Method for manufacturing film-like bonding material

Abstract

Provided is a film-like bonding material which has a short bonding process time, a long opening time, and excellent bonding properties. A method for producing a film-like bonding material, the method comprising: a step in which a resin composition containing an amorphous thermoplastic resin and a solvent is applied to a support; and a step of removing the solvent from the resin composition after the coating to obtain a film-like bonding material laminated on the support, the amorphous thermoplastic resin being at least one of a thermoplastic epoxy resin and a phenoxy resin, having an epoxy equivalent of 1600 g / eq. Or not containing an epoxy group, and having a heat of fusion of 15 J / g or less.

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a film-like bonding material suitable for use in easily and firmly bonding different materials. Background Art

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

[0003] As a method for firmly bonding different materials, a thermosetting epoxy resin-based adhesive as a liquid-type adhesive is widely used (Patent Document 1, etc.).

[0004] Bonding using a liquid-type 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-type adhesive, in the coating step, the coating of the resin composition takes time, and in the curing step, the polymerization reaction takes time (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 material to the end when the bonded body is completed. For example, it includes the steps of coating a liquid adhesive on the base material, the drying step or the step of placing a film, and the time required to bond the base materials to each other (for example, curing the adhesive layer).

[0007] There is also disclosed a technique for manufacturing a bonded body by impregnating or coating an epoxy resin composition on a base material, semi-curing (B-staging) it, and forming a laminate with a B-stage adhesive layer.

[0008] However, bonding using a B-stage 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-stage adhesive is poor, and it cannot be stored at room temperature for a long time. It needs to be stored at a low temperature, and there are problems of a short open time and lack of convenience.

[0010] In this specification, the open time means the limited time from when the bonding material is applied or placed on the base material A until the placement of the base material B is completed. If within the open time, the adhesive force of the bonding material does not decrease, and the base materials A and B can be bonded together with sufficient adhesive force. The longer the open time, the longer the time from when the bonding material is applied or placed on the base material A until the placement of the base material B is completed, and the higher the convenience.

[0011] As a means for bonding different types of 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 bonds by utilizing a phase change that does not accompany a polymerization reaction, no coating process is required, the curing time is fast (that is, the bonding process time is short), and the convenience is excellent. Also, it can be stored at room temperature for a long time, and the convenience is excellent in terms of the long open time.

[0012] However, conventional hot melt adhesives are composed of a crystalline resin or a resin containing a crystalline resin in order to reduce the melt viscosity. Therefore, the cohesive force within the adhesive resin is high, and sufficient interaction with the base material cannot be achieved. In addition, during melt bonding, it becomes low viscosity at high temperatures and easily flows out from the bonding surface, and since it is difficult to control the viscosity, the film thickness is unstable. For these reasons, there is a problem that a high adhesive force cannot be stably obtained with conventional hot melt adhesives.

[0013] Prior Art Documents

[0014] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2019-157018

[0015] Patent Document 2: Japanese Unexamined Patent Application Publication No. 10-17685

[0016] Patent Document 3: Japanese Unexamined Patent Application Publication No. 10-168417 Summary of the Invention

[0017] As described above, in the prior art, among thermosetting epoxy resin-based adhesives with excellent adhesiveness, in either the liquid form or the B-stage form, there is at least one of the problems of a long bonding process time and a short open time, and there is a problem that a hot melt adhesive with a short bonding process time and a long open time cannot stably obtain a high adhesive force.

[0018] The present invention has been completed in view of this technical background, and its object is to provide a method for manufacturing a film-like bonding material suitable for easily and firmly bonding different types of materials, and to provide a bonding technique with a short bonding process time, a long open time, and excellent adhesiveness.

[0019] In order to achieve the foregoing object, the present invention provides the following means.

[0020] Further, in this specification, "bonding" means connecting an object to another object, and adhesion and welding are subordinate concepts thereof. "Adhesion" means forming a bonded state between two adherends (materials to be bonded) via 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 bonded state by contact pressure and cooling, utilizing entanglement and crystallization caused by molecular diffusion.

[0021] <Method for manufacturing film-like bonding material> [1]

[0023] A method for manufacturing a film-like bonding material, comprising:

[0024] a step of coating a resin composition containing an amorphous thermoplastic resin and a solvent on a support; and a step of removing the solvent from the resin composition after the coating to obtain a film-like bonding material laminated on the support,

[0025] The amorphous thermoplastic resin is at least one of a thermoplastic epoxy resin and a phenoxy resin, has an epoxy equivalent of 1600 g / eq. or more or does not contain an epoxy group, and the heat of fusion of the amorphous thermoplastic resin is 15 J / g or less. [2]

[0027] The method for manufacturing a film-like bonding material according to [1] includes a step of peeling the film-like bonding material from the support on which the film-like bonding material is laminated. [3]

[0029] The method for manufacturing a film-like bonding material according to [1] or [2], wherein the support is a strip-shaped release film. [4]

[0031] The method for manufacturing a film-like bonding material according to any one of [1] to [3], wherein the thickness of the film is 10 μm to 3 mm.

[0032] <Bonded body> [5]

[0034] A bonded body is a bonded body formed by bonding a base material A and a base material B via a film-like bonding material manufactured by the method for manufacturing a film-like bonding material according to any one of [1] to [4].

[0035] According to the present invention, it is possible to provide a film-like bonding material that realizes a short bonding process time, a long open time, and excellent adhesiveness. Description of the Drawings

[0036] Figure 1 It is a configuration diagram of a bonded body using a film-like bonding material according to an embodiment of the present invention. Detailed implementation mode

[0037] [Manufacturing method of film-like bonding material]

[0038] The manufacturing method of the film-like adhesive material of the present disclosure includes: a step of coating a resin composition containing an amorphous thermoplastic resin and a solvent on a support; and a step of removing the solvent from the resin composition after the coating to obtain a film-like adhesive material laminated on the support, wherein the amorphous thermoplastic resin is at least one of a thermoplastic epoxy resin and a phenoxy resin, the epoxy equivalent is 1600 g / eq. or more or does not contain an epoxy group, and the heat of fusion is 15 J / g or less.

[0039] It is preferable to perform a release treatment on the surface of the support.

[0040] (Film-like bonding material)

[0041] The film-like bonding material obtained by the manufacturing method of the present disclosure contains an amorphous thermoplastic resin, which is at least one selected from a thermoplastic epoxy resin and a phenoxy resin, the epoxy equivalent is 1600 g / eq. or more or does not contain an epoxy group, and the heat of fusion is 15 J / g or less.

[0042] In the present disclosure, an amorphous resin refers to a resin that has a melting point (Tm) in the measurement using a differential scanning calorimeter (DSC), but does not have or has a very small endothermic peak (melting point) associated with a distinct melting. The heat of fusion is calculated based on 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 film-like bonding material, it is calculated based on the weight of the resin component after removing the inorganic filler. Specifically, in the present disclosure, an amorphous thermoplastic resin refers to the following resin. Weigh 2 - 10 mg of the sample, put it in an aluminum pan, and heat it from 23 °C to 200 °C or more at 10 °C / minute using a DSC (DSC8231 manufactured by Rigaku Corporation) to obtain a DSC curve. Then, when calculating the heat of fusion based on the area of the endothermic peak at the time of melting obtained from this DSC curve and the weighing value, the resin with a heat of fusion of 15 J / g or less.

[0043] From the viewpoint of fully imparting the characteristics of the amorphous thermoplastic resin to the film-like bonding material, the content of the amorphous thermoplastic resin 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 among the resin components in the film-like bonding material. In the present disclosure, "the resin components in the film-like bonding material" refers to the components in the film-like bonding material other than the filler.

[0044] The heat of fusion is 15 J / g or less, preferably 11 J / g or less, more preferably 7 J / g or less, still more preferably 4 J / g or less, and most preferably the melting peak is below the detection limit.

[0045] The epoxy equivalent is 1600 or more, preferably 2000 or more, more preferably 5000 or more, still more preferably 9000 or more, and most preferably above the detection limit so that epoxy groups are substantially undetectable.

[0046] By using a film-like bonding material containing an amorphous thermoplastic resin with an epoxy equivalent of 1600 or more and a heat of fusion of 15 J / g or less, upon heating, there is no sharp drop in viscosity as in conventional hot melt adhesives, and even in a high temperature range exceeding 200°C, it does not reach a low viscosity state (0.001 - 100 Pa·s). Therefore, this film-like bonding material does not flow out of the laminate even in a molten state, can stably ensure the thickness of the adhesive layer, and can stably obtain a high adhesive force.

[0047] The epoxy equivalent (the weight of the 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 film-like bonding material before bonding, and is a value measured by the method specified in JIS-K 7236:2001 (unit "g / eq."). Specifically, using a potentiometric titration device, using cyclohexanone as a solvent, adding a tetraethylammonium bromide acetic acid solution, using a 0.1 mol / L perchloric acid - acetic acid solution, the value of the solvent dilution product (resin varnish) is a value calculated as a solid component conversion value based on the non-volatile component. Furthermore, in the case of a mixture of two or more resins, it can also be calculated based on their respective contents and epoxy equivalents.

[0048] The melting point of the amorphous thermoplastic resin contained in the film-like bonding material is preferably 50 - 400°C, more preferably 60°C - 350°C, still more preferably 70°C - 300°C. By having a melting point in the range of 50 - 400°C, the film-like bonding material is efficiently deformed and melted by heating, and effectively wets and spreads on the bonding surface, so a high adhesive force can be obtained.

[0049] 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 becoming capable of melting and bonding.

[0050] In conventional thermosetting adhesives, it is difficult to disassemble the joined body, and it is difficult to recycle different materials constituting the joined body separately (i.e., poor recyclability). Also, in the manufacturing process of the joined body, when there is an offset of the joining part, etc., and when the content or adherend is defective and needs to be replaced, it is difficult to re-paste (i.e., poor reparability), and there is a problem of lack of convenience. However, the film-like joining material can be softened and melted by heat and can be easily peeled off, so the recyclability is excellent. In addition, since the film-like joining material is thermoplastic, reversible softening, melting, and curing can be repeated, and the reparability is also excellent.

[0051] "Thermoplastic Epoxy Resin"

[0052] The thermoplastic epoxy resin is preferably a polymer of (a) a bifunctional epoxy resin monomer or oligomer and (b) a bifunctional compound having two identical or different functional groups selected from a phenolic hydroxyl group, a carboxyl group, a mercapto group, an isocyanate group, and a cyanate group. By using this compound, the polymerization reaction to form a linear polymer proceeds preferentially, and a thermoplastic epoxy resin having the desired properties can be obtained.

[0053] The resin composition coated on the support in the manufacturing method of the film-like joining material of the present disclosure may be a resin composition obtained by dissolving the thermoplastic epoxy resin obtained by carrying out the polymerization reaction without a solvent in a solvent, or a resin composition containing the thermoplastic epoxy resin obtained by carrying out the polymerization reaction in a solvent together with the solvent.

[0054] The (a) bifunctional epoxy resin monomer or oligomer means an epoxy resin monomer or oligomer having two epoxy groups in the molecule.

[0055] As a specific example of the above (a), examples thereof include bisphenol A type epoxy resin, bisphenol F type epoxy resin, 2-functional phenol novolac type epoxy resin, bisphenol AD type epoxy resin, biphenyl type epoxy resin, 2-functional naphthalene type epoxy resin, 2-functional alicyclic epoxy resin, 2-functional glycidyl ester type epoxy resin (such as diglycidyl phthalate, diglycidyl tetrahydrophthalate, diglycidyl dimer acid, etc.), 2-functional glycidyl amine type epoxy resin (such as diglycidyl aniline, diglycidyl toluidine, etc.), 2-functional heterocyclic epoxy resin, 2-functional 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.), 2-functional alkylene glycidyl ether compound (such as butanediol diglycidyl ether, butenediol diglycidyl ether, butynediol diglycidyl ether, etc.), 2-functional glycidyl-containing hydantoin compound (such as 1,3-diglycidyl-5,5-dialkyl hydantoin, 1-glycidyl-3-(epoxypropoxyalkyl)-5,5-dialkyl hydantoin, etc.), 2-functional glycidyl-containing siloxane (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.

[0056] As the 2-functional compound having a phenolic hydroxyl group of the above (b), examples thereof include mononuclear aromatic dihydroxy compound classes having 1 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), etc., compounds having a condensed ring such as dihydroxynaphthalene, 2-functional phenolic compounds into which allyl groups are introduced such as diallyl resorcinol, diallyl bisphenol A, triallyl dihydroxybiphenyl, etc., and dibutyl bisphenol A.

[0057] As specific examples of the carboxyl group-containing compound of the above (b), examples thereof include adipic acid, succinic acid, malonic acid, cyclohexanedicarboxylic acid, phthalic acid, isophthalic acid, and terephthalic acid.

[0058] As the 2-functional group compound having a mercapto group of the above (b), examples thereof include ethylene glycol dithioacetate, ethylene glycol dithiopropionate, etc.

[0059] Specific examples of the isocyanate group-containing bifunctional compound of the above (b) include diphenylmethane diisocyanate (MDI), isophorone diisocyanate (IPDI), hexamethylene diisocyanate (HMDI), toluene diisocyanate (TDI), and the like.

[0060] Specific examples of the cyanate group-containing bifunctional compound of the above (b) include 2,2-bis(4-cyanophenyl)propane, 1,1-bis(4-cyanophenyl)ethane, bis(4-cyanophenyl)methane, and the like.

[0061] 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, 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.

[0062] 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 and connected by an alkylene group, and a structure in which hydroxyl groups generated by addition polymerization are arranged in the side chain.

[0063] Through the linear structure composed of a p-phenylene skeleton, the mechanical strength of the polymer after polymerization can be improved. At the same time, through the hydroxyl groups arranged in the side chain, the adhesion to the substrate can be improved. 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, by softening and melting it with heat, recycling and repair can be carried out, and the recyclability and repairability, which are problems in thermosetting resins, can be improved.

[0064] "Phenoxy Resin"

[0065] Phenoxy resin is a polyhydroxy polyether synthesized from bisphenols and epichlorohydrin and has thermoplasticity. For the manufacture of phenoxy resin, methods based on the direct reaction of diphenols and epichlorohydrin and methods based on the addition polymerization of diglycidyl ethers of diphenols and diphenols are known. The phenoxy resin used in the present invention can also be obtained by any of these production methods. In the case of the direct reaction of diphenols and epichlorohydrin, as diphenols, for example, phenols such as bisphenol A, bisphenol F, bisphenol S, biphenol, bis(4-hydroxyphenyl)ether, phenyl furoate, etc.; aliphatic diols such as ethylene glycol, propylene glycol, diethylene glycol, etc. can be cited. Among them, from the viewpoints of cost, adhesiveness, viscosity, and heat resistance, bisphenol A, bisphenol F, and bisphenol S are preferred. They can be used alone or in combination of two or more.

[0066] The phenoxy resin has a chemical structure similar to that of the 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 the side chains.

[0067] "Physical Properties of Thermoplastic Epoxy Resin and Phenoxy Resin"

[0068] Regarding the above-mentioned thermoplastic epoxy resin and phenoxy resin, the polystyrene equivalent value, i.e., the weight-average molecular weight, measured by GPC (gel permeation chromatography) 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 based on the elution peak position detected by GPC, which is the molecular weight value under standard polystyrene conversion. If the weight-average molecular weight is within this value range, the balance between thermoplasticity and heat resistance is good, and a bonded body can be obtained by efficient 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 it is 500,000 or less, the viscosity during melting is low and the adhesiveness is high.

[0069] "Solvent"

[0070] The solvent used in the manufacturing method of the film-like bonding material of the present disclosure is not particularly limited as long as it is a solvent that dissolves the resin to form a resin composition. For example, ketone solvents such as methyl ethyl ketone, cyclohexanone, and methyl isobutyl ketone, ether solvents such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, and diethylene glycol dimethyl ether, amide solvents such as formamide, N-methylformamide, N,N-dimethylformamide, acetamide, N-methylacetamide, N,N-dimethylacetamide, N,N,N',N'-tetramethylurea, 2-pyrrolidone, N-methylpyrrolidone, and carbamate can be mentioned.

[0071] The concentration of the solvent contained in the resin composition coated on the support is preferably 10 to 95% by mass, more preferably 30 to 90% by mass, and particularly preferably 50 to 80% by mass.

[0072] The solvent contained in the resin composition can also serve as a solvent for polymerizing the epoxy resin.

[0073] "Components Other than the Resin Component in the Resin Composition"

[0074] As needed, within the scope not hindering the object of the present invention, as components other than the resin component, fillers and additives can also be contained.

[0075] As fillers, inorganic fillers and organic fillers (resin powders) can be mentioned.

[0076] As the inorganic filler, examples thereof include 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, and the like.

[0077] When the filler is contained, the content of the filler in 100% by volume of the total amount of the film-like bonding material 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.

[0078] The content (% by volume) of the filler is obtained based on the feeding amount at 25°C. Specifically, with respect to the mass% of the filler, based on the specific gravity of the components other than the filler and the true specific gravity of the filler, it is calculated by the following (Formula 1).

[0079] (Formula 1)

[0080] X = (MF / DF) ÷ (MF / DF + (100 - MF) / DR) × 100%

[0081] In (Formula 1),

[0082] X: Content (% by volume) of the filler

[0083] MF: Feeding amount (% by mass) of the filler

[0084] DR: Specific gravity when the resin component is cured

[0085] DF: True specific gravity of the filler.

[0086] The content of the resin component in 100% by volume of the total amount of the film-like bonding material is preferably 10% by volume or more, more preferably 20% by volume or more, still more preferably 30% by volume or more, further preferably 50% by volume or more, in one mode is 80% by volume or more, in another mode is 90% by volume or more, and in another mode is 99% by volume or more.

[0087] As the additive, examples thereof include defoamers, coupling agents such as silane coupling agents, pigments, etc., and one or more of them may also be contained.

[0088] The content of the additive in the film-like bonding material is preferably 10% by mass or less, more preferably 5% by mass or less, still more preferably 1% by mass or less.

[0089] The content of the resin component in the film-like bonding material is preferably 10% by mass or more, more preferably 20% by mass or more, still more preferably 30% by mass or more, further preferably 50% by mass or more, in one mode is 80% by mass or more, in another mode is 90% by mass or more, and in another mode is 99% by mass or more.

[0090] The manufacturing method of the resin composition used in the production of the film-like bonding material of the present disclosure is not particularly limited. For example, it can be obtained by heating and polymerizing a bifunctional epoxy compound monomer or oligomer. In order to reduce the viscosity during polymerization and facilitate stirring, a solvent can also be added. In the case of adding a solvent, it must be removed, and drying or polymerization or both can be carried out on a support that has been subjected to a release treatment to obtain a film.

[0091] (The step of coating the resin composition on a support and the step of removing the solvent to obtain a film-like bonding material)

[0092] The manufacturing method of the film-like bonding material of the present disclosure includes: a step of coating the resin composition on a support; and a step of removing the solvent from the resin composition coated on the support to obtain a film-like bonding material laminated on the support.

[0093] The surface of the support on which the resin composition is coated is preferably subjected to a release treatment.

[0094] The support subjected to the release treatment is preferably a strip-shaped release film.

[0095] As the release film, for example, a synthetic resin film such as a polyester-based film like polyethylene terephthalate, or a polyolefin-based film such as polyethylene and polypropylene can be used.

[0096] The method of the release treatment is not particularly limited, and examples include a peeling treatment based on a silicone resin, an alkyd resin, and a resin containing a long-chain alkyl group.

[0097] The thickness of the film-like bonding material obtained through the above steps is preferably 10 μm to 3 mm. If it is within this range of dimensions, it can be sandwiched between substrate A and substrate B, and effectively spread on the bonding surface by heating and pressing to obtain a high adhesive force.

[0098] The film-like bonding material can also have an initial tack within a range that does not hinder the adhesive force and its heat resistance. In this case, in the laminate preparation step, the film is temporarily fixed to the substrate.

[0099] The film-like bonding material can be a single layer or a laminate composed of multiple layers, but from the viewpoints of ease of manufacture and improvement of the bonding force, a single layer is preferred.

[0100] [Bonded body]

[0101] Figure 1The bonded body 1 shown is formed by melting and then solidifying the film-like bonding material of the present invention to bond and integrate the base material A (3) and the base material B (4). In one embodiment, the bonded body 1 can be prepared by sequentially arranging the base material A, the film-like bonding material, and the base material B to form a laminate, and heating and pressing the laminate to melt the film-like bonding material. In other embodiments, the bonded body 1 can also be obtained through a first bonding process and a second bonding process. In the first bonding process, the base material A and the film-like bonding material are bonded by melting and then solidifying the film-like bonding material in a state where the film-like bonding material is in surface contact with the base material A. In the second bonding process, the base material A and the base material B are bonded by melting and then solidifying the film-like bonding material in a state where the film-like bonding material bonded to the base material A is in surface contact with the base material B.

[0102] The bonded body obtained using the film-like bonding material of the present invention shows excellent bonding strength even when it is a bonded body of different materials. The bonding strength is affected by various factors such as the strength of the interfacial interaction acting between the bonding layer and the base material A and between the bonding layer and the base material B, as well as the thickness of the bonding layer, the molecular weight, chemical structure, mechanical properties, viscoelastic properties, etc. of the polymer constituting the film-like bonding material. The detailed mechanism of the excellent bonding strength shown by the bonded body of the present invention is not very clear yet, but it is speculated that the main reasons are: the low cohesion force in the amorphous thermoplastic resin constituting the bonding layer 2, and the presence of hydroxyl groups in the resin, forming chemical bonds such as hydrogen bonds and van der Waals forces at the interfaces between the bonding layer and the base material A and between the bonding layer and the base material 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. It is impossible or impractical in the current technology to specify it for the purpose of differentiating from the case where the film-like bonding material is not used.

[0103] The bonded body of the present invention in which the bonding layer is composed of a thermoplastic resin has excellent recyclability and reparability, and can be easily disassembled into the base material A and the base material B by heating the bonded body.

[0104] The materials and shapes of the base material A and the base material B are not particularly limited. The base material A and the base material B can be the same kind of base material or different kinds of base materials. Examples of the materials constituting each base material include glass, ceramics, magnetic materials, non-magnetic materials, fiber-reinforced plastics (FRP), metals, wood, paper, laminated glass, etc.

[0105] Examples of the glass include soda-lime glass, lead glass, borosilicate glass, quartz glass, etc.

[0106] As the ceramic, oxide ceramics such as alumina, zirconia, barium titanate, etc., hydroxide ceramics such as hydroxyapatite, carbide ceramics such as silicon carbide, nitride ceramics such as silicon nitride, etc. can be cited.

[0107] As the magnetic material, in addition to magnetic metal such as iron, etc., magnetic ceramics having a magnetic permeability larger than that of the following non-magnetic material can be cited.

[0108] As the non-magnetic material, in addition to aluminum, ceramics, etc., non-magnetic ferrite ceramics, insulating glass ceramics mainly composed of alumina and glass, etc. can be cited.

[0109] As the fiber reinforced plastic (FRP), 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, phenolic resin, etc. to improve the strength can be cited. A molded body formed of glass fiber, carbon fiber SMC (sheet molding compound), etc. can be cited.

[0110] As the metal, iron, aluminum, copper, magnesium, titanium, etc. can be cited. Among them, from the viewpoints of light weight and ease of processing, etc., aluminum and copper are particularly preferably used. Further, in the present invention, the term "aluminum" is used in the meaning of including aluminum and its alloys. Similarly, iron, copper, aluminum, magnesium, and titanium are also used in the meaning of including their simple substances and their alloys (such as stainless steel, duralumin, etc.).

[0111] As the wood, wood veneer, wood veneer sheet, wood plywood, particle board, MDF (medium density fiberboard) and other wood fiber boards can be cited.

[0112] As the paper, kraft paper, high-quality paper, coated paper, paper having barrier properties (barrier coated paper), etc. can be cited.

[0113] As the composite glass, composite glass obtained by disposing two opposed glasses with a space of at least 0.1 mm or more therebetween and pasting a window film containing an ultraviolet absorber on the inner surface of at least one glass can be cited.

[0114] Examples

[0115] 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, the base material A and the base material B are collectively referred to as the bonding base material.

[0116] <Bonding base material>

[0117] The following bonding base materials are used.

[0118] 《PA6 (Nylon 6)》

[0119] An injection molding was performed on Amilan CM3001G-30 manufactured by Toray Industries, Inc. 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. In order to effectively heat during ultrasonic welding, a linear protrusion with a height of 0.5 mm and a cross-section of an equilateral triangle was formed at a position 2.5 mm from the end.

[0120] 《PBT (Polybutylene Terephthalate)》

[0121] An injection molding was performed on 20-1001 manufactured by SABIC to obtain a test piece with a width of 18 m, a length of 45 mm, and a thickness of 1.5 mm. It was used without surface treatment.

[0122] 《PC (Polycarbonate)》

[0123] An injection molding was performed on 121R manufactured by SABIC 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.

[0124] 《Iron》

[0125] The surface of SPCC-SD was sandblasted to obtain a test piece with a width of 10 mm, a length of 45 mm, and a thickness of 2.3 mm.

[0126] 《Aluminum》

[0127] 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.

[0128] <Weight-average Molecular Weight, Heat of Fusion, and Epoxy Equivalent of Thermoplastic Epoxy Resin and Phenoxy Resin>

[0129] The weight-average molecular weight, heat of fusion, and epoxy equivalent of the film were determined as follows.

[0130] (Weight-average Molecular Weight)

[0131] 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 performed under the following conditions.

[0132] Column: LF-804 × 2 pieces manufactured by Showa Denko K.K.

[0133] Column temperature: 40 °C

[0134] Sample: 0.4 mass% tetrahydrofuran solution of the resin

[0135] Flow rate: 1 ml / min

[0136] Eluent: Tetrahydrofuran

[0137] Calibration method: Conversion based on standard polystyrene

[0138] (Heat of fusion)

[0139] Weigh 2 - 10 mg of thermoplastic epoxy resin and phenoxy resin, place them in an aluminum pan, and heat from 23°C to 200°C at 10°C / minute using a DSC (DSC8231 manufactured by Rigaku Corporation) to obtain a DSC curve. Calculate the heat of fusion based on the area of the endothermic peak during melting of this DSC curve and the weighed value.

[0140] (Epoxy equivalent)

[0141] Measure using JIS K - 7236:2001 and convert to the value as the resin solid content. Additionally, in the case of a simple mixture without accompanying reactions, calculate based on the respective epoxy equivalent and content.

[0142] <Example 1>

[0143] (Film P - 1)

[0144] Add 20 g of Enotate (registered trademark) YP - 50S (manufactured by Nippon Steel Chemical & Materials Co., Ltd., phenoxy resin, weight - average molecular weight of about 50000) and 80 g of cyclohexanone to a reaction apparatus equipped with a stirrer, reflux condenser, gas inlet tube, and thermometer. Heat to 60°C while stirring, visually confirm dissolution, cool to 40°C, and obtain a resin composition with a solid content of 20% by mass. After coating the resin composition on a poly(ethylene terephthalate) film (thickness 100 μm) that has undergone a release treatment, heat at 160°C for 2 hours to remove the solvent, and obtain a film (P - 1) with a solid content of 100% by mass and a thickness of 100 μm. The weight - average molecular weight is 50000, and the epoxy equivalent is above the detection limit. No heat of fusion peak was detected in the DSC.

[0145] (Bonded body)

[0146] Three types of bonded bodies were produced as follows.

[0147] In addition, for open - time evaluation, after placing the film on the aluminum substrate (substrate A) and allowing it to stand for 3 days, then placing the PC substrate (substrate B) thereon, a bonded body for open - time evaluation was produced in the same manner as the following 《Metal·Metal》 except for this.

[0148] 《Resin·Resin》

[0149] On the PBT substrate as substrate A, the film P-1 cut to a size of 10×15 mm is disposed, and then the PA6 substrate is quickly disposed thereon in such a manner that the triangular protrusions are placed, as substrate B. The overlap between these substrates is 10 mm in width and 5 mm in depth. The film P-1 is disposed so as to cover the entire overlapping area between the substrates. That is, there is no direct contact between substrate A and substrate B, and a state is formed in which the film is sandwiched therebetween, and an unbonded laminate is prepared. In this specification, "then quickly" means aiming for a degree within 30 minutes.

[0150] An ultrasonic welder (manufactured by Seiden Electric Industry Co., Ltd., oscillator JII930S, press JIIP30S) is used to apply ultrasonic waves, whereby the test pieces are joined to each other by heating and pressing. The sinking amount is 0.6 mm, and the ultrasonic application time is within 1 second. (Even if the time is shorter than 1 second at the moment when the sinking ends, it ends.) The subsequent holding time is 1 second. The pressing force is 110 N (pressure 2.2 MPa), and the oscillation frequency is 28.5 kHz.

[0151] 《Resin·Metal》

[0152] On the aluminum substrate as substrate A, the film P-1 cut to a size of 10×15 mm is disposed, and then the PC substrate is quickly disposed thereon as substrate B. The overlap between these substrates is 10 mm in width and 5 mm in depth. The film P-1 is disposed so as to cover the entire overlapping area between the substrates. That is, there is no direct contact between substrate A and substrate B, and a state is formed in which the film is sandwiched therebetween, and an unbonded laminate is prepared.

[0153] A high-frequency induction welder (manufactured by Seiden Electric Industry Co., Ltd., oscillator UH-2.5K, press JIIP30S) is used to heat the metal by high-frequency induction, and the test pieces are joined to each other by heating and pressing. The pressing force is 110 N (pressure 2.2 MPa), and the oscillation frequency is 900 kHz. The oscillation time is 6 seconds.

[0154] 《Metal·Metal》

[0155] On the aluminum substrate as substrate A, the film P-1 cut to a size of 10×15 mm is disposed, and then the iron substrate is quickly disposed thereon as substrate B. The overlap between these substrates is 10 mm in width and 5 mm in depth. The film P-1 is disposed so as to cover the entire overlapping area between the substrates. That is, there is no direct contact between substrate A and substrate B, and a state is formed in which the film is sandwiched therebetween, and an unbonded laminate is prepared.

[0156] Using a high-frequency induction welding machine (manufactured by Seidensha Electronics Industry Co., Ltd., oscillator UH-2.5K, press JIIP30S), heat the metal by high-frequency induction, and join the test pieces together by heating and pressing. The pressing force is 110 N (pressure 2.2 MPa), the oscillation frequency is 900 kHz, and the oscillation time is 5 seconds.

[0157] <Example 2>

[0158] (Film P-2)

[0159] Sprinkle the powder of crystalline epoxy resin YSLV-80XY (manufactured by Nippon Steel Chemical & Materials Co., Ltd.) on the film P-1 at a mass ratio of 98:2 and press it to obtain film (P-2). The weight-average molecular weight is 36000, the epoxy equivalent is 9600 g / eq, and the heat of fusion is 2 J / g.

[0160] (Bonded body)

[0161] Except for using P-2 as the film, three types of bonded bodies and a bonded body for open time evaluation were produced in the same manner as in Example 1.

[0162] <Example 3>

[0163] (Film P-3)

[0164] Sprinkle the powder of crystalline epoxy resin YSLV-80XY (manufactured by Nippon Steel Chemical & Materials Co., Ltd.) on the film P-1 at a mass ratio of 94:6 and press it to obtain film (P-3). The weight-average molecular weight is 35000, the epoxy equivalent is 2100 g / eq, and the heat of fusion is 4 J / g.

[0165] (Bonded body)

[0166] Except for using P-3 as the film, three types of bonded bodies and a bonded body for open time evaluation were produced in the same manner as in Example 1.

[0167] <Example 4>

[0168] (Film P-4)

[0169] Sprinkle the powder of crystalline epoxy resin YSLV-80XY (manufactured by Nippon Steel Chemical & Materials Co., Ltd.) on the film P-1 at a mass ratio of 89:11 and press it to obtain film (P-4). The weight-average molecular weight is 33000, the epoxy equivalent is 1745 g / eq, and the heat of fusion is 11 J / g.

[0170] (Bonded body)

[0171] Except for using P-4 as the film, three types of bonded bodies and a bonded body for open time evaluation were produced in the same manner as in Example 1.

[0172] <Comparative Example 1>

[0173] (Film Q-1)

[0174] The two components of the thermosetting liquid epoxy adhesive E-250 (manufactured by Konishi Co., Ltd., two-component type of bisphenol-type epoxy resin and amine curing agent) were mixed and coated on a release film. After curing at 100 °C for 1 hour and then cooling, it was peeled off from the release film to obtain a film (Q-1) with a thickness of 100 μm. No melting heat peak was detected in DSC. The epoxy equivalent and the weight average molecular weight could not be measured because it was insoluble in solvents.

[0175] (Bonded body)

[0176] Except for using Q-1 as the film, three types of bonded bodies and a bonded body for open time evaluation were produced in the same manner as in Example 1.

[0177] <Comparative Example 2>

[0178] (Film Q-2)

[0179] An amorphous polycarbonate film (Iupilon (registered trademark) FE2000, manufactured by Mitsubishi Engineering-Plastics Corporation, thickness 100 μm) was used as the solid bonded body Q-2. No melting heat peak was detected in DSC.

[0180] (Bonded body)

[0181] Except for using Q-2 as the film, three types of bonded bodies and a bonded body for open time evaluation were produced in the same manner as in Example 1.

[0182] <Comparative Example 3>

[0183] (Film Q-3)

[0184] Crystalline epoxy resin YSLV-80XY (manufactured by Nippon Steel Chemical & Material Co., Ltd.) was used as the film (Q-3). The epoxy equivalent was 192 g / eq. The weight average molecular weight was 340. The heat of fusion was 70 J / g.

[0185] (Bonded body)

[0186] Except for using Q-3 as the film, three types of bonded bodies and a bonded body for open time evaluation were produced in the same manner as in Example 1.

[0187] <Comparative Example 4>

[0188] (Bonded body)

[0189] The two components of the thermosetting liquid epoxy adhesive E-250 (manufactured by Konishi Co., Ltd., a two-component type of bisphenol epoxy resin and amine curing agent) were mixed, coated on three types of each of the same substrates A and B as in Example 1 above, and bonded within 1 minute. Thereafter, with the state fixed by clips, it was left standing in an oven at 100 °C for 1 hour to cure the bonding components. Thereafter, it was cooled to room temperature, and thus three types of bonded bodies were produced.

[0190] In addition, the thermosetting liquid epoxy adhesive E-250 was coated on substrates A and B and left standing for 3 days before bonding. Except for this, bonded bodies for open time evaluation were produced in the same manner as above.

[0191] <Comparative Example 5>

[0192] 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 1000 g of methyl ethyl ketone were added to a flask and stirred at room temperature, whereby a liquid resin composition having a solid content of about 20% by mass was obtained. The liquid resin composition was blade-coated on three types of each of the same substrates B as in Example 1 above. After drying at room temperature for 30 minutes, it was left standing in an oven at 160 °C for 2 hours, whereby a solid thermoplastic epoxy resin polymer coating with a thickness of 100 μm was formed on the surface of substrate B. The weight average molecular weight of the coating was about 40,000. The epoxy equivalent was above the detection limit. No melting heat peak was detected in DSC.

[0193] (Bonded body)

[0194] Except for directly disposing substrate A on the substrate B having the coating, three types of bonded bodies were produced in the same manner as in Example 1.

[0195] In addition, for open time evaluation, after forming a thermoplastic epoxy resin polymer coating on the surface of substrate B and leaving it standing for 3 days, it was then laminated with substrate A. Except for this, bonded bodies for open time evaluation were produced in the same manner as above.

[0196] <Comparative Example 6>

[0197] Into a reaction apparatus equipped with a stirrer, a reflux cooler, a gas inlet tube, and a thermometer, 20 g of Phenotole (registered trademark) YP-50S (manufactured by Nippon Steel Chemical & Materials Co., Ltd., a phenoxy resin, weight average molecular weight of about 50,000) and 80 g of cyclohexanone were added. While stirring, the temperature was raised to 60 °C, and dissolution was visually confirmed. After cooling to 40 °C, a liquid resin composition with a solid content of 20 mass% was obtained. On each of the three types of substrate B that were the same as in Example 1, the liquid resin composition was applied by bar coating, and it was left standing in an oven at 70 °C for 30 minutes. Thus, a phenoxy resin coating with a thickness of 100 μm was formed on the surface of substrate B. The weight average molecular weight of the coating was about 50,000. The epoxy equivalent was above the detection limit. No melting heat peak was detected in DSC.

[0198] (Bonded body)

[0199] Except for directly disposing substrate A on the substrate B having the phenoxy resin coating, three types of bonded bodies were produced in the same manner as in Example 1.

[0200] In addition, for the evaluation of open time, after forming a phenoxy resin coating on the surface of substrate B and leaving it standing for 3 days, it was then laminated with substrate A. Except for this, the bonded bodies for open time evaluation were produced in the same manner as above.

[0201] [Comparative Example 7]

[0202] (Bonded body)

[0203] Except for using a crystalline polyamide-based hot melt adhesive film NT-120 (manufactured by Nippon Mat Tai Co., Ltd., thickness 100 μm) as the film, three types of bonded bodies and bonded bodies for open time evaluation were produced in the same manner as in Example 1. The heat of fusion was 60 J / g.

[0204] [Shear bond strength]

[0205] The bonded bodies obtained in Examples 1 to 6 and Comparative Examples 1 to 7 were left standing at the measurement temperature (23 °C or 80 °C) for 30 minutes or more, and then, 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); test load 10 kN, tensile speed 10 mm / minute) to measure the bond strength.

[0206] The measurement results are shown in Table 1.

[0207] [Bonding process time]

[0208] The bonding process time was measured as follows.

[0209] Starting from the moment when at least one base material constituting the bonded body comes into contact with the bonding agent and ending when the bonded body is completed, the time from the start point to the end point was measured. Regarding the heating and bonding time, the respective heating and bonding times of the two types of bonded bodies were averaged. The measurement results are shown in Tables 1-1 and 1-2.

[0210] [Recyclability]

[0211] After heating the bonded body in an oven at 200 °C for 10 minutes, it was judged whether it could be easily detached with a force of 1 N or less. If it could be detached, it was rated as good (A); if it could not be detached, it was rated as inappropriate (B).

[0212] [Repairability]

[0213] After the tensile strength test at 23 °C, the test piece of iron (substrate A or B or the layer of bonding solid remaining on the surface of both) with the bonded surface fractured was heated to 350 °C, and by inserting substrate A, a bonded body was fabricated in the same manner as in Example 1, thereby obtaining a repaired bonded body. In the same manner as the test method, the tensile adhesion of the repaired bonded body at 23 °C was measured. If it was 80% or more of the shear adhesion of the first time, it was rated as good (A); if it was less than 80%, it was rated as inappropriate (B). The evaluation results are shown in Tables 1-1 and 1-2.

[0214] [Open time evaluation]

[0215] Using the bonded body for open time evaluation, the tensile shear bond strength test was carried out at 23 °C. Compared with the test pieces made by the methods of the above-mentioned examples and comparative examples, if the shear adhesion was 80% or more, it was rated as good (A); if it was less than 80%, it was rated as inappropriate (B). A good (A) open time evaluation means a long open time and excellent convenience. The evaluation results are shown in Tables 1-1 and 1-2.

[0216] [Table 1-1]

[0217]

[0218] [Table 1-2]

[0219]

[0220] Industrial applicability

[0221] The film-like bonding material obtained by the manufacturing method of the present invention can be used for manufacturing automotive components such as door side panels, hood tops, tailgates, steering hangers, A-pillars, B-pillars, C-pillars, D-pillars, crash boxes, power control unit (PCU) housings, electric compressor components (inner wall parts, suction port parts, exhaust control valve (ECV) insertion parts, mounting boss parts, etc.), lithium-ion battery (LIB) spacers, battery housings, LED headlamps, etc., as well as for manufacturing structures of smartphones, laptop computers, tablet computers, smartwatches, large liquid crystal displays (LCD-TVs), and outdoor LED lighting, but is not particularly limited to these exemplified uses.

[0222] Explanation of Reference Numerals

[0223] 1 Bonded body

[0224] 2 Adhesive layer

[0225] 3 Base material A

[0226] 4 Base material B

Claims

1. A method for manufacturing a film-like bonding material, comprising: a step of applying a resin composition containing an amorphous thermoplastic resin and a solvent onto a support; and a step of removing the solvent from the resin composition after the application to obtain a film-like bonding material laminated on the support, wherein the amorphous thermoplastic resin is at least one of a thermoplastic epoxy resin and a phenoxy resin, has an epoxy equivalent of 1600 g / eq. or more or does not contain an epoxy group, and the heat of fusion of the amorphous thermoplastic resin is 15 J / g or less.

2. The method for manufacturing a film-like bonding material according to the claim, comprising a step of peeling the film-like bonding material from the support on which the film-like bonding material is laminated.

3. The method for manufacturing a film-like bonding material according to claim 1, wherein the support is a strip-shaped release film.

4. The method for manufacturing a film-like bonding material according to claim 1, wherein the thickness of the film-like bonding material is 10 μm to 3 mm.

5. An assembly, which is an assembly in which a substrate A and a substrate B are bonded via a film-like bonding material manufactured by the method for manufacturing a film-like bonding material according to any one of claims 1 to 4.

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