Adhesive set, structure and method for producing the same

Abstract

To provide an adhesive set capable of forming a cured product of an adhesive composition in which substrate surface layer fracture hardly occurs in a high temperature environment.SOLUTION: An adhesive set including a main agent and a curing agent is provided. The base material contains a urethane prepolymer. The curing agent contains a polyol. At least one of the base material and the curing agent contains a filler. The filler comprises particles composed of a layered compound.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present disclosure relates to adhesive sets, as well as structures and methods of making the same. [Background technology]

[0002] Steel sheets are commonly used for interior and exterior parts of automobiles, such as bodies, front doors, rear doors, tailgates, front bumpers, rear bumpers, and rocker moldings. However, in order to meet the recent demand for improved fuel efficiency, weight reduction is required. For this reason, plastic materials such as polypropylene are increasingly being used instead of steel sheets for interior and exterior parts of automobiles. However, because plastic materials such as polypropylene have lower strength than steel sheets, it is common to add talc, glass fillers, etc. to improve their strength.

[0003] Urethane adhesive compositions have been proposed as adhesives for joining plastic automobile parts, such as polypropylene. Known urethane adhesive compositions include one-component adhesives, also known as moisture-curing adhesives, which cure when exposed to atmospheric moisture, and two-component adhesives, which are made by mixing an adhesive set consisting of a base compound and a curing agent. Two-component curing urethane adhesive compositions cure through a crosslinking reaction between a component containing an isocyanate group (NCO group) in the base compound and a component containing a hydroxyl group (OH group) in the curing agent. Among these, two-component curing adhesives tend to be preferred from the standpoint of workability in the bonding process, as they can ensure sufficient pot life (pot life, the time until the paint begins to harden due to a chemical reaction in a multi-component paint) and can cure quickly.

[0004] For example, Patent Document 1 discloses a two-component curing urethane adhesive composition in which a base agent containing a urethane prepolymer and an isocyanate silane compound and a curing agent containing polybutadiene diol are mixed during operation. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-077094 Summary of the Invention [Problem to be solved by the invention]

[0006] According to the investigations of the present inventors, when a structure in which substrates are bonded together via an adhesive layer containing a cured product of a conventional adhesive composition is subjected to shear in a high-temperature environment (e.g., 90°C), it has been found that substrate surface failure (cohesive failure) may occur. When substrate surface failure occurs, there are problems such as unstable strength of the structure and inability to reuse the substrate.

[0007] Therefore, a main object of the present disclosure is to provide an adhesive set that is capable of forming a cured product of an adhesive composition that is less likely to cause damage to the surface of a substrate in a high-temperature environment. [Means for solving the problem]

[0008]

[0009] It is believed that substrate surface layer failure occurs due to stress concentration on the substrate surface layer when shear is applied to the substrate. The present inventors have found that by applying particles composed of layered compounds with weak interlayer bonding strength so that the adhesive composition will fail preferentially even when stress is concentrated on the substrate, it is easy to obtain a cured adhesive composition that is less likely to cause substrate surface failure, and have completed the present invention.

[0009] The present disclosure provides an adhesive set according to [1], a structure according to [2], and a method for producing the structure according to [3]. [1] An adhesive set including a base agent and a curing agent, The base material contains a urethane prepolymer, the curing agent contains a polyol, At least one of the base agent and the curing agent contains a filler, The filler includes particles composed of a layered compound. Adhesive set. [2] A first substrate; a second substrate; an adhesive layer that bonds the first substrate and the second substrate to each other; Equipped with The adhesive layer contains a cured product of an adhesive composition comprising the main agent and the curing agent in the adhesive set according to claim 1. structure. [3] A method for producing the structure according to [2], a step of bonding the first substrate and the second substrate together via an adhesive composition containing the base agent and the curing agent, Method for manufacturing the structure. [Effects of the Invention]

[0010] The present disclosure provides an adhesive set capable of forming a cured product of an adhesive composition that is resistant to substrate surface damage in a high-temperature environment. The present disclosure also provides a structure obtainable by using such an adhesive set and a method for producing the same. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a schematic diagram showing the state of failure of a test specimen after an adhesion test. FIG. 1(a) is a schematic cross-sectional view showing the test specimen before the adhesion test. FIG. 1(b) is a schematic cross-sectional view showing that the failure state of the test specimen is cohesive failure. FIG. 1(c) is a schematic cross-sectional view showing that the failure state of the test specimen is interfacial failure. FIG. 1(d) is a schematic cross-sectional view showing that the failure state of the test specimen is substrate surface failure. [Figure 2] Figure 2 shows SEM (scanning electron microscope) images of the adhesive layer of the test specimen of Example 1. Figure 2(a) is an image of the cut surface of the adhesive layer observed by SEM when the adhesive layer of the test specimen of Example 1 was cut at an arbitrary location before shear strength measurement and the substrates were separated, and Figure 2(b) is an image of the cohesive failure surface of the adhesive layer of the test specimen of Example 1 observed by SEM after shear strength measurement under high temperature (90°C) conditions. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, embodiments of the present disclosure will be described. However, the present disclosure is not limited to the following embodiments. In this specification, a numerical range indicated using "to" indicates a range that includes the numerical values ​​before and after "to" as the minimum and maximum values, respectively. In addition, in numerical ranges described in stages in this specification, the upper or lower limit of a numerical range of a certain stage may be replaced with the upper or lower limit of a numerical range of another stage. In addition, in numerical ranges described in this specification, the upper or lower limit of that numerical range may be replaced with a value shown in an example.

[0013] As used herein, the term "polyol" refers to a compound having an average of more than one hydroxyl group in the molecule.

[0014] As used herein, the term "polyisocyanate" refers to a compound having an average of more than one isocyanate group in the molecule.

[0015] Unless otherwise specified, the materials exemplified below may be used alone or in combination of two or more. When the base agent or curing agent contains multiple substances corresponding to each component, the content of each component in the base agent or curing agent means the total amount of the multiple substances present in the base agent or curing agent, unless otherwise specified.

[0016] The base agent contains a urethane prepolymer (hereinafter sometimes referred to as "component (a)"). The curing agent contains a polyol (hereinafter sometimes referred to as "component (b)"). At least one of the base agent and the curing agent contains a filler (hereinafter sometimes referred to as "component (c)"). At least one of the base agent and the curing agent may further contain a curing catalyst (hereinafter sometimes referred to as "component (d)"), carbon black (hereinafter sometimes referred to as "component (e)"), a plasticizer (hereinafter sometimes referred to as "component (f)"), other additives, etc. Each component will be explained below.

[0017] (a) Component: urethane prepolymer The component (a) is a reaction product of a compound having two or more active hydrogen groups (hereinafter sometimes referred to as the “component (a-1)”) and a polyisocyanate compound having two or more isocyanate groups (hereinafter sometimes referred to as the “component (a-2)”). The component (a) is preferably a urethane prepolymer having an isocyanate group (as a terminal group). A urethane prepolymer having an isocyanate group as a terminal group can be obtained by reacting the component (a-1) with the component (a-2) so that the number of isocyanate groups is in excess. By using two or more types of the component (a-1) and the component (a-2), multiple components (a) may be present as the reaction product. Examples of active hydrogen groups include hydroxyl groups (OH groups), carboxyl groups (COOH groups), amino groups (NH groups), and mercapto groups (SH groups). The active hydrogen group may be a hydroxyl group (OH group). The reaction product of the components (a-1) and (a-2) may be obtained by reacting them in the reaction system and then isolating the product before use, or may be used as is without isolation.

[0018] The component (a-1) may be a compound having two or more hydroxyl groups (OH groups), or may be a compound having three or more hydroxyl groups (OH groups). The component (a-1) may contain, for example, a polyether polyol. The polyether polyol is not particularly limited, but examples thereof include polyethylene glycol (PEG), polypropylene glycol (PPG), ethylene oxide / propylene oxide copolymer, polytetramethylene ether glycol (PTMEG), sorbitol-based polyol, ethylenediamine propylene oxide modified product, and ethylenediamine ethylene oxide / propylene oxide modified product. Among these, the polyether polyol may contain, for example, polypropylene glycol (PPG).

[0019] The number average molecular weight of component (a-1) may be 20,000 or less, or may be 18,000 or less, 15,000 or less, or 12,000 or less. When the number average molecular weight of component (a-1) is 20,000 or less, the number of crosslinking points increases, and mechanical properties upon curing tend to improve. The number average molecular weight of component (a-1) is not particularly limited, but may be, for example, 500 or more.

[0020] In this specification, the term "number average molecular weight" is calculated using gel permeation chromatography (GPC) and a calibration curve of standard polystyrene. The GPC measurement conditions are, for example, as follows. Measurement equipment: ACQUITY UPLC APC system (Waters) Columns: APC XT-900, APC XT-200, APC XT-125, APC XT-45 (Waters) Carrier: tetrahydrofuran (THF) Detector: Differential refractive index detector Sample: 0.5% by mass THF solution Calibration curve: Polystyrene

[0021] Examples of component (a-2) include aromatic polyisocyanates in which an isocyanate group is bonded to an aromatic hydrocarbon, alicyclic polyisocyanates in which an isocyanate group is bonded to an alicyclic hydrocarbon, and aliphatic polyisocyanates in which an isocyanate group is bonded to an aliphatic hydrocarbon. Among these, component (a-2) may be an aromatic polyisocyanate, such as diphenylmethane diisocyanate. Examples of diphenylmethane diisocyanates include 4,4'-diphenylmethane diisocyanate (4,4'-MDI) and 2,4'-diphenylmethane diisocyanate (2,4'-MDI).

[0022] When component (a-1) and component (a-2) are reacted to obtain component (a), a catalyst for forming a urethane prepolymer (hereinafter sometimes referred to as "component (a-3)") may be used as needed. Component (a-3) can be a known catalyst that promotes a urethanization reaction or a urea reaction, such as component (d) (curing catalyst) described below. Component (a-3) may be, for example, a tin-based catalyst, such as dibutyltin dilaurate.

[0023] The content of the (a-3) component can be adjusted appropriately depending on the type of the (a-1) component, the type of the (a-2) component, etc. The content of the (a-3) component may be, for example, 0.001 to 5 mass%, 0.005 to 1 mass%, or 0.01 to 0.1 mass% based on the total amount of the (a-1) component and the (a-2) component.

[0024] The content of component (a) (the sum of components (a-1), (a-2), and (a-3)) may be 20 to 70 mass%, 30 to 60 mass%, or 35 to 55 mass% based on the total amount of the base agent. When the content of component (a) is 20 mass% or more based on the total amount of the base agent, it tends to be possible to prevent a decrease in elongation during curing, and when it is 70 mass% or less, it tends to be possible to prevent a decrease in adhesive properties after curing (after curing).

[0025] The content of component (a) (total of components (a-1), (a-2), and (a-3)) may be 5 to 35 mass%, 10 to 30 mass%, or 15 to 25 mass%, based on the total amount of base agent and curing agent. When the content of component (a) is 5 mass% or more based on the total amount of base agent and curing agent, a decrease in elongation during curing tends to be prevented, and when it is 35 mass% or less, a decrease in adhesive properties after curing (after curing) tends to be prevented.

[0026] (b) Component: Polyol The component (b) is not particularly limited as long as it is a compound having two or more hydroxyl groups (OH groups). The component (b) may be a combination of multiple components having different numbers of hydroxyl groups (OH groups). Examples of the component (b) include the same compounds as the component (a-1) above. The component (b) may contain, for example, a polyether polyol. The polyether polyol may contain, for example, polypropylene glycol (PPG). The polyether polyol may contain, for example, an ethylenediamine propylene oxide modified product.

[0027] The number average molecular weight of component (b) may be 20,000 or less, 18,000 or less, 15,000 or less, or 12,000 or less. The number average molecular weight of component (b) may be, for example, 1,000 or more.

[0028] When component (b) contains a compound having two hydroxyl groups (OH groups) and a compound having three or more hydroxyl groups (OH groups), the content of the compound having two hydroxyl groups (OH groups) may be 0% by mass or more, 10% by mass or more, or 20% by mass or more, and 50% by mass or less, 40% by mass or less, or 30% by mass or less, based on the total amount of component (b). The content of the compound having three or more hydroxyl groups (OH groups) may be 50% by mass or more, 60% by mass or more, or 70% by mass or more, and 100% by mass or less, 90% by mass or less, or 80% by mass or less, based on the total amount of component (b).

[0029] The content of component (b) may be 20 to 60 mass%, 25 to 55 mass%, or 30 to 50 mass%, based on the total amount of curing agent. When the content of component (b) is 20 mass% or more, based on the total amount of curing agent, it tends to be possible to prevent a decrease in flexibility of the adhesive composition during curing, and when the content of component (b) is 60 mass% or less, based on the total amount of curing agent, it tends to be possible to prevent a decrease in strength during curing.

[0030] The content of component (b) may be 5 to 35 mass%, 10 to 30 mass%, or 15 to 25 mass%, based on the total amount of base agent and curing agent. When the content of component (b) is 5 mass% or more, based on the total amount of base agent and curing agent, a decrease in flexibility of the adhesive composition during curing tends to be prevented, and when it is 35 mass% or less, a decrease in strength during curing tends to be prevented.

[0031] (c) Ingredient: Filler The component (c) contains particles (hereinafter sometimes referred to as the “component (c-1)”) composed of a layered compound. The component (c) may contain, in addition to the component (c-1), particles other than the component (c-1) (hereinafter sometimes referred to as the “component (c-2)”). When the component (c) contains the component (c-1), it becomes possible to form a cured product of the adhesive composition that is less likely to cause substrate surface failure in a high-temperature environment. The reason for this effect is not entirely clear, but the inventors believe that when a crack occurs in the adhesive layer due to shear applied to the substrate in a high-temperature environment (e.g., 90°C), stress near the tip of the crack causes, for example, cleavage between layers of the component (c-1) in the adhesive layer, creating a defect, and the crack propagates to the defect, making it more likely that cohesive failure of the adhesive layer will progress than substrate surface failure.

[0032] (c-1) Component: Particles composed of layered compounds A layered compound refers to a substance (simple substance or compound) having a layered crystal structure. The layered compound may have a layered structure in which unit layers formed by relatively strong bonds such as covalent bonds or ionic bonds are stacked via relatively weak intermolecular forces such as van der Waals forces. Component (c-1) may be, for example, scale-like particles composed of the layered compound.

[0033] Examples of the layered compound include graphite, boron nitride, and layered silicate minerals such as mica, smectite, talc, kaolin, pyrophyllite, and sericite. The layered compound may be, for example, graphite or mica.

[0034] The average particle size of component (c-1) (D50: particle size at 50% of the volume particle size distribution curve) may be, for example, 0.1 to 50 μm, and may be 1 μm or more, 5 μm or more, 10 μm or more, 15 μm or more, or 20 μm or more, and may be 40 μm or less, 30 μm or less, 25 μm or less, 20 μm or less, 15 μm or less, or 10 μm or less. A relatively large average particle size of component (c-1) tends to make it easier to obtain a cured adhesive composition that is less susceptible to substrate surface damage, while a relatively small average particle size of component (c-1) tends to provide excellent shear strength when bonding substrates together. The average particle size of component (c-1) can be measured, for example, by laser diffraction light scattering using a particle size distribution analyzer.

[0035] The content of component (c-1) may be 30 to 70 mass%, 40 to 65 mass%, or 50 to 60 mass%, based on the total amount of component (c). When the content of component (c-1) is within the above range, an adhesive composition that is less likely to cause damage to the surface of the substrate tends to be obtained.

[0036] The content of component (c-1) may be 3 to 8 volume %, 3.5 to 7.5 volume %, or 4 to 7 volume %, based on the total volume of the base material and curing agent. By having the content of component (c-1) in the above range, it tends to be easier to obtain an adhesive composition that is less likely to cause damage to the surface of the substrate.

[0037] (c-2) component: particles other than (c-1) component Component (c-2) is a filler that does not fall under component (c-1) (particles composed of layered compounds). Examples of component (c-2) include particles composed of calcined clay (calcined layered silicate minerals such as calcined kaolin), silica, glass, magnesium hydroxide, aluminum hydroxide, antimony trioxide, barium sulfate, zinc borate, alumina, magnesia, titania, etc. Component (c-2) may be, for example, particles composed of calcined kaolin.

[0038] The content of the component (c-2) may be 30 to 70 mass %, 35 to 60 mass %, or 40 to 50 mass % based on the total amount of the component (c).

[0039] The content of component (c) (the sum of components (c-1) and (c-2)) may be 5 to 35 mass%, 10 to 30 mass%, or 15 to 25 mass%, based on the total amount of the base material and curing agent. When the content of component (c) is within the above range, an adhesive composition that is less likely to cause damage to the substrate surface tends to be obtained.

[0040] (d) Component: Curing catalyst As the component (d), for example, a known catalyst that promotes a urethanization reaction or a urea reaction can be used. Examples of the component (d) include tin-based catalysts and amine-based catalysts. Examples of the tin-based catalyst include dibutyltin dilaurate, dioctyltin dilaurate, dibutyltin didecate, dioctyltin didecate, and tin 2-ethylhexanoate. Examples of the amine catalyst include triethylenediamine, bis(dimethylaminoethyl)ether, di(N,N-dimethylaminoethyl)amine, and 1-isobutyl-2-methylimidazole. The component (d) can be appropriately selected according to the desired curing rate. The component (d) may be, for example, an amine-based catalyst, such as triethylenediamine.

[0041] The content of component (d) may be 0.01 to 5 mass%, 0.1 to 3 mass%, or 0.2 to 1 mass%, based on the total amount of the base agent and curing agent. When the content of component (e) is 0.01 mass% or more, based on the total amount of the base agent and curing agent, the curing reaction of the adhesive composition tends to be more sufficiently promoted. When the content of component (d) is 5 mass% or less, based on the total amount of the base agent and curing agent, the usable life of the adhesive composition tends to be more sufficiently ensured.

[0042] (e) Ingredient: Carbon black Component (e) may have an average particle size (D50: particle size at 50% of the volume particle size distribution curve) of 20 to 40 nm or 25 to 35 nm. When the average particle size of component (e) is within the above range, the viscosity of the adhesive composition and the dispersibility of component (e) are adjusted to more appropriate ranges, which tends to further improve the workability and strength of the adhesive composition. The average particle size (D50) of component (e) can be measured, for example, by laser diffraction light scattering using a particle size distribution analyzer.

[0043] Commercially available products of component (e) include, for example, Monarch 460 (manufactured by Cabot Corporation), Asahi Carbon 70 (manufactured by Asahi Carbon Co., Ltd.), Seast 3 (manufactured by Tokai Carbon Co., Ltd.), Mitsubishi Carbon 32 (manufactured by Mitsubishi Chemical Corporation), and Nitelon 200 (manufactured by Shin-Nichika Carbon Co., Ltd.).

[0044] The content of component (e) may be 8 to 30 mass%, 10 to 25 mass%, or 12 to 20 mass% based on the total amount of the base agent and curing agent. When the content of component (c-2) is 8 mass% or more based on the total amount of the base agent and curing agent, strength upon curing tends to be improved, and when it is 30 mass% or less, dispersibility is further improved, so strength upon curing tends to be maintained.

[0045] (f) Ingredient: Plasticizer Examples of component (f) include phthalate ester compounds, alkylsulfonate ester compounds, adipate ester compounds, trimellitate ester compounds, phosphate ester compounds, etc. Specific examples of phthalate ester compounds include dioctyl phthalate (DOP), dibutyl phthalate (DBP), diisononyl phthalate (DINP), diisodecyl phthalate (DIDP), butyl benzyl phthalate (cBP), etc.

[0046] The content of the component (f) may be 5 to 40 mass % or 10 to 30 mass % based on the total amount of the base resin and curing agent.

[0047] In addition to the above components (a) to (f), at least one of the base agent and the curing agent may further contain other additives such as an ultraviolet absorber, a dehydrating agent, a pigment, a dye, an antioxidant, an antioxidant, an antistatic agent, a flame retardant, an adhesion promoter, a dispersant, a solvent, etc. The amount of the other additives may be 0.01 to 20% by mass or 0.1 to 10% by mass based on the total amount of the base agent and the curing agent.

[0048] When the base agent and curing agent are mixed, the molar ratio (NCO / OH) of the isocyanate groups (NCO) in the base agent to the hydroxyl groups (OH) in the curing agent may be, for example, 1.0 to 5.0. When the equivalent ratio (NCO / OH) is 1.0 or higher, the proportion of unreacted polyol present when the base agent and curing agent are mixed is reduced, tending to provide sufficient non-primer adhesion. When the equivalent ratio (NCO / OH) is 5.0 or lower, the proportion of isocyanate and prepolymer present when the base agent and curing agent are mixed is within an appropriate range, which reduces the proportion of reaction with moisture in the air and tends to provide sufficient curing properties. The isocyanate groups in the base agent are primarily derived from component (a), and the hydroxyl groups in the curing agent are primarily derived from component (b).

[0049] The adhesive set of this embodiment can prepare an adhesive composition (a two-component curing urethane adhesive composition) by mixing the main component and the curing agent. The temperature and time for mixing the main component and the curing agent may be, for example, 10 to 35°C and 1 to 60 minutes.

[0050] The method for mixing the base agent and the curing agent is not particularly limited, and may be, for example, a method in which they are mixed by hand application using a normal caulking gun, or a method in which they are mixed using a mechanical rotary mixer, static mixer, or the like in combination with a metering pump (e.g., a gear pump, a plunger pump, or the like) and a throttle valve for feeding the raw materials.

[0051] The prepared adhesive composition (two-component curing urethane adhesive composition) can be cured to form a cured product, which can act as an adhesive layer for bonding substrates together. The conditions for curing the adhesive composition (curing conditions) may be, for example, 10 to 35°C, 30 to 60% RH (relative humidity), and 2 to 7 days.

[0052] In one embodiment, the structure includes a first substrate, a second substrate, and an adhesive layer that bonds the first substrate and the second substrate together. The adhesive layer contains a cured product of an adhesive composition that includes the base agent and curing agent in the adhesive set. Examples of structures that can be used include vehicle back doors, trunk lids, windshields, and spoilers.

[0053] At least one of the first substrate and the second substrate may be a polypropylene (PP) substrate, or both the first substrate and the second substrate may be a polypropylene (PP) substrate. Examples of substrates other than polypropylene (PP) substrates include plastic substrates such as polyvinyl chloride, acrylonitrile / butadiene / styrene copolymer (ABS), polycarbonate (PC), polyamide (PA), poly(methyl methacrylate) (PMMA), polyester, epoxy resin, polyurethane (PUR), polyoxymethylene (POM), polyethylene (PE), ethylene / propylene copolymer (EPM), and ethylene / propylene / diene polymer (EPDM); fiber-reinforced plastic substrates such as carbon fiber reinforced plastic (CFRP) and glass fiber reinforced plastic (GFRP); and resin compound substrates such as sheet molding compound (SMC). When the structure is a vehicle back door, the first substrate may be an inner panel made of a polypropylene substrate, and the second substrate may be an outer panel made of a substrate other than a propylene substrate.

[0054] A method for manufacturing a structure according to one embodiment includes bonding a first substrate and a second substrate together using an adhesive composition containing a base agent and a curing agent. A known method can be used to apply the adhesive composition containing a base agent and a curing agent to at least one of the first substrate or the second substrate. The temperature and time for mixing the base agent and the curing agent in the adhesive set, the conditions for curing the adhesive composition, and the like are the same as those described above. [Example]

[0055] The present disclosure will be described in more detail below with reference to examples, although the present disclosure is not limited to these examples.

[0056] [Preparation of main agent A-1] A kneading vessel equipped with a stirrer, a nitrogen inlet tube, a vacuum pump, and a heating / cooling device was charged with 100.0 parts by mass of EPL-S202 (polypropylene glycol, manufactured by Mitsui Chemicals, Inc., number average molecular weight: 12,000, number of hydroxyl groups: 3, symbol: a-1-(1)) as the component (a-1) of the component (a), 35.0 parts by mass of Monarch 460 (carbon black, manufactured by Cabot Corporation, symbol: (e)-(1)) as the component (e), 50.0 parts by mass of Iceberg (calcined kaolin, manufactured by Shiraishi Calcium Co., Ltd., symbol: c-2-(1)) as the component (c-2) of the component (c), and 45.0 parts by mass of DINP (diisononyl phthalate, symbol: f-(1)) as the component (f), and the mixture was stirred at room temperature (25°C) for 60 minutes until no lumps of component (e) remained. Next, the kneading vessel was heated until the contents reached 100 ° C., and the pressure inside the kneading vessel was reduced to 2.7 kPa (20 mmHg) using a vacuum pump, and the contents were stirred for 1 hour. Next, the temperature of the contents was cooled to 40 ° C., and 10.0 parts by mass of Millionate MT (4,4'-diphenylmethane diisocyanate, manufactured by Tosoh Corporation, NCO content: 33.6%, symbol: a-2-(1)) was added to the kneading vessel as the (a-2) component in the (a) component, and 0.02 parts by mass of KS-1260 (tin catalyst, dibutyltin dilaurate, manufactured by Sakai Chemical Industry Co., Ltd., symbol: a-3-(1)) was added as the (a-3) component in the (a) component, and nitrogen was introduced. The contents were heated to 70 ° C., and the contents were stirred for 1 hour. The temperature of the contents was cooled to 40 ° C. and stirred for 30 minutes. The viscous material obtained through the above steps was designated as base component A-1. It is presumed that the viscous material contains a urethane prepolymer, which is a reaction product of a-1-(1) and a-2-(1).

[0057] [Table 1]

[0058] [Preparation of Curing Agent B-1] A mixing vessel equipped with a stirrer, a nitrogen inlet tube, a vacuum pump, and a heating / cooling device was charged with 84.0 parts by mass of EPL-S201 (polypropylene glycol, manufactured by Mitsui Chemicals, Inc., number average molecular weight: 10,000, number of hydroxyl groups: 3, symbol: b-(1)), 28.0 parts by mass of DL-4000 (polypropylene glycol, manufactured by Mitsui Chemicals, Inc., number average molecular weight: 4,000, number of hydroxyl groups: 2, symbol: b-(2)), and 28.0 parts by mass of EDP-1100 (ethylenediamine propylene glycol, manufactured by Mitsui Chemicals, Inc., number average molecular weight: 10,000, number of hydroxyl groups: 2, symbol: b-(3)) as component (b). 2.0 parts by mass of modified side (manufactured by ADEKA Corporation, number of hydroxyl groups: 4, symbol: b-(3)), 60.0 parts by mass of CPB (graphite, manufactured by Nippon Graphite Industries Co., Ltd., average particle size: 22 μm, symbol: c-1-(1)) as component (c-1) in component (c), 40.0 parts by mass of Monarch 460 (same as above) as component (e), and 36.1 parts by mass of DINP (same as above) as component (f) were charged and stirred at room temperature (25 ° C) for 30 minutes until lumps of component (e) disappeared. Next, the kneading vessel was heated to 100 ° C, and the pressure inside the kneading vessel was reduced to 2.7 kPa (20 mmHg) using a vacuum pump, and the contents were stirred for 1 hour. The contents were cooled to 40°C, and 0.3 parts by mass of BHT (dibutylhydroxytoluene, symbol: g-(1)) as component (g) (ultraviolet absorber), 1.0 part by mass of dehydrating molecular sieve 4A (symbol: h-(1)) as component (h) (dehydrating agent), and 2.1 parts by mass of TEDA (triethylenediamine, amine catalyst, manufactured by Tosoh Corporation, symbol: d-(1)) as component (d) were added and stirred for 30 minutes. The viscous material obtained through the above process was designated Curing Agent B-1. Table 2 shows the formulation of Curing Agent B-1.

[0059] [Preparation of Curing Agent B-2] Curing agent B-2 was prepared in the same manner as curing agent B-1, except that 60.0 parts by mass of CPB was replaced with 60.0 parts by mass of M-XF (mica, manufactured by Repco Co., Ltd., average particle size: 4 μm, symbol: c-1-(2)) as component (c-1) in component (c). Table 2 shows the formulation of curing agent B-2.

[0060] [Preparation of curing agent b-1] Curing agent b-1 was prepared in the same manner as curing agent B-1, except that 60.0 parts by mass of CPB was replaced with 60.0 parts by mass of Iceberg (same as above) as component (c-2) in component (c), and 28.0 parts by mass of DL-4000 was replaced with 14.0 parts by mass of DL-4000. Table 2 shows the formulation of curing agent b-1.

[0061] [Table 2]

[0062] [Preparing adhesive sets] Example 1 The above-mentioned base agent A-1 was used as the base agent in Example 1. The above-mentioned curing agent B-1 was used as the curing agent in Example 1. In the following evaluations, the base agent A-1:curing agent B-1 were used in a mass ratio of 1:1 (the molar ratio of NCO groups in the base agent to OH groups in the curing agent (NCO groups / OH groups) = 1.24).

[0063] Example 2 The above-mentioned base agent A-1 was used as the base agent in Example 2. The above-mentioned curing agent B-2 was used as the curing agent in Example 2. In the following evaluations, the base agent A-1:curing agent B-2 were used in a mass ratio of 1:1 (the molar ratio of NCO groups in the base agent to OH groups in the curing agent (NCO groups / OH groups) = 1.24).

[0064] (Comparative Example 1) The above-mentioned main agent A-1 was used as the main agent in Comparative Example 1. The above-mentioned curing agent b-1 was used as the curing agent in Comparative Example 1. In the following evaluations, the main agent A-1:curing agent b-1 were used in a mass ratio of 1:1 (the molar ratio of NCO groups in the main agent to OH groups in the curing agent (NCO groups / OH groups) = 1.38).

[0065] [Shear strength measurement] Two substrates made primarily of flame-treated polypropylene (PP) were prepared, and an arbitrary urethane primer was applied to the adhesive surface of the substrate. The base material and curing agent of Examples 1 and 2 and Comparative Example 1 were mixed in the above mass ratio, and the resulting adhesive composition was applied to one of the substrates so that the adhesive layer was 3 mm thick, and the adhesive area was 250 mm. 2 The laminate was then laminated to the surface of another substrate to form a 25 mm × 10 mm square, followed by pressure bonding to obtain a laminate. The resulting laminate was cured at 23°C for 72 hours to obtain multiple test specimens for Examples 1 and 2 and Comparative Example 1, in which the substrates were bonded together via an adhesive layer containing the cured product of the adhesive composition. In the shear strength (breaking strength) tests described below, different test specimens were used for each condition.

[0066] (initial conditions) The obtained test specimens were subjected to a tensile test in accordance with JIS K6850:1999 at 23° C. to determine the shear strength (breaking strength). The results are shown in Table 3.

[0067] (High temperature (90℃) conditions) The obtained specimens were heated at 90°C for 1 hour and then subjected to a tensile test under the same conditions as the initial test at 90°C to determine the shear strength (breaking strength). After the test (after fracture in the tensile test), the specimens were observed and evaluated for fracture state based on the following evaluation criteria. The results are shown in Table 3.

[0068] FIG. 1 is a schematic diagram showing the failure state of a test specimen after an adhesion test. FIG. 1(a) is a schematic cross-sectional view showing the test specimen before the adhesion test. The test specimen 10 shown in FIG. 1(a) includes substrates 2a and 2b and an adhesive layer 1 bonding these substrates together before the adhesion test. FIG. 1(b) is a schematic cross-sectional view showing the failure state of the test specimen as cohesive failure (hereinafter, sometimes referred to as "CF"). When CF occurs, the test specimen 10 is torn inside the adhesive layer 1, as shown in FIG. 1(b). FIG. 1(c) is a schematic cross-sectional view showing the failure state of the test specimen as interfacial failure (hereinafter, sometimes referred to as "AF"). When AF occurs, the test specimen 10 is torn at the interface between the substrate 2a and the adhesive layer 1 (or the interface between the substrate 2b and the adhesive layer 1), as shown in FIG. 1(c). FIG. 1(d) is a schematic cross-sectional view showing the failure state of the test specimen as substrate surface failure (substrate cohesive failure) (hereinafter, sometimes referred to as "TSF"). When TSF occurs, as shown in FIG. 1(d), the specimen 10 is divided inside the substrate 2a (or inside the substrate 2b), and the surface layer of the substrate 2a (or the surface layer of the substrate 2b) is destroyed. The destruction of the specimen 10 usually occurs as a combination of these types of destruction (CF, AF, TSF, etc.). In this test, the destruction area caused by each type of destruction was observed and the evaluation was performed by determining the area ratio of each type of destruction. For example, in Table 3, "CF84TSF16" means that 84% of the destruction area was caused by CF and 16% of the destruction area was caused by TSF. In this test, the larger the ratio of the destruction area caused by CF to the destruction area, the more the destruction of the substrate can be suppressed, and therefore, it can be said that the substrate surface destruction is less likely to occur.

[0069] [Table 3]

[0070] As shown in Table 3, the cured products of the adhesive compositions prepared from the adhesive sets of Examples 1 and 2, which contained component (c-1) as component (c), had a smaller area proportion resulting from substrate surface failure in the test specimens after shear strength measurements under high-temperature (90°C) conditions than the cured product of the adhesive composition prepared from the adhesive set of Comparative Example 1, which did not contain component (c-1) as component (c). These results confirmed that the adhesive set of the present disclosure is capable of forming a cured product of an adhesive composition that is less likely to cause substrate surface failure in high-temperature environments.

[0071] Figure 2 shows SEM (scanning electron microscope) images of the adhesive layer of the test specimen of Example 1. Figure 2(a) is an image of the cut surface of the adhesive layer observed by SEM when the adhesive layer of the test specimen of Example 1 was cut at an arbitrary location and the substrates were separated before shear strength measurement, and Figure 2(b) is an image of the cohesive failure surface of the adhesive layer of the test specimen of Example 1 observed by SEM after shear strength measurement under high temperature (90°C) conditions. The SEM images were taken using a low-vacuum SEM (low-vacuum scanning electron microscope (TM3030Plus), manufactured by Hitachi High-Technologies Corporation).

[0072] When the adhesive layer of the specimen of Example 1 was cut at an arbitrary location to separate the substrates, a moderate proportion of graphite (c-1) (the area indicated by the double arrow in FIG. 2(a)) was exposed, as shown in FIG. 2(a). In contrast, the cohesive failure surface of the adhesive layer of the specimen of Example 1 after fracture in a tensile test under high temperature (90°C) conditions, as shown in FIG. 2(b), had a large amount of graphite (c-1) (the area indicated by the double arrow in FIG. 2(b)) exposed. This supports the idea that cohesive failure of the adhesive layer was promoted starting from the (c-1) component, and it is speculated that the inclusion of the (c-1) component in the (c) component suppressed the occurrence of substrate surface failure, promoting cohesive failure. [Explanation of symbols]

[0073] 1...adhesive layer, 2a, 2b...substrate, 10...test specimen.

Claims

1. An adhesive set including a base agent and a curing agent, The base material contains a urethane prepolymer, the curing agent contains a polyol, At least one of the base agent and the curing agent contains a filler, The filler includes particles composed of a layered compound. Adhesive set.

2. a first substrate; a second substrate; and an adhesive layer that bonds the first substrate and the second substrate to each other; Equipped with The adhesive layer contains a cured product of an adhesive composition comprising the base agent and the curing agent in the adhesive set according to claim 1. structure.

3. A method for manufacturing the structure according to claim 2, comprising: a step of bonding the first substrate and the second substrate together via an adhesive composition containing the base agent and the curing agent, Method for manufacturing the structure.

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