Metal resin bonded body

Abstract

To provide a metal resin bonded body in which a metal member and a resin member are bonded with high bonding strength.SOLUTION: The metal resin bonded body comprises: a metal member having a joining surface made of metal; and a resin member having a joining surface made of polyamide, wherein the joining surface of the metal member and the joining surface of the resin member are represented by the following formula (1): [wherein R1 to R3 each independently represent a hydrogen atom, a halogen atom, a hydroxyl group, or a linear or branched alkoxy group which may contain a heteroatom; R4 represents a divalent organic group having one or more carbon atoms which may contain a heteroatom; R5 represents a monovalent organic group having one or more carbon atoms which may contain a heteroatom; and m and n each independently represent an integer from 1 to 15], and are bonded via a silane coupling agent in which a structural unit [-NH-(CH2)m-C(=O)-] in the formula (1) has the same structure as a repeating unit of the polyamide.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a metal-resin bonded body, and more particularly to a metal-resin bonded body in which a metal member and a polyamide resin member are bonded together. [Background technology]

[0002] In the development of high-performance, multifunctional components and products, it is effective to combine materials with different functions and properties. In particular, in the automotive, railway, and aircraft fields, there is a demand for lighter parts from the perspective of improving fuel efficiency, and the replacement of some metal components with resins is being considered. However, since the properties of metal and resin components are significantly different, it is not easy to directly bond them. Conventional methods for bonding metal and resin components include indirect bonding using a primer or adhesive, and direct bonding using the anchor effect of forming a fine uneven structure on the surface of the metal component.

[0003] For example, Japanese Patent Laid-Open Publication No. 2016-117228 (Patent Document 1) describes a metal-resin bonded structure in which a resin member containing a polyamide having a melting point within a specific range and a metal member are bonded via a primer layer containing a polyamide having a melting point lower than that of the polyamide contained in the resin member. Furthermore, International Journal of Adhesion & Adhesives, 2021, Vol. 109, pp. 102906 (Non-Patent Document 1) describes a metal-resin bonded structure in which the surface of an aluminum plate is treated with hot water to form a micro-relief structure, the surface having this micro-relief structure is treated with 3-(2-aminoethylamino)propyltrimethoxysilane, a silane coupling agent, and polyamide 6 is thermocompression-bonded to the surface treated with this silane coupling agent. However, these metal-resin bonded structures do not necessarily achieve sufficient bonding strength. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-117228 [Non-patent literature]

[0005] [Non-Patent Document 1] International Journal of Adhesion & Adhesives, 2021, Volume 109, 102906 Summary of the Invention [Problem to be solved by the invention]

[0006] The present invention has been made in view of the problems with the prior art described above, and has an object to provide a metal-resin joined body in which a metal member and a resin member are joined with high joining strength. [Means for solving the problem]

[0007] As a result of extensive research to achieve the above object, the present inventors have discovered that when joining a metal member and a polyamide resin member via a silane coupling agent, by using a silane coupling agent having the same structural unit as the repeating unit of the polyamide, a metal-resin joined body in which the metal member and the polyamide resin member are joined with high joining strength can be obtained, and have completed the present invention.

[0008] That is, the present invention provides the following aspects. [1] A metal member having a joining surface made of a metal selected from the group consisting of metals, and a resin member having a joining surface made of polyamide, The joining surface of the metal member and the joining surface of the resin member have a viscosity expressed by the following formula (1):

[0009] [ka]

[0010] [wherein R 1 ~R 3 each independently represents a hydrogen atom, a halogen atom, a hydroxy group, or a linear or branched alkoxy group which may contain a heteroatom; R 4 represents a divalent organic group having one or more carbon atoms which may contain a heteroatom, and R 5 represents a monovalent organic group having one or more carbon atoms which may contain a heteroatom, and m and n each independently represent an integer of 1 to 15. The structural unit [—NH—(CH) m a metal-resin bonded body in which the repeating unit [—C(═O)—] is bonded via a silane coupling agent having the same structure as the repeating unit of the polyamide. [2] In the formula (1), R 4 is a divalent organic group containing a nitrogen atom or an oxygen atom and having one or more carbon atoms, and R 5 is a monovalent organic group having one or more carbon atoms and containing a nitrogen atom or an oxygen atom. [3] In the formula (1), R 4 Ga-NH-R 41 - [wherein R 41 represents a divalent hydrocarbon group having one or more carbon atoms, and R 5 R 51 —OC(═O)— (wherein R 51 represents a monovalent hydrocarbon group having one or more carbon atoms. [4] The metal resin joined body according to any one of [1] to [3], wherein the metal constituting the joining surface of the metal member is aluminum or an aluminum alloy. [5] The metal-resin joined body according to any one of [1] to [4], wherein the polyamide constituting the joining surface of the resin member is at least one selected from the group consisting of polyamide 6, polyamide 11, and polyamide 12. [6] The metal-resin bonded body according to any one of [1] to [5], wherein the bonding surfaces of the metal members are treated with a solution containing the silane coupling agent at a concentration of 15 to 150 mmol / L. [7] The method for producing a metal-resin bonded body according to any one of [1] to [6], comprising treating the bonding surfaces of the metal members with a solution containing the silane coupling agent, and then bonding the bonding surfaces of the metal members and the bonding surfaces of the resin members via the silane coupling agent. [8] The method for producing a metal-resin bonded body according to [7], wherein the concentration of the silane coupling agent in the solution containing the silane coupling agent is 15 to 150 mmol / L.

[0011] Although the reason why the present invention enables a metal member and a resin member to be bonded with high bonding strength is not entirely clear, the inventors speculate as follows. That is, in the metal-resin bonded body of the present invention, a metal member and a resin member are bonded via a silane coupling agent, and the silane coupling agent has the same structural unit as the repeating unit of the polyamide that constitutes the bonding surface of the resin member. In such a metal-resin bonded body, it is speculated that the metal member and the resin member are bonded with high bonding strength because an amide group in the repeating unit of the polyamide and an amide group in the structural unit of the silane coupling agent form a hydrogen bond. [Effects of the Invention]

[0012] According to the present invention, it is possible to obtain a metal-resin bonded body in which a metal member and a resin member are bonded with high bonding strength via a silane coupling agent. [Brief explanation of the drawings]

[0013] [Figure 1A] 1 is a scanning electron microscope photograph (50,000 magnifications) showing the surface of an aluminum plate pretreated in Preparation Example 1. [Figure 1B] 1 is a scanning electron microscope photograph (5,000 magnifications) showing the surface of an aluminum plate pretreated in Preparation Example 1. [Figure 2] 1 is a graph showing the 1H-NMR spectrum of the polyamide 6 (PA6) oligomer (n=1) silane coupling agent obtained in Synthesis Example 1. [Figure 3] 1 is a graph showing the 1H-NMR spectrum of the polyamide 6 (PA6) oligomer (n=2) silane coupling agent obtained in Synthesis Example 2. [Figure 4] 1 is a graph showing a 1H-NMR spectrum of a polyamide 6 (PA6) oligomer (n=4) silane coupling agent obtained in Synthesis Example 3. [Figure 5] 1 is a graph showing the tensile strength of metal-resin bonded bodies produced in Examples 1 to 3 and Comparative Examples 1 and 2. [Figure 6] 1 is a graph showing the relationship between the concentration of a silane coupling agent and the tensile strength of a metal-resin bonded body. DETAILED DESCRIPTION OF THE INVENTION

[0014] The present invention will be described in detail below based on preferred embodiments thereof.

[0015] The metal-resin bonded body of the present invention includes a metal member having a bonding surface made of metal and a resin member having a bonding surface made of polyamide, The joining surface of the metal member and the joining surface of the resin member have a viscosity expressed by the following formula (1):

[0016] [ka]

[0017] [wherein R 1 ~R 3 each independently represents a hydrogen atom, a halogen atom, a hydroxy group, or a linear or branched alkoxy group which may contain a heteroatom; R 4 represents a divalent organic group having one or more carbon atoms which may contain a heteroatom, and R 5 represents a monovalent organic group having one or more carbon atoms which may contain a heteroatom, and m and n each independently represent an integer of 1 to 15. The structural unit [—NH—(CH) mThe polyamide resin is bonded with high bonding strength via a silane coupling agent having the same structure as the repeating unit of the polyamide.

[0018] (Metal parts) The metal member used in the present invention has at least a joining surface made of metal, and the entire metal member may be made of metal. The metal is a metal capable of having hydroxyl groups on the joining surface, such as aluminum, titanium, silicon, tin, germanium, or zirconium, or an alloy such as aluminum alloy, SUS, ITO (indium tin oxide), or PZT (lead zirconate titanate), or a mixture of these metals with alloys, or a metal to which a single element such as carbon or phosphorus or various compounds has been added to exhibit various physical properties, such as increased mechanical strength. When the metal is a metal capable of having hydroxyl groups on the joining surface, the joining strength between the metal member and the resin member is improved. Among these metals, aluminum, aluminum alloys, and titanium are preferred from the viewpoint of weight reduction, and aluminum and aluminum alloys are even more preferred from the viewpoint of cost.

[0019] Specific examples of metal members used in the present invention include metal plates capable of having hydroxyl groups on the joining surface, and laminates having a metal film, such as a metal plating layer or a metal vapor deposition film, on the surface thereof, capable of having hydroxyl groups on the joining surface. There are no particular restrictions on the shape of such metal members, and they can be used after being processed into a desired shape by known metal processing methods such as cutting, pressing, milling, and grinding.

[0020] Furthermore, the metal member used in the present invention preferably has its joining surface pretreated. Examples of pretreatment include polishing treatments such as mechanical polishing, electrolytic polishing, chemical polishing, and chemical-mechanical polishing, and cleaning treatments such as degreasing. Such pretreatments tend to remove oil films and oxide films from the joining surface and form a fine uneven structure on the joining surface, which tends to improve the joining strength with the resin member. In particular, the joining surface formed with a fine uneven structure tends to further improve the joining strength due to the anchor effect.

[0021] (Resin parts) The resin member used in the present invention may have at least the joining surface made of polyamide, or the entire resin member may be made of polyamide. Examples of polyamides include polyamide 6, polyamide 11, polyamide 12, polyamide 46, polyamide 66, polyamide 610, polyamide 6T, polyamide 6I, polyamide 9T, and polyamide M5T. Among these, in the case of polyamides having the same structural units as the silane coupling agent described below, polyamide 6, polyamide 11, and polyamide 12 are preferred from the viewpoints of compatibility at the joining surface and ease of hydrogen bonding. Furthermore, the polyamide may contain fillers and various additives.

[0022] Specific examples of the resin member used in the present invention include a resin plate, a laminate having a resin film on the surface, etc. The shape of such a resin member is not particularly limited, and it is possible to use a resin member processed into a desired shape by a known resin molding method such as extrusion molding or injection molding.

[0023] (Silane coupling agent) The silane coupling agent used in the present invention is represented by the formula (1), and the structural unit [—NH—(CH) mThe repeating unit [—C(═O)—] has the same structure as the repeating unit of the polyamide. By bonding the metal member and the resin member using a silane coupling agent having such a structural unit, the metal member and the resin member are bonded with high bonding strength.

[0024] In the formula (1), R 1 ~R 3 R each independently represents a hydrogen atom, a halogen atom, a hydroxyl group, or a linear or branched alkoxy group which may contain a heteroatom. Examples of the heteroatom include a nitrogen atom, an oxygen atom, and a sulfur atom. Examples of the alkoxy group include a methoxy group, an ethoxy group, an n-propoxy group, and an i-propoxy group. 1 ~R 3 The group can be selected arbitrarily depending on the storage stability and reaction control during use. Generally, alkoxy groups, halogen atoms, and hydroxy groups with a small number of carbon atoms have poorer storage stability than other groups, and have a faster reaction rate during use.

[0025] In the formula (1), R 4 represents a divalent organic group having one or more carbon atoms which may contain a heteroatom. Examples of the heteroatom include a nitrogen atom, an oxygen atom, and a sulfur atom. Examples of the divalent organic group which does not contain a heteroatom include saturated or unsaturated divalent hydrocarbon groups such as an alkylene group and an alkenylene group. This hydrocarbon group may be linear or branched. Furthermore, the divalent organic group which contains a heteroatom (for example, a nitrogen atom) is an organic group (for example, -NH-R 41 -) [wherein R 41 represents a saturated or unsaturated divalent hydrocarbon group having one or more carbon atoms, and this hydrocarbon group may be linear or branched.

[0026] In addition, in the formula (1), R 4 is a divalent organic group containing such a heteroatom (e.g., —NH—R 41-), the heteroatom-containing group (e.g., -NH- group) is not a part of the structural unit [-NH-(CH) m -C(=O)- group in the -C(=O)- group, for example, to form a -C(=O)-NH- bond, and -C(=O)-NH-R 41 -structure is preferably formed.

[0027] In the formula (1), the number of carbon atoms in the divalent organic group (preferably the divalent hydrocarbon group) is the same as that in the structural unit [—NH—(CH) m From the viewpoint of hydrogen bonding between the structural unit [—C(═O)—] and the polyamide, the number of carbon atoms in the divalent organic group is preferably 3 to 6. When the number of carbon atoms in the divalent organic group is less than the lower limit, the number of carbon atoms in the structural unit [—NH—(CH2) m If the number of carbon atoms in the divalent organic group exceeds the upper limit, the operational complexity of the organic synthesis tends to increase.

[0028] In the formula (1), R 5 represents a monovalent organic group having one or more carbon atoms which may contain a heteroatom. Examples of the heteroatom include a nitrogen atom, an oxygen atom, and a sulfur atom.

[0029] Examples of the monovalent organic group containing no heteroatoms include saturated or unsaturated monovalent hydrocarbon groups such as alkyl groups, alkenyl groups, etc. The hydrocarbon group may be linear, branched, or cyclic.

[0030] The monovalent organic group containing a heteroatom (for example, an oxygen atom or a sulfur atom) may be an organic group (for example, R 51 -OC(=O)-, R 51 -S(=O)2- group (wherein R 51represents a saturated or unsaturated monovalent hydrocarbon group having one or more carbon atoms. The hydrocarbon group may be linear, branched, or cyclic, and may have a substituent, and the substituent may contain a heteroatom.

[0031] In addition, in the formula (1), R 5 is a monovalent organic group containing such a heteroatom (e.g., R 51 -OC(=O)-, R 51 When the structural unit [-NH-(CH) m -C(=O)-] and form, for example, an -OC(=O)-NH- bond or an -S(=O)2-NH- bond, and R 51 -OC(=O)-NH- structure or R 51 It is preferred that the —S(═O)2—NH— structure is formed.

[0032] In the formula (1), the monovalent organic group is the structural unit [—NH—(CH) m From the viewpoint of synthesizing silane coupling agents with different repeating numbers of -C(=O)- (protection and deprotection of the -NH- in the structural unit), tert-butoxycarbonyl group (Boc group), benzyloxycarbonyl group (Cbz group), 9-fluorenylmethyloxycarbonyl group (Fmoc group), allyloxycarbonyl group (Alloc group), phthaloyl group (Phth group), 2-nitrobenzenesulfonyl group (Ns group), (2-trimethylsilyl)-ethanesulfonyl group (SES group), and 2,2,2-trichloroethoxycarbonyl group (Troc group) are preferred, with Boc group, Cbz group, Alloc group, SES group, and Troc group being more preferred because of their simpler deprotection conditions and easier purification during the synthesis route. Furthermore, from the viewpoint of hydrogen bonding with the polyamide, Boc group, Cbz group, Alloc group, and Troc group are even more preferred.

[0033] In the formula (1), m represents the number of methylene groups between the -NH- group and the -C(=O)- group, and is an integer of 1 to 15, preferably an integer of 1 to 12, and more preferably an integer of 1, 11, or 12. If m exceeds the upper limit, the operational complexity of organic synthesis tends to increase.

[0034] In the formula (1), n ​​represents the structural unit [—NH—(CH) m represents the number of repeating units of the formula [—C(═O)—], and is an integer of 1 to 15, preferably an integer of 1 to 12, more preferably an integer of 1 to 6, and even more preferably an integer of 1 to 4. If n exceeds the upper limit, the solubility of the compound in the solvent during synthesis tends to decrease, and the operation tends to become more complicated.

[0035] In the silane coupling agent used in the present invention, the structural unit [—NH—(CH) m

[0033] The silane coupling agent in the formula (1) where m is 5 is used when the resin member has a joining surface made of polyamide 6, and the silane coupling agent in the formula (1) where m is 11 is used when the resin member has a joining surface made of polyamide 12, thereby bonding the metal member and the resin member with high bonding strength.

[0036] (Method for preparing silane coupling agent) The silane coupling agent used in the present invention is, for example, a compound represented by the following formula (1a):

[0037] [ka]

[0038] [R in the formula (1a) 5 , m and n are R in the formula (1), 5, m and n, and X represents a reactive functional group. A polyamide (PA) oligomer having a reactive functional group represented by the formula (1) is synthesized, and the PA oligomer having the reactive functional group is reacted with a silane compound having a functional group capable of reacting with the reactive functional group, thereby obtaining a PA oligomer silane coupling agent represented by the formula (1).

[0039] Examples of the reactive functional group X include a carboxy group, a carboxylic acid halide group, a reactive carboxylate group (e.g., a carboxylic acid N-hydroxysuccinimide ester group), an isocyanate group, etc. Examples of the functional group of the silane compound include an amino group (preferably a primary amino group), a hydroxy group, etc.

[0040] The reaction conditions for the reactive functional group X and the functional group of the silane compound are not particularly limited, and conventionally known reaction conditions can be employed.

[0041] <Method of manufacturing a metal-resin bonded body> The method for producing the metal-resin bonded body of the present invention is not particularly limited, but examples include a method in which the joining surfaces of the metal members (preferably, the joining surfaces having a micro-relief structure) are treated with a solution containing the silane coupling agent, and then the joining surfaces of the metal members and the resin members are joined via the silane coupling agent. More specifically, the silane coupling agent is applied to the joining surfaces of the metal members (preferably, the joining surfaces having a micro-relief structure), and then the silane coupling agent is reacted with hydroxyl groups on the metal surface, and a joining surface made of the polyamide of a resin member previously molded by extrusion molding or the like is brought into contact with the joining surface to which the silane coupling agent is bonded by thermocompression bonding or the like; or a method in which the polyamide is injection molded onto the joining surface to which the silane coupling agent is bonded to directly mold the resin member.

[0042] There are no particular limitations on the method for attaching the silane coupling agent to the joining surface of the metal member, and examples thereof include a method of immersing the metal member in a solution containing the silane coupling agent, and a method of applying or spraying the solution containing the silane coupling agent onto the joining surface of the metal member.

[0043] The method for reacting the hydroxyl groups on the metal surface with the silane coupling agent is not particularly limited, and examples thereof include a method in which the metal member is immersed in a solution containing the silane coupling agent and then heated, and in which an acid, a base, or water may be added to the solution.

[0044] The concentration of the silane coupling agent in the solution containing the silane coupling agent is not particularly limited, but is preferably 15 to 150 mmol / L, more preferably 20 to 150 mmol / L, even more preferably 25 to 120 mmol / L, and particularly preferably 30 to 100 mmol / L. A metal-resin joined body in which the joining surfaces of the metal members are treated with a solution having a silane coupling agent concentration within the above range will have the metal members and the resin members joined with even higher joining strength (tensile strength of 12 MPa or more, preferably 14 MPa or more, more preferably 16 MPa or more, even more preferably 17 MPa or more, and particularly preferably 18 MPa or more). [Example]

[0045] The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to the following examples. The pretreatment of the aluminum plate used in the examples and comparative examples and the synthesis of the silane coupling agent used in the examples were carried out by the following methods.

[0046] (Preparation Example 1) <Pretreatment of aluminum sheets> An aluminum plate (Al1050: 45 mm x 10 mm x 2 mm) was immersed in hexane and acetone, respectively, and subjected to ultrasonic treatment for 5 minutes. This aluminum plate was then immersed in a 3% by mass aqueous solution of sodium hydroxide and heated at 50°C for 1 minute, and then washed with ion-exchanged water. The aluminum plate was then immersed in hot water at 90°C for 30 minutes and then air-dried.

[0047] 1A and 1B show scanning electron microscope (SEM) photographs (50,000x magnification for Fig. 1A and 5,000x magnification for Fig. 1B) of the surface of the aluminum plate after pretreatment. As shown in Fig. 1A and 1B, it was confirmed that the surface of the aluminum plate after pretreatment was covered with a forest of scale-like aggregates (size: 1 μm) (Fig. 1B) measuring tens to hundreds of nanometers (Fig. 1A).

[0048] (Synthesis Example 1) <Synthesis of Compound 1: N-(tert-butoxycarbonyl)-6-aminohexanoic acid succinimide ester> A 50 mL two-necked recovery flask A was fitted with a three-way stopcock and a septum. The atmosphere inside the recovery flask A was purged with nitrogen three times. N-(tert-butoxycarbonyl)-6-aminohexanoic acid (1.00 g, 4.32 mmol) and N-hydroxysuccinimide (NHS) (0.55 g, 4.76 mmol) were then charged to the recovery flask A and vacuum dried for 30 minutes. The nitrogen atmosphere was then restored to the recovery flask A, and dehydrated N,N-dimethylformamide (DMF) (15 mL) was added. N,N'-dicyclohexylcarbodiimide (DCC) (0.98 g, 4.78 mmol) was then added. The mixture was stirred at 0 °C for 1 hour, then returned to room temperature and stirred overnight to synthesize N-(tert-butoxycarbonyl)-6-aminohexanoic acid succinimide ester (Compound 1). After the synthesis reaction was completed, the precipitated 1,3-dicyclohexylurea (DCU) was removed by filtration through Celite, and the DMF in the filtrate was distilled off using an evaporator. Anhydrous DMF was then added to the resulting residue to dissolve the residue, and the remaining DCU was removed by filtration through Celite. The DMF in the filtrate was then distilled off using an evaporator to purify Compound 1. After this purification was performed again, a three-way stopcock was attached to the two-necked recovery flask A containing the residue, and the flask was dried under vacuum. The flask was then stored in a nitrogen atmosphere. The synthesized Compound 1 was used directly in the following reaction (Compound 1 / DCU = 1 / 0.14 (mol / mol)) without further purification.

[0049] <Synthesis of Polyamide 6 (PA6) Oligomer (n=1) Silane Coupling Agent> The residue stored in the two-necked recovery flask A was dried under vacuum for 30 minutes, and then the nitrogen atmosphere was returned to the two-necked recovery flask A. Anhydrous DMF (5 ml) was added to dissolve the compound 1, yielding a DMF solution of the compound 1. A three-way stopcock and a septum were attached to another 50 ml two-necked recovery flask B, and the atmosphere in the two-necked recovery flask B was replaced with nitrogen three times. The DMF solution of compound 1 in the two-necked recovery flask A was transferred to the two-necked recovery flask B using a syringe. The syringe and the two-necked recovery flask A were then washed together with a total of 2.5 ml of anhydrous DMF, and all of the compound 1 remaining in the syringe and the two-necked recovery flask A was transferred to the two-necked recovery flask B. Next, 3-aminopropyltriethoxysilane (APTES) (1.04 ml, 4.45 mmol) was added and stirred. N,N-diisopropylethylamine (DIPEA, 0.78 ml, 4.45 mmol), which had been distilled under reduced pressure from CaH2, was then added. The two-necked flask B was then covered with aluminum foil and stirred overnight at room temperature to synthesize the PA6 oligomer (n = 1) silane coupling agent. After the synthesis reaction was complete, the mixture was diluted with dehydrated DMF (41 ml) to prepare a DMF solution of the PA6 oligomer (n = 1) silane coupling agent (concentration: 0.09 mol / L). The resulting DMF solution of the PA6 oligomer (n = 1) silane coupling agent contained NHS, which had been released and dissolved in the DMF during the reaction, but was used directly without separation.

[0050] Figure 2 shows the results of the PA6 oligomer (n = 1) silane coupling agent. 1 2 shows the H-NMR spectrum (400 MHz, DMSO-d6, rt). As shown in FIG. 2, the obtained PA6 oligomer (n=1) silane coupling agent was a compound represented by the formula (1) [wherein R 1 ~R 3 is -OCH2CH3, and R 4 is -NH-CH2-CH2-CH2-, and R 5 is C(CH3)3OC(=O)-, m=5, and n=1.

[0051] (Synthesis Example 2) Polyamide 6 (PA6) oligomer (n=2) was synthesized according to the method described in Srinivasa S. Reddy et al., Macromolecules, 1999, Vol. 32, p. 1367, and then a PA6 oligomer (n=2) silane coupling agent was synthesized.

[0052] <Synthesis of Compound 2: Cesium N-(tert-butoxycarbonyl)-6-aminohexanoate> N-(tert-butoxycarbonyl)-6-aminohexanoic acid (400 g, 1.73 mol), ethanol (5.6 L), and water (2.4 L) were charged into a 20 L separable flask and stirred. To the resulting solution, an aqueous solution (594 mL) of Cs2CO3 (155 g, 0.48 mol) was added dropwise while stirring until the pH reached 6.5. Stirring was continued for a while, synthesizing N-(tert-butoxycarbonyl)-6-aminohexanoic acid cesium salt (compound 2). The resulting reaction solution was concentrated using an evaporator, and then ethanol and toluene were added to the mixture for azeotropy. The residue after azeotropy was vacuum dried to remove the solvent, yielding compound 2 (yield 628 g, crude yield 99.9%).

[0053] <Synthesis of Compound 3: N-(tert-butoxycarbonyl)-6-aminohexanoic acid carboxyamide methyl ester> The entire amount of compound 2 was placed in a 20 L separable flask, and DMF (12 L) was added to dissolve the compound. 2-Chloroacetamide (243 g, 2.60 mol) was added to the resulting solution, and the mixture was stirred overnight to synthesize N-(tert-butoxycarbonyl)-6-aminohexanoic acid carboxyamide methyl ester (compound 3). The resulting reaction solution was concentrated at 45-50 °C using an evaporator, and then ethyl acetate (AcOEt, 16 L) was added to dissolve the concentrate. Compound 3 was then washed with 1N aqueous sodium carbonate solution (4 L) and water (4 L x 2) under ice cooling, and further washed with 10% aqueous citric acid solution (4 L) and water (4 L x 2). The resulting organic layer was dehydrated over sodium sulfate and concentrated. The resulting oil (294 g) was reprecipitated by adding diethyl ether (EtO) / hexane (1 / 1). The resulting crystals were filtered and dried to obtain the compound 3 as a white solid (yield: 205 g, 41%).

[0054] <Synthesis of Compound 4: Trifluoroacetate of Compound 3> Under an argon atmosphere, trifluoroacetic acid (1.4 L) was charged into a 3 L four-neck flask and stirred. The four-neck flask was immersed in a water bath to prevent a rapid temperature rise, and the compound 3 (200 g, 0.69 mol) was added. Stirring was continued for 1 hour to synthesize the trifluoroacetate salt of the compound 3 (compound 4). The resulting reaction solution was added dropwise to 20 L of EtO prepared separately, and the mixture was stirred for 1 hour. The resulting crystals were filtered, washed with a small amount of EtO, and dried under reduced pressure using a vacuum pump to obtain the compound 4 as a white solid (yield: 192 g, 92%).

[0055] <Synthesis of Compound 5: PA6 Oligomer (n=2)> Under a nitrogen atmosphere, compound 4 (140 g, 0.46 mol), N-(tert-butoxycarbonyl)-6-aminohexanoic acid (107 g, 0.46 mol), (benzotriazol-1-yloxy)tripyrrolidinophosphonium hexafluorophosphate (PyBOP, 241 g, 0.46 mol), and DMF (1.4 L) were charged into a 3 L four-neck flask and stirred until dissolved. Subsequently, DIEPA (159 mL, 0.93 mol) was added dropwise with ice cooling at an internal temperature of 10 °C or less, and the mixture was allowed to warm to room temperature and stirred overnight to carry out the synthesis reaction. The resulting reaction solution was concentrated using an evaporator at 45-50 °C, and the residue (700 g) was stirred overnight in EtO (7 L). The precipitate was filtered under an argon atmosphere and washed with a small amount of EtO to obtain mixture A (yield: 478 g).

[0056] 50 g of the resulting mixture A was weighed and dissolved in a small amount of eluent. The resulting solution was loaded onto DMS silica (500 g) and fractionated in 500 ml increments using water / methanol (7 / 3 (vol / vol)). A spot near the origin eluted in fractions 1 to 4, and the target PA6 oligomer (n = 2) began to elute in fraction 5. The eluent was then replaced with methanol alone, and fractions were collected up to fraction 10. This procedure was repeated 10 times until no remaining mixture A remained. The solvent was removed from the fraction containing the target PA6 oligomer (n = 2) using an evaporator, yielding mixture B (yield 230 g).

[0057] The resulting mixture B was dissolved in methanol / trichloromethane (5 / 95 (vol / vol)), loaded onto silica (2990 g), and fractionated in 1500 ml increments. Fractions 5-10 contained the impurity alone, fractions 11 and 12 contained both the impurity and the target PA6 oligomer (n = 2), and fractions 13-18 contained the target PA6 oligomer (n = 2) almost exclusively. The eluent was switched from fraction 13 onwards. The solutions from fraction 13 onwards were concentrated using an evaporator to obtain mixture C (yield 150 g).

[0058] The resulting mixture C was dissolved in hexane / AcOEt (5 / 95 (vol / vol)) with heating and then allowed to stand overnight at room temperature. The precipitated crystals were filtered and dried under reduced pressure using a vacuum pump to obtain PA6 oligomer (n=2) (compound 5) (yield: 110 g, 59%).

[0059] <Compound 6: Synthesis of PA6 oligomer (n=2) carboxylic acid> Compound 5 (PA6 oligomer (n = 2)) (3.00 g, 7.47 mmol) and DMF (30 ml) were placed in a 100 ml recovery flask and dissolved. 22 ml of 0.5 N aqueous sodium hydroxide (NaOH: 0.440 g, 10.5 mmol) was added to the resulting solution, followed by 14.1 ml of ultrapure water. The mixture was stirred at room temperature for 30 minutes to carry out the reaction. After the reaction was completed, 0.5 N aqueous citric acid was added to the resulting reaction solution to adjust the pH to 7, and then the water was removed using an evaporator. The resulting residue was dissolved in 50 ml of saturated aqueous NaHCO3 and washed twice with 50 ml of EtOAc. The resulting aqueous layer was transferred to a 300 ml beaker and cooled in an ice bath. Citric acid was added as a solid to adjust the pH to 3.0. The mixture was then extracted three times with 60 ml of EtOAc, and the resulting organic layer was washed twice with 50 ml of water. After washing with water, the organic layer was dried by adding anhydrous sodium sulfate, and EtOAc was removed using an evaporator to obtain PA6 oligomer (n=2) carboxylic acid (compound 6) (yield: 2.30 g, 84%).

[0060] <Synthesis of Compound 7: PA6 Oligomer (n=2) Carboxylic Acid Succinimide Ester> A three-way cock and a septum were attached to a 50-ml two-neck eggplant flask A, and the inside of the two-neck eggplant flask A was replaced with nitrogen three times. The compound 6 (PA6 oligomer (n = 2) carboxylic acid) (1.49 g, 4.32 mmol) and NHS (0.547 g, 4.76 mmol) were charged into this two-neck eggplant flask A and vacuum-dried for 30 minutes. Then, the inside of the two-neck eggplant flask A was returned to a nitrogen atmosphere, and dehydrated DMF (15 ml) was added. Further, after adding DCC (0.980 g, 4.76 mmol), it was stirred at 0 °C for 1 hour. Then, it was returned to room temperature and stirring was continued overnight to synthesize PA6 oligomer (n = 2) carboxylic acid succinimide ester (Compound 7). After completion of the synthesis reaction, the precipitated DCU was removed by filtration through celite, and further, the DMF in the filtrate was distilled off with an evaporator. Then, dehydrated DMF was added to the obtained residue to dissolve the residue, and the undissolved DCU was removed by filtration through celite, and further, the DMF in the filtrate was distilled off with an evaporator to purify the Compound 7. After performing this purification again, a three-way cock was attached to the two-neck eggplant flask A containing the residue and vacuum-dried, and then stored in a nitrogen atmosphere. The synthesized Compound 7 was used as it was (Compound 7 / DCU = 1 / 0.04 (mol / mol)) in the following reaction without further purification.

[0061] <Synthesis of PA6 oligomer (n = 2) silane coupling agent> The residue stored in the two-necked eggplant flask A was vacuum dried for 30 minutes, and then the nitrogen atmosphere was restored to the two-necked eggplant flask A. Anhydrous DMF (5 ml) was added to dissolve the compound 7 (PA6 oligomer (n = 2) carboxylic acid succinimide ester), yielding a DMF solution of the compound 7. A separate 50 ml two-necked eggplant flask B was fitted with a three-way stopcock and a septum, and the atmosphere in the two-necked eggplant flask B was purged with nitrogen three times. The DMF solution of compound 7 in the two-necked eggplant flask A was transferred to the two-necked eggplant flask B using a syringe. The syringe and the two-necked eggplant flask A were then washed together with a total of 5 ml of anhydrous DMF, and all of the compound 7 remaining in the syringe and the two-necked eggplant flask A was transferred to the two-necked eggplant flask B. APTES (1.04 ml, 4.45 mmol) was then added and stirred. Furthermore, DIPEA (0.775 ml, 4.45 mmol), which had been distilled under reduced pressure with CaH2, was added. The two-necked flask B was then covered with aluminum foil and stirred overnight at room temperature to synthesize the PA6 oligomer (n = 2) silane coupling agent. After the synthesis reaction was completed, the mixture was diluted with dehydrated DMF (38.7 ml) to prepare a DMF solution of the PA6 oligomer (n = 2) silane coupling agent (concentration 0.09 mol / L). Note that the resulting DMF solution of the PA6 oligomer (n = 2) silane coupling agent contained NHS, which had been released during the reaction and dissolved in the DMF, but was used as is without separation.

[0062] Figure 3 shows the results of the PA6 oligomer (n=2) silane coupling agent before dilution. 1 3 shows the H-NMR spectrum (400 MHz, DMSO-d6, rt). As shown in FIG. 3, the obtained PA6 oligomer (n=2) silane coupling agent was a compound represented by the formula (1) [wherein R 1 ~R 3 is -OCH2CH3, and R 4 is -NH-CH2-CH2-CH2-, and R 5 is C(CH3)3OC(=O)-, m=5, and n=2.

[0063] (Synthesis Example 3) Polyamide 6 (PA6) oligomer (n=4) was synthesized according to the method described in Srinivasa S. Reddy et al., Macromolecules, 1999, Vol. 32, p. 1367, and further, a PA6 oligomer (n=4) silane coupling agent was synthesized.

[0064] <Synthesis of Compound 8: Trifluoroacetate of PA6 Oligomer (n=2)> Trifluoroacetic acid (3.0 ml) was charged into a 50 ml two-neck flask and stirred. The two-neck flask was immersed in a water bath to prevent a sudden temperature rise. Compound 5 (PA6 oligomer (n = 2)) (0.641 g, 1.60 mmol), synthesized in the same manner as in Synthesis Example 2, was added, and stirring was continued for 1 hour to synthesize the trifluoroacetate salt of PA6 oligomer (n = 2) (compound 8). The resulting reaction solution was added dropwise to 20 L of EtO prepared separately, followed by stirring for 1 hour. The resulting reaction solution was dried under reduced pressure using a vacuum pump to obtain compound 8 as a white solid (yield: 0.633 g, 95.5%).

[0065] <Synthesis of Compound 9: PA6 Oligomer (n=4)> Under a nitrogen atmosphere, a 50 mL two-necked pear-shaped flask was charged with compound 6 (0.483 g, 1.40 mmol), which was synthesized in the same manner as in Synthesis Example 2, compound 8 (0.583 g, 1.40 mmol), 1H-benzotriazol-1-yloxytris(dimethylamino)phosphonium hexafluorophosphate (BOP, 0.590 g, 1.33 mmol), and dehydrated DMF (5 mL) and dissolved. DIEPA (0.448 mL, 2.80 mmol) was then added under ice cooling, stirred for 30 minutes, and then returned to room temperature. The two-necked pear-shaped flask was covered with aluminum foil to protect from light and stirred overnight to carry out the synthesis reaction. The precipitate was removed from the resulting reaction solution by filtration, and the DMF was distilled off using an evaporator. The resulting residue and 1 N aqueous citric acid solution (50 mL) were charged into a 100 mL flask and vigorously stirred for 1 hour using a magnetic stirrer, after which the residue was filtered. The resulting residue and ultrapure water (50 ml) were then placed in a 100 ml flask and vigorously stirred on a magnetic stirrer for 1 hour, after which the residue was filtered. The resulting residue and 1 N NaHCO3 aqueous solution (50 ml) were then placed in a 100 ml flask and vigorously stirred on a magnetic stirrer for 1 hour, after which the residue was filtered. The resulting residue was washed with Et2O and then dried under reduced pressure using a vacuum pump to obtain PA6 oligomer (n = 4) (compound 9) (0.600 g, 68% yield).

[0066] <Synthesis of Compound 10: PA6 Oligomer (n=4) Carboxylic Acid> Compound 9 (PA6 oligomer (n = 4)) (0.596 g, 0.949 mmol) and DMF (7.5 ml) were placed in a 100 ml beaker A and dissolved by slight heating using a laboratory dryer. NaOH (56.5 mg, 1.42 mmol), DMF (2.8 ml), and ultrapure water (6.8 ml) were placed in a separate 100 ml beaker B and dissolved. The solution in beaker B was added to the solution in beaker A, and the mixture was stirred at room temperature for 30 minutes to allow the reaction to proceed. After the reaction was completed, the pH of the resulting reaction solution was adjusted to 7 by adding 0.5 N aqueous citric acid solution, and the water was then removed using an evaporator. The resulting residue was dissolved in saturated aqueous NaHCO3 solution (39 ml). The resulting solution was cooled in an ice bath, and solid citric acid was added to adjust the pH to 3.0. The resulting white precipitate was filtered and washed several times with ultrapure water and EtO. The washed precipitate was dried in vacuo to obtain PA6 oligomer (n = 4) carboxylic acid (compound 10) (yield: 0.364 g, 67%).

[0067] <Synthesis of Compound 11: PA6 Oligomer (n=4) Carboxylic Acid Succinimide Ester> A 50 ml two-necked recovery flask A was fitted with a three-way stopcock and a septum, and the atmosphere inside the recovery flask A was replaced with nitrogen three times. Compound 10 (PA6 oligomer (n=4) carboxylic acid) (0.352 g, 0.618 mmol) and NHS (78.2 mg, 0.679 mmol) were then placed in the recovery flask A and vacuum dried for 30 minutes. Thereafter, the nitrogen atmosphere was restored inside the recovery flask A, and dehydrated DMF (8.1 ml) was added. DCC (0.140 g, 0.679 mmol) was then added, and the mixture was stirred at room temperature for 24 hours. At this time, the reaction solution 1Since the reaction conversion rate was 89% from the results of 1H-NMR measurement, NHS (14.2 mg) and DCC (25.4 mg) corresponding to 20 mol% of the charged amount of the PA6 oligomer (n = 4) of the compound 10 were added, and further, the mixture was stirred at 50 °C for 2 hours to synthesize a PA6 oligomer (n = 4) carboxylic acid succinimide ester (compound 11). After completion of the synthesis reaction, the precipitated DCU was removed by filtration through celite, and further, the DMF in the filtrate was distilled off with an evaporator. Then, dehydrated DMF was added to the obtained residue to dissolve the residue, and the undissolved DCU was removed by filtration through celite, and further, the DMF in the filtrate was distilled off with an evaporator to purify the compound 11. After repeating this purification, a three-way cock was attached to the two-neck eggplant flask A containing the residue for vacuum drying, and then, it was stored in a nitrogen atmosphere. In addition, the synthesized compound 11 was used as it was (compound 11 / DCU = 1 / 0.52 (mol / mol)) in the following reaction without further purification.

[0068] <Synthesis of PA6 oligomer (n = 4) silane coupling agent> The residue stored in the two-necked recovery flask A was dried under vacuum for 30 minutes, and then the nitrogen atmosphere was returned to the two-necked recovery flask A. Anhydrous DMF (3 ml) was added to dissolve the compound 11 (PA6 oligomer (n = 4) carboxylic acid succinimide ester), yielding a DMF solution of the compound 11. A three-way stopcock and a septum were attached to another 50 ml two-necked recovery flask B, and the atmosphere in the two-necked recovery flask B was purged with nitrogen three times. The DMF solution of the compound 11 in the two-necked recovery flask A was transferred to the two-necked recovery flask B using a syringe. Furthermore, the syringe and the two-necked recovery flask A were washed together with a total of 1 ml of anhydrous DMF, and all of the compound 11 remaining in the syringe and the two-necked recovery flask A was transferred to the two-necked recovery flask B. APTES (0.16 ml, 0.691 mmol) was then added and stirred. Furthermore, DIPEA (0.12 ml, 0.692 mmol), which had been distilled under reduced pressure with CaH2, was added. The two-necked flask B was then covered with aluminum foil and stirred overnight at room temperature to synthesize the PA6 oligomer (n = 4) silane coupling agent. After the synthesis reaction was complete, the mixture was diluted with dehydrated DMF (2.95 ml) to prepare a DMF solution of the PA6 oligomer (n = 4) silane coupling agent (concentration: 0.09 mol / L). The resulting DMF solution of the PA6 oligomer (n = 4) silane coupling agent contained NHS, which had been released during the reaction and dissolved in the DMF, but was used as is without separation.

[0069] Figure 4 shows the results of the PA6 oligomer (n=4) silane coupling agent before dilution. 1 4 shows the H-NMR spectrum (400 MHz, DMSO-d6, rt). As shown in FIG. 4, the obtained PA6 oligomer (n=2) silane coupling agent was a compound represented by the formula (1) [wherein R 1 ~R 3 is -OCH2CH3, and R 4 is -NH-CH2-CH2-CH2-, and R 5 is C(CH3)3OC(=O)-, m=5, and n=4.

[0070] (Synthesis Example 4) <Synthesis of Compound 1: N-(tert-butoxycarbonyl)-6-aminohexanoic acid succinimide ester> N-(tert-butoxycarbonyl)-6-aminohexanoic acid succinimide ester (Compound 1) was synthesized and purified in the same manner as in Synthesis Example 1, except that the amount of N-(tert-butoxycarbonyl)-6-aminohexanoic acid was changed to 3.28 g (14.2 mmol), the amount of N-hydroxysuccinimide (NHS) was changed to 1.79 g (15.6 mmol), the amount of dehydrated N,N-dimethylformamide (DMF) used during the synthesis was changed to 49.2 ml, and the amount of N,N'-dicyclohexylcarbodiimide (DCC) was changed to 3.21 g (15.6 mmol). The compound was stored in a nitrogen atmosphere and used as is in the following reaction (Compound 1 / DCU = 1 / 0.14 (mol / mol)).

[0071] <Synthesis of Polyamide 6 (PA6) Oligomer (n=1) Silane Coupling Agent> The amount of dehydrated DMF used when dissolving the compound 1 was 17.8 ml, the total amount of dehydrated DMF used for co-washing was 15 ml, the amount of 3-aminopropyltriethoxysilane (APTES) was 3.40 ml (14.6 mmol), and the amount of N,N-diisopropylethylamine (DIPEA) was 2.54 ml (14.6 mmol). Except for this, the synthesis reaction was carried out in the same manner as in Example 1 to obtain a DMF solution (concentration 432 mmol / L) of PA6 oligomer (n = 1) silane coupling agent. The obtained DMF solution of PA6 oligomer (n = 1) silane coupling agent contained NHS, which was released by the reaction and dissolved in DMF, but was used as is without separation.

[0072] The obtained PA6 oligomer (n = 1) silane coupling agent 1 The H-NMR spectrum (400 MHz, DMSO-d6, rt) was measured, and the PA6 oligomer (n=1) silane coupling agent obtained in Synthesis Example 1 was 1 Similar to the H-NMR spectrum (Figure 2), 1H-NMR spectrum was obtained, and the obtained PA6 oligomer (n=1) silane coupling agent was found to be a compound represented by the formula (1) [wherein R 1 ~R 3 is -OCH2CH3, and R 4 is -NH-CH2-CH2-CH2-, and R 5 is C(CH3)3OC(=O)-, m=5, and n=1.

[0073] Example 1 A 50 ml sample bottle was charged with a DMF solution (5 ml, concentration: 0.09 mol / L) of the PA6 oligomer (n = 1) silane coupling agent obtained in Synthesis Example 1. The aluminum plate pretreated in Preparation Example 1 was immersed in this DMF solution and heated at 110 °C for 4 hours. After heating, the aluminum plate was removed, ultrasonicated in ethanol for 5 minutes, rinsed with ethanol, and air-dried. The aluminum plate was mounted in a mold at 120 °C, and polyamide 6 ("CM1007" manufactured by Toray Industries, Inc.) vacuum-dried at 100 °C for 12 hours was melt-injected at 240 °C to produce a butt-joint metal-resin bonded body. The resulting metal-resin bonded body was used as a tensile test specimen and placed in an Instron tensile tester with a chuck distance of 50 mm. A tensile test was performed at room temperature at a tension rate of 10 mm / min to measure the tensile strength. The results are shown in Table 1 and Figure 5.

[0074] Example 2 A butt-jointed metal-resin bonded body was prepared in the same manner as in Example 1, except that the DMF solution of PA6 oligomer (n=2) silane coupling agent (5 ml, concentration: 0.09 mol / L) obtained in Synthesis Example 2 was used instead of the DMF solution of PA6 oligomer (n=1) silane coupling agent, and the tensile strength was measured. The results are shown in Table 1 and Fig. 5.

[0075] Example 3 A butt-jointed metal-resin bonded body was prepared in the same manner as in Example 1, except that the DMF solution of PA6 oligomer (n=4) silane coupling agent (5 ml, concentration: 0.09 mol / L) obtained in Synthesis Example 3 was used instead of the DMF solution of PA6 oligomer (n=1) silane coupling agent, and the tensile strength was measured. The results are shown in Table 1 and Fig. 5.

[0076] Example 4 A DMF solution (concentration: 432 mmol / L) of the PA6 oligomer (n=1) silane coupling agent obtained in Synthesis Example 4 was diluted with dehydrated DMF to prepare a DMF solution of the PA6 oligomer (n=1) silane coupling agent with a concentration of 133 mmol / L. A butt-jointed metal-resin bonded body was fabricated in the same manner as in Example 1, except that 5 mL of this DMF solution of the PA6 oligomer (n=1) silane coupling agent was used instead of the DMF solution of the PA6 oligomer (n=1) silane coupling agent obtained in Synthesis Example 1 (concentration: 0.09 mol / L), and the tensile strength was measured. The results are shown in Table 2 and FIG. 6.

[0077] Example 5 A DMF solution (concentration: 432 mmol / L) of the PA6 oligomer (n=1) silane coupling agent obtained in Synthesis Example 4 was diluted with dehydrated DMF to prepare a DMF solution of the PA6 oligomer (n=1) silane coupling agent with a concentration of 89 mmol / L. A butt-jointed metal-resin bonded body was fabricated in the same manner as in Example 1, except that 5 mL of this DMF solution of the PA6 oligomer (n=1) silane coupling agent was used instead of the DMF solution of the PA6 oligomer (n=1) silane coupling agent obtained in Synthesis Example 1 (concentration: 0.09 mol / L), and the tensile strength was measured. The results are shown in Table 2 and FIG. 6.

[0078] Example 6 A DMF solution (concentration: 432 mmol / L) of the PA6 oligomer (n=1) silane coupling agent obtained in Synthesis Example 4 was diluted with dehydrated DMF to prepare a DMF solution of the PA6 oligomer (n=1) silane coupling agent with a concentration of 44.5 mmol / L. A butt-jointed metal-resin bonded body was fabricated in the same manner as in Example 1, except that 5 mL of this DMF solution of the PA6 oligomer (n=1) silane coupling agent was used instead of the DMF solution of the PA6 oligomer (n=1) silane coupling agent obtained in Synthesis Example 1 (concentration: 0.09 mol / L), and the tensile strength was measured. The results are shown in Table 2 and FIG. 6.

[0079] Example 7 A DMF solution (concentration: 432 mmol / L) of the PA6 oligomer (n=1) silane coupling agent obtained in Synthesis Example 4 was diluted with dehydrated DMF to prepare a DMF solution of PA6 oligomer (n=1) silane coupling agent with a concentration of 17.8 mmol / L. A butt-jointed metal-resin bonded body was fabricated in the same manner as in Example 1, except that 5 mL of this DMF solution of PA6 oligomer (n=1) silane coupling agent was used instead of the DMF solution of PA6 oligomer (n=1) silane coupling agent (concentration: 0.09 mol / L) obtained in Synthesis Example 1, and its tensile strength was measured. The results are shown in Table 2 and FIG. 6.

[0080] (Comparative Example 1) A butt-jointed metal-resin bonded body was produced in the same manner as in Example 1, except that the surface of the aluminum plate pretreated in Preparation Example 1 was not surface-treated with a PA6 oligomer (n=1) silane coupling agent, and the tensile strength was measured. The results are shown in Tables 1 and 2 and Figures 5 and 6.

[0081] (Comparative Example 2) A butt-jointed metal-resin bonded body was prepared in the same manner as in Example 1, except that a DMF solution of 3-(2-aminoethylamino)propyltrimethoxysilane (5 ml, concentration 0.09 mol / L) was used instead of the DMF solution of PA6 oligomer (n=1) silane coupling agent, and the tensile strength was measured. The results are shown in Tables 1 and 2 and Figures 5 and 6.

[0082] [Table 1]

[0083] [Table 2]

[0084] As shown in Table 1 and FIG. 5, it was confirmed that the metal-resin joined bodies (Examples 1 to 3) in which an aluminum plate and a polyamide resin member were joined via a silane coupling agent having an amide bond had higher tensile strength than the metal-resin joined body (Comparative Example 1) in which the aluminum plate and the polyamide resin member were joined without using a silane coupling agent and the metal-resin joined body (Comparative Example 2) in which the aluminum plate and the polyamide resin member were joined via a silane coupling agent not containing an amide bond.

[0085] Furthermore, as shown in Table 2 and FIG. 6, the metal-resin joined bodies (Examples 4 to 7) in which an aluminum plate and a polyamide resin member were joined using a solution containing a silane coupling agent having an amide bond at a concentration of 15 to 150 mmol / L had higher tensile strength than the metal-resin joined body (Comparative Example 1) in which the aluminum plate and the polyamide resin member were joined without using a silane coupling agent and the metal-resin joined body (Comparative Example 2) in which the aluminum plate and the polyamide resin member were joined via a silane coupling agent that did not contain an amide bond, and it was confirmed that the aluminum plate and the polyamide resin member were joined with high bonding strength (tensile strength of 15 MPa or more). [Industrial Applicability]

[0086] As described above, according to the present invention, it is possible to bond a metal member and a resin member with high bonding strength via a silane coupling agent. Therefore, the metal-resin bonded body of the present invention has a metal member and a resin member firmly bonded to each other and is lighter than a member made of only metal, and is therefore useful as a member that can replace a member made of only metal in the automotive, railroad, aircraft, and other fields.

Claims

1. The joint includes a metal member having a joining surface made of metal and a resin member having a joining surface made of polyamide, The joining surface of the metal member and the joining surface of the resin member have a viscosity expressed by the following formula (1): 【Chemical 1】 [wherein R １ ~R ３ each independently represents a hydrogen atom, a halogen atom, a hydroxy group, or a linear or branched alkoxy group which may contain a heteroatom; R ４ represents a divalent organic group having one or more carbon atoms which may contain a heteroatom, and R ５ represents a monovalent organic group having one or more carbon atoms which may contain a heteroatom, and m and n each independently represent an integer of 1 to 15. The structural unit [—NH—(CH ２ ) ｍ -C(=O)-] is bonded via a silane coupling agent having the same structure as the repeating unit of the polyamide.

2. In the formula (1), R ４ is a divalent organic group containing a nitrogen atom and having one or more carbon atoms, and R ５ 2. The metal-resin bonded body according to claim 1, wherein: is a monovalent organic group having one or more carbon atoms and containing an oxygen atom.

3. In the formula (1), R ４ Ga-NH-R ４１ - [wherein R ４１ represents a divalent hydrocarbon group having one or more carbon atoms, and R ５ is R ５１ —O—C(═O)— (wherein R ５１ 2. The metal-resin bonded body according to claim 1, wherein R represents a monovalent hydrocarbon group having one or more carbon atoms.

4. 2. The metal-resin joined body according to claim 1, wherein the metal constituting the joining surface of the metal member is aluminum or an aluminum alloy.

5. 2. The metal-resin joined body according to claim 1, wherein the polyamide constituting the joining surface of the resin member is at least one selected from the group consisting of polyamide 6, polyamide 11, and polyamide 12.

6. 2. The metal-resin bonded body according to claim 1, wherein the bonding surfaces of the metal members are treated with a solution containing the silane coupling agent at a concentration of 15 to 150 mmol / L.

7. A method for producing a metal-resin bonded body according to any one of claims 1 to 6, a method for producing a metal-resin bonded body, the method comprising treating the bonding surfaces of the metal members with a solution containing the silane coupling agent, and then bonding the bonding surfaces of the metal members and the resin members via the silane coupling agent.

8. 8. The method for producing a metal-resin bonded body according to claim 7, wherein the concentration of the silane coupling agent in the solution containing the silane coupling agent is 15 to 150 mmol / L.

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