Adhesive composition, adhesive sheet, and flexible electronic device

Abstract

To provide an adhesive composition that can form an adhesive layer having superior deformability and superior recoverability.SOLUTION: An adhesive composition contains (A) an isobutene polymer having an epoxy group, (B) an isobutene polymer having an acid anhydride group and / or a carboxy group, with a number average molecular weight of 10,000 or more, and (C) an olefinic polymer having an acid anhydride group and / or a carboxy group, with a number average molecular weight of less than 10,000.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to an adhesive composition, an adhesive sheet, and a flexible electronic device. [Background technology]

[0002] Glass substrates have traditionally been used primarily for electronic devices such as flat panel displays (liquid crystal displays, organic electroluminescence (EL) displays, electronic paper, etc.) and solar cells. However, glass substrates are heavy and fragile, and their strength decreases when they are made lighter and thinner. For this reason, in recent years, there has been active development of flexible electronic devices (hereinafter sometimes simply referred to as "flexible devices") in which glass substrates are replaced with flexible, bendable substrates. In addition, adhesive sheets having adhesive layers are sometimes used for interlayer adhesion in flexible devices, and in such cases, the flexible device has an adhesive layer.

[0003] Components of flexible devices may be damaged or peeled off due to stress applied when they are bent. To prevent such damage or peeling, the adhesive layer in the flexible device is required to have excellent ability to deform under stress (sometimes referred to as "deformability" in this specification).

[0004] Furthermore, flexible device components are also required to return to their original shape after stress is removed, and therefore the adhesive layer in the flexible device is required to have excellent performance (sometimes referred to as "recovery" in this specification) of returning to its original shape after stress is removed.

[0005] For example, Patent Document 1 discloses an assembly layer for a flexible device to prevent failure and delamination, which includes an adhesive composition and is characterized by having a specific shear storage modulus, a specific shear creep compliance, and a specific strain recovery. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Special Publication No. 2018-526469 Summary of the Invention [Problem to be solved by the invention]

[0007] An object of the present invention is to provide an adhesive composition capable of forming an adhesive layer having excellent deformability and recoverability. [Means for solving the problem]

[0008] The present invention that can achieve the above object is as follows. [1] The following components (A) to (C): (A) an isobutene-based polymer having an epoxy group, (B) an isobutene-based polymer having an acid anhydride group and / or a carboxyl group and a number average molecular weight of 10,000 or more; and (C) an olefin polymer having an acid anhydride group and / or a carboxyl group and a number average molecular weight of less than 10,000 An adhesive composition comprising: [2] The pressure-sensitive adhesive composition according to the above [1], wherein the component (B) is an isobutene-based polymer having an acid anhydride group and a number-average molecular weight of 10,000 or more. [3] The pressure-sensitive adhesive composition according to [1] or [2], wherein the component (C) is an olefin polymer having an acid anhydride group and a number-average molecular weight of less than 10,000. [4] The adhesive composition according to any one of [1] to [3] above, wherein the number average molecular weight of component (B) is 20,000 to 500,000. [5] The adhesive composition according to any one of [1] to [4], wherein the number average molecular weight of component (C) is 300 or more and less than 10,000. [6] The pressure-sensitive adhesive composition according to any one of the above [1] to [5], further comprising a liquid olefin polymer other than the components (A), (B) and (C). [7] The adhesive composition according to any one of [1] to [6], further comprising a plasticizer. [8] A pressure-sensitive adhesive sheet having a laminated structure comprising a support and a pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition according to any one of the above [1] to [7]. [9] A flexible electronic device comprising an adhesive layer formed from the adhesive composition according to any one of [1] to [7] above. [Effects of the Invention]

[0009] According to the present invention, it is possible to obtain an adhesive composition that can form an adhesive layer that is excellent in deformability and recovery property. DETAILED DESCRIPTION OF THE INVENTION

[0010] adhesive composition The adhesive composition of the present invention is characterized by comprising the following components (A) to (C): (A) an isobutene-based polymer having an epoxy group, (B) an isobutene-based polymer having an acid anhydride group and / or a carboxyl group and a number average molecular weight of 10,000 or more; and (C) An olefin polymer having an acid anhydride group and / or a carboxy group and a number average molecular weight of less than 10,000.

[0011] Components (A) to (C) may each be used alone or in combination of two or more. Components (A) to (C) will be explained in order below.

[0012] <Component (A)> The component (A) used in the present invention is an isobutene-based polymer having an epoxy group. In this specification, the term "isobutene-based polymer" refers to a polymer in which structural units derived from isobutene (hereinafter sometimes abbreviated as "isobutene units") are the main structural units (i.e., the amount of isobutene units is the largest among all structural units). In the following, "structural units derived from olefins" and the like may be abbreviated as "olefin units" and the like, in the same manner as structural units derived from isobutene.

[0013] The isobutene polymer may be a homopolymer of isobutene or a copolymer of isobutene and a monomer other than isobutene. The copolymer may be a random copolymer or a block copolymer.

[0014] The isobutene-based polymer may be an isobutene-based resin (e.g., polyisobutene) or an isobutene-based rubber (e.g., butyl rubber, i.e., an isobutene-isoprene copolymer). In this specification, "isobutene-based resin" means an isobutene-based polymer that cannot form a rubbery elastomer by crosslinking, and "isobutene-based rubber" means an isobutene-based polymer that can form a rubbery elastomer by crosslinking.

[0015] The epoxy group concentration in component (A) is preferably 0.1 to 5 mmol / g, more preferably 0.3 to 3 mmol / g, from the viewpoint of the deformability and recovery of the adhesive layer. The epoxy group concentration is determined from the epoxy equivalent obtained in accordance with JIS K 7236-1995.

[0016] From the viewpoint of the deformability and recovery of the adhesive layer, the number average molecular weight of component (A) is preferably 10,000 to 500,000, more preferably 30,000 to 400,000, and even more preferably 50,000 to 300,000. The number average molecular weight of each component is measured by gel permeation chromatography (GPC) (polystyrene equivalent). Specifically, the number average molecular weight measured by GPC is measured using a Shimadzu Corporation "LC-9A / RID-6A" measuring device, a Showa Denko Corporation "Shodex K-800P / K-804L / K-804L" column, toluene, or the like, as the mobile phase, at a column temperature of 40°C, and can be calculated using a calibration curve of standard polystyrene.

[0017] Component (A) can be obtained, for example, by graft-modifying an isobutene-based polymer with an unsaturated compound having an epoxy group (e.g., glycidyl (meth)acrylate, 4-hydroxybutyl acrylate glycidyl ether, allyl glycidyl ether) under radical reaction conditions.

[0018] As component (A), for example, a polymer available from Seiko PMC Co., Ltd. Examples of such polymers available from Seiko PMC Co., Ltd. include "ER850" (glycidyl methacrylate-modified butyl rubber), "ER866" (glycidyl methacrylate-modified butyl rubber), and "ER869" (glycidyl methacrylate-2-ethylhexyl acrylate random copolymer-modified butyl rubber).

[0019] Component (A) is preferably an isobutene-isoprene copolymer having epoxy groups (ie, butyl rubber). When an isobutene-isoprene copolymer having an epoxy group (i.e., butyl rubber) is used as component (A), the amount of isoprene units in the copolymer is preferably 0.1 to 10 mass%, more preferably 0.3 to 5 mass%, and even more preferably 0.5 to 3 mass% based on the total of isobutene units and isoprene units, from the viewpoint of yellowing resistance of the adhesive layer. The amount of isoprene units is based on the isobutene units and isoprene units excluding modified portions (for example, portions derived from glycidyl (meth)acrylate for introducing epoxy groups).

[0020] The total content of the (A) component and the (B) component described below is preferably 10% by mass or more, more preferably 20% by mass or more, and even more preferably 30% by mass or more, relative to 100% by mass of the non-volatile content of the adhesive composition, from the viewpoint of the recoverability of the adhesive layer, and is preferably 90% by mass or less, more preferably 80% by mass or less, and even more preferably 70% by mass or less, from the viewpoint of the deformability of the adhesive layer.

[0021] The mass ratio of component (A) to component (B) (component (A):component (B)) is preferably 5:95 to 95:5, more preferably 10:90 to 90:10, and even more preferably 80:20 to 20:80, in order to form an appropriate crosslinked structure.

[0022] <(B) component> The component (B) used in the present invention is an isobutene polymer having an acid anhydride group (i.e., a carbonyloxycarbonyl group (—CO—O—CO—)) and / or a carboxy group and a number-average molecular weight of 10,000 or more, preferably an isobutene polymer having an acid anhydride group and a number-average molecular weight of 10,000 or more. The explanation of the “isobutene polymer” in the component (B) is the same as that in the component (A).

[0023] When an isobutene-based polymer having an acid anhydride group and a number average molecular weight of 10,000 or more is used as component (B), the concentration of the acid anhydride group in the polymer is preferably 0.1 to 5 mmol / g, more preferably 0.2 to 3 mmol / g, from the viewpoint of the deformability and recovery of the adhesive layer. The concentration of the acid anhydride group is obtained from the acid value, which is defined as the number of milligrams of potassium hydroxide required to neutralize the acid present in 1 g of polymer, as described in JIS K 2501.

[0024] When an isobutene-based polymer having carboxy groups and a number average molecular weight of 10,000 or more is used as component (B), the concentration of carboxy groups in the polymer is preferably 0.1 to 5 mmol / g, more preferably 0.2 to 3 mmol / g, from the viewpoint of the deformability and recovery of the adhesive layer. The concentration of carboxy groups is obtained from the acid value, which is defined as the number of milligrams of potassium hydroxide required to neutralize the acid present in 1 g of polymer, as described in JIS K 2501.

[0025] When an isobutene-based polymer having an acid anhydride group and a carboxy group and a number average molecular weight of 10,000 or more is used as component (B), the sum of the concentration of the acid anhydride group and the concentration of the carboxy group in the polymer is preferably 0.1 to 5 mmol / g, more preferably 0.2 to 3 mmol / g, from the viewpoint of the deformability and recoverability of the adhesive layer.

[0026] The number average molecular weight of component (B) is preferably 20,000 to 500,000, more preferably 25,000 to 400,000, and even more preferably 30,000 to 300,000, from the viewpoint of the deformability and recovery properties of the adhesive layer.

[0027] The component (B) can be produced, for example, by graft-modifying an isobutene polymer with an unsaturated compound having an acid anhydride group and / or a carboxy group (for example, maleic anhydride) under radical reaction conditions.

[0028] As component (B), for example, a polymer available from Seiko PMC Co., Ltd. Examples of such polymers available from Seiko PMC Co., Ltd. include "ER641" (maleic anhydride-modified butyl rubber), "ER661" (maleic anhydride-butyl methacrylate random copolymer-modified butyl rubber), "ER669" (maleic anhydride-2-ethylhexyl acrylate random copolymer-modified butyl rubber), and "ER674" (maleic anhydride-lauryl methacrylate random copolymer-modified butyl rubber).

[0029] In one embodiment of the present invention, component (B) is preferably an isobutene-isoprene copolymer (i.e., butyl rubber) having an acid anhydride group and / or a carboxy group and a number average molecular weight of 10,000 or more, and more preferably an isobutene-isoprene copolymer having an acid anhydride group and a number average molecular weight of 10,000 or more.

[0030] When an isobutene-isoprene copolymer (i.e., butyl rubber) having an acid anhydride group and / or a carboxyl group (preferably an acid anhydride group) and a number average molecular weight of 10,000 or more is used as component (B), the amount of isoprene units in the copolymer is preferably 0.1 to 5 mass%, more preferably 0.2 to 3 mass%, based on the total of isobutene units and isoprene units, from the viewpoint of yellowing resistance of the adhesive layer. The amount of isoprene units is based on the isobutene units and isoprene units excluding modified portions (for example, portions derived from maleic anhydride for introducing acid anhydride groups, portions derived from maleic anhydride-(meth)acrylate copolymers, etc.).

[0031] <(C) component> The component (C) used in the present invention is an olefin polymer having an acid anhydride group (i.e., a carbonyloxycarbonyl group (-CO-O-CO-)) and / or a carboxy group and a number average molecular weight of less than 10,000, and preferably an olefin polymer having an acid anhydride group and a number average molecular weight of less than 10,000. In this specification, the term "olefin polymer" refers to a polymer in which olefin units are the main structural units (i.e., the amount of olefin units is the largest among all structural units).

[0032] The olefin polymer may be an olefin resin (e.g., a propylene-butene copolymer) or an olefin rubber (e.g., a butyl rubber, i.e., an isobutene-isoprene copolymer). In this specification, "olefin resin" means an olefin polymer that cannot form a rubber elastomer by crosslinking, and "olefin rubber" means an olefin polymer that can form a rubber elastomer by crosslinking.

[0033] The olefin is preferably a monoolefin having one olefinic carbon-carbon double bond and / or a diolefin having two olefinic carbon-carbon double bonds. Examples of monoolefins include α-olefins such as ethylene, propylene, 1-butene, isobutene (isobutylene), 1-pentene, 1-hexene, 1-heptene, and 1-octene. Examples of diolefins include 1,3-butadiene, isoprene, 1,3-pentadiene, and 2,3-dimethylbutadiene.

[0034] The olefin-based polymer may be a homopolymer or a copolymer. The copolymer may be a random copolymer or a block copolymer. The olefin-based polymer may also be a copolymer of an olefin and a monomer other than an olefin. Examples of the olefin-based copolymer include an ethylene-non-conjugated diene copolymer, an ethylene-propylene copolymer, an ethylene-propylene-non-conjugated diene copolymer, an ethylene-butene copolymer, a propylene-butene copolymer, a propylene-butene-non-conjugated diene copolymer, an isobutene-isoprene copolymer, a styrene-isobutene copolymer, and a styrene-isobutene-styrene copolymer.

[0035] When an olefin polymer having an acid anhydride group and a number average molecular weight of less than 10,000 is used as component (C), the concentration of the acid anhydride group in the polymer is preferably 0.05 to 3 mmol / g, more preferably 0.1 to 2 mmol / g, from the viewpoint of the deformability and recoverability of the adhesive layer. The concentration of the acid anhydride group is obtained from the acid value, which is defined as the number of milligrams of potassium hydroxide required to neutralize the acid present in 1 g of polymer, according to the description of JIS K 2501.

[0036] When an olefin polymer having carboxy groups and a number average molecular weight of less than 10,000 is used as component (C), the concentration of carboxy groups in the polymer is preferably 0.05 to 3 mmol / g, more preferably 0.1 to 2 mmol / g, from the viewpoint of the deformability and recovery of the adhesive layer. The concentration of carboxy groups is obtained from the acid value, which is defined as the number of milligrams of potassium hydroxide required to neutralize the acid present in 1 g of polymer, as described in JIS K 2501.

[0037] When an olefin polymer having an acid anhydride group and a carboxy group and a number average molecular weight of less than 10,000 is used as component (C), the sum of the concentration of the acid anhydride group and the concentration of the carboxy group in the polymer is preferably 0.05 to 3 mmol / g, more preferably 0.1 to 2 mmol / g, from the viewpoint of the deformability and recoverability of the adhesive layer.

[0038] The number average molecular weight of component (C) is preferably 300 or more and less than 10,000, more preferably 500 to 8,000, and even more preferably 1,000 to 6,000, from the viewpoint of deformability of the adhesive layer.

[0039] The component (C) can be produced, for example, by graft-modifying an olefin polymer with an unsaturated compound having an acid anhydride group and / or a carboxy group (for example, maleic anhydride) under radical reaction conditions.

[0040] Polymers available from manufacturers can be used as component (C). Examples of such polymers include "HV-300M" (maleic anhydride-modified liquid polybutene) manufactured by Toho Chemical Industry Co., Ltd., "ER688" (maleic anhydride-modified liquid polybutene) manufactured by Seiko PMC Corporation, and "Lucant A-5515" (acid-modified ethylene-α-olefin copolymer), "Lucant A-5260" (acid-modified ethylene-α-olefin copolymer), and "Lucant A-5320H" (acid-modified ethylene-α-olefin copolymer) manufactured by Mitsui Chemicals, Inc.

[0041] In one embodiment of the present invention, component (C) is preferably a polybutene having an acid anhydride group and / or a carboxy group and having a number average molecular weight of less than 10,000, and more preferably a polybutene having an acid anhydride group and having a number average molecular weight of less than 10,000.

[0042] The content of component (C) is preferably 3% by mass or more, more preferably 5% by mass or more, and even more preferably 10% by mass or more, relative to 100% by mass of the non-volatile content of the adhesive composition, from the viewpoint of the deformability of the adhesive layer, and is preferably 70% by mass or less, more preferably 60% by mass or less, and even more preferably 50% by mass or less, from the viewpoint of the recovery property of the adhesive layer.

[0043] <Amount of component (A), and amounts of components (B) and (C) used> The amount of component (A) used and the amounts of components (B) and (C) used are preferably determined by the ratio of the functional groups they contain. From the viewpoint of the recovery of the adhesive layer, the ratio of "the amount (mol) of epoxy groups contained in component (A)" to "the total amount (mol) of acid anhydride groups contained in components (B) and (C) and the total amount (mol) of carboxy groups contained in components (B) and (C)" is preferably 20:80 to 80:20, more preferably 25:75 to 75:25, and even more preferably 30:70 to 70:30. Note that, for example, when component (B) and component (C) both contain only acid anhydride groups, the "total amount (mol) of acid anhydride groups and the total amount (mol) of carboxy groups" means "the total amount (mol) of acid anhydride groups."

[0044] <Other ingredients> The adhesive composition of the present invention may contain components other than components (A) to (C) (hereinafter, sometimes referred to as "other components"), as long as the effects of the present invention are not impaired. Examples of other components include liquid olefin polymers, plasticizers, antioxidants, metal complexes, curing agent accelerators, etc. These may be used alone or in combination of two or more. The liquid olefin polymers, etc. will be described below in order.

[0045] (liquid olefin polymer) In the present invention, a liquid olefin-based polymer other than components (A), (B), and (C) may be used to impart good adhesion and even better deformability to the adhesive layer. In the present invention, the term "liquid" in "liquid olefin-based polymer" means that the viscosity at 25°C is 5,000 Pa·s or less. Furthermore, in the present invention, the term "viscosity at 25°C" means the viscosity calculated by multiplying the kinematic viscosity at 25°C measured using a dynamic viscoelasticity measuring device by the density. Examples of dynamic viscoelasticity measuring devices include a rheometer (trade name: DISCOVERY HR-2) manufactured by TA Instruments. The explanations and examples of "olefin" and "olefin-based polymer" in "liquid olefin-based polymer" are the same as those for component (C).

[0046] Among liquid olefin polymers, liquid isobutene polymers having epoxy groups are classified as component (A) in the present invention. Furthermore, among liquid olefin polymers, liquid isobutene polymers having acid anhydride groups and / or carboxy groups and having a number average molecular weight of 10,000 or more are classified as component (B) in the present invention. Furthermore, among liquid olefin polymers, liquid olefin polymers having acid anhydride groups and / or carboxy groups and having a number average molecular weight of less than 10,000 are classified as component (C).

[0047] The viscosity of the liquid olefin polymer at 25° C. is preferably 50 to 5,000 Pa·s, more preferably 50 to 4,000 Pa·s, and even more preferably 100 to 3,000 Pa·s, from the viewpoint of the deformability of the adhesive layer.

[0048] The number average molecular weight of the liquid polyolefin polymer is determined from the viewpoint of adhesiveness of the adhesive layer. The molecular weight is preferably 100 to 50,000, more preferably 200 to 30,000, and even more preferably 300 to 20,000.

[0049] Commercially available liquid olefin polymers can be used. Examples of such commercially available products include ENEOS "HV-300" (liquid polybutene), ENEOS "HV-1900" (liquid polybutene), ENEOS "HV-50" (liquid polybutene), ENEOS "HV-35" (liquid polybutene), Kothari "950MW" (liquid polybutene), Kothari "2400MW" (liquid olefin polymer), INEOS "H-1900" (liquid polybutene), and INEOS "H-6000" (liquid polybutene). Liquid polybutene), INEOS "H-18000" (liquid polybutene), NOF Corporation "200N" (liquid polybutene), Nippon Soda Co., Ltd. "BI-2000" (hydrogenated polybutadiene), Nippon Soda Co., Ltd. "BI-3000" (hydrogenated polybutadiene), Nippon Soda Co., Ltd. "GI-3000" (hydrogenated polybutadiene), Mitsui Chemicals Inc. "Lucant LX100" (liquid olefin polymer), Mitsui Chemicals Inc. "Lucant LX400" (liquid olefin polymer), Idemitsu Showa Shell Co., Ltd. "Poly bd R-45HT" (liquid butadiene rubber), Idemitsu Showa Shell Co., Ltd. "Poly bd R-15HT" (liquid butadiene rubber), Idemitsu Showa Shell Co., Ltd. "Poly ip" (liquid polyisoprene), Nippon Soda's "B-1000" (liquid polybutadiene), Nippon Soda's "B-3000" (liquid polybutadiene), Nippon Soda's "G-3000" (liquid polybutadiene), Kuraray's "LIR-30" (liquid polyisoprene), Kuraray's "LIR-390" (liquid polyisoprene), Kuraray's "LIR-290" (liquid polyisoprene), Kuraray's "LBR-302" (liquid polybutadiene), Kuraray's "LBR-305" (liquid polybutadiene), Kuraray's "LBR-361" (liquid polybutadiene), Kuraray's "L-SBR-820" (liquid styrene-butadiene random copolymer), CRAY VALLEY's "Ricon154" (liquid butadiene), CRAY Examples include "RICON 184" (liquid styrene-butadiene random copolymer) manufactured by Valley.

[0050] The liquid olefin polymer is preferably liquid polybutene. When a liquid olefin-based polymer is used, its content in the adhesive composition is preferably 3 to 50 mass %, more preferably 5 to 40 mass %, and even more preferably 10 to 30 mass %, relative to 100 mass % of the non-volatile content of the adhesive composition, from the viewpoint of adhesion of the adhesive layer.

[0051] (plasticizer) In the present invention, a plasticizer may be used to impart better deformability to the adhesive layer, such as phthalate ester plasticizers, adipate ester plasticizers, phosphate ester plasticizers, trimellitate ester plasticizers, sulfonate ester plasticizers, petroleum oils, polyol polyesters, animal oils, vegetable oils, and castor oil derivatives.

[0052] Examples of phthalate ester plasticizers include dioctyl phthalate (DOP) and dibutyl phthalate (DBP). Examples of adipate ester plasticizers include dioctyl adipate, propylene glycol adipate polyester, and butylene glycol adipate polyester. Examples of phosphate ester plasticizers include tricresyl phosphate and trioctyl phosphate. Examples of trimellitate ester plasticizers include trioctyl trimellitate. Examples of sulfonate ester plasticizers include alkyl sulfonates.

[0053] Examples of petroleum oils include paraffin oil (liquid paraffin), naphthenic oil, aromatic oil, etc. Examples of polyol polyesters include diethylene glycol dibenzoate, pentaerythritol ester, etc.

[0054] Examples of animal oils include squalane, squalene, etc. Examples of vegetable oils include olive oil, camellia oil, castor oil, tall oil, peanut oil, cottonseed oil, rapeseed oil, soybean oil, palm oil, coconut oil, etc.

[0055] Castor oil derivatives are commercially available as plasticizers from various manufacturers. Examples of commercially available castor oil derivatives include "Castor Hydrogenated Oil A," "CO-FA," "DCO-FA," "Riccizer S4," "Riccizer C-101," "Riccizer GR-310," and "Riccizer S-8" manufactured by Ito Oil Mills; "Brawnon BR-410," "Brawnon BR-410," "Brawnon BR-430," "Brawnon BR-450," "Brawnon CW-10," "Brawnon RCW-20," "Brawnon RCW-40," "Brawnon RCW-50," and "Brawnon RCW-60" manufactured by Aoki Oil & Fat Industries; and "Castor Wax A," "Newcizer 510R," "Sakura Stearate," "Castor Hydrogenated Fatty Acid," "NAA-34," "NAA-160," and "NAA-175" manufactured by NOF Corporation.

[0056] When a plasticizer is used, its content in the adhesive composition is preferably 1 to 40 mass %, more preferably 3 to 30 mass %, and even more preferably 5 to 25 mass %, relative to 100 mass % of the non-volatile content of the adhesive composition, from the viewpoint of the deformability and adhesion of the adhesive layer.

[0057] (antioxidant) In the present invention, there is no particular limitation on the antioxidant, and known antioxidants can be used. When an antioxidant is used, the content thereof is, relative to 100% by mass of the nonvolatile content of the adhesive composition, The content is preferably 0.05 to 5 mass %, more preferably 0.10 to 4 mass %, and even more preferably 0.20 to 3 mass %.

[0058] (metal complexes) In the present invention, in order to form an adhesive layer with even better recovery properties, a metal complex may be used in which a bidentate ligand in which both coordinating atoms are oxygen atoms (hereinafter sometimes referred to as an "oxygen-bidentate ligand") and a monodentate ligand in which the coordinating atom is an oxygen atom (hereinafter sometimes referred to as an "oxygen-monodentate ligand") are bonded to a central metal.

[0059] The metal complex is preferably represented by the following formula (1):

[0060] [ka]

[0061] [In formula (1), M represents a divalent or higher metal; R1 and R3 each independently represent a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, an alkoxy group, an alkenyloxy group, an aryl group, or an aralkyl group; R2 represents a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, an alkoxy group, an alkenyloxy group, an alkoxycarbonyl group, an aryl group, or an aralkyl group; X represents a monodentate ligand; In formula (1), the solid line between the oxygen atom (O) in [ ] and M represents a covalent bond. The dashed line between the oxygen atom (O) and M in [ ] in formula (1) represents a coordinate bond, and m represents 3 or 4, n represents an integer of 0 to 4, and m≧n. The metal complex (1) may be used alone or in combination of two or more kinds thereof.

[0062] M in the above formula (1) is preferably a metal of Group 4 of the periodic table or a metal of Group 13 of the periodic table, and more preferably aluminum, titanium or zirconium.

[0063] In this specification, examples of halogen atoms include fluorine atoms, chlorine atoms, bromine atoms, and iodine atoms.

[0064] In this specification, the alkyl group may be either linear or branched. The number of carbon atoms in the alkyl group (excluding the alkyl group in the long-chain alkyl (meth)acrylate) is preferably 1 to 20, more preferably 1 to 10, and particularly preferably 1 to 6. Examples of the alkyl group include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, a pentyl group, an isopentyl group, a neopentyl group, a 1-ethylpropyl group, a hexyl group, an isohexyl group, a 1,1-dimethylbutyl group, a 2,2-dimethylbutyl group, a 3,3-dimethylbutyl group, and a 2-ethylbutyl group. The alkyl group may have a substituent. Examples of the substituent include a halogen atom, a hydroxy group, and an amino group which may have a substituent.

[0065] In this specification, the alkenyl group may be either linear or branched. The number of carbon atoms in the alkenyl group is preferably 2 to 20. Examples of the alkenyl group include ethenyl (i.e., vinyl), 1-propenyl, 2-propenyl, 2-methyl-1-propenyl, 1-butenyl, 2-butenyl, 3-butenyl, 3-methyl-2-butenyl, 1-pentenyl, 2-pentenyl, 3-pentenyl, 4-pentenyl, 4-methyl-3-pentenyl, 1-hexenyl, 3-hexenyl, and 5-hexenyl. The alkenyl group may have a substituent. Examples of the substituent include a halogen atom, a hydroxyl group, and an amino group that may have a substituent.

[0066] In this specification, the alkynyl group may be either linear or branched. The number of carbon atoms in the alkynyl group is preferably 2 to 10, more preferably 2 to 6. Examples of the alkynyl group include an ethynyl group, a 1-propynyl group, a 2-propynyl group, a 1-butynyl group, a 2-butynyl group, a 3-butynyl group, a 1-pentynyl group, a 2-pentynyl group, a 3-pentynyl group, a 4-pentynyl group, a 1-hexynyl group, a 2-hexynyl group, a 3-hexynyl group, a 4-hexynyl group, a 5-hexynyl group, and a 4-methyl-2-pentynyl group. The alkynyl group may have a substituent. Examples of the substituent include a halogen atom, a hydroxy group, and an amino group which may have a substituent.

[0067] In this specification, the number of carbon atoms in the aryl group is preferably 6 to 18, more preferably 6 to 14. Examples of the aryl group include a phenyl group, a 1-naphthyl group, a 2-naphthyl group, a 1-anthryl group, a 2-anthryl group, and a 9-anthryl group. The aryl group may have a substituent. Examples of the substituent include a halogen atom, a hydroxy group, an alkyl group which may have a substituent, an alkenyl group which may have a substituent, an alkynyl group which may have a substituent, and an amino group which may have a substituent.

[0068] In this specification, the number of carbon atoms in the aralkyl group is preferably 7 to 16. Examples of the aralkyl group include a benzyl group, a phenethyl group, a naphthylmethyl group, and a phenylpropyl group. The aralkyl group may have a substituent. Examples of the substituent include a halogen atom, a hydroxy group, and an amino group which may have a substituent.

[0069] In this specification, examples of the amino group which may have a substituent include an amino group, a mono- or di-alkylamino group (e.g., a methylamino group, a dimethylamino group, an ethylamino group, a diethylamino group, a propylamino group, a dibutylamino group), a mono- or di-cycloalkylamino group (e.g., a cyclopropylamino group, a cyclohexylamino group), a mono- or di-arylamino group (e.g., a phenylamino group), a mono- or di-aralkylamino group (e.g., a benzylamino group, a dibenzylamino group), a heterocyclic amino group (e.g., a pyridylamino group), and the like.

[0070] In this specification, the explanation of the alkyl group in the alkoxy group (i.e., alkyloxy group) is the same as the explanation of the alkyl group described above. The alkoxy group may have a substituent. Examples of the substituent include a halogen atom, a hydroxy group, and an amino group which may have a substituent.

[0071] In this specification, the alkenyl group in the alkenyloxy group is the same as the above-mentioned alkenyl group. The alkenyloxy group may have a substituent. Examples of the substituent include a halogen atom, a hydroxy group, and an amino group which may have a substituent.

[0072] In this specification, the alkyl group in the alkoxycarbonyl group (i.e., alkyloxycarbonyl group) is the same as the alkyl group described above. The alkoxycarbonyl group may have a substituent. Examples of the substituent include a halogen atom, a hydroxy group, and an amino group which may have a substituent.

[0073] The monodentate ligand represented by X in formula (1) is, for example, an alkoxide anion (RO - ) (wherein R represents an organic group), carboxylate anion (RCOO - ) (wherein R represents an organic group), oxo (O), and the like.

[0074] The alkoxide anion is RO- (wherein R represents an organic group). The organic group R may be either an aliphatic group or an aromatic group. The aliphatic group may be either a saturated aliphatic group or an unsaturated aliphatic group. The number of carbon atoms in the organic group R is preferably 1 to 20, more preferably 6 to 18, and particularly preferably 8 to 14. The alkoxide anion (RO - ) include, for example, methoxide, ethoxide, propoxide, isopropoxide, butoxide, isobutoxide, sec-butoxide, tert-butoxide, pentyl oxide, hexyl oxide, phenoxide, 4-methylphenoxide, and the like.

[0075] The carboxylate anion is RCOO - (wherein R represents an organic group). The organic group R may be either an aliphatic group or an aromatic group. The aliphatic group may be either a saturated aliphatic group or an unsaturated aliphatic group. The number of carbon atoms in the organic group R is preferably 1 to 20, more preferably 6 to 18, and particularly preferably 8 to 14. The carboxylate anion (RCOO - ) include, for example, carboxylate anions corresponding to carboxylic acids such as acetic acid, propionic acid, butanoic acid, pentanoic acid, hexanoic acid, heptanoic acid, octanoic acid, octylic acid, nonanoic acid, decanoic acid, dodecanoic acid, stearic acid, oleic acid, linoleic acid, linolenic acid, arachidonic acid, eicosapentaenoic acid, docosahexaenoic acid, and benzoic acid.

[0076] In formula (1), the brackets [ ] represent a polydentate ligand. Examples of the polydentate ligand include acetylacetone, 3-methyl-2,4-pentanedione, acetylacetaldehyde, 2,4-hexanedione, 2,4-heptanedione, 5-methyl-2,4-hexanedione, 5,5-dimethyl-2,4-hexanedione, benzoylacetone, benzoylacetophenone, salicylaldehyde, 1,1,1-trifluoroacetylacetone, 1,1,1,5,5,5-hexafluoroacetylacetone, 3-methoxy-2,4-pentanedione, 3-cyano-2,4-pentanedione, 3-nitro-2,4-pentanedione, 3-chloro-2,4-pentanedione, acetoacetic acid, methyl acetoacetate, ethyl acetoacetate, propyl acetoacetate, salicylic acid, methyl salicylate, malonic acid, dimethyl malonate, and diethyl malonate. When coordinated to the metal center, the multidentate ligand has a structure that has one or more protons removed from it.

[0077] Specific examples of metal complex (1) in which M is aluminum include aluminum diisopropylate mono-sec-butylate, aluminum tri-sec-butylate, aluminum triisopropylate, aluminum triethylate, aluminum tris(acetylacetonate), aluminum bis(ethylacetoacetate) mono(acetylacetonate), aluminum tris(ethylacetoacetate), aluminum octadecenylacetoacetate diisopropylate, aluminum ethylacetoacetate diisopropylate, aluminum ethylacetoacetate di-n-butylate, aluminum propylacetoacetate diisopropylate, aluminum n-butylacetoacetate diisopropylate, aluminum tris(ethylacetoacetate), aluminum mono(acetylacetonate)bis(ethylacetoacetate), and aluminum tris(acetylacetonate).

[0078] Specific examples of the metal complex (1) in which M is titanium include tetraisopropyl titanate, tetranormalbutyl titanate, tetraoctyl titanate, tetratert-butyl titanate, tetrastearyl titanate, titanium tetraacetylacetonate, titanium octylene glycolate (also known as bis(2-ethylhexyloxy)bis(2-ethyl-3-oxohexyloxy)titanium(IV)), titanium diisopropoxide bis(ethylacetoacetate), Examples include allyl acetoacetate triisopropoxide, titanium di-normal butoxide bis(2,4-pentanedionate), titanium diisopropoxide bis(tetramethylheptanedionate), titanium diisopropoxide bis(ethyl acetoacetate), titanium(IV) tetra(methylphenolate), titanium oxide bis(2,4-pentanedionate), monoisopropoxy titanium triisostearate, and diisopropoxy titanium diisostearate.

[0079] Specific examples of the metal complex (1) in which M is zirconium include zirconium tetra-normal propoxide, zirconium tetra-normal butoxide, zirconium tetra(acetylacetonate), zirconium allylacetoacetate triisopropoxide, zirconium di-normal butoxide bis(2,4-pentanedionate), zirconium diisopropoxide bis(2,4-pentanedionate), zirconium diisopropoxide bis(tetramethylheptanedionate), zirconium diisopropoxide bis(ethylacetoacetate), zirconium butoxide(acetylacetate)bis(ethylacetoacetate), zirconium tributoxide monoacetylacetonate, zirconium octylate, zirconium stearate, tri-normal butoxyzirconium monooctylate, and tri-normal butoxyzirconium monostearate.

[0080] When a metal complex is used, its content in the adhesive composition is preferably 0.5 to 20 mass %, more preferably 1.0 to 15 mass %, and even more preferably 1.5 to 10 mass %, relative to 100 mass % of the non-volatile content of the adhesive composition, from the viewpoint of the recovery property of the adhesive layer.

[0081] (curing accelerator) In the present invention, a curing accelerator may be used to accelerate the crosslinking reaction between the epoxy groups in component (A) and the acid anhydride groups and / or carboxyl groups in components (B) and (C). Examples of curing accelerators include imidazole compounds, tertiary and quaternary amine compounds, dimethylurea compounds, and organic phosphine compounds.

[0082] Examples of the imidazole compound include 1H-imidazole, 2-methylimidazole, 2-phenyl-4-methylimidazole, 2-ethyl-4-methylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole, 2-undecylimidazole, 1-cyanoethyl-2-undecylimidazole, 1-cyanoethyl-2-undecylimidazole, 1-cyanoethyl-2-undecylimidazolium trimellitate, 2-phenyl-4,5-bis(hydroxymethyl)imidazole, 1-benzyl-2-methylimidazole, 1-benzyl-2-phenylimidazole, 2-phenylimidazole, 2-dodecylimidazole, 2-heptadecylimidazole, 1,2-dimethylimidazole, and 2-phenyl-4-methyl-5-hydroxymethylimidazole. Specific examples of imidazole compounds include Curezol 2MZ, 2P4MZ, 2E4MZ, 2E4MZ-CN, C11Z, C11Z-CN, C11Z-CNS, C11Z-A, 2PHZ, 1B2MZ, 1B2PZ, 2PZ, C17Z, 1.2DMZ, 2P4MHZ-PW, 2MZ-A, and 2MA-OK (all manufactured by Shikoku Chemicals Corporation).

[0083] The tertiary and quaternary amine compounds are not particularly limited, and examples thereof include quaternary ammonium salts such as tetramethylammonium bromide, tetrabutylammonium bromide, and triethylmethylammonium 2-ethylhexanoate; diazabicyclo compounds such as DBU (1,8-diazabicyclo[5.4.0]undecene-7), DBN (1,5-diazabicyclo[4.3.0]nonene-5), DBU-phenolate, DBU-octylate, DBU-p-toluenesulfonate, DBU-formate, and DBU-phenol novolac resin salt; tertiary amines or salts thereof such as benzyldimethylamine, 2-(dimethylaminomethyl)phenol, and 2,4,6-tris(dimethylaminomethyl)phenol (TAP); and dimethylurea compounds such as aromatic dimethylurea and aliphatic dimethylurea.

[0084] Examples of dimethylurea compounds include aromatic dimethylureas such as DCMU (3-(3,4-dichlorophenyl)-1,1-dimethylurea) and U-CAT3512T (manufactured by San-Apro Co., Ltd.); and aliphatic dimethylureas such as U-CAT3503N (manufactured by San-Apro Co., Ltd.). Among these, aromatic dimethylureas are preferably used from the viewpoint of curability.

[0085] Examples of organic phosphine compounds include triphenylphosphine, tetraphenylphosphonium tetra-p-tolylborate, tetraphenylphosphonium tetraphenylborate, tri-tert-butylphosphonium tetraphenylborate, (4-methylphenyl)triphenylphosphonium thiocyanate, tetraphenylphosphonium thiocyanate, butyltriphenylphosphonium thiocyanate, triphenylphosphine triphenylborane, etc. Specific examples of organic phosphine compounds include TPP, TPP-MK, TPP-K, TTBuP-K, TPP-SCN, TPP-S (all manufactured by Hokko Chemical Industry Co., Ltd.), etc.

[0086] When a curing accelerator is used, its content in the adhesive composition is preferably 0.01 to 5 mass%, more preferably 0.05 to 4 mass%, and even more preferably 0.10 to 3 mass%, relative to 100 mass% of the nonvolatile content of the adhesive composition, in order to promote the crosslinking reaction between the epoxy groups of component (A) and the acid anhydride groups and / or carboxyl groups of components (B) and (C).

[0087] adhesive sheet The present invention also provides a pressure-sensitive adhesive sheet having a laminated structure including a support and an adhesive layer formed from the pressure-sensitive adhesive composition of the present invention. A protective sheet may be used in the present invention. That is, the pressure-sensitive adhesive sheet of the present invention may have a laminated structure including a support, an adhesive layer, and a protective sheet in this order. Other layers (e.g., release layers) may be present between the support and the adhesive layer, and between the adhesive layer and the protective sheet.

[0088] Examples of the support and protective sheet include polyolefins such as polyethylene, polypropylene, and polyvinyl chloride; cycloolefin polymers; polyesters such as polyethylene terephthalate (hereinafter sometimes referred to as "PET") and polyethylene naphthalate; polycarbonate; and plastic films such as polyimide. The support and protective sheet may both be single-layer films or laminate films.

[0089] The support and protective sheet may be, for example, a low-moisture-permeable film having a barrier layer, or a laminate film of a low-moisture-permeable film having a barrier layer and another film. Examples of barrier layers include inorganic films such as silica vapor deposition films, silicon nitride films, and silicon oxide films. The barrier layer may be composed of multiple layers of inorganic films (e.g., silica vapor deposition films). The barrier layer may also be composed of organic and inorganic materials, or may be a composite multilayer of organic and inorganic films.

[0090] The surface of the protective sheet that contacts the adhesive layer is preferably release-treated. On the other hand, the support may or may not be release-treated. Examples of release treatments include release treatments using a release agent such as a silicone resin-based release agent, an alkyd resin-based release agent, or a fluororesin-based release agent.

[0091] The thicknesses of the support and the protective sheet are not particularly limited, but from the viewpoint of ease of handling of the pressure-sensitive adhesive sheet, each is preferably 10 to 150 μm, more preferably 20 to 100 μm. When the support and the protective sheet are laminated films, the thicknesses mentioned above are the thicknesses of the laminated films. On the other hand, from the viewpoint of adhesion and stress relaxation during bending, the thickness of the pressure-sensitive adhesive layer is preferably 5 to 200 μm, more preferably 10 to 150 μm, and even more preferably 20 to 100 μm.

[0092] Production of adhesive composition and adhesive sheet The adhesive composition of the present invention can be produced by mixing the above-mentioned components using known equipment.

[0093] The adhesive sheet of the present invention can be produced, for example, by (i) dissolving the above-mentioned components in an organic solvent to prepare a varnish of the adhesive composition, (ii) applying the obtained varnish to a support to form a coating film, and (iii) heating the obtained coating film to remove the organic solvent.

[0094] Examples of organic solvents that can be used to prepare the varnish include ketones such as acetone, methyl ethyl ketone, and cyclohexanone; acetate esters such as ethyl acetate, butyl acetate, cellosolve acetate, propylene glycol monomethyl ether acetate, and carbitol acetate; cellosolves such as cellosolve; carbitols such as butyl carbitol; aromatic hydrocarbons such as toluene and xylene; amides of dimethylformamide, dimethylacetamide, and N-methylpyrrolidone; and the like. Only one organic solvent may be used, or two or more may be used in combination. Commercially available organic solvents may also be used. Examples of commercially available organic solvents include "Swasol" manufactured by Maruzen Petrochemical Co., Ltd. and "Ipsol" manufactured by Idemitsu Kosan Co., Ltd. The varnish can be applied by any known method (e.g., a method using a die coater), and the application method is not particularly limited.

[0095] In order to promote the reaction between the epoxy groups of component (A) and the acid anhydride groups and / or carboxyl groups of components (B) and (C), the organic solvent is preferably removed by heating the coating film. The heating temperature of the coating film is preferably 80 to 200°C, more preferably 100 to 180°C, and the heating time is preferably 2 to 90 minutes, more preferably 5 to 60 minutes. The coating film may be heated under normal pressure or under reduced pressure.

[0096] Uses of the adhesive composition and adhesive sheet The pressure-sensitive adhesive composition and pressure-sensitive adhesive sheet of the present invention are useful for producing flexible electronic devices. The pressure-sensitive adhesive sheet of the present invention can also be used as an optically transparent adhesive sheet (OCA) or the like.

[0097] Flexible Electronic Devices The present invention also provides a flexible electronic device comprising an adhesive layer formed from the adhesive composition of the present invention. The flexible electronic device of the present invention can be produced, for example, by (i) producing an adhesive sheet of the present invention using the adhesive composition of the present invention, and (ii) using the adhesive sheet of the present invention to form an adhesive layer in the flexible electronic device (e.g., by laminating the adhesive sheet of the present invention on the substrate of the flexible electronic device to form an adhesive layer). The flexible electronic device of the present invention can also be produced by using the adhesive sheet of the present invention for interlayer adhesion of multiple materials (e.g., touch panel sensors, polarizing plates, surface protection sheets, etc.), forming an adhesive layer on an arbitrary material (layer) using the adhesive sheet of the present invention, and then laminating another arbitrary material (layer) on top of the adhesive layer. [Example]

[0098] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples and can be practiced with appropriate modifications within the scope of the above and below aims, all of which are included within the technical scope of the present invention. Furthermore, "parts" and "%" in the amounts of components and copolymerized units mean "parts by mass" and "% by mass," respectively, unless otherwise specified.

[0099] <Ingredients> The components used in the examples and comparative examples are shown below. (1) Component (A) "ER866" (Seiko PMC Corporation, glycidyl methacrylate modified butyl rubber, epoxy group concentration: 1.63 mmol / g, number average molecular weight: 113,000, isobutene unit / isoprene unit: 98.9% / 1.1%) "ER869" (Seiko PMC Corporation, glycidyl methacrylate-2-ethylhexyl acrylate random copolymer modified butyl rubber, 2-ethylhexyl acrylate unit concentration: 0.067 mmol / g, epoxy group concentration: 1.51 mmol / g, number average molecular weight: 189,000, isobutene unit / isoprene unit ratio: 98.9% / 1.1%)

[0100] (2)(B) Component "ER661" (manufactured by Seiko PMC Corporation, maleic anhydride-butyl methacrylate random copolymer modified butyl rubber, butyl methacrylate unit concentration: 0.32 mmol / g, acid anhydride group concentration: 0.46 mmol / g, number average molecular weight: 40,000, isobutene unit / isoprene unit ratio: 98.9% / 1.1%) "ER669" (manufactured by Seiko PMC Corporation, maleic anhydride-2-ethylhexyl acrylate random copolymer modified butyl rubber (2-ethylhexyl acrylate unit concentration: 0.21 mmol / g, acid anhydride group concentration: 0.43 mmol / g, number average molecular weight: 96,000, isobutene unit / isoprene unit: 98.9% / 1.1%)

[0101] (3)(C) component "HV-300M" (manufactured by Toho Chemical Industry Co., Ltd., maleic anhydride-modified liquid polybutene, acid anhydride group concentration: 0.77 mmol / g, number average molecular weight: 2,100) "ER688" (Seiko PMC Corporation, maleic anhydride-modified liquid polybutene, acid anhydride group concentration: 0.29 mmol / g, number average molecular weight: 2,100)

[0102] (4) Liquid olefin polymer "HV-1900" (ENEOS Corporation, liquid polybutene, number average molecular weight: 2,900, viscosity at 25°C: 460 Pa·s)

[0103] (5) Plasticizers "Riccizer S-8" (manufactured by Ito Oil Mills, castor oil derivative)

[0104] (6) Antioxidants "Irganox 1010" (BASF, hindered phenol antioxidant) "Irgafos 168" (BASF, phosphorus-based antioxidant)

[0105] (7) Metal complexes "Plenact AL-M" (Ajinomoto Fine-Techno Co., Ltd., aluminum octadecenyl acetoacetate diisopropylate)

[0106] (8) Hardener accelerator "U CAT-18X" (San-Apro Co., Ltd., triethylmethylammonium 2-ethylhexane salt)

[0107] Example 1 Varnishes having the blending ratios shown in the table below were prepared by the following procedure, and adhesive sheets were produced using the resulting varnishes. The amount (parts) of each component used in the table below indicates the amount of non-volatile content of each component in the varnish.

[0108] Specifically, glycidyl methacrylate-modified butyl rubber ("ER866" manufactured by Seiko PMC Corporation), maleic anhydride-butyl methacrylate random copolymer-modified butyl rubber ("ER661" manufactured by Seiko PMC Corporation), maleic anhydride-modified liquid polybutene ("HV-300M" manufactured by Toho Chemical Industry Co., Ltd.), liquid polybutene ("HV-1900" manufactured by ENEOS Corporation), plasticizer ("Riccizer S-8" manufactured by Ito Oil Mills, Inc.), metal complex ("Plenact AL-M" manufactured by Ajinomoto Fine-Techno Co., Inc.), hindered phenol-based antioxidant ("Irganox 1010" manufactured by BASF), phosphorus-based antioxidant ("Irgafos 168" manufactured by BASF), curing accelerator ("U CAT-18X" manufactured by San-Apro Co., Ltd.), and toluene were blended, and the resulting mixture was uniformly dispersed in a high-speed rotating mixer to obtain a varnish of the adhesive composition. The obtained varnish was uniformly applied using a die coater onto the release-treated surface of a polyethylene terephthalate (PET) film ("SP3000" manufactured by Toyo Cross Co., Ltd., PET film thickness: 38 μm) that had been treated with a silicone-based release agent, and heated at 130°C for 30 minutes to obtain an adhesive sheet with a 50 μm-thick adhesive layer.

[0109] <Example 2> A varnish of the adhesive composition and an adhesive sheet having a 50 μm thick adhesive layer were prepared in the same manner as in Example 1, except that a glycidyl methacrylate-2-ethylhexyl acrylate random copolymer modified butyl rubber (manufactured by Seiko PMC Corporation, "ER869") was used as component (A) instead of a glycidyl methacrylate-modified butyl rubber (manufactured by Seiko PMC Corporation, "ER866"), and a maleic anhydride-2-ethylhexyl acrylate random copolymer modified butyl rubber (manufactured by Seiko PMC Corporation, "ER669") was used as component (B) instead of a maleic anhydride-butyl methacrylate random copolymer modified butyl rubber (manufactured by Seiko PMC Corporation, "ER661").

[0110] Example 3 A varnish of the adhesive composition and an adhesive sheet having a 50 μm thick adhesive layer were prepared in the same manner as in Example 1, except that maleic anhydride-modified liquid polybutene ("ER688" manufactured by Seiko PMC Corporation) was used as component (C) instead of maleic anhydride-modified liquid polybutene ("HV-300M" manufactured by Toho Chemical Industry Co., Ltd.) and the amounts of components (A) and (B) used were changed.

[0111] <Comparative Example 1> A varnish of the adhesive composition and an adhesive sheet having an adhesive layer with a thickness of 50 μm were prepared in the same manner as in Example 1, except that component (B) was not used.

[0112] <Comparative Example 2> A varnish of the adhesive composition and an adhesive sheet having an adhesive layer with a thickness of 50 μm were prepared in the same manner as in Example 1, except that component (C) was not used.

[0113] <Evaluation of deformability and recovery> The obtained adhesive sheet was folded, and the folded adhesive sheet was punched out with a belt punch having a diameter of 8 mm. The support was peeled off from both sides of the punched piece to prepare an evaluation sample having a thickness of approximately 0.8 mm and a diameter of 8 mm.

[0114] The obtained evaluation sample was placed in a DHR parallel plate rheometer, and the shear strain S1 of the evaluation sample was measured after a shear stress of 95 kPa was applied for 5 seconds.The shear strain S2 of the evaluation sample was then measured 60 seconds after the applied stress was released.

[0115] The deformability of the evaluation samples was evaluated according to the following criteria. The results are shown in Table 1. (Deformability criteria) 〇 (Good): Shear strain S1 is 5.0 or more × (bad): Shear strain S1 is less than 5.0

[0116] From the shear strain S1 and shear strain S2, the following formula is obtained: Strain recovery rate (%) = 100 × (S1 - S2) / S1 The strain recovery rate was calculated by the above method, and the recoverability of the evaluation sample was evaluated according to the following criteria. The results are shown in Table 1. (Resilience criteria) Good: Strain recovery rate is 85% or more × (bad): Strain recovery rate is less than 85%

[0117] [Table 1]

[0118] The evaluation samples formed from the adhesive compositions of Examples 1 to 4, which satisfied the requirements of the present invention, were excellent in deformability and responsiveness. On the other hand, the evaluation sample formed from the adhesive composition of Comparative Example 1, which did not contain component (B), was significantly inferior in recovery. Furthermore, the evaluation sample formed from the adhesive composition of Comparative Example 2, which did not contain component (C), was inferior in both deformability and recovery. [Industrial Applicability]

[0119] The pressure-sensitive adhesive composition and pressure-sensitive adhesive sheet of the present invention are useful for producing flexible electronic devices.

Claims

1. The following components (A) to (C): (A) an isobutene-based polymer having an epoxy group and a number average molecular weight of 10,000 to 500,000; (B) an isobutene-based polymer having an acid anhydride group and / or a carboxy group and a number average molecular weight of 20,000 to 500,000; (C) an olefin polymer having an acid anhydride group and / or a carboxy group and a number average molecular weight of 300 or more and less than 10,000; and Liquid olefin polymer other than components (A), (B) and (C) An adhesive composition comprising: the total content of the (A) component and the (B) component is 10 to 90 mass% relative to 100 mass% of the nonvolatile content of the adhesive composition; the mass ratio of component (A):component (B) is 5:95 to 95:5; the ratio of "the amount (mol) of epoxy groups in component (A)" to "the total amount (mol) of acid anhydride groups and the amount (mol) of carboxy groups in component (B) and component (C)" is 20:80 to 80:20; and The content of the liquid olefin polymer is 3 to 50 mass % relative to 100 mass % of the nonvolatile content of the adhesive composition. Adhesive composition.

2. 2. The pressure-sensitive adhesive composition according to claim 1, wherein the component (B) is an isobutene-based polymer having an acid anhydride group and a number average molecular weight of 20,000 to 500,000.

3. 3. The pressure-sensitive adhesive composition according to claim 1, wherein the component (C) is an olefin polymer having an acid anhydride group and a number average molecular weight of 300 or more but less than 10,000.

4. The pressure-sensitive adhesive composition according to any one of claims 1 to 3, further comprising a plasticizer.

5. A pressure-sensitive adhesive sheet having a laminated structure comprising a support and a pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition according to any one of claims 1 to 4.

6. A flexible electronic device comprising an adhesive layer formed from the adhesive composition according to any one of claims 1 to 4.

Images