CN118043425A - Pressure-sensitive adhesive composition, pressure-sensitive adhesive sheet, and joined body - Google Patents

Abstract

The purpose of the present invention is to provide an adhesive composition capable of forming an adhesive layer that firmly bonds members when no voltage is applied and that sufficiently reduces the adhesion due to the application of voltage, and an adhesive sheet and a joined body that are provided with an adhesive layer formed from the adhesive composition. The present invention relates to an adhesive composition comprising a polymer, an ionic liquid and a tackifier, wherein the product of the acid value [ mgKOH/g ] of the tackifier and the content [ parts by mass ] of the tackifier relative to 100 parts by mass of the polymer is less than 1200, and an adhesive sheet and a joined body each comprising an adhesive layer formed from the adhesive composition.

Description

Pressure-sensitive adhesive composition, pressure-sensitive adhesive sheet, and joined body

Technical Field

The present invention relates to an adhesive composition, an adhesive sheet including an adhesive layer formed from the adhesive composition, and a bonded body of the adhesive sheet and an adherend.

Background

In an electronic component manufacturing process and the like, demands for reworking (reworking) for improving yield, recycling in which components are decomposed and recovered after use, and the like are increasing. In order to meet such a demand, a double-sided pressure-sensitive adhesive sheet having a predetermined adhesive force and a predetermined peelability is sometimes used for joining members in an electronic component manufacturing process or the like.

As the double-sided pressure-sensitive adhesive sheet for realizing the above-mentioned adhesion and releasability, a pressure-sensitive adhesive sheet (electric release pressure-sensitive adhesive sheet) which is released by applying a voltage to a pressure-sensitive adhesive layer is known (patent documents 1 to 3).

The following means are described for the electrically-releasable pressure-sensitive adhesive sheet of patent document 3: an ionic liquid containing cations and anions is used as a component for forming the adhesive composition, and when a voltage is applied, the cations of the ionic liquid move to the cathode side and are located near the interface between the adhesive layer and the adherend, and thus the adhesive force at the adhesive interface becomes weak, and the peeling becomes easy.

Patent documents 1 to 3 disclose the following means: in order to improve the adhesion when no voltage is applied, an adhesive agent may be contained as an additive in the adhesive layer forming the adhesive sheet.

Prior art literature

Patent literature

Patent document 1: japanese patent No. 6152288

Patent document 2: japanese patent No. 6097112

Patent document 3: japanese patent laid-open No. 2020-164778

Disclosure of Invention

Problems to be solved by the invention

The electrically-peelable pressure-sensitive adhesive sheet preferably has a structure in which members are firmly bonded when no voltage is applied and can be peeled off with a small force when a voltage is applied.

However, as a result of the study by the inventors of the present application, the following new problems were found: in the prior art, although the bonding force when no voltage is applied is improved by the addition of the adhesion promoter, peelability when voltage is applied may be deteriorated.

The present invention has been made in view of the above-described circumstances, and an object thereof is to provide an adhesive composition capable of forming an adhesive layer which firmly bonds members when no voltage is applied and in which the adhesive force is sufficiently reduced by the application of the voltage, and an adhesive sheet comprising the adhesive layer formed from the adhesive composition.

Means for solving the problems

As a result of intensive studies, the inventors of the present application have found that the above problems can be solved by setting the product of the acid value [ mgKOH/g ] of the tackifier and the content [ parts by mass ] of the tackifier relative to 100 parts by mass of the polymer within a specific range, and have completed the present application.

Namely, the present invention is as follows.

〔1〕

An adhesive composition comprising a polymer, an ionic liquid and an adhesion promoter,

The product of the acid value [ mgKOH/g ] of the tackifier and the content [ parts by mass ] of the tackifier per 100 parts by mass of the polymer is less than 1200.

〔2〕

The adhesive composition according to [ 1 ], wherein the softening point of the tackifier is 100℃or higher.

〔3〕

The adhesive composition according to [1], wherein the content of the tackifier is 5 to 50 parts by mass relative to 100 parts by mass of the polymer.

〔4〕

The adhesive composition according to [1], wherein the tackifier is a terpene-based tackifying resin or a rosin-based tackifying resin.

〔5〕

The adhesive composition according to [ 1], wherein the anion of the ionic liquid contains at least 1 selected from the group consisting of bis (fluorosulfonyl) imide anion and bis (trifluoromethanesulfonyl) imide anion.

〔6〕

The adhesive composition according to [1 ], wherein the polymer comprises at least 1 selected from the group consisting of a polyester-based polymer, a urethane-based polymer and an acrylic-based polymer.

〔7〕

The adhesive composition according to [1], further comprising a2 nd polymer having a glass transition temperature (Tg) of 40 to 180 ℃.

〔8〕

The adhesive composition according to [ 7 ], wherein the content of the 2 nd polymer is 1 to 50 parts by mass based on 100 parts by mass of the polymer.

〔9〕

The adhesive composition according to [ 1], which is used for electric peeling.

〔10〕

An adhesive sheet comprising an adhesive layer formed of the adhesive composition according to any one of [ 1] to [ 9 ].

〔11〕

A joined body comprising the adhesive sheet according to [ 10 ] and a conductive material,

The adhesive layer is adhered to the conductive material.

Effects of the invention

According to the present invention, an adhesive composition capable of forming an adhesive layer that firmly bonds members when no voltage is applied and that sufficiently reduces adhesion due to application of voltage, and an adhesive sheet and a joined body each having an adhesive layer formed of the adhesive composition can be provided.

Drawings

Fig. 1 is a cross-sectional view showing an example of an adhesive sheet of the present invention.

Fig. 2 is a cross-sectional view showing an example of a laminated structure of the adhesive sheet of the present invention.

Fig. 3 is a cross-sectional view showing another example of the laminated structure of the adhesive sheet of the present invention.

Fig. 4 is a cross-sectional view showing an outline of a method of 180 ° peel test in the example.

Detailed Description

Hereinafter, specific embodiments of the present invention will be described in detail. The present invention is not limited to the embodiments described below.

[ Adhesive composition ]

The adhesive composition according to an embodiment of the present invention contains a polymer, an ionic liquid, and a tackifier, and the product of the acid value [ mgKOH/g ] of the tackifier and the content [ parts by mass ] of the tackifier relative to 100 parts by mass of the polymer is less than 1200.

The inventors of the present application have found that, when an acid value of an acid-forming agent [ mgKOH/g ] and a content of the acid-forming agent [ parts by mass ] per 100 parts by mass of a polymer are added to an adhesive composition comprising a polymer and an ionic liquid so that the product becomes 1200 or more, the adhesive strength when no voltage is applied increases, but the decrease in adhesive strength due to voltage application becomes insufficient. This is presumed to be due to two reasons: (i) The compatibility of the polymer with the tackifier is poor, dispersibility of the tackifier in the adhesive layer formed from the adhesive composition is poor, and precipitation of the tackifier, phase separation of the adhesive layer and the like occur; and (ii) the acid value-containing thickener has a function of capturing the ionic liquid, and by virtue of this function, the movement of cations of the ionic liquid to the cathode side is prevented and the bias thereof to the vicinity of the interface between the pressure-sensitive adhesive layer and the adherend is prevented.

In the pressure-sensitive adhesive composition according to the embodiment of the present invention, the product of the acid value [ mgKOH/g ] of the tackifier and the content [ parts by mass ] of the tackifier relative to 100 parts by mass of the polymer is made to be less than 1200. This can improve the dispersion state of the adhesion promoter in the adhesive layer, and can suppress the trapping of the adhesion promoter in the ionic liquid, thereby achieving both an improvement in adhesion force when no voltage is applied and a sufficient reduction in adhesion force due to the application of voltage. The adhesive composition is suitable as an adhesive composition for electric peeling.

Hereinafter, the adhesive composition will be described.

In the present specification, the adhesive force when no voltage is applied may be referred to as "initial adhesive force".

In addition, the property that the adhesive force is reduced by the voltage application may be referred to as "electrical peelability", and the case where the rate of reduction in the adhesive force by the voltage application is large may be referred to as "electrical peelability excellent", or the like.

< Ingredients of adhesive composition >

(Polymer)

The adhesive composition according to the embodiment of the present invention contains a polymer. In the embodiment of the present invention, the polymer is not particularly limited as long as it is a general organic polymer compound, and is, for example, a polymer of a monomer or a partial polymer. The monomer may be 1 monomer or a mixture of 2 or more monomers. The term "partial polymer" refers to a polymer in which at least a part of a monomer or a mixture of monomers is partially polymerized.

The polymer in the embodiment of the present invention is not particularly limited as long as it is a polymer that is generally used as a binder and has adhesiveness, and examples thereof include acrylic polymers, rubber polymers, vinyl alkyl ether polymers, silicone polymers, polyester polymers, polyamide polymers, urethane polymers, fluorine polymers, and epoxy polymers.

The above polymers may be used alone or in combination of 2 or more.

The polymer in the embodiment of the present invention preferably contains at least 1 selected from the group consisting of polyester-based polymer, urethane-based polymer and acrylic-based polymer.

The acrylic polymer preferably has carboxyl, alkoxy, hydroxyl and/or amide bonds.

Since the polyester polymer and the urethane polymer have a hydroxyl group which is easily polarized at the terminal and the carboxyl group, the alkoxy group, the hydroxyl group, and/or the amide bond of the acrylic polymer having a carboxyl group, an alkoxy group, a hydroxyl group, and/or an amide bond are easily polarized, an adhesive layer exhibiting excellent adhesion when no voltage is applied can be obtained by using these polymers.

The content of the polyester polymer, the urethane polymer, and the acrylic polymer in all the polymers contained in the adhesive composition according to the embodiment of the present invention is preferably 60 mass% or more, more preferably 80 mass% or more.

In addition, in particular, in order to reduce cost, improve productivity, and increase initial adhesion, the polymer in the embodiment of the present invention is preferably an acrylic polymer, more preferably an acrylic polymer having a carboxyl group, an alkoxy group, a hydroxyl group, and/or an amide bond.

That is, the adhesive composition according to the embodiment of the present invention is preferably an acrylic adhesive composition containing an acrylic polymer as a polymer.

The acrylic polymer preferably contains a monomer unit derived from an alkyl (meth) acrylate having an alkyl group having 1 to 14 carbon atoms (formula (1) below). Such monomer units are suitable for obtaining a large initial adhesion. In order to improve the adhesion and electrical peelability of the resulting pressure-sensitive adhesive layer when no voltage is applied, the carbon number of the alkyl group R ^b in the following formula (1) is preferably small, particularly preferably 8 or less, and more preferably 4 or less.

CH₂＝C(R^a)COOR^b (1)

[ R ^a in formula (1) is a hydrogen atom or a methyl group, and R ^b is an alkyl group having 1 to 14 carbon atoms ]

Examples of the alkyl (meth) acrylate having an alkyl group having 1 to 14 carbon atoms include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, sec-butyl (meth) acrylate, 1, 3-dimethylbutyl (meth) acrylate, pentyl (meth) acrylate, isopentyl (meth) acrylate, hexyl (meth) acrylate, 2-ethylbutyl (meth) acrylate, heptyl (meth) acrylate, n-octyl (meth) acrylate, isooctyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-nonyl (meth) acrylate, isononyl (meth) acrylate, n-decyl (meth) acrylate, isodecyl (meth) acrylate, n-dodecyl (meth) acrylate, n-tridecyl (meth) acrylate, and n-tetradecyl (meth) acrylate. Among them, n-butyl acrylate, 2-ethylhexyl acrylate and isononyl acrylate are preferable. The alkyl (meth) acrylate having an alkyl group having 1 to 14 carbon atoms may be used alone or in combination of 2 or more.

The proportion of the alkyl (meth) acrylate having an alkyl group having 1 to 14 carbon atoms to the total monomer components (100 mass%) constituting the acrylic polymer is not particularly limited, but is preferably 70 mass% or more, more preferably 80 mass% or more, and still more preferably 85 mass% or more. When the proportion of the alkyl (meth) acrylate having an alkyl group having 1 to 14 carbon atoms is 70 mass% or more, a large initial adhesion is easily obtained.

The acrylic polymer preferably contains, for the purpose of modifying the cohesive force, heat resistance, crosslinking property, and the like, a monomer unit derived from a polar group-containing monomer copolymerizable with the monomer unit in addition to a monomer unit derived from a (meth) acrylic acid alkyl ester having an alkyl group having 1 to 14 carbon atoms. The monomer units may impart cross-linking points suitable for obtaining a large initial adhesion. In addition, from the viewpoint of improving the adhesion and the electrical peelability when no voltage is applied, it is also preferable to include a monomer unit derived from a polar group-containing monomer.

Examples of the polar group-containing monomer include carboxyl group-containing monomers, alkoxy group-containing monomers, hydroxyl group-containing monomers, cyano group-containing monomers, vinyl group-containing monomers, aromatic vinyl monomers, amide group-containing monomers, imide group-containing monomers, amino group-containing monomers, epoxy group-containing monomers, vinyl ether monomers, N-acryloylmorpholine, sulfo group-containing monomers, phosphoric acid group-containing monomers, and anhydride group-containing monomers. Among them, carboxyl group-containing monomers, alkoxy group-containing monomers, hydroxyl group-containing monomers, and amide group-containing monomers are preferable, and carboxyl group-containing monomers are particularly preferable, from the viewpoint of excellent flocculation property. Carboxyl group-containing monomers are particularly suitable for obtaining a large initial adhesion. The polar group-containing monomer may be used alone or in combination of 2 or more.

Examples of the carboxyl group-containing monomer include acrylic acid, methacrylic acid, carboxyethyl (meth) acrylate, carboxypentyl (meth) acrylate, itaconic acid, maleic acid, fumaric acid, crotonic acid, and isocrotonic acid. Acrylic acid is particularly preferred. The carboxyl group-containing monomers may be used alone or in combination of 2 or more.

Examples of the alkoxy group-containing monomer include methoxy group-containing monomers and ethoxy group-containing monomers. Examples of the methoxy group-containing monomer include 2-methoxyethyl acrylate.

Examples of the hydroxyl group-containing monomer include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, 8-hydroxyoctyl (meth) acrylate, 10-hydroxydecyl (meth) acrylate, 12-hydroxylauryl (meth) acrylate, 4-hydroxymethylcyclohexyl) methyl (meth) acrylate, N-methylol (meth) acrylamide, vinyl alcohol, allyl alcohol, 2-hydroxyethyl vinyl ether, 4-hydroxybutyl vinyl ether, and diethylene glycol monovinyl ether. 2-hydroxyethyl (meth) acrylate and 4-hydroxybutyl (meth) acrylate are particularly preferred. The hydroxyl group-containing monomers may be used singly or in combination of 2 or more.

Examples of the amide group-containing monomer include acrylamide, methacrylamide, N-vinylpyrrolidone, N-dimethylacrylamide, N-dimethylmethacrylamide, N-diethylacrylamide, N, N-diethyl methacrylamide, N' -methylenebisacrylamide, N-dimethylaminopropyl acrylamide, N-dimethylaminopropyl methacrylamide, diacetone acrylamide, and the like. The amide group-containing monomers may be used alone or in combination of 2 or more.

Examples of the cyano group-containing monomer include acrylonitrile and methacrylonitrile.

Examples of the vinyl-containing monomer include vinyl esters such as vinyl acetate, vinyl propionate and vinyl laurate, and vinyl acetate is particularly preferred.

Examples of the aromatic vinyl monomer include styrene, chlorostyrene, chloromethylstyrene, α -methylstyrene, and other substituted styrenes.

Examples of the imide group-containing monomer include cyclohexylmaleimide, isopropylmaleimide, N-cyclohexylmaleimide, and itaconimide.

Examples of the amino group-containing monomer include aminoethyl (meth) acrylate, N-dimethylaminoethyl (meth) acrylate, and N, N-dimethylaminopropyl (meth) acrylate.

Examples of the epoxy group-containing monomer include glycidyl (meth) acrylate, methyl glycidyl (meth) acrylate, and allyl glycidyl ether.

Examples of the vinyl ether monomer include methyl vinyl ether, ethyl vinyl ether, and isobutyl vinyl ether.

The proportion of the polar group-containing monomer to the total monomer components (100 mass%) constituting the acrylic polymer is preferably 0.1 mass% or more and 35 mass% or less. The upper limit of the proportion of the polar group-containing monomer is more preferably 25% by mass, still more preferably 20% by mass, and the lower limit is more preferably 0.5% by mass, still more preferably 1% by mass, and particularly preferably 2% by mass. When the proportion of the polar group-containing monomer is 0.1 mass% or more, the cohesive force is easily obtained, and therefore, the adhesive residue is less likely to occur on the surface of the adherend after the release of the adhesive layer, and the electrical release property is improved. In addition, when the proportion of the polar group-containing monomer is 35 mass% or less, the pressure-sensitive adhesive layer is easily prevented from being excessively adhered to the adherend and being peeled again. In particular, when the content is 2 mass% or more and 20 mass% or less, both of releasability from an adherend and adhesion of the pressure-sensitive adhesive layer to other layers can be easily achieved.

In addition, as the monomer component constituting the acrylic polymer, a polyfunctional monomer may be included in order to easily obtain a necessary cohesive force for introducing a crosslinked structure into the acrylic polymer.

Examples of the polyfunctional monomer include ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate, 1, 6-hexanediol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, dipentaerythritol hexa (meth) acrylate, divinylbenzene, and N, N' -methylenebisacrylamide. The polyfunctional monomer may be used alone or in combination of 2 or more.

The content of the polyfunctional monomer is preferably 0.1 mass% or more and 15 mass% or less with respect to the total monomer components (100 mass%) constituting the acrylic polymer. The upper limit of the content of the polyfunctional monomer is more preferably 10 mass%, and the lower limit is more preferably 3 mass%. When the content of the polyfunctional monomer is 0.1 mass% or more, the flexibility and adhesion of the pressure-sensitive adhesive layer are easily improved, and thus, the pressure-sensitive adhesive layer is preferable. When the content of the polyfunctional monomer is 15 mass% or less, the cohesive force is not excessively increased, and proper adhesion is easily obtained.

Typically, the polyester polymer has a structure in which a polycarboxylic acid such as a dicarboxylic acid or a derivative thereof (hereinafter, also referred to as "polycarboxylic acid monomer") is condensed with a polyhydric alcohol such as a diol or a derivative thereof (hereinafter, referred to as "polyhydric alcohol monomer").

The polycarboxylic acid monomer is not particularly limited, and for example, adipic acid, azelaic acid, dimer acid, sebacic acid, 1, 4-cyclohexanedicarboxylic acid, 1, 3-cyclohexanedicarboxylic acid, 1, 2-cyclohexanedicarboxylic acid, 4-methyl-1, 2-cyclohexanedicarboxylic acid, dodecenylsuccinic anhydride, fumaric acid, succinic acid, dodecanedioic acid, hexahydrophthalic anhydride, tetrahydrophthalic anhydride and the like, maleic acid, maleic anhydride, itaconic acid, citraconic acid, derivatives thereof and the like can be used.

The polycarboxylic acid monomer may be used alone or in combination of 2 or more.

The polyhydric alcohol monomer is not particularly limited, and for example, ethylene glycol, 1, 2-propylene glycol, 1, 3-propylene glycol, 2-methyl-1, 3-propylene glycol, 1, 2-butanediol, 1, 3-butanediol, 1, 4-butanediol, 1, 5-pentanediol, 1, 6-hexanediol, 3-methyl-1, 5-pentanediol, neopentyl glycol, diethylene glycol, dipropylene glycol, 2, 4-trimethyl-1, 5-pentanediol, 2-ethyl-2-butylpropanediol, 1, 9-nonanediol, 2-methyl octanediol, 1, 10-decanediol, derivatives thereof, and the like can be used.

The polyhydric alcohol monomer may be used alone or in combination of 2 or more.

Examples of the urethane polymer include ether-based polyurethane and polyester-based polyurethane.

Examples of the ether-based polyurethane include urethane acrylate resins.

The coating composition for forming a resin film using the urethane acrylate resin can be produced, for example, by the following method: an oligomer obtained by polymerizing a precursor including a polyether segment, a (meth) acrylic segment and a urethane segment under a condition capable of controlling molecular weight is produced, and then various additives are added thereto. It is coated on a support substrate and crosslinked, thereby being obtainable as a urethane acrylate resin film on the support substrate.

More specifically, the coating composition for forming a resin film using the urethane acrylate resin can be produced by: the urethane acrylate oligomer is prepared by polymerizing a polyether polyol, an isocyanate group-containing compound, a hydroxyalkyl (meth) acrylate, an acrylic modified polyether polyol, an isocyanate group-containing compound, and the like in advance, and an additive is added thereto as appropriate. It is coated on a support substrate and crosslinked, thereby being obtainable as a urethane acrylate resin film on the support substrate.

Examples of the polyether polyol include polyalkylene glycols such as polyethylene glycol, polypropylene glycol and polytetramethylene glycol, and various derivatives thereof.

Examples of the ester-based polyurethane include an adipate-based (ester-based) polyurethane and a polycaprolactone-based (ester-based) polyurethane.

In an embodiment of the present invention, the polymer may be obtained by (co) polymerizing monomer components. The polymerization method is not particularly limited, and examples thereof include solution polymerization, emulsion polymerization, bulk polymerization, suspension polymerization, photopolymerization (active energy ray polymerization), and the like. In particular, the solution polymerization method is preferable from the viewpoints of cost and productivity. In the case of copolymerization, the polymer may be any of random copolymer, block copolymer, alternating copolymer, graft copolymer, and the like.

The solution polymerization method is not particularly limited, and the following methods may be mentioned: the monomer component, the polymerization initiator, and the like are dissolved in a solvent, heated, and polymerized to obtain a polymer solution containing a polymer.

As a solvent usable in the solution polymerization method, various general solvents can be used. Examples of such solvents (polymerization solvents) include aromatic hydrocarbons such as toluene, benzene and xylene; esters such as ethyl acetate and n-butyl acetate; aliphatic hydrocarbons such as n-hexane and n-heptane; alicyclic hydrocarbons such as cyclohexane and methylcyclohexane; organic solvents such as ketones, e.g., methyl ethyl ketone and methyl isobutyl ketone. The solvent may be used alone or in combination of 2 or more.

The amount of the solvent to be used is not particularly limited, but is preferably 10 parts by mass or more and 1000 parts by mass or less relative to the total monomer components (100 parts by mass) constituting the polymer. The upper limit of the amount of the solvent to be used is more preferably 500 parts by mass, and the lower limit is more preferably 50 parts by mass.

The polymerization initiator that can be used in the solution polymerization method is not particularly limited, and examples thereof include peroxide-based polymerization initiators, azo-based polymerization initiators, and the like. The peroxide-based polymerization initiator is not particularly limited, and examples thereof include peroxycarbonates, peroxyketones, peroxyketals, hydroperoxides, dialkylperoxides, diacyl peroxides, peroxyesters, and the like, and more specifically, benzoyl peroxide, t-butyl hydroperoxide, di-t-butyl peroxide, t-butyl peroxybenzoate, dicumyl peroxide, 1-bis (t-butylperoxy) -3, 5-trimethylcyclohexane, and 1, 1-bis (t-butylperoxy) cyclododecane, and the like. The azo-based polymerization initiator is not particularly limited, examples thereof include 2,2 '-azobisisobutyronitrile, 2' -azobis-2-methylbutyronitrile, 2 '-azobis (2, 4-dimethylvaleronitrile), dimethyl 2,2' -azobis (2-methylpropionate), 2 '-azobis (4-methoxy-2, 4-dimethylvaleronitrile), 1' -azobis (cyclohexane-1-carbonitrile), 2,2 '-azobis (2, 4-trimethylpentane), 4' -azobis-4-cyanovaleric acid, 2 '-azobis (2-amidinopropane) dihydrochloride, 2' -azobis [2- (5-methyl-2-imidazolin-2-yl) propane ] dihydrochloride, 2 '-azobis (2-methylpropionamidine) disulfate, 2' -azobis (N, N '-dimethylene isobutyl amidine hydrochloride, 2' -azobis [ N- (2-carboxyethyl) -2-methylpropionamidine ] hydrate, and the like. The polymerization initiator may be used alone or in combination of 2 or more.

The amount of the polymerization initiator to be used is not particularly limited, but is preferably 0.01 parts by mass or more and 5 parts by mass or less relative to the total monomer components (100 parts by mass) constituting the polymer. The upper limit of the amount of the polymerization initiator to be used is more preferably 3 parts by mass, and the lower limit is more preferably 0.05 part by mass.

The heating temperature in the polymerization by the solution polymerization method is not particularly limited, and is, for example, 50℃to 80 ℃. The heating time is not particularly limited, and is, for example, 1 hour to 24 hours.

The weight average molecular weight of the polymer is not particularly limited, but is preferably 10 to 500 tens of thousands. The upper limit of the weight average molecular weight is more preferably 400 ten thousand, still more preferably 300 ten thousand, and the lower limit is more preferably 20 ten thousand, still more preferably 30 ten thousand. When the weight average molecular weight is 10 ten thousand or more, the cohesive force becomes small, and the occurrence of a problem such as the occurrence of a residual gum on the surface of the adherend after the release of the pressure-sensitive adhesive layer can be effectively suppressed. In addition, when the weight average molecular weight is 500 ten thousand or less, the problem that the wettability of the surface of the adherend after peeling the pressure-sensitive adhesive layer becomes insufficient can be effectively suppressed.

The weight average molecular weight is obtained by measurement by Gel Permeation Chromatography (GPC), and more specifically, for example, a molecular weight can be calculated from a value converted to standard polystyrene by using a trade name "HLC-8220GPC" (manufactured by TOSOH corporation) as a GPC measurement device, and measuring the molecular weight under the following conditions.

(Conditions for measuring weight average molecular weight)

Sample concentration: 0.2 mass% (tetrahydrofuran solution)

Sample injection amount: 10 mu L

Sample column: TSK protective column SuperHZ-H (1 root) + TSKgel SuperHZM-H (2 roots)

Reference column: TSKgel SuperH-RC (1 root)

Eluent: tetrahydrofuran (THF)

Flow rate: 0.6mL/min

Detector: differential Refractometer (RI)

Column temperature (measurement temperature): 40 DEG C

The glass transition temperature (Tg) of the polymer is not particularly limited, but is preferably-10℃or less, more preferably-20℃or less, since the decrease in initial adhesion can be suppressed. In addition, at-40 ℃ or less, the rate of decrease in adhesion due to voltage application becomes particularly large, so that it is particularly preferable, and most preferably at-50 ℃ or less.

The glass transition temperature (Tg) can be calculated, for example, based on the following formula (Y) (Fox equation).

1/Tg＝W1/Tg1+W2/Tg2+……+Wn/Tgn(Y)

In the formula (Y), tg represents the glass transition temperature (unit: K) of the polymer, tgi (i=1, 2, … … n) represents the glass transition temperature (unit: K) when the monomer i forms a homopolymer, and Wi (i=1, 2, … … n) represents the mass fraction of the monomer i in the whole monomer components

The formula (Y) is a calculation formula when the polymer is composed of n monomer components, namely, monomer 1, monomer 2, … …, and monomer n.

The glass transition temperature when a homopolymer is formed refers to the glass transition temperature of the homopolymer of the monomer, and refers to the glass transition temperature (Tg) of a polymer formed by using only one monomer (sometimes referred to as "monomer X") as a monomer component. Specifically, the values are listed in "Polymer Handbook" (3 rd edition, john Wiley & Sons, inc., 1989). The glass transition temperature (Tg) of the homopolymer not described in this document is a value obtained by, for example, the following measurement method. Specifically, 100 parts by mass of monomer X, 0.2 parts by mass of 2,2' -azobisisobutyronitrile and 200 parts by mass of ethyl acetate as a polymerization solvent were charged into a reactor equipped with a thermometer, a stirrer, a nitrogen inlet pipe and a reflux condenser, and stirred for 1 hour while introducing nitrogen gas. After oxygen in the polymerization system was removed as described above, the temperature was raised to 63℃and the reaction was carried out for 10 hours. Then, the mixture was cooled to room temperature to obtain a homopolymer solution having a solid content concentration of 33% by mass. Subsequently, the homopolymer solution was cast on a release liner, and dried to prepare a test sample (sheet-like homopolymer) having a thickness of about 2 mm. Then, about 1 to 2mg of the test sample was weighed into an open vessel (open cell) made of aluminum, and the reversible heat Flow (REVERSING HEAT Flow) (specific heat component) behavior of the homopolymer was obtained at a temperature rising rate of 5℃per minute under a nitrogen atmosphere of 50ml/min using a temperature-modulated DSC (trade name "Q-2000"TA Instruments,Inc). With reference to JIS-K-7121, the temperature at the point where a straight line equidistant from the low-temperature side base line and the straight line extending the high-temperature side base line of the obtained reversible heat flow in the longitudinal axis direction intersects the curve of the stepwise change portion of the glass transition is taken as the glass transition temperature (Tg) at the time of producing a homopolymer.

The content of the polymer in the adhesive composition according to the embodiment of the present invention is preferably 50 mass% or more and 99.9 mass% or less, more preferably 99.5 mass% or more, further preferably 99 mass% or less, and still more preferably 60 mass% or more, further preferably 70 mass% or less, with respect to the total amount (100 mass%) of the adhesive composition.

(Ionic liquid)

The ionic liquid in the embodiment of the present invention is not particularly limited as long as it is a molten salt (normal temperature molten salt) which is composed of a pair of anions and cations and is liquid at 25 ℃. In the following, examples of anions and cations are given, and of the ionic substances obtained by combining them, the substances that are liquid at 25 ℃ are ionic liquids, and the substances that are solid at 25 ℃ are not ionic liquids, but ionic solids described below.

Examples of anions of the ionic liquid include (FSO₂)₂N^-、(CF₃SO₂)₂N^-、(CF₃CF₂SO₂)₂N^-、(CF₃SO₂)₃C^-、Br^-、AlCl₄ ^-、Al₂Cl₇ ^-、NO₃ ^-、BF₄ ^-、PF₆ ^-、CH₃COO^-、CF₃COO^-、CF₃CF₂CF₂COO^-、CF₃SO₃ ^-、CF₃(CF₂)₃SO₃ ^-、AsF₆ ^-、SbF₆ ^- and F (HF) _n ^-. Among them, the anions are preferably anions of a sulfonimide compound such as (FSO ₂)₂N^- [ bis (fluorosulfonyl) imide anion ], and (CF ₃SO₂)₂N^- [ bis (trifluoromethanesulfonyl) imide anion ]) in terms of chemical stability and suitability for use in improving the electrical releasability, that is, the anions of the ionic liquid preferably contain at least 1 selected from the group consisting of bis (fluorosulfonyl) imide anion and bis (trifluoromethanesulfonyl) imide anion.

From the viewpoint of being chemically stable and suitable for use in making the electric peeling property good, the cations in the ionic liquid are preferably nitrogen-containing onium, sulfur-containing onium and phosphonium-containing cations, and more preferably imidazolium-based, ammonium-based, pyrrolidinium-based and pyridinium-based cations.

Examples of the imidazolium-based cation include 1-methylimidazolium cation, 1-ethyl-3-methylimidazolium cation, 1-propyl-3-methylimidazolium cation, 1-butyl-3-methylimidazolium cation, 1-pentyl-3-methylimidazolium cation, 1-hexyl-3-methylimidazolium cation, 1-heptyl-3-methylimidazolium cation, 1-octyl-3-methylimidazolium cation, 1-nonyl-3-methylimidazolium cation, 1-undecyl-3-methylimidazolium cation, 1-dodecyl-3-methylimidazolium cation, 1-tridecyl-3-methylimidazolium cation, 1-tetradecyl-3-methylimidazolium cation, 1-pentadecyl-3-methylimidazolium cation, 1-hexadecyl-3-methylimidazolium cation, 1-heptadecyl-3-methylimidazolium cation, 1-octadecyl-3-methylimidazolium cation, 1-undecyl-3-methylimidazolium cation, 1-dodecyl-3-methylimidazolium cation, and bis (1, 2-dodecyl-3-methylimidazolium) cation.

Examples of the pyridinium-based cation include 1-butylpyridinium cation, 1-hexylpyridinium cation, 1-butyl-3-methylpyridinium cation, 1-butyl-4-methylpyridinium cation, and 1-octyl-4-methylpyridinium cation.

Examples of the pyrrolidinium cation include 1-ethyl-1-methylpyrrolidinium cation and 1-butyl-1-methylpyrrolidinium cation.

Examples of the ammonium cations include tetraethylammonium cation, tetrabutylammonium cation, methyltrioctylammonium cation, tetradecyltriahexyl ammonium cation, glycidyl trimethylammonium cation, and trimethylaminoethyl acrylate cation.

From the viewpoint of increasing the rate of decrease in the adhesive strength upon application of a voltage, it is preferable to select a cation having a molecular weight of 160 or less as the cation constituting the ionic liquid, and particularly preferable is an ionic liquid containing the above-mentioned (FSO ₂)₂N^- [ bis (fluorosulfonyl) imide anion ] or (CF ₃SO₂)₂N^- [ bis (trifluoromethylsulfonyl) imide anion) ] and a cation having a molecular weight of 160 or less, examples of the cation having a molecular weight of 160 or less include 1-methylimidazolium cation, 1-ethyl-3-methylimidazolium cation, 1-propyl-3-methylimidazolium cation, 1-butyl-3-methylimidazolium cation, 1-pentyl-3-methylimidazolium cation, 1-butylpyridinium cation, 1-butyl-3-methylpyridinium cation, 1-butyl-4-methylpyridinium cation, 1-ethyl-1-methylpyrrolium cation, tetraethylammonium cation, triethylammonium cation, and trimethylammonium glycidate.

In addition, as the cation of the ionic liquid, cations represented by the following formulas (2-A) to (2-D) are also preferable.

[ Chemical formula 1]

R ¹ in the formula (2-A) represents a hydrocarbon group having 4 to 10 carbon atoms (preferably a hydrocarbon group having 4 to 8 carbon atoms, more preferably a hydrocarbon group having 4 to 6 carbon atoms), and may contain a hetero atom, and R ² and R ³ are the same or different and represent a hydrogen atom or a hydrocarbon group having 1 to 12 carbon atoms (preferably a hydrocarbon group having 1 to 8 carbon atoms, more preferably a hydrocarbon group having 2 to 6 carbon atoms, more preferably a hydrocarbon group having 2 to 4 carbon atoms), and may contain a hetero atom. Where the nitrogen atom forms a double bond with an adjacent carbon atom, R ³ is absent.

R ⁴ in the formula (2-B) represents a hydrocarbon group having 2 to 10 carbon atoms (preferably a hydrocarbon group having 2 to 8 carbon atoms, more preferably a hydrocarbon group having 2 to 6 carbon atoms), and may contain a hetero atom, and R ⁵、R⁶ and R ⁷ are the same or different and represent a hydrogen atom or a hydrocarbon group having 1 to 12 carbon atoms (preferably a hydrocarbon group having 1 to 8 carbon atoms, more preferably a hydrocarbon group having 2 to 6 carbon atoms, more preferably a hydrocarbon group having 2 to 4 carbon atoms), and may contain a hetero atom.

R ⁸ in the formula (2-C) represents a hydrocarbon group having 2 to 10 carbon atoms (preferably a hydrocarbon group having 2 to 8 carbon atoms, more preferably a hydrocarbon group having 2 to 6 carbon atoms), and may contain a hetero atom, and R ⁹、R¹⁰ and R ¹¹ are the same or different and represent a hydrogen atom or a hydrocarbon group having 1 to 16 carbon atoms (preferably a hydrocarbon group having 1 to 10 carbon atoms, more preferably a hydrocarbon group having 1 to 8 carbon atoms), and may contain a hetero atom.

X in the formula (2-D) represents a nitrogen, sulfur or phosphorus atom, R ¹²、R¹³、R¹⁴ and R ¹⁵ are the same or different and each represents a hydrocarbon group having 1 to 16 carbon atoms (preferably a hydrocarbon group having 1 to 14 carbon atoms, more preferably a hydrocarbon group having 1 to 10 carbon atoms, still more preferably a hydrocarbon group having 1 to 8 carbon atoms, particularly preferably a hydrocarbon group having 1 to 6 carbon atoms), and may contain a hetero atom. Where X is a sulfur atom, R ¹² is absent.

In an embodiment of the present invention, the cation of the ionic liquid preferably comprises at least 1 selected from the group consisting of a nitrogen-containing onium cation, a sulfur-containing onium cation, and a phosphonium-containing cation.

The molecular weight of the cation in the ionic liquid is, for example, 500 or less, preferably 400 or less, more preferably 300 or less, further preferably 250 or less, particularly preferably 200 or less, and most preferably 160 or less. In addition, it is usually 50 or more. The cations in the ionic liquid are believed to have the following properties: in the adhesive layer, the adhesive layer moves to the cathode side when a voltage is applied, and is concentrated near the interface between the adhesive layer and the adherend. For this reason, in the present invention, the adhesive force during voltage application is lower than the initial adhesive force, and electrical peelability is generated. Such a small-molecular-weight cation having a molecular weight of 500 or less is suitable from the viewpoint of: the movement of cations to the cathode side in the adhesive layer becomes easier, increasing the rate of decrease in adhesive force upon application of a voltage.

Examples of the commercial products of the ionic liquid include "HMI-FSI" manufactured by "ELEXCEL AS-110"、"ELEXCEL MP-442"、"ELEXCEL IL-210"、"ELEXCEL MP-471"、"ELEXCEL MP-456"、"ELEXCEL AS-804"、Mitsubishi Materials Co.,Ltd. of first Industrial pharmaceutical Co., ltd., and "CIL-312" and "CIL-313" manufactured by Japan Carlit Co., ltd.

The ionic conductivity of the ionic liquid is preferably 0.1mS/cm or more. More preferably 1mS/cm or more, still more preferably 3mS/cm or more, still more preferably 5mS/cm or more, still more preferably 10mS/cm or more, particularly preferably 15mS/cm or more, and most preferably 20mS/cm or more. The upper limit is not particularly limited, and by having the ionic conductivity described above, the adhesion force is sufficiently reduced even at a low voltage. The ion conductivity may be measured by an AC impedance method using, for example, a 1260 frequency response analyzer manufactured by Solartron corporation.

The content (amount of the ionic liquid) in the adhesive composition according to the embodiment of the present invention is preferably 0.5 parts by mass or more in terms of reducing the adhesive force during voltage application with respect to 100 parts by mass of the polymer, and preferably 30 parts by mass or less in terms of improving the initial adhesive force. From the same viewpoint, it is more preferably 20 parts by mass or less, still more preferably 15 parts by mass or less, particularly preferably 10 parts by mass or less, and most preferably 5 parts by mass or less. Further, the amount is more preferably 0.6 parts by mass or more, still more preferably 0.8 parts by mass or more, particularly preferably 1.0 parts by mass or more, and most preferably 1.5 parts by mass or more.

(Adhesion promoter)

The adhesion promoter according to the embodiment of the present invention has a product of an acid value [ mgKOH/g ] of the adhesion promoter and a content [ parts by mass ] of the adhesion promoter per 100 parts by mass of the polymer (hereinafter, also simply referred to as a "product of acid value and content") of less than 1200. The product of the acid value and the content is not more than 1200, but the electric releasability tends to be deteriorated with an increase in the amount of carboxylic acid groups contained in the binder, and thus, for example, it is preferably 1000 or less, more preferably 750 or less, still more preferably 500 or less, and most preferably 300 or less. The lower limit is not particularly limited, but may be set to 10 or more from the viewpoint of electrical peelability, for example.

Here, as the value of the acid value, a value obtained by JIS K0070:1992, a value measured by a potentiometric titration method. Specific measurement methods are shown below.

[ Method for measuring acid value ]

1. Reagent(s)

(1) As the solvent, a solvent obtained by mixing and stirring diethyl ether and ethanol at a volume ratio of 4:1 was used.

(2) As the measurement reagent, 0.1mol/L potassium hydroxide ethanol solution was used.

(3) As indicator, phenolphthalein solution was used.

2. Operation of

(1) To the solvent, a few drops of phenolphthalein solution were added, and neutralization was carried out with 0.1mol/L potassium hydroxide ethanol solution.

(2) Approximately 5g of a sample was collected by precise weighing in a beaker, 50mL of the solvent neutralized in 1) above was added thereto, and the mixture was thoroughly stirred and dissolved in a flat-plate heater (80 ℃).

(3) Potential difference titration was performed using 0.1mol/L potassium hydroxide ethanol solution. The inflection point of the obtained titration curve was used as the end point.

3. Calculation of

The acid value was calculated by the following formula.

Acid value (mgKOH/g) = (b×f× 5.611)/S

Here the number of the elements is the number,

B: the amount of 0.1mol/L potassium hydroxide ethanol solution (mL) used for the sample,

F: factor of 0.1mol/L potassium hydroxide ethanol solution,

S: the mass (g) of the sample,

5.611: 1/10 Of the molecular weight of the potassium hydroxide 56.11.

The hydroxyl value of the tackifier is not particularly limited, and may be more than 0mgKOH/g, but is preferably 0mgKOH/g.

The softening point of the tackifier is preferably 100℃or higher, more preferably 120℃or higher, still more preferably 130℃or higher, and most preferably 145℃or higher. By setting the softening point of the adhesive agent to 100 ℃ or higher, the adhesive force when no voltage is applied, that is, the initial adhesive force can be further improved. The softening point is preferably 200℃or less, more preferably 180℃or less, still more preferably 170℃or less, and most preferably 160℃or less. By setting the softening point of the adhesion promoter to 200 ℃ or lower, the dispersibility of the adhesion promoter in the adhesive layer becomes good, precipitation and phase separation of the adhesion promoter are less likely to occur, and movement of the ionic liquid in the adhesive layer at the time of voltage application is less likely to be inhibited.

The softening point of the tackifier is defined herein as a value measured based on the softening point test method (ring and ball method) specified in JIS K5902 and JIS K2207. Specifically, the sample was melted rapidly at as low a temperature as possible, filled in a ring placed on a flat metal plate, taking care not to foam. After cooling, the portion protruding from the plane containing the upper end of the ring was cut off with a slightly heated knife. Next, the support (ring table) was placed in a glass container (heating bath) having a diameter of 85mm or more and a height of 127mm or more, and glycerin was injected until the depth became 90mm or more. Next, a steel ball (diameter: 9.5mm, weight: 3.5 g) and a ring filled with a sample were immersed in glycerin so as not to contact each other, and the temperature of glycerin was maintained at 20.+ -. 5 ℃ for 15 minutes. Then, the steel ball is placed in the center of the surface of the sample in the ring, and is placed in a fixed position on the support. Then, the distance from the upper end of the ring to the glycerin surface was kept at 50mm, a thermometer was placed, the center position of the mercury ball of the thermometer was set to the same height as the center of the ring, and the container was heated. The flame of the Bunsen burner used in heating is positioned in the middle of the center and the edge of the bottom of the container, so that the heating is uniform. The rate of rise in bath temperature after reaching 40℃after the start of heating must be 5.0.+ -. 0.5℃per minute. The sample gradually softens and flows down the ring, and the temperature at which it eventually contacts the bottom plate is read as the softening point. The softening points were measured simultaneously in 2 or more pieces, and the average value was used.

As the tackifier, for example, a tackifier resin can be used. Specific examples of the tackifying resin include phenol-based tackifying resins, terpene-based tackifying resins, rosin-based tackifying resins, hydrocarbon-based tackifying resins, epoxy-based tackifying resins, polyamide-based tackifying resins, elastomer-based tackifying resins, ketone-based tackifying resins, and the like.

Examples of the phenolic tackifying resin include terpene phenol resins, hydrogenated terpene phenol resins, alkyl phenol resins, rosin phenol resins, and xylene formaldehyde resins.

The term "terpene phenol resin" means a polymer containing terpene residues and phenol residues, and the concept thereof includes both a copolymer of a terpene and a phenol compound (terpene-phenol copolymer resin) and a resin obtained by phenol-modifying a terpene homopolymer or copolymer (phenol-modified terpene resin). Examples of terpenes constituting such terpene phenol resins include monoterpenes such as α -pinene, β -pinene, and limonene (including d-form, l-form, and d/l-form (dipentene)).

The hydrogenated terpene phenol resin is a hydrogenated terpene phenol resin having a structure obtained by hydrogenating such a terpene phenol resin, and is sometimes referred to as a hydrogenated terpene phenol resin.

The alkylphenol resin is a resin (oleophenol resin) obtained from alkylphenol and formaldehyde. Examples of the alkylphenol resin include Novolac type and Resol type.

Examples of the rosin phenol resin include rosin and phenol modified products of various rosin derivatives (including rosin esters, unsaturated fatty acid modified rosin and unsaturated fatty acid modified rosin esters). Examples of the rosin phenol resin include rosin phenol resins obtained by a method in which phenol is added to rosin or various rosin derivatives using an acid catalyst and subjected to thermal polymerization.

Examples of the terpene-based tackifying resin include terpene resins, terpene phenol resins, styrene-modified terpene resins, aromatic-modified terpene resins, and hydrogenated terpene resins.

Examples of the terpene resin include polymers of terpenes (typically monoterpenes) such as α -pinene, β -pinene, d-limonene, l-limonene, dipentene, and the like. Examples of homopolymers of 1 terpene include α -pinene polymers, β -pinene polymers, dipentene polymers, and the like.

Rosin-based tackifying resins include both rosin-based and rosin derivative resins.

Examples of the rosin include unmodified rosins (raw rosins) such as gum rosin, wood rosin, and tall oil rosin; modified rosins (hydrogenated rosins, disproportionated rosins, polymerized rosins, other chemically modified rosins, etc.) obtained by modifying these unmodified rosins by hydrogenation, disproportionation, polymerization, etc.; etc.

Examples of the rosin derivative resin include rosin esters such as unmodified rosin esters which are esters of unmodified rosin and alcohols, and modified rosin esters which are esters of modified rosin and alcohols; unsaturated fatty acid-modified rosins obtained by modifying rosins with unsaturated fatty acids; unsaturated fatty acid modified rosin esters obtained by modifying rosin esters with unsaturated fatty acids; rosin alcohols obtained by reducing carboxyl groups of rosin-based or rosin-derived resins (rosin esters, unsaturated fatty acid-modified rosin-based or unsaturated fatty acid-modified rosin esters, etc.); rosin phenols; their metal salts; etc.

Examples of rosin esters include methyl esters, triethylene glycol esters, glycerol esters, pentaerythritol esters, and maleic acid esters of unmodified or modified rosins (e.g., hydrogenated rosins, disproportionated rosins, and polymerized rosins).

Examples of the hydrocarbon-based tackifying resin include aliphatic hydrocarbon resins, aromatic hydrocarbon resins (e.g., styrene-based resins, xylene-based resins, etc.), aliphatic cyclic hydrocarbon resins, aliphatic/aromatic petroleum resins (e.g., styrene-olefin-based copolymers, etc.), aliphatic/alicyclic petroleum resins, hydrogenated hydrocarbon resins, coumarone-based resins, coumarone-indene-based resins, etc.

Among them, terpene-based tackifying resins or rosin-based tackifying resins are preferable. The tackifier may be used alone or in combination of 2 or more.

In the embodiment of the present invention, when 2 or more tackifiers are used in combination, the product of the acid value and the content of each of the tackifiers may be obtained, and the value obtained by adding them together may be less than 1200. The preferable range of the sum of the acid value and the content of each of the tackifiers in combination of 2 or more kinds is the same as that of the tackifiers used alone.

The preferable acid value of the pressure-sensitive adhesive according to the embodiment of the present invention varies depending on the content of the pressure-sensitive adhesive to be used, and is, in general, preferably 50mgKOH/g or less, more preferably 30mgKOH/g or less, and most preferably 10mgKOH/g from the viewpoint of electric releasability. The lower limit is not particularly limited.

The acid value of the thickener is preferably 1 to 200mgKOH/g.

The content of the tackifier in the pressure-sensitive adhesive composition according to the embodiment of the present invention varies depending on the magnitude of the acid value of the tackifier used, and is usually preferably 5 parts by mass or more, more preferably 7.5 parts by mass or more, still more preferably 10 parts by mass or more, and most preferably 15 parts by mass or more, relative to 100 parts by mass of the polymer, for example, from the viewpoint of electric releasability. By setting the content of the tackifier to 5 parts by mass or more, the effect of adding the tackifier, that is, the effect of combining the initial adhesion and the electric peelability can be easily obtained. The upper limit is preferably 50 parts by mass or less, more preferably 45 parts by mass or less, still more preferably 40 parts by mass or less, and most preferably 30 parts by mass. By setting the content of the tackifier to 50 parts by mass or less, dispersibility of the tackifier in the resin can be maintained, and initial adhesion can be easily obtained.

The content of the tackifier in the adhesive composition is preferably 5 to 50 parts by mass relative to 100 parts by mass of the polymer.

(Polymer 2)

The adhesive composition according to the embodiment of the present invention may further include a2 nd polymer having a glass transition temperature (Tg) of 40 to 180 ℃.

In the adhesive composition according to the embodiment of the present invention, the glass transition temperature (Tg) of the 2 nd polymer must be 40 to 180 ℃. Further, the polymer may be a polymer different from the polymer.

The adhesive composition according to the embodiment of the present invention can obtain an effect of improving the elastic modulus by including the 2 nd polymer having a glass transition temperature (Tg) of 40 to 180 ℃, and can exhibit excellent adhesion when no voltage is applied, and can form an adhesive layer having excellent wet heat stability in which the adhesion is sufficiently reduced by the application of voltage even after storage under high-temperature and high-humidity environments.

From the viewpoint of the adhesive property, the glass transition temperature (Tg) of the 2 nd polymer is preferably 40 ℃ or higher, more preferably 50 ℃ or higher, still more preferably 60 ℃ or higher, and preferably 70 ℃ or higher. From the viewpoint of the adhesive property, it is necessary to be 180 ℃ or less, more preferably 160 ℃ or less, still more preferably 140 ℃ or less, still more preferably 120 ℃ or less, and still more preferably 100 ℃ or less.

The glass transition temperature (Tg) of the 2 nd polymer can be calculated by the same method as the glass transition temperature (Tg) of the polymer.

The glass transition temperature (Tg) of the 2 nd polymer can be adjusted by the kind, amount, and the like of the monomer constituting the 2 nd polymer.

In the embodiment of the present invention, the 2 nd polymer is not particularly limited as long as the Tg satisfies the above specific range, and a usual organic polymer compound may be used, and examples thereof include a polymer of a monomer or a partial polymer. The monomer may be 1 monomer or a mixture of 2 or more monomers. The partial polymer is a polymer in which 1 or 2 or more components in a monomer or a monomer mixture are partially polymerized.

The 2 nd polymer may be a polymer having an adhesive property, or may be the tackifying resin. The 2 nd polymer preferably contains an organic polymer compound in addition to the above-mentioned tackifying resin. The adhesive composition is preferably used because the initial adhesion and the electrical peelability can be further improved by including the 2 nd polymer, particularly an organic polymer compound as the 2 nd polymer.

Examples of the organic polymer compound contained in the 2 nd polymer include acrylic polymers, rubber polymers, vinyl alkyl ether polymers, silicone polymers, polyester polymers, polyamide polymers, urethane polymers, fluorine polymers, and epoxy polymers.

In the present specification, the organic high molecular compound in the 2 nd polymer means a polymer or a partial polymer compound as a monomer, and means a component different from the tackifying resin and the polymer.

Among the above, acrylic polymers and polyester polymers are preferably used from the viewpoint of adhesive properties.

In the embodiment of the present invention, the acrylic polymer used as the organic high molecular compound in the 2 nd polymer may be a commercially available polymer or may be obtained by polymerizing an acrylic monomer component.

Examples of the commercial products of the acrylic polymer used as the organic polymer compound in the 2 nd polymer include ARUFON UH2170 and UC3000 (manufactured by eastern asia synthetic corporation).

As the acrylic monomer component, any acrylic monomer may be used, and examples thereof include hydroxyl group-containing acrylic monomers, polymerizable acrylic monomers, and the like.

The acrylic monomer component constituting the organic polymer compound in the 2 nd polymer preferably contains a polymerizable acrylic monomer. The polymerizable acrylic monomer contained in the acrylic monomer component may be 1 or 2 or more.

Examples of the polymerizable monomer include Acrylic Acid (AA), N-vinyl-2-pyrrolidone, dicyclopentyl methacrylate, methyl Acrylate (MA), methyl Methacrylate (MMA), cyclohexyl acrylate, cyclohexyl methacrylate (CHMA), isobornyl acrylate (IBXMA), β -carboxyethyl acrylate, 2-hydroxy-3-phenoxypropyl acrylate, acrylonitrile, acrylamide, dimethylacrylamide, isopropylacrylamide, hydroxyethylacrylamide, methylolacrylamide, hydroxybutylacrylamide, acryloylmorpholine (ACMO), 1-vinylimidazole, and the like, and at least one selected from the group consisting of acrylic acid, methyl Acrylate (MA), methyl Methacrylate (MMA), cyclohexyl acrylate, cyclohexyl methacrylate (CHMA), isobornyl acrylate (IBXMA), and Acryloylmorpholine (ACMO) is preferable, and at least one selected from the group consisting of Acrylic Acid (AA), cyclohexyl acrylate, cyclohexyl methacrylate (CHMA), and isobornyl acrylate (IBXMA) is more preferable from the viewpoint of further exhibiting the effect of the present invention.

From the viewpoint of the adhesive property, the content of the polymerizable monomer in the acrylic monomer component is preferably 1% by mass or more, more preferably 10% by mass or more, still more preferably 30% by mass or more, still more preferably 50% by mass or more, and still more preferably 80% by mass or more.

Specific examples of the hydroxyl group-containing monomer include hydroxyalkyl (meth) acrylates such as 2-hydroxybutyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 4-hydroxybutyl acrylate (4 HBA), 4-hydroxybutyl methacrylate, 6-hydroxyhexyl (meth) acrylate, 8-hydroxyoctyl (meth) acrylate, 10-hydroxydecyl (meth) acrylate, and 12-hydroxylauryl (meth) acrylate; hydroxyalkyl cycloalkane (meth) acrylates such as (4-hydroxymethyl cyclohexyl) methyl (meth) acrylate; other hydroxyl-containing monomers such as hydroxyethyl (meth) acrylamide, allyl alcohol, 2-hydroxyethyl vinyl ether, 4-hydroxybutyl vinyl ether, diethylene glycol monovinyl ether, and the like; etc.

Among them, from the viewpoint of operability and the effect of the present invention can be further exhibited, the hydroxyl-containing monomers are preferably hydroxyalkyl (meth) acrylates, more preferably hydroxyalkyl (meth) acrylates having a hydroxyalkyl group having 2 to 6 carbon atoms, and specifically, at least 1 selected from 2-hydroxyethyl (meth) acrylate and 4-hydroxybutyl (meth) acrylate is preferable, and 4-hydroxybutyl (4 HBA) acrylate is more preferable.

From the viewpoint of the adhesive property, the content of the hydroxyl group-containing monomer in the acrylic monomer component is preferably 1 mass% or more, more preferably 3 mass% or more, still more preferably 5 mass% or more, still more preferably 10 mass% or more, and preferably 15 parts by mass. From the viewpoint of the adhesive property, it is preferably 30 mass% or less, more preferably 25 mass% or less, and even more preferably 20 mass% or less.

The organic polymer compound in the 2 nd polymer according to the embodiment of the present invention can be produced by any suitable polymerization within a range that does not impair the effects of the present invention.

Examples of the method for polymerizing the organic polymer compound in the 2 nd polymer according to the embodiment of the present invention include a solution polymerization method, an emulsion polymerization method, a bulk polymerization method, and a polymerization method by irradiation of active energy rays (active energy ray polymerization method). Among them, the bulk polymerization method and the solution polymerization method are preferable, and the solution polymerization method is more preferable.

Examples of the solvent that can be used for polymerization include esters such as ethyl acetate and n-butyl acetate; aromatic hydrocarbons such as toluene and benzene; aliphatic hydrocarbons such as n-hexane and n-heptane; alicyclic hydrocarbons such as cyclohexane and methylcyclohexane; ketones such as methyl ethyl ketone and methyl isobutyl ketone; and the like. The number of solvents may be 1 or 2 or more.

In the polymerization, any suitable polymerization initiator (e.g., a thermal polymerization initiator, a photopolymerization initiator, etc.) may be used within a range that does not impair the effects of the present invention. The polymerization initiator may be 1 or 2 or more. In the case of performing solution polymerization, an oil-soluble polymerization initiator is preferably used.

As the thermal polymerization initiator, any suitable thermal polymerization initiator may be used within a range that does not impair the effects of the present invention. The thermal polymerization initiator may be 1 or 2 or more. As the thermal polymerization initiator, for example, examples thereof include 2,2 '-Azobisisobutyronitrile (AIBN), 2' -azobis-2-methylbutyronitrile (AMBN), dimethyl 2,2 '-azobis (2-methylpropionate), 4' -azobis-4-cyanovaleric acid azo initiators such as 2,2 '-azobis (4-methoxy-2, 4-dimethylvaleronitrile), 2' -azobis (2, 4-dimethylvaleronitrile), 1 '-azobis (cyclohexane-1-carbonitrile), and 2,2' -azobis (2, 4-trimethylpentane); peroxide initiators such as benzoyl peroxide, t-butyl hydroperoxide, di-t-butyl peroxide, t-butyl peroxybenzoate, dicumyl peroxide, 1-bis (t-butylperoxy) -3, 5-trimethylcyclohexane, and 1, 1-bis (t-butylperoxy) cyclododecane.

The amount of the thermal polymerization initiator used is, for example, preferably 0.1 to 15 parts by mass based on 100 parts by mass of all monomers (monomer composition) that can be used for constituting the organic polymer compound in the 2 nd polymer.

As the photopolymerization initiator, any appropriate photopolymerization initiator may be used within a range that does not impair the effects of the present invention. The photopolymerization initiator may be 1 or 2 or more. Examples of such photopolymerization initiators include benzoin ether photopolymerization initiators, acetophenone photopolymerization initiators, α -ketol photopolymerization initiators, aromatic sulfonyl chloride photopolymerization initiators, photoactive oxime photopolymerization initiators, benzoin photopolymerization initiators, benzil photopolymerization initiators, benzophenone photopolymerization initiators, ketal photopolymerization initiators, thioxanthone photopolymerization initiators, and acylphosphine oxide photopolymerization initiators.

The amount of the photopolymerization initiator used is, for example, preferably 0.001 to 0.5 parts by mass based on 100 parts by mass of all monomers (monomer composition) that can be used for constituting the organic polymer compound in the 2 nd polymer.

In the polymerization of the organic polymer compound in the 2 nd polymer, a chain transfer agent may be used for adjusting the molecular weight. Examples of the chain transfer agent include 2-mercaptoethanol, α -thioglycerol, 2, 3-dimercapto-1-propanol, octylmercaptan, t-nonylthiol, dodecylmercaptan (lauryl mercaptan), t-dodecylmercaptan, glycidyl mercaptan, thioglycolic acid, methyl thioglycolate, ethyl thioglycolate, propyl thioglycolate, butyl thioglycolate, t-butyl thioglycolate, 2-ethylhexyl thioglycolate, octyl thioglycolate, isooctyl thioglycolate, decyl thioglycolate, dodecyl thioglycolate, thioglycolate of ethylene glycol, thioglycolate of neopentyl glycol, thioglycolate of pentaerythritol, and α -methylstyrene dimer. Among them, 2-mercaptoethanol and methyl thioglycolate are preferable, and 2-mercaptoethanol is particularly preferable from the viewpoint of suppressing whitening or the like of the double-sided adhesive tape of the present invention. The chain transfer agent may be 1 or 2 or more.

For example, the amount of the chain transfer agent to be used is preferably 0.1 to 20 parts by mass, more preferably 0.2 to 15 parts by mass, and even more preferably 0.3 to 10 parts by mass, based on 100 parts by mass of the total monomers (monomer composition) that can be used to constitute the organic polymer compound in the 2nd polymer.

The weight average molecular weight of the organic polymer compound in the 2 nd polymer is not particularly limited, but is preferably 500 to 100 ten thousand. The upper limit of the weight average molecular weight is more preferably 80 ten thousand, still more preferably 60 ten thousand, still more preferably 40 ten thousand, still more preferably 20 ten thousand, still more preferably 10 ten thousand, still more preferably 1 ten thousand, and the lower limit is more preferably 1000, still more preferably 2000, still more preferably 3000, still more preferably 4000. When the weight average molecular weight is 500 or more, the surface of the adherend after peeling the adhesive layer due to surface segregation can be effectively prevented from being contaminated. In addition, when the weight average molecular weight is 100 ten thousand or less, the decrease in the cohesive force of the pressure-sensitive adhesive layer can be effectively suppressed, and the occurrence of a problem such as the occurrence of a residual adhesive on the adherend after peeling can be effectively suppressed.

From the viewpoint of the adhesive property, the content of the organic polymer compound in the 2 nd polymer is preferably 1 to 40 parts by mass, more preferably 1 to 30 parts by mass, still more preferably 1 to 20 parts by mass, and particularly preferably 1 to 10 parts by mass, relative to 100 parts by mass of the polymer.

The 2 nd polymer may be used alone or in combination of 2 or more.

The content of the 2 nd polymer in the adhesive composition according to the embodiment of the present invention is preferably 1 part by mass or more, more preferably 5 parts by mass or more, still more preferably 10 parts by mass or more, particularly preferably 15 parts by mass or more, still more preferably 20 parts by mass or more, still more preferably 25 parts by mass or more, and most preferably 30 parts by mass or more, relative to 100 parts by mass of the polymer or 100 parts by mass of the monomer mixture as a raw material of the polymer, from the viewpoint of the adhesive property. From the viewpoint of the adhesive property, it is preferably 50 parts by mass or less, more preferably 40 parts by mass or less, and still more preferably 30 parts by mass or less.

The content of the 2 nd polymer may be 1 to 50 parts by mass based on 100 parts by mass of the polymer.

These 2 nd polymers may be added after the polymer is obtained or may be blended with a monomer mixture as a raw material of the polymer before the polymer is obtained and subjected to polymerization, but it is preferable that the polymer and the 2 nd polymer are blended after each of them is subjected to polymerization.

(Other Components)

The adhesive composition according to the embodiment of the present invention may contain 1 or 2 or more components (hereinafter, sometimes referred to as "other components") other than the polymer, the ionic liquid, and the 2 nd polymer as needed within a range that does not impair the effects of the present invention. Hereinafter, other components that may be contained in the adhesive composition according to the embodiment of the present invention will be described.

(Catalyst)

The adhesive composition according to the embodiment of the present invention may contain a catalyst. Examples of the catalyst include an organometallic compound and a tertiary amine compound. The number of the catalysts may be 1 or 2 or more.

Examples of the organometallic compound include iron-based compounds, tin-based compounds, titanium-based compounds, zirconium-based compounds, lead-based compounds, cobalt-based compounds, and zinc-based compounds. Among them, iron-based compounds and tin-based compounds are preferable in terms of reaction rate and pot life of the adhesive layer.

Examples of the iron-based compound include iron acetylacetonate and iron 2-ethylhexanoate.

Examples of the tin compound include dibutyltin dichloride, dibutyltin oxide, dibutyltin dibromide, dibutyltin maleate, dibutyltin dilaurate, dibutyltin diacetate, dibutyltin sulfide, tributylmethoxy tin, tributyltin acetate, triethylethoxy tin, tributylethoxy tin, dioctyl tin oxide, dioctyl tin dilaurate, tributyltin chloride, tributyltin trichloroacetate, and tin 2-ethylhexanoate.

Examples of the titanium compound include dibutyl titanium dichloride, tetrabutyl titanate, and butoxytitanium trichloride.

Examples of the zirconium compound include zirconium naphthenate and zirconium acetylacetonate.

Examples of the lead compound include lead oleate, lead 2-ethylhexanoate, lead benzoate, and lead naphthenate.

Examples of the cobalt-based compound include cobalt 2-ethylhexanoate and cobalt benzoate.

Examples of the zinc compound include zinc naphthenate and zinc 2-ethylhexanoate.

Examples of the tertiary amine compound include triethylamine, triethylenediamine and 1, 8-diazabicyclo- (5, 4, 0) -undec-7-ene.

The amount of the catalyst is preferably 0.02 to 0.50 wt%, more preferably 0.05 to 0.40 wt%, and even more preferably 0.07 wt% based on the polyol (a).

(Ionic additive)

The adhesive composition according to the embodiment of the present invention may contain an ionic additive for the purpose of controlling the electric peeling force. As the ionic additive, for example, an ionic solid can be used.

The ionic solid is an ionic substance that is solid at 25 ℃. The ionic solid is not particularly limited, and for example, a solid substance among ionic substances obtained by combining anions and cations exemplified in the description column of the ionic liquid can be used. When the binder composition contains an ionic solid, the content of the ionic solid is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, and further preferably 10 parts by mass or less, more preferably 5 parts by mass or less, and further preferably 2.5 parts by mass or less, based on 100 parts by mass of the polymer.

(Crosslinking agent)

The adhesive composition according to the embodiment of the present invention may contain a crosslinking agent as needed for the purpose of improving creep property and shearing property by crosslinking the polymer. Examples of the crosslinking agent include isocyanate-based crosslinking agents, carbodiimide-based crosslinking agents, epoxy-based crosslinking agents, melamine-based crosslinking agents, peroxide-based crosslinking agents, urea-based crosslinking agents, metal alkoxide-based crosslinking agents, metal chelate-based crosslinking agents, metal salt-based crosslinking agents, oxazoline-based crosslinking agents, aziridine-based crosslinking agents, and amine-based crosslinking agents. Examples of the isocyanate-based crosslinking agent include toluene diisocyanate and methylene bis-isocyanate. As the carbodiimide-based crosslinking agent, for example, a polycarbodiimide resin or the like can be considered. Examples of the epoxy-based crosslinking agent include N, N' -tetraglycidyl-m-xylylenediamine, diglycidyl aniline, 1, 3-bis (N, N-diglycidyl aminomethyl) cyclohexane, and 1, 6-hexanediol diglycidyl ether. The content of the crosslinking agent is preferably 0.1 part by mass or more, more preferably 0.7 part by mass or more, and further preferably 50 parts by mass or less, more preferably 10 parts by mass or less, and further preferably 3 parts by mass or less, based on 100 parts by mass of the polymer. The crosslinking agent may be used alone or in combination of 2 or more.

(Polyethylene glycol, tetraethylene glycol dimethyl ether)

The binder composition according to the embodiment of the present invention may contain polyethylene glycol or tetraethylene glycol dimethyl ether as needed for the purpose of aiding movement of the ionic liquid when a voltage is applied. As polyethylene glycol or tetraethylene glycol dimethyl ether, a substance having a number average molecular weight of 100 to 6000 can be used. The content of these components when contained is preferably 0.1 part by mass or more, more preferably 0.5 part by mass or more, further preferably 1 part by mass or more, and further preferably 30 parts by mass or less, more preferably 20 parts by mass or less, further preferably 15 parts by mass or less, per 100 parts by mass of the polymer.

(Conductive filler)

The adhesive composition according to the embodiment of the present invention may contain a conductive filler as needed for the purpose of imparting conductivity to the adhesive composition. The conductive filler is not particularly limited, and a generally known or commonly used conductive filler may be used, and for example, graphite, carbon black, carbon fiber, metal powder of silver, copper, or the like may be used. The content of the conductive filler is preferably 0.1 parts by mass or more and 200 parts by mass or less with respect to 100 parts by mass of the polymer.

(Anticorrosive agent)

The adhesive composition according to the embodiment of the present invention may contain an anticorrosive agent as needed for the purpose of suppressing corrosion of a metal adherend. The anticorrosive agent is not particularly limited, and generally known or commonly used anticorrosive agents may be used, and for example, carbodiimide compounds, adsorption-type inhibitors, chelate-type molded metal deactivators, and the like may be used.

Examples of the carbodiimide compound include 1- [3- (dimethylamino) propyl ] -3-ethylcarbodiimide, 1-ethyl-3- (3-dimethylaminopropyl) carbo-diimide, N '-dicyclohexylcarbodiimide, N' -diisopropylcarbodiimide, 1-ethyl-3-tert-butylcarbodiimide, N-cyclohexyl-N '- (2-morpholinoethyl) carbodiimide, N' -di-tert-butylcarbodiimide, and 1, 3-bis (p-tolyl) carbodiimide. These carbodiimide compounds may be used alone or in combination of 2 or more. The content of the carbodiimide compound in the adhesive composition according to the embodiment of the invention is preferably 0.01 parts by mass or more and 10 parts by mass or less with respect to 100 parts by mass of the polymer.

Examples of the adsorption inhibitor include alkylamines, carboxylates, carboxylic acid derivatives, and alkyl phosphates. The adsorption type inhibitor may be used alone or in combination of 2 or more. The content of the alkylamine in the adhesive composition according to the embodiment of the present invention is preferably 0.01 part by mass or more and 20 parts by mass or less based on 100 parts by mass of the polymer. The content of the carboxylate in the adhesive composition according to the embodiment of the present invention is preferably 0.01 parts by mass or more and 10 parts by mass or less with respect to 100 parts by mass of the polymer. The content of the carboxylic acid derivative in the adhesive composition according to the embodiment of the present invention is preferably 0.01 parts by mass or more and 10 parts by mass or less based on 100 parts by mass of the polymer. The content of the alkyl phosphate in the adhesive composition according to the embodiment of the present invention is preferably 0.01 parts by mass or more and 10 parts by mass or less based on 100 parts by mass of the polymer.

As the chelate forming metal deactivator, for example, a triazole-group-containing compound or a benzotriazole-group-containing compound can be used. These are preferable in view of the above-mentioned fact that they have a high effect of passivating the surface of a metal such as stainless steel or aluminum, and that they are less likely to affect adhesion even when included in the adhesive component. The chelate-forming metal deactivator may be used alone or in combination of 2 or more. The content of the chelate-forming metal deactivator in the adhesive composition according to the embodiment of the present invention is preferably 0.01 parts by mass or more and 20 parts by mass or less with respect to 100 parts by mass of the polymer.

The total content (blending amount) of the anticorrosive agent is preferably 0.01 parts by mass or more and 30 parts by mass or less with respect to 100 parts by mass of the polymer.

(Various additives)

In addition, the adhesive composition according to the embodiment of the present invention may further contain various additives such as a filler, a plasticizer, an anti-aging agent, an antioxidant, a pigment (dye), a flame retardant, a solvent, a surfactant (leveling agent), an anti-rust agent, and an antistatic agent. The total content of these components is not particularly limited as long as the effects of the present invention are achieved, and is preferably 0.01 parts by mass or more and 20 parts by mass or less, more preferably 10 parts by mass or less, and still more preferably 5 parts by mass or less, based on 100 parts by mass of the polymer.

Examples of the filler include silica, iron oxide, zinc oxide, aluminum oxide, titanium oxide, barium oxide, magnesium oxide, calcium carbonate, magnesium carbonate, zinc carbonate, pyrophyllite clay, kaolinite clay, and calcined clay.

Examples of the plasticizer include known plasticizers commonly used in general resin compositions and the like, and examples thereof include liquid rubbers such as paraffin oil, oils such as process oil, liquid polyisoprene, liquid polybutadiene, and liquid ethylene-propylene rubber, tetrahydrophthalic acid, azelaic acid, benzoic acid, phthalic acid, trimellitic acid, pyromellitic acid, adipic acid, sebacic acid, fumaric acid, maleic acid, itaconic acid, citric acid, derivatives thereof, dioctyl phthalate (DOP), dibutyl phthalate (DBP), dioctyl adipate, diisononyl adipate (DINA), and isodecyl succinate.

Examples of the anti-aging agent include hindered phenol compounds, aliphatic and aromatic hindered amine compounds, and the like.

Examples of the antioxidant include Butylhydroxytoluene (BHT) and Butylhydroxyanisole (BHA).

Examples of the pigment include inorganic pigments such as titanium dioxide, zinc oxide, ultramarine blue, iron oxide red, lithopone, lead, cadmium, iron, cobalt, aluminum, hydrochloride, sulfate and the like, and organic pigments such as azo pigments and copper phthalocyanine pigments.

Examples of the rust inhibitor include zinc phosphate, tannic acid derivatives, phosphoric acid esters, basic sulfonates, and various rust-preventive pigments.

Examples of the adhesion imparting agent include a titanium coupling agent and a zirconium coupling agent.

Examples of the antistatic agent include generally quaternary ammonium salts, hydrophilic compounds such as polyglycolic acid and ethylene oxide derivatives.

< Initial adhesive force and electric Release force >

The adhesive strength of the adhesive composition according to the embodiment of the present invention can be evaluated by various methods, for example, by the 180 ° peel test described in the column of examples.

In the adhesive composition according to the embodiment of the present invention, the initial adhesion force measured by forming an adhesive sheet and performing a 180 ° peel test as described in the column above is preferably 4.0N/cm or more, more preferably 4.5N/cm or more, still more preferably 5.0N/cm or more, particularly preferably 5.5N/cm or more, and most preferably 6.0N/cm or more. If the initial adhesion is 4.0N/cm or more, the adhesive strength with the adherend is sufficient, and the adherend is less likely to peel off or shift.

In the adhesive composition according to the embodiment of the present invention, it is preferable that the adhesive sheet is formed as described in the column of the examples, and the electric peeling force, which is the adhesive force measured by the 180 ° peeling test while applying the voltage of 30V for 30 seconds after applying the voltage of 30V, is sufficiently smaller than the initial adhesive force.

In the adhesive composition according to the embodiment of the present invention, the electric peel force measured by 180 ° peel test while applying 30V voltage for 30 seconds after forming the adhesive sheet as described in the example column is preferably 1.0N/cm or less, more preferably 0.5N/cm or less, still more preferably 0.3N/cm or less, particularly preferably 0.1N/cm or less, and most preferably 0.05N/cm or less. When the electric peeling force is 1.0N/cm or less, the electric peeling property is excellent, so that the re-workability is improved and the recycling is easy.

The voltage applied and the time for applying the voltage at the time of the electric peeling are not limited to those described above, and the pressure-sensitive adhesive sheet may be peeled without any particular limitation. The preferred ranges thereof are as follows.

The applied voltage is preferably 1V or more, more preferably 3V or more, and still more preferably 6V or more. Further, the voltage is preferably 100V or less, more preferably 50V or less, further preferably 30V or less, and particularly preferably 15V or less.

The voltage application time is preferably 60 seconds or less, more preferably 40 seconds or less, further preferably 20 seconds or less, and particularly preferably 10 seconds or less. In this case, workability is excellent. The shorter the application time, the better, but is usually 1 second or more.

< Method for producing adhesive composition >

The pressure-sensitive adhesive composition of the present invention is not particularly limited, and can be produced by appropriately stirring and mixing a polymer, an ionic liquid, a thickener, and a crosslinking agent, polyethylene glycol, a conductive filler, and the like, if necessary.

[ Adhesive sheet ]

(Constitution of adhesive sheet)

The pressure-sensitive adhesive sheet according to the embodiment of the present invention is not particularly limited as long as it has at least one pressure-sensitive adhesive layer (hereinafter also referred to as "electrically-releasable pressure-sensitive adhesive layer") formed of the pressure-sensitive adhesive composition according to the embodiment of the present invention. The pressure-sensitive adhesive sheet according to the embodiment of the present invention may have a pressure-sensitive adhesive layer (hereinafter, sometimes referred to as "other pressure-sensitive adhesive layer") containing no ionic liquid other than the electro-release pressure-sensitive adhesive layer. The pressure-sensitive adhesive sheet according to the embodiment of the present invention may further include a base material, a conductive layer, a base material for electric conduction, an intermediate layer, a primer layer, and the like, in addition to the above. The pressure-sensitive adhesive sheet according to the embodiment of the present invention may be wound in a roll form or a sheet form, for example.

The term "adhesive sheet" also includes the meaning of "adhesive tape". That is, the pressure-sensitive adhesive sheet according to the embodiment of the present invention may be a pressure-sensitive adhesive tape having a tape-like shape.

The pressure-sensitive adhesive sheet according to the embodiment of the present invention may be formed of only an electrically-releasable pressure-sensitive adhesive layer without a base material, that is, a double-sided pressure-sensitive adhesive sheet (without a base material) without a base material layer. The pressure-sensitive adhesive sheet according to the embodiment of the present invention may be a double-sided pressure-sensitive adhesive sheet having a base material and pressure-sensitive adhesive layers (an electrically-peelable pressure-sensitive adhesive layer or other pressure-sensitive adhesive layers) on both sides of the base material. The pressure-sensitive adhesive sheet according to the embodiment of the present invention may be a single-sided pressure-sensitive adhesive sheet having a base material and having a pressure-sensitive adhesive layer (an electrically-peelable pressure-sensitive adhesive layer or other pressure-sensitive adhesive layer) on only one side of the base material. The pressure-sensitive adhesive sheet according to the embodiment of the present invention may have a release liner for protecting the surface of the pressure-sensitive adhesive layer, but the release liner is not included in the pressure-sensitive adhesive sheet according to the embodiment of the present invention.

The structure of the pressure-sensitive adhesive sheet according to the embodiment of the present invention is not particularly limited, and preferably, the pressure-sensitive adhesive sheet X1 shown in fig. 1, the pressure-sensitive adhesive sheet X2 shown in fig. 2 and the pressure-sensitive adhesive sheet X3 shown in fig. 3 are laminated. The adhesive sheet X1 is a base-material-free double-sided adhesive sheet formed only of the electro-release adhesive layer 1. The pressure-sensitive adhesive sheet X2 is a double-sided pressure-sensitive adhesive sheet with a base material, which is composed of layers including a pressure-sensitive adhesive layer 2, a base material 5 for electrical conduction (base material 3 and conductive layer 4), and an electrically-peelable pressure-sensitive adhesive layer 1. The pressure-sensitive adhesive sheet X3 is a double-sided pressure-sensitive adhesive sheet with a base material, which is composed of layers including a pressure-sensitive adhesive layer 2, a base material 5 for electric conduction (base material 3 and conductive layer 4), an electrically-peelable pressure-sensitive adhesive layer 1, a base material 5 for electric conduction (base material 3 and conductive layer 4), and a pressure-sensitive adhesive layer 2. In the base material 5 for energizing the adhesive sheets X2 and X3 shown in fig. 2 and 3, the base material 3 is not necessarily required, and may be only the conductive layer 4. In the pressure-sensitive adhesive sheet X2 of fig. 2, the pressure-sensitive adhesive layer 2 may be omitted.

The substrate 3 is not particularly limited, and examples thereof include paper substrates such as paper, fiber substrates such as cloth and nonwoven fabric, plastic substrates such as films and sheets formed of various plastics (polyolefin resins such as polyethylene and polypropylene, polyester resins such as polyethylene terephthalate, acrylic resins such as polymethyl methacrylate, and the like), and laminates thereof. The substrate may have a single layer or a multilayer structure. The substrate may be subjected to various treatments such as a back surface treatment, an antistatic treatment, and a primer treatment, as needed.

The conductive layer 4 is not particularly limited as long as it is a layer having conductivity, and may be a metal (e.g., aluminum, magnesium, copper, iron, tin, gold, etc.) foil, a metal base material such as a metal plate (e.g., aluminum, magnesium, copper, iron, tin, silver, etc.), a conductive polymer, or the like, or may be a metal vapor deposited film or the like provided on the base material 3.

The substrate for energization 5 is not particularly limited as long as it is a substrate having a conductive layer (energized), and examples thereof include a substrate having a metal layer formed on the surface of the substrate exemplified above by a plating method, a chemical vapor deposition method, a sputtering method, and the like. The metal layer may be a metal, a metal plate, or a conductive polymer as exemplified above.

In the pressure-sensitive adhesive sheet X1, the adherend on both sides is preferably an adherend having a metal adherend surface. In the pressure-sensitive adhesive sheet X2, the adherend on the side of the electro-release pressure-sensitive adhesive layer 1 is preferably an adherend having a metal adherend surface.

The metal-adhered surface is a surface having conductivity and formed of a metal containing, for example, aluminum, copper, iron, magnesium, tin, gold, silver, lead, or the like as a main component, and among these, a surface formed of a metal containing iron or aluminum (for example, stainless steel, or the like) is preferable. Examples of the adherend having a metal adherend surface include a sheet, a member, a plate, and the like, which are made of a metal containing aluminum, copper, iron, magnesium, tin, gold, silver, lead, and the like as a main component. Examples of the adherend other than the adherend having a metal adherend surface include, but are not particularly limited to, fibrous sheets such as paper, cloth and nonwoven fabric, films and sheets of various plastics, and the like.

From the viewpoint of initial adhesion, the thickness of the electro-release adhesive layer 1 is preferably 1 μm to 1000 μm. The upper limit of the thickness of the electro-release adhesive layer 1 is more preferably 500 μm, still more preferably 300 μm, still more preferably 200 μm, still more preferably 150 μm, still more preferably 100 μm, still more preferably 80 μm, still more preferably 70 μm, still more preferably 60 μm, still more preferably 50 μm, and the lower limit is more preferably 5 μm, still more preferably 10 μm, still more preferably 20 μm, still more preferably 30 μm.

The thickness of the electrically-peelable adhesive sheet according to the present embodiment is preferably 20 μm or more and 3000 μm or less. The upper limit of the thickness is more preferably 1000 μm, still more preferably 500 μm, still more preferably 300 μm, still more preferably 250 μm, still more preferably 200 μm, still more preferably 150 μm, still more preferably 100 μm, and the lower limit is more preferably 30 μm, still more preferably 50 μm.

From the viewpoint of adhesion, the thickness of the adhesive layer 2 is preferably 1 μm to 2000 μm. The upper limit of the thickness of the pressure-sensitive adhesive layer 2 is more preferably 1000 μm, still more preferably 500 μm, particularly preferably 100 μm, and the lower limit is more preferably 3 μm, still more preferably 5 μm, particularly preferably 8 μm.

The thickness of the base material 3 is preferably 10 μm or more and 1000 μm or less. The upper limit of the thickness is more preferably 500. Mu.m, still more preferably 300. Mu.m, particularly preferably 100. Mu.m, and the lower limit is more preferably 12. Mu.m, still more preferably 25. Mu.m.

The thickness of the conductive layer 4 is preferably 0.001 μm or more and 1000 μm or less. The upper limit of the thickness is more preferably 500. Mu.m, still more preferably 300. Mu.m, still more preferably 50. Mu.m, still more preferably 10. Mu.m, and the lower limit is more preferably 0.01. Mu.m, still more preferably 0.03. Mu.m, still more preferably 0.05. Mu.m.

The thickness of the base material 5 for electric conduction is preferably 10 μm or more and 1000 μm or less. The upper limit of the thickness is more preferably 500. Mu.m, still more preferably 300. Mu.m, particularly preferably 100. Mu.m, and the lower limit is more preferably 12. Mu.m, still more preferably 25. Mu.m.

The surface of the electrically-releasable adhesive layer and other adhesive layers of the adhesive sheet according to the embodiment of the present invention may be protected by a release liner. The release liner is not particularly limited, and examples thereof include: a release liner obtained by subjecting the surface of a substrate (liner substrate) such as paper or plastic film to a silicone treatment; and release liners obtained by laminating the surface of a substrate (liner substrate) such as paper or plastic film with a polyolefin resin. The thickness of the release liner is not particularly limited, but is preferably 10 μm to 100 μm.

The thickness of the pressure-sensitive adhesive sheet according to the embodiment of the present invention is preferably 20 μm to 3000 μm. The upper limit of the thickness is more preferably 1000 μm, still more preferably 500 μm, still more preferably 300 μm, still more preferably 250 μm, still more preferably 200 μm, still more preferably 150 μm, still more preferably 100 μm, and the lower limit is more preferably 30 μm, still more preferably 50 μm.

In particular, in the case of the pressure-sensitive adhesive sheet X2 shown in FIG. 2, the thickness of the pressure-sensitive adhesive sheet is preferably 50 μm to 2000. Mu.m. The upper limit of the thickness is more preferably 1000. Mu.m, still more preferably 500. Mu.m, still more preferably 300. Mu.m, still more preferably 250. Mu.m, still more preferably 200. Mu.m, still more preferably 150. Mu.m, and the lower limit is more preferably 80. Mu.m, still more preferably 100. Mu.m.

In particular, in the case of the pressure-sensitive adhesive sheet X3 shown in FIG. 3, the thickness of the pressure-sensitive adhesive sheet is preferably 20 μm to 3000 μm. The upper limit of the thickness is more preferably 1000 μm, still more preferably 500 μm, still more preferably 300 μm, still more preferably 250 μm, still more preferably 200 μm, still more preferably 150 μm, and the lower limit is more preferably 50 μm, still more preferably 80 μm, still more preferably 100 μm.

The pressure-sensitive adhesive sheet according to the embodiment of the present invention may further include a coating layer. The coating is preferably disposed between the electrically releasable adhesive layer and the conductive layer.

The electrically-peelable adhesive sheet according to the present embodiment further includes a coating layer, whereby the ionic liquid contained in the electrically-peelable adhesive layer is prevented from penetrating into the conductive layer by the application of a voltage, and the effect of preventing the conductive layer from peeling off the substrate is achieved.

Further, since the coating layer is in contact with the electrically-peelable adhesive layer, the adhesion between the electrically-peelable adhesive layer and the conductive layer is improved, and the effect of preventing peeling in the electrically-peelable adhesive sheet due to reduction in interfacial adhesion between the electrically-peelable adhesive layer and a conductive material (for example, an adherend or the like) caused by thermosetting of the electrically-peelable adhesive layer exposed to a high-temperature environment is achieved.

The coating layer is a layer mainly composed of a resin or an inorganic substance, and can be formed using a resin composition mainly composed of a resin component or a composition mainly composed of an inorganic substance.

The coating layer preferably contains at least one resin selected from polyester-based resins, acrylic-based resins, epoxy-based resins, and urethane-based resins, or at least one inorganic substance selected from SiNx, siOx, al ₂O₃, ni, and NiCr.

(Method for producing adhesive sheet)

The method for producing the pressure-sensitive adhesive sheet according to the embodiment of the present invention may be a known or commonly used method. The electrically-releasable pressure-sensitive adhesive layer in the pressure-sensitive adhesive sheet according to the embodiment of the present invention includes the following methods: the adhesive composition according to the embodiment of the present invention is applied to a release liner, and if necessary, the solution obtained by dissolving the adhesive composition in a solvent is dried and/or cured. The other pressure-sensitive adhesive layers include the following methods: the release liner is coated with a solution obtained by dissolving the adhesive composition containing no ionic liquid in a solvent as needed, and dried and/or cured. The solvents and release liners listed above may be used.

In coating, a usual coater (e.g., gravure roll coater, reverse roll coater, kiss roll coater, dip roll coater, bar coater, blade coater, spray roll coater, etc.) may be used.

The electrically-peelable adhesive layer and the other adhesive layers can be produced by the above-described method, and the adhesive sheet according to the embodiment of the present invention can be produced by appropriately laminating the electrically-peelable adhesive layer and the other adhesive layers on the substrate, the conductive layer, and the base material for electric conduction. Instead of the release liner, a base material, a conductive layer, and an energizing base material may be used, and the adhesive composition may be applied to produce an adhesive sheet.

(Method of electrically peeling adhesive sheet)

The release of the pressure-sensitive adhesive sheet according to the embodiment of the present invention from the adherend can be performed by: by applying a voltage to the electro-release adhesive layer, a potential difference is generated in the thickness direction of the electro-release adhesive layer.

For example, in the joined body obtained by attaching the adhesive sheet X1 to the conductive adherend, the conductive adherend can be energized, and the electric peeling type adhesive layer can be peeled by applying a voltage thereto.

In the case where the pressure-sensitive adhesive sheet X2 has an adherend having a metal adherend surface on the side of the electrically-peelable pressure-sensitive adhesive layer, the electrically-conductive adherend and the conductive layer 4 can be energized, and a voltage can be applied to the electrically-peelable pressure-sensitive adhesive layer to peel off the electrically-peelable pressure-sensitive adhesive layer.

In the case of the pressure-sensitive adhesive sheet X3, the electrically conductive layers 4 on both sides can be electrified and a voltage can be applied to the electrically releasable pressure-sensitive adhesive layer to peel the same.

The electrification is preferably performed by connecting terminals to one end and the other end of the pressure-sensitive adhesive sheet so that a voltage is applied to the whole of the electrically-peelable pressure-sensitive adhesive layer. In the case where the adherend has a metal adherend surface, the one end and the other end may be part of the adherend having a metal adherend surface. In the peeling, water may be added to the interface between the metal adherend surface and the electrically-peeling adhesive layer, and then a voltage may be applied.

(Use of adhesive sheet)

As a conventional re-peeling technique, there are an adhesive layer peeled by curing by irradiation with Ultraviolet (UV) light and an adhesive layer peeled by heat. An adhesive sheet using such an adhesive layer cannot be used in cases where Ultraviolet (UV) light is difficult to irradiate, in cases where heat damages a member as an adherend, or the like. The pressure-sensitive adhesive sheet according to the embodiment of the present invention including the above-described electrically-peelable pressure-sensitive adhesive layer does not use ultraviolet light or heat, and therefore, the pressure-sensitive adhesive sheet can be easily peeled off by applying a voltage without damaging a member as an adherend.

By utilizing the above characteristics, the adhesive sheet according to the embodiment of the present invention is suitable for use in fixing a secondary battery (for example, a lithium ion battery pack) used in a mobile terminal such as a smart phone, a mobile phone, a notebook computer, a video camera, a digital camera, and the like in a case. The pressure-sensitive adhesive sheet according to the embodiment of the present invention is suitable for fixing a vehicle-mounted member (for example, a battery, a motor, or the like). The adhesive sheet according to the embodiment of the present invention is suitable for fixing purposes (for example, ceramic capacitors, lithium ion batteries, and the like) in semiconductor manufacturing processes and inspections. The pressure-sensitive adhesive sheet according to the embodiment of the present invention is suitable for protecting use in a metal working process (for example, a stainless steel sheet for railway use).

Examples of the rigid member to be bonded by the adhesive sheet according to the embodiment of the present invention include a silicon substrate for a semiconductor wafer, a sapphire substrate for an LED, a SiC substrate and a metal base substrate, a TFT substrate and a color filter substrate for a display, and a base substrate for an organic EL panel. Examples of the fragile member to be bonded by the double-sided adhesive sheet include a semiconductor substrate such as a compound semiconductor substrate, a silicon substrate for MEMS devices, a passive matrix substrate, a surface cover glass for smart phones, an OGS (One Glass Solution, monolithic glass touch technology) substrate having a touch panel sensor attached to the cover glass, an organic substrate and an organic-inorganic hybrid substrate containing silsesquioxane as a main component, a flexible glass substrate for flexible displays, and a graphene sheet.

[ Joint body ]

The joined body according to the embodiment of the present invention includes the adhesive sheet according to the embodiment of the present invention and the conductive material, and is a joined body in which the electrically-peelable adhesive layer in the adhesive sheet is adhered to the conductive material.

The conductive material is preferably an adherend having a metal adherend surface, and examples of the adherend having a metal adherend surface include an adherend formed of a metal mainly composed of aluminum, copper, iron, magnesium, tin, gold, silver, lead, and the like, and among these, a metal containing aluminum is preferable.

As a joined body according to an embodiment of the present invention, for example, there may be mentioned: an adhesive sheet X1 which is a bonded body of an adherend having a metal adherend surface on both sides of the electrically-releasable adhesive layer 1; an adhesive sheet X2 which is a joined body having an adherend having a metal adherend surface on the side of the electro-peeling adhesive layer 1 and an adherend on the side of the adhesive layer 2; an adhesive sheet X3 which is a bonded body of an adherend is provided on both sides of the adhesive layer 2; etc.

As described above, the following matters are disclosed in the present specification.

<1>

An adhesive composition comprising a polymer, an ionic liquid and an adhesion promoter,

The product of the acid value [ mgKOH/g ] of the tackifier and the content [ parts by mass ] of the tackifier per 100 parts by mass of the polymer is less than 1200.

<2>

The adhesive composition according to <1>, wherein the softening point of the tackifier is 100 ℃ or higher.

<3>

The adhesive composition according to <1> or <2>, wherein the content of the tackifier is 5 to 50 parts by mass based on 100 parts by mass of the polymer.

<4>

The adhesive composition according to any one of <1> to <3>, wherein the tackifier is a terpene-based tackifying resin or a rosin-based tackifying resin.

<5>

The adhesive composition according to any one of <1> to <4>, wherein the anion of the ionic liquid comprises at least 1 selected from the group consisting of bis (fluorosulfonyl) imide anion and bis (trifluoromethanesulfonyl) imide anion.

<6>

The adhesive composition according to any one of <1> to <5>, wherein the polymer comprises at least 1 selected from the group consisting of a polyester-based polymer, a urethane-based polymer and an acrylic-based polymer.

<7>

The adhesive composition according to any one of <1> to <6>, further comprising a2 nd polymer having a glass transition temperature (Tg) of 40 to 180 ℃.

<8>

The adhesive composition according to <7>, wherein the content of the 2 nd polymer is 1 to 50 parts by mass based on 100 parts by mass of the polymer.

<9>

The adhesive composition according to any one of <1> to <8>, which is used for electric peeling.

<10>

An adhesive sheet comprising an adhesive layer formed from the adhesive composition according to any one of <1> to <9 >.

<11>

A bonded body comprising the adhesive sheet of <10> and a conductive material,

The adhesive layer is adhered to the conductive material.

Examples

The present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples. The weight average molecular weight described below was measured by Gel Permeation Chromatography (GPC). The Tg of the acrylic polymer and the Tg of the second polymer were determined by the FOX equation, and the Tg of the polyester polymer was calculated using the catalogue value. In addition, the acid value, hydroxyl value, tg and softening point of the tackifier are in principle catalog values, and in the case where there is no catalog value, actual measurement values are used. In the case where the directory value exists in a range, a central value is basically used.

< Polymer >

(Preparation of acrylic Polymer 1 solution)

N-Butyl Acrylate (BA) as a monomer component: 87 parts by mass of 2-methoxyethyl acrylate (MEA): 10 parts by mass of Acrylic Acid (AA): 3 parts by mass of ethyl acetate as a polymerization solvent: 150 parts by mass was charged into a separable flask, and stirred for 1 hour while introducing nitrogen gas. After oxygen in the polymerization system was removed as described above, 2' -Azobisisobutyronitrile (AIBN) was added as a polymerization initiator: 0.2 part by mass, the temperature was raised to 63℃and the reaction was carried out for 6 hours. Then, ethyl acetate was added to obtain an acrylic polymer 1 solution having a solid content concentration of 40 mass%. The weight average molecular weight of the obtained acrylic polymer 1 was 75 ten thousand. In addition, tg is-45 ℃.

(Preparation of acrylic Polymer 2 solution)

N-Butyl Acrylate (BA) as a monomer component: 95 parts by mass of Acrylic Acid (AA): 5 parts by mass of ethyl acetate as a polymerization solvent: 150 parts by mass was charged into a separable flask, and stirred for 1 hour while introducing nitrogen gas. After oxygen in the polymerization system was removed as described above, 2' -Azobisisobutyronitrile (AIBN) was added as a polymerization initiator: 0.2 part by mass, the temperature was raised to 63℃and the reaction was carried out for 6 hours. Then, ethyl acetate was added to obtain an acrylic polymer 2 solution having a solid content concentration of 40 mass%. The weight average molecular weight of the obtained acrylic polymer 2 was 60 ten thousand. In addition, tg is-47 ℃.

< Polymer No. 2 >

Cyclohexyl methacrylate (CHMA) as monomer component: 95 parts by mass of Acrylic Acid (AA): 5 parts by mass of ethyl acetate as a polymerization solvent: 300 parts by mass of 2-mercaptoethanol (thioglycol) as a chain transfer agent: 3 parts by mass were put into a separable flask and stirred for 1 hour while introducing nitrogen gas. After oxygen in the polymerization system was removed as described above, 2' -Azobisisobutyronitrile (AIBN) was added as a polymerization initiator: 0.2 part by mass, and then, raising the temperature to 65℃and carrying out the reaction for 3 hours, followed by carrying out the reaction at 75℃for 2 hours, to obtain a2 nd polymer solution having a solid content concentration of 25% by mass. The Tg of the 2 nd polymer obtained was 68 ℃.

Examples 1 to 20 and comparative examples 1 to 5

< Preparation of adhesive composition >

The acrylic polymer solution, the 2 nd polymer solution, the ethyl acetate solution of each adhesion promoter having a solid content concentration of 50 mass%, the crosslinking agent, the ionic liquid, and the catalyst, which are shown below, were used as described in tables 1 and 2, and stirred and mixed to obtain adhesive compositions (solutions) for electric separation of examples 1 to 20 and comparative examples 1 to 5 having a solid content concentration of 25 mass%. In the adjustment of the solid content concentration of the adhesive composition, ethyl acetate was used. The amounts of the components are shown in tables 1 to 2.

The values of the components in tables 1 to 2 refer to parts by mass. The blending amounts (parts by mass) of the polymer, the 2 nd polymer and the tackifier are each expressed as a blending amount (parts by mass) in terms of solid content.

< Preparation of electric Release adhesive layer >

The adhesive composition (solution) for electric separation obtained above was applied to the release treated surface of the surface-release-treated polyethylene terephthalate release liner (trade name "MRF38", mitsubishi Chemical Corporation) in a uniform thickness using an applicator. Next, heat drying was performed at 150 ℃ for 3 minutes, and a release treated surface of a surface-release treated polyethylene terephthalate release liner (trade name "MRE38", manufactured by Mitsubishi Chemical Corporation) was laminated onto the adhesive layer using a hand roller, to obtain an electrically-release adhesive layer (adhesive sheet) having a thickness of 60 μm.

< Production of Single-sided adhesive sheet with substrate >

The obtained electrically-peelable pressure-sensitive adhesive layer (pressure-sensitive adhesive sheet) was formed into a sheet having a size of 10mm×80mm, and a release liner (MRE 38) was peeled off, and a film with a metal layer (trade name "1005CR", manufactured by Toli Co., ltd., thickness: 12 μm, and a size of 10mm×100 mm) was laminated on the exposed electrically-peelable pressure-sensitive adhesive layer surface to prepare a single-sided pressure-sensitive adhesive sheet with a base material.

< Production of bonded body >

The release liner (MRF 38) of the single-sided pressure-sensitive adhesive sheet with a substrate was peeled off, a stainless steel sheet as an adherend was attached to the peeled surface so that one end of the pressure-sensitive adhesive sheet protruded from the adherend by about 2mm, and the sheet was reciprocated 1 time by a 2kg roller and left to stand at 23℃for 30 minutes, to obtain a joined body composed of the stainless steel sheet 6/the electrically-peelable pressure-sensitive adhesive layer (pressure-sensitive adhesive sheet) 1 '/the film with a metal layer (substrate for electric conduction) 5'. Fig. 4 schematically shows the joined body.

< Product of acid value and content >

The product of the acid value and the content is obtained by multiplying the acid value [ mgKOH/g ] of the tackifier by the content [ parts by mass ] of the tackifier relative to 100 parts by mass of the polymer. The results are shown in tables 1 to 2.

< Evaluation >

(180 Degree peel force)

180 ° Peel test was performed using the bonded bodies of examples and comparative examples. The material to be bonded used was a stainless steel plate (SUS 304, size: 30mm. Times.120 mm).

The adhesive force in the 180℃peel test (tensile speed: 300mm/min, peel temperature: 23 ℃) was measured by peeling in the direction of the arrow in FIG. 4 using a peel tester (trade name "variable angle peel tester YSP", manufactured by Asahi Kabushiki Kaisha Co., ltd.), and 180℃peel force was measured as the initial adhesive force.

It is to be noted that the case where the initial adhesion was 4.0N/cm or more was evaluated as good, and the case where the initial adhesion was less than 4.0N/cm was evaluated as X. The measurement results are shown in tables 1 to 2.

(Electric peeling force)

As the material to be bonded, a stainless steel plate (SUS 316, size: 30 mm. Times.120 mm) was used.

The bonded body was produced by pressing back and forth with a 2kg roller 1 time, and after being left to stand in an environment of 23 ℃ for 30 minutes, the negative electrode and positive electrode of a direct current machine were respectively attached to the portions α and β in fig. 4 of the bonded body before peeling, and voltage application was performed for 30 seconds at a voltage of 30V, and in this state, peeling was performed in the same manner as the 180 ° peel force measurement described above while applying the voltage, and the adhesive force during the voltage application was measured as an electrical peel force.

It is to be noted that the case where the electrical peeling force was 1.0N/cm or less was evaluated as good, and the case where the electrical peeling force was more than 1.0N/cm was evaluated as X. The measurement results are shown in tables 1 to 2.

TABLE 1

TABLE 2

The short term of the ester polymer, urethane polymer, thickener, ionic liquid, crosslinking agent and catalyst in tables 1 to 2 is as follows. Unless otherwise specified, the hydroxyl value of the adhesion promoter to be described below is 0mgKOH/g.

(Polyester-based Polymer)

NP-110S50EO: polyester resin Mitsubishi Chemical Corporation, tg= -50 DEG C

(Urethane Polymer)

UR-V8700: urethane-modified polyester resin, trade name "VYLON UR-V8700", manufactured by eastern spinning corporation

(Adhesion promoter)

PINECRYSTAL KE-311: rosin-based tackifying resin, manufactured by Deskaching chemical industry Co., ltd., acid value of 6mgKOH/g, tg=50deg.C, softening point of 100 deg.C

Pensel D-125: rosin-based tackifying resin, manufactured by Deskaching chemical industry Co., ltd., acid value of 10mgKOH/g, tg=75deg.C, softening point of 125 deg.C

HARITACK 4740: rosin-based tackifying resin, HARIMA CHEMICALS Group, inc. with an acid value of 30mgKOH/g, tg=70deg.C, softening point of 120deg.C

Pensel AZ: rosin-based tackifying resin, manufactured by Deskaching chemical industry Co., ltd., acid value of 43mgKOH/g, tg=50deg.C, softening point of 100 deg.C

Pensel KK: rosin-based tackifying resin, manufactured by the chemical industry Co., ltd., acid value of 15mgKOH/g, tg=120℃, and softening point of 170 DEG C

HARIESTER MSR-4: rosin-based tackifying resin, HARIMA CHEMICALS Group, inc. with acid value of 135mgKOH/g, tg=75deg.C, softening point of 125 deg.C

(Ionic liquid)

AS-110: cation: 1-ethyl-3-methylimidazolium cation, anion: bis (fluorosulfonyl) imide anion, trade name "ELEXCEL AS-110", manufactured by first Industrial pharmaceutical Co., ltd

(Crosslinking agent)

V-05: polycarbodiimide resin, trade name "CARBODILITE V-05", nisshinbo Chemical Inc

Coronete L: isocyanate-based crosslinking agent, TOSOH Co., ltd

(Catalyst)

ZC-150: zirconium acetylacetonate, trade name "ORGATIX ZC-150", matsumoto FINE CHEMICAL co., ltd

In the electrically-peelable adhesive layers formed from the adhesive compositions of examples 1 to 20, the product of the acid value [ mgKOH/g ] of the tackifier and the content [ parts by mass ] of the tackifier relative to 100 parts by mass of the polymer was less than 1200, and therefore, the initial adhesion was high and the electrically-peelable properties were excellent. Further, since the electrically-peelable adhesive layers formed from the adhesive compositions of examples 11 to 20 further contained the 2 nd polymer, further improvements in initial adhesion and electrical peelability were observed.

The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the claims, and embodiments in which technical means disclosed in the different embodiments are appropriately combined are also included within the technical scope of the present invention.

While various embodiments have been described above with reference to the drawings, it is needless to say that the present invention is not limited to the examples. It is obvious to those skilled in the art that various changes and modifications can be made within the scope of the present invention as defined in the appended claims, and it is understood that they are naturally within the technical scope of the present invention. The components in the above embodiments may be arbitrarily combined within a range not departing from the gist of the present invention.

The present application has been completed based on Japanese patent applications (Japanese patent application publication Nos. 2021-161475) filed on 9/30/2021, 2022/1/7 (Japanese patent application publication Nos. 2022-001918) and 2022/2/24 (Japanese patent application publication No. 2022-026642), the contents of which are incorporated herein by reference.

Description of the reference numerals

X1, X2 and X3 adhesive sheet

1. Electrically releasable adhesive layer

2. Adhesive layer

3. Substrate material

4. Conductive layer

5-Pass substrate

Claims (11)

1. An adhesive composition comprising a polymer, an ionic liquid and an adhesion promoter,

The product of the acid value [ mgKOH/g ] of the adhesion promoter and the content [ parts by mass ] of the adhesion promoter relative to 100 parts by mass of the polymer is less than 1200.

2. The adhesive composition according to claim 1, wherein the softening point of the tackifier is 100 ℃ or higher.

3. The adhesive composition according to claim 1, wherein the tackifier is contained in an amount of 5 to 50 parts by mass relative to 100 parts by mass of the polymer.

4. The adhesive composition according to claim 1, wherein the tackifier is a terpene-based tackifying resin or a rosin-based tackifying resin.

5. The adhesive composition of claim 1, wherein the anions of the ionic liquid comprise at least 1 selected from the group consisting of bis (fluorosulfonyl) imide anions and bis (trifluoromethanesulfonyl) imide anions.

6. The adhesive composition according to claim 1, wherein the polymer comprises at least 1 selected from the group consisting of polyester-based polymers, urethane-based polymers, and acrylic-based polymers.

7. The adhesive composition of claim 1, further comprising a2 nd polymer having a glass transition temperature (Tg) of 40 to 180 ℃.

8. The adhesive composition according to claim 7, wherein the content of the 2 nd polymer is 1 to 50 parts by mass with respect to 100 parts by mass of the polymer.

9. The adhesive composition of claim 1 for use in electrical stripping.

10. An adhesive sheet comprising an adhesive layer formed from the adhesive composition according to any one of claims 1 to 9.

11. A bonded body comprising the pressure-sensitive adhesive sheet according to claim 10 and a conductive material,

The adhesive layer is adhered to the conductive material.