Laminate, joined body, and electric / electronic device

Abstract

Provided is a laminate in which it is possible to include, in a photocurable adhesive agent layer, a component that inhibits photocuring.　In the laminate (1), an adhesive agent layer A (2) and an adhesive agent layer B (3) are layered. The adhesive agent layer A (2) contains a polymer and a component that inhibits photocuring. The adhesive agent layer B (3) contains a polymer having a structure derived from a photopolymerization initiator. At least one of the adhesive agent layer A (2) and the adhesive agent layer B (3) preferably contains a corrosion inhibitor. The ratio [thickness per layer of adhesive agent layer A (2) : thickness per layer of adhesive agent layer B (3)] of the thickness per layer of the adhesive agent layer A (2) to the thickness per layer of the adhesive agent layer B (3) is preferably 1:4 to 3:2.

Description

Laminates, bonded structures, and electrical and electronic equipment

[0001] The present invention relates to laminates, bonded structures, and electrical and electronic equipment. More specifically, the present invention relates to laminates, bonded structures formed by bonding such laminates together, and electrical and electronic equipment.

[0002] In recent years, electronic devices such as home appliances, office automation equipment, mobile phones (smartphones, etc.), digital cameras, and PDAs (Personal Digital Assistants) are widely used. For example, mobile phones, a representative portable device, tend to have thinner and larger screens for their main components. Typically, the display part of a portable device consists mainly of an LCD module and a backlight unit, with various sheet-like components layered to exhibit functions such as light emission, reflection, light shielding, and light guidance. Furthermore, recent mobile phones often employ organic electroluminescent displays, which are even more expensive than LCD modules. Adhesive sheets (adhesive tapes) are used for assembling (joining) these components.

[0003] Adhesive sheets used in electronic devices require various properties, including high adhesive strength. For example, in addition to having high adhesive strength, they must not peel off even when subjected to impact, and must not be subjected to strong impacts to components.

[0004] As a double-sided adhesive sheet used in portable electronic devices and possessing excellent impact resistance, for example, those comprising a photocurable adhesive layer disclosed in Patent Documents 1 and 2 are known.

[0005] Japanese Patent Publication No. 2023-8796, International Publication No. 2023 / 282010

[0006] However, since the photocurable adhesive layer hardens and forms upon light irradiation, it was not possible to add components that inhibit photocuring to the adhesive layer.

[0007] The present invention was conceived under these circumstances, and its objective is to provide a laminate that can contain a component that inhibits photocuring in a photocurable adhesive layer. The present invention also provides a bonded body and electrical and electronic equipment comprising the above-mentioned laminate.

[0008] As a result of diligent research to achieve the above objective, the inventors of this invention have found that, in certain laminates, a component that inhibits photocuring can be included in the photocurable adhesive layer. This invention was completed based on these findings.

[0009] In other words, the present invention provides a laminate comprising an adhesive layer A containing a polymer and a component that inhibits photocuring, and an adhesive layer B containing a polymer having a structure derived from a photopolymerization initiator.

[0010] Preferably, the adhesive layer A and / or the adhesive layer B contain a corrosion inhibitor.

[0011] The ratio of the thickness per layer of adhesive layer A to the thickness per layer of adhesive layer B [thickness per layer of adhesive layer A: thickness per layer of adhesive layer B] is preferably 1:4 to 3:2.

[0012] The total amount of the corrosion inhibitor in the laminate is preferably 0.1 to 15% by mass relative to 100% by mass of the total amount of the laminate.

[0013] The gel fraction of the above laminate is preferably 60 to 80% by mass.

[0014] The adhesive layer A preferably contains an electrolyte.

[0015] The above laminate is for fixing components together in electrical and electronic equipment, and it is preferable that the adhesive layer A and the adhesive layer B are double-sided adhesive sheets that provide both adhesive surfaces.

[0016] Furthermore, the present invention provides a bonded body comprising the laminate and a conductive material, wherein the adhesive layer A or the adhesive layer B is attached to the conductive material.

[0017] Furthermore, the present invention provides an electrical and electronic device comprising the above-mentioned laminate, wherein the double-sided adhesive sheet fixes the components together on both adhesive surfaces.

[0018] According to the laminate of the present invention, a photocurable adhesive layer can contain a component that inhibits photocuring. For example, a corrosion inhibitor that inhibits photocuring can be included in the photocurable adhesive layer. Furthermore, since the bonded body and electrical and electronic equipment of the present invention are equipped with a photocurable adhesive layer containing a component that inhibits photocuring, they can have excellent impact resistance while containing the above-mentioned component that inhibits photocuring.

[0019] This is a cross-sectional view of a laminate according to one embodiment of the present invention. This is a cross-sectional view of a laminate according to another embodiment of the present invention. This is a front view showing an example of a portable electronic device comprising the laminate of the present invention. This is a cross-sectional view showing an overview of the 180° peel test method in the embodiment.

[0020] [Laminate] A laminate according to one embodiment of the present invention has a structure in which an adhesive layer A containing a polymer and a component that inhibits photocuring is laminated with an adhesive layer B containing a polymer having a structure derived from a photopolymerization initiator.

[0021] Figure 1 is a cross-sectional view showing one embodiment of the laminate of the present invention. As shown in Figure 1, the laminate (1) comprises an adhesive layer A (2) and an adhesive layer B (3). The adhesive layer A (2) and the adhesive layer B (3) are directly laminated (in contact). A release liner (4) and a release liner (5) are provided on both end faces of the laminate (1), respectively. Note that the release liners (4) and (5) are optional.

[0022] Adhesive layer A(2) contains at least a polymer and a component that inhibits photocuring. In this specification, the component that inhibits photocuring may be referred to as the "curing inhibitor." Adhesive layer B(3) contains at least a polymer having a structure derived from a photopolymerization initiator. That is, adhesive layer B(3) is an adhesive layer that has been cured by using a photopolymerization initiator and irradiating with light to form a polymer. The curing inhibitor in adhesive layer A(2) is a component that inhibits the curing of adhesive layer B(3) by light irradiation. Since the laminate (1) has a structure in which such adhesive layer A(2) and adhesive layer B(3) are laminated, the curing inhibitor in adhesive layer A(2) migrates into the cured adhesive layer B(3), and adhesive layer B(3) can contain the curing inhibitor.

[0023] The above-mentioned curing inhibitor is a component that inhibits photocuring when forming the photocurable adhesive layer B. In other words, adhesive layer B is a photocurable adhesive layer. Furthermore, it is preferable that the light from the above-mentioned photocuring inhibitor and the light from which adhesive layer B cures contain the same wavelength. Examples of such light include ultraviolet light, visible light, and infrared light. Among these, ultraviolet light is preferred. Therefore, it is preferable that the above-mentioned curing inhibitor is a component that inhibits ultraviolet curing, and that adhesive layer B is a photocurable adhesive layer.

[0024] Adhesive layer A (2) and adhesive layer B (3) are pressure-sensitive adhesives whose surfaces are pressure-sensitive adhesive surfaces. As shown in Figure 1, one end face (2a) of the laminate (1) is the adhesive surface of adhesive layer A (2), and the other end face (3a) is the adhesive surface of adhesive layer B (3), so the laminate (1) is a double-sided adhesive sheet. Thus, it is preferable that the laminate of the present invention has adhesive layer A and / or adhesive layer B at both ends.

[0025] Adhesive layers A (2) and B (3) are preferably adhesive layers (electro-peelable adhesive layers) whose adhesive strength decreases and can be peeled off from the adherend by applying a voltage. To increase the recycling and reuse rate of the adherend, there is a growing need for easy dismantling (reworkability), which allows for easy dismantling at any time and by any method. Conventional re-peel technologies include adhesive layers that are cured and peeled off by light irradiation such as ultraviolet light (UV), and adhesive layers that are peeled off by heat. Adhesive sheets using such adhesive layers cannot be used when light irradiation is difficult or when heat damages the adherend. Electro-peelable adhesive layers do not use light or heat, so they can be easily peeled off by applying a voltage without damaging the adherend.

[0026] In Figure 1, adhesive layer A(2) and adhesive layer B(3) are directly laminated, but other layers may be interposed between adhesive layer A(2) and adhesive layer B(3) as long as the curing inhibitor can migrate from adhesive layer A(2) to adhesive layer B(3).

[0027] The laminate of the present invention may comprise only one adhesive layer A and one adhesive layer B, or two or more adhesive layers. An example of the laminate of the present invention comprising two or more adhesive layers A and / or adhesive layers B is a laminate in which adhesive layers A and adhesive layers B are alternately laminated. In such a laminate, the ends of the laminate may be different layers (for example, adhesive layer A and adhesive layer B) or the same layer (for example, adhesive layer A and adhesive layer A, or adhesive layer B and adhesive layer B). When there are two or more adhesive layers A and / or adhesive layers B, the multiple adhesive layers A may be the same adhesive layer, or they may be adhesive layers with different compositions, thicknesses, physical properties, etc. Similarly, the multiple adhesive layers B may be the same adhesive layer, or they may be adhesive layers with different compositions, thicknesses, physical properties, etc.

[0028] Figure 2 is a cross-sectional view showing another embodiment of the laminate of the present invention. As shown in Figure 2, the laminate (1) comprises adhesive layers A and B alternately. Specifically, adhesive layers A1 (21), B (3), and A2 (22) are directly laminated (in contact) in this order from one end to the other. Release liners (4) and (5) are provided on both end faces of the laminate (1), respectively. Note that the release liners (4) and (5) are optional. In Figure 2, adhesive layers A1 (21) and B (3), and adhesive layer A2 (22) and B (3) are directly laminated, but other layers may be interposed between adhesive layer A1 (21) and B (3) and / or between adhesive layer A2 (22) and B (3), to the extent that the curing inhibitory component can migrate from adhesive layer A1 (21) to adhesive layer B (3), or from adhesive layer A2 (22) to adhesive layer B (3).

[0029] When two or more adhesive layers A and / or adhesive layers B are present, the layer configuration of the laminate of the present invention can include, in addition to [adhesive layer A / adhesive layer B / adhesive layer A] as shown in Figure 2, [adhesive layer A / adhesive layer A / adhesive layer B], [adhesive layer A / adhesive layer B / adhesive layer A / adhesive layer B / adhesive layer A], [adhesive layer B / adhesive layer A / adhesive layer B / adhesive layer A / adhesive layer B], and so on.

[0030] <Adhesive Layer A> Adhesive layer A contains at least the polymer and the curing inhibitor component as described above. From the viewpoint that adhesive layer A is preferably an ionization-peelable adhesive layer, it is preferable that adhesive layer A further contains an electrolyte.

[0031] (Polymer) The polymer contained in the adhesive layer A can be any known or conventional polymer, and is not particularly limited, but examples include acrylic polymers, rubber polymers, vinyl alkyl ether polymers, silicone polymers, polyester polymers, polyamide polymers, urethane polymers, fluorine polymers, epoxy polymers, etc. Only one of the above polymers may be used, or two or more may be used.

[0032] The above polymer is preferably a base polymer. In this specification, the base polymer refers to the main component of the polymer component in the adhesive constituting the adhesive layer, for example, the polymer component that is present in more than 50% by mass. The content ratio of the base polymer in the above adhesive layer is preferably 60% by mass or more, and more preferably 70% by mass or more, based on 100% by mass of the total amount of the adhesive layer.

[0033] As for the base polymer, it is preferable that the polymer has a high dielectric constant, from the viewpoint of increasing the dielectric constant of components other than the electrolyte in the adhesive layer A and improving electropenetration. From this viewpoint, polyester polymers and acrylic polymers are preferred as the base polymer. In particular, acrylic polymers are preferred in order to increase cost, productivity, and initial adhesive strength.

[0034] The above-mentioned acrylic polymer is a polymer that contains an acrylic monomer (a monomer having a (meth)acryloyl group in its molecule) as a monomer component constituting the polymer. That is, the above-mentioned acrylic polymer contains constituent units derived from an acrylic monomer. Note that only one type of acrylic polymer may be used, or two or more types may be used. Furthermore, the above-mentioned acrylic polymer may contain only one type of acrylic monomer as a monomer component, or it may contain two or more types. In this specification, "(meth)acrylic" refers to "acrylic" and / or "methacrylic" (either one or both of "acrylic" and "methacrylic"), and the same applies to other terms.

[0035] The above acrylic polymer is preferably a polymer that contains the largest mass percentage of constituent units derived from (meth)acrylic acid ester. Examples of the above (meth)acrylic acid ester include hydrocarbon group-containing (meth)acrylic acid esters which may have alkoxy groups. Examples of hydrocarbon group-containing (meth)acrylic acid esters which may have alkoxy groups include alkyl (meth)acrylic acid esters having linear or branched aliphatic hydrocarbon groups, cycloalkyl (meth)acrylic acid esters having alicyclic hydrocarbon groups, and aryl (meth)acrylic acid esters having aromatic hydrocarbon groups. Only one type of hydrocarbon group-containing (meth)acrylic acid ester which may have alkoxy groups may be used, or two or more types may be used.

[0036] Examples of the above alkyl (meth)acrylate esters include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, butyl (meth)acrylate, isobutyl (meth)acrylate, s-butyl (meth)acrylate, t-butyl (meth)acrylate, pentyl (meth)acrylate, isopentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and methyl (meth)acrylate. Examples include isooctyl (meth)acrylate, nonyl (meth)acrylate, isononyl (meth)acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate, undecyl (meth)acrylate, dodecyl (meth)acrylate (lauryl (meth)acrylate), tridecyl (meth)acrylate, tetradecyl (meth)acrylate, pentadecyl (meth)acrylate, hexadecyl (meth)acrylate, heptadecyl (meth)acrylate, octadecyl (meth)acrylate, nonadecyl (meth)acrylate, and eicosyl (meth)acrylate.

[0037] Among the above alkyl (meth)acrylate esters, alkyl (meth)acrylate esters having linear or branched aliphatic hydrocarbon groups with 1 to 14 carbon atoms (preferably 2 to 8, more preferably 2 to 4) are preferred. When the number of carbon atoms is within the above range, the dielectric constant of the components other than the electrolyte in the adhesive layer A can be increased, and the electropenetration properties can be further improved.

[0038] Examples of the above-mentioned cycloalkyl (meth)acrylates include cyclopropyl (meth)acrylate, cyclobutyl (meth)acrylate, cyclopentyl (meth)acrylate, cyclohexyl (meth)acrylate, 3,3,5-trimethylcyclohexyl (meth)acrylate, cycloheptyl (meth)acrylate, cyclooctyl (meth)acrylate, isobornyl (meth)acrylate, and dicyclopentanyl (meth)acrylate.

[0039] Examples of hydrocarbon group-containing (meth)acrylic acid esters having an alkoxy group include those in which one or more hydrogen atoms in the hydrocarbon group of the above hydrocarbon group-containing (meth)acrylic acid ester are substituted with an alkoxy group, such as 2-methoxymethyl ester, 2-methoxyethyl ester, and 2-methoxybutyl ester of (meth)acrylic acid.

[0040] In order to appropriately exhibit the basic properties such as tackiness of the hydrocarbon group-containing (meth)acrylic acid ester which may have an alkoxy group in the adhesive layer A, the proportion of the hydrocarbon group-containing (meth)acrylic acid ester which may have an alkoxy group in the total monomer components constituting the acrylic polymer is preferably 70% by mass or more, more preferably 80% by mass or more, and even more preferably 85% by mass or more, based on the total amount (100% by mass) of the total monomer components. Furthermore, from the viewpoint of enabling copolymerization with other monomer components and obtaining the effects of those other monomer components, the above proportion may be 99.9% by mass or less, 98% by mass or less, or 95% by mass or less.

[0041] In this specification, the term "monomer component" in the context of "total amount of monomer components constituting the acrylic polymer" refers to a compound having only one polymerizable functional group, and does not include compounds having two or more polymerizable functional groups, such as polyfunctional (meth)acrylates.

[0042] The above acrylic polymer may contain constituent units derived from other monomer components copolymerizable with the hydrocarbon group-containing (meth)acrylic acid ester, for the purpose of modifying it to improve cohesiveness or introduce crosslinking points. Examples of the above other monomer components include polar group-containing monomers such as carboxyl group-containing monomers, hydroxyl group-containing monomers, cyano group-containing monomers, vinyl group-containing monomers, aromatic vinyl monomers, amide group-containing monomers, imide group-containing monomers, amino group-containing monomers, epoxy group-containing monomers, vinyl ether monomers, N-acryloylmorpholine, sulfo group-containing monomers, phosphate group-containing monomers, and acid anhydride group-containing monomers. Each of the above other monomer components may be used individually or in combination of two or more.

[0043] Among the polar group-containing monomers mentioned above, carboxyl group-containing monomers, hydroxyl group-containing monomers, and amide group-containing monomers are preferred due to their excellent cohesiveness. Furthermore, acrylic polymers having carboxyl and hydroxyl groups are preferred because the carboxyl and hydroxyl groups are easily polarized, allowing for a relatively high dielectric constant of the polymer. In particular, carboxyl group-containing monomers are preferred from the viewpoint of obtaining a particularly large initial adhesive strength.

[0044] Examples of the above-mentioned carboxyl group-containing monomers include acrylic acid, methacrylic acid, carboxyethyl (meth)acrylate, carboxypentyl (meth)acrylate, itaconic acid, maleic acid, fumaric acid, crotonic acid, and isocrotonic acid.

[0045] Examples of the above-mentioned hydroxyl group-containing monomers include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, 10-hydroxydecyl (meth)acrylate, 12-hydroxylauryl (meth)acrylate, (4-hydroxymethylcyclohexyl)methyl (meth)acrylate, N-methylol (meth)acrylamide, vinyl alcohol, allyl alcohol, 2-hydroxyethyl vinyl ether, 4-hydroxybutyl vinyl ether, and diethylene glycol monovinyl ether.

[0046] Examples of the above-mentioned cyano group-containing monomers include acrylonitrile and methacrylonitrile.

[0047] Examples of the vinyl group-containing monomers mentioned above include vinyl esters such as vinyl acetate, vinyl propionate, and vinyl laurate.

[0048] Examples of the above-mentioned aromatic vinyl monomers include styrene, chlorostyrene, chloromethylstyrene, α-methylstyrene, and other substituted styrenes.

[0049] Examples of the above-mentioned amide group-containing monomers include acrylamide, methacrylamide, N-vinylpyrrolidone, N,N-dimethylacrylamide, N,N-dimethylmethacrylamide, N,N-diethylacrylamide, N,N-diethylmethacrylamide, N,N'-methylenebisacrylamide, N,N-dimethylaminopropylacrylamide, N,N-dimethylaminopropylmethacrylamide, and diacetoneacrylamide.

[0050] Examples of the above-mentioned imide group-containing monomers include cyclohexylmaleimide, isopropylmaleimide, N-cyclohexylmaleimide, and itaconimide.

[0051] Examples of the above-mentioned amino group-containing monomers include aminoethyl (meth)acrylate, N,N-dimethylaminoethyl (meth)acrylate, and N,N-dimethylaminopropyl (meth)acrylate.

[0052] Examples of the epoxy group-containing monomers mentioned above include glycidyl (meth)acrylate, methylglycidyl (meth)acrylate, and allyl glycidyl ether.

[0053] Examples of the vinyl ether monomers mentioned above include methyl vinyl ether, ethyl vinyl ether, and isobutyl vinyl ether.

[0054] Examples of the above sulfo group-containing monomers include styrene sulfonic acid, allyl sulfonic acid, 2-(meth)acrylamide-2-methylpropanesulfonic acid, (meth)acrylamidepropanesulfonic acid, sulfopropyl (meth)acrylate, and (meth)acryloyloxynaphthalenesulfonic acid.

[0055] Examples of the above-mentioned phosphate group-containing monomers include 2-hydroxyethyl acryloyl phosphate.

[0056] Examples of the above-mentioned acid anhydride monomers include maleic anhydride and itaconic anhydride.

[0057] The total proportion of the polar group-containing monomers in the total monomer components (100% by mass) constituting the above acrylic polymer is not particularly limited, but is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, even more preferably 1% by mass or more, and particularly preferably 2% by mass or more. Furthermore, from the viewpoint of obtaining an adhesive layer A with appropriate flexibility, the total proportion is preferably 35% by mass or less, more preferably 25% by mass or less, and even more preferably 20% by mass or less. When the proportion is 0.1% by mass or more, cohesive force is easily obtained, so that adhesive residue is less likely to be left on the surface of the adherend after peeling off the adhesive layer A, and the electropenetration properties are improved. Furthermore, when the proportion is 35% by mass or less, it is easier to prevent the adhesive layer A from adhering excessively to the adherend and causing excessive peeling. In particular, when the proportion is 2 to 20% by mass, the adhesive strength tends to decrease when voltage is applied.

[0058] The monomer components constituting the above-mentioned acrylic polymer may further include other monomers. Examples of these other monomers include aromatic vinyl compounds such as styrene, substituted styrene (α-methylstyrene, etc.), and vinyltoluene; olefin monomers such as ethylene, propylene, isoprene, butadiene, and isobutylene; and chlorine-containing monomers such as vinyl chloride and vinylidene chloride.

[0059] The proportion of the other monomers in the total amount of all monomer components constituting the above acrylic polymer (100% by mass) may be, for example, 0.05% by mass or more, or 0.5% by mass or more. The above proportion may also be, for example, 20% by mass or less, 10% by mass or less, or 5% by mass or less, and may be substantially absent.

[0060] The weight-average molecular weight (Mw) of the above acrylic polymer is preferably between 100,000 and 5,000,000. The upper limit of the weight-average molecular weight is more preferably 4,000,000, and even more preferably 3,000,000. The lower limit is more preferably 200,000, and even more preferably 300,000. When the weight-average molecular weight is 100,000 or more, the cohesive force is reduced, which effectively suppresses the problem of adhesive residue remaining on the surface of the adherend after peeling off the adhesive layer A. Furthermore, when the weight-average molecular weight is 5,000,000 or less, it effectively suppresses the problem of insufficient wettability on the surface of the adherend after peeling off the adhesive layer A.

[0061] The above weight-average molecular weight was obtained by measurement using gel permeation chromatography (GPC). More specifically, for example, it can be measured using the "HLC-8220GPC" (manufactured by Tosoh Corporation) as a GPC measuring device under the following conditions and calculated using the standard polystyrene equivalent value. (Weight-average molecular weight measurement conditions) ・Sample concentration: 0.2% by mass (tetrahydrofuran solution) ・Sample injection volume: 10 μL ・Sample column: TSKguardcolumn SuperHZ-H (1 tube) + TSKgel SuperHZM-H (2 tubes) ・Reference column: TSKgel SuperH-RC (1 tube) ・Eluent: Tetrahydrofuran (THF) ・Flow rate: 0.6 mL / min ・Detector: Differential refractometer (RI) ・Column temperature (measurement temperature): 40°C

[0062] The glass transition temperature (Tg) of the polymer is not particularly limited, but it is preferably 0°C or lower because it suppresses the decrease in initial adhesive strength, more preferably -10°C or lower, and even more preferably -20°C or lower. Furthermore, it is even more preferable if the temperature is -40°C or lower because the decrease in adhesive strength due to voltage application is particularly large, and especially preferably -50°C or lower.

[0063] The glass transition temperature (Tg) can be calculated, for example, based on the following equation (Y) (Fox equation): 1 / Tg = W1 / Tg1 + W2 / Tg2 + ... + Wn / Tgn (Y) [In equation (Y), Tg is the glass transition temperature of the polymer (unit: K), Tgi (i = 1, 2, ..., n) is the glass transition temperature when monomer i forms a homopolymer (unit: K), and Wi (i = 1, 2, ..., n) represents the mass fraction of monomer i in the total monomer components]. The above equation (Y) is the calculation formula when the polymer is composed of n types of monomer components: monomer 1, monomer 2, ..., monomer n.

[0064] The glass transition temperature when forming a homopolymer refers to the glass transition temperature of the homopolymer of the monomer in question, and specifically refers to the glass transition temperature (Tg) of a polymer formed using only one monomer (sometimes referred to as "monomer X") as the monomer component. The specific values ​​are given in "Polymer Handbook" (3rd edition, John Wiley & Sons, Inc., 1989). Note that the glass transition temperature (Tg) of a homopolymer not listed in the aforementioned literature refers to a value obtained, for example, by the following measurement method: In a reactor equipped with a thermometer, stirrer, nitrogen inlet tube, and reflux condenser, 100 parts by mass of monomer X, 0.2 parts by mass of 2,2'-azobisisobutyronitrile, and 200 parts by mass of ethyl acetate as a polymerization solvent are added, and the mixture is stirred for 1 hour while introducing nitrogen gas. After removing oxygen from the polymerization system in this manner, the temperature is raised to 63°C and the reaction is carried out for 10 hours. Then, the mixture is cooled to room temperature to obtain a homopolymer solution with a solid content of 33% by mass. Next, this homopolymer solution is cast onto a release liner and dried to produce a test sample (sheet-like homopolymer) with a thickness of approximately 2 mm. Then, approximately 1-2 mg of this test sample is weighed into an aluminum open cell, and the reversing heat flow (specific heat component) behavior of the homopolymer is obtained using a temperature-modulated DSC (product name "Q-2000", manufactured by T.A. Instruments Corporation) at a heating rate of 5°C / min under a nitrogen atmosphere of 50 ml / min. Referring to JIS-K-7121, the glass transition temperature (Tg) of the homopolymer is defined as the temperature at the point where a line equidistant in the vertical axis direction from the line extending from the low-temperature baseline and the high-temperature baseline of the obtained reversing heat flow intersects with the curve of the step-like change portion of the glass transition.

[0065] The above-mentioned acrylic polymer is obtained by polymerizing a composition containing at least an acrylic monomer. Polymerization methods other than light irradiation are used because they contain curing inhibitors. Examples include solution polymerization, emulsion polymerization, bulk polymerization, thermal polymerization, and polymerization by irradiation with active energy rays other than light (active energy ray polymerization). Among these, bulk polymerization and thermal polymerization are preferred in terms of the transparency of the adhesive layer A and cost. Furthermore, the resulting acrylic polymer may be a random copolymer, block copolymer, graft copolymer, or any other type.

[0066] Various common solvents may be used in the polymerization of monomer components. Examples of such solvents include esters such as ethyl acetate and n-butyl acetate; aromatic hydrocarbons such as toluene and benzene; aliphatic hydrocarbons such as n-hexane and n-heptane; alicyclic hydrocarbons such as cyclohexane and methylcyclohexane; and organic solvents such as ketones such as methyl ethyl ketone and methyl isobutyl ketone. One or more of these solvents may be used.

[0067] The polymerization initiators, chain transfer agents, emulsifiers, etc., used in the radical polymerization of monomer components are not particularly limited and can be selected and used as appropriate. The weight-average molecular weight of the polymer can be controlled by the amount of polymerization initiator and chain transfer agent used and the reaction conditions, and the appropriate amounts used are adjusted according to the type of agent.

[0068] For polymerization of monomer components, thermal polymerization initiators can be used depending on the type of polymerization reaction. One type of polymerization initiator may be used, or two or more types may be used.

[0069] The above-mentioned thermal polymerization initiators are not particularly limited, but examples include azo polymerization initiators, peroxide polymerization initiators (e.g., persulfates such as dibenzoyl peroxide, tert-butyl permaleate, potassium persulfate, benzoyl peroxide, hydrogen peroxide, etc.), substituted ethane initiators such as phenyl-substituted ethane, aromatic carbonyl compounds, redox polymerization initiators, etc. Among these, the azo polymerization initiator disclosed in Japanese Patent Application Publication No. 2002-69411 is preferred. Examples of the above-mentioned azo polymerization initiators include 2,2'-azobisisobutyronitrile, 2,2'-azobis-2-methylbutyronitrile, 2,2'-azobis(2-methylpropionic acid)dimethyl, and 4,4'-azobis-4-cyanovaleric acid. The amount of thermal polymerization initiator used can be the usual amount, for example, it can be selected from a range of 0.01 to 5 parts by mass, preferably 0.05 to 3 parts by mass, per 100 parts by mass of monomer component.

[0070] The acrylic polymer may have structural components derived from the crosslinking agent. That is, the acrylic polymer may be crosslinked with the crosslinking agent. By using the crosslinking agent, a crosslinked structure can be formed in the acrylic polymer in the adhesive layer A, and the gel fraction can be controlled. When the crosslinking agent is used, a crosslinked structure is formed in the base polymer in the adhesive layer A, and the cohesive force is improved. Only one type of crosslinking agent may be used, or two or more types may be used.

[0071] The above-mentioned crosslinking agents are not particularly limited, but examples include isocyanate-based crosslinking agents, epoxy-based crosslinking agents, melamine-based crosslinking agents, peroxide-based crosslinking agents, urea-based crosslinking agents, metal alkoxide-based crosslinking agents, metal chelate-based crosslinking agents, metal salt-based crosslinking agents, carbodiimide-based crosslinking agents, oxazoline-based crosslinking agents, aziridine-based crosslinking agents, amine-based crosslinking agents, hydrazine-based crosslinking agents, silicone-based crosslinking agents, and silane-based crosslinking agents (silane coupling agents).

[0072] Examples of the above-mentioned carbodiimide-based crosslinking agents include 1-[3-(dimethylamino)propyl]-3-ethylcarbodiimide, 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide, N,N'-dicyclohexylcarbodiimide, N,N'-diisopropylcarbodiimide, 1-ethyl-3-tert-butylcarbodiimide, N-cyclohexyl-N'-(2-morpholinoethyl)carbodiimide, N,N'-di-tert-butylcarbodiimide, 1,3-bis(p-tolyl)carbodiimide, and polycarbodiimide resins using these as monomers.

[0073] Examples of commercially available carbodiimide-based crosslinking agents include the product names "Carbodilite V-03", "Carbodilite V-05", "Carbodilite V-07", "Carbodilite V-09", and "Elastostab H01" (all manufactured by Nisshinbo Chemical Co., Ltd.).

[0074] The content of the crosslinking agent is not particularly limited, but is preferably 0.001 to 50 parts by mass, more preferably 0.01 to 30 parts by mass, and especially preferably 0.5 to 20 parts by mass, based on 100 parts by mass of the total amount of monomer components constituting the acrylic polymer.

[0075] (Curing Inhibiting Component) A corrosion inhibitor is preferred as the curing inhibitor. This is because the metal surface to which the electropenetrating adhesive layer is bonded may corrode due to the electrolyte, and it is desirable to include a corrosion inhibitor in the adhesive layer B. One or more curing inhibitors may be used.

[0076] As for the corrosion inhibitors mentioned above, from the viewpoint of inhibiting photocuring, compounds that scavenge radicals are mentioned, and include carbodiimide compounds, alkylamines having carbon-carbon double bonds, carboxylic acids, carboxylates, carboxylic acid derivatives, and alkyl phosphates. However, carboxylic acids, carboxylates, carboxylic acid derivatives, and alkyl phosphates have high polarity, resulting in low compatibility with the photocurable adhesive layer and making it difficult to incorporate them into adhesive layer B.

[0077] Corrosion of the metal surface is caused by the interaction of carboxyl groups that may be present in the base polymer with cations of ionic substances, resulting in H₂ ＋ One possible cause is that it reacts with the metal, but in the presence of the above carbodiimide compound, the above carboxyl group reacts with the carbodiimide compound and the carboxyl group disappears, H ＋ Since the occurrence of is suppressed, corrosion is thought to be suppressed. The above carbodiimide compound also functions as a crosslinking agent, and those exemplified as carbodiimide-based crosslinking agents above can be used. The amount of the above carbodiimide compound blended into the adhesive layer A is preferably 0.01 parts by mass or more, more preferably 0.1 parts by mass or more, even more preferably 0.2 parts by mass or more, and particularly preferably 0.5 parts by mass or more, per 100 parts by mass of the base polymer. Furthermore, from the viewpoint of achieving higher initial adhesive strength, the blending amount is preferably 10 parts by mass or less, more preferably 7 parts by mass or less, even more preferably 4 parts by mass or less, and particularly preferably 2 parts by mass or less.

[0078] Examples of alkylamines having a carbon-carbon double bond include primary amines, secondary amines, and tertiary amines. Examples of alkylamines having a carbon-carbon double bond include amines having an alkyl group with 1 to 25 carbon atoms and a carbon-carbon double bond, preferably amines having an alkyl group with 3 to 20 carbon atoms. The alkyl group may have a branched chain or may be cyclic, such as a cycloalkyl group. Examples of tertiary amines include imidazoline derivatives. Examples of alkylamines having a hydroxyl group include the trade name "Amine O" (manufactured by BASF Japan Ltd.).

[0079] The amount of alkylamine having a carbon-carbon double bond added to the adhesive layer A is preferably 0.01 parts by mass or more, more preferably 0.1 parts by mass or more, even more preferably 0.2 parts by mass or more, even more preferably 0.5 parts by mass or more, and particularly preferably 0.8 parts by mass or more, per 100 parts by mass of the base polymer. From the viewpoint of having high initial adhesive strength and being able to sufficiently reduce adhesive strength when voltage is applied, the amount added is preferably 20 parts by mass or less, more preferably 15 parts by mass or less, and even more preferably 10 parts by mass or less.

[0080] Examples of the carboxylate salts mentioned above include disodium sebacate and other sodium salts. Examples of commercially available disodium sebacate include the trade name "M138C" (manufactured by CORTEC) and the trade name "Irgacor DSSG" (manufactured by BASF). The amount of the carboxylate salt added to the adhesive layer A is preferably 0.01 parts by mass or more per 100 parts by mass of the base polymer. From the viewpoint of having high initial adhesive strength and allowing the adhesive strength to decrease sufficiently when voltage is applied, the amount added is preferably 10 parts by mass or less.

[0081] Examples of the carboxylic acid derivatives mentioned above include succinic acid derivatives such as alkenyl succinic acid half-esters. A commercially available alkenyl succinic acid half-ester is the product name "Irgacoe L12" (manufactured by BASF). The amount of the carboxylic acid derivative added to the adhesive layer A is preferably 0.01 parts by mass or more per 100 parts by mass of the base polymer. From the viewpoint of having high initial adhesive strength and allowing the adhesive strength to decrease sufficiently when voltage is applied, the amount added is preferably 10 parts by mass or less.

[0082] Examples of commercially available alkyl phosphate compounds include the product name "Colomin W" (manufactured by Kao Corporation). The amount of alkyl phosphate blended into the adhesive layer A is preferably 0.01 parts by mass or more per 100 parts by mass of the base polymer. From the viewpoint of having high initial adhesive strength and allowing the adhesive strength to decrease sufficiently when voltage is applied, the blending amount is preferably 10 parts by mass or less.

[0083] The blending amount of the above-mentioned curing inhibition component in the pressure-sensitive adhesive layer A is preferably 0.01 parts by mass or more, more preferably 1.5 parts by mass or more, still more preferably 0.2 parts by mass or more, still more preferably 0.5 parts by mass or more, and particularly preferably 0.8 parts by mass or more, relative to 100 parts by mass of the base polymer. From the viewpoint of increasing the initial adhesive force, the blending amount is preferably 30 parts by mass or less, more preferably 20 parts by mass or less, still more preferably 15 parts by mass or less, still more preferably 10 parts by mass or less, and particularly preferably 5 parts by mass or less.

[0084] (Electrolyte) The above-mentioned electrolyte that may be contained in the pressure-sensitive adhesive layer A is a substance that can be ionized into anions and cations. Examples of the above-mentioned electrolyte include ionic substances, alkali metal salts, alkaline earth metal salts, organic quaternary ammonium salts, and the like. From the viewpoint of achieving good electrostatic peelability, an ionic substance is preferable as the above-mentioned electrolyte. Only one type of the above-mentioned electrolyte may be used, or two or more types may be used.

[0085] Anions of the above ionic substances are, for example, (FSO ２ ) ２ N － , (CF ３ SO ２ ) ２ N － , (CF ３ CF ２ SO ２ ) ２ N － , (CF ３ SO ２ ) ３ C － , Br － , AlCl ４ － , Al ２ Cl ７ － , NO ３ － , BF ４ － , PF ６ － , CH ３ COO － , CF ３ COO － , CF ３ CF ２ CF２ COO － CF ３ SO ３ － CF ３ (CF ２ ) ３ SO ３ － AsF ６ － SbF ６ － , F (HF) ｎ － These are some examples. Among them, as anions, (FSO ２ ) ２ N － [Bis(fluorosulfonyl)imide anion], (CF ３ SO ２ ) ２ N － Anions of sulfonylime compounds such as [bis(trifluoromethanesulfonyl)imide anions] are commonly used because they are chemically stable and preferable for improving electrolysis properties. In other words, the anions of ionic substances are generally selected from the group consisting of bis(fluorosulfonyl)imide anions and bis(trifluoromethanesulfonyl)imide anions.

[0086] In the above-mentioned ionic substances, the cation is generally selected from the group consisting of nitrogen-containing onium cations, sulfur-containing onium cations, and phosphorus-containing onium cations, as this is preferable for chemical stability and good electrolysis properties. Imidazolium-based, ammonium-based, pyrrolidinium-based, and pyridinium-based cations are more commonly used.

[0087] Examples of imidazolium-based cations include 1-methylimidazolium cation, 1-ethyl-3-methylimidazolium cation, 1-propyl-3-methylimidazolium cation, 1-butyl-3-methylimidazolium cation, 1-pentyl-3-methylimidazolium cation, 1-hexyl-3-methylimidazolium cation, 1-heptyl-3-methylimidazolium cation, 1-octyl-3-methylimidazolium cation, 1-nonyl-3-methylimidazolium cation, 1-undecyl-3-methylimidazolium cation, and 1-dodecyl-3-methylimidazolium cation. Examples include lium cations, 1-tridecyl-3-methylimidazolium cation, 1-tetradecyl-3-methylimidazolium cation, 1-pentadecyl-3-methylimidazolium cation, 1-hexadecyl-3-methylimidazolium cation, 1-heptadecyl-3-methylimidazolium cation, 1-octadecyl-3-methylimidazolium cation, 1-undecyl-3-methylimidazolium cation, 1-benzyl-3-methylimidazolium cation, 1-butyl-2,3-dimethylimidazolium cation, and 1,3-bis(dodecyl)imidazolium cation.

[0088] Examples of pyridinium-based cations include 1-butylpyridinium cation, 1-hexylpyridinium cation, 1-butyl-3-methylpyridinium cation, 1-butyl-4-methylpyridinium cation, and 1-octyl-4-methylpyridinium cation.

[0089] Examples of pyrrolidinium-based cations include 1-ethyl-1-methylpyrrolidinium cation and 1-butyl-1-methylpyrrolidinium cation.

[0090] Examples of ammonium-based cations include tetraethylammonium cation, tetrabutylammonium cation, methyltrioctylammonium cation, tetradecyltrihexylammonium cation, glycidyltrimethylammonium cation, and trimethylaminoethyl acrylate cation.

[0091] As for the above ionic substance, from the viewpoint of significantly reducing the rate of decrease in adhesive strength when voltage is applied, cations with a molecular weight of 160 or less are generally used as constituent cations, and the above (FSO ２ ) ２ N － [Bis(fluorosulfonyl)imide anion] or (CF ３ SO ２ ) ２ N － Ionic substances containing a [bis(trifluoromethanesulfonyl)imide anion] and a cation with a molecular weight of 160 or less are particularly commonly used. Examples of cations with a molecular weight of 160 or less include 1-methylimidazolium cation, 1-ethyl-3-methylimidazolium cation, 1-propyl-3-methylimidazolium cation, 1-butyl-3-methylimidazolium cation, 1-pentyl-3-methylimidazolium cation, 1-butylpyridinium cation, 1-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 trimethylaminoethyl acrylate cation.

[0092] Furthermore, cations represented by the following formulas (2-A) to (2-D) are also commonly used as cations of the above-mentioned ionic substances.

[0093]

[0094] R in equation (2-A) １ R represents a hydrocarbon group having 4 to 10 carbon atoms (preferably a hydrocarbon group having 4 to 8 carbon atoms, more preferably a hydrocarbon group having 4 to 6 carbon atoms), and may contain heteroatoms. ２ and R ３R represents the same or different hydrogen atom or a hydrocarbon group having 1 to 12 carbon atoms (preferably a hydrocarbon group having 1 to 8 carbon atoms, more preferably a hydrocarbon group having 2 to 6 carbon atoms, and even more preferably a hydrocarbon group having 2 to 4 carbon atoms), and may also contain heteroatoms. However, if the nitrogen atom forms a double bond with an adjacent carbon atom, R ３ It does not exist.

[0095] R in equation (2-B) ４ R represents a hydrocarbon group having 2 to 10 carbon atoms (preferably a hydrocarbon group having 2 to 8 carbon atoms, more preferably a hydrocarbon group having 2 to 6 carbon atoms), and may contain heteroatoms. ５ , R ６ , and R ７ These represent, either identically or differently, a hydrogen atom or a hydrocarbon group having 1 to 12 carbon atoms (preferably a hydrocarbon group having 1 to 8 carbon atoms, more preferably a hydrocarbon group having 2 to 6 carbon atoms, and even more preferably a hydrocarbon group having 2 to 4 carbon atoms), and may also contain heteroatoms.

[0096] R in equation (2-C) ８ R represents a hydrocarbon group having 2 to 10 carbon atoms (preferably a hydrocarbon group having 2 to 8 carbon atoms, more preferably a hydrocarbon group having 2 to 6 carbon atoms), and may contain heteroatoms. ９ , R １０ , and R １１ These represent, either identically or differently, 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 also contain heteroatoms.

[0097] In formula (2-D), X represents a nitrogen, sulfur, or phosphorus atom, and R １２ , R １３ , R １４ , and R １５ R represents a hydrocarbon group having 1 to 16 carbon atoms, either identical or different, (preferably a hydrocarbon group having 1 to 14 carbon atoms, more preferably a hydrocarbon group having 1 to 10 carbon atoms, even more preferably a hydrocarbon group having 1 to 8 carbon atoms, and particularly preferably a hydrocarbon group having 1 to 6 carbon atoms), and may contain heteroatoms. However, if X is a sulfur atom, R １２ It does not exist.

[0098] The molecular weight of the cation in the ionic substance described above is, for example, 500 or less, preferably 400 or less, more preferably 300 or less, still more preferably 250 or less, further preferably 200 or less, and particularly preferably 160 or less. In addition, it is usually 50 or more. It is considered that cations in the ionic substance move to the cathode side when a voltage is applied in the pressure-sensitive adhesive layer, and have a property of being biased near the interface between the pressure-sensitive adhesive layer and an adherend. For this reason, the adhesive force during voltage application is reduced relative to the initial adhesive force, and electrically peelable properties are exhibited. Cations having a small molecular weight such as a molecular weight of 500 or less are preferable in that the movement of cations toward the cathode side in the pressure-sensitive adhesive layer becomes easier, and the reduction rate of adhesive force upon voltage application is increased.

[0099] Examples of commercial products of the ionic substance described above include those with the trade name "E1452", trade name "E0599", trade name "M2098", trade name "M2980", trade name "M2981", trade name "M2998" (all manufactured by Tokyo Chemical Industry Co., Ltd.), trade name "HMI-FSI" (manufactured by Mitsubishi Materials Corporation), trade name "CIL-312", and trade name "CIL-313" (all manufactured by Nippon Carlit Co., Ltd.).

[0100] The ionic substance described above contains an anion and a cation, wherein the cation has a saturated alicyclic structure containing an N element, and it is preferable that the ionic substance includes an ionic substance that does not contain a trifluoromethane group (may sometimes be referred to as "ionic substance A"). When the anion of an ionic substance contains a trifluoromethane group, the ionic substance may be subject to regulations on organic fluorine compounds (PFAS). For this reason, even when the pressure-sensitive adhesive layer A contains an ionic substance other than the ionic substance A, it is preferable that the anion of the ionic substance does not contain a trifluoromethane group.

[0101] Examples of anions in the ionic substance A include (FSO ２ ) ２ N － , Br － , AlCl ４ － , Al ２ Cl ７ － , NO ３ － , BF４ － , PF ６ － , CH ３ COO － , AsF ６ － , SbF ６ － , F(HF) ｎ － are mentioned. Among these, (FSO ２ ) ２ N － is more preferred. Examples of commercially available ionic substances A containing such anions include 1-Methyl-1-propylpyrrolidinium Bis(fluorosulfonyl)imide (manufactured by Tokyo Chemical Industry Co., Ltd.) and the product named "Erexel AS-110" (cation: 1-ethyl-3-methylimidazolium cation, anion: bis(fluorosulfonyl)imide anion, manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.).

[0102] The ionic conductivity of the above ionic substance A is 1.0×10 －４ mS / cm or more is preferable. The upper limit of the above ionic conductivity is preferably 20 mS / cm, more preferably 15 mS / cm, still more preferably 10 mS / cm. The lower limit of the above ionic conductivity is more preferably 1 mS / cm, still more preferably 3 mS / cm, particularly preferably 5 mS / cm. When the above ionic conductivity is 1.0×10 －４ mS / cm or more, it is preferable since the adhesive force is sufficiently reduced after voltage application. When the above ionic conductivity is 20 mS / cm or less, it is preferable since the influence of weak external current is suppressed, and electrical peeling can be performed only when a voltage is intentionally applied.

[0103] As the ionic substance having an ionic conductivity of 1.0×10 －４ mS / cm or more, the cation is an imidazolium-based, pyridinium-based, pyrrolidinium-based, piperidinium-based, or ammonium-based cation having a molecular weight of 160 or less, and the anion is (FSO ２ ) ２ N － , (CF ３ SO ２ )２ N － , Cl － , Br － BF ４ － , or PF ６ － Examples include combinations of the following: Of these, 1-methyl-1-propylpyrrolidinium bis(fluorosulfonyl)imide, 1-(2-ethoxymethyl)-1-methylpyrrolidinium bis(fluorosulfonyl)imide, 1-(2-methoxyethyl)-1-methylpyrrolidinium bis(fluorosulfonyl)imide, 1-methyl-1-(2-propen-1-yl)pyrrolidinium bis(fluorosulfonyl)imide, and 1-methyl-1-propylpiperidinium bis(fluorosulfonyl)imide are preferred, and 1-methyl-1-propylpyrrolidinium bis(fluorosulfonyl)imide is more preferred. Furthermore, commercially available examples of such ionic substance A include 1-Methyl-1-propylpyrrolidinium bis(fluorosulfonyl)imide (manufactured by Tokyo Chemical Industry Co., Ltd.) and N-Methyl-N-propylpiperidinium bis(fluorosulfonyl)imide (manufactured by Kanto Chemical Co., Ltd.).

[0104] The above ionic conductivity can be measured, for example, using the AC impedance method with a Solartron 1260 frequency response analyzer.

[0105] The amount of the above-mentioned ionic substance A blended into the adhesive layer A is preferably 0.5 parts by mass or more, more preferably 0.6 parts by mass or more, even more preferably 0.8 parts by mass or more, even more preferably 1.0 part by mass or more, and particularly preferably 1.5 parts by mass or more, per 100 parts by mass of the base polymer, from the viewpoint of sufficiently reducing the adhesive force during voltage application. From the viewpoint of further increasing the initial adhesive force, the blending amount is preferably 30 parts by mass or less, more preferably 20 parts by mass or less, even more preferably 15 parts by mass or less, even more preferably 10 parts by mass or less, and particularly preferably 5 parts by mass or less.

[0106] As the above-mentioned ionic substance, only one type of ionic substance A may be used, two or more types of ionic substance A may be used in combination, or ionic substance A may be used in combination with other ionic substances other than ionic substance A. When ionic substance A is used in combination with the above-mentioned other ionic substances, from the viewpoint of exhibiting a function in which the adhesive strength is sufficiently reduced by the application of voltage even in a low humidity environment, the total amount of ionic substances blended is preferably 0.5 parts by mass or more, more preferably 1.0 part by mass or more, and even more preferably 1.5 parts by mass or more, per 100 parts by mass of base polymer. Furthermore, the above total blending amount is preferably 30 parts by mass or less, more preferably 20 parts by mass or less, and even more preferably 10 parts by mass or less. When two or more types of ionic substances are used in combination, it is preferable to use 2 to 5 types of ionic substances, including ionic substances other than ionic substance A, more preferably 2 to 3 types of ionic substances, and even more preferably 2 types of ionic substances.

[0107] The amount of the above-mentioned ionic substance blended into the adhesive layer A is preferably 0.5 parts by mass or more, more preferably 0.6 parts by mass or more, even more preferably 0.8 parts by mass or more, even more preferably 1.0 part by mass or more, and particularly preferably 1.5 parts by mass or more, per 100 parts by mass of the base polymer, from the viewpoint of further reducing the adhesive force during voltage application. The above blending amount is preferably 30 parts by mass or less, more preferably 20 parts by mass or less, even more preferably 15 parts by mass or less, even more preferably 10 parts by mass or less, and particularly preferably 5 parts by mass or less, from the viewpoint of further increasing the initial adhesive force.

[0108] (Corrosion inhibitor) The adhesive layer (A) may contain a corrosion inhibitor (other corrosion inhibitor) that does not fall under the above-mentioned hardening inhibitory component. Examples of the above-mentioned other corrosion inhibitors include adsorption-type inhibitors and chelate-forming metal deactivators. Only one of the above-mentioned other corrosion inhibitors may be used, or two or more may be used.

[0109] The above-mentioned adsorption-type inhibitor is a compound that physically or chemically adsorbs onto a metal surface to form a protective film and prevent metal corrosion. Examples of the above-mentioned adsorption-type inhibitor include alkylamines (alkylamines that do not have a carbon-carbon double bond). One type of the above-mentioned adsorption-type inhibitor may be used, or two or more types may be used.

[0110] Examples of alkylamines include primary amines, secondary amines, and tertiary amines. Examples of alkylamines include amines having an alkyl group with 1 to 25 carbon atoms, preferably amines having an alkyl group with 3 to 20 carbon atoms. The alkyl group may have a branched chain or be cyclic, such as a cycloalkyl group, but a linear alkyl group is preferred. The alkyl group may also have substituents, such as alkoxy groups. In particular, it is preferable that the alkyl group does not have substituents. Examples of primary amines include propylamine, butylamine, pentylamine, hexylamine, heptylamine, octylamine, nonylamine, decylamine, undecylamine, laurylamine, tridecylamine, tetradecylamine, pentadecylamine, stearylamine, heptadecylamine, and octadecylamine. Examples of the above secondary amines include dicyclohexylamine, diethylamine, dipropylamine, dibutylamine, dihexylamine, dilaurylamine, distearylamine, and diethanolamine. Examples of the above tertiary amines include imidazoline derivatives, trimethylamine, triethylamine, tripropylamine, tributylamine, dimethyloctylamine, dimethyldecylamine, dimethyllaurylamine, dimethyloctylamine, dimethylcoconutamine, dimethylmyristylamine, dimethylpalmitylamine, dimethylstearylamine, dimethylbehenylamine, dilaurylmonomethylamine, and N,N,N',N'-tetramethyl-2,2-dimethyl-1,3-propanediamine.

[0111] Examples of commercially available primary amines include the product names "Farmin 08D", "Farmin 20D", "Farmin 80", "Farmin 86T", and "Farmin CS" (all manufactured by Kao Corporation). Examples of commercially available tertiary amines include the following products: "Farmin DM0898", "Farmin DM1098", "Farmin DM2098", "Farmin DM2285", "Farmin DM2458", "Farmin DM2463", "Farmin DM24C", "Farmin DM4098", "Farmin DM4255", "Farmin DM6098", "Farmin DM6875", "Farmin DM8098", "Farmin DM8680", and "Farmin M2-2095" (all manufactured by Kao Corporation).

[0112] The amount of alkylamine blended into the adhesive layer A is preferably 0.01 parts by mass or more, more preferably 0.1 parts by mass or more, even more preferably 0.2 parts by mass or more, even more preferably 0.5 parts by mass or more, and particularly preferably 0.8 parts by mass or more, per 100 parts by mass of the base polymer. From the viewpoint of having high initial adhesive strength and being able to sufficiently reduce adhesive strength when voltage is applied, the blending amount is preferably 20 parts by mass or less, more preferably 15 parts by mass or less, and even more preferably 10 parts by mass or less.

[0113] The above-mentioned chelate-forming metal deactivators are compounds that prevent metal corrosion by forming a protective film on the metal surface through the formation of complex salts. Examples of the above-mentioned chelate-forming metal deactivators include triazole group-containing compounds and benzotriazole group-containing compounds. These are preferred because they have a high deactivating effect on the surface of metals such as aluminum, and they do not significantly affect the adhesiveness when included in adhesive components.

[0114] Examples of the above triazole group-containing compounds include 1,2,4-triazole, 1,2,3-triazole, 4-amino-1,2,4-triazole, and N,N-bis(2-ethylhexyl)-1,2,4-triazole-1-ylmethaneamine. Examples of the above benzotriazole group-containing compounds include 1,2,3-benzotriazole, methylbenzotriazole, potassium methylbenzotriazole salt, 1-[N,N-bis(2-ethylhexyl)aminomethyl)benzotriazole, 1-(methoxymethyl)-1H-benzotriazole, and 1-(chloromethyl)-1H-benzotriazole.

[0115] Examples of commercially available chelate-forming metal deactivators include the trade names "Irgamet 30", "Irgamet 39", and "Irgamet 42" (all manufactured by BASF), and "M238" (manufactured by CORTEC).

[0116] The amount of the chelate-forming metal deactivator blended into the adhesive layer A is preferably 0.01 parts by mass or more, more preferably 0.1 parts by mass or more, even more preferably 0.2 parts by mass or more, even more preferably 0.5 parts by mass or more, and particularly preferably 0.8 parts by mass or more, per 100 parts by mass of the base polymer. From the viewpoint of having high initial adhesive strength and being able to sufficiently reduce adhesive strength when voltage is applied, the blending amount is preferably 20 parts by mass or less, more preferably 15 parts by mass or less, even more preferably 9 parts by mass or less, even more preferably 5 parts by mass or less, and particularly preferably 3 parts by mass or less.

[0117] The total amount of the above-mentioned other corrosion inhibitors is preferably 0.01 parts by mass or more, more preferably 0.1 parts by mass or more, even more preferably 0.2 parts by mass or more, even more preferably 0.5 parts by mass or more, and particularly preferably 0.8 parts by mass or more, per 100 parts by mass of the base polymer. From the viewpoint of increasing initial tackiness, the above amount is preferably 30 parts by mass or less, more preferably 20 parts by mass or less, even more preferably 15 parts by mass or less, even more preferably 10 parts by mass or less, and particularly preferably 5 parts by mass or less. Furthermore, it is preferable that the total amount of the corrosion inhibitor corresponding to the above-mentioned curing inhibitor and the above-mentioned other corrosion inhibitors is within the above range.

[0118] (Other components) The adhesive layer A may optionally contain polyethylene glycol to assist in the movement of electrolytes when voltage is applied. Polyethylene glycol with a number average molecular weight of 200 to 6000 can be used. When polyethylene glycol is included, the amount added is preferably 0.1 to 30 parts by mass per 100 parts by mass of the base polymer.

[0119] The adhesive layer A may contain a conductive filler as needed for the purpose of imparting conductivity to the adhesive layer A. The conductive filler is not particularly limited, and general known or conventional conductive fillers can be used, such as graphite, carbon black, carbon fiber, or metal powders such as silver or copper. When the conductive filler is included, the content is preferably 0.1 to 200 parts by mass per 100 parts by mass of the base polymer.

[0120] The adhesive layer A may optionally contain additives such as tackifiers, crosslinking accelerators, anti-aging agents, antioxidants, plasticizers, softeners, surfactants, antistatic agents, surface lubricants, flame retardants, surfactants, leveling agents, light stabilizers, ultraviolet absorbers, fillers, polymerization inhibitors, foil-like materials, rust inhibitors, and colorants (dyes, pigments, etc.), to the extent that they do not impair the effects of the present invention. Each of the above additives may be used individually or in combination of two or more. The total amount of the above additives is not particularly limited, but is preferably 20 parts by mass or less, more preferably 10 parts by mass or less, and even more preferably 5 parts by mass or less, per 100 parts by mass of the base polymer. The total content may also be 0.01 parts by mass or more.

[0121] The thickness of the adhesive layer A (thickness per layer) is preferably 1 μm or more, more preferably 10 μm or more, even more preferably 20 μm or more, even more preferably 30 μm or more, even more preferably 40 μm or more, and particularly preferably 50 μm or more. When the above thickness is 1 μm or more, the initial adhesive strength is higher, and the adhesive strength decreases sufficiently when voltage is applied. The above thickness is preferably 1000 μm or less, more preferably 500 μm or less, even more preferably 300 μm or less, and particularly preferably 200 μm or less.

[0122] The adhesive layer A may be in any form, for example, an emulsion type, a solvent type (solution type), a type that is cured by active energy rays other than light, or a hot melt type. Among these, the solvent type adhesive layer is preferred because it is easy to form while incorporating curing inhibitors.

[0123] <Adhesive Layer B> Adhesive layer B contains at least a polymer having a structure derived from a photopolymerization initiator. That is, adhesive layer B is a photocurable adhesive layer (preferably an ultraviolet curable adhesive layer). Adhesive layer B preferably further contains an electrolyte, from the viewpoint that it is preferable to be an ionization-peelable adhesive layer. Adhesive layer B also contains the curing inhibitor component. This curing inhibitor component migrates and penetrates from adhesive layer A.

[0124] (Polymer) The polymer contained in the adhesive layer B can be any known or conventional polymer, and is not particularly limited, but examples include those exemplified and described above as polymers contained in the adhesive layer A. Only one type of polymer may be used, or two or more types may be used. The polymer is preferably a base polymer.

[0125] As for the base polymer mentioned above, it is preferable that the polymer has a high dielectric constant, from the viewpoint of increasing the dielectric constant of components other than the electrolyte in the adhesive layer B and improving electropenetration. From this viewpoint, polyester polymers and acrylic polymers are preferred as the base polymer. In particular, acrylic polymers are preferred in order to increase cost, productivity, and initial adhesive strength.

[0126] The above acrylic polymer is preferably a polymer that contains the largest mass percentage of constituent units derived from (meth)acrylic acid ester. Examples of the above (meth)acrylic acid ester include hydrocarbon group-containing (meth)acrylic acid esters which may have an alkoxy group. Only one type of hydrocarbon group-containing (meth)acrylic acid ester which may have an alkoxy group may be used, or two or more types may be used.

[0127] Among the hydrocarbon group-containing (meth)acrylic acid esters that may have the above-mentioned alkoxy group-containing (meth)acrylic acid esters, the alkyl (meth)acrylic acid esters exemplified as hydrocarbon group-containing (meth)acrylic acid esters are, in particular, alkyl (meth)acrylic acid esters having linear or branched aliphatic hydrocarbon groups with 1 to 14 carbon atoms (preferably 2 to 8, more preferably 2 to 4). When the number of carbon atoms is within the above range, the dielectric constant of the components other than the electrolyte in the adhesive layer B can be increased, and the electropenetration properties can be further improved.

[0128] In order to appropriately exhibit the basic properties such as tackiness of the hydrocarbon group-containing (meth)acrylic acid ester which may have an alkoxy group in the adhesive layer B, the proportion of the hydrocarbon group-containing (meth)acrylic acid ester which may have an alkoxy group in the total monomer components constituting the acrylic polymer is preferably 70% by mass or more, more preferably 80% by mass or more, and even more preferably 85% by mass or more, based on the total amount (100% by mass) of the total monomer components. Furthermore, from the viewpoint of enabling copolymerization of other monomer components and obtaining the effects of those other monomer components, the above proportion may be 99.9% by mass or less, 98% by mass or less, or 95% by mass or less.

[0129] The above-mentioned acrylic polymer may contain constituent units derived from the above-mentioned other monomer components for the purpose of modification, such as improving cohesive strength or introducing crosslinking points. Each of the above-mentioned other monomer components may be used individually or in combination of two or more types.

[0130] Among the other monomers mentioned above, the polar group-containing monomers are preferred. Among the polar group-containing monomers, carboxyl group-containing monomers, hydroxyl group-containing monomers, and amide group-containing monomers are preferred due to their excellent cohesiveness. Furthermore, acrylic polymers having carboxyl and hydroxyl groups are preferred because the carboxyl and hydroxyl groups are easily polarized, allowing for a relatively high dielectric constant of the polymer. In particular, carboxyl group-containing monomers are preferred from the viewpoint of obtaining particularly high initial adhesive strength. Examples of carboxyl group-containing monomers, hydroxyl group-containing monomers, and amide group-containing monomers are those exemplified and described in adhesive layer A.

[0131] The total proportion of the polar group-containing monomers in the total monomer components (100% by mass) constituting the above acrylic polymer is not particularly limited, but is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, even more preferably 1% by mass or more, and particularly preferably 2% by mass or more. Furthermore, from the viewpoint of obtaining an adhesive layer B with appropriate flexibility, the total proportion is preferably 35% by mass or less, more preferably 25% by mass or less, and even more preferably 20% by mass or less. When the proportion is 0.1% by mass or more, cohesive force is easily obtained, so that adhesive residue is less likely to be left on the surface of the adherend after peeling off the adhesive layer B, and the electropenetration properties are improved. Furthermore, when the proportion is 35% by mass or less, it is easier to prevent the adhesive layer B from adhering excessively to the adherend and causing excessive peeling. In particular, when the proportion is 2 to 20% by mass, the adhesive strength tends to decrease when voltage is applied.

[0132] The monomer components constituting the above acrylic polymer may further include the above-mentioned other monomers. The proportion of the above-mentioned other monomers in the total amount of all monomer components constituting the above acrylic polymer (100% by mass) may be, for example, 0.05% by mass or more, or 0.5% by mass or more. The above proportion may also be, for example, 20% by mass or less, 10% by mass or less, or 5% by mass or less, and may be substantially absent.

[0133] The above-mentioned acrylic polymer may contain constituent units derived from polyfunctional (meth)acrylates copolymerizable with monomer components constituting the acrylic polymer in order to form a crosslinked structure within its polymer backbone. Examples of the above-mentioned polyfunctional (meth)acrylates include hexanediol di(meth)acrylate, nonanediol di(meth)acrylate, (poly)ethylene glycol di(meth)acrylate, (poly)propylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, pentaerythritol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, and dipentaerythritol hexa(meth)acrylate. Only one type of the above-mentioned polyfunctional (meth)acrylate may be used, or two or more types may be used.

[0134] The content of the above-mentioned polyfunctional (meth)acrylate is preferably 0.001 to 5 parts by mass, more preferably 0.01 to 3 parts by mass, and even more preferably 0.03 to 1 part by mass, based on 100 parts by mass of the total amount of monomer components constituting the above-mentioned acrylic polymer. When the content is 0.001 parts by mass or more, cohesive force is easily obtained, so that adhesive residue is less likely to be left on the surface of the adherend after peeling off the adhesive layer A, and the electropenetration properties are improved. When the content is 5 parts by mass or less, the migration of the curing inhibitor from adhesive layer A to adhesive layer B proceeds more easily.

[0135] The adhesive layer B is an adhesive layer formed and cured by polymerization of monomer components by light irradiation (preferably ultraviolet irradiation) in the presence of a photopolymerization initiator, thereby forming the polymer described above. The photopolymerization initiator is not particularly limited, but examples include benzoin ether-based photopolymerization initiators, acetophenone-based photopolymerization initiators, α-ketol-based photopolymerization initiators, aromatic sulfonyl chloride-based photopolymerization initiators, photoactive oxime-based photopolymerization initiators, benzoin-based photopolymerization initiators, benzyl-based photopolymerization initiators, benzophenone-based photopolymerization initiators, ketal-based photopolymerization initiators, and thioxanthone-based photopolymerization initiators. Other examples include acylphosphine oxide-based photopolymerization initiators and titanocene-based photopolymerization initiators. Only one type of photopolymerization initiator may be used, or two or more types may be used.

[0136] Examples of the above-mentioned benzoin ether-based photopolymerization initiators include benzoin methyl ether, benzoin ethyl ether, benzoin propyl ether, benzoin isopropyl ether, benzoin isobutyl ether, 2,2-dimethoxy-1,2-diphenylethane-1-one, and anisole methyl ether. Examples of the above-mentioned acetophenone-based photopolymerization initiators include 2,2-diethoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 1-hydroxycyclohexylphenyl ketone, 4-phenoxydichloroacetophenone, and 4-(t-butyl)dichloroacetophenone. Examples of the above-mentioned α-ketol-based photopolymerization initiators include 2-methyl-2-hydroxypropiophenone and 1-[4-(2-hydroxyethyl)phenyl]-2-methylpropan-1-one. Examples of the above-mentioned aromatic sulfonyl chloride-based photopolymerization initiators include 2-naphthalenesulfonyl chloride. Examples of the above-mentioned photoactive oxime-based photopolymerization initiators include 1-phenyl-1,1-propanedione-2-(O-ethoxycarbonyl)-oxime. Examples of the above-mentioned benzoin-based photopolymerization initiators include benzoin. Examples of the above-mentioned benzyl-based photopolymerization initiators include benzyl. Examples of the above-mentioned benzophenone-based photopolymerization initiators include benzophenone, benzoylbenzoic acid, 3,3'-dimethyl-4-methoxybenzophenone, polyvinylbenzophenone, and α-hydroxycyclohexylphenyl ketone. Examples of the above-mentioned ketal-based photopolymerization initiators include benzyldimethylketal. Examples of the above-mentioned thioxanthone-based photopolymerization initiators include thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2,4-dimethylthioxanthone, isopropylthioxanthone, 2,4-diisopropylthioxanthone, and dodecylthioxanthone. Examples of the above-mentioned acylphosphine oxide-based photopolymerization initiators include 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide and bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide.Examples of the titanocene-based photopolymerization initiators mentioned above include bis(η5-2,4-cyclopentadiene-1-yl)-bis(2,6-difluoro-3-(1H-pyrrole-1-yl)-phenyl)titanium.

[0137] The amount of the above-mentioned photopolymerization initiator used is not particularly limited, but for example, it is preferably 0.001 to 1 part by mass, and more preferably 0.01 to 0.5 parts by mass, per 100 parts by mass of the total monomer units of the acrylic polymer (total amount of monomer components constituting the acrylic polymer).

[0138] (Electrolyte) The electrolyte that the adhesive layer B may contain is a substance that can ionize into anions and cations. Examples of the electrolyte include those described and illustrated as electrolytes that the adhesive layer A may contain. The electrolyte preferably contains an ionic substance. The ionic substance preferably contains ionic substance A. The electrolyte may be of one type only, or two or more types may be used.

[0139] The amount of the above-mentioned ionic substance A blended into the adhesive layer B is preferably 0.5 parts by mass or more, more preferably 0.6 parts by mass or more, even more preferably 0.8 parts by mass or more, even more preferably 1.0 part by mass or more, and particularly preferably 1.5 parts by mass or more, per 100 parts by mass of the base polymer, from the viewpoint of sufficiently reducing the adhesive force during voltage application. From the viewpoint of further increasing the initial adhesive force, the blending amount is preferably 30 parts by mass or less, more preferably 20 parts by mass or less, even more preferably 15 parts by mass or less, even more preferably 10 parts by mass or less, and particularly preferably 5 parts by mass or less.

[0140] As the above-mentioned ionic substance, only one type of ionic substance A may be used, two or more types of ionic substance A may be used in combination, or ionic substance A may be used in combination with other ionic substances other than ionic substance A. When ionic substance A is used in combination with the above-mentioned other ionic substances, from the viewpoint of exhibiting a function in which the adhesive strength is sufficiently reduced by the application of voltage even in a low humidity environment, the total amount of ionic substances blended is preferably 0.5 parts by mass or more, more preferably 1.0 part by mass or more, and even more preferably 1.5 parts by mass or more, per 100 parts by mass of base polymer. Furthermore, the above total blending amount is preferably 30 parts by mass or less, more preferably 20 parts by mass or less, and even more preferably 10 parts by mass or less. When two or more types of ionic substances are used in combination, it is preferable to use 2 to 5 types of ionic substances, including ionic substances other than ionic substance A, more preferably 2 to 3 types of ionic substances, and even more preferably 2 types of ionic substances.

[0141] The amount of the electrolyte blended into the adhesive layer B is preferably 0.5 parts by mass or more, more preferably 0.6 parts by mass or more, even more preferably 0.8 parts by mass or more, even more preferably 1.0 part by mass or more, and particularly preferably 1.5 parts by mass or more, per 100 parts by mass of the base polymer, from the viewpoint of further reducing the adhesive force during voltage application. The amount blended is preferably 30 parts by mass or less, more preferably 20 parts by mass or less, even more preferably 15 parts by mass or less, even more preferably 10 parts by mass or less, and particularly preferably 5 parts by mass or less, from the viewpoint of further increasing the initial adhesive force.

[0142] (Corrosion inhibitor) The adhesive layer B may contain a corrosion inhibitor that does not fall under the curing inhibitory component (the other corrosion inhibitors described above). Examples of the other corrosion inhibitors described above are those that the adhesive layer A may contain. Only one type of the other corrosion inhibitor may be used, or two or more types may be used.

[0143] The amount of the alkylamine (alkylamine without a carbon-carbon double bond) blended into the adhesive layer B is preferably 0.01 parts by mass or more, more preferably 0.1 parts by mass or more, even more preferably 0.2 parts by mass or more, even more preferably 0.5 parts by mass or more, and particularly preferably 0.8 parts by mass or more, per 100 parts by mass of the base polymer. From the viewpoint of having high initial adhesive strength and being able to sufficiently reduce adhesive strength when voltage is applied, the blending amount is preferably 20 parts by mass or less, more preferably 15 parts by mass or less, and even more preferably 10 parts by mass or less.

[0144] The amount of the chelate-forming metal deactivator blended into the adhesive layer B is preferably 0.01 parts by mass or more, more preferably 0.1 parts by mass or more, even more preferably 0.2 parts by mass or more, even more preferably 0.5 parts by mass or more, and particularly preferably 0.8 parts by mass or more, per 100 parts by mass of the base polymer. From the viewpoint of having high initial adhesive strength and being able to sufficiently reduce adhesive strength when voltage is applied, the blending amount is preferably 20 parts by mass or less, more preferably 15 parts by mass or less, even more preferably 9 parts by mass or less, even more preferably 5 parts by mass or less, and particularly preferably 3 parts by mass or less.

[0145] The total amount of the above-mentioned other corrosion inhibitors is preferably 0.01 parts by mass or more, more preferably 0.1 parts by mass or more, even more preferably 0.2 parts by mass or more, even more preferably 0.5 parts by mass or more, and particularly preferably 0.8 parts by mass or more, per 100 parts by mass of the base polymer. From the viewpoint of increasing initial tackiness, the above amount is preferably 30 parts by mass or less, more preferably 20 parts by mass or less, even more preferably 15 parts by mass or less, even more preferably 10 parts by mass or less, and particularly preferably 5 parts by mass or less. Furthermore, it is preferable that the total amount of the corrosion inhibitor corresponding to the above-mentioned curing inhibitor and the above-mentioned other corrosion inhibitors is within the above range.

[0146] (Other components) The adhesive layer B may optionally contain polyethylene glycol to assist in the movement of electrolytes when voltage is applied. Polyethylene glycol with a number average molecular weight of 200 to 6000 can be used. When polyethylene glycol is included, the amount added is preferably 0.1 to 30 parts by mass per 100 parts by mass of the base polymer.

[0147] The adhesive layer B may or may not contain a filler. The presence of the filler improves impact resistance. Only one type of filler may be used, or two or more types may be used.

[0148] Examples of fillers include particulate organic and inorganic materials. Materials constituting the inorganic materials include, for example, metals such as copper, silver, gold, platinum, nickel, aluminum, chromium, iron, and stainless steel; metal oxides such as aluminum oxide, silicon oxide (silicon dioxide, silica), titanium oxide, zirconium oxide, zinc oxide, tin oxide, copper oxide, and nickel oxide; aluminum hydroxide, boehmite, magnesium hydroxide, calcium hydroxide, zinc hydroxide, silicic acid, iron hydroxide, copper hydroxide, barium hydroxide, zirconium oxide hydrate, tin oxide hydrate, basic magnesium carbonate, and hydrotalus. Examples include metal hydroxides and hydrated metal compounds such as oxalite, dosonite, borax, and zinc borate; carbides such as silicon carbide, boron carbide, nitrogen carbide, and calcium carbide; nitrides such as aluminum nitride, silicon nitride, boron nitride, and gallium nitride; carbonates such as calcium carbonate; titanates such as barium titanate and potassium titanate; carbon-based materials such as carbon black, carbon tubes (carbon nanotubes), carbon fibers, and diamonds; inorganic materials such as glass; and natural raw material particles such as volcanic ash, clay, and sand.

[0149] Examples of materials constituting the above-mentioned organic matter include polystyrene, acrylic resin (e.g., polymethyl methacrylate), phenolic resin, benzoguanamine resin, urea resin, silicone resin, polyester, polyurethane, polyolefin (polymers with one or more α-olefins as monomer components; for example, polyethylene such as LLDPE, LDPE, HDPE, polypropylene, etc.), polyamide (e.g., nylon, etc.), polyimide, polyvinylidene chloride, and other polymers.

[0150] The content of the filler in the adhesive layer B is preferably more than 0 parts by mass and 40 parts by mass or less, more preferably 0.008 to 30 parts by mass, even more preferably 0.1 to 20 parts by mass, even more preferably 0.2 to 10 parts by mass, and particularly preferably 0.4 to 6 parts by mass, based on 100 parts by mass of the total amount of the base polymer.

[0151] The adhesive layer B may, if necessary, further contain the additives exemplified and described as additives that may be included in adhesive layer A, to the extent that they do not impair the effects of the present invention. Each of the above additives may be used individually or in combination of two or more. The total amount of the above additives is not particularly limited, but is preferably 20 parts by mass or less, more preferably 10 parts by mass or less, and even more preferably 5 parts by mass or less, per 100 parts by mass of the base polymer. The total content may also be 0.01 parts by mass or more.

[0152] The thickness of the adhesive layer B (thickness per layer) is preferably 100 μm or more, more preferably 120 μm or more, and even more preferably 130 μm or more. When the above thickness is 100 μm or more, the initial adhesive strength is higher and the impact resistance is better. The above thickness is preferably 1000 μm or less, more preferably 500 μm or less, even more preferably 300 μm or less, and particularly preferably 200 μm or less.

[0153] The adhesive layer B can be manufactured, for example, by applying an adhesive composition for forming the adhesive layer B onto a release liner, and curing the resulting adhesive composition layer by irradiating it with light. Alternatively, it may be further heat-dried as needed.

[0154] Furthermore, known coating methods may be used for applying (coating) the above adhesive composition. For example, coaters such as gravure roll coaters, reverse roll coaters, kiss roll coaters, dip roll coaters, bar coaters, knife coaters, spray coaters, comma coaters, and direct coaters may be used.

[0155] Examples of the above-mentioned adhesive composition include a composition comprising a mixture of monomer components constituting a polymer (sometimes referred to as a "monomer mixture") or a partially polymerized thereof, the above-mentioned photopolymerization initiator, and, if necessary, other components such as an electrolyte. The above-mentioned monomer mixture may consist of a single monomer component or two or more monomer components. Furthermore, the above-mentioned "partially polymerized" may also be referred to as a "prepolymer," "syrup," etc., and means a composition in which one or more monomer components of the above-mentioned monomer mixture are partially polymerized.

[0156] Furthermore, it is preferable that the above adhesive composition does not contain or substantially contains organic solvents. Examples of organic solvents include those exemplified and described in the above-mentioned adhesive layer A. Only one organic solvent may be used, or two or more may be used.

[0157] In the above-mentioned adhesive composition, "substantially free of organic solvents" means that organic solvents are not actively incorporated except in cases where they are inevitably mixed in. Specifically, an adhesive composition in which the content of organic solvents is 1.0% by mass or less (preferably 0.5% by mass or less, and more preferably 0.2% by mass or less) relative to the total amount of the adhesive composition (100% by mass) can be said to be substantially free of organic solvents.

[0158] <Laminate> In the laminate of the present invention, the ratio of the thickness per layer of adhesive layer A to the thickness per layer of adhesive layer B [thickness per layer of adhesive layer A: thickness per layer of adhesive layer B] is preferably 1:4 to 3:2, more preferably 2:5 to 1:1, and even more preferably 1:3 to 4:5. When the above ratio is within the above range, the impact resistance is superior. When the laminate of the present invention comprises a plurality of adhesive layers A and / or adhesive layers B, it is preferable that the relationship between the thickness of at least one adhesive layer A and the thickness of at least one adhesive layer B satisfies the above ratio, and it is preferable that the relationship between the thickness of adhesive layer A and the thickness of adhesive layer B at the position closest to the thickness direction satisfies the above ratio.

[0159] Preferably, at least one of adhesive layer A and adhesive layer B contains a corrosion inhibitor, and preferably both contain a corrosion inhibitor. The corrosion inhibitor is a component that prevents corrosion of the adherend such as metal, and may be a corrosion inhibitor corresponding to the hardening inhibitor component, or any other corrosion inhibitor. The corrosion inhibitor contained in adhesive layer A and / or adhesive layer B may be one type or two or more types.

[0160] The total amount of corrosion inhibitor in the laminate of the present invention is preferably 0.1 to 15% by mass, more preferably 0.4 to 10% by mass, even more preferably 0.8 to 7% by mass, and particularly preferably 1 to 5% by mass, based on 100% by mass of the total amount of the laminate of the present invention. When the above content is 0.1% by mass or more, corrosion of the adherend can be prevented more effectively. When the above content is 15% by mass or less (particularly 5% by mass or less), impact resistance is superior.

[0161] The gel fraction of the laminate of the present invention is preferably 60 to 80% by mass. When the gel fraction is 60% by mass or more, the impact resistance is superior. When the gel fraction is 80% by mass or less, the migration of the curing inhibitory component from adhesive layer A to adhesive layer B proceeds more easily.

[0162] The gel fraction mentioned above is specifically the value calculated by, for example, the following "Method for Measuring Gel Fraction". (Method for Measuring Gel Fraction) Cut the laminate in the thickness direction and take 1 g worth, then wrap it in a porous PTFE (polytetrafluoroethylene) sheet to make a sample. If the laminate has a base material, the weight after removing the base material is taken as 1 g. Place the sample in a glass bottle, immerse it in ethyl acetate solution and leave it for 7 days, then remove the sample and dry it at 130°C for 2 hours. Weigh the dried sample and subtract the weight of the porous PTFE sheet to obtain the weight of the adhesive after drying, W2 g. Substitute W1 and W2 into the following formula to calculate the gel fraction [%]. As the porous PTFE sheet, you can use the product name "TEMISH" manufactured by Nitto Denko Corporation or an equivalent product. Gel fraction [%] = (W2 / W1) × 100

[0163] The laminate of the present invention preferably has an adhesive strength of 0.5 N / mm or less, more preferably 0.3 N / mm or less, and even more preferably 0.1 N / mm or less, in a 180° peel test (tensile speed: 300 mm / min, peel temperature 23°C, humidity 50% RH) on a stainless steel plate (SUS316) after bonding a 30V voltage to the adhesive surface of adhesive layer A and / or adhesive layer B for 90 seconds. When the above electropenetration force is 0.5 N / mm or less, the electropenetration properties are superior. When measuring the above electropenetration force, a conductive substrate may be backed on the side opposite to the side bonded to the stainless steel plate, and a plastic film such as a PET film may be further backed on the conductive substrate via a non-conductive adhesive sheet. Specifically, the above electropenetration force can be measured by the method described in the examples.

[0164] The thickness of the laminate of the present invention is preferably 150 to 3000 μm, more preferably 170 to 1000 μm, and even more preferably 190 to 500 μm. When the above thickness is 150 μm or more, the impact resistance is superior. When the above thickness is 3000 μm or less, the thickness of the laminate can be made thinner. The above thickness of the laminate refers to the thickness from one adhesive surface to the other adhesive surface and does not include the release liner.

[0165] The laminate of the present invention may be a so-called "substrate-less type" adhesive sheet (hereinafter sometimes referred to as a "substrate-less adhesive sheet") that does not have a base material (substrate layer), or it may be an adhesive sheet of the type that has a base material (hereinafter sometimes referred to as a "substrate-attached adhesive sheet"). Possible locations of the base material include between adhesive layer A and adhesive layer B, the side of adhesive layer A opposite to adhesive layer B, and the side of adhesive layer B opposite to adhesive layer A. The "substrate" mentioned above refers to the part that is attached to the adherend together with the laminate when the laminate is attached to the adherend. The release liner that is peeled off when the laminate is used (attached) is not included in the "substrate".

[0166] The above-mentioned substrate is not particularly limited, but examples include various optical films such as plastic films, anti-reflective (AR) films, polarizing plates, and phase difference plates. Examples of materials for the above-mentioned plastic films include polyester resins such as polyethylene terephthalate (PET), acrylic resins such as polymethyl methacrylate (PMMA), polycarbonate, triacetylcellulose (TAC), polysulfone, polyarylate, polyimide, polyvinyl chloride, polyvinyl acetate, polyethylene, polypropylene, ethylene-propylene copolymer, and cyclic olefin polymers such as the trade name "Arton" (cyclic olefin polymer, manufactured by JSR Corporation) and the trade name "Zeonor" (cyclic olefin polymer, manufactured by Nippon Zeon Co., Ltd.). Note that one or more of these plastic materials may be used. Furthermore, the above-mentioned "substrate" refers to the part that is attached to the substrate together with the adhesive layer when the laminate is attached to the substrate. The release liner that is peeled off when the laminate is used (attached) is not included in the "substrate".

[0167] The thickness of the above-mentioned substrate is not particularly limited, but is preferably, for example, 12 to 500 μm. The above-mentioned substrate may be in the form of a single layer or a multi-layer structure. Furthermore, the surface of the above-mentioned substrate may be appropriately subjected to known and conventional surface treatments, such as physical treatments such as corona discharge treatment or plasma treatment, or chemical treatments such as undercoating.

[0168] The laminate of the present invention may have a release liner bonded to the surface (adhesive surface) of the adhesive layer until use. Each adhesive surface of the above laminate may be protected by two release liners, or it may be protected by a single release liner with both sides being release surfaces, in a roll-like winding form (winding body). The release liner is used as a protective material for the adhesive layer and is peeled off when it is attached to the substrate. Note that the release liner is not necessarily required.

[0169] The above-mentioned release liner can be conventional release paper or the like, and is not particularly limited, but examples include a substrate having a release treatment layer, a low-adhesion substrate made of a fluoropolymer, or a low-adhesion substrate made of a nonpolar polymer. Examples of the substrate having the release treatment layer include plastic films and paper surface-treated with release agents such as silicone-based, long-chain alkyl-based, fluorine-based, or molybdenum sulfide. Examples of fluorine-based polymers in the low-adhesion substrate made of a fluoropolymer include polytetrafluoroethylene, polychlorotrifluoroethylene, polyvinyl fluoride, polyvinylidene fluoride, tetrafluoroethylene-hexafluoropropylene copolymer, and chlorofluoroethylene-vinylidene fluoride copolymer. Examples of the above-mentioned nonpolar polymer include olefin resins (e.g., polyethylene, polypropylene, etc.). The release liner can be formed by known or conventional methods. The thickness of the release liner is also not particularly limited.

[0170] The laminate of the present invention can be manufactured by known or conventional manufacturing methods. For example, the laminate (1) shown in Figure 1 can be obtained by forming an adhesive layer A (2) on a release liner, separately forming an adhesive layer B (3) on a release liner, and bonding the formed adhesive layers A (2) and B (3). To ensure sufficient adhesion between adhesive layers A and B, it is preferable to pressurize and heat the laminated adhesive layers A and B. Furthermore, from the viewpoint of ensuring sufficient migration of curing inhibitors and the like from adhesive layer A to adhesive layer B, it is preferable to age the laminated adhesive layers A and B.

[0171] [Removal Method] In the laminate of the present invention, if adhesive layer A and / or adhesive layer B are electrorelease adhesive layers, the laminate can be removed from the adherend by applying a voltage to the electrorelease adhesive layer, thereby creating a potential difference in the thickness direction of the electrorelease adhesive layer. For example, a bond in which the laminate of the present invention is attached to conductive adherends A and B can be removed from the adherend by applying current to the conductive adherends A and B and applying a voltage to the electrorelease adhesive layer. It is preferable to apply current by connecting terminals to one end and the other end of the electrorelease adhesive layer so that the voltage is applied to the entire electrorelease adhesive layer. Note that if the adherend has a metal adherend, the one end and the other end may be parts of the adherend having a metal adherend. Note that when removing the laminate, water may be added to the interface between the adherend surface of the conductive adherend and the electrorelease adhesive layer before applying the voltage.

[0172] Conventional re-peelable technologies include adhesive layers that harden and peel off by light irradiation such as ultraviolet (UV) light, and adhesive layers that peel off by heat. However, adhesive sheets using such adhesive layers cannot be used when light irradiation is difficult or when heat damages the adherend. The laminate of the present invention, when equipped with an electro-peelable adhesive layer, does not use light or heat, and can be easily peeled off by applying voltage without damaging the adherend.

[0173] [Applications] The laminate of the present invention is preferably used as a double-sided adhesive sheet to be bonded to components provided in electrical and electronic equipment, for use in bonding electrical and electronic components. The double-sided adhesive sheet is preferably used for bonding components provided in electrical and electronic equipment to both adhesive surfaces, that is, for fixing components together in electrical and electronic equipment. The double-sided adhesive sheet may be used for fixing components together or for temporary fixing. For example, when a double-sided adhesive sheet is used to fix or temporarily fix components provided in electrical and electronic equipment, there may be cases where the double-sided adhesive sheet must be peeled off and reworked due to a problem in the bonding process, or where the double-sided adhesive sheet must be peeled off in order to repair, replace, inspect, or recycle a component to which the double-sided adhesive sheet has been bonded. Thus, when a double-sided adhesive sheet is used, for example, to fix or temporarily fix components provided in electrical and electronic equipment, the frequency of removing the double-sided adhesive sheet is particularly high.

[0174] Furthermore, "electrical and electronic equipment" refers to equipment that falls under either electrical equipment or electronic equipment. Examples of such electrical and electronic equipment include image display devices such as liquid crystal displays, electroluminescent displays, and plasma displays, as well as portable electronic devices.

[0175] Examples of the above-mentioned portable electronic devices include mobile phones, smartphones, tablet computers, notebook computers, various wearable devices (e.g., wristwear-type devices worn on the wrist like watches, modular-type devices attached to a part of the body with clips or straps, eyewear-type devices including glasses (monocular and binocular types, including head-mounted types), clothing-type devices attached to shirts, socks, hats, etc. as accessories, earwear-type devices attached to the ears like earphones, etc.), digital cameras, digital video cameras, audio equipment (portable music players, IC recorders, etc.), calculators (calculators, etc.), portable game consoles, electronic dictionaries, electronic organizers, e-books, in-car information systems, portable radios, portable televisions, portable printers, portable scanners, and portable modems. In this specification, "portable" means not merely being able to carry something, but having a level of portability that allows an individual (a typical adult) to carry it relatively easily. The above-mentioned double-sided adhesive sheet is used, for example, so that the electro-peelable adhesive layer adheres closely to the components of the above-mentioned portable electronic device.

[0176] The laminate of the present invention is particularly preferred for applications such as fixing secondary batteries (e.g., lithium-ion battery packs) to their housings.

[0177] Figure 3 schematically shows an example of a portable electronic device (smartphone) in which the laminate of the present invention is used to bond the battery and the housing. As shown in Figure 3, a battery (heat-generating element) 8 is built into the housing 7 of the portable electronic device 6. The portable electronic device 6 is also constructed with the laminate 1 of the present invention, which is a double-sided adhesive sheet. In this example, the laminate 1 has the form of a double-sided adhesive sheet that fixes the components constituting the portable electronic device 6, specifically the housing 7 and the battery 8. The portable electronic device 6 is equipped with a touch panel 9 in which the display unit also functions as an input unit.

[0178] Furthermore, examples of materials that can be bonded by the laminate of the present invention include rigid members such as silicon substrates for semiconductor wafer applications, sapphire substrates, SiC substrates and metal base substrates for LEDs, TFT substrates and color filter substrates for displays, and base substrates for organic EL panels. In addition, examples of materials that can be bonded by the laminate of the present invention include semiconductor substrates such as compound semiconductor substrates, silicon substrates for MEMS devices, passive matrix substrates, surface cover glass for smartphones, OGS (One Glass Solution) substrates with touch panel sensors attached to the cover glass, organic substrates mainly composed of silsesquioxane and organic-inorganic hybrid substrates, flexible glass substrates for flexible displays, and fragile members such as graphene sheets.

[0179] The laminate of the present invention provides excellent impact resistance when bonded to an adherend by including a photocurable adhesive layer B, and by laminating adhesive layer A, the photocurable adhesive layer B can contain a curing inhibitor. For example, a corrosion inhibitor that inhibits photocuring can be included in the photocurable adhesive layer B. Furthermore, if adhesive layer A and / or adhesive layer B are electropenetrating adhesive layers located at both ends of the laminate, it has electropenetrating properties that allow it to be peeled off from the adherend by applying a voltage. Furthermore, by using a corrosion inhibitor as the curing inhibitor, the corrosion resistance of the adherend can also be improved. Thus, the laminate of the present invention provides excellent impact resistance and corrosion resistance of the adherend when bonded to an adherend, and is electropenetrating.

[0180] [Bonded Body] The laminate of the present invention can be bonded to a conductive material to obtain a bonded body. The bonded body comprises the laminate of the present invention and a conductive material, wherein the adhesive layer A and / or adhesive layer B of the laminate are bonded to the conductive material. The conductive material is preferably an adherend having a metal-bonding surface. Examples of adherends having a metal-bonding surface include those made of metals mainly composed of aluminum, copper, iron, magnesium, tin, gold, silver, lead, etc. Among these, metals containing aluminum are preferred.

[0181] Examples of the above-mentioned bonded body include a bonded body in which the laminate of the present invention and the adhesive layer A and / or adhesive layer B of the laminate are attached to a conductive adherend having, for example, a metal adherend surface.

[0182] The present invention will be described in more detail below with reference to examples, but the present invention is not limited in any way by these examples. The weight-average molecular weights below were measured by the method described above using gel permeation chromatography (GPC).

[0183] Example 1 [Preparation of Adhesive Layer A] (Preparation of Acrylic Polymer Solution 1) 87 parts by mass of n-butyl acrylate (BA), 10 parts by mass of 2-methoxyethyl acrylate (MEA), 3 parts by mass of acrylic acid (AA), and 150 parts by mass of ethyl acetate as a polymerization solvent were placed in a separable flask and stirred for 1 hour while introducing nitrogen gas. After removing oxygen from the polymerization system in this way, 0.2 parts by mass of 2,2'-azobisisobutyronitrile (AIBN) was added as a polymerization initiator, and the mixture was heated to 63°C and reacted for 6 hours. Then, ethyl acetate was added to obtain Acrylic Polymer Solution 1 with a solid content of 30% by mass. The weight-average molecular weight of the obtained acrylic polymer was 700,000.

[0184] (Preparation of adhesive layer A) To the acrylic polymer solution 1 obtained above, 0.4 parts by mass of a crosslinking agent (polycarbodiimide resin, trade name "Carbodilite V-05", manufactured by Nisshinbo Chemical Co., Ltd.) is added per 100 parts by mass of the acrylic polymer, 4.4 parts by mass of an ionic substance trade name "Elexel AS-110" (cation: 1-ethyl-3-methylimidazolium cation, anion: bis(fluorosulfonyl)imide anion, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), 4 parts by mass of an additive (corrosion inhibitor) trade name "Irgamet 30" (N,N-bis(2-ethylhexyl)[(1,2,4-triazole-1-yl)methyl]amine, manufactured by BASF Japan Ltd.), and trade name "Amine Three parts by mass of "O" (2-(8-heptadecene-1-yl)-4,5-dihydro-1H-imidazole-1-ethanol, manufactured by BASF Japan Ltd.), 0.3 parts by mass of "Irgacor DSSG" (sodium sebacate, manufactured by BASF Japan Ltd.), and ethyl acetate were added and stirred and mixed to obtain an electrolytic adhesive composition (solution) adjusted to a solid content concentration of 25% by mass. The obtained electrolytic adhesive composition (solution) was applied to the peeled surface of a polyethylene terephthalate peel liner (product name "MRF38", manufactured by Mitsubishi Chemical Corporation) using an applicator to a uniform thickness. Next, the polyethylene terephthalate release liner (product name "MRE38", manufactured by Mitsubishi Chemical Corporation), which had been heat-dried at 150°C for 3 minutes to remove surface defects, was laminated onto the adhesive using a hand roller to obtain an adhesive layer A (electro-peelable adhesive layer) with a thickness of 60 μm.

[0185] [Preparation of Adhesive Layer B] (Preparation of Acrylic Polymer Solution 2) As monomer components, 87 parts by mass of n-butyl acrylate (BA), 10 parts by mass of 2-methoxyethyl acrylate (MEA), 3 parts by mass of acrylic acid (AA), and as photopolymerization initiators, 0.05 parts by mass of trade name "Omnirad 184" (manufactured by IGM Resins B.V.) and 0.05 parts by mass of trade name "Omnirad 654" (manufactured by IGM Resins B.V.) were placed in a separable flask and stirred for 15 minutes while introducing nitrogen gas. After removing oxygen from the polymerization system in this manner, ultraviolet light was irradiated under conditions of illuminance 3 mW and integrated light amount 2000 mJ, and the reaction was allowed to proceed for 15 minutes to obtain Acrylic Polymer Solution 2, which is a mixture of 95% by mass of monomer and 5% by mass of polymer.

[0186] (Preparation of adhesive layer B) To the acrylic polymer solution 2 obtained above, 0.08 parts by mass of 1,9-nonanediol diacrylate (1,9-NDDA) (manufactured by Osaka Organic Chemical Industry Co., Ltd.) as a crosslinking agent and 4.4 parts by mass of the product name "Elexel AS-110" (cation: 1-ethyl-3-methylimidazolium cation, anion: bis(fluorosulfonyl)imide anion, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) as an ionic substance were added per 100 parts by mass of the acrylic polymer, and the mixture was stirred and mixed to obtain an electrolytic adhesive composition (solution). The obtained electrolytic adhesive composition (solution) was applied to the peeled surface of a polyethylene terephthalate peel liner (product name "MRF38", manufactured by Mitsubishi Chemical Corporation) with a peeled surface using an applicator to a uniform thickness, and a polyethylene terephthalate peel liner (product name "MRE38", manufactured by Mitsubishi Chemical Corporation) with a peeled surface was placed on top. Then, ultraviolet light was irradiated under conditions of illuminance 3 mW and cumulative light amount 2000 mJ, and the mixture was allowed to react for 16 minutes to obtain an adhesive layer B (electropeelable adhesive layer) with a thickness of 160 μm.

[0187] [Preparation of Double-Sided Adhesive Sheet] One release liner (MRE38) of adhesive layer A obtained above was peeled off, and one release liner (MRE38) of adhesive layer B obtained above was peeled off. The exposed surfaces of the two layers were overlapped and heat-pressed together using a thermal laminator (MRK-650Y type, speed 0.1 m / min, temperature 80°C, pressure 0.5 MPa). After that, aging was performed at room temperature for 168 hours. Through the above process, a double-sided adhesive sheet, which is the laminate of Example 1, was prepared.

[0188] Examples 2-4 and 6-8: Double-sided adhesive sheets, which are laminates, were prepared in the same manner as in Example 1, except that the composition of adhesive layer B and the lamination conditions were changed as shown in Table 1. In Table 1, "DCPA" refers to dicyclopentanyl acrylate, and "filler" refers to silicone filler (product name "KMP-605", manufactured by Shin-Etsu Chemical Co., Ltd.).

[0189] Example 5 One release liner (MRE38) of adhesive layer A prepared in Example 3 was peeled off, and one release liner (MRE38) of adhesive layer B prepared in Example 3 was peeled off, and the exposed surfaces of the two layers were overlapped. Then, the release liner (MRF38) on the adhesive layer B side was peeled off, and the release liner (MRE38) of adhesive layer A prepared separately in Example 3 was peeled off, and the exposed surface was overlapped with the adhesive layer B, and the layers were heat-pressed using a thermal laminator (MRK-650Y type, speed 0.1 m / min, temperature 100°C, pressure 0.5 MPa). After that, aging was performed at room temperature for 168 hours. Through the above process, a double-sided adhesive sheet, which is a laminate of Example 5 consisting of a three-layer structure [adhesive layer A / adhesive layer B / adhesive layer A], was prepared.

[0190] Example 9 A double-sided adhesive sheet, which is a laminate, was prepared in the same manner as in Example 6, except that the amount of corrosion inhibitor in adhesive layer A was changed as shown in Table 1.

[0191] Comparative Example 1 A double-sided adhesive sheet, which is a laminate, was prepared in the same manner as in Example 6, except that adhesive layer A of Example 6 was replaced with adhesive layer A', which does not contain the corrosion inhibitor found in adhesive layer A.

[0192] Reference Example 1: The adhesive layer B prepared in Example 1 was used as the double-sided adhesive sheet in Reference Example 1.

[0193] Reference Example 2: The adhesive layer B prepared in Example 4 was used as the double-sided adhesive sheet in Reference Example 2.

[0194] Reference Example 3: The adhesive layer A prepared in Example 1 was used as the double-sided adhesive sheet in Reference Example 3.

[0195] <Evaluation> The double-sided adhesive sheets obtained in the examples, reference examples, and comparative examples were evaluated as follows. The results are shown in the table.

[0196] (1) Three test pieces were prepared by cutting the double-sided adhesive sheets prepared in the corrosion resistance examples, reference examples, and comparative examples to a size of 80 mm x 10 mm. The three test pieces were attached to a 100 mm x 50 mm aluminum plate with adhesive layer B side (adhesive layer A side in Reference Example 3) and stored for three weeks in an environment of 65°C and 90% relative humidity. The three test pieces were then peeled off and the aluminum plate was visually observed after peeling. If the aluminum plate was whitened after peeling, it was considered "corrosion present". The evaluation was as follows: if there were no "corrosion present" test pieces out of the three, it was "○"; if there was one, it was "△"; and if there were two or three, it was "×".

[0197] (2) Gel fraction The gel fraction of adhesive layer B in the double-sided adhesive sheets prepared in the examples, reference examples, and comparative examples was measured by the following method. The double-sided adhesive sheet was cut in the thickness direction, and 1 g of W was taken and wrapped in a porous PTFE (polytetrafluoroethylene) sheet to make a sample. The sample was placed in a glass bottle, immersed in ethyl acetate solution and left to stand for 7 days, then the sample was removed and dried at 130°C for 2 hours. The dried sample was weighed, and the weight of the porous PTFE sheet was subtracted to obtain the weight of the adhesive after drying, W2 g. Then, W1 and W2 were substituted into the following formula to calculate the gel fraction [%]. Gel fraction [%] = (W2 / W1) × 100

[0198] (3) Impact Resistance The double-sided adhesive sheets prepared in the examples, reference examples, and comparative examples were cut into squares with sides of 24.5 mm. A stainless steel plate was also prepared, which was 2 mm thick and had an outer diameter of 50 mm x 50 mm, with a square hole of 20 mm on each side in the center. The cut double-sided adhesive sheets were placed so that their centers aligned with the square hole in the stainless steel plate. Another square stainless steel plate (3 mm thick, outer diameter 30 mm x 30 mm) was placed on top of the stainless steel plate with the square hole, sandwiching the double-sided adhesive sheets and ensuring that the centers of gravity of the two stainless steel plates coincided, and this was used as the evaluation sample. The evaluation sample was pressed with a load of 90 N for 15 seconds to ensure that the force was applied uniformly to the double-sided adhesive sheets, thereby bonding the two stainless steel plates and the double-sided adhesive sheets together. After releasing the force, the sample was left to stand at 25°C for 72 hours. Next, a measuring platform was placed on the base of a DuPont impact tester (manufactured by Toyo Seiki Seisakusho Co., Ltd.), and the evaluation sample was placed on the measuring platform so that the stainless steel plate with the square-shaped hole was facing upwards (adhesive layer B side was facing upwards (in Reference Example 3, adhesive layer A side was facing upwards)). Then, a stainless steel impact pin with a tip radius of 3.1 mm was placed in the center of the square-shaped hole, and the impact resistance was measured by changing the weight of the drop weight and the drop height in the following order. The impact resistance measurement was carried out so that the amount of energy increased until peeling occurred. The amount of energy (J) used in the test performed just before peeling was calculated by multiplying the load by the height, and this was used as the evaluation result of impact resistance. When performing (i) to (v) above, tests were not performed for energy amounts that had already been evaluated, and the load and height were set so that the energy amounts would not overlap.

[0199] (i) The drop weight was changed in 50 mm increments from 50 mm to 500 mm using a 50 g weight. (ii) The drop weight was changed in 50 mm increments from 50 mm to 500 mm using a 100 g weight. (iii) The drop weight was changed in 50 mm increments from 350 mm to 500 mm using a 150 g weight. (iv) The drop weight was changed in 50 mm increments from 400 mm to 500 mm using a 200 g weight. (v) The drop weight was changed in 50 mm increments from 350 mm to 500 mm using a 300 g weight.

[0200] (4) Electropeelability The double-sided adhesive sheets prepared in the examples, reference examples, and comparative examples were made into sheets of 25 mm x 80 mm in size. One release liner was peeled off, and the conductive layer side of the conductive substrate was bonded to the exposed adhesive layer B (adhesive layer A in Reference Example 3) to obtain a single-sided adhesive sheet with a substrate. As conductive substrates, a substrate-less double-sided adhesive sheet was used, consisting of an adhesive layer prepared in the same manner as adhesive layer A in Example 1, except that ionic substances and corrosion inhibitors were not added to the non-conductive side of a metal-layered film (product name "MetalMe 25S", manufactured by Toray Industries, Inc., thickness 25 μm), and a PET film with a thickness of 50 μm (manufactured by Toray Industries, Inc., product number: S-10) bonded together with a hand roller. Then, the other release liner of the double-sided adhesive sheet was peeled off, and a SUS316 (30 mm x 120 mm) was attached to the surface of the exposed adhesive layer A (adhesive layer A' in Comparative Example 1) so that one end of the double-sided adhesive sheet protruded about 20 mm from the adherend, and it was pressed with a 2 kg roller for one back-and-forth motion. After that, it was left in an environment of 23°C / 50% RH for 72 hours to obtain a bonded body consisting of [conductive substrate / electrorelease adhesive layer / substrate / electrorelease adhesive layer / SUS316]. The positive and negative electrodes of a DC stabilizer were attached to the α and β points in Figure 4 of the above-mentioned joint, respectively. Immediately after applying a voltage of 30V for 90 seconds, the joint was peeled in the direction of the arrow in Figure 4 using a peel tester (product name "Variable Angle Peel Tester YSP", manufactured by Asahi Seiko Co., Ltd.). The adhesive strength (23°C / 50%RH) in a 180° peel test (tensile speed: 300 mm / min, peel temperature 23°C, humidity 50%RH) at the interface between the double-sided adhesive sheet and SUS316 was measured and defined as the electropenetrating force. In Figure 4, 10 is the adherend (SUS316), and 11 is the backing material formed by bonding a conductive substrate and a PET film with a substrate-less double-sided adhesive sheet.

[0201]

[0202] As shown in Table 1, the double-sided adhesive sheet of Reference Example 2, which did not contain a corrosion inhibitor, had poor corrosion resistance. The double-sided adhesive sheet of Reference Example 1 consisted of a single layer of adhesive layer B, and although adhesive layer B contained a corrosion inhibitor, it also had poor corrosion resistance. The double-sided adhesive sheet of Comparative Example 1 was a double-sided adhesive sheet consisting of adhesive layer B of Reference Example 1, with an adhesive layer A' that did not contain a corrosion inhibitor laminated on top, but this double-sided adhesive sheet also had poor corrosion resistance. In contrast to these, the double-sided adhesive sheets of Examples 1 to 9 had the same or less corrosion inhibitor content in adhesive layer B as Reference Example 1, yet their corrosion resistance was good or fair, confirming that the corrosion inhibitor had migrated from adhesive layer A to the light-curing adhesive layer B.

[0203] The following describes variations of the invention relating to this disclosure. [Note 1] A laminate comprising an adhesive layer A containing a polymer and a component that inhibits photocuring, and an adhesive layer B containing a polymer having a structure derived from a photopolymerization initiator. [Note 2] The laminate according to Note 1, wherein the adhesive layer A and / or the adhesive layer B contains a corrosion inhibitor. [Note 3] The laminate according to Note 2, wherein the content ratio of the total amount of the corrosion inhibitor in the laminate is 0.1 to 15% by mass with respect to 100% by mass of the total amount of the laminate. [Note 4] The laminate according to any one of Notes 1 to 3, wherein the ratio of the thickness per layer of adhesive layer A to the thickness per layer of adhesive layer B [thickness per layer of adhesive layer A: thickness per layer of adhesive layer B] is 1:4 to 3:2. [Note 5] The laminate according to any one of Notes 1 to 4, wherein the gel fraction of the laminate is 60 to 80% by mass. [Note 6] The laminate according to any one of Notes 1 to 5, wherein the adhesive layer A contains an electrolyte. [Note 7] The laminate according to any one of Notes 1 to 6, for fixing components together in electrical and electronic equipment, wherein the adhesive layer A and the adhesive layer B are double-sided adhesive sheets providing both adhesive surfaces. [Note 8] A joint comprising the laminate according to any one of Notes 1 to 7 and a conductive material, wherein the adhesive layer A or the adhesive layer B is attached to the conductive material. [Note 9] Electrical and electronic equipment comprising the laminate according to Note 7, wherein the double-sided adhesive sheet fixes components together on both adhesive surfaces.

[0204] 1. Laminate 2, 21, 22. Adhesive layer A 3. Adhesive layer B 4, 5. Release liner 6. Portable electronic device 7. Housing 8. Battery 9. Touch panel 10. Adhered surface 11. Backing material

Claims

1. A laminate comprising adhesive layer A containing a polymer and a component that inhibits photocuring, and adhesive layer B containing a polymer having a structure derived from a photopolymerization initiator.

2. The laminate according to claim 1, wherein the adhesive layer A and / or the adhesive layer B contains a corrosion inhibitor.

3. The laminate according to claim 1 or 2, wherein the ratio of the thickness per layer of adhesive layer A to the thickness per layer of adhesive layer B [thickness per layer of adhesive layer A: thickness per layer of adhesive layer B] is 1:4 to 3:

2.

4. The laminate according to claim 2, wherein the total amount of the corrosion inhibitor in the laminate is 0.1 to 15% by mass with respect to 100% by mass of the total amount of the laminate.

5. The laminate according to claim 1 or 2, wherein the gel fraction of the laminate is 60 to 80% by mass.

6. The laminate according to claim 1 or 2, wherein the adhesive layer A comprises an electrolyte.

7. The laminate according to claim 1 or 2, which is for fixing components together in electrical and electronic equipment, and is a double-sided adhesive sheet in which adhesive layer A and adhesive layer B provide both adhesive surfaces.

8. A bonded body comprising a laminate according to claim 1 or 2 and a conductive material, wherein the adhesive layer A or the adhesive layer B is attached to the conductive material.

9. An electrical and electronic device comprising the laminate described in claim 7, wherein the double-sided adhesive sheet fixes the components together on both adhesive surfaces.

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