JP5714864B2 - CFRP prepreg and bonded material - Google Patents

Description

  The present invention relates to CFRP (Carbon Fiber Reinforced Plastics) used in the entire manufacturing field of transportation equipment, electrical equipment, medical equipment and the like. Specifically, the present invention relates to a CFRP prepreg obtained by improving a matrix resin, and a joined body obtained by joining the CFRP prepreg and an adherend (CFRP, metal alloy, or the like).

  The inventors of the present invention have developed a technique for firmly bonding metal alloys to each other or a metal alloy and CFRP with an epoxy adhesive. Patent Document 1 discloses a technique for firmly bonding aluminum alloys or between an aluminum alloy and CFRP using a one-component epoxy adhesive. Similarly, in Patent Documents 2, 3, 4, 5, and 6, magnesium alloy, copper alloy, titanium alloy, stainless steel, and general steel material are respectively used as a metal alloy or a CFRP member and a one-component epoxy adhesive. Thus, a technique for firmly bonding is disclosed.

  Here, in the said technique, the adhesive force was acquired by the anchor effect by making the metal alloy surface into a predetermined shape and structure. The inventors refer to this theory as “NAT (Nano Adhesion Technology)”. In NAT, the metal alloy surface satisfies the following three conditions to achieve strong adhesion to the adherend.

(1) The first condition is that when the metal alloy surface is scanned with the latest dynamic mode scanning probe microscope, RSm is 0.8 to 10 μm and Rz is 0.2 to 5 μm. It is a measure. 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). This roughness surface is referred to as a “surface having a roughness on the order of microns”.
(2) 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 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 a roughness on the order of micron is 5 to 500 nm, preferably 10 to 300 nm, more preferably 30 to 100 nm (optimum value). Form ultra-fine irregularities with a period of 50 to 70 nm.
(3) 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. It is a simple idea that when a liquid adhesive enters the surface of the metal alloy thus formed and hardens after the penetration, the metal alloy and the hardened adhesive are bonded very firmly.

  The procedure of adhesive bonding is shown below. First, the surface of the metal alloy is etched to satisfy the above three conditions. 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 cure the adhesive.

  In such a case, if the epoxy adhesive is liquid, it can penetrate into the concave portion (concave concave portion in the first condition) on the surface of the metal alloy even if the viscosity is high. And the epoxy adhesive which penetrate | invaded hardens | cures in this recessed part by subsequent heating. Actually, an ultrafine unevenness is further formed on the inner wall surface of the recess (the second condition), and the ultrafine unevenness is a thin ceramic-like thin film (the third condition). 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.

  The present inventors have demonstrated that “NAT” enables high-strength bonding between metal alloys or between metal alloys and CFRP (abbreviation of carbon fiber reinforced plastics). As an example, as a result of adhering together A7075 aluminum alloys having the conditions of “NAT” using a commercially available one-component epoxy adhesive, a bonded body exhibiting an intense shear breaking force and tensile breaking force as high as 70 MPa is obtained. (Patent Document 1).

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)

“Adhesive Erabi, which produces high performance” by Katsuhiro Maeda, p51, March 1, 1992, first edition, 7th edition (Technical Review) ThreeBond Technical News 19 (issued October 1, 1987, ThreeBond Co., Ltd.)

  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.

  As a result of investigating factors that cause the adhesive strength between CFRP and metal alloy to be inferior to the adhesive strength between metal alloys, the present inventors have found the following facts. In short, it has been found that the cause of the fracture of the composite of CFRP and metal alloy is the adhesive force between the carbon fiber in CFRP and the matrix resin. When the composite of CFRP and metal alloy was pulled and broken, the fracture surface of the metal alloy was enlarged and observed, and a lot of carbon fibers were attached to all of the fracture surface. 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 occurred previously between the hardened matrix resin and carbon fiber, and this appeared as a low adhesive force. In other words, the adhesive strength between the surface of the metal alloy and the cured adhesive and between the cured adhesive and the cured matrix resin is extremely high, and the cured adhesive itself is extremely strong. The factor that determines the adhesive strength of CFRP is the adhesive strength between the carbon fiber and the matrix resin.

  From this, it is estimated that the improvement in the adhesion between the carbon fiber and the matrix resin directly contributes to the improvement in the adhesion between the metal alloy and CFRP. The present invention has been made based on such a background, and an object of the present invention is to provide a CFRP prepreg having improved adhesion between the carbon fiber and the matrix resin, and to apply the CFRP prepreg to the CFRP prepreg. The object is to provide a bonded body in which materials (CFRP or metal alloy) are firmly bonded.

  Although CFRP is super lightweight, it has toughness exceeding steel and is recognized as an extremely excellent structural material. Although it was expensive, it was initially used only as a structural material for fighters, but in recent years it has also been used for civilian products such as aircraft, golf clubs, tennis rackets, and fishing rods, and is recognized as a general structural material. It is being done. Under such circumstances, techniques relating to carbon fiber of CFRP prepreg, carbon fiber surface treatment method, matrix resin and the like have been established. However, as described above, as a result of the development of the “NAT” by the present inventors, it becomes possible to firmly bond the metal alloy and the one-part epoxy adhesive, and the one-part epoxy adhesive and the CFRP. The adhesion between the carbon fiber and the matrix resin in the CFRP prepreg became a problem.

  As a method for improving the adhesion between the carbon fiber and the matrix resin, (1) selection of an optimal carbon fiber (focus on surface properties, not fiber strength), (2) improvement of the surface treatment method of the carbon fiber, and (3) The matrix resin can be improved. Here, although (1) and (2) are difficult unless a carbon fiber manufacturer, (3) is possible even if it is not a carbon fiber manufacturer. In recent years, carbon fiber bundles or carbon fiber fabrics that have been surface-treated have been distributed on the market. In the present invention, the adhesive strength between the matrix resin and the carbon fiber is improved by improving the matrix resin used in the CFRP prepreg. Hereinafter, the features of the CFRP prepreg of the present invention will be described in comparison with a normal CFRP prepreg.

[CFRP prepreg]
In the material more than 30 years ago, CFRP is said to be ACM (abbreviation of Advanced composite material), and the prepreg was a carbon fiber fabric soaked with a one-component epoxy adhesive. That is, a carbon fiber cloth was laid on a release paper, a one-component epoxy adhesive as a viscous liquid was applied thereto, and the entire carbon fiber cloth was infiltrated, and this was covered with a polyethylene film to form a prepreg. This prepreg is a carbon fiber bundle or carbon fiber cloth in which a matrix resin (here, one-component epoxy adhesive) is impregnated, and the surface has adhesiveness. Therefore, release paper or polyethylene film is used as the cover material because it is inconvenient for transportation and storage. At the time of use, the sheet-like prepreg sandwiched between the cover materials was cut with scissors, and then the cover material was peeled off, and the prepreg was laminated on a forming jig and fired.

  At present, the epoxy resin and the curing agent in the matrix resin are improved, and the matrix resin is a thermosetting epoxy resin composition that is solid at room temperature or has a high viscosity. Therefore, the CFRP prepreg can be easily processed. The composition of the CFRP prepreg currently on the market, particularly the specific composition of the matrix resin, is an important secret of the manufacturer and is not disclosed, so the details are unknown, but it is generally based on the following composition. The epoxy resin used as the matrix resin is a monomer type of bisphenol A type epoxy resin as a main component, and a multimeric type of bisphenol A type epoxy resin and a polyfunctional type epoxy resin having three or more epoxy groups. It is a mixture of about 3 to 5 types of different epoxy resins. A matrix resin is prepared by adding aromatic diamine or dicyandiamide as a curing agent to this mixture and kneading while heating.

  When the curing agent is an aromatic diamine, the Tg (glass transition point) of the cured epoxy resin can be increased to 150 to 190 ° C., and the heat resistance of CFRP can be ensured (Non-patent Document 1). The addition amount of the aromatic diamine is optimally based on the epoxy equivalent, and is usually 25 to 35 parts by mass with respect to 100 parts by mass of the epoxy resin. The most commonly used aromatic diamine as a curing agent is diaminodiphenyl sulfone (referred to as “DDS”), which is a solid. The epoxy resin mixture is a high-viscosity liquid, and the curing agent mixed therewith is a solid, and the amount of addition is large as described above. Therefore, mixing operation with a hardening | curing agent will be performed in the state which heated the epoxy resin mixture to 60-80 degreeC. Specifically, both are kneaded by a heating roll to form a sheet-like matrix resin. That is, the kneaded product becomes solid at room temperature. A CFRP prepreg is formed by sandwiching a carbon fiber bundle or a carbon fiber cloth between the two matrix resins formed into a sheet and heating it again to form a single layer by heating. The CFRP prepreg by this method is a hard and thin sheet as a whole, and the matrix resin is solid, so that a cover material is not necessary in principle, and an automatically controlled cutter can be used for cutting the cover material.

  On the other hand, when the curing agent is dicyandiamide, the Tg of the cured epoxy resin varies depending on the epoxy resin composition (Non-patent Document 2). This non-patent document 2 states that “the polymerization between epoxy resins is different between the case where an aliphatic polyamine or aromatic diamine is used as a curing agent and the case where dicyandiamide is used as a curing agent. There is also catalytic polymerization. " As a basis for this, when dicyandiamide powder is used as a curing agent, the optimum addition amount is far less than the value based on the epoxy equivalent, and is 3 to 8 parts by mass with respect to 100 parts by mass of the epoxy resin. Therefore, when dicyandiamide is used as the curing agent, the matrix resin is only slightly increased in viscosity compared to the epoxy resin mixture before the addition of the curing agent, and is usually not a solid at room temperature but a high viscosity liquid.

  Therefore, the CFRP prepreg manufacturing method is the above-described old method. CFRP prepreg is commercialized by sandwiching both sides with release paper or polyolefin film. A scissors or a cutter can be used for cutting the CFRP prepreg. When creating a CFRP member from a CFRP prepreg, the CFRP prepreg is cut to create a number of prepreg pieces. This prepreg piece is laminated in a jig so that the whole is clamped, and the jig is placed in an autoclave and heated while being evacuated. Alternatively, the jig is put in a heat-resistant bag to be evacuated, and is heated in a hot air dryer, a heating press, or an autoclave while being evacuated. When the matrix resin is heated to 80 to 90 ° C., it melts at one end to become a highly viscous liquid material. Accordingly, by reducing the pressure at this temperature, the air between the CFRP prepregs and in the CFRP prepreg can be extracted. Then, it is preferable to make the inside of an autoclave into a pressurized state, heating up further. By doing in this way, the voids after the air escapes between the CFRP prepregs or in the CFRP prepregs are crushed, and it becomes possible to completely cure by eliminating bubbles in the matrix resin. The heating temperature is 140 to 180 ° C., and it is preferable to heat at this temperature for 1 to 2 hours.

[Improvement of matrix resin]
An object of the present invention is to improve the adhesion between a cured matrix resin and carbon fibers. In the process of developing a one-component epoxy adhesive suitable for NAT as described above, the present inventors examined the application of the composition of this one-component epoxy adhesive to a matrix resin of a CFRP prepreg. The present inventors conducted an experiment in which metal alloys having three conditions in NAT are bonded to each other with a one-component epoxy adhesive and the adhesive force is measured. What has become clear at this time is that the adhesive strength between metal alloys by the epoxy adhesive is determined by the surface shape of the metal alloy, that is, physical factors. In other words, the chemical factor, that is, the wettability of the adhesive was favorable for the metal alloy in general. Since the surface layer of these metal alloys is a thin layer of metal oxide or metal phosphate, it is presumed that the epoxy resin has good affinity with oxygen-containing groups and ionic groups.

  On the other hand, since carbon nanotubes consisting only of carbon are lipophilic, it is presumed that carbon fibers have a similar lipophilic surface and there are few oxygen-containing groups on the surface. Therefore, it is presumed that the carbon fiber itself does not have good wettability with the epoxy resin. For such a problem, (1) means for improving the affinity with the epoxy resin by applying a surface treatment to the carbon fiber and oxidizing the fiber surface to attach a carboxylic acid group or a hydroxyl group to the fiber surface. Conceivable. That is, the affinity point concentration is improved. In addition to this, (2) there is a method of improving the adhesiveness with the matrix resin by deliberately selecting lower carbon fibers having irregularities on the carbon fiber surface. However, this method has a problem that the fiber strength of the carbon fiber itself is lowered. In addition, (3) a method of improving the epoxy group concentration in the matrix resin is also conceivable.

  Regarding (1) and (2) above, detailed examination is difficult unless a carbon fiber manufacturer. The present inventors examined (3). In order to achieve (3), an attempt was made to reduce the average epoxy equivalent of the epoxy resin. Therefore, the ratio of the bisphenol A type epoxy resin monomer type in the epoxy resin was increased, and the ratio of the polyfunctional type epoxy resin having a small epoxy equivalent was increased. Furthermore, dicyandiamide powder was used as a curing agent so that the content of the curing agent was small. When dicyandiamide powder is used, the addition amount that maximizes the adhesive performance is only 3 to 8 parts by mass with respect to 100 parts by mass of the epoxy resin, and is as large as 15 to 30 parts by mass calculated based on the epoxy equivalent. Different. In short, by using dicyandiamide powder instead of aromatic diamine as the curing agent for the matrix resin, the ratio of the curing agent in the matrix resin can be reduced and the epoxy group concentration in the matrix resin can be increased.

  The composition of the matrix resin according to the present invention is as follows. When the total epoxy resin mixture constituting this matrix resin is 100 parts by mass, (1) 45 to 75 parts by mass of bisphenol A type epoxy resin mainly composed of bisphenol A type epoxy resin monomer, (2) epoxy It is a polyfunctional type having 3 or more groups and is mixed with 55 to 25 parts by mass of an epoxy resin having an aromatic ring. As (2), those having an epoxy equivalent of 180 or less are preferable. A phenol novolac type epoxy resin “JER154 (manufactured by Japan Epoxy Resin Co., Ltd.)”, an aniline type epoxy resin having three epoxy groups on aniline “JER630 (Japan Epoxy) Resin Co., Ltd.), tetraglycidyl diaminodiphenylmethane (abbreviated as TGDDM), “JER604 (Japan Epoxy Resin Co., Ltd.)” and the like can be used. 3 to 8 parts by mass of dicyandiamide powder is added as a curing agent to 100 parts by mass of this epoxy resin mixture, and 3- (3,4-dichlorophenyl) -1,1-dimethylurea is further added as a curing aid. 1 to 4 parts by mass were added.

  In the present invention, the basic composition in the matrix resin, that is, the epoxy group content contained in the total amount of the epoxy resin and the curing agent is relatively increased to increase the adhesion between the carbon fibers after the matrix resin is cured and the matrix resin. It is intended to improve. Therefore, even when the total amount of the epoxy resin is a bisphenol A type epoxy resin monomer having a small molecular weight, the effect can be obtained. However, when the epoxy resin component is only a bisphenol A type epoxy resin monomer, the adhesion between the matrix resin and the carbon fiber at room temperature is high, but the heat resistance of the CFRP member (the heat resistance of the cured matrix resin) is low. There is a problem that the adhesive strength at a high temperature (150 ° C.) becomes extremely low. Therefore, in order to provide the matrix resin cured product with heat resistance, (2) 55 to 25 parts by mass of a polyfunctional epoxy resin having an aromatic ring and having 3 or more epoxy groups is mixed. In order to improve the quickness of the matrix resin cured product, (1) 0 to 15 parts by mass of a bisphenol A type epoxy resin oligomer having a large molecular weight is mixed in the bisphenol A type epoxy resin.

  Here, it is important that (2) 55 to 25 parts by mass of the polyfunctional epoxy resin sufficiently contain an epoxy resin having a molecular weight of 300 or less. That is, it is preferable that 70 to 100% by mass in the polyfunctional epoxy resin is composed of one having a molecular weight of 300 or less. By mixing such a polyfunctional epoxy resin, it was possible to improve the hardness of the cured matrix resin and to ensure high heat resistance.

The inventors mixed the following epoxy resins to prepare an epoxy resin component of a matrix resin.
(1) Bisphenol A type epoxy resin mainly composed of bisphenol A type epoxy resin monomer (the following two mixtures)
(1-1) Bisphenol A type epoxy resin monomer “JER828 (made by Japan Epoxy Resin Co., Ltd.)”
Viscosity: 120-150P at 25 ° C (liquid at normal temperature)
Epoxy equivalent: 184-194
Molecular weight: about 370
(1-2) Bisphenol A type epoxy resin oligomer “JER1004 (made by Japan Epoxy Resin Co., Ltd.)”
Viscosity: Q to U at 25 ° C (Gardner Holt viscosity)
Epoxy equivalent: 875-975
Molecular weight: about 1650
(2) Polyfunctional epoxy resin having an aromatic ring and having 3 or more epoxy groups (the following two mixtures)
(2-1) Phenol novolac type epoxy resin “JER154 (manufactured by Japan Epoxy Resin Co., Ltd.)”
Viscosity: 350 to 650 P at 52 ° C. (solid at normal temperature)
Epoxy equivalent: 176-180
(2-2) Aniline-type epoxy resin with three epoxy groups attached to aniline “JER630 (manufactured by Japan Epoxy Resin Co., Ltd.)”
Viscosity: 5-10P at 25 ° C (liquid at normal temperature)
Epoxy equivalent: 90-105

Here, as the above (2), the following (2-3) can also be used.
(2-3) Tetraglycidyldiaminodiphenylmethane which is a tetrafunctional epoxy resin “JER604 (made by Japan Epoxy Resin Co., Ltd.)”
Viscosity: 50-100P at 25 ° C (high viscosity liquid at normal temperature)
Epoxy equivalent: 110-130

  A matrix resin was prepared by adjusting the viscosity by mixing an inorganic filler with the epoxy resin mixture. The inorganic filler is not limited to mineral fillers such as talc or clay. In the present invention, when aluminum powder is used as the inorganic filler, the adhesive force between the matrix resin and the carbon fiber can be improved. In the present invention, 10 to 30 parts by mass of an aluminum powder having a particle size distribution center of 10 to 30 μm and 0 to 30 parts by mass of a clay having a particle size distribution center of 10 to 30 μm (preferably 10 to 30 parts by mass) 25 parts by mass). These are sufficiently kneaded to obtain a matrix resin.

  The matrix resin thus obtained becomes a high-viscosity liquid, so-called paste, which is close to the composition of a high-performance adhesive. To this matrix resin, it is also possible to add a polyethersulfone resin powder with a hydroxyl group used in CFRP prepreg for the purpose of improving impact resistance. Even when 0 to 30 parts by mass of a hydroxyl group-containing polyethersulfone resin powder having a particle size distribution center of 10 to 30 μm was added to 100 parts by mass of the total epoxy resin, the curing performance and adhesion performance of the CFRP prepreg were not affected. Polyethersulfone resin (hereinafter referred to as “PES”) is a thermoplastic resin having a melting point of 300 ° C. or higher, and is sufficiently hard from room temperature to about 150 ° C., but it creeps and deforms when an excessive force is applied. Therefore, impact resistance is given to the CFRP member.

  A CFRP prepreg was prepared by combining the matrix resin thus prepared and a commercially available carbon fiber. The CFRP prepreg was laminated to prepare a CFRP member, which was adhered to the adherend and the adhesion strength of the joined body was measured. As a result, the adhesive strength was remarkably improved as compared with the commercially available CFRP prepreg.

(How to create CFRP prepreg)
A commercially available surface-treated carbon fiber fabric (hereinafter referred to as “CF cloth”) is prepared. Prepare a release paper and polyethylene film using silicone resin that is one size larger than the CF cloth. The CF cloth is spread on the release paper and the ends are fixed with tape or pins, and the matrix resin is applied to the CF cloth. This matrix resin is in the form of a paste and may be applied in a slightly larger amount. After application, the coated surface is covered with a polyethylene film, and lightly pressed from the center toward the end to release air. Then, the excess matrix resin is pushed out by pressing again from the center toward the end. Thereby, a sheet-like product having a three-layer structure of release paper, CFRP prepreg, and polyethylene film is completed. The periphery of the sheet is cut to align the edges. The obtained sheet was sealed in a polyethylene bag and stored in a refrigerator at 5 ° C. or lower. When used, take it out of the refrigerator, leave it at room temperature for about 1 hour, remove it from the bag, cut it to the required size, peel off the cover material (release paper and polyethylene film), and use it.

[Preparation of joined body by co-bonding method]
A method for producing a joined body of a CFRP member and an adherend by the cobond method will be described. Fix the laminate of CFRP prepreg with a jig, put it in an autoclave, raise the temperature under reduced pressure, return to normal pressure after the temperature of the laminate rises to about 90 ° C, and further pressurize it to several atmospheres . Since the CFRP prepreg is once softened around 90 ° C., the air sandwiched between the layers of the CFRP prepreg is released at this point. Then, by applying pressure, the air gap after the air has escaped is crushed. Further, the laminate is heated to the curing temperature to be completely cured, the heating is stopped, and the laminate is taken out from the autoclave. This laminate is a CFRP member. Alternatively, the CFRP member is formed by cutting the laminate with a high-pressure water cutter as necessary. A bonded body is created by bonding the CFRP member and the adherend (CFRP member or metal alloy) with an adhesive.

[Creating a bonded body by the cocure method]
On the other hand, in the production of the bonded body by the co-curing method, the uncured CFRP member is not bonded to the adherend, but is heated and integrated in a state where the uncured CFRP prepreg and the adherend are conjugated. For example, when uncured CFRP prepreg laminates are integrated, they are fixed using a jig in a state in which a predetermined range of CFRP prepreg laminates is in close contact. And there exists a method of hardening the whole by putting in an autoclave in the state fixed with the jig | tool. This is an adhesion method between CFRP (a laminate of uncured CFRP prepregs) by a co-curing method. Here, a laminate of uncured CFRP prepregs may be bonded together via an epoxy adhesive. That is, an epoxy adhesive is applied to the predetermined range, and the CFRP prepreg matrix resin and the epoxy adhesive are cured at a time in an autoclave. This is also adhesion by the co-curing method. In the case where it is difficult to apply a tightening force from above and below to the contact surfaces of the CFRP prepreg laminates, it is preferable to use an epoxy adhesive.

  In addition, when the uncured CFRP prepreg laminate and the metal alloy are bonded, an epoxy adhesive is first applied to the bonding region on the surface of the metal alloy, and then a soaking process described later is performed. Thereafter, the metal alloy and the uncured CFRP prepreg laminate are brought into close contact with each other and fixed with a jig. This is placed in an autoclave and heated to cure the CFRP prepreg matrix resin and epoxy adhesive at a time. This is also adhesion by the co-curing method.

[Roughening of CFRP member]
When the CFRP member is bonded to the adherend, a stable adhesive force can be obtained by roughening the surface of the CFRP member. This surface can be polished with abrasive paper, and as a result of trial and error by the present inventors, 80-480, preferably 120-240, as specified in JIS R6252 A material obtained by polishing the surface of the CFRP member about 10 to 20 times was an adherend that stably exhibited high adhesive strength. In order to remove dirt (fine powder) adhering to the roughened surface, the CFRP member is immersed in an aqueous solution containing a detergent and then dried. Alternatively, the dirt on the roughened portion may be removed with a strong water flow, soaked in tap water or pure water, washed, and dried. In the experimental examples to be described later, abrasive paper is used, but the polishing member is not limited to abrasive paper. In the mass production process, sandblasting can be used instead of abrasive paper.

  Roughening to such an extent that a part of the carbon fiber is exposed from the surface of the CFRP member is preferable. This is because the adhesion between the carbon fiber and the one-component epoxy adhesive is generally superior to the adhesion between the carbon fiber and the matrix resin. When a commercially available one-component epoxy adhesive is used, the adhesion between the carbon fiber and the one-component epoxy adhesive is superior to the adhesion between the carbon fiber and the matrix resin at room temperature. However, at a high temperature of 100 ° C. or higher, the adhesive force between the commercially available one-component epoxy adhesive and the carbon fiber is sharply reduced, and breakage occurs between the one-component epoxy adhesive and the carbon fiber. That is, at a high temperature, not the adhesive force between the carbon fiber and the matrix resin in the CFRP prepreg used in the present invention, but a breakage is caused by a decrease in the adhesive force between the carbon fiber and the one-component epoxy adhesive.

  Based on this result, if it was possible to improve the adhesion between the carbon fiber and the one-component epoxy adhesive at high temperature, the CFRP member and the adherend were bonded extremely firmly from room temperature to high temperature. A joined body can be obtained. That is, since the adhesive force between the carbon fiber and the matrix resin becomes a problem at room temperature, the adhesive force between the two is improved by improving the matrix resin. On the other hand, since the adhesive force between the carbon fiber and the one-component epoxy adhesive becomes a problem at high temperatures, an attempt was made to improve this adhesive force by improving the one-component epoxy adhesive. When the heat-resistant one-component epoxy adhesive developed by the present inventors is used, it is possible to obtain a bonded body in which the CFRP member and the adherend are bonded extremely firmly at a high temperature. This is because the improved one-component epoxy adhesive covers the periphery of the exposed carbon fiber. This adhesive will be described below.

[Adhesive used]
The present inventors mainly used a one-component thermosetting adhesive in adhesion using NAT. Adhesive is prepared by mixing the main liquid and curing agent, and even if it is a two-component adhesive that is applied within a few minutes to an hour after mixing and cured at room temperature, the metal alloy and CFRP can be bonded. It is. However, the adhesive strength does not reach that of a one-component thermosetting adhesive. In NAT, the adhesive penetrates into a concave portion having a roughness on the order of microns on the surface of a metal alloy, and further hardens after penetrating into the ultra-fine irregularities on the inner wall surface of the concave portion. Because. For example, in the case of a two-component adhesive such as a two-component epoxy resin adhesive, polymerization / gelation starts immediately after mixing the main solution and the curing agent, so that the molecular diameter becomes too large, resulting in ultra-fine irregularities. There is a problem that it does not penetrate and the ultra fine irregularities do not contribute to the improvement of the adhesive force. As a result, it becomes difficult to obtain adhesive strength. In the case of a two-component adhesive, the time required to mix the two components before being applied to the surface of the metal alloy and soaked into the surface of the metal alloy (described later) cannot be fixed, and the adhesive force itself is not stable. There is. However, even adhesives that are generally classified into two-part adhesives do not polymerize or gel immediately after the curing agent is mixed, and the reaction proceeds substantially for several hours. It can be used if it is not. At least in the case of adhesion using NAT, it can be handled in the same manner as a one-component thermosetting adhesive.

[One-part epoxy adhesive]
For the above reasons, in the present invention, a one-component epoxy adhesive is used for bonding CFRP and a metal alloy. When metal alloys having three NAT conditions are bonded to each other, a shear fracture strength of 60 to 70 MPa can be obtained at room temperature even when a commercially available general-purpose one-component epoxy adhesive is used. On the other hand, the shear breaking force at 150 ° C. is about 6 to 15 MPa, and heat resistance has been a problem. As a result of improving the composition and filler of the epoxy resin by the present inventors, it was possible to improve the shear breaking force at room temperature to 70 to 80 MPa and improve the shear breaking force at 150 ° C. to around 40 MPa. . The one-component epoxy adhesive developed by the present inventors is particularly excellent in heat resistance, and is naturally effective for bonding metal alloys having the three conditions of NAT, but in bonding for CFRP members. Is also effective.

  The composition of the one-component epoxy adhesive is the same as that of the matrix resin described above. That is, it becomes as follows. When the total epoxy resin mixture constituting the matrix resin is 100 parts by mass, 45 to 75 parts by mass of bisphenol A type epoxy resin mainly composed of bisphenol A type epoxy resin monomer and 3 or more epoxy groups It is a functional type mixture of 55 to 25 parts by mass of an epoxy resin having an aromatic ring and having an epoxy equivalent of 180 or less. 3 to 8 parts by mass of dicyandiamide powder is added as a curing agent to 100 parts by mass of this epoxy resin mixture, and 3- (3,4-dichlorophenyl) -1,1-dimethylurea is further added as a curing aid. Add 1-4 parts by weight. As a filler, 10 to 30 parts by mass of an aluminum powder having a particle size distribution center of 10 to 30 μm and 10 to 30 parts by mass of clay having a particle size distribution center of 10 to 30 μm are added. Furthermore, it is preferable to add 0 to 30 parts by mass of a hydroxyl group-containing polyethersulfone resin powder having a particle size distribution center of 10 to 30 μm to 100 parts by mass of the total epoxy resin.

(spacer)
An object of the present invention is to enable strong bonding between a CFRP member and a metal alloy. However, a difference in linear expansion coefficient becomes a problem during this bonding. The linear expansion coefficient of the CFRP member varies depending on the amount of carbon fiber contained, but is usually about 0.3 × 10 ⁻⁵ ° C.− ¹ . On the other hand, aluminum has the largest linear expansion coefficient among metals, and its value is about 2.2 × 10 ⁻⁵ ° C. ⁻¹ . Therefore, there is a difference of about 1.9 × 10 ⁻⁵ ° C. ⁻¹ between the two. When a composite of CFRP pieces and A7075 aluminum alloy pieces adhered without gaps at room temperature (25 ° C.) is placed in an environment of 150 ° C., (1.9 × 10 ⁻⁵ ° C. ⁻¹ ) × (150 ° C.− 25 ° C.) = 0.24% deviation occurs, and 10 mm × 0.24% = 0.024 mm deviation occurs with respect to the length of 10 mm. Accordingly, even when a one-component epoxy adhesive having heat resistance is used, it softens at a high temperature and the adhesive strength is rapidly reduced. Therefore, if both materials to be bonded are of high hardness (high elastic modulus), it is impossible to suppress the force for causing the shift at high temperature with the adhesive force, and it is predicted that the breakage proceeds.

  In short, the adhesion force between the CFRP piece and the A7075 aluminum alloy piece is always lower than the adhesion force between the A7075 aluminum alloy pieces, and the difference can be reduced by using the present invention. However, it is impossible to completely seal the deviation caused by the difference in linear expansion coefficient at a high temperature of about 150 ° C. or higher. The present inventors tried to increase the thickness of the cured adhesive layer sandwiched between the A7075 aluminum alloy piece and the CFRP piece in order to alleviate the difference in linear expansion coefficient at high temperatures. This is because the hardness of the cured epoxy resin decreases when the temperature is higher than 150 ° C., and the flexibility of the filled pure aluminum-based aluminum powder and the polyethersulfone resin powder contributes to the relaxation of the deviation. This is because of expectation. As the thickness of the cured adhesive layer, if the thickness of 100 to several hundred μm can be secured, the quickness of the filler is sufficiently exerted, and the deviation generated between the upper surface and the lower surface of the cured adhesive layer is absorbed. be able to.

The inventors prepared a composite in which a CFRP piece having a thickness of 45 mm × 15 mm × 3 mm and an aluminum alloy piece were bonded with a one-component epoxy adhesive. The adhesion area at this time was about 0.5 cm ² . The bonding method is a co-bonding method, and an adhesive is applied to both ends of the CFRP piece and the aluminum alloy piece. It is fixed and put in a hot air dryer to heat and cure the adhesive. The CFRP piece and the aluminum alloy piece are pressed in the direction of the bonding surface by the pressure of the clip, and most of the adhesive sandwiched therebetween is pushed out from the edge.

  Considering the pressure by the clip, the thickness of the cured adhesive layer is less than 0.1 mm if it is a normal one-component epoxy adhesive. In order to make the thickness of the adhesive cured product layer 0.1 mm or more, a powder having a particle size of around 100 μm was included as a filler in the one-component epoxy adhesive. This large particle size powder is referred to as a “spacer”. The present inventors selected a spacer having a particle size of about 75 to 150 μm and a narrow particle size distribution and easily available. Specific examples include polyethersulfone resin powder, polyethersulfone resin powder with a hydroxyl group, metal powder such as stainless steel, calcium carbonate powder, and talc powder. These were added to a one-component epoxy adhesive, and an adhesion test between CFRP and A7075 aluminum alloy was performed.

  When the adhesive strength at room temperature is compared, there is no clear difference between the one-component epoxy adhesive containing a spacer and the one-component epoxy adhesive not containing a spacer. It is considered that the inclusion of at least a spacer does not cause a decrease in adhesive strength. Theoretically, as long as the affinity with the epoxy resin is good, it can be used as a spacer. It can be said that the PES powder with hydroxyl group and the stainless steel powder used in the experiments described later are suitable as spacers. In addition, it is estimated that aluminum powder having a particle size of about 100 μm, copper powder, copper powder with silver plating, and the like can be used. Since these are commercially available, they are easily available. In addition, since the problem of a difference in linear expansion coefficient does not occur in the adhesion between CFRPs, a spacer is unnecessary. An effect is produced when a certain number or more of spacers are included in the adhesive application region. Therefore, although it depends on the adhesion area, the addition amount is preferably about 1 to 20 parts by mass with respect to 100 parts by mass of the epoxy resin.

  In the present invention, the adhesive force between the carbon fiber and the matrix resin is improved by improving the matrix resin. Specifically, the epoxy group contained in the epoxy resin was increased, and dicyandiamide was used as the curing agent without using aromatic diamines, thereby reducing the addition amount of the curing agent. That is, the concentration of epoxy groups contained in the matrix resin was improved. The adhesive strength is increased by increasing the epoxy group concentration in the matrix resin with respect to the parent epoxy point present in the surface-treated carbon fiber.

  The present inventors conducted an experiment in which CFRP pieces obtained by laminating and curing CFRP prepregs were bonded to each other with a one-component epoxy adhesive, and the shear breaking strength of the joined body was measured. As a result, the CFRP piece using the CFRP prepreg of the present invention exceeded the shear breaking force by 5 MPa or more as compared with the CFRP piece using the conventional CFRP prepreg. Since the shear breaking force at this time is mainly determined by the adhesive force between the carbon fiber and the matrix resin, the adhesive force between the carbon fiber and the matrix resin is clearly improved. Similar results were obtained when the CFRP piece and the metal alloy piece were bonded together.

  By using the CFRP prepreg of the present invention, it was possible to obtain a bonded body in which the CFRP member (cured CFRP prepreg) and the adherend (metal alloy or CFRP member) were bonded extremely firmly. The bonding strength of this bonded body was close to that of a bonded body in which metal alloys were bonded together. Furthermore, when the CFRP member and the adherend are bonded, a bonded body having a strong adhesive force from room temperature to high temperature can be obtained by using a heat-resistant one-component epoxy adhesive.

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 is an electron micrograph ((a): 10,000 times, (b): 10) of a surface obtained by chemically etching a “KFC” copper alloy with a sulfuric acid / hydrogen peroxide aqueous solution and performing a surface hardening treatment with a sodium chlorite aqueous solution. Million times). FIG. 7 is an electron micrograph ((a): 10,000 times, (b): 10) of a surface obtained by chemically etching “KLF5” copper alloy with sulfuric acid / hydrogen peroxide aqueous solution and surface hardening treatment with sodium chlorite aqueous solution. Million 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 solution of 1 hydrogen difluoride ammonium. FIG. 9 is an electron micrograph ((a): 10,000 times, (b): 100,000 times) of a surface obtained by chemically etching a “KSTi-9” α-β titanium alloy with an aqueous solution of ammonium hydrogen difluoride. is there. 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 producing a CFRP plate by laminating CFRP prepregs. FIG. 14 shows a test piece in which a metal alloy piece and a CFRP piece, or CFRP pieces are bonded together. FIG. 15 is a test piece obtained by bonding a reinforced metal alloy piece and a CFRP piece. FIG. 16 is a schematic cross-sectional view showing a surface structure when a metal alloy and a thermosetting epoxy resin composition are bonded. FIG. 17 is a cross-sectional view of a firing jig for creating a composite of a CFRP member and a metal alloy, or a joined body of CFRP members.

[Metal alloys as adherends]
The CFRP prepreg of the present invention has an increased adhesive force between carbon fibers and a matrix resin. However, the adhesive strength becomes a problem when the adhesive strength between the CFRP member and the cured adhesive and between the cured adhesive and the adherend is extremely high as described above. Therefore, if the adherend is a metal alloy having a surface that meets the three conditions of NAT, the effect of improving the matrix resin of the CFRP prepreg can be exhibited. Hereinafter, the metal alloy as the adherend will be described.

(Metal alloy that meets NAT requirements)
The metal alloy having a surface structure based on the above-described “NAT” is not particularly limited in theory. However, “NAT” can actually be applied to hard and practical metal alloys. The inventors of the present invention have confirmed that “NAT” can be applied to metal alloy types mainly composed of aluminum, magnesium, copper, titanium, and iron. Patent Document 1 describes an aluminum alloy. Patent Document 2 describes a magnesium alloy. Patent Document 3 describes a copper alloy. Patent Document 4 describes a titanium alloy. Patent Document 5 describes stainless steel. Patent Document 6 describes general steel materials. However, since “NAT” aims to improve the adhesive force by the anchor effect, it is not limited to at least these metal alloy types. Hereinafter, a surface treatment process for making the surface of the metal alloy into a surface structure conforming to the “NAT” condition will be described.

(Chemical etching)
The chemical etching in this surface treatment process is intended to produce a roughness on the order of microns on the surface of the 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 performing trial and error. According to literature records (for example, "Chemical Engineering Handbook (edited by 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 can be corroded entirely by highly concentrated nitric acid aqueous solution or strongly acidic oxidizing acid such as hydrogen peroxide or oxidizer compound liquid, and titanium alloys are oxalic acid or hydrofluoric acid based It can be seen from technical books and patent literature that it can be totally corroded with a special acid. 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 1 describes an aluminum alloy, Patent Document 2 describes a magnesium alloy, Patent Document 3 describes a copper alloy, Patent Document 4 describes a titanium alloy, and Patent Document 5 describes a stainless steel. And Patent Document 6 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 diluted 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 and surface hardening treatment)
The purpose of the fine etching in the surface treatment step is to form ultra-fine irregularities on the surface of the 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 natural oxide layer on the surface may be thicker than the original and the surface hardening process may be completed. For example, a pure titanium-based titanium alloy is only subjected 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 perform 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) In some cases, the condition of “NAT” is provided without performing a surface hardening process or a fine etching process again. The problem at that time is that the corrosion resistance of the natural oxide layer is not sufficient, so that corrosion starts before the bonding step, and the adhesive strength is reduced 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 when the thickness of a film (chemical conversion film) formed on the surface of a metal alloy by chemical conversion treatment is thick, the adhesive force often decreases. A strong adhesive force can be obtained when the thin layer is such that the 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 lowered. Therefore, the degree of balance depends on the purpose of use and application.

[Soaking process]
(Metal alloy)
After applying a one-component epoxy adhesive to the surface of the metal alloy satisfying the first to third conditions that conform to NAT, the metal alloy is sealed in a container such as a desiccator, and the container is vacuumed. The pressure is once reduced with a 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 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 so that it can easily penetrate into the ultra-fine irregularities on the surface. By setting the adhesive viscosity of the adhesive to 15 Pa seconds or less, preferably 10 Pa seconds or less, the ultra fine unevenness is caused to enter. The metal alloy soaked and treated is taken out of the container and placed in a hot air dryer to cure the adhesive.

  Here, when the viscosity of the adhesive to be applied to the surface of the metal alloy is low (for example, 10 Pa seconds or less), the adhesive penetrates into the ultra-fine irregularities without performing the above-described decompression / normal pressure return operation. There is a case. In this case, of course, the soaking process is unnecessary. Moreover, even if the viscosity of the adhesive to be applied is high, by warming the metal alloy, the viscosity of the adhesive may decrease after application and may enter into the ultra-fine irregularities. Even in this case, the soaking process is unnecessary. The heating and the soaking process of the metal alloy before application of the adhesive may be performed according to the degree of penetration of the adhesive into the ultra-fine irregularities.

(CFRP member)
After applying a one-component epoxy adhesive to a specified part of the roughened CFRP member, place it in a container such as a desiccator, seal it, and once depressurize the container with a vacuum pump, then return to normal pressure I do. 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. The purpose of this operation is to allow the adhesive to penetrate into the irregularities on the surface of the CFRP member caused by the roughening. That is, the epoxy resin cured product obtained by curing the CFRP matrix resin is soaked with an adhesive as an epoxy adhesive. When the viscosity of the adhesive after mixing the curing agent is as high as several tens of Pa seconds or more, the container used for the soaking process is heated to 50 to 70 ° C. in advance. Thus, the viscosity of the epoxy adhesive is set to 15 Pa seconds or less, preferably 10 Pa seconds or less.

  Here, when the viscosity of the adhesive to be applied to the CFRP member is low (for example, 15 Pa seconds or less), it is not necessary to perform the above-described decompression / normal pressure return operation, and the adhesive is uneven on the roughened portion. May invade. In this case, of course, the soaking process is unnecessary. Even if the viscosity of the adhesive to be applied is high, by warming the CFRP member, the viscosity of the adhesive may decrease after application and may enter the irregularities of the roughened portion. Even in this case, the soaking process is unnecessary. The heating and soaking process of the CFRP member before application of the adhesive may be performed according to the degree of penetration of the adhesive into the unevenness.

[Experimental example]
Embodiments of the present invention will be described below. The equipment used for measurement etc. is shown below.
(A) X-ray surface observation (XPS observation)
ESCA “AXIS-Nova (Kraitos (USA) / Shimadzu Corporation (Kyoto Prefecture, Japan))” in the form of observing 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 “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 Bonding Strength of Composite Material Using a tensile tester “MODEL-1323 (manufactured by Aiko Engineering Co., Ltd. (Osaka, Japan))”, the shear breaking strength was measured at a pulling speed of 10 mm / min.
Next, the surface treatment of the metal alloy plate constituting the laminated material will be described.

[Experimental Example 1] (Surface treatment of aluminum alloy (A7075))
A commercially available aluminum alloy plate “A7075” having a thickness of 3 mm was obtained and cut to produce a large number of 45 mm × 18 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 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 × 18 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 piece was 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 which carried out the said process was observed with the electron microscope, it turned out that it is covered with the 30-100 nm diameter recessed part. 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 1-2 μm and Rz was 0.3-0.5 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 × 18 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 above-treated AZ31B piece was observed with an electron microscope, a rod-like crystal having a diameter of 5 to 20 nm was intertwined into a lump having a diameter of about 100 nm, and the lump was covered with a super fine uneven shape forming a surface. was there. 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 mm, was obtained and cut to produce a large number of rectangular C1100 pieces of 45 mm × 18 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 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.

  The C1100 piece treated 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 0.8 mm was obtained and cut to produce a large number of rectangular C5191 pieces of 45 mm × 18 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 an etching material for copper alloy “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.

  The C5191 piece treated 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 0.7 mm was obtained and cut to produce a large number of 45 mm × 18 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.

  The KFC piece treated 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)
A commercially available 0.7 mm thick special copper alloy sheet “KLF5 (manufactured by Kobe Steel, Ltd.)” was obtained and cut to produce a large number of 45 mm × 18 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. The KLF5 pieces are 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 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.

  The KLF5 piece treated 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 × 18 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.

  The KS40 piece subjected to the above treatment 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 × 18 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 piece was 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 hot 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 above treated KSTi-9 pieces were 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 material “SUS304” having a thickness of 1 mm was obtained and cut to produce a large number of 45 mm × 18 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 piece was 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.

  The SUS304 piece treated 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.

[Experiment 11] (Surface treatment of SPCC steel piece)
A commercially available cold rolled steel plate material “SPCC” having a thickness of 1.6 mm was obtained and cut to produce a large number of 45 mm × 18 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 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.

[Experiment 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 × 18 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 difluoride was prepared in another tank, and the SPHC pieces were immersed in this for 2 minutes and washed thoroughly 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 matrix resin)
An epoxy resin “JER828 (manufactured by Japan Epoxy Resin Co., Ltd.)” whose main component is a monomer of bisphenol A type epoxy resin, and a multimeric bisphenol A type epoxy resin “JER1004” (Japan) Epoxy Resin Co., Ltd.) ”, polyfunctional phenol novolac epoxy resin“ JER154 (Japan Epoxy Resin Co., Ltd.) ”, aniline type trifunctional epoxy resin“ JER630 (Japan Epoxy Resin Co., Ltd.) ”, tetrafunctional Tetraglycidyldiaminodiphenylmethane “JER604 (Japan Epoxy Resin Co., Ltd.)”, a pure aluminum-based aluminum alloy powder with a particle size distribution of 16 μm “Filler aluminum powder (Toyo Aluminum) ”, Fine powdered dicyandiamide“ DICY7 (manufactured by Japan Epoxy Resin Co., Ltd.) ”which is a curing agent for epoxy resin, and 3- (3,4-dichlorophenyl) -1,1-dimethylurea as a curing aid “DCMU99 (manufactured by Hodogaya Chemical Co., Ltd.)”, PES powder with a hydroxyl group whose particle size distribution is 20 μm “Ultrazone E2020P-SRMicro (manufactured by BASF)”, fine powder talc with an average particle size of 8 to 12 μm “High” Micron HE5 (manufactured by Takehara Chemical Industry Co., Ltd. (Hyogo, Japan)) ”and clay (kaolin)“ Satinton 5 (manufactured by Takehara Chemical Industry Co., Ltd.) ”having an equivalent particle size were obtained.

  Take 65 parts by weight of “JER828”, 5 parts by weight of “JER1004”, 10 parts by weight of “JER154”, and 20 parts by weight of “JER630” in a beaker and leave them in a hot air drier at 160 ° C. to heat them. The mold “JER1004” 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.

  Next, 100 parts by mass of the mixture, 14 parts by mass of aluminum powder “aluminum powder for filler” having a particle size distribution center of 16 μm, and 14 parts by mass of clay “Satinton 5” having a particle size distribution center of 8 to 12 μm are cured in a mortar. 5 parts by mass of fine powder type dicyandiamide “DICY7” as an agent and 2.5 parts by mass of “DCMU99” as a curing aid were taken. The mortar contents were kneaded with a pestle for 15 minutes. The mixture was allowed to stand for 1 hour and then kneaded again with a pestle for several minutes. This was taken in a polyethylene bottle and aged at room temperature for 1 day, and then stored in a refrigerator at 5 ° C.

[Experiment 14] (Preparation of CFRP prepreg)
A CF cloth “TR3110M (manufactured by Mitsubishi Rayon Co., Ltd.)” having a thickness of about 0.2 mm was obtained and cut into 130 mm × 130 mm. On the other hand, a release paper using a silicone resin was cut into 200 mm × 200 mm, placed on a wooden flat plate, and fixed on four sides with a tape and a pin. Next, a CF cloth cut to 130 mm × 130 mm was laid in the center, and the four sides were fixed with a tape and a pin. Next, the pasty matrix resin prepared in Experimental Example 13 was applied from above the CF cloth using a plastic spatula. The coating layer of the matrix resin was made to be uniformly thick. A 0.01 mm thick polyethylene film cut to 200 mm × 200 mm from the top of the coating layer was covered. A block to be overlapped was placed at the center of the polyethylene film, and the block was moved from the center toward the end while being pressed with a constant pressure. As a result, the matrix resin oozes out to the surface of the CF cloth, and excess matrix resin is pushed out from the end of the CF cloth. Thereafter, the end of the CF cloth sandwiched between the release paper and the polyethylene film and coated with the matrix resin was cut with a cutter to prepare a 110 mm × 110 mm square sheet. The same operation was repeated to produce a large number of 110 mm × 110 mm square sheets. These square sheets were put in a desiccator and sealed, and the inside of the desiccator was decompressed with a vacuum pump and returned to normal pressure in about 5 minutes. As a result, air inside the matrix resin and the CF cloth is removed, and the matrix resin is spread over the entire CF cloth. A large number of CFRP prepregs (in a state sandwiched between release paper and polyethylene film) thus prepared were sealed in a bag and stored in a refrigerator at 5 ° C.

[Experiment 15] (Production of CFRP member)
A commercially available plain weave CFRP prepreg “Pyrofil TR3110 (manufactured by Mitsubishi Rayon Co., Ltd.)” having a thickness of 0.2 mm was prepared, and a large number of 220 mm × 220 mm square pieces (thickness 0.2 mm) were cut out therefrom. A CFRP plate made of a laminate of CFRP prepregs is prepared using the firing jig 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.

  On this release film 17, 15 commercially available CFRP prepregs having a size of 220 mm × 220 mm were laminated. A laminate of these CFRP prepregs is shown as CFRP prepreg laminate 22 in the figure. A release film 14 was laid so as to cover the CFRP prepreg laminate 22. A PTFE block 15 was placed on the release film 14, and an iron weight 18 was placed on the block 15 and placed in a large autoclave. After closing the autoclave lid to set the internal temperature to about 90 ° C., the internal pressure was reduced to 10 mmHg or less with a vacuum pump. After heating at this temperature for 15 minutes, the temperature was raised and when it reached 135 ° C., air was introduced to return to normal pressure. Then, it heated at 135 degreeC for 40 minutes, and raised the temperature to 165 degreeC after that, and heated for 30 minutes, adjusting so that it might be around 165 degreeC. Thereafter, heating was stopped and the mixture was allowed to cool. Thereafter, the autoclave was opened and the firing jig 1 was disassembled to obtain a CFRP plate (cured product of the CFRP prepreg laminate 22). The CFRP plate was cut with a high-pressure water cutter to produce a large number of CFRP pieces of 45 mm × 15 mm and a thickness of 3 mm. The same process was repeated to produce a large number of CFRP pieces.

  15 mm from the surface end of the CFRP piece prepared as described above was firmly polished 10 times with No. 120 polishing paper defined in JIS R6252 to roughen the surface. Next, an aqueous solution (60 ° C.) containing 7.5% of a degreasing agent for aluminum alloy “NE-6” was prepared in a tank in which an ultrasonic wave transmitting end was installed, and the surface was roughened by applying ultrasonic waves thereto. The CFRP piece was immersed for 5 minutes. Thereafter, this CFRP piece was washed with water and dried in a hot air dryer set at 80 ° C. for 15 minutes. The CFRP piece obtained in this way was wrapped in aluminum foil and stored.

[Experimental Example 16] (Production of CFRP member)
A commercially available plain weave CFRP prepreg “Pyrofil TR3110 (manufactured by Mitsubishi Rayon Co., Ltd.)” having a thickness of 0.2 mm was prepared, and a large number of 220 mm × 220 mm square pieces (thickness 0.2 mm) were cut out therefrom. In addition, a large number of 110 mm × 110 mm CFRP prepregs (invention) prepared in Experimental Example 14 were prepared. At this time, the CFRP prepreg of the present invention is in a state of being covered with a cover material (release paper and polyethylene film). A CFRP plate made of a laminate of these CFRP prepregs is prepared using the firing jig 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.

  On this release film 17, 12 “Pyrofil TR3110” cut to 220 mm × 220 mm were laminated. Further, four (2 × 2) CFRP prepregs (110 mm × 110 mm) of the present invention were spread on the laminated “Pyrofil TR3110” according to the shape (220 mm × 220 mm). At this time, the cover material (release paper and polyethylene film) was peeled off from the CFRP prepreg and laminated. Further, the layer composed of four CFRP prepregs of the present invention has a three-layer structure. That is, 4 × 3 = 12 CFRP prepregs (110 mm × 110 mm) of the present invention were used. A laminate of these CFRP prepregs is shown as CFRP prepreg laminate 22 in the figure. A release film 14 was laid so as to cover the CFRP prepreg laminate 22.

  A PTFE block 15 was placed on the release film 14, and a weight 18 was placed on the block 15 and placed in a large autoclave. After closing the autoclave lid to set the internal temperature to about 90 ° C., the internal pressure was reduced to 10 mmHg or less with a vacuum pump. After heating at this temperature for 15 minutes, the temperature was raised and when it reached 135 ° C., air was introduced to return to normal pressure. Then, it heated at 135 degreeC for 40 minutes, and raised the temperature to 165 degreeC after that, and heated for 30 minutes, adjusting so that it might be around 165 degreeC. Thereafter, the heating was stopped and the mixture was allowed to cool for 24 hours. Thereafter, the autoclave was opened and the firing jig 1 was disassembled to obtain a CFRP plate (cured product of the CFRP prepreg laminate 22). The CFRP plate was cut with a high-pressure water cutter to produce a large number of CFRP pieces of 45 mm × 15 mm and a thickness of 3 mm. The same process was repeated to produce a large number of CFRP pieces. Of the 15 CFRP prepreg layers constituting the CFRP piece, 3 surface layers are constituted by the CFRP prepreg of the present invention.

  15 mm from the surface end of the CFRP piece prepared as described above was firmly polished 10 times with No. 120 polishing paper defined in JIS R6252 to roughen the surface. Next, an aqueous solution (60 ° C.) containing 7.5% of a degreasing agent for aluminum alloy “NE-6” was prepared in a tank in which an ultrasonic wave transmitting end was installed, and the surface was roughened by applying ultrasonic waves thereto. The CFRP piece was immersed for 5 minutes. Thereafter, this CFRP piece was washed with water and dried in a hot air dryer set at 80 ° C. for 15 minutes. The CFRP piece obtained in this way was wrapped in aluminum foil and stored.

[Experimental Example 17] (Adhesion of CFRP pieces by cobond method)
A commercially available one-component epoxy adhesive “EP106NL (manufactured by Cemedine Co., Ltd.)” was obtained. The CFRP pieces (CFRP members composed only of commercially available CFRP prepregs) prepared in Experimental Example 15 were bonded together with this adhesive. First, an adhesive was applied to the roughened area of both CFRP pieces, put in a desiccator and sealed, the inside of the desiccator was decompressed, placed under reduced pressure for several minutes, and then returned to normal pressure. After repeating this decompression / return to normal pressure several times, both CFRP pieces were removed from the desiccator. As shown in FIG. 14, the adhesive application areas of both CFRP pieces 23 and 24 were brought into close contact with each other and fixed with clips. The adhesion area (shaded portion 25 in FIG. 14) was set to about 0.5 cm ² . In the same manner as this, the CFRP pieces (CFRP members composed of a commercially available CFRP prepreg and the CFRP prepreg of the present invention) prepared in Experimental Example 16 were bonded to each other with the adhesive. In other words, an adhesive is applied to the roughened area of both CFRP pieces, soaked and treated, the adhesive application areas of both CFRP pieces 23 and 24 are brought into close contact with each other, and fixed with clips. .

  These were put into a hot air dryer set at 90 ° C., heated to 135 ° C. and heated for 40 minutes. Then, after heating up to 165 degreeC and heating for 30 minutes, the power supply was turned off and it stood to cool. The bonded body 20 of the CFRP pieces 23 and 24 thus obtained was pulled and broken using a testing machine after 3 days, and the shear breaking force was measured. These tests were performed at room temperature and 150 ° C. As a result, the joined body of CFRP pieces obtained in Experimental Example 15 exhibited a shear breaking force of 46.4 MPa at room temperature. On the other hand, the joined body of CFRP pieces obtained in Experimental Example 16 exhibited a shear breaking force of 56.7 MPa at room temperature. From this result, it was confirmed that the CFRP piece using the CFRP prepreg of the present invention in the bonding range shows higher adhesive strength. In addition, the shear breaking force at 150 ° C. was low for all joined bodies, and was several MPa.

[Experiment 18] (Preparation of adhesive 1)
A one-part epoxy adhesive was prepared as follows. Take 65 parts by weight of “JER828”, 5 parts by weight of “JER1004”, 10 parts by weight of “JER154”, 15 parts by weight of “JER630”, and 5 parts by weight of “JER604” in a beaker and leave them in a hot air dryer at 160 ° C. The solid type “JER1004” was melted and stirred at the same time to homogenize the whole.

  Next, 100 parts by mass of the epoxy resin mixture in the mortar, 14 parts by mass of aluminum powder “aluminum powder for filler” having a particle size distribution center of 16 μm, and 14 parts by mass of clay “Satinton 5” having a particle size distribution center of 8 to 12 μm. 5 parts by mass of fine powder dicyandiamide “DICY7” as a curing agent and 2.5 parts by mass of “DCMU99” as a curing aid. The contents of this mortar were kneaded with a pestle for 3 minutes. Thereafter, the mixture was allowed to stand for 1 hour and then kneaded again with a pestle for several minutes. This was taken in a polyethylene bottle and stored in a refrigerator at 5 ° C. The one-component epoxy adhesive thus obtained is referred to as adhesive 1.

[Experimental Example 19] (Preparation of Adhesive 2)
A one-part epoxy adhesive was prepared as follows. Take 50 parts by weight of “JER828”, 10 parts by weight of “JER154”, 20 parts by weight of “JER630”, and 20 parts by weight of “JER604” in a beaker and leave them in a hot air dryer at 160 ° C. Turned into.

  Next, 100 parts by mass of the epoxy resin mixture in the mortar, 20 parts by mass of aluminum powder “aluminum powder for filler” having a particle size distribution center of 16 μm, and 20 parts by mass of clay “Satinton 5” having a particle size distribution center of 8 to 12 μm. 5 parts by mass of PES powder with a hydroxyl group having a particle size distribution center of 20 μm “Ultra Zone E2020P-SRMicro (manufactured by BASF)”, 5 parts by mass of fine powder dicyandiamide “DICY7” as a curing agent, and “ DCMU99 "3 parts by weight were taken. The contents of this mortar were kneaded with a pestle for 3 minutes. Thereafter, the mixture was allowed to stand for 1 hour and then kneaded again with a pestle for several minutes. This mixture was taken in a polyethylene bottle and stored in a refrigerator at 5 ° C.

  On the other hand, a stainless steel powder “DAP304L (manufactured by Daido Special Steel Co., Ltd.)” made of stainless steel SUS304L and having a particle size distribution center of 100 μm is obtained. 1 liter of an aqueous solution containing 3% by mass of “made by Co., Ltd.” was added. Thereafter, the beaker liquid was filtered, and the separated stainless steel powder was washed using a large amount of ion-exchanged water. The stainless steel powder was transferred to a beaker, 200 cc of an aqueous solution containing 1% by mass of caustic soda was added, and the mixture was lightly stirred and left for 1 minute.

  Thereafter, the beaker liquid was filtered, and the separated stainless steel powder was washed using a large amount of ion-exchanged water. The stainless steel powder was transferred to a beaker, 500 cc of an aqueous solution containing 5% by mass of sulfuric acid and 1% by mass of 1 hydrogen difluoride was added and stirred gently, and then left for 5 minutes. The liquid in the beaker was filtered, and the separated stainless steel powder was washed using a large amount of ion exchange water. The stainless steel powder was transferred to a beaker, 500 cc of an aqueous solution containing 3% by mass of nitric acid was added, and the mixture was lightly stirred and left for 5 minutes. Further, the beaker liquid was filtered, and the separated stainless steel powder was washed using a large amount of ion-exchanged water. The stainless steel powder obtained in this way is transferred to a large petri dish, spread over the entire petri dish, tilt the petri dish, absorb the water accumulated in the lower part with filter paper, etc., and place in a hot air dryer set at 100 ° C for 30 minutes to dry. did. The stainless steel powder thus obtained is used.

  The mixture stored in the refrigerator was taken out and placed in a mortar. To 100 parts by mass of the epoxy resin in the mixture, 5 parts by mass of stainless steel powder and 10 parts by mass of hydroxyl group-containing polyethersulfone resin powder having a particle size of 90 to 106 μm were added and kneaded for 1 minute or more. The kneaded mixture was transferred from a mortar to a glass bottle, capped, and stored in a refrigerator at 5 ° C. The polyethersulfone resin powder with a hydroxyl group having a particle size of 90 to 106 μm described above is a product obtained by pulverizing and classifying a polyethersulfone resin granule with a hydroxyl group “Sumika Excel 5003P (manufactured by Sumitomo Chemical Co., Ltd.)”. The one-component epoxy adhesive thus obtained is referred to as adhesive 2.

[Experiment 20] (Adhesion test between CFRP piece and A7075 piece)
A large number of 45 mm × 15 mm A7075 aluminum alloy pieces (thickness: 3 mm) prepared in Experimental Example 1 were prepared, and the adhesive 1 prepared in Experimental Example 18 was applied and soaked into the respective end portions for treatment. On the other hand, the adhesive 1 was applied and soaked into the roughened range of the CFRP piece (CFRP member composed only of commercially available CFRP prepreg) prepared in Experimental Example 15, and the treatment was performed. As shown in FIG. 14, the adhesive application areas of the A7075 piece and the CFRP piece were brought into close contact with each other and fixed with clips. The adhesion area (shaded area in FIG. 14) was set to about 0.5 cm ² . In the same manner, the A7075 piece prepared in Experimental Example 1 and the CFRP piece prepared in Experimental Example 16 (CFRP member composed of a commercially available CFRP prepreg and the CFRP prepreg of the present invention) were bonded together with the adhesive 1. . That is, the adhesive 1 is applied and soaked at the end of the A7075 piece, while the adhesive 1 is applied and soaked into the roughened area of the CFRP piece, and both adhesives are applied. The areas were brought into close contact with each other and fixed with clips.

  These were put into a hot air dryer set at 90 ° C., heated to 135 ° C. and heated for 40 minutes. Then, after heating up to 165 degreeC and heating for 30 minutes, the power supply was turned off and it stood to cool. The joined body obtained as described above was subjected to tensile fracture using a testing machine after one week, and the shear fracture strength was measured. These tests were performed at room temperature and 150 ° C. The results are shown in Table 1. The composite of the CFRP piece and A7075 piece obtained in Experimental Example 15 exhibited a shear breaking strength of 49.5 MPa. On the other hand, the composite of the CFRP piece and A7075 piece obtained in Experimental Example 16 exhibited a shear breaking force of 56.8 MPa. From this result, it was confirmed that the CFRP piece using the CFRP prepreg of the present invention in the bonding range shows higher adhesive strength.

  Further, even at 150 ° C., the CFRP piece using the CFRP prepreg of the present invention in the bonding range showed higher adhesive strength. In addition, although the adhesive agent 1 is used for the adhesion | attachment in this experiment example, this adhesive agent 1 is the 1 liquid epoxy adhesive improved so that heat resistance might be improved. The shear breaking force at 150 ° C. is as high as 15.7 MPa when the CFRP piece of Experimental Example 15 is used, and 19.8 MPa when the CFRP piece of Experimental Example 16 is used. The effect of the one-part epoxy adhesive As a result, the heat resistance was good.

[Experimental example 21] (Adhesion test between CFRP piece and A7075 piece)
A large number of 45 mm × 15 mm A7075 aluminum alloy pieces (thickness 3 mm) prepared in Experimental Example 1 were prepared, and the adhesive 2 prepared in Experimental Example 19 was applied and soaked into the respective end portions for treatment. On the other hand, the adhesive 2 was applied and soaked into the roughened range of the CFRP piece (CFRP member composed only of commercially available CFRP prepreg) prepared in Experimental Example 15, and the treatment was performed. As shown in FIG. 14, the adhesive application areas of the A7075 piece and the CFRP piece were brought into close contact with each other and fixed with clips. The adhesion area (shaded area in FIG. 14) was set to about 0.5 cm ² . In the same manner as this, the A7075 piece prepared in Experimental Example 1 and the CFRP piece prepared in Experimental Example 16 (CFRP member composed of a commercially available CFRP prepreg and the CFRP prepreg of the present invention) were bonded together with the adhesive 2. . That is, the adhesive 2 is applied and soaked at the end of the A7075 piece, while the adhesive 2 is applied and soaked in the roughened area of the CFRP piece, and both adhesives are applied. The areas were brought into close contact with each other and fixed with clips.

  These were put into a hot air dryer set at 90 ° C., heated to 135 ° C. and heated for 40 minutes. Then, after heating up to 165 degreeC and heating for 30 minutes, the power supply was turned off and it stood to cool. The joined body obtained as described above was subjected to tensile fracture using a testing machine after one week, and the shear fracture strength was measured. These tests were performed at room temperature and 150 ° C. The results are shown in Table 1. The composite of CFRP piece and A7075 piece obtained in Experimental Example 15 exhibited a shear breaking force of 52.5 MPa. On the other hand, the composite of the CFRP piece and A7075 piece obtained in Experimental Example 16 exhibited a shear breaking force of 58.8 MPa. From this result, it was confirmed that the CFRP piece using the CFRP prepreg of the present invention in the bonding range shows higher adhesive strength.

  Further, even at 150 ° C., the CFRP piece using the CFRP prepreg of the present invention in the bonding range showed higher adhesive strength. The adhesive 2 used here is a one-part epoxy adhesive that is improved to improve heat resistance. The shear breaking force at 150 ° C. is as high as 15.4 MPa when the CFRP piece of Experimental Example 15 is used, and 24.8 MPa when the CFRP piece of Experimental Example 16 is used. The effect of the one-component epoxy adhesive As a result, the heat resistance was good.

[Experimental Examples 22 to 32] (Adhesion test between CFRP piece and metal alloy piece)
In place of the A7075 aluminum alloy piece, the same adhesion experiment as in Experimental Example 21 was performed using the various metal alloy pieces prepared in Experimental Examples 2-12. That is, using the adhesive 2 prepared in Experimental Example 19, the CFRP piece prepared in Experimental Example 15 and various metal alloy pieces were bonded, and the CFRP piece prepared in Experimental Example 16 and various metal alloy pieces were bonded. The experiment was conducted. The results are shown in Table 2 (Experiments 22 to 32).

  Here, when the thickness of the metal alloy piece is thin, at the time of the tensile fracture test, due to the bending stress, when the metal alloy piece originally breaks (for example, when the thickness of the metal alloy piece is 3 mm like the A7075 aluminum alloy piece) Shear fracture occurs before the time of fracture. Therefore, A5052 aluminum alloy, AZ31B magnesium alloy, C1100 copper alloy, C5191 phosphor bronze alloy, KFC copper alloy, KLF5 copper alloy, “KS40” pure titanium-based titanium alloy, “KSTi-9” α, which are thin metal alloy pieces Regarding the β-type titanium alloy and SUS304 stainless steel, a 1.6 mm-thick SPCC cold-rolled steel plate piece was bonded to the surface opposite to the bonding surface with a one-component epoxy adhesive and reinforced. FIG. 15 shows the appearance of the composite 30. Various metal alloy pieces 33 and CFRP 34 are joined via an adhesive application region 35. The bottom side of the metal alloy 33 is reinforced by SPCC cold-rolled steel plate pieces 36. Thereby, since bending strength is inadequate, it can prevent that the peeling fracture | rupture by bending will arise before a shear fracture.

  As shown in Table 2, in all the metal alloy types, the CFRP piece (Experimental Example 16) constituted by the CFRP prepreg of the present invention was compared with the CFRP piece (Experimental Example 15) constituted only by a commercially available CFRP prepreg. When bonded, it showed a high shear breaking force. By using the CFRP prepreg of the present invention in the bonding range, a high shear breaking force of about 5 to 10 MPa at room temperature and about 10 to 15 MPa at 150 ° C. was exhibited. The reason why the adhesive strength at high temperature is improved is that the heat resistance of the matrix resin is improved. Regarding “KS40” pure titanium-based titanium alloy and “KSTi-9” α-β-based titanium alloy, the shear fracture strength at room temperature is improved only by about 2 MPa. This is probably because the ideal conditions are not met.

[Experimental Example 33] (Adhesion of CFRP piece and aluminum alloy piece by cocure method)
(1) Preparation of matrix resin Epoxy resin “JER828 (manufactured by Japan Epoxy Resin Co., Ltd.)” having a molecular weight of about 370 whose main component is a monomer of bisphenol A type epoxy resin, and polyfunctional type phenol novolac type epoxy resin “JER154” "Japan Epoxy Resin Co., Ltd."), aniline-type trifunctional epoxy resin "JER630 (Japan Epoxy Resin Co., Ltd.)", tetrafunctional epoxy resin tetraglycidyldiaminodiphenylmethane "JER604 (Japan Epoxy Resin Co., Ltd.)" , Pure aluminum-based aluminum alloy powder “Aluminum powder for filler (manufactured by Toyo Aluminum Co., Ltd.)” with a particle size distribution center of 16 μm, fine powder type dicyandiamide “DICY7 (Japan Epoxy), which is a curing agent for epoxy resin Jin Co., Ltd.) ”, 3- (3,4-dichlorophenyl) -1,1-dimethylurea“ DCMU99 (manufactured by Hodogaya Chemical Co., Ltd.) ”as a curing aid, and a clay having a particle size distribution center of 15 μm. (Sintered Kaolin) “Satinton 5 (manufactured by Takehara Chemical Co., Ltd.)” was obtained.

  In a mortar, 50 parts by mass of “JER828”, 10 parts by mass of “JER154”, 20 parts by mass of “JER630” and 20 parts by mass of “JER604” were taken as 100 parts by mass of the epoxy resin mixture. 15 parts by mass of the aluminum powder “aluminum powder for filler”, 15 parts by mass of the clay “Satinton 5”, 5 parts by mass of “DICY7” as a curing agent, and “DCMU99” 3 as a curing aid. A mass part was taken. The contents of the mortar were kneaded with a pestle for 3 minutes. The mixture was allowed to stand for 1 hour and then kneaded again with a pestle for 1 minute. The pasty material was taken up in a polyethylene bottle and stored in a refrigerator at 5 ° C.

(2) Preparation of CFRP prepreg Plain weave CF cloth “Pyrofil 3110M (Mitsubishi Rayon Co., Ltd.)” having a thickness of about 0.23 mm using carbon fiber “Pyrofil TR30S (Mitsubishi Rayon Co., Ltd.)” having a tensile strength of 4.4 GPa. Was obtained and cut into 130 mm squares. The release paper using silicone resin was cut into 200 mm squares and placed on a wooden flat plate, and the four sides were fixed with tape and pins. Next, the CF cloth was laid in the center, and this was also fixed with a tape and a pin. Next, the paste-like matrix resin prepared in the above (1) was spread using a plastic spatula so as to be slightly thick and uniform from above the CF cloth. A 0.01 mm thick polyethylene film cut to 200 mm × 200 mm was placed on the coated surface. A block to be overlapped was placed at the center of the polyethylene film, and the block was moved from the center toward the end while being pressed with a constant pressure. As a result, the matrix resin oozes out to the surface of the CF cloth, and excess matrix resin is pushed out from the end of the CF cloth. Thereafter, the end of the CF cloth sandwiched between the release paper and the polyethylene film and coated with the matrix resin was cut with a cutter to prepare a 110 mm × 110 mm square sheet. The same operation was repeated to produce a large number of 110 mm × 110 mm square sheets. These square sheets were put in a desiccator and sealed, and the inside of the desiccator was decompressed with a vacuum pump and returned to normal pressure in about 5 minutes. As a result, air inside the matrix resin and the CF cloth is removed, and the matrix resin is spread over the entire CF cloth. A large number of CFRP prepregs (in a state sandwiched between release paper and polyethylene film) thus prepared were sealed in a bag and stored in a refrigerator at 5 ° C.

(3) Cocure adhesion A bonded body in which a CFRP piece and an aluminum alloy piece are adhered by a cocure method is prepared 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. On the release film 17, the surface-treated A7075 aluminum alloy piece 11 having a thickness of 45 mm × 18 mm × 3 mm obtained in Experimental Example 1 was placed. A space between the aluminum alloy piece 11 and the side wall of the mold body 2 was filled with a spacer 16 made of polytetrafluoroethylene resin (hereinafter referred to as “PTFE”).

Next, the CFRP prepreg prepared in (2) was cut into small pieces (prepreg pieces) of 42 mm × 15 mm, and the release paper and the polyethylene film were removed from each prepreg piece. Subsequently, 13 prepreg pieces were laminated on the upper surfaces of the A7075 aluminum alloy piece 11 and the spacer 16. A laminate of these 13 prepreg pieces is shown as a prepreg piece laminate 12 in the figure. Here, the left end portion of the bottom surface of the prepreg piece as the lowermost layer of the prepreg piece laminate 12 shown in FIG. 17 is in contact with the upper surface of the A7075 aluminum alloy piece 11. This bonding area is about 0.6 cm ² (15 mm × 4 mm). In order to fill the gap between the prepreg piece laminate 12 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 an iron 5 kg weight 18 was placed on the block 15 and placed in a large autoclave. The lid of the autoclave was closed to start the temperature rise, and the internal pressure was reduced with a vacuum pump to 15 mmHg or less. When the temperature of the mold body 2 reached 90 ° C., air was introduced to return to normal pressure. Thereafter, the temperature was raised and the mixture was heated at 135 ° C. for 1 hour, then further heated to 165 ° C. and heated for 20 minutes while being adjusted to maintain around 165 ° C. Thereafter, heating was stopped and the autoclave was opened. After the temperature dropped to 100 ° C., the firing jig 1 was taken out and decomposed 30 minutes later to obtain a joined body of the A7075 aluminum alloy piece 11 and the CFRP piece 12 (cured product of the prepreg piece laminate 12). In the production of this joined body, a one-component epoxy adhesive is not used. It is the matrix resin of CFRP prepreg that is used for adhesion.

  The bonded body of the aluminum alloy piece and the CFRP piece obtained as described above was subjected to a tensile fracture test using a testing machine after one week, and the shear fracture strength was measured. These tests were performed at normal temperature and 150 ° C. As a result, the shear breaking force (average of 3 pairs) was 55.3 MPa at room temperature and 32.3 MPa at 150 ° C. The shear breaking force at room temperature is not particularly high, but the shear breaking force at 150 ° C. is extremely high, which is a level that cannot be obtained with conventional CFRP prepregs. This value is close to the value when the A7075 aluminum alloy pieces are bonded to each other by NAT. This is presumably due to the use of a matrix resin excellent in heat-resistant adhesion and the use of carbon fibers having a medium tensile strength.

22 ... CFRP plate 23 ... CFRP piece 24 ... CFRP piece 30 ... composite 33 ... metal alloy piece 34 ... CFRP piece 35 ... adhesive application region 36 ... SPCC cold-rolled steel plate piece 40 ... metal alloy 41 ... ceramic layer 42 ... Adhesive cured product layer

Claims (13)

A bonded body of a CFRP prepreg made of carbon fiber and a matrix resin and an adherend,
When the epoxy resin component constituting the matrix resin is 100 parts by mass, the epoxy resin component is (1) 45 to 75 parts by mass of bisphenol A type epoxy resin mainly composed of bisphenol A type epoxy resin monomer, (2) 55 to 25 parts by mass of an epoxy resin having a polyfunctional type having 3 or more epoxy groups and an epoxy equivalent having an aromatic ring of 180 or less ,
The matrix resin, dicyandiamide powder 3 viewed 8 parts by weight containing as a curing agent,
The bonded body, wherein the CFRP prepreg is cured and bonded to the adherend via a one-component epoxy adhesive. A joined body of a CFRP prepreg and an adherend according to claim 1,
(1) The bonded product according to claim 1, wherein the bisphenol A type epoxy resin contains 0 to 15 parts by mass of a bisphenol A type epoxy resin oligomer. A bonded body of a CFRP prepreg and an adherend according to claim 1 or 2 ,
The said matrix resin contains 1-4 mass parts of 3- (3,4-dichlorophenyl) -1,1-dimethylurea as a hardening adjuvant, The said conjugate | zygote characterized by the above-mentioned . A bonded body of a CFRP prepreg and an adherend according to claim 1 selected from claims 1 to 3 ,
The matrix resin, the assembly center of particle size distribution, characterized in that it comprises 10 to 30 parts by weight of aluminum powder is 10~30μm as filler. A bonded body of a CFRP prepreg and an adherend according to claim 1 selected from claims 1 to 4 ,
The matrix resin, the assembly center of particle size distribution, characterized in that it comprises a a clay 10-30 parts by further 10~30μm as a filler. A bonded body of a CFRP prepreg and an adherend according to claim 1 selected from claims 1 to 5 ,
The adherend is also CFRP prepreg, and when the epoxy resin component constituting the matrix resin is 100 parts by mass, the epoxy resin component is (1) bisphenol A mainly composed of bisphenol A type epoxy resin monomer. 45 to 75 parts by mass of a type epoxy resin, (2) 55 to 25 parts by mass of an epoxy resin having a polyfunctional type having 3 or more epoxy groups and having an aromatic ring of 180 or less,
The matrix resin contains 3 to 8 parts by mass of dicyandiamide powder as a curing agent,
The bonded body, wherein both CFRP prepregs are cured, and then both CFRP prepregs are bonded via a one-component epoxy adhesive . A bonded body of a CFRP prepreg and an adherend according to claim 1 selected from claims 1 to 5 ,
The adherend is any one metal alloy selected from an aluminum alloy, a magnesium alloy, a copper alloy, a titanium alloy, stainless steel, and a steel material,
The surface of the metal alloy has a roughness on the order of microns in which the average length (RSm) of the contour curve element is 0.8 to 10 μm and the maximum height (Rz) is 0.2 to 5 μm, and the roughness In the plane having a degree, ultrafine irregularities with a period of 5 to 500 nm are formed, and the surface layer is a thin layer of metal oxide or metal phosphate,
The bonded body, wherein the CFRP prepreg is cured, and then the CFRP prepreg and the metal alloy are bonded via a one-component epoxy adhesive . A bonded body of a CFRP prepreg and an adherend according to claim 1 selected from claim 1,
When the one-component epoxy adhesive is 100 parts by mass of the epoxy resin contained in the adhesive,
(1) It contains 45 to 75 parts by mass of a bisphenol A type epoxy resin mainly composed of a bisphenol A type epoxy resin monomer,
(2) 55 to 25 parts by mass of an epoxy resin having a polyfunctional type having 3 or more epoxy groups and an epoxy equivalent having an aromatic ring of 180 or less,
The joined body comprising 3 to 8 parts by mass of dicyandiamide powder as a curing agent. A joined body of a CFRP prepreg and an adherend according to claim 8,
The one-component epoxy adhesive contains 1 to 4 parts by mass of 3- (3,4-dichlorophenyl) -1,1-dimethylurea as a curing aid. A bonded body of a CFRP prepreg and an adherend according to claim 8 or 9 ,
The one-component epoxy adhesive contains 10 to 30 parts by mass of aluminum powder having a particle size distribution center of 10 to 30 μm as a filler. A joined body of a CFRP prepreg and an adherend according to claim 1 selected from claims 8 to 10 ,
The one-component epoxy adhesive further includes 10 to 30 parts by mass of clay having a particle size distribution center of 10 to 30 μm as a filler. A joined body of a CFRP prepreg and an adherend according to claim 1 selected from claims 8 to 11 ,
The said one-part epoxy adhesive contains 0-30 mass parts of polyethersulfone resin powder with a hydroxyl group whose particle size distribution center is 10-30 micrometers. A joined body of a CFRP prepreg and an adherend according to claim 1 selected from claims 8 to 12 ,
The one-component epoxy adhesive further includes a polyethersulfone resin powder or a metal powder with a hydroxyl group having a particle size distribution center of 75 to 150 μm as a spacer.