Adhesive agent composition and bonded object

Abstract

Disclosed is an adhesive agent composition. The adhesive agent composition contains a (meth)acrylate compound, an epoxy compound, an oxetane compound, and a photoacid generator. The adhesive agent composition optionally further contains a (meth)acrylic resin having a cation-polymerizable group. The epoxy compound optionally contains an alicyclic epoxy compound.

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] However, the cured products of conventional adhesive compositions do not have sufficient surface hardness, and there is still room for improvement.

[0005] Therefore, a main object of the present disclosure is to provide an adhesive composition that is capable of forming a cured product with excellent surface hardness.

[0006] The present disclosure provides adhesive compositions according to [1] to [5] and an adhesive structure according to [6]. [1] An adhesive composition containing a (meth)acrylate compound, an epoxy compound, an oxetane compound, and a photoacid generator. [2] The adhesive composition according to [1], in which the epoxy compound comprises an alicyclic epoxy compound. [3] The adhesive composition according to [1] or [2], further containing a (meth)acrylic resin having a cationically polymerizable group. [4] The adhesive composition according to any one of [1] to [3], in which the (meth)acrylate compound comprises at least one selected from the group consisting of monofunctional (meth)acrylate compounds and difunctional (meth)acrylate compounds. [5] The adhesive composition according to [4], in which the (meth)acrylate compound further comprises a trifunctional or higher functional (meth)acrylate compound. [6] 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 [5].

[0007] According to the present disclosure, an adhesive composition is provided that can form a cured product with excellent surface hardness. Cured products of some types of adhesive compositions tend to exhibit a low refractive index (e.g., 1.500 or less (room temperature (25°C), wavelength: 589 nm)). Furthermore, according to the present disclosure, an adherend using such an adhesive composition is provided.

[0008] Hereinafter, embodiments of the present disclosure will be described in detail, but the present disclosure is not limited to the following embodiments.

[0009] 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 numerical ranges 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 the expression "A to B," the numerical values ​​A and B at both ends are included in the numerical range as the lower and upper limits, respectively. In this specification, for example, the expression "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 expression "10 or less" means "10" and "a number less than 10," and this also applies when the numerical values ​​are different.

[0010] 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, a bifunctional (meth)acrylate compound refers to a compound having two (meth)acryloyl groups, and a trifunctional or higher functional (meth)acrylate compound refers to a compound having three or more (meth)acryloyl groups. The (meth)acrylate compound may be a compound that does not have an epoxy group or an oxetanyl group. The (meth)acrylic resin refers to a (co)polymer having at least a structural unit derived from a (meth)acrylate compound. The (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.

[0011] Unless otherwise specified, the materials exemplified below may be used alone or in combination of two or more. When a plurality of substances corresponding to each component are present in the composition, the content of each component in the composition means the total amount of the plurality of substances present in the composition unless otherwise specified.

[0012] [Adhesive Composition] The adhesive composition of one embodiment contains a (meth)acrylate compound (hereinafter sometimes referred to as "component (A)"), an epoxy compound (hereinafter sometimes referred to as "component (B)"), an oxetane compound (hereinafter sometimes referred to as "component (C)"), and a photoacid generator (hereinafter sometimes referred to as "component (D)"). The adhesive composition may also contain a (meth)acrylic resin having a cationically polymerizable group (hereinafter sometimes referred to as "component (E)").

[0013] Component (A): (Meth)acrylate Compound Examples of the component (A) include a monofunctional (meth)acrylate compound (hereinafter sometimes referred to as "component (A1)"), a bifunctional (meth)acrylate compound (hereinafter sometimes referred to as "component (A2)"), and a tri- or higher functional (meth)acrylate compound (hereinafter sometimes referred to as "component (A3)"). The component (A) may contain at least one compound selected from the group consisting of components (A1) and (A2), or may further contain component (A3) in addition to at least one compound selected from the group consisting of components (A1) and (A2).

[0014] Examples of the component (A1) 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; and alkyl (meth)acrylates such as 3-butenyl (meth)acrylate. alkenyl (meth)acrylates having an alkenyl group; (meth)acrylates having an aromatic group such as benzyl (meth)acrylate and phenoxyethyl (meth)acrylate; (meth)acrylates having an alicyclic group such as cyclohexyl (meth)acrylate, isobornyl (meth)acrylate and dicyclopentanyl (meth)acrylate; (meth)acrylates having a heterocyclic group such as 4-(meth)acryloylmorpholine; 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate; (meth)acrylates having a hydroxyalkyl group such as propyl (meth)acrylate and 4-hydroxybutyl (meth)acrylate; (meth)acrylates having an alkoxyalkyl group such as 2-methoxyethyl acrylate and 2-ethoxyethyl (meth)acrylate; (meth)acrylates having a fluoroalkyl group such as 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 and perfluorohexylmethyl (meth)acrylate; alkoxypolyalkylene glycol (meth)acrylates such as methoxyethylene glycol (meth)acrylate, methoxytetraethylene glycol (meth)acrylate, methoxyhexaethylene glycol (meth)acrylate and methoxyoctaethylene glycol (meth)acrylate;Examples of the polyalkylene glycol mono(meth)acrylate include tetraethylene glycol mono(meth)acrylate, hexaethylene glycol mono(meth)acrylate, and octapropylene glycol mono(meth)acrylate; and (meth)acrylates having a siloxane skeleton.

[0015] From the viewpoint of the curability and adhesion of the adhesive composition, the component (A1) may contain a (meth)acrylate having a hydroxyalkyl group. Furthermore, from the viewpoint of the refractive index of a cured product of the adhesive composition, the component (A1) may contain a (meth)acrylate having an alkoxyalkyl group. The component (A1) may contain at least one selected from the group consisting of a (meth)acrylate having a hydroxyalkyl group and a (meth)acrylate having an alkoxyalkyl group.

[0016] Examples of the component (A2) include ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, tetrapropylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, ethoxylated polypropylene glycol di(meth)acrylate, 1,3-butanediol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, 3-methyl-1,5-pentanediol di(meth)acrylate, and 1,6-hexanediol di(meth)acrylate. difunctional aliphatic (meth)acrylates such as ethoxylated bisphenol A di(meth)acrylate, 1,10-decanediol di(meth)acrylate, glycerin di(meth)acrylate, tricyclodecane dimethanol (meth)acrylate, and ethoxylated 2-methyl-1,3-propanediol di(meth)acrylate; ethoxylated bisphenol A di(meth)acrylate, propoxylated bisphenol A di(meth)acrylate, and ethoxylated propoxylated bisphenol A di(meth)acrylate; and bifunctional aromatic (meth)acrylates such as bisphenol F di(meth)acrylate, ethoxylated bisphenol F di(meth)acrylate, propoxylated bisphenol F di(meth)acrylate, ethoxylated propoxylated bisphenol F di(meth)acrylate, ethoxylated fluorene di(meth)acrylate, propoxylated fluorene di(meth)acrylate, and ethoxylated propoxylated fluorene di(meth)acrylate.

[0017] When the component (A) contains the component (A2), a polymer having a network structure is formed together with the component (A1), which tends to further improve the surface hardness of the cured product of the adhesive composition. From the viewpoint of the curability and adhesion of the adhesive composition, the component (A2) may contain a bifunctional aliphatic (meth)acrylate.

[0018] The content of the (A1) component, based on the total amount of the (A1) component and the (A2) component, may be 5% by mass or more, 10% by mass or more, or 15% by mass or more, and may be 100% by mass or less, 80% by mass or less, 60% by mass or less, 40% by mass or less, or 30% by mass or less.

[0019] The content of the (A2) component, based on the total amount of the (A1) component and the (A2) component, may be 0% by mass or more, 20% by mass or more, 40% by mass or more, 60% by mass or more, or 70% by mass or more, and may be 95% by mass or less, 90% by mass or less, or 85% by mass or less.

[0020] The total content of the (A1) component and the (A2) component may be 80% by mass or more, 85% by mass or more, or 90% by mass or more, and may be 100% by mass or less, 98% by mass or less, or 96% by mass or less, based on the total amount of the (A) component.

[0021] Examples of the component (A3) include trifunctional (meth)acrylates such as trimethylolpropane 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, and ditrimethylolpropane tetra(meth)acrylate. tetrafunctional (meth)acrylates such as dipentaerythritol tetra(meth)acrylate and 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.

[0022] When component (A) contains component (A3), a polymer having a network structure is formed together with components (A1) and (A2), which tends to further improve the surface hardness of the cured product of the adhesive composition. Component (A3) may be a decafunctional or less (meth)acrylate compound, an octafunctional or less (meth)acrylate compound, or a hexafunctional or less (meth)acrylate compound.

[0023] The content of the (A3) component may be 0% by mass or more, 2% by mass or more, or 4% by mass or more, and may be 20% by mass or less, 15% by mass or less, or 10% by mass or less, based on the total amount of the (A) component.

[0024] The content of the component (A) (total of the components (A1), (A2), and (A3)) may be 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.

[0025] Component (B): Epoxy Compound Component (B) is a compound having one or more epoxy groups. Component (B) may be a compound that does not have a (meth)acryloyl group or an oxetanyl group. Component (B) may be a compound that has two or more epoxy groups. Note that component (E), described below, is not included in component (B). Component (B) may contain an alicyclic epoxy compound (hereinafter sometimes referred to as "component (B1)") or an aliphatic epoxy compound (hereinafter sometimes referred to as "component (B2)"). Component (B) may contain both component (B1) and component (B2).

[0026] The component (B1) is a compound having an alicyclic structure and one or more epoxy groups in the molecule. Depending on its structure, the component (B1) can be broadly classified into, for example, a first alicyclic epoxy compound having an epoxy group (e.g., an epoxycyclohexyl group) formed together with the two carbon atoms constituting the alicyclic ring, and a second alicyclic epoxy compound having an epoxy-containing group such as a glycidyl group bonded to the alicyclic structure. In the present disclosure, either the first alicyclic epoxy compound or the second alicyclic epoxy compound may be used alone, or both may be used in combination. The component (B1) may contain a first alicyclic epoxy compound from the viewpoint of heat resistance and crosslinkability of the adhesive composition, or may contain a second alicyclic epoxy compound from the viewpoint of surface hardness of the adhesive composition.

[0027] Commercially available examples of the first alicyclic epoxy compound include CELLOXIDE 8010, CELLOXIDE 2021P, and CELLOXIDE 2081 (trade names, all manufactured by Daicel Corporation). The first alicyclic epoxy compound may be an epoxy compound having no aromatic ring.

[0028] Commercially available examples of the second alicyclic epoxy compound include EHPE3150 (1,2-epoxy-4-(2-oxiranyl)cyclohexane adduct of 2,2-bis(hydroxymethyl)-1-butanol, manufactured by Daicel Corporation) and Epolite 4000 (hydrogenated bisphenol A diglycidyl ether, manufactured by Kyoeisha Chemical Co., Ltd.). The second alicyclic epoxy compound may be an epoxy compound having no aromatic ring.

[0029] The content of the component (B1) may be 5 to 100 mass %, 10 to 100 mass %, or 12 to 100 mass %, based on the total amount of the component (B).

[0030] The component (B2) is a compound having an aliphatic group (linking group) and an epoxy group. The inclusion of the component (B2) in the component (B) tends to improve the compatibility and crosslinkability of the adhesive composition. The component (B2) 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. The component (B2) may also be an epoxy compound having no aromatic ring.

[0031] 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; and diglycidyl ethers having an oxyalkylene group, such as diethylene glycol diglycidyl ether, tripropylene glycol diglycidyl ether, and polyethylene glycol diglycidyl ether.

[0032] The content of the component (B2) may be 0 to 95 mass %, 0 to 90 mass %, or 0 to 88 mass %, based on the total amount of the component (B).

[0033] In addition to the components (B1) and (B2), the component (B) may contain another epoxy compound (hereinafter, sometimes referred to as "component (B3)") 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.

[0034] Examples of the component (B3) 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.

[0035] The content of the component (B3) 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 (B).

[0036] The content of the (B) component (the total of the (B1) component, the (B2) component, and the (B3) component) may be 5% by mass or more, 10% by mass or more, or 15% 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.

[0037] Component (C): Oxetane Compound Component (C) is a compound having one or more oxetanyl groups. Component (C) may be a compound having no (meth)acryloyl group or epoxy group. Component (C) may be a compound having two or more oxetanyl groups. By including component (C) in the adhesive composition, it becomes possible to form a cured product having excellent surface hardness. Note that component (E), described below, is not included in component (C).

[0038] Examples of commercially available products of component (C) include ETERNACOLL OXBP and ETERNACOLL OXIPA (trade names, manufactured by Ube Industries, Ltd.), OXSQ, OXT-121, OXT-221, OXT-101, and OXT-212 (trade names, manufactured by Toagosei Co., Ltd.).

[0039] The content of component (C) may be 1 mass % or more, 3 mass % or more, or 5 mass % or more, and may be 50 mass % or less, 45 mass % or less, or 40 mass % or less, based on the total amount of the adhesive composition.

[0040] Component (D): Photoacid Generator Component (D) is a component that generates an acid that initiates polymerization upon irradiation with light. Component (D) may be a component that generates an acid that initiates cationic 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. Component (D) may also be a component that generates radicals that initiate radical polymerization upon irradiation with light. Component (D) may be a component that generates radicals and an acid upon irradiation with light, or may be a component that generates radicals and an acid upon irradiation with ultraviolet light.

[0041] Examples of the component (D) 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.

[0042] Examples of commercially available products of component (D) 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).

[0043] The content of the component (D) may be, for example, 0.1 to 10 mass %, 0.3 to 7 mass %, or 0.5 to 5 mass % based on the total amount of the components (B) and (C).

[0044] Component (E): (meth)acrylic resin having a cationically polymerizable group Component (E) can be, for example, a (meth)acrylic resin having a structural unit derived from a (meth)acrylate having a cationically polymerizable group. Component (E) is a component that can act as a crosslinker with components (B) and (C) when the adhesive composition is cured. When the adhesive composition further contains component (E), the surface hardness of the cured product of the adhesive composition tends to be further improved. Note that component (E) is not included in components (B) and (C).

[0045] The cationically polymerizable group may be, for example, a cyclic ether group. The (meth)acrylate having a cyclic ether group 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.

[0046] From the viewpoint of crosslinkability with the (B) component and the (C) component, the content of the structural units derived from the (meth)acrylate having a cationically polymerizable group may be 1 mol % or more, 2 mol % or more, or 3 mol % or more, and may be 30 mol % or less, 20 mol % or less, or 10 mol % or less, based on all structural units of the (meth)acrylic resin.

[0047] The component (E) may further contain structural units derived from other (meth)acrylates. Examples of other (meth)acrylates include the (meth)acrylates exemplified for the components (A1) and (A2).

[0048] The content of structural units derived from other (meth)acrylates may be 70 mol% or more, 80 mol% or more, or 90 mol% or more, and may be 99 mol% or less, 98 mol% or less, or 97 mol% or less, based on all structural units of the (meth)acrylic resin.

[0049] The component (E) may have structural units other than the structural units derived from the (meth)acrylate having a cationically polymerizable group and the structural units derived from other (meth)acrylates, to the extent that the effects of the present disclosure are not impaired. Examples of compounds that provide such structural units include compounds having a radically polymerizable group other than a (meth)acryloyl group, such as styrene, 4-methylstyrene, vinylpyridine, vinylpyrrolidone, vinyl acetate, cyclohexylmaleimide, and phenylmaleimide.

[0050] The content of the other structural units may be 0 to 30 mol %, 0 to 20 mol %, or 0 to 10 mol % based on all structural units of the (meth)acrylic resin.

[0051] The weight average molecular weight (Mw) of component (E) may be, for example, 1,000 to 200,000, or may be 3,000 or more, 5,000 or more, or 10,000 or more, or 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.

[0052] Component (E) can be obtained, for example, by radical polymerization using a solution polymerization method. More specifically, it can be obtained by polymerizing a monomer containing a (meth)acrylate having a cationically polymerizable group in a solvent.

[0053] The solvent can be appropriately selected from organic solvents commonly used in the field of radical polymerization. Since the solvent can be used directly in the preparation of the adhesive composition without isolating component (E), it may be a solvent having a cyclic ether group (epoxy group or oxetanyl group) but not having a radically polymerizable group. 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. In terms of being usable as component (B2), the solvent may be, for example, an aliphatic diglycidyl ether. Examples of the aliphatic diglycidyl ether include those exemplified for component (B2).

[0054] 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.

[0055] When polymerizing the monomers, a thermal radical generator, an additive, etc. may be added as needed.

[0056] 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).

[0057] The amount of the thermal radical generator to be 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, 1,000 to 100,000 ppm by mass, or 10,000 to 80,000 ppm by mass based on the total amount of the monomers.

[0058] 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.

[0059] 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.

[0060] The content of component (E) may be 5% by mass or more, 10% by mass or more, or 15% by mass or more, and may be 40% by mass or less, 35% by mass or less, or 30% by mass or less, based on the total amount of the adhesive composition.

[0061] The adhesive composition may contain other components, such as a coupling agent (hereinafter sometimes referred to as "component (F)"), a photoradical generator (hereinafter sometimes referred to as "component (G)"), an antioxidant, a photosensitizer, etc.

[0062] 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 fully achieve the effects of the present disclosure. In this specification, compounds having a hydrolyzable silyl group and a (meth)acryloyl group, and compounds having a hydrolyzable silyl group and an epoxy group are classified as silane coupling agents.

[0063] 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.).

[0064] The content of component (F) may be 0.1 mass % or more, 0.3 mass % or more, or 0.5 mass % or more, and may be 10 mass % or less, 5 mass % or less, or 3 mass % or less, based on the total amount of the adhesive composition.

[0065] 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).

[0066] The component (G) generates free radicals when exposed to light. In other words, the component (G) is a compound that generates radicals when exposed to external light energy. 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.

[0067] 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.

[0068] 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-(4-morpholinophenyl)-butanone-1, and the like.

[0069] 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.

[0070] The amount of the component (G) relative to 100 parts by mass of the total amount of the component (A) 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.

[0071] The content of the antioxidant may be 0.1 to 10 mass % based on the total amount of the adhesive composition.

[0072] Examples of photosensitizers include benzoflavin, anthracene, pyrene, thioxanthone, benzophenone, anthraquinone, camphorquinone, coumarin dyes, and oxazole compounds.

[0073] 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.

[0074] The adhesive composition can be prepared by mixing (or kneading) the components. Mixing can be carried out using an appropriate combination of a conventional mixer, a planetary mixer, or other dispersing machine. During mixing, degassing treatment may be carried out, as appropriate, by vacuum degassing or the like.

[0075] The refractive index of the adhesive composition at room temperature (25°C) may be 1.550 or less, 1.540 or less, 1.530 or less, 1.520 or less, 1.510 or less, 1.505 or less, 1.500 or less, or 1.495 or less. The refractive index can be determined by setting a sample to be 0.1 to 0.2 mL and measuring the refractive index at a wavelength of 589 nm using a refractometer.

[0076] The adhesive composition can form an adhesive part (adhesive layer) that has excellent adhesion to various adherends. The adhesive part can be obtained by placing the adhesive composition at a predetermined position on the adherend to form an adhesive part precursor, and irradiating the formed adhesive part precursor with light. The light irradiation may be performed while heating. The adhesive part contains a cured product of the adhesive composition. The light irradiation may be performed directly on the adhesive part precursor, or may be performed via a transparent resin, glass, etc.

[0077] 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.

[0078] 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.

[0079] 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.

[0080] When light irradiation is performed while heating, the heating conditions may be, for example, 60 to 150°C.

[0081] After the adhesive precursor is irradiated with light, it may be further subjected to a heat treatment, for example, at a heating temperature of 60 to 180° C. for a holding time of 5 to 60 minutes.

[0082] The surface hardness (Shore D hardness) of the cured product of the adhesive composition may be 50 or more, and may be 55 or more, 60 or more, 65 or more, 70 or more, 75 or more, or 80 or more. The surface hardness (Shore D hardness) can be measured using a Shore D hardness tester. A measurement sample can be prepared by the following procedure. First, a 1 mm thick silicone rubber having a 5 mm diameter hole is placed on a glass plate. Next, the adhesive composition is introduced into the silicone rubber hole, and the adhesive composition is irradiated with an illuminance of 100 mW / cm using a 365 nm LED light source (manufactured by Asahi Spectroscopy Co., Ltd.). ２ and irradiation time of 30 seconds, and then cured at room temperature (25°C) for 30 minutes to prepare a cured product sample for measurement having a diameter of 5 mm and a thickness of 1 mm. The surface hardness (Shore D hardness) of the cured adhesive composition of the cured product sample for measurement is measured using a Shore D hardness tester.

[0083] The infrared transmittance of the cured product of the adhesive composition may be 70% or more, or may be 75% or more, 80% or more, 85% or more, 90% or more, 92% or more, or 95% 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 measure the infrared transmittance at an illuminance of 30 mW / cm. ２ The adhesive composition is irradiated with light under the conditions of 100°C, 100°F, and 30 seconds of irradiation time, 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.

[0084] The glass transition temperature (Tg) of the cured product of the adhesive composition may be 70°C or higher, 75°C or higher, 80°C or higher, or 85°C or higher. The glass transition temperature (Tg) is the midpoint glass transition temperature calculated by a method in accordance with JIS K7121:1987, where the change in heat quantity is measured under conditions of a temperature rise rate of 10°C / min and a measurement temperature of 25 to 300°C. The glass transition temperature (Tg) can be measured using a differential scanning calorimeter. A measurement sample is prepared by introducing the adhesive composition into an aluminum pan for measurement, and subjecting the adhesive composition to an illuminance of 100 mW / cm using a 365 nm LED light source (manufactured by Asahi Spectroscopy Co., Ltd.). ２ The film is irradiated under the conditions of 1000 W and 30 seconds of irradiation time, and then cured at room temperature (25° C.) for 30 minutes to prepare the film.

[0085] [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.

[0086] 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 include composite materials of the above-mentioned plastics and inorganic materials. From the standpoint of light irradiation, either the first or second adherend may be a transparent resin or glass.

[0087] 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.

[0088] 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 precursor containing the adhesive composition, placing a second adherend on the adhesive precursor to produce a laminate, and irradiating the adhesive precursor of the laminate with light to form an adhesive containing a cured product of the adhesive composition.

[0089] 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.

[0090] The light irradiation conditions (light wavelength, light source, integrated light amount, etc.) for the adhesive portion precursor of the laminate may be the same as the light irradiation conditions (light wavelength, light source, integrated light amount, etc.) described above.

[0091] The adhesive portion precursor of the laminate may be irradiated with light while being heated. The heating conditions (heating temperature, etc.) may be the same as those described above.

[0092] After the adhesive precursor of the laminate is irradiated with light, the adhesive precursor may be further subjected to a heat treatment. The heat treatment conditions (heating temperature, holding time, etc.) may be the same as those described above.

[0093] 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.

[0094] The present disclosure will be specifically described below using examples, but the present disclosure is not limited to these examples.

[0095] [Synthesis and Evaluation of (Meth)acrylic Resin Having Cationically Polymerizable Group] The following raw materials were prepared. (Meth)acrylate Compounds BA: Butyl acrylate (manufactured by Toagosei Co., Ltd.) MMA: Methyl methacrylate (Acryester M, manufactured by Mitsubishi Chemical Corporation) GMA: Glycidyl methacrylate (manufactured by Mitsubishi Gas Chemical Company, Inc.) Thermal Radical Generator V-601: Dimethyl-2,2'-azobis(2-methylpropionate) (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) Solvent NPG(D): Neopentyl glycol diglycidyl ether (Epogose NPG(D)) (manufactured by Yokkaichi Synthetic Co., Ltd.)

[0096] Synthesis Example 1: 95.41 g of BA, 82.81 g of MMA, and 11.76 g of GMA (molar ratio of BA / MMA / GMA = 45% / 50% / 5%), 2.28 g of V-601, and 24.42 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).

[0097] A flask equipped with a stirrer, dropping funnel, condenser, thermometer, and gas inlet tube was charged with 162.44 g of NPG (D), which was stirred under a nitrogen atmosphere while replacing the gas, and heated 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, after which 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 a (meth)acrylic resin having a cationically polymerizable group of Synthesis Example 1. The solids concentration was 50% by mass. Note that the solids content of the solution containing a (meth)acrylic resin having a cationically polymerizable group refers to the components other than the solvent of the solution containing a (meth)acrylic resin having a cationically polymerizable group.

[0098] (Measurement of Weight Average Molecular Weight (Mw)) A solution containing the (meth)acrylic resin having cationically polymerizable groups of Synthesis Example 1 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 using a calibration curve of standard polystyrene. The GPC conditions are shown below. The Mw of the (meth)acrylic resin having cationically polymerizable groups of Synthesis Example 1 was 48,000. 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] [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 the respective components were prepared by mixing the respective components in the amounts (unit: parts by mass) shown in Tables 1, 2, and 3 using a planetary mixer (5 minutes / 1500 rpm). The amounts of the (meth)acrylic resin having a cationically polymerizable group of Synthesis Example 1, which is component (E), and NPG (D), which is component (B2) of component (B), added were adjusted to the parts by mass of each component shown in the tables using the solution containing the (meth)acrylic resin having a cationically polymerizable group of Synthesis Example 1 obtained above (the solids content corresponds to component (E) and the solvent corresponds to component (B2) of component (B)).

[0100] Details of each raw material are as follows:Component (A): (meth)acrylate compound Component (A1): monofunctional (meth)acrylate compound 4-HBA: 4-hydroxybutyl acrylate (manufactured by Osaka Organic Chemical Industry Ltd.) 2-MTA: 2-methoxyethyl acrylate (manufactured by Osaka Organic Chemical Industry Ltd.) IBXA: isobornyl acrylate (manufactured by Osaka Organic Chemical Industry Ltd.) NOAA: n-octyl acrylate (manufactured by Osaka Organic Chemical Industry Ltd.) Component (A2): bifunctional (meth)acrylate compound HDDA: 1,6-hexanediol diacrylate (manufactured by Osaka Organic Chemical Industry Ltd.) A-NPG: neopentyl glycol diacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd.) Component (A3): trifunctional or higher functional (meth)acrylate compound A-9300S: tris(2-acryloxyethyl)isocyanurate (trifunctional, isocyanuric acid EO-modified triacrylate, manufactured by Shin-Nakamura Chemical Co., Ltd.) EBECRYL160S: trimethylolpropane ethoxy triacrylate (trifunctional, trimethylolpropane EO-modified triacrylate, manufactured by Daicel-Allnex Co., Ltd.) (B) component: epoxy compound (B1) component: alicyclic epoxy compound 2021P: 3',4'-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate (Celloxide 2021P, manufactured by Daicel Corporation) EHPE3150: (2,2-bis(hydroxymethyl)-1-butanol to 1,2-epoxy-4-(2-oxiranyl)cyclohexane adduct (EHPE3150, manufactured by Daicel Corporation) (B2) component: aliphatic epoxy compound NPG (D): neopentyl glycol diglycidyl ether (Epogose NPG (D), manufactured by Yokkaichi Synthetic Co., Ltd.) (C) component: oxetane compound OXT-221: 3-ethyl-3{[(3-ethyloxetan-3-yl)methoxy]methyl}oxetane (manufactured by Toagosei Co., Ltd.) Component (D): photoacid generator CPI-110P: sulfonium salt (manufactured by San-Apro Ltd.) Component (E): (meth)acrylic resin having a cationically polymerizable group Synthesis Example 1: (meth)acrylic resin having a cationically polymerizable group of Synthesis Example 1 Component (F): coupling agent KBE-9007N: 3-isocyanatepropyltriethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd.).

[0101] [Evaluation of Adhesive Composition] (Measurement of Refractive Index) The refractive index of the adhesive composition at room temperature (25°C) was measured using an Abbemat 300 (manufactured by Anton Paar, wavelength: 589 nm) so that the sample volume was 0.1 to 0.2 mL. The results are shown in Tables 1, 2, and 3.

[0102] (Measurement of Surface Hardness (Shore D Hardness)) First, a 1 mm thick silicone rubber sheet having a 5 mm diameter hole was placed on a glass plate. Next, the adhesive composition was introduced into the silicone rubber hole, and the adhesive composition was irradiated with a 365 nm LED light source (manufactured by Asahi Spectroscopy Co., Ltd.) at an illuminance of 100 mW / cm. ２ and irradiation time of 30 seconds, and then cured at room temperature (25°C) for 30 minutes to prepare cured samples for measurement, each 5 mm in diameter and 1 mm thick. The surface hardness (Shore D hardness) of the cured adhesive composition was measured for each of the cured samples for measurement using a Shore D hardness tester (manufactured by Ueshima Seisakusho Co., Ltd., product name: HD-1100 Type D). The results are shown in Tables 1, 2, and 3.

[0103] (Measurement of infrared transmittance) The infrared transmittance of the cured adhesive composition was measured at a wavelength of 1,310 nm using a spectrophotometer (manufactured by Agilent Technologies, product name: Cary 7000). Measurement samples were prepared by the following procedure. First, a 500 μm thick spacer film was placed on a release film so that the dimensions were 50 mm wide x 50 mm long and 500 μm thick, and the adhesive composition was applied onto the release film. Next, an LED lamp (manufactured by Ushio Inc., wavelength: 365 nm) was used to measure the infrared transmittance at an illuminance of 30 mW / cm. ２ The adhesive composition was irradiated with light under conditions of 1000 nm and 30 seconds of irradiation time, and 600 seconds after the end of the light irradiation, the adhesive composition was peeled off from the release film to prepare a measurement sample. The glass substrate was used as a baseline. The results are shown in Tables 1, 2, and 3.

[0104] (Measurement of Glass Transition Temperature (Tg)) A measurement sample was prepared by placing the adhesive composition in an aluminum pan for measurement, and applying the adhesive composition to a 365 nm LED light source (manufactured by Asahi Spectroscopy Co., Ltd.) at an illuminance of 100 mW / cm. ２The samples were prepared by irradiating the sample with 1000 kJ / min of 1000 kJ / s for 30 seconds, followed by aging at room temperature (25°C) for 30 minutes. The glass transition temperature (Tg) was measured using a differential scanning calorimeter (manufactured by Netzsch). Specifically, the change in calorific value was measured at a temperature rise rate of 10°C / min and a measurement temperature range of 25 to 300°C. The glass transition temperature (Tg) was determined in accordance with JIS K7121:1987 by determining the point at which a straight line equidistant from the baselines on the low-temperature and high-temperature sides of the stepwise change in the measurement results intersected with the curve of the stepwise change, and this point was designated the midpoint glass transition temperature. The results are shown in Tables 1, 2, and 3.

[0105] (Measurement of Shear Strength) A 50 μm thick spacer film was placed on a glass slide to have 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 measure the shear strength at an illuminance of 30 mW / cm. ２ The adhesive composition was irradiated with light for 30 seconds. Shear strength was measured using a bond tester (Nordson, product name: DAGE 4000) by peeling off the glass chip at a shear rate of 180 mm / min, using a sample taken 270 seconds after the end of light irradiation. The results are shown in Tables 1, 2, and 3.

[0106]

[0107]

[0108]

[0109] As shown in Tables 1, 2, and 3, the adhesive compositions of Examples 1 to 13 were superior in terms of surface hardness to the adhesive composition of Comparative Example 1. These results confirmed that the adhesive composition of the present disclosure is capable of forming a cured product with excellent surface hardness.

Claims

1. An adhesive composition comprising a (meth)acrylate compound, an epoxy compound, an oxetane compound, and a photoacid generator.

2. The adhesive composition according to claim 1, wherein the epoxy compound comprises an alicyclic epoxy compound.

3. The adhesive composition according to claim 1, further comprising a (meth)acrylic resin having a cationically polymerizable group.

4. The adhesive composition according to claim 1, wherein the (meth)acrylate compound comprises at least one compound selected from the group consisting of monofunctional (meth)acrylate compounds and difunctional (meth)acrylate compounds.

5. The adhesive composition according to claim 4, wherein the (meth)acrylate compound further comprises a tri- or higher functional (meth)acrylate compound.

6. An adhesive 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 claims 1 to 5.

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