Adhesive compound, adhesive tape, bonded assembly and method for electrically separating the bonded assembly

Abstract

The invention relates to an adhesive compound, an adhesive tape, a bonded assembly, a method for electrically releasing the bonded assembly, and the use of the adhesive compound for bonding components in electronic devices, automobiles, medical devices, and dental devices. The adhesive compound comprises at least one electrolyte and a base compound, wherein the base compound comprises at least one polydiene block copolymer and at least one adhesive resin.

Description

The invention relates to a pressure-sensitive adhesive, an adhesive tape, an bonded composite, a method for electrically releasing the bonded composite and the use of the adhesive for bonding components in electronic devices, automobiles, medical devices and dental devices.Recently, there has been an increased interest in "bonding-on-demand" functionalities which are brought about on account of environmental laws or the awareness of end customers for sustainability and an increasing cost pressure during production. The application scenarios for debond processes are classified into reworking, repair, recycling, and processing aids.The purpose of the debond technologies is to achieve cohesive splitting of the adhesive layer or adhesive detachment of the adhesive layer from the substrate. While the former requires cleaning of the substrate before re-bonding, the latter does not require such a cleaning.However, adhesive-releasing technologies which guarantee the required high and permanently reliable bond strength are generally more difficult to realize or take a very long time in use, such as, for example, detachment by means of a migrating solvent.Thus, at present, particularly in the reworking or repair of electronic devices, such as smartphones and tablet computers, adhesive bonds that split predominantly cohesive are used, in many cases embodied as pressure-sensitive adhesive tapes, which are reduced in their cohesion by an increase in temperature to such an extent that a manual, cohesive separation of the bond can take place. Extensive reworking to prepare the substrate surface contaminated with adhesive residues for re-bonding is the consequence.In addition to heat-mediated separation methods, electrical separation methods are discussed. For example, EP 3031875 B1 discloses reducing the bond strength of an acrylate adhesive by applying a voltage.However, acrylate adhesives often do not have sufficient tackiness, especially on low-energy surfaces.It is therefore an object of the present invention to provide a pressure-sensitive adhesive, where the pressure-sensitive adhesive is also intended to adhere well to substrates having low energy surfaces and is also intended to be removable again from at least one substrate with little exertion of force. At the same time, the redetachment should be as simple and clean as possible. A supplementary object is to provide a corresponding advantageous adhesive tape.It is an additional object to specify an bonded composite and a method for redetaching the bonded connection produced by the adhesive composition or the adhesive tape.It is a further object of the invention to provide a use of the adhesives or adhesive tapes to be provided for bonding two or more substrates.The above objects are achieved by the subject matter of the invention as defined in the claims. Preferred embodiments according to the invention are evident from the further, dependent claims and the following explanations.Such embodiments, which are referred to below as preferred, are combined in particularly preferred embodiments with features of other embodiments referred to as preferred. Combinations of two or more of the embodiments referred to below as particularly preferred are thus very particularly preferred. Also preferred are embodiments in which a feature of one embodiment designated as preferred to any extent is combined with one or more further features of other embodiments designated as preferred to any extent. The invention thus includes combinations of individual features with one another and in this case also different preferred levels. Thus, the invention comprises, for example, the combination of a first feature marked as "preferred" with a second feature marked as "particularly preferred". Here, objects designated within the scope of "embodiments" are also included in different preferred stages. Features of preferred adhesive tapes, bonded composites and uses and methods result from the features of preferred pressure-sensitive adhesives. Features of preferred bonded composites, uses and methods also result from the features of preferred adhesive tapes.The PSA of the invention comprises at least one electrolyte and one base composition, where the base composition comprises at least one polydiene block copolymer and at least one tackifier resin.By means of the electrolyte present, the adhesive is also capable of being electrically removed after bonding by application of a voltage.Surprisingly, it has been found that a PSA comprising at least one polydiene block copolymer and at least one electrolyte can be redetached electrically from bonded substrates in a simple and rapid manner without great exertion of force, and at the same time the bond strength of the PSA to such substrates to be bonded with low energy surfaces is not adversely affected before the detachment.Adhesives and methods for the electrical redetachment or for the electrical reduction of the bond strength are known in principle in the prior art. Thus, as stated above, EP 3031875 B1 discloses such an electrical method. The electrically removable adhesive is an acrylate-based adhesive.However, it was not foreseeable here that a pressure-sensitive adhesive comprising at least one polydiene block copolymer could also be removed electrically after adhesion, and indeed without the adhesive force to the substrates to be adhered being adversely affected before dissolution. In particular, it was not to be assumed that polydiene-based PSAs which, owing to the high proportion of hydrocarbon compounds, have a non-polar character are miscible with electrolytes at all in such a form that, on the one hand, attractive pressure-sensitive adhesive properties are obtained and, on the other hand, detachment is possible by applying a voltage.At the same time, the detachment is clean and simple.The PSA of the invention is detailed below.The PSA comprises a base composition and at least one electrolyte, the amount of which is based on the amount of the base composition.An "electrolyte" is understood in the present case to mean a chemical compound "which is dissociated into ions in the solid, liquid or dissolved state and which moves in a directed manner under the influence of an electric field", as listed under the Wikipedia entry "electrolyte" of 04.01.2023.The electrolyte is preferably selected from the group consisting of ionic liquids and metal salts, with ionic liquids being particularly preferred.In particular, the adhesive tape can be easily detached again by one or more ionic liquids as electrolyte without the adhesive properties of the adhesive tape being adversely impaired. Ionic liquids have the advantage that they can be distributed well and homogeneously in the polymer matrix of adhesives and redetachment works more quickly than with other electrolytes.Furthermore, the constituents of ionic liquids are nonvolatile, in particular at room temperature. Ionic liquids are moreover comparatively heat-stable and noncombustible and also comparatively chemically stable.Ionic liquids in the context of the present invention are salts which are liquid at room temperature, i.e. 23° C. Ionic liquids accordingly contain anions and cations.Ionic liquids are therefore particularly suitable as electrolyte in the context of the separation process or process for electrical dissolution according to the invention.When a voltage is applied, the anions migrate to the anodic side and the cations to the cathodic side. Without wishing to be restricted thereto, it can be assumed mechanismally that this results in a lowering of the bond strength of the adhesive composition containing the ionic liquid to at least one substrate, as a result of which adhesive cleavage is achieved between the adhesive composition and the at least one substrate.In principle, all ionic liquids are suitable in the context of the present invention.The ionic liquids used in the context of the present invention comprise at least one anion and at least one cation. It is also conceivable here for the ionic liquid to comprise two or more types of anions and / or two or more types of cations. It is furthermore conceivable for two or more different ionic liquids to be added to the adhesive, or for the adhesive then to comprise two or more different ionic liquids.Preferably, the anion of the ionic liquid is selected from the group consisting of Br -, AlCl 4-, Al 2 Cl 7-, NO 3-, BF 4-, PF 6-, CH 3 COO -, CF 3 COO-, CF3CO3NER19_, CF3SO3NER22_, (CF3SO2)2N-, (cf_ner27_so_ner28_)_ner29_c -, AsF 6,-, SbF 6-, CF 3( CF 2)3 SO 3-( CF 3 CF 2 SO 2)2 N -, CF3CF2CF2COO-, (FSO2)2N-.The anion is particularly preferably tetrafluoroborate (BF4 -).This achieves a particularly high reduction in the bond strength by applying a voltage and hence particularly good electrical releasability of the PSA of the invention or of the adhesive tape of the invention. In particular, the (re)- oxidation reaction with this anion is particularly rapid and no residues remain.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.Particularly preferably, the cation is selected from the group consisting of imidazolium-based cations.This achieves a particularly high reduction in the bond strength by applying a voltage and hence particularly good electrical releasability of the PSA of the invention or of the adhesive tape of the invention. In particular, the (re)- oxidation reaction with this anion is particularly rapid and no residues remain.Most preferably, the cation is selected from the group consisting of 1-ethyl-3-methylimidazolium and 1-butyl-3-methylimidazolium.Again preferably, the cation is 1-ethyl-3-methylimidazolium.The electrolyte is particularly preferably 1-ethyl-3-methylimidazolium tetrafluoroborate.This achieves a particularly high reduction in the bond strength by applying a voltage and hence particularly good electrical releasability of the PSA of the invention or of the adhesive tape of the invention. In particular, the (re)- oxidation reaction with this anion is particularly rapid and no residues remain.It has proven particularly advantageous here if the pressure-sensitive adhesive of the invention comprises at least one styrene-butadiene-styrene block copolymer (SBS) and preferably at least one tackifier resin selected from polar resins, such as, in particular, rosin resins and terpenephenol resins, in combination with 1-ethyl-3-methylimidazolium tetrafluoroborate as electrolyte.It is preferred that the PSA comprises from 2 to 10% by weight, more preferably from 4 to 9% by weight, of electrolytes, preferably ionic liquids, based on 100% by weight of the base composition.With such a preferred or particularly preferred amount of electrolytes, in particular ionic liquids, a comparatively rapid electrical detachment is made possible, wherein at the same time the adhesion of the adhesive to in particular at least one substrate is not adversely affected before detachment.The PSA of the invention comprises a base composition, where the base composition comprises at least one polydiene block copolymer and at least one tackifier resin.The PSA of the invention preferably comprises from 80 to 95% by weight, more preferably from 85 to 95% by weight, very preferably from 85 to 92% by weight, of the basis composition, based in each case on the total mass of the PSA.Preferably, the at least one polydiene block copolymer is a polyvinyl aromatic polydiene block copolymer.According to a preferred embodiment, the at least one polyvinylaromatic polydiene block copolymer has a structure of the form A-B-A, (A-B) n, ( A-B) n X or (A-B-A) n X, in which• Blocks A, independently of one another, represent a polymer formed by polymerization of at least one vinylaromatic;• The blocks B independently of one another represent a polymer formed by polymerization of one or more conjugated dienes having 4 to 18 carbon atoms (C atoms);• X for the residue of a coupling reagent or multifunctional initiator and• n represents an integer ≥ 2.Coupling reagents and multifunctional initiators are known to the skilled person, as described, for example, in N. Hadjichristidis, M. Pitsicalis, S. Pispas, H. latrou, Chem. Rev., 2001, 101, 3747-3792; R. P. Quirk in Thermoplastic Elastomers, G. Holden, G. H. Kricheldorf, R. P. Quirk (Ed.), 3rd Edition, 2004, C. Hanser, Munich, pp. 71-75.The polyvinylaromatic polydiene block copolymers preferably each comprise one or more rubber-like blocks B (elastomer blocks, soft blocks) and at least two glass-like blocks A (hard blocks).In the embodiments described here, particular preference is given to at least one polyvinylaromatic-polydiene block copolymer having an A-B-A, (A-B) 2 X, (A-B) 3 X or (AB) 4 X structure, where A, B and X are each as defined above.The base composition preferably comprises at least one triblock copolymer or higher multiblock copolymer, which may be linear or multiarmed, such as radial or star-shaped.Preference is given, based in each case on the entirety of all polyvinylaromatic polydiene block copolymers in the base composition, to polyvinylaromatic polydiene block copolymers having a peak molar mass of at least 90,000 g / mol, more preferably of at least 120,000 g / mol. The peak molar mass of the polyvinylaromatic-polydiene block copolymers used is preferably not more than 300,000 g / mol, particularly preferably not more than 250,000 g / mol. The peak molar mass can be determined by GPC (test Ia) according to the method described in the section "test methods".In the ranges mentioned for the peak molar mass, the adhesive has very good processability together with very good thermal shear strength, the adhesive being correspondingly further optimized with regard to the conflict of goals of processability and thermal shear strength in the peak molar mass ranges which result from the selection of the lower limits and upper limits of higher preferred stages.The base composition may additionally comprise one or more diblock copolymers A-B. Too high a proportion of diblock copolymers, however, generally has a negative effect on the thermal shear strength. Their proportion in the pressure-sensitive adhesive should therefore not be too high. Particularly preferably, the average diblock fraction of the polyvinylaromatic polydiene block copolymers, based on the entirety of all polyvinylaromatic polydiene block copolymers of the base composition, is not more than 50% by weight, in particular not more than 35% by weight, and in this case preferably not more than 10% by weight.With the diblock fractions mentioned, the adhesive has very good flowability and bond strength with simultaneously very good thermal shear strength, the adhesive being correspondingly further optimized with regard to the conflict of goals of flowability and bond strength on the one hand and thermal shear strength on the other hand with the diblock fraction ranges which result from the selection of the lower limits and upper limits of higher preference stages.In particular, the base composition of the adhesive comprises a mixture of polyvinylaromatic-polydiene block copolymers having an A-B, A-B-A, (A-B) 3 X or (A-B) 4 X structure, which particularly preferably comprises a radial block copolymer and / or triblock copolymers A-B-A. Preference is likewise given to a mixture of triblock copolymers and (A-B) n- or (AB) n X block copolymers where n is greater than / equal to 3. The block copolymers may have linear A-B-A structures, be of radial shape and comprise star-shaped and linear multiblock copolymers.Vinylaromatics for building up block A preferably comprise styrene and styrene derivatives, more preferably styrene and α-methylstyrene. The block A can be present as a homo- or copolymer. Most preferably, block A is a polystyrene block.The at least one polydiene block copolymer is thus particularly preferably a polystyrene-polydiene block copolymer.Instead of the preferred polystyrene blocks, however, polymer blocks based on other aromatic-containing homo- and copolymers, preferably of C8to C12aromatics, in particular having glass transition temperatures of greater than 75° C., for example α-methylstyrene-containing aromatic blocks, can also be used as vinylaromatics. The glass transition temperature can be determined, for example, by means of DSC (test II).The polyvinylaromatic polydiene block copolymers used according to the invention can contain identical or different A blocks. Preferably, the polyvinyl aromatic polydiene block copolymers have polystyrene endblocks.The monomers for the soft block B are preferably conjugated dienes, in particular those selected from the group consisting of butadiene, isoprene, ethylbutadiene, phenylbutadiene, piperylene, pentadiene, hexadiene, ethylhexadiene, farnesene and dimethylbutadiene, and also any desired mixtures of these monomers. The block B can also be present as a homopolymer or as a copolymer. Particularly preferably, the monomers for the soft block B are selected from butadiene and isoprene.For example, the soft block B is a polyisoprene block or a polybutadiene block or a polymer block of a mixture of butadiene and isoprene. Most preferably, the block B is a polyisoprene or a polybutadiene, again preferably polybutadiene.In particular with polybutadiene as block B, high thermal shear strength and long-term stability of the adhesive composition are obtained.The A blocks of the polyvinyaromatic polydiene block copolymers preferably have a glass transition temperature of at least 25° C., in particular at least 50° C.For the B blocks, a glass transition temperature of not more than 0° C., in particular not more than -25° C., is preferred. These data relate to the pure, unblended block copolymers and are determined according to the invention by means of DSC (test II).The proportion of A block in the polyvinylaromatic polydiene block copolymers is preferably at least 12% by weight and at most 40% by weight, more preferably at least 15% by weight and preferably at most 35% by weight.In particular and preferably, the polydiene block copolymer is a polystyrene-polydiene block copolymer with a polystyrene content of 14 to 40 wt. %, preferably 18 to 35 wt. %, particularly preferably 20 to 35 wt. %.The proportion of the total of all polyvinylaromatic-polydiene block copolymers, based on the total basis weight, is preferably at least 35% by weight and at most 65% by weight, more preferably at least 40% by weight and at most 60% by weight. It has been found that too low a proportion of polyvinylaromatic polydiene block copolymers results in a decrease in the thermal shear strength of the pressure-sensitive adhesive, while too high a proportion of polyvinylaromatic polydiene block copolymers results in too much loss of adhesive capacity for the pressure-sensitive adhesive, so that the pressure-sensitive adhesive or the corresponding adhesive tape according to the invention can no longer be suitable for individual applications.The above data on the molar mass of the block copolymers relate in each case to that polymer mode which can be assigned to the block copolymer architecture mentioned in the relevant context by a person skilled in the art. Figures for the molar mass are to be understood in this context as peak molar mass. GPC usually allows the molecular weight of the individual polymer modes to be determined in a mixture of different block copolymers.According to particularly preferred embodiments, the at least one polyvinylaromatic polydiene block copolymer is a styrene-isoprene-styrene (SIS) block copolymer, in particular an SBS block copolymer.In particular, an SBS block copolymer gives high thermal shear strength and long-term stability of the adhesive composition.The total amount of polydiene block copolymers in the base composition is preferably 35 to 65 wt %, more preferably 38 to 60 wt %, most preferably 40 to 55 wt %, based on the total weight of the base composition.The base composition further comprises at least one tackifier resin.The adhesive resin is used in particular in order to set the adhesion and / or bond strength in the desired manner. According to the general understanding of the skilled worker, an "tackifier resin" is understood to mean an oligomeric or polymeric resin which increases the adhesion, i.e. the inherent tackiness, of the PSA compared with an PSA which does not comprise an tackifier resin but is otherwise identical. Tackifier resins are special compounds having a low molar mass compared with elastomers, such as the polydiene block copolymers present, usually having a weight-average molecular weight M w of less than 5,000 g / mol. Typically, the weight-average molecular weight of an tackifier resin component used in the context of the present invention is from 400 to 5,000 g / mol, preferably from 500 to 2,000 g / mol, determined by GPC (test Ib).The at least one tackifier resin is preferably compatible with the soft blocks of the polydiene block copolymers, i.e. with the polydiene blocks, and is preferably substantially incompatible with the hard blocks of the polydiene block copolymers.The expression "substantially incompatible" or "substantially incompatible" is understood in the context of the present invention in particular to mean that the constituents or components mentioned are miscible with one another to an extent of not more than 10% by weight, preferably not more than 5% by weight.The term "substantially compatible" is understood in the context of the present invention in particular to mean that the constituents or components mentioned are miscible with one another to an extent of at least 90% by weight, preferably to an extent of at least 95% by weight.The at least one tackifier resin preferably has a softening temperature (ring & ball, test III) of at least 70° C., preferably at least 90° C. and at most +140 ° C.The tackifier resin is preferably selected from the group consisting of nonpolar hydrocarbon resins, preferably hydrogenated and nonhydrogenated polymers of dicyclopentadiene (DCPD); nonhydrogenated, partially, selectively or fully hydrogenated hydrocarbon resins based on C5- or C5 / C9monomer streams or partially, selectively or fully hydrogenated hydrocarbon resins based on C9monomer streams; polyterpene resins based on α-pinene and / or β-pinene and / or δ-limonene, which may also be hydrogenated; polar oxygen-containing tackifier resins such as terpenephenol resins and rosin-containing resins, in particular rosin esters.Preference is given, inter alia, to at least one polyterpene resin based on α-pinene. In particular when the polyvinylaromatic polydiene block copolymer or copolymers are polybutadiene block copolymers, it is preferred that the pressure-sensitive adhesive of the invention comprises at least one polyterpene resin based on α-pinene.Rosin resins and rosin ester resins may be hydrogenated or non-hydrogenated or disproportionated or otherwise stabilized. Their acid number is preferably not more than 100 mg KOH / g (according to ASTM D465-15 / 2020).Terpene phenol resins may or may not be hydrogenated. Their OH number is preferably at most 100 mg KOH / g.According to preferred embodiments, at least one tackifier resin is present, which is selected from the group consisting of rosins and terpenephenol resins. The base composition thus contains a comparatively polar resin. This results in particularly good electrical redetachability of the pressure sensitive adhesive composition of the invention or of the adhesive tape of the invention.Preferred is, for example, and in particular, a hydrogenated resin based on a pentaerythrite esterified with rosin.The total amount of tackifier resins in the base composition is preferably at least 25% by weight, more preferably 25 to 65% by weight, very preferably 30 to 55% by weight, again preferably 35 to 55% by weight, based on the total weight of the base composition.In the ranges mentioned for the total amount of tackifier resins, the adhesive has an attractive thermal shear strength with simultaneously attractive bond strength and nevertheless electrical redetachability, the adhesive being correspondingly further optimized with regard to the conflict of goals of bond strength and thermal shear strength and redetachability in the ranges of amounts which result from the selection of the lower limits and upper limits of higher preference stages.Preferably, the proportion of polar resins, such as, in particular, rosins and terpene-phenol resins, is high.The proportion of polar resins, such as, in particular, rosin resins and terpene-phenol resins, based on the total amount of tackifier resins present in the base composition is preferably from 50 to 100% by weight, more preferably from 55 to 100% by weight.This results in particularly good electrical redetachability of the pressure sensitive adhesive composition of the invention or of the adhesive tape of the invention.The base composition of the pressure-sensitive adhesive composition of the invention may comprise further constituents in addition to the constituents mentioned.The base composition especially further comprises at least one plasticizer.The plasticizer serves primarily for final fine adjustment of the cohesion / adhesion balance. The plasticizer is preferably one or more soft resins and / or one or more mineral oils having a softening temperature, determined according to test III, of below 30° C. Preference is given to a soft resin or soft resin mixture and very preferably to a soft resin or soft resin mixture having a melt viscosity (test IV) at 25° C. and 1 Hz of at least 20 Pa*s, preferably of at least 50 Pa*s. Mineral or vegetable oils having a weight-average molecular weight of at least 500 g / mol, preferably of at least 800 g / mol, are also conceivable. Plasticizers based on poly(iso)butylene are also conceivable.The total amount of plasticizers in the base composition is preferably from 0 to 15% by weight, more preferably from 0 to 10% by weight. In the case where at least one plasticizer is present, the total amount of plasticizers is preferably from 1 to 15% by weight, more preferably from 1 to 10% by weight, very preferably from 1 to 5% by weight, based on the total weight of the base composition.To set further properties, the base composition may comprise further additives. Preferably, however, the proportion thereof is not more than 18% by weight of the base composition, preferably not more than 10% by weight.These additives are primarily preservatives. Mention may be made here of antioxidants of the primary and secondary types, light and UV protection agents and flame retardants, but also fillers, dyes and pigments. The adhesive layer can thus be dyed as desired or white, gray or black. As such or other other additives, it is typically possible to use:• primary antioxidants, such as, for example, sterically hindered phenols, preferably in a proportion of from 0.2 to 1% by weight, based on the total weight of the base composition,• secondary antioxidants, such as phosphites or thioethers, for example, preferably in a proportion of from 0.2 to 1% by weight, based on the total weight of the base composition,• Process stabilizers such as, for example, C radical scavengers, preferably in a proportion of from 0.2 to 1% by weight, based on the total weight of the base composition,• Light stabilizers such as, for example, UV absorbers or sterically hindered amines, preferably in a proportion of from 0.2 to 1% by weight, based on the total weight of the base composition,• Processing aid, preferably in a proportion of 0.2 to 1% by weight, based on the total weight of the base composition• optionally further polymers of preferably elastomeric nature; correspondingly usable elastomers include, inter alia, those based on pure hydrocarbons, for example unsaturated polydienes such as natural or synthetically produced polyisoprene or polybutadiene, chemically substantially saturated elastomers such as saturated ethylene-propylene copolymers, olefin copolymers, polyisobutylene, butyl rubber, ethylene-propylene rubber, and also chemically functionalized hydrocarbons such as, for example, halogen-containing, acrylate-containing, allyl- or vinyl ether-containing polyolefins, preferably with a proportion of 0.2 to 10 wt %, based on the total weight of the base composition.If the PSA comes into contact with a layer from which potentially so-called rubber poisons such as copper, manganese II, iron II, cobalt or nickel ions can be liberated, at least one type of a metal deactivator, also referred to as "metal scavenger", is advantageously added to it. Specific examples thereof are ADK rod CDA-1, CDA-1H, CDA-6 and CDA-10 and ADK rod ZS-27 or ZS-90 from Adeka, Hostanox OSP1 from Clariant, Naugard XL-1 from SIGroup and Irganox MD-1024 from BASF. Typical amounts used are up to 0.5% by weight, based on the base composition.In addition to the base composition and the electrolyte, according to preferred embodiments, the pressure-sensitive adhesive of the invention comprises at least one compatibilizer selected, for example, from the group consisting of polyethers, polyamines, polyvinylpyrrolidones or aliphatic polyesters, where the compatibilizer preferably has a weight-average molecular weight distribution Mwof from 100 to 5000 g / mol, more preferably from 200 to 2000 g / mol. Furthermore, amphoteric substances such as alkali metal or alkaline earth metal fatty soaps, anionic, cationic or nonionic surfactants can be used advantageously.According to particularly preferred embodiments, the pressure-sensitive adhesive of the invention comprises at least one polyether as compatibilizer, preferably at least one substance selected from the group consisting of polyethylene glycol (PEG), polypropylene glycol (PPG), polytetrahydrofuran, particular preference being given to PEG and PPG. Block copolymers of PEG and PPG are likewise conceivable, and polyethers which carry hydrocarbon segments.The substances mentioned surprisingly achieve particularly good redetachability. Without wishing to be bound by a specific theory, it is conceivable that the ion flow of the electrolyte or electrolytes through the mass layer is accelerated by the substances mentioned, in particular and for example PEG.In preferred embodiments in which at least one compatibilizer is present, the total amount of compatibilizers in the adhesive is from 1 to 10% by weight, preferably from 1 to 5% by weight, based on 100% by weight of the base composition.As a result, the adhesive is further optimized with regard to the conflict of goals of bond strength and electrical redetachability.In a particularly preferred embodiment of the invention, the PSA of the invention comprises the base composition described above, including all configurations or preference stages, preferably in an amount of 88 to 94% by weight, based on the total weight of the adhesive, and the ionic liquid comprises 1-ethyl-3-methylimidazolium tetrafluoroborate as electrolyte, preferably in an amount of 4 to 10% by weight, based on the total weight of the adhesive, and PEG as compatibilizer, preferably in an amount of 2 to 8% by weight, based on the total weight of the adhesive.The at least one polyvinylaromatic polydiene block copolymer is preferably at least one styrene-butadiene-styrene block copolymer, wherein particularly preferably two different styrene-butadiene-styrene block copolymers are contained.Preferably, the tackifier resin here is also a hydrogenated pentaerythritol rosin resin, preferably in a proportion, based on the total amount of tackifier resins present, of from 55 to 100% by weight.With such an adhesive, particularly good redetachability results with simultaneously good bond strength before redetachability.The adhesive of the invention is a pressure-sensitive adhesive.In the present case, a PSA is understood according to the invention, as is generally customary, to mean a substance which-especially at room temperature-is permanently tacky and adhesive. A characteristic of a pressure-sensitive adhesive is that it can be applied to a substrate by pressure and remains adhering there, the pressure to be applied and the duration of action of this pressure not being defined in any more detail. In some cases, depending on the precise type of PSA, the temperature and the atmospheric humidity and the substrate, the action of a short-term minimum pressure, which does not go beyond a slight contact for a short moment, is sufficient to achieve the adhesion effect; in other cases, a prolonged action duration of a high pressure may also be necessary.PSAs have particular, characteristic viscoelastic properties which lead to permanent tackiness and adhesiveness. It is characteristic of these that, if they are mechanically deformed, both viscous flow processes and the build-up of elastic restoring forces occur. With regard to their respective proportion, both processes are in a specific ratio to one another, depending both on the precise composition, the structure and the degree of crosslinking of the PSA and on the rate and duration of the deformation and on the temperature.The proportional viscous flow is necessary to achieve adhesion. Only the viscous components, caused by macromolecules with relatively great mobility, permit good wetting and good flow onto the substrate to be bonded. A high proportion of viscous flow leads to a high pressure-sensitive adhesiveness (also referred to as tack or surface adhesiveness) and thus often also to a high adhesive force. Highly crosslinked systems, crystalline or glassyally solidified polymers, are generally not tacky or at least only sparingly tacky, owing to the absence of flowable constituents.The proportional elastic restoring forces are necessary to achieve cohesion. They are caused, for example, by very long-chain and strongly entangled macromolecules and by physically or chemically crosslinked macromolecules and make it possible to transmit the forces acting on an adhesive bond. As a result, an adhesive connection can withstand a permanent load acting on it, for example in the form of a permanent shear load, to a sufficient extent over a relatively long period of time.For a more detailed description and quantification of the measure of elastic and viscous component and of the ratio of the components to one another, the variables storage modulus (G') and loss modulus (G") which can be determined by means of dynamic mechanical analysis (DMA, according to DIN EN ISO 6721) can be used. G' is a measure of the elastic fraction, G" is a measure of the viscous fraction of a substance. Both variables are dependent on the deformation frequency and the temperature.The quantities can be determined with the aid of a rheometer. The material to be examined is exposed to a sinusoidal oscillating shear stress, for example in a plate-plate arrangement. In shear stress controlled devices, the deformation as a function of time and the time offset of this deformation with respect to the introduction of the shear stress are measured. This time offset is referred to as phase angle δ.The storage modulus G' is defined as follows:The definition of the loss modulus G" is:A substance is generally considered to be pressure-sensitively adhesive and is defined as pressure-sensitively adhesive in the sense of the invention if, at room temperature, here as defined at 23° C., in the deformation frequency range of 10 0 to 10 1 rad / sec G' is at least partially in the range of 10 3 to 10 7 Pa, and if G" is likewise at least partially in this range. "partially" means that at least a portion of the G' curve is within the window, which is defined by the deformation frequency range from 10 0 inclusive to 10 1 rad / sec inclusive (abscissa) and the range of the G' values from 10 3 inclusive to 10 7 Pa inclusive (ordinate). This applies correspondingly to G".The PSA preferably has, in the deformation frequency range from 10 0 to 10 1 rad / sec at 23° C., a storage modulus G' and a loss modulus G" in the range from 10 3 to 10 7 Pa, determined in accordance with DIN EN ISO 6721.To achieve the viscoelastic properties, the monomers on which the polymers on which the PSA is based, and also the further components of the PSA which may be present, are selected in particular such that the PSA has a glass transition temperature (to DIN 53765) below the application temperature (i.e. usually below room temperature (23° C.)). By suitable cohesion-enhancing measures, such as, for example, crosslinking reactions (formation of bridge-forming linkages between the macromolecules), the temperature range in which a polymer composition has pressure-sensitively adhesive properties can be increased and / or shifted. The field of application of the PSAs can thus be optimized by adjusting the flowability and cohesion of the composition.In particular, the PSA has a glass transition temperature of ≤ 23° C., determined in accordance with DIN 53765.Unlike PSAs, hotmelt adhesives, for example based on polyamides, polyurethanes or modified polyethylenes, typically have no tackiness at room temperature (23° C.), as is also the case in hotmelt adhesive compositions.The present invention further provides an adhesive tape comprising at least one adhesive layer D of at least one adhesive of the invention.The adhesive tape of the invention is preferably a double-sided adhesive tape. For the sake of simplicity, the adhesive tape according to the invention is also referred to as "adhesive tape" in the double-sided embodiments within the scope of the present invention.The present invention relates to an adhesive tape which can be present in any desired formulation forms, with adhesive tape rolls being preferred. The adhesive tape, in particular in web form, can be produced either in the form of a roll, i.e. in the form of an Archimedes spiral rolled onto itself, or as an adhesive strip, as is obtained, for example, in the form of blanks or diecuts.The adhesive tape of the invention is present in particular in web form. A path is understood to mean an object whose length (extension in the x direction) is many times greater than its width (extension in the y direction) and whose width is designed to be approximately preferably exactly constant along the entire length.The general term "adhesive tape", also called "adhesive strips" as synonyms, encompasses, for the purposes of this invention, all planar structures, such as films or film sections extended in two dimensions, tapes with extended length and limited width, tape sections and the like, and ultimately also diecuts or labels.In addition to the longitudinal extent (x direction) and width extent (y direction), the adhesive tape also has a thickness (z direction) running perpendicular to both extents, the width extent and longitudinal extent being many times greater than the thickness. The thickness is as uniform as possible over the entire surface area of the adhesive tapes determined by length and width, preferably exactly the same within tolerances.The explanations apply analogously to the carrier layer(s) which, as a constituent of the adhesive tape, according to some preferred embodiments, form or form a layer in the x- and y-directions.It is understood that the individual layers are arranged one on top of the other along the z-direction.The present invention further provides an bonded composite 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 the substrate A and the substrate B and adheres the substrates A and B to one another.The present invention further provides a method for the electrical dissolution of the composite of the invention, comprising at least the following method steps: i.) applying a voltage at two different points of the composite, the voltage preferably being from 2 to 50 V.The voltage is applied according to step i.) of the method according to the invention for the electrical release of the composite.The voltage is in particular a DC voltage.According to preferred embodiments of the invention, the voltage is from 3 to 12 V. Such a voltage can be applied in particular by using a battery located in the immediate vicinity of the bond, such as in particular and for example in a mobile telephone, tablet etc.According to further preferred embodiments of the invention, the voltage is from 12 to 50 V. As a result of this comparatively high voltage, the redetachment can take place particularly quickly; the voltage in this case only has to be applied for a few seconds.The time duration of the application of the voltage in step i.) can be, in particular depending on the selected voltage, from a few seconds, in particular 2 seconds, up to 900 seconds, preferably up to 600 seconds.Of course, it is also conceivable for the voltage to be applied for a longer period of time than 900 seconds, in particular if the voltage is comparatively low.The method according to the invention for electrically releasing the composite according to the invention allows the substrates A and B to be released from one another in a quick and simple manner without requiring excessively great force expenditure.If the layers do not dissolve from one another without further action after application of the voltage, the method according to the invention comprises at least the further method step:ii.) Application of force to the adhesive layer D and / or the substrate A and / or the substrate B, so that the distance between the substrates A and B is increased.The force which may still be required according to step ii.) is significantly lower than the bond strength before the application of the voltage according to step i.)The voltage is applied according to step i.) at two different points of the bonded composite according to the invention. The locations at which the voltage is expediently applied depend on the structure of the adhesive tape and of the bonded composite and thus on the nature of the individual layers and substrates A and B bonded to one another.Some preferred embodiments are set forth below.According to preferred embodiments, the adhesive tape is a transfer adhesive tape and consists of the adhesive layer D.Such an adhesive tape can advantageously be released electrically again in an bonded composite with two substrates A and B by virtue of the fact that both substrates A and B are electrically conductive. For this purpose, a voltage is then applied to the substrates A and B, resulting in migration of anions to the anode and of cations to the cathode in the adhesive composition. Without wishing to be bound by any particular theory, the inventors assume the following mechanism: the application of the voltage causes the electrolyte to migrate, in particular the anions and cations of an ionic liquid, in the adhesive layer D. This greatly reduces the adhesion of the adhesive layer D to the substrate A and to the substrate B, and these layers are dissolved from one another.According to preferred embodiments of the present invention, the bonded composite thus comprises the following layers:• a first substrate A which is electrically conductive; and• a second substrate B which is electrically conductive; and• An adhesive tape according to the invention, which consists of the adhesive layer D and is arranged between the substrate A and the substrate B, and bonds the substrates A and B to one another.According to further preferred embodiments, 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 support layer T arranged between the layers D and C.Such an adhesive tape can be adapted as a double-sided adhesive tape via the second adhesive layer C to a multiplicity of different substrates. These may in principle be the same substrates as in the previous embodiments in which the adhesive tape is a transfer adhesive tape.However, such an adhesive tape can also be used in particular and advantageously for later releasing substrates A and B from one another, of which only one is electrically conductive, for example substrate A.According to preferred embodiments, either xi.) only the carrier layer T or xii.), the carrier layer T and the second adhesive layer C are configured to be electrically conductive.As a result, a voltage at xi.) of the electrically conductive carrier layer or xii.) can be applied to the second adhesive composition layer C and to the conductive substrate A.The adhesive tape is advantageously bonded beforehand as double-sided adhesive tape in such a way that the electrically releasable adhesive layer D is bonded to the conductive substrate A and the second adhesive layer to the substrate B, which may or may not be conductive.Without wishing to be bound by any particular theory, the inventors assume the following mechanism: the application of the voltage causes the electrolyte to migrate, in particular the anions and cations of an ionic liquid, in the adhesive layer D. This greatly reduces the adhesion of the adhesive layer D to the substrate A and the layers are dissolved from one another.According to preferred embodiments of the invention, xi.) only the carrier layer is electrically conductive. A voltage can be applied particularly well to this, in particular and preferably if the carrier layer laterally projects beyond at least one of the adhesive layers.According to further preferred embodiments of the invention, xii.) the carrier layer and the second adhesive layer C are electrically conductive. Such a structure has the advantage that the voltage can be applied to the adhesive layer C. A lateral protrusion of the carrier layer is not necessary. The adhesive tape can therefore be produced in a simple manner, in particular since the layers D, T and C can be punched together.The adhesive tape according to the embodiments described above preferably consists of the three layers D, T and C. For this purpose, the term three-layer composite D-T-C is also used in the context of the present application.According to preferred embodiments of the present invention, the bonded composite thus comprises the following layers:• a first substrate A which is electrically conductive; and• a second substrate B; and• An adhesive tape according to the invention which consists of the three-layer composite D-T-C and adheres the substrates A and B to one another in such a way that the adhesive layer D is bonded to the conductive substrate A.According to further preferred embodiments, 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 support layer T arranged between the layers D and C; and• at least one second electrically conductive carrier layer T' arranged on the surface of the adhesive layer D opposite the first electrically conductive carrier layer T; and• A third adhesive layer C' which is arranged on the surface of the second electrically conductive carrier layer T' opposite the first adhesive layer D.An adhesive tape of this kind has at least the layer structure C-T-D-T'-C' and can be adapted as a double-sided adhesive tape via the adhesive layer C and C' to a multiplicity of different substrates.These may in principle be the same substrates as in the preceding embodiments, in which the adhesive tape is a transfer adhesive tape or has the three-layer structure D-T-C.Such an adhesive tape can be used in particular and advantageously, however, also to later separate substrates A and B from one another, none of which is electrically conductive.According to preferred embodiments, either 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 configured to be electrically conductive.As a result, a voltage at xi.) can be applied to the two electrically conductive carrier layers or xii.) to at least one of the adhesive layers C and C' and to one of the carrier layers or the other adhesive layer.Analogously to the above embodiments, it is assumed that the application of the voltage results in the electrolyte migrating, in particular a separation of the anions and cations of an ionic liquid, in the adhesive layer D. As a result, the adhesion of the adhesive layer D to the electrically conductive carrier layers T and T' is greatly reduced and these layers are separated from one another.According to preferred embodiments of the invention, xi.) only the carrier layers T and T' are electrically conductive. A voltage can be applied particularly well to this, in particular and preferably if the carrier layers T and T' project laterally beyond at least one of the respectively adjacent adhesive layers.According to further preferred embodiments of the invention, xii.) the carrier layers T and T' and the second and third adhesive layer C and C', respectively, are electrically conductive. Such a construction has the advantage that the voltage can be applied to the adhesive composition layers C and C'. A lateral protrusion of the carrier layers T and T' is not necessary. The adhesive tape can therefore be produced in a simple manner, in particular since the layers C, T, D, T' and C' can be punched together.The adhesive tape according to the embodiments described above preferably consists of the five layers C, T, D, T' and C'. For this purpose, the term five-layer composite C-T-D-T'-C' is also used in the context of the present application.According to preferred embodiments of the present invention, the bonded composite thus comprises the following layers:• a first substrate A; and• a second substrate B; and• An adhesive tape according to the invention which consists of the five-layer composite C-T-D-T'-C' and bonds the substrates A and B to one another.The electrically conductive substrate of all embodiments may be, for example, a metal housing of a mobile phone.The electrically non-conductive substrate of all embodiments can be, in particular, a housing made of a non-conductive material, such as plastic, or a battery or other components configured to be non-electrically conductive, such as loudspeakers, for example.The present invention further provides for the use of the adhesive composition of the invention for bonding components in electronic devices, automobiles, medical devices and dental devices.The present invention further provides for the use of the adhesive tape of the invention for bonding components in electronic devices, automobiles, medical devices and dental devices.The carrier layers T as well as T and T' of all the above-mentioned embodiments are electrically conductive.These layers are further explained below. For the sake of simplicity, the term "electrically conductive carrier layer" or else only "carrier layer" is used. Depending on the above embodiments, this relates to the carrier layer T or the carrier layers T and T'.The carrier layers T and T' are independent of one another and can be embodied identically or differently from one another.The electrically conductive carrier layer preferably comprises at least one metal.According to preferred embodiments of the invention, the metal is selected from the group consisting of copper, nickel, zinc, tin, silver, gold, aluminum, iron, chromium and alloys of these mentioned metals. The metal is very particularly preferably selected from the group consisting of aluminum, zinc, copper and nickel. Aluminum is very preferred.The electrically conductive carrier layer preferably has a layer thickness, measured in the z direction, i.e. parallel to the stacking direction of the layer arrangement, of 10 nm (nanometers) to 50 μm (micrometers).According to preferred embodiments of the invention, the electrically conductive carrier layer has a) at least one metal foil, preferably an aluminum foil, and / or b) at least one electrically conductive textile having at least one metal, preferably selected from the group consisting of copper and nickel, and / or c) one or more layers of at least one vapor-deposited metal, preferably selected from the group consisting of copper and aluminum, and / or d) at least one grid of metal and / or e) a metal-vapor-deposited foil.It is also conceivable in principle for the layer T to have a combination of two or more of the possibilities mentioned.Metal foils, such as, for example and preferably, aluminum foils, are known to the skilled person. The metal foil, for example and preferably the aluminum foil, preferably has a layer thickness, measured in the z direction, i.e. parallel to the stacking direction of the layer arrangement, of 5 to 50 μm, particularly preferably of 10 to 30 μm.Electrically conductive textiles are known to the person skilled in the art, in particular under the English term "conductive mesh". This is a textile fabric, for example made of PET (polyethylene terephthalate), which is coated with a metal, for example copper and / or nickel, as a result of which the electrical conductivity of the fabric is produced.The skilled worker is likewise aware that metals can be vapor-deposited directly as a monolayer or multilayer on surfaces, such as here the surface of an adhesive layer. In the context of the present invention, the electrically conductive backing layer can be provided by vapor deposition of metal onto the adhesive layer D or the adhesive layer C or the adhesive layer C'.Furthermore, grids made of metal of different dimensions are known to the person skilled in the art. Metal grids with suitable layer thicknesses can be produced, for example, by a laid scrim of appropriately thin metal threads or by punching at least one foil of appropriate layer thickness.In the case of a metal-vapor-deposited film, a non-conductive film is in particular vapor-deposited with metal in order to form it electrically conductive. The material of the film can in principle be selected from all materials which are suitable for being vapor-deposited with metal and for being used as carrier film in adhesive tapes. The material is selected in particular from polyesters and polyolefins, wherein a mixture of a plurality of materials is also conceivable. Preferred polyesters are, in particular, polyethylene terephthalate (PET) and polyethylene naphthalate (PEN). Polypropylene (PP), polyethylene (PE) are particularly preferred polyolefins. According to preferred embodiments, the material of the film is selected from the group consisting of PET, PEN, PE, PP. It is preferably a film made of PET (polyethylene terephthalate). Such a film is dimensionally stable and thus is highly processable without significantly stretching or tearing. This makes it possible to apply a homogeneous and gapless metal layer permanently, so that the electrical conductivity, in particular in the z direction, is permanently ensured over the entire film.In the embodiments in which at least one electrically conductive carrier layer T or at least two electrically conductive carrier layers T and T' are present, it is preferred that these laterally project beyond at least one adjacent adhesive layer in at least one direction of extent of the layer plane and thus have a lateral projection. A voltage can then be applied to this lateral protrusion in a simple manner.In the case of the five-layer composite, the lateral protrusions of the electrically conductive carrier layers T and T' are arranged spatially separated from one another according to advantageous embodiments. This makes it easier to apply a voltage to these two protrusions.In the case of vapor-deposited metal as carrier layer, it is preferred that this carrier layer laterally projects only beyond an adjacent adhesive layer in at least one direction of extent of the layer plane and the respective other adhesive layer serves as mechanical support for this metal layer. In this case, the metal layer does not have any actual carrier function. Instead, the other adhesive layer functions as a carrier for the metal layer. For the sake of simplicity, the term carrier layer for the metal layer is, however, also retained in these embodiments. In this case, the layer thickness of the layer T is preferably greater than or equal to 10 nm (nanometers), preferably 50 to 200 nm.According to preferred embodiments of the invention, the electrically conductive carrier layer T or T and / or T'a) has at least one metal foil, preferably an aluminum foil, and / or b) has at least one electrically conductive textile having at least one metal, preferably selected from the group consisting of copper and nickel, and / or d) has at least one grid of metal and / or e) has a metal-vapor-deposited foil, and projects 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' in at least one direction of extent.As a result, a voltage can be applied to the carrier layer in a simple and reliable manner. At the same time, the adhesive tape can be produced in a comparatively simple manner.According to preferred embodiments of the invention, the electrically conductive carrier layer T or T and / or T' has one or more layers, preferably one layer, of at least one vapor-deposited metal, preferably selected from the group consisting of copper and aluminum.According to particularly preferred embodiments of the invention, the electrically conductive carrier layer T or T and / or T'e) has a film vapor-deposited with metal, and projects beyond the first adhesive layer D in at least one direction of extent. In this case, the film is in particular vapor-deposited with metal on one surface and the respective carrier layer is bonded via the metallized surface to the first adhesive layer D, and thus to the electrically removable layer.As a result, a voltage can be applied to the carrier layer in a simple and reliable manner.The term "laterally projecting" in the context of the present invention means any type of lateral projecting part of the layer or layers mentioned and means that the layer mentioned in each case extends further than the reference layer in particular in the "xy" plane and thus laterally-perpendicular to the stacking direction. Instead of the term "lateral protrusion", the terms "lateral extension" or "lateral extension section" are also used within the scope of the present invention.The term "lateral" refers here to any direction of extent of the layer plane "xy" perpendicular to the stacking direction of the layers "z". The term is thus in particular independent of the geometric shape of the adhesive tape in the "xy" plane, which can be, for example, a rectangle, as is customary for adhesive tapes (see above), but also a square or a circle.Slight variations in the dimensions of the individual layers in the "xy" plane, which arise due to the punching process or similar shaping processes, are not addressed with this, in particular since such slight material elevations are not suitable, due to the dimensions, for applying a voltage to them on a plan basis.The adhesive layers C or C and C' can in principle be based on the same compositions as the adhesive layer D, but the adhesives of the layers C or C and C' need not contain electrolytes. The layers C or C and C' preferably contain no electrolytes.According to some embodiments of the three-layer composite D-T-C described above, the adhesive layer C is electrically conductive.Likewise, the adhesive layer C and / or the adhesive layer C' of the five-layer composite C-T-D-T'-C' can also be configured to be electrically conductive.These layers are further explained below. For the sake of simplicity, the term "electrically conductive adhesive layer" is used at suitable points. Depending on the above embodiments, this relates to the adhesive layer C or the adhesive layers C and / or C'. For the sake of simplicity, the expression "the adhesive layers C or C and / or C'" is also used, meaning the respective layers in the described embodiments of the adhesive tape comprising at least the three-layer composite or at least the five-layer composite.The adhesive layers C and C' are independent of one another and may be identical to or different from one another.For this purpose, the electrically conductive adhesive layer preferably comprises at least one metal, such as in particular nickel, copper, silver, preferably in the form of electrically conductive metal particles and / or metallized particles, particularly preferably metal particles. Metallized particles are in particular and preferably glass or polymer particles which are metallized with at least one metal, so that the particles which were not electrically conductive beforehand are configured to be electrically conductive by the metallization.The electrically conductive adhesive composition layer particularly preferably comprises electrically conductive particles selected from the group consisting of nickel particles, copper particles and silvered copper particles.According to particularly preferred embodiments, the electrically conductive adhesive layer comprises nickel particles.The electrically conductive adhesive composition layer preferably comprises 5 to 40% by weight, more preferably 20 to 40% by weight, very preferably 25 to 35% by weight, of electrically conductive particles, in particular metal particles and / or metallized particles, based on 100% by weight, based on 100% by weight, of polymers and tackifier resins present.The electrically conductive particles should preferably not be, or should not be significantly, greater than the respective thickness of the electrically conductive adhesive layer in the z direction, measured with the light microscope.The electrically conductive particles preferably have an average particle size of 1 to 10 μm, particularly preferably of 1 to 6 μm, again preferably of 3 to 5 μm, such as in particular 4 μm.The electrically conductive adhesive layer is electrically conductive in particular 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, a smaller amount of these materials is necessary according to preferred embodiments in which a metal, in particular metal particles, is added in order to achieve the electrical conductivity. This optimizes the adhesive with regard to required conductivity, bond strength, flow behavior and costs.In the context of the present invention, a layer is considered to be "electrically conductive" in particular when the resistance is less than 1 ohm, measured in the respective direction, here in particular in the z direction, according to the standard MIL-DTL-83528C.Regardless of whether the adhesive layers C or C and / or C' are electrically conductive, the following statements apply.The adhesive of adhesive layers C or C and / or C' is, in preferred embodiments, not a pressure-sensitive adhesive.According to particularly preferred embodiments of the invention, the adhesive of the adhesive layers C or C and C' is a pressure-sensitive adhesive and the adhesive layer C or C and C' is thus a pressure-sensitive adhesive layer.According to preferred embodiments of the invention, adhesive layers C or C and / or C' are, like adhesive layer D, adhesives based on at least one polydiene block copolymer and at least one tackifier resin.According to preferred embodiments of the invention, the same polydiene block copolymer and the same tackifier resin as in adhesive layer D are used in adhesive layers C or C and / or C'.In this way, in particular similar substrates, referred to here as A and B, can be bonded to one another.According to further preferred embodiments of the invention, an adhesive different from the adhesive of adhesive layer D is used in adhesive layers C or C and / or C'.As a result, the properties of the conductive layer can be adapted particularly well to the substrate or substrates which is bonded via the adhesive layer C or C and / or C'. Because adhesive layer C or C and / or C' preferably does not contain or must contain an electrolyte, such as an ionic liquid, the constituents do not have to be matched to this.According to preferred embodiments of the invention, an adhesive different from the adhesive of the adhesive layer D is used in the adhesive layers C or C and / or C', it being possible for the adhesive of the adhesive layers C or C and / or C' to be heat-activatable or to be an acrylate-based PSA.The adhesive of adhesive layer D and, depending on the embodiment, further adhesives are produced by known processes and are brought into layer form, in particular by spreading. This can be done using one or more suitable solvents or else solvent-free.Furthermore, one or more drying steps can optionally be carried out. However, the production of adhesives according to the invention preferably takes place without solvents by extrusion, which is a further advantage of the present invention. In this way, even in the production of adhesives and adhesive layers according to the invention, the degree of sustainability can be further increased in addition to the later possibility of redetachment by avoiding the use of solvent.The lamination of a plurality of layers onto one another is carried out in a manner known to the person skilled in the art, wherein the layers are placed one on top of the other in such a way that in particular a layer composite DTC, wherein T is arranged between D and C, or C'-T'-D-T-C is obtained as double-sided adhesive tape.The provision of the carrier layers T or T' can be effected in various ways, as already explained above.It is thus conceivable for a) a metal foil, in particular an aluminum foil, and / or b) an electrically conductive mesh, and / or d) at least one grid of metal and / or e) a PET foil vapor-coated with metal to be placed between the respective adhesive layers.Furthermore, c) metal particles can be vapor-deposited directly on the surface of the adhesive layer D or C or C'.The adhesive tape of the invention is in particular a double-sided adhesive tape in which, depending on the embodiment, two surfaces of the adhesive layer D (transfer adhesive tape) or one surface of the first adhesive layer D and one surface of the second adhesive layer C (three-layer composite D-T-C) or in each case one surface of the adhesive layers C and C' (five-layer composite C-T-D-T'-C') are available in each case for bonding substrates.Advantageously, the outer, exposed surfaces of the adhesive layers of the adhesive tape of the invention may be provided with antiadhesive materials, such as with a release paper or a release film, also referred to as a liner. A liner can also be an anti-adhesively coated material at least on one side, preferably on both sides, such as material siliconized on both sides, for example. A liner, or more generally a temporary carrier, is not part of an adhesive tape, but only an aid for its production, storage and / or further processing by punching. Moreover, a liner, unlike a permanent backing, is not firmly bonded to an adhesive layer, but rather functions as a temporary backing, i.e., a backing that is peelable from the adhesive layer. "Permanent backings" are also interchangeably referred to herein as "backings.".The thickness of the individual adhesive layer(s) (in the z direction) is preferably from 15 to 2000 μm, particularly preferably from 20 to 500 μm, very particularly preferably from 25 to 200 μm. However, as small a thickness as possible is preferred, for example, below 100 μm.In the embodiments of the three-layer composite D-T-C and of the five-layer composite C-T-D-T'-C', the adhesive layers D and C or D and C and D and C' according to preferred embodiments have different layer thicknesses, the thickness of the adhesive layer D being, for example, less than that of the adhesive layers C or C and C'.According to further preferred embodiments, the layers D and C or D, C and C' have the same layer thickness.If the layer thickness of the layer D is too high, this may be uneconomically expensive because of the electrolytes contained.In order, if desired, to increase the anchoring of the adhesive layer or layers on a carrier layer, the carrier layer may be chemically and / or physically pretreated, in particular physically pretreated. Corona, plasma or flame pretreatment are conceivable. Surface treatment by corona, also for metallized films, is known to the person skilled in the art and is described, for example, in EP 0355622 A2.Preferred embodiments of the invention are explained and described in more detail below with reference to the enclosed figures. The following are shown: FIG. 1 shows a simplified schematic cross-sectional illustration through a double-sided adhesive tape according to the invention in a preferred embodiment; and FIG. 2 shows a simplified schematic cross-sectional illustration through a double-sided adhesive tape according to the invention in a preferred embodiment; and FIG. 3 shows a simplified schematic cross-sectional illustration through a double-sided adhesive tape according to the invention in a preferred embodiment; and FIG. 4 shows a simplified schematic cross-sectional illustration through an inventive bonded composite of a preferred embodiment; and FIG. 5 shows a simplified schematic cross-sectional illustration through an inventive bonded composite to which a voltage is applied, in a preferred embodiment; and FIG. 6 shows a simplified schematic cross-sectional illustration through an bonded composite according to the invention after a voltage has been applied and as a result adhesive cleavage has taken place; and FIG. 7 shows a simplified schematic cross-sectional illustration through an inventive bonded composite of a preferred embodiment; and FIG. 8 shows a simplified schematic cross-sectional illustration through an inventive bonded composite of a preferred embodiment.As can be seen in FIG. 1, the adhesive layer D 1 is connected via one of its surfaces to the carrier layer T 2. On the surface of the carrier layer T opposite the layer D, the second adhesive layer C 3 is arranged.As is likewise evident in FIG. 1, the layer composite represents a double-sided adhesive tape in which one area of the adhesive layer D and one area of the second adhesive layer C are each available for bonding.Referring now to Fig. 2, there is shown a preferred embodiment of the invention. In this case, the electrically conductive carrier layer T 2 projects laterally beyond the adhesive layer D 1 and the second adhesive layer C 3 in at least one direction of extent of the layer plane, such that the electrically conductive carrier layer T 2 has a projection with at least one free surface 2 a.In Fig. 3 a further preferred embodiment of the invention is shown. In this case, the electrically conductive carrier layer T 2 protrudes laterally beyond the adhesive layer D 1 in at least one direction of extent of the layer plane, such that the electrically conductive carrier layer T 2 has a protrusion with a free surface 2 a. In FIG. 3, the adhesive layer C 3 is formed such that it likewise has a protrusion relative to the layer D 1. The carrier layer T 2 is in particular a PET film coated on one side with aluminum, the aluminated side being bonded to the layer D 1.FIG. 4 shows a schematic illustration of the bonded composite according to the invention in a preferred embodiment. As can be seen from FIG. 4, the adhesive tape is arranged on one surface of the first substrate A 4 via the adhesive layer D 1, the first substrate being electrically conductive.Furthermore, the adhesive tape is arranged on one surface of a second substrate B 5 via the second adhesive layer C 3.In FIG. 4, it is likewise shown by way of example that the electrically conductive carrier layer T 2 laterally projects beyond the adhesive layer D 1 in at least one direction of extent of the layer plane, such that the electrically conductive carrier layer T has a projecting length with a free surface 2 a.A voltage can now be applied across this free area 2a, as shown in the schematic illustration according to FIG. 5.The application of the voltage results in the electrolyte migrating, in particular a separation of the anions and cations of an ionic liquid, in the adhesive layer D1.As a result, the adhesion of the adhesive layer D1 to the substrate A4 is greatly reduced and these layers are released from one another, as can be seen from the schematic illustration according to FIG. 6.FIG. 7 shows a further schematic illustration of the bonded composite according to the invention in a preferred embodiment. As can be seen from FIG. 7, the adhesive tape is arranged on one surface of the first substrate A 4 via the adhesive layer C 3.Furthermore, the adhesive tape is arranged on one surface of a second substrate B 5 via the third adhesive layer C' 7.Between the layers C3 and C' 7 are the electrically detachable adhesive layer D1 and two electrically conductive carrier layers T2 and T' 6, the layer D1 being arranged between the carrier layers.In FIG. 7, it is likewise shown by way of example that the electrically conductive carrier layer T2 and the electrically conductive carrier layer T' 6 project laterally beyond the adhesive layer D1 in each case in at least one direction of extent of the layer plane, with the result that the electrically conductive carrier layer T has a projection with a free surface 2a and the electrically conductive carrier layer T' has a projection with a free surface 6a.FIG. 8 shows a further schematic illustration of the bonded composite according to the invention in a preferred embodiment, which is similar to the illustration according to FIG. 7. In contrast to FIG. 7, however, 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 surfaces of these layers 2a and 6a are spatially separated.A voltage can now be applied across these free surfaces 2 aand 6 a, analogously to FIG. 5. In contrast to the embodiment according to FIG. 5, the voltage can be applied to the surfaces 2 aand 6 a, so that none of the substrates A and B must be electrically conductive.The application of the voltage causes the electrolyte to migrate, in particular the anions and cations of an ionic liquid are separated, in the adhesive layer D1. As a result, the adhesion of the adhesive layer D1 to the carrier layers T2 and / or T' 6 is greatly reduced and these layers are dissolved from one another. In particular, detachment takes place at the layer to which the negative pole is applied.The application of the voltage is simplified in the case of the spatially separated surfaces 2a and 6a according to Fig. 8.The representations in FIGS. 1 to 8 are schematic representations as explained. In particular, the layer thicknesses of the individual layers D, T and C may deviate from one another. Furthermore, the substrates A and B are also only schematically shown as further layers. These may of course have any other spatial geometry.Some examples are described below to further illustrate the invention.Test MethodsAll measurements are carried out at 23° C. and 50% relative humidity, unless otherwise stated. The mechanical and adhesive data were determined as follows:Test I - Molecular Weight (GPC)(a) Peak Molar Mass of Individual Block Copolymer ModesPolymers are polymodal systems with respect to the molar mass distribution. Mixtures of different polymers can be understood as multimodal systems, each polymer introducing its own molar mass distribution. Mixtures of block copolymers having structures of different molar mass distributions can likewise be regarded as multimodal systems. Each block copolymer then introduces its own molecular weight distribution. For simplicity, these are referred to herein as block copolymer mode.GPC (gel permeation chromatography) is a metrological method for determining the molar mass of individual polymer modes in mixtures of different polymers. For the block copolymers prepared by living anionic polymerization which can be used in the context of this invention, the molar mass distributions are typically sufficiently narrow, such that polymer modes which can be assigned to triblock copolymers, diblock copolymers or multiblock copolymers occur sufficiently resolved from one another in the elution. The peak molar mass for the individual polymer modes can then be read from the elugrams.Peak molar masses (peak MM) of elastomers are determined by GPC. THF is used as the eluent. The measurement is carried out at 23° C. The precolumn used is PSS-SDV, 5 μ, 10 3 Å, ID 8.0 mm×50 mm. For separation, the columns PSS-SDV, 5 μ, 10 3 Å and 10 4 Å and 10 6 Å, each having ID 8.0 mm×300 mm, are used. The sample concentration is 4 g / l, the flow rate 1.0 ml per minute. The calibration is carried out by means of the commercially available ReadyCal kit poly(styrene) high from PSS Polymer Standard Service GmbH, Mainz (μ=μm; 1 Å=10 -10 m).(b) Weight-average molar massThe weight-average molecular weight M w of tackifier resins, plasticizers and enhancers is determined by means of GPC. THF is used as the eluent. The measurement is carried out at 23° C. The precolumn used is PSS-SDV, 5 μ, 10 3 Å, ID 8.0 mm×50 mm. For separation, the columns PSS-SDV, 5 μ, 10 3 Å and 10 4 Å and 10 6 Å, each having ID 8.0 mm×300 mm, are used. The sample concentration is 4 g / l, the flow rate 1.0 ml per minute. The calibration is carried out by means of the commercially available ReadyCal kit poly(styrene) high from PSS Polymer Standard Service GmbH, Mainz.Test II - DSCGlass transition points are synonymous with glass transition temperatures-in particular of polymers or polymer blocks-are specified as a result of measurements by means of dynamic differential calorimetry DDK (dynamic scanning calorimetry; DSC) in accordance with DIN 53 765, in particular sections 7.1 and 8.1, but with uniform heating and cooling rates of 10 K / min in all heating and cooling steps (compare DIN 53 765; section 7.1; note 1). The sample weight is 20 mg. The melting temperature or softening temperature of polymers or polymer blocks is also determined in this way.Test III - (tackifier resin) heat release temperatureFor individual substances: The (tackifier) resin softening temperature (softening point; first point) is carried out according to the relevant methodology known as Ring & Ball and standardized according to ASTM E28.Test IV - Melt ViscosityTo determine the melt viscosity of the soft resins, a shear stress sweep is carried out in a shear stress-controlled DSR 200 N rheometer from Rheometrics Scientific in rotation. A cone / plate measurement system with a diameter of 25 mm (cone angle 0.1002 rad) is used, the measurement head is air-mounted and suitable for normal force measurements. The gap is 0.053 mm and the measurement temperature is 25° C. The frequency is varied from 0.002 Hz to 200 Hz and the melt viscosity is recorded at 1 Hz.Test V - Bond strength steelThe determination of the bond strength is carried out as follows. A polished steel plate (ASTM D3330; cleaned three times with acetone with a cellulose cloth and evaporated for 10 min) having a thickness of 2 mm is used as the defined adhesion base. Unless otherwise stated, the adhesive sheet to be examined is cut to a width of 20 mm and a length of about 25 cm, provided with a handling section and immediately thereafter pressed back and forth five times onto the adhesive base with a steel roll of 4 kg at a feed rate of 10 m / min. Immediately thereafter, the adhesive surface element is removed at an angle of 180° from the adhesion base using a tensile tester (Zwick company) at a speed v=300 mm / min, and the force required for this purpose at room temperature is measured. The measured value (in N / cm) is obtained as an average value from two individual measurements.Test VI - ThicknessThe thickness of an adhesive layer can be determined by determining the thickness of a portion, defined with respect to its length and its width, of such an adhesive layer applied to a liner, minus the (known or separately determinable) thickness of a portion of the same dimensions of the liner used. The thickness of the adhesive layer can be determined with precisions of less than 1 μm deviation using commercially available thickness measurement devices (probe testing devices). If thickness variations are detected, the mean value of measurements is given at at least three representative points, i.e. in particular not measured at creases, folds, specks and the like.As already the thickness of an adhesive layer, the thickness of an adhesive tape (adhesive strip) or of a carrier can also be determined analogously by means of commercially available thickness measurement devices (probe testing devices) with precisions of less than 1 μm deviation. If thickness variations are detected, the mean value of measurements is given at at least three representative points, i.e. in particular not measured at creases, folds, specks and the like.The following example according to the invention for an adhesive according to the invention and also adhesive tapes comprising at least one adhesive layer D of an adhesive according to the invention was produced in the form of a transfer adhesive tape, bonded between substrates and subsequently electrically redissolved by application of a voltage.Inventive Example 1The adhesive composition and the transfer adhesive tape produced therefrom were provided as follows: 30% Kraton D1152 ES (15% diblock, polystyrene content: 29%, linear SBS), 13% Kraton D116 AT (PS 23%, diblock 16%, radial SBS), 23% Dercolyte A115 (tackifier resin, EP: 115° C., alpha-pinene) 30% Foral 105 (tackifier resin, EP 105° C., hydrogenated pentaerythryte rosin, high polarity), 3% Wingtack 10 (plasticizer resin, EP 10° C., fl. C5 resin), 0.5% Irganox 1010 (primary anti-ageing agent), 0.5% Irgafos 168 (secondary anti-ageing agent) were added with solvent (e.g. acetone, boiling point spirit 60 / 95, toluene) and mixed with one another until a homogeneous solution was obtained. The data in % represent percent by weight, based on the total weight of the base composition consisting of the stated constituents without solvent. The total concentration of the pressure-sensitive adhesive in the solvent is 35% by weight.Subsequently, 7% by weight of 1-ethyl-3-methylimidazolium tetrafluoroborate and 3.5% by weight of polyethylene glycol 400 were added, these amounts being based on 100% by weight of the base composition prepared above.The solution was coated by means of a comma doctor onto a layer of a siliconized polyester carrier (siliconized liner) and subsequently freed of solvent for 15 minutes at 120° C. in a drying cabinet. Until further use, the open side of the PSA was covered with a further layer of a siliconized polyester carrier (siliconized liner).After drying, the layer thickness of the PSA layer was 50 μm.A siliconized liner was removed. The exposed side of the PSA was then laminated onto the aluminated side of an aluminum-vapor-deposited PET film having a total thickness of 23 μm, giving a lateral protrusion of 4 cm from the PSA. The aluminated side of the foil was co-grained immediately before lamination (dose of 30 W*min / m 2).The sample was stored at 23° C. and 50% relative humidity for 24 hours.Subsequently, the adhesive force was determined according to the above-mentioned method. It was 7.1 N / cm.A corresponding comparative composition V1 was likewise prepared without the addition of 7% by weight of 1-ethyl-3-methylimidazolium tetrafluoroborate and 3.5% by weight of polyethylene glycol 400, but otherwise in an identical manner, and tested for its adhesive strength by the above method. The bond strength here was 9.3 N / cm.For testing the electrical releasability, samples of the abovementioned inventive example 1, i.e. including the addition of 7% by weight of 1-ethyl-3-methylimidazolium tetrafluoroborate and 3.5% by weight of polyethylene glycol 400, were prepared again in accordance with the instructions described above and tested for the electrical releasability.Here too, the exposed side of the PSA was laminated onto the aluminated side of an aluminum-vapor-deposited PET film having a total thickness of 23 μm, resulting in a lateral protrusion of 4 cm from the PSA.Subsequently, a voltage was applied, a first crocodile clamp (clamping jaws insulated externally with rubber) being applied with the positive pole to the protrusion and a second being applied with the negative pole to the steel plate.The voltage was 12 V and was applied for 1 min.After 1 minute elapsed, the stress was removed and, immediately thereafter, the adhesion force was determined according to the above-mentioned method.The bond strength was only 4.9 N / cm.The steel plate was residueless with respect to adhesive residues.It has thus surprisingly been possible to produce an adhesive layer based on a polydiene block copolymer in an electrically detachable manner and without leaving any residue.As the tests for bond strength and redetachability show in Example 1 according to the invention, the bond strength of the adhesive layer D to substrates, such as steel, before the application of the voltage is high and is only reduced to such a low value by the application of the voltage, so that the substrates can be separated from one another more easily.List of reference characters1 Adhesive layer D2 Electrically conductive carrier layer T2a Free area of electrically conductive carrier layer T3 Second adhesive layer C4 First substrate A5 Second substrate B6 Second electrically conductive carrier layer T' 6a Free area of electrically conductive carrier layer T' 7 Third adhesive layer C'References included in the specificationThis list of documents cited by the applicant has been produced in an automated manner and is only included for the better information of the reader. The list is not part of the German patent application or utility model application. The DPMA does not take any adhesion for any faults or omissions.Patent Literature citedEP 3031875 B1 [0006, 0016]EP 0355622 A2

[0228] Cited Non-Patent LiteratureWikipedia entry "Electrolyte" of 04.01.2023

[0021] N. Hadjichristidis, M. Pitsicalis, S. Pispas, H. latrou, Chem. Rev.,2001, 101, 3747-3792

[0047] R. P. Quirk in Thermoplastic Elastomers, G. Holden, G. H. Kricheldorf, R. P. Quirk (Ed.), 3rd Ed., 2004, C. Hanser, Munich, pp. 71-75

[0047]

Claims

PSA comprising at least one electrolyte and a base composition, where the base composition comprises at least one polydiene block copolymer and at least one tackifier resin.Pressure-sensitive adhesive according to Claim 1, characterized in that the electrolyte is selected from the group consisting of ionic liquids and metal salts, particular preference being given to ionic liquids.The PSA according to claim 2, wherein the anion of the ionic liquid is selected from the group consisting of Br -, AlCl 4-, Al 2 Cl 7-, NO 3-, BF 4-, PF6 -, CH 3 COO -, CF 3 COO-, CF3CO3NER18_, CF3SO3NER21_, (CF3SO2)2N-, (cf_ner26_so_ner27_)_ner28_C -, AsF6 -, SbF6 -, CF 3( CF 2)3 SO 3-, ( CF 3 CF 2 SO 2)2 N -, CF3CF2CF2COO-, (FSO2)2N-, and particularly preferably selected from (CF 3 SO 2)2 N - and (FSO 2)2 N -, and / or 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, and particularly preferably selected from the group consisting of imidazolium-based cations, wherein the cation is particularly preferably selected from the group consisting of 1-ethyl-3-methylimidazolium and 1-butyl-3-methylimidazolium, wherein the cation is very particularly preferably 1-ethyl-3-methylimidazolium.Pressure-sensitive adhesive according to one of the preceding claims, characterized in that the electrolyte is 1-ethyl-3-methylimidazolium tetrafluoroborate.Pressure-sensitive adhesive according to any of the preceding claims, characterized in that it comprises from 2 to 10% by weight, preferably from 4 to 9% by weight, of electrolytes, preferably ionic liquids, based on 100% by weight of the base composition.Pressure-sensitive adhesive according to any of the preceding claims, characterized in that the at least one polydiene block copolymer is a polyvinylaromatic polydiene block copolymer, preferably a polystyrene-polydiene block copolymer.The PSA according to any of the preceding claims, characterized in that it comprises at least one compatibilizer selected from the group consisting of polyethers, polyamines, polyvinylpyrrolidones or aliphatic polyesters, where the compatibilizer preferably has a weight average molecular weight distribution M w of from 100 to 5000 g / mol, more preferably from 200 to 2000 g / mol.Pressure-sensitive adhesive according to one of the preceding claims, characterized in that the tackifier resin is selected from the group consisting of rosins and terpene-phenol resins, particular preference being given to a hydrogenated resin based on a pentaerythrite esterified with rosin.Adhesive tape comprising at least one adhesive layer D of an adhesive according to any of Claims 1 to 8,Adhesive tape according to Claim 9, characterized in that the adhesive tape is a transfer adhesive tape and consists of the adhesive layer D.Adhesive tape according to Claim 9, characterized in that it additionally comprises at least the following layers: • a second layer of adhesive C; and • at least one electrically conductive backing layer T arranged between the layers D and C.Adhesive tape according to Claim 9, characterized in that it additionally comprises at least the following layers: • a second layer of adhesive C; and • at least one first electrically conductive backing layer T arranged between the layers D and C; and • at least one second electrically conductive backing layer T' arranged on that surface of the layer of adhesive D which is opposite the first electrically conductive backing layer T; and • a third layer of adhesive C' arranged on that surface of the second backing layer T' which is opposite the first layer of adhesive D.Bonded composite comprising at least the following layers: • A first substrate A; and • A second substrate B; and • An adhesive tape according to one of Claims 9 to 12, which is arranged between the substrate A and the substrate B and bonds the substrates A and B to one another.Method for the electrical detachment of the composite according to Claim 13, comprising at least the following method steps: i.) applying a voltage at two different points of the composite, the voltage preferably being from 2 to 50 V.Use of the adhesive composition according to any of Claims 1 to 8 for bonding components in electronic devices, automobiles, medical devices and dental devices.

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