental Example 36).

  Prior to Experimental Examples 35 and 36, the present inventors conducted an experiment regarding curing of the adhesive. The metal alloy pieces are bonded to each other with an adhesive, the curing condition is varied to cure the adhesive, and the shear breaking force is measured to specify the curing condition. As a result of the experiment, the adhesive “MCNT, DICY, DCMU” produced in Experimental Example 20 and “MCNT, DICY, DMP” produced in Experimental Example 24 were heated at 100 ° C. for 90 minutes, or 1 at 110 ° C. It was confirmed that the film was almost completely cured by heating for a period of time. In addition, the adhesive “MCNT, DICY, 2PI” created in Experimental Example 23 and the adhesive “CNT, DICY, 2MI” in which 2-phenylimidazole (2PI) is replaced with 2-methylimidazole (2MI) are as follows: It was confirmed that the film was almost completely cured by heating at 120 ° C. for 1 hour. Therefore, the adhesive II was cured under the same conditions as these conditions.

  As a result, when “MCNT, DICY, DCMU” was heated at 110 ° C. for 1 hour, a shear breaking force of 65.3 MPa at room temperature and 52.8 MPa at 100 ° C. was exhibited (Table 5: Experimental Example 35). . This is equivalent to or higher than the result of heating the adhesive at 90 ° C. for 10 minutes, heating at 135 ° C. for 50 minutes, and heating at 165 ° C. for 30 minutes (Table 9: Experimental Example 26). From this, it can be grasped that the adhesive II was almost completely cured under the curing conditions of Experimental Example 35. Further, by heating “MCNT, DICY, 2PI” at 120 ° C. for 1 hour, a shear breaking force of 59.8 MPa at room temperature and 53.5 MPa at 100 ° C. was shown (Table 5: Experimental Example 36). This is equal to or more than the result of heating the adhesive at 90 ° C. for 10 minutes, heating at 135 ° C. for 50 minutes, and heating at 165 ° C. for 30 minutes (Table 9: Experimental Example 32). From this, it can be understood that the adhesive II was almost completely cured under the curing conditions of Experimental Example 36. From this result, when DICY7 and DCMU99, or DICY7 and 2PI are used as a combination of a curing agent and a curing aid, curing at a relatively low temperature (110 ° C. to 120 ° C.) and a short time (about 1 hour) is possible. It can be said that it can be planned. That is, the equipment for performing the bonding operation can be simplified, and the bonding operation itself is facilitated.

[Experiment 37] (Adhesion of A5052 piece and CFRP piece)
In Experimental Example 35, it was confirmed that a sufficiently high adhesive force was exhibited by heating the adhesive II at a low temperature for a short time (1 hour at 110 ° C.). The present inventors obtained A5052 / CFRP composite test pieces in the same manner as in Experimental Example 35 using A5052 pieces obtained in Experimental Example 2 instead of A7075 pieces. That is, in this Experimental Example 37, the curing conditions of the adhesive I “A, PES, DICY, 2PI” were heated at 90 ° C. for 10 minutes, then heated at 135 ° C. for 50 minutes, and further heated at 165 ° C. for 30 minutes. It is to do. The curing condition for the adhesive II “MCNT, DICY, DCMU” is to heat at 110 ° C. for 1 hour. The same applies to Experimental Examples 38 to 47 described later. Table 6 shows the shear breaking force (average value of three pairs) when this test piece was broken by a tensile tester (Experimental Example 37).

[Experiment 38] (Adhesion of AZ31B piece and CFRP piece)
The present inventors obtained a test piece that was an AZ31B / CFRP composite by the same method as in Experimental Example 35, using the AZ31B piece obtained in Experimental Example 3 instead of the A7075 piece. Table 6 shows the shear breaking force (average value of three pairs) when the test piece was broken by a tensile tester (Experimental Example 38).

[Experimental Example 39] (Adhesion between C1100 piece and CFRP piece)
The present inventors obtained a test piece which is a C1100 / CFRP composite by the same method as in Experimental Example 35, using the C1100 piece obtained in Experimental Example 4 instead of the A7075 piece. Table 6 shows the shear breaking force (average value of three pairs) when this specimen was broken by a tensile tester (Experimental Example 39).

[Experimental example 40] (Adhesion of C5191 piece and CFRP piece)
The present inventors obtained a test piece which is a C5191 / CFRP composite by the same method as in Experimental Example 35, using the C5191 piece obtained in Experimental Example 5 instead of the A7075 piece. Table 6 shows the shear breaking force (average value of three pairs) when the test piece was broken by a tensile tester (Experimental Example 40).

[Experimental example 41] (Adhesion of KFC piece and CFRP piece)
The present inventors obtained a test piece which is a KFC / CFRP composite by the same method as in Experimental Example 35, using the KFC piece obtained in Experimental Example 6 instead of the A7075 piece. Table 6 shows the shear breaking force (average value of three pairs) when this test piece was broken by a tensile tester (Experimental Example 41).

[Experimental example 42] (Adhesion of KLF5 piece and CFRP piece)
The present inventors obtained a test piece which is a KLF5 / CFRP composite by the same method as in Experimental Example 35 using the KLF5 piece obtained in Experimental Example 7 instead of the A7075 piece. Table 6 shows the shear breaking force (average value of three pairs) when this test piece was broken by a tensile tester (Experimental Example 42).

[Experimental example 43] (Adhesion of KS40 piece and CFRP piece)
The present inventors obtained a test piece which is a KS40 / CFRP composite by the same method as in Experimental Example 35, using the KS40 piece obtained in Experimental Example 8 instead of the A7075 piece. Table 6 shows the shear breaking force (average value of three pairs) when this test piece was broken by a tensile tester (Experimental Example 43).

[Experimental Example 44] (Adhesion of KSTi-9 piece and CFRP piece)
The present inventors obtained a test piece which is a KSTi-9 / CFRP composite by the same method as in Experimental Example 35, using the KSTi-9 piece obtained in Experimental Example 9 instead of the A7075 piece. Table 6 shows the shear breaking force (average value of three pairs) when the test piece was broken by a tensile tester (Experimental Example 44).

[Experimental Example 45] (Adhesion of SUS304 piece and CFRP piece)
The present inventors obtained a test piece which is a SUS304 / CFRP composite by the same method as in Experimental Example 35 using the SUS304 piece obtained in Experimental Example 10 instead of the A7075 piece. Table 6 shows the shear breaking force (average value of three pairs) when this test piece was broken by a tensile tester (Experimental Example 45).

[Experimental example 46] (Adhesion of SPCC piece and CFRP piece)
The present inventors obtained a test piece which is an SPCC / CFRP composite by the same method as in Experimental Example 35, using the SPCC piece obtained in Experimental Example 11 instead of the A7075 piece. Table 6 shows the shear breaking force (average value of three pairs) when this test piece was broken by a tensile tester (Experimental Example 46).

[Experimental Example 47] (Adhesion of SPHC pieces and CFRP pieces)
The present inventors obtained SPHC / CFRP composite test pieces in the same manner as in Experimental Example 35 using the SPHC pieces obtained in Experimental Example 12 instead of A7075 pieces. Table 6 shows the shear breaking force (average value of three pairs) when this test piece was broken by a tensile tester (Experimental Example 47).

  From the results shown in Table 6, all metal alloy types showed extremely high shear fracture strength at room temperature. Therefore, the bonding method of the present invention can be used for all metal alloys, and can be said to be a technique for firmly bonding various metal alloys and CFRP. Moreover, although the shear breaking force at 100 ° C. is generally reduced by about 5 to 18 MPa as compared with normal temperature, all show 30 MPa or more, and the composites of various metal alloys and CFRP have practically sufficient heat resistance. It has. In particular, for the composite of pure copper-based C1100 copper alloy and CFRP, the shear fracture strength at room temperature is 49.9 MPa, but at 100 ° C., it remains as extremely small as 45.5 MPa (4.4 MPa). It can be said that it has extremely excellent heat resistance. Also, regarding the composite of SUS304 stainless steel and CFRP, the shear fracture strength at room temperature is 52.1 MPa, whereas it is 47.5 MPa at 100 ° C., so it has extremely excellent heat resistance. It can be said that.

DESCRIPTION OF SYMBOLS 12 ... CFRP prepreg laminated body 30 ... Composite 31 ... Metal alloy piece 32 ... CFRP piece 33 ... Adhesion range 40 ... Metal alloy 41 ... Ceramic layer 42 ... Adhesive hardened material layer 50 ... CFRP board material 51 ... Metal alloy part 52 ... Adhesive layer

Claims (17)

On the surface of the metal alloy, a roughness on the order of microns having an average length (RSm) of the contour curve element of 0.8 to 10 μm and a maximum height (Rz) of 0.2 to 5 μm is generated, and the roughness A surface treatment step of performing surface treatment for forming ultrafine irregularities with a period of 5 to 500 nm in a plane having a degree and forming a surface layer as a thin layer of metal oxide or metal phosphate;
A first application step of applying a first adhesive which is a one-component epoxy adhesive containing at least an inorganic filler having a particle size distribution center of 5 to 20 μm to the surface of the metal alloy that has undergone the surface treatment step; ,
A first curing step of heating and curing the first adhesive applied to the metal alloy;
An adhesive hardened material layer roughening step of roughening the adhesive hardened material layer formed on the metal alloy surface by the first hardening step;
An FRP curing step of heating and curing a fiber reinforced plastic having an epoxy resin as a matrix resin;
An FRP roughening step of roughening the surface of the fiber reinforced plastic cured by the FRP curing step;
Epoxy containing at least an inorganic filler having a center of particle size distribution of 5 to 20 μm on the surface of the cured adhesive layer after the roughening step of the cured adhesive layer and the surface of the fiber reinforced plastic after the roughening step of FRP. A second application step of applying a second adhesive which is an adhesive;
About the metal alloy and fiber reinforced plastic which apply | coated the said 2nd adhesive agent, the range which apply | coated each 2nd adhesive agent is fixed in the state which closely_contact | adhered, and both are obtained by hardening the said 2nd adhesive agent A second curing step for integrating
A method for producing a composite of a metal alloy and a fiber reinforced plastic, comprising: A method for producing a composite of a metal alloy and a fiber reinforced plastic according to claim 1,
The metal alloy that has undergone the first application step is further sealed in a sealed container, and further includes a first soaking step that pressurizes the sealed container after depressurization.
The said manufacturing method characterized by performing the said 1st hardening process after the said 1st soaking process. A method for producing a composite of a metal alloy and a fiber reinforced plastic according to claim 1 or 2,
The metal alloy or fiber reinforced plastic that has undergone the second application step, or both of them are sealed in a sealed container, and further includes a second soaking step that once pressurizes the sealed container after depressurization,
The said manufacturing method characterized by performing the said 2nd hardening process after the said 2nd soaking process. A method for producing a composite of a metal alloy and a fiber reinforced plastic according to claim 1 selected from claims 1 to 3,
The manufacturing method according to claim 1, wherein the metal alloy is any one selected from an aluminum alloy, a magnesium alloy, a copper alloy, a titanium alloy, stainless steel, and a steel material. A method for producing a composite of a metal alloy and a fiber reinforced plastic according to claim 1 selected from claims 1 to 4,
The manufacturing method, wherein the fiber reinforced plastic is CFRP (carbon fiber reinforced plastics). A method for producing a composite of a metal alloy and a fiber reinforced plastic according to claim 1 selected from claims 1 to 5,
The manufacturing method according to claim 1, wherein the first adhesive further includes an ultrafine inorganic filler having a particle size of 100 nm or less. A method for producing a composite of a metal alloy and a fiber reinforced plastic according to claim 6,
The manufacturing method according to claim 1, wherein the first adhesive contains 0.3 to 3.0 mass% of fumed silica as the ultrafine inorganic filler. A method for producing a composite of a metal alloy and a fiber reinforced plastic according to claim 1 selected from claims 1 to 5,
The manufacturing method according to claim 1, wherein the second adhesive further includes 0.04 to 0.2% by mass of carbon nanotubes having a diameter of 20 nm or more. A method for producing a composite of a metal alloy and a fiber reinforced plastic according to claim 1 selected from claims 1 to 5,
The second adhesive is a one-component epoxy adhesive,
The process as described above, wherein dicyandiamide is contained as a curing agent and 3- (3,4-dichlorophenyl) -1,1-dimethylurea is contained as a curing aid. A method for producing a composite of a metal alloy and a fiber reinforced plastic according to claim 1 selected from claims 1 to 5,
The second adhesive is a one-component epoxy adhesive,
The said manufacturing method characterized by including dicyandiamide as a hardening | curing agent and 1, 4- dimethyl piperazine as a hardening adjuvant. A method for producing a composite of a metal alloy and a fiber reinforced plastic according to claim 1 selected from claims 1 to 5,
The second adhesive is a one-component epoxy adhesive,
The said manufacturing method characterized by including dicyandiamide as a hardening | curing agent and containing 2-phenylimidazole or 2-methylimidazole as a hardening adjuvant. A method for producing a composite of a metal alloy and a fiber reinforced plastic according to one of claims 9 to 11, comprising:
The said manufacturing method characterized by hardening the said 2nd adhesive agent by heating for 2 hours or less at the temperature of 120 degrees C or less. A method for producing a composite of a metal alloy and a fiber reinforced plastic according to claim 1 selected from claims 1 to 5,
The manufacturing method according to claim 2, wherein the second adhesive is a two-component epoxy adhesive. A method for producing a composite of a metal alloy and a fiber reinforced plastic according to claim 13,
The said manufacturing method characterized by the said 2nd adhesive agent containing m-xylylenediamine as a hardening | curing agent. A method for producing a composite of a metal alloy and a fiber reinforced plastic according to claim 13 or 14,
When the second adhesive is cured, the second adhesive is cured by being left without being heated. A method for producing a composite of a metal alloy and a fiber reinforced plastic according to claim 1 selected from claims 1 to 5,
In the FRP curing step, the fiber-reinforced plastic cured by heating is heated again at a temperature equal to or higher than a temperature necessary for curing. On the surface of the α-β type titanium alloy, an average length (RSm) of the contour curve element is 0.8 to 10 μm, and a maximum height (Rz) is 0.2 to 5 μm, and a roughness on the order of microns is generated. And a surface for forming fine irregularities in which both a smooth dome shape and a curved dead leaf shape exist within an area of 10 μm square, and the surface layer is a thin layer of a metal oxide mainly containing titanium and aluminum. A surface treatment process for performing the treatment;
A first adhesive which is a one-component epoxy adhesive containing at least an inorganic filler having a particle size distribution center of 5 to 20 μm is applied to the surface of the α-β type titanium alloy that has undergone the surface treatment step. Application process of
A first curing step of heating and curing the first adhesive applied to the α-β type titanium alloy;
An adhesive hardened material layer roughening step for roughening the adhesive hardened material layer formed on the α-β type titanium alloy surface by the first hardening step;
An FRP curing step of heating and curing a fiber reinforced plastic having an epoxy resin as a matrix resin;
An FRP roughening step of roughening the surface of the fiber reinforced plastic cured by the FRP curing step;
Epoxy containing at least an inorganic filler having a center of particle size distribution of 5 to 20 μm on the surface of the cured adhesive layer after the roughening step of the cured adhesive layer and the surface of the fiber reinforced plastic after the roughening step of FRP. A second application step of applying a second adhesive which is an adhesive;
The α-β type titanium alloy coated with the second adhesive and the fiber reinforced plastic are fixed in a state where the areas where the second adhesive is applied are in close contact with each other, and the second adhesive is cured. A second curing step that integrates both of them,
A method for producing a composite of a metal alloy and a fiber reinforced plastic, comprising: