JP2011156764A - Composite of metal and polyamide resin composition, and method for manufacturing same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a composite of a polyamide resin composition and a metal in which nylon 610 is major in a join portion with the metal, and a use amount of the nylon 610 is reduced in the whole resin molded article. <P>SOLUTION: A metal alloy is subjected to surface treatment to satisfy three conditions of NAT. Then the metal alloy is inserted in the first injection molding mold followed by injecting the first polyamide resin composition containing 10 to 100 mass%, based on the resin components, of the nylon 610 to obtain the first composite. The first composite is inserted in the second injection molding mold followed by injecting the second polyamide resin composition containing 90 to 100 mass%, based on the resin components, of one or more selected from nylon 6, nylon 66 and nylon 12 to obtain the final molded article. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a composite of a metal and a polyamide resin composition and a method for producing the same. In particular, metal parts made by various machining processes and molded articles of polyamide resin compositions can be firmly bonded. Cases for various electronic devices for mobile devices and housings for home appliances. It can be used for body and machine parts.

  The inventors of the present invention inject a molten engineering resin into a metal part previously inserted in an injection mold to mold a resin part, and at the same time, a method of joining the molded part and the metal part (hereinafter, Abbreviated as "injection joining"). Patent Document 1 discloses a technique for injection-bonding polybutylene terephthalate resin (hereinafter referred to as “PBT”) to an aluminum alloy, and Patent Document 2 discloses a polyphenylene sulfide resin (hereinafter referred to as “PPS”) for an aluminum alloy. The technology of injection joining is disclosed. The principle of injection joining in Patent Document 1 and Patent Document 2 will be briefly described as follows.

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

  In addition, as shown in Patent Documents 3, 4, 5, 6, and 7, the present inventors have a special exothermic reaction or assistance for any chemical reaction without chemical adsorption of amine compounds on the metal alloy surface. We found the conditions that enable injection joining without obtaining That is, for metal alloys other than aluminum alloys, a condition was found that allows the metal alloy and thermoplastic resin to be firmly joined by injection joining, and the mechanism of injection joining based on this condition was referred to as “new NMT”. .

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

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

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

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

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

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

  However, the NMT theory for an aluminum alloy is not limited to the first to third conditions. In place of these first to third conditions, the aluminum alloy surface is covered with ultrafine irregularities with a period of 20 to 80 nm, and the amine compound is chemically adsorbed on the surface. You may satisfy what.

  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. A part of the resin composition 42 has infiltrated into the ultra-fine irregularities. When the liquid resin composition penetrates into the surface of the metal alloy thus formed and is cured after the penetration, the metal alloy and the cured resin composition are joined together very firmly.

[Conditions on the resin side in the new NMT theory]
On the other hand, the resin composition that can be injection-bonded with a strong force to the surfaces of the various metal alloys subjected to the surface treatment includes a resin composition improved by compounding different polymers with PBT and PPS, as described above, and an aromatic It is the resin composition of the polyamide resin mixture containing a group polyamide (patent documents 3 to 7). Further, in order to stably maintain the bonding state between the metal alloy and the thermoplastic resin for a long period of time, it is necessary that the linear expansion coefficients of both are close. The linear expansion coefficient of the thermoplastic resin composition can be considerably reduced by containing a large amount of reinforcing fibers such as glass fibers and carbon fibers, that is, a filler, and the limit is (2-3) × 10 ^−5. ° C ^-1 . Metals close to this value near room temperature are aluminum, magnesium, copper, and silver, and steel materials and titanium alloys have a smaller linear expansion coefficient. Nevertheless, since reducing the linear expansion coefficient on the resin side is effective in reducing the difference in linear expansion coefficient between the two and maintaining the bonding force for a long period of time, addition of a filler is important.

According to the new NMT theory, for example, a composite obtained by injection-bonding PBT or PPS resin to magnesium alloy, copper alloy, titanium alloy, stainless steel, etc. has a shear breaking force of 20-30 MPa (about 200-300 kgf / cm ² ), which is confirmed to be a strong composite.

WO 03/064150 A1 (aluminum alloy) WO 2004/041532 A1 (Aluminum alloy) WO 2008/069252 A1 (magnesium alloy) WO 2008/047811 A1 (copper alloy) WO 2008/078714 A1 (titanium alloy) WO 2008/081933 A1 (stainless steel) WO 2009/011398 A1 (general steel)

  The present inventors have already disclosed a system of a polyamide resin mixture containing PBT and PPS and an aromatic polyamide as a resin that can be used for injection joining with a metal alloy as described above. However, the polyamide resin itself is not necessarily suitable as the resin used for injection joining with the metal alloy. Inexpensive and versatile polyamide resins such as nylon 6 and nylon 66, which are easy to handle as engineering plastics, such as nylon polyamide, are injection-bonded to the aluminum alloy, but the bonding strength is weak. Because there was.

  In addition, polyamide resins such as nylon 6 and nylon 66 are easily broken in an actual use environment even when they are once joined to a metal alloy due to expansion and contraction due to high water absorption. The present inventors have improved the bonding force by injection joining by using such a polyamide resin as a compound compound of polyamide resins including an aromatic polyamide resin, and after PBT and PPS as resins usable for injection joining. It can be used now. However, even when a mixed compound is used, the water absorption is higher than that of PBT and PPS as described above. If the composite obtained by injection molding an aliphatic polyamide resin suitable as an engineering plastic into a metal alloy exhibits a strong bonding force and can maintain the bonding force, the versatility of the aliphatic polyamide resin described above, It can be applied to a wide range of technical fields due to its cost.

  The present invention has been made on the basis of the above technical background, and the object thereof is a composite in which a polyamide resin composition containing an aliphatic polyamide resin as a main resin component and a metal alloy are firmly integrated by injection molding. It is in providing a body and its manufacturing technology.

  In addition, electronic device manufacturers have a desire to use heat-resistant and halogen-free resins for internal parts of electronic devices, etc. in advance of environmental problems. However, since PPS having the highest bonding strength and stability is originally synthesized from dichlorobenzene, it is very difficult to make it completely halogen-free. In addition, conventional injection joining resins such as PPS need to contain 30-50% by mass of fillers such as glass fibers in order to bring the linear expansion coefficient close to that of metals. Therefore, for example, when a chassis of an electronic device is created by injection joining and the molded product of the resin composition is used as a screw boss inside the device, it becomes a hard screw boss containing a large amount of inorganic filler. It became necessary to use it. This is because the boss breaks when a normal wood screw type screw is tightened.

  In contrast, an aliphatic polyamide resin that does not contain any aromatic polyamide resin that easily absorbs ultraviolet rays can be halogen-free even when a flame retardant is used, and its adjustment is easy. In addition, the use of aliphatic polyamide resin, which is quick and easy to use for screwing bosses, meets the demands of the demand side. In addition, since the aliphatic polyamide resin is flexible, when a screw boss is used, a normal wood screw type screw can be tightened even if it contains a little filler.

  The present invention has been made on the basis of the above technical background, and the object thereof is a polyamide resin composition that is strongly bonded by injection molding to a metal alloy, and the resin component is all aliphatic polyamide resin. And providing a composite of the polyamide resin composition and a metal alloy, and a production technique thereof.

  In order to solve the above-mentioned problems, the present inventors conducted an injection joining experiment using a polyamide resin composition in which nylon 6, nylon 66, and nylon 610 are mixed. It has been confirmed that a high bonding strength is exhibited by use. Among the polyamide resin compositions containing nylon 610, those having the maximum joining force by injection joining are those in which nylon 610 in the resin component is about 45 mass% and nylon 66 or nylon 6 is about 55 mass%. Met. This polyamide resin composition showed a very high shear breaking force of 35.8 MPa. And the polyamide resin composition which uses only nylon 610 as a resin component and does not contain glass fiber showed a shear breaking force of 20 MPa or more. From these results, the present inventors have found special suitability for nylon 610 regarding injection joining.

  However, the main use of nylon 610 is a brush part of a toothbrush, and the market distribution amount is not so much. Therefore, compared with nylon 6 and nylon 66, which are versatile, the price is 2 to 2.5 times as high. The present invention has been made to solve such problems, and its purpose is to reduce the amount of use of nylon 610 as a whole resin molded product while mainly using nylon 610 in connection with a metal. An object of the present invention is to provide a composite of a polyamide resin composition and a metal, and a manufacturing technique thereof.

  The inventors selected nylon 610 as the aliphatic polyamide resin, and used a polyamide resin composition containing this as a resin component as an injection molding resin. Thereby, the strong injection joining with the metal alloy was attained. Among the polyamide resin compositions containing nylon 610, the bonding strength with the A5052 aluminum alloy was maximized, as shown in Table 1, when nylon 610 was about 45% by mass of resin, and nylon 66 or nylon 6 was about It contained 55% by mass, and contained about 30% by mass of glass fiber in the entire resin composition.

  Further, in experiments conducted in the past, even when a resin composition consisting of only a single resin (that is, only PBT resin, only PPS resin, or only aromatic polyamide resin) is injection-molded into a surface-treated aluminum alloy, The shear fracture strength of 20 MPa or more was never exhibited. However, in an experiment conducted by the present inventors, a polyamide resin composition containing only nylon 610 as a resin component and containing no inorganic filler such as glass fiber showed a shear breaking force of 20 MPa or more. . This is a feature not found in conventional resins.

  The result of inferring the reason why nylon 610 is suitable for injection molding with a metal alloy among aliphatic polyamide resins is shown. Nylon 610 is obtained by a copolycondensation reaction of hexamethylenediamine having 6 carbon atoms and sebacic acid having 10 carbon atoms. Although the density of peptide bonds is clearly lower than that of nylon 6 and nylon 66, it is a peptide bond having a strong influence on the periphery, so that the crystallization rate at equilibrium greatly decreases with nylon 610. Cannot be assumed. On the other hand, nylon 6 is obtained by a polycondensation reaction of ε-caprolactam (carbon number 6), and nylon 66 is obtained by a co-condensation polymerization reaction of hexamethylenediamine (carbon number 6) + adipic acid (carbon number 6). Have the same carbon number. On the other hand, nylon 610 is obtained by a co-condensation polymerization reaction of hexamethylenediamine having 6 carbon atoms and sebacic acid having 10 carbon atoms. That is, the carbon numbers of both are greatly different. Therefore, it can be expected that when nylon 610 is cooled and aligned (crystallized) from the molten state, it will take more time than nylon 6 and nylon 66.

  In short, since it can be estimated that the crystallization speed of nylon 610 during quenching is significantly slower than that of nylon 6 and nylon 66, it has physical properties suitable for injection joining alone. This is thought to be confirmed by an injection joining experiment in which a polyamide composed of hexamethylenediamine and a terminal dicarboxylic acid having 9 or 11 carbon atoms is synthesized.

  Further, the injection joining of the present invention is different from the injection joining that the present inventors have performed so far. This is the difference in the breaking mode when the composite is broken with a strong force. That is, in a composite of a metal alloy and a resin (PBT or PPS, etc.) obtained by past injection joining, when the composite is broken with a strong force, the resin portion that has bite into the recess on the surface of the metal alloy is the entrance of the recess. In many cases, the resin portion that had been torn off in the vicinity and that had entered the recesses on the surface of the metal alloy remained in the metal alloy portion. However, when the composite obtained by injection joining using nylon 610 was broken, the resin portion remaining on the surface of the metal alloy after the fracture was hardly observed. That is, it is considered that the resin molded product deforms rather than breaks and peels from the surface of the metal alloy in a form of coming out of the recesses on the surface of the metal alloy.

  Nylon 610 has a lower hardness (softer) than nylon 6, nylon 66, nylon 6I (condensation polymer of hexamethylenediamine and isophthalic acid), nylon 6T (condensation polymer of hexamethylenediamine and terephthalic acid), and the like. ). Although it is clear that the source of flexibility is in the sebacic acid moiety having 10 carbon atoms, the pursuit of whether the crystal itself is soft although it is crystallized because of low crystallization rate or in the future It is a problem. However, since nylon 610 alone exhibits a relatively high shear breaking force, it can be assumed that the crystallization rate at equilibrium is not low. The amorphous polymer showed no shear rupture force in the vicinity of 20 MPa regardless of the operation. Therefore, the inventors estimated that nylon 610 has a high crystallization rate and has sufficient hardness or quickness to ensure injection joining. However, the hardness is still softer than that of PPS and PBT crystals, and if a force in the peeling direction is applied with a strong force, it may be deformed and dropped out without being cut from the recess on the metal alloy surface. Estimated.

  This point anticipated the possibility of solving problems with composites based on the hygroscopicity of polyamide resins. In general, since the hygroscopic polyamide resin expands by the amount of moisture absorption, the composite of the metal and the polyamide resin causes a strong internal strain on the joint surface, and if the hygroscopic amount is large, the joint breaks. However, the hygroscopicity of nylon 610 is about half that of nylon 66, and the hygroscopic rate is half or less. In addition, as described above, it is basically quick and somewhat soft. This quickness may be able to suppress the expansion of internal strain even during moisture absorption.

  That is, the above-mentioned aliphatic polyamide resins such as nylon 6 and nylon 66 are not only weakly bonded to the metal alloy when injection molded, but also temporarily bonded to the metal alloy due to expansion and contraction due to high hygroscopicity. Even if it was done, there was a problem that it was easily destroyed in an actual environment. The bonding strength with the metal alloy can be improved by using a mixed compound of polyamide resins in which an aromatic polyamide resin is mixed with the above aliphatic polyamide resin, but the hygroscopicity and water absorption are still higher than those of PBT and PPS. Therefore, it is difficult to maintain the bonding force. Moreover, there is a limitation that it is necessary to mix with an aromatic polyamide resin to the last, which is contrary to simplification of the process and cost reduction. On the other hand, nylon 610 has low hygroscopicity as compared with other aliphatic polyamide resins, and is quick and slightly soft. Therefore, this quickness increases the internal strain even during moisture absorption. This is considered to contribute to maintaining the bonding strength with the metal alloy.

  Here, the main use of nylon 610 is a brush part of a toothbrush, and the market distribution amount is not so much. Therefore, compared with nylon 6 and nylon 66, which are versatile, the price is 2 to 2.5 times as high. The present inventors use a polyamide resin composition mainly composed of nylon 610 for a portion directly provided for injection joining with a metal, and for portions other than the portion in the resin molded product, nylon 6 or nylon By using a polyamide resin composition mainly composed of 66, the amount of nylon 610 used as a whole resin molded product was reduced.

The present invention takes the following means in order to achieve the object.
In producing the composite of the metal alloy and the polyamide resin composition of the present invention, the average length (RSm) of the contour curve element is 0 on the surface of the metal alloy when analyzed by (1) scanning probe microscope observation. .8-10 μm, maximum height (Rz) is 0.2-5 μm, and a micron-order roughness is generated. (2) In addition, the surface having the roughness was observed with a 100,000 × electron microscope. At this time, ultrafine irregularities with a period of 5 to 500 nm are formed, and (3) surface treatment is performed to make the surface layer a thin layer of metal oxide or metal phosphate. This surface-treated metal alloy is inserted into an injection mold. In the injection molding, the present inventors applied a two-color molding method using two types of polyamide resin compositions.

[Primary molding]
First, in the primary molding, a first polyamide resin composition containing 10 to 100 mass% of nylon 610 is injected and bonded to a metal alloy inserted in a mold. The injected first polyamide resin composition penetrates into the ultra-fine irregularities and then solidifies, whereby the metal alloy and the molded product of the first polyamide resin composition are joined. The metal alloy used here is selected from, but not limited to, an aluminum alloy, a magnesium alloy, a copper alloy, a titanium alloy, stainless steel, and a steel material.

  Here, the resin component of the first polyamide resin composition may be an aliphatic polyamide resin. Nylon 610 accounted for 20 to 70% by mass of the resin content, and the balance exhibited strong bonding strength when a polyamide resin composition of nylon 66 or nylon 6 was used. Nylon 610 accounted for 30 to 50% by mass of the resin content, and the balance exhibited particularly strong bonding strength when a polyamide resin composition of nylon 66 or nylon 6 was used. The highest bonding force was exhibited when nylon 610 accounted for about 45% by mass of the resin content, and the remainder was nylon 66 or nylon 6 polyamide resin composition. The first polyamide resin composition (where nylon 610 occupies 20 to 70% by mass of resin) is made of carbon fiber, glass fiber, boron fiber, calcium carbonate, dolomite, talc, glass powder, and clay as fillers. It is preferable to include 30 to 50% by mass of the selected one or more selected from the entire resin composition. Thus, a molded product having both hardness and bonding strength is obtained.

  Moreover, as a 1st polyamide resin composition, the resin part is all aliphatic polyamide resin, Comprising: The nylon 610 occupies 80-100 mass% of the said resin part can also be used. For example, it is possible to use a polyamide resin composition in which nylon 610 accounts for 80 to 100% by mass of the resin content, and the balance is nylon 66 or nylon 6. Furthermore, a polyamide resin composition in which nylon 610 accounts for 100% by mass of the resin can also be used. The first polyamide resin composition (where nylon 610 occupies 80 to 100% by mass of resin) is made of carbon fiber, glass fiber, boron fiber, calcium carbonate, dolomite, talc, glass powder, and clay as fillers. It is preferable to include 0 to 20% by mass of the selected one or more selected from the entire resin composition.

  As shown in Table 1, as a resin composition, a resin composition using compound pellets in which nylon 66 containing glass fibers, nylon 610 not containing glass fibers, and separately added glass fibers are well dispersed and mixed with each other ( Compared to 5), the resin composition (1) obtained by dry blending nylon 66 containing glass fiber and nylon 610 not containing glass fiber showed higher injection bonding strength. This is a unique phenomenon in terms of polymer physics.

  Among the resin compositions (2) to (8) shown in Table 1, the resin composition (5) had the highest shear breaking strength (29.8 MPa), but the resin composition as a whole was a dry blend. The shear fracture strength of the composition (1) occupied the maximum value (35.8 MPa). Resin compositions (1) and (5) have the same resin composition, and the glass fiber ratio is not significantly different. However, a difference of 6 MPa occurred in the shear breaking force. This phenomenon has been reproduced in subsequent tests, and the physical properties of the resin composition change due to the uniformity of the distribution density of the filler added to the thermoplastic resin, in other words, the distribution pattern of the filler density. It is shown that.

  As a factor, it can be estimated that the molded product from the dry blend has one kind of sea-island structure. That is, a kind of hard segment portion (island portion) in which harder nylon 66 and glass fiber are gathered at a high concentration, and other portions with slightly low hardness in which nylon 66, nylon 610 and glass fiber are mixed ( It is assumed that the sea part) was completed. More simply, the existence density of the glass fibers is not completely uniform as a whole, and it can be considered that the hardness is low relative to the glass fiber addition rate as a whole, and this has been effective in improving the speed.

  From the general theory of injection molding technology, the addition rate of fillers such as reinforcing fibers and inorganic powders is directly related to the hardness, strength, linear expansion rate, molding shrinkage rate, etc. of the thermoplastic resin. However, if the filler distribution is not completely uniform dispersion but sea-island type uniform dispersion where the density of the filler existing density is an island, the degree of influence of the filler addition rate on various polymer properties can be expected to change. If the island part has a high density of reinforcing fibers, the hardness, tensile modulus, and flexural modulus will probably decrease, and the linear expansion rate, molding shrinkage rate, and water absorption rate will have a relatively small effect. We can infer that it will improve.

[Secondary molding]
Next, in the secondary molding, a second product containing 90 to 100% by mass of the resin content of one or more selected from nylon 6, nylon 66, and nylon 12 with respect to the molded product of the first polyamide resin composition. The first polyamide resin composition and the second polyamide resin composition, that is, nylon were directly fused and joined together. As the second polyamide resin composition, one containing at least one selected from nylon 6, nylon 66, and nylon 12 and having a resin content of 90 to 100% by mass and containing no filler is also used. However, it is preferable that the filler contains 10 to 50% by mass of the entire resin composition containing at least one selected from carbon fiber, glass fiber, boron fiber, calcium carbonate, dolomite, talc, glass powder, and clay. .

  In addition to the above, a mixture of an aliphatic polyamide resin and an aromatic polyamide resin can be used as the second polyamide resin composition. For example, many mixed resins of an aliphatic polyamide resin and an aromatic polyamide resin containing 5 to 80% by mass of an aromatic polyamide resin such as nylon 6I or nylon 6T are commercially available. Its characteristics are high strength and low moisture absorption, but these can also be used preferably. Furthermore, it is possible to use a resin composition containing nylon 6 or nylon 12 as a main component and containing 50 to 90% by mass of a powder magnet based on the entire resin composition. This is an injection molding material for plastic magnets.

[Method of injection joining]
When injection molding the first polyamide resin composition and the second polyamide resin composition, it is reasonable to use a two-color molding machine. Of course, using two injection molding machines, primary molding may be performed by one unit and secondary molding may be performed by another unit. Hereinafter, a molding method in the case of performing primary molding and secondary molding using two injection molding machines will be described. FIG. 10 is a cross-sectional view of an injection mold 10 for performing primary molding, FIG. 11 (a) is a plan view of a composite 30a obtained by primary molding, and FIG. 11 (b) is a side view thereof. is there. 12 is a cross-sectional view of an injection mold 20 for performing secondary molding. FIG. 13A is a plan view of a composite 30b which is a final molded product obtained by secondary molding. FIG. Is the same side view.

The composite 30b, which is the final molded product, is molded as follows. In the injection mold 10 for performing the primary molding shown in FIG. 10, the movable side mold plate 11 is first opened, and a predetermined surface treatment is performed on the cavity formed between the fixed side mold plate 12. The metal alloy piece 31 is inserted. After the insertion, the movable template 11 is closed to the state before the resin injection in FIG. Next, the first polyamide resin composition containing the melted nylon 610 is injected into the inserted cavity of the metal alloy piece 31 through the gate. When injected, the first polyamide resin composition is molded by filling the cavity while being joined to the metal alloy piece 31, and a composite 30a in which the metal alloy piece 31 and the resin molded product 32 shown in FIG. 11 are integrated is obtained. . The composite 30a has a joint surface between the metal alloy piece 31 and the resin molded product 32. In this example, the joint area is about 0.5 cm ² (5 mm × 10 mm).

  The composite 30a thus obtained is formed between the fixed mold 22 and the movable mold 21 of the injection mold 20 for performing the secondary molding shown in FIG. Insert into the cavity. After the insertion, the movable side mold plate 21 is closed to the state before the resin injection in FIG. Next, the molten second polyamide resin composition is injected through the gate into the inserted cavity of the composite 30a. When injected, the second polyamide resin composition is molded by fusing with the resin molded product 32 while filling the cavity, and the resin molded product 32 made of the first polyamide resin composition shown in FIG. The final composite 30b in which the resin molded product 33 made of the polyamide resin composition is directly fused is obtained.

  In the experimental examples to be described later, primary molding and secondary molding are performed by different injection molding machines as described above. However, it is naturally possible to perform primary molding and secondary molding using a two-color molding machine. Specifically, a plurality of shapes (here, the shape of the molded product 32 and the shape of the molded product 33) (here, the first mold and the second mold) are provided on the same fixed side template. . Then, the resin is injected into the first cavity formed by the metal alloy and the first mold in accordance with the position of the first mold in a state where the metal alloy is inserted into the movable side mold plate, and the primary mold. Molding is performed to obtain a composite 30a. Thereafter, with the composite 30a left in the movable template, the movable template is rotated to align the composite 30a with the position of the second mold, and the composite 30a (particularly the molded product 32) and the second Resin is injected into the second cavity formed by the mold 2 to perform secondary molding. Such a two-color molding method is often used and can be applied to the present invention.

  According to the present invention, it is possible to obtain a composite in which a polyamide resin composition containing an aliphatic polyamide resin suitable as an engineering plastic as a main resin component and a metal alloy are firmly integrated by injection molding. The composite of the present invention is obtained by strongly joining and integrating a polyamide resin composition containing a metal alloy and nylon 610. For example, when a metal alloy is used as a chassis of an electronic device, it is possible to injection-mold a polyamide resin composition therein, and to firmly bond the boss or rib that is the molded product to the chassis.

  According to the inventions of the present inventors in the past, metal alloy parts and PPS resins, metal alloy parts and PBT resins, metal alloy parts and polyamide resins containing an aromatic polyamide resin can be strongly injection-bonded. On the other hand, the present invention is characterized in that even when a polyamide resin composition made of an all-aliphatic polyamide resin is used, a bonding force equivalent to that obtained when the above-described resin is used can be obtained.

  In addition, since it is possible to strongly integrate the polyamide resin composition and metal alloy, which does not contain any aromatic polyamide resin that easily absorbs ultraviolet rays, and the resin component is all aliphatic polyamide resin, by injection molding, A completely halogen-free composite can be produced, contributing to environmental measures. In addition, since the aliphatic polyamide resin is flexible, when it is used as a screw boss, even if it contains some filler, it can meet the demands of the customer, such as a normal wood screw type screw can be tightened.

  Furthermore, nylon 610 has a lower hygroscopicity than other aliphatic polyamide resins, and has a quickness and is slightly soft, so this quickness suppresses the expansion of internal strain, including during moisture absorption. This contributes to maintaining the bonding strength with metal alloys. Nylon 610 occupies 100% by mass of the resin, and the entire nylon 610 resin itself, which does not contain an inorganic filler, exhibited a shear breaking force of 20 MPa under dry conditions. That is, there is no need to mix with other resins, and a high bonding force is exhibited without using a filler, which greatly contributes to shortening the manufacturing process and reducing the cost. The composite made of a metal alloy shaped article and an aliphatic polyamide resin molded product obtained by the present invention is particularly suitable for use in mobile electronic devices, home appliances, mechanical parts, etc., and is a halogen-free composite.

  In the present invention, as described above, the characteristics of nylon 610 that exhibits a strong bonding force with a metal alloy are applied, and the first polyamide resin composition containing nylon 610 and the metal alloy are integrated by injection bonding. Further, by using the second polyamide resin composition mainly containing at least one selected from nylon 6, nylon 66, and nylon 12 in addition to the joining portion, the usage ratio of expensive nylon 610 as the entire molded product The manufacturing cost can be reduced.

  According to the present invention, for example, it is possible to make a boss using nylon 610 for a joining portion of an aluminum alloy case or chassis and using nylon 66 in addition to the joining portion. That is, the molded product of nylon 66 is joined to the case and the chassis via the molded product of nylon 610 having a high joining force. Nylon resin screw bosses are extremely easy to use. In the past, the present inventors have developed a number of techniques for injection-bonding PPS resins to various metal alloy materials. For aluminum alloys and stainless steels, the injection joining technique of the present inventors has been put to practical use, and there are many cases where a screw boss is injection joined to a metal alloy chassis. At this time, there may be a problem caused by using the PPS resin.

  That is, the PPS resin used for injection joining contains a resin added for the purpose of slowing down the crystallization speed during quenching in addition to PPS, and in order to bring the linear expansion coefficient after solidification closer to that of a metal alloy. -40 mass% glass fiber is included. As a result, the solidified PPS resin is hard, and troubles such as cracking of the boss are likely to occur when a normal home appliance assembly screw is screwed into a perforated boss made of this resin. Therefore, there was a restriction that only specific screws with cut-type threads could be used.

  Compared with this, screwed bosses made of nylon 6 and nylon 66 are extremely easy to use. The characteristics of the polyamide resin itself, which has a high crystallization rate and high toughness while having a considerable hardness, are suitable for such applications. Even though the crystalline resin is crystallized, the proportion of the crystallized is less than half of the whole, and the infinite number of crystal grains having various shapes of micron level and the non-crystallized amorphous material left in the gaps between the crystals. The resin part is formed by the part. Since the crystal grains themselves appear to be hard, the resin composition including the glass fiber contained is made hard, but the amorphous part is intermingled with peptide bond polymers with strong binding force and mutual affinity, This is presumed to be a factor of strong toughness. For this reason, nylon 6 or nylon 66 perforated bosses are widely used in home appliances, electronic devices, and the like.

  Furthermore, the present invention can be applied to the production of plastic magnets. In order to obtain a high magnetic force, a plastic magnet usually has a magnet content of 80% by mass or more. Therefore, since the thermal conductivity is high, solidification is fast, and a high joining force cannot be obtained when injection joining is performed. However, some plastic magnets use nylon 6 and nylon 12 as the base resin, and if a fusion strength between these resins and a polyamide resin including nylon 610 is obtained, the nylon 610 is interposed. A composite of metal and plastic magnet can be obtained. Plastic magnets are widely used in home appliances, such as small motors, compressor solenoid valves, and automobile sliding door sensors. Joining with metal is a field that has been sought before, and the above problem can be solved by using the joining technique of the present invention.

  In this way, the present invention interposes nylon 610 for injection joining of nylon 6 and nylon 66 to a metal alloy, which has heretofore been highly hygroscopic and could not be put into practical use due to severe expansion and contraction due to moisture absorption and drying. This is possible.

FIG. 1 is a 10,000 times and 100,000 times electron micrograph of an A5052 aluminum alloy piece etched with a caustic soda aqueous solution and finely etched with a hydrated hydrazine aqueous solution. FIG. 2 is a 10,000 times and 100,000 times electron micrograph of an A7075 aluminum alloy piece etched with an aqueous caustic soda solution and finely etched with a hydrated hydrazine aqueous solution. FIG. 3 is a 100,000 times electron micrograph of an AZ31B magnesium alloy piece etched with an organic carboxylic acid aqueous solution and subjected to chemical conversion treatment with a potassium permanganate aqueous solution. FIG. 4 is a 10,000 times and 100,000 times electron micrograph of a KFC copper alloy piece etched with sulfuric acid / hydrogen peroxide aqueous solution and oxidized with sodium chlorite aqueous solution. FIG. 5 is a 10,000 times and 100,000 times electron micrograph of a pure titanium-based titanium alloy KS-40 piece etched with an aqueous hydrogen difluoride ammonium solution. FIG. 6 is a 10,000 times and 100,000 times electron micrograph of an α-β type titanium alloy KSTI-9 piece etched with an aqueous solution of 1 hydrogen difluoride ammonium fluoride. FIG. 7 is a 10,000 times and 100,000 times electron micrograph of a stainless steel SUS304 piece etched with a sulfuric acid aqueous solution. FIG. 8 is a 10,000 times and 100,000 times electron micrograph of a cold rolled steel SPCC steel piece etched with a sulfuric acid aqueous solution and subjected to chemical conversion treatment with a potassium permanganate aqueous solution. FIG. 9 is a cross-sectional view showing a surface structure when a metal alloy and a resin composition that meet the conditions of the new NMT are injection-bonded. FIG. 10 is a cross-sectional view of an injection mold for primary molding. Fig.11 (a) is a top view of the composite_body | complex obtained by primary shaping | molding, FIG.11 (b) is the same side view. FIG. 12 is a sectional view of an injection mold for performing secondary molding. FIG. 13A is a plan view of a composite body that is a final molded product obtained by secondary molding, and FIG. 13B is a side view thereof.

[Metal alloy]
As the metal alloy having the surface structure based on the above-mentioned “new NMT”, the type is not particularly limited in theory. However, “new NMT” can be applied to hard and practical metal alloys. The present inventors have confirmed that “new NMT” can be applied to metal alloy types mainly composed of aluminum, magnesium, copper, titanium, and iron. Patent Documents 1 and 2 described aluminum alloys. Patent Document 3 describes a magnesium alloy. Patent Document 4 describes a copper alloy. Patent Document 5 describes a titanium alloy. Patent Document 6 describes stainless steel. Patent Document 7 describes general steel materials. However, since “new NMT” aims to improve the bonding 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 that meets the conditions of “new NMT” 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 chemical etching methods, Patent Documents 1 and 2 describe aluminum alloys, Patent Document 3 describes magnesium alloys, Patent Document 4 describes copper alloys, Patent Document 5 describes titanium alloys, and Patent Document 6 describes stainless steel. The description about the general steel material was described in Patent Document 7.

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

(Fine etching 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 “new NMT” is provided without performing the surface hardening process or the 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 injection joining process, and the joining force decreases in a short time depending on the environment after joining. These can be prevented by chemical conversion treatment.

  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 large, the bonding force often decreases. A strong bonding force is 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. Even with a general steel material, it is considered that the bonding force 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 bonding force itself decreases. Therefore, the degree of balance depends on the purpose of use and application. Hereinafter, the surface treatment method of various metal alloys will be described in detail.

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

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

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

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

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

(Surface treatment of aluminum alloy (NMT))
The above processing is processing for satisfying the first condition to the third condition in the “new NMT”. As described above, in “NMT” for aluminum alloys, instead of the first to third conditions, the surface of the aluminum alloy is covered with ultrafine irregularities with a period of 20 to 80 nm, And what satisfy | filled the conditions that the amine compound is chemisorbing on the surface may be sufficient. When this condition is met, the chemical etching is not an essential process, and only the fine etching may be performed. However, chemical etching has the effect of further improving the bonding strength with the thermoplastic resin composition. In particular, it is effective for aluminum alloys other than 1000 series aluminum alloy (pure aluminum alloy type).

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

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

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

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

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

  FIG. 3 is a 100,000 times electron micrograph of the surface of the magnesium alloy subjected to the above treatment. Although it is difficult to express these ultra fine irregularities in text, daringly speaking, this ultra fine irregular shape has innumerable rod-like or spherical protrusions having a diameter of 5 to 20 nm and a length of 10 to 30 nm. It can be said that spherical objects having a diameter of 80 to 120 nm are irregularly stacked. The rod-like (needle-like) substance having a diameter of about 10 nm can be said to be completely crystalline from the result of observation with an electron microscope, but the diffraction line seen in manganese oxide by analysis with an X-ray diffractometer (XRD). Was not recognized.

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

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

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

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

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

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

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

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

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

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

  An analysis example of a titanium alloy etched with an aqueous solution of 1 hydrogen difluoride ammonium, washed with water, and then dried is shown. First, the scanning analysis result by the scanning probe microscope was obtained. In this case, a 20 μm square area was scanned, and RSm was 1.8 μm and Rz was 0.9 μm. Moreover, the example of the 10,000 times and 100,000 times electron micrograph of the thing which carried out the same process was shown in FIG. 5 (upper 10,000 times, lower: 100,000 times). Here, a very unique and mysterious ultra-fine concavo-convex shape in which a mountain-shaped or mountain-shaped (mountain) -shaped convex part having a height and width of 10 to 300 nm and a length of 10 nm or more is present on the entire surface with a period of 10 to 350 nm is shown. It was done.

  According to XPS analysis, large oxygen and titanium peaks were obtained, and the surface compound was clearly titanium oxide. However, the surface color tone was dark brown, and it was seen as a thin film of titanium (trivalent) oxide or a mixed oxide of titanium (trivalent) and titanium (tetravalent). That is, the surface was a metal color before etching, and this surface was a natural oxidation layer of titanium, but after etching with an aqueous hydrogen bifluoride solution, it changed to a dark titanium oxide layer that was not a natural oxidation layer. This titanium oxide layer was etched by 10 to several tens of nm with an argon ion beam, and the etched surface was subjected to XPS analysis. This XPS analysis revealed the thickness of the titanium oxide layer, which is clearly thicker than the natural oxide layer, and when pure titanium-based titanium alloy was etched with an aqueous solution of 1 hydrogen difluoride ammonium. It was considered to be 50 nm or more.

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

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

  The surface shape of an alloy other than a pure titanium-based titanium alloy etched with ammonium monohydrogen difluoride and smut-removed is a surface shape whose surface shape is difficult to express in language compared to the above-mentioned photograph of FIG. become. An example of an α-β type titanium alloy containing aluminum is shown in the photograph of FIG. 6 (top: 10,000 times, bottom: 100,000 times). Here, a smooth dome-like part without ultra-fine irregularities (similar to FIG. 5), which looks like a titanium alloy, was observed, but a mysterious shape like a dead leaf of a plant was observed. The entire surface is not covered with ultrafine irregularities having a period of 10 to 300 nm, which is preferable as the second condition described above, but a surface with a longer period (called “fine irregularities”) is observed. The unevenness itself was smooth.

  However, apart from the smooth dome-shaped portion in this surface, the dead leaf shape portion is thin and curved, and if it has hardness, it becomes a strong spike shape. The surface of the α-β type titanium alloy almost does not meet the second condition (ultra-fine irregularities with a period of 5 nm to 500 nm) in the new NMT described above. It is thought that it can play the role of unevenness. Since the spike shape of the surface is large, it is rather related to the micron-order roughness (surface roughness) required under the first condition required by the new NMT. With this spike shape, a roughness surface that satisfies the first condition (RSm is 0.8 to 10 μm, Rz is 0.2 to 5 μm) as viewed with a scanning probe microscope is formed. In addition, since it slightly deviates from the second condition and the concavo-convex period is large, the whole surface image cannot be grasped with an electron micrograph of 100,000 times. The surface was observed by taking a magnification photograph of 10,000 times or less. In other words, as shown in FIG. 6 (upper), the area is at least 10 μm square or more when viewed with a 10,000 × electron microscope. By doing so, a fine uneven shape in which both a smooth dome shape and a curved dead leaf shape are present is observed. From the analysis by XPS, it was confirmed that the surface layer was a thin layer of metal oxide containing titanium and aluminum.

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

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

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

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

  An example in which stainless steel is actually chemically etched with a sulfuric acid aqueous solution is shown in FIG. A micron-order roughness is formed on the surface by appropriate etching. When the surface is observed with an electron microscope, it can be seen that the surface is covered with ultrafine irregularities. In short, in stainless steel, fine etching is achieved at the same time by chemical etching alone. In FIG. 7, a shape in which particles having a diameter of 20 to 70 nm, indefinite polygonal shapes, and the like are stacked is recognized. This 10,000 times photograph (FIG. 7 (upper)) and 100,000 times photograph (FIG. 7 (lower)). Both of them were very similar to the lava field on the slope of the lava plateau formed by lava flowing around the volcano. When XPS analysis was performed on the surface of stainless steel covered with ultra-fine irregularities, large peaks of oxygen and iron and small peaks of nickel, chromium, carbon, and molybdenum were recognized. In short, the surface is an oxide of a metal having exactly the same composition as that of ordinary stainless steel, and is covered with a similar corrosion resistant surface.

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

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

<Surface treatment method I: Chemical etching only>
After the chemical etching described above, it is washed with water, dried, and observed with an electron micrograph. Ultra fine irregularities with a height and depth of 50 to 500 nm and a width of several hundred to several thousand nm followed by infinite steps. Often, the shape covers almost the entire surface. This seems to have exposed the pearlite structure that steel materials generally have. Specifically, when an aqueous sulfuric acid solution is used under appropriate conditions in the chemical etching step, an uneven surface having a roughness on the order of microns can be obtained, and at the same time, stepped ultrafine unevenness can be formed simultaneously. Many. In this way, when the formation of micron order roughness and ultra-fine irregularities is made at once, the water that has been sufficiently washed after the chemical etching and then drained and rapidly dried at a high temperature of 90-100 ° C. or more Can be used as is. Rust on the surface does not appear and it becomes a beautiful natural oxide layer.

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

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

  In any case, the adsorption or reaction of these amine-based molecules seems to have priority over the adsorption of water molecules and the iron hydroxide formation reaction. In that sense, at least for several days to several weeks until injection joining is performed, the adsorption of moisture and the generation of rust due to the reaction can be suppressed. In addition, the maintenance of the bonding force was also superior to “Surface Treatment Method I”, and the bonding force did not decrease when the bonded body was left for 4 weeks.

  The concentration and temperature of the aqueous ammonia, the aqueous hydrazine solution, or the aqueous solution of the water-soluble amine to be used need almost no strict conditions. Specifically, an effect can be obtained by using an aqueous solution having a concentration of 0.5 to several percent at room temperature, immersing for 0.5 to several minutes, washing with water, and drying. Industrially, ammonia water having a concentration of about 1%, which is slightly odorous but inexpensive, or a 1% to several percent aqueous solution of hydrated hydrazine having a small odor and a stable effect is preferable.

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

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

[Joint experiment]
The results of an injection joining experiment using an aliphatic polyamide resin are 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 A dynamic force scanning probe microscope “SPM-9600 (manufactured by Shimadzu Corporation)” was used.
(D) X-ray diffraction analysis (XRD analysis)
“XRD-6100 (manufactured by Shimadzu Corporation)” was used.
(E) Measurement of composite bond strength The composite was pulled with a tensile tester to apply a shearing force, and the breaking force when the composite broke was measured as the shear breaking force. “MODEL-1323 (manufactured by Aiko Engineering Co., Ltd., Japan)” was used as a tensile tester, and the shear breaking strength was measured at a tensile speed of 10 mm / min.

[Experimental Example 1] (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 treated in the same manner as described above was observed with an electron microscope, it was found that the A5052 piece was covered with a recess having a diameter of 30 to 100 nm. A photograph 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 1.8 to 2.6 μm, and Rz was 0.3 to 0.5 μm.

[Experimental Example 2] (Surface treatment of A7075 aluminum alloy piece)
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 in the same manner as described above was observed with an electron microscope, it was found that the A7075 piece was covered with a recess having a diameter of 40 to 100 nm. A photograph 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 3-4 μm, and Rz was 1-2 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 degreasing agent for magnesium alloy “Cleaner 160 (manufactured by Meltex Co., Ltd.)” was added to the water in the tank to prepare an aqueous solution (65 ° C.) having a concentration of 7.5%. The AZ31B piece was immersed in this for 5 minutes and washed thoroughly with water. Subsequently, a 1% strength aqueous hydrated citric acid solution (40 ° C.) was prepared in another tank, and the AZ31B piece was dipped in this for 6 minutes and washed with water. Next, an aqueous solution (65 ° C.) containing 1% concentration sodium carbonate and 1% concentration sodium hydrogen carbonate was prepared in another tank, and the AZ31B piece was immersed in this for 5 minutes and washed with water. Subsequently, a 15% strength aqueous caustic soda solution (65 ° C.) was prepared in another tank, and the AZ31B piece was immersed in this for 5 minutes and washed with water. Next, a 0.25% strength aqueous hydrated citric acid solution (40 ° C.) was prepared in another tank, and the AZ31B piece was immersed in this for 1 minute and washed with water. Next, an aqueous solution (45 ° C.) containing 2% potassium permanganate, 1% acetic acid and 0.5% hydrated sodium acetate was prepared, and the AZ31B piece was immersed in this for 1 minute and washed with water for 15 seconds. Next, the AZ31B piece was placed in a hot air dryer set at 90 ° C. for 15 minutes and dried.

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

[Experimental Example 4] (Surface treatment of KFC copper alloy piece)
A commercially available iron-containing copper alloy sheet “KFC (manufactured by Kobe Steel, Ltd.)” having a thickness of 1.5 mm was obtained and cut to prepare 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.

  A KFC piece treated in the same manner as described above was applied to a scanning probe microscope. As a result, RSm was 1.5-2 μm and Rz was 0.2-0.5 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 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 5] (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.

  A KS40 piece treated in the same manner as described above was observed with a scanning probe microscope. As a result, RSm was 3 to 4 μm and Rz was 1 to 2 μm. Most of the unevenness of individual irregularities was 0.5 to 1.5 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). 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 6] (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 black smut was attached to the KSTi-9 piece, the smut was dropped by immersing in a 3% nitric acid aqueous solution (40 ° C.) for 3 minutes and then immersing in ion-exchanged water subjected to ultrasonic waves for 5 minutes. . Thereafter, 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. 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). In addition to the portion very similar to FIG. 5 of Experimental Example 5, many dead leaf-like portions that were difficult to express were seen.

[Experimental Example 7] (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 (60 ° C.) containing 10% of 98% sulfuric acid was prepared in another tank, and the SUS304 piece was immersed in this for 5 minutes and washed thoroughly with ion-exchanged water. Next, the SUS304 pieces were immersed in a 5% aqueous hydrogen peroxide solution (40 ° C.) for 5 minutes and washed with water. Next, the SUS304 pieces were placed in a hot air dryer at 90 ° C. for 15 minutes and dried.

  A SUS304 piece treated in the same manner as described above was observed with a scanning probe microscope. According to scanning analysis, the interval between peaks and valleys was 2 to 6 μm, RSm was around 4 μm, and Rz was 0.2 to 1 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). From observation with an electron microscope, the surface is covered with a shape in which particles having a diameter of 20 to 70 nm and indefinite polygonal shapes are stacked, that is, a lava plateau slope-like ultra-fine uneven shape, and the coverage is about 90%. 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 8] (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 in the same manner as described above was observed with a scanning probe microscope. According to scanning analysis, RSm was 1 to 3 μm and Rz was 0.3 to 1.0 μm. Photographs obtained by observing the electron microscope at 10,000 times and 100,000 times are shown in FIG. 8 ((a): 10,000 times, (b): 100,000 times). From the result of observation with a 100,000 times electron microscope, it is found that the entire surface is almost entirely covered with an ultra fine uneven shape having a height and depth of 50 to 500 nm and a width of several hundred to several thousand nm that is infinitely continuous. I understand. It can be seen that the pearlite structure is exposed and the chemical conversion treatment layer is very thin.

[Experimental Example 9] (Preparation of resin composition (1))
Nylon 66 resin “Amilan CM3001G45 (manufactured by Toray Industries, Inc.)” containing 45% glass fiber and commercially available nylon 610 resin “Amilan 2001 (manufactured by Toray Industries, Inc.)” free of glass fibers was obtained. 70 parts by mass of “Amilan CM3001G45” and 30 parts by mass of “Amilan 2001” were mixed in a Henschel mixer. As a result, nylon 66 accounted for 56% by mass of nylon 66 and 44% by mass of nylon 610, and a resin composition containing 31.5% by mass of glass fiber was obtained. However, since it was a dry blend, it was expected that how far the nylons and the glass fibers were uniformly mixed would be influenced by the operation method of the injection molding machine. This was designated as a resin composition (1).

[Experimental Example 10] (Injection joining test with A5052 aluminum alloy)
As shown in FIG. 10, the A5052 piece subjected to the surface treatment of Experimental Example 1 is inserted into an injection mold for primary molding heated to 140 ° C., and the resin prepared in Experimental Example 9 is used for this A5052 piece. Composition (1) was injected at an injection temperature of 280 ° C. Thus, a composite 30a in which the A5052 piece 31 and the molded product 32 of the resin composition (1) shown in FIG. 11 were joined was obtained. The bonding area of this composite 30a was 0.5 cm ² .

Next, as shown in FIG. 12, the composite 30a is inserted into an injection mold for secondary molding within one hour after the primary molding, and 45% of glass fiber is contained in the resin molded product portion 32. Nylon 66 resin “Amilan CM3001G45 (manufactured by Toray Industries, Inc.)” was injected at an injection temperature of 280 ° C. Thus, a composite 30b was obtained in which a molded product 33 of nylon 66 resin was joined to a molded product 32 of the resin composition (1) shown in FIG. Here, the bonding area between the molded product 32 of the resin composition (1) and the molded product 33 of the nylon 66 resin is 0.15 cm ² (width 5 mm × height 3 mm).

  Within 4 hours from the secondary molding, the composite 30b as the final molded product was aged in a hot air dryer set at 150 ° C. for 1 hour and allowed to cool. This aging is an operation often performed at the time of injection joining, and the purpose thereof is to remove internal strain of the joint surface caused by molding shrinkage of each material after shrinkage caused by injection joining or cooling due to cooling. Three days after the secondary molding, the three composites 30b were broken with a tensile tester, and the tensile breaking strength was measured. As a result, an average of three pieces showed a tensile breaking force of 18 MPa. For all the composites 30b, the fracture occurred at the joint portion between the molded product 32 of the resin composition (1) and the molded product 33 of the nylon 66 resin.

[Experimental Examples 11 to 17] (Injection joining test with various metal alloys)
In place of the A5052 piece, using the A7075 piece, the AZ31B piece, the KFC piece, the KS40 piece, the KSTi-9 piece, the SUS304 piece, and the SPCC piece subjected to the surface treatment of Experimental Examples 2 to 8, the same as the Experimental Example 10 The experiment was conducted. The results are shown in Table 2. In all the experiments, the fracture occurred at the joint between the molded product 32 of the resin composition (1) and the molded product 33 of the nylon 66 resin. This is because the bonding area of the resin fusion is only 0.15 cm ² , which is smaller than the bonding area of 0.5 cm ² between the metal alloy piece 31 and the molded product 32 of the resin composition (1). That is, for all the composites, the results were the same as measuring the heat fusion force between two types of resin molded products. As shown in Table 2, the tensile breaking force was in the range of 17.2 to 19.3 MPa, and the variation was small.

  In the present invention, as shown in Table 1 described above, the first polyamide resin composition containing various metal alloys and nylon 610 can be firmly bonded. This is due to the use of the characteristics of nylon 610. As a result of the strong bonding between the two, the bonding strength between the first polyamide resin composition and nylon 66 becomes a problem. In the results shown in Table 2, since any composite showed a high breaking force of around 18 MPa, only the joint portion with the metal alloy is made of nylon 610, and the other resin portion is made of nylon 6 or nylon. The composite composed of 66 can be used for many applications.

[Experiment 18] (Injection test with aluminum alloy)
As shown in FIG. 10, the A5052 piece subjected to the surface treatment of Experimental Example 1 is inserted into an injection mold for primary molding heated to 140 ° C., and the resin prepared in Experimental Example 9 is used for this A5052 piece. Composition (1) was injected at an injection temperature of 280 ° C. Thus, a composite 30a in which the A5052 piece 31 and the molded product 32 of the resin composition (1) shown in FIG. 11 were joined was obtained. The bonding area of this composite 30a was 0.5 cm ² .

Next, as shown in FIG. 12, the composite 30a is inserted into an injection mold for secondary molding within 1 hour after the primary molding, and the magnet is 80% by mass with respect to the resin molded product portion 32. The contained nylon 12 was injected at an injection temperature of 280 ° C. As a result, a composite 30b was obtained in which a molded product 33 of nylon 12 resin was joined to a molded product 32 of the resin composition (1) shown in FIG. Here, the joint area between the molded product 32 of the resin composition (1) and the molded product 33 of the nylon 12 resin is 0.15 cm ² (width 5 mm × height 3 mm).

  Within 4 hours from the secondary molding, the composite 30b as the final molded product was aged in a hot air dryer set at 150 ° C. for 1 hour and allowed to cool. This aging is an operation often performed at the time of injection joining, and the purpose thereof is to remove internal strain of the joint surface caused by molding shrinkage of each material after shrinkage caused by injection joining or cooling due to cooling. Three days after the secondary molding, the three composites 30b were broken with a tensile tester, and the tensile breaking strength was measured. As a result, an average of three pieces showed a tensile breaking force of 15 MPa. Regarding all the composite bodies 30b, the fracture occurred at the joint portion between the molded product 32 of the resin composition (1) and the plastic magnet molded product 33.

[Experimental Examples 19 to 25] (Injection joining test with various metal alloys)
In place of the A5052 piece, using the A7075 piece, the AZ31B piece, the KFC piece, the KS40 piece, the KSTi-9 piece, the SUS304 piece, and the SPCC piece subjected to the surface treatment of Experimental Examples 2 to 8, the same as the Experimental Example 18 The experiment was conducted. The results are shown in Table 3. In all the experiments, the fracture occurred at the joint portion between the molded product 32 of the resin composition (1) and the plastic magnet molded product 33. This is because the bonding area of the resin fusion is only 0.15 cm ² , which is smaller than the bonding area of 0.5 cm ² between the metal alloy piece 31 and the molded product 32 of the resin composition (1). That is, for all the composites, the results were the same as measuring the heat fusion force between two types of resin molded products. As shown in Table 3, the tensile breaking force was in the range of 13.2 to 16.8 MPa, and the variation was small.

  In the present invention, as shown in Table 1 described above, the first polyamide resin composition containing various metal alloys and nylon 610 can be firmly bonded. This is due to the use of the characteristics of nylon 610, and as a result of the strong bonding between the two, the bonding force between the first polyamide resin composition and the nylon 12 resin becomes a problem. In the results shown in Table 2, since any composite showed a high breaking force of about 15 MPa, only the joint portion with the metal alloy is made of nylon 610, and the other resin portion is made of a plastic magnet. The resulting composite can be used for many applications.

10: Injection mold (for primary molding)
20: Injection mold (for secondary molding)
30a: Composite 30b: Final composite 31: Metal alloy piece 32: First polyamide resin composition 33: Second polyamide resin composition 40: Metal alloy 41: Ceramic layer 42: Resin composition

Claims (17)

A composite of a metal and a polyamide resin composition,
The surface of the metal 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. 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 polyamide resin composition comprises a molded product of a first polyamide resin composition containing 10% to 100% by mass of nylon 610, and one or more selected from nylon 6, nylon 66, and nylon 12 as a resin component. A molded product of the second polyamide resin composition containing 90 to 100% by mass of
The first polyamide resin composition is solidified in a state of intruding into the ultra-fine irregularities, whereby the molded product of the first polyamide resin composition and the metal are firmly bonded, and the second The molded article of the polyamide resin composition is bonded to the molded article of the first polyamide resin composition. In the composite of the metal and the polyamide resin composition according to claim 1,
The composite is characterized in that the metal is any one selected from an aluminum alloy, a magnesium alloy, a copper alloy, a titanium alloy, stainless steel, and a steel material. A composite of a metal and a polyamide resin composition,
The metal is an aluminum alloy,
The surface is covered with ultra fine irregularities with a period of 20 to 80 nm, and the nitrogen element is adsorbed on the surface,
The polyamide resin composition comprises a molded product of a first polyamide resin composition containing 10% to 100% by mass of nylon 610, and one or more selected from nylon 6, nylon 66, and nylon 12 as a resin component. A molded product of the second polyamide resin composition containing 90 to 100% by mass of
The first polyamide resin composition is solidified in a state of intruding into the ultra-fine irregularities, whereby the molded product of the first polyamide resin composition and the metal are firmly bonded, and the second The molded article of the polyamide resin composition is bonded to the molded article of the first polyamide resin composition. A composite of a metal and a polyamide resin composition,
The metal is an α-β type titanium alloy,
The surface has a roughness on the order of microns with an average length (RSm) of the contour curve elements of 0.8 to 10 μm, a maximum height (Rz) of 0.2 to 5 μm, and an area of 10 μm square Fine irregularities in which both a smooth dome shape and a curved dead leaf shape are present are formed, and the surface layer is a thin layer of metal oxide mainly containing titanium and aluminum,
The polyamide resin composition comprises a molded product of a first polyamide resin composition containing 10% to 100% by mass of nylon 610, and one or more selected from nylon 6, nylon 66, and nylon 12 as a resin component. A molded product of the second polyamide resin composition containing 90 to 100% by mass of
The first polyamide resin composition is solidified in a state of entering the fine irregularities, whereby the molded product of the first polyamide resin composition and the metal are firmly joined, and the second polyamide resin The molded article of the resin composition is bonded to the molded article of the first polyamide resin composition. In the composite of the metal and the polyamide resin composition according to claim 1 selected from claims 1 to 4,
The composite according to claim 1, wherein the first polyamide resin composition is an aliphatic polyamide resin. In the composite of the metal and the polyamide resin composition according to claim 5,
The resin component in the first polyamide resin composition is characterized in that nylon 610 occupies 10 to 70% by mass of the resin component, and the balance is one or more selected from nylon 66 and nylon 6. Said complex. In the composite of the metal and the polyamide resin composition according to claim 5,
The resin component in the first polyamide resin composition is characterized in that nylon 610 occupies 20 to 70% by mass of the resin component, and the balance is one or more selected from nylon 66 and nylon 6. Said complex. In the composite of the metal and the polyamide resin composition according to claim 5,
The resin content in the first polyamide resin composition is characterized in that nylon 610 occupies 30 to 50% by mass of the resin content, and the remainder is one or more selected from nylon 66 and nylon 6. Said complex. In the composite of the metal and the polyamide resin composition according to claim 5,
The composite in which the resin component in the first polyamide resin composition is such that nylon 610 occupies 80 to 100% by mass of the resin component. In the composite of the metal and the polyamide resin composition according to claim 5,
The resin component in the first polyamide resin composition is characterized in that nylon 610 accounts for 80 to 100% by mass of the resin component, and the balance is one or more selected from nylon 66 and nylon 6. Said complex. In the composite of the metal and the polyamide resin composition according to claim 5,
The resin component in the first polyamide resin composition is characterized in that nylon 610 accounts for 100% by mass of the resin component, and the first polyamide resin composition does not contain a filler. Said complex. In the composite of the metal and the polyamide resin composition according to claim 6,
In the first polyamide resin composition, at least one selected from carbon fiber, glass fiber, boron fiber, calcium carbonate, dolomite, talc, glass powder, and clay is used as a filler. The composite comprising the mass%. In the composite of the metal and the polyamide resin composition according to claim 9,
The first polyamide resin composition contains, as a filler, one or more selected from carbon fiber, glass fiber, boron fiber, calcium carbonate, dolomite, talc, glass powder, and clay, and 0-20 of the entire resin composition. The composite comprising the mass%. In the composite of the metal and the polyamide resin composition according to claim 1 selected from claims 1 to 4,
In the second polyamide resin composition, as a filler, at least one selected from carbon fiber, glass fiber, boron fiber, calcium carbonate, dolomite, talc, glass powder, and clay is used as 10 to 50 of the entire resin composition. The composite comprising the mass%. In the composite of the metal and the polyamide resin composition according to claim 1 selected from claims 1 to 4,
Said 2nd polyamide resin composition contains 90-100 mass% of resin parts for 1 or more types selected from nylon 6 and nylon 12, and contains 50-90 mass% of powder magnets with respect to the whole resin composition. Said complex. 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 is generated on the surface of the metal, and the roughness A surface treatment step of performing surface treatment for forming ultrafine irregularities with a period of 5 to 500 nm in a plane having a surface layer and forming a surface layer as a thin layer of metal oxide or metal phosphate,
A first insert step of inserting the metal that has undergone the surface treatment step into a first injection mold;
On the surface of the inserted metal, a first polyamide resin composition containing 10% to 100% by mass of nylon 610 is injected, and the injected first polyamide resin composition penetrates into the ultra-fine irregularities. And then solidifying to obtain a first composite in which the metal and the molded product of the first polyamide resin composition are joined;
A second insert step of inserting the first composite into a second injection mold;
90 to 100 mass of resin component of at least one selected from nylon 6, nylon 66 and nylon 12 with respect to the molded article of the first polyamide resin composition constituting the inserted first composite. A second joining step of injecting a second polyamide resin composition containing 1% and fusing with the molded article;
A method for producing a composite of a metal and a polyamide resin composition, comprising: 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 is generated on the surface of the metal, and the roughness A surface treatment step of performing surface treatment for forming ultrafine irregularities with a period of 5 to 500 nm in a plane having a surface layer and forming a surface layer as a thin layer of metal oxide or metal phosphate,
An insert step of inserting the metal that has undergone the surface treatment step into a movable side mold plate of an injection mold;
A first cavity formed by a combination of the inserted metal and a first mold provided on a fixed-side mold plate of the injection mold includes nylon 610 containing 10 to 100% by mass of resin. 1 polyamide resin composition is injected, and after the injected polyamide resin composition penetrates into the ultra-fine irregularities, the metal and the molded article of the first polyamide resin composition are joined, A first joining step in which a composite of 1 is obtained;
After the first joining step, the first composite is moved to a position of a second mold provided on the fixed-side template while the first composite is fixed to the movable-side template. Moving process;
One or more types selected from nylon 6, nylon 66, and nylon 12 in the second cavity formed by the combination of the molded product of the first polyamide resin composition and the second mold after the moving step. A second bonding step of injecting a second polyamide resin composition containing 90 to 100% by mass of a resin component and fusing the molded product with the second polyamide resin composition;
A method for producing a composite of a metal and a polyamide resin composition, comprising: