Active energy radiation-cured adhesive compositions, cured products and laminates

Abstract

This invention provides an active energy radiation-curable adhesive composition, a cured product, and a laminate. The active energy radiation-curable adhesive composition provides a cured layer with excellent heat resistance, exhibiting strong adhesion and a high storage modulus even at high temperatures. The active energy radiation-curable adhesive composition comprises: a polyurethane (meth)acrylate (A), which is a reaction product of a polyol (a1), a polyisocyanate (a2), and a hydroxyl-containing mono(meth)acrylate (a3-1), or a reaction product of a polyol (a1), a polyisocyanate (a2), and an isocyanate-containing mono(meth)acrylate (a3-2), wherein the polyurethane (meth)acrylate (A) has an average of 1 to 4 (meth)acryloyl groups and a weight-average molecular weight of 10,000 to 90,000; an alkyl mono(meth)acrylate (B); a mono(meth)acrylate (C) having at least two aromatic rings; and a compound (D) having a secondary thiol group.

Description

Technical Field

[0001] This invention relates to active energy ray-cured adhesive compositions, cured products, and laminates. Background Technology

[0002] Adhesives are used in the manufacturing processes of mobile devices such as smartphones and tablets, digital cameras, audio equipment, and communication devices such as wireless devices and modems for bonding optical components together. Examples include bonding touch sensors to the front panel or to an image display device during touch panel manufacturing. Such adhesives, in addition to high adhesion, also possess high storage modulus at high temperatures (meaning that the elastic modulus changes little with temperature), requiring excellent heat resistance.

[0003] In response to such requirements, the applicant disclosed a UV-curable adhesive comprising specific amounts of polyurethane (meth)acrylate, two non-hydroxyl-containing polymerizable monomers with specific glass transition temperatures, a monomer containing primary hydroxyl groups, and a photopolymerization initiator (Patent Document 1). However, the aforementioned adhesive has a low storage modulus at high temperatures, leaving room for further improvement in heat resistance (heat retention).

[0004] To improve heat resistance, the use of aromatic ring monomers can be cited as a means, and as a technique, thermosetting adhesive compositions comprising an acrylic copolymer, a polyisocyanate crosslinking agent, and an organic solvent are known, wherein the acrylic copolymer contains a specific amount of aromatic ring monomers as monomer units (Patent Document 2). However, while the heat resistance is generally improved when aromatic ring monomers are used, there is a tendency for the adhesive strength to decrease.

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: Japanese Patent Application Publication No. 2018-039999

[0008] Patent Document 2: International Publication No. 2018 / 062288 Summary of the Invention

[0009] The problem that the invention aims to solve

[0010] The objective of this invention is to provide an active energy ray-curable adhesive composition that provides a cured layer with excellent heat resistance, exhibiting high adhesion and high storage modulus even at high temperatures.

[0011] Methods for solving problems

[0012] The inventors conducted in-depth research and discovered that the aforementioned problems were solved by combining various mono(meth)acrylates into polyurethane (meth)acrylates. Specifically, this invention relates to the following active energy ray-curable adhesive compositions, cured products, and laminates.

[0013] 1. An active energy radiation-curable adhesive composition, comprising:

[0014] Polyurethane (meth)acrylate (A) is a reaction product of polyol (a1), polyisocyanate (a2) and hydroxyl-containing mono(meth)acrylate (a3-1), or a reaction product of polyol (a1), polyisocyanate (a2) and isocyanate-containing mono(meth)acrylate (a3-2), wherein the polyurethane (meth)acrylate (A) has an average number of (meth)acryloyl groups of 1 to 4 and a weight-average molecular weight of 10,000 to 90,000;

[0015] Mono(meth)acrylate alkyl ester (B);

[0016] Mono(meth)acrylates (C) having at least two aromatic rings; and

[0017] Compounds containing a secondary thiol group (D).

[0018] 2. The active energy ray-curable adhesive composition according to item 1 above, wherein component (a1) comprises a polyether polyol.

[0019] 3. The active energy ray curable adhesive composition according to paragraph 1 or 2 above, wherein component (B) comprises alkyl mono(meth)acrylate (B1) and / or hydroxyalkyl mono(meth)acrylate (B2) without hydroxyl groups.

[0020] 4. The active energy ray-curable adhesive composition according to any one of paragraphs 1 to 3, wherein the content of component (C) is 30% to 75% by mass relative to 100% by mass of the total of components (A), (B) and (C).

[0021] 5. The active energy ray-curable adhesive composition according to any one of paragraphs 1 to 4, wherein component (D) is a compound having two or more secondary thiol groups.

[0022] 6. In the active energy ray curable adhesive composition according to any one of the preceding items 1 to 5, the content of component (D) is 0.1 to 5 parts by weight relative to the total 100 parts by weight of components (A), (B) and (C) based on the mass of solid components.

[0023] 7. A cured product of any one of the active energy ray-curable adhesive compositions described in items 1 to 6 above.

[0024] 8. The cured material according to paragraph 7 above has a storage modulus G' of 0.3 MPa or more at a temperature of 25°C and a frequency of 1 Hz, and has a storage modulus G' of 0.1 MPa or more at a temperature of 100°C and a frequency of 1 Hz.

[0025] 9. A laminate having at least one side of a substrate the cured material described in paragraph 7 or 8 above.

[0026] The effects of the invention

[0027] The active energy ray-curable adhesive composition of the present invention (hereinafter referred to as the "adhesive composition") provides a cured layer with high adhesive strength and exhibiting excellent heat resistance and high storage modulus. Furthermore, the cured layer also possesses excellent resistance to humid heat. Detailed Implementation

[0028] The adhesive composition of the present invention comprises a specific polyurethane (meth)acrylate (A) (hereinafter referred to as component (A), a mono(meth)acrylate alkyl ester (B) (hereinafter referred to as component (B)), a mono(meth)acrylate (C) having at least two aromatic rings (hereinafter referred to as component (C)), and a compound (D) having a secondary thiol group (hereinafter referred to as component (D)).

[0029] The (A) component of the present invention is a reaction product of a polyol (a1) (hereinafter referred to as (a1) component), a polyisocyanate (a2) (hereinafter referred to as (a2) component) and a hydroxyl-containing mono(meth)acrylate (a3-1) (hereinafter referred to as (a3-1) component) or an isocyanate-containing mono(meth)acrylate (a3-2) (hereinafter referred to as (a3-2) component).

[0030] (a1) refers to an alcohol having two or more hydroxyl groups, used to enable the cured product to exhibit excellent adhesion. As (a1), a single-compound polyol, a polymeric polyol, or a crystalline or amorphous polyol can be used. Here, a crystalline polyol refers to a polyol that preferably has a crystalline structure at 20–60°C, more preferably at 20–40°C.

[0031] Polyols as single compounds are not particularly limited, and examples include ethylene glycol, diethylene glycol, propylene glycol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2-methyl-1,3-propanediol, 1,5-pentanediol, neopentanediol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, 2-methyl-1,5-pentanediol, and 2,2-diethyl-1,3-propanediol. Aliphatic diols such as diols, 1,9-nonanediol, 1,10-decanediol, butylethylpropylene glycol, and butylethylpentanediol; alicyclic diols such as 1,4-cyclohexanediethanol; trimethylolpropane, pentaerythritol, bis(trimethylolpropane), dipentaerythritol, dimerized glycol, hydrogenated dimerized glycol, trimerized glycol, hydrogenated trimerized glycol, castor oil, castor oil-modified polyols, and epoxide adducts of bisphenol compounds or their derivatives. These can be used alone or in combination of two or more.

[0032] As a polymeric polyol, there are no particular limitations; examples include polyether polyols, polyester polyols, poly(meth)acrylic acid polyols, polyolefin polyols, polycaprolactone polyols, and polycarbonate polyols. They can be used alone or in combination of two or more. It should be noted that (meth)acrylic acid refers to acrylic acid or methacrylic acid.

[0033] Among these, polymeric polyols are preferred from the perspective of the high adhesion exhibited by the cured product. Specific polymeric polyols will be given below.

[0034] As polyether polyols, there are no particular limitations; examples include polyethylene glycol, polypropylene glycol, polytetramethylene glycol, and other polyalkylene glycols, as well as copolymers containing multiple epoxides as monomer components, such as ethylene oxide-propylene oxide copolymers (epoxide-other epoxides). They can be used alone or in combination of two or more.

[0035] Commercially available polyether polyols include "Adeka Polyester P-400", "Adeka Polyester G-400", "Adeka Polyester T-400", "Adeka Polyester AM-302", "Adeka Polyester P1000", and "Adeka Polyester P2000" (all manufactured by ADEKA Corporation); "Polyethylene Glycol #1540" (manufactured by NACALAITESQUE Corporation); "Dipropylene Glycol" and "Polypropylene Glycol 400" (manufactured by Junsei Chemical Co., Ltd.); and "PTMG650", "PTMG1000", "PTMG2000", and "PTMG3000" (manufactured by Mitsubishi Chemical Co., Ltd.).

[0036] There are no particular limitations on what constitutes a polyester polyol; examples include condensation polymers of polyols and polycarboxylic acids; ring-opening polymers of cyclic esters (lactones); and ternary reaction products of polyols, polycarboxylic acids, and cyclic esters.

[0037] As a polyol, there is no particular limitation. For example, polyols listed above that are single compounds can be used as examples; triols such as glycerol, trimethylolpropane, and trimethylolethane; cyclohexanediols such as 1,2-cyclohexanediol, 1,3-cyclohexanediol, and 1,4-cyclohexanediol; cyclohexanediethanols such as 1,2-cyclohexanediethanol, 1,3-cyclohexanediethanol, and 1,4-cyclohexanediethanol; bisphenols such as bisphenol A and bisphenol F; and sugar alcohols such as xylitol and sorbitol. They can be used alone or in combination of two or more.

[0038] As a polycarboxylic acid, there are no particular limitations. Examples include aliphatic dicarboxylic acids such as malonic acid, maleic acid, succinic acid, adipic acid, octanoic acid, azelaic acid, sebacic acid, and dodecanoic acid; alicyclic dicarboxylic acids such as 1,4-cyclohexanedicarboxylic acid; and aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, phthalic acid, 2,6-naphthalenedicarboxylic acid, and trimellitic acid. They can be used alone or in combination of two or more.

[0039] As cyclic esters, there are no particular limitations. Examples include proprolactone, β-methyl-δ-valerolactone, and ε-caprolactone. They can be used alone or in combination of two or more.

[0040] Commercially available polyester polyols include “POLYLITE RX-4800”, “POLYLITE OD-X-2523”, “POLYLITE OD-X-2547”, “POLYLITE OD-X-2420”, “POLYLITE OD-X-2692”, and “POLYLITE OD-X-2108” (all manufactured by DIC Corporation); and “Kuraray Polyol P-510”, “Kuraray Polyol P-1010”, “Kuraray Polyol P-2010”, and “Kuraray Polyol F-510” (all manufactured by Kuraray Corporation).

[0041] Examples of polycarbonate polyols include, for example, reaction products of polyols and carbonyl chlorides; ring-opening polymers of cyclic carbonates (alkylene carbonates, etc.). Examples of polyols include the aforementioned polyols. Examples of alkylene carbonates are not particularly limited; for example, ethylene carbonate, trimethylol carbonate, tetramethylol carbonate, and hexamethylene carbonate are examples. Commercially available polycarbonate polyols include "Kuraray Polyol C-590" (manufactured by Kuraray Co., Ltd.); "NIPPOLAN 4002", "NIPPOLAN 4009", and "NIPPOLAN 981" (manufactured by Tosoh Co., Ltd.); and "DURANOLT6002" and "DURANOL T5652" (manufactured by Asahi Kasei Corporation).

[0042] Poly(meth)acrylic acid polyols, for example, include homopolymers or copolymers of acrylic monomers having one or more hydroxyl groups, or poly(meth)acrylic acid polyols obtained by copolymerizing these copolymers with other monomers, which can be used alone or in combination of two or more.

[0043] Commercially available poly(meth)acrylic acid polyols include "ARUFON UH-2041" (manufactured by Toa Synthetic Co., Ltd.); "Acrylic Polyol #6000" (manufactured by TAISEI FINE CHEMICAL Co., Ltd.); and "Acrylic Polyol PC #5984" (manufactured by Toei Kasei Co., Ltd.).

[0044] As a polyolefin polyol, there are no particular limitations; examples include polybutadiene, hydrogenated polybutadiene, polyisoprene, hydrogenated polyisoprene, and their chlorides, which have two or more hydroxyl groups. They can be used alone or in combination of two or more. Commercially available products include "NISSO-PB GI-1000," "NISSO-PB GI-2000," and "NISSO-PB GI-3000" (all manufactured by Nippon Soda Co., Ltd.).

[0045] There are no particular limitations on the polycaprolactone polyols used; examples include polycaprolactone diol, polycaprolactone triol, and polycaprolactone tetraol. These can be used alone or in combination of two or more. Commercially available products include "POLYLITE OD-X-2155" (manufactured by DIC Corporation); "Praxel 200," "Praxel 205," "Praxel 300," and "Praxel 400" (all manufactured by DAICEL Corporation).

[0046] Among these polymeric polyols, polyether polyols, polyester polyols, and polycaprolactone polyols are preferred, with polyether polyols being more preferred, based on the high adhesion of the cured product and its excellent heat and moisture resistance.

[0047] (a1) The physical properties of the components are not particularly limited. For example, considering that the cured product exhibits high adhesion and excellent resistance to damp heat, the number average molecular weight (the polystyrene equivalent based on gel permeation chromatography (GPC)) is usually around 700 to 10,000, preferably around 1,000 to 4,000.

[0048] In addition, from the perspective of the cured product exhibiting high adhesion, the average number of hydroxyl groups per molecule of component (a1) (hereinafter also referred to as "average number of hydroxyl groups") is usually about 1.5 to 3, preferably about 2 to 3.

[0049] The average number of hydroxyl groups per molecule of component (a1) refers to the average number of hydroxyl groups present in one molecule of component (a1). For example, ethylene glycol has 2 hydroxyl groups per molecule, so the average number of hydroxyl groups is "2". Furthermore, when using multiple components (a1) with different numbers of hydroxyl groups, such as 0.4 mol of ethylene glycol (hydroxyl group: 2) and 0.6 mol of trimethylolpropane (hydroxyl group: 3), the average number of hydroxyl groups can be determined by a weighted average.

[0050] (Equation 1) [(a1) Average number of hydroxyl groups per molecule of component]

[0051] = (2 × 0.4 + 3 × 0.6) / (0.4 + 0.6) = 2.6

[0052] As component (a2), there are no particular limitations, and examples include aromatic diisocyanates such as toluene diisocyanate, diphenylmethane diisocyanate, and phenylenediamine diisocyanate; and aliphatic diisocyanates such as hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, lysine diisocyanate, dicyclohexylmethane diisocyanate, isophorone diisocyanate, 1,4-cyclohexane diisocyanate, hydrogenated phenylenediamine diisocyanate, and hydrogenated toluene diisocyanate. These can be used alone or in combination of two or more. Furthermore, as component (a2), their ureate esters, adducts, or biuret forms can be used. Among these, aliphatic diisocyanates are preferred from the perspective of exhibiting high adhesion in the cured product.

[0053] The ratio of component (a1) to component (a2) is not particularly limited, and is usually determined by the number of moles of isocyanate groups (NCO) in component (a2). (a2) The number of moles of hydroxyl groups (OH) in components (a1) and (a2) (a1) The ratio of NCO (a2) / OH(a1) The optimal value is set to approximately 1.01 to 2.

[0054] As for component (a3-1), there are no particular limitations. Examples include 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, 3-hydroxypropyl methacrylate, 3-hydroxybutyl methacrylate, 4-hydroxybutyl methacrylate, 6-hydroxyhexyl methacrylate, and 8-hydroxyoctyl methacrylate. These can be used alone or in combination of two or more. Among them, 2-hydroxyethyl methacrylate and 4-hydroxybutyl methacrylate are preferred from the perspective of high adhesion of the cured product. It should be noted that (meth)acrylate refers to acrylate or methacrylate.

[0055] As a component (a3-2), there are no particular limitations, and various known mono(meth)acrylates can be used. Examples include ethyl 2-isocyanate (meth)acrylate, 1,1-bis(acryloyloxymethyl)ethyl isocyanate, and ethyl 2-(o-[1'-methylpropyleneamino]carboxyamino)methacrylate, which can be used alone or in combination with two or more.

[0056] (A) There are no particular limitations on the ingredients, and they can be manufactured by various known methods. Hereinafter, we will explain the ingredients as follows: (A1) obtained by using ingredient (a3-1) as ingredient (a3) ​​(hereinafter referred to as ingredient (A1)) and (A2) obtained by using ingredient (a3-2) as ingredient (a3) ​​(hereinafter referred to as ingredient (A2)).

[0057] Component (A1) is not particularly limited. For example, it can be obtained by reacting component (a1) with component (a2) to produce an isocyanate-terminated urethane prepolymer (hereinafter referred to as component (A1')), followed by reacting component (A1') with component (a3-1). The reaction conditions are not particularly limited, but typically the temperature is around 70–85°C and the time is around 1–5 hours. Furthermore, the ratio of component (a1) to component (a2) is not particularly limited, but the molar number of isocyanate groups in component (a2) (NCO) is not particularly limited. (a2) The number of moles of hydroxyl groups (OH) in components (a1) and (a2) (a1) The ratio of NCO (a2) / OH (a1) The concentration is typically in the range of 1.01 to 2. Furthermore, there is no particular limitation on the ratio of (A1') to (a3-1) components, but the molar number of isocyanate groups in the former (NCO) is acceptable. (A1’) The number of moles of hydroxyl groups (OH) in the latter. (a3-1) The ratio of NCO (A1’) / OH (a3-1)The value is usually in the range of 0.25 to 1.

[0058] For component (A2), after reacting component (a1) with component (a2) to obtain the hydroxyl-terminated urethane prepolymer (hereinafter referred to as component (A2')), component (A2') is reacted with component (a3-2). The reaction temperature and reaction time are the same as for component (A1). Furthermore, there is no particular limitation on the ratio of component (a1) to component (a2), (NCO... (a2) / OH (a1) The concentration is typically in the range of 0.50 to 0.99. Furthermore, there is no particular limitation on the ratio of component (A2') to component (a3-2), but the molar number of isocyanate groups in the latter (NCO) is not critical. (a3-2) The number of moles of hydroxyl groups (OH) in the former. (A2’) The ratio of NCO (a3-2) / OH (A2’) The value is usually in the range of 0.5 to 1.

[0059] The manufacture of these components (A1) and (A2) can be carried out in the presence of the organic solvents described later, but to reduce environmental impact, it is preferable to carry them out in a solvent-free environment. Alternatively, their manufacture can also be carried out in the presence of component (B), described later.

[0060] The weight-average molecular weight of component (A) is 10,000 to 90,000. If the weight-average molecular weight is less than 10,000, it is considered low molecular weight, thus failing to fully utilize the adhesive strength of the cured product. If it exceeds 90,000, the storage modulus of the cured product at high temperatures decreases, and its heat resistance also decreases. Furthermore, following the same trend, the weight-average molecular weight of component (A) is preferably 20,000 to 80,000, and more preferably 20,000 to 60,000. It should be noted that the weight-average molecular weight is a value determined by gel permeation chromatography (GPC) using polystyrene as a standard.

[0061] Furthermore, the average number of (meth)acryloyl groups per molecule of component (A) (hereinafter also simply referred to as "average (meth)acryloyl group number") is 1 to 4. By keeping the average (meth)acryloyl group number within this range, the cured product exhibits high adhesive strength. Additionally, following the same trend, the average (meth)acryloyl group number is preferably 1 to 3, more preferably 1 to 2. It should be noted that (meth)acryloyl group refers to acryloyl group or methacryloyl group.

[0062] The average number of (meth)acryloyl groups per molecule of component (A) refers to the average number of (meth)acryloyl groups present in each molecule of component (A). For example, when 1 mole of ethylene glycol, 2 moles of diisocyanate as component (a2), and 2 moles of component (a3-1) are reacted, the average number of (meth)acryloyl groups is "2" when component (a3-1) is mono(meth)acrylate, and the average number of (meth)acryloyl groups is "6" when component (a3-1) is tri(meth)acrylate.

[0063] It should be noted that component (A) may contain two or more substances with the same or different average (meth)acryloyl groups, or they may be mixed. In this case, the average (meth)acryloyl group number can be determined by weighted average. For example, in the case of containing 0.2 moles of component (A) with an average (meth)acryloyl group number of 1 and 0.8 moles of component (A) with an average (meth)acryloyl group number of 2, the following is described.

[0064] (Equation 2) [Average number of (meth)acryloyl groups per molecule of component (A)] = (1 × 0.2 + 2 × 0.8) / (0.2 + 0.8) = 1.8

[0065] The content of component (A) is determined from the perspective of exhibiting high adhesion and excellent heat resistance. The total of components (A), (B) and (C) is set to 100% by mass, usually 10 to 49% by mass, preferably 15 to 49% by mass, and more preferably 25 to 49% by mass, based on the mass of solid components (the same below).

[0066] (B) Components are used to impart high adhesion to the cured product and can be various well-known components. Specifically, examples include hydroxyl-free mono(meth)acrylates (B1) (hereinafter referred to as component (B1)) and / or mono(meth)acrylates with hydroxyl groups (B2) (hereinafter referred to as component (B2)).

[0067] Examples of (B1) components include methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, n-butyl methacrylate, tert-butyl methacrylate, isobutyl methacrylate, n-pentyl methacrylate, n-hexyl methacrylate, n-heptyl methacrylate, n-octyl methacrylate, 2-ethylhexyl methacrylate, n-nonyl methacrylate, n-decyl methacrylate, isodecyl methacrylate, tri-n-decyl methacrylate, n-laurate methacrylate, n-myristyl methacrylate, n-palmitoyl methacrylate, n-stearyl methacrylate, and isostearyl methacrylate, among other aliphatic mono(meth)acrylate alkyl esters.

[0068] Cyclohexyl methacrylate, norbornyl methacrylate, isobornyl methacrylate, dicyclopentenyl methacrylate, dicyclopentenoxyethyl methacrylate, dicyclopentyl methacrylate, dicyclopentoxyethyl methacrylate, tricyclodecane dihydroxymethyl di(meth)acrylate and other alicyclic mono(meth)acrylates;

[0069] Aromatic mono(meth)acrylates such as phenyl methacrylate, benzyl methacrylate, 2-phenylethyl methacrylate, and nonylphenoxy polyethylene glycol (meth)acrylate can be used alone or in combination of two or more. Aliphatic mono(meth)acrylates are preferred from the perspective of exhibiting high adhesion to the adhesive layer, and 2-ethylhexyl methacrylate is more preferred.

[0070] Examples of (B2) components include 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, 3-hydroxypropyl methacrylate, 3-hydroxybutyl methacrylate, 4-hydroxybutyl methacrylate, 6-hydroxyhexyl methacrylate, and 8-hydroxyoctyl methacrylate. These can be used alone or in combination of two or more. Among these, 2-hydroxyethyl methacrylate and 4-hydroxybutyl methacrylate are preferred from the perspective of exhibiting excellent resistance to damp heat in the adhesive layer.

[0071] The content of component (B) is determined based on the aspect that the adhesive layer exhibits high adhesion and excellent resistance to damp heat. The total amount of components (A), (B) and (C) is set to 100% by mass, typically 10 to 35% by mass, preferably 10 to 30% by mass, and more preferably 10 to 20% by mass.

[0072] The content of components (B1) and (B2) is preferably (B1) / (B2) = 1 / 3 to 2 / 1, more preferably 1 / 3 to 1 / 1, and even more preferably 1 / 2 to 1 / 1, based on the mass ratio of solid components, so as to exhibit high adhesion and excellent resistance to damp heat in the adhesive layer.

[0073] Component (C) is a mono(meth)acrylate having at least two aromatic rings, which contributes to the excellent heat resistance of the adhesive layer by being incorporated into the adhesive composition. Examples of component (C) include o-phenylphenoxyethyl (meth)acrylate, m-phenylphenoxyethyl (meth)acrylate, p-phenylphenoxyethyl (meth)acrylate, o-phenoxybenzyl (meth)acrylate, m-phenoxybenzyl (meth)acrylate, p-phenoxybenzyl (meth)acrylate, ethoxylated o-phenylphenol (meth)acrylate, ethoxylated m-phenylphenol (meth)acrylate, ethoxylated p-phenylphenol (meth)acrylate, ethylene oxide modified o-cumylphenol (meth)acrylate, ethylene oxide modified m-cumylphenol (meth)acrylate, ethylene oxide modified p-cumylphenol (meth)acrylate, triphenyl methyl (meth)acrylate, etc. They can be used alone or in combination of two or more. Among these, o-phenylphenoxyethyl (meth)acrylate, m-phenylphenoxyethyl (meth)acrylate, and p-phenylphenoxyethyl (meth)acrylate are preferred, based on the aspect that the adhesive layer exhibits high adhesion and excellent heat resistance.

[0074] As for the content of component (C), from the perspective of the adhesive exhibiting excellent heat resistance, the total of components (A), (B) and (C) is set to 100% by mass, preferably 40 to 75% by mass, more preferably 45 to 75% by mass, and even more preferably 50 to 75% by mass.

[0075] (D) is a compound having at least one secondary thiol group, which contributes to the high adhesive strength of the adhesive layer by being incorporated into the adhesive composition. A secondary thiol group refers to a group with a thiol group (-SH) bonded to a secondary carbon atom (-C(H)-).

[0076] Examples of components (C) include compounds having a secondary thiol group such as 2-octylthiol, 2-nonylthiol, 2-decylthiol, 1,2-propanedithiol, 1,2-butanedithiol, 1,3-butanedithiol, and 1,2,3-propanetrithiol.

[0077] Compounds containing two secondary thiol groups, such as 1,4-bis(3-mercaptobutyrooxy)butane and tetraethylene glycol bis(2-mercaptopropionate);

[0078] Compounds containing three secondary thiol groups, such as trimethylolpropane tris(2-mercaptopropionate), trimethylolpropane tris(3-mercaptobutyrate), and 1,3,5-tris(3-mercaptobutyryloxyethyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione.

[0079] Compounds containing four secondary thiol groups, such as pentaerythritol tetra(2-mercaptopropionate) and pentaerythritol tetra(3-mercaptobutyrate), can be used alone or in combination of two or more.

[0080] In addition, commercially available products containing component (D) include, for example, "Karenz MT D1", "Karenz MT TPMB", "Karenz MT NR1", and "Karenz MT PE1" (all manufactured by Showa Denko Co., Ltd.).

[0081] Of the components in (D) above, compounds having two or more secondary thiols are preferred from the perspective of exhibiting excellent heat resistance in the adhesive layer, and more preferably trimethylolpropane tris(3-mercaptobutyrate), 1,3,5-tris(3-mercaptobutyryloxyethyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, pentaerythritol tetra(2-mercaptopropionate), and pentaerythritol tetra(3-mercaptobutyrate).

[0082] The content of component (D) is preferably 0.1 to 5 parts by mass, more preferably 0.2 to 3 parts by mass, relative to a total of 100 parts by mass of components (A), (B) and (C), based on the aspect that the adhesive layer exhibits high adhesion and excellent heat resistance.

[0083] From the perspective that the adhesive layer exhibits a high storage modulus at high temperatures, the adhesive composition of the present invention may further include multifunctional monomers. Examples include hexanediol di(meth)acrylate, polyethylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol di(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol di(meth)acrylate, dipentaerythritol tri(meth)acrylate, dipentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, epoxy (meth)acrylate, polyester (meth)acrylate, urethane (meth)acrylate, and other (meth)acrylates. They can be used alone or in combination of two or more. Furthermore, there is no particular limitation on the amount of the aforementioned multifunctional monomers used, but it is generally 10 parts by weight or less, preferably 5 parts by weight or less, relative to 100 parts by weight of the adhesive composition of the present invention.

[0084] The adhesive composition of the present invention may contain various known additives as needed. There are no particular limitations on the additives; examples include surface conditioners, surfactants, ultraviolet absorbers, antioxidants, light stabilizers, inorganic fillers, silane coupling agents, colloidal silica, defoamers, wetting agents, rust inhibitors, etc. These can be used alone or in combination of two or more.

[0085] The adhesive composition of the present invention is obtained by mixing component (A), component (B), component (C), and component (D), along with the aforementioned multifunctional monomers and additives as needed. The mixing method and order are not particularly limited. Alternatively, when component (A) is diluted with component (B), components (C) and (D), along with the aforementioned monomers and additives as needed, can be mixed in a solution of component (A) and component (B).

[0086] The adhesive composition of the present invention is substantially solvent-free, but may contain organic solvents if the content is less than 1% by mass, preferably less than 0.1% by mass. It should be noted that examples of organic solvents include, for instance, aromatic hydrocarbons such as benzene, toluene, ethylbenzene, n-propylbenzene, tert-butylbenzene, o-xylene, m-xylene, p-xylene, tetrahydronaphthalene, decahydronaphthalene, and aromatic naphtha; aliphatic hydrocarbons such as n-hexane, n-heptane, n-octane, isooctane, and n-decane; alicyclic hydrocarbons such as cyclohexane; and ethyl acetate, n-butyl acetate, n-pentyl acetate, 2-hydroxyethyl acetate, and 2-ethyl acetate. Esters such as butoxyethyl ester, 3-methoxybutyl acetate, and methyl benzoate; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, isophorone, cyclohexanone, and methyl cyclohexanone; glycol ethers such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, and diethylene glycol monobutyl ether; and alcohols such as methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, sec-butanol, and tert-butanol.

[0087] The adhesive composition of the present invention is combined with a photopolymerization initiator when irradiated with active energy rays. The photopolymerization initiator is not particularly limited, and examples include photopolymerization initiators such as benzoin compounds, acetophenone compounds, phosphine oxide compounds, titanium dioxide compounds, thioxanone compounds, and oxime ester compounds, as well as photosensitizers such as amines and quinones. More specifically, examples include 2,2-dimethoxy-1,2-diphenylethane-1-one, 1-hydroxycyclohexylphenyl ketone, 2-hydroxy-2-methyl-1-phenylpropane-1-one, and 1-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methyl-1-propane. Alkyl-1-one, 2-hydroxy-1-[4-[4-(2-hydroxy-2-methyl-propanoyl)-benzyl]phenyl]-2-methyl-propane-1-one, 2-methyl-1-(4-methylthiophenyl)-2-morpholinopropane-1-one, 2-(dimethylamino)-2-[(4-methylphenyl)methyl]-1-[4-(4-morpholinyl)phenyl]-1-butanone, diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide, bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, bis(η 5 -2,4-cyclopentadien-1-yl)-bis(2,6-difluoro-3-(1H-pyrrolo-1-yl)-phenyl)titanium, 1,2-octanedione 1-[4-(phenylthio)-2-(o-benzoyl oxime)], acetone 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazole-3-yl]-1-(o-acetyl oxime), etc. They can be used alone or in combination of two or more.

[0088] The content of the photopolymerization initiator is not particularly limited, but from the perspective of the excellent heat resistance of the adhesive layer, it is usually about 0.1 to 10 parts by mass relative to the total of 100 parts by mass of components (A) to (D), preferably about 0.1 to 3 parts by mass, and more preferably about 0.1 to 2 parts by mass.

[0089] The cured product of the present invention is formed by curing the above-mentioned adhesive composition.

[0090] The cured product of the present invention is obtained by coating the above-mentioned adhesive composition onto a substrate and then irradiating it with active energy rays.

[0091] The substrate is not particularly limited, and examples include polyethylene terephthalate (PET), cyclic olefin polymers (COP), polypropylene, polybutene, polybutadiene, polymethylpentene, polyvinyl chloride, vinyl chloride copolymer, polyethylene naphthalate, polybutylene terephthalate, polyurethane, ethylene vinyl acetate, ionomer resin, ethylene-(meth)acrylate copolymer, ethylene-(meth)acrylate copolymer, polystyrene, polycarbonate, polyimide, and fluorinated resins. Additionally, cross-linked films or laminated films of these materials can also be used. These films can be any of the following: untreated films, films subjected to light to heavy peel treatment, and films with an easy-to-adhere layer.

[0092] Furthermore, there are no particular limitations on the coating method; examples include applicators, bar coaters, roller coaters, die coaters, comma coaters, doctor blade coaters, and gravure coaters. The coating amount of the active energy ray-cured adhesive composition is also not particularly limited; coating is typically performed so that the cured film thickness reaches 10–500 μm, preferably 25–250 μm.

[0093] The term "active energy ray" is not particularly limited, and examples include ultraviolet light, infrared light, visible light, electron beams, X-rays, alpha rays, beta rays, gamma rays, neutron beams, etc. In this invention, light is preferred, and ultraviolet light is more preferred.

[0094] There are no particular limitations on the source of ultraviolet light; examples include xenon lamps, high-pressure mercury lamps, metal halide lamps, and UV-LEDs. Furthermore, there are no particular limitations on the cumulative light intensity and transmission speed of ultraviolet light; the cumulative light intensity is typically 100–3000 mJ / cm². 2 The transmission speed is usually around 5 to 50 m / min.

[0095] The resulting solidified material has a storage modulus G' of 0.3 MPa or more at a temperature of 25°C and a frequency of 1 Hz, preferably 0.5 MPa or more.

[0096] In addition, the storage modulus G' of the above-mentioned solidified material at a temperature of 100°C and a frequency of 1Hz is 0.1MPa or more, preferably 0.12MPa or more.

[0097] The laminate of the present invention has the above-described cured material on at least one side of the substrate. The substrate, coating method, irradiation conditions, etc., used are the same as described above.

[0098]

Example

[0099] The present invention will now be specifically described through examples and comparative examples. It should be noted that the technical scope of the present invention is not limited thereto. Unless otherwise specified, "parts" and "%" in the examples refer to mass.

[0100] Manufacturing Example 1

[0101] In a reaction apparatus equipped with a condenser, a stirrer, and a nitrogen inlet, 870 parts of polypropylene glycol (trade name: "Adeka Polyester P-2000", manufactured by ADEKA Co., Ltd.) with a number average molecular weight of 2000, 113 parts of isophorone diisocyanate (hereinafter referred to as IPDI), 0.4 parts of p-hydroxyanisole (Japanese original: メトキノン, hereinafter referred to as MQ), and 0.1 parts of stannous octoate were added. The mixture was heated to 70°C and held for 3 hours to obtain an isocyanate-terminated urethane prepolymer as an intermediate. Next, 17 parts of 2-hydroxyethyl acrylate (hereinafter referred to as HEA) were added, and the mixture was held at 70°C for 2 hours. The NCO value was measured to confirm the end of the reaction, thereby obtaining component (A-1) with a weight average molecular weight of 39000 and an average number of acryloyl groups of 2. It should be noted that the NCO value was measured according to JIS K 1603-1 (the same applies below).

[0102] Manufacturing Example 2

[0103] 884 parts of P-2000, 106 parts of IPDI, 0.4 parts of MQ, and 0.1 parts of stannous octoate were added to the same reaction apparatus as in Manufacturing Example 1. The mixture was heated to 70°C and held for 3 hours to obtain an isocyanate-terminated urethane prepolymer as an intermediate. Next, 10 parts of 4-hydroxybutyl acrylate (hereinafter referred to as 4-HBA) were added, and the mixture was held at 70°C for 2 hours. The NCO value was measured to confirm the end of the reaction, thereby obtaining component (A-2) with a weight-average molecular weight of 70,000 and an average number of acryloyl groups of 2.

[0104] Manufacturing Example 3

[0105] 883 parts of P-2000, 108 parts of dicyclohexylmethane diisocyanate, 0.4 parts of MQ, and 0.1 parts of stannous octoate were added to the same reaction apparatus as in Manufacturing Example 1. After heating to 70°C and holding at that temperature for 3 hours, a hydroxyl-terminated urethane prepolymer as an intermediate was obtained. Next, 9 parts of ethyl 2-isocyanate (trade name: "Karenz MOI") (hereinafter referred to as Karenz MOI) were added, and the mixture was held at 70°C for 2 hours. The NCO value was measured to confirm the end of the reaction, thereby obtaining component (A-3) with a weight average molecular weight of 45,000 and an average number of acryloyl groups of 2.

[0106] Manufacturing Example 4

[0107] 918 parts of P-2000, 72 parts of hexamethylene diisocyanate, 0.4 parts of MQ, and 0.1 parts of stannous octoate were added to the same reaction apparatus as in Manufacturing Example 1. The mixture was heated to 70°C and held for 3 hours to obtain a hydroxyl-terminated urethane prepolymer as an intermediate. Next, 9 parts of Karenz MOI were added, and the mixture was held at 70°C for 2 hours. The NCO value was measured to confirm the end of the reaction, thereby obtaining component (A-4) with a weight-average molecular weight of 45,000 and an average number of acryloyl groups of 2.

[0108] Comparative Manufacturing Example 1

[0109] 732 parts of P-2000, 163 parts of IPDI, 0.4 parts of MQ, and 0.1 parts of stannous octoate were added to the same reaction apparatus as in Manufacturing Example 1. The mixture was heated to 70°C and held at that temperature for 3 hours to obtain an isocyanate-terminated urethane prepolymer as an intermediate. Next, 105 parts of 4-HBA were added, and the mixture was held at 70°C for 2 hours. The NCO value was measured to confirm the end of the reaction, thereby obtaining component (G-1) with a weight-average molecular weight of 8000 and an average number of acryloyl groups of 2.

[0110] Comparative Manufacturing Example 2

[0111] 972 parts of a polyether polyol (trade name: "PREMINOL S 4103F", manufactured by AGC Corporation) with a number average molecular weight of 12,000, 22 parts of IPDI, 0.4 parts of MQ, and 0.1 parts of stannous octoate were added to the same reaction apparatus as in Manufacturing Example 1. The mixture was heated to 70°C and held at that temperature for 3 hours to obtain an isocyanate-terminated urethane prepolymer as an intermediate. Next, 6 parts of 4-HBA were added, and the mixture was held at 70°C for 2 hours. The NCO value was measured to confirm the end of the reaction, thereby obtaining a (G-2) component with a weight average molecular weight of 100,000 and an average number of acryloyl groups of 2.

[0112] Example 1

[0113] The components (A-1), 2-ethylhexyl acrylate (B1), 4-hydroxybutyl acrylate (B2), o-phenylphenoxyethyl acrylate (C), and pentaerythritol tetra(3-mercaptobutyrate) (D) were mixed in the proportions shown in Table 1, and then 1 part of 1-hydroxycyclohexylphenyl ketone (trade name: "Omnirad 184", manufactured by IGM Resins) was further mixed in as a photopolymerization initiator to obtain an active energy radiation-curable adhesive composition.

[0114] Examples 2-12, Comparative Examples 1-6

[0115] The compositions and proportions were changed to those shown in Table 1, and the same procedure was followed as in Example 1 to obtain active energy ray-cured adhesive compositions. It should be noted that the adhesive composition of Comparative Example 4 exhibited poor storage stability; therefore, the following items were not evaluated.

[0116] <Creating Layered Bodies>

[0117] The adhesive compositions of each example and comparative example were coated onto a 75 μm thick heavily peel-treated polyester film (manufactured by PANAC Corporation, trade name "SP-PET-03-75BU") with a cured film thickness of 100 μm. The peel-treated surface of a 38 μm thick lightly peel-treated polyester film (manufactured by PANAC Corporation, trade name "SP-PET-01-38BU") was then bonded onto the coated layer.

[0118] Next, in the atmosphere, a high-pressure mercury lamp (100mW / cm²) was used. 2 900mJ / cm 2 Irradiate with ultraviolet light to produce a pre-laminated material (lightly peeled polyester film / cured material / heavily peeled polyester film).

[0119] Next, the lightly peeled polyester film was peeled off from the pre-laminated body. Instead, a 50μm thick polyester film (manufactured by Toyobo Co., Ltd., trade name "Cosmoshine A-4300") was laminated using a 2kg roller and left for 2 hours. Then, an 8cm × 8cm test piece was cut from it, and the heavily peeled polyester film was peeled off, thus obtaining a single-sided adhesive sheet (Cosmoshine A-4300 / cured product).

[0120] A laminate (Cosmoshine A-4300 / cured product / glass) was prepared by bonding a 2kg roller to a glass plate and placing it at 25°C and 50% humidity for 24 hours. It should be noted that in the adhesive composition of Comparative Example 1, the adhesive layer peeled off from the glass plate, so the following items were not evaluated.

[0121] <Adhesive Force>

[0122] Using a commercially available testing machine (Tensilon universal testing machine manufactured by A&D Corporation), the glass plate was peeled off along a 180° direction at a speed of 300 mm / min in the above-mentioned laminate, and the adhesion strength (N / 25 mm) of the cured product was measured. A value exceeding 10 N / 25 mm was considered good. The results are shown in Table 1.

[0123] <Resistance to damp heat>

[0124] After each laminate was left to stand in a constant temperature and humidity bath for 500 hours at 85°C and 85% humidity, the resistance of the cured material to damp heat was evaluated according to the following criteria.

[0125] <Evaluation Criteria>

[0126] ○: There were no issues with substrate peeling, adhesive layer misalignment, air bubbles in the adhesive layer, or adhesive layer damage.

[0127] ×: At least one of the following defects occurs: substrate peeling, adhesive layer misalignment, air bubbles in the adhesive layer, or adhesive layer breakage.

[0128] <Heat resistance>

[0129] After cutting a 2.5cm × 2.5cm test piece from the pre-laminated body, peel off the lightly peeled polyester film and instead use a 2kg roller to attach a 50μm thick polyester film (2.5cm × 8cm) to the adhesive layer of the test piece, and leave it for 2 hours.

[0130] Next, after obtaining a single-sided adhesive sheet (Cosmoshine A-4300 / cured product) by peeling and re-peeling the polyester film, the adhesive layer of the adhesive sheet is bonded to a stainless steel plate (2.5cm×8cm) using a 2kg roller and placed at 25°C and 50%RH for 24 hours.

[0131] According to JIS Z-1524, a 1 kg load was applied to one end of the single-sided adhesive sheet in the vertical direction, and the time until the adhesive tape deviated and detached was measured in a holding force testing machine (manufactured by TESTERSANGYO Co., Ltd., creep testing machine (with constant temperature bath)) at 100°C. The evaluation criteria are shown below.

[0132] ○: The time until the adhesive tape falls off is more than 240 hours.

[0133] ×: The time until the adhesive tape falls off is less than 240 hours.

[0134] <Energy Storage Modulus>

[0135] After cutting a 1cm×1cm test piece from the pre-laminated body, the lightly peeled polyester film and the heavily peeled polyester film are peeled off to obtain the adhesive sheet.

[0136] Ten overlapping sheets were used to prepare an adhesive layer with a thickness of 1 mm. The dynamic viscoelasticity was measured using a commercially available testing machine (product name "MCR302", manufactured by Anton Paar) under the following conditions. Then, the storage modulus G' (unit: MPa) at 25°C and 100°C was calculated based on the measurement results.

[0137] (Measurement conditions)

[0138] Deformation mode: Torsion

[0139] Measurement frequency: 1Hz

[0140] Strain: 0.01~1% Automatic setting

[0141] Heating rate: 3℃ / minute

[0142] Measurement temperature: -50~100℃

[0143] Shape: Parallel plate 8.0mmφ

[0144] Table 1

[0145]

[0146] ※1: The content of thiols is expressed as parts by mass of 100 parts by mass relative to the total solid content of components (A), (B) and (C).

[0147] The symbols and abbreviations in Table 1 refer to the following compounds.

[0148] <Polyurethane (Meth)acrylate>

[0149] • A-1: ​​Polyurethane acrylate of Example 1

[0150] •A-2: Polyurethane acrylate of Manufacturing Example 2

[0151] • A-3: Polyurethane acrylate of Example 3

[0152] • A-4: Polyurethane acrylate of Example 4

[0153] • G-1: Comparative manufacturing example 1 of polyurethane acrylate

[0154] • G-2: Comparative manufacturing example 2 of polyurethane acrylate

[0155] <Alkyl mono(meth)acrylate>

[0156] B-1: 2-Ethylhexyl acrylate

[0157] B-2: 4-Hydroxybutyl acrylate

[0158] <Mono(meth)acrylates with aromatic rings>

[0159] • C-1: o-Phenylphenoxyethyl acrylate (with 2 aromatic rings)

[0160] • C-2: m-phenoxybenzyl acrylate (with 2 aromatic rings)

[0161] E-1: Benzyl acrylate (with one aromatic ring)

[0162] <Thiols>

[0163] • D-1: Pentaerythritol tetra(3-mercaptobutyrate), trade name: "Karenz MT PE1", manufactured by Showa Denko Corporation.

[0164] F-1: Pentaerythritol tetra(3-mercaptopropionate).

Claims

1. An active energy ray-curable adhesive composition comprising: a polyurethane (meth)acrylate (A) which is a reaction product of a polyol (al), a polyisocyanate (a2), and a hydroxyl group-containing mono(meth)acrylate (a3-1) or a reaction product of a polyol (al), a polyisocyanate (a2), and an isocyanate group-containing mono(meth)acrylate (a3-2), the average number of (meth)acryloyl groups of the polyurethane (meth)acrylate (A) being 1 to 4, and the weight average molecular weight being 10,000 to 90,000; a mono(meth)acrylate alkyl ester (B); a mono(meth)acrylate having at least 2 aromatic rings (C); and a compound having a secondary mercaptan group (D), the mono(meth)acrylate having at least 2 aromatic rings (C) being one or two or more selected from the group consisting of o-phenylphenoxyethyl (meth)acrylate, m-phenylphenoxyethyl (meth)acrylate, p-phenylphenoxyethyl (meth)acrylate, o-phenoxybenzyl (meth)acrylate, m-phenoxybenzyl (meth)acrylate, p-phenoxybenzyl (meth)acrylate, ethoxylated-o-phenylphenol (meth)acrylate, ethoxylated-m-phenylphenol (meth)acrylate, ethoxylated-p-phenylphenol (meth)acrylate, oxirane-modified o-cumylphenol (meth)acrylate, oxirane-modified m-cumylphenol (meth)acrylate, oxirane-modified p-cumylphenol (meth)acrylate, and triphenylmethyl (meth)acrylate, the compound having a secondary mercaptan group (D) being one or two or more selected from the group consisting of 2-octanethiol, 2-nonanethiol, 2-decanethiol, 1,2-propanedithiol, 1,2-butanedithiol, 1,3-butanedithiol, 1,2,3-propanetriol, 1,4-bis(3-mercaptobutyryloxy)butane, tetraethylene glycol bis(2-mercaptopropionate), trimethylolpropane tris(2-mercaptopropionate), trimethylolpropane tris(3-mercaptobutyrate), 1,3,5-tris(3-mercaptobutyryloxyethyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, pentaerythritol tetra(2-mercaptopropionate), and pentaerythritol tetra(3-mercaptobutyrate), the content ratio of the (A) component being 10 to 49 mass% with respect to 100 mass% of the total of the (A) component, the (B) component, and the (C) component, the content ratio of the (B) component being 10 to 35 mass%, and the content ratio of the (C) component being 30 to 75 mass%, the content of the (D) component being 0.1 to 5 parts by mass with respect to 100 parts by mass of the total of the (A) component, the (B) component, and the (C) component.

2. The active energy ray-curable adhesive composition according to claim 1, wherein, the (al) component comprising a polyether polyol.

3. The active energy ray-curable adhesive composition according to claim 1 or 2, the (B) component comprising a mono(meth)acrylate alkyl ester (Bl) and / or a mono(meth)acrylate hydroxyalkyl ester (B2) which do not contain a hydroxyl group.

4. The active energy ray-curable adhesive composition according to claim 1 or 2, wherein the component (D) is a compound having 2 or more secondary mercaptan groups.

5. A cured product of the active energy ray-curable adhesive composition according to any one of claims 1 to 4.

6. The cured product according to claim 5, which has a storage modulus G' of 0.3 MPa or more at a temperature of 25°C and a frequency of 1 Hz, and a storage modulus G' of 0.1 MPa or more at a temperature of 100°C and a frequency of 1 Hz.

7. A laminate having the cured product according to claim 5 or 6 on at least one side of a substrate.

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