One-component thermosetting liquid resin composition for metal adhesion

Abstract

To provide a one-component thermosetting liquid resin composition for metal adhesion which is usable as a one-component system at normal temperature, exhibits rapid curing after heating, has low viscosity, and provides a cured product excellent in flexibility and adhesive strength.SOLUTION: A one-component thermosetting liquid resin composition for metal adhesion contains a urethane(meth)acrylate (A), a phosphate ester (B), and a thermally decomposable organic peroxide (C), wherein the urethane(meth)acrylate (A) has a structural unit derived from a compound (a) having two or more isocyanate groups, a structural unit derived from a (meth)acrylate (b) having a hydroxy group, and a structural unit derived from a polyalkylene glycol (c) having a number-average molecular weight of 1500-3500, and the acrylic equivalent of the urethane(meth)acrylate (A) is 1000-4000 g / eq.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a one-component thermosetting liquid resin composition for bonding metals. [Background technology]

[0002] Epoxy resin adhesives are widely used as adhesives for metals. They are characterized by excellent heat resistance, water resistance, and durability. For example, Patent Document 1 discloses a heat-curable epoxy resin composition containing an epoxy resin obtained by condensing an epoxy group-containing alkoxysilicon compound in the presence of a basic catalyst, an epoxy resin having two or more epoxy groups, an imidazole compound, and a compound having a phenolic hydroxyl group, as an adhesive that can be cured in a short time at low temperatures, the cured product has excellent heat resistance, and can maintain good adhesive properties even under high-temperature and high-humidity conditions.

[0003] Demand for metal adhesives is increasing year by year, including the need for fast curing adhesives and applications to thin film substrates. For example, Patent Document 2 discloses an epoxy vinyl ester resin composition that is characterized by containing a β-diketone compound, an epoxy vinyl ester resin, a radically polymerizable unsaturated monomer, and a polymerization initiator as essential components, and that has excellent adhesive strength without generating unevenness or voids that cause poor adhesion of metal foil. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-199851 [Patent Document 2] Japanese Patent Application Laid-Open No. 2003-105039 Summary of the Invention [Problem to be solved by the invention]

[0005] Conventional adhesives do not have the ability to be applied to thin metal substrates and have a sufficiently fast curing rate. For use on thin substrates in particular, adhesives with low viscosity are desirable, and the cured film must also be flexible after application. On the other hand, from the viewpoints of productivity and workability, there is a demand for a one-component adhesive that can be stored and used at room temperature, but it has been difficult to achieve both this and other performance characteristics such as curing speed. Therefore, there has been a demand for a metal adhesive that satisfies the above performance characteristics. Therefore, an object of the present invention is to provide a one-component thermosetting liquid resin composition for metal bonding that can be used as a single component at room temperature, cures quickly after heating, has low viscosity, and provides a cured product with excellent flexibility and adhesive strength. [Means for solving the problem]

[0006] The present inventors have found that a resin composition containing a specific urethane (meth)acrylate, a phosphoric acid ester, and a thermally decomposable organic peroxide can solve the above problems. That is, the present invention relates to the following. [1] A one-component thermosetting liquid resin composition for metal bonding, comprising a urethane (meth)acrylate (A), a phosphate ester (B), and a thermally decomposable organic peroxide (C), wherein the urethane (meth)acrylate (A) has structural units derived from a compound (a) having two or more isocyanate groups, structural units derived from a (meth)acrylate (b) having a hydroxy group, and structural units derived from a polyalkylene glycol (c) having a number average molecular weight of 1500 to 3500, and the acrylic equivalent of the urethane (meth)acrylate (A) is 1000 to 4000 g / eq. [2] The one-component thermosetting liquid resin composition for metal bonding according to the above [1], further comprising a polymerizable monomer (D). [3] The one-component thermosetting liquid resin composition for metal bonding according to the above [2], wherein the content of the polymerizable monomer (D) relative to the urethane (meth)acrylate (A) is 1 to 40 mass %. [4] The thermal decomposition type organic peroxide (C) has a 10-hour half-life temperature of 45 to 130°C. The one-component thermosetting liquid resin composition for metal bonding according to any one of the above [1] to [3]. [5] The one-component thermosetting liquid resin composition for metal bonding according to any one of the above [1] to [4], wherein the phosphate ester (B) is an ethylenically unsaturated group-containing phosphate ester. [6] The one-component thermosetting liquid resin composition for metal bonding according to any one of the above [1] to [5], wherein the phosphate ester (B) is an acidic phosphate ester. [7] The one-component thermosetting liquid resin composition for metal bonding according to any one of [2] to [6] above, wherein the polymerizable monomer (D) is at least one selected from the group consisting of hydroxyalkyl(meth)acrylates and polyalkylene glycol di(meth)acrylates. [Effects of the Invention]

[0007] According to the present invention, it is possible to provide a one-component thermosetting liquid resin composition for metal bonding that can be used as a single component at room temperature, cures quickly after heating, has low viscosity, and provides a cured product with excellent flexibility and adhesive strength. DETAILED DESCRIPTION OF THE INVENTION

[0008] The one-component thermosetting liquid resin composition for metal bonding of the present invention contains a urethane (meth)acrylate (A), a phosphate ester (B), and a thermally decomposable organic peroxide (C), wherein the urethane (meth)acrylate (A) has a structural unit derived from a compound (a) having two or more isocyanate groups, a structural unit derived from a (meth)acrylate (b) having a hydroxy group, and a structural unit derived from a polyalkylene glycol (c) having a number average molecular weight of 1500 to 3500, and the acrylic equivalent of the urethane (meth)acrylate (A) is 1000 to 4000 g / eq. The one-component thermosetting liquid resin composition for metal bonding of the present invention can be used as a single component at room temperature, cures quickly after heating, has low viscosity, and provides excellent flexibility and adhesive strength to the cured product, making it excellent in productivity and enabling thin films to be formed when bonding metals.

[0009] The reasons why the one-component thermosetting liquid resin composition for metal bonding of the present invention has the above-mentioned configuration, can be used as a single component at room temperature, cures quickly after heating, has low viscosity, and provides excellent flexibility and adhesive strength to the cured product are not clear, but are thought to be as follows. The one-component thermosetting liquid resin composition for metal bonding of the present invention contains a thermally decomposable organic peroxide and a urethane (meth)acrylate, and is therefore believed to be usable as a single component at room temperature and to cure rapidly after heating. Furthermore, because the urethane (meth)acrylate has an acrylic equivalent of 1000 to 4000 g / eq, the resin composition has low viscosity, yet the cured product is believed to be flexible. Furthermore, because the one-component thermosetting liquid resin composition for metal bonding of the present invention contains a phosphate ester, it has excellent adhesion to metals and strength after bonding, and is therefore believed to be useful as a resin composition for metal bonding.

[0010] [Urethane (meth)acrylate (A)] The one-component thermosetting liquid resin composition for metal bonding of the present invention contains a urethane (meth)acrylate (A) having a structural unit derived from a compound (a) having two or more isocyanate groups, a structural unit derived from an ethylenically unsaturated group-containing monoalcohol compound (b), and a structural unit derived from a polyalkylene glycol (c) having a number average molecular weight of 1500 to 3500, and having an acrylic equivalent of 1000 to 4000 g / eq. That is, the urethane (meth)acrylate (A) has a structural unit derived from a compound (a) having two or more isocyanate groups, a structural unit derived from an ethylenically unsaturated group-containing monoalcohol compound (b), and a structural unit derived from a polyalkylene glycol (c) having a number average molecular weight of 1500 to 3500, and has an acrylic equivalent of 1000 to 4000 g / eq. In the present invention, "(meth)acrylate" refers to at least one selected from the group consisting of "acrylate" and "methacrylate", "(meth)acryloyl group" refers to at least one selected from the group consisting of "acryloyl group" and "methacryloyl group", and "(meth)acrylic acid" refers to at least one selected from the group consisting of "acrylic acid" and "methacrylic acid".

[0011] Examples of the compound (a) having two or more isocyanate groups include aromatic isocyanate compounds, alicyclic isocyanate compounds, and aliphatic isocyanate compounds, and at least one selected from the group consisting of alicyclic isocyanate compounds and aliphatic isocyanate compounds is preferred, with alicyclic isocyanate compounds being more preferred. Also suitable are trifunctional isocyanates (nurate-type polyisocyanates) having an isocyanurate ring obtained by trimerizing a bifunctional isocyanate compound, and isocyanate prepolymers modified with polyols.

[0012] Examples of aromatic isocyanate compounds include 1,3-xylylene diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 4,4'-diphenyl diisocyanate, 1,5-naphthalene diisocyanate, 4,4'-diphenylmethane diisocyanate, polymethylene polyphenyl polyisocyanate, and m-tetramethylxylene diisocyanate. Examples of the alicyclic isocyanate compound include hydrogenated xylylene diisocyanate (1,3-bis(isocyanatomethyl)cyclohexane), isophorone diisocyanate, norbornene diisocyanate, dicyclohexylmethane diisocyanate, hydrogenated methylene bisphenylene diisocyanate, and 1,4-cyclohexane diisocyanate. Examples of the aliphatic isocyanate compound include 1,6-hexamethylene diisocyanate, trimethylene diisocyanate, etc. These isocyanate compounds can be used alone or in combination of two or more.

[0013] Of the compounds (a) having two or more isocyanate groups, at least one selected from the group consisting of 1,6-hexamethylene diisocyanate, 1,3-bis(isocyanatomethyl)cyclohexane, isophorone diisocyanate, and nurate-type polyisocyanates thereof is preferred, at least one selected from the group consisting of 1,6-hexamethylene diisocyanate, isophorone diisocyanate, and nurate-type polyisocyanates thereof is more preferred, and isophorone diisocyanate is even more preferred. The nurate type polyisocyanate of isophorone diisocyanate is preferably at least one selected from a trimer, pentamer, heptamer, nonamer, and decamer of isophorone diisocyanate (IPDI) in which a nurate ring is formed by an IPDI monomer, or a mixture thereof.

[0014] The (meth)acrylate (b) having a hydroxy group is preferably a hydroxyalkyl (meth)acrylate, a hydroxyphenoxypropyl (meth)acrylate, or a polyalkylene glycol (meth)acrylate, more preferably a hydroxyalkyl (meth)acrylate. Examples of the hydroxyalkyl (meth)acrylate include hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, hydroxybutyl (meth)acrylate, trimethylolpropane di(meth)acrylate, pentaerythritol tri(meth)acrylate, and dipentaerythritol penta(meth)acrylate. Hydroxyethyl (meth)acrylate and hydroxypropyl (meth)acrylate are preferred, hydroxyethyl (meth)acrylate is more preferred, and hydroxyethyl methacrylate is even more preferred. Preferred examples of the polyalkylene glycol (meth)acrylate include polyethylene glycol mono(meth)acrylate and polypropylene glycol mono(meth)acrylate.

[0015] Examples of the polyalkylene glycol (c) having a number average molecular weight of 1500 to 3500 include polymethylene glycol, polyethylene glycol, polypropylene glycol, polybutylene glycol, polyhexamethylene glycol, polyalkylene glycols having two or more alkylene glycol components (copolymers of two or more alkylene oxides), and polyalkylene glycols having a polyhydric alcohol component such as glycerin. Preferably, it is at least one selected from the group consisting of polyethylene glycol, polypropylene glycol, polybutylene glycol, and polyalkylene glycols having an ethylene glycol component and a propylene glycol component (copolymers of ethylene oxide and propylene oxide), more preferably at least one selected from the group consisting of polyethylene glycol and polypropylene glycol, and even more preferably polypropylene glycol.

[0016] The number average molecular weight of the polyalkylene glycol (c) having a number average molecular weight of 1500 to 3500 is 1500 to 3500, preferably 1500 to 3300, more preferably 1800 to 3200, and even more preferably 2000 to 3000. When the number average molecular weight of the polyalkylene glycol (c) is within the above range, a resin composition having excellent flexibility in the cured product can be obtained.

[0017] The molar ratio [(a) / (c)] of the compound (a) having two or more isocyanate groups to the (meth)acrylate (b) having a hydroxy group is preferably 1.0 to 6.0, more preferably 1.2 to 5.0, and even more preferably 1.4 to 3.0. The molar ratio of the compound (a) having two or more isocyanate groups to the polyalkylene glycol (c) [(a) / (c)] is preferably 0.4 to 4.0, more preferably 0.6 to 3.0, and even more preferably 0.7 to 2.0.

[0018] The urethane (meth)acrylate (A) has an acrylic equivalent of 1000 to 4000 g / eq. When the acrylic equivalent of the urethane (meth)acrylate (A) is within the above range, it is possible to obtain a resin composition that can be used as a single component at room temperature, cures quickly after heating, and has excellent flexibility in particular after curing. The acrylic equivalent of the urethane (meth)acrylate (A) is 1000 to 4000 g / eq, preferably 1200 to 3500 g / eq, more preferably 1300 to 3000 g / eq, even more preferably 1400 to 2500 g / eq, and still more preferably 1500 to 2000 g / eq. When the acrylic equivalent of the urethane (meth)acrylate (A) is within the above range, a resin composition can be obtained that exhibits excellent flexibility in particular in the cured product.

[0019] The urethane (meth)acrylate (A) can be obtained by forming a urethane bond from an isocyanate group of a compound (a) having two or more isocyanate groups, and a hydroxy group (hydroxyl group) of a (meth)acrylate (b) having a hydroxy group and a polyalkylene glycol (c). In the reaction for forming a urethane bond, a catalyst such as a metal catalyst or an amine catalyst may be used, and a polymerization inhibitor may be used to prevent the reaction of the (meth)acryloyl group.

[0020] The content of the urethane (meth)acrylate (A) in the one-component thermosetting liquid resin composition for metal bonding is preferably 40 to 95 mass %, more preferably 50 to 90 mass %, even more preferably 60 to 85 mass %, and even more preferably 70 to 80 mass %. By having the content of the urethane (meth)acrylate (A) in the above range, a resin composition having excellent adhesive properties and excellent flexibility of the cured product can be obtained.

[0021] [Phosphate ester (B)] The one-component thermosetting liquid resin composition for metal bonding of the present invention contains a phosphoric acid ester (B). The phosphate ester (B) is preferably an ethylenically unsaturated group-containing phosphate ester. The ethylenically unsaturated group-containing phosphate ester may have one ethylenically unsaturated group or two or more ethylenically unsaturated groups, but is preferably a phosphate ester having one or two ethylenically unsaturated groups, and more preferably a mixture of phosphate esters having one and two ethylenically unsaturated groups. By using the ethylenically unsaturated group-containing phosphate ester, a one-component thermosetting liquid resin composition for metal bonding can be obtained that cures quickly after heating and has excellent adhesive strength. The phosphate ester (B) is more preferably an acidic phosphate ester. By using an acidic phosphate ester, it is possible to obtain a one-component thermosetting liquid resin composition for metal bonding that has even more excellent adhesive strength.

[0022] More specifically, the ethylenically unsaturated group-containing phosphate ester is preferably a phosphate ester having a (meth)acryloyl group, and more preferably a phosphate ester (meth)acrylate. More preferred is an acidic phosphate ester in which one or two (meth)acryloyl groups are bonded to the phosphoric acid. Preferred examples of the phosphate ester (B) include 2-methacryloyloxyethyl phosphate ester, bis(2-methacryloyloxyethyl) phosphate ester, and mixtures thereof.

[0023] The content of the phosphate ester (B) in the one-component thermosetting liquid resin composition for metal bonding is preferably 1 to 20 mass %, more preferably 1 to 15 mass %, even more preferably 2 to 10 mass %, and even more preferably 3 to 7 mass %. When the content of the phosphate ester (B) is within the above range, the one-component thermosetting liquid resin composition for metal bonding can be quickly cured after heating and has excellent adhesive strength.

[0024] [Thermal decomposition type organic peroxide (C)] The one-component thermosetting liquid resin composition for metal bonding of the present invention contains a thermally decomposable organic peroxide (C). The thermally decomposable organic peroxide (C) is preferably an organic peroxide.

[0025] Examples of organic peroxides include t-butylperoxy-2-ethylhexyl monocarbonate, 1,1-di(t-hexylperoxy)cyclohexane, 1,1-di(t-butylperoxy)cyclohexane, 1,1-di(t-butylperoxy)-3,3,5-trimethylcyclohexane, t-butylperoxyoctoate, benzoyl peroxide, methyl ethyl ketone peroxide, acetylacetone peroxide, t-butylperoxybenzoate, t-butylcumyl peroxide, and dicumyl peroxide. Among these, at least one selected from the group consisting of t-butyl peroxy octoate, t-butylperoxy-2-ethylhexyl monocarbonate, and t-butylcumyl peroxide is preferred, at least one selected from the group consisting of t-butyl peroxy octoate and t-butylperoxy 2-ethylhexyl monocarbonate is more preferred, and t-butylperoxy 2-ethylhexyl monocarbonate is even more preferred. The 10-hour half-life temperature of the thermally decomposable organic peroxide (C) is preferably 45 to 130°C, more preferably 70 to 120°C, and even more preferably 90 to 110°C. Within this range, it can be used as a single liquid at room temperature and has an excellent curing rate. The thermally decomposable organic peroxide (C) may be used alone or in combination of two or more types.

[0026] The content of the thermally decomposable organic peroxide (C) in the one-component type thermosetting liquid resin composition for metal bonding is preferably 0.3 to 4.0 mass%, more preferably 0.5 to 3.0 mass%, even more preferably 0.8 to 2.5 mass%, and still more preferably 1.0 to 2.0 mass%. By setting the content of the thermally decomposable organic peroxide (C) within the above range, the one-component type thermosetting liquid resin composition for metal bonding can be used as a single component at room temperature and has an excellent curing rate.

[0027] [Polymerizable monomer (D)] The one-component thermosetting liquid resin composition for metal bonding of the present invention preferably further contains a polymerizable monomer (D). Before curing, the polymerizable monomer (D) acts as a diluent to impart fluidity to the resin composition and also functions as a solvent for the resin, and after curing, it acts as a crosslinking moiety to improve the strength and hardness of the resulting cured product. Therefore, in the present invention, by containing the polymerizable monomer (D), the resin composition can be used as a one-component at room temperature and can have a low viscosity. The polymerizable monomer (D) is an optional component, and the one-component thermosetting liquid resin composition for metal bonding of the present invention is a one-component thermosetting liquid resin composition for metal bonding that does not contain the polymerizable monomer (D) or that contains the polymerizable monomer (D).

[0028] The polymerizable monomer (D) is preferably at least one selected from the group consisting of a styrene-based monomer, a (meth)acrylic acid-based monomer, and a vinyl acetate-based monomer, more preferably at least one selected from the group consisting of a styrene-based monomer and a (meth)acrylic acid-based monomer, and even more preferably a (meth)acrylic acid-based monomer. The styrene-based monomer is preferably at least one selected from the group consisting of styrene, vinyltoluene, and α-methylstyrene, and more preferably styrene. The (meth)acrylic acid monomer is preferably at least one selected from the group consisting of (meth)acrylic acid, alkyl (meth)acrylate, hydroxyalkyl (meth)acrylate, polyalkylene glycol di(meth)acrylate, and polyalkylene glycol mono(meth)acrylate, more preferably at least one selected from the group consisting of hydroxyalkyl (meth)acrylate and polyalkylene glycol di(meth)acrylate, even more preferably polyalkylene glycol di(meth)acrylate, and still more preferably polyalkylene glycol di(meth)acrylate and hydroxyalkyl (meth)acrylate. By using these preferred (meth)acrylic acid monomers, the resin composition can be used as a one-part composition at room temperature, can have a low viscosity, has excellent adhesion, and can make the resulting cured product flexible.

[0029] Examples of alkyl (meth)acrylates include methyl methacrylate, benzyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, t-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate, tridecyl (meth)acrylate, cyclohexyl (meth)acrylate, isobornyl (meth)acrylate, norbornyl (meth)acrylate, dicyclopentenyl (meth)acrylate, and dicyclopentanyl (meth)acrylate. Examples of the hydroxyalkyl (meth)acrylate include hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, hydroxybutyl (meth)acrylate, trimethylolpropane di(meth)acrylate, pentaerythritol tri(meth)acrylate, and dipentaerythritol penta(meth)acrylate. Hydroxyethyl (meth)acrylate and hydroxypropyl (meth)acrylate are preferred, hydroxyethyl (meth)acrylate is more preferred, and hydroxyethyl methacrylate is even more preferred. Examples of polyalkylene glycol di(meth)acrylate include polyethylene glycol di(meth)acrylate and polypropylene glycol di(meth)acrylate, with polyethylene glycol di(meth)acrylate being preferred. Examples of the polyalkylene glycol mono(meth)acrylate include polyethylene glycol mono(meth)acrylate and polypropylene glycol mono(meth)acrylate.

[0030] The polymerizable monomer (D) is an optional component, and the one-component thermosetting liquid resin composition for metal bonding of the present invention is a one-component thermosetting liquid resin composition for metal bonding that either does not contain the polymerizable monomer (D) or contains the polymerizable monomer (D). Therefore, the content of the polymerizable monomer (D) in the one-component thermosetting liquid resin composition for metal bonding is preferably 0 to 40% by mass. When the one-component thermosetting liquid resin composition contains the polymerizable monomer (D), the content is preferably 1 to 40% by mass, more preferably 5 to 35% by mass, even more preferably 10 to 30% by mass, and even more preferably 15 to 25% by mass. By setting the content of the polymerizable monomer (D) within the above range, the composition can be used as a one-component resin at room temperature, can have a low viscosity, can have excellent adhesive strength, and can produce a flexible cured product.

[0031] The content of the polymerizable monomer (D) relative to the urethane (meth)acrylate (A) is preferably 0 to 40% by mass, more preferably 1 to 40% by mass, even more preferably 10 to 35% by mass, still more preferably 15 to 33% by mass, and even more preferably 20 to 30% by mass. By setting the content of the polymerizable monomer (D) within the above range, the composition can be used as a one-part composition at room temperature, the viscosity can be low, the adhesive strength can be excellent, and the resulting cured product can be made flexible.

[0032] <Production method, characteristics, etc. of one-component thermosetting liquid resin composition for metal bonding> The one-component thermosetting liquid resin composition for metal bonding of the present invention may be obtained by any method, but it is sufficient to blend the components and mix them until they are uniform. Since the one-component thermosetting liquid resin composition for metal bonding of the present invention can be used as a single component at room temperature, it is preferable that mixing is also carried out at room temperature (room temperature, about 20 to 30°C).

[0033] The one-component thermosetting liquid resin composition for metal bonding of the present invention may contain a polymerization inhibitor as another component in addition to the above-mentioned urethane (meth)acrylate (A), phosphate ester (B), thermally decomposable organic peroxide (C), and polymerizable monomer (D), within the scope of not impairing the effects of the present invention. Examples of the polymerization inhibitor include dibutylhydroxytoluene and toluhydroquinone.

[0034] The viscosity at 25°C of the one-component thermosetting liquid resin composition for metal bonding of the present invention is preferably less than 10 Pa·s, more preferably 8 Pa·s or less, even more preferably 6 Pa·s or less, even more preferably 5 Pa·s or less, and even more preferably 4 Pa·s or less. Having a viscosity at 25°C within the above range is preferable because it allows the adhesive layer to be thin. It also enables application to thin-film metal substrates.

[0035] As described above, the one-component thermosetting liquid resin composition for metal bonding of the present invention can be used as a single component at room temperature, cures quickly after heating, has low viscosity, and provides excellent flexibility and adhesive strength in the cured product. Therefore, it can be applied to thin-film metal substrates. Furthermore, since it can be stored and used as a single component at room temperature and has a fast curing rate, it is useful as a metal adhesive that is also excellent in productivity and workability.

[0036] <Laminate> Since the one-component thermosetting liquid resin composition for metal bonding of the present invention is suitably used for bonding metals together, it is preferable to form a laminate by providing a cured layer obtained by curing the one-component thermosetting liquid resin composition for metal bonding between two metal layers. That is, the laminate is preferably a laminate having a metal layer and a cured layer obtained by curing the one-component thermosetting liquid resin composition for bonding metal of the present invention. As described above, the one-component thermosetting liquid resin composition for metal bonding contains a specific urethane (meth)acrylate (A), a phosphate ester (B), and a thermally decomposable organic peroxide (C). Therefore, it can be used as a one-component resin at room temperature, cures quickly after heating, has low viscosity, and exhibits excellent flexibility in the cured product. Therefore, the cured layer of the laminate is flexible and exhibits excellent adhesion to metal. Therefore, it is particularly useful for use on thin-film metal substrates. In view of the above, the metal layer constituting the laminate is preferably a thin film metal substrate. Examples of metals constituting the metal layer include iron, stainless steel, and aluminum, with stainless steel being preferred. The laminate has a cured layer made of the cured product of the resin composition between two metal layers, and may be made of the above three layers or more layers depending on the application. [Example]

[0037] Hereinafter, one embodiment of the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. Unless otherwise specified, "parts" means "parts by mass" and "%" means "% by mass."

[0038] <Production of urethane (meth)acrylate> The urethane (meth)acrylate, which is a compounding component of the one-component thermosetting liquid resin compositions for metal bonding in the examples and comparative examples, was produced as follows.

[0039] Production Example 1 (Production of Urethane (Meth)acrylate 1) A four-neck flask was charged with 805.7 parts of polypropylene glycol (number average molecular weight 3000, manufactured by Sanyo Chemical Industries, Ltd., trade name "Sannyx PP-3000"), 121.4 parts of isophorone diisocyanate (two isocyanate groups, manufactured by Evonik, trade name "VASTANAT IPDI"), 72.3 parts of 2-hydroxyethyl methacrylate (manufactured by Mitsubishi Gas Chemical Co., Ltd., trade name "2-hydroxyethyl methacrylate"), 0.1 parts of toluhydroquinone, 0.4 parts of dibutylhydroxytoluene, and 0.05 parts of dibutyltin dilaurate, and the mixture was reacted under a dry air flow (0.2 L / min) at a temperature of 98 to 102 °C. The reaction was monitored by IR, and the absorption of the isocyanate group (2270 cm) was monitored. -1 The reaction ended when the ethylenically unsaturated group (near the end of the reaction) disappeared, yielding urethane (meth)acrylate 1. The reaction took 3 hours. The theoretical ethylenically unsaturated group equivalent of the urethane (meth)acrylate was 1800 g / eq, and its viscosity measured with an E-type viscometer was approximately 10 Pa·s at 25°C.

[0040] Production Example 2 (Production of Urethane (Meth)acrylate 2) A four-neck flask was charged with 855.7 parts of polypropylene glycol (number average molecular weight 3000, manufactured by Sanyo Chemical Industries, Ltd., trade name "Sannix PP-3000"), 100.4 parts of isophorone diisocyanate (two isocyanate groups, manufactured by Evonik, trade name "VASTANAT IPDI"), 43.3 parts of 2-hydroxyethyl methacrylate (manufactured by Mitsubishi Gas Chemical Co., Ltd., trade name "2-hydroxyethyl methacrylate"), 0.1 parts of toluhydroquinone, 0.4 parts of dibutylhydroxytoluene, and 0.05 parts of dibutyltin dilaurate, and the mixture was reacted under a dry air flow (0.2 L / min) at a temperature of 98 to 102 °C. The reaction was monitored by IR, and the absorption of the isocyanate group (2270 cm) was monitored. -1 The reaction ended when the ethylenically unsaturated group (approximately 100%) disappeared, yielding urethane (meth)acrylate 2. The reaction took 3 hours. The theoretical ethylenically unsaturated group equivalent of the urethane (meth)acrylate was 3000 g / eq, and its viscosity measured with an E-type viscometer was approximately 14 Pa·s at 25°C.

[0041] Production Example 3 (Production of Urethane (Meth)acrylate 3) A four-neck flask was charged with 598.5 parts of polypropylene glycol (number average molecular weight 1000, manufactured by Sanyo Chemical Industries, Ltd., trade name "Sannix PP-1000"), 256.5 parts of isophorone diisocyanate (two isocyanate groups, manufactured by Evonik, trade name "VASTANAT IPDI"), 144.5 parts of 2-hydroxyethyl methacrylate (manufactured by Mitsubishi Gas Chemical Co., Inc., trade name "2-hydroxyethyl methacrylate"), 0.1 parts of toluhydroquinone, 0.4 parts of dibutylhydroxytoluene, and 0.05 parts of dibutyltin dilaurate, and the mixture was reacted under a dry air flow (0.2 L / min) at a temperature of 98 to 102 °C. The reaction was monitored by IR, and the absorption of the isocyanate group (2270 cm) was monitored. -1 The reaction ended when the ethylenically unsaturated group (approximately 100%) disappeared, yielding urethane (meth)acrylate 3. The reaction took 3 hours. The theoretical ethylenically unsaturated group equivalent of the urethane (meth)acrylate was 900 g / eq, and its viscosity measured with an E-type viscometer was approximately 140 Pa·s at 25°C.

[0042] Production Example 4 (Production of Urethane (Meth)acrylate 4) A four-neck flask was charged with 885.6 parts of polypropylene glycol (number average molecular weight 3000, manufactured by Sanyo Chemical Industries, Ltd., trade name "Sannix PP-3000"), 87.8 parts of isophorone diisocyanate (two isocyanate groups, manufactured by Evonik, trade name "VASTANAT IPDI"), 26.0 parts of 2-hydroxyethyl methacrylate (manufactured by Mitsubishi Gas Chemical Co., Inc., trade name "2-hydroxyethyl methacrylate"), 0.1 parts of toluhydroquinone, 0.4 parts of dibutylhydroxytoluene, and 0.05 parts of dibutyltin dilaurate, and the mixture was reacted under a dry air flow (0.2 L / min) at a temperature of 98 to 102 °C. The reaction was monitored by IR, and the absorption of the isocyanate group (2270 cm) was monitored. -1 The reaction ended when the ethylenically unsaturated group (approximately 100%) disappeared, yielding urethane (meth)acrylate 3. The reaction took 3 hours. The theoretical ethylenically unsaturated group equivalent of the urethane (meth)acrylate was 5000 g / eq, and its viscosity measured with an E-type viscometer was approximately 19 Pa·s at 25°C.

[0043] <Production of one-component thermosetting liquid resin composition for metal bonding> Examples 1 to 5 and Comparative Examples 1 to 3 The urethane (meth)acrylates 1 to 4 obtained in Production Examples 1 to 4 above were mixed with the following components to obtain the compositions shown in Table 1, and the mixture was stirred until a homogeneous solution was obtained, thereby obtaining a one-component thermosetting liquid resin composition for metal bonding.

[0044] The following ingredients were used in addition to the urethane (meth)acrylate. (1) Phosphate ester JPA-514: 2-hydroxyethyl methacrylate acid phosphate (mixture of 2-methacryloyloxyethyl phosphate ester and bis(2-methacryloyloxyethyl) phosphate ester), manufactured by Johoku Chemical Industry Co., Ltd. Light Ester P-2M: 2-methacryloyloxyethyl acid phosphate, manufactured by Kyoeisha Chemical Co., Ltd. (2) Pyrolytic organic peroxide Percure O: t-butyl peroxyoctoate, NOF Corporation, 10-hour half-life temperature: 72.1°C Perbutyl E: t-butylperoxy 2-ethylhexyl monocarbonate, NOF Corporation, 10-hour half-life temperature: 99.0°C (3) Polymerizable monomer 2HEMA: 2-hydroxyethyl methacrylate, manufactured by Mitsubishi Gas Chemical Co., Ltd. M-90G: NK Ester M-90G, methoxypolyethylene glycol methacrylate, manufactured by Shin-Nakamura Chemical Co., Ltd.

[0045] <Evaluation method> (1) Viscosity evaluation The viscosity at 25°C of the one-component thermosetting liquid resin compositions for metal bonding of the examples and comparative examples shown in Table 1 was measured using an E-type cone-plate viscometer (manufactured by Toki Sangyo Co., Ltd., device name "TV-25H"). The lower the viscosity, the more thin a film can be formed during metal bonding, and the more preferable it is. The evaluation criteria were as follows: a viscosity of less than 10 Pa·s at 25°C was rated as "good", and a viscosity of 10 Pa·s or more at 25°C was rated as "bad". The results are shown in Table 1.

[0046] (2) Curability evaluation The curability at 150°C of the one-component thermosetting liquid resin compositions for metal bonding of the Examples and Comparative Examples shown in Table 1 was evaluated as follows. Approximately 1 g of each resin composition of the Examples and Comparative Examples was weighed out and placed on the hot plate of a gelation tester heated to 150°C. An aluminum plate was then placed over the composition, and measurement with a stopwatch was started. The time until the aluminum plate stopped moving was recorded as the gelation time (hot plate gel time). A shorter gelation time is preferable because it results in faster curing after heating and superior productivity. The evaluation criteria were as follows: a gelation time of less than 30 seconds was marked as ◯, and a gelation time of 30 seconds or more was marked as ×. The results are shown in Table 1. In Table 1, "<10" means "less than 10 seconds."

[0047] (3) Evaluation of flexibility (bending test) Two acetone-degreased stainless steel thin plates (10 cm long, 2 cm wide, 0.1 mm thick) were sandwiched between two sheets of thin stainless steel plates (10 cm long, 2 cm wide, 0.1 mm thick) so that the thickness of the adhesive layer (cured resin composition) was 0.2 mm. The plates were then heated at 150°C for 15 minutes to fully cure. The resulting laminate of thin plates was then rolled up so that both ends met, and the adhesive layer was visually inspected for cracks. The fewer cracks present, the more flexible the adhesive and the thinner it can be during metal bonding, making it preferable. Furthermore, no cracks are even more preferable because they provide better flexibility. The evaluation criteria were as follows: no cracks present, ◯; cracks present, ×. The results are shown in Table 1.

[0048] (4) Adhesion strength evaluation A shear test was conducted in accordance with JIS K 6850:1999 to evaluate the adhesive strength of the one-component thermosetting liquid resin compositions for metal bonding of the Examples and Comparative Examples shown in Table 1. Test pieces were prepared in accordance with JIS K 6850:1999 and subjected to a tensile test to determine the shear strength. Acetone-degreased steel plate test pieces were used as the test plates, and the curing time was 150°C for 5 minutes. The higher the shear strength value, the greater the adhesive strength, which is preferable. The evaluation criteria were as follows: a shear strength of 2.8 MPa or more was rated as ◯, and a shear strength of less than 2.8 MPa was rated as ×. The results are shown in Table 1.

[0049] [Table 1]

[0050] Table 1 shows that the one-component thermosetting liquid resin compositions for metal bonding of the examples have low viscosity, short gel times (hot plate gel times) in the curing evaluation, and no cracks in the bending test. This shows that the one-component thermosetting liquid resin compositions for metal bonding of the present invention can be used as a single component at room temperature, cure quickly after heating, have low viscosity, and exhibit excellent flexibility of the cured product. Furthermore, the one-component thermosetting liquid resin compositions for metal bonding of the examples have high shear strength values ​​in the adhesive strength evaluation, demonstrating excellent adhesive strength. Therefore, they can be applied to thin-film metal substrates. Furthermore, because they can be stored and used as a single component at room temperature and have a fast curing rate, they are useful as metal adhesives that are excellent in productivity and workability.

Claims

1. The composition contains a urethane (meth)acrylate (A), a phosphoric acid ester (B), and a thermally decomposable organic peroxide (C), The one-component thermosetting liquid resin composition for metal bonding, wherein the urethane (meth)acrylate (A) has a structural unit derived from a compound (a) having two or more isocyanate groups, a structural unit derived from a (meth)acrylate (b) having a hydroxy group, and a structural unit derived from a polyalkylene glycol (c) having a number average molecular weight of 1500 to 3500, and the acrylic equivalent of the urethane (meth)acrylate (A) is 1000 to 4000 g / eq.

2. The one-component thermosetting liquid resin composition for metal bonding according to claim 1, further comprising a polymerizable monomer (D).

3. 3. The one-component thermosetting liquid resin composition for metal bonding according to claim 2, wherein the content of the polymerizable monomer (D) relative to the urethane (meth)acrylate (A) is 1 to 40 mass %.

4. 2. The one-component thermosetting liquid resin composition for metal bonding according to claim 1, wherein the thermally decomposable organic peroxide (C) has a 10-hour half-life temperature of 45 to 130°C.

5. 2. The one-component thermosetting liquid resin composition for metal bonding according to claim 1, wherein the phosphate ester (B) is an ethylenically unsaturated group-containing phosphate ester.

6. 2. The one-component thermosetting liquid resin composition for metal bonding according to claim 1, wherein the phosphate ester (B) is an acidic phosphate ester.

7. 3. The one-component thermosetting liquid resin composition for metal bonding according to claim 2, wherein the polymerizable monomer (D) is at least one selected from the group consisting of hydroxyalkyl(meth)acrylates and polyalkylene glycol di(meth)acrylates.

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