Next method

Abstract

This invention provides a bonding method in which an adhesive layer (1) and a hardener layer (3) are disposed between a first substrate (2) and a second substrate (4) to bond the first substrate (2) and the second substrate (4). The adhesive layer (1) contains epoxy resin as its main component and is hardened by the action of the hardener layer. The hardener contained in the hardener layer (3) is a polymer catalyst type hardener. The thickness A (m) of the adhesive layer (1) before hardening and the coating amount B (kg / m²) of the hardener contained in the hardener layer (3) are also specified. 2) Satisfies 5 < B / A < 900.

Description

Technical Field

[0001] This invention relates to a bonding method, and more particularly to a bonding method in which an adhesive layer and a hardener layer are disposed between a first substrate and a second substrate, thereby bonding the first substrate and the second substrate together. Prior Technology

[0002] Previously, as a bonding method, there is a known method of using a two-component adhesive that combines two liquids, namely a base agent (liquid A) and a hardener (liquid B) (see, for example, Patent Document 1 below).

[0003] The bonding method disclosed in Patent Document 1 involves separately measuring the main agent and the hardener before use, mixing them to prepare a mixture, applying the mixture to a resin plate to form a film, and then bonding one resin plate to another via the film.

[0004] Subsequently, in the coating, the base agent and the hardener react, and the base agent hardens, thereby firmly bonding the two resin plates together.

[0005] Furthermore, Patent Document 2 discloses a bonding method characterized by comprising the following steps: step (1), disposing an adhesive layer on a first substrate; step (2), disposing a hardener layer on a second substrate, wherein the hardener layer can harden the adhesive layer by reacting upon contact with the adhesive layer; and step (3), bringing the adhesive layer and the hardener layer into contact in such a manner that they are sandwiched between the first substrate and the second substrate. Previous technical documents Patent documents

[0006] Patent Document 1: Japanese Patent Application Publication No. 2000-336333 Patent Document 2: Japanese Patent Application Publication No. 2017-88723 Summary of the Invention

[0007] [The problem the invention aims to solve]

[0008] However, the bonding method using a two-component adhesive described in Patent Document 1 requires the main agent and hardener to be measured and mixed separately just before use. Therefore, this method is cumbersome.

[0009] Furthermore, the bonding method described in Patent Document 2 has the problem of causing hardening differences, which compromises the reliability of the physical properties of the resulting bonded structure. The bonded structure obtained by the bonding method described in Patent Document 2 can be used, for example, as a fixing component for a stress-detecting sensor; however, if the physical properties of the bonded structure change, it will also adversely affect the sensor's function.

[0010] Therefore, the object of the present invention is to provide a bonding method that enables a first adhesive to be bonded to a second adhesive easily and firmly, and can suppress the hardening difference of the adhesive layer after hardening, and suppress undesirable changes in physical properties. [Technical means to solve the problem]

[0011] The present invention is described below. 1. A bonding method, characterized in that: An adhesive layer and a hardener layer are disposed between the first substrate and the second substrate, so that the first substrate and the second substrate are bonded together; The aforementioned adhesive layer contains epoxy resin as its main component and is cured by the action of the aforementioned hardener layer. The hardener contained in the above-mentioned hardener layer is a polymer catalyst type hardener. The thickness A (m) of the adhesive layer before curing and the amount of curing agent B (kg / m2) contained in the curing agent layer satisfy the following formula (1). 5 2. The bonding method as described in 1 above, characterized in that the polymer catalyst type curing agent is an imidazole compound. 3. The bonding method as described in 1 or 2 above, characterized in that the elastic modulus (Pa) of the adhesive layer after curing is more than 10 times that of the adhesive layer before curing. 4. The bonding method described in any one of 1 to 3 above is characterized in that the elastic modulus (Pa) of the adhesive layer after curing is 5 × 10⁷ (Pa) or higher after 48 hours at room temperature (25°C). 5. The bonding method as described in any one of 1 to 4 above, characterized in that the ratio of solid resin in the adhesive layer before curing is 15% by mass or more and 80% by mass or less. 6. The bonding method as described in any one of 1 to 5 above, characterized in that the thickness of the adhesive layer before curing is more than 3 μm and less than 100 μm. ​7. The bonding method as described in any one of 1 to 6 above, characterized in that the adhesive layer comprises a porous sheet impregnated with an adhesive composition comprising an epoxy resin as a main component. [Effects of the Invention]

[0012] According to one embodiment of the present invention, a bonding method is provided that enables a first adhesive to be bonded to a second adhesive easily and firmly, and can suppress hardening differences in the hardened adhesive layer, thereby suppressing undesirable changes in physical properties. Simple Explanation of the Diagram

[0013] Figures 1(A) and 1(B) are step diagrams illustrating one embodiment of the bonding method of the present invention. Figure 1(A) shows step (1) of disposing an adhesive layer on a first substrate and step (2) of disposing a hardener layer on a second substrate. Figure 1(B) shows step (3) of disposing the adhesive layer and the hardener layer in such a way that they are equally sandwiched between the first substrate and the second substrate. Figure 2 is a cross-sectional view of an adhesive layer having a first adhesive layer and a second adhesive layer disposed on a first substrate layer. Figure 3 is a diagram illustrating the morphology of a second substrate layer disposed between the adhesive layer and the hardener layer before curing. Implementation

[0014] The embodiments of the present invention will be described below. The characteristic of the following method in this embodiment is: An adhesive layer and a hardener layer are disposed between the first substrate and the second substrate, so that the first substrate and the second substrate are bonded together. The aforementioned adhesive layer contains epoxy resin as its main component and is cured by the action of the aforementioned hardener layer. The hardener contained in the above-mentioned hardener layer is a polymer catalyst type hardener. The thickness A (m) of the adhesive layer before curing and the amount of curing agent B (kg / m2) contained in the curing agent layer satisfy the following formula (1). 5

[0015] ​As a method for setting the adhesive layer and the hardener layer, examples include: (i) a method in which the adhesive layer is disposed on a first substrate, a hardener layer that can be hardened by reacting with the adhesive layer is disposed on a second substrate, and the adhesive layer and the hardener layer are disposed such that they are sandwiched between the first substrate and the second substrate; and (ii) a method in which the adhesive layer is disposed on a first substrate, a hardener layer that can be hardened by reacting with the adhesive layer is disposed on the adhesive layer, and then a second substrate is disposed thereon.

[0016] First, the implementation method of the following method in this embodiment will be described when the method (i) above is used.

[0017] When using the method described in (i) above, the bonding method of this embodiment includes: step (1) of disposing the adhesive layer 1 on the first substrate 2 (see Figure 1(A)); step (2) of disposing the hardener layer 3, which can harden the adhesive layer 1 by reacting with the adhesive layer 1, on the second substrate 4 (see Figure 1(A)); and step (3) of disposing the adhesive layer 1 and the hardener layer 3 in such a way that they are sandwiched between the first substrate 2 and the second substrate 4 (see Figure 1(B)). The following explains each step.

[0018] (i) Step (1) In step (1), as shown in FIG1(A), adhesive layer 1 is disposed on the first bonded body 2.

[0019] The adhesive layer 1 is a layer (sheet) that is cured by reacting with the hardener layer 3. It has a generally flat shape that extends along the surface direction (orthogonal to the thickness direction) and includes a flat front and a flat back.

[0020] Since the adhesive layer 1 is adhesive in its uncured state, it can be attached to the substrate as a sheet, and it can also exhibit adhesion after curing.

[0021] To place the adhesive layer 1 onto the first bonded body 2, for example, the adhesive layer 1 is first formed on the surface of the release liner 10.

[0022] In order to form an adhesive layer 1 on the surface of the release liner 10, an adhesive composition is first prepared.

[0023] There are no particular restrictions on the adhesive composition as long as it contains epoxy resin as the main component and is the main agent of a two-component adhesive that can form a layer.

[0024] Other possible components besides epoxy resin include, for example, silicone compounds, polyols such as polypropylene glycol, polyurethane resins, and epoxy resins.

[0025] Because the adhesive composition contains epoxy resin as the main component, the first adhesive 2 and the second adhesive 4 can be easily and firmly bonded together. Here, "main component" means the component that is present in the composition or layer by weight.

[0026] Examples of epoxy resins include: bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, hydrogenated bisphenol A type epoxy resin and other bisphenol-based epoxy resins, naphthalene type epoxy resin, biphenyl type epoxy resin, bicyclic epoxy resin, alicyclic epoxy resin, triglycidyl isocyanate epoxy resin, hydantoin epoxy resin, glycidyl ether type epoxy resin and glycidyl amino type epoxy resin, etc.

[0027] Furthermore, multifunctional epoxy resins with three or more functions can also be used as epoxy resins. Examples of such multifunctional epoxy resins include glycidyl ether-based epoxy resins and glycidyl amino-based epoxy resins.

[0028] Examples of glycidyl ether-based epoxy resins include: phenolic varnish type, o-cresol phenolic varnish type epoxy resin, DPP phenolic varnish type epoxy resin, trihydroxyphenylmethane type epoxy resin, tetraphenolic ethane type epoxy resin, etc.

[0029] Examples of glycidylamine-based epoxy resins include: for example, diaminodiphenylmethane type epoxy resins such as tetraglycidyldiaminodiphenylmethane; for example, diaminodiphenylmethane type epoxy resins such as tetraglycidyldiaminodiphenylmethane; for example, tetraglycidylm-phenylenediamine, tetraglycidyl1,3-diaminomethylcyclohexane, triglycidyl isocyanurate, hydantoin type epoxy resin, and aminophenol type epoxy resin.

[0030] As an epoxy resin, bisphenol-based epoxy resins are preferred, and bisphenol A type epoxy resins are even more preferred.

[0031] Epoxy resins can be used alone or in combination with two or more types.

[0032] Furthermore, when using multifunctional epoxy resins, the percentage of the total epoxy resin content is preferably 0.1 to 50% by mass, and more preferably 0.5 to 40% by mass.

[0033] Epoxy resins can be in any of the following forms at room temperature: liquid, semi-solid, and solid. Examples of preferred applications include the use of semi-solid epoxy resins alone and the combined use of liquid and solid epoxy resins. This allows for a more reliable formation of a viscous, layered adhesive layer 1 from the adhesive composition.

[0034] The epoxy resin that is liquid at room temperature is specifically liquid at 25°C. The viscosity of the liquid epoxy resin at 25°C is, for example, 0.01 Pa‧s or higher, preferably 1 Pa‧s or higher.

[0035] Furthermore, the viscosity of the liquid epoxy resin at 25°C is, for example, 50 Pa‧s or less, preferably 30 Pa‧s or less.

[0036] Epoxy resin that is solid at room temperature is specifically solid at 25°C. The softening point of solid epoxy resin is, for example, above 70°C, preferably above 75°C.

[0037] In this embodiment, from the viewpoint that the adhesive layer 1 can be easily sheeted, the ratio of solid resin (solid resin at room temperature (25°C)) in the adhesive layer 1 before curing is preferably 15% by mass or more and 80% by mass or less, and more preferably 20% by mass or more and 50% by mass or less.

[0038] The mixing ratio (mass ratio) of liquid epoxy resin to solid epoxy resin (liquid epoxy resin / solid epoxy resin) is, for example, 1.0 or more, preferably 1.5 or more.

[0039] Furthermore, the mixing ratio (mass ratio) of liquid epoxy resin to solid epoxy resin (liquid epoxy resin / solid epoxy resin) is, for example, 6.0 or less, preferably 3.0 or less.

[0040] If the mixing ratio of liquid epoxy resin to solid epoxy resin is above the lower limit mentioned above, the viscosity of the adhesive composition can be reduced, preventing uneven coating and resulting in a uniform adhesive layer 1. If the mixing ratio of liquid epoxy resin to solid epoxy resin is below the upper limit mentioned above, a viscous, layered adhesive layer can be obtained.

[0041] The formulation ratio of epoxy resin in the adhesive composition is set to a ratio in which epoxy resin is the main component. Specifically, relative to the adhesive composition, the epoxy resin is, for example, 80% by mass or more, preferably 90% by mass or more, and, for example, 100% by mass or less.

[0042] The adhesive composition is preferably composed of only epoxy resin, that is, the epoxy resin is mixed in a ratio of 100 by mass relative to the adhesive composition.

[0043] The adhesive composition can also be formulated with acrylic polymers, urethane polymers, polyester polymers, and rubber polymers as needed. This can improve the cohesiveness of the adhesive composition and reduce its fragility. The following mainly describes acrylic polymers.

[0044] Acrylic polymers are obtained by reacting monomeric components containing (meth)acrylates.

[0045] (Meth)acrylates refer to alkyl methacrylates and / or alkyl acrylates. Specifically, examples include methyl methacrylate, ethyl methacrylate, propyl methacrylate, isopropyl methacrylate, butyl methacrylate, isobutyl methacrylate, dibutyl methacrylate, terbutyl methacrylate, n-butyl methacrylate, amyl methacrylate, isoamyl methacrylate, hexyl methacrylate, heptyl methacrylate, octyl methacrylate, 2-ethylhexyl methacrylate, isooctyl methacrylate, and propyl methacrylate. Nonyl acrylate, isononyl acrylate, decyl acrylate, isodecyl acrylate, undecyl acrylate, dodecyl acrylate, tridecyl acrylate, tetradecyl acrylate, pentadecyl acrylate, hexadecyl acrylate, heptadecanyl acrylate, octadecyl acrylate, nonadecanyl acrylate, eicosyl acrylate, etc., alkyl esters of methacrylate with 1 to 20 carbon atoms.

[0046] As (meth)acrylates, alkyl esters of (meth)acrylate having 2 to 14 carbon atoms are preferred examples, and alkyl esters of (meth)acrylate having 4 to 9 carbon atoms are even more preferred examples. (Meth)acrylates can be used alone or in combination of two or more types.

[0047] The blending ratio of (meth)acrylate relative to the monomer component is, for example, 70% by mass or more, preferably 80% by mass or more.

[0048] Furthermore, the blending ratio of (meth)acrylate relative to the monomer content is, for example, 99% by mass or less, preferably 98% by mass or less.

[0049] The monomer components may further contain comonomers that can be copolymerized with (meth)acrylates.

[0050] Examples of comonomers include: (meth)acrylic acid, itaconic acid, maleic acid, butenoic acid, maleic anhydride, and other carboxyl-containing monomers or their anhydrides; (meth)acrylic acid 2-hydroxyethyl ester, (meth)acrylic acid 3-hydroxypropyl ester, and other hydroxy(meth)acrylic acid esters; (meth)acrylamide, N,N-dimethyl(meth)acrylamide, N-hydroxymethyl(meth)acrylamide, N-methoxymethyl(meth)acrylamide, N-butoxymethyl(meth)acrylamide, and other acetylamine-containing monomers; vinyl acetate and other vinyl esters; styrene, vinyltoluene and other aromatic vinyl compounds; (meth)acrylonitrile; N-(meth)acrylamide porphyrin, for example, N-vinyl-2-pyrrolidone, etc.

[0051] Examples of comonomers include carboxyl-containing monomers and hydroxyl-containing (meth)acrylates, and more preferably (meth)acrylates and 2-hydroxyethyl (meth)acrylates.

[0052] These comonomers can be used alone or in combination of two or more. Preferably, a combination of carboxyl-containing monomers and hydroxyl-containing (meth)acrylates is used; even more preferably, a combination of (meth)acrylic acid and 2-hydroxyethyl (meth)acrylate is used.

[0053] The ratio of the comonomer to 100 parts by weight of (meth)acrylate is, for example, 0.1 parts by weight or more, preferably 0.3 parts by weight or more.

[0054] Furthermore, the ratio of the comonomer to 100 parts by weight of (meth)acrylate is, for example, 15 parts by weight or less, preferably 10 parts by weight or less.

[0055] Monomer components are prepared by reacting monomer components, for example by blending (meth)acrylates with desired comonomers, and then polymerizing them using known polymerization methods such as solution polymerization, bulk polymerization, emulsion polymerization, and various free radical polymerizations.

[0056] Solution polymerization is a preferred example of a polymerization method.

[0057] In solution polymerization, for example, a monomer solution is prepared by mixing monomer components and a polymerization initiator in a solvent, and then the monomer solution is heated.

[0058] Examples of solvents include organic solvents. Examples of organic solvents include aromatic solvents such as toluene, benzene, and xylene; ether solvents such as ethyl acetate; ketone solvents such as acetone and methyl ethyl ketone; ester solvents such as ethyl acetate; and amine solvents such as N,N-dimethylformamide.

[0059] Solvents can be used alone or in combination of two or more. It is preferable to use aromatic solvents and ether solvents together.

[0060] The solvent mixing ratio is, for example, 10 parts by mass or more, preferably 50 parts by mass or more, relative to 100 parts by mass of the monomer component.

[0061] Furthermore, the solvent mixing ratio is less than 1000 parts by mass relative to the monomer component, for example, less than 1000 parts by mass, preferably less than 500 parts by mass.

[0062] Examples of polymerization initiators include peroxide-based polymerization initiators and azo-based polymerization initiators.

[0063] Examples of peroxide-based polymerization initiators include: peroxide carbonates, peroxide ketones, peroxide ketals, hydrogen peroxide, dialkyl peroxide, diacetyl peroxide, peroxide esters, and other organic peroxides.

[0064] Examples of azo polymerization initiators include: 2,2'-azobisisobutyronitrile, 2,2'-azobis(2-methylbutyronitrile), 2,2'-azobis(2,4-dimethylpentanonitrile), dimethyl 2,2'-azobisisobutyrate, and other azo compounds.

[0065] Azo polymer initiators are preferred examples of polymerization initiators.

[0066] The polymerization initiator is formulated at a ratio of 0.01 parts by mass or more, preferably 0.05 parts by mass or more, relative to 100 parts by mass of the monomer component.

[0067] Furthermore, the mixing ratio of the polymerization initiator relative to 100 parts by mass of the monomer component is, for example, 5 parts by mass or less, preferably 3 parts by mass or less.

[0068] The heating temperature is, for example, above 50°C and below 80°C.

[0069] Heating time is, for example, more than 1 hour and less than 24 hours.

[0070] This allows the monomer components to polymerize, resulting in an acrylic polymer solution containing acrylic polymers.

[0071] The acrylic polymer solution is formulated into the epoxy resin in a ratio of acrylic polymer to adhesive composition of, for example, 20 parts by mass or more, preferably 30 parts by mass or more, relative to 100 parts by mass.

[0072] Furthermore, the acrylic polymer solution is formulated into the epoxy resin in such a ratio that the acrylic polymer is 90 parts by weight or less, preferably 80 parts by weight or less, relative to 100 parts by weight of the adhesive composition.

[0073] Furthermore, the mixing ratio of the acrylic polymer relative to 100 parts by weight of epoxy resin is, for example, 50 parts by weight or more, preferably 150 parts by weight or more, and even more preferably 200 parts by weight or more.

[0074] Furthermore, the mixing ratio of the acrylic polymer relative to 100 parts by weight of epoxy resin is, for example, 300 parts by weight or less, preferably 250 parts by weight or less.

[0075] If the mixing ratio of acrylic polymers is above the lower limit mentioned above, the cohesiveness of the adhesive composition can be improved, thereby improving the adhesion and thus improving the peel adhesion of adhesive layer 1.

[0076] If the blending ratio of acrylic polymers is below the above-mentioned upper limit, it can be hardened.

[0077] Furthermore, examples of urethane polymers include polycarbonate-based polyurethanes, polyester-based polyurethanes, and polyether-based polyurethanes.

[0078] Furthermore, polyester polymers are typically polymers with a structure formed by the condensation of dicarboxylic acids or their derivatives (hereinafter also referred to as "polycarboxylic acid monomers") and diols or their derivatives (hereinafter referred to as "polyol monomers").

[0079] There are no particular limitations on the monomers used as polycarboxylic acids. For example, adipic acid, azelaic acid, dimer acid, sebacic acid, 1,4-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, 4-methyl-1,2-cyclohexanedicarboxylic acid, dodecenylsuccinic anhydride, fumaric acid, succinic acid, dodecanoic acid, hexahydrophthalic anhydride, tetrahydrophthalic anhydride, maleic acid, maleic anhydride, itaconic acid, citraconic acid, and their derivatives can be used. Polycarboxylic acid monomers can be used alone or in combination of two or more.

[0080] There are no particular limitations on the monomers used as polyols. For example, ethylene glycol, 1,2-propanediol, 1,3-propanediol, 2-methyl-1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, neopentanediol, diethylene glycol, dipropylene glycol, 2,2,4-trimethyl-1,5-pentanediol, 2-ethyl-2-butylpropanediol, 1,9-nonanediol, 2-methyloctanediol, 1,10-decanediol, and their derivatives can be used.

[0081] Polyol monomers can be used alone or in combination of two or more.

[0082] Furthermore, examples of rubber-based polymers include: polyisobutylene (PIB), copolymers of isobutylene and n-butene, copolymers of isobutylene and isoprene (e.g., ordinary butyl rubber, chlorinated butyl rubber, brominated butyl rubber, partially crosslinked butyl rubber, etc.), and their vulcanizates; styrene-ethylene-butene-styrene block copolymers (SEBS), styrene-isoprene-styrene block copolymers (SIS), isoprene rubber (IR), styrene-butadiene-styrene block copolymers (SBS), and styrene-ethylene-propylene-styrene block copolymers (S... Styrene-based thermoplastic elastomers include styrene-based block copolymers such as EPS and SIS (hydrogenated forms), styrene-ethylene-propylene block copolymers (SEP and styrene-isoprene block copolymers), styrene-isobutylene-styrene block copolymers (SIBS), and styrene-butadiene rubber (SBR); synthetic butyl rubber (IIR), recycled butyl rubber, butadiene rubber (BR), acrylonitrile-butadiene rubber (NBR), EPR (binary ethylene-propylene rubber), EPT (tertiary ethylene-propylene rubber), acrylic rubbers, urethane rubbers, and silicone rubbers.

[0083] A trace amount of hardener may also be incorporated into the adhesive composition. This can enhance the cohesiveness of adhesive layer 1. Examples of hardeners are described below.

[0084] The mixing ratio of the hardener is adjusted to a ratio that, on the one hand, improves the peel adhesion of adhesive layer 1, and on the other hand, slightly hardens (not fully hardens) the adhesive composition.

[0085] Specifically, the mixing ratio of the hardener is, for example, 0.05 parts by weight or more, preferably 0.15 parts by weight or more, relative to 100 parts by weight of epoxy resin.

[0086] Furthermore, the mixing ratio of the hardener relative to 100 parts by weight of epoxy resin is, for example, 5 parts by weight or less, preferably 3 parts by weight or less.

[0087] Furthermore, when the hardener is an imidazole compound as described later, the mixing ratio is, specifically, 0.05 parts by mass or more, preferably 0.15 parts by mass or more, relative to 100 parts by mass of epoxy resin, and, for example, 5 parts by mass or less, preferably 3 parts by mass or less.

[0088] If the mixing ratio of the hardener is above the lower limit mentioned above, the peel adhesion of the adhesive layer 1 can be improved. If the mixing ratio of the hardener is below the upper limit mentioned above, the complete hardening of the adhesive layer 1 can be suppressed, the decrease in reactivity between the adhesive layer 1 and the hardener layer 3 can be suppressed, and the hardened layer 5 described later can be formed more reliably.

[0089] To obtain an adhesive composition, for example, epoxy resin is formulated with various polymers (acrylic polymer solutions, urethane polymer solutions, polyester polymer solutions, and rubber polymer solutions, etc.) and / or hardeners as needed, and diluted with solvents as needed to prepare a varnish.

[0090] Any solvent that can dissolve the adhesive composition is acceptable; examples include the solvents mentioned above. Ketone-based solvents are preferred.

[0091] The concentration of the adhesive composition in the varnish is, for example, 20% by mass or more, preferably 40% by mass or more.

[0092] Furthermore, the concentration of the adhesive composition in the varnish is, for example, 80% by mass or less, preferably 70% by mass or less.

[0093] Furthermore, when acrylic polymers, carbamate polymers, polyester polymers, and rubber polymers (hereinafter also referred to as polymers) are formulated into the adhesive composition, a crosslinking agent may also be formulated during the preparation of the adhesive composition.

[0094] Examples of crosslinking agents include isocyanate-based crosslinking agents, aziridine-based crosslinking agents, epoxy-based crosslinking agents, and metal chelate-based crosslinking agents, with isocyanate-based or epoxy-based crosslinking agents being preferred.

[0095] Examples of isocyanate-based crosslinking agents include aromatic isocyanates such as toluene diisocyanate and phenyl diisocyanate, alicyclic isocyanates such as isophorone diisocyanate, and aliphatic isocyanates such as hexamethylene diisocyanate.

[0096] More specifically, examples include: lower aliphatic polyisocyanates such as butyl diisocyanate and hexamethylene diisocyanate; alicyclic isocyanates such as cyclopentyl diisocyanate, cyclohexyl diisocyanate, and isophorone diisocyanate; aromatic diisocyanates such as 2,4-toluene diisocyanate, 4,4'-diphenylmethane diisocyanate, phenyl diisocyanate, and polymethylene polyphenyl isocyanate; trimethylolpropane / toluene diisocyanate trimer adduct (manufactured by Tosoh Corporation, trade name Coronate L); trimethylolpropane / hexamethylene diisocyanate trimer adduct (manufactured by Tosoh Corporation, trade name Coronate HL); and isocyanurate derivatives of hexamethylene diisocyanate (manufactured by Tosoh Corporation, trade name Coronate). Isocyanate adducts such as HX, trimethylolpropane adduct of phenyl diisocyanate (manufactured by Mitsui Chemicals, trade name D110N), trimethylolpropane adduct of hexamethylene diisocyanate (manufactured by Mitsui Chemicals, trade name D160N); polyether polyisocyanates, polyester polyisocyanates, and their adducts with various polyols, as well as polyisocyanates that have been multifunctionalized using isocyanurate bonds, biuret bonds, urethane bonds, etc.

[0097] Epoxy crosslinking agents are polyfunctional epoxy compounds having two or more epoxy groups in one molecule. Examples of epoxy crosslinking agents include: bisphenol A, epichlorohydrin-type epoxy resins, vinyl glycidyl ether, N,N,N',N'-tetraglycidyl-m-phenylenediamine, diglycidyl aniline, diamine glycidylamine, 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane, 1,6-hexanediol diglycidyl ether, neopentyl glycol diglycidyl ether, ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, and sorbitol. Examples of epoxy resins include alcohol-based polyglycidyl ethers, glycerol-based polyglycidyl ethers, pentaerythritol-based polyglycidyl ethers, glycerol diglycidyl ethers, glycerol triglycidyl ethers, polyglycerol polyglycidyl ethers, sorbitan polyglycidyl ethers, trimethylolpropane polyglycidyl ethers, diglycidyl adipate, diglycidyl phthalate, triglycidyl isocyanate tri(2-hydroxyethyl) ester, resorcinol diglycidyl ether, and bisphenol-S-d-diglycidyl ether. Other examples include epoxy resins with two or more intramolecular epoxy groups. As epoxy crosslinking agents, products manufactured by Mitsubishi Gas Chemical Co., Ltd. under the trade names "Tetrad C" and "Tetrad X" can be used, for example.

[0098] The crosslinking agent is formulated at a ratio of 0.5 parts by mass or more, preferably 5 parts by mass or more, relative to 100 parts by mass of the polymer.

[0099] Furthermore, the mixing ratio of the crosslinking agent relative to 100 parts by mass of the polymer is, for example, 20 parts by mass or less, preferably 15 parts by mass or less.

[0100] In this way, an adhesive composition is prepared. Then, the adhesive composition is applied to the surface of the release liner 10 and then dried.

[0101] The release liner 10 is, for example, a release sheet in a generally rectangular flat plate shape, with its upper and lower surfaces formed flat.

[0102] The release liner 10 is formed into a film from ethylene polymers such as polyolefins (specifically polyethylene, polypropylene), ethylene-vinyl acetate copolymer (EVA), polyesters such as polyethylene terephthalate, polycarbonate, and fluoropolymers such as polytetrafluoroethylene.

[0103] Furthermore, the release liner 10 can also be formed from metal materials such as iron, aluminum, or stainless steel.

[0104] As the release liner 10, a polyester film is preferred, and a polyethylene terephthalate film is even more preferred.

[0105] Furthermore, a long-chain alkyl or silicone-based release treatment layer may be provided on the surface of the release liner 10 as needed to perform appropriate release treatment.

[0106] The thickness of the peeling liner 10 is, for example, between 10 μm and 1000 μm.

[0107] Examples of coating methods include: applicator method, doctor blade method, roller method, screen printing method, gravure method, spray method, etc.

[0108] As for heating conditions, the heating temperature is, for example, 70°C or higher and 160°C or lower. Also, the heating time is, for example, 1 minute or higher and 5 minutes or lower.

[0109] When the adhesive composition contains a crosslinking agent, depending on the type of crosslinking agent, further heating can be performed after the above heating to carry out a curing treatment in which the polymer is crosslinked by the crosslinking agent.

[0110] The temperature for further heating is, for example, above 30°C and below 60°C. The heating time is, for example, more than 1 hour, preferably more than 1 day, and also, for example, less than 7 days.

[0111] When the adhesive composition contains a hardener, the heating temperature is, for example, 70°C to 160°C. Furthermore, the heating time is 5 minutes to 5 hours. In this way, all of the hardener reacts with a portion of the epoxy resin.

[0112] Through the above, an adhesive layer 1 is formed on the surface of the release liner 10 by the adhesive composition.

[0113] Furthermore, the adhesive layer 1 can also be configured as shown in FIG2, having a first adhesive layer 11, a first substrate layer 13, and a second adhesive layer 12 sequentially arranged facing upward (in the thickness direction), and formed on the surface of the release liner 10. In other words, the adhesive layer 1 can also be configured to have a first substrate layer 13 and a second adhesive layer 12 and a first adhesive layer 11 disposed on its upper and lower sides, and formed on the surface of the release liner 10.

[0114] Furthermore, the adhesive layer 1 may also be formed without the use of the release liner 10, by providing the first adhesive layer 11 and the second adhesive layer 12 on both sides of the first substrate layer 13.

[0115] The first substrate layer 13 is a support layer that imparts toughness to the adhesive layer 1, and has a generally flat (sheet) shape that extends along the surface direction of the adhesive layer 1.

[0116] The first substrate layer 13 may be either soft or hard. Furthermore, the first substrate layer 13 may also contain air bubbles. Moreover, the first substrate layer 13 may be a porous sheet that extends throughout its thickness direction through a porous treatment. Specifically, a foamed sheet can be cited as an example of a porous sheet. In this case, the adhesive layer comprises a porous sheet impregnated with an adhesive composition containing epoxy resin as a main component.

[0117] Examples of materials that can be used to make foam sheets include: amorphous cross-linked materials such as polyurethane, polyolefins (polyethylene, polypropylene and copolymers thereof), silicone, acrylic resins, and rubber.

[0118] As a material for foamed sheets, resins are preferred, polyurethanes and polyolefins are more preferred, and polyurethanes are even more preferred.

[0119] Polyurethane has low compressive hardness and is easily deformable relative to stepped surfaces, allowing it to follow substrates with stepped surfaces (excellent step following ability). As a foaming form of foamed sheet, examples include continuous foaming and independent foaming. In terms of the permeability of the curing agent component, continuous foaming is preferable.

[0120] Furthermore, as a porous sheet material, there are no particular limitations as long as it has a plurality of pores. For example, in addition to the foamed sheets mentioned above, non-woven fabrics can also be cited. Examples of such non-woven fabrics include polyester non-woven fabrics.

[0121] When the first substrate layer 13 is a porous sheet, the adhesive layer 1 can also be a multilayer structure as shown in FIG. 2, wherein the adhesive composition is contained in a plurality of pores within the first substrate layer 13. In this configuration, the adhesive composition is present in both the upper and lower surfaces of the first substrate layer 13 within the plurality of pores. To produce this type of adhesive layer 1, for example, the adhesive composition is impregnated in the porous sheet, and then the solvent is allowed to evaporate.

[0122] Furthermore, when the first substrate layer 13 is a porous sheet, the adhesive layer 1 may also be a single-layer structure in which the above-mentioned adhesive composition is contained in a plurality of pores within the first substrate layer 13, rather than a multi-layer structure as shown in FIG2.

[0123] When the first substrate layer 13 is a porous sheet, the hardener contained in the hardener layer 3 described later penetrates through the plurality of pores in the first substrate layer 13 into the plurality of pores or into the adhesive composition present on the upper and lower surfaces of the first substrate layer 13, thereby hardening the adhesive layer 1, which is even better.

[0124] The thickness of the first substrate layer 13 is, for example, 2 μm or more, preferably 10 μm or more. Also, the thickness of the first substrate layer 13 is, for example, 75 μm or less, preferably 50 μm or less.

[0125] If the first substrate layer 13 is a foamed sheet, its thickness is, for example, 0.5 mm or more, preferably 1 mm or more, and, for example, 8 mm or less, preferably 5 mm or less. If the thickness of the first substrate layer 13 is above or below the aforementioned lower limit, the step followability is excellent.

[0126] Furthermore, when the adhesive layer 1 is a single-layer structure containing an adhesive composition in a plurality of pores within the first substrate layer 13, the thickness of the first substrate layer 13 is the same as or approximately the same as the thickness of the adhesive layer 1.

[0127] Furthermore, the various physical properties of the first substrate layer 13 are appropriately set according to the first substrate 2 and the second substrate 4, without any particular limitation.

[0128] The thickness of the adhesive layer 1 before curing is, for example, 3 μm or more, preferably 5 μm or more, and more preferably 10 μm or more. Furthermore, the thickness of the adhesive layer 1 before curing is, for example, 100 μm or less, preferably 80 μm or less, and more preferably 70 μm or less.

[0129] Having an adhesive layer 1 with a thickness of 3 μm or more before curing is advantageous in terms of ensuring adhesion and conformability to uneven surfaces.

[0130] Furthermore, since the thickness of adhesive layer 1 before curing is less than 100 μm, the curing agent described below can penetrate into adhesive layer 1 more easily, which is beneficial in terms of increasing the curing speed.

[0131] Alternatively, other release liner (not shown) may be disposed (in contact with) the surface of adhesive layer 1 (the surface opposite to the contact surface of release liner 10). That is, adhesive layer 1 may also be sandwiched between two release liner.

[0132] Secondly, the adhesive layer 1 has pressure-sensitive adhesion (adhesion or initial adhesion).

[0133] Then, the adhesive layer 1 is transferred from the release liner 10 to the surface of the first substrate 2. Specifically, first, the adhesive layer 1 is brought into contact with the first substrate 2, and then, as shown by the arrow in FIG1(A), the release liner 10 is peeled off from the adhesive layer 1.

[0134] Alternatively, the self-adhesive layer 1 of the release liner 10 can be peeled off after step (2) and just before step (3) begins.

[0135] Furthermore, in the case where the adhesive layer 1 is sandwiched between two release liner pads, for example, firstly, one release liner pad is peeled off. Next, the exposed surface of the adhesive layer 1 is brought into contact with the first bonded object 2, and then, as shown by the arrow in FIG1(A), the release liner pad 10 is peeled off from the adhesive layer 1.

[0136] There are no particular limitations on the first substrate 2, and examples include porous materials such as metal, glass, plastic, slate or non-woven fabric, mortar, concrete, rubber, wood, leather, cloth, paper, etc.

[0137] Examples of the first bonded material 2 include metal, slate, mortar, and concrete.

[0138] Thus, as shown in Figure 1(A), adhesive layer 1 is disposed on the first bonded body 2.

[0139] (i) Step (2) The hardener layer 3 is a layer that can harden the adhesive layer 1 by reacting with it. It has a generally flat shape that extends along the surface direction (orthogonal to the thickness direction) and includes a flat front and back.

[0140] In step (2), as shown in FIG1(A), the hardener layer 3 is disposed on the second bonded body 4.

[0141] To configure the hardener layer 3 onto the second bonded body 4, for example, the hardener components are first prepared.

[0142] The hardener contains a hardener.

[0143] The curing agent used in this embodiment is a polymerization catalyst type curing agent. As is well known, a polymerization catalyst type curing agent is a compound that catalyzes the self-polymerization reaction of epoxy groups. For example, the function of a polymerization catalyst type curing agent is to induce a three-stage reaction: the first stage is the formation of an adduct with the epoxy resin; the second stage is the further addition to the epoxy resin to become an ionic compound; and the third stage is the initiation of a polymerization reaction between the epoxy resins.

[0144] Examples of polymerization catalyst-type curing agents include: tertiary amines, quaternary ammonium salts, phosphine compounds, phosphonium salts, and imidazole compounds. Among these, imidazole compounds are preferred due to their faster curing speed.

[0145] Examples of imidazole compounds include: methylimidazolium, 2-ethyl-4-methylimidazolium, 1-isobutyl-2-methylimidazolium (IBMI12), 1-benzyl-2-methylimidazolium (1B2MZ), 1,2-dimethylimidazolium (1,2DMZ), 1-butylimidazolium (1BZ), 1-decyl-2-methylimidazolium (1D2MZ), 1-octylimidazolium (1OZ), 2-ethyl-4-methylimidazolium, ethylimidazolium, isopropylimidazolium, 2,4-dimethylimidazolium (2E4MZ), 1-phenylimidazolium (1PZ), undecylimidazolium, heptadecanylimidazolium, 2-phenyl-4-methylimidazolium, 2-phenyl-4,5-dihydroxymethylimidazolium, 2-phenyl-4-methyl-5-hydroxymethylimidazolium, etc. From the viewpoint of curing speed, 1-substituted imidazolium compounds are preferred.

[0146] Hardeners can be used alone or in combination with two or more.

[0147] The mixing ratio of the hardener relative to the hardener components is, for example, 10% by mass or more, preferably 30% by mass or more, more preferably 50% by mass or more, and even more preferably 60% by mass or more, and even more preferably 80% by mass or more.

[0148] Furthermore, for example, it is 100% by mass or less, preferably 90% by mass or less. The mixing ratio of the hardener relative to the hardener composition is preferably 60% by mass or more and 90% by mass or less. If the mixing ratio of the hardener is above or below the above lower limit, the adhesion of the adhesive layer 1 is excellent.

[0149] The curing agent components can also be formulated with the above-mentioned epoxy resin as needed.

[0150] The mixing ratio of epoxy resin relative to 100 parts by weight of hardener is 30 parts by weight or more, preferably 40 parts by weight or more. Furthermore, the mixing ratio of epoxy resin relative to 100 parts by weight of hardener is, for example, 70 parts by weight or less, preferably 60 parts by weight or less.

[0151] If the mixing ratio of epoxy resin is below the above upper limit, then in step (2), it can prevent almost all of the hardener in the hardener layer 3 from reacting with the epoxy resin, and in step (3), it can prevent the reactivity of the hardener layer 3 (the hardener) relative to the adhesive layer 1 (the epoxy resin) from decreasing.

[0152] Furthermore, reaction diluents or metal catalysts may be added to the hardener components as needed.

[0153] Examples of reaction diluents include glycidyl ethers, which can be monofunctional or polyfunctional. Examples of metal catalysts include organometallic compounds of Al, Sn, Zr, and Fe.

[0154] The mixing ratio of the reactive diluent relative to 100 parts by mass of the hardener is, for example, 1 part by mass or more, preferably 5 parts by mass or more. Furthermore, the mixing ratio of the reactive diluent relative to 100 parts by mass of the hardener is, for example, 80 parts by mass or less, preferably 50 parts by mass or less.

[0155] The mixing ratio of the metal catalyst relative to 100 parts by weight of the hardener is 0.01 parts by weight or more, preferably 0.1 parts by weight or more. Furthermore, the mixing ratio of the metal catalyst relative to 100 parts by weight of the hardener is, for example, 10 parts by weight or less, preferably 5 parts by weight or less.

[0156] To prepare the curing agent components, the curing agent is mixed with epoxy resin, reaction diluent, metal catalyst, etc., as needed, to prepare the curing agent component liquid.

[0157] If the hardener is in solid form, it can be dissolved in a solvent as needed to prepare a hardener component solution.

[0158] As a solvent, any solvent that can dissolve the adhesive composition is acceptable; examples include the solvents mentioned above.

[0159] The concentration of the hardener component in the hardener solution is, for example, 10% by mass or more, preferably 20% by mass or more.

[0160] Furthermore, the concentration of the hardener component in the hardener solution is, for example, 100% by mass or less, preferably 50% by mass or less.

[0161] Based on the above, the hardener components are prepared.

[0162] Next, the hardener component is applied to the second substrate 4. Specifically, the hardener liquid is applied to the second substrate 4.

[0163] There are no particular restrictions on the second substrate 4, and examples of the aforementioned substrates can be cited.

[0164] Furthermore, when the second adhesive 4 is a porous material, the hardener contained in the hardener layer 3 may penetrate into the porous material, thereby potentially hindering the reaction between the adhesive layer and the hardener layer (hardener). Therefore, when using method (i), the second adhesive 4 is preferably made of a material other than a porous material; and when a porous material is used as the second adhesive 4, the method described later (ii) is preferred.

[0165] Examples of coating methods include the methods mentioned above.

[0166] Then, if necessary, remove excess hardener from the surface of the second substrate 4. For example, wipe away excess hardener from the surface of the second substrate 4.

[0167] In this way, a hardener layer 3 is formed on the surface of the second substrate 4, and the hardener layer 3 is disposed on the second substrate 4.

[0168] This forms an adhesive sleeve 7 comprising an adhesive layer 1 disposed on the first substrate 2 and a hardener layer 3 disposed on the second substrate 4.

[0169] (i) Step (3) In step (3), as shown in FIG1(B), the adhesive layer 1 and the hardener layer 3 are arranged such that they are sandwiched between the first substrate 2 and the second substrate 4. That is, the first substrate 2 and the second substrate 4 overlap with the adhesive layer 1 and the hardener layer 3. In this way, the adhesive layer 1 and the hardener layer 3 react with each other through the action of the hardener. The action of the hardener can be exemplified by, for example, the penetration of the hardener into the adhesive layer 1.

[0170] Furthermore, Figure 1(B) shows a state in which the adhesive layer 1 and the hardener layer 3 are in contact with each other, but it is not limited to this. As long as the hardener contained in the hardener layer 3 acts (penetrates) into the adhesive layer 1, a second substrate layer 8 can also be provided between the adhesive layer 1 and the hardener layer 3 as shown in Figure 3.

[0171] The reaction temperature is, for example, room temperature.

[0172] Alternatively, the adhesive layer 1 and the hardener layer 3 may be heated as needed, for example, at a temperature of 50°C or higher, preferably 70°C or higher. Alternatively, the heating temperature may be, for example, below 130°C, preferably below 110°C.

[0173] The reaction temperature is preferably room temperature. Room temperature is the temperature at which the above-mentioned heating (e.g., heating above 50°C) used to react the adhesive layer 1 with the hardener layer 3 is not carried out. For example, if it does not reach 50°C, it is preferably below 40°C, or, for example, above 10°C, and preferably above 20°C.

[0174] If the reaction temperature is room temperature, there is no need for heating to react the adhesive layer 1 and the hardener layer 3, and the first substrate 2 and the second substrate 4 can be bonded more easily.

[0175] The reaction time is, for example, more than 1 hour, preferably more than 12 hours. Also, the reaction time is, for example, less than 96 hours, preferably less than 48 hours.

[0176] Through the above process, adhesive layer 1 hardens, becoming hardened layer 5. Preferably, adhesive layer 1 hardens at room temperature.

[0177] The thickness of the hardened layer 5 (or any thickness other than the first substrate layer 13 or the second substrate layer 8 when the hardened layer 5 includes such layers) is preferably 3 μm or more, and more preferably 15 μm or more. Furthermore, the thickness of the hardened layer 5 is preferably 150 μm or less, and more preferably 120 μm or less.

[0178] Furthermore, in Figure 1(B), there is a boundary between adhesive layer 1 and hardener layer 3, but hardener layer 5 is a layer formed by the integrated reaction of adhesive layer 1 and hardener layer 3, and the above-mentioned boundary does not exist.

[0179] The first substrate 2 and the second substrate 4 are bonded together by the hardening layer 5.

[0180] The shear adhesion of the hardened layer 5 is, for example, 0.1 MPa or more, preferably 0.4 MPa or more, more preferably 0.6 MPa or more, even more preferably 0.7 MPa or more, particularly preferably 1.0 MPa or more, most preferably 2.3 MPa or more, even more preferably 2.5 MPa or more, and even more preferably 3.5 MPa or more.

[0181] If the shear adhesion of the hardened layer 5 is above the lower limit mentioned above, the adhesion of the adhesive layer is excellent, and the first substrate 2 and the second substrate 4 can be bonded with higher reliability.

[0182] The shear adhesion of the hardened layer 5 was determined by the following method. One of the self-adhesive layers 1 of the adhesive layer 1, which is sandwiched between two peeled polyethylene terephthalate films, was peeled off. The peeled adhesive layer 1 was then placed on the first slate slab. Next, the other self-adhesive layer 1 of the polyethylene terephthalate film was peeled off. Additionally, the hardener layer 3 was placed on the second slate slab.

[0183] Next, the adhesive layer 1 and the hardener layer 3 are brought into contact in such a way that they are sandwiched between the first slate slab and the second slate slab, and left for 24 hours to form the hardened layer 5. Then, the first slate slab and the second slate slab are pulled along the shear direction at a speed of 5 mm / min, and the strength of the two slate slabs when they are peeled off is obtained as the shear bonding force.

[0184] The above steps are used to manufacture the bonding structure 6. That is, the bonding structure 6 includes a first bonded body 2, a second bonded body 4 disposed opposite to the first bonded body 2, and a hardening layer 5 sandwiched between them. In the bonding structure 6, the first bonded body and the second bonded body are firmly bonded together by the hardening layer 5.

[0185] Next, the method (ii) for setting the adhesive layer and the hardener layer described above will be explained. Method (ii) is a method in which the adhesive layer is placed on the first substrate, a hardener layer that can harden the adhesive layer by reacting with the adhesive layer is placed on the adhesive layer, and then the second substrate is placed on it.

[0186] In method (ii), except that the hardener layer is not placed on the second substrate but on the adhesive layer, the implementation method is the same as that of method (i), and the preferred form is also the same.

[0187] In the hardened layer 5, a second substrate layer 8 can also be provided near the center of the hardened layer 5 in the thickness direction, as shown in Figure 3. That is, the second substrate layer 8 can also be provided between the adhesive layer 1 and the hardener layer 3 before hardening. The second substrate layer 8 imparts toughness to the hardened layer.

[0188] For example, in either method (i) or method (ii), a hardener layer 3 can be disposed on the second substrate layer 8 while the adhesive layer 1 is provided, or an adhesive layer 1 can be disposed on the second substrate layer 8 while the hardener layer 3 is provided.

[0189] The material of the second substrate layer 8 can be the same as that of the first substrate layer 13 of the adhesive layer 1. When the second substrate layer 8 is a porous sheet, the hardener contained in the hardener layer 3 can penetrate through the second substrate layer 8 to the adhesive layer 1, thereby hardening the adhesive layer 1, which is preferable.

[0190] The thickness of the second substrate layer 8 is appropriately set according to the first substrate 2 and the second substrate 4, without particular limitation, for example, it is 2 μm or more, preferably 10 μm or more. Also, the thickness of the second substrate layer 8 is, for example, 75 μm or less, preferably 50 μm or less.

[0191] The bonding method of this embodiment is characterized in that the thickness A (m) of the adhesive layer before curing and the coating amount B (kg / m2) of the curing agent contained in the curing agent layer satisfy the following formula (1). 5

[0192] Here, the coating amount B (kg / m 2) of the hardener layer refers to the content (kg) of hardener relative to the coating area (m 2) of the hardener.

[0193] Furthermore, the coating area of ​​the so-called hardener is consistent with the surface area of ​​the main surface of the hardener layer formed by the hardener coating, and also consistent with the surface area of ​​the main surface of the adhesive layer. Therefore, B / A in formula (1) is consistent with the value obtained by dividing the content of hardener in the hardener layer (kg) by the volume of the adhesive layer (m3).

[0194] By making the above B / A satisfy the above formula (1), the first substrate and the second substrate can be easily and firmly bonded together, and the hardening difference of the resulting bonded structure can be suppressed, and undesirable changes in physical properties can be suppressed.

[0195] If the B / A ratio is below 5, the desired adhesive strength caused by the hardener cannot be achieved.

[0196] ​If the B / A ratio is above 900, then there is an excess of hardener, the adhesive layer becomes sticky, and uneven hardening is likely to occur.

[0197] To ensure that the above B / A satisfies the above formula (1), for example, a method is used such as using a sprayer, roller and bar applicator to apply a fixed amount of hardener component liquid with an adjusted concentration of hardener component.

[0198] Furthermore, when one of the bonded bodies is a porous material such as slate, in order to satisfy the above formula (1), it is preferable to apply the above method (ii) to set the adhesive layer and the hardener layer. In this way, even if the bonded body is a porous material, there will be no situation where the hardener penetrates into the porous material and hinders the penetration into the adhesive layer, and the hardener can be quantitatively applied (penetrated) into the adhesive layer.

[0199] The B / A (kg / m 3) mentioned above is preferably greater than 6 kg / m 3, more preferably greater than 30 kg / m 3, and even more preferably greater than 100 kg / m 3.

[0200] Furthermore, the aforementioned B / A is preferably less than 600 kg / m³, more preferably less than 500 kg / m³, and even more preferably less than 400 kg / m³.

[0201] The aforementioned hardening differences can be evaluated by the elastic modulus (Pa) of the hardened adhesive layer 1.

[0202] Specifically, regarding the elastic modulus (Pa) of the adhesive layer 1 after curing, if it is 5×10⁷ (Pa) or higher after 48 hours at room temperature (25°C), then the curing of the adhesive layer 1 is sufficient and can be judged as having no curing difference.

[0203] The elastic modulus (Pa) of the hardened adhesive layer 1 is preferably 5×10⁷ (Pa) or more, more preferably 1×10⁸ (Pa) or more, and especially preferably 5×10⁸ (Pa) or more.

[0204] Furthermore, the elastic modulus (Pa) of the adhesive layer 1 after curing is preferably more than 10 times, more preferably more than 100 times, and even more preferably more than 10,000 times compared to the elastic modulus (Pa) of the adhesive layer 1 before curing.

[0205] Furthermore, the elastic modulus (Pa) of the adhesive layer 1 before and after curing refers to the value measured by the method described in the examples. [Example]

[0206] The following embodiments and comparative examples are disclosed to further illustrate the present invention. However, the present invention is not limited to any particular embodiment or comparative example.

[0207] Furthermore, the specific values ​​of mixing ratios (including ratios), physical property values, parameters, etc. used in the following description can be replaced with the corresponding upper limit values ​​(as defined by "below" or "not reached") or lower limit values ​​(as defined by "above" or "exceeding") of the mixing ratios (including ratios), physical property values, parameters, etc., described in the above "Implementation Method".

[0208] Furthermore, the terms "liquid" and "solid" refer to their properties at room temperature (25°C).

[0209] Furthermore, unless otherwise stated, "parts" and "%" are quality standards.

[0210] (Examples 1-12, Comparative Examples 1-2) The following adhesive compositions (varnishes) were prepared by mixing the following products in the combinations and proportions shown in Table 1: liquid bisphenol A epoxy resin (trade name "jER828", manufactured by Mitsubishi Chemical Co., Ltd.), liquid bisphenol F epoxy resin (trade name "jER806", manufactured by Mitsubishi Chemical Co., Ltd.), solid bisphenol A epoxy resin (trade name "jER1256", manufactured by Mitsubishi Chemical Co., Ltd.), solid bisphenol F epoxy resin (trade name "jER4010P", manufactured by Mitsubishi Chemical Co., Ltd.), liquid multifunctional phenolic varnish epoxy resin (trade name "jER152", manufactured by Mitsubishi Chemical Co., Ltd.), and solid special phenolic varnish epoxy resin (trade name "jER157s70", manufactured by Mitsubishi Chemical Co., Ltd.). Methyl ethyl ketone was added for dilution to make the epoxy resin concentration 65%. The adhesive layer was coated onto the release-treated surface of a polyethylene terephthalate (PET) film (trade name "DIAFOIL MRF#38", manufactured by Mitsubishi Chemical Corporation) that had undergone release treatment with a silicone-based release agent, with the thickness (thickness of the adhesive layer) as shown in Table 2 after drying and before curing. The film was then dried at 80°C for 3 minutes to obtain adhesive layers A through C. Subsequently, the adhesive layer was sandwiched between two polyethylene terephthalate films to bring it into contact with another polyethylene terephthalate film, thus obtaining a sheet.

[0211] (Example 13) Liquid bisphenol A epoxy resin (trade name "jER828", manufactured by Mitsubishi Chemical Corporation), solid bisphenol A epoxy resin (trade name "jER1256", manufactured by Mitsubishi Chemical Corporation), and liquid multifunctional phenolic varnish epoxy resin (trade name "jER152", manufactured by Mitsubishi Chemical Corporation) were mixed in the proportions shown in Table 1 below. Methyl ethyl ketone was added for dilution to bring the epoxy resin concentration to 20%, thus preparing an adhesive composition (varnish). In the above varnish, a polyurethane foam sheet (trade name: "kurara Foam 780EA", 3 mm thick, continuously foamed type, manufactured by Kurashiki Bosho Co., Ltd.) was impregnated as the first substrate layer, ensuring that the varnish was fully impregnated into the pores of the polyurethane foam sheet. Subsequently, the polyurethane foam sheet was lifted from the varnish and then heated at 80°C to evaporate the methyl ethyl ketone, resulting in an epoxy resin-containing substrate sheet (adhesive layer) with epoxy resin present in multiple pores, on the upper and lower surfaces. Furthermore, the thickness of the adhesive layer (before curing) shown in Table 2 includes the total thickness of the adhesive layer of the aforementioned porous sheet.

[0212] (Determination of elastic modulus) (Examples 1-12, Comparative Examples 1-2) In Examples 1-12 and Comparative Examples 1-2, the elastic modulus before hardening was determined as follows. First, a 30 mm × 30 mm sample sheet was cut out, a PET film with a peeling treatment was peeled off, and the exposed adhesive layer was rolled into a cylindrical shape to prepare a test sample. Then, a tensile test was performed on the prepared test sample with a clamping distance of 10 mm and a tensile speed of 50 mm / min. The initial tensile elastic modulus (Pa) was obtained by the slope of the initial part (tangent) of the obtained stress-strain curve.

[0213] In Examples 1-12 and Comparative Examples 1-2, the modulus of elasticity during curing was determined as follows. First, one of the PET films of the obtained sheet was peeled off, and the curing agent components were applied using a wire bar coater at the amount specified in Table 2 below. The mixture was allowed to react at room temperature (25°C) for 48 hours to cure the adhesive layer and obtain a cured layer. Next, the other PET film of the sheet was peeled off, and the cured sheet was cut into pieces 10 mm wide and 40 mm long. A tensile test was performed with a clamping distance of 10 mm and a stretching speed of 50 mm / min. The initial tensile modulus of elasticity (Pa) was obtained by measuring the slope of the initial portion (tangent) of the obtained stress-strain curve.

[0214] (Example 13) In Example 13, the elastic modulus before hardening was determined as follows. First, a 30 mm × 30 mm specimen was cut out and a compression test was performed at a compression speed of 10 mm / min. The initial tensile elastic modulus (Pa) was obtained by the slope of the initial portion of the stress-strain curve (the thickness was compressed from the initial value to 20%).

[0215] In Example 13, the modulus of elasticity during curing was determined as follows. First, the hardener components were applied using a sprayer at the application amounts specified in Table 2 below, and allowed to react at room temperature (25°C) for 48 hours to harden the adhesive layer, resulting in a hardened layer. Subsequently, 30 mm × 30 mm specimens were cut out and compression tests were performed at a compression speed of 10 mm / min. The initial tensile modulus of elasticity (Pa) was determined by the slope of the initial portion of the obtained stress-strain curve (thickness compressed from the initial value to 20%).

[0216] The results are shown in Table 2. In Table 2, (A)E+(0X) is notated as A×10⁻¹⁰ X, and (B)E-(0Y) is notated as B×10⁻¹⁰ -Y. Furthermore, "sticky" indicates the presence of unreacted hardener components in the adhesive layer, and also indicates stickiness due to insufficient hardening of the adhesive layer. The abbreviations for each hardener in Table 2 are detailed below.

[0217] 1,2DMZ: 1,2-Dimethylimidazole 1B2MZ: 1-Benzyl-2-methylimidazolium 1BZ: 1-Butylimidazole 1D2MZ:1-decyl-2-methylimidazolium 1 oz: 1-Octylimidazole 2E4MZ:2,4-Dimethylimidazole IBMI12: 1-Isobutyl-2-methylimidazolium

[0218] [Table 1] Table 1 Epoxy resin Types of epoxy resins Product Name Adhesive layer A Adhesive layer B Adhesive layer C Liquid epoxy resin Bisphenol A type epoxy resin jER828 69 45 - Bisphenol F type epoxy resin JER806 - - 59 Solid epoxy resin Bisphenol A type epoxy resin jER1256 30 30 - Bisphenol F type epoxy resin jER4010P - - 40 Multifunctional epoxy resin Phenolic varnish series jER152 - 25 - Special phenolic varnish type epoxy resin jER157S70 1 - 1

[0219] [Table 2] Table 2 Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Example 8 Example 9 Example 10 Example 11 Example 12 Example 13 Comparative Example 1 Comparative Example 2 Adhesive layer type A A A A A A A A A B B C B A A Thickness (before hardening) μm 50 50 50 50 50 50 50 50 50 25 50 75 3580 50 50 hardener components Types of hardeners 1,2DMZ 1B2MZ 1BZ 1D2MZ 1 oz 2E4MZ IBM I12 IBM I12 IBM I12 1,2DMZ 1,2DMZ IBM I12 1,2DMZ 1,2DMZ IBM I12 Application amount of hardener components g / m 2 10.4 10.4 8.9 8.9 8.9 10.8 twenty one 42 1.5 9.5 4 10 720 10.4 52.2 hardener ratio % 80 80 100 100 100 80 100 100 100 80 10 100 80 1 100 Application amount of hardener g / m 2 8.3 8.3 8.9 8.9 8.9 8.6 21.0 42.0 1.5 7.6 0.4 10.0 576.0 0.1 52.2 Equation (1) Thickness of the adhesive layer (A) m 5.0E-05 5.0E-05 5.0E-05 5.0E-05 5.0E-05 5.0E-05 5.0E-05 5.0E-05 5.0E-05 2.5E-05 5.0E-05 7.5E-05 3.6E-03 5.0E-05 5.0E-05 Application amount of hardener (B) kg / m 2 8.3E-03 8.3E-03 8.9E-03 8.9E-03 8.9E-03 8.6E-03 2.1E-02 4.2E-02 1.5E-03 7.6E-03 4.0E-04 1.0E-02 5.8E-01 1.0E-04 5.2E-02 (B) / (A) kg / m 3 166 166 178 178 178 173 420 840 30 304 8 133 161 2 1044 physical properties Elastic modulus before hardening Pa 5.0E+04 5.0E+04 5.0E+04 5.0E+04 5.0E+04 5.0E+04 5.0E+04 5.0E+04 5.0E+04 1.2E+05 1.2E+05 5.0E+04 2.3E+04 5.0E+04 5.0E+04 Elastic modulus after 48 hours Pa 7.5E+08 6.6E+08 7.8E+08 7.7E+08 6.3E+08 2.8E+08 5.4.E+08 5.2.E+08 4.8E+08 7.7E+08 5.2E+08 6.5E+08 2.4E+05 Sticky Sticky Thickness of the hardened adhesive layer (hardened layer) μm 61 60 60 60 60 60 65 69 51 30 51 87 3602 51 73

[0220] As shown in Table 2, it can be seen that in the embodiments that satisfy the above formula (1), the elastic modulus increases after curing, and the curing difference of the adhesive layer decreases after curing. On the other hand, in the comparative examples that do not satisfy the above formula (1), unreacted curing agent components remain in the adhesive layer. Furthermore, because the adhesive layer is not sufficiently cured, stickiness occurs.

[0221] Although various embodiments have been described above with reference to illustrations, the present invention is not limited to these examples. It is obvious to those skilled in the art that various modifications or alterations can be conceived within the scope of the patent application claims, and these are also understood to fall within the technical scope of the present invention. Furthermore, the constituent elements of the above embodiments can be combined arbitrarily without departing from the spirit of the invention.

[0222] Furthermore, this application is based on Japanese patent application filed on November 20, 2020 (Japanese Patent Application No. 2020-193664), the contents of which are incorporated herein by reference.

[0223] 1: Adhesive layer 2: The first body to be connected 3: Hardener layer 4: The second body was connected 5: Hardened layer 6: Next, the structure 7: Next set 8: Second substrate layer 10: Peeling the liner 11: First adhesive layer 12: Second adhesive layer 13: First substrate layer

Claims

1. A bonding method, characterized in that: an adhesive layer and a hardener layer are disposed between a first substrate and a second substrate, so that the first substrate and the second substrate are bonded; the adhesive layer contains epoxy resin as the main component and is cured by the action of the hardener layer; the hardener contained in the hardener layer is a polymer catalyst type hardener; the mixing ratio of the hardener is 60% by mass or more and 90% by mass or less relative to the hardener component forming the hardener layer; the thickness A (m) of the adhesive layer before curing and the coating amount B (kg / m2) of the hardener contained in the hardener layer satisfy the following formula (1): 5 < B / A < 900 (1).

2. The method following claim 1, wherein the aforementioned polymeric catalyst-type curing agent is an imidazole compound.

3. The bonding method as requested in item 1 or 2, wherein the elastic modulus (Pa) of the adhesive layer after curing is more than 10 times that of the adhesive layer before curing.

4. The bonding method as requested in item 1 or 2, wherein the elastic modulus (Pa) of the adhesive layer after curing is 5 × 10⁷ (Pa) or higher after 48 hours at room temperature (25°C).

5. The bonding method as requested in item 1 or 2, wherein the ratio of solid resin in the adhesive layer before curing is 15% by mass or more and 80% by mass or less.

6. The bonding method as requested in item 1 or 2, wherein the thickness of the adhesive layer before curing is more than 3 μm and less than 100 μm.

7. The bonding method as claimed in claim 1 or 2, wherein the adhesive layer comprises a porous sheet impregnated with an adhesive composition comprising an epoxy resin as a main component.

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