Active energy radiation-cured adhesive composition, cured product and adhesive sheet

Abstract

The purpose of this invention is to provide an active energy radiation-curable adhesive composition, a cured product, and an adhesive sheet with good bending resistance. This invention relates to an active energy ray-curable adhesive composition, which contains: (A): A reactant of (a1) a polyol, (a2) an aliphatic polyisocyanate and (a3-1) a mono(meth)acrylate containing a hydroxyl group or (a3-2) a mono(meth)acrylate containing an isocyanate group, wherein the weight average molecular weight is 30,000 or more and 150,000 or less. (B): A (meth)acrylate with one vinyl unsaturated double bond and no hydroxyl group in the molecule. (C): Mono(meth)acrylates containing primary hydroxyl groups; Among them, component (B) contains (meth)acrylate (b1) and / or (meth)acrylate (b2), wherein the (meth)acrylate (b1) has a glass transition temperature of less than -5°C when it is a homopolymer, and the (meth)acrylate (b2) has a glass transition temperature of more than -5°C when it is a homopolymer. When the total percentage of component (A), component (B), and component (C) is 100% by mass, (A) The content of the solid component, converted from its content, is greater than 35% by mass and less than 55% by mass. (B) The content of the solid component, converted from its composition, is 30% by mass or more and 55% by mass or less. (C) The content of solid components, converted from their equivalent values, is 9% by mass or more and less than 20% by mass; When the total amount of (meth)acrylates constituting component (B) is 100% by mass, (b1) The content of the solid component, converted from its composition, is 71% by mass or more and 100% by mass or less. (b2) The content of the solid component of the ingredient is more than 0% by mass and less than 29% by mass.

Description

Actinic energy ray-curable adhesive composition, cured product, and adhesive sheet The present invention relates to an actinic energy ray-curable adhesive composition, a cured product, and an adhesive sheet. In recent years, adhesive compositions having characteristics suitable for foldable devices (e.g., foldable image display devices, etc.) have been developed. However, when a foldable device is bent, strong loads are applied to each layer constituting the device, and various problems may occur. For example, when folding the device, the layer of the adhesive composition (in the present invention, the "cured product" is also referred to as the "adhesive composition layer") may peel off, etc. Therefore, a cured product that does not peel off even when folded is required. In Patent Document 1, an actinic energy ray-curable adhesive composition containing urethane (meth)acrylate, alkyl mono(meth)acrylate, and mono(meth)acrylate containing a primary hydroxyl group (in the present invention, the "actinic energy ray-curable adhesive composition" is also referred to as the "adhesive composition") is disclosed. [Prior Art Documents] [Patent Documents] [Patent Document 1] Japanese Patent Application Laid-Open No. 2020-037689 [Technical Problem to be Solved by the Invention] In Patent Document 1, no study on bend resistance was conducted. An object of the present invention is to provide an actinic energy ray-curable adhesive composition, a cured product, and an adhesive sheet having good bend resistance. [Technical Means] As a result of intensive studies, the present inventors have found that the above problems can be solved by a specific actinic energy ray-curable adhesive composition, its cured product, and an adhesive sheet having the cured product. Further, the present invention is an invention made to solve at least a part of the above problems and can be implemented as the following aspects or application examples. That is, the present invention relates to the following items. (Item 1) A radiation-curable adhesive composition containing: (A): A urethane (meth)acrylate (A) having a weight average molecular weight of 30,000 or more and 150,000 or less, which is a reaction product of (a1) a polyol, (a2) an aliphatic polyisocyanate, and (a3-1) a mono(meth)acrylate containing a hydroxyl group or (a3-2) a mono(meth)acrylate containing an isocyanate group, (B): A (meth)acrylate having one ethylenically unsaturated double bond in the molecule and no hydroxyl group, (C): A mono(meth)acrylate containing a primary hydroxyl group; wherein the component (B) contains the (meth)acrylate (b1) and / or the (meth)acrylate (b2), the glass transition temperature of the (meth)acrylate (b1) when it becomes a homopolymer is less than -5°C, and the glass transition temperature of the (meth)acrylate (b2) when it becomes a homopolymer is -5°C or more; when the total of the components (A), (B), and (C) is 100% by mass, the content of the component (A) in terms of solid content is more than 35% by mass and 55% by mass or less, the content of the component (B) in terms of solid content is 30% by mass or more and 55% by mass or less, and the content of the component (C) in terms of solid content is 9% by mass or more and less than 20% by mass; when the total of the (meth)acrylates constituting the component (B) is 100% by mass, the content of the component (b1) in terms of solid content is 71% by mass or more and 100% by mass or less, and the content of the component (b2) in terms of solid content is 0% by mass or more and 29% by mass or less. (Item 2) The radiation-curable adhesive composition according to Item 1, wherein the radiation-curable adhesive composition does not contain a resin having a softening point of 90°C or more in an amount of 1% by mass or more based on the total of 100% by mass of the components (A), (B), and (C). (Item 3) A cured product obtained from the radiation-curable adhesive composition according to Item 1 or 2. (Item 4) An adhesive sheet having the cured product according to Item 3 on at least one surface of a substrate surface. [Effects of the Invention] The radiation-curable adhesive composition, cured product, and adhesive sheet of the present invention can exhibit good flexural resistance. In the whole of the present invention, numerical ranges of various physical property values, contents, etc. can be appropriately set (for example, selected from the upper and lower limit values described in the following items). Specifically, regarding the numerical value α, when A1, A2, A3, etc. are listed as the lower limit of the numerical value α and B1, B2, B3, etc. are listed as the upper limit of the numerical value α, the range of the numerical value α can include A1 or more, A2 or more, A3 or more, B1 or less, B2 or less, B3 or less, A1 to B1, A1 to B2, A1 to B3, A2 to B1, A2 to B2, A2 to B3, A3 to B1, A3 to B2, A3 to B3, etc. Also, in the present invention, the so-called "~" is used to indicate that the numerical values described before and after it are included as the lower limit value and the upper limit value. Hereinafter, the components and manufacturing methods of the present invention will be described in detail. <(A) component> The (A) component is a reaction product of (a1) a polyol, (a2) an aliphatic polyisocyanate, and (a3-1) a mono(meth)acrylate containing a hydroxyl group or (a3-2) a mono(meth)acrylate containing an isocyanate group, and is a urethane (meth)acrylate having a weight average molecular weight of 30,000 or more and 150,000 or less. <(a1) component> Since a polyol is used as the (a1) component, the cured product of the present invention has excellent transparency and flexural resistance. Examples of the (a1) component include polyether polyols, polyester polyols, polymer polyols, poly(meth)acrylate polyols, polycarbonate polyols, castor oil-based polyols, and polyolefin polyols. Also, in the present invention, the so-called (meth)acrylate means acrylic acid and / or methacrylic acid. Examples of the polyether polyol include polyethylene glycol, polypropylene glycol, polytetramethylene ether glycol, and polytetramethylene glycol. The polyether polyol can be a commercially available product. Examples of such products include polyether diol (product name: "ADEKA POLYETHER P", manufactured by ADEKA Corporation), polyether triol (product name: "ADEKA POLYETHER G", manufactured by ADEKA Corporation), polyether tetrol (product name: "ADEKA POLYETHER EDP", manufactured by ADEKA Corporation), polyethylene glycol (product name: "Polyethylene Glycol #1,540", manufactured by NACALAI TESQUE, Inc.), dipropylene glycol (product name: "Dipropylene glycol", manufactured by Junsei Chemical Co., Ltd.), polypropylene glycol (product name: "Polypropylene Glycol 400", manufactured by Kishida Chemical Co., Ltd.), polytetramethylene ether glycol (product names: "PTMG650", "PTMG1000", "PTMG2000", "PTMG3000", manufactured by Mitsubishi Chemical Corporation), etc. The polyester polyol can be a commercially available product. Examples of such products include polyester polyols of high refractive index grade (product name: "POLYLITE RX-4800", manufactured by DIC Corporation), polyester polyols of high crystallinity grade (product names: "POLYLITE OD-X-2523", "POLYLITE OD-X-2547", manufactured by DIC Corporation), polyester polyols of transparent grade (product names: "POLYLITE OD-X-2420", "POLYLITE OD-X-2692", manufactured by DIC Corporation), polyester polyols of high adhesiveness grade (product name: "POLYLITE OD-X-2108", manufactured by DIC Corporation), polyester polyol (product name: "ETERNACOLL3000", manufactured by Ube Industries, Ltd.), polycaprolactone polyol (product name: "POLYLITE OD-X-2155", manufactured by DIC Corporation), polycaprolactone diol (product name: "PLACCEL 200", manufactured by Daicel Corporation), polycaprolactone triol (product name: "PLACCEL 300", manufactured by Daicel Corporation), polycaprolactone tetrol (product name: "PLACCEL 400", manufactured by Daicel Corporation), etc. The polymer polyol can be a commercially available product. Examples of such products include polymer polyol (product name: "SHARPFLOW", manufactured by Sanyo Chemical Industries, Ltd.), polymer polyol (product name: "EXCENOL", manufactured by AGC, Inc.), etc. The poly(meth)acrylic polyol can be a commercially available product. Examples of such products include acrylic polyols (product name: "ACRYLIC POLYOL ♯6000", manufactured by Taisei Fine Chemical Co., Ltd.), acrylic polyols (product name: "ETERAC7315-XS-60", manufactured by Chang Chun Materials Industry Co., Ltd.), acrylic polyols (product name: "ACRYLIC POLYOL PC♯5984", manufactured by Toei Kasei Co., Ltd.), and the like. The polycarbonate polyol can be a commercially available product. Examples of such products include polycarbonate diols (product name: "BENEBiOL", manufactured by Mitsubishi Chemical Corporation), (product name: "NIPPOLLAN", manufactured by Tosoh Corporation), (product name: "DURANOL series", manufactured by Asahi Kasei Corporation), and the like. The castor oil-based polyol can be a commercially available product. Examples of such products include castor oil-based polyols (product name: "URIC H series", manufactured by Ito Oil Co., Ltd.), castor oil-based polyols (product name: "CASTOR OIL-BASED POLYOL HS CM-025P", "CASTOR OIL-BASED POLYOL HS CM-075P", manufactured by Hokoku Corporation), and the like. Examples of polyolefin polyols include hydroxyl-containing polybutadiene, hydrogenated hydroxyl-containing polybutadiene, hydroxyl-containing polyisoprene, hydrogenated hydroxyl-containing polyisoprene, hydroxyl-containing chlorinated polypropylene, hydroxyl-containing chlorinated polyethylene, and the like. The polyolefin polyol can be a commercially available product. Examples of such products include polybutadiene diols (product name: "Poly bd R-45HT", "Poly bd R-15HT", manufactured by Idemitsu Kosan Co., Ltd.) (product name: "NISSO-PB B-1000", "NISSO-PB B-2000", "NISSO-PB G-1000", "NISSO-PB G-2000", manufactured by Nippon Soda Co., Ltd.), hydrogenated polybutadiene diols (product name: "NISSO-PB GI-1000", "NISSO-PB GI-2000", manufactured by Nippon Soda Co., Ltd.), and the like. As the upper limit of the number average molecular weight of the (a1) component, examples include 13,000, 12,000, 11,000, 10,000, 9,000, 8,000, 7,000, 6,000, 5,000, 4,000, 3,000, 2,000, 1,000, 900, 800, etc.; as the lower limit, examples include 12,000, 11,000, 10,000, 9,000, 8,000, 7,000, 6,000, 5,000, 4,000, 3,000, 2,000, 1,000, 900, 800, 700, etc. In terms of the cured product having excellent adhesion and height difference followability, the number average molecular weight of the (a1) component is preferably 700 or more and 13,000 or less. When the number average molecular weight of the (a1) component is less than the above lower limit, the cured product tends to become hard, and when it exceeds the above upper limit, the cured product tends to become soft. Therefore, when within the above preferred range, the adhesion and height difference followability tend to become good. In the present invention, the number average molecular weight can be determined by the method described in JIS K7252-1:2016. As the upper limit of the number of hydroxyl groups of the (a1) component, examples include 3.0, 2.8, 2.5, 2.3, 2.0, 1.8, etc.; as the lower limit, examples include 2.8, 2.5, 2.3, 2.0, 1.8, 1.5, etc. In terms of the cured product having excellent height difference followability and processability, the number of hydroxyl groups of the (a1) component is preferably 1.5 or more and 3.0 or less, more preferably 1.8 or more and 2.5 or less. In the present invention, the so-called "height difference followability" and "processability" have the same meaning as those described in JP-A-2020-037689. In 100% by mass (in terms of solid content) of the total amount of the (a1) component, the (a2) component, and the (a3-1) component or the (a3-2) component, as the upper limit of the content of the (a1) component (in terms of solid content), examples include 98% by mass, 95% by mass, 90% by mass, 85% by mass, 80% by mass, 75% by mass, 70% by mass, 65% by mass, 60% by mass, 55% by mass, 50% by mass, 45% by mass, 40% by mass, 35% by mass, 30% by mass, 25% by mass, 20% by mass, 15% by mass, 10% by mass, 5% by mass, etc.; as the lower limit, examples include 95% by mass, 90% by mass, 85% by mass, 80% by mass, 75% by mass, 70% by mass, 65% by mass, 60% by mass, 55% by mass, 50% by mass, 45% by mass, 40% by mass, 35% by mass, 30% by mass, 25% by mass, 20% by mass, 15% by mass, 10% by mass, 5% by mass, 1% by mass, etc. In one embodiment, in 100% by mass (in terms of solid content) of the total amount of the (a1) component, the (a2) component, and the (a3-1) component or the (a3-2) component, the content of the (a1) component (in terms of solid content) is preferably about 1 to 98% by mass. <Component (a2)> The component (a2) is an aliphatic polyisocyanate. Examples of the component (a2) include aliphatic diisocyanates, aliphatic triisocyanates, aliphatic tetraisocyanates, etc. Examples of the component (a2) include linear aliphatic polyisocyanates, branched aliphatic polyisocyanates, alicyclic aliphatic polyisocyanates, etc. Examples of the linear aliphatic diisocyanate include trimethylene diisocyanate, tetramethylene diisocyanate, 1,5-pentamethylene diisocyanate, hexamethylene diisocyanate, octamethylene diisocyanate, decamethylene diisocyanate, etc. Examples of the branched aliphatic diisocyanate include methyl 2,6-diisocyanatohexanoate, trimethylhexamethylene diisocyanate, etc. Examples of the alicyclic aliphatic diisocyanate include dicyclohexylmethane-4,4'-diisocyanate, isophorone diisocyanate, 1,3-bis(isocyanatomethyl)cyclohexane, cyclohexane-1,4-diylbis(methylene)diisocyanate, 1-methylcyclohexane-2,4-diyl diisocyanate, 1,4-cyclohexane diisocyanate, hydrogenated xylylene diisocyanate, hydrogenated tolylene diisocyanate, norbornene diisocyanate, etc. Examples of the linear aliphatic triisocyanate include lysine triisocyanate, etc. In terms of the excellent durability of the cured product after the wet heat test and excellent height difference followability, the component (a2) is preferably an aliphatic diisocyanate, and more preferably a linear aliphatic diisocyanate and / or an alicyclic aliphatic diisocyanate. In the present invention, the so-called "durability after the wet heat test" has the same meaning as that described in JP-A-2020-037689. The molar ratio of the isocyanate group (NCO （ a2 ） ) of the component (a2) to the molar ratio of the hydroxyl group (OH （ a1 ） ) of the component (a1) (NCO （ a2 ） / OH （a1 ） The upper limits of ( ) can include 2.0, 1.9, 1.8, 1.7, 1.6, 1.5, 1.4, 1.3, 1.2, 1.1, 1.0, 0.9, 0.8, 0.7, 0.6, etc.; as the lower limits, 1.9, 1.8, 1.7, 1.6, 1.5, 1.4, 1.3, 1.2, 1.1, 1.0, 0.9, 0.8, 0.7, 0.6, 0.5, etc. can be enumerated. The number of moles of isocyanate groups (NCO （ a2 ） of component (a2)) and the number of moles of hydroxyl groups (OH （ a1 ） of component (a1)) ratio (NCO （ a2 ） / OH （a1 ） is preferably about 0.5 to 2.0. The upper limits of the molecular weight of component (a2) can include 1000, 950, 900, 850, 800, 750, 700, 650, 600, 550, 500, 450, 400, 350, 300, 250, 200, 150, 100, 50, 25, etc.; as the lower limits, 950, 900, 850, 800, 750, 700, 650, 600, 550, 500, 450, 400, 350, 300, 250, 200, 150, 100, 50, 25, 10, etc. can be enumerated. In one embodiment, the molecular weight of component (a2) is preferably 10 to 1000. In the present invention, when only "molecular weight" is described, it is a value calculated based on atomic weight. As the upper limit of the content ratio (mass ratio, in terms of solid components, [(a1) component / (a2) component]) of the (a1) component and the (a2) component, examples include 99 / 1, 95 / 5, 90 / 10, 85 / 15, 80 / 20, 75 / 25, 70 / 30, 65 / 35, 60 / 40, 55 / 45, 50 / 50, 45 / 55, 40 / 60, 35 / 65, 30 / 70, 25 / 75, 20 / 80, 15 / 85, 10 / 90, 5 / 95, etc.; as the lower limit, examples include 95 / 5, 90 / 10, 85 / 15, 80 / 20, 75 / 25, 70 / 30, 65 / 35, 60 / 40, 55 / 45, 50 / 50, 45 / 55, 40 / 60, 35 / 65, 30 / 70, 25 / 75, 20 / 80, 15 / 85, 10 / 90, 5 / 95, 1 / 99, etc. In one embodiment, the content ratio (mass ratio, in terms of solid components, [(a1) component / (a2) component]) of the (a1) component and the (a2) component is preferably about 1 / 99 to 99 / 1. In 100% by mass (in terms of solid components) of the total amount of the (a1) component, the (a2) component, and the (a3-1) component or the (a3-2) component, as the upper limit of the content (in terms of solid components) of the (a2) component, examples include 98% by mass, 95% by mass, 90% by mass, 85% by mass, 80% by mass, 75% by mass, 70% by mass, 65% by mass, 60% by mass, 55% by mass, 50% by mass, 45% by mass, 40% by mass, 35% by mass, 30% by mass, 25% by mass, 20% by mass, 15% by mass, 10% by mass, 5% by mass, etc.; as the lower limit, examples include 95% by mass, 90% by mass, 85% by mass, 80% by mass, 75% by mass, 70% by mass, 65% by mass, 60% by mass, 55% by mass, 50% by mass, 45% by mass, 40% by mass, 35% by mass, 30% by mass, 25% by mass, 20% by mass, 15% by mass, 10% by mass, 5% by mass, 1% by mass, etc. In one embodiment, in 100% by mass (in terms of solid components) of the total amount of the (a1) component, the (a2) component, and the (a3-1) component or the (a3-2) component, the content (in terms of solid components) of the (a2) component is preferably about 1 to 98% by mass. <(Component (a3-1) or component (a3-2))> Component (a3-1) is a mono(meth)acrylate containing a hydroxyl group, and component (a3-2) is a mono(meth)acrylate containing an isocyanate group. Due to the use of component (a3-1) or component (a3-2), the curability of the adhesive composition is excellent. When manufacturing an adhesive composition that does not contain component (a3-1) or component (a3-2), or uses, for example, a photoinitiator containing a hydroxyl group as a substitute for component (a3-1) or component (a3-2), poor curing occurs, and the cured product becomes too soft at room temperature. When cutting a substrate or the like containing such a cured product, the cured product easily adheres to the surface of the blade of the cutting machine (that is, the processability deteriorates), so an adhesive composition that does not contain component (a3-1) or component (a3-2) is not desirable. Since the transparency also deteriorates when manufacturing an adhesive composition using, for example, a photoinitiator containing a hydroxyl group as a substitute for component (a3-1) or component (a3-2), it is not desirable. Examples of component (a3-1) include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 2-(meth)acryloyloxyethyl-2-hydroxyethyl phthalate, glycerol mono(meth)acrylate, 2-hydroxy-3-phenoxypropyl (meth)acrylate, and the like. Examples of component (a3-2) include 2-isocyanatoethyl (meth)acrylate and the like. From the perspective of excellent curability of the adhesive composition, component (a3-1) or component (a3-2) is preferably a mono(meth)acrylate containing a hydroxyl group having 5 or more and 10 or less carbon atoms, and more preferably one or more selected from the group consisting of 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, and 2-hydroxybutyl (meth)acrylate. Examples of the upper limit of the number of carbon atoms of component (a3-1) or component (a3-2) include 60, 50, 40, 30, 20, 10, 9, 8, 7, 5, 4, etc.; examples of the lower limit include 50, 40, 30, 20, 10, 9, 8, 7, 5, 4, 3, etc. In one embodiment, the number of carbon atoms of component (a3-1) or component (a3-2) is preferably about 4 to 60. As the upper limit of the molecular weight of the component (a3-1) or the component (a3-2), examples include 1000, 950, 900, 850, 800, 750, 700, 650, 600, 550, 500, 450, 400, 350, 300, 250, 200, 150, 100, 50, 25, etc.; as the lower limit, examples include 950, 900, 850, 800, 750, 700, 650, 600, 550, 500, 450, 400, 350, 300, 250, 200, 150, 100, 50, 25, 10, etc. In one embodiment, the molecular weight of the component (a3-1) or the component (a3-2) is preferably 10 to 1000. As the upper limit of the content ratio (mass ratio, in terms of solid components, [(a1) component or (a2) component / (a3-1) component or (a3-2) component]) of the component (a1) or the component (a2) and the component (a3-1) or the component (a3-2), examples include 99.9 / 0.1, 99.5 / 0.5, 99 / 1, 95 / 5, 90 / 10, 85 / 15, 80 / 20, 75 / 25, etc.; as the lower limit, examples include 99.5 / 0.5, 99 / 1, 95 / 5, 90 / 10, 85 / 15, 80 / 20, 75 / 25, 70 / 30, etc. In one embodiment, the content ratio (mass ratio, in terms of solid components, [(a1) component or (a2) component / (a3-1) component or (a3-2) component]) of the component (a1) or the component (a2) and the component (a3-1) or the component (a3-2) is preferably about 70 / 30 to 99.9 / 0.1. In 100% by mass (in terms of solid components) of the total amount of the component (a1), the component (a2), and the component (a3-1) or the component (a3-2), as the upper limit of the content (in terms of solid components) of the component (a3-1) or the component (a3-2), examples include 20% by mass, 15% by mass, 10% by mass, 9% by mass, 8% by mass, 7% by mass, 6% by mass, 5% by mass, 4% by mass, 3% by mass, 2% by mass, 1% by mass, 0.5% by mass, etc.; as the lower limit, examples include 15% by mass, 10% by mass, 9% by mass, 8% by mass, 7% by mass, 6% by mass, 5% by mass, 4% by mass, 3% by mass, 2% by mass, 1% by mass, 0.5% by mass, 0.1% by mass, etc. In one embodiment, in 100% by mass (in terms of solid components) of the total amount of the component (a1), the component (a2), and the component (a3-1) or the component (a3-2), the content (in terms of solid components) of the component (a3-1) or the component (a3-2) is preferably about 0.1 to 20% by mass. <Other additives that can be combined with component (A)> As needed, component (A) may also contain various additives. Examples of the additives include catalysts, crystal nucleating agents, crystallization accelerators, chain transfer agents, etc. An isocyanate group-terminated urethane prepolymer can be produced by reacting component (a1) with component (a2). Then, the isocyanate group-terminated urethane prepolymer is reacted with component (a3-1) to obtain component (A). The reaction conditions are generally a temperature of about 70 to 85°C and a time of about 1 to 5 hours. The usage ratio of the isocyanate group-terminated urethane prepolymer to component (a3-1) is such that the ratio (NCO / OH) of the molar number of the former isocyanate group (NCO) to the molar number of the latter hydroxyl group (OH) can generally be in the range of about 0.25 to 1. A hydroxyl group-terminated urethane prepolymer can be produced by reacting component (a1) with component (a2). Then, the hydroxyl group-terminated urethane prepolymer is reacted with component (a3-2) to obtain component (A). The reaction conditions are generally a temperature of about 70 to 85°C and a time of about 1 to 5 hours. The usage ratio of the hydroxyl group-terminated urethane prepolymer to component (a3-2) is such that the ratio (NCO / OH) of the molar number of the latter isocyanate group (NCO) to the molar number of the former hydroxyl group (OH) can generally be in the range of about 0.5 to 1. Examples of the upper limit of the weight average molecular weight of component (A) include 150000, 140000, 130000, 120000, 110000, 100000, 90000, 80000, 70000, 60000, 50000, 40000, etc.; examples of the lower limit include 140000, 130000, 120000, 110000, 100000, 90000, 80000, 70000, 60000, 50000, 40000, 30000, etc. In terms of the cured product having excellent adhesion, height difference followability, and excellent flexural resistance, the weight average molecular weight of component (A) is 30000 or more and 150000 or less, preferably 50000 or more and 110000 or less. When the weight average molecular weight of component (A) is less than the above lower limit, the adhesion of the cured product weakens, and there is also a tendency for the flexural resistance to deteriorate; when it exceeds the above upper limit, the viscosity of the adhesive composition increases, and there is a tendency for it to become difficult to manufacture. In the present invention, the weight average molecular weight is a polystyrene conversion value obtained by gel permeation chromatography. Examples of the upper limit of the number of (meth)acryloyl groups that component (A) has include 15, 10, 8, 6, 4, 2, etc.; examples of the lower limit include 10, 8, 6, 4, 2, 1, etc. In one embodiment, the number of (meth)acryloyl groups that component (A) has is preferably about 1 to 15. As the upper limit of the (meth)acrylic acid equivalent (g / eq) of the component (A), examples include 150,000, 140,000, 130,000, 120,000, 110,000, 100,000, 90,000, 80,000, 70,000, 60,000, 50,000, 40,000, 30,000, 20,000, 10,000, etc.; as the lower limit, examples include 140,000, 130,000, 120,000, 110,000, 100,000, 90,000, 80,000, 70,000, 60,000, 50,000, 40,000, 30,000, 20,000, 10,000, 5,000, etc. In one embodiment, the (meth)acrylic acid equivalent (g / eq) of the component (A) is preferably about 5,000 to 150,000. In the present invention, the so-called (meth)acrylic acid equivalent is represented by the weight average molecular weight per (meth)acrylic acid group and can be calculated as "weight average molecular weight / number of functional groups". In 100% by mass (in terms of solid content) of the total amount of the component (A), the component (B) and the component (C), as the upper limit of the content of the component (A) (in terms of solid content), examples include 55% by mass, 54% by mass, 53% by mass, 52% by mass, 51% by mass, 50% by mass, 49% by mass, 48% by mass, 47% by mass, 46% by mass, 45% by mass, 44% by mass, 43% by mass, 42% by mass, 41% by mass, 40% by mass, 39% by mass, 38% by mass, 37% by mass, 36% by mass, etc.; as the lower limit, examples include 54% by mass, 53% by mass, 52% by mass, 51% by mass, 50% by mass, 49% by mass, 48% by mass, 47% by mass, 46% by mass, 45% by mass, 44% by mass, 43% by mass, 42% by mass, 41% by mass, 40% by mass, 39% by mass, 38% by mass, 37% by mass, 36% by mass, 35% by mass, etc. In one embodiment, in 100% by mass (in terms of solid content) of the total amount of the component (A), the component (B) and the component (C), the content of the component (A) (in terms of solid content) is greater than 35% by mass and 55% by mass or less. When the content of the component (A) is greater than 55% by mass, since the elastic modulus of the cured product increases and the flexural resistance deteriorates, it is not ideal. There is a tendency that the less the amount of the component (A), the better the flexural resistance. If the content of the component (A) is 35% by mass or less, it is too soft and the processability and cutability of the sheet become poor, so it is not ideal. <(B) component> The (B) component is a (meth)acrylate having one ethylenically unsaturated double bond in the molecule and no hydroxyl group. The (B) component contains (meth)acrylate (b1) and / or (meth)acrylate (b2). The glass transition temperature (also referred to as "Tg" in the present invention) of the (meth)acrylate (b1) when it becomes a homopolymer is less than -5°C, and the glass transition temperature of the (meth)acrylate (b2) when it becomes a homopolymer is -5°C or higher. Since the adhesive composition of the present invention contains the (b1) component, the storage elastic modulus decreases and the flex resistance becomes good. Since the adhesive composition of the present invention contains the (b2) component, the adhesive strength becomes good. Also, the "glass transition temperature when it becomes a homopolymer" uses the value described in the Polymer Handbook of Wiley-Interscience. Examples of the (b1) component include tetradecyl methacrylate (Tg: -72°C), 2-ethylhexyl acrylate (Tg: -70°C), ethoxydiethylene glycol acrylate (Tg: -70°C), isooctyl acrylate (Tg: -70°C), ethyl carbitol acrylate (Tg: -67°C), n-octyl acrylate (Tg: -65°C), lauryl methacrylate (Tg: -65°C), isononyl acrylate (Tg: -58°C), n-butyl acrylate (Tg: -56°C), 2-methoxyethyl acrylate (Tg: -50°C), isodecyl methacrylate (Tg: -41°C), nonyl acrylate (Tg: -37°C), 2-ethoxyethyl methacrylate (Tg: -31°C), isobutyl acrylate (Tg: -26°C), lauryl acrylate (Tg: -23°C), phenoxyethyl acrylate (Tg: -22°C), isooctadecyl acrylate (Tg: -18°C), 2-ethylhexyl methacrylate (Tg: -10°C), (2-methyl-2-ethyl-1,3-dioxolan-4-yl)methyl acrylate (Tg: -7°C), etc. In terms of excellent adhesive strength, the (b1) component is preferably 2-ethylhexyl acrylate and / or n-octyl acrylate. Examples of the component (b2) include 2-methoxyethyl methacrylate (Tg: -2°C), (3-ethyl-3-oxetanyl)methyl methacrylate (Tg: 2°C), benzyl acrylate (Tg: 6°C), methyl acrylate (Tg: 8°C), cyclohexyl acrylate (Tg: 15°C), diethylaminoethyl methacrylate (Tg: 16 - 24°C), dimethylaminoethyl methacrylate (Tg: 18°C), n-butyl methacrylate (Tg: 20°C), cyclic trimethylolpropane formal acrylate (Tg: 27°C), n-octadecyl acrylate (Tg: 30°C), n-octadecyl methacrylate (Tg: 38°C), tert-butyl acrylate (Tg: 41°C), glycidyl methacrylate (Tg: 46°C), isobutyl methacrylate (Tg: 48°C), 3,3,5-trimethylcyclohexyl acrylate (Tg: 52°C), benzyl methacrylate (Tg: 54°C), tetrahydrofurfuryl methacrylate (Tg: 60°C), glycidyl acrylate (Tg: 60°C), ethyl methacrylate (Tg: 65°C), cyclohexyl methacrylate (Tg: 66°C), isobornyl acrylate (Tg: 97°C), methyl methacrylate (Tg: 105°C), tert-butyl methacrylate (Tg: 107°C), dicyclopentyl acrylate (Tg: 120°C), 1-adamantyl acrylate (Tg: 153°C), 1-adamantyl methacrylate (Tg: 250°C), etc. In terms of excellent adhesiveness, the component (b2) is preferably isobornyl acrylate and / or dicyclopentyl acrylate. Examples of the upper limit of the carbon number of the component (B) include 30, 25, 20, 15, 10, 9, 8, 7, 6, 5, 4, 3, etc.; examples of the lower limit include 25, 20, 15, 10, 9, 8, 7, 6, 5, 4, 3, 2, etc. In one embodiment, the carbon number of the component (B) is preferably 6 or more and 15 or less. Examples of the upper limit of the Tg of the component (b1) include -5°C, -10°C, -15°C, -20°C, -25°C, -30°C, -35°C, -40°C, -45°C, -50°C, -55°C, -60°C, -65°C, etc.; examples of the lower limit include -10°C, -15°C, -20°C, -25°C, -30°C, -35°C, -40°C, -45°C, -50°C, -55°C, -60°C, -65°C, -70°C, etc. In one embodiment, the Tg of the component (b1) is less than -5°C, preferably -70°C or more and less than about -5°C. As the upper limit of the Tg of the component (b2), examples thereof include 250°C, 240°C, 230°C, 220°C, 210°C, 200°C, 190°C, 180°C, 170°C, 160°C, 150°C, 140°C, 130°C, 120°C, 110°C, 100°C, 90°C, 80°C, 70°C, 60°C, 50°C, 40°C, 30°C, 20°C, 10°C, 0°C, etc.; as the lower limit, examples thereof include 240°C, 230°C, 220°C, 210°C, 200°C, 190°C, 180°C, 170°C, 160°C, 150°C, 140°C, 130°C, 120°C, 110°C, 100°C, 90°C, 80°C, 70°C, 60°C, 50°C, 40°C, 30°C, 20°C, 10°C, 0°C, -5°C, etc. In one embodiment, the Tg of the component (b2) is -5°C or higher, preferably around -5°C or higher and 250°C or lower. In 100% by mass (in terms of solid content) of the total (meth)acrylate constituting the component (B), as the upper limit of the content (in terms of solid content) of the component (b1), examples thereof include 100% by mass, 99% by mass, 98% by mass, 97% by mass, 96% by mass, 95% by mass, 94% by mass, 93% by mass, 92% by mass, 91% by mass, 90% by mass, 89% by mass, 88% by mass, 87% by mass, 86% by mass, 85% by mass, 84% by mass, 83% by mass, 82% by mass, 81% by mass, 80% by mass, 79% by mass, 78% by mass, 77% by mass, 76% by mass, 75% by mass, 74% by mass, 73% by mass, 72% by mass, etc.; as the lower limit, examples thereof include 99% by mass, 98% by mass, 97% by mass, 96% by mass, 95% by mass, 94% by mass, 93% by mass, 92% by mass, 91% by mass, 90% by mass, 89% by mass, 88% by mass, 87% by mass, 86% by mass, 85% by mass, 84% by mass, 83% by mass, 82% by mass, 81% by mass, 80% by mass, 79% by mass, 78% by mass, 77% by mass, 76% by mass, 75% by mass, 74% by mass, 73% by mass, 72% by mass, 71% by mass, etc. In one embodiment, in 100% by mass (in terms of solid content) of the total (meth)acrylate constituting the component (B), the content (in terms of solid content) of the component (b1) is 71 to 100% by mass. In 100% by mass (in terms of solid content) of the total (meth)acrylate of component (B), the upper limit of the content (in terms of solid content) of component (b2) can be exemplified by 29% by mass, 28% by mass, 27% by mass, 26% by mass, 25% by mass, 24% by mass, 23% by mass, 22% by mass, 21% by mass, 20% by mass, 19% by mass, 18% by mass, 17% by mass, 16% by mass, 15% by mass, 14% by mass, 13% by mass, 12% by mass, 11% by mass, 10% by mass, 9% by mass, 8% by mass, 7% by mass, 6% by mass, 5% by mass, 4% by mass, 3% by mass, 2% by mass, 1% by mass, etc.; the lower limit can be exemplified by 28% by mass, 27% by mass, 26% by mass, 25% by mass, 24% by mass, 23% by mass, 22% by mass, 21% by mass, 20% by mass, 19% by mass, 18% by mass, 17% by mass, 16% by mass, 15% by mass, 14% by mass, 13% by mass, 12% by mass, 11% by mass, 10% by mass, 9% by mass, 8% by mass, 7% by mass, 6% by mass, 5% by mass, 4% by mass, 3% by mass, 2% by mass, 1% by mass, 0% by mass, etc. In one embodiment, in 100% by mass (in terms of solid content) of the total (meth)acrylate of component (B), the content (in terms of solid content) of component (b2) is 0 to 29% by mass. When the content (in terms of solid content) of component (b2) is greater than 29% by mass, the adhesive surface becomes easily peeled during repeated bending, so it is not ideal. The more the content (in terms of solid content) of component (b2), the better the adhesiveness becomes. As the upper limit of the content ratio (mass ratio, in terms of solid content, [(A) component / (B) component]) of component (A) and component (B), it can be exemplified by 70 / 30, 65 / 35, 60 / 40, 55 / 45, 50 / 50, 45 / 55, 40 / 60, 35 / 65, 30 / 70, 25 / 75, 20 / 80, 15 / 85, etc.; as the lower limit, it can be exemplified by 65 / 35, 60 / 40, 55 / 45, 50 / 50, 45 / 55, 40 / 60, 35 / 65, 30 / 70, 25 / 75, 20 / 80, 15 / 85, 10 / 90, etc. In one embodiment, from the viewpoints of haze value, storage elastic modulus, and strain, the content ratio (mass ratio, in terms of solid content, [(A) component / (B) component]) of component (A) and component (B) is preferably 40 / 60 to 65 / 35, more preferably 40 / 60 to 55 / 45, and even more preferably 40 / 60 to 50 / 50. In the total amount of 100% by mass (in terms of solid content) of component (A), component (B), and component (C), examples of the upper limit of the content of component (B) (in terms of solid content) include 55% by mass, 54% by mass, 53% by mass, 52% by mass, 51% by mass, 50% by mass, 49% by mass, 48% by mass, 47% by mass, 46% by mass, 45% by mass, 44% by mass, 43% by mass, 42% by mass, 41% by mass, 40% by mass, 39% by mass, 38% by mass, 37% by mass, 36% by mass, 35% by mass, 34% by mass, 33% by mass, 32% by mass, 31% by mass, etc.; examples of the lower limit include 54% by mass, 53% by mass, 52% by mass, 51% by mass, 50% by mass, 49% by mass, 48% by mass, 47% by mass, 46% by mass, 45% by mass, 44% by mass, 43% by mass, 42% by mass, 41% by mass, 40% by mass, 39% by mass, 38% by mass, 37% by mass, 36% by mass, 35% by mass, 34% by mass, 33% by mass, 32% by mass, 31% by mass, 30% by mass, etc. In one embodiment, in the total amount of 100% by mass (in terms of solid content) of component (A), component (B), and component (C), the content of component (B) (in terms of solid content) is about 30 to 55% by mass. When the content of component (B) is less than 30% by mass, the flexural resistance deteriorates, which is not desirable. When the content of component (B) is greater than 55% by mass, poor hardening and poor processability will occur, which is not desirable. <Component (C)> Component (C) is a mono(meth)acrylate containing a primary hydroxyl group. Due to the use of component (C), the adhesive composition has excellent curability, and the cured product has excellent durability after a damp heat test. When using a mono(meth)acrylate without a hydroxyl group as a substitute for component (C), the durability after a damp heat test and the haze value after a damp heat test deteriorate. Also, when using a mono(meth)acrylate containing a secondary hydroxyl group as a substitute for component (C), the haze value after a damp heat test deteriorates. In the present invention, the so-called "haze value after a damp heat test" has the same meaning as that described in JP-A-2020-037689. Examples of component (C) include 2-hydroxyethyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, cyclohexanedimethanol mono(meth)acrylate, etc. In terms of the adhesive composition having excellent curability and the cured product having excellent durability after a damp heat test, component (C) is preferably 2-hydroxyethyl (meth)acrylate and / or 4-hydroxybutyl (meth)acrylate. As the upper limit of the content ratio (mass ratio, in terms of solid components, [(A) component / (C) component]) of the (A) component and the (C) component, examples include 90 / 10, 85 / 15, 80 / 20, 75 / 25, 70 / 30, 65 / 35, 60 / 40, 55 / 45, 50 / 50, 45 / 55, etc.; as the lower limit, examples include 85 / 15, 80 / 20, 75 / 25, 70 / 30, 65 / 35, 60 / 40, 55 / 45, 50 / 50, 45 / 55, 40 / 60, etc. In one embodiment, the content ratio (mass ratio, in terms of solid components, [(A) component / (C) component]) of the (A) component and the (C) component is preferably around 40 / 60 to 90 / 10. As the upper limit of the content ratio (mass ratio, in terms of solid components, [(B) component / (C) component]) of the (B) component and the (C) component, examples include 95 / 5, 90 / 10, 85 / 15, 80 / 20, 75 / 25, 70 / 30, 65 / 35, 60 / 40, 55 / 45, etc.; as the lower limit, examples include 90 / 10, 85 / 15, 80 / 20, 75 / 25, 70 / 30, 65 / 35, 60 / 40, 55 / 45, 50 / 50, etc. In one embodiment, the content ratio (mass ratio, in terms of solid components, [(B) component / (C) component]) of the (B) component and the (C) component is preferably around 50 / 50 to 95 / 5. In 100% by mass (in terms of solid components) of the total amount of the (A) component, the (B) component, and the (C) component, as the upper limit of the content (in terms of solid components) of the (C) component, examples include 20% by mass, 19% by mass, 18% by mass, 17% by mass, 16% by mass, 15% by mass, 14% by mass, 13% by mass, 12% by mass, 11% by mass, 10% by mass, etc.; as the lower limit, examples include 19% by mass, 18% by mass, 17% by mass, 16% by mass, 15% by mass, 14% by mass, 13% by mass, 12% by mass, 11% by mass, 10% by mass, 9% by mass, etc. In one embodiment, in 100% by mass (in terms of solid components) of the total amount of the (A) component, the (B) component, and the (C) component, the content (in terms of solid components) of the (C) component is preferably 9% by mass or more and less than 20% by mass. When the content of the (C) component is less than 9% by mass, the adhesive strength decreases, so it is not preferable. When the content of the (C) component is 20% by mass or more, the compatibility with other components deteriorates and the b* value of the cured product becomes high, so it is not preferable. <(D) component> In the adhesive composition of the present invention, from the viewpoint of excellent curability of the cured product, it is preferably to contain a radical-based photoinitiator (hereinafter, also referred to as the "(D) component"). Examples of the component (D) include alkylbenzophenone-based photopolymerization initiators, acylphosphine oxide-based photopolymerization initiators, hydrogen abstraction-based photopolymerization initiators, oxime ester-based photopolymerization initiators, and the like. Examples of the alkylbenzophenone-based photopolymerization initiators include benzyldimethyl ketal (such as 2,2-dimethoxy-1,2-diphenylethan-1-one, etc.), α-hydroxyalkylbenzophenones (such as 1-[4-(2-hydroxyethoxy)phenyl]-2-hydroxy-2-methylpropan-1-one, 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, etc.), α-aminoalkylbenzophenones (such as 2-methyl-1-(4-methylthiophenyl)-2-morpholinopropan-1-one, etc.). Examples of the acylphosphine oxide-based photopolymerization initiators include 2,4,6-trimethylbenzoyl-diphenyl-oxide, bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, and the like. Examples of the hydrogen abstraction-based photopolymerization initiators include methyl phenylglyoxylate, etc. Examples of the oxime ester-based photopolymerization initiators include 1,2-octanedione 1-[4-(phenylthio)phenyl]-2-(o-benzoyl oxime), acetophenone 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazol-3-yl] 1-(o-acetyl oxime), and the like. In terms of the excellent curability of the adhesive composition, the component (D) is preferably an α-hydroxyalkylbenzophenone-based photopolymerization initiator and / or an acylphosphine oxide-based photopolymerization initiator. In 100% by mass (in terms of solid content) of the total amount of the components (A), (B), and (C), examples of the upper limit of the content (in terms of solid content) of the component (D) include 10% by mass, 9% by mass, 8% by mass, 7% by mass, 6% by mass, 5% by mass, 4% by mass, 3% by mass, 2% by mass, 1.5% by mass, 1% by mass, 0.5% by mass, 0.2% by mass, etc.; examples of the lower limit include 9% by mass, 8% by mass, 7% by mass, 6% by mass, 5% by mass, 4% by mass, 3% by mass, 2% by mass, 1.5% by mass, 1% by mass, 0.5% by mass, 0.2% by mass, 0.1% by mass, etc. In one embodiment, in 100% by mass (in terms of solid content) of the total amount of the components (A), (B), and (C), the content (in terms of solid content) of the component (D) is preferably 0.1% by mass or more and 3% by mass or less, more preferably 0.1% by mass or more and 2% by mass or less, and still more preferably 0.1% by mass or more and 1.5% by mass or less. <Other additives that can be combined> The adhesive composition of the present invention may also contain various additives as needed. Examples of the additives include surface modifiers, surfactants, ultraviolet absorbers, antioxidants, light stabilizers, inorganic fillers, silane coupling agents, colloidal silica, defoamers, wetting agents, rust inhibitors, plasticizers, chain transfer agents, photosensitizers, etc. In the adhesive composition of the present invention, a resin having a softening point of 90 °C or higher as the component (E) may also be contained. When the component (E) is contained in the adhesive composition of the present invention, the adhesiveness of the cured product becomes good. On the other hand, when the content is too large, it will have an adverse effect on the flexural resistance of the cured product. Therefore, when the total of the components (A), (B), and (C) is 100% by mass, the content (% by mass) of the component (E) in terms of solid content is preferably less than 10% by mass, more preferably less than 1% by mass, and still more preferably 0% by mass. Examples of the component (E) include hydroxyl-containing petroleum resins, disproportionated rosin resins, hydrogenated rosin resins, etc. In the present invention, the softening point is measured by the ring and ball method based on JIS K-2351. Examples of the upper limit of the softening point (°C) of the component (E) include 150, 140, 130, 120, 110, 100, etc.; examples of the lower limit include 140, 130, 120, 110, 100, 90, etc. In the adhesive composition of the present invention, a coupling agent as the component (F) may also be contained. Since the component (F) is contained in the adhesive composition of the present invention, the adhesion to the substrate becomes good. In particular, from the viewpoint of good adhesion when the substrate is glass, it is preferable that the coupling agent having a reactive group for chemically bonding to an inorganic material and a reactive group for chemically bonding to an organic material is used as the component (F). Examples of such a coupling agent include silane coupling agents, etc. When the total of the components (A), (B), and (C) is 100% by mass, examples of the upper limit of the content (% by mass) of the component (F) in terms of solid content include 10% by mass, 9% by mass, 8% by mass, 7% by mass, 6% by mass, 5% by mass, 4% by mass, 3% by mass, 2% by mass, 1% by mass, etc. Examples of the lower limit include 9% by mass, 8% by mass, 7% by mass, 6% by mass, 5% by mass, 4% by mass, 3% by mass, 2% by mass, 1% by mass, 0% by mass, etc. In one embodiment, when the total of the components (A), (B), and (C) is 100% by mass, the content (% by mass) of the component (F) in terms of solid content is preferably 0% by mass to 10% by mass, etc. In the adhesive composition of the present invention, a solvent may also be contained. Examples of the solvent include ketone solvents, aromatic solvents, alcohol solvents, glycol solvents, glycol ether solvents, ester solvents, petroleum-based solvents, halogenated alkane solvents, amide solvents, etc. Examples of the ketone solvent include methyl ethyl ketone, acetylacetone, methyl isobutyl ketone, cyclopentanone, cyclohexanone, and the like. Examples of the aromatic solvent include toluene, xylene, and the like. Examples of the alcohol solvent include methanol, ethanol, n-propanol, isopropanol, butanol, and the like. Examples of the diol solvent include ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, triethylene glycol, tripropylene glycol, polyethylene glycol, polypropylene glycol, and the like. Examples of the diol ether solvent include ethylene glycol dimethyl ether, ethylene glycol diethyl ether, propylene glycol dimethyl ether, propylene glycol diethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, diethylene glycol methyl ethyl ether, diethylene glycol diethyl ether, propylene glycol monomethyl ether, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monon-propyl ether, ethylene glycol monoisopropyl ether, ethylene glycol monon-butyl ether, ethylene glycol monoisobutyl ether, ethylene glycol monoter-butyl ether, and the like. Examples of the ester solvent include ethyl acetate, butyl acetate, methyl cellulose acetate, ethyl cellulose acetate, propylene glycol monomethyl ether acetate, and the like. Examples of the petroleum-based solvent include T-SOL 100 (manufactured by ENEOS Corporation), T-SOL 150 (manufactured by ENEOS Corporation), and the like. Examples of the haloalkane solvent include chloroform, and the like. Examples of the amide solvent include dimethylformamide, and the like. The adhesive composition of the present invention can be used without containing a solvent. Therefore, from the viewpoint of being able to suppress costs and environmental impacts, it is desirable that the adhesive composition of the present invention does not contain a solvent. Examples of the upper limit of the viscosity (mPa·s / 25°C) of the adhesive composition of the present invention include 10000, 9000, 8000, 7000, 6000, 5000, 4000, 3000, 2000, 1000, 500, 300, and the like; examples of the lower limit include 9000, 8000, 7000, 6000, 5000, 4000, 3000, 2000, 1000, 500, 300, 100, and the like. From the viewpoint of the adhesive composition having excellent processability, the viscosity (mPa·s / 25°C) of the adhesive composition of the present invention is preferably 100 or more and 10000 or less, more preferably 300 or more and 8000 or less, and even more preferably 500 or more and 7000 or less. The viscosity in the present invention is a measured value (5 minutes) by an E-type viscometer (product name "TVE-10", manufactured by Toki Sangyo Co., Ltd.). The adhesive composition of the present invention is obtained by mixing component (A), component (B), and component (C), as well as component (D), component (E), component (F), and other optional additives as needed. The order of mixing is not particularly limited, and they can be mixed sequentially or all at once. <Hardened product> A product obtained by irradiating the adhesive composition with active energy rays such as ultraviolet rays to harden it is also one of the present inventions. When the adhesive composition contains a solvent, a drying treatment can be considered before ultraviolet irradiation. It is also possible to obtain a hardened product by applying the adhesive composition onto various substrates to form an adhesive composition layer and then irradiating this layer with ultraviolet rays. Examples of the ultraviolet light source include ultraviolet irradiation devices having xenon lamps, high-pressure mercury lamps, and metal halide lamps. In such a device, conditions such as the irradiation intensity and cumulative light quantity of ultraviolet rays, and the conveying speed are generally an irradiation intensity of 80 mW / cm² or more and 160 mW / cm² or less, a conveying speed of 3 m / min or more and 50 m / min or less, and a cumulative light quantity of 100 mJ / cm² or more and 3000 mJ / cm² or less. Examples of the coating method of the adhesive composition include coating with a doctor blade coater, coating with a mayer bar, air knife coating, gravure coating, reverse gravure coating, offset printing, flexographic printing, screen printing, etc. The coating amount is generally a mass after drying of 1 g / m² or more and 1000 g / m² or less, preferably in the range of 3 g / m² or more and 500 g / m² or less. The thickness of the hardened product of the present invention is not particularly limited. From the perspective that the hardened product suitably exhibits high difference followability and is difficult to generate bubbles, it is preferably a dry coating film of 10 μm or more and 1000 μm or less, and more preferably 25 μm or more and 500 μm or less. As the upper limit of the storage elastic modulus at 23°C and 1 Hz of the cured product of the present invention, examples include 150 kPa, 140 kPa, 130 kPa, 120 kPa, 110 kPa, 100 kPa, 95 kPa, 90 kPa, 85 kPa, 80 kPa, 75 kPa, 70 kPa, 65 kPa, 60 kPa, 55 kPa, 50 kPa, 40 kPa, 30 kPa, 20 kPa, etc.; as the lower limit, examples include 140 kPa, 130 kPa, 120 kPa, 110 kPa, 100 kPa, 95 kPa, 90 kPa, 85 kPa, 80 kPa, 75 kPa, 70 kPa, 65 kPa, 60 kPa, 55 kPa, 50 kPa, 40 kPa, 30 kPa, 20 kPa, 10 kPa, etc. As an embodiment, the lower the storage elastic modulus at 23°C and 1 Hz of the cured product of the present invention, the better the durability (also referred to as "flexural fatigue resistance" in the present invention) when repeatedly bending the cured product in a room temperature environment (23°C). Therefore, it is preferably less than 150 kPa, and more preferably less than 80 kPa. In addition, as the upper limit of the storage elastic modulus at -15°C and 1 Hz of the cured product of the present invention, examples include 400 kPa, 350 kPa, 300 kPa, 250 kPa, 200 kPa, 190 kPa, 180 kPa, 170 kPa, 160 kPa, 150 kPa, 140 kPa, 130 kPa, 120 kPa, 110 kPa, etc.; as the lower limit, examples include 350 kPa, 300 kPa, 250 kPa, 200 kPa, 190 kPa, 180 kPa, 170 kPa, 160 kPa, 150 kPa, 140 kPa, 130 kPa, 120 kPa, 110 kPa, 100 kPa, etc. As an embodiment, the lower the storage elastic modulus at -15°C and 1 Hz of the cured product of the present invention, the better the durability (also referred to as "flexural fatigue resistance" in the present invention) when repeatedly bending the cured product in a low temperature environment (-15°C). Therefore, it is preferably less than 400 kPa, and more preferably less than 250 kPa. As the upper limit of the value of the strain test at 23°C of the cured product of the present invention, 1000, 900, 800, 700, 600, 500, 400, 300, 200, etc. can be cited; as the lower limit, 900, 800, 700, 600, 500, 400, 300, 200, 100, etc. can be cited. In one embodiment, the value of the strain test at 23°C of the cured product of the present invention is desirably 100 or more and 1000 or less, more desirably 200 or more and 900 or less, and still more desirably 300 or more and 800 or less. As the upper limit of the value of the strain test at -15°C of the cured product of the present invention, 1000, 900, 800, 700, 600, 500, 400, 300, 200, 100, etc. can be cited; as the lower limit, 900, 800, 700, 600, 500, 400, 300, 200, 100, 50, etc. can be cited. In one embodiment, the value of the strain test at -15°C of the cured product of the present invention is desirably 50 or more and 1000 or less, more desirably 100 or more and 700 or less, and still more desirably 100 or more and 500 or less. Since the value is above the lower limit value, it is possible to withstand the strain generated when the cured product is repeatedly bent. Since the value is below the upper limit value, it is possible to reduce the adhesion of the cured product to the blade when cutting the cured product, and the workability also becomes good. <Formed article> As an application example of the adhesive composition, coating between the base materials of various known articles can be cited. As the article, the main body of home appliances such as televisions and their remote controllers, and the outer casings and displays of information terminals such as mobile phones, smartphones, tablet computers, and personal computers can be cited. The active energy ray curable adhesive composition of the present invention is suitable for optical applications, and is desirably used as an optical transparent adhesive (OCA). For example, it can be applied to a display panel having a multilayer structure in a digital display device. In addition, since the cured product of the present invention has excellent flexural resistance, it is particularly considered for use in foldable devices. <Applicable Substrates> As substrates on which the adhesive composition of the present invention is coated, glass substrates, plastic substrates, paper substrates, cloth substrates, rubber sheet substrates, foam sheet substrates, metal substrates, etc. can be cited. As plastic substrates, thermoplastic plastic substrates, thermosetting plastic substrates, etc. can be cited. As thermoplastic plastic substrates, general-purpose plastic substrates, engineering plastic substrates, etc. can be cited. As general-purpose plastic substrates, olefin-based, polyester-based, acrylic-based, vinyl-based, polystyrene-based, etc. can be cited. As olefin-based, polyethylene, polypropylene, norbornene, etc. can be cited. As polyester-based, polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polybutylene succinate (PBS), polybutylene adipate succinate (PBSA), polybutylene terephthalate adipate (PBAT), polylactic acid (PLA), polyhydroxyalkanoate (PHA), polycaprolactone (PCL), etc. can be cited. As acrylic-based, polymethyl methacrylate (PMMA), etc. can be cited. As vinyl-based, polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, etc. can be cited. As polystyrene-based, polystyrene (PS) resin, styrene-acrylonitrile (AS) resin, styrene-butadiene-acrylonitrile (ABS) resin, etc. can be cited. As engineering plastic substrates, general engineering plastics, super engineering plastics, etc. can be cited. As general engineering plastics, polycarbonate, polyamide (nylon), etc. can be cited. As super engineering plastics, polyetheretherketone (PEEK), etc. can be cited. As thermosetting plastic substrates, polyimide, epoxy resin, melamine resin, etc. can be cited. As other plastic substrates, triacetyl cellulose resin, etc. can be cited. As paper substrates, Japanese paper, kraft paper, cellophane, high-grade paper, synthetic paper, surface-coated paper, etc. can be cited. As cloth substrates, woven fabrics and non-woven fabrics obtained by various fibrous substances alone or in combination, etc. can be cited. As rubber sheet substrates, natural rubber, butyl rubber, etc. can be cited. As foam sheet substrates, foamed polyurethane, foamed polychloroprene rubber, etc. can be cited. As metal substrates, aluminum foil, copper foil, etc. can be cited. In addition, the substrate can also be surface-treated (such as corona discharge, etc.). In addition, other layers (such as an easy-adhesion layer, an anchoring layer, etc.) can be provided between the adhesive composition layers on one or both sides of the substrate. The substrate is preferably a substrate for optical use.Examples of the optical substrate include polyester films such as polyethylene terephthalate (PET), polybutylene terephthalate, and polyethylene naphthalate (PEN), polyethylene films, polypropylene films, cellophane, diacetyl cellulose films, triacetyl cellulose films, cellulose acetate butyrate films, polyvinyl chloride films, polyvinylidene chloride films, polyvinyl alcohol films, ethylene-vinyl acetate copolymer films, polystyrene films, polycarbonate films, polymethylpentene films, polysulfone films, polyetheretherketone films, polyethersulfone films, polyetherimide films, polyimide films, fluororesin films, polyamide films, acrylic resin films, norbornene-based resin films, and cycloolefin resin films, glass, indium tin oxide film, ITO film, transparent conductive film, etc. Further, the thickness of the substrate is not particularly limited and is usually about 30 to 300 μm. Specifically, examples of the combination of the cured product of the present invention and the optical substrate include the following: (1) Substrate, cured product of the present invention, transparent conductive film (also referred to as "ITO" in the present invention); (2) Substrate, cured product of the present invention, liquid crystal display. [Examples] Manufacturing examples, comparative manufacturing examples, examples, comparative examples, evaluation examples, and comparative evaluation examples are given below to illustrate the present invention more specifically, but the present invention is not limited to these examples. In addition, in the following description, parts and % are based on mass. The weight average molecular weight (Mw) in this example was measured by gel permeation chromatography (GPC) under the following conditions. (GPC measurement conditions) Model: Product name "HLC-8220GPC" (manufactured by Tosoh Corporation) Columns: Product names "TSKgel G1000H" and "TSKgel G2000H" (manufactured by Tosoh Corporation) Developing solvent: Tetrahydrofuran Flow rate: 0.6 mL / min Measurement temperature: 40°C Detector: Differential refractive index detector (RI: Refractive Index Detector) Standard: Monodisperse polystyrene Sample: A 20 μL solution obtained by preparing a 0.2% concentration solution of the resin in tetrahydrofuran in terms of solid content and filtering the solution through a microfilter. In each production example, the method for measuring the NCO of the urethane prepolymer is as follows. Measuring device main body: Automatic potentiometric titrator (product name "AT-400", manufactured by Kyoto Electronics Industry Co., Ltd.) Measuring procedure: 1: Weigh a sample of about 0.500 g or more and 1.000 g or less in a weighing bottle. 2: Inject 10 mL of a toluene solution of 0.15 mol / L dibutylamine. 3: Place the weighing bottle containing the sample in an ultrasonic cleaner to completely dissolve the sample. 4: Confirm that the sample is completely dissolved and leave it for 15 minutes (away from direct sunlight or high temperature). 5: After 15 minutes, add 100 mL of isopropyl alcohol to the weighing bottle. Place a stirring piece in the weighing bottle. 6: Titrate with a 0.1 mol / L hydrochloric acid solution (f = 1.00) to obtain the NCO value. Input the sample amount to be measured into the automatic titrator and then perform the measurement. If the measurement error is within 0.30, it is judged as acceptable. If it is 0.30 or more, measure again and confirm that it is within 0.30. <Production Example 1: Preparation of Component (A-1)> In a reaction apparatus equipped with a condenser, a stirrer, and a nitrogen inlet tube, 884 parts of polypropylene glycol with a number average molecular weight of 2000 (product name "ADEKA POLYETHER P-2000" (also referred to as "PPG2000" in the present invention), manufactured by ADEKA Corporation), 106 parts of isophorone diisocyanate (also referred to as "IPDI" in the present invention), 333 parts of 2-ethylhexyl acrylate (also referred to as "2EHA" in the present invention), and 0.4 part of stannous octoate were added. After heating to 80 °C and maintaining the temperature for 3 hours, a 2EHA solution of an isocyanate group-terminated urethane prepolymer as an intermediate was obtained. Then, 10 parts of 4-hydroxybutyl acrylate (also referred to as "4HBA" in the present invention) were added, and the temperature was maintained at 80 °C for 2 hours. After confirming the completion of the reaction by NCO measurement, a 2EHA solution of a polyurethane acrylate (A-1) (also referred to as "Component (A-1)" in the present invention) with a weight average molecular weight of 55000, an average number of acryloyl groups of 2, and an acrylic acid equivalent of 27500 was obtained. <Example 1: Preparation of Adhesive Composition (1)> 37 parts of Component (A-1), 53 parts of 2-EHA as Component (B), 10 parts of 4HBA as Component (C), and 1 part of 1-hydroxycyclohexyl phenyl ketone (product name "Omnirad 184" (also referred to as "Omni 184" in the present invention), manufactured by IGM Resins) as Component (D) were mixed to obtain Adhesive Composition (1). <Examples 2 to 6 and Comparative Examples 1 to 6: Adhesive Compositions (2) to (6) and Adhesive Compositions (C1) to (C6)> Except that the components were changed as described in Table 1, the same procedure as in Example 1 was carried out. <Performance Evaluation (1): Adhesion> The adhesive compositions (1) to (6) and (C1) to (C6) were respectively coated on a 75-μm thick heavily peeled polyester film (product name "SP-PET-03-75BU", manufactured by Mitsui Chemicals Tohcello, Inc.) so that the film thickness of the cured adhesive layer was 50 μm. The peeled surface of a 38-μm thick lightly peeled polyester film (product name "SP-PET-01-38BU", manufactured by Mitsui Chemicals Tohcello, Inc.) was laminated on the coated layer of the adhesive composition. Then, the obtained coated film was irradiated with ultraviolet rays by a high-pressure mercury lamp (100 mW / cm², 2,000 mJ / cm²) in the air to produce a laminated film containing an adhesive layer (lightly peeled polyester film / adhesive layer / heavily peeled polyester film). Next, the lightly peeled polyester film was peeled off, and instead, a 50-μm thick polyester film (product name "COSMOSHINE A-4300", manufactured by Toyobo Co., Ltd.) was laminated using a 2-kg roller and left standing for 2 hours. Then, a test piece of 2.5 cm × 10 cm was cut from this material, and a single-sided adhesive sheet (COSMOSHINE A-4300 / adhesive layer) was produced by peeling off the heavily peeled polyester film. By overlapping the single-sided adhesive sheet (adhesive layer / COSMOSHINE A-4300) (2.5 cm × 10 cm × 150 μm) on a glass plate (2.5 cm × 12 cm × 2 mm) and pressing it tightly using a 2-kg roller, a laminate (COSMOSHINE A-4300 (50-μm thick) / adhesive layer (50-μm thick) / glass plate (2-mm thick)) (laminates (1) to (6) and (C1) to (C6)) was produced. The laminates (1) to (6) and (C1) to (C6) were left standing for 24 hours under the conditions of 25°C and 50% humidity. The adhesion (N / 25 mm) was measured by peeling the single-sided adhesive sheet (adhesive layer / COSMOSHINE A-4300) from the glass plate at a speed of 300 mm / min in the 180° direction and evaluated according to the following criteria. The measurement was performed using a commercially available machine (product name "TENSILON universal material testing machine", manufactured by AND Corporation). 〇: Greater than 5 N ×: 5 N or less <Performance Evaluation (2): Total Light Transmittance> The total light transmittance of the laminates (1) to (6) and (C1) to (C6) was measured using a commercially available measuring machine (product name "Haze and Transmittance Meter HM-150", manufactured by Murakami Color Research Laboratory Co., Ltd.) based on the single-beam method described in JIS K 7361-1:1997 and evaluated according to the following criteria. 〇: Greater than 90% ×: 90% or less <Performance Evaluation (3): Haze Value> Using a commercially available measuring instrument (product name "Haze / Transmittance Meter HM-150", manufactured by Murakami Color Research Laboratory Co., Ltd.), the haze values of the laminates (1) to (6) and (C1) to (C6) were measured according to JIS K 7136:2000, and evaluated according to the following criteria. 〇: Less than 0.15% △: 0.15% or more and less than 0.3% ×: 0.3% or more <Performance Evaluation (4): Chromaticity b* Value> Regarding the laminates (1) to (6) and (C1) to (C6), b* in the CIE1976L*a*b* color system was measured according to JIS Z8781-4:2013, and evaluated according to the following criteria. 〇: Less than 0.4% ×: 0.4% or more <Performance Evaluation (5): Glass Transition Temperature> Using a measuring instrument (product name "MCR302", manufactured by Anton Paar), the adhesive compositions (1) to (6) and (C1) to (C6) were measured. The loss tangent was expressed as the loss elastic modulus (G'') / storage elastic modulus (G'), and the temperature at the peak of the loss tangent was taken as the glass transition temperature. The glass transition temperature was evaluated according to the following criteria. 〇: Less than -40°C △: -40°C or more and less than -30°C ×: -30°C or more <Performance Evaluation (6): Storage Modulus> The adhesive compositions (1) to (6) and (C1) to (C6) were each coated on a 75-μm-thick heavily release-treated polyester film (product name "SP-PET-03-75BU", manufactured by Mitsui Chemicals Toagosei Co., Ltd.) so that the film thickness of the cured product after curing was 50 μm. The release-treated surface of a 38-μm-thick lightly release-treated polyester film (product name "SP-PET-01-38BU", manufactured by Mitsui Chemicals Toagosei Co., Ltd.) was laminated on the adhesive composition coating layer. Then, the obtained coating film was irradiated with ultraviolet rays using a high-pressure mercury lamp (100 mW / cm², 2,000 mJ / cm²) in the atmosphere to produce a laminate (lightly release-treated polyester film / cured product / heavily release-treated polyester film) containing the cured product. Next, a 1 cm × 1 cm test piece was cut from the laminate. Then, the lightly release-treated polyester film and the heavily release-treated polyester film were peeled off from the test piece to obtain the cured products (1) to (6) and (C1) to (C6). The 50-μm-thick cured products were laminated 20 times to obtain a 1-mm-thick sample. The sample was punched to a diameter of 8 mm to obtain the measurement samples (1) to (6) and (C1) to (C6). The measurement samples (1) to (6) and (C1) to (C6) were measured for their dynamic viscoelasticity using a commercially available measuring machine (product name "MCR302", manufactured by Anton Paar) under the following conditions. Then, based on the measurement results, the storage modulus at -15°C and 1 Hz and the storage modulus at 23°C and 1 Hz were determined and evaluated according to the following criteria. (Measurement Conditions) Deformation mode: Torsion Measurement frequency: 1 Hz Strain: 0.01 to 1% Automatic setting of heating rate: 3°C / min Measurement temperature: -80 to 100°C Shape: Parallel plate 8.0 mmφ (Storage modulus at -15°C and 1 Hz) 〇: Less than 250 kPa △: 250 kPa or more and less than 400 kPa ×: 400 kPa or more (Storage modulus at 23°C and 1 Hz) 〇: Less than 80 kPa △: 80 kPa or more and less than 150 kPa ×: 150 kPa or more <Performance Evaluation (7): Strain Test> The cured products (1) to (6) and (C1) to (C6) were measured using a measuring instrument (product name "MCR302", manufactured by Anton Paar). <Creep Test> A shear stress of 40 kPa was applied to the cured product at -15°C or 23°C for 10 minutes. The strain amount of the cured product after 10 minutes was evaluated according to the following criteria. (Strain at -15°C) 〇: 100 or more and 500 or less △: 50 or more and less than 100, or more than 500 and 1000 or less ×: Less than 50, or more than 1000 (Strain at 23°C) 〇: 300 or more and 800 or less △: 100 or more and less than 300, or more than 800 and 1000 or less ×: Less than 100, or more than 1000 [Table 1] The meanings of the terms in Table 1 are as described below. Values related to the content of each component in the table are in terms of solid components. UA: Polyurethane acrylate obtained in Production Example 1 2EHA: 2-Ethylhexyl acrylate (product name "2-Ethylhexyl acrylate", manufactured by Mitsubishi Chemical Corporation) NOAA: n-Octyl acrylate (product name "NOAA", manufactured by Osaka Organic Chemical Industry Co., Ltd.) FA-513AS: Dicyclopentanyl acrylate (product name "FA-513AS", manufactured by Showa Denko Materials Co., Ltd.) 4HBA: 4-Hydroxybutyl acrylate (product name "4-HBA", manufactured by Osaka Organic Chemical Industry Co., Ltd.) Omni 184: 1-Hydroxycyclohexyl phenyl ketone (product name "Omnirad 184", manufactured by IGM Resins) KE-100: Ultra-light-colored rosin ester (product name "PINECRYSTAL KE-100", manufactured by Arakawa Chemical Industries, Ltd.) Coupling agent: 3-Methacryloxypropylmethyldimethoxysilane (product name "KBM-502", manufactured by Shin-Etsu Chemical Co., Ltd.)

Claims

1. A composition of an active energy radiation-curable adhesive, comprising: (A): a reactant containing (a1) a polyol, (a2) an aliphatic polyisocyanate, and (a3-1) a mono(meth)acrylate containing a hydroxyl group or (a3-2) a mono(meth)acrylate containing an isocyanate group, wherein the weight average molecular weight is 50,000 or more and 110,000 or less; (B): a (meth)acrylate having one vinyl unsaturated double bond and lacking a hydroxyl group; and (C): a mono(meth)acrylate containing a primary hydroxyl group; wherein, (B) Component contains (meth)acrylate (b1) and / or (meth)acrylate (b2), wherein (meth)acrylate (b1) has a glass transition temperature of less than -5°C when it is a homopolymer, and (meth)acrylate (b2) has a glass transition temperature of more than -5°C when it is a homopolymer; When the total of components (A), (B), and (C) is 100% by mass, the solid content of component (A) is greater than 35% by mass and less than 50% by mass, the solid content of component (B) is greater than 40% by mass and less than 55% by mass, and the solid content of component (C) is greater than 9% by mass and less than 20% by mass; When the total of (meth)acrylate constituting component (B) is 100% by mass, the solid content of component (b1) is greater than 71% by mass and less than 100% by mass. (b2) The content of the solid component of the ingredient is more than 0% by mass and less than 29% by mass.

2. The active energy ray-curing adhesive composition as described in claim 1, wherein, Compared to 100% by mass of components (A), (B) and (C), this active energy ray curing adhesive composition does not contain more than 1% by mass of resin with a softening point of 90°C or higher.

3. A hardener, which is a hardener of an active energy ray-curable adhesive composition as described in claim 1 or 2.

4. An adhesive sheet having a hardened material as described in claim 3 on at least one side of a substrate surface.