Adhesive tape, bonded composite, and method for electrically releasing bonded composite

Abstract

To provide an adhesive tape that can be removed again from at least one substrate without leaving residue and has excellent impact resistance (impact toughness).SOLUTION: The present invention relates to an adhesive tape, a bonded composite, a method for electrically releasing a bonded composite, and the use of the adhesive tape for bonding components in an electronic device, an automobile, a medical device and a dental device. The adhesive tape includes at least the following layer: an adhesive layer D, where, the adhesive layer D includes at least one electrolyte and is subjected to foaming, where the foaming is achieved using microballoons, and the microballoons have surface layers composed of silicate or almosilicate.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to adhesive tapes, bonded joints, methods for electrorelease of bonded joints, and the use of said adhesive tapes to bond components in electronic, automotive, medical and dental devices. [Background technology]

[0002] Most adhesive tape solutions are not removable or cannot be removed without damaging the substrate. Recently, there has been an increased interest in "on-demand desorption" functionality due to environmental legislation and end-customer awareness regarding sustainability as well as increasing cost pressures in manufacturing. The usage scenarios for desorption processes are categorized into rework, repair, recycling and conversion aids.

[0003] Debonding techniques aim to achieve cohesive failure of the adhesive layer or adhesive debonding of the adhesive layer from the substrate, the former requiring cleaning of the substrate prior to rebonding, whereas the latter avoids such cleaning.

[0004] However, debonding techniques that ensure the required high and permanently reliable adhesive strength are generally either relatively difficult to achieve or take a very long time to apply, for example debonding using penetrating solvents.

[0005] Therefore, currently, in particular in the rework or repair of electronic devices such as smartphones or tablet computers, mainly cohesively breaking adhesive bonds are used, which are often designed as pressure-sensitive adhesive tapes whose cohesive strength is reduced via an increase in temperature to such an extent that cohesive separation of the bond can be performed manually. The result is extensive post-treatment of substrate surfaces contaminated with adhesive residues in preparation for re-adhesion.

[0006] Besides the thermally mediated separation method, an electrical separation method is also discussed. For example, EP3363873B1 discloses such an electrical separation method or a corresponding adhesive tape, which allows electrical separation of substrates bonded to each other. It is intended to allow separation of rigid substrates in particular. For this purpose, the adhesive tape proposed in EP3363873B1 has a centrally located electrically conductive layer surrounded by two adhesive layers, one of which contains an electrolyte, so that it can be electrically peeled off from the conductive layer or from the electrically conductive substrate.

[0007] Especially in the use of adhesive tapes in electronic devices, impact resistance is often important, since the bonded parts must not come apart even if the mobile device is dropped.

[0008] To increase the impact resistance of adhesive tapes, the adhesive is often foamed, in particular by adding foamable microballoons.

[0009] However, the addition of such additives, such as expandable microballoons, affects the properties of the adhesive, especially the adhesive strength. Foaming itself also gives a different property profile than that of a non-foamed adhesive. This is especially related to the density, strength and the mobility of relatively small molecules in the adhesive, with the last-mentioned aspect especially affecting the electrical release properties of the adhesive. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] EP3363873B1 [Non-patent literature]

[0011] [Non-Patent Document 1] Carl H. Hamann,Wolf Vielstich:Elektrochemie I:Elektrolytische Leitfaehigkeit,Potentiale,Phasengrenzen.2.Auflage.VCH Verlagsgesellschaft mbH,Oldenburg / Bonn 1985,ISBN3-527-21100-4,S.4 [Non-Patent Document 2] PEHinkamp, ​​Polymer, 1967, 8, 381 Summary of the Invention [Problem to be solved by the invention]

[0012] The present invention is therefore based on the problem of providing an adhesive tape which can be peeled off again without residue from at least one substrate and which has good impact resistance (impact toughness), while at the same time the adhesion of said adhesive tape to the substrate to be bonded should not be negatively affected prior to peeling. [Means for solving the problem]

[0013] The above object is achieved according to the invention by an adhesive tape according to claim 1.

[0014] The adhesive tape according to the invention comprises at least the following layers: an adhesive layer D, which comprises at least one electrolyte and is foamed, whereby foaming is effected by means of microballoons and whereby said microballoons have on their surface a layer made of silicate or alumosilicate.

[0015] By using the contained electrolyte, the adhesive layer D is electrically peelable.

[0016] Surprisingly, it has been found that the adhesive layer D can be electrically peeled off even when it is foamed with microballoons and therefore contains microballoons. For this purpose, it is important that the microballoons have a layer made of silicate or alumosilicate on their surface. This results in high impact resistance of the adhesive tape as well as high impact resistance of the bonded assembly comprising the adhesive tape and the substrates bonded together via it. At the same time, the adhesive tape has high adhesion, despite containing microballoons.

[0017] Therefore, by using the present invention, an adhesive tape is successfully provided which can be easily and quickly re-peeled and therefore contributes to sustainability, and on the other hand the article comprising it has an extended lifespan, even if subjected to undesirable forces, for example when dropped.

[0018] The adhesive tape according to the invention is preferably a double-sided adhesive tape. For the sake of brevity, the adhesive tape according to the invention will be referred to within the scope of the present invention as "adhesive tape", even in the case of a double-sided adhesive embodiment.

[0019] The present invention relates to an adhesive tape, which can be in any ready-made form, with adhesive tape rolls being preferred. The adhesive tape, especially in web-like form, can be produced in the form of a roll, i.e. wound on itself in the form of an Archimedean spiral, or can be produced as an adhesive strip, which can be obtained, for example, in the form of a die cut.

[0020] The adhesive tape according to the invention is in particular in the form of a web, by which is understood a body whose length (extension in the x-direction) is several times greater than its width (extension in the y-direction) and whose width is essentially constant or, above all, exactly constant along its entire length.

[0021] The general expression "adhesive tape", also called synonymously "adhesive strip", in the sense of the present invention encompasses all flat formations, such as two-dimensionally extended films or film segments, tapes having an extended length and limited width, tape segments, etc., and finally also die cuts or labels.

[0022] The adhesive tape has a longitudinal extension (x-direction) and a width extension (y-direction) as well as a thickness (z-direction) extending perpendicularly to both extensions, where the width extension and the longitudinal extension are many times greater than the thickness. The thickness is as uniform as possible, and in particular exactly uniform, over the entire surface area of ​​the adhesive tape, which is determined by the length and the width.

[0023] This statement applies equally to the carrier layer(s) that in some preferred embodiments form layers in the x and y directions as components of the adhesive tape.

[0024] It is understood that the individual layers are stacked along the z-direction.

[0025] All statements in the specification apply to the adhesive tape according to the invention, to the method according to the invention for producing said adhesive tape, to the bonded assembly according to the invention as well as to the method for electrically releasing said assembly and to the use of the adhesive tape according to the invention.

[0026] In addition, all features which are technical matters recited in the respective dependent claims are also included in the present invention. Furthermore, combinations of individual features with one another and, in this case, combinations of aspects with different levels of preference are also included in the present invention. Thus, for example, a combination of a first feature indicated as "preferred" with a second feature indicated as "particularly preferred" is included in the present invention. In this case, technical matters indicated within the framework of "embodiments" with different levels of preference are also included.

[0027] The adhesive layer D contains at least one electrolyte.

[0028] Here, "electrolyte" is understood to mean a compound that is "dissociated into ions in a solid, liquid or dissolved state and moves in a direction under the influence of an electric field," as described in the Wikipedia entry "Elektrolyt" on January 4, 2023 or in accordance with Carl H. Hamann, Wolf Vielstich: Elektrochemie I: Elektrolytische Leitfaehigkeit, Potentiale, Phasengrenzen. 2. Auflage. VCH Verlagsgesellschaft mbH, Oldenburg / Bonn 1985, ISBN3-527-21100-4, S.4 (Non-Patent Document 1).

[0029] Preferably, the electrolyte of the adhesive layer D is selected from the group consisting of ionic liquids and metal salts, with ionic liquids being particularly preferred.

[0030] In particular, the adhesive tape can be easily peeled off by using one or more ionic liquids as electrolytes without the adhesive properties of the adhesive tape being negatively affected, the ionic liquids being distributed well and uniformly in the polymer matrix of the adhesive, and the peeling off takes place more quickly than with other electrolytes.

[0031] Furthermore, the components of ionic liquids are non-volatile, especially at room temperature. In addition, ionic liquids are relatively thermally stable and non-flammable, as well as relatively chemically stable.

[0032] Ionic liquids, within the framework of the present invention, are salts which are liquid at room temperature, i.e. at 23° C. Accordingly, ionic liquids comprise an anion and a cation.

[0033] Therefore, ionic liquids are particularly well suited as electrolytes in the separation process or method according to the invention for electrical peeling. When a voltage is applied, anions migrate to the anode side and cations to the cathode side. This reduces the adhesion of the adhesive layer containing ionic liquid, here layer D, to at least one of the adjacent layers, and thus achieves adhesive separation between adhesive layer D and at least one of the adjacent layers.

[0034] In principle, all ionic liquids are suitable within the scope of the present invention.

[0035] The ionic liquids used within the scope of the present invention comprise at least one anion and at least one cation. In this case, it is also conceivable that the ionic liquid comprises more than one type of anion and / or more than one type of cation. Furthermore, it is also conceivable that two or more different ionic liquids are added to the adhesive layer D or that the adhesive layer D comprises two or more different ionic liquids.

[0036] Preferably, the anion of the ionic liquid is Br - , AlCl 4 - , Al 2 Cl 7 - , NO 3 - , B.F. 4 - , P.F. 6 - , C.H. 3 COO - , C.F. 3 COO - , C.F. 3 CO 3 - , C.F. 3 SO 3 - , (CF 3 SO 2 ) 2 N - , (CF 3 SO 2 ) 3 C - , AsF6 - , SbF 6 - , C.F. 3 (CF 2 ) 3 SO 3 - (CF 3 CF 2 SO 2 ) 2 N - , C.F. 3 CF 2 CF 2 COO - , (FSO 2 ) 2 N - These anions are particularly well soluble in the polymers used in the adhesive, such as (meth)acrylates, and can diffuse quickly and well into the matrix, thus allowing a relatively fast separation process, while leaving no residue behind.

[0037] Particularly preferably, the anion is (CF 3 SO 2 ) 2 N - and (FSO 2 ) 2 N - These anions are particularly well suited because they achieve the best electro-detachability, in particular because with these anions (re)detachment proceeds particularly quickly and without leaving any residues.

[0038] Preferably, the cation of the ionic liquid is selected from the group consisting of imidazolium-based cations, pyridinium-based cations, pyrrolidine-based cations and ammonium-based cations.

[0039] These cations are particularly well soluble in the polymers used in the adhesives, such as (meth)acrylates, and can diffuse quickly and well into the matrix, thus allowing a relatively fast separation process, while leaving no residue behind.

[0040] Particularly preferably, the cation is selected from the group consisting of imidazolium-based cations. These cations are particularly well suited, because they achieve the best electro-detachability. In particular, with these cations, (re)peeling is particularly successful, fast, and leaves no residue.

[0041] Very particularly preferably, the cation is selected from the group consisting of 1-ethyl-3-methylimidazolium and 1-butyl-3-methylimidazolium.Also preferably, the cation is 1-ethyl-3-methylimidazolium.

[0042] Particularly preferably, the electrolyte of the adhesive layer D is selected from the group consisting of the following ionic liquids: 1-ethyl-3-methylimidazolium-bis(trifluoromethylsulfonyl)imide (EMIN-TFSI) and 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide (EMIM-FSI). These ionic liquids are particularly well soluble in the polymers used in the adhesive, such as (meth)acrylates, and can diffuse quickly and well into the matrix, thus allowing a relatively fast separation process, and at the same time leaving no residues.

[0043] The adhesive of adhesive layer D preferably comprises at least one polymer.

[0044] It is particularly preferred that the adhesive layer D is based on poly(meth)acrylate. The expression "based on (meth)acrylate" means within the scope of the present invention that poly(meth)acrylate is the main polymer of the adhesive and is accordingly present in the adhesive layer D in a proportion of 90 to 100% by weight, based on 100% by weight, i.e. based on the total amount of polymer present in the adhesive layer D. The tackifying resin optionally present in the adhesive layer D does not count towards 100% by weight of the polymer present.

[0045] When the adhesive layer comprises less than 100% by weight of poly(meth)acrylate (based on the total amount of polymers contained), the adhesive layer comprises at least one type of other polymer.

[0046] Particularly preferably, 100% by weight of the polymer contained in the adhesive layer D is a poly(meth)acrylate.

[0047] The poly(meth)acrylate of all embodiments can in principle be any poly(meth)acrylate suitable for use in adhesives.

[0048] "Poly(meth)acrylate" is understood in particular to mean polymers obtainable by radical or anionic polymerization of acrylic and / or methacrylic monomers and, optionally, further copolymerizable monomers. In particular, "poly(meth)acrylate" is understood to mean polymers whose monomer base consists of acrylic acid, methacrylic acid, acrylic acid esters and / or methacrylic acid esters in a proportion of at least 50% by weight, whereby the acrylic acid esters and / or methacrylic acid esters are present at least in proportion, preferably in a proportion of at least 30% by weight, based on the total monomer base of the polymer.

[0049] Preferably, the poly(meth)acrylate comprises at least a proportionately polymerized functional monomer, particularly preferably at least one monomer having at least one functional group selected from the group consisting of carboxylic acid groups, sulfonic acid groups, phosphonic acid groups, hydroxy groups, acid anhydride groups, epoxide groups and amino groups.

[0050] The above groups, with the exception of epoxide groups, are reactive with epoxide groups, so that the poly(meth)acrylates can advantageously be thermally crosslinked with the incorporated epoxides.

[0051] Very particularly preferably, the poly(meth)acrylate comprises at least a proportionately polymerized functional monomer, particularly preferably at least one monomer having at least one functional group selected from the group consisting of carboxylic acid groups and epoxide groups; in particular at least one carboxylic acid group.

[0052] According to a particularly advantageous embodiment, the poly(meth)acrylate comprises polymerized acrylic acid and / or methacrylic acid in proportion, whereby the poly(meth)acrylate, by virtue of its carboxylic acid groups, is reactive with epoxide groups, whereby the poly(meth)acrylate can be advantageously thermally crosslinked with the incorporated epoxides.

[0053] The poly(meth)acrylates can preferably be attributed to the following monomer composition: a) at least one acrylic acid ester and / or methacrylic acid ester represented by the following formula (1): (1) CH 2 =C(R I )(COOR II ) [In the formula, R I is H or CH 3 and R II is an alkyl group having 4 to 18 carbon atoms. B) at least one olefinically unsaturated monomer having at least one functional group selected from the group consisting of a carboxylic acid group, a sulfonic acid group, a phosphonic acid group, a hydroxyl group, an acid anhydride group, an epoxide group, and an amino group; c) optionally further acrylates and / or methacrylates and / or olefinically unsaturated monomers copolymerizable with component (a).

[0054] According to a particularly advantageous embodiment, the poly(meth)acrylates are based on a monomer composition which comprises monomers of group a) in a proportion of 93 to 99% by weight and monomers of group b) in a proportion of 1 to 7% by weight.

[0055] By using such poly(meth)acrylates in the adhesive layer (D) of the adhesive tape according to the invention, a particularly good property profile is achieved, including adhesion, impact resistance as well as residue-free peelability.

[0056] The monomers of component a) are generally softening, rather non-polar monomers. Particularly preferred are R II is an alkyl group having 4 to 10 carbon atoms. The monomer of formula (1) is in particular selected from the group consisting of n-butyl acrylate, n-butyl methacrylate, n-pentyl acrylate, n-pentyl methacrylate, n-amyl acrylate, n-hexyl acrylate, n-hexyl methacrylate, n-heptyl acrylate, n-octyl acrylate, n-octyl methacrylate, n-nonyl acrylate, isobutyl acrylate, isooctyl acrylate, isooctyl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, 2-propylheptyl acrylate and 2-propylheptyl methacrylate.

[0057] Particularly preferably, the monomers of formula (1) or of group (a) are selected from the group consisting of n-butyl acrylate, n-hexyl acrylate, n-octyl acrylate, isooctyl acrylate, 2-ethylhexyl acrylate and 2-propylheptyl acrylate.

[0058] The above-mentioned monomers can be particularly easily polymerized, and the glass transition temperature of the produced poly(meth)acrylates can be particularly easily adjusted, so that optimized properties can be achieved again in terms of flow and adhesion, which are also adapted in each case to the substrate or component to be bonded.

[0059] The monomers of formula (1) or of group (a) are again preferably selected from the group consisting of n-butyl acrylate, isooctyl acrylate and 2-ethylhexyl acrylate.

[0060] Very particular preference is given to using n-butyl acrylate and 2-ethylhexyl acrylate as monomers of formula (1) or of group a).

[0061] Monomers of group b) are particularly preferably selected from the group consisting of acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, crotonic acid, aconitic acid, dimethylacrylic acid, β-acryloyloxypropionic acid, trichloroacrylic acid, vinylacetic acid, vinylphosphonic acid, maleic anhydride, hydroxyethyl acrylate, 2-hydroxyethyl acrylate, hydroxypropyl acrylate, 3-hydroxypropyl acrylate, hydroxybutyl acrylate, 4-hydroxybutyl acrylate, hydroxyhexyl acrylate, 6-hydroxyhexyl acrylate, hydroxyethyl methacrylate, 2-hydroxyethyl methacrylate, hydroxypropyl methacrylate, 3-hydroxypropyl methacrylate, hydroxybutyl methacrylate, 4-hydroxybutyl methacrylate, hydroxyhexyl methacrylate, 6-hydroxyhexyl methacrylate, allyl alcohol, glycidyl acrylate, glycidyl methacrylate.

[0062] Preferably, the monomers of group b) are selected from acrylic acid, methacrylic acid and hydroxyethyl acrylate.

[0063] Very particular preference is given to using acrylic acid as monomer from group b).

[0064] Exemplary monomers of component c) are: methyl acrylate, ethyl acrylate, propyl acrylate, methyl methacrylate, ethyl methacrylate, benzyl acrylate, benzyl methacrylate, sec-butyl acrylate, tert-butyl acrylate, phenyl acrylate, phenyl methacrylate, isobornyl acrylate, isobornyl methacrylate, tert-butylphenyl acrylate, tert-butylphenyl methacrylate, dodecyl methacrylate, isodecyl acrylate, lauryl acrylate, n-undecyl acrylate. acrylate, stearyl acrylate, tridecyl acrylate, behenyl acrylate, cyclohexyl methacrylate, cyclopentyl methacrylate, phenoxyethyl acrylate, phenoxyethyl methacrylate, 2-butoxyethyl methacrylate, 2-butoxyethyl acrylate, 3,3,5-trimethylcyclohexyl acrylate, 3,5-dimethyladamantyl acrylate, 4-cumylphenyl methacrylate, cyanoethyl acrylate, cyanoethyl methacrylate, 4-biphenyl acrylate, 4-biphenyl Nyl methacrylate, 2-naphthyl acrylate, 2-naphthyl methacrylate, tetrahydrofurfuryl acrylate, diethylaminoethyl acrylate, diethylaminoethyl methacrylate, dimethylaminoethyl acrylate, dimethylaminoethyl methacrylate, 3-methoxyacrylic acid methyl ester, 3-methoxybutyl acrylate, 2-phenoxyethyl methacrylate, butyl diglycol methacrylate, ethylene glycol acrylate, ethylene glycol monomethyl acrylate, methoxypolyethylene glycol methacrylate 350, methoxypolyethylene glycol methacrylate 500, propylene glycol monomethacrylate, butoxydiethylene glycol methacrylate, ethoxytriethylene glycol methacrylate, octafluoropentyl acrylate, octafluoropentyl methacrylate, 2,2,2-trifluoroethyl methacrylate, 1,1,1,3,3,3-hexafluoroisopropyl acrylate, 1,1,1,3,3,3-hexafluoroisopropyl methacrylate, 2,2,3,3,3-Pentafluoropropyl methacrylate, 2,2,3,4,4,4-hexafluorobutyl methacrylate, 2,2,3,3,4,4,4-heptafluorobutyl acrylate, 2,2,3,3,4,4,4-heptafluorobutyl methacrylate, 2,2,3,3,4,4,5,5,6,6,7,7,8,8,8-pentadecafluorooctyl methacrylate, dimethyl-aminopropyl acrylamide, dimethylaminopropyl methacrylamide, N-(1-methylundecyl)acrylamide, N-(n-butoxymethyl)acrylamide, N-(butoxymethyl)methacrylamide, N-(ethoxymethyl)acrylamide, N-(n-octadecyl)acrylamide; N,N-dialkyl-substituted amides such as N,N-dimethylacrylamide and N,N-dimethylmethacrylamide; N-benzyl acrylamide, N-isopropyl acrylamide, N-tert-butyl acrylamide, N-tert-octylacrylamide, N-methylolacrylamide, N-methylol methacrylamide, acrylonitrile, methacrylonitrile; vinyl ethers, such as vinyl methyl ether, ethyl vinyl ether, vinyl isobutyl ether; vinyl esters, such as vinyl acetate; vinyl halides, vinylidene halides, vinylpyridine, 4-vinylpyridine, N-vinylphthalimide, N-vinyl lactams, N-vinylpyrrolidone, styrene, α- and p-methylstyrene, α-butylstyrene, 4-n-butylstyrene, 4-n-decylstyrene, 3,4-dimethoxystyrene; macromonomers, such as 2-polystyreneethyl methacrylate (weight average molecular weight Mw, determined by GPC, from 4000 to 13000 g / mol), poly(methyl methacrylate)ethyl methacrylate (Mw from 2000 to 8000 g / mol). ,

[0065] The monomer of component c) can be advantageously selected so that it contains a functional group that supports subsequent radiation-chemical crosslinking (e.g. crosslinking by electron beam or UV radiation).Suitable copolymerizable photoinitiators are, for example, benzoin acrylate and acrylate-functionalized benzophenone derivatives.Monomers that support crosslinking by electron beam irradiation are, for example, tetrahydrofurfuryl acrylate, N-tert-butylacrylamide and allyl acrylate.

[0066] Preferably, the poly(meth)acrylate is a polyacrylate prepared by polymerizing n-butyl acrylate and / or n-hexyl acrylate and / or n-octyl acrylate and / or isooctyl acrylate and / or 2-ethylhexyl acrylate and / or 2-propylheptyl acrylate, and acrylic acid.

[0067] Particularly preferably, the poly(meth)acrylate is a polyacrylate prepared by polymerizing n-butyl acrylate, 2-ethylhexyl acrylate and acrylic acid.

[0068] This results in a particularly high adhesion of the adhesive layer D. The adhesive tape according to the invention therefore has a particularly high adhesion, in particular also when the adhesive tape is applied with at least one side of the adhesive layer D.

[0069] The preparation of said poly(meth)acrylate is preferably carried out by conventional radical polymerization or controlled radical polymerization.The said poly(meth)acrylate can be prepared by copolymerizing monomers using conventional polymerization initiators and optionally regulators, and is polymerized at normal temperatures in bulk, in emulsion, for example in water or liquid hydrocarbons, or in solution.

[0070] The poly(meth)acrylates are preferably prepared in a solvent, particularly preferably in a solvent having a boiling range of from 50 to 150° C., in particular from 60 to 120° C., using from 0.01 to 5% by weight, in particular from 0.1 to 2% by weight, of a polymerization initiator, in each case based on the total weight of the monomers.

[0071] In principle, all customary initiators are suitable. Examples of radical sources are peroxides, hydroperoxides and azo compounds, such as bis(4-tert-butylcyclohexyl) peroxydicarbonate, dibenzoyl peroxide, cumene hydroperoxide, cyclohexanone peroxide, di-t-butyl peroxide, cyclohexylsulfonylacetyl peroxide, diisopropyl percarbonate, t-butyl peroctoate and benzpinacol. A preferred radical initiator is 2,2'-azobis(2-methylbutyronitrile) (Vazo® 67 from DuPont). TM ) or 2,2'-azobis(2-methylpropionitrile) (2,2'-azobisisobutyronitrile; AIBN; Vazo® 64 from DuPont TM ).

[0072] According to a preferred embodiment, bis-(4-tert-butylcyclohexyl) peroxydicarbonate is used.

[0073] Preferred solvents for the preparation of the poly(meth)acrylates are alcohols, such as methanol, ethanol, n- and iso-propanol, n- and iso-butanol, especially isopropanol and / or isobutanol; hydrocarbons, such as toluene and especially mineral spirits boiling in the range from 60 to 120° C.; ketones, especially acetone, methyl ethyl ketone, methyl isobutyl ketone; esters, such as ethyl acetate, as well as mixtures of the abovementioned solvents. Particularly preferred solvents are mixtures which contain isopropanol in an amount of from 2 to 15% by weight, especially from 3 to 10% by weight, in each case based on the solvent mixture used.

[0074] After the preparation of the poly(meth)acrylate, it can be further processed from solution or can be concentrated, and the further processing of the poly(meth)acrylate can be carried out essentially without solvent.The concentration of the polymer can be carried out in the absence of crosslinker and accelerator substances.However, one of these compound classes can be added to the polymer already before concentration, i.e., in that case, concentration is carried out in the presence of this (these) substances.

[0075] The polymer can be transferred to a blender after the concentration step. Optionally, concentration and blending can be carried out in the same reactor.

[0076] The weight average molecular weight (weight average of molecular weight distribution) of the poly(meth)acrylate or poly(meth)acrylates is preferably in the range of from 20,000 to 2,000,000 g / mol, particularly preferably in the range of from 100,000 to 1,500,000 g / mol, very particularly preferably in the range of from 150,000 to 1,000,000 g / mol. In this regard, it may be advantageous to carry out the polymerization in the presence of a suitable polymerization regulator, such as a thiol, a halogen compound, and / or an alcohol, in order to adjust the desired average molecular weight.

[0077] With such an Mw of the poly(meth)acrylate(s) (including all levels of preferred embodiments), sufficient cohesive strength of the adhesive is achieved with simultaneous good flow and good adhesion, which is optimized to a greater extent in the higher levels of preferred embodiments with respect to the property profile of said properties.

[0078] Mw determination is done by GPC as described under "Test Methods."

[0079] The poly(meth)acrylates, measured in toluene (1% strength by weight solution at 21° C.), preferably have a K value of from 30 to 90, particularly preferably a K value of from 40 to 70. The K value according to the Fikentscher method is a measure for the molecular weight and viscosity of the polymer.

[0080] The principle of the method is based on the determination of the relative solution viscosity by means of a capillary viscometer. For this, the test substance is dissolved in toluene by shaking for 30 minutes, thus obtaining a 1% strength solution. The efflux time is measured at 25°C in a Vogel-Ossag viscometer, on the basis of which the relative viscosity of the sample solution is determined in relation to the viscosity of the pure solvent. Based on the Fikentscher method [PE Hinkamp, ​​Polymer, 1967, 8, 381 (Non-Patent Document 2)], the K value can be read off from a table (K=1000k).

[0081] Preferably, the poly(meth)acrylate has a polydispersity PD of <4, and therefore a relatively narrow molecular weight distribution. The adhesive based thereon has particularly good shear strength after crosslinking, despite its relatively low molecular weight. In addition, a relatively low polydispersity allows it to be processed in melt form relatively easily, since it has a lower flow viscosity than more widely distributed poly(meth)acrylates, with roughly the same application properties. Narrowly distributed poly(meth)acrylates can be advantageously produced by anionic or controlled radical polymerization, with controlled radical polymerization being particularly well suited. The corresponding poly(meth)acrylates can also be produced via N-oxyl. Atom transfer radical polymerization (ATRP) can also be advantageously used to synthesize narrowly distributed poly(meth)acrylates, with the use of mono- or difunctional secondary or tertiary halides as initiators, and preferably Cu, Ni, Fe, Pd, Pt, Ru, Os, Rh, Co, Ir, Ag or Au complexes for halide abstraction. RAFT polymerization is also suitable.

[0082] The poly(meth)acrylate is preferably crosslinked by a thermal crosslinking agent by a crosslinking reaction (particularly in the sense of an addition or substitution reaction) of the functional groups contained therein, such as carboxylic acid groups in particular. This has the advantage that the adhesive is not too soft and has a not too high cold flow. This has an advantageous effect on the cohesion of the adhesive as well as on the storage and processability of the adhesive.

[0083] The thermal crosslinking agent is - ensure a sufficiently long processing time, so that gelation does not occur during the processing process, in particular the extrusion process, In addition, it also brings about a rapid postcrosslinking of the polymer to the desired degree of crosslinking at temperatures below the processing temperature, in particular at room temperature. Any thermal crosslinking agent can be used.

[0084] For example, a combination of polymers containing carboxy-(carboxylic acid-), amino- and / or hydroxy groups with isocyanates, especially aliphatic or blocked isocyanates, such as trimer isocyanates deactivated with amines, is possible as crosslinking agents. Suitable isocyanates are in particular the trimer derivatives of MDI [4,4-methylenedi(phenylisocyanate)], HDI [hexamethylene diisocyanate, 1,6-hexylene diisocyanate] and IPDI [isophorone diisocyanate, 5-isocyanato-1-isocyanatomethyl-1,3,3-trimethylcyclohexane].

[0085] The thermal crosslinking agent is preferably used in an amount of 0.1 to 5% by weight, particularly 0.2 to 1% by weight, based on the total amount of the polymer to be crosslinked.

[0086] Cross-linking is also possible using complexing agents, also called chelates. A preferred complexing agent is, for example, aluminium acetylacetonate.

[0087] Preferably, the poly(meth)acrylates are crosslinked with epoxide(s) or with one or more epoxide group-containing substances(s), thereby ensuring permanent and irreversible crosslinking.

[0088] The epoxide group-containing substance is in particular a polyfunctional epoxide, i.e. a polyfunctional epoxide having at least two epoxide groups; thus, in summary, an indirect linking of the functionalized components of the poly(meth)acrylate occurs. The epoxide group-containing substance can be an aromatic or aliphatic compound.

[0089] Particularly suitable polyfunctional epoxides are oligomers of epichlorohydrin, epoxy ethers of polyhydric alcohols (especially ethylene glycol, propylene glycol, and butylene glycol, polyglycols, thiodiglycol, glycerin, pentaerythritol, sorbitol, polyvinyl alcohol, polyallyl alcohol, and the like); polyhydric phenols (especially resorcinol, hydroquinone, bis-(4-hydroxyphenyl)-methane, bis-(4-hydroxy-3-methylphenyl)-methane, bis-(4-hydroxy-3,5-dibromophenyl)-methane, bis-(4-hydroxy-3,5-difluorophenyl)-methane, 1,1-bis-(4-hydroxyphenyl)ethane, 2,2-bis-(4-hydroxyphenyl)propane, 2,2-bis-(4-hydroxy-3-methylphenyl)-propane, 2,2-bis-(4-hydroxy-3-chlorophenyl)-propane, 2,2-bis-(4-hydroxyphenyl) ... -3,5-dichlorophenyl)-propane, 2,2-bis-(4-hydroxy-3,5-dichlorophenyl)-propane, bis-(4-hydroxyphenyl)-phenylmethane, bis-(4-hydroxyphenyl)-phenylmethane, bis-(4-hydroxyphenyl)diphenylmethane, bis(4-hydroxyphenyl)-4'-methylphenylmethane, 1,1-bis-(4-hydroxyphenyl)-2,2,2-trichloroethane, bis-(4-hydroxyphenyl)-(4-chlorophenyl)-methane, 1,1-bis-(4-hydroxyphenyl)-cyclohexane, bis-(4-hydroxyphenyl)-cyclohexylmethane, 4,4'-dihydroxydiphenyl, 2,2'-dihydroxydiphenyl, 4,4'-dihydroxydiphenylsulfone] epoxy ethers and their hydroxyethyl ethers, phenol-formaldehyde condensation products, such as phenol alcohols, and phenol aldehyde resins; S-containing and N-containing epoxides (e.g. N,N-diglycidylaniline, N,N'-dimethyldiglycidyl-4,4-diaminodiphenylmethane, tetraglycidyl-meta-xylylenediamine) and epoxides prepared according to conventional methods from monounsaturated carboxylic acid esters of polyunsaturated carboxylic acids or unsaturated alcohols; glycidyl esters;Polyglycidyl esters that can be obtained by polymerization or mixed polymerization of glycidyl esters of unsaturated acids or obtained from other acidic compounds, such as cyanuric acid, diglycidyl sulfide, or cyclic trimethylene trisulfone, or derivatives thereof;

[0090] Very suitable ethers are, for example, 1,4-butanediol diglycid ether, polyglycerol-3-diglycid ether, cyclohexanedimethanol diglycid ether, glycerol triglycid ether, neopentyl glycol diglycid ether, pentaerythritol tetraglycid ether, 1,6-hexanediol diglycid ether, polypropylene glycol diglycid ether, trimethylolpropane triglycid ether, pentaerythritol tetraglycid ether, bisphenol-A diglycid ether and bisphenol-F diglycid ether.

[0091] Yet other preferred epoxides are cycloaliphatic epoxides such as 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate (UVACure 1500).

[0092] According to a preferred embodiment, tetraglycidyl-meta-xylylenediamine is used as the crosslinking agent.

[0093] According to a preferred embodiment, the poly(meth)acrylates are crosslinked using a crosslinker-accelerator system ("crosslinker system") in order to obtain better control over processing time, crosslinking rate as well as crosslinking degree. The crosslinker-accelerator system preferably comprises at least one epoxide group-containing substance as crosslinker and at least one substance as accelerator which acts to accelerate the crosslinking reaction with the epoxide group-containing compound at a temperature below the melt viscosity of the polymer to be crosslinked.

[0094] As accelerator, the present invention particularly preferably uses amines.These can be formally understood as substitution products of ammonia; the substituents include, in particular, alkyl and / or aryl groups.Particularly preferably, the amines that do not react or react only slightly with the polymer to be crosslinked are used.

[0095] In principle, accelerators include primary amines (NRH 2 ), secondary amines (NR 2 H), and tertiary amines (NR 3 ), and of course amines with multiple primary and / or secondary and / or tertiary amino groups can also be selected. Particularly preferred accelerators are tertiary amines, such as triethylamine, triethylenediamine, benzyldimethylamine, dimethylaminomethylphenol, 2,4,6-tris-(N,N-dimethylaminomethyl)-phenol, N,N'-bis(3-(dimethylamino)propyl)urea. Further preferred accelerators are polyfunctional amines, such as diamines, triamines and / or tetraamines, such as diethylenetriamine, triethylenetetramine, trimethylhexamethylenediamine.

[0096] Further preferred accelerators are amino alcohols, in particular secondary and / or tertiary amino alcohols, where, if there are several amino functions per molecule, preferably at least one, particularly preferably all, of the amino functions are secondary and / or tertiary. Particularly preferred such accelerators are triethanolamine, N,N-bis(2-hydroxypropyl)ethanolamine, N-methyldiethanolamine, N-ethyldiethanolamine, 2-aminocyclohexanol, bis(2-hydroxycyclohexyl)methylamine, 2-(diisopropylamino)ethanol, 2-(dibutylamino)ethanol, N-butyldiethanolamine, N-butylethanolamine, 2-[bis(2-hydroxyethyl)amino]-2-(hydroxymethyl)-1,3-propanediol, 1-[bis(2-hydroxyethyl)amino]-2-propanol, triisopropanolamine, 2-(dimethylamino)ethanol, 2-(diethylamino)ethanol, 2-(2-dimethylaminoethoxy)ethanol, N,N,N'-trimethyl-N'-hydroxyethylbisaminoethylether, N,N,N'-trimethylaminoethylethanolamine and N,N,N'-trimethylaminopropylethanolamine.

[0097] Further suitable accelerators are pyridine, imidazoles, such as 2-methylimidazole and 1,8-diazabicyclo[5.4.0]undec-7-ene. Cycloaliphatic polyamines can also be used as accelerators. Phosphorus-based accelerators, such as phosphines and / or phosphonium compounds, such as triphenylphosphine or tetraphenylphosphonium tetraphenylborate, are also suitable.

[0098] Quaternary ammonium compounds may also be used as accelerators; examples include tetrabutylammonium hydroxide, cetyltrimethylammonium bromide, and benzalkonium chloride.

[0099] The first adhesive layer D preferably contains 2 to 10 wt %, particularly preferably 4 to 6 wt %, of an electrolyte, preferably an ionic liquid, relative to 100 wt % of the polymer contained therein, and in this case, the polymer is preferably 100 wt % poly(meth)acrylate.

[0100] The use of the electrolyte, especially the ionic liquid, in such preferred or particularly preferred amounts allows for relatively rapid electrical peeling, while at the same time the adhesion of the adhesive layer to adjacent layers, especially to at least one substrate, is not negatively affected prior to peeling.

[0101] In the present invention, the adhesive layer D is foamed, the foaming being brought about by means of microballoons which have on their surface a layer made of silicate or alumosilicate.

[0102] By "microballoons" is meant microhollow spheres that are elastic and therefore expandable in their base state and have a thermoplastic polymer shell. These spheres are filled with a low-boiling liquid or liquefied gas. As shell materials, in particular polyacrylonitrile, PVDC, PVC or polyacrylates are used. As low-boiling liquids or gases, in particular hydrocarbons of lower alkanes, for example isobutane or isopentane, are suitable, which are enclosed in the polymer shell under pressure as liquefied gas, with isopentane being particularly preferred.

[0103] In particular, by acting on the microballoons by the action of heat, the outer polymer shell becomes soft. At the same time, the liquid foaming gas present in the shell changes to its gaseous state. The microballoons then irreversibly expand and expand three-dimensionally. The expansion ends when the internal and external pressures become equal. The polymer shell remains intact, resulting in a closed-cell foam.

[0104] Numerous types of microballoons are commercially available, which differ essentially in their size (diameter in the unexpanded state from 6 to 45 μm) and in the initial temperature required for expansion (from 75 to 220° C.). Examples of commercially available microballoons are Expancel® DU-type (DU = dry unexpanded) from Nuryon or Microsphere® FN-type from Matsumoto.

[0105] Microballoons often have an inorganic layer on their surface for stabilization, which can be, for example, a silicate or an alumosilicate, but also carbonates, such as calcium carbonate, or various oxides, can be used.

[0106] Surprisingly, within the scope of the present invention, it is possible to produce an adhesive layer D which is electro-releaseable and therefore contains an electrolyte and is simultaneously foamed, simply by using microballoons which have a layer of silicate or alumosilicate on their surface.

[0107] Silicates are orthosilicic acid (Si(OH) 4 ) and their condensates. All salts are SiO 4 It is a compound composed of tetrahedra, but the tetrahedra can be bonded to each other in various ways. The free sites of the tetrahedra contribute to the charge balance of the metal cation or sometimes to hydroxide ions (OH - Alumosilicates exist as SiO as their basic building block. 4 Tetrahedron and AlO 4 It is the name of a collection of compounds from the group of silicates composed of tetrahedrons.

[0108] Furthermore, a distinction can be made between unexpanded and pre-expanded microballoons. In principle, within the scope of the present invention, the use of unexpanded and / or pre-expanded microballoons is conceivable.

[0109] In this case, the unexpanded microballoons are usually added to the adhesive in an unexpanded state and only afterwards do they take on an expansion effect, in particular by heating.

[0110] The unexpanded type microballoons can be obtained as aqueous dispersions with a solids content or microballoon content of about 40 to 45% by weight, and also as polymer-bound microballoons (masterbatch) with a microballoon concentration of about 65% by weight (e.g. in ethyl vinyl acetate). Both the microballoon dispersions and the masterbatches are suitable for producing foamed adhesives, as are the DU types.

[0111] The foamed adhesive layer can also be produced using so-called pre-expanded microballoons. In the case of pre-expanded microballoons, the expansion has already taken place before mixing into the polymer matrix. Pre-expanded microballoons are commercially available, for example under the name Dualite®. In the processing of microballoons of the already expanded type, it can happen that the microballoons, due to their small density in the polymer matrix in which they are to be incorporated, tend to float, i.e. float "upwards" during the processing process in the polymer matrix. This leads to an uneven distribution of the microballoons in the layer. In the upper regions of the layer (z-direction), there are more microballoons than in the lower regions of the layer, which results in a density gradient across the layer thickness.

[0112] In order to largely or almost completely prevent such density gradients, the present invention preferably incorporates non-pre-expanded or only slightly pre-expanded (and therefore expandable) microballoons into the polymer matrix of the adhesive layer. The microballoons are expanded only after they are incorporated into the layer. In this way, a more uniform distribution of the microballoons is obtained in the polymer matrix.

[0113] Only after compounding or directly during compounding does the expansion of the expandable microballoons occur, thereby resulting in foaming. In the case of solvent-containing adhesives, the microballoons are preferably expanded only after compounding, coating and drying (solvent evaporation).

[0114] Therefore, according to a preferred embodiment of the present invention, the adhesive layer D is foamed, the foaming being brought about by the expansion of expandable microballoons, the expandable microballoons having a layer made of silicate or alumosilicate on their surface.

[0115] The average diameter of the hollow space formed by the microballoons in the foamed adhesive layer(s) is preferably from 10 to 200 μm, particularly preferably from 15 to 200 μm, very particularly preferably from 15 to 150 μm, even more preferably from 20 to 100 μm, and even more particularly preferably from 25 to 70 μm. By using the above-mentioned preferred and particularly preferred size ranges, particularly good impact resistance is achieved. At the same time, the size is adapted to the layer thickness of the adhesive layer(s).

[0116] In this case, the diameter of the hollow space formed by the microballoons in the foamed adhesive layer is measured, so that the diameter is the diameter of the hollow space formed by the expanded microballoons. The above-mentioned average diameter here means the arithmetic calculation of the diameter of the hollow space formed by the microballoons in the adhesive layer. The determination of the average diameter of the hollow space formed by the microballoons in the adhesive layer is carried out on the basis of five different cryosection edges of the adhesive tape in a scanning electron microscope (REM) at a magnification of 500 times. The diameter of the microballoons visible in the photograph is determined graphically from the REM photograph of each individual microballoon of the adhesive layer examined by taking its largest dimension in any (two-dimensional) direction and considering it as its diameter.

[0117] The microballoons can be provided to the formulation as a batch, a paste, or as a neat or diluted powder. Additionally, the microballoons can be present in suspension in a solvent.

[0118] The proportion of microballoons in the adhesive layer, according to an embodiment of the invention, is between more than 0 and 12% by weight, particularly preferably between 0.25 and 5% by weight, very particularly preferably between 0.5 and 3% by weight, each based on the total composition (including the incorporated microballoons) of the corresponding layer.

[0119] The above amounts provide a particularly good compromise between the objectives of properties such as adhesion, flow behavior and foaming.

[0120] The adhesive of the adhesive layer D may further comprise other conventional additives, such as tackifying resins, softeners, compatibilizers and fillers. As compatibilizers, preferably low molecular weight polyethers, polyamines, polyvinylpyrrolidones or aliphatic polyesters are used, which can be homogeneously mixed with the adhesive. Some softeners can also be compatibilizers at the same time, for example polyethylene glycol (PEG). According to a particularly preferred embodiment, the adhesive of the adhesive layer D comprises at least one polyether, preferably at least one substance selected from the group consisting of polyethylene glycol (PEG), polypropylene glycol (PPG), polytetrahydrofuran, with PEG and PPG being particularly preferred. The use of them aids in particularly good peelability. Without intending to be bound by a particular theory, it can be considered that the above-mentioned substances, especially PEG, accelerate the ionic flow of the electrolyte(s) flowing through the adhesive layer.

[0121] The molecular weight (by GPC) of the above substances is preferably between 100 and 5000 g / mol, particularly preferably between 200 and 2000 g / mol. The skilled person is aware that PEGs and PPGs with different molecular weights Mw are available, for example PEG400 or PPG600 (numbers representing Mw).

[0122] A further object of the present invention is to provide a composition comprising at least the following layers: a first substrate A; and a second substrate B; and an adhesive tape according to the invention, which is arranged between a substrate A and a substrate B and which bonds substrates A and B to one another; A bonded joint comprising:

[0123] A further object of the present invention is to provide a method for producing a method for producing a semiconductor device comprising the steps of: i.) applying a voltage to two different points of the junction, the voltage being preferably between 2 and 20 V, particularly preferably between 3 and 15 V; The method for electrical delamination of a bonded body according to the present invention comprises:

[0124] The application of a voltage is carried out according to step i.) of the method of the invention for the electrical detachment of the bonded bodies. The voltage is in particular a direct current voltage.

[0125] The duration of the voltage application in step i.) can hereby be from a few seconds, in particular 2 seconds, up to 300 seconds, preferably up to 120 seconds.

[0126] The method according to the invention for the electrical delamination of the bonded assembly according to the invention allows the substrates A and B to be quickly and simply delaminated from one another without the need for the application of excessively large forces.

[0127] If the layers do not peel off from each other without further action after the application of the voltage, the method according to the invention comprises at least the following process steps: ii.) applying a force to adhesive layer D and / or substrate A and / or substrate B to increase the distance between substrate A and substrate B; Includes.

[0128] The possibly further necessary force according to step ii.) is clearly smaller than the adhesion force before the application of the voltage according to step i.).

[0129] The application of the voltage according to step i.) is carried out at two different points of the bonded assembly according to the invention: where the voltage is advantageously applied depends on the structure of the adhesive tape and of the bonded assembly and thus on the nature of the individual layers and of the substrates A and B bonded to one another.

[0130] Below, some preferred embodiments are described.

[0131] In a preferred embodiment, the adhesive tape is a transfer adhesive tape and is made of adhesive D.

[0132] Such an adhesive tape can advantageously be electrically peeled off in a bonded assembly having two substrates A and B, both of which are electrically conductive. For this purpose, a voltage is applied to the substrates A and B, which then causes anions to migrate to the anode and cations to the cathode in the adhesive. Without intending to be bound by a particular theory, the inventors assume the following mechanism: the application of a voltage causes migration of the electrolyte in the adhesive layer D, in particular separation of the anions and cations of the ionic liquid. This greatly weakens the adhesion of the adhesive layer D to the substrates A and B, and these layers peel off from each other.

[0133] Thus, according to a preferred embodiment of the invention, the bonded assembly comprises the following layers: an electrically conductive first substrate A; and an electrically conductive second substrate B; and An adhesive tape according to the invention, which comprises an adhesive layer D, which is arranged between substrate A and substrate B and which bonds substrate A and substrate B to one another.

[0134] According to yet another preferred embodiment, the adhesive tape comprises, in addition to the first adhesive layer D, at least the following layers: a second adhesive layer C; and At least one electrically conductive carrier layer T arranged between layers D and C.

[0135] Such an adhesive tape can be adapted as a double-sided adhesive tape via the second adhesive layer C to a large number of different substrates, in which case these can in principle be the same substrates as in the previously described embodiments in which the adhesive tape is a transfer adhesive tape.

[0136] In addition, however, such adhesive tapes can in particular and advantageously also be used for the subsequent peeling off of substrates A and B from one another, where only one substrate, for example only substrate A, is electrically conductive.

[0137] According to a preferred embodiment, xi.) only the carrier layer T or xii.) the carrier layer T and the second adhesive layer C are designed to be electrically conductive.

[0138] Thereby, a voltage can be applied to xi) the electrically conductive carrier layer or xii) the second adhesive layer C and the conductive substrate A.

[0139] The adhesive tape is advantageously pre-applied as a double-sided adhesive tape, with an electrically releasable adhesive layer D bonded to a conductive substrate A and a second adhesive layer bonded to a substrate B, which may, but need not, be conductive.

[0140] Without intending to be bound by any particular theory, the inventors postulate the following mechanism: application of a voltage causes migration of electrolytes, particularly separation of anions and cations of the ionic liquid, in adhesive layer D. This strongly weakens the adhesion of adhesive layer D to substrate A, causing these substrates to peel off from each other.

[0141] According to a preferred embodiment of the invention, xi.) only the carrier layer is electrically conductive. In particular and preferably, if the carrier layer extends laterally beyond at least one of the adhesive layers, a voltage can be applied to it particularly well.

[0142] According to yet another preferred embodiment of the invention, xii.) the carrier layer and the second adhesive layer C are electrically conductive. Such a construction has the advantage that a voltage can be applied to the adhesive layer C. No lateral overhang of the carrier layer is necessary. The adhesive tape is therefore particularly simple to produce, in particular because the layers D, T and C can be die-cut together.

[0143] Preferably, the adhesive tape according to the embodiment described above is composed of the three aforementioned layers D, T and C. For this purpose, within the framework of the present invention, the term three-layer assembly DTC is also used.

[0144] Thus, according to a preferred embodiment of the invention, the bonded assembly comprises the following layers: an electrically conductive first substrate A; and a second substrate B; and An adhesive tape according to the invention, which consists of said three-layer composite DTC and which adheres a substrate A and a substrate B to one another such that the adhesive layer D is bonded to the conductive substrate A.

[0145] According to yet another preferred embodiment, the adhesive tape comprises, in addition to the first adhesive layer D, at least the following layers: a second adhesive layer C; and at least one first electrically conductive carrier layer T, which is arranged between layer D and layer C; and at least one second electrically conductive carrier layer T' arranged on the surface of the adhesive layer D opposite to the first electrically conductive carrier layer T; and A third adhesive layer C' disposed on a surface of the second electrically conductive carrier layer T' opposite to the first adhesive layer D.

[0146] Such an adhesive tape has at least the layer structure CTD-R'-C' and, as a double-sided adhesive tape, can be adapted via the adhesive layers C and C' to a large number of different substrates.

[0147] In this case, in principle these can be the same substrates as in the previous embodiments in which the adhesive tape is a transfer adhesive tape or has a three-layer DTC.

[0148] However, such adhesive tapes can also be used in particular and advantageously for the subsequent peeling off of substrates A and B, neither of which is electrically conductive, from one another.

[0149] According to a preferred embodiment, xi.) only the carrier layers T and T' or xii.) the carrier layers T and T' and also the second adhesive layer C and / or the third adhesive layer C' are designed to be electrically conductive.

[0150] Thereby, a voltage can be applied to xi.) both electrically conductive carrier layers or xii.) to at least one of the adhesive layers C and C' and to one of the carrier layers or the other adhesive layer.

[0151] As in the previous embodiment, application of a voltage is believed to cause migration of the electrolyte, in particular separation of the anions and cations of the ionic liquid, in the adhesive layer D. This significantly weakens the adhesion of the adhesive layer D to the electrically conductive carrier layers T and T′, and causes delamination of these layers from each other.

[0152] According to a preferred embodiment of the invention, xi.) only the carrier layers T and T' are electrically conductive. In particular and preferably, a voltage can be applied to the carrier layers T and T' particularly well if they extend laterally beyond at least one of the adhesive layers adjacent thereto.

[0153] According to yet another preferred embodiment of the invention, xii.) the carrier layers T and T' and the second and third adhesive layers C or C' are electrically conductive. Such a construction has the advantage that a voltage can be applied to the adhesive layers C and C'. No lateral overhang of the carrier layers T and T' is necessary. The adhesive is therefore simple to manufacture, especially since the layers C, T, D, T' and C' can be die-cut together.

[0154] Preferably, the adhesive tape according to the above-mentioned embodiment is composed of five layers C, T, D, T' and C', for which purpose within the framework of the present application the term five-layer assembly CTD-T'-C' is also used.

[0155] Thus, according to a preferred embodiment of the invention, the bonded assembly comprises the following layers: a first substrate A; and a second substrate B; and An adhesive tape according to the invention, which consists of a five-layer assembly CTD-T'-C' and which bonds substrates A and B to one another.

[0156] The electrically conductive substrate in all embodiments can be, for example, the metallic housing of a mobile telephone.

[0157] The electrically non-conductive substrate of all embodiments may in particular be a housing made of a non-conductive material, for example a plastic, or a battery or a component designed to be non-electrically conductive, for example a speaker.

[0158] A further subject of the invention is the use of the adhesive tape according to the invention for bonding components in electronic devices, automobiles, medical devices and dental devices.

[0159] The carrier layers T as well as T and T' in all the embodiments described above are electrically conductive.

[0160] These layers are further described below. For the sake of brevity, the term "electrically conductive carrier layer" or simply the term "carrier layer" is used, which refers to carrier layer T or to carrier layers T and T', depending on the embodiment.

[0161] The carrier layers T and T' can be designed identically or differently depending on each other.

[0162] Preferably, the electrically conductive carrier layer comprises at least one metal.

[0163] Particularly preferably, the metal is selected from the group consisting of copper, nickel, zinc, tin, silver, gold, aluminum, iron, chromium and alloys of these metals. Very particularly preferably, the metal is selected from the group consisting of aluminum, copper and nickel.

[0164] Preferably, the electrically conductive carrier layer has a layer thickness, measured in the z-direction, ie parallel to the stacking direction of the layer arrangement, of from 10 nm (nanometers) to 50 μm (micrometers).

[0165] The electrically conductive carrier layer comprises, according to a preferred embodiment of the invention, a) at least one metal film, preferably an aluminum film, and / or b) at least one electrically conductive textile comprising at least one metal, preferably at least one metal selected from the group consisting of copper and nickel, and / or c) one or more layers of at least one vapor-deposited metal, preferably at least one vapor-deposited metal selected from the group consisting of copper and aluminum, and / or d) at least one metal grid, and / or e) a vapor-deposited metal film, where in principle it is also conceivable that the layer T comprises a combination of two or more of the above options.

[0166] Metal films, for example and preferably aluminum films, are known to those skilled in the art.

[0167] Preferably, the metal film, for example and preferably the aluminum film, has a layer thickness in the z-direction, ie parallel to the stacking direction of the layer sequence, of from 5 to 50 μm, particularly preferably from 10 to 30 μm.

[0168] Electrically conductive textiles are known to those skilled in the art, in particular under the English name "conductive mesh". In this case, these are textile fabrics, for example textile fabrics made of PET (polyethylene terephthalate), which are coated with a metal, for example copper and / or nickel, thus providing the electrical conductivity of the fabric.

[0169] It is likewise known to the skilled artisan that metals can be vapour-deposited as single or multiple layers directly onto a flat surface, for example here onto the surface of an adhesive layer.Within the scope of the present invention, an electrically conductive carrier layer can be provided by vapour-depositing a metal onto the adhesive layer D or onto the adhesive layer C or onto the adhesive layer C'.

[0170] Furthermore, metal grids of various dimensions are also known to those skilled in the art. Metal grids with the appropriate layer thickness can be produced, for example, by non-crimp weaving of appropriate fine metal threads or by die cutting of at least one film of the appropriate layer thickness.

[0171] In metallized films, non-conductive films are in particular vapor-deposited with metal in order to make them electrically conductive. The material of the film can in principle be selected from all materials suitable for vapor-depositing metals and suitable for use as carrier films for adhesive tapes. The material is in particular selected from polyesters and polyolefins, whereby mixtures of several materials are also conceivable. As polyesters, in particular polyethylene terephthalate (PET) and polyethylene naphthalate (PEN) are preferred. As polyolefins, in particular polypropylene (PP), polyethylene (PE) are preferred. In a preferred embodiment, the material of the film is selected from the group consisting of PET, PEN, PE, PP.

[0172] These are preferably films made of PET (polyethylene terephthalate). Such films are dimensionally stable and therefore can be easily processed without being significantly stretched or torn. This allows a uniform, defect-free metal layer to be applied consistently, so that electrical conductivity (especially in the z-direction) is consistently guaranteed across the entire film.

[0173] In the embodiment in which at least one electrically conductive carrier layer T or at least two electrically conductive carrier layers T and T' are present, these preferably laterally extend beyond at least one adjacent adhesive layer in at least one extension direction of the layer plane and thus have a lateral extension, to which a voltage can then simply be applied.

[0174] In the case of a five-layer assembly, the lateral extensions of the electrically conductive carrier layers T and T' are in an advantageous embodiment arranged spatially separated from one another, which makes it easier to apply a voltage to both extensions.

[0175] In the case of a vapor-deposited metal as carrier layer, it is preferred that this carrier layer only overhangs the adjacent adhesive layer laterally in at least one extension direction of the layer plane, and each further adhesive layer serves as a mechanical support for this metal layer. In this case, the metal layer does not have an inherent carrier function. Instead, the further adhesive layer serves as a carrier for the metal layer. However, for the sake of brevity, the description of a carrier layer for a metal layer is also retained in these embodiments. Preferably, the layer thickness of the layer T in this case is greater than or equal to 10 nm (nanometers), preferably from 50 to 200 nm.

[0176] According to a preferred embodiment of the invention, the electrically conductive carrier layer T or T and / or T' comprises a) at least one metal film, preferably an aluminum film, and / or b) at least one electrically conductive textile, which comprises at least one metal, preferably at least one metal selected from the group consisting of copper and nickel, and / or d) at least one metallic grid, and / or e) a metallized film, and extends in at least one direction beyond the first adhesive layer D and the second adhesive layer C, or the first adhesive layer D and the second adhesive layer C, and / or the first adhesive layer D and the third adhesive layer C'. This allows a voltage to be applied to the carrier layer simply and reliably. At the same time, the adhesive tape can be produced relatively simply.

[0177] According to a preferred embodiment of the present invention, the electrically conductive carrier layer T or T and / or T′ comprises one or more layers, preferably one layer, of at least one evaporated metal, preferably at least one evaporated metal selected from the group consisting of copper and aluminum.

[0178] According to a particularly preferred embodiment of the invention, the electrically conductive carrier layer T or T and / or T' has e) a metallized film and extends in at least one direction of extension beyond the first adhesive layer D. In this case, this film is metallized, in particular on one surface, and the respective carrier layer is connected via the metallized film to the first adhesive layer D and thus to the electrically peelable layer. This makes it possible to apply a voltage to the carrier layers in a simple and reliable manner.

[0179] The expression "lateral overhang" in the context of the present invention means any type of lateral overhang of the layer or layers in question, whereby each layer in question extends further laterally (perpendicular to the stacking direction) than the reference layer, in particular in the "xy" plane. Instead of the expression "lateral overhang", the expressions "lateral extension" or "lateral extension" are also used in the context of the present invention.

[0180] The term "lateral side" here refers to any extension direction "xy" of the layer plane perpendicular to the stacking direction "z" of the layers. This description is therefore independent of the geometric shape of the adhesive tape, in particular in the "xy" plane, which can be rectangular (see above) as is customary for adhesive tapes, or square or circular.

[0181] Slight variations in the dimensions of the individual layers in the "xy" plane, which arise due to die-cutting processes or similar forming processes, are not treated as such, especially since such small material extrusions are not suitable for the deliberate application of voltage thereto due to their dimensions.

[0182] The adhesive layers C or C and C' can in principle be based on the same adhesive as the adhesive layer D, in which case the adhesive of layers C or C and C' does not have to contain an electrolyte, but may, and preferably layers C or C and C' do not contain an electrolyte.

[0183] According to some of the above-described embodiments of the three-layer assembly DTC, the adhesive layer C is electrically conductive.

[0184] Similarly, the adhesive layer C and / or the adhesive layer C' of the five-layer assembly CTD-T'-C' can also be designed to be electrically conductive.

[0185] These layers are further described below. For the sake of brevity, where appropriate, the term "electrically conductive adhesive layer" is used. This refers to adhesive layer C or adhesive layers C and / or C', depending on the embodiment. Furthermore, for the sake of brevity, the expression "adhesive layer C or C and / or C'" is used, which means the respective layer in the above-mentioned embodiment of the adhesive tape comprising at least the above-mentioned three-layer assembly or at least the above-mentioned five-layer assembly. Adhesive layers C and C' are independent of each other and can be the same or different from each other.

[0186] In addition, the electrically conductive adhesive layer preferably comprises at least one metal, such as in particular nickel, copper, silver, preferably in the form of electrically conductive metal particles and / or metal-coated particles, particularly preferably in the form of metal particles. Metal-coated particles are in particular and preferably glass or polymer particles that are metal-coated with at least one metal, so that originally electrically non-conductive particles become electrically conductive due to the metal coating. Particularly preferably, the electrically conductive adhesive layer comprises electrically conductive particles, which are selected from the group consisting of nickel particles, copper particles and silver-coated copper particles. According to a particularly preferred embodiment, the electrically conductive adhesive layer comprises nickel particles.

[0187] Preferably, the electrically conductive adhesive layer comprises from 5 to 40% by weight, particularly preferably from 20 to 40% by weight, very particularly preferably from 25 to 35% by weight, of electrically conductive particles, in particular metal particles and / or metal-coated particles, based on 100% by weight of the polymers and adhesive resins involved.

[0188] The electrically conductive particles are preferably not thicker or not significantly thicker than the thickness of each of the electrically conductive adhesive layers in the z-direction, as measured by optical microscopy. Preferably, the electrically conductive particles have an average particle size of 1 to 10 μm, particularly preferably 1 to 6 μm, even more preferably 3 to 5 μm, for example especially 4 μm.

[0189] The electrically conductive adhesive layer is especially electrically conductive at least in the z-direction. However, it can also be electrically conductive in the xy-plane. If the electrically conductive adhesive layer is only electrically conductive in the z-direction, but not necessarily in the xy-direction, in a preferred embodiment, metal, especially metal particles, are added to make it electrically conductive, less of these materials are required. This allows the adhesive to be optimized with respect to the required conductivity, adhesion, flow behavior and cost.

[0190] Within the scope of the present invention, a layer is considered to be "electrically conductive" if, in particular, the resistance is less than 1 ohm, measured in the respective direction, here in particular in the z-direction, in accordance with the MIL-DTL-83528C standard.

[0191] The following description applies regardless of whether adhesive layer C or C and / or C' is configured to be electrically conductive.

[0192] The adhesive layer C or C and / or C′ is, in a preferred embodiment of the invention, based on poly(meth)acrylate, just like the adhesive layer D. In this case, all the statements made above regarding the definition and the type and amount of poly(meth)acrylate system or poly(meth)acrylate apply.

[0193] According to a preferred embodiment of the invention, the same poly(meth)acrylate is used in the adhesive layer C or C and / or C' as in the adhesive layer D. This allows in particular similar substrates (designated here as A and B) to be bonded to one another. Furthermore, this improves the ageing and heat resistance of the adhesive tape.

[0194] According to yet another preferred embodiment of the invention, a polymer different from the poly(meth)acrylate used in the adhesive layer D is used in the adhesive layer C or C and / or C'. This allows the properties of the conductive layer to be particularly well adapted to the substrate(s) bonded via the adhesive layer C or C and / or C'. The adhesive layer C or C and / or C' preferably does not or does not need to comprise an electrolyte, such as an ionic liquid, so that no components have to be matched thereto.

[0195] According to yet another preferred embodiment of the invention, a poly(meth)acrylate different from the poly(meth)acrylate used in adhesive layer D is used in adhesive layer C or C and / or C'.

[0196] According to yet another preferred embodiment of the invention, in the adhesive layer C or C and / or C' at least one vinyl aromatic block copolymer is included.

[0197] According to preferred embodiments of the invention, the adhesive layer C or C and / or C′ is based on vinyl aromatic block copolymer(s), i.e. according to these embodiments, the vinyl aromatic block copolymer is the main polymer in the adhesive layer, present in a proportion of 70 to 100% by weight, based on 100% by weight of the polymer present in layer C. Any tackifying resins present in the adhesive layer are not counted in this calculation towards the 100% by weight of the polymer present.

[0198] The vinyl aromatic block copolymer(s) can in principle be of any type known to those skilled in the art.

[0199] Preferably, the vinyl aromatic block copolymer is AB, ABA and / or (AB) n X, where X represents the residue of a coupling agent or initiator, and n is 2 or greater.

[0200] Particularly preferably, the vinyl aromatic block copolymer(s) have the structure ABA, optionally in admixture with a proportion of AB, where the former represents the diblock component.

[0201] Very particularly preferably, the vinyl aromatic block copolymer(s) are present as a mixture of polymers having the structure ABA and polymers having the structure AB.

[0202] Block A represents a block formed from vinyl aromatic monomers.

[0203] Preferably, block A is formed from a polymerization mixture comprising at least styrene and α-methylstyrene, preferably from a polymerization mixture comprising at least styrene. Very particularly preferably, block A is a block formed from styrene, and therefore a polystyrene block.

[0204] Block B represents the other block of the block copolymer. Preferably, block B is formed from a polymerization mixture comprising monomers of 1,3-diene and isobutylene, more preferably from a polymerization mixture comprising butadiene and / or isoprene. Very particularly preferably, block B is a block formed from butadiene, and therefore a polybutadiene block.

[0205] Particularly preferably, the vinyl aromatic block copolymer(s) are styrene block copolymer(s), also preferably styrene-butadiene block copolymers of the structure ABA, optionally including AB.

[0206] The problem on which the invention is based is solved particularly well using it.

[0207] In a particularly advantageous embodiment, the pressure-sensitive adhesive layer comprises as vinyl aromatic block copolymer a mixture of at least two styrene-butadiene block copolymers, where the first block copolymer has a diblock AB proportion of 50 to 85% and the second block copolymer has a diblock AB proportion of 5 to 35%.

[0208] The problem on which the invention is based is solved particularly well using it.

[0209] The diblock ratio is determined by GPC and can be precisely adjusted by selecting the appropriate preparation method, as known to those skilled in the art.

[0210] Preferably, the ABA polymer strands of the vinyl aromatic block copolymer(s) contained have a weight average molecular weight distribution Mw(GPC) of from 50,000 g / mol to 300,000 g / mol, particularly preferably from 80,000 to 180,000 g / mol.

[0211] As previously described, the adhesive layers C and C' can be identical or different from each other. For example, an adhesive layer, for example C, can be composed of an acrylate-based adhesive, while the other layer, in the same example C', is composed based on an adhesive based on vinyl aromatic block copolymer(s).

[0212] In a preferred embodiment of the invention, the adhesive layer C or C and / or C', in particular if it is based on a vinyl aromatic block copolymer as the main polymer, comprises at least one tackifying resin.

[0213] Thereby, the adhesive properties of the adhesive are increased and nevertheless the adhesive layer(s) C or C and / or C' can still be electrically conductive.

[0214] By "tackifying resin" is meant an oligomeric or polymeric resin that, according to the understanding of one skilled in the art, increases the adhesive properties (tack, inherent adhesion) of an adhesive layer when compared to an otherwise identical adhesive without the tackifying resin.

[0215] Preferably, the at least one tackifying resin has a weight-average molecular weight M of from 400 to 15,000 g / mol, particularly preferably from 400 to 5,000 g / mol, very particularly preferably from 500 to 2,000 g / mol. w has.

[0216] Preferably, said at least one tackifying resin is selected from the group consisting of non-hydrogenated, partially hydrogenated or fully hydrogenated resins based on rosin or rosin derivatives, hydrogenated polymers of dicyclopentadiene, non-hydrogenated, partially hydrogenated, selectively hydrogenated or fully hydrogenated hydrocarbon resins based on C-5, C-5 / C-9 or C-9 monomer mixtures, and polyterpene resins based on α-pinene and / or β-pinene and / or δ-limonene.

[0217] It will be apparent to one skilled in the art that such tackifying resins may be selected that are particularly compatible with the vinyl aromatic block copolymer(s).

[0218] The adhesive of the adhesive layer C or C and / or C' may further comprise further customary additives, such as softeners and fillers.

[0219] According to a preferred embodiment, the adhesive of the adhesive layer C or C and / or C' is also foamed. This further improves the impact resistance of the adhesive tape according to the invention and therefore of the bonded assembly. This ensures that no undesired premature delamination between the substrates occurs, especially when forces (e.g. due to a fall) act on the bonded assembly. Preferably, foaming of the adhesive of the adhesive layer C or C and / or C' is also brought about by means of the expansion of inflatable microballoons.

[0220] The adhesive layer C or C and / or C' does not need to contain an electrolyte or be electrically peelable, so all types of microballoons known to those skilled in the art can be used.

[0221] In a preferred embodiment of the invention, the adhesive of the adhesive layer C or C and / or C' is also foamed, the foaming being brought about by means of microballoons, which have a silicate or alumosilicate layer on their surface and are preferably mixed into the adhesive as expandable microballoons.

[0222] Preferably, the adhesive of the adhesive layer D is a pressure-sensitive adhesive, and therefore the adhesive layer D is preferably a pressure-sensitive adhesive layer D. Thereby, the adhesive tape can be simply glued on its side, since, in particular, no heat input is required in comparison with heat-activatable adhesive systems. Furthermore, the components of the electrolyte, such as, in particular, the ions of the ionic liquid, migrate more quickly in the pressure-sensitive adhesive due to the relatively low crosslinking density.

[0223] The adhesive component C or the adhesive of C and / or C' is according to a preferred embodiment not a pressure sensitive adhesive.

[0224] According to yet another preferred embodiment of the present invention, the adhesive of adhesive layer C or C and C' is a pressure sensitive adhesive, and therefore adhesive layer C or C and C' is a pressure sensitive adhesive layer.

[0225] In embodiments in which all outer adhesive layers are pressure sensitive adhesive layers, the adhesive tape of the present invention is a pressure sensitive adhesive tape.

[0226] In the present invention, a pressure-sensitive adhesive is, as it is commonly used, a substance that is persistently tacky and adhesive (especially at room temperature). It is a characteristic of a pressure-sensitive adhesive that it can be applied to a substrate by pressure and remains attached thereto, the pressure used and the duration of the application of this pressure are not specifically defined. In some cases, depending on the exact type of pressure-sensitive adhesive, the temperature and air humidity as well as the substrate, a short-term application of minimal pressure, not exceeding a momentary light touch, is sufficient to achieve the adhesive effect, in other cases a long application time of high pressure may be necessary.

[0227] Pressure-sensitive adhesives have characteristic viscoelastic properties that in particular provide a long-lasting tack and adhesion. Pressure-sensitive adhesives are characterized by the fact that, when mechanically deformed, they undergo both a viscous flow process and the development of elastic restoring forces. Both processes, in terms of their respective proportions, are in a specific ratio to one another, depending on the exact composition, structure and degree of crosslinking of the pressure-sensitive adhesive, on the rate and time of deformation, and on the temperature.

[0228] A proportionate viscous flow is necessary to achieve adhesion. Only the viscous component caused by the relatively large mobility of the macromolecules allows good wetting and good flow on the substrate to be bonded. A high proportion of viscous flow leads to strong pressure-sensitive adhesion (also called tack or surface adhesion) and therefore often also high adhesive strength. Highly crosslinked systems, crystalline or glass-like hardened polymers, lacking a flowable component, are generally not pressure-sensitive adhesive, or at least only slightly pressure-sensitive adhesive.

[0229] A proportional elastic restoring force is necessary to achieve cohesion, which is provided, for example, by very long-chain, strongly entangled and physically or chemically crosslinked polymers and allows the transmission of forces acting on the adhesive bond, such that the adhesive bond can withstand sustained loads acting on it, for example in the form of sustained shear loads, sufficiently and for a relatively long time.

[0230] To more accurately express and quantify the measures of the elastic and viscous parts and their ratio to one another, one can refer to the storage modulus (G') and the loss modulus (G"), values ​​which can be determined by dynamic mechanical analysis (DMA, according to DIN EN ISO 6721). G' is a measure for the elastic part of the material and G" is a measure for the viscous part of the material. Both values ​​depend on the deformation frequency and on the temperature.

[0231] These values ​​can be determined by means of a rheometer. The material to be examined is then subjected to a sinusoidally oscillating shear load, for example in a plate-plate configuration. In the case of shear-stress-controlled instruments, the deformation as a function of time and the time lag of this deformation relative to the introduction of the shear stress are measured. This time lag is called the phase angle δ.

[0232] The storage modulus G' is defined as follows: G' = (τ / γ) cos(δ) (τ = shear stress, γ = deformation, δ = phase angle = phase shift between the shear stress vector and the deformation vector).

[0233] The loss modulus G'' is defined as: G'' = (τ / γ)·sin(δ) (τ = shear stress, γ = deformation, δ = phase angle = phase shift between the shear stress vector and the deformation vector).

[0234] A material is generally considered to be pressure-sensitive adhesive, and is defined as pressure-sensitive adhesive within the meaning of this specification, if it is adhesive at room temperature, as defined herein at 23° C., and has a deformation frequency of 10 0 ~10 1 rad / sec range, G' is at least partially 10 3 ~10 7 Pa and G″ is also at least partially within this range. “Partial” means 10 0 rad / sec or more 10 1 Deformation frequency (abscissa) below rad / sec and 10 3 Pa or more 10 7The goal is to have at least one section of the G' curve within a window spanning the range of G' values ​​(ordinate) below Pa. Similarly for G".

[0235] Preferably, the pressure sensitive adhesive has a viscosity of 10 0 From 10 1 rad / sec, determined according to DIN EN ISO 6721, 3 From 10 7 It has a storage modulus G' and loss modulus G'' in the range up to 100 Pa.

[0236] To achieve viscoelastic properties, the monomers on which the polymers on which the pressure-sensitive adhesive is based, as well as any further components of the pressure-sensitive adhesive that may be present, are in particular selected so that the pressure-sensitive adhesive has a glass transition temperature (according to DIN 53765) below the use temperature, i.e. usually below room temperature (23°C). By appropriate cohesion control measures, such as crosslinking reactions (the formation of bridge-forming bonds between macromolecules), the temperature range in which the polymer composition exhibits pressure-sensitive adhesive properties can be expanded and / or shifted. The use range of the pressure-sensitive adhesive can therefore be optimized by adjusting between the flowability and cohesion of the adhesive.

[0237] Preferably, the pressure sensitive adhesive has a glass transition temperature, determined according to DIN 53765, of ≦23° C.

[0238] Hot melt adhesives, for example those based on polyamide, polyurethane or modified polyethylene, unlike pressure sensitive adhesives, have no adhesive properties at room temperature (23° C.), even in the hot melt adhesive composition.

[0239] A further subject of the invention is a method for the production of an adhesive tape according to the invention, which in a first preferred embodiment comprises at least the following process steps: A) providing a first adhesive layer D, wherein the adhesive layer D comprises at least one electrolyte and expandable microballoons, wherein the expandable microballoons have a layer made of silicate or alumosilicate on their surface; and B) foaming the first adhesive layer D, wherein the foaming occurs by expansion of the expandable microballoons.

[0240] According to a preferred embodiment of the present invention, the method comprises at least the following process steps: A) providing a first adhesive layer D, wherein the adhesive layer D comprises at least one electrolyte and expandable microballoons, wherein the expandable microballoons have a layer made of silicate or alumosilicate on their surface; and B) providing a second adhesive layer C; and C) providing an electrically conductive carrier layer T; and D) laminating the layers D, T and C provided above, wherein the layers are in contact with each other, with the electrically conductive layer T being disposed between the layers D and C, such that a layer assembly DTC is obtained as a double-sided adhesive tape; and E) foaming the first adhesive layer D, wherein the foaming occurs by expansion of the expandable microballoons.

[0241] Process step A) of all embodiments particularly and preferably comprises the following substeps: A1) providing an adhesive; and A2) providing at least one electrolyte; and A3) providing an expandable microballoon, wherein the expandable microballoon has a layer of silicate or alumosilicate on its surface; and A4) adding the microballoons to the adhesive; and A5) adding the electrolyte to the adhesive.

[0242] The provision of the first adhesive according to step A1) is in particular carried out by providing at least one polymer, which may optionally comprise further components. With respect to the adhesive, electrolyte and expandable microballoons, all statements made above regarding the adhesive layer D apply. The list of steps A2) to A5) does not necessarily represent a chronological order. For example, an electrolyte, such as in particular at least one ionic liquid, can be added to the adhesive first, and only afterwards the expandable microballoons can be added.

[0243] According to yet another embodiment of the invention, the method for the production of an adhesive tape according to the invention comprises the following process steps: X1) providing an adhesive; and X2) providing at least one electrolyte; and X3) providing a pre-expanded microballoon, wherein the pre-expanded microballoon has a layer of silicate or alumosilicate on its surface; and X3) adding the microballoons to the adhesive; and X4) adding said electrolyte to said adhesive.

[0244] All statements made above regarding the adhesive layer D apply to the adhesive, electrolyte and pre-expanded microballoons. The list of steps X2) to X5) does not necessarily represent a chronological order. For example, it is also possible to first add an electrolyte, such as at least one ionic liquid in particular, to the adhesive and only afterwards add the pre-expanded microballoons.

[0245] The adhesive is applied in the form of a layer using known methods, in particular by spreading, and optionally one or more drying steps can be carried out.

[0246] The provision of the second adhesive layer C according to step B) is in particular carried out by providing at least one further adhesive, which is brought into the form of a layer using known methods, in particular by spreading. Furthermore, one or more drying steps can optionally be carried out.

[0247] The lamination according to step D) is carried out in a manner known to the person skilled in the art, the layers being laminated in such a way that a layer assembly DTC is obtained as a double-sided adhesive tape, T being arranged between D and C.

[0248] The provision of the carrier layer T according to step C) can be carried out in various ways, as already mentioned above.

[0249] For example, it is conceivable to arrange a) a metal film, in particular an aluminum film, and / or b) an electrically conductive net and / or d) at least one metal grid and / or e) a metal-vapor-deposited PET film between layer D and layer C.

[0250] Additionally, c) metal particles can be vapor-deposited directly onto the surface of adhesive layer D or C.

[0251] The listing of process steps A) through C) does not necessarily represent a chronological order.

[0252] The foaming of the adhesive layer D according to process step E) can take place either temporally before the lamination in step D) or after it.

[0253] In a preferred embodiment, the adhesive of adhesive layer C is likewise supplemented with expandable microballoons during its provision according to step B). Expansion is in particular and preferably achieved by heating the layer to be foamed or the layers to be foamed to the appropriate temperature required for the expansion of the microballoons used.

[0254] In particular, if layer C also contains expandable microballoons, it is preferred that the expansion according to step E) is carried out temporally after the lamination according to step D), since this allows layers D and C to be heated and thereby foamed simultaneously, saving time and energy.

[0255] The method of making the adhesive tape in the five-layer assembly embodiment involves similar steps, except that layers T' and C' are additionally provided and similarly laminated into the assembly.

[0256] The adhesive tapes according to the invention are in particular double-sided adhesive tapes, where, depending on the embodiment, both sides of the adhesive layer D (transfer adhesive tape) or one side of the first adhesive layer D and one side of the second adhesive layer C (three-layer assembly DTC) or one side each of the adhesive layers C and C' (five-layer assembly CTD-T'-C') are each available for bonding to the substrate.

[0257] Advantageously, the outer free surface of the adhesive layer of the adhesive tape according to the invention can be equipped with an anti-adhesive material, such as a release paper or release film (also called liner). The liner can also be a material that is anti-adhesively coated on at least one side, but especially on both sides, for example a material that is silicone-coated on both sides. The liner or more generally the temporary carrier is not part of the adhesive tape, but merely an auxiliary means for its production, storage and / or secondary processing by die cutting. Moreover, unlike a permanent carrier, the liner is not firmly bonded to the adhesive layer, but rather functions as a temporary carrier, i.e. a carrier that can be peeled off from the adhesive layer. In this application, the "permanent carrier" is also synonymously referred to simply as "carrier".

[0258] The thickness (in the z-direction) of the individual adhesive layer(s) is preferably from 15 to 150 μm, particularly preferably from 20 to 100 μm, very particularly preferably from 25 to 70 μm.

[0259] In the embodiment of the three-layer assembly DTC and the five-layer assembly CTD-T'-C', the adhesive layers D and C, or D and C and D and C', according to a preferred embodiment, have different layer thicknesses, with the thickness of the adhesive layer D being, for example, less than the thickness of the adhesive layers C or C and C'. According to yet another embodiment, the layers D and C or D, C and C' have the same layer thickness. If the layer D is too thick, this may become uneconomically costly due to the electrolyte contained.

[0260] Preferred embodiments of the present invention will now be explained in more detail with reference to the accompanying drawings. [Brief description of the drawings]

[0261] [Figure 1] FIG. 1 shows a simplified schematic cross-section of a double-sided adhesive tape according to the invention in a preferred embodiment. [Diagram 2] FIG. 2 shows a simplified schematic cross-section of a double-sided adhesive tape according to the invention in a preferred embodiment. [Diagram 3] FIG. 3 shows a simplified schematic cross-section of a double-sided adhesive tape according to the invention in a preferred embodiment. [Figure 4] FIG. 4 shows a simplified schematic cross-section of a bonded assembly according to the present invention in a preferred embodiment. [Diagram 5] FIG. 5 shows a simplified schematic cross-section of a bonded assembly according to the invention with a voltage applied thereto in a preferred embodiment. [Figure 6] FIG. 6 shows a simplified schematic cross-section of an assembly bonded in accordance with the present invention after a voltage has been applied, resulting in bond separation. [Figure 7] FIG. 7 shows a simplified schematic cross-section of a bonded assembly according to the present invention in a preferred embodiment. [Figure 8] FIG. 8 shows a simplified schematic cross-section of a bonded assembly according to the present invention in a preferred embodiment.

[0262] As can be seen in figure 1, the adhesive layer D1 is bonded over its surface to the carrier layer T2. On the face of the carrier layer T opposite to the layer D an adhesive layer 3C is arranged.

[0263] As can also be seen from FIG. 1, the layer assembly is a double-sided adhesive tape, in which one side of an adhesive layer D and one side of a second adhesive layer C, respectively, are available for bonding.

[0264] Figure 2 shows a preferred embodiment of the invention, in which the electrically conductive carrier layer T2 protrudes laterally from the adhesive layer D1 and from the second adhesive layer C3 in at least one extension direction of the layer plane, so that the electrically conductive carrier layer T2 has at least one protruding part with a free surface 2a.

[0265] Fig. 3 shows yet another preferred embodiment of the invention. In this case, the electrically conductive carrier layer T2 laterally protrudes from the adhesive layer D1 in at least one extension direction of the layer plane, so that the electrically conductive carrier layer T2 has an overhang with one free surface 2a. In Fig. 3, the adhesive layer C3 is formed in such a way that it likewise has an overhang relative to the layer D1. The carrier layer T2 is in particular a PET film coated on one side with aluminum, where the aluminum-coated side is bonded to the layer D1.

[0266] In Fig. 4, a schematic diagram of a bonded assembly according to the invention is shown according to a preferred embodiment. As can be seen from Fig. 4, the adhesive tape is arranged on one side of a first substrate A4, which is electrically conductive, via an adhesive layer D1. Furthermore, the adhesive tape is arranged on one side of a second substrate B5 via a second adhesive layer C3. Fig. 4 also shows, by way of example, that the electrically conductive carrier layer T2 laterally protrudes from the adhesive layer D1 in at least one extension direction of the layer plane, so that the electrically conductive carrier layer T has a protruding part with one free surface 2a.

[0267] In this case, a voltage can be applied via this free surface 2a, as shown in the schematic diagram of FIG.

[0268] By applying a voltage, a migration of the electrolyte, in particular a separation of the anions and cations of the ionic liquid, occurs in the adhesive layer D1, which greatly weakens the adhesion of the adhesive layer D1 to the substrate A4 and causes these layers to move away from each other, as can be seen in the schematic diagram of FIG.

[0269] In Fig. 7, a further schematic diagram of a bonded assembly according to the invention in a preferred embodiment is shown. As can be seen from Fig. 7, the adhesive tape is arranged on one side of a first substrate A4 via an adhesive layer C3. Furthermore, the adhesive tape is arranged on one side of a second substrate B5 via a third adhesive layer C'7. Between the layers C3 and C'7 there is an electrically peelable adhesive layer D1 and two electrically conductive carrier layers T2 and T'6, with the layer D1 being arranged between these carrier layers. Fig. 7 also shows by way of example that the electrically conductive carrier layer T2 and the electrically conductive carrier layer T'6 each laterally extend from the adhesive layer D1 in at least one extension direction of the layer plane, so that the electrically conductive carrier layer T has a protruding portion with one free surface 2a and the electrically conductive carrier layer T' has a protruding portion with a free surface 6a.

[0270] In Fig. 8, yet another schematic diagram of a bonded assembly according to the invention in a preferred embodiment is shown, which is similar to Fig. 7. However, in contrast to Fig. 7, the protrusions of the electrically conductive carrier layer T2 and the electrically conductive carrier layer T'6 are oriented in different directions, so that the resulting free faces (2a or 6a) of these layers are spatially separated.

[0271] Here, a voltage can be applied via these free faces 2a and 6a, similar to Figure 5. Unlike the embodiment of Figure 5, a voltage can be applied to faces 2a and 6a, so that neither of the substrates A and B need be electrically conductive.

[0272] By applying a voltage, a migration of the electrolyte, in particular a separation of the anions and cations of the ionic liquid, occurs in the adhesive layer D1. This significantly weakens the adhesion of the adhesive layer D1 to the carrier layers T2 and / or T'6, and these layers separate from each other. In particular, the peeling occurs in the layer to which the negative electrode is applied.

[0273] The application of voltages is simplified in the case of spatially separated surfaces 2a and 6a according to FIG.

[0274] The representations of Figures 1 to 8 are, as mentioned above, schematic. In particular, the layer thicknesses of the individual layers D, T and C can differ from one another. Furthermore, the substrates A and B are also only shown diagrammatically as further layers. They can of course have any other three-dimensional shape. EXAMPLES

[0275] Below some examples are given to further illustrate the invention.

[0276] Test Method All measurements are carried out at 23° C. and 50% relative humidity (unless otherwise stated). Mechanical and adhesion technical data were determined as follows: Molecular weight M n , M w The number average molecular weight M n or weight average molecular weight M w The data relate to the determination by gel permeation chromatography (GPC). The determination is carried out on 100 μl of a clarified filtered sample (sample concentration 4 g / l). As an eluent, tetrahydrofuran containing 0.1% by volume of trifluoroacetic acid is used. The measurement is carried out at 25°C. As a precolumn, a column type PSS-SDV, 5 μm, 10 3 Å, 8.0mm*50mm (in the following description, the order of type, grain size, porosity, inner diameter*length; 1Å=10 -10 For separation, we used type PSS-SDV, 5μm, 10 3 A and 105 Å and 10 6 A combination of columns of 1.0 Å is used (Polymer Standards Service columns; detection with a Shodex RI71 differential refractometer). The flow rate is 1.0 ml per minute. Calibration is performed against PMMA standards (polymethylmethacrylate calibration) in the case of polar molecules, such as the starting polyurethanes, and against PS standards (polystyrene calibration) in other cases.

[0277] Adhesive resin softening temperature The tackifying resin softening temperature is determined according to a suitable methodology known as the Ring and Ball method and standardized according to ASTM E28.

[0278] Thickness The thickness of the adhesive layer can be determined by subtracting the thickness (known or determined separately) of a cross section of the same dimensions of the liner used from the determined thickness of a section of such adhesive layer applied on the liner defined by its length and width. The thickness of the adhesive layer can be determined with a precision of error of less than 1 μm using a conventional thickness measuring device (sensor test device). If thickness variations are identified, the average value of measurements at at least three representative locations is taken, i.e., measurements are not taken in particular at folds, creases, ridges and similar areas.

[0279] The thickness of the adhesive tape (adhesive strip) or carrier, as well as the thickness of the adhesive layer, can likewise be determined with a precision of less than 1 μm by means of customary thickness measuring devices (sensor test devices). If thickness variations are identified, the average value of measurements at at least three representative locations is taken, i.e. measurements are not taken in particular at folds, creases, ridges and similar areas.

[0280] Adhesive strength 180° Adhesion Test: To test the adhesion of the electrically peelable layer D to steel: A 20 mm wide strip of the adhesive tape according to the invention is applied with the adhesive side of layer C to a 23 μm thick PET film with a slight adhesive overflow. This assembly is applied with the electrically peelable side (layer D) to a steel plate that has been previously cleaned twice with acetone and once with isopropanol. The pressure-sensitive adhesive strip is pressed twice onto the substrate with a pressure equivalent to a weight of 2 kg. The adhesive tape is then immediately peeled off from the substrate at a speed of 300 mm / min and an angle of 180°. All measurements are carried out at room temperature.

[0281] The results are expressed in N / cm and are averaged from three measurements.

[0282] To test the adhesion of layer C to steel, measurements are carried out analogously, with a 20 mm wide strip of the adhesive tape of the invention first applied with the electrically peelable adhesive side (layer D) to a 20 μm thick PET film with a slight adhesive overflow, then this assembly is applied with the other side (layer C) to a steel plate, and so on.

[0283] Example 1 according to the present invention The adhesive layer D is prepared as follows: The base polymer based on acrylates is prepared as follows: A conventional reactor for radical polymerization is charged with 48 kg of 2-ethylhexyl acrylate, 48 kg of n-butyl acrylate, 4 kg of acrylic acid and 66 kg of mineral spirits / acetone (70 / 30). After 45 minutes of passing nitrogen gas through with stirring, the reactor is heated to 58° C. and 50 g of AIBN are added. The external heating bath is then warmed to 75° C. and the reaction is carried out constantly at this external temperature. After 1 hour, 50 g of AIBN are added again and after 4 hours it is diluted with 20 g of a mineral spirits / acetone mixture. After 5.5 hours and 7 hours, respectively, it is reinitiated with 150 g of bis-(4-tert-butylcyclohexyl) peroxydicarbonate. After 22 hours of reaction time, the polymerization is interrupted and cooled to room temperature. The resulting polyacrylate has an average molecular weight of Mw=386,000 g / mol with a polydispersity PD(Mw / Mn)=3.6.

[0284] Based on the amount of the polymer (excluding the solvent), 5.5% by weight of 1-ethyl-3-methylimidazolium-bis(trifluoromethylsulfonyl)imide (EMIM-TFSI) as an ionic liquid and 4% by weight of polyethylene glycol 400 (Sigma Aldrich) are mixed.

[0285] In addition, 0.1% by weight of Erysis GA240 as a crosslinker, based on the amount of acrylate polymer excluding the solvent, is added.

[0286] Additionally, add 1 wt % Matsumoto FN100SSD as microballoons based on the total amount of adhesive in Layer D, which have a silicate coating and a size of about 20 μm after expansion.

[0287] The resulting mixture is then applied using a coating bar onto a PET liner equipped with release silicone, such that after drying at 110° C. a layer thickness of 45 μm results.

[0288] Adhesive layer C is prepared as follows: The acrylate-based polymer is prepared as described above for adhesive layer D. 0.1% by weight, based on the amount of acrylate polymer excluding the solvent, of Erysis GA240 as a crosslinker is added.

[0289] Additionally, Matsumoto FN100SSD as microballoons is added at 1% by weight based on the total amount of adhesive.

[0290] An aluminium-coated PET film with a layer thickness of 25 μm is provided as an electrically conductive carrier layer T.

[0291] By "aluminum-coated PET film" is understood a PET film on whose surface aluminum is vapor-deposited. The resulting layer thickness of the aluminum layer in the z-direction is approximately 40 nm.

[0292] A second adhesive layer C is then applied to the non-metallized side of the PET film using a coating bar, the resulting layer thickness of this adhesive layer C being again 45 μm, and the reverse side is covered with a liner based on a silicone-coated PET film.

[0293] An electrically releasable adhesive layer D is then laminated to the aluminum side of the assembly consisting of carrier layer T and adhesive layer C to obtain an adhesive tape with the layer sequence DTC.

[0294] In this case, the adhesive layer C together with the electrically conductive carrier layer T protrudes in at least one direction, optimally by about 1 cm, beyond the adhesive layer D. The total thickness of this adhesive tape is 115 μm.

[0295] The adhesive tape, still with the silicone-coated liner on both sides, is then heated at 180° C. for 1 minute, thereby expanding the microballoons and thus foaming the adhesive layers C and D. The total thickness of the adhesive tape, excluding the silicone-coated liner, is now 145 μm.

[0296] The adhesion of this joint to steel is 4.0 N / cm on the electrically peelable side, ie the free side of adhesive layer D, and 6.5 N / cm on adhesive layer C.

[0297] For the peelability test, an adhesive tape is applied as follows: the peelable side of the adhesive tape is applied to a conductive surface, in this case a steel plate as representative of the conductive substrate A (see also the method description for "adhesion"). On the other side, a 23 μm thick PET film is applied. After application, a voltage is applied, specifically the cathode to the steel plate and the anode to the protruding part of the carrier film T.

[0298] At this time, the voltage is 12 V and is applied for 1 minute.

[0299] The sample is then immediately placed in the measuring device and the adhesion of the adhesive layer D of this adhesive tape to the steel plate is measured again, where the adhesion is only 0.5 N / cm.

[0300] The adhesive force could be significantly weakened by applying a voltage.

[0301] Example 2 according to the present invention In a second example, the electrically peelable adhesive of adhesive layer D is varied by changing the ratio of acrylates used.

[0302] 30 kg of 2-ethylhexyl acrylate, 64 kg of n-butyl acrylate and 6 kg of acrylic acid are used.

[0303] As the ionic liquid, 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide (EMIM-FSI) is added in an amount of 5% by weight based on 100% by weight of the polymer, excluding the solvent.

[0304] Additionally, 4% by weight of polypropylene glycol 600 (Sigma Aldrich) is added.

[0305] In addition, 0.1% by weight of Erysis GA240 as a crosslinker, based on the amount of acrylate polymer excluding the solvent, is added.

[0306] Again, 1 wt% Matsumoto FN100SSD as microballoons is added.

[0307] The adhesive is applied in a layer thickness of 45 μm onto a silicone-coated liner.

[0308] The adhesive used for adhesive layer C is an adhesive based on a styrene block copolymer, in particular an adhesive consisting of 33% Kraton D1118, 17% Kraton D1102 and 50% Piccolyte A115.

[0309] This adhesive also contains 1% by weight of Matsumoto FN100SSD as microballoons.

[0310] This adhesive is applied, analogously to Example 1, to an aluminum-coated PET film having a thickness of 25 μm as carrier layer T, resulting in a layer thickness of 45 μm. Again, a silicone-coated PET film as a liner is laminated to the free side of the adhesive.

[0311] Then, again in this case, an electrically peelable layer D is laminated onto the still free metal-coated side of the carrier layer T, the carrier layer T together with the adhesive layer C protruding from the peelable adhesive layer D in at least one direction.

[0312] Again, the resulting adhesive tape is heated at 180° C. for 1 minute to expand the microballoons in adhesive layers D and C. The total thickness of the adhesive tape, excluding both liners, is now 145 μm.

[0313] The resulting adhesive tape has an adhesion to steel of 3.8 N / cm on the electrically peelable side, i.e. the free side of adhesive layer D, and 8.4 N / cm on the other side, i.e. the free side of adhesive layer C.

[0314] The application for the removability test is carried out as described above. After applying a voltage of 12 V for 1 minute, the adhesion of the releasable side of the adhesive tape, i.e. adhesive layer D, to the steel is measured: the adhesion drops to 0.3 N / cm.

[0315] Comparative Example 1 For the electrically peelable layer D, the same adhesive as in Example 1 according to the invention is used, only the microballoons are replaced by microballoons Expancel 920DU20 from Nouryon with a calcium carbonate coating.

[0316] Layer T and adhesive layer C remain unchanged from Example 1 according to the invention.

[0317] The individual layers are laminated together as described above and then heated to 160° C. for 1 min. It can be seen that uniform expansion of the microballoons is not possible and there is significantly less expansion. Under the microscope it can be seen that the microballoons are already largely destroyed. It seems that the microballoons with calcium carbonate coating are not compatible with the ionic liquid.

[0318] Surprisingly, therefore, only with microballoons having a silicate or alumosilicate coating can an adhesive layer D be successfully produced which is electro-releaseable, therefore also contains an electrolyte, and is simultaneously foamed.

[0319] As the tests for adhesion and removability show in Examples 1 and 2 according to the invention, the adhesion of the adhesive layer D on a substrate such as steel is strong before the application of a voltage, and only by applying a voltage does it weaken to a value low enough that the substrates can be peeled away from each other quickly and without using a lot of force.

[0320] Substances used: Kraton D1102: Styrene-butadiene-styrene block copolymer containing a mixture of ABA and AB structures, styrene content 30%, diblock content (AB) 15%, Kraton Kraton D1118: Styrene-butadiene-styrene block copolymer containing a mixture of ABA and AB structures, styrene content 31%, diblock content (AB) 78%, Kraton Adhesive resin Piccolyte A 115: terpene resin made from alpha-pinene, softening point 115°C, manufactured by DRT Polyethylene glycol 400, Sigma Aldrich Polypropylene glycol 600, Sigma Aldrich Erysis® 240: Tetraglycidyl-meta-xylylenediamine, Huntsman ·Micro balloon Matsumoto FN100SSD, manufactured by Matsumoto Honsha Microballoons Expancel 920DU20, manufactured by Nouryon [Explanation of symbols]

[0321] 1 Adhesive layer D 2 Electrically conductive carrier layer T 2a Free surface of electrically conductive carrier layer T 3 Second adhesive layer C 4. First substrate A 5 Second substrate B 6. Second electrically conductive carrier layer T' 6a Free surface of electrically conductive carrier layer T' 7 Third adhesive layer C'

Claims

1. An adhesive tape comprising at least the following layers: an adhesive layer D, which comprises at least one electrolyte and is foamed, whereby the foaming is brought about by means of microballoons and whereby said microballoons have on their surface a layer made of silicate or alumosilicate.

2. 2. Adhesive tape according to claim 1, characterized in that the electrolyte of the adhesive layer D is selected from the group consisting of ionic liquids and metal salts, ionic liquids being particularly preferred.

3. The anion of the ionic liquid is Br － , AlCl ４ － , Al ２ C ７ － , NO ３ － , B.F. ４ － , P.F. ６ － , C.H. ３ COO － , C.F. ３ COO － , C.F. ３ CO ３ － , C.F. ３ SO ３ － , (CF ３ SO ２ ) ２ N － , (CF ３ SO ２ ) ３ C － , AsF ６ － , SbF ６ － , C.F. ３ (CF ２ ) ３ SO ３ － , (CF ３ CF ２ SO ２ ) ２ N － , C.F. ３ CF ２ CF ２ COO － , (FSO ２ ) ２ N － and particularly preferably selected from the group consisting of (CF ３ SO ２ ) ２ N － and (FSO ２ ) ２ N － 3. The adhesive tape according to claim 2, wherein the adhesive tape is selected from the group consisting of:

4. 4. Adhesive tape according to claim 2 or 3, characterized in that the cation of the ionic liquid is selected from the group consisting of imidazolium-based cations, pyridinium-based cations, pyrrolidine-based cations and ammonium-based cations, particularly preferably from the group consisting of imidazolium-based cations, and particularly preferably from the group consisting of 1-ethyl-3-methylimidazolium and 1-butyl-3-methylimidazolium, very particularly preferably 1-ethyl-3-methylimidazolium.

5. 5. Adhesive tape according to claim 1, characterized in that the electrolyte of the adhesive layer D is selected from the group consisting of the ionic liquids 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (EMIM-TFSI) and 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide (EMIM-FSI).

6. 6. Adhesive tape according to claim 1, characterized in that the first adhesive layer D is based on poly(meth)acrylate.

7. 7. Adhesive tape according to claim 1 , characterized in that the first adhesive layer D comprises from 2 to 10 wt.-%, preferably from 4 to 6 wt.-%, of an electrolyte, preferably an ionic liquid, based on 100 wt.-% of the polymer present.

8. 8. The adhesive tape according to claim 1, which is a transfer adhesive tape and comprises an adhesive layer D.

9. The adhesive tape according to any one of claims 1 to 7, additionally comprising at least the following layers: a second adhesive layer C; and At least one electrically conductive carrier layer T, arranged between layers D and C.

10. The adhesive tape according to any one of claims 1 to 7, additionally comprising at least the following layers: a second adhesive layer C; and at least one first electrically conductive carrier layer T, arranged between layer D and layer C; and at least one second electrically conductive carrier layer T′ disposed on the surface of the adhesive layer D opposite to the first electrically conductive carrier layer T; and A third adhesive layer C' disposed on the surface of the second carrier layer T' opposite to the first adhesive layer D.

11. 11. The adhesive tape according to claim 9 or 10, characterized in that the electrically conductive carrier layer T or the electrically conductive first carrier layer T and the electrically conductive second carrier layer T' comprise at least one metal, which is selected from the group consisting of copper, nickel, zinc, tin, silver, gold, aluminum, iron, chromium and alloys of said metals, and that the electrically conductive first carrier layer T and the electrically conductive second carrier layer T' are, independently of one another, the same or different from one another.

12. 12. The adhesive tape according to claim 11, characterized in that the electrically conductive carrier layer T or the electrically conductive first carrier layer T and the electrically conductive second carrier layer T' comprise a) at least one metal film, preferably an aluminum film, and / or b) at least one electrically conductive textile comprising at least one metal, preferably at least one metal selected from the group consisting of copper and nickel, and / or c) one or more layers of at least one vapor-deposited metal, preferably at least one vapor-deposited metal selected from the group consisting of copper and aluminum, and / or d) at least one metal grid, and / or e) a metal vapor-deposited film, and the electrically conductive first carrier layer T and the electrically conductive second carrier layer T' are, independently of one another, the same or different from one another.

13. A bonded assembly comprising at least the following layers: a first substrate A; and A second substrate B; and An adhesive tape according to any one of claims 1 to 12, which is disposed between a substrate A and a substrate B and bonds the substrates A and B to each other.

14. 14. The method of electrical delamination of a bonded body according to claim 13, comprising at least the following process steps: i.) Applying a voltage to two different points of the junction, the voltage being preferably between 2 and 20 V, particularly preferably between 3 and 15 V.

15. Use of the adhesive tape according to any one of claims 1 to 12 for bonding components in electronic devices, automobiles, medical devices and dental devices.

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