阅读说明：本技术 粘合剂组合物、粘合片和接合体 (Adhesive composition, adhesive sheet, and joined body ) 是由 沟端香 赤松香织 高岛望花 冈本昌之 于 2019-08-30 设计创作，主要内容包括：本发明涉及粘合剂组合物,其至少包含聚合物和离子液体,其中,利用由所含的成分中的离子液体以外的成分形成的组合物来形成粘合剂层、并将该粘合剂层在22℃、20％RH的环境下放置3天后的、该粘合剂层在频率100Hz时的相对介电常数为5以上。(The present invention relates to an adhesive composition comprising at least a polymer and an ionic liquid, wherein the relative dielectric constant of the adhesive layer at a frequency of 100Hz is 5 or more, when the adhesive layer is formed from a composition comprising components other than the ionic liquid among the contained components and left to stand in an environment of 22 ℃ and 20% RH for 3 days.)

1. And a pressure-sensitive adhesive composition comprising a polymer and an ionic liquid, wherein the pressure-sensitive adhesive layer has a relative dielectric constant of 5 or more at a frequency of 100Hz, when the pressure-sensitive adhesive layer is left to stand in an environment of 22 ℃ and 20% RH for 3 days after the pressure-sensitive adhesive layer is formed from a composition comprising components other than the ionic liquid among the components contained in the pressure-sensitive adhesive composition.

2. An adhesive composition comprising a polymer and an ionic liquid, wherein, after an adhesive layer is formed using the adhesive composition and attached to an aluminum plate formed of A5052P H32 in JIS H4000:2014 and left to stand in an environment of 22 ℃ and 15% RH for 7 days, the capacitance per unit area of the interface of the adhesive layer and the aluminum plate is 0.9 [ mu ] F/cm²The ion conductivity of the pressure-sensitive adhesive layer is 10 [ mu ] S/m or more.

3. The adhesive composition according to claim 2, wherein an adhesive layer is formed using the adhesive composition and attached to an aluminum plate formed of a5052P H32 in JIS H4000:2014, and a capacitance per unit area of an interface of the adhesive layer and the aluminum plate after being left for 7 days in an environment of 22 ℃ and 15% RH is 1.2 μ F/cm²The ion conductivity of the pressure-sensitive adhesive layer is 20. mu.S/m or more.

4. The adhesive composition of any one of claims 1-3, further comprising an ionic solid.

5. The adhesive composition of any one of claims 1 to 4, wherein the polymer comprises an ionic polymer.

6. The adhesive composition according to any one of claims 1 to 5, wherein the polymer contains at least 1 selected from the group consisting of a polyester-based polymer, a urethane-based polymer, and an acrylic polymer having a carboxyl group, an alkoxy group, a hydroxyl group, and/or an amide bond.

7. An adhesive composition comprising a polymer and an ionic liquid, wherein the ionic liquid is contained in an amount of 0.5 to 30 parts by mass and an ionic solid is contained in an amount of 0.5 to 10 parts by mass, relative to 100 parts by mass of the polymer.

8. An adhesive composition comprising a polymer and an ionic liquid, wherein the ionic liquid is contained in an amount of 0.5 to 30 parts by mass per 100 parts by mass of the polymer, and the ionic polymer is contained in an amount of 0.05 to 2 parts by mass in the polymer.

9. An adhesive composition comprising 100 parts by mass of an acrylic polymer and 0.5 to 30 parts by mass of an ionic liquid, wherein the proportion of a polar group-containing monomer to the total monomer components constituting the acrylic polymer is 0.1 to 35% by mass.

10. The adhesive composition according to any one of claims 1 to 9, which is used for electrical peeling.

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

12. A bonded body, comprising:

an adherend having a metal adherend surface; and

the adhesive sheet according to claim 11,

the adhesive layer of the adhesive sheet is bonded to the metal adherend surface.

Technical Field

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

Background

In the manufacturing process of electronic components, there are increasing demands for rework for improving the yield, reuse for decomposing and recovering components after use, and the like. In order to meet such a demand, a double-sided adhesive sheet having a certain adhesive strength and a certain peelability may be used when joining members in an electronic component manufacturing process or the like.

As the double-sided pressure-sensitive adhesive sheet capable of achieving the above-described adhesive strength and peelability, there is known a pressure-sensitive adhesive sheet (electrically-peelable pressure-sensitive adhesive sheet) in which an ionic liquid containing a cation and an anion is used as a component for forming a pressure-sensitive adhesive composition and a voltage is applied to a pressure-sensitive adhesive layer to peel the pressure-sensitive adhesive layer (patent documents 1 to 3).

In the electrically peelable pressure-sensitive adhesive sheets of patent documents 1 to 3, it is considered that cations of the ionic liquid move to the cathode side and are reduced, anions of the ionic liquid move to the anode side and are oxidized by application of a voltage, and the adhesive strength of the adhesive interface is weakened and peeling is facilitated.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2010-037354

Patent document 2: japanese patent No. 6097112

Patent document 3: japanese patent No. 4139851

Disclosure of Invention

Problems to be solved by the invention

In the case of an electrically peelable adhesive sheet, it is preferable that the members are firmly joined when no voltage is applied and can be peeled off with a small force when a voltage is applied. Therefore, in the electrically peelable pressure-sensitive adhesive sheet, it is preferable that the rate of decrease in adhesive strength due to voltage application is large. However, in an environment with low humidity such as winter, for example, there is a problem that the rate of decrease in adhesive strength due to voltage application becomes small.

The present invention has been made in view of the above circumstances, and an object thereof is to provide an adhesive composition which can sufficiently reduce the adhesive strength by applying a voltage even in a low humidity environment, and an adhesive sheet having an adhesive layer formed from the adhesive composition.

Means for solving the problems

According to the studies of the inventors of the present application, the decrease in the rate of decrease in the adhesive strength due to the application of voltage in the low humidity environment is caused by the decrease in the water content of the pressure-sensitive adhesive layer and the difficulty in the movement of cations and anions of the ionic liquid in the low humidity environment.

The inventors of the present application have further made studies and, as a result, have obtained the following findings.

First, it was found that the relative permittivity of a component other than the ionic liquid in the pressure-sensitive adhesive layer has a correlation with the rate of decrease in adhesive strength due to voltage application, and by increasing the relative permittivity, the rate of decrease in adhesive strength due to voltage application can be increased. Further, it was found that even when the water content of the pressure-sensitive adhesive layer is reduced under a low humidity environment, if the relative dielectric constant is large, the electrical peelability is good, that is, the rate of decrease in the adhesive strength due to voltage application is large.

Second, it was found that the ionic conductivity of the pressure-sensitive adhesive layer and the capacitance per unit area of the interface between the pressure-sensitive adhesive layer and the adherend have a correlation with the rate of decrease in adhesive strength due to voltage application, and that the rate of decrease in adhesive strength due to voltage application can be increased by increasing the ionic conductivity and the capacitance per unit area of the interface between the pressure-sensitive adhesive layer and the adherend. Further, it was found that even when the moisture content of the pressure-sensitive adhesive layer is reduced under a low humidity environment, if the ion conductivity and the capacitance per unit area of the interface between the pressure-sensitive adhesive layer and the adherend are large, the electrical peelability is good, that is, the rate of reduction in the adhesive strength by voltage application is large.

One pressure-sensitive adhesive composition of the present invention completed based on the above-mentioned finding 1 is a pressure-sensitive adhesive composition comprising a polymer and an ionic liquid, wherein a pressure-sensitive adhesive layer is formed from a composition comprising components other than the ionic liquid among the components contained in the pressure-sensitive adhesive composition, and the relative dielectric constant of the pressure-sensitive adhesive layer at a frequency of 100Hz is 5 or more after the pressure-sensitive adhesive layer is left to stand in an environment of 22 ℃ and 20% RH for 3 days.

Another adhesive composition of the present invention, which was completed based on the above-mentioned 2 nd finding, is an adhesive composition comprising a polymer and an ionic liquid, wherein an adhesive layer is formed using the adhesive composition and attached to an aluminum plate formed of A5052P H32 in JIS H4000:2014, and after being left for 7 days in an environment of 22 ℃ and 15% RH, the capacitance per unit area of the interface of the adhesive layer and the aluminum plate is 0.9. mu.F/cm²The ion conductivity of the pressure-sensitive adhesive layer is 10 [ mu ] S/m or more.

In one embodiment of the adhesive composition of the present invention, the adhesive composition is used to form an adhesive layer and the adhesive layer is attached to an aluminum plate formed from a5052P H32 in JIS H4000:2014, and the capacitance per unit area of the interface between the adhesive layer and the aluminum plate after the adhesive layer is left to stand in an environment of 22 ℃ and 15% RH for 7 days may be 1.2 μ F/cm²The ion conductivity of the pressure-sensitive adhesive layer may be 20. mu.S/m or more.

In one embodiment of the adhesive composition of the present invention, the adhesive composition may further contain an ionic solid.

In one embodiment of the adhesive composition of the present invention, the polymer may contain an ionic polymer.

In one embodiment of the adhesive composition of the present invention, the polymer may include at least 1 selected from the group consisting of a polyester-based polymer, a urethane-based polymer, and an acrylic polymer having a carboxyl group, an alkoxy group, a hydroxyl group, and/or an amide bond.

In addition, another adhesive composition of the present invention comprises a polymer and an ionic liquid, and comprises 0.5 to 30 parts by mass of the ionic liquid and 0.5 to 10 parts by mass of an ionic solid with respect to 100 parts by mass of the polymer.

The adhesive composition of the present invention further comprises a polymer and an ionic liquid, wherein the ionic liquid is contained in an amount of 0.5 to 30 parts by mass per 100 parts by mass of the polymer, and the ionic polymer is contained in an amount of 0.05 to 2 parts by mass in the polymer.

Another adhesive composition of the present invention is an adhesive composition comprising 100 parts by mass of an acrylic polymer and 0.5 to 30 parts by mass of an ionic liquid, wherein the proportion of a polar group-containing monomer to the total monomer components constituting the acrylic polymer is 0.1 to 35% by mass.

In one embodiment of the present invention, the adhesive composition is used for electrical peeling.

The pressure-sensitive adhesive sheet of the present invention further includes a pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition of the present invention.

Further, the joined body of the present invention comprises: an adherend having a metal adherend surface and the pressure-sensitive adhesive sheet of the invention, wherein the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet of the invention is bonded to the metal adherend surface.

ADVANTAGEOUS EFFECTS OF INVENTION

The adhesive composition of the present invention can sufficiently reduce the adhesive strength by applying a voltage even in a low humidity environment.

Drawings

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

FIG. 2 is a sectional view showing an example of a laminated structure of the pressure-sensitive adhesive sheet of the present invention.

FIG. 3 is a sectional view showing another example of the laminated structure of the pressure-sensitive adhesive sheet of the present invention.

FIG. 4 is a sectional view showing an outline of a 180 DEG peel test in examples.

FIG. 5 is a side view of a composite sample for measuring capacitance and ionic conductivity.

FIG. 6 is a plan view of a composite sample for measuring capacitance and ionic conductivity.

FIG. 7 is an equivalent circuit diagram of a composite sample for measuring capacitance and ionic conductivity.

Detailed Description

Hereinafter, embodiments for carrying out the present invention will be described in detail. The present invention is not limited to the embodiments described below.

[ adhesive composition ]

The adhesive compositions of embodiments 1 and 2 of the present invention each comprise a polymer and an ionic liquid.

The adhesive layer is formed from a composition comprising components other than the ionic liquid among the components contained in the adhesive composition of embodiment 1, and the relative dielectric constant of the adhesive layer at a frequency of 100Hz is 5 or more after the adhesive layer is left to stand in an environment of 22 ℃ and 20% RH for 3 days.

In addition, when an adhesive layer was formed using the adhesive composition of embodiment 2 and attached to an aluminum plate formed of a5052P H32 in JIS H4000:2014 and left to stand at 22 ℃ and 15% RH for 7 days, the capacitance per unit area of the interface between the adhesive layer and the aluminum plate was 0.9 μ F/cm²The ion conductivity of the pressure-sensitive adhesive layer is 10 [ mu ] S/m or more.

These pressure-sensitive adhesive compositions have a property of reducing the adhesive strength by voltage application, and are suitable as pressure-sensitive adhesive compositions for electrical peeling.

The above-mentioned embodiments 1 and 2 are not exclusive, and there are adhesive compositions conforming to both embodiments 1 and 2, and there are adhesive compositions conforming to only either one. The effect of the present invention can be exhibited as long as the adhesive composition is one according to any one of embodiment 1 or embodiment 2.

These adhesive compositions are explained below.

In the present specification, embodiments 1 and 2 of the present invention may be collectively referred to as "the present embodiment".

In the present specification, the adhesive strength when no voltage is applied is sometimes referred to as "initial adhesive strength".

In addition, a composition formed of a component other than the ionic liquid among the components contained in the binder composition may be referred to as a "binder composition containing no ionic liquid".

In addition, the adhesive layer formed by the adhesive composition containing no ionic liquid is sometimes referred to as "an adhesive layer containing no ionic liquid".

Further, the property of decreasing the adhesive force by voltage application may be referred to as "electrical peelability", and the property of increasing the rate of decrease in the adhesive force by voltage application may be referred to as "excellent electrical peelability".

< ingredients of adhesive composition >

(Polymer)

The adhesive composition of the present embodiment contains a polymer. In the present embodiment, 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 partial polymer means a polymer in which at least a part of a monomer or a monomer mixture is partially polymerized.

The polymer in the present embodiment is not particularly limited as long as it is a polymer having adhesion property and generally used as an adhesive, 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 polymer may be used alone or in combination of two or more.

In order to increase the relative permittivity of the components other than the ionic liquid of the obtained pressure-sensitive adhesive layer, and to increase the ionic conductivity of the obtained pressure-sensitive adhesive layer and the capacitance per unit area of the bonding interface to improve the electrical peelability, it is preferable that the relative permittivity of the polymer is large, and from this viewpoint, it is particularly preferable that the polymer in the present embodiment contains at least 1 selected from the group consisting of a polyester-based polymer, a urethane-based polymer, and an acrylic-based polymer having a carboxyl group, an alkoxy group, a hydroxyl group, and/or an amide bond. Since polyester polymers and urethane polymers have hydroxyl groups that are easily polarized at their ends and acrylic polymers having carboxyl groups, alkoxy groups, hydroxyl groups, and/or amide linkages are easily polarized, polymers having a relatively large relative dielectric constant can be obtained by using these polymers. The total content of the polyester polymer and the acrylic polymer having a carboxyl group, an alkoxy group, a hydroxyl group and/or an amide bond in the polymer of the present embodiment is preferably 60% by mass or more, and more preferably 80% by mass or more.

In addition, the polymer in the present embodiment is preferably an acrylic polymer in order to reduce costs, improve productivity, and increase initial adhesion.

That is, the adhesive composition of the present embodiment 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 with 1 to 14 carbon atoms (formula (1) below). Such a monomer unit is suitable for obtaining a large initial adhesion. Furthermore, in order to increase the relative permittivity of the components other than the ionic liquid of the pressure-sensitive adhesive layer, and to increase the ionic conductivity of the obtained pressure-sensitive adhesive layer and the capacitance per unit area of the bonding interface to improve the electrical peelability, the alkyl group R in the following formula (1)^bThe number of carbon atoms of (2) is preferably small, particularly preferably 8 or less, and more preferably 4 or less.

CH₂＝C(R^a)COOR^b (1)

[ R in the formula (1) ]^aIs a hydrogen atom or a methyl group, R^bIs 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 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-decyl (meth) acrylate, n-butyl (meth) acrylate, n-hexyl, N-tridecyl (meth) acrylate and n-tetradecyl (meth) acrylate, and the like. Among them, n-butyl acrylate, 2-ethylhexyl acrylate and isononyl acrylate are preferable. The alkyl (meth) acrylate having an alkyl group with 1 to 14 carbon atoms can be used alone or in combination of two 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 acrylic polymer is 70% by mass or more, a large initial adhesion can be easily obtained.

In order to improve cohesion, heat resistance, crosslinking properties, and the like, the acrylic polymer preferably contains a monomer unit derived from a polar group-containing monomer copolymerizable with the alkyl (meth) acrylate having an alkyl group of 1 to 14 carbon atoms in addition to a monomer unit derived from the alkyl (meth) acrylate. The monomer unit can give a crosslinking point and is suitable for obtaining a large initial adhesion. Further, from the viewpoint of increasing the relative permittivity of the components other than the ionic liquid of the pressure-sensitive adhesive layer, and increasing the ionic conductivity of the obtained pressure-sensitive adhesive layer and the capacitance per unit area of the bonding interface to improve the electrical releasability, it is also preferable to include a monomer unit derived from a polar group-containing monomer.

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

Examples of the alkoxy group-containing monomer include a methoxy group-containing monomer and an ethoxy group-containing monomer. 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 vinyl ether. Particularly preferred are 2-hydroxyethyl (meth) acrylate and 4-hydroxybutyl (meth) acrylate. The hydroxyl group-containing monomers may be used alone or in combination of two or more.

Examples of the amide group-containing monomer include acrylamide, methacrylamide, N-vinylpyrrolidone, N-dimethylacrylamide, N-dimethylmethacrylamide, N-diethylacrylamide, N-diethylmethacrylamide, N' -methylenebisacrylamide, N-dimethylaminopropylacrylamide, N-dimethylaminopropylmethacrylamide, and diacetoneacrylamide. The amide group-containing monomer may be used alone or in combination of two or more.

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

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

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% by mass or more, cohesive force is easily obtained, and therefore, adhesive residue is less likely to occur on the surface of the adherend after the pressure-sensitive adhesive layer is peeled off, and the electrical peelability is improved. When the proportion of the polar group-containing monomer is 30% by mass or less, the pressure-sensitive adhesive layer is easily prevented from being excessively adhered to an adherend and from being peeled off again. In particular, when the content is 2% by mass or more and 20% by mass or less, it is easy to achieve both peelability to an adherend and adhesion between the pressure-sensitive adhesive layer and another layer.

Further, as the monomer component constituting the acrylic polymer, a polyfunctional monomer may be contained in order to introduce a crosslinked structure into the acrylic polymer and easily obtain a desired cohesive force.

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 two 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% by mass, and the lower limit is more preferably 3% by mass. When the content of the polyfunctional monomer is 0.1% by mass or more, flexibility and adhesiveness of the pressure-sensitive adhesive layer are easily improved. When the content of the polyfunctional monomer is 15% by mass or less, the cohesive force does not become excessively high, and appropriate adhesiveness is easily obtained.

The polyester-based polymer is typically a polymer having a structure obtained by condensing a polycarboxylic acid such as a dicarboxylic acid, a derivative thereof (hereinafter also referred to as "polycarboxylic acid monomer"), and 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 examples thereof include 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, and derivatives thereof.

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

Examples of the polyol monomer include, but are not particularly limited to, ethylene glycol, 1, 2-propanediol, 1, 3-propanediol, 2-methyl-1, 3-propanediol, 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-methyloctanediol, 1, 10-decanediol, and derivatives thereof.

The polyol monomers may be used alone or in combination of two or more.

The polymer of the present embodiment may contain an ionic polymer. The ionic polymer is a polymer having an ionic functional group. Since the polymer contains an ionic polymer, the relative dielectric constant of the polymer is increased, and the electrical releasability is improved. When the polymer contains an ionic polymer, the content of the ionic polymer is preferably 0.05 parts by mass or more and 2 parts by mass or less with respect to 100 parts by mass of the polymer.

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

The solution polymerization method is not particularly limited, and includes: a method in which a monomer component, a polymerization initiator, and the like are dissolved in a solvent and heated to polymerize the monomer component and the polymerization initiator, thereby obtaining a polymer solution containing a polymer; and so on.

As the solvent used in the solution polymerization method, various general solvents can be used. Examples of such a solvent (polymerization solvent) 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; and organic solvents such as ketones, e.g., methyl ethyl ketone and methyl isobutyl ketone. The solvent may be used alone or in combination of two or more.

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

The polymerization initiator used in the solution polymerization method is not particularly limited, and examples thereof include a peroxide-based polymerization initiator, an azo-based polymerization initiator, and the like. The peroxide-based polymerization initiator is not particularly limited, and examples thereof include peroxycarbonate, peroxyketone, peroxyketal, hydrogen peroxide, dialkyl peroxide, diacyl peroxide, peroxyester, and the like, and more specifically, benzoyl peroxide, t-butyl hydroperoxide, di-t-butyl peroxide, t-butyl peroxybenzoate, dicumyl peroxide, 1-bis (t-butylperoxy) -3,3, 5-trimethylcyclohexane, 1-bis (t-butylperoxy) cyclododecane, and the like. The azo polymerization initiator is not particularly limited, and 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 '-azobis (2,4, 4-trimethylpentane), 4, 4' -azobis-4-cyanovaleric acid, 2 '-azobis (2-amidinopropane) dihydrochloride, 2' -azobis [2- (5-methyl-2-imidazolin-2-yl) propane ] dihydrochloride, and the like, 2,2 '-azobis (2-methylpropionamidine) disulfate, 2' -azobis (N, N '-dimethyleneisobutylamidine) hydrochloride, and 2, 2' -azobis [ N- (2-carboxyethyl) -2-methylpropionamidine ] hydrate. The polymerization initiator may be used alone or in combination of two or more.

The amount of the polymerization initiator to be used is not particularly limited, and is preferably 0.01 part by mass or more and 5 parts by mass or less with respect 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 parts by mass.

The heating temperature in the polymerization by heating 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 or more and 24 hours or less.

The weight average molecular weight of the polymer is not particularly limited, but is preferably 10 to 500 ten thousand. 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 problem that the cohesive force is decreased and adhesive residue is generated on the surface of the adherend after the pressure-sensitive adhesive layer is peeled off can be effectively suppressed. Further, when the weight average molecular weight is 500 ten thousand or less, such a disadvantage that the wettability of the adherend surface after peeling the pressure-sensitive adhesive layer becomes insufficient can be effectively suppressed.

The weight average molecular weight is obtained by measurement by a Gel Permeation Chromatography (GPC) method, and more specifically, is measured under the following conditions using, for example, the trade name "HLC-8220 GPC" (manufactured by Tosoh Corp.) as a GPC measurement apparatus, and is calculated from a standard polystyrene conversion value. (conditions for weight-average molecular weight measurement)

Sample concentration: 0.2% by mass (tetrahydrofuran solution)

Sample injection amount: 10 μ L

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

Reference column: TSKgel SuperH-RC (1 root)

Eluent: tetrahydrofuran (THF)

Flow rate: 0.6mL/min

The detector: differential Refractometer (RI)

Column temperature (measurement temperature): 40 deg.C

The glass transition temperature (Tg) of the polymer is not particularly limited, and is preferably-10 ℃ or lower, more preferably-20 ℃ or lower because a decrease in initial adhesion can be suppressed when the glass transition temperature (Tg) is 0 ℃ or lower. In addition, when the temperature is-40 ℃ or lower, the rate of decrease in adhesive strength by voltage application becomes particularly large, and therefore, the temperature is particularly preferably-50 ℃ or lower.

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

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 entire monomer components

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

The glass transition temperature in the formation of a homopolymer means the glass transition temperature of a homopolymer of the monomer, and means the glass transition temperature (Tg) of a polymer formed by using only a certain monomer (sometimes referred to as "monomer X") as a monomer component. Specifically, numerical values are listed in "Polymer Handbook" (3 rd edition, John Wiley & Sons, Inc, 1989). The glass transition temperature (Tg) of a homopolymer not described in this document is a value obtained by the following measurement method, for example. That is, 100 parts by mass of the monomers X, 0.2 part 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 introduction tube and a reflux condenser, and stirred for 1 hour while introducing nitrogen. After the oxygen in the polymerization system was removed in this manner, the temperature was raised to 63 ℃ and the reaction was carried out for 10 hours. Subsequently, the mixture was cooled to room temperature to obtain a homopolymer solution having a solid content of 33 mass%. Then, 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 groove made of aluminum, and a reversible Heat Flow (specific Heat component) behavior of a homopolymer was obtained at a temperature rise rate of 5 ℃/min under a nitrogen atmosphere of 50ml/min by using a temperature modulation DSC (trade name "Q-2000", manufactured by TA Instruments). The temperature of the point where the curve of the stepwise change in glass transition intersects with a straight line equidistant from a straight line extending the base line on the low temperature side and the base line on the high temperature side of the obtained reversible heat flow in the vertical axis direction when the homopolymer is produced is defined as the glass transition temperature (Tg) in JIS-K-7121.

The content of the polymer in the pressure-sensitive adhesive composition of the present embodiment is preferably 50% by mass or more and 99.9% by mass or less, with the upper limit more preferably 99.5% by mass, even more preferably 99% by mass, and the lower limit more preferably 60% by mass, even more preferably 70% by mass, based on the total amount (100% by mass) of the pressure-sensitive adhesive composition.

(Ionic liquid)

The ionic liquid in the present embodiment is composed of a pair of anions and cations, and is not particularly limited as long as it is a molten salt (normal temperature molten salt) that is liquid at 25 ℃. Examples of anions and cations are given below, but among ionic substances obtained by combining these, a substance that is liquid at 25 ℃ is an ionic liquid, and a substance that is solid at 25 ℃ is an ionic solid described below, not an ionic liquid.

Examples of the anion of the ionic liquid include (FSO)₂)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 ^-And the like. Wherein, as an anion, (FSO)₂)₂N^-[ bis (fluorosulfonyl) imide anion]And (CF)₃SO₂)₂N^-[ bis (trifluoromethanesulfonyl) imide anion]The anion of the sulfonyl imide compound is preferably chemically stable and suitable for improving the electrical peelability.

The cation in the ionic liquid is preferably a nitrogen-containing onium, a sulfur-containing onium, or a phosphorus-containing onium cation in view of chemical stability and suitability for improving electrical peeling property, and more preferably an imidazolium-based, ammonium-based, pyrrolidinium-based, or pyridinium-based cation.

Examples of the imidazolium-based cation include a 1-methylimidazolium cation, a 1-ethyl-3-methylimidazolium cation, a 1-propyl-3-methylimidazolium cation, a 1-butyl-3-methylimidazolium cation, a 1-pentyl-3-methylimidazolium cation, a 1-hexyl-3-methylimidazolium cation, a 1-heptyl-3-methylimidazolium cation, a 1-octyl-3-methylimidazolium cation, a 1-nonyl-3-methylimidazolium cation, a 1-undecyl-3-methylimidazolium cation, a 1-dodecyl-3-methylimidazolium cation, a 1-tridecyl-3-methylimidazolium cation, a, 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-benzyl-3-methylimidazolium cation, 1-butyl-2, 3-dimethylimidazolium cation, 1, 3-bis (dodecyl) imidazolium cation, and the like.

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

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

Examples of the ammonium cation include tetraethylammonium cation, tetrabutylammonium cation, methyltrioctylammonium cation, tetradecyltrihexylammonium cation, glycidyltrimethylammonium cation, and trimethylaminoethylacrylate cation.

The ionic liquid is preferably a cation having a molecular weight of 160 or less, and particularly preferably a cation containing the above-mentioned (FSO) ion, from the viewpoint of increasing the rate of decrease in adhesive strength when voltage is applied₂)₂N^-[ bis (fluorosulfonyl) imide anion]Or (CF)₃SO₂)₂N^-[ bis (trifluoromethanesulfonyl) 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 a 1-methylimidazolium cation, a 1-ethyl-3-methylimidazolium cation, a 1-propyl-3-methylimidazolium cation, a 1-butyl-3-methylimidazolium cation, a 1-pentyl-3-methylimidazolium cation, a 1-butylpyridinium cation, and a 1-hexylpyridinium cation, 1-butyl-3-methylpyridinium cation, 1-butyl-4-methylpyridinium cation, 1-ethyl-1-methylpyrrolidinium cation, 1-butyl-1-methylpyrrolidinium cation, tetraethylammonium cation, glycidyltrimethylammonium cation, and trimethylaminoethylacrylate cation, and the like.

Further, 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 in the formula (2-A)¹Represents a C4-10 hydrocarbon group (preferably C4-8 hydrocarbon group, more preferably C4-6 hydrocarbon group), and may contain a hetero atom, R²And R³The same or different, represent a hydrogen atomThe carbon atom or the 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, and further preferably a hydrocarbon group having 2 to 4 carbon atoms) may contain a hetero atom. Wherein R is absent when the nitrogen atom forms a double bond with an adjacent carbon atom³。

R in the formula (2-B)⁴Represents a C2-10 hydrocarbon group (preferably a C2-8 hydrocarbon group, more preferably a C2-6 hydrocarbon group), and may contain a hetero atom, R⁵、R⁶And R⁷The hydrogen atom or the 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, and further preferably a hydrocarbon group having 2 to 4 carbon atoms) may contain a hetero atom.

R in the formula (2-C)⁸Represents a C2-10 hydrocarbon group (preferably a C2-8 hydrocarbon group, more preferably a C2-6 hydrocarbon group), and may contain a hetero atom, R⁹、R¹⁰And R¹¹The same or different, represents 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, R¹²、R¹³、R¹⁴And R¹⁵The same or different hydrocarbon groups having 1 to 16 carbon atoms (preferably hydrocarbon groups having 1 to 14 carbon atoms, more preferably hydrocarbon groups having 1 to 10 carbon atoms, still more preferably hydrocarbon groups having 1 to 8 carbon atoms, and particularly preferably hydrocarbon groups having 1 to 6 carbon atoms) may contain a hetero atom. Wherein, in the case where X is a sulfur atom, R is absent¹²。

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. It is considered that the cations in the ionic liquid have a property of moving to the cathode side when a voltage is applied in the pressure-sensitive adhesive layer and being localized near the interface between the pressure-sensitive adhesive layer and the adherend. Therefore, in the present invention, the adhesive force during voltage application is reduced with respect to the initial adhesive force, and the electrical peelability is generated. Cations having a molecular weight of 500 or less are preferably used in order to facilitate the movement of cations in the pressure-sensitive adhesive layer to the cathode side and increase the rate of decrease in adhesive strength when a voltage is applied.

Examples of commercially available products of ionic liquids include "ELEXCEL AS-110", "ELEXCEL MP-442", "ELEXCEL IL-210", "ELEXCEL MP-471", "ELEXCEL MP-456", "ELEXCEL AS-804", manufactured by Mitsubishi Materials, and "CIL-312" and "CIL-313" manufactured by JAPAN CARLIT, and the like.

The ionic conductivity of the ionic liquid is preferably 0.1mS/cm or more and 10mS/cm or less. The upper limit of the ionic conductivity is more preferably 5mS/cm, still more preferably 3mS/cm, and the lower limit is more preferably 0.3mS/cm, still more preferably 0.5 mS/cm. By having the ion conductivity in this range, the adhesive strength can be sufficiently reduced even at a low voltage. The ion conductivity can be measured by an AC impedance method using, for example, a frequency response analyzer 1260 manufactured by Solartron corporation.

The content (blending amount) of the ionic liquid in the pressure-sensitive adhesive composition of the present embodiment is preferably 0.5 parts by mass or more in terms of reducing the adhesive strength during voltage application and preferably 30 parts by mass or less in terms of improving the initial adhesive strength, relative to 100 parts by mass of the polymer. 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, it is more preferably 0.6 parts by mass or more, further 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.

(other Components)

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

The adhesive composition of the present embodiment may contain an ionic additive for the purpose of controlling the relative dielectric constant, ionic conductivity, and capacitance. As the ionic additive, for example, an ionic solid can be used.

The ionic solid is an ionic substance which is solid at 25 ℃. The ionic solid is not particularly limited, and for example, among ionic substances obtained by combining the anion and the cation exemplified in the description column of the ionic liquid, those which are solid 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.

The adhesive composition of the present embodiment may contain a crosslinking agent as needed for the purpose of improving creep and shear properties by crosslinking the polymer. Examples of the crosslinking agent include isocyanate crosslinking agents, epoxy crosslinking agents, melamine crosslinking agents, peroxide crosslinking agents, urea crosslinking agents, metal alkoxide crosslinking agents, metal chelate crosslinking agents, metal salt crosslinking agents, oxazoline crosslinking agents, aziridine crosslinking agents, and amine crosslinking agents. Examples of the isocyanate crosslinking agent include toluene diisocyanate and methylene diphenylisocyanate. Examples of the epoxy-based crosslinking agent include N, N' -tetraglycidyl m-xylylenediamine, diglycidylaniline, 1, 3-bis (N, N-diglycidylaminomethyl) 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 two or more.

The adhesive composition of the present embodiment may contain polyethylene glycol or tetraethylene glycol dimethyl ether as necessary for the purpose of assisting the movement of the ionic liquid at the time of voltage application. Polyethylene glycol and tetraethylene glycol dimethyl ether having a number average molecular weight of 100 to 6000 can be used. The content of these components is preferably 0.1 part by mass or more, more preferably 0.5 part by mass or more, and further preferably 1 part by mass or more, and is preferably 30 parts by mass or less, more preferably 20 parts by mass or less, and further preferably 15 parts by mass or less, based on 100 parts by mass of the polymer.

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

The pressure-sensitive adhesive composition of the present embodiment may contain a preservative as necessary for the purpose of suppressing corrosion of a metal adherend. The preservative is not particularly limited, and a commonly known or customary preservative can be used, and for example, a carbodiimide compound, an adsorption-type inhibitor, a chelate-forming metal deactivator, and the like can be used.

Examples of the carbodiimide compound include 1- [3- (dimethylamino) propyl ] -3-ethylcarbodiimide, 1-ethyl-3- (3-dimethylaminopropyl) carbodiimide, N '-dicyclohexylcarbodiimide, N' -diisopropylcarbodiimide, 1-ethyl-3-tert-butylcarbodiimide, N-cyclohexyl-N '- (2-morpholinoethyl) carbodiimide, N' -di-tert-butylcarbodiimide, 1, 3-bis (p-tolyl) carbodiimide, and a polycarbodiimide resin using these compounds as monomers. These carbodiimide compounds may be used alone or in combination of two or more. The content of the carbodiimide compound in the case where the carbodiimide compound is contained in the pressure-sensitive adhesive composition of the present embodiment 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-type inhibitor include alkylamines, carboxylates, carboxylic acid derivatives, and alkylphosphates. The adsorption-type inhibitor may be used alone or in combination of two or more. The content of the alkylamine contained in the adhesive composition of the present embodiment as the adsorption inhibitor 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 content of the carboxylic acid salt as the adsorption inhibitor in the pressure-sensitive adhesive composition of the present embodiment 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 case where the carboxylic acid derivative is contained as the adsorption inhibitor in the pressure-sensitive adhesive composition of the present embodiment 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 alkyl phosphate in the case where the alkyl phosphate is contained as the adsorption inhibitor in the adhesive composition of the present embodiment 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.

As the chelate-forming metal deactivator, for example, a triazole group-containing compound or a benzotriazole group-containing compound can be used. These compounds are preferable because they have a high effect of passivating the surface of a metal such as aluminum and are less likely to affect the adhesion even when they are contained in a binder component. The chelate-forming metal deactivators may be used alone or in combination of two or more. The content of the chelate-forming metal deactivator in the adhesive composition of the present embodiment 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 preservative 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.

The pressure-sensitive adhesive composition of the present embodiment may contain various additives such as a filler, a plasticizer, an antioxidant, a pigment (dye), a flame retardant, a solvent, a surfactant (leveling agent), a rust inhibitor, a tackifier resin, and an antistatic agent. The total content of these components is not particularly limited as long as the effects of the present invention can be exerted, 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 further preferably 5 parts by mass or less, relative to 100 parts by mass of the polymer.

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

As the plasticizer, known and conventional plasticizers used in usual resin compositions and the like can be used, and examples thereof include oils such as paraffin oil, processing oil and the like, liquid rubbers such as liquid polyisoprene, liquid polybutadiene, liquid ethylene-propylene rubber and the like, tetrahydrophthalic acid, azelaic acid, benzoic acid, phthalic acid, trimellitic acid, pyromellitic acid, adipic acid, sebacic acid, fumaric acid, maleic acid, itaconic acid, citric acid, and 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, red lead, lithopone, lead, cadmium, iron, cobalt, aluminum, hydrochloride, and sulfate; organic pigments such as azo pigments and copper phthalocyanine pigments.

Examples of the rust inhibitor include zinc phosphate, tannic acid derivatives, phosphate esters, alkali sulfonates, and various rust-inhibiting pigments.

Examples of the thickener include a titanium coupling agent and a zirconium coupling agent.

The antistatic agent is generally a hydrophilic compound such as a quaternary ammonium salt, polyglycolic acid, or an ethylene oxide derivative.

Examples of the tackifier resin include a rosin-based tackifier resin, a terpene-based tackifier resin, a phenol-based tackifier resin, a hydrocarbon-based tackifier resin, and a ketone-based tackifier resin, and further include a polyamide-based tackifier resin, an epoxy-based tackifier resin, and an elastic-based tackifier resin. The tackifier resins may be used alone or in combination of two or more.

< relative dielectric constant of adhesive layer containing no ionic liquid >

The pressure-sensitive adhesive composition of embodiment 1 is a pressure-sensitive adhesive composition in which a pressure-sensitive adhesive layer (pressure-sensitive adhesive layer not containing an ionic liquid) is formed from a composition (pressure-sensitive adhesive composition not containing an ionic liquid) composed of components other than an ionic liquid among the components contained in the pressure-sensitive adhesive composition, and the relative dielectric constant of the pressure-sensitive adhesive layer at a frequency of 100Hz is 5 or more after the pressure-sensitive adhesive layer is left to stand in an environment of 22 ℃ and 20% RH for 3 days.

The relative permittivity refers to a relative permittivity measured as follows.

First, an adhesive composition containing no ionic liquid was uniformly applied to the release surface of the separator whose surface was subjected to release treatment, and heat-dried at 130 ℃ for 3 minutes, thereby obtaining an adhesive layer containing no ionic liquid with a thickness of 30 μm. Next, the obtained adhesive layer containing no ionic liquid was left to stand at 22 ℃ under an atmosphere of 20% RH for 3 days. Thereafter, the relative dielectric constant was measured under the following conditions.

(conditions for measuring relative permittivity)

The determination method comprises the following steps: capacitance method (apparatus: use Agilent Technologies 4294A Precision Impedance Analyzer)

The electrode is composed of: phi 12.1mm, 0.5mm thick aluminum plate

Counter electrode: aluminum foil with thickness of 60 mu m

And (3) measuring environment: 23 + -1 deg.C, 52 + -1% RH

The relative dielectric constant of the adhesive layer containing no ionic liquid has a correlation with the ease of movement of the ionic liquid in the adhesive layer formed by the adhesive composition containing an ionic liquid. As the relative dielectric constant of the pressure-sensitive adhesive layer containing no ionic liquid is higher, the ionic liquid is more likely to migrate in the pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition containing the ionic liquid, and therefore, the adhesive strength is more likely to decrease when a voltage is applied.

In the pressure-sensitive adhesive composition of embodiment 1, the pressure-sensitive adhesive layer containing no ionic liquid has a relative dielectric constant of 5 or more at a frequency of 100Hz after being left for 3 days in an environment of 22 ℃ and 20% RH, and therefore, a bond having a sufficiently reduced adhesive strength can be formed by applying a voltage even in a low humidity environment.

The relative dielectric constant of the pressure-sensitive adhesive layer containing no ionic liquid can be controlled by appropriately adjusting the polymer component and the kind and content of the ionic additive in the pressure-sensitive adhesive composition within the above-described appropriate ranges, for example.

< ion conductivity of pressure-sensitive adhesive layer and capacitance per unit area of interface between pressure-sensitive adhesive layer and adherend >

With the adhesive composition of embodiment 2, the capacitance per unit area of the interface between the adhesive layer and the aluminum plate after the adhesive layer was formed using the adhesive composition and attached to the aluminum plate formed of a5052P H32 in JIS H4000:2014 and left to stand in an environment of 22 ℃ and 15% RH for 7 days was 0.9 μ F/cm²The ion conductivity of the pressure-sensitive adhesive layer is 10 [ mu ] S/m or more.

The ionic conductivity of the adhesive layer has a correlation with the ease of movement of the ionic liquid in the adhesive layer, and the greater the ionic conductivity, the easier the ionic liquid moves. Further, the capacitance per unit area of the interface between the pressure-sensitive adhesive layer and the adherend has a correlation with the ease with which the ionic liquid is present at the interface between the pressure-sensitive adhesive layer and the adherend, and the greater this capacitance, the greater the ease with which the ionic liquid is present in a large amount at the interface between the pressure-sensitive adhesive layer and the adherend.

In the adhesive composition of embodiment 2, the adhesive composition is used to form an adhesive layer and attach the adhesive layer to an aluminum plate formed of a5052P H32 in JIS H4000:2014, and the adhesive layer and the aluminum plate are left to stand in an environment of 22 ℃ and 15% RH for 7 days, and then the adhesive layer and the aluminum plate are subjected to capacitance per unit areaIs 0.9 mu F/cm²As described above, since the ion conductivity of the pressure-sensitive adhesive layer is 10 μ S/m or more, a bond having sufficiently reduced adhesive strength can be formed by applying a voltage even in a low humidity environment. More preferably, the capacitance per unit area is 1.2. mu.F/cm²The ion conductivity of the pressure-sensitive adhesive layer is 20. mu.S/m or more.

The ionic conductivity and capacitance can be controlled by, for example, appropriately adjusting the polymer component, the type and content of the ionic liquid, and the type and content of the ionic additive in the binder composition within the above-described appropriate ranges.

The ion conductivity and the capacitance are measured as follows.

(preparation of sample for measurement (composite sample))

First, an adhesive composition was uniformly applied to the aluminum deposition surface side of an aluminum deposition PET film 100 (trade name "metal TS", manufactured by TORAY ADVANCED FILM). In this case, a portion not coated with the binder composition is locally provided so that the electrode is in contact with the aluminum deposition surface. Next, the adhesive layer 200 was formed by heat drying at 130 ℃ for 3 minutes, and an adhesive sheet sample was obtained.

Thereafter, the adhesive surface of the obtained adhesive sheet sample was attached to an aluminum plate 300(a5052P H32(JIS H4000:2014)), to obtain a joint body sample 400 in the shape shown in fig. 5 and 6. Fig. 5 is a side view, and fig. 6 is a plan view.

(measurement of capacitance and ion conductivity)

For measurement of capacitance and ionic conductivity, an LCR meter (for example, IM3533 manufactured by japanese electrical machinery corporation) was used.

First, an ac voltage of 0.5V was applied between the aluminum plate 300 and the aluminum deposition surface of the aluminum deposition PET film 100 using an LCR meter, and a cole-cole (cole-cole) graph was obtained by changing the frequency from 0.5Hz to 200 kHz.

Next, the bulk of the adhesive layer 200 is regarded as the resistance component R_adhAnd an electrostatic capacity component C_adhWill be adhered toThe interface of the mixture layer 200 is regarded as the resistance component R_pAnd an electrostatic capacity component C_dlThe equivalent circuit of the joined body sample was set as shown in fig. 7, and the obtained cole-cole plot was fitted by the following formula (a). The resistance component R is₀Is a wiring resistance.

[ mathematical formula 1]

In the formula (a), ω is an angular frequency.

By mixing the obtained C_dlThe capacitance per unit area of the interface between adhesive layer 200 and aluminum plate 300 can be obtained by dividing the area a of the adhesive surface of adhesive layer 200.

Next, the resistance component R of the bulk of the pressure-sensitive adhesive layer 200 obtained from the formula (A) can be used_adhThe ion conductivity σ of the pressure-sensitive adhesive layer was determined by using the following formula (B).

[ mathematical formula 2]

In formula (B), l represents the thickness of the pressure-sensitive adhesive layer, and a represents the area of the pressure-sensitive adhesive surface of the pressure-sensitive adhesive layer 200.

< initial adhesion and adhesion reduction rate by Voltage application >

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

The adhesive composition of the present embodiment has an initial adhesive strength, measured by forming an adhesive sheet and performing a 180 ° peel test as described in the section of examples, of preferably 1.0N/cm or more, more preferably 1.5N/cm or more, still more preferably 2.0N/cm or more, particularly preferably 2.5N/cm or more, and most preferably 3.0N/cm or more. When the initial adhesion is 1.0N/cm or more, the adhesion to the adherend is sufficient, and the adherend is less likely to be peeled off or displaced.

In the adhesive composition of the present embodiment, it is preferable that the adhesive sheet is formed as described in the section of examples, left in an environment of a predetermined temperature and humidity for a predetermined time, and the adhesive strength measured by a 180 ° peel test while applying a voltage of 10V 30 seconds after applying the voltage of 10V is sufficiently small relative to the initial adhesive strength.

That is, the rate of decrease in the adhesive strength determined by the following formula (C) is preferably 60% or more, more preferably 70% or more, and even more preferably 80% or more, based on the adhesive strength measured by the above method (in the following formula (C), simply expressed as "adhesive strength during voltage application") and the initial adhesive strength. The temperature, humidity and time are preferably 22 ℃ 20% RH3 days, more preferably 22 ℃ 15% RH7 days.

The rate of decrease in adhesion (%) { 1- (adhesion in voltage application/initial adhesion) } × 100(C)

The voltage and time for applying the voltage in the electrical peeling are not limited to the above voltages and times, and are not particularly limited as long as the pressure-sensitive adhesive sheet can be peeled. Suitable ranges thereof are shown below.

The applied voltage is preferably 1V or more, more preferably 3V or more, and further preferably 6V or more. Further, it 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, the workability is excellent. The shorter the application time, the better, but it is usually 1 second or more.

< method for producing adhesive composition >

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

[ adhesive sheet ]

(construction of adhesive sheet)

The pressure-sensitive adhesive sheet of the present embodiment is not particularly limited as long as it has at least one pressure-sensitive adhesive layer (hereinafter, also referred to as "electrically peelable pressure-sensitive adhesive layer") formed from the pressure-sensitive adhesive composition of the present embodiment. The pressure-sensitive adhesive sheet of the present embodiment may have a pressure-sensitive adhesive layer (hereinafter, sometimes referred to as "other pressure-sensitive adhesive layer") other than the electrically-peelable pressure-sensitive adhesive layer and not containing an ionic liquid. The adhesive sheet of the present embodiment may further include a substrate, a conductive layer, a substrate for electrical conduction, an intermediate layer, an undercoat layer, and the like, in addition to the above. The pressure-sensitive adhesive sheet of the present embodiment may be in a roll form or a sheet form, for example. The term "pressure-sensitive adhesive sheet" also includes "pressure-sensitive adhesive tape". That is, the pressure-sensitive adhesive sheet of the present embodiment may be a pressure-sensitive adhesive tape having a tape-like form.

The pressure-sensitive adhesive sheet of the present embodiment may be a double-sided pressure-sensitive adhesive sheet that does not have a substrate but includes only an electrically peelable pressure-sensitive adhesive layer, that is, does not include a substrate layer (no substrate). The pressure-sensitive adhesive sheet of the present embodiment may be a double-sided pressure-sensitive adhesive sheet having a substrate and pressure-sensitive adhesive layers (electrically-peelable pressure-sensitive adhesive layers or other pressure-sensitive adhesive layers) on both sides of the substrate. The pressure-sensitive adhesive sheet of the present embodiment may be a one-sided pressure-sensitive adhesive sheet having a substrate and a pressure-sensitive adhesive layer (electrically-peelable pressure-sensitive adhesive layer or another pressure-sensitive adhesive layer) on only one side of the substrate. The pressure-sensitive adhesive sheet of the present embodiment may have a separator (release liner) for protecting the surface of the pressure-sensitive adhesive layer, but the separator is not included in the pressure-sensitive adhesive sheet of the present embodiment.

The structure of the psa sheet of the present embodiment is not particularly limited, and preferred examples thereof include a psa sheet X1 shown in fig. 1, a psa sheet X2 shown in fig. 2 and a psa sheet X3 shown in fig. 3. The pressure-sensitive adhesive sheet X1 is a double-sided pressure-sensitive adhesive sheet without a substrate, which includes only the electrically-peelable pressure-sensitive adhesive layer 1. The pressure-sensitive adhesive sheet X2 is a double-sided pressure-sensitive adhesive sheet with a substrate having a layer structure of the pressure-sensitive adhesive layer 2, the energization substrate 5 (substrate 3 and conductive layer 4), and the electrically peelable pressure-sensitive adhesive layer 1. The pressure-sensitive adhesive sheet X3 is a substrate-attached double-sided pressure-sensitive adhesive sheet having a layer structure of the pressure-sensitive adhesive layer 2, the energization substrate 5 (the substrate 3 and the conductive layer 4), the electrically peelable pressure-sensitive adhesive layer 1, the energization substrate 5 (the substrate 3 and the conductive layer 4), and the pressure-sensitive adhesive layer 2. In the current-carrying substrate 5 of the adhesive sheets X2 and X3 shown in fig. 2 and 3, the substrate 3 is not essential, and may be only the conductive layer 4. In the pressure-sensitive adhesive sheet X2 of fig. 2, the pressure-sensitive adhesive sheet may be a one-sided pressure-sensitive adhesive sheet without the pressure-sensitive adhesive layer 2.

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 made of various plastics (polyolefin resins such as polyethylene and polypropylene, polyester resins such as polyethylene terephthalate, and acrylic resins such as polymethyl methacrylate), and laminates thereof. The substrate may have a single-layer form or a multi-layer form. 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-based substrate such as a metal (e.g., aluminum, magnesium, copper, iron, tin, gold, etc.) foil, a metal plate (e.g., aluminum, magnesium, copper, iron, tin, silver, etc.), a conductive polymer, or the like, or may be a metal vapor deposition film provided on the substrate 3.

The energizing substrate 5 is not particularly limited as long as it is a (energized) substrate having a conductive layer, and examples thereof include a substrate having a metal layer formed on the surface thereof, and examples thereof include substrates having a metal layer formed on the surface thereof by a plating method, a chemical vapor deposition method, sputtering, or the like. Examples of the metal layer include the metals, metal plates, and conductive polymers exemplified above.

In the pressure-sensitive adhesive sheet X1, the double-sided adherend is preferably an adherend having a metal-adherend surface. In the psa sheet X2, the adherend on the electrically-peelable psa layer 1 side is preferably an adherend having a metal adherend surface.

The metal-to-be-bonded surface is a surface having conductivity and formed of a metal containing aluminum, copper, iron, magnesium, tin, gold, silver, lead, or the like as a main component, for example, and is preferably a surface formed of a metal containing aluminum. Examples of the adherend having a metal-adherend surface include sheets, members, and plates made of a metal containing aluminum, copper, iron, magnesium, tin, gold, silver, lead, or the like as a main component. The adherend other than the adherend having the metal adherend surface is not particularly limited, and examples thereof include fiber sheets such as paper, cloth, and nonwoven fabric, and films and sheets of various plastics.

The thickness of the electrically peelable pressure-sensitive adhesive layer 1 is preferably 1 μm or more and 1000 μm or less from the viewpoint of initial adhesion. The upper limit of the thickness of the electrically-peelable adhesive layer 1 is more preferably 500 μm, still more preferably 100 μm, and particularly preferably 30 μm, and the lower limit is more preferably 3 μm, still more preferably 5 μm, and particularly preferably 8 μm. In the case where the psa sheet is a substrate-less double-sided psa sheet (psa sheet X1 shown in fig. 1) including only 1 electrically peelable psa layer, the thickness of the electrically peelable psa layer is the thickness of the psa sheet.

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

The thickness of the substrate 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 μm, still more preferably 25 μm.

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, yet more preferably 50 μm, yet more preferably 10 μm, and the lower limit is more preferably 0.01. mu.m, yet more preferably 0.03. mu.m, yet more preferably 0.05. mu.m.

The thickness of the energization base material 5 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 μm, still more preferably 25 μm.

The electrically releasable pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet of the present embodiment and the surface of the other pressure-sensitive adhesive layer can be protected by a separator (release liner). The separator is not particularly limited, and examples thereof include a release liner obtained by treating the surface of a base material (liner base material) such as paper or a plastic film with silicone, and a release liner obtained by laminating the surface of a base material (liner base material) such as paper or a plastic film with a polyolefin resin. The thickness of the separator is not particularly limited, but is preferably 10 μm or more and 100 μm or less.

The thickness of the pressure-sensitive adhesive sheet of the present embodiment is preferably 20 μm or more and 3000 μm or less. The upper limit of the thickness is more preferably 1000. mu.m, still more preferably 300. mu.m, particularly preferably 200. mu.m, 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 or more and 2000 μm or less. The upper limit of the thickness is more preferably 1000. mu.m, still more preferably 200. mu.m, and the lower limit is more preferably 80 μm, 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 100 μm or more and 3000 μm or less. The upper limit of the thickness is more preferably 1000 μm, and still more preferably 300. mu.m, and the lower limit is more preferably 150 μm, and still more preferably 200. mu.m.

(method for producing adhesive sheet)

The adhesive sheet of the present embodiment can be produced by a known or conventional production method. The electrically peelable pressure-sensitive adhesive layer in the pressure-sensitive adhesive sheet of the present embodiment may be prepared by a method in which a solution obtained by dissolving the pressure-sensitive adhesive composition of the present embodiment in a solvent as necessary is applied to a separator, and dried and/or cured. The other pressure-sensitive adhesive layer may be prepared by a method of applying a solution obtained by dissolving a pressure-sensitive adhesive composition containing no ionic liquid and no additive in a solvent as required to a separator, and drying and/or curing the solution. It is to be noted that the solvent and the separator may be those listed above.

In the coating, a conventional coater (e.g., a gravure roll coater, a reverse roll coater, a contact roll coater, a dip roll coater, a bar coater, a knife coater, a spray roll coater, etc.) may be used.

The electrically peelable pressure-sensitive adhesive layer and the other pressure-sensitive adhesive layer can be produced by the above method, and the pressure-sensitive adhesive sheet of the present embodiment can be produced by appropriately laminating the electrically peelable pressure-sensitive adhesive layer and the other pressure-sensitive adhesive layer on the substrate, the conductive layer, and the energization substrate. Instead of the separator, the adhesive composition may be applied to a substrate, a conductive layer, or a substrate for electrical conduction to produce an adhesive sheet.

(method for electrically peeling adhesive sheet)

The pressure-sensitive adhesive sheet of the present embodiment can be peeled off from an adherend in the following manner: by applying a voltage to the electrically peelable adhesive layer, a potential difference is generated in the thickness direction of the electrically peelable adhesive layer. For example, in the case where the pressure-sensitive adhesive sheet X1 is an adherend having metal-adherend surfaces on both sides, peeling can be performed by applying a voltage to the electrically peelable pressure-sensitive adhesive layer by passing a current through the metal-adherend surfaces on both sides. In the case where the electrically peelable pressure-sensitive adhesive layer side of the pressure-sensitive adhesive sheet X2 is an adherend having a metal adherend surface, peeling can be performed by applying a voltage to the electrically peelable pressure-sensitive adhesive layer by passing a current through the electrically conductive adherend and the electrically conductive layer 4. In the case of the pressure-sensitive adhesive sheet X3, peeling can be performed by applying a voltage to the electrically peelable pressure-sensitive adhesive layer by passing a current through the double-sided conductive layer 4. The energization is preferably performed by connecting terminals to one end and the other end of the pressure-sensitive adhesive sheet to apply a voltage to the entire 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 the metal adherend surface. In the case of peeling, water may be added to the interface between the metal adherend surface and the electrically peelable pressure-sensitive adhesive layer, and then a voltage may be applied.

(use of adhesive sheet)

As conventional re-peeling techniques, there are an adhesive layer that is peeled off by curing with Ultraviolet (UV) radiation and an adhesive layer that is peeled off by heat. Pressure-sensitive adhesive sheets using such pressure-sensitive adhesive layers cannot be used when Ultraviolet (UV) irradiation is difficult, when members to be adhered are damaged by heat, or the like. The pressure-sensitive adhesive sheet of the present embodiment having the electrically peelable pressure-sensitive adhesive layer described above can be easily peeled off by applying a voltage without damaging members to be adhered, because ultraviolet light or heat is not used. Therefore, the adhesive sheet of the present embodiment is suitable for use in fixing a secondary battery (for example, a lithium ion battery pack) used in a mobile terminal such as a smartphone, a mobile phone, a notebook computer, a video camera, and a digital camera to a case.

Examples of the rigid member to be bonded with the adhesive sheet of the present embodiment include a silicon substrate for semiconductor wafers, a sapphire substrate for LEDs, a SiC substrate and a metal base substrate, a TFT substrate and a filter substrate for displays, and a base substrate for organic EL panels. Examples of the brittle member to be bonded with 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-coated Glass for smart phones, an OGS (One Glass Solution) substrate in which a touch panel sensor is attached to the coated 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.

[ conjugant ]

The joined body of the present embodiment has a laminated structure portion including: an adherend having a metal adherend surface and a pressure-sensitive adhesive sheet in which an electrically peelable pressure-sensitive adhesive layer is bonded to the metal adherend surface. Examples of the adherend having a metal adherend surface include adherends formed of a metal containing aluminum, copper, iron, magnesium, tin, gold, silver, lead, or the like as a main component, and a metal containing aluminum is preferable among them.

Examples of the joined body of the present embodiment include: a joined body which is a pressure-sensitive adhesive sheet X1 and which has an adherend having a metal-to-be-bonded surface on both sides of an electrically-peelable pressure-sensitive adhesive layer 1; a joined body which is a pressure-sensitive adhesive sheet X2 and which is provided with an adherend having a metal adherend surface on the electrically peelable pressure-sensitive adhesive layer 1 side and an adherend on the pressure-sensitive adhesive layer 2 side; a bonded body which is a pressure-sensitive adhesive sheet X3 and is provided with adherends on both sides of the pressure-sensitive adhesive layer 2; and so on.

Examples

The present invention will be described more specifically with reference to the following examples, but the present invention is not limited to these examples. The following weight average molecular weights were measured by the Gel Permeation Chromatography (GPC) method according to the method described above.

Examples 1-1 to 1-8 and comparative examples 1-1 to 1-5

< preparation of Polymer solution >

(preparation of acrylic Polymer 1 solution)

n-Butyl Acrylate (BA) as a monomer component: 95 parts by mass, Acrylic Acid (AA): 5 parts by mass, and ethyl acetate as a polymerization solvent: 150 parts by mass were put into a separable flask, and stirred for 1 hour while introducing nitrogen gas. After the oxygen in the polymerization system was removed in this manner, 2' -Azobisisobutyronitrile (AIBN) was added as a polymerization initiator: 0.2 part by mass, heated to 63 ℃ and reacted for 6 hours. Thereafter, ethyl acetate was added to obtain an acrylic polymer 1 solution having a solid content concentration of 40 mass%.

(preparation of acrylic Polymer 2 solution)

n-Butyl Acrylate (BA) as a monomer component: 90 parts by mass, 4-hydroxybutyl acrylate (4 HBA): 10 parts by mass, and ethyl acetate as a polymerization solvent: 150 parts by mass were put into a separable flask, and stirred for 1 hour while introducing nitrogen gas. After the oxygen in the polymerization system was removed in this manner, 2' -Azobisisobutyronitrile (AIBN) was added as a polymerization initiator: 0.2 part by mass, heated to 63 ℃ and reacted for 6 hours. Thereafter, ethyl acetate was added to obtain an acrylic polymer 2 solution having a solid content concentration of 30% by mass.

(preparation of acrylic Polymer 3 solution)

n-Butyl Acrylate (BA) as a monomer component: 67 parts by mass, 2-methoxyethyl acrylate (MEA): 30 parts by mass, Acrylic Acid (AA): 3 parts by mass, and ethyl acetate as a polymerization solvent: 150 parts by mass were put into a separable flask, and stirred for 1 hour while introducing nitrogen gas. After the oxygen in the polymerization system was removed in this manner, 2' -Azobisisobutyronitrile (AIBN) was added as a polymerization initiator: 0.2 part by mass, heated to 63 ℃ and reacted for 6 hours. Thereafter, ethyl acetate was added to obtain an acrylic polymer 3 solution having a solid content concentration of 40 mass%.

(preparation of acrylic Polymer 4 solution)

n-Butyl Acrylate (BA) as a monomer component: 67 parts by mass, Methyl Methacrylate (MMA): 33 parts by mass, and ethyl acetate as a polymerization solvent: 150 parts by mass were put into a separable flask, and stirred for 1 hour while introducing nitrogen gas. After the oxygen in the polymerization system was removed in this manner, 2' -Azobisisobutyronitrile (AIBN) was added as a polymerization initiator: 0.2 part by mass, heated to 63 ℃ and reacted for 6 hours. Thereafter, ethyl acetate was added to obtain an acrylic polymer 4 solution having a solid content concentration of 40 mass%.

(preparation of acrylic Polymer 5 solution)

n-Butyl Acrylate (BA) as a monomer component: 87 parts by mass, 4-hydroxybutyl acrylate (4 HBA): 10 parts by mass, Acrylic Acid (AA): 3 parts by mass, and ethyl acetate as a polymerization solvent: 150 parts by mass were put into a separable flask, and stirred for 1 hour while introducing nitrogen gas. After the oxygen in the polymerization system was removed in this manner, 2' -Azobisisobutyronitrile (AIBN) was added as a polymerization initiator: 0.2 part by mass, heated to 63 ℃ and reacted for 6 hours. Thereafter, ethyl acetate was added to obtain an acrylic polymer 5 solution having a solid content concentration of 30% by mass.

< preparation of adhesive composition >

The acrylic polymer solution obtained in the above, the polymer shown below, a crosslinking agent, an ionic liquid, and an additive were added, stirred, and mixed to obtain adhesive compositions of examples 1-1 to 1-8 and comparative examples 1-1 to 1-5. Table 1 shows the amounts of the respective components.

The values of the components in table 1 are parts by mass. The amount of the polymer (parts by mass) indicates the amount of the solid content in the polymer solution (parts by mass).

The abbreviations for the polymers, crosslinking agents, ionic liquids, and additives in table 1 are as follows.

(Polymer)

VYLON UR-V8700: urethane-modified polyester resin available under the trade name "VYLON UR-V8700", manufactured by Toyo Boseki Co., Ltd

VYLON BX 1001: polyester resin, trade name "VYLON BX 1001", manufactured by Toyo Boseki Co., Ltd

SOMAREX 530: anionic polyacrylamide Polymer (Ionic Polymer) having a trade name of "SOMAREX 530", manufactured by SOMAR corporation

(Ionic liquid)

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

(crosslinking agent)

V-05: polycarbodiimide resin, trade name of CARBODILITE V-05, manufactured by Nisshinbo Chemicals

TAKENATE D110, 110: trimethylolpropane xylylene diisocyanate available under the trade name of TAKENATE D110N, manufactured by Mitsui chemical Co., Ltd

(additives)

EMI-nitrate: 1-Ethyl-3-methylimidazolium nitrate, manufactured by Tokyo chemical industries Ltd

Zn-nitrate: zinc nitrate hexahydrate, Wako pure chemical industries, Ltd

BTC-5B: barium titanate

No. 27776: carbon black

< measurement of relative dielectric constant of adhesive layer containing no Ionic liquid >

The materials were stirred and mixed in the same manner as in examples 1-1 to 1-8 and comparative examples 1-1 to 1-5, except that no ionic liquid was added, and the obtained adhesive composition containing no ionic liquid was applied to the release-treated surface of a polyethylene terephthalate separator (product name "MRF 38", manufactured by mitsubishi resin corporation) whose surface was release-treated so as to have a uniform thickness using an applicator. Next, heat drying was performed at 130 ℃ for 3 minutes to obtain an adhesive layer containing no ionic liquid and having a thickness of 30 μm. Next, the obtained adhesive layer containing no ionic liquid was left to stand in an environment of 22 ℃ and 20% RH for 3 days, and then the relative dielectric constant of the adhesive layer at a frequency of 100kHz was measured under the following conditions in accordance with JIS K6911.

(measurement conditions)

The determination method comprises the following steps: capacitance method (apparatus: use Agilent Technologies 4294A Precision Impedance Analyzer)

The electrode is composed of: phi 12.1mm, 0.5mm thick aluminum plate

Counter electrode: 3oz copper plate

And (3) measuring environment: 23 + -1 deg.C, 52 + -1% RH

< measurement of Water content of electrically peelable adhesive layer >

The electrically peelable pressure-sensitive adhesive layer obtained in the same manner as described above was left for 3 days at 22 ℃ under 20% RH using the pressure-sensitive adhesive compositions of the respective examples, and then the water content of the pressure-sensitive adhesive layer was measured by karl fischer moisture evaporation-coulometry (JIS K0113: 2005). Specifically, the amount of water generated by vaporization by heating at 200 ℃ for 30 minutes was measured using a biogas micro-water measuring apparatus AQ-2100 manufactured by biogas industry, Inc., and the ratio thereof to the weight of the sample before heating was defined as the water content. That is, the water content is determined by the following equation. In Table 1, "-" means that no measurement was performed.

Water content (%) × 100 (water content in karl fischer/total weight of sample before measurement) × 100

< evaluation >

(initial adhesion)

The adhesive composition of each example was applied to a release-treated surface of a polyethylene terephthalate separator (trade name "MRF 38", manufactured by mitsubishi resin corporation) whose surface was release-treated, using an applicator so as to have a uniform thickness. Subsequently, the resultant was dried by heating at 130 ℃ for 3 minutes to obtain an electrically peelable pressure-sensitive adhesive layer (pressure-sensitive adhesive sheet) having a thickness of 30 μm.

The obtained electrically peelable pressure-sensitive adhesive layer (pressure-sensitive adhesive sheet) was then formed into a sheet having a size of 10mm × 80mm, and a metal layer of a film (trade name "BR 1075", manufactured by TORAY ADVANCED FILM, 25 μm thick, 10mm × 100mm in size) with a metal layer as a substrate was attached to the surface without a separator to form a single-sided pressure-sensitive adhesive sheet with a substrate. A separator of a single-sided pressure-sensitive adhesive sheet with a substrate was peeled off, an aluminum plate (A5052P H32(JIS H4000:2014)) as an adherend was attached to the peeled surface so that one end of the pressure-sensitive adhesive sheet protruded by about 2mm from the adherend, and the sheet was pressed back and forth once with a 2kg roller and left to stand at 23 ℃ for 30 minutes to obtain a joined body comprising a stainless steel plate 6/an electrically peelable pressure-sensitive adhesive layer (pressure-sensitive adhesive sheet) 1 '/a film with a metal layer (substrate for electrification) 5'. Fig. 4 shows a schematic diagram of the joined body. Thereafter, the sheet was peeled by a peel tester (trade name "variable angle peel tester YSP", manufactured by Asahi Seiki Seiko Co., Ltd.) by a method indicated by an arrow in FIG. 4, and the adhesive strength in a 180 ℃ peel test (tensile rate: 300mm/min, peeling temperature 23 ℃) was measured. The measurement results are shown in table 1.

(adhesion force in Voltage application)

The adhesive force during voltage application was measured in the same manner as the above initial adhesive force measurement except that the adhesive force was measured in the same manner as the initial adhesive force measurement in the above manner, after being pressed once back and forth with a 2kg roller, left to stand in an environment of 22 ℃ and 20% RH for 3 days, and before peeling, the negative and positive electrodes of a dc motor were attached to the joined body at positions α and β in fig. 4, respectively, and voltage was applied at 10V for 30 seconds. The measurement results are shown in table 1.

(rate of lowering of adhesion)

The initial adhesion force measured by the above method and the adhesion force during voltage application were used to determine the rate of decrease in adhesion force due to voltage application by the following formula (C). The results are shown in Table 1.

The rate of decrease in adhesion (%) { 1- (adhesion in voltage application/initial adhesion) } × 100(C)

[ Table 1]

The adhesive compositions of examples 1-1 to 1-8, in which the adhesive layer was formed from a composition comprising components other than the ionic liquid among the components contained in the adhesive composition and was left to stand in an environment of 22 ℃ and 20% RH for 3 days, had a relative dielectric constant of 5 or more at a frequency of 100Hz, exhibited a large rate of decrease in the adhesive strength by voltage application.

Examples 2-1 to 2-11 and comparative examples 2-1 to 2-3

< preparation of Polymer solution >

(preparation of acrylic Polymer 6 solution)

n-Butyl Acrylate (BA) as a monomer component: 90 parts by mass, Acrylic Acid (AA): 10 parts by mass, and ethyl acetate as a polymerization solvent: 150 parts by mass were put into a separable flask, and stirred for 1 hour while introducing nitrogen gas. After the oxygen in the polymerization system was removed in this manner, 2' -Azobisisobutyronitrile (AIBN) was added as a polymerization initiator: 0.2 part by mass, heated to 63 ℃ and reacted for 6 hours. Thereafter, ethyl acetate was added to obtain an acrylic polymer 6 solution having a solid content concentration of 40% by mass.

(preparation of acrylic Polymer 7 solution)

n-Butyl Acrylate (BA) as a monomer component: 90 parts by mass, 4-hydroxybutyl acrylate (4 HBA): 7 parts by mass, Acrylic Acid (AA): 3 parts by mass, and ethyl acetate as a polymerization solvent: 150 parts by mass were put into a separable flask, and stirred for 1 hour while introducing nitrogen gas. After the oxygen in the polymerization system was removed in this manner, 2' -Azobisisobutyronitrile (AIBN) was added as a polymerization initiator: 0.2 part by mass, heated to 63 ℃ and reacted for 6 hours. Thereafter, ethyl acetate was added to obtain an acrylic polymer 7 solution having a solid content concentration of 30% by mass.

(preparation of acrylic Polymer 8 solution)

n-Butyl Acrylate (BA) as a monomer component: 94 parts by mass, 4-hydroxybutyl acrylate (4 HBA): 3 parts by mass, Acrylic Acid (AA): 3 parts by mass, and ethyl acetate as a polymerization solvent: 150 parts by mass were put into a separable flask, and stirred for 1 hour while introducing nitrogen gas. After the oxygen in the polymerization system was removed in this manner, 2' -Azobisisobutyronitrile (AIBN) was added as a polymerization initiator: 0.2 part by mass, heated to 63 ℃ and reacted for 6 hours. Thereafter, ethyl acetate was added to obtain an acrylic polymer 8 solution having a solid content concentration of 30% by mass.

(preparation of acrylic Polymer 9 solution)

n-Butyl Acrylate (BA) as a monomer component: 77 parts by mass, 2-methoxyethyl acrylate (MEA): 20 parts by mass, Acrylic Acid (AA): 3 parts by mass, and ethyl acetate as a polymerization solvent: 150 parts by mass were put into a separable flask, and stirred for 1 hour while introducing nitrogen gas. After the oxygen in the polymerization system was removed in this manner, 2' -Azobisisobutyronitrile (AIBN) was added as a polymerization initiator: 0.2 part by mass, heated to 63 ℃ and reacted for 6 hours. Thereafter, ethyl acetate was added to obtain an acrylic polymer 9 solution having a solid content concentration of 40 mass%.

(preparation of acrylic Polymer 10 solution)

n-Butyl Acrylate (BA) as a monomer component: 87 parts by mass, 2-methoxyethyl acrylate (MEA): 10 parts by mass, Acrylic Acid (AA): 3 parts by mass, and ethyl acetate as a polymerization solvent: 150 parts by mass were put into a separable flask, and stirred for 1 hour while introducing nitrogen gas. After the oxygen in the polymerization system was removed in this manner, 2' -Azobisisobutyronitrile (AIBN) was added as a polymerization initiator: 0.2 part by mass, heated to 63 ℃ and reacted for 6 hours. Thereafter, ethyl acetate was added to obtain an acrylic polymer 10 solution having a solid content concentration of 40 mass%.

< preparation of adhesive composition >

The acrylic polymer solution obtained in the above, the above-mentioned polymer, a crosslinking agent, an ionic liquid, an additive, or the following ionic liquid and a preservative were added thereto, and stirred and mixed to obtain adhesive compositions of examples 2-1 to 2-11 and comparative examples 2-1 to 2-3. Table 2 shows the amounts of the respective components.

(Ionic liquid)

1-hexyl-pyridinium-bis (trifluorosulfonyl) imide

(preservatives, additives, crosslinking agents)

Irgamet 30: n, N-bis (2-ethylhexyl) -1,2, 4-triazole-1-methylamine available under the trade name Irgamet30, manufactured by BASF

IrgacorrDSSG: disodium sebacate, trade name IrgametDSSG, manufactured by BASF corporation

AminO O: imidazoline derivatives, trade name "Amin O", manufactured by BASF corporation

PEG 400: polyethylene glycol, trade name "PEG 400", Coronate L manufactured by tokyo chemical industries: isocyanate Compound, trade name "Coronate L", manufactured by Tosoh Corp

< measurement of ion conductivity and capacitance per unit area of adhesive layer >

Using the adhesive compositions of the respective examples, measurement samples (composite samples) were prepared as follows, and the capacitance of the adhesive interface and the ionic conductivity of the adhesive layer were determined by the following methods. The results are shown in Table 2.

(preparation of sample for measurement (composite sample))

First, an adhesive composition was uniformly applied to the aluminum deposition surface side of an aluminum deposition PET film 100 (trade name "metal TS", manufactured by TORAY ADVANCED FILM). In this case, a portion not coated with the binder composition is locally provided so that the electrode is in contact with the aluminum deposition surface. Next, heat drying was performed at 130 ℃ for 3 minutes to form the adhesive layer 200, and an adhesive sheet sample was obtained.

Thereafter, the adhesive surface of the obtained adhesive sheet sample was attached to an aluminum plate 300(a5052P H32(JIS H4000:2014)), to obtain a joint body sample 400 in the shape shown in fig. 5 and 6. Fig. 5 is a side view, and fig. 6 is a plan view.

(measurement of capacitance and ion conductivity)

For measurement of capacitance and ionic conductivity, an LCR meter (for example, IM3533 manufactured by japanese electrical machinery corporation) was used.

First, an ac voltage of 0.5V was applied between aluminum plate 300 and the aluminum deposition surface of aluminum deposition PET film 100 using an LCR meter, and a koll-koll graph was obtained by changing the frequency from 0.5Hz to 200 kHz.

Next, the bulk of the adhesive layer 200 is regarded as the resistance component R_adhAnd an electrostatic capacity component C_adhThe parallel circuit (2) is obtained by regarding the interface of the adhesive layer 200 as the resistance component R_pAnd an electrostatic capacity component C_dlThe equivalent circuit of the joined body sample was set as shown in fig. 7, and the obtained cole-cole plot was fitted by the following formula (a). The resistance component R is₀Is a wiring resistance.

[ mathematical formula 3]

In the formula (a), ω is an angular frequency.

By mixing the obtained C_dlThe capacitance per unit area of the interface between adhesive layer 200 and aluminum plate 300 was determined by dividing the area a of the adhesive surface of adhesive layer 200.

Then, the resistance component R of the bulk of the pressure-sensitive adhesive layer 200 obtained from the formula (a) is used_adhThe ion conductivity σ of the pressure-sensitive adhesive layer was determined by using the following formula (B).

[ mathematical formula 4]

In formula (B), l represents the thickness of the pressure-sensitive adhesive layer, and a represents the area of the pressure-sensitive adhesive surface of the pressure-sensitive adhesive layer 200.

< evaluation >

(initial adhesion)

The initial adhesive force was measured in the same manner as in examples 1-1 to 1-8 and comparative examples 1-1 to 1-5, except that an aluminum deposited PET film (trade name "metal TS", manufactured by TORAY ADVANCED FILM) was used as a substrate for the adhesive composition of each example, and an adhesive layer was formed on the aluminum deposited surface. The measurement results are shown in table 2.

(adhesive force during voltage application after storage at 22 ℃ and 20% RH for 3 days)

After being pressed once back and forth by a 2kg roller, the assembly was left for 3 days in an environment of 22 ℃ and 20% RH, and before the separation, the negative and positive electrodes of a dc motor were attached to the assembly at α and β in fig. 4, respectively, and a voltage was applied at 10V for 30 seconds, and the assembly was separated while applying the voltage. The measurement results are shown in table 2.

O: the adhesive strength reduction rate is more than 60%.

X: the bonding force reduction rate is less than 60 percent.

(adhesive force during voltage application after 7 days storage at 22 ℃ and 15% RH)

The adhesive force during voltage application was measured in the same manner as the above initial adhesive force measurement except that the adhesive force was measured in the same manner as the initial adhesive force measurement in the above state, after being pressed once back and forth with a 2kg roller, left to stand in an environment of 22 ℃ and 15% RH for 7 days, and before peeling, the negative and positive electrodes of a dc motor were attached to the joined body at positions α and β in fig. 4, respectively, and voltage was applied at 10V for 10 seconds. The measurement results are shown in table 2.

(rate of lowering of adhesion)

The initial adhesion measured by the above method and the adhesion during voltage application after storage for 7 days in an environment of 22 ℃ and 15% RH were used to determine the rate of decrease in adhesion due to voltage application by the following formula (C).

The results are shown in Table 2.

The rate of decrease in adhesion (%) { 1- (adhesion in voltage application/initial adhesion) } × 100(C)

[ Table 2]

The capacitance per unit area of the interface between the adhesive layer and the aluminum plate after the adhesive layer was formed using the adhesive composition and attached to the aluminum plate formed from A5052P H32 in JIS H4000:2014 and left for 7 days in an environment of 22 ℃ and 15% RH was 0.9. mu.F/cm²The adhesive compositions of examples 2-1 to 2-11, in which the ion conductivity of the adhesive layer was 10. mu.S/m or more, had a large rate of decrease in adhesive strength due to voltage application.

[ examples 3-1 to 3-5]

< preparation of Polymer solution >

(preparation of acrylic Polymer 11 solution)

2-methoxyethyl acrylate (MEA) as a monomer component: 95 parts by mass, 4-hydroxybutyl acrylate (4 HBA): 5 parts by mass were put into a separable flask, and stirred for 1 hour while introducing nitrogen gas. After the oxygen in the polymerization system was removed in this manner, 2' -Azobisisobutyronitrile (AIBN) was added as a polymerization initiator: 0.2 part by mass, heated to 63 ℃ and reacted for 6 hours. Thereafter, ethyl acetate was added to obtain an acrylic polymer 11 solution having a solid content concentration of 30% by mass.

< preparation of adhesive composition >

The acrylic polymer solution obtained in the above, the above-mentioned polymer, a crosslinking agent, an ionic liquid, an additive, or the following additives were added thereto, and stirred and mixed to obtain adhesive compositions of examples 3-1 to 3-5. Table 3 shows the amounts of the respective components.

(additives)

EMIM-MeSO₃: ionic additives, imidazolium salts, manufactured by Tokyo chemical industries, Ltd.

EPOMIN 200: polyethyleneimine, manufactured by Japanese catalyst.

< measurement and evaluation of ion conductivity and capacitance per unit area of pressure-sensitive adhesive layer >

The initial adhesive strength, the adhesive strength and the rate of decrease in adhesive strength after voltage application after storage at 22 ℃ and 20% RH for 3 days, and the adhesive strength and the rate of decrease in adhesive strength after voltage application after storage at 22 ℃ and 15% RH for 7 days were measured in the same manner as in examples 2-1 to 2-11 and comparative examples 2-1 to 2-3. In addition, measurement samples (composite samples) were prepared in the same manner as in examples 2-1 to 2-11 and comparative examples 2-1 to 2-3, and the capacitance at the bonding interface and the ionic conductivity of the pressure-sensitive adhesive layer were determined. The results are shown in Table 3.

[ Table 3]

The capacitance per unit area of the interface between the adhesive layer and the aluminum plate after the adhesive layer was formed using the adhesive composition and attached to the aluminum plate formed from A5052P H32 in JIS H4000:2014 and left for 7 days in an environment of 22 ℃ and 15% RH was 0.9. mu.F/cm²The adhesive compositions of examples 3-1 to 3-5, in which the ion conductivity of the adhesive layer was 10. mu.S/m or more, had a large rate of decrease in adhesive strength due to voltage application.

While the preferred embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and various modifications and substitutions can be made to the above embodiments without departing from the scope of the present invention.

It should be noted that the present application is based on japanese patent application (japanese application 2018-164545) proposed on 3.9.2018, japanese patent application (japanese application 2019-065065) proposed on 28.3.2019 and japanese patent application (japanese application 2019-157325) proposed on 29.8.2019, the contents of which are incorporated herein by reference.

Description of the reference numerals

X1, X2, X3 adhesive sheet

1 electrically peelable pressure-sensitive adhesive layer

2 adhesive layer

3 base material

4 conductive layer

5 base material for electrification

100 aluminum evaporation PET film

200 adhesive layer

300 aluminium plate

400 conjugate sample