Adhesive tape, bonded joint, and method for electrically releasing a bonded joint

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 electrodetaching 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 either not removable or cannot be removed without damaging the substrate. Recently, environmental legislation and end-customer awareness regarding sustainability, as well as increasing cost pressures in manufacturing, have led to an increased interest in "on-demand desorption" capabilities. The usage scenarios for desorption processes can be categorized into rework, repair, recycling, and processing 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 before re-adhesion, whereas the latter avoids such cleaning.

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

[0005] Therefore, currently, cohesively breaking adhesive bonds are mainly used in the rework or repair of electronic devices, particularly smartphones and tablet computers, and 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 the substrate surface contaminated with adhesive residues in preparation for re-adhesion.

[0006] In addition to thermal separation methods, electrical separation methods have also been discussed. For example, EP3363873B1 (Patent Document 1) discloses such an electrical separation method or a corresponding adhesive tape that allows electrical separation of substrates bonded to each other. It is intended to enable separation of rigid substrates in particular. For this purpose, the adhesive tape proposed in EP3363873B1 (Patent Document 1) has a centrally located electrically conductive layer surrounded by two adhesive layers, one of which contains an electrolyte, thereby allowing electrical separation 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 adhered parts must not come off 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 adhesive's properties, especially its adhesive strength. Foaming itself also results in a different property profile than that of an unfoamed adhesive. This is particularly related to density, strength, and the mobility of relatively small molecules in the adhesive, with the latter aspect especially affecting the electro-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 object of providing an adhesive tape which can be peeled off again from at least one substrate without leaving any residue and which has good impact resistance (impact toughness), while at the same time the adhesive strength of the adhesive tape to the substrate to be bonded should not be negatively affected before 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, the foaming being effected by means of microballoons, said microballoons having a layer made of silicate or alumosilicate on their surface;

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

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

[0017] Therefore, by using the present invention, an adhesive tape is successfully provided which can be easily and quickly re-detached and therefore contributes to sustainability, and on the other hand, the article comprising it has a longer lifespan even if it is 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 also 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 form, can be produced in the form of a roll, i.e. wound on itself in the form of an Archimedes spiral, or can be produced as an adhesive strip, for example, obtained in the form of a die cut.

[0020] The adhesive tape of the invention is present in particular in the form of a web, which is understood to mean 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, in particular, exactly constant along its entire length.

[0021] The general expression "adhesive tape", also called synonymously as "adhesive strip", in the sense of the present invention encompasses all flat formations, such as two-dimensionally extended films or film segments, tapes with 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 determined by the length and width.

[0023] This statement also applies in some preferred embodiments to the carrier layer(s) that 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 the adhesive tape, to the bonded assembly according to the invention, as well as to the method for electrically releasing the assembly, and to the use of the adhesive tape according to the invention.

[0026] In addition, all features that 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 different preferred aspects, 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 preferred levels are also included.

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

[0028] Here, "electrolytes" are understood to mean compounds that "are dissociated into ions in the solid, liquid or dissolved state and move in a direction under the influence of an electric field", as described in the Wikipedia entry for "Elektrolyt" on January 4, 2023 or accordingly in Carl H. Hamann, Wolf Vielstich: Elektrochemie I: Elektrolytische Leitfaehigkeit, Potentiale, Phasengrenzen. 2. Auflage. VCH Verlagsgesellschaft mbH, Oldenburg / Bonn 1985, ISBN 3-527-21100-4, 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 use of one or more ionic liquids as electrolytes allows for easy re-detachment of the adhesive tape without adversely affecting the adhesive properties of the adhesive tape, since the ionic liquids are distributed well and uniformly in the polymer matrix of the adhesive, and this re-detachment occurs 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 scope of the present invention, are salts that are liquid at room temperature, i.e. 23° C. Accordingly, ionic liquids comprise anions and cations.

[0033] Therefore, ionic liquids are particularly well suited as electrolytes in the separation process or method according to the invention for electrical delamination. When a voltage is applied, anions migrate to the anode side and cations to the cathode side. This reduces the adhesive strength of the adhesive layer containing the ionic liquid, in this case layer D, to at least one of the adjacent layers, thereby achieving 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 two or more types of anions and / or two or more types of cations. 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 - , AlCl4 - , Al2Cl7 - , NO3 - , BF4 - , PF6 - , CH3COO - , CF3COO - , CF3CO3 - , CF3SO3 - , (CF3SO2)2N - , (CF3SO2)3C - , AsF6 - , SbF6 - , CF3(CF2)3SO3 - (CF3CF2SO2)2N - , CF3CF2CF2COO - , (FSO2)2N -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 (CF3SO2)2N - and (FSO2)2N - These anions are particularly well suited because they achieve the best electro-detachability. In particular, with these anions, (re)detachment is achieved particularly quickly and without leaving any residue.

[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 adhesive, such as (meth)acrylates, and can diffuse quickly and thoroughly 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)detachment is particularly successful and fast, and no residue is left behind.

[0041] Very particularly preferably, the cation is selected from the group consisting of 1-ethyl-3-methylimidazolium and 1-butyl-3-methylimidazolium.Once again 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 thoroughly into the matrix, thus enabling a relatively fast separation process and, at the same time, leaving no residue.

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

[0046] Particularly preferably, 100% by weight of the polymer contained in the adhesive layer D is 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 to mean, in particular, 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 at least 50% by weight of acrylic acid, methacrylic acid, acrylic acid esters and / or methacrylic acid esters, wherein the acrylic acid esters and / or methacrylic acid esters are present at least proportionally, preferably in an amount 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 a carboxylic acid group, a sulfonic acid group, a phosphonic acid group, a hydroxy group, an acid anhydride group, an epoxide group and an amino group.

[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 contains proportionately polymerized acrylic acid and / or methacrylic acid, whereby the poly(meth)acrylate, due to its carboxylic acid groups, is reactive with epoxide groups, and can therefore advantageously be 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 of the following formula (1): (1) CH2=C(R I )(COOR II ) [In the formula, R I is H or CH3, 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)acrylate is based on a monomer composition comprising 93 to 99% by weight of monomers from group a) and 1 to 7% by weight of monomers from group b).

[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 and residue-free peelability.

[0056] The monomers of component a) are generally softening, rather non-polar monomers. Particularly preferred are R IIis 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 polymerized particularly well, and the glass transition temperature of the produced poly(meth)acrylates can be adjusted particularly well, thereby again achieving optimized properties in terms of flowability and adhesion, which are also adapted in each case to the substrate or component to be bonded.

[0059] In this case, 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 of 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 methyl 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, dimethylaminopropyl 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 produced 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 adhesive strength of the adhesive layer D. The adhesive tape according to the invention therefore has a particularly high adhesive strength, especially when the adhesive tape is also adhered with at least one side of the adhesive layer D.

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

[0070] Preferably, the poly(meth)acrylates are prepared in a solvent, particularly preferably 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, each 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 manufactured by DuPont) TM )

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

[0073] Preferred solvents for preparing 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 acetic acid ethyl ester, as well as mixtures of the above-mentioned solvents. Particularly preferred solvents are mixtures containing isopropanol in an amount of from 2 to 15% by weight, especially from 3 to 10% by weight, based in each case 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 without the presence of crosslinker substances and accelerator substances.However, one of these compound classes can also be added to the polymer before concentration, that is, in this case, concentration is carried out in the presence of this (these) substance.

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

[0076] The weight-average molecular weight (weight average of the molecular weight distribution) of the one or more poly(meth)acrylates is preferably in the range of 20,000 to 2,000,000 g / mol, particularly preferably in the range of 100,000 to 1,500,000 g / mol, and very particularly preferably in the range of 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] By having such Mw of the poly(meth)acrylate(s) (including preferred embodiments at all levels), sufficient cohesive strength of the adhesive is achieved, with simultaneous good flow and good adhesion, wherein the adhesive is optimized to a greater extent in the preferred embodiments at higher levels with respect to the property profile of said properties.

[0078] Mw determination is performed by GPC as described in Test Methods.

[0079] The poly(meth)acrylates preferably have a K value, measured in toluene (1% strength by weight solution, 21° C.), of between 30 and 90, particularly preferably between 40 and 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 this method is based on determining the relative solution viscosity using a capillary viscometer. For this purpose, the test substance is dissolved in toluene by shaking for 30 minutes, thus obtaining a 1% solution. The efflux time is measured in a Vogel-Ossag viscometer at 25°C, and the relative viscosity of the sample solution compared to the viscosity of the pure solvent is determined on the basis of this. Based on the Fikentscher method [PE Hinkamp, ​​Polymer, 1967, 8, 381 (Non-Patent Document 2)], the K value can be read 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. Adhesives based thereon have particularly good shear strength after crosslinking, despite their relatively low molecular weight. In addition, a relatively low polydispersity allows for easier melt processing, since the flow viscosity is lower than that of more widely distributed poly(meth)acrylates, given similar application properties. Narrowly distributed poly(meth)acrylates can be advantageously prepared by anionic or controlled radical polymerization, with controlled radical polymerization being particularly suitable. Corresponding poly(meth)acrylates can also be prepared via N-oxyl. Atom transfer radical polymerization (ATRP) can also be advantageously used to synthesize narrowly distributed poly(meth)acrylates, preferably using monofunctional or difunctional secondary or tertiary halides as initiators and 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 with 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 low temperature flow that is not too high. This has a favorable effect on the cohesion of the adhesive as well as on the storage and processability of the adhesive.

[0083] The thermal crosslinking agent is - ensures a sufficiently long processing time, so that gelling does not occur during the processing process, in particular the extrusion process, In addition, it also brings about a rapid post-crosslinking 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 polymer containing carboxy- (carboxylic acid-), amino-, and / or hydroxy groups can be combined with an isocyanate, especially an aliphatic or blocked isocyanate, such as an amine-quenched trimeric isocyanate, as a crosslinking agent. Suitable isocyanates are, in particular, the trimeric 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, aluminum acetylacetonate.

[0087] Preferably, the poly(meth)acrylate is crosslinked with epoxide(s) or with one or more epoxide group-containing substances(s), thereby ensuring permanent, 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 general, 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-hydroxy ... 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'-dihydroxydiphenyl sulfone] epoxy ethers and their hydroxyethyl ethers, phenol-formaldehyde condensation products, such as phenol alcohol, and phenolaldehyde resins; S-containing and N-containing epoxides (e.g., N,N-diglycidylaniline, N,N'-dimethyldiglycidyl-4,4-diaminodiphenylmethane, tetraglycidyl-meta-xylenediamine), as well as epoxides prepared from monounsaturated carboxylic acid esters of polyunsaturated carboxylic acids or unsaturated alcohols according to conventional methods; glycidyl esters;Polyglycidyl esters 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 their derivatives);

[0090] Very suitable ethers are, for example, 1,4-butanediol diglycide ether, polyglycerol-3-diglycide ether, cyclohexanedimethanol diglycide ether, glycerin triglycide ether, neopentyl glycol diglycide ether, pentaerythritol tetraglycide ether, 1,6-hexanediol diglycide ether, polypropylene glycol diglycide ether, trimethylolpropane triglycide ether, pentaerythritol tetraglycide ether, bisphenol-A diglycide ether, and bisphenol-F diglycide ether.

[0091] Yet another preferred epoxide is a cycloaliphatic epoxide such as 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate (UVACure 1500).

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

[0093] According to a preferred embodiment, the poly(meth)acrylate is crosslinked using a crosslinker-accelerator system ("crosslinker system") to obtain better control over processing time, crosslinking rate, and degree of crosslinking. The crosslinker-accelerator system preferably comprises at least one epoxide group-containing substance as a crosslinker and at least one substance as an accelerator that serves to accelerate the crosslinking reaction with the epoxide group-containing compound at temperatures 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 the substitution product of ammonia; the substituents include, in particular, alkyl and / or aryl groups.Particularly preferably, the amines that do not react or only slightly react with the polymer to be crosslinked are used.

[0095] In principle, the accelerator can be selected from primary amines (NRH2), secondary amines (NR2H), and tertiary amines (NR3), and of course, amines having 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, and N,N'-bis(3-(dimethylamino)propyl)urea. Further preferred accelerators are polyfunctional amines, such as diamines, triamines, and / or tetraamines, such as diethylenetriamine, triethylenetetramine, and trimethylhexamethylenediamine.

[0096] Further preferred accelerators are amino alcohols, in particular secondary and / or tertiary amino alcohols, where, if there are several amino functional groups per molecule, preferably at least one, particularly preferably all, of the amino functional groups 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'-hydroxyethylbisaminoethyl ether, N,N,N'-trimethylaminoethylethanolamine and N,N,N'-trimethylaminopropylethanolamine.

[0097] Further suitable accelerators include pyridine, imidazoles such as 2-methylimidazole and 1,8-diazabicyclo[5.4.0]undec-7-ene. Alicyclic 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 can 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, in particular 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, in particular to at least one substrate, is not negatively affected before 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] "Microballoons" are understood to mean hollow microspheres 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. Polyacrylonitrile, PVDC, PVC, or polyacrylates are particularly suitable as shell materials. Suitable low-boiling liquids or gases are, in particular, hydrocarbons such as lower alkanes, for example, isobutane or isopentane, which are enclosed in the polymer shell under pressure as liquefied gases, with isopentane being particularly preferred.

[0103] In particular, by applying heat to the microballoons, the outer polymer shell softens. At the same time, the liquid foaming gas present in the shell changes to its gaseous state. This causes the microballoons to irreversibly expand and expand three-dimensionally. The expansion ends when the internal and external pressures are equalized. 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 (unexpanded diameter from 6 to 45 μm) and the initial temperature required for expansion (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. This can be, for example, a silicate or alumosilicate. However, carbonates, such as calcium carbonate, or various oxides can also 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 made of silicate or alumosilicate on their surface.

[0107] Silicates are salts of orthosilicic acid (Si(OH)4) and its condensates. All salts are compounds composed of SiO4 tetrahedra, although the tetrahedra can be bonded to each other in various ways. The free sites of the tetrahedra contribute to the charge balance of metal cations or sometimes hydroxide ions (OH - Alumosilicate is a collective name for compounds from the group of silicates, which are composed of SiO₄ and AlO₄ tetrahedra as basic building blocks.

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

[0109] In this case, the unexpanded microballoons are usually added to the adhesive in an unexpanded state and only then are they expanded, in particular by heating.

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

[0111] Foamed adhesive layers can also be produced using so-called pre-expanded microballoons. In the case of pre-expanded microballoons, expansion occurs before the microballoons are mixed into the polymer matrix. Pre-expanded microballoons are commercially available, for example, under the name Dualite®. When processing pre-expanded microballoons, the microballoons tend to float due to their low density in the polymer matrix into which they are incorporated, i.e., they can float "upward" 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, resulting in a density gradient across the layer thickness.

[0112] 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 then expanded only after they are incorporated into the layer. In this way, a more uniform distribution of the microballoons in the polymer matrix is ​​achieved.

[0113] The expansion of the expandable microballoons occurs only after or directly during compounding, 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 spaces 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 spaces formed by the microballoons in the foamed adhesive layer is measured, so the diameter is the diameter of the hollow spaces formed by the expanded microballoons. The average diameter here refers to the arithmetic calculation of the diameter of the hollow spaces formed by the microballoons in the adhesive layer. The determination of the average diameter of the hollow spaces 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 500x magnification. The diameter of the microballoons visible in the photograph is determined graphically by taking the largest dimension in any (two-dimensional) direction from the REM photograph of each individual microballoon in the examined adhesive layer and considering it as the 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] According to an embodiment of the invention, the proportion of microballoons in the adhesive layer is between more than 0 and 12% by weight, particularly preferably between 0.25 and 5% by weight, and very particularly preferably between 0.5 and 3% by weight, each based on the total composition of the corresponding layer (including the incorporated microballoons).

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

[0120] The adhesive of adhesive layer D may further contain other conventional additives, such as tackifying resins, softeners, compatibilizers, and fillers. The compatibilizer is preferably a low-molecular-weight polyether, polyamine, polyvinylpyrrolidone, or aliphatic polyester, which can be uniformly mixed with the adhesive. Some softeners can also be compatibilizers, such as polyethylene glycol (PEG). According to a particularly preferred embodiment, the adhesive of adhesive layer D contains at least one polyether, preferably at least one substance selected from the group consisting of polyethylene glycol (PEG), polypropylene glycol (PPG), and polytetrahydrofuran, with PEG and PPG being particularly preferred. The use of these substances particularly aids in peelability. While not intending to be bound by any particular theory, it is believed 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 substances is preferably between 100 and 5000 g / mol, particularly preferably between 200 and 2000 g / mol. Those skilled in the art will recognize that PEGs and PPGs with different molecular weights Mw are available, for example PEG 400 or PPG 600 (the numbers represent Mw).

[0122] A further object of the present invention is to provide a coating 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 bonds the 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 comprising the steps of: i.) applying a voltage to two different points of the junction, the voltage preferably being 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 in accordance with step i.) of the method of the invention for the electrical delamination of the bonded body, the voltage being in particular a direct current voltage.

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

[0126] The method of the present invention for the electrical debonding of the bonded assembly allows substrates A and B to be quickly and simply debonded from one another without requiring the application of excessive force.

[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 adhesive 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 therefore on the nature of the individual layers and of the substrates A and B bonded together.

[0130] Below are described some preferred embodiments.

[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, since both substrates A and B are electrically conductive. For this purpose, a voltage is applied to substrates A and B, which causes anions to migrate to the anode and cations to migrate to the cathode in the adhesive. Without intending to be bound by a particular theory, the inventors assume the following mechanism: application of a voltage causes migration of electrolytes in adhesive layer D, in particular separation of anions and cations of the ionic liquid. This significantly weakens the adhesion of adhesive layer D to substrates A and B, causing these layers to peel off from each other.

[0133] Therefore, according to a preferred embodiment of the present 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, comprising an adhesive layer D, which is arranged between substrate A and substrate B and 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, which in principle can 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 also be used, in particular and advantageously, for the subsequent peeling off of substrates A and B from one another, where only one substrate, for example 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 applied beforehand as a double-sided adhesive tape, with an electro-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 hypothesize 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 from each other.

[0141] According to a preferred embodiment of the present 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 previously described embodiment is composed of the three layers D, T and C. For this purpose, within the scope of the present invention, the term three-layer assembly DTC is also used.

[0144] Therefore, according to a preferred embodiment of the present 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 comprises 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, 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 the 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 to a large number of different substrates via the adhesive layers C and C'.

[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 particularly and advantageously for the subsequent peeling 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 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.) at least one of the adhesive layers C and C' and 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, the carrier layers T and T' can be particularly well applied to a voltage if they extend laterally beyond at least one of the adhesive layers adjacent to them.

[0153] According to yet another preferred embodiment of the present 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 aforementioned embodiment is composed of five layers C, T, D, T' and C', for which purpose the term five-layer assembly CTD-T'-C' is also used within the framework of the present application.

[0155] Therefore, according to a preferred embodiment of the present 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 composite CTD-T'-C' and bonds substrates A and B to one another.

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

[0157] The electrically non-conductive substrate in all embodiments can 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, automotive, medical and dental devices.

[0159] The carrier layers T and T and T′ in all the above-described embodiments are electrically conductive.

[0160] These layers are further described below. For brevity, the term "electrically conductive carrier layer" or simply "carrier layer" is used. This refers to carrier layer T or 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] According to a preferred embodiment of the present invention, the electrically conductive carrier layer comprises 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 for the layer T to comprise 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), that are coated with a metal, for example copper and / or nickel, thereby providing the fabric with electrical conductivity.

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

[0170] Furthermore, metal grids of various dimensions are 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 at least one film of the appropriate layer thickness.

[0171] In metallized films, non-conductive films are vapor-deposited with metal to render them electrically conductive. The film material can be selected from all materials suitable for vapor-depositing metal and for use as carrier films for adhesive tapes. These materials are preferably selected from polyesters and polyolefins, although mixtures of several materials are also possible. Polyesters are preferably polyethylene terephthalate (PET) and polyethylene naphthalate (PEN). Polyolefins are preferably polypropylene (PP) and polyethylene (PE). In a preferred embodiment, the film material is selected from the group consisting of PET, PEN, PE, and PP.

[0172] Preferably, these are films made of PET (polyethylene terephthalate). Such films are dimensionally stable and therefore easily processable without significant stretching or tearing. This allows for a consistent application of a uniform, defect-free metal layer, thereby ensuring consistent electrical conductivity across the entire film (especially in the z-direction).

[0173] In embodiments 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 extend laterally beyond at least one adjacent adhesive layer in at least one extension direction of the layer plane and thus have lateral extensions, to which a voltage can be easily 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 a carrier layer, it is preferred that this carrier layer only extends laterally beyond the adjacent adhesive layer in at least one extension direction of the layer plane, and each other 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 other adhesive layers serve as carriers for the metal layer. However, for the sake of simplicity, the description of a carrier layer for a metal layer is retained in these embodiments. Preferably, the layer thickness of layer T in this case is 10 nm (nanometers) or more, preferably 50 to 200 nm.

[0176] According to a preferred embodiment of the present 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 comprising at least one metal, preferably at least one metal selected from the group consisting of copper and nickel, and / or d) at least one metal grid, and / or e) a vapor-deposited metal 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 for a simple and reliable application of a voltage to the carrier layer. At the same time, the adhesive tape can be produced relatively easily.

[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 vapor-deposited metal, preferably at least one vapor-deposited 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 beyond the first adhesive layer D. In this case, this film is metallized, in particular on one surface, and each carrier layer is bonded to the first adhesive layer D, and thus to the electrically peelable layer, via the metallized film. This makes it possible to apply a voltage to the carrier layer simply and reliably.

[0179] The term "lateral extension" in the context of the present invention means any type of lateral extension of the layer(s) in question, meaning that 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 term "lateral extension", the terms "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, for example.

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

[0182] The adhesive layer 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 the layer C or C and C' does not have to contain an electrolyte, but may contain one. Preferably, the layer C or C and C' does 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, the term "electrically conductive adhesive layer" is used where appropriate. 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 refers to each of the above-mentioned layers in the above-mentioned embodiments of an 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 contains at least one metal, such as, in particular, nickel, copper, or 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 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 contains electrically conductive particles 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 contains nickel particles.

[0187] Preferably, the electrically conductive adhesive layer comprises from 5 to 40% by weight, particularly preferably from 20 to 40% by weight, and 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 no 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 particularly 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 configured to be electrically conductive only in the z-direction but not necessarily in the xy-direction, in a preferred embodiment in which metal, especially metal particles, are added to make it electrically conductive, less of these materials are required. This allows the adhesive to be optimized in terms of the required conductivity, adhesive strength, flow behavior, and cost.

[0190] Within the scope of the present invention, a layer is considered to be "electrically conductive" if it has a resistance of less than 1 ohm, measured in the respective direction, here particularly 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] In a preferred embodiment of the present invention, adhesive layer C or C and / or C′ is based on poly(meth)acrylate, just like adhesive layer D. In this case, all of the above statements regarding the definition and 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 adhesive layer C or C and / or C' as in 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 aging 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 adhesive layer D is used in 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 adhesive layer C or C and / or C'. Adhesive layer C or C and / or C' preferably does not or does not need to contain an electrolyte, such as an ionic liquid, so that no matching components thereto are required.

[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 present invention, at least one vinyl aromatic block copolymer is contained in the adhesive layer C or C and / or C'.

[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, in a proportion of 70 to 100% by weight, based on 100% by weight of the polymer contained in layer C. Any tackifying resins contained in the adhesive layer are not included in this calculation as 100% by weight of the polymers contained.

[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 with the structure ABA and polymers with 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 1,3-diene and isobutylene monomers, 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] With it, the problem on which the invention is based is solved particularly well.

[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, wherein 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] With it, the problem on which the invention is based is solved particularly well.

[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 included vinyl aromatic block copolymer(s) have a weight average molecular weight distribution Mw(GPC) of from 50,000 to 300,000 g / mol, particularly preferably from 80,000 to 180,000 g / mol.

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

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

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

[0214] By "tackifying resin" is meant, as understood by those skilled in the art, an oligomeric or polymeric resin that 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 It has.

[0216] Preferably, the 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 those skilled in the art that such tackifying resins can be selected that are particularly compatible with the vinyl aromatic block copolymer(s).

[0218] The adhesive of adhesive layer C or C and / or C' may further comprise other 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 undesired premature separation between the substrates does not occur, especially when a force (e.g., due to a fall) acts 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 releasable, so all types of microballoons known to those skilled in the art can be used.

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

[0222] Preferably, the adhesive of adhesive layer D is a pressure-sensitive adhesive, and therefore adhesive layer D is preferably a pressure-sensitive adhesive layer D. This allows the adhesive tape to be easily bonded on its side, since, in particular, no heat input is required compared to heat-activatable adhesive systems. Furthermore, components of the electrolyte, such as ions in particular of ionic liquids, 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, as commonly used, refers to a substance that is persistently tacky and adhesive (especially at room temperature). A pressure-sensitive adhesive is characterized by the fact that it can be applied to a substrate by pressure and remains adhered thereto, without specifying the pressure used or the duration of application of this pressure. In some cases, depending on the exact type of pressure-sensitive adhesive, the temperature and humidity of the air, and the substrate, a short, minimal application of pressure, not exceeding a momentary light touch, is sufficient to achieve an adhesive effect, while in other cases, a long application of high pressure may be required.

[0227] Pressure-sensitive adhesives have characteristic viscoelastic properties that, in particular, provide them with long-lasting tack and adhesion. What is characteristic of pressure-sensitive adhesives is that when they are mechanically deformed, they undergo both a viscous flow process and the development of elastic restoring forces. Both processes, in terms of the proportion of each, are in a specific ratio to each other, depending on the exact composition, structure, and degree of crosslinking of the pressure-sensitive adhesive, as well as on the rate and time of deformation, and on the temperature.

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

[0229] A proportional elastic resilience is necessary to achieve cohesion. This resilience is provided, for example, by very long-chain, highly entangled polymers and physically or chemically crosslinked polymers and allows the transmission of forces acting on the adhesive bond. The resilience enables the adhesive bond to 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 fractions 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 fraction of a material, and G" is a measure for the viscous fraction of a material. Both values ​​depend on the deformation frequency and the temperature.

[0231] These values ​​can be determined using a rheometer. The material to be investigated is subjected to a sinusoidally oscillating shear load, for example in a plate-plate configuration. In shear-stress-controlled instruments, the deformation as a function of time and the time lag of this deformation relative to the introduction of 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 defined as pressure-sensitive adhesive within the meaning of this specification, if it has a deformation frequency of 10°C at room temperature, as defined here at 23°C. 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 7At least one section of the G' curve lies 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" ranging from 0.1 to 10 Pa.

[0236] To achieve viscoelastic properties, the monomers on which the polymer forming the basis of the pressure-sensitive adhesive is based, as well as any further components of the pressure-sensitive adhesive, are selected in particular 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 polymers), the temperature range in which the polymer composition exhibits pressure-sensitive adhesive properties can be expanded and / or shifted. Therefore, the use range of the pressure-sensitive adhesive can be optimized by adjusting the adhesive's flowability and cohesive strength.

[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, differ from pressure sensitive adhesives in that they have no adhesive properties at room temperature (23° C.) even in the hot melt adhesive composition.

[0239] A further subject of the present 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 expanding 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 these layers are in contact with each other, with the electrically conductive layer T being disposed between the layers D and C, so that the layer assembly DTC is obtained as a double-sided adhesive tape; and E) foaming the first adhesive layer D, wherein the foaming occurs by expanding the expandable microballoons.

[0241] Process step A) in 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 in step A1) is carried out in particular by providing at least one polymer, which may optionally contain further components. All of the above statements regarding adhesive layer D apply to the adhesive, electrolyte, and expandable microballoons. The list of steps A2) to A5) does not necessarily represent a chronological order. For example, an electrolyte, such as at least one ionic liquid, can be added to the adhesive first, and only then can the expandable microballoons be added.

[0243] According to yet another embodiment of the present invention, a method for the production of an adhesive tape according to the present 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 the electrolyte to the adhesive;

[0244] All statements made above regarding 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, to the adhesive and only then 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 carried out in particular by providing at least one further adhesive, which is brought into the form of a layer using known methods, in particular by spreading, and optionally one or more drying steps can then be carried out.

[0247] The lamination according to step D) is carried out in a manner known to those 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 placed 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-coated PET film between layer D and layer C.

[0250] Furthermore, 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 of step D) or after it.

[0253] In a preferred embodiment, the adhesive of adhesive layer C is likewise provided with expandable microballoons when it is provided in step B). Expansion is particularly and preferably achieved by heating the layer or layers to be expanded to the appropriate temperature required for the expansion of the microballoons used.

[0254] In particular, if layer C also contains expandable microballoons, it is preferable to carry out the expansion according to step E) 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 manufacturing 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, either two 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 film (also referred to as a 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 double-sided silicone-coated material. 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. Furthermore, 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 term "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 thicknesses, with the thickness of adhesive layer D being less than that of adhesive layers C or C and C', for example. According to a further embodiment, layers D and C, or D, C and C', have the same thickness. If layer D is too thick, this may become uneconomically costly due to the electrolyte contained therein.

[0260] Preferred embodiments of the present invention will now be explained in more detail with reference to the accompanying drawings. [Brief explanation 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. [Figure 2] FIG. 2 shows a simplified schematic cross-section of a double-sided adhesive tape according to the invention in a preferred embodiment. [Figure 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. [Figure 5] FIG. 5 shows a simplified schematic cross-section of a bonded assembly according to the present invention with a voltage applied, 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 to the carrier layer T2 over its surface. On the side of the carrier layer T opposite to 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, where one side of an adhesive layer D and one side of a second adhesive layer C are each available for bonding.

[0264] 2 shows a preferred embodiment of the invention, in which the electrically conductive carrier layer T2 extends 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 an extending portion with at least one free surface 2a.

[0265] Figure 3 shows another preferred embodiment of the invention. In this case, the electrically conductive carrier layer T2 extends laterally from the adhesive layer D1 in at least one direction of extension of the layer plane, so that the electrically conductive carrier layer T2 has an extension with one free surface 2a. In Figure 3, the adhesive layer C3 is also configured so that it extends beyond 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] Fig. 4 shows a schematic diagram of a bonded assembly according to the invention in 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 extends laterally 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.

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

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

[0269] FIG. 7 shows another schematic diagram of a bonded assembly according to the present invention in a preferred embodiment. 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 layers C3 and C'7, there is an electrically releasable adhesive layer D1 and two electrically conductive carrier layers T2 and T'6, with layer D1 arranged between these carrier layers. FIG. 7 also exemplarily shows that the electrically conductive carrier layers T2 and T'6 each extend laterally 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] Figure 8 shows yet another schematic diagram of an assembly bonded according to the invention in a preferred embodiment, which is similar to Figure 7. However, unlike Figure 7, the protrusions of the electrically conductive carrier layer T2 and the electrically conductive carrier layer T'6 point 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 substrates A nor B need be electrically conductive.

[0272] Application of a voltage causes migration of the electrolyte, in particular separation of the anions and cations of the ionic liquid, in the adhesive layer D1. This significantly weakens the adhesion of the adhesive layer D1 to the carrier layers T2 and / or T'6, causing these layers to separate from each other. Peeling occurs particularly 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 depictions 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 schematically as further layers. They can, of course, have any other three-dimensional shape. [Example]

[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 are based on determination by gel permeation chromatography (GPC). The determination is carried out on 100 μl of a clarified filtered sample (sample concentration 4 g / l). The eluent used is tetrahydrofuran containing 0.1% by volume of trifluoroacetic acid. The measurement is carried out at 25°C. The pre-column used is a column type PSS-SDV, 5 μm, 10 3 Å, 8.0 mm * 50 mm (here and hereinafter, the order of type, particle size, porosity, inner diameter * length; 1 Å = 10 -10 For separation, we use 8.0mm*300mm type PSS-SDV, 5μm, 10 3 Å and 105 Å and 10 6 A combination of columns of 1.0 Å is used (Polymer Standards Service columns; detection is performed using a Shodex RI71 differential refractometer). The flow rate is 1.0 ml per minute. Calibration is performed against PMMA standards (polymethyl methacrylate calibration) in the case of polar molecules, such as the raw polyurethane, 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 the adhesive layer applied to the liner, defined by its length and width. The thickness of the adhesive layer can be determined with a precision of less than 1 μm using a conventional thickness measuring device (sensor test device). If thickness variations are observed, the average value of measurements at at least three representative locations is taken. That is, measurements are particularly not taken 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 also be determined with a precision of less than 1 μm using conventional thickness measuring devices (sensor test devices). If thickness variations are observed, 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 to a 23 μm thick PET film with the adhesive side of layer C, with a slight adhesive overhang. This assembly is applied with the electrically peelable side (layer D) to a steel plate that has previously been 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 measurement 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 in the same way, with a 20 mm wide strip of the adhesive tape of the invention first applied with the electrically releasable adhesive side (layer D) to a 20 μm thick PET film with a slight adhesive overhang, and 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: An acrylate-based base polymer is prepared as follows: 48 kg of 2-ethylhexyl acrylate, 48 kg of n-butyl acrylate, 4 kg of acrylic acid, and 66 kg of mineral spirit / acetone (70 / 30) are charged into a conventional reactor for radical polymerization. After 45 minutes of nitrogen gas passage with stirring, the reactor is heated to 58°C and 50 g of AIBN is added. The external heating bath is then heated to 75°C, and the reaction is carried out constantly at this external temperature. After 1 hour, 50 g of AIBN is again added, and after 4 hours, 20kgThe polymerization is then diluted with a petroleum spirit / acetone mixture. After 5.5 and 7 hours, respectively, the polymerization is restarted with 150 g of bis-(4-tert-butylcyclohexyl) peroxydicarbonate. After a reaction time of 22 hours, 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 polymer (excluding the solvent), 5.5 wt% of 1-ethyl-3-methylimidazolium-bis(trifluoromethylsulfonyl)imide (EMIM-TFSI) as an ionic liquid and 4 wt% of polyethylene glycol 400 (Sigma Aldrich) were mixed.

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

[0286] Additionally, 1 wt % of Matsumoto FN100SSD microballoons based on the total amount of adhesive in Layer D is added, 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, so as to result in a layer thickness of 45 μm after drying at 110° C.

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

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

[0290] An aluminum-coated PET film having 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 has been vapor-deposited. The resulting 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 thickness of this adhesive layer C again being 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 the carrier layer T and the 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 provided with the silicone-coated liner on both sides, is then heated to 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, the 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 representing the conductive substrate A (see also the method description for "adhesion"). A 23 μm thick PET film is applied to the other side. After application, a voltage is applied; specifically, the cathode is applied to the steel plate and the anode is applied 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 adhesive strength of the adhesive layer D of this adhesive tape to the steel plate is measured again, in this case the adhesive strength is only 0.5 N / cm.

[0300] By applying a voltage, the adhesive force could be significantly weakened.

[0301] Example 2 according to the present invention In a second example, the electrically releasable 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 relative to 100% by weight of the amount 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 crosslinking agent 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, specifically an adhesive consisting of 33% Kraton D1118, 17% Kraton D1102 and 50% Piccolyte A115.

[0309] This adhesive also contains 1 wt% Matsumoto FN100SSD microballoons.

[0310] This adhesive is applied to a 25 μm thick aluminum-coated PET film as carrier layer T, similar to Example 1, resulting in a layer thickness of 45 μm. Again, a silicone-coated PET film as 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 releasable side, i.e., the side with adhesive layer D free, and 8.4 N / cm on the other side, i.e., the side with adhesive layer C free.

[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 minute. At this point, uniform expansion of the microballoons is not possible; rather, it is found that there is significantly less expansion. Under a microscope, it can be seen that the microballoons have already been largely destroyed. It appears that the calcium carbonate-coated microballoons are incompatible with the ionic liquid.

[0318] Surprisingly, therefore, it is only by using microballoons with a silicate or alumosilicate coating that an electro-releaseable, therefore electrolyte-containing and simultaneously foamed adhesive layer D can be successfully produced.

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

[0320] Substances used: Kraton D1102: Styrene-butadiene-styrene block copolymer containing a mixture of ABA and AB structures, 30% styrene content, 15% diblock content (AB), manufactured by 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: alpha-pinene terpene resin, softening point 115°C, manufactured by DRT Polyethylene glycol 400, Sigma Aldrich Polypropylene glycol 600, Sigma Aldrich Erysis® 240: Tetraglycidyl-meta-xylylenediamine, manufactured by Huntsman Matsumoto FN100SSD microballoons, manufactured by Matsumoto Honsha Microballoons Expancel 920DU20, manufactured by Nouryon This application relates to the invention described in the claims, but the disclosure of this application also includes the following. 1. An adhesive tape comprising at least the following layers: an adhesive layer D, which comprises at least one electrolyte and is foamed, the foaming being effected by means of microballoons, said microballoons having a layer made of silicate or alumosilicate on their surface; 2. The adhesive tape according to claim 1, wherein the electrolyte of adhesive layer D is selected from the group consisting of ionic liquids and metal salts, with ionic liquids being particularly preferred. 3. 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 - , 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 - The adhesive tape according to 2. above, characterized in that it is selected from the following. 4. The 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 selected from the group consisting of imidazolium-based cations, and the cation is particularly preferably selected from the group consisting of 1-ethyl-3-methylimidazolium and 1-butyl-3-methylimidazolium, with 1-ethyl-3-methylimidazolium being very particularly preferred. 5. An adhesive tape according to any one of 1. to 4. above, characterized in that the electrolyte of adhesive layer D is selected from the group consisting of ionic liquids 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (EMIM-TFSI) and 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide (EMIM-FSI). 6. The adhesive tape according to any one of 1. to 5. above, characterized in that the first adhesive layer D is based on poly(meth)acrylate. 7. An adhesive tape according to any one of the above paragraphs 1 to 6, characterized in that the first adhesive layer D contains 2 to 10% by weight, preferably 4 to 6% by weight, of an electrolyte, preferably an ionic liquid, based on 100% by weight of the polymer contained. 8. The adhesive tape according to any one of 1. to 7. above, which is a transfer adhesive tape and comprises an adhesive layer D. 9. The adhesive tape according to any one of the above paragraphs 1 to 7, further comprising at least the following layer: 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 1. to 7. above, further comprising at least the following layer: 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′ arranged on the surface of the adhesive layer D opposite to the first electrically conductive carrier layer T; and A third adhesive layer C' arranged on the surface of the second carrier layer T' opposite to the first adhesive layer D. 11. The adhesive tape according to paragraph 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 selected from the group consisting of copper, nickel, zinc, tin, silver, gold, aluminum, iron, chromium, and alloys of these metals, 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. 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 The adhesive tape according to any one of 1. to 12. above, which is disposed between a substrate A and a substrate B and bonds the substrates A and B to each other. 14. A method for electrically peeling a bonded body according to paragraph 13, comprising at least the following process steps: i.) applying a voltage to two different points on the bonded body, the voltage being preferably 2 to 20 V, particularly preferably 3 to 15 V. 15. Use of the adhesive tape according to any one of 1. to 12. above for bonding components in electronic devices, automobiles, medical devices, and dental devices. [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. At least the following layers: a first adhesive layer D, An adhesive tape comprising: the first adhesive layer D contains at least one electrolyte and is foamed, wherein the foaming is effected by means of microballoons, and the microballoons have a layer made of silicate on their surface; the electrolyte of the first adhesive layer D is selected from the group consisting of ionic liquids, and The cation of the ionic liquid is selected from the group consisting of imidazolium-based cations; The adhesive tape.

2. 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 － , 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 － 2. The adhesive tape of claim 1, wherein the adhesive tape is selected from the group consisting of:

3. The adhesive tape according to claim 1, wherein the anion of the ionic liquid is selected from (CF 3 SO 2 ) 2 N − , (CF 3 CF 2 SO 2 ) 2 N − and (FSO 2 ) 2 N − .

4. The adhesive tape according to claim 1, wherein the anion of the ionic liquid is selected from (CF 3 SO 2 ) 2 N − and (FSO 2 ) 2 N − .

5. 2. The adhesive tape according to claim 1, wherein the cation of the ionic liquid is selected from the group consisting of 1-ethyl-3-methylimidazolium and 1-butyl-3-methylimidazolium.

6. The adhesive tape of claim 1, wherein the cation of the ionic liquid is 1-ethyl-3-methylimidazolium.

7. An adhesive tape as described in claim 1, characterized in that the electrolyte of the first 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).

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

9. 9. Adhesive tape according to claim 1, characterized in that the first adhesive layer D contains from 2 to 10% by weight of electrolyte, based on 100% by weight of the polymer contained.

10. An adhesive tape according to claim 1, wherein the first adhesive layer D contains 4 to 6% by weight of electrolyte, based on 100% by weight of the polymer contained therein.

11. 9. The adhesive tape according to claim 1, which is a transfer adhesive tape and comprises a first adhesive layer D.

12. The adhesive tape according to any one of claims 1 to 8, characterized in that it additionally comprises 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.

13. 13. The adhesive tape according to claim 12, characterized in that the electrically conductive carrier layer T comprises at least one metal, said metal being selected from the group consisting of copper, nickel, zinc, tin, silver, gold, aluminum, iron, chromium and alloys of said metals.

14. 14. Adhesive tape according to claim 13, characterized in that the electrically conductive carrier layer T comprises a) at least one metal film, and / or b) at least one electrically conductive textile containing at least one metal, and / or c) one or more layers of at least one vapor-deposited metal, and / or d) at least one metal grid, and / or e) a vapor-deposited metal film.

15. An adhesive tape according to claim 13, characterized in that the electrically conductive carrier layer T comprises: a) at least one aluminum film, and / or b) at least one electrically conductive textile containing 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 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.

16. The adhesive tape according to any one of claims 1 to 8, characterized in that it additionally comprises 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 first adhesive layer D opposite 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;

17. 17. The adhesive tape according to claim 16, characterized in that the electrically conductive first carrier layer T and the electrically conductive second carrier layer T' comprise at least one metal 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.

18. 18. Adhesive tape according to claim 17, characterized in that the electrically conductive first carrier layer T and the electrically conductive second carrier layer T' comprise a) at least one metal film, and / or b) at least one electrically conductive textile comprising at least one metal, and / or c) one or more layers of at least one vapor-deposited metal, and / or d) at least one metal grid, and / or e) a vapor-deposited metal film, 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.

19. An adhesive tape according to claim 17, characterized in that the electrically conductive first carrier layer T and the electrically conductive second carrier layer T' comprise a) at least one aluminum film, and / or b) at least one electrically conductive textile comprising 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 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 each other, the same or different from each other.

20. 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 8, which is disposed between a substrate A and a substrate B and bonds the substrates A and B to each other.

21. 21. A method for electrical delamination of a bonded body according to claim 20, comprising at least the following process steps: i.) applying a voltage to two different locations on the bonded body.

22. The electrical stripping method of claim 21, wherein the voltage is from 2 to 20 V.

23. The electrical stripping method of claim 21, wherein the voltage is from 3 to 15 V.

24. Use of the adhesive tape according to any one of claims 1 to 8 for bonding components in electronic devices, automobiles, medical devices and dental devices.

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