Method for manufacturing bonded body

Abstract

The present invention relates to a technique for bonding a base material A, which is a fiber-reinforced plastic base material, and a base material B, which is a metal base material, and provides a bonding technique which has a short bonding process time, a long opening time, and excellent adhesiveness. This method for producing a bonded body is provided with: a pre-bonding step for preparing a laminate by sequentially arranging a base material A, which is a fiber-reinforced plastic base material, a solid binder containing an amorphous thermoplastic resin, and a base material B, which is a metal base material, in this order; the amorphous thermoplastic resin is at least one selected from thermoplastic epoxy resin and phenoxy resin; a bonding step for bonding the base material A and the base material B by heating and pressurizing the laminate to melt the solid binder; the amorphous thermoplastic resin has an epoxy equivalent of 1,600 or more or does not contain an epoxy group, and has a heat of fusion of 15 J / g or less.

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a bonded body, which is suitable for use in easily and firmly bonding dissimilar materials. Background Art

[0002] In recent years, in consideration of aspects such as weight reduction and high performance of products, in various fields such as automotive parts, medical devices, and household appliances, the multi-materialization of components has been promoted. Multi-materialization refers to a method of achieving weight reduction and high strength of materials by using materials with different functions and materials (hereinafter referred to as dissimilar materials) in combination. In order to achieve multi-materialization, a technology for firmly bonding dissimilar materials is indispensable.

[0003] As a means for firmly bonding dissimilar materials, thermosetting epoxy resin adhesives (Patent Document 1, etc.), which are liquid adhesives, have been widely used.

[0004] Bonding using a liquid adhesive requires a coating step of coating a liquid resin composition and a curing step of polymerizing and curing the resin composition after coating.

[0005] Therefore, in the case of bonding using a liquid adhesive, it takes time to coat the resin composition in the coating step, and it takes time to carry out the polymerization reaction in the curing step (that is, the bonding process time is long), and there is a problem of lack of convenience.

[0006] In this specification, the bonding process time means the time from the start when at least one base material constituting the bonded body comes into contact with the bonding agent to the end when the bonded body is completed. For example, it includes the time for coating a liquid adhesive on the base material, the drying process, or the process of placing a solid bonding agent, and the time required to bond the base materials to each other (for example, curing the bonding layer).

[0007] In addition, a technique for manufacturing a bonded body has also been disclosed in which a base material is impregnated or coated with an epoxy resin composition and then semi-cured (B-staged) to form a laminate having a B-staged adhesive layer.

[0008] However, bonding using a B-staged adhesive also requires a curing step of polymerizing and curing the semi-cured adhesive layer, and there is a problem of a long bonding process time.

[0009] In addition, the storage stability of the B-staged adhesive is poor, and it cannot be stored at room temperature for a long time and needs to be stored at a low temperature. There are problems of a short open time and lack of convenience.

[0010] In this specification, the open time refers to the limited time from when the adhesive is coated or placed on the base material A until the base material B is completely placed. If within the open time, the adhesive strength of the adhesive will not decrease, and the base material A and the base material B can be bonded with sufficient adhesive strength. The longer the open time, the longer the limited time from when the adhesive is coated or placed on the base material A until the base material B is completely placed, and the higher the convenience.

[0011] As a means of bonding dissimilar materials, a thermoplastic adhesive composition (hereinafter referred to as a hot melt adhesive) is also used (Patent Document 3, etc.). By using a hot melt adhesive, specifically, since the hot melt adhesive is an adhesive that bonds by utilizing a phase change without a polymerization reaction, there is no need for a coating process, the curing time is fast (that is, the bonding process time is short), and the convenience is excellent. In addition, it can be stored at room temperature for a long time, and the convenience is also excellent in terms of the long open time.

[0012] However, as a conventional hot melt adhesive, it is formed of a crystalline resin or a resin containing a crystalline resin in order to reduce the melt viscosity. Therefore, the cohesive force in the adhesive resin is high, and there is no sufficient interaction with the base material. In addition, when performing melt bonding, it becomes low viscosity at high temperature and easily flows out from the bonding surface. In addition, it is difficult to control the viscosity, so the film thickness is unstable. Due to these factors, there is a problem that a high adhesive strength cannot be stably obtained with the existing hot melt adhesives.

[0013] Prior Art Documents

[0014] Patent Documents

[0015] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2019-157018

[0016] Patent Document 2: Japanese Unexamined Patent Application Publication No. 10-17685

[0017] Patent Document 3: Japanese Unexamined Patent Application Publication No. 10-168417 Summary of the Invention

[0018] Problems to be Solved by the Invention

[0019] As described above, in the prior art, in either the liquid type or the B-stage state of the thermosetting epoxy resin adhesive with excellent adhesiveness, there is at least one of the problems of a long bonding process time and a short open time. The hot melt adhesive with a short bonding process time and a long open time has a problem that a high adhesive strength cannot be stably obtained.

[0020] The present invention has been completed in view of the above technical background, and an object thereof is to provide a joining technique for joining a substrate A as a fiber-reinforced plastic substrate and a substrate B as a metal substrate, which has a short joining process time, a long open time, and excellent adhesiveness.

[0021] Means for solving the problem

[0022] In order to achieve the above object, the present invention provides the following means.

[0023] It should be noted that in this specification, joining means connecting an object to an object, and adhesion and welding are subordinate concepts thereof. Adhesion means forming a joined state of two adherends (materials to be adhered) by means of an organic material such as a tape or an adhesive (thermosetting resin, thermoplastic resin, etc.). Welding means melting the surface of a thermoplastic resin or the like by heat and forming a joined state by contact pressure and cooling using winding and crystallization based on molecular diffusion.

[0024] <Manufacturing method of joined body>

[0025] [1] A manufacturing method of a joined body, which includes a pre-joining process and a joining process.

[0026] In the pre-joining process: a laminate is prepared by sequentially arranging a substrate A as a fiber-reinforced plastic substrate, a solid binder, and a substrate B as a metal substrate. The solid binder contains an amorphous thermoplastic resin, and the amorphous thermoplastic resin is at least one selected from a thermoplastic epoxy resin and a phenoxy resin.

[0027] In the joining process: the laminate is heated and pressed to melt the solid binder, thereby joining the substrate A and the substrate B.

[0028] The epoxy equivalent of the amorphous thermoplastic resin is 1,600 or more or does not contain an epoxy group, and the heat of fusion is 15 J / g or less.

[0029] [2] The manufacturing method of the joined body according to [1], wherein the heating and pressing are performed under the conditions of 100 to 400 °C and 0.01 to 20 MPa.

[0030] [3] The manufacturing method of the joined body according to [1] or [2], wherein the solid binder before melting has a film shape.

[0031] [4] A manufacturing method of a joined body, which is a manufacturing method of a joined body formed by sequentially joining a substrate A as a fiber-reinforced plastic substrate, a solid binder, and a substrate B as a metal substrate. The solid binder contains an amorphous thermoplastic resin, and the amorphous thermoplastic resin is at least one selected from a thermoplastic epoxy resin and a phenoxy resin.

[0032] This method includes a first bonding process and a second bonding process.

[0033] The first bonding process: In a state where the solid bonding agent is in surface contact with the substrate A, the solid bonding agent is melted and then solidified, thereby bonding the substrate A and the solid bonding agent, or in a state where the solid bonding agent is in surface contact with the substrate B, the solid bonding agent is melted and then solidified, thereby bonding the substrate B and the solid bonding agent.

[0034] The second bonding process: In a state where the solid bonding agent bonded to the substrate A is in surface contact with the substrate B, the solid bonding agent is melted and then solidified, thereby bonding the substrate A and the substrate B, or in a state where the solid bonding agent bonded to the substrate B is in surface contact with the substrate A, the solid bonding agent is melted and then solidified, thereby bonding the substrate A and the substrate B.

[0035] The epoxy equivalent of the amorphous thermoplastic resin is 1,600 g / eq. or more or does not contain an epoxy group, and the heat of fusion is 15 J / g or less.

[0036] [5] The method for manufacturing a bonded body according to [4], in the first bonding process, the solid bonding agent is heated to 100 - 300 °C to be melted and then solidified.

[0037] [6] The method for manufacturing a bonded body according to [4] or [5], in the second bonding process, the solid bonding agent is melted and then solidified by at least one selected from contact heating, hot air heating, hot pressing, infrared heating, hot plate welding, ultrasonic welding, vibration welding, and high-frequency induction welding.

[0038] [7] The method for manufacturing a bonded body according to any one of [4] - [6], in the second bonding process, the solid bonding agent is melted and then solidified under a heating temperature of 100 - 400 °C and a pressure of 0.01 - 20 MPa.

[0039] [8] The method for manufacturing a bonded body according to any one of [1] - [7], the solid bonding agent before melting has the shape of a film.

[0040] <Bonded body>

[0041] [9] A bonded body formed by bonding a substrate A as a fiber-reinforced plastic substrate and a substrate B as a metal substrate through an adhesive layer.

[0042] The adhesive layer is formed by disposing a solid binder containing an amorphous thermoplastic resin between the base material A and the base material B, heating and pressing it to melt, and curing the solid binder. The amorphous thermoplastic resin is at least one selected from a thermoplastic epoxy resin and a phenoxy resin, has an epoxy equivalent of 1,600 or more, and a heat of fusion of 15 J / g or less.

[0043]

[10] For the bonded body according to [9], the heating and pressing are carried out under the conditions of 100 to 400 °C and 0.01 to 20 MPa.

[0044] Advantages of the Invention

[0045] According to the present invention, a technique for bonding a base material A as a fiber-reinforced plastic base material and a base material B as a metal base material is provided, and a bonding technique with a short bonding process time, a long pot life, and excellent adhesiveness can be provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 It is an explanatory view showing the structure of a bonded body according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0047] [Manufacturing Method of Bonded Body - Embodiment 1]

[0048] The manufacturing method of the bonded body of Embodiment 1 includes a pre-bonding process and a bonding process. In the pre-bonding process, a laminate is prepared by sequentially disposing a base material A as a fiber-reinforced plastic base material, a solid binder, and a base material B as a metal base material. The solid binder contains an amorphous thermoplastic resin, and the amorphous thermoplastic resin is at least one selected from a thermoplastic epoxy resin and a phenoxy resin. In the bonding process, the laminate is heated and pressed to melt the solid binder, thereby bonding the base material A and the base material B.

[0049] In the above pre-bonding process, the bonding between the base material A and the solid binder and the bonding between the base material B and the solid binder are not carried out, but the bonding is carried out in the subsequent bonding process. The solid binder may also have adhesiveness, and in this case, the solid binder is temporarily fixed to the base material in the pre-bonding process.

[0050] Hereinafter, each process will be described.

[0051] [Pre-bonding Process]

[0052] In the pre-bonding process, a laminate is prepared by sequentially disposing a base material A, a solid binder containing an amorphous thermoplastic resin, and a base material B. The amorphous thermoplastic resin is at least one selected from a thermoplastic epoxy resin and a phenoxy resin.

[0053] Regarding the above laminate, the base material A and the solid binder, and the solid binder and the base material B are not joined, but rather, independent components are stacked together.

[0054] The "solid" of the above solid binder means that it is a solid at normal temperature, that is, it has no fluidity in the unpressurized state at 23°C.

[0055] The above solid binder preferably has the property of being able to maintain its shape without deformation and without deterioration for 30 days or more in the unpressurized state at 23°C.

[0056] (Solid binder)

[0057] The solid binder contains an amorphous thermoplastic resin, and the amorphous thermoplastic resin is at least one selected from a thermoplastic epoxy resin and a phenoxy resin, with an epoxy equivalent of 1,600 or more and a heat of fusion of 15 J / g or less.

[0058] The amorphous resin in the present invention refers to a resin that has a melting point (Tm) in the measurement using a differential scanning calorimeter (DSC), but does not have an endothermic peak (melting point) accompanied by a distinct melting or the endothermic peak (melting point) is very small. The heat of fusion is calculated from the area of the endothermic peak of the DSC and the weight of the thermoplastic resin component. In the case where an inorganic filler or the like is included in the solid binder, it is calculated from the weight of the resin component excluding the inorganic filler. Specifically, the amorphous thermoplastic resin in the present invention refers to the following substances. Weigh 2 - 10 mg of the sample, place it in an aluminum pan, and heat it from 23°C to 200°C or more at 10°C / min using a DSC (DSC8231 manufactured by Rigaku Corporation) to obtain a DSC curve. Then, when calculating the heat of fusion from the area of the endothermic peak during melting obtained from this DSC curve and the above weighing value, the resin with a heat of fusion of 15 J / g or less.

[0059] From the aspect of fully endowing the solid binder with the characteristics of the amorphous thermoplastic resin, as the content of the above amorphous thermoplastic resin, it is preferably 51% by mass or more, more preferably 60% by mass or more, further preferably 70% by mass or more, particularly preferably 80% by mass or more, and most preferably 90% by mass or more in the resin component of the solid binder. In the present disclosure, the "resin component in the solid thermal conductive material" refers to the components other than the filler in the solid thermal conductive material.

[0060] The heat of fusion is 15 J / g or less, preferably 11 J / g or less, more preferably 7 J / g or less, further preferably 4 J / g or less, and most preferably the melting peak is below the detection limit.

[0061] The epoxy equivalent is 1,600 or more, preferably 2,000 or more, more preferably 5,000 or more, further preferably 9,000 or more, and most preferably above the detection limit and substantially no epoxy groups can be detected.

[0062] By using a solid binder containing an amorphous thermoplastic resin with an epoxy equivalent of 1600 or more and a heat of fusion of 15 J / g or less, there is no sharp decrease in viscosity that occurs in conventional hot melt binders during heating, and even in a high temperature region exceeding 200 °C, it does not reach a low viscosity (0.001 - 100 Pa·s) state. Therefore, even in a molten state, this solid binder does not flow out from the laminate, can stably ensure the thickness of the adhesive layer, and can stably obtain a high adhesive force.

[0063] The epoxy equivalent (the weight of the above resin containing 1 mole of epoxy groups) mentioned here is the value of the epoxy equivalent of the thermoplastic epoxy resin or phenoxy resin component contained in the solid binder before bonding, and is a value measured by the method specified in JIS - K7236:2001 (unit "g / eq."). Specifically, using a potentiometric titration device, with cyclohexanone as the solvent, adding a tetraethylammonium bromide acetic acid solution, using a 0.1 mol / L perchloric acid - acetic acid solution, the solvent dilution (resin varnish) is a value obtained by calculating the solid content conversion value from the non - volatile components. It should be noted that in the case of a mixture of two or more resins, it can also be calculated from their respective contents and epoxy equivalents.

[0064] The melting point of the amorphous thermoplastic resin contained in the solid binder is preferably 50 - 400 °C, more preferably 60 °C - 350 °C, and further preferably 70 °C - 300 °C. By making the melting point within the range of 50 - 400 °C, the above solid binder is efficiently deformed and melted by heating, and effectively wets and spreads on the bonding surface, so a high adhesive force can be obtained.

[0065] In this specification, the melting point of the amorphous thermoplastic resin refers to the temperature range of the process of substantially softening from a solid, becoming thermoplastic, and being able to melt and bond.

[0066] Regarding conventional thermosetting adhesives, it is difficult to disassemble the bonded body, difficult to separate and recycle dissimilar materials constituting the bonded body (i.e., poor recyclability), and in addition, in cases where there is an offset at the bonding part in the manufacturing process of the bonded body, and in cases where the contents or adherends are defective and need to be replaced, there are problems such as difficulty in re - bonding (i.e., poor reparability) and lack of convenience. However, the above solid binder can be softened and melted by heat and can be easily peeled off, so the recyclability is excellent. In addition, since the above solid binder is thermoplastic, it can be reversibly softened, melted, and cured repeatedly, and the reparability is also excellent.

[0067] "Thermoplastic Epoxy Resin"

[0068] The thermoplastic epoxy resin is preferably a polymer of (a) a difunctional epoxy resin monomer or oligomer and (b) a difunctional compound having two identical or different functional groups selected from phenolic hydroxyl groups, carboxyl groups, mercapto groups, isocyanate groups, and cyanate groups.

[0069] By using this compound, the polymerization reaction for forming a linear polymer proceeds preferentially, and a thermoplastic epoxy resin having desired properties can be obtained.

[0070] The above-mentioned (a) difunctional epoxy resin monomer or oligomer refers to an epoxy resin monomer or oligomer having two epoxy groups in the molecule.

[0071] Specific examples of the above (a) include, for example, bisphenol A type epoxy resin, bisphenol F type epoxy resin, difunctional phenol novolak type epoxy resin, bisphenol AD type epoxy resin, biphenyl type epoxy resin, difunctional naphthalene type epoxy resin, difunctional alicyclic epoxy resin, difunctional glycidyl ester type epoxy resin (such as diglycidyl phthalate, diglycidyl tetrahydrophthalate, diglycidyl dimer acid, etc.), difunctional glycidyl amine type epoxy resin (such as diglycidyl aniline, diglycidyl toluidine, etc.), difunctional heterocyclic epoxy resin, difunctional diaryl sulfone type epoxy resin, hydroquinone type epoxy resin (such as hydroquinone diglycidyl ether, 2,5-di-tert-butyl hydroquinone diglycidyl ether, resorcinol diglycidyl ether, etc.), difunctional alkylene glycidyl ether compounds (such as butanediol diglycidyl ether, butenediol diglycidyl ether, butynediol diglycidyl ether, etc.), difunctional glycidyl-containing hydantoin compounds (such as 1,3-diglycidyl-5,5-dialkylhydantoin, 1-glycidyl-3-(epoxypropoxyalkyl)-5,5-dialkylhydantoin, etc.), difunctional glycidyl-containing siloxanes (such as 1,3-bis(3-epoxypropoxypropyl)-1,1,3,3-tetramethyldisiloxane, α,β-bis(3-epoxypropoxypropyl)polydimethylsiloxane, etc.), and modified products thereof. Among them, from the viewpoints of reactivity and operability, bisphenol A type epoxy resin, bisphenol F type epoxy resin, and biphenyl type epoxy resin are preferred.

[0072] Examples of the difunctional compound having a phenolic hydroxyl group as the above (b) include mononuclear aromatic dihydroxy compounds having one benzene ring such as catechol, resorcinol, and hydroquinone, bisphenols such as bis(4-hydroxyphenyl)propane (bisphenol A), bis(4-hydroxyphenyl)methane (bisphenol F), bis(4-hydroxyphenyl)ethane (bisphenol AD), compounds having a condensed ring such as dihydroxynaphthalene, difunctional phenolic compounds having an allyl group introduced such as diallyl resorcinol, diallyl bisphenol A, and triallyl dihydroxybiphenyl, and dibutyl bisphenol A.

[0073] Specific examples of the carboxyl group-containing compound in the above (b) include adipic acid, succinic acid, malonic acid, cyclohexanedicarboxylic acid, phthalic acid, isophthalic acid, terephthalic acid, etc.

[0074] Specific examples of the bifunctional compound having a mercapto group in the above (b) include, for example, ethylene glycol bis(mercaptoacetate), ethylene glycol bis(mercaptopropionate), etc.

[0075] Specific examples of the bifunctional compound containing an isocyanate group in the above (b) include diphenylmethane diisocyanate (MDI), isophorone diisocyanate (IPDI), hexamethylene diisocyanate (HMDI), toluene diisocyanate (TDI), etc.

[0076] Specific examples of the bifunctional compound containing a cyanate group in the above (b) include 2,2-bis(4-cyanatophenyl)propane, 1,1-bis(4-cyanatophenyl)ethane, bis(4-cyanatophenyl)methane, etc.

[0077] In the above (b), from the viewpoint of obtaining a thermoplastic polymer, a bifunctional compound having a phenolic hydroxyl group is preferred. From the viewpoints of heat resistance and adhesiveness, a bifunctional compound having two phenolic hydroxyl groups and having a bisphenol structure or a biphenyl structure is preferred. From the viewpoints of heat resistance and cost, bisphenol A, bisphenol F, or bisphenol S is preferred.

[0078] When the above (a) is bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, or biphenyl type epoxy resin, and the above (b) is bisphenol A, bisphenol F, or bisphenol S, the polymer obtained by the polymerization of the above (a) and (b) has a main chain composed of a p-phenylene structure and an ether bond as a main skeleton, which are connected by an alkylene group, and hydroxyl groups generated by addition polymerization are arranged on the side chains.

[0079] The linear structure composed of a p-phenylene skeleton can improve the mechanical strength of the polymer after polymerization, and the hydroxyl groups arranged on the side chains can improve the adhesion to the substrate. As a result, high adhesive strength can be achieved while maintaining the workability of the thermosetting resin. Furthermore, in the case of a thermoplastic resin, it can be recycled and repaired by softening and melting it with heat, which can improve the recyclability and reparability, which are problems in thermosetting resins.

[0080] "Phenoxy Resin"

[0081] Phenoxy resin is a polyhydroxy polyether synthesized from bisphenols and epichlorohydrin, and has thermoplasticity. In the manufacture of phenoxy resin, methods using the direct reaction of bisphenols and epichlorohydrin and methods using the addition polymerization reaction of diglycidyl ethers of bisphenols and bisphenols are known, and the phenoxy resin used in the present invention can be obtained by any production method. In the case of the direct reaction of bisphenols and epichlorohydrin, examples of bisphenols include phenols such as bisphenol A, bisphenol F, bisphenol S, biphenol, biphenylenediol, and fluorene diphenyl; aliphatic diols such as ethylene glycol, propylene glycol, and diethylene glycol. Among them, bisphenol A, bisphenol F, and bisphenol S are preferred in terms of cost, adhesiveness, viscosity, and heat resistance. They can be used alone or in combination of two or more.

[0082] Phenoxy resin has a chemical structure similar to that of epoxy resin, having a main chain formed by connecting p-phenylene structures and ether bonds as the main skeleton and a structure in which hydroxyl groups are arranged in side chains.

[0083] "Physical Properties of Thermoplastic Epoxy Resin and Phenoxy Resin"

[0084] For the above-mentioned thermoplastic epoxy resin and phenoxy resin, the weight-average molecular weight in terms of polystyrene obtained by GPC (gel permeation chromatography) measurement is preferably 10,000 to 500,000, more preferably 18,000 to 300,000, and further preferably 20,000 to 200,000. The weight-average molecular weight is calculated from the elution peak position detected by GPC and is a molecular weight value converted by standard polystyrene. If the weight-average molecular weight is within this range, the balance between thermoplasticity and heat resistance is good, and a bonded body can be efficiently obtained by melting, and its heat resistance is also high. If the weight-average molecular weight is 10,000 or more, the heat resistance is excellent, and if the weight-average molecular weight is 500,000 or less, the viscosity during melting is low and the adhesiveness is high.

[0085] "Components Other than Resin Components in Solid Bonding Agents"

[0086] As needed, the solid bonding agent can contain fillers and additives as components other than the resin component within the range that does not hinder the purpose of the present invention.

[0087] Examples of fillers include inorganic fillers and organic fillers (resin powders).

[0088] Examples of inorganic fillers include, for example, spherical fused silica, metal powders of metals such as iron, silica sand, talc, calcium carbonate, mica, acid clay, diatomaceous earth, kaolin, quartz, titanium oxide, silica, phenolic resin microspheres, glass spheres, etc.

[0089] In the case of containing fillers, the content of the fillers in the total amount of 100% by volume of the solid binder is preferably 50% by volume or less, more preferably 30% by volume or less, still more preferably 20% by volume or less, and most preferably 10% by volume or less.

[0090] The content (% by volume) of the fillers is determined from the addition amount at 25°C. Specifically, relative to the mass % of the fillers, based on the specific gravity of the components other than the fillers and the true specific gravity of the fillers, it is calculated by the following (Equation 1).

[0091] (Equation 1)

[0092] X = (MF / DF) ÷ (MF / DF + (100 - MF) / DR) × 100%

[0093] In (Equation 1),

[0094] X: Content (% by volume) of the fillers

[0095] MF: Addition amount (mass %) of the fillers

[0096] DR: Specific gravity after curing of the resin component

[0097] DF: True specific gravity of the fillers

[0098] Examples of the additives include defoamers, coupling agents such as silane coupling agents, pigments, etc., and one or more of them may be contained.

[0099] The content of the additives in the solid binder is preferably 10% by mass or less, more preferably 5% by mass or less, still more preferably 1% by mass or less.

[0100] The content of the resin component in the solid binder is preferably 10% by mass or more, more preferably 20% by mass or more, still more preferably 30% by mass or more, even more preferably 50% by mass or more, 80% by mass or more in one embodiment, 90% by mass or more in another embodiment, and 99% by mass or more in yet another embodiment.

[0101] "Manufacturing Method of Solid Binder"

[0102] The manufacturing method of the solid binder is not particularly limited. For example, it can be obtained by heating and polymerizing a monomer or oligomer of a bifunctional epoxy compound. In order to reduce the viscosity during polymerization and facilitate stirring, a solvent can be added. In the case of adding a solvent, it needs to be removed, and the solid binder can be obtained by drying or polymerizing on a release film or the like or both of these methods.

[0103] As the above-mentioned additives, for example, viscosity modifiers, inorganic fillers, organic fillers (resin powders), defoamers, coupling agents such as silane coupling agents, pigments, etc. can be cited, and one of them or two or more of them can be used in combination.

[0104] As the viscosity modifier, for example, a reactive diluent or the like can be used.

[0105] As the inorganic filler, for example, spherical fused silica, metal powders of metals such as iron, silica sand, talc, calcium carbonate, mica, acid clay, diatomaceous earth, kaolin, quartz, titanium oxide, silica, phenolic resin microspheres, glass beads, etc. can be cited.

[0106] The solid binder thus obtained has excellent storage stability because the content of unreacted monomers and terminal epoxy groups is small or substantially absent, and can also be stored at room temperature for a long time.

[0107] The form of the solid binder is not particularly limited, and it preferably has any shape selected from films, rods, pellets, and powders. In particular, it is preferably such that at least one side of the outer shape is 5 mm or less, more preferably 3 mm or less, further preferably 1 mm or less, still more preferably 0.5 mm or less, and most preferably 0.3 mm or less. If the size is within this range, it can be sandwiched between the substrate A and the substrate B and efficiently spread on the bonding surface by heating and pressing to obtain a high adhesive force.

[0108] The solid binder can have adhesiveness within a range that does not hinder the adhesive force and its heat resistance. In this case, in the laminate preparation step, the above-mentioned solid binder is temporarily fixed to the substrate.

[0109] <Bonding step>

[0110] In the bonding step, the above-mentioned laminate is heated and pressed to melt the above-mentioned solid binder, and then the above-mentioned solid binder is cured by lowering the temperature to bond the above-mentioned substrate A and the above-mentioned substrate B.

[0111] The temperature in the above-mentioned heating and pressing is preferably 100 to 400 °C, more preferably 120 to 350 °C, and further preferably 150 °C to 300 °C. By heating at 100 to 400 °C, the above-mentioned solid binder is efficiently deformed and melted, and effectively wets and spreads on the bonding surface, so that a high adhesive force can be obtained.

[0112] The applied pressure in the above heating and pressing is preferably 0.01 to 20 MPa, more preferably 0.1 to 10 MPa, and still more preferably 0.2 to 5 MPa. If it is within this pressure range, the above solid binder deforms efficiently and wets and spreads effectively on the bonding surface, so that a high bonding force can be obtained. When at least one of the base materials A or B is a thermoplastic resin, by pressing at 0.01 to 20 MPa, the solid binder can be made compatible with the base material, and a strong bonding force can be obtained.

[0113] The amorphous thermoplastic resin contained in the solid binder has a low cohesive force within the resin and has hydroxyl groups, so it has a strong interaction with the base material and can bond dissimilar materials with a bonding force higher than that of conventional crystalline hot-melt adhesives.

[0114] The bonding of the above base material A and the above base material B utilizes the phase change (solid state - liquid state - solid state) of the solid binder and does not involve a chemical reaction. Therefore, compared with conventional thermosetting epoxy resins, the bonding can be completed in a short time.

[0115] [Manufacturing method of bonded body_Embodiment 2]

[0116] The manufacturing method of the bonded body of this embodiment is a manufacturing method of a bonded body formed by sequentially bonding a base material A as a fiber-reinforced plastic base material, a solid binder, and a base material B as a metal base material. The solid binder contains an amorphous thermoplastic resin selected from at least one of a thermoplastic epoxy resin and a phenoxy resin; this method includes a first bonding step and a second bonding step. The first bonding step: in a state where the solid binder is in surface contact with the base material A, melting and then curing the solid binder, thereby bonding the base material A and the solid binder, or in a state where the solid binder is in surface contact with the base material B, melting and then curing the solid binder, thereby bonding the base material B and the solid binder; The second bonding step: in a state where the solid binder bonded to the base material A is in surface contact with the base material B, melting and then curing the solid binder, thereby bonding the base material A and the base material B, or in a state where the solid binder bonded to the base material B is in surface contact with the base material A, melting and then curing the solid binder, thereby bonding the base material A and the base material B; The epoxy equivalent of the amorphous thermoplastic resin is 1,600 g / eq. or more or does not contain an epoxy group, and the heat of fusion is 15 J / g or less.

[0117] According to this manufacturing method, the bonding of the above-mentioned base material A and the above-mentioned base material B utilizes the phase change (solid state - liquid state - solid state) of a solid bonding agent containing an amorphous thermoplastic resin, which is at least one selected from thermoplastic epoxy resins and phenoxy resins, and does not involve a chemical reaction. Therefore, compared with conventional thermosetting epoxy resins, bonding can be completed in a short time, and the open time is also long. In addition, thermoplastic epoxy resins and phenoxy resins have low cohesion within the resin and have hydroxyl groups, so they have a strong interaction with the base material and can bond dissimilar materials with a higher bonding force than conventional crystalline hot melt adhesives.

[0118] In addition, in this manufacturing method, the process is divided into a first bonding process and a second bonding process for bonding. By separating in this way, heating can be carried out at a temperature suitable for the bonding interface for bonding, and a bonded body with excellent bondability can be manufactured. In addition, compared with the case where the process is not separated, the control of the heating temperature becomes easier. Furthermore, by pre-bonding the solid bonding agent to the base material A in advance, the base material A and the base material B can be bonded with high precision, and the generation of deviation at the bonding part can be suppressed.

[0119] <First bonding process>

[0120] The first bonding process is a process of bonding the above-mentioned base material A and the above-mentioned solid bonding agent by melting and then curing the above-mentioned solid bonding agent in a state where the above-mentioned solid bonding agent is in surface contact with the above-mentioned base material A, or a process of bonding the above-mentioned base material B and the above-mentioned solid bonding agent by melting and then curing the above-mentioned solid bonding agent in a state where the above-mentioned solid bonding agent is in surface contact with the above-mentioned base material B.

[0121] In the first bonding process, by pre-bonding the base material A or the base material B with the above-mentioned solid bonding agent, the base material A and the base material B can be bonded with good precision.

[0122] It should be noted that in this specification, "curing" means being solid at normal temperature, that is, having no fluidity in an unpressurized state at 23°C. However, the film after the first bonding process may also have adhesiveness.

[0123] As a method for melting the above-mentioned solid bonding agent, at least one method selected from contact heating, hot air heating, hot pressing, hot plate welding, infrared heating, ultrasonic welding, vibration welding, and high-frequency induction welding can be cited. Among them, infrared heating is preferred in terms of manufacturing ease and shortening the bonding process.

[0124] In the case of melting the solid binder by heating, it is preferable to heat the bonding surface of the base material A or the base material B with the solid binder to 100 to 300 °C to melt it, more preferably 120 to 250 °C, and further preferably 150 °C to 220 °C. By heating at 100 to 300 °C, the above-mentioned film deforms and melts efficiently, and effectively wets and spreads on the bonding surface, so that a high bonding force can be obtained.

[0125] As a method for curing the molten solid binder, a method of natural cooling at room temperature or a method of natural cooling using a cooling device can be cited. It should be noted that "room temperature" refers to the usual room temperature in the range of 5 to 30 °C. Among them, from the aspect of manufacturing ease, a method of natural cooling at room temperature is preferred.

[0126] (Solid binder)

[0127] The solid binder is the same as that in the above-mentioned Embodiment 1, but the solid binder in this embodiment is preferably a film. In the present disclosure, a film refers to a sheet having a thickness of 10 μm to 3 mm.

[0128] 《Morphology of the film》

[0129] From the aspect of obtaining a bonded body with excellent bondability in a short bonding process time, the thickness of the film is preferably 1 mm or less, more preferably 0.5 mm or less, further preferably 0.3 mm or less, still further preferably 0.2 mm or less, and most preferably 0.1 mm or less.

[0130] If the size is within this range, it can be sandwiched between the base material A and the base material B, and can be efficiently spread on the bonding surface by heating, pressing, etc., to obtain a high bonding force.

[0131] The film can be a single layer or a laminate including multiple layers. From the aspects of manufacturing ease and improving the bonding force, a single layer is preferred.

[0132] In addition, the film can have adhesiveness within a range that does not hinder the bonding force and its heat resistance.

[0133] 《Method for manufacturing the film》

[0134] The method for manufacturing the film is not particularly limited. For example, a resin composition can be obtained by heating and polymerizing a monomer or oligomer of a bifunctional epoxy compound, and a solvent can be added to the obtained resin composition as needed, coated on a release film, etc., cured, dried, and pressed as needed, thereby obtaining a film.

[0135] <Second bonding process>

[0136] The second bonding step is a step of bonding the substrate A and the substrate B by melting and then solidifying the solid bonding agent while the solid bonding agent bonded to the substrate A is in surface contact with the substrate B, or a step of bonding the substrate A and the substrate B by melting and then solidifying the solid bonding agent while the solid bonding agent bonded to the substrate B is in surface contact with the substrate A.

[0137] From the aspect of obtaining high bonding strength, in the second bonding step, it is preferable to heat at a temperature equal to or higher than the melting point of at least one of the substrate A and the solid bonding agent to melt and then solidify the solid bonding agent. By heating at a temperature equal to or higher than the melting point of at least one of the substrate A and the solid bonding agent, the solid bonding agent and the substrate become compatible, and it is easy to obtain a stronger bonding strength.

[0138] As a method for melting the solid bonding agent, at least one method selected from contact heating, hot air heating, hot pressing, infrared heating, hot plate welding, ultrasonic welding, vibration welding, and high-frequency induction welding can be cited. Among them, hot pressing, ultrasonic welding, and high-frequency induction welding are preferable.

[0139] There are no particular restrictions on the conditions for hot pressing.

[0140] For example, the temperature is preferably 100 to 400 °C, more preferably 120 to 350 °C, and further preferably 150 °C to 300 °C. By heating at 100 to 400 °C, the above solid bonding agent deforms and melts efficiently, and wets and spreads effectively on the bonding surface, so a high bonding strength can be obtained.

[0141] The applied pressure in the above hot pressing is preferably 0.01 to 20 MPa, more preferably 0.1 to 10 MPa, and further preferably 0.2 to 5 MPa. If it is within this pressure range, the above solid bonding agent deforms efficiently and wets and spreads effectively on the bonding surface, so a high bonding strength can be obtained.

[0142] There are no particular restrictions on the conditions for high-frequency induction welding.

[0143] For example, the emission frequency is preferably 0.1 to 3 MHz, more preferably 0.5 to 2 MHz.

[0144] From the aspects of adhesiveness and appearance, the high-frequency application time is preferably 0.1 to 120 seconds, more preferably 1 to 60 seconds.

[0145] When applying high frequency while pressing substrate A and substrate B, the applied pressure is preferably 0.01 to 20 MPa, more preferably 0.1 to 10 MPa, and further preferably 0.2 to 5 MPa. If it is within this pressure range, the above-mentioned solid binder deforms efficiently and wets and spreads effectively on the bonding surface, so a high bonding force can be obtained.

[0146] There are no particular restrictions on the conditions for high-frequency induction welding.

[0147] For example, the output power can be in the range of 100 to 10000 W.

[0148] There are no particular restrictions on the conditions for ultrasonic welding.

[0149] For example, the emission frequency is preferably 10 to 70 kHz, more preferably 15 to 40 kHz.

[0150] Considering the adhesiveness and appearance, the ultrasonic application time is preferably 0.1 to 3 seconds, more preferably 0.2 to 2 seconds.

[0151] When applying ultrasonic waves while pressing substrate A and substrate B, the applied pressure is preferably 0.01 to 20 MPa, more preferably 0.1 to 10 MPa, and further preferably 0.2 to 5 MPa. If it is within this pressure range, the above-mentioned solid binder deforms efficiently and wets and spreads effectively on the bonding surface, so a high bonding force can be obtained.

[0152] There are no particular restrictions on the conditions for ultrasonic welding.

[0153] For example, the oscillation frequency can be in the range of 1 to 1500 kHz. It is only necessary to adjust it to an appropriate oscillation frequency according to the size and type of substrate A and substrate B.

[0154] The output power can be in the range of 100 to 5000 W.

[0155] The oscillation time can be adjusted according to the size and type of substrate A and substrate B. For example, it is preferably 1.0 to 10.0 seconds, more preferably 1.5 to 8.0 seconds.

[0156] As described above, the bonding of substrate A and substrate B utilizes the phase change (solid state - liquid state - solid state) of the solid binder and does not involve chemical reactions. Therefore, compared with conventional thermosetting epoxy resins, the bonding can be completed in a short time.

[0157] [Bonded body]

[0158] Figure 1 One embodiment of the bonded body of the present invention is shown. Figure 1The bonded body 1 shown is a bonded body formed by bonding a substrate A (3) as a fiber-reinforced plastic substrate and a substrate B (4) as a metal substrate together through a bonding layer 2. The bonding layer 2 is formed by melting and then solidifying a solid bonding agent containing an amorphous thermoplastic resin, and the amorphous thermoplastic resin is at least one selected from thermoplastic epoxy resins and phenoxy resins. The bonded body of the present invention shows excellent bonding strength even if it is a bonded body of dissimilar materials. For the bonding strength, in addition to the strength of the interfacial interaction acting between the bonding layer and substrate A and between the bonding layer and substrate B, it is also affected by various factors such as the thickness of the bonding layer, the molecular weight, chemical structure, mechanical properties, and viscoelastic properties of the polymer constituting the solid bonding agent. Therefore, the detailed mechanism by which the bonded body of the present invention shows excellent bonding strength is not yet clear, but it is speculated that the main reason is that the cohesive force in the amorphous thermoplastic resin constituting the bonding layer 2 is low, and there are hydroxyl groups in the resin, forming chemical bonds and intermolecular forces such as hydrogen bonds and van der Waals forces at the interfaces between the bonding layer and substrate A and between the bonding layer and substrate B. However, in the said bonded body, the state or properties of the interface of the bonded body are extremely thin chemical structures below the nanoscale and are difficult to analyze. At the current technical level, it is impossible or impractical to determine the mechanism in order to distinguish it from the case where a solid bonding agent is not used and express it.

[0159] The recyclability and reparability of the bonded body of the present invention in which the bonding layer is formed of a thermoplastic resin are excellent, and by heating the bonded body, it can be easily disassembled into substrate A and substrate B.

[0160] Substrate A is not limited to a specific fiber-reinforced plastic (FRP). For example, glass fiber-reinforced plastic (GFRP), carbon fiber-reinforced plastic (CFRP), boron fiber-reinforced plastic (BFRP), aromatic polyamide fiber-reinforced plastic (AFRP), etc., in which various fibers are compounded in thermosetting resins such as polyurethane resin, epoxy resin, vinyl ester resin, unsaturated polyester, polyamide resin, and phenolic resin to improve the strength. Molded bodies formed of glass fiber, carbon fiber SMC (sheet molding compound), etc.

[0161] Substrate B is not limited to a specific metal. For example, iron, aluminum, copper, magnesium, titanium, etc. can be cited. Among them, considering aspects such as light weight and ease of processing, it is particularly preferable to use aluminum and copper. It should be noted that in the present disclosure, the term "aluminum" is used in the sense of including aluminum and its alloys. Similarly, iron, copper, aluminum, magnesium, and titanium are also used in the sense of including their simple substances and their alloys (such as stainless steel and duralumin).

[0162] The shapes of substrate A and substrate B are not particularly limited.

[0163] By performing pretreatment suitable for each of substrate A and substrate B on the substrates, high adhesive force can sometimes be obtained.

[0164] As the pretreatment, pretreatment for cleaning the surface of the substrate or pretreatment for imparting unevenness to the surface can be cited. Specifically, degreasing treatment, UV ozone treatment, sandblasting treatment, polishing treatment, plasma treatment, corona discharge treatment, laser treatment, etching treatment, flame treatment, etc. can be listed. The pretreatment can be only one kind, or two or more kinds can be implemented. As specific methods of these pretreatments, known methods can be used.

[0165] The above degreasing treatment refers to a method of dissolving and removing dirt such as grease on the surface of the substrate with an organic solvent such as acetone or toluene.

[0166] The above UV ozone treatment refers to a method of cleaning or modifying the surface with the energy of short-wavelength ultraviolet rays emitted by a low-pressure mercury lamp and the power of ozone (O3) generated therefrom. In the case of glass, it becomes one of the surface cleaning methods for removing organic impurities on the surface. Usually, a cleaning surface modification device using a low-pressure mercury lamp is called a "UV ozone cleaner", "UV cleaning device", "ultraviolet surface modification device", etc.

[0167] As the above sandblasting treatment, for example, wet sandblasting treatment, shot peening treatment, sandblasting treatment, etc. can be listed. Among them, wet sandblasting treatment can obtain a denser surface compared with dry sandblasting treatment, so it is preferred.

[0168] As the above polishing treatment, for example, polishing using a polishing cloth, roll polishing using abrasive paper (sandpaper), electrolytic polishing, etc. can be listed.

[0169] The above plasma treatment refers to a method of making a plasma beam with a high-voltage power supply and a rod, making it collide with the surface of the raw material, exciting the molecules to become a functional state, and an atmospheric pressure plasma treatment method capable of imparting hydroxyl groups and polar groups to the surface of the raw material can be listed.

[0170] The above corona discharge treatment can be cited as a method for surface modification of a polymer film, which is a method of generating hydroxyl groups and polar groups on the surface starting from free radicals generated by cutting the main chain and side chain of the polymer surface layer by electrons released from the electrode.

[0171] The above laser treatment is a technique for improving surface characteristics by rapidly heating and cooling only the surface of the substrate by laser irradiation, and is an effective method for roughening the surface. Known laser treatment techniques can be used.

[0172] As the above etching treatment, for example, chemical etching treatments such as alkali method, phosphoric acid-sulfuric acid method, fluoride method, chromic acid-sulfuric acid method, ferric chloride method, etc., and electrochemical etching treatments such as electrolytic etching method, etc. can be listed.

[0173] The above-mentioned flame treatment refers to a method of making oxygen in the air plasma by burning a mixed gas of combustion gas and air, applying oxygen plasma to the object to be treated, and thereby achieving surface hydrophilization. Known flame treatment techniques can be used.

[0174] Examples

[0175] Next, specific examples of the present invention will be described, but the present invention is not particularly limited to these examples. In the following examples, substrate A and substrate B are collectively referred to as the bonding substrate.

[0176] <Bonding substrate>

[0177] The following bonding substrates are used.

[0178] Substrate A:

[0179] 《PA6 (Nylon 6)-CF40》

[0180] Daisel Plastron PA6-CF40-01 (L9) was injection molded to obtain a test piece with a width of 10 mm, a length of 45 mm, and a thickness of 3 mm. It was used without surface treatment.

[0181] Substrate B:

[0182] 《Aluminum》

[0183] The surface of A6061-T6 was sandblasted to obtain a test piece with a width of 10 mm, a length of 45 mm, and a thickness of 3 mm.

[0184] <Weight average molecular weight, heat of fusion, and epoxy equivalent of thermoplastic epoxy resin and phenoxy resin>

[0185] The weight average molecular weight, heat of fusion, and epoxy equivalent of the solid bonding agent were determined as follows, respectively.

[0186] (Weight average molecular weight)

[0187] The thermoplastic epoxy resin and phenoxy resin were dissolved in tetrahydrofuran, and using Prominence 501 (manufactured by Showa Kagaku Co., Ltd., Detector: Shodex (registered trademark) RI-501 (manufactured by Showa Denko K.K.)), the measurement was carried out under the following conditions.

[0188] Column: Two LF-804 columns manufactured by Showa Denko K.K.

[0189] Column temperature: 40 °C

[0190] Sample: 0.4 mass% tetrahydrofuran solution of the resin

[0191] Flow rate: 1 ml / min

[0192] Eluent: Tetrahydrofuran

[0193] Calibration method: Conversion based on standard polystyrene

[0194] (Heat of fusion)

[0195] Weigh 2 - 10 mg of thermoplastic epoxy resin and phenoxy resin, place them in an aluminum pan, and use DSC (DSC8231 manufactured by Rigaku Corporation) to heat from 23°C to 200°C at 10°C / min to obtain a DSC curve. Calculate the heat of fusion from the area of the endothermic peak during melting on this DSC curve and the above weighing value.

[0196] (Epoxy equivalent)

[0197] Perform the measurement in accordance with JIS K - 7236:2001 and convert it to a value based on the resin solids. Additionally, in the case of a simple mixture without a reaction, calculate it from the respective epoxy equivalent and content.

[0198] <Example 1>

[0199] (Solid binder P - 1)

[0200] In a reaction apparatus equipped with a stirrer, reflux condenser, gas inlet tube, and thermometer, add 1.0 equivalent (203 g) of jER (registered trademark) 1007 (bisphenol A type epoxy resin, weight - average molecular weight of about 10,000, manufactured by Mitsubishi Chemical Corporation), 1.0 equivalent (12.5 g) of bisphenol S, 2.4 g of triphenylphosphine, and 1,000 g of methyl ethyl ketone. Heat to 100°C with stirring under a nitrogen atmosphere. Visually confirm dissolution, cool to 40°C to obtain a resin composition with a solid content of about 20% by mass. Remove the solvent from it to obtain a solid. Set non - stick fluororesin films (Nitoflon (registered trademark) No.900UL, manufactured by Nitto Denko Corporation) on the upper and lower plates of a press. After placing the above solid on the non - stick fluororesin film on the lower plate, heat the press to 160°C and heat - compress the above resin composition for 2 hours to obtain a film - like solid binder (P - 1) with a solid content of 100% by mass and a thickness of 100 μm. The weight - average molecular weight is about 37,000. The epoxy equivalent is above the detection limit. No heat - of - fusion peak was detected in DSC.

[0201] (Bonded body: Substrate A 《PA6 (nylon 6) - CF40》, Substrate B 《aluminum》)

[0202] On the above-mentioned aluminum substrate (substrate B), the above-mentioned solid binder P-1 cut into a size of 10×15 mm is arranged, and then the above-mentioned PA6-CF substrate (substrate A) is quickly arranged thereon. The overlap of these substrates with each other is set to a width of 10 mm and a depth of 5 mm. The above-mentioned solid binder P-1 is arranged so as to cover the entire overlapping area of the substrates with each other. That is, a non-bonded laminate is prepared in a state where substrate A and substrate B do not directly contact each other and the above-mentioned solid binder is sandwiched between them. In this specification, "quickly afterwards" means aiming to be within about 30 minutes.

[0203] In addition, for the evaluation of the open time, after arranging the solid binder P-1 on the above-mentioned aluminum substrate (substrate B) and allowing it to stand for 3 days, then placing the above-mentioned PA6-CF substrate (substrate A), and except for this, the same operations as above are carried out to produce a bonded body for open time evaluation.

[0204] Using a high-frequency induction welding machine (manufactured by Seiden Electronics Industry Co., Ltd., oscillator UH-2.5K, press JIIP30S), the metal is heated by high-frequency induction, and the test pieces are bonded by heating and pressing. The applied pressure is set to 110 N (pressure 2.2 MPa), the oscillation frequency is set to 900 kHz, and the oscillation time is set to 5 seconds.

[0205] <Example 2>

[0206] (Solid binder P-2)

[0207] In a reaction device equipped with a stirrer, a reflux condenser, a gas inlet tube, and a thermometer, 20 g of Enotoat (registered trademark) YP-50S (manufactured by Nippon Steel Chemical & Material Co., Ltd., phenoxy resin, weight average molecular weight of about 50,000) and 80 g of cyclohexanone are added, heated to 60 °C while stirring, visually confirmed to be dissolved, and cooled to 40 °C to obtain a resin composition with a solid content of 20% by mass. The solvent is removed from it to obtain a film-like solid binder (P-2) with a solid content of 100% and a thickness of 100 μm. The weight average molecular weight is 50,000, and the epoxy equivalent is above the detection limit. No heat of fusion peak is detected in DSC.

[0208] (Bonded body)

[0209] Except for using P-2 as the solid binder, the same operations as in Example 1 are carried out to produce a bonded body and a bonded body for open time evaluation.

[0210] <Example 3>

[0211] (Solid binder P-3)

[0212] The above resin composition P-2 and crystalline epoxy resin YSLV-80XY (manufactured by Nippon Steel Chemical & Material Co., Ltd.) were mixed at a mass ratio of 98:2 to obtain a solid binder (P-3). The weight-average molecular weight was 36,000, the epoxy equivalent was 9600 g / eq, and the heat of fusion was 2 J / g.

[0213] (Bonded body)

[0214] Except for using P-3 as the solid binder, the same operations as in Example 1 were carried out to fabricate a bonded body and a bonded body for open time evaluation.

[0215] <Example 4>

[0216] (Solid binder P-4)

[0217] The above resin composition P-2 and crystalline epoxy resin YSLV-80XY (manufactured by Nippon Steel Chemical & Material Co., Ltd.) were mixed at a mass ratio of 94:6 to obtain a solid binder (P-4). The weight-average molecular weight was 35,000, the epoxy equivalent was 2100 g / eq, and the heat of fusion was 4 J / g.

[0218] (Bonded body)

[0219] Except for using P-4 as the solid binder, the same operations as in Example 1 were carried out to fabricate a bonded body and a bonded body for open time evaluation.

[0220] <Example 5>

[0221] (Solid binder P-5)

[0222] The above resin composition P-2 and crystalline epoxy resin YSLV-80XY (manufactured by Nippon Steel Chemical & Material Co., Ltd.) were mixed at a mass ratio of 89:11 to obtain a solid binder (P-5). The weight-average molecular weight was 33,000, the epoxy equivalent was 1745 g / eq, and the heat of fusion was 11 J / g.

[0223] (Bonded body)

[0224] Except for using P-5 as the solid binder, the same operations as in Example 1 were carried out to fabricate a bonded body and a bonded body for open time evaluation.

[0225] <Example 6>

[0226] (Solid binder P-6)

[0227] In a reaction apparatus equipped with a stirrer, a reflux condenser, a gas inlet tube, and a thermometer, 1.0 equivalent (203 g) of jER (registered trademark) 1007 (manufactured by Mitsubishi Chemical Corporation, bisphenol A type epoxy resin, molecular weight approximately 4060), 0.6 equivalent (12.5 g) of bisphenol S (molecular weight 250), 2.4 g of triphenylphosphine, and 1,000 g of methyl ethyl ketone were added. While stirring under a nitrogen atmosphere, the temperature was raised to 100 °C. After visually confirming dissolution, it was cooled to 40 °C to obtain a resin composition containing approximately 20% by mass of solids. The solvent was removed therefrom to obtain a solid. Non-stick fluororesin films (Nitoflon (registered trademark) No. 900UL, manufactured by Nitto Denko Corporation) were provided on the upper and lower plates of a press. After placing the above solid on the non-stick fluororesin film on the lower plate, the press was heated to 160 °C, and the above resin composition was heated and compressed for 2 hours to obtain a film-like solid binder (P-6) with 100% by mass of solids and a thickness of 100 μm. The weight average molecular weight was approximately 30,000, and the epoxy equivalent was above the detection limit. No heat of fusion peak was detected in DSC.

[0228] (Bonded body)

[0229] Regarding the method for producing the bonded body, except for using P-6 as the solid binder, the same operations as in Example 1 were carried out to produce a bonded body and a bonded body for open time evaluation.

[0230] <Example 7>

[0231] When producing the bonded body, the above solid binder P-1 was placed on an aluminum substrate (substrate B), heated on a hot plate at 200 °C for 1 minute to melt the film, and then naturally cooled at room temperature for 1 minute to cure the film. After bonding the aluminum substrate (substrate B) to the film, it was laminated in such a way that the bonding material was in surface contact with the above PA6-CF substrate (substrate A). Except for this, the same operations as in Example 1 were carried out to obtain a bonded body.

[0232] <Comparative Example 1>

[0233] (Solid binder Q-1)

[0234] Two liquids of a thermosetting liquid epoxy adhesive E-250 (manufactured by Konishi Co., Ltd., a two-component type of bisphenol type epoxy resin and an amine curing agent) were mixed, coated on a release film, cured at 100 °C for 1 hour, cooled, and peeled off from the release film to obtain a film-like solid binder (Q-1) with a thickness of 100 μm. No heat of fusion peak was detected in DSC. Since it is insoluble in solvents, the epoxy equivalent and the weight average molecular weight could not be measured.

[0235] (Bonded body)

[0236] Except for using Q-1 as the solid-state binder, the same operations as in Example 1 were carried out to fabricate the bonded body and the bonded body for open time evaluation.

[0237] <Comparative Example 2>

[0238] (Solid-state binder Q-2)

[0239] An amorphous polycarbonate film (Iupilon (registered trademark) FE2000, manufactured by Mitsubishi Engineering-Plastics Corporation, thickness 100 μm) was used as the solid-state binder Q-2. No heat of fusion peak was detected in DSC.

[0240] (Bonded body)

[0241] Except for using Q-2 as the solid-state binder, the same operations as in Example 1 were carried out to fabricate the bonded body and the bonded body for open time evaluation.

[0242] <Comparative Example 3>

[0243] (Solid-state binder Q-3)

[0244] A crystalline epoxy resin YSLV-80XY (manufactured by Nippon Steel Chemical & Material Co., Ltd.) was used as the solid-state binder (Q-3). The epoxy equivalent was 192 g / eq. The weight-average molecular weight was 340. The heat of fusion was 70 J / g.

[0245] (Bonded body)

[0246] Except for using Q-3 as the solid-state binder, the same operations as in Example 1 were carried out to fabricate the bonded body and the bonded body for open time evaluation.

[0247] <Comparative Example 4>

[0248] (Bonded body)

[0249] Two liquids of a thermosetting liquid epoxy adhesive E-250 (manufactured by Konishi Co., Ltd., a two-component type of bisphenol-type epoxy resin and amine curing agent) were mixed and coated on the same substrates A and B as in Example 1 above, and were laminated within 1 minute. Then, they were left standing in an oven at 100 °C for 1 hour in a state fixed with jigs, thereby curing the adhesive components, and then cooled to room temperature, thus fabricating the bonded body.

[0250] In addition, after the above thermosetting liquid epoxy adhesive E-250 was coated on substrates A and B, they were left standing for 3 days and then laminated, and except for this, the same operations as above were carried out to fabricate the bonded body for open time evaluation.

[0251] <Comparative Example 5>

[0252] Add 1.0 equivalent (203 g) of jER (registered trademark) 1007 (manufactured by Mitsubishi Chemical Corporation, bisphenol A type epoxy resin, weight average molecular weight of about 10,000), 1.0 equivalent (12.5 g) of bisphenol S, 2.4 g of triphenylphosphine, and 1,000 g of methyl ethyl ketone to a flask, and stir at room temperature to obtain a liquid resin composition having about 20% by mass of a solid. Rod coat the above liquid resin composition on the same substrate B as in Example 1 above, dry at room temperature for 30 minutes, and then leave it standing in an oven at 160 °C for 2 hours to form a solid thermoplastic epoxy resin polymer coating with a thickness of 100 μm on the surface of substrate B. The weight average molecular weight of the coating is about 40,000. The epoxy equivalent is above the detection limit. No heat of fusion peak was detected in DSC.

[0253] (Bonded body)

[0254] Directly place substrate A on the above substrate B with the coating, and perform the same operations as in Example 1 except for this to produce a bonded body.

[0255] In addition, for the pot life evaluation, after forming a thermoplastic epoxy resin polymer coating on the surface of substrate B, leave it standing for 3 days, then laminate it with substrate A, and perform the same operations as above except for this to produce a bonded body for pot life evaluation.

[0256] <Comparative Example 6>

[0257] Add 20 g of Phenotote (registered trademark) YP-50S (manufactured by Nippon Steel Chemical & Material Co., Ltd., phenoxy resin, weight average molecular weight of about 50,000) and 80 g of cyclohexanone to a reaction apparatus equipped with a stirrer, a reflux condenser, a gas inlet tube, and a thermometer, heat it up to 60 °C while stirring, visually confirm dissolution, and cool it to 40 °C to obtain a liquid resin composition having 20% by mass of a solid. Rod coat the above liquid resin composition on the same substrate B as in Example 1 above, and leave it standing in an oven at 70 °C for 30 minutes to form a phenoxy resin coating with a thickness of 100 μm on the surface of substrate B. The weight average molecular weight of the coating is about 50,000. The epoxy equivalent is above the detection limit. No heat of fusion peak was detected in DSC.

[0258] (Bonded body)

[0259] Directly place substrate A on the above substrate B with the phenoxy resin coating, and perform the same operations as in Example 1 except for this to produce a bonded body.

[0260] In addition, for the pot life evaluation, after forming a phenoxy resin coating on the surface of substrate B, leave it standing for 3 days, then laminate it with substrate A, and perform the same operations as above except for this to also produce a bonded body for pot life evaluation.

[0261] <Comparative Example 7>

[0262] (Bonded body)

[0263] Except for using the crystalline polyamide-based hot-melt adhesive film NT-120 (manufactured by Nippon MatTai Co., Ltd., thickness 100 μm) as the solid binder, the same operations as in Example 1 were carried out to produce a bonded body and a bonded body for open time evaluation. The heat of fusion was 60 J / g.

[0264] [Shear adhesive strength]

[0265] After leaving the bonded bodies obtained in Examples 1 to 7 and Comparative Examples 1 to 7 standing at the measurement temperature (23 °C or 80 °C) for 30 minutes or more, according to ISO19095, a tensile shear bond strength test was carried out in an atmosphere of 23 °C and 80 °C using a tensile testing machine (universal testing machine Autograph “AG-X plus” (manufactured by Shimadzu Corporation), load cell 10 kN, tensile speed 10 mm / min) to measure the bond strength. The measurement results are shown in Tables 1-1 and 1-2.

[0266] [Bonding process time]

[0267] The bonding process time was measured as follows.

[0268] Taking the time when at least one of the base materials constituting the bonded body comes into contact with the binder as the starting point and the end of the production of the bonded body as the end point, the time from the starting point to the end point was measured. The measurement results are shown in Tables 1-1 and 1-2.

[0269] [Recyclability]

[0270] After heating the bonded body on a hot plate at 200 °C for 1 minute, it was judged whether it could be easily peeled off with a force of 1 N or less. If it could be peeled off, it was evaluated as good (A), and if it could not be peeled off, it was evaluated as inappropriate (B). The evaluation results are shown in Tables 1-1 and 1-2.

[0271] [Repairability]

[0272] In each test piece where the bonded surface broke at 23 °C in the above tensile shear strength test (a layer of bonded solid remained on the surface of substrate A or B or both), substrate A was placed on substrate B, and a bonded body was produced in the same manner as in Example 1 above, thereby obtaining a repaired bonded body. The shear adhesive strength at 23 °C of the above repaired bonded body was measured in the same manner as the above test method. If it was 80% or more of the first shear adhesive strength, it was evaluated as good (A), and if it was less than 80%, it was evaluated as inappropriate (B). The evaluation results are shown in Tables 1-1 and 1-2.

[0273] [Evaluation of open time]

[0274] Using the bonded body for open time evaluation, the above tensile shear bond strength test was carried out at 23°C. Compared with the test pieces produced by the methods of the above examples and comparative examples, if the shear bond force is 80% or more, it is evaluated as good (A), and if it is less than 80%, it is evaluated as inappropriate (B). An open time evaluation of good (A) means a long open time and excellent convenience. The evaluation results are shown in Tables 1-1 and 1-2.

[0275]

[0276]

[0277] Industrial applicability

[0278] The bonded body obtained by the production method of the present invention can be used as, for example, automotive parts such as door side panels, engine hoods, tailgates, steering hangers, A-pillars, B-pillars, C-pillars, D-pillars, crash boxes, power control unit (PCU) housings, electric compressor components (inner wall parts, air inlets, exhaust control valve (ECV) insertion parts, mounting boss parts, etc.), lithium-ion battery (LIB) spacers, battery cases, LED headlamps, etc., smartphones, notebook computers, tablet computers, smart watches, large liquid crystal displays (LCD-TVs), structures for outdoor LED lighting, etc., but is not particularly limited to these exemplified uses.

[0279] Symbol description

[0280] 1 Bonded body

[0281] 2 Adhesive layer

[0282] 3 Substrate A

[0283] 4 Substrate B

Claims

1. A method for manufacturing a bonded body, which includes a pre-bonding process and a bonding process. The pre-bonding process: Prepare a laminate by sequentially arranging substrate A as a fiber-reinforced plastic substrate, a solid bonding agent, and substrate B as a metal substrate. The solid bonding agent contains an amorphous thermoplastic resin, and the amorphous thermoplastic resin is at least one selected from thermoplastic epoxy resins and phenoxy resins. The bonding process: Heat and press the laminate to melt the solid bonding agent, thereby bonding substrate A and substrate B. The epoxy equivalent of the amorphous thermoplastic resin is 1,600 or more or does not contain an epoxy group, and the heat of fusion is 15 J / g or less.

2. The method for manufacturing a bonded body according to claim 1, wherein the heating and pressing are performed under the conditions of 100 to 400 °C and 0.01 to 20 MPa.

3. The method for manufacturing a bonded body according to claim 1 or 2, wherein the solid bonding agent before melting has a film shape.

4. A method for manufacturing a bonded body, which is a method for manufacturing a bonded body formed by sequentially bonding substrate A as a fiber-reinforced plastic substrate, a solid bonding agent, and substrate B as a metal substrate. The solid bonding agent contains an amorphous thermoplastic resin, and the amorphous thermoplastic resin is at least one selected from thermoplastic epoxy resins and phenoxy resins. This method includes a first bonding process and a second bonding process. The first bonding process: In a state where the solid bonding agent is in surface contact with substrate A, melt and then cure the solid bonding agent, thereby bonding substrate A and the solid bonding agent, or in a state where the solid bonding agent is in surface contact with substrate B, melt and then cure the solid bonding agent, thereby bonding substrate B and the solid bonding agent. The second bonding process: In a state where the solid bonding agent bonded to substrate A is in surface contact with substrate B, melt and then cure the solid bonding agent, thereby bonding substrate A and substrate B, or in a state where the solid bonding agent bonded to substrate B is in surface contact with substrate A, melt and then cure the solid bonding agent, thereby bonding substrate A and substrate B. The epoxy equivalent of the amorphous thermoplastic resin is 1,600 g / eq. or more or does not contain an epoxy group, and the heat of fusion is 15 J / g or less.

5. The method for manufacturing a bonded body according to claim 4, wherein in the first bonding process, the solid bonding agent is heated to 100 to 300 °C to be melted and then cured.

6. The method for manufacturing a bonded body according to claim 4, wherein in the second bonding process, the solid bonding agent is melted and then cured by at least one selected from contact heating, hot air heating, hot pressing, infrared heating, hot plate welding, ultrasonic welding, vibration welding, and high-frequency induction welding.

7. The manufacturing method of the bonded body according to claim 4, wherein in the second bonding step, the solid bonding agent is melted and then solidified under heating at a temperature of 100 to 400°C and under pressure of 0.01 to 20 MPa.

8. The manufacturing method of the bonded body according to any one of claims 1 to 7, wherein the solid bonding agent before melting has a film shape.

9. A bonded body formed by bonding a substrate A as a fiber-reinforced plastic substrate and a substrate B as a metal substrate through an adhesive layer. The adhesive layer is formed by disposing a solid bonding agent containing an amorphous thermoplastic resin between the substrate A and the substrate B, heating and pressurizing it to melt, and solidifying the solid bonding agent. The amorphous thermoplastic resin is at least one selected from a thermoplastic epoxy resin and a phenoxy resin, and has an epoxy equivalent of 1,600 or more and a heat of fusion of 15 J / g or less.

10. The bonded body according to claim 9, wherein the heating and pressurization are carried out under the conditions of 100 to 400°C and 0.01 to 20 MPa.

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