JP2022183747A - Adhesive composition, adhesive sheet and flexible electronic device - Google Patents

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 The present invention relates to an adhesive composition, an adhesive sheet and a flexible electronic device.

Conventionally, glass substrates have mainly been used for electronic devices such as flat panel displays (liquid displays, organic EL displays, electronic paper, etc.) and solar cells. Then, there is a problem that the strength is lowered. For this reason, in recent years, flexible electronic devices (hereinafter sometimes simply referred to as "flexible devices") in which glass substrates are replaced with flexible substrates that are flexible and bendable have been actively developed. Moreover, an adhesive sheet having an adhesive layer may be used for interlayer adhesion of flexible devices, and in that case, the flexible device has an adhesive layer.

The members of the flexible device may be damaged or peeled off due to the stress applied during bending. In order to prevent such damage or peeling, the adhesive layer in the flexible device is required to have excellent deformation performance due to stress (which may be referred to herein as "deformability").

It is also required that the members of the flexible device return to their original shape after the stress is removed. Therefore, the adhesive layer in the flexible device is required to have excellent performance (which may be referred to herein as “recoverability”) to restore the deformed shape to its original shape after the stress is removed. .

For example, U.S. Pat. No. 6,200,009 discloses assembly layers for flexible devices to prevent defects and delamination. The assembly layer comprises an adhesive composition and is characterized by having a specific shear storage modulus, a specific shear creep compliance, and a specific strain recovery.

Japanese Patent Publication No. 2018-526469

An object of the present invention is to provide an adhesive composition capable of forming an adhesive layer with excellent deformability and recoverability.

The present invention capable of achieving the above objects 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 carboxy group and having a number average molecular weight of 10,000 or more, and (C) having an acid anhydride group and/or a carboxy group, and An adhesive composition containing an olefinic polymer having a number average molecular weight of less than 10,000.
[2] The pressure-sensitive adhesive composition according to [1] above, wherein the component (B) is an isobutene 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] above, wherein component (C) is an olefin polymer having an acid anhydride group and a number average molecular weight of less than 10,000.
[4] The pressure-sensitive adhesive composition according to any one of [1] to [3], wherein the component (B) has a number average molecular weight of 20,000 to 500,000.
[5] The pressure-sensitive adhesive composition according to any one of [1] to [4], wherein the component (C) has a number average molecular weight of 300 or more and less than 10,000.
[6] The adhesive composition according to any one of [1] to [5], further comprising a liquid olefin polymer other than components (A), (B) and (C).
[7] The pressure-sensitive 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 [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].

ADVANTAGE OF THE INVENTION According to this invention, the adhesive composition which can form the adhesive layer excellent in deformability and recoverability can be obtained.

Adhesive composition The adhesive composition of the present invention is characterized by containing 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 carboxy group and having a number average molecular weight of 10,000 or more, and (C) having an acid anhydride group and/or a carboxy group, and An olefinic polymer having a number average molecular weight of less than 10,000.

Components (A) to (C) may be used singly or in combination of two or more. Components (A) to (C) will be described in order below.

<(A) Component>
Component (A) used in the present invention is an isobutene polymer having an epoxy group. In the present specification, the term "isobutene-based polymer" means that structural units derived from isobutene (hereinafter sometimes abbreviated as "isobutene units") are the main structural units (i.e., the amount of isobutene units is is the largest) polymer. In the following, like the structural unit derived from isobutene, the "structural unit derived from olefin" and the like may be abbreviated as "olefin unit" and the like.

The isobutene-based polymer may be an isobutene homopolymer or a copolymer of isobutene and a monomer other than isobutene. The copolymer may be a random copolymer or a block copolymer.

The isobutene-based polymer may be an isobutene-based resin (eg, polyisobutene) or an isobutene-based rubber (eg, butyl rubber, ie, isobutene-isoprene copolymer). As used herein, "isobutene-based resin" means an isobutene-based polymer that cannot form a rubber elastic body by cross-linking, and "isobutene-based rubber" means an isobutene-based polymer that can form a rubber elastic body by cross-linking. means.

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

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

Component (A) is, for example, an unsaturated compound having an epoxy group (eg, glycidyl (meth)acrylate, 4-hydroxybutyl acrylate glycidyl ether, allyl glycidyl ether), and an isobutene polymer grafted under radical reaction conditions. It can be obtained by denaturation.

As component (A), for example, polymers available from Seiko PMC Co., Ltd. can be used. The polymers available from Seiko PMC include, for example, "ER850" (glycidyl methacrylate-modified butyl rubber), "ER866" (glycidyl methacrylate-modified butyl rubber), "ER869" (glycidyl methacrylate-2-ethylhexyl acrylate random copolymer-modified butyl rubber). ) and the like.

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

The total content of component (A) and component (B) to be described later is preferably 10% by mass or more, more preferably 10% by mass or more, based on 100% by mass of the non-volatile content of the adhesive composition, from the viewpoint of recoverability of the adhesive layer. It is 20% by mass or more, more preferably 30% by mass or more, and 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 deformability of the adhesive layer.

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

<(B) Component>
The component (B) used in the present invention has an acid anhydride group (that is, a carbonyloxycarbonyl group (--CO--O--CO--)) and/or a carboxy group, and has a number average molecular weight of 10,000 or more. Preferably, it is an isobutene polymer having an acid anhydride group and a number average molecular weight of 10,000 or more. The description of the "isobutene-based polymer" in component (B) is the same as that in component (A).

When an isobutene-based polymer having an acid anhydride group and a number average molecular weight of 10,000 or more is used as the component (B), the concentration of the acid anhydride group in the polymer affects the deformation of the adhesive layer. It is preferably from 0.1 to 5 mmol/g, more preferably from 0.2 to 3 mmol/g, from the viewpoint of resistance and recoverability. The concentration of acid anhydride groups is obtained from the value of acid value defined as mg of potassium hydroxide required to neutralize acid present in 1 g of polymer according to JIS K 2501.

When an isobutene polymer having a carboxy group and a number average molecular weight of 10,000 or more is used as the component (B), the concentration of the carboxy group in the polymer determines the deformability and recoverability of the adhesive layer. from the viewpoint of, it is preferably 0.1 to 5 mmol/g, more preferably 0.2 to 3 mmol/g. The concentration of carboxy groups is obtained from the value of acid value defined as mg of potassium hydroxide required to neutralize acid present in 1 g of polymer according to JIS K 2501.

When an isobutene polymer having an acid anhydride group and a carboxy group and a number average molecular weight of 10,000 or more is used as the component (B), the concentration of the acid anhydride group and 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 deformability and recoverability of the adhesive layer.

The number average molecular weight of component (B) is preferably from 20,000 to 500,000, more preferably from 25,000 to 400,000, still more preferably from 30,000 to 30,000, from the standpoint of deformability and recovery of the adhesive layer. 300,000.

Component (B) can be produced by graft-modifying an isobutene-based polymer with, for example, an unsaturated compound having an acid anhydride group and/or a carboxy group (e.g., maleic anhydride) under radical reaction conditions. can be done.

As component (B), for example, a polymer available from Seiko PMC can be used. Examples of the polymer available from Seiko PMC 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), "ER674" (maleic anhydride-lauryl methacrylate random copolymer-modified butyl rubber), and the like.

In one aspect of the present invention, the component (B) is preferably an isobutene-isoprene copolymer (that is, butyl rubber) having an acid anhydride group and/or a carboxyl 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.

An isobutene-isoprene copolymer (that is, butyl rubber) having an acid anhydride group and/or a carboxy group (preferably an acid anhydride group) and having a number average molecular weight of 10,000 or more is used as component (B). In that case, from the viewpoint of yellowing resistance of the adhesive layer, the amount of isoprene units in the copolymer is preferably 0.1 to 5% by mass, more preferably 0.2, based on the total of isobutene units and isoprene units. ~3% by mass. In addition, the amount of the isoprene unit is a modified portion (for example, a portion derived from maleic anhydride for introducing an acid anhydride group, a portion derived from a maleic anhydride-(meth)acrylate copolymer, etc.). Based on isobutene units and isoprene units excluding .

<(C) Component>
The component (C) used in the present invention has an acid anhydride group (that is, a carbonyloxycarbonyl group (--CO--O--CO--)) and/or a carboxy group, and has a number average molecular weight of less than 10,000. is preferably an olefin polymer having an acid anhydride group and a number average molecular weight of less than 10,000. As used herein, the term "olefin-based polymer" means a polymer in which olefin units are the main structural units (that is, the amount of olefin units is the largest among all structural units).

The olefinic polymer may be an olefinic resin (eg, propylene-butene copolymer) or an olefinic rubber (eg, butyl rubber, ie, isobutene-isoprene copolymer). As used herein, the term "olefinic resin" means an olefinic polymer that cannot form a rubber elastic body by crosslinking, and the term "olefinic rubber" means an olefinic polymer that can form a rubber elastic body by crosslinking. means.

Preferred olefins are monoolefins having one olefinic carbon-carbon double bond and/or diolefins 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, 2,3-dimethylbutadiene and the like.

The olefinic polymer may be a homopolymer or a copolymer. The copolymer may be a random copolymer or a block copolymer. Also, the olefinic polymer may be a copolymer of an olefin and a monomer other than the olefin. Examples of olefinic copolymers include ethylene-nonconjugated diene copolymers, ethylene-propylene copolymers, ethylene-propylene-nonconjugated diene copolymers, ethylene-butene copolymers, and propylene-butene copolymers. , propylene-butene-nonconjugated diene copolymer, isobutene-isoprene copolymer, styrene-isobutene copolymer, styrene-isobutene-styrene copolymer and the like.

When an olefin polymer having an acid anhydride group and a number average molecular weight of less than 10,000 is used as the component (C), the concentration of the acid anhydride group in the polymer affects the deformation of the adhesive layer. It is preferably 0.05 to 3 mmol/g, more preferably 0.1 to 2 mmol/g, from the viewpoints of resistance and recoverability. The concentration of acid anhydride groups is obtained from the value of acid value defined as mg of potassium hydroxide required to neutralize acid present in 1 g of polymer according to JIS K 2501.

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

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

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

Component (C) can be produced by, for example, graft-modifying an olefinic polymer with an unsaturated compound having an acid anhydride group and/or a carboxyl group (e.g., maleic anhydride) under radical reaction conditions. can be done.

As the component (C), polymers available from manufacturers can be used. 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, and " Lucant A-5515” (acid-modified ethylene-α-olefin copolymer), “Lucant A-5260” (acid-modified ethylene-α-olefin copolymer), “Lucant A-5320H” (acid-modified ethylene-α- olefin copolymer) and the like.

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

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, based on 100% by mass of the non-volatile content of the adhesive composition, from the viewpoint of deformability of the adhesive layer. It is at least 70% by mass, 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 recovery of the adhesive layer.

<Amount of component (A) used, and amount of components (B) and (C) used>
The amount of component (A) used and the amount of components (B) and (C) used are preferably determined by the ratio of functional groups possessed by these components. "Amount (mol) of epoxy groups possessed by component (A)": "Total amount (mol) of acid anhydride groups and amounts (mol) of carboxy groups possessed by components (B) and (C)" From the standpoint of recoverability of the adhesive layer, it is preferably 20:80 to 80:20, more preferably 25:75 to 75:25, still more preferably 30:70 to 70:30. In addition, for example, when both the (B) component and the (C) component have only acid anhydride groups, the "total of the amount (mol) of acid anhydride groups and the amount (mol) of carboxy groups" is "acid anhydride means "total amount (mol) of physical groups".

<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") within a range that does not impair the effects of the present invention. . Other components include, for example, liquid olefin polymers, plasticizers, antioxidants, metal complexes, curing agent accelerators, and the like. These may use only 1 type, and may use 2 or more types together. The liquid olefin polymer and the like will be described in order below.

(Liquid olefin polymer)
In the present invention, a liquid olefin polymer other than components (A), (B) and (C) is used in order to impart good adhesion and even better deformability to the adhesive layer. good too. In the present invention, the “liquid” in the “liquid olefin polymer” means that the viscosity at 25° C. is 5,000 Pa·s or less. In the present invention, the "viscosity at 25°C" means the viscosity calculated by multiplying the kinematic viscosity at 25°C measured by a dynamic viscoelasticity measuring device by the density. Examples of the dynamic viscoelasticity measuring device include rheometer (trade name: DISCOVERY HR-2) manufactured by TA Instruments. Descriptions and examples of "olefin" and "olefin polymer" in "liquid olefin polymer" are the same as those of component (C).

Among liquid olefin polymers, liquid isobutene polymers having epoxy groups are classified as component (A) in the present invention. Among the liquid olefin polymers, a liquid isobutene polymer having an acid anhydride group and/or a carboxy group and a number average molecular weight of 10,000 or more is used as the component (B) in the present invention. being classified. Further, 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). .

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

From the viewpoint of adhesion of the adhesive layer, the number average molecular weight of the liquid polyolefin polymer is
It is preferably 100 to 50,000, more preferably 200 to 30,000, still more preferably 300 to 20,000.

Commercially available products can be used as the liquid olefin polymer. Examples of such commercial products include "HV-300" (liquid polybutene) manufactured by ENEOS, "HV-1900" manufactured by ENEOS (liquid polybutene), "HV-50" manufactured by ENEOS (liquid polybutene), and ENEOS. "HV-35" (liquid polybutene) manufactured by Kothari, "950MW" manufactured by Kothari (liquid polybutene), "2400MW" manufactured by Kothari (liquid olefin polymer), "H-1900" manufactured by INEOS (liquid polybutene), INEOS "H-6000" (liquid polybutene), INEOS "H-18000" (liquid polybutene), NOF "200N" (liquid polybutene), Nippon Soda "BI-2000" (hydrogenated polybutadiene), "BI-3000" (hydrogenated polybutadiene) manufactured by Nippon Soda Co., Ltd., "GI-3000" (hydrogenated polybutadiene) manufactured by Nippon Soda Co., Ltd., "Lucant LX100" manufactured by Mitsui Chemicals (liquid olefin polymer), Mitsui Chemical company "Lucant LX400" (liquid olefin polymer), Idemitsu Showa Shell "Poly bd R-45HT" (butadiene liquid rubber), Idemitsu Showa Shell "Poly bd R-15HT" (butadiene liquid Rubber), "Poly ip" (liquid polyisoprene) manufactured by Idemitsu Showa Shell Co., Ltd., "B-1000" manufactured by Nippon Soda Co., Ltd. (liquid polybutadiene), "B-3000" manufactured by Nippon Soda Co., Ltd. (liquid polybutadiene), manufactured by Nippon Soda Co., Ltd. "G-3000" (liquid polybutadiene), Kuraray's "LIR-30" (liquid polyisoprene), Kuraray's "LIR-390" (liquid polyisoprene), Kuraray's "LIR-290" (liquid polyisoprene) ), Kuraray Co., Ltd. “LBR-302” (liquid polybutadiene), Kuraray Co., Ltd. “LBR-305” (liquid polybutadiene), Kuraray Co., Ltd. “LBR-361” (liquid polybutadiene), Kuraray Co., Ltd. “L-SBR-820” (liquid styrene-butadiene random copolymer), CRAY VALLEY's "Ricon 154" (liquid butadiene), and CRAY VALLEY's "RICON 184" (liquid styrene-butadiene random copolymer).

The liquid olefinic polymer is preferably liquid polybutene.
When a liquid olefin polymer is used, its content in the adhesive composition is preferably 3 to 50% by mass with respect to 100% by mass of the non-volatile content of the adhesive composition, from the viewpoint of adhesion of the adhesive layer. More preferably 5 to 40 mass %, still more preferably 10 to 30 mass %.

(Plasticizer)
In the present invention, a plasticizer may be used in order to impart even better deformability to the adhesive layer. Examples of plasticizers include phthalate plasticizers, adipate plasticizers, phosphate ester plasticizers, trimellitate plasticizers, sulfonate plasticizers, petroleum oils, polyol polyesters, Animal oils, vegetable oils, castor oil derivatives, and the like.

Examples of phthalate plasticizers include dioctyl phthalate (DOP) and dibutyl phthalate (DBP). Examples of adipate plasticizers include dioctyl adipate, propylene glycol polyester adipate, and butylene glycol polyester adipate. Examples of phosphate plasticizers include tricresyl phosphate and trioctyl phosphate. Examples of the trimellitate ester plasticizer include trioctyl trimellitate. Examples of sulfonic acid ester plasticizers include alkylsulfonic acid esters.

Examples of petroleum oils include paraffin oil (liquid paraffin), naphthenic oil, and aromatic oil. Examples of polyol polyester include diethylene glycol dibenzoate, pentaerythritol ester, and the like.

Animal oils include, for example, squalane, squalene, and the like. Vegetable oils include, for example, olive oil, camellia oil, castor oil, tall oil, peanut oil, cottonseed oil, rapeseed oil, soybean oil, palm oil, coconut oil and the like.

Castor oil derivatives are commercially available as plasticizers from various manufacturers. Commercial products of castor oil derivatives include, for example, “Hardened castor oil A”, “CO-FA”, “DCO-FA”, “Ricksizer S4”, “Ricksizer C-101”, “Ricksizer C-101” manufactured by Ito Oil Co., Ltd. Ricksizer GR-310", "Ricksizer S-8"; "Brownon BR-410", "Brownon BR-410", "Brownon BR-430", "Brownon BR-450", "Brownon BR-450" manufactured by Aoki Oil Industry Co., Ltd. Braunon CW-10", "Braunon RCW-20", "Braunon RCW-40", "Braunon RCW-50", "Braunon RCW-60"; NOF's "Caster Wax A", "Newsizer 510R" , “Sakura stearic acid”, “castor hardened fatty acid”, “NAA-34”, “NAA-160”, “NAA-175” and the like.

When a plasticizer is used, its content in the adhesive composition is preferably 1 to 40% by mass with respect to 100% by mass of the non-volatile content of the adhesive composition, from the viewpoint of the deformability and adhesion of the adhesive layer. More preferably 3 to 30% by mass, still more preferably 5 to 25% by mass.

(Antioxidant)
In the present invention, the antioxidant is not particularly limited, and known antioxidants can be used. When using an antioxidant, its content is relative to 100% by mass of the non-volatile content of the adhesive composition,
It is preferably 0.05 to 5% by mass, more preferably 0.10 to 4% by mass, still more preferably 0.20 to 3% by mass.

(metal complex)
In the present invention, in order to form an adhesive layer having even better recovery properties, a bidentate ligand whose two coordinating atoms are both oxygen atoms (hereinafter referred to as "oxygen-bidentate ligand" ) and a metal complex in which a monodentate ligand whose coordinating atom is an oxygen atom (hereinafter sometimes referred to as "oxygen-monodentate ligand") is bound to the central metal.

The metal complex preferably has the following formula (1):

[In formula (1),
M represents a metal with a valence of 2 or more,
R ₁ and R ₃ 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,
The solid line between the oxygen atom (O) and M in [ ] in formula (1) 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, m≧n. ]
is a metal complex represented by (hereinafter sometimes abbreviated as "metal complex (1)"). Only one kind of the metal complex (1) may be used, or two or more kinds thereof may be used in combination.

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, more preferably aluminum, titanium or zirconium.

As used herein, the halogen atom includes, for example, a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

As used herein, alkyl groups may be straight-chain or branched. The number of carbon atoms in the alkyl group (excluding the alkyl group in the long-chain alkyl (meth)acrylate) is preferably 1-20, more preferably 1-10, particularly preferably 1-6. Alkyl groups include, for example, methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, sec-butyl group, tert-butyl group, pentyl group, isopentyl group, neopentyl group, 1-ethylpropyl group, Examples include hexyl group, isohexyl group, 1,1-dimethylbutyl group, 2,2-dimethylbutyl group, 3,3-dimethylbutyl group and 2-ethylbutyl group. The alkyl group may have a substituent. Examples of the substituent include a halogen atom, a hydroxy group, an optionally substituted amino group, and the like.

As used herein, alkenyl groups can be straight or branched. The alkenyl group preferably has 2 to 20 carbon atoms. Examples of alkenyl groups include ethenyl group (that is, vinyl group), 1-propenyl group, 2-propenyl group, 2-methyl-1-propenyl group, 1-butenyl group, 2-butenyl group, 3-butenyl group, 3-methyl-2-butenyl group, 1-pentenyl group, 2-pentenyl group, 3-pentenyl group, 4-pentenyl group, 4-methyl-3-pentenyl group, 1-hexenyl group, 3-hexenyl group, 5- A hexenyl group and the like can be mentioned. The alkenyl group may have a substituent. Examples of the substituent include a halogen atom, a hydroxy group, an optionally substituted amino group, and the like.

As used herein, alkynyl groups may be straight or branched. The number of carbon atoms in the alkynyl group is preferably 2-10, more preferably 2-6. Examples of alkynyl groups include ethynyl, 1-propynyl, 2-propynyl, 1-butynyl, 2-butynyl, 3-butynyl, 1-pentynyl, 2-pentynyl, 3-pentynyl groups, 4-pentynyl group, 1-hexynyl group, 2-hexynyl group, 3-hexynyl group, 4-hexynyl group, 5-hexynyl group, 4-methyl-2-pentynyl group and the like. The alkynyl group may have a substituent. Examples of the substituent include a halogen atom, a hydroxy group, an optionally substituted amino group, and the like.

In the present specification, the aryl group preferably has 6 to 18 carbon atoms, more preferably 6 to 14 carbon atoms. Examples of aryl groups include phenyl, 1-naphthyl, 2-naphthyl, 1-anthryl, 2-anthryl and 9-anthryl groups. The aryl group may have a substituent. Examples of the substituent include a halogen atom, a hydroxy group, an optionally substituted alkyl group, an optionally substituted alkenyl group, an optionally substituted alkynyl group, An amino group optionally having a substituent and the like can be mentioned.

In the present specification, the aralkyl group preferably has 7 to 16 carbon atoms. Examples of aralkyl groups include benzyl, phenethyl, naphthylmethyl, and phenylpropyl groups. The aralkyl group may have a substituent. Examples of the substituent include a halogen atom, a hydroxy group, an optionally substituted amino group, and the like.

In the present specification, the optionally substituted amino group includes, for example, an amino group, a mono- or di-alkylamino group (e.g., methylamino group, dimethylamino group, ethylamino group, diethylamino group, propylamino group, dibutylamino group), mono- or di-cycloalkylamino group (e.g., cyclopropylamino group, cyclohexylamino group), mono- or di-arylamino group (e.g., phenylamino group), mono- or di-aralkylamino groups (eg, benzylamino group, dibenzylamino group), heterocyclic amino groups (eg, pyridylamino group), and the like.

In this specification, the description of the alkyl group in the alkoxy group (that is, the alkyloxy group) is the same as the description of the alkyl group above. The alkoxy group may have a substituent. Examples of the substituent include a halogen atom, a hydroxy group, an optionally substituted amino group, and the like.

In this specification, the description of the alkenyl group in the alkenyloxy group is the same as the description of the alkenyl group above. The alkenyloxy group may have a substituent. Examples of the substituent include a halogen atom, a hydroxy group, an optionally substituted amino group, and the like.

In this specification, the description of the alkyl group in the alkoxycarbonyl group (that is, the alkyloxycarbonyl group) is the same as the description of the alkyl group above. An alkoxycarbonyl group may have a substituent. Examples of the substituent include a halogen atom, a hydroxy group, an optionally substituted amino group, and the like.

Monodentate ligands represented by X in formula (1) include, for example, alkoxide anion (RO ^- ) (wherein R represents an organic group), carboxylate anion (RCOO ^- ) (in the above formula , R represents an organic group), oxo (O), and the like.

Alkoxide anions are represented by RO ⁻ (wherein R represents an organic group). The organic group R can be either an aliphatic group or an aromatic group. Also, 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 1-20, more preferably 6-18, particularly preferably 8-14. Alkoxide anions (RO ⁻ ) include, for example, methoxide, ethoxide, propoxide, isopropoxide, butoxide, isobutoxide, sec-butoxide, tert-butoxide, pentyl oxide, hexyl oxide, phenoxide, 4-methylphenoxide and the like. be done.

A carboxylate anion is represented by RCOO ⁻ (wherein R represents an organic group). The organic group R can be either an aliphatic group or an aromatic group. Also, 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 1-20, more preferably 6-18, particularly preferably 8-14. Carboxylate anions (RCOO ⁻ ) include, for example, 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, Examples include carboxylate anions corresponding to carboxylic acids such as linoleic acid, linolenic acid, arachidonic acid, eicosapentaenoic acid, docosahexaenoic acid, and benzoic acid.

[ ] in formula (1) represents a multidentate ligand. Examples of multidentate ligands include acetylacetone, 3-methyl-2,4-pentanedione, acetylacetaldehyde, and 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, acetoacetate, methyl acetoacetate, ethyl acetoacetate, propyl acetoacetate, salicylic acid, methyl salicylate, malonic acid, dimethyl malonate, diethyl malonate and the like. When coordinated to the central metal, the polydentate ligand has one or more protons removed from it.

Specific examples of metal complexes (1) in which M is aluminum include aluminum diisopropylate monosec-butyrate, aluminum trisec-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-butyrate, aluminum Propyl acetoacetate diisopropylate, aluminum n-butyl acetoacetate diisopropylate, aluminum tris(ethylacetoacetate), aluminum mono(acetylacetonate) bis(ethylacetoacetate), aluminum tris(acetylacetonate).

Specific examples of the metal complex (1) in which M is titanium include tetraisopropyl titanate, tetra-normal-butyl titanate, tetraoctyl titanate, tetra-tert-butyl titanate, tetrastearyl titanate, titanium tetraacetylacetonate, and titanium octylene glycolate. (alias: bis(2-ethylhexyloxy)bis(2-ethyl-3-oxohexyloxy)titanium (IV)), titanium diisopropoxide bis(ethylacetoacetate), allylacetoacetate triisopropoxide, titanium diisopropoxide n-butoxide bis(2,4-pentanedionate), titanium diisopropoxide bis(tetramethylheptanedionate), titanium diisopropoxide bis(ethylacetoacetate), titanium (IV) tetra(methylphenolate), Titanium oxide bis(2,4-pentanedionate), monoisopropoxytitanium triisostearate, diisopropoxytitanium diisostearate.

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-butoxy zirconium monooctylate, tri-butoxy zirconium monostearate.

When using a metal complex, its content in the adhesive composition is preferably 0.5 to 20% by mass, based on 100% by mass of the non-volatile content of the adhesive composition, from the viewpoint of recoverability of the adhesive layer. It is preferably 1.0 to 15% by mass, more preferably 1.5 to 10% by mass.

(Curing accelerator)
In the present invention, a curing accelerator may be used to promote the cross-linking reaction between the epoxy groups of component (A) and the acid anhydride groups and/or carboxy groups of components (B) and (C). good. Examples of curing accelerators include imidazole compounds, tertiary/quaternary amine compounds, dimethylurea compounds, and organic phosphine compounds.

Examples of imidazole compounds include 1H-imidazole, 2-methylimidazole, 2-phenyl-4-methylimidazole, 2-ethyl-4-methylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole, 2-un Decylimidazole, 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, 2-phenyl-4-methyl-5-hydroxymethylimidazole and the like. . Specific examples of imidazole compounds include Curazole 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 (both manufactured by Shikoku Kasei Kogyo Co., Ltd.).

The tertiary/quaternary amine compound is not particularly limited, but examples include quaternary ammonium salts such as tetramethylammonium bromide, tetrabutylammonium bromide, and triethylmethylammonium/2-ethylhexanoate; DBU (1, 8-diazabicyclo[5.4.0]undecene-7), DBN (1,5-diazabicyclo[4.3.0]nonene-5), DBU-phenol salt, DBU-octylate, DBU-p-toluene Diazabicyclo compounds such as sulfonates, DBU-formates, DBU-phenol novolac resin salts; benzyldimethylamine, 2-(dimethylaminomethyl)phenol, 2,4,6-tris(dimethylaminomethyl)phenol (TAP), etc. tertiary amines of or salts thereof, aromatic dimethylurea, aliphatic dimethylurea and other dimethylurea compounds;

Examples of dimethylurea compounds include aromatic dimethylurea such as DCMU (3-(3,4-dichlorophenyl)-1,1-dimethylurea) and U-CAT3512T (manufactured by San-Apro); U-CAT3503N (manufactured by San-Apro); ) and other aliphatic dimethylureas. Among them, aromatic dimethylurea is preferably used from the viewpoint of curability.

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, triphenylphosphinetriphenylborane and the like. Specific examples of organic phosphine compounds include TPP, TPP-MK, TPP-K, TTBuP-K, TPP-SCN, and TPP-S (all manufactured by Hokko Chemical Industry Co., Ltd.).

When using a curing accelerator, its content in the adhesive composition is determined by the crosslinking reaction between the epoxy groups of component (A) and the acid anhydride groups and/or carboxy groups of components (B) and (C). In order to promote the non-volatile content of the adhesive composition 100% by mass, preferably 0.01 to 5% by mass, more preferably 0.05 to 4% by mass, more preferably 0.10 to 3% by mass is.

Adhesive Sheet The present invention also provides an adhesive sheet having a laminated structure comprising a support and an adhesive layer formed from the 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 invention may have a laminated structure comprising a support, a pressure-sensitive adhesive layer, and a protective sheet in this order. Another layer (for example, a release layer) may be present between the support and the adhesive layer and between the adhesive layer and the protective sheet.

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; polycarbonates; and the like plastic films. Both the support and the protective sheet may be single-layer films or laminated films.

As the support and protective sheet, for example, a low moisture-permeable film having a barrier layer or a laminated film of a low moisture-permeable film having a barrier layer and another film can be used. Examples of the barrier layer include inorganic films such as silica deposition films, silicon nitride films, and silicon oxide films. The barrier layer may be composed of a plurality of layers of inorganic films (for example, deposited silica films). Moreover, the barrier layer may be composed of an organic substance and an inorganic substance, or may be a composite multilayer of an organic layer and an inorganic film.

In the protective sheet, it is preferable that the surface in contact with the adhesive layer is subjected to release treatment. On the other hand, the support may or may not be subjected to release treatment. Examples of the mold release treatment include mold release treatment using a mold release agent such as a silicone resin mold release agent, an alkyd resin mold release agent, and a fluororesin mold release agent.

The thicknesses of the support and the protective sheet are not particularly limited, but are preferably 10 to 150 μm, more preferably 20 to 100 μm, respectively, from the standpoint of handleability of the pressure-sensitive adhesive sheet. When the support and the protective sheet are laminated films, the thickness is the thickness of the laminated film. On the other hand, the thickness of the adhesive layer is preferably 5 to 200 μm, more preferably 10 to 150 μm, still more preferably 20 to 100 μm, from the viewpoint of adhesion and stress relaxation during bending.

Production of Adhesive Composition and Adhesive Sheet The adhesive composition of the present invention can be produced by mixing the components described above using known equipment.

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

Examples of organic solvents that can be used for the preparation of varnishes include ketones such as acetone, methyl ethyl ketone and cyclohexanone; acetic acid esters such as ethyl acetate, butyl acetate, cellosolve acetate, propylene glycol monomethyl ether acetate and carbitol acetate; carbitols such as butyl carbitol; aromatic hydrocarbons such as toluene and xylene; amides of dimethylformamide, dimethylacetamide and N-methylpyrrolidone; Only one kind of organic solvent may be used, or two or more kinds thereof may be used in combination. You may use a commercial item as an organic solvent. Examples of commercially available products include "Swazol" manufactured by Maruzen Petrochemical Co., Ltd., and "Ipsol" manufactured by Idemitsu Kosan Co., Ltd. Application of the varnish may be performed by a known method (for example, a method using a die coater), and the application method is not particularly limited.

In order to promote the reaction between the epoxy groups of component (A) and the acid anhydride groups and/or carboxy groups of components (B) and (C), the organic solvent is removed by heating the coating film. preferably. 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.

Uses of Adhesive Composition and Adhesive Sheet The adhesive composition and 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 optical transparent pressure-sensitive adhesive sheet (OCA) and the like.

Flexible Electronic Device 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 the pressure-sensitive adhesive sheet of the present invention using the pressure-sensitive adhesive composition of the present invention, and (ii) using the pressure-sensitive adhesive sheet of the present invention to form an adhesive layer in the flexible electronic device. (for example, by laminating the adhesive sheet of the present invention on a substrate of a flexible electronic device to form an adhesive layer). In addition, the flexible electronic device of the present invention uses the pressure-sensitive adhesive sheet of the present invention for interlayer adhesion of a plurality of materials (for example, touch panel sensors, polarizing plates, surface protection sheets, etc.), and any material (layer). It can be manufactured through a step of forming an adhesive layer from the adhesive sheet of the present invention and further laminating another arbitrary material (layer) thereon.

Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited by the following examples, and can be modified appropriately within the scope of the above and the following. It is also possible to implement it, and all of them are included in the technical scope of the present invention. "Parts" and "%" in the amount of components and the amount of copolymer units mean "parts by mass" and "% by mass", respectively, unless otherwise specified.

<Ingredients>
Components used in Examples and Comparative Examples are shown below.
(1) Component (A) “ER866” (manufactured by Seiko PMC, 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" (manufactured by Seiko PMC, 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: 98.9%/1.1%)

(2) Component (B) "ER661" (manufactured by Seiko PMC, 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: 98.9%/1.1%)
"ER669" (manufactured by Seiko PMC, 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%)

(3) Component (C) “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" (manufactured by Seiko PMC, maleic anhydride-modified liquid polybutene, acid anhydride group concentration: 0.29 mmol/g, number average molecular weight: 2,100)

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

(5) Plasticizer "Ricksizer S-8" (manufactured by Ito Oil Co., Ltd., castor oil derivative)

(6) Antioxidant "Irganox 1010" (manufactured by BASF, hindered phenolic antioxidant)
"Irgafos 168" (manufactured by BASF, phosphorus antioxidant)

(7) Metal complex “Preneact AL-M” (manufactured by Ajinomoto Fine-Techno Co., Ltd., aluminum octadecenylacetoacetate diisopropylate)

(8) Curing agent accelerator "U CAT-18X" (manufactured by San-Apro Co., Ltd., triethylmethylammonium 2-ethylhexane salt)

<Example 1>
Varnishes having the compounding ratios shown in the table below were prepared by the following procedure, and pressure-sensitive adhesive sheets were prepared using the obtained varnishes. The amount (parts) of each component used in the table below indicates the amount of non-volatile matter of each component in the varnish.

Specifically, glycidyl methacrylate-modified butyl rubber (“ER866” manufactured by Seiko PMC), maleic anhydride-butyl methacrylate random copolymer modified butyl rubber (“ER661” manufactured by Seiko PMC), maleic anhydride-modified liquid polybutene (Toho Chemical Kogyo Co., Ltd., “HV-300M”), liquid polybutene (ENEOS, “HV-1900”), plasticizer (Ito Oil Co., Ltd., “Ricksizer S-8”), metal complex (Ajinomoto Fine Techno Co., Ltd., “Plenact AL-M"), hindered phenol antioxidant (BASF "Irganox 1010"), phosphorus antioxidant (BASF "Irgafos 168"), curing accelerator (San-Apro "U CAT-18X ), and toluene, 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 applied onto the release-treated surface of a polyethylene terephthalate (PET) film (“SP3000” manufactured by Toyo Cloth Co., Ltd., PET film thickness: 38 μm) treated with a silicone release agent, using a die coater. It was applied uniformly and heated at 130° C. for 30 minutes to obtain an adhesive sheet having an adhesive layer with a thickness of 50 μm.

<Example 2>
Glycidyl methacrylate-modified butyl rubber (manufactured by Seiko PMC Co., Ltd., instead of "ER866", glycidyl methacrylate-2-ethylhexyl acrylate random copolymer-modified butyl rubber ("ER869" manufactured by Seiko PMC Co., Ltd.) is used as component (A), and (B ) component maleic anhydride-2-ethylhexyl acrylate random copolymer modified butyl rubber ("ER669" manufactured by Seiko PMC) instead of maleic anhydride-butyl methacrylate random copolymer modified butyl rubber ("ER661" manufactured by Seiko PMC). A pressure-sensitive adhesive sheet having a varnish of the pressure-sensitive adhesive composition and a pressure-sensitive adhesive layer with a thickness of 50 μm was produced in the same manner as in Example 1 except that the was used.

<Example 3>
Maleic anhydride-modified liquid polybutene (“ER688” manufactured by Seiko PMC) is used instead of maleic anhydride-modified liquid polybutene (“HV-300M” manufactured by Toho Chemical Industry Co., Ltd.) as component (C), and component (A). A pressure-sensitive adhesive sheet having a varnish of the pressure-sensitive adhesive composition and a pressure-sensitive adhesive layer with a thickness of 50 μm was prepared in the same manner as in Example 1, except that the amount of the component (B) used was changed.

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

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

<Evaluation of deformability and recovery>
The pressure-sensitive adhesive sheet thus obtained was folded, and the folded pressure-sensitive adhesive sheet was punched out with a belt punch having a diameter of 8 mm. An evaluation sample was prepared.

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

The deformability of the evaluation samples was evaluated according to the following criteria. Table 1 shows the results.
(Deformability standard)
○ (good): shear strain S1 is 5.0 or more × (poor): shear strain S1 is less than 5.0

From shear strain S1 and shear strain S2, the following formula:
Strain recovery rate (%) = 100 × (S1-S2) / S1
By calculating the strain recovery rate, the recoverability of the evaluation sample was evaluated according to the following criteria. Table 1 shows the results.
(Criteria for recoverability)
○ (good): strain recovery rate is 85% or more × (poor): strain recovery rate is less than 85%

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 the component (B), was significantly inferior in recoverability. In addition, the evaluation sample formed from the adhesive composition of Comparative Example 2, which did not contain component (C), was inferior in both deformability and recoverability.

The adhesive composition and adhesive sheet of the present invention are useful for producing flexible electronic devices.

Claims (9)

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 carboxy group and having a number average molecular weight of 10,000 or more, and (C) having an acid anhydride group and/or a carboxy group, and An adhesive composition containing an olefinic polymer having a number average molecular weight of less than 10,000. 2. The adhesive composition according to claim 1, wherein component (B) is an isobutene polymer having an acid anhydride group and a number average molecular weight of 10,000 or more. 3. The adhesive composition according to claim 1, wherein 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 claims 1 to 3, wherein the component (B) has a number average molecular weight of 20,000 to 500,000. 5. The adhesive composition according to any one of claims 1 to 4, wherein the component (C) has a number average molecular weight of 300 or more and less than 10,000. The adhesive composition according to any one of claims 1 to 5, further comprising a liquid olefin polymer other than components (A), (B) and (C). The adhesive composition according to any one of claims 1 to 6, further comprising a plasticizer. 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 7. A flexible electronic device comprising an adhesive layer formed from the adhesive composition according to any one of claims 1-7.