Adhesive set and adherend

Abstract

To provide a two-pack type adhesive which has sufficient curability at room temperature even in the presence of oxygen, and suppresses liquid sagging when being coated onto the adherend.SOLUTION: An adhesive set includes a first liquid containing one or more kinds of acrylic monomers having two or more (meth)acryloyl groups, and an epoxy resin having two or more epoxy groups, and a second liquid containing a curing agent containing a compound having a nucleophilic reactive group reactive with both the epoxy group and the (meth)acryloyl groups. The acrylic monomer contains a bifunctional acrylic monomer having two (meth)acryloyl groups. A ratio of the bifunctional acrylic monomer to the total mass of the acrylic monomer is 75 mass% or more.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to an adhesive set and an adherend.

Background Art

[0002] Conventionally, as a type of adhesive, a two-component adhesive using a (meth)acrylic monomer has been known (for example, Patent Document 1). In the case of a conventional two-component adhesive using a (meth)acrylic monomer, generally, the polymerization of the (meth)acrylic monomer proceeds by a redox catalyst system formed of a polymerization initiator and a reducing agent, and as a result, the adhesive cures.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] One aspect of the present invention provides a two-component adhesive that has sufficient curability at room temperature even in the presence of oxygen and suppresses dripping when applied to an adherend.

Means for Solving the Problems

[0005] One aspect of the present invention provides an adhesive set including a first liquid containing one or more acrylic monomers having two or more (meth)acryloyl groups and an epoxy resin having two or more epoxy groups, and a second liquid containing a curing agent including a compound having a nucleophilic reactive group that reacts with both an epoxy group and a (meth)acryloyl group. The acrylic monomer includes a bifunctional acrylic monomer having two (meth)acryloyl groups, and the ratio of the bifunctional acrylic monomer to the total mass of the acrylic monomer is 75% by mass or more.

Effects of the Invention

[0006] According to one aspect of the present invention, there is provided a two-component adhesive that has sufficient curability at room temperature even in the presence of oxygen and suppresses dripping when applied to an adherend. The adhesive set according to one aspect of the present invention can have excellent characteristics also in terms of good dischargeability from a nozzle or the like and a sufficiently long pot life.

Brief Description of the Drawings

[0007]

Figure 1

Embodiments for Carrying Out the Invention

[0008] Hereinafter, embodiments of the present invention will be described. However, the present invention is not limited to the following embodiments. In this specification, (meth)acryloyl means acryloyl or methacryloyl, and the same applies to other similar expressions.

[0009] An adhesive set according to one embodiment is a two-component adhesive composed of a first liquid and a second liquid. The first liquid contains one or more acrylic monomers having two or more (meth)acryloyl groups and an epoxy resin having two or more epoxy groups. The second liquid contains a curing agent containing a compound having a nucleophilic reactive group that reacts with both an epoxy group and a (meth)acryloyl group.

[0010] The acrylic monomer is a bifunctional or higher-functional compound having an acryloyl group, a methacryloyl group, or both. The number of (meth)acryloyl groups possessed by the acrylic monomer may be 2 to 4.

[0011] The acrylic monomer contained in the first liquid is mainly composed of a bifunctional acrylic monomer having two (meth)acryloyl groups. Specifically, the proportion of the bifunctional acrylic monomer with respect to the total mass of the acrylic monomer contained in the first liquid is 75% by mass or more. The proportion of the bifunctional acrylic monomer with respect to the total mass of the acrylic monomer may be 76% by mass or more, 77% by mass or more, 78% by mass or more, 79% by mass or more, 80% by mass or more, 81% by mass or more, 82% by mass or more, 83% by mass or more, 84% by mass or more, 85% by mass or more, 86% by mass or more, 87% by mass or more, 88% by mass or more, 89% by mass or more, 90% by mass or more, 91% by mass or more, 92% by mass or more, 93% by mass or more, 94% by mass or more, 95% by mass or more, 96% by mass or more, 97% by mass or more, 98% by mass or more, 99% by mass or more, or 100% by mass from the viewpoint of a long pot life and the like.

[0012] The bifunctional acrylic monomer may be, for example, a poly(meth)acrylate of an aliphatic polyol. Examples of the poly(meth)acrylate of an aliphatic polyol include diethylene glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, tripropylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, and polyethylene polypropylene glycol di(meth)acrylate. Other examples of the bifunctional acrylic monomer include 2,2'-di(meth)acryloyloxydiethyl phosphate, ethylene oxide-modified di(meth)acrylate phosphate, urethane acrylate, and epoxy acrylate. Examples of commercially available products of urethane acrylate include EBECRYL230 (Daicel Ornex). Examples of commercially available products of epoxy acrylate include EBECRYL230 (Daicel Ornex). These bifunctional acrylic monomers can be used alone or in combination of two or more.

[0013] The acrylic monomer may have two or more (meth)acryloyl groups and an epoxy group. In the present specification, a compound having two or more (meth)acryloyl groups and one or more epoxy groups is classified as a bifunctional or polyfunctional acrylic monomer based on the number of (meth)acryloyl groups. The bifunctional acrylic monomer may be a compound having two (meth)acryloyl groups and no epoxy group.

[0014] In addition to the bifunctional acrylic monomer, the first liquid may further contain a polyfunctional acrylic monomer having three or more (meth)acryloyl groups. Examples of the polyfunctional acrylic monomer include trifunctional (meth)acrylic monomers such as trimethylolpropane tri(meth)acrylate and pentaerythritol tri(meth)acrylate, and tetrafunctional (meth)acrylic monomers such as ditrimethylolpropane tetra(meth)acrylate.

[0015] The first liquid may further contain a monofunctional acrylic monomer having one (meth)acryloyl group. The proportion of the monofunctional acrylic monomer may be 0 to 10% by mass, 0 to 5% by mass, 0 to 2% by mass, or 0 to 1% by mass with respect to the total amount of the bifunctional acrylic monomer and the polyfunctional acrylic monomer.

[0016] The epoxy resin may be a bifunctional or higher epoxy resin. The number of epoxy groups in the epoxy resin may be 2 to 4.

[0017] Examples of epoxy resins include diglycidyl ether type epoxy resins such as bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol AD type epoxy resin, bisphenol S type epoxy resin, and hydrogenated bisphenol A type epoxy resin; novolac type epoxy resins such as phenol novolac type epoxy resin and cresol novolac type epoxy resin; biphenyl type epoxy resins such as biphenyl type epoxy resin and biphenyl aralkyl type epoxy resin; glycidyl ester type epoxy resin which is a reaction product of polybasic acid (for example, phthalic acid, dimer acid) and epichlorohydrin; glycidyl amine type epoxy resin which is a reaction product of amine compound (for example, p-aminophenol, diaminodiphenylmethane, isocyanuric acid) and epichlorohydrin; and aliphatic epoxy resin.

[0018] The epoxy resin may further have a (meth)acryloyl group. In this specification, a compound having two or more epoxy groups and one (meth)acryloyl group is classified as an epoxy resin. The epoxy resin may be a compound having two or more epoxy groups and no (meth)acryloyl group.

[0019] The first liquid may further contain a monofunctional acrylic monomer having one (meth)acryloyl group, a monofunctional epoxy resin having one epoxy group, or both of them.

[0020] The content of the acrylic monomer having two or more (meth)acryloyl groups in the first liquid is 10 to 90% by mass, 20 to 80% by mass, 30 to 70% by mass, or 40 to 60% with respect to the total amount of the acrylic monomer having two or more (meth)acryloyl groups and the epoxy resin having two or more epoxy groups. The total amount of the acrylic monomer having two or more (meth)acryloyl groups and the epoxy resin having two or more epoxy groups may be 50 to 100% by mass, 60 to 100% by mass, 70 to 100% by mass, 80 to 100% by mass, 85 to 100% by mass, or 90 to 100% with respect to the amount of the first liquid.

[0021] The curing agent contained in the second liquid is a component that cures the mixture (adhesive) of the first liquid and the second liquid by reacting with an epoxy resin, an acrylic monomer, or both. The curing agent includes at least a compound having a nucleophilic reactive group that reacts with both an epoxy group and a (meth)acryloyl group. This compound may have 2 to 4, or 2 to 3 nucleophilic reactive groups.

[0022] The nucleophilic reactive group may be, for example, an aliphatic amino group or a thiol group. From the viewpoint of reactivity with a (meth)acryloyl group, the nucleophilic reactive group may be an aliphatic amino group. Examples of compounds having an aliphatic amino group include aliphatic amine compounds having two or more primary aliphatic amino groups, such as 1,3-bis(aminomethyl)cyclohexane and 1,6-hexanediamine. Examples of commercially available products of compounds having an aliphatic amino group include jER Cure 3080 (manufactured by Mitsubishi Chemical Corporation, trade name).

[0023] The curing agent contained in the second liquid may further contain a compound that reacts substantially only with the epoxy resin. Examples of such a compound include aromatic amine compounds.

[0024] The content of the compound having a nucleophilic reactive group in the second liquid may be 30 to 100% by mass, 40 to 100% by mass, 50 to 100% by mass, 60 to 100% by mass, 70 to 100% by mass, 80 to 100% by mass, 85 to 100% by mass, or 90 to 100% by mass with respect to the amount of the second liquid.

[0025] The first liquid, the second liquid, or both may further contain an inorganic filler. By blending the inorganic filler, dripping of the liquid when applied to the adherend can be more effectively suppressed. Examples of the inorganic filler include silica particles, calcium carbonate particles, and glass beads. The silica particles may be, for example, unmodified silica fillers or silica fillers chain-modified with an alkyl chain or a (meth)acryloyl group or the like.

[0026] The content of the inorganic filler in the first liquid may be 0 to 30% by mass, 0 to 20% by mass, or 0 to 15% by mass based on the amount of the first liquid. The content of the inorganic filler in the second liquid may be 0 to 30% by mass, 0 to 20% by mass, or 0 to 15% by mass based on the amount of the second liquid. The content of the inorganic filler in the first liquid and the content of the inorganic filler in the second liquid may be the same or different.

[0027] The first liquid, the second liquid, or both of them may further contain a silane coupling agent. The silane coupling agent may be, for example, a compound having a hydrolyzable silyl group and a functional group that reacts with at least one of an acrylic monomer, an epoxy resin, or a curing agent. The hydrolyzable silyl group may be, for example, a group having a silicon atom and 1 to 3 alkoxy groups bonded to the silicon atom. The carbon number of the alkoxy group bonded to the silicon atom may be, for example, 1 to 4. Examples of the functional group that reacts with at least one of the acrylic monomer or the epoxy resin include amino groups such as primary amino groups and secondary amino groups, epoxy groups, mercapto groups, and (meth)acryloyl groups. In this specification, a compound having a hydrolyzable silyl group and a (meth)acryloyl group is classified as a silane coupling agent.

[0028] Specific examples of the silane coupling agent include 3-glycidoxypropyltrimethoxysilane and 3-aminopropyltrimethoxysilane.

[0029] As commercially available products of the silane coupling agent, for example, KBM-303, KBM-402, KBM-403, KBE-402, KBE-403, KBM-4803, KBM-502, KBM-503, KBE-502, KBE-503, KBM-5103, KBM-5803, KBM-602, KBM-603, KBM-903, KBE-903, KBE-9103P, KBM-573, KBM-575, KBM-802, and KBM-803 (the above are trade names of Shin-Etsu Chemical Co., Ltd.) are available.

[0030] The content of the silane coupling agent in the first liquid may be 0 to 5% by mass, or 0 to 3% by mass, based on the amount of the first liquid. The content of the silane coupling agent in the second liquid may be 0 to 5% by mass, or 0 to 3% by mass, based on the amount of the second liquid.

[0031] The first liquid, the second liquid, or both of them may further contain other components as needed. Examples of other components include pigments (e.g., carbon black, titanium oxide particles), and elastomers.

[0032] The elastomer may be, for example, a triblock copolymer of methyl methacrylate-butyl acrylate-methyl methacrylate, an acrylate polymer with acrylate groups at both ends, or a combination thereof. The content of the elastomer may be 10 to 50% by mass, or 20 to 40% by mass, based on the total amount of one or more acrylic monomers having two or more (meth)acryloyl groups, an epoxy resin, a compound having a nucleophilic reactive group that reacts with both epoxy groups and (meth)acryloyl groups, and the elastomer.

[0033] Only one of the first liquid or the second liquid may contain a pigment. Or, both the first liquid and the second liquid may contain a pigment, and in that case, the pigment contained in the first liquid and the pigment contained in the second liquid may be different. When the adhesive set contains a pigment in this way, the mixing state of the first liquid and the second liquid can be visualized when the first liquid and the second liquid are mixed. By making the mixed liquid of the first liquid and the second liquid in a mixing state where the pigment is sufficiently uniformly dispersed, a more excellent adhesive force tends to be obtained.

[0034] The adhesive set exemplified above is used to bond adherends to each other with an adhesive that is a mixture of a first liquid and a second liquid, so as to obtain a desired adherend having two or more adherends and an adhesive layer that bonds these adherends. FIG. 1 is a cross-sectional view showing an embodiment of the adherend. The adherend 30 shown in FIG. 1 has two adherends 11, 12 and an adhesive layer 20 that is interposed between the two adherends 11, 12 and bonds these adherends. The adhesive layer 20 can be a cured product formed from the adhesive set according to the above-described embodiment.

[0035] The adherend may be, for example, a molded body of a metal such as steel, iron, copper, brass, aluminum, stainless steel, a resin, or a carbon fiber reinforced plastic (CFRP). The two or more adherends can be molded bodies of the same or different materials from each other.

[0036] A method for obtaining an adherend having two adherends using the adhesive set includes, for example, arranging the two adherends with a gap therebetween, injecting the first liquid and the second liquid into the gap between the two adherends, and curing the adhesive that is a mixture of the first liquid and the second liquid. The first liquid and the second liquid may be mixed substantially simultaneously with being injected into the gap between the two adherends, or may be injected between the two adherends after being mixed. The first liquid and the second liquid, or a mixture thereof (adhesive), is injected between the two adherends using, for example, a mixing nozzle.

[0037] The method for obtaining the adherend may include applying an adhesive that is a mixture of the first liquid and the second liquid onto one adherend, bonding one adherend and the other adherend while sandwiching the applied adhesive therebetween, and then curing the adhesive. When the adhesive cures, an adhesive layer that is interposed between the two adherends and bonds these adherends is formed.

[0038] The mixing ratio of the first liquid and the second liquid is adjusted so that the adhesive cures appropriately in consideration of the stoichiometric ratio of the reaction between the acrylic monomer and the epoxy resin contained in the first liquid and the curing agent contained in the second liquid. For example, the volume ratio of the first liquid to the second liquid may be 0.5 to 5.0.

[0039] The curing conditions are adjusted so that the adhesive cures properly. For example, the adhesive may be cured in an environment of 10 to 40°C. The curing time is adjusted, for example, between 1 hour and 1 week. The adhesive may be heated, and in that case, the heating temperature may be, for example, 40 to 120°C.

Example

[0040] Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples.

[0041] 1. Preparation of Adhesive Set Using the following raw materials, the first liquid and the second liquid having the compositions shown in Table 1 or Table 2 were prepared. (1) Acrylic monomer (Bifunctional acrylic monomer) · 1,6 - hexanediol diacrylate (Product name: Biscoat 230, Shin-Nakamura Chemical Co., Ltd.) (Trifunctional acrylic monomer) · Trimethylolpropane triacrylate (Product name: TMPTA, Daicel - Ornex Co., Ltd.) (Tetrafunctional acrylic monomer) · Ditrimethylolpropane tetraacrylate (Product name: EBECRYL 140, Daicel - Ornex Co., Ltd.) (2) Epoxy resin · Bisphenol F type epoxy resin (Product name: EPICLON 830, DIC Corporation) (3) Curing agent · 1,3 - bis(aminomethyl)cyclohexane · Aliphatic amine - based curing agent (Product name: jER Cure 3080, Mitsubishi Chemical Corporation) (4) Filler (Inorganic filler) · Silica particles (Product name: Aerosil 200V, Nippon Aerosil Co., Ltd.) (5) Silane coupling agent · 3 - glycidyloxypropyltrimethoxysilane (Product name: KBM - 403, Shin-Etsu Chemical Co., Ltd.) · 3 - Aminopropyltrimethoxysilane (Product name: KBM - 903, Shin-Etsu Chemical Co., Ltd.) (6) Elastomer · Triblock copolymer of methyl methacrylate - butyl acrylate - methyl methacrylate (Product name: Clarite LA3320 or LA2140, Kuraray Co., Ltd.) · Both - ends acrylate polymer (Product name: XMAP RC110C or RC310C, Kaneka Corporation)

[0042] 2. Evaluation The adhesive sets were evaluated by the following methods. The evaluation results are shown in Table 1 and Table 2. (1) Dripping Using a static mixer, the first liquid and the second liquid were mixed at a volume ratio of 2:1, and the formed adhesive was applied onto a vertically - standing aluminum plate. The dripping state of the adhesive mixture after application was observed, and the time until dripping of 1.0 mm or more occurred from the time of application was measured. Based on the measurement results, each adhesive set was evaluated according to the following evaluation criteria. A: 30 minutes or more B: More than 10 minutes and less than 30 minutes C: Within 10 minutes

[0043] (2) Room - temperature curability Using a static mixer, the first liquid and the second liquid were mixed at a volume ratio of 2:1, and the formed adhesive was applied onto an aluminum plate. When the applied adhesive was cured at 25°C for 1 day in an air environment, it was visually confirmed whether the adhesive had cured or not. The adhesive for which curing was confirmed was judged as "A", and the adhesive for which curing was not confirmed was judged as "C".

[0044] (3) Pot life The first liquid and the second liquid were mixed at a volume ratio of 2:1 using a static mixer, and the formed adhesive was applied onto an aluminum plate. The applied adhesive was left standing at 25°C for 30 minutes. Thereafter, the adhesive was sandwiched between another aluminum plate, and the formed laminate was cured at 25°C for 3 days. After curing, the adhesive strength (shear strength) between the two aluminum plates was measured. A large shear strength means a large pot life. Based on the value of the shear strength, the pot life was determined according to the following criteria. A: The shear strength is 8 MPa or more B: The shear strength is 4 MPa or more and less than 8 MPa C: The shear strength is less than 4 MPa

[0045]

Table 1

[0046]

Table 2

Explanation of Symbols

[0047] 11, 12… adherends, 20… adhesive layer, 30… adherent.

Claims

1. A first liquid containing one or more acrylic monomers having two or more (meth)acryloyl groups and an epoxy resin having two or more epoxy groups, and A second liquid containing a curing agent containing a compound having a nucleophilic reactive group that reacts with both an epoxy group and a (meth)acryloyl group, The acrylic monomer includes a bifunctional acrylic monomer having two (meth)acryloyl groups, and the ratio of the bifunctional acrylic monomer to the total mass of the acrylic monomer is 75% by mass or more. An adhesive set.

2. The adhesive set according to claim 1, wherein the nucleophilic reactive group is an aliphatic amino group.

3. The adhesive set according to claim 1 or 2, wherein at least one of the first liquid and the second liquid further contains an inorganic filler.

4. The adhesive set according to any one of claims 1 to 3, wherein only one of the first liquid and the second liquid further contains a pigment.

5. The adhesive set according to any one of claims 1 to 4, wherein the first liquid and the second liquid each further contain a pigment, and the pigment contained in the first liquid is different from the pigment contained in the second liquid.

6. Having two or more adherends and an adhesive layer for adhering the two or more adherends, An adherend, wherein the adhesive layer is a layer formed by the adhesive set according to any one of claims 1 to 5.

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