Adhesive composition and bonded object

Abstract

Disclosed is an adhesive composition containing a monofunctional (meth)acrylate compound, a polyfunctional (meth)acrylate compound, an epoxy compound, a crosslinking agent, and a photoacid generator. The monofunctional (meth)acrylate compound includes a (meth)acrylate having a fluorine-containing organic group. The crosslinking agent includes a (meth)acrylic resin comprising a first structural unit derived from a (meth)acrylate having a fluorine-containing organic group and a second structural unit derived from a (meth)acrylate having a cyclic ether group.

Description

Adhesive composition and adhesive body

[0001] The present disclosure relates to an adhesive composition and an adhesive body.

[0002] As an adhesive composition, a photocurable composition containing a (meth)acrylate compound, an epoxy compound, and a photoacid generator is known (see, for example, Patent Document 1).

[0003] Japanese Patent Application Laid-Open No. 2018-141137

[0004] Polymers of compounds having a fluorine-containing organic group have attracted attention as materials exhibiting a low refractive index. The present inventors have focused on adhesive compositions containing a (meth)acrylate compound, an epoxy compound, and a photoacid generator, and have investigated the curing reaction using a (meth)acrylate having a fluorine-containing organic group as the (meth)acrylate compound. As a result, the present inventors have found that the adhesive strength of a cured product of the adhesive composition tends to decrease significantly after a moist heat test (for example, a durability test under conditions of a temperature of 85°C, a humidity of 85% RH, and a time of 168 hours).

[0005] A primary object of the present disclosure is to provide an adhesive composition that can give a cured product that sufficiently retains adhesive strength before and after a moist heat test.

[0006] The present inventors have conducted extensive research to solve the above problems and have found that by combining a monofunctional (meth)acrylate compound and a polyfunctional (meth)acrylate compound in a specific adhesive composition, a cured product can be obtained in which the adhesive strength is sufficiently maintained (kept) before and after a moist heat test, which led to the completion of the presently disclosed invention.

[0007] The present disclosure includes the following items [1] to [5]. [1] An adhesive composition comprising a monofunctional (meth)acrylate compound, a polyfunctional (meth)acrylate compound, an epoxy compound, a crosslinking agent, and a photoacid generator, wherein the monofunctional (meth)acrylate compound comprises a (meth)acrylate having a fluorine-containing organic group, and the crosslinking agent comprises a (meth)acrylic resin having a first structural unit derived from the (meth)acrylate having a fluorine-containing organic group and a second structural unit derived from a (meth)acrylate having a cyclic ether group. [2] The adhesive composition according to item [1], wherein the polyfunctional (meth)acrylate compound comprises a tri- or higher functional (meth)acrylate compound. [3] The adhesive composition according to item [1] or [2], wherein the epoxy compound comprises an aliphatic epoxy compound. [4] The adhesive composition according to item [3], wherein the epoxy compound further comprises an alicyclic epoxy compound. [5] An adhesive structure comprising a first adherend, a second adherend, and an adhesive joint that bonds the first adherend and the second adherend to each other, wherein the adhesive joint contains a cured product of the adhesive composition according to any one of [1] to [4].

[0008] According to the present disclosure, an adhesive composition is provided that can give a cured product that sufficiently retains adhesive strength before and after a moist heat test. Also, according to the present disclosure, an adherend using such an adhesive composition is provided.

[0009] Hereinafter, embodiments of the present disclosure will be described, but the present disclosure is not limited to the following embodiments.

[0010] 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 numerical ranges described in stages in this specification, the upper or lower limit of a certain numerical range may be replaced with the upper or lower limit of another numerical range. Furthermore, in a numerical range described in this specification, the upper or lower limit of that numerical range may be replaced with a value shown in the examples. Furthermore, individually described upper and lower limits can be arbitrarily combined. In a numerical range described as "A to B," the numerical values ​​A and B at both ends are included as the lower and upper limits, respectively, in the numerical range. In this specification, for example, the term "10 or more" means "10" and "a number greater than 10," and this also applies when the numerical values ​​are different. Furthermore, for example, the term "10 or less" means "10" and "a number less than 10," and this also applies when the numerical values ​​are different.

[0011] In this specification, a (meth)acrylate compound refers to a compound having one or more (meth)acryloyl groups, a monofunctional (meth)acrylate compound refers to a compound having one (meth)acryloyl group, and a polyfunctional (meth)acrylate compound refers to a compound having two or more (meth)acryloyl groups. A (meth)acrylic resin refers to a (co)polymer having at least a structural unit derived from a (meth)acrylate compound. A (meth)acryloyl group refers to an acryloyl group or a corresponding methacryloyl group. The same applies to other similar expressions such as (meth)acrylate. Furthermore, "A or B" may include either A or B, or may include both.

[0012] In this specification, the term "cyclic ether group" refers to a group obtained by removing one hydrogen atom directly bonded to a carbon atom from a compound having a cyclic ether such as oxirane or oxetane. The cyclic ether group may be a group obtained by removing one hydrogen atom directly bonded to a carbon atom from a compound having a three- or four-membered cyclic ether. Examples of such cyclic ether groups include epoxy groups (oxiranyl groups), oxetanyl groups, and alicyclic epoxy groups (epoxy groups formed together with the two carbon atoms constituting the alicyclic ring) such as epoxycyclohexyl groups.

[0013] Unless otherwise specified, the materials exemplified below may be used alone or in combination of two or more. When a composition contains multiple substances corresponding to each component, the amount used or content of each component means the total amount of the multiple substances present in the composition, unless otherwise specified.

[0014] [Adhesive Composition] The adhesive composition of one embodiment contains a monofunctional (meth)acrylate compound (hereinafter sometimes referred to as "component (A)"), a polyfunctional (meth)acrylate compound (hereinafter sometimes referred to as "component (B)"), an epoxy compound (hereinafter sometimes referred to as "component (C)"), a crosslinking agent (hereinafter sometimes referred to as "component (D)"), and a photoacid generator (hereinafter sometimes referred to as "component (E)"). The adhesive composition may further contain, for example, a coupling agent (hereinafter sometimes referred to as "component (F)"), a photoradical generator (hereinafter sometimes referred to as "component (G)"), etc.

[0015] Component (A): Monofunctional (meth)acrylate Compound The component (A) contains a (meth)acrylate having a fluorine-containing organic group (hereinafter, sometimes referred to as "component (A1)"). The component (A) may further contain a (meth)acrylate having a hydroxy group (hereinafter, sometimes referred to as "component (A2)"). The component (A) may further contain a (meth)acrylate having an alkoxy group (hereinafter, sometimes referred to as "component (A3)").

[0016] By including the component (A1) in the component (A), it is possible to achieve a low refractive index in the cured product of the adhesive composition. The component (A1) may be, for example, a (meth)acrylate having a fluoroalkyl group. Examples of (meth)acrylates having a fluoroalkyl group include trifluoromethyl (meth)acrylate, 2,2,2-trifluoroethyl (meth)acrylate, 1,1,1,3,3,3-hexafluoro-2-propyl (meth)acrylate, perfluoroethylmethyl (meth)acrylate, perfluoropropylmethyl (meth)acrylate, perfluorobutylmethyl (meth)acrylate, perfluoropentylmethyl (meth)acrylate, perfluorohexylmethyl (meth)acrylate, perfluoroheptylmethyl (meth)acrylate, perfluorooctylmethyl (meth)acrylate, perfluorononylmethyl (meth)acrylate, perfluorodecylmethyl (meth)acrylate, perfluoroundecylmethyl (meth)acrylate, perfluorododecylmethyl (meth)acrylate, and perfluorotridecylmethyl (meth)acrylate. perfluoromethyl (meth)acrylate, perfluorotetradecylmethyl (meth)acrylate, 2-(trifluoromethyl)ethyl (meth)acrylate, 2-(perfluoroethyl)ethyl (meth)acrylate, 2-(perfluoropropyl)ethyl (meth)acrylate, 2-(perfluorobutyl)ethyl (meth)acrylate, 2-(perfluoropentyl)ethyl (meth)acrylate, 2-(perfluorohexyl)ethyl (meth)acrylate, 2-(perfluoroheptyl)ethyl (meth)acrylate, 2-(perfluorooctyl)ethyl (meth)acrylate, 2-(perfluorononyl)ethyl (meth)acrylate, 2-(perfluorotridecyl)ethyl (meth)acrylate, 2-(perfluorotetradecyl)ethyl (meth)acrylate, 1H,1H,5H-octafluoropentyl (meth)acrylate, and the like.

[0017] In the (meth)acrylate having a fluoroalkyl group as the component (A1), the number of carbon atoms in the fluoroalkyl group may be, for example, 1 to 20, 2 or more, 3 or more, 4 or more, or 6 or more, or may be 18 or less, 16 or less, 14 or less, or 12 or less, from the viewpoint of reducing the refractive index of the cured product.

[0018] In a (meth)acrylate having a fluoroalkyl group as component (A1), the proportion of fluorine atoms in the fluoroalkyl group is calculated based on the total amount of hydrogen atoms and fluorine atoms directly bonded to carbon atoms constituting the fluoroalkyl group. For example, the trifluoromethyl group of trifluoromethyl (meth)acrylate has three fluorine atoms and no hydrogen atoms, so the proportion of fluorine atoms is 100%. For example, the 2,2,2-trifluoroethyl group of 2,2,2-trifluoroethyl (meth)acrylate has three fluorine atoms and two hydrogen atoms, so the proportion of fluorine atoms is 60%. From the viewpoint of lowering the refractive index of the cured product, the proportion of fluorine atoms may be, for example, 100% or less, 90% or less, or 80% or less, or 30% or more, 40% or more, or 50% or more.

[0019] From the viewpoint of achieving a low refractive index of the cured product, the content of the component (A1) may be 5% by mass or more, 15% by mass or more, 25% by mass or more, 30% by mass or more, 35% by mass or more, 40% by mass or more, or 45% by mass or more, and may be 70% by mass or less, 65% by mass or less, or 60% by mass or less, based on the total amount of the component (A).

[0020] By including component (A2) in component (A), the curability and adhesion of the adhesive composition can be further improved. Component (A2) may be, for example, a (meth)acrylate having a hydroxyalkyl group. Examples of (meth)acrylates having a hydroxyalkyl group include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate.

[0021] From the viewpoint of the curability and adhesion of the adhesive composition, the content of component (A2) may be 0.1 mass % or more, 1 mass % or more, or 2 mass % or more, and may be 15 mass % or less, 12 mass % or less, 10 mass % or less, or 8 mass % or less, based on the total amount of component (A).

[0022] By including the component (A3) in the component (A), the solubility of the component (D), which will be described later, can be further improved, and further the transmittance of the cured product of the adhesive composition can be further improved. The component (A3) may be, for example, a (meth)acrylate having an alkoxyalkyl group. Examples of the component (A3) include 2-methoxyethyl acrylate and 2-ethoxyethyl (meth)acrylate.

[0023] From the viewpoint of the solubility of the component (D), the content of the component (A3) may be 5% by mass or more, 10% by mass or more, 20% by mass or more, 30% by mass or more, or 35% by mass or more, and may be 65% by mass or less, 60% by mass or less, 55% by mass or less, or 50% by mass or less, based on the total amount of the component (A).

[0024] The component (A) may contain another (meth)acrylate (hereinafter, sometimes referred to as "component (A4)") to the extent that the effects of the present disclosure are not impaired. Examples of the component (A4) include monofunctional (meth)acrylates having one (meth)acryloyl group other than the components (A1), (A2), and (A3).

[0025] Examples of the component (A4) include alkyl (meth)acrylates having an alkyl group, such as methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, n-hexyl (meth)acrylate, n-octyl (meth)acrylate, isooctyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isodecyl (meth)acrylate, and dodecyl (meth)acrylate; alkenyl (meth)acrylates having an alkenyl group, such as 3-butenyl (meth)acrylate; (meth)acrylates having an aromatic group, such as benzyl (meth)acrylate and phenoxyethyl (meth)acrylate; cyclohexyl (meth)acrylate, isobornyl (meth)acrylate, and the like. (meth)acrylates having an alicyclic group such as acrylate or dicyclopentanyl (meth)acrylate; (meth)acrylates having a heterocyclic group such as 4-(meth)acryloylmorpholine; alkoxypolyalkylene glycol (meth)acrylates such as methoxyethylene glycol (meth)acrylate, methoxytetraethylene glycol (meth)acrylate, methoxyhexaethylene glycol (meth)acrylate, and methoxyoctaethylene glycol (meth)acrylate; polyalkylene glycol mono(meth)acrylates such as tetraethylene glycol mono(meth)acrylate, hexaethylene glycol mono(meth)acrylate, and octapropylene glycol mono(meth)acrylate; and (meth)acrylates having a siloxane skeleton.

[0026] The content of the component (A4) may be 0 to 45 mass%, 0 to 40 mass%, 0 to 30 mass%, 0 to 25 mass%, 0 to 10 mass%, or 0 to 5 mass%, based on the total amount of the component (A).

[0027] The content of the component (A) (total amount of the components (A1), (A2), (A3), and (A4)) may be 20% by mass or more, 25% by mass or more, or 30% by mass or more, and may be 60% by mass or less, 55% by mass or less, 50% by mass or less, or 45% by mass or less, based on the total amount of the adhesive composition.

[0028] Component (B): Polyfunctional (meth)acrylate compound When the adhesive composition contains component (B), a polymer with a network structure is formed together with component (A), making it possible to provide a cured product that sufficiently retains its adhesive strength before and after a moist heat test.

[0029] Examples of the component (B) include bifunctional (meth)acrylates such as ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, polyethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, 1,3-bis((meth)acryloyloxy)-2-propanol, dioxane glycol di(meth)acrylate, isocyanuric acid EO-modified di(meth)acrylate, dimethyloltricyclodecane di(meth)acrylate, and 1,3-adamantanediol di(meth)acrylate. trifunctional (meth)acrylates such as pentaerythritol tri(meth)acrylate, trimethylolpropane EO-modified tri(meth)acrylate, trimethylolpropane PO-modified tri(meth)acrylate, glycerin PO-modified tri(meth)acrylate, and isocyanuric acid EO-modified tri(meth)acrylate; pentaerythritol tetra(meth)acrylate, sorbitol tetra(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, prop ... Examples of the acrylate include tetrafunctional (meth)acrylates such as dipentaerythritol propionate tetra(meth)acrylate; pentafunctional (meth)acrylates such as sorbitol penta(meth)acrylate; and hexafunctional (meth)acrylates such as dipentaerythritol hexa(meth)acrylate, sorbitol hexa(meth)acrylate, alkylene oxide-modified hexa(meth)acrylate of phosphazene, and caprolactone-modified dipentaerythritol hexa(meth)acrylate.

[0030] Component (B) may contain a tri- or higher functional (meth)acrylate compound, as this makes it easier to obtain the effects of the present disclosure. The tri- or higher functional (meth)acrylate compound may be a decafunctional or lower (meth)acrylate compound, an octafunctional or lower (meth)acrylate compound, or a hexafunctional or lower (meth)acrylate compound.

[0031] The component (B) may be an acrylate compound having an acryloyl group but not a methacryloyl group, or a methacrylate compound having a methacryloyl group but not an acryloyl group. The component (B) may be an acrylate compound having an acryloyl group but not a methacryloyl group, because this makes it easier to obtain the effects of the present disclosure more sufficiently.

[0032] The content of component (B) may be 0.1 mass % or more, 0.5 mass % or more, or 1 mass % or more, and may be 15 mass % or less, 10 mass % or less, or 5 mass % or less, based on the total amount of the adhesive composition.

[0033] Component (C): Epoxy Compound The component (C) is a compound having one or more epoxy groups. The component (C) may be a compound having two or more epoxy groups. The component (C) may contain an aliphatic epoxy compound (hereinafter sometimes referred to as "component (C1)"). The component (C) may contain an alicyclic epoxy compound (hereinafter sometimes referred to as "component (C2)"). The component (C) may contain both the component (C1) and the component (C2).

[0034] When component (C) contains component (C1), the compatibility and crosslinkability of the adhesive composition tend to be improved. Component (C1) may be an aliphatic diglycidyl ether having at least one aliphatic group (linking group) selected from the group consisting of an alkylene group, an oxyalkylene group, and a cycloalkylene group. Component (C1) may also be an epoxy compound having no aromatic ring.

[0035] Examples of aliphatic diglycidyl ethers include diglycidyl ethers having an alkylene group, such as ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, neopentyl glycol diglycidyl ether, 1,4-butanediol diglycidyl ether, and 1,6-hexanediol diglycidyl ether; diglycidyl ethers having an oxyalkylene group, such as diethylene glycol diglycidyl ether, tripropylene glycol diglycidyl ether, and polyethylene glycol diglycidyl ether; and diglycidyl ethers having a cycloalkylene group, such as hydrogenated bisphenol A diglycidyl ether, 1,4-cyclohexanedimethanol diglycidyl ether, and diglycidyl-1,2-cyclohexanedicarboxylate.

[0036] The content of the component (C1) may be 10% by mass or more, 20% by mass or more, 30% by mass or more, 40% by mass or more, 50% by mass or more, or 60% by mass or more, and may be 100% by mass or less, 90% by mass or less, or 85% by mass or less, based on the total amount of the component (C).

[0037] Component (C2) is a compound having an epoxy group (e.g., an epoxycyclohexyl group) formed together with the two carbon atoms constituting the alicyclic ring. When component (C) contains component (C2), the heat resistance and crosslinkability of the adhesive composition tend to be improved. Commercially available products of component (C2) include, for example, Celloxide 8010, Celloxide 2021P, and Celloxide 2081 (trade names, all manufactured by Daicel Corporation). Furthermore, component (C2) may be an epoxy compound that does not have an aromatic ring.

[0038] The content of the (C2) component, based on the total amount of the (C) component, may be 0% by mass or more, 10% by mass or more, or 15% by mass or more, and may be 90% by mass or less, 80% by mass or less, 70% by mass or less, 60% by mass or less, 50% by mass or less, or 40% by mass or less.

[0039] In addition to the components (C1) and (C2), the component (C) may contain another epoxy compound (hereinafter, sometimes referred to as "component (C3)") to the extent that the effects of the present disclosure are not impaired. Examples of the other epoxy compound include epoxy compounds having an aromatic ring.

[0040] Examples of the component (C3) include phthalic acid diglycidyl ester, bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol AD ​​type epoxy resin, bisphenol S type epoxy resin, phenol novolac type epoxy resin, cresol novolac type epoxy resin, biphenyl type epoxy resin, and biphenyl aralkyl type epoxy resin.

[0041] The content of the component (C3) may be 0 to 40 mass %, 0 to 30 mass %, 0 to 20 mass %, or 0 to 10 mass % based on the total amount of the component (C).

[0042] The content of the component (C) (total amount of the components (C1), (C2), and (C3)) may be 5% by mass or more, 10% by mass or more, 15% by mass or more, or 20% by mass or more, and may be 50% by mass or less, 45% by mass or less, or 40% by mass or less, based on the total amount of the adhesive composition.

[0043] Component (D): Crosslinking Agent The component (D) contains a (meth)acrylic resin having a first structural unit derived from a (meth)acrylate having a fluorine-containing organic group and a second structural unit derived from a (meth)acrylate having a cyclic ether group. The crosslinking agent may consist of the (meth)acrylic resin.

[0044] The (meth)acrylate having a fluorine organic group that provides the first structural unit may be, for example, a (meth)acrylate having a fluoroalkyl group. Examples of the (meth)acrylate having a fluoroalkyl group include those exemplified for the component (A1).

[0045] In the (meth)acrylate having a fluoroalkyl group, the number of carbon atoms in the fluoroalkyl group may be, for example, 1 to 10, 2 or more, or 8 or less, 6 or less, 4 or less, or 3 or less, from the viewpoint of compatibility with the component (A) or a polymer thereof.

[0046] In a (meth)acrylate having a fluoroalkyl group, the proportion of fluorine atoms in the fluoroalkyl group may be, for example, 100% or less, 80% or less, or 70% or less, or may be 30% or more, 40% or more, or 50% or more, from the viewpoint of compatibility with component (A) or a polymer thereof.

[0047] The content of the first structural unit may be 10 to 90 mol%, 20 to 90 mol%, 30 to 90 mol%, or 40 to 90 mol%, based on all structural units of the (meth)acrylic resin, from the viewpoint of compatibility with the component (A) or a polymer thereof.

[0048] The (meth)acrylate having a cyclic ether group that provides the second structural unit may be, for example, at least one selected from the group consisting of (meth)acrylates having an epoxy group, (meth)acrylates having an alicyclic epoxy group, and (meth)acrylates having an oxetanyl group. Examples of (meth)acrylates having an epoxy group include glycidyl (meth)acrylate. Examples of (meth)acrylates having an alicyclic epoxy group include 3,4-epoxycyclohexylmethyl (meth)acrylate. Examples of (meth)acrylates having an oxetanyl group include (3-ethyloxetan-3-yl)methyl (meth)acrylate.

[0049] In the (meth)acrylic resin, the content of the second structural unit may be 10 to 90 mol %, 10 to 80 mol %, 10 to 70 mol %, or 10 to 60 mol % based on all structural units of the (meth)acrylic resin, from the viewpoint of crosslinkability with the component (B).

[0050] The (meth)acrylic resin may have structural units other than the first structural unit and the second structural unit, as long as the effects of the present disclosure are not impaired. Examples of compounds that provide such structural units include monofunctional (meth)acrylates having one (meth)acryloyl group, such as alkyl(meth)acrylates having an alkyl group, (meth)acrylates having an aromatic group, (meth)acrylates having an alicyclic group, (meth)acrylates having a nitrogen-oxygen heterocyclic group, alkoxypolyalkylene glycol (meth)acrylates, polyalkylene glycol mono(meth)acrylates, and (meth)acrylates having a siloxane skeleton; polyfunctional (meth)acrylates having two or more (meth)acryloyl groups, such as aliphatic poly(meth)acrylates and aromatic poly(meth)acrylates; and compounds having a radical polymerizable group other than a (meth)acryloyl group, such as styrene, 4-methylstyrene, vinylpyridine, vinylpyrrolidone, vinyl acetate, cyclohexylmaleimide, and phenylmaleimide.

[0051] The content of the other structural units may be 0 to 40 mol %, 0 to 30 mol %, 0 to 20 mol %, or 0 to 10 mol % based on all structural units of the (meth)acrylic resin.

[0052] The weight average molecular weight (Mw) of the (meth)acrylic resin may be, for example, 1,000 to 200,000, 3,000 or more, 5,000 or more, or 10,000 or more, and may be 150,000 or less, 100,000 or less, 60,000 or less, or 50,000 or less. The weight average molecular weight (Mw) is a polystyrene-equivalent value measured by gel permeation chromatography (GPC) using a calibration curve with standard polystyrene. The weight average molecular weight (Mw) can be measured, for example, by the method described in the Examples.

[0053] The (meth)acrylic resin can be obtained, for example, by radical polymerization using a solution polymerization method. More specifically, it can be obtained by polymerizing, in a solvent, monomers including a (meth)acrylate having a cyclic ether group and a (meth)acrylate having a fluorine-containing organic group.

[0054] The solvent can be appropriately selected from organic solvents commonly used in the field of radical polymerization. The solvent may be a solvent having a cyclic ether group (epoxy group or oxetanyl group) but no radical polymerizable group, since the crosslinking agent ((meth)acrylic resin) can be directly used in the polymerization reaction for the curing reaction of a curable resin such as a compound (epoxy resin) having a cyclic ether group without isolating the crosslinking agent ((meth)acrylic resin) (without removing or replacing the solvent). Examples of the solvent include those commonly used in the field of epoxy resin diluents. Examples of the solvent include epoxy resins that are liquid at 25°C. The solvent may be, for example, an aliphatic diglycidyl ether, from the viewpoint of being usable as component (C1). Examples of the aliphatic diglycidyl ether include those exemplified for component (C1).

[0055] In this specification, the radical polymerizable group refers to a group having a carbon-carbon double bond. Examples of the radical polymerizable group include a (meth)acryloyl group, a vinyl group, an allyl group, a styryl group, an alkenyl group, an alkenylene group, and a maleimide group.

[0056] The amount of the solvent used can be appropriately determined depending on the type of monomer, reaction conditions, the proportion of solids in the (meth)acrylic resin solution, and the like.

[0057] When polymerizing the monomers, a thermal radical generator, an additive, etc. may be added as needed.

[0058] Examples of the thermal radical generator include organic peroxides such as cumene hydroperoxide, diisopropylbenzene hydroperoxide, di-t-butyl peroxide, lauroyl peroxide, benzoyl peroxide, t-butylperoxyisopropyl carbonate, t-amylperoxy-2-ethylhexanoate, and t-butylperoxy-2-ethylhexanoate; and azo compounds such as 2,2'-azobis(isobutyronitrile), 1,1'-azobis(cyclohexanecarbonitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), and dimethyl-2,2'-azobis(2-methylpropionate).

[0059] The amount of the thermal radical generator added may be appropriately set depending on the type of monomer, reaction conditions, etc., and is not particularly limited, but may be 100 to 200,000 ppm by mass, 100 to 100,000 ppm by mass, 1,000 to 100,000 ppm by mass, 1,000 to 50,000 ppm by mass, 3,000 to 30,000 ppm by mass, or 10,000 to 80,000 ppm by mass, based on the total amount of the monomers.

[0060] Examples of the additives include chain transfer agents, antioxidants, light stabilizers, weather stabilizers, ultraviolet absorbers, radical scavengers, etc. The amount of the additives added is not particularly limited, but may be 0.001 to 2% by mass or 0.005 to 1% by mass based on the total amount of the monomers.

[0061] The polymerization temperature may be 40 to 120° C., 50 to 100° C., or 60 to 90° C. The polymerization time may be 0.1 to 24 hours, 0.5 to 20 hours, or 1 to 12 hours.

[0062] The content of component (D) may be 5% by mass or more, 8% by mass or more, 10% by mass or more, 12% by mass or more, or 15% by mass or more, based on the total amount of the adhesive composition, and may be 40% by mass or less, 35% by mass or less, or 30% by mass or less.

[0063] Component (E): Photoacid Generator The component (E) may be a component that generates an acid that initiates polymerization upon irradiation with light having a wavelength in the range of 150 to 750 nm or light having a wavelength in the range of 254 to 405 nm. The component (E) may be a component that generates radicals and an acid upon irradiation with ultraviolet light.

[0064] Examples of the component (E) include onium salts such as sulfonium salts, phosphonium salts, ammonium salts, diazonium salts, iodonium salts, and anilinium salts. Examples of the anion of the onium salt include BF ４ － , B.R. ４ － (R represents a phenyl group substituted with two or more fluorine atoms or two or more trifluoromethyl groups), PF ６ － , SbF ６ － , AsF ６ － , S.O. ４ R － (R represents an alkyl group), etc.

[0065] Examples of commercially available products of component (E) include CPI-100P, CPI-110P, CPI-101A, CPI-200K, and CPI-210S (all manufactured by San-Apro Ltd.), UVI-6990, UVI-6992, and UVI-6976 (all manufactured by Dow Chemical Japan Ltd.), and SP-150, SP-152, SP-170, SP-172, and SP-300 (all manufactured by ADEKA Corporation).

[0066] The content of the (E) component may be, for example, 0.1 parts by mass or more, 0.5 parts by mass or more, or 1 part by mass or more, and may be 15 parts by mass or less, 10 parts by mass or less, or 8 parts by mass or less, relative to 100 parts by mass of the total amount of the (C) component and the (D) component.

[0067] Component (F): Coupling Agent Component (F) may be, for example, a silane coupling agent. The silane coupling agent may be, for example, a compound having a hydrolyzable silyl group and a functional group capable of reacting with either a (meth)acrylate compound or an epoxy compound. The hydrolyzable silyl group is, for example, a group having a silicon atom and 1 to 3 alkoxy groups bonded to the silicon atom. The alkoxy group bonded to the silicon atom may have, for example, 1 to 4 carbon atoms. Examples of functional groups include amino groups such as primary amino groups and secondary amino groups, epoxy groups, mercapto groups, (meth)acryloyl groups, and isocyanate groups. The functional group may be an isocyanate group, as this makes it easier to achieve the effects of the present disclosure more fully. That is, component (F) may contain a silane coupling agent having an isocyanate group. In this specification, a compound having a hydrolyzable silyl group and a (meth)acryloyl group, and a compound having a hydrolyzable silyl group and an epoxy group are classified as a silane coupling agent.

[0068] Commercially available silane coupling agents include, 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, KBM-803, and KBE-9007N (trade names, manufactured by Shin-Etsu Chemical Co., Ltd.).

[0069] The content of component (F) may be 0.1 mass % or more, 0.2 mass % or more, or 0.3 mass % or more, and may be 10 mass % or less, 8 mass % or less, 5 mass % or less, 3 mass % or less, or 2 mass % or less, based on the total amount of the adhesive composition.

[0070] Component (G): Photoradical Generator The component (G) may be a component that generates radicals upon irradiation with light having a wavelength in the range of 150 to 750 nm or light having a wavelength in the range of 254 to 405 nm. The component (G) may be a component that generates radicals upon irradiation with ultraviolet light. The component (G) may be a component that acts mainly on the component (A).

[0071] The component (G) decomposes under light to generate free radicals. In other words, the component (G) is a compound that generates radicals when external light energy is applied. The component (G) may be a compound having an oxime ester structure, a bisimidazole structure, an acridine structure, an α-aminoalkylphenone structure, an aminobenzophenone structure, an N-phenylglycine structure, an acylphosphine oxide structure, a benzyl dimethyl ketal structure, an α-hydroxyalkylphenone structure, or the like. The component (G) may be, for example, a compound having a structure selected from the group consisting of an oxime ester structure, an α-aminoalkylphenone structure, and an acylphosphine oxide structure, or may be a compound having an acylphosphine oxide structure.

[0072] Specific examples of the compound having an oxime ester structure include 1-phenyl-1,2-butanedione-2-(o-methoxycarbonyl)oxime, 1-phenyl-1,2-propanedione-2-(o-methoxycarbonyl)oxime, 1-phenyl-1,2-propanedione-2-(o-ethoxycarbonyl)oxime, 1-phenyl-1,2-propanedione-2-o-benzoyloxime, 1,3-diphenylpropanetrione-2-(o-ethoxycarbonyl)oxime, and 1-phenyl-3-ethoxypropanetrione-2-(o-benzoyl)oxime.

[0073] Specific examples of compounds having an α-aminoalkylphenone structure include 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one, 2-benzyl-2-dimethylamino-1-morpholinophenyl)-butanone-1, and the like.

[0074] Specific examples of compounds having an acylphosphine oxide structure include bis(2,6-dimethoxybenzoyl)-2,4,4-trimethyl-pentylphosphine oxide, bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, and diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide.

[0075] The content of the component (G) may be, for example, 0.1 to 15 parts by mass, 0.5 to 10 parts by mass, or 1 to 8 parts by mass per 100 parts by mass of the total amount of the components (A) and (B).

[0076] The adhesive composition may contain other components, such as an antioxidant and a photosensitizer.

[0077] The content of the antioxidant may be 0.1 to 10 mass % based on the total amount of the adhesive composition.

[0078] Examples of photosensitizers include benzoflavin, anthracene, pyrene, thioxanthone, benzophenone, anthraquinone, camphorquinone, coumarin dyes, and oxazole compounds.

[0079] The content of the photosensitizer may be 0.01 to 10% by mass, or may be 0.01 to 1% by mass, based on the total amount of the adhesive composition.

[0080] The adhesive composition can be prepared by mixing (or kneading) components (A), (B), (C), (D), and (E), as well as components (F), (G), and other components. Mixing can be carried out using an appropriate combination of a conventional mixer and a dispersing machine such as a planetary mixer. During mixing, degassing treatment, such as vacuum degassing, may be performed as appropriate.

[0081] The adhesive composition can form an adhesive joint (adhesive layer) that has excellent adhesion to various adherends. The adhesive joint can be obtained by placing the adhesive composition at a predetermined position and irradiating the placed adhesive composition with light. The adhesive joint contains a cured product of the adhesive composition. The light irradiation may be performed directly on the adhesive composition or may be performed via a transparent resin, glass, or the like.

[0082] The light for irradiation may be light having a wavelength in the range of 150 to 750 nm or light having a wavelength in the range of 254 to 405 nm, or may be ultraviolet light.

[0083] Examples of light sources for light irradiation include low-pressure mercury lamps, medium-pressure mercury lamps, high-pressure mercury lamps, ultra-high-pressure mercury lamps, xenon lamps, metal halide lamps, and LED light sources. The integrated light amount of light irradiation can be appropriately set, for example, from 100 to 5000 mJ / cm. ２ It may be.

[0084] The atmosphere for light irradiation is not particularly limited, but may be, for example, an air atmosphere or an inert gas atmosphere such as nitrogen or argon.

[0085] The infrared transmittance of the cured product of the adhesive composition may be 70% or more, 75% or more, 80% or more, 85% or more, or 90% or more. The infrared transmittance can be determined by measuring the transmittance at a wavelength of 1310 nm using a spectrophotometer. A measurement sample can be prepared by the following procedure. First, a 500 μm thick spacer film is placed on a release film so that the dimensions are 50 mm wide x 50 mm long and 500 μm thick, and the adhesive composition is applied to the release film. Next, an LED lamp (manufactured by Ushio Inc., wavelength: 365 nm) is used to illuminate the cured product at 30 mW / cm. ２ The adhesive composition is irradiated with light for 30 seconds, and 600 seconds after the end of the light irradiation, the adhesive composition is peeled off from the release film to obtain a measurement sample. In addition, glass used as the substrate can be used as a baseline.

[0086] [Adhesive] In one embodiment, the adhesive comprises a first adherend, a second adherend, and an adhesive joint that bonds the first adherend and the second adherend to each other. The adhesive joint contains a cured product of the adhesive composition described above.

[0087] Examples of the first and second adherends include organic materials such as polyolefin resins, polyamide resins, ABS (acrylonitrile butadiene styrene) resins, PC (polycarbonate) resins, PET (polyethylene terephthalate) resins, PPS (polyphenylene sulfide) resins, acrylic resins, and transparent resins; inorganic materials such as steel, stainless steel, metals (aluminum, copper, nickel, chromium, etc.) or alloys of these metals, glass, and silicon wafers; wood; and rubber. Examples of the first and second adherends 1 and 2 include composites of the above-mentioned plastics and inorganic materials. Either the first or second adherend 1 or 2 may be a transparent resin or glass from the viewpoint of light irradiation.

[0088] The thickness of the first adherend and the second adherend may be, for example, 0.1 to 2.0 mm, 0.1 to 1.0 mm, or 0.1 to 0.5 mm.

[0089] The adhesive can be obtained, for example, by a method including the steps of applying an adhesive composition onto a first adherend to form an adhesive joint containing the adhesive composition, placing a second adherend on the adhesive joint precursor to produce a laminate, and irradiating the adhesive joint of the laminate with light to form an adhesive joint containing a cured product of the adhesive composition.

[0090] The adhesive composition can be applied using a knife coater, a roll coater, an applicator, a comma coater, a die coater, a dispenser, or the like.

[0091] The light irradiation conditions (light wavelength, light source, integrated light amount, etc.) for the adhesive portion of the laminate may be the same as the light irradiation conditions (light wavelength, light source, integrated light amount, etc.) described above.

[0092] The thickness of the adhesive joint containing the cured product of the adhesive composition may be, for example, 0.01 to 1.0 mm, 0.01 to 0.5 mm, or 0.01 to 0.2 mm.

[0093] The present disclosure will be specifically described below using examples, but the present disclosure is not limited to these examples.

[0094] [Synthesis of (meth)acrylic resin (crosslinking agent)] The following raw materials were prepared. (Meth)acrylate compound M-3F: 2,2,2-trifluoroethyl methacrylate (Light Ester M-3F, Kyoeisha Chemical Co., Ltd.) TTA-15: 3,4-epoxycyclohexylmethyl methacrylate (Sun Chemical Co., Ltd.) Thermal radical generator V-601: dimethyl-2,2'-azobis(2-methylpropionate) (Fujifilm Wako Pure Chemical Industries, Ltd.) Solvent NPG(D): neopentyl glycol diglycidyl ether (Epogose NPG(D)) (Yokkaichi Synthetic Co., Ltd.)

[0095] Preparation Example 1: 144.38 g of M-3F and 42.13 g of TTA-15 (molar ratio of M-3F / TTA-15=80% / 20%), 5.78 g of V-601, and 24.11 g of NPG (D) were mixed to prepare a mixture (a). Separately, 1.87 g of V-601 was dissolved in 7.46 g of NPG (D) to prepare a solution (b).

[0096] A flask equipped with a stirrer, dropping funnel, condenser, thermometer, and gas inlet tube was charged with 162.44 g of NPG (D), and the mixture was stirred under a nitrogen atmosphere while replacing the gas, and the temperature was raised to 85°C. Next, mixture (a) was added dropwise to the flask over 2 hours. After the dropwise addition was completed, the mixture was stirred at 85°C for 20 minutes, and then solution (b) was added and stirred for an additional 7 hours. Next, while continuing to stir, the mixture was cooled to room temperature (25°C) to obtain a solution containing the (meth)acrylic resin (crosslinking agent A) of Production Example 1. The solids concentration was 50% by mass.

[0097] [Evaluation of (meth)acrylic resin (crosslinking agent)] (Measurement of viscosity (25°C)) The viscosity of a solution containing a (meth)acrylic resin at 25°C was measured at a rotation speed of 10 rpm after setting a sample volume of 0.5 to 1.0 mL in an E-type viscometer (manufactured by Toki Sangyo Co., Ltd., product name: VISCOMETER-TV22, applicable cone-plate rotor: 3° × R17.65). The results are shown in Table 1.

[0098] (Measurement of weight average molecular weight (Mw)) A solution containing a (meth)acrylic resin was dissolved in tetrahydrofuran (THF) to prepare a 0.2 mass % THF solution as a sample for Mw measurement. Mw was measured by gel permeation chromatography (GPC) and calculated by conversion using a calibration curve of standard polystyrene. The GPC conditions are shown below. The results are also shown in Table 1. Measuring apparatus: Shodex (registered trademark) GPC-101 (manufactured by Resonac Co., Ltd.) Detector: Differential refractometer Shodex RI-71S (manufactured by Resonac Co., Ltd.) Column: Shodex LF-804 + LF-804 (manufactured by Resonac Co., Ltd.) Column temperature: 40°C Eluent: tetrahydrofuran (THF) Flow rate: 1 mL / min

[0099]

[0100] [Preparation of Adhesive Compositions] <Examples 1 to 13 and Comparative Example 1> The adhesive compositions of Examples 1 to 13 and Comparative Example 1 containing component (A), component (B), component (C), component (D), component (E), and component (F) were prepared by mixing the components (parts by mass) shown in Tables 2 and 3 in a planetary mixer (5 minutes / 1500 rpm).

[0101] The details of each raw material are as follows: Component (A): Monofunctional (meth)acrylate compound V-13F: 1H,1H,2H,2H-tridecafluorooctyl acrylate (2-(perfluorohexyl)ethyl acrylate) (manufactured by Osaka Organic Chemical Industry Ltd.) M3F: 2,2,2-trifluoroethyl acrylate (manufactured by Kyoeisha Chemical Co., Ltd.) V-8F: 1H,1H,5H-octafluoropentyl acrylate (manufactured by Osaka Organic Chemical Industry Ltd.) 4-HBA: 4-hydroxybutyl acrylate (manufactured by Osaka Organic Chemical Industry Ltd.) 2-MTA: 2-methoxyethyl acrylate (manufactured by Osaka Organic Chemical Industry Ltd.) Component (B): Multifunctional (meth)acrylate compound A-9300S: Tris(2-acryloxyethyl)isocyanurate (trifunctional, isocyanuric acid EO-modified tri(meth)acrylate, manufactured by Shin-Nakamura Chemical Co., Ltd.) M-402: Dipentaerythritol hexaacrylate (hexafunctional, manufactured by Toagosei Co., Ltd.) M-305: Pentaerythritol tri- and tetraacrylate (mixture of trifunctional and tetrafunctional, manufactured by Toagosei Co., Ltd.) 160S: Trimethylolpropane ethoxy triacrylate (TMPEOTA) (trimethylolpropane EO-modified triacrylate, trifunctional, manufactured by Daicel-Allnex Corporation) A-NPG: Neopentyl glycol diacrylate (bifunctional, manufactured by Shin-Nakamura Chemical Co., Ltd.) Component (C): Epoxy compound NPG (D): Neopentyl glycol diglycidyl ether (Epogose NPG (D)) (manufactured by Yokkaichi Synthetic Co., Ltd.) 2021P: 3',4'-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate (Celloxide 2021P, manufactured by Daicel Corporation) Component (D): Crosslinking agent Crosslinker A: (meth)acrylic resin of Production Example 1 Component (E): photoacid generator CPI-110P: sulfonium salt (manufactured by San-Apro Co., Ltd.) Component (F): coupling agent KBM-403: 3-glycidoxypropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd.) KBE-9007N: 3-isocyanatopropyltriethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd.)

[0102] The amounts of the (meth)acrylic resin (crosslinking agent A) of Production Example 1, which is the component (D), and NPG (D), which is the component (C), added were adjusted using the solution containing the (meth)acrylic resin (crosslinking agent) obtained above.

[0103] [Evaluation of Adhesive Composition] (Measurement of Shear Strength Before and After Wet Heat Test) A 50 μm thick spacer film was placed on a glass slide to give dimensions of 5 mm wide x 5 mm thick x 50 μm thick, and the adhesive composition was applied to the glass slide. A glass chip with a width of 7 mm x 7 mm and a thickness of 1.0 mm was placed on the applied adhesive composition, and an LED lamp (manufactured by Ushio Inc., wavelength: 365 nm) was used to illuminate the adhesive composition at 30 mW / cm. ２ The adhesive composition was irradiated with light for 30 seconds, and the sample taken 270 seconds after the end of light irradiation was used as the measurement sample. Multiple measurement samples were prepared for measuring the shear strength after the moist heat test. The shear strength of the measurement samples was measured using a bond tester (Nordson, product name: DAGE4000) at a shear rate of 180 mm / min to measure the initial shear strength. The results are shown in Tables 2 and 3. Next, a measurement sample different from the measurement sample used to measure the initial shear strength was subjected to a moist heat test (durability test under conditions of a temperature of 85°C, a humidity of 85% RH, and a time of 168 hours) in a constant temperature and humidity chamber (ETAC, product name: SXN402-E) to obtain a measurement sample after the moist heat test. The measurement sample after the moist heat test was measured under the same conditions as above, and the shear strength after the moist heat test was measured. The strength retention rate (%) of adhesive strength was calculated from the initial shear strength and the shear strength after the moist heat test according to the following formula. The results are shown in Tables 2 and 3. Strength retention rate (%) of adhesive strength = (shear strength after moist heat test / initial shear strength) x 100

[0104]

[0105]

[0106] As shown in Tables 2 and 3, the adhesive compositions of Examples 1 to 13 containing component (B) were superior in terms of strength retention (strength maintenance rate) of the adhesive strength of the cured product compared to the adhesive composition of Comparative Example 1, which did not contain component (B). Furthermore, a comparison of Examples 1 and 2 with Examples 3 to 13 revealed that the use of component (F) (silane coupling agent) tended to further improve the strength retention of the adhesive strength. Furthermore, a comparison of Examples 3, 5, and 7 with Examples 4, 6, and 8 revealed that the use of a silane coupling agent having an isocyanate group as component (F) tended to further improve the strength retention of the adhesive strength. This tendency was also observed in Examples 9 to 13. From the above, it was confirmed that the adhesive composition of the present disclosure can provide a cured product with a sufficiently high strength retention of adhesive strength before and after a moist heat test.

Claims

1. An adhesive composition comprising a monofunctional (meth)acrylate compound, a polyfunctional (meth)acrylate compound, an epoxy compound, a crosslinking agent, and a photoacid generator, wherein the monofunctional (meth)acrylate compound comprises a (meth)acrylate having a fluorine-containing organic group, and the crosslinking agent comprises a (meth)acrylic resin having a first structural unit derived from the (meth)acrylate having a fluorine-containing organic group and a second structural unit derived from a (meth)acrylate having a cyclic ether group.

2. The adhesive composition according to claim 1, wherein the polyfunctional (meth)acrylate compound includes a tri- or higher functional (meth)acrylate compound.

3. The adhesive composition according to claim 1, wherein the epoxy compound comprises an aliphatic epoxy compound.

4. The adhesive composition according to claim 3, wherein the epoxy compound further comprises an alicyclic epoxy compound.

5. An adhesive comprising a first adherend, a second adherend, and an adhesive part that adheres the first adherend and the second adherend to each other, the adhesive part containing a cured product of the adhesive composition according to any one of claims 1 to 4.

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