Pressure-sensitive adhesive, adhesive tape, adhesive composite and electrical separation method for adhesive composite

Abstract

The invention relates to a pressure-sensitive adhesive, an adhesive tape, an adhered composite, an electrical separation method for an adhered composite, and the use of the adhesive for adhering components in electronic, automotive, medical and dental devices. The pressure-sensitive adhesive comprises at least one electrolyte and a base material, wherein the base material comprises at least one polydiene block copolymer and at least one tackifying resin.

Description

Technical Field

[0001] The invention relates to a pressure-sensitive adhesive, an adhesive tape, a bonded composite, a method for electrical separation of a bonded composite, and the use of the adhesive for bonding components in electronic devices, automobiles, medical devices and dental devices. Background Art

[0002] Recently, there has been a growing interest in "debonding on demand" capabilities, which is due to environmental laws or end-customer awareness of sustainability and increasing cost pressure in the manufacturing industry. The application scenarios of the debonding process are divided into rework (post-processing), repair, recycling and processing assistance.

[0003] Debonding techniques aim to achieve either cohesive splitting of the adhesive layer or adhesive separation of the adhesive layer from the substrate. The former requires cleaning of the substrate prior to rebonding, while the latter does not require such cleaning.

[0004] However, adhesive separation techniques that guarantee the required high and permanently reliable adhesion are often more difficult to implement or require a long time in application, such as stripping with the aid of penetrating solvents.

[0005] At present, in particular in the rework or repair of electronic devices such as smartphones and tablets, mainly cohesive-splitting adhesive compounds (usually designed as pressure-sensitive tapes) are used, which decrease in their cohesion with increasing temperature, so that manual cohesive separation of the bond can be carried out. The result is extensive rework for preparing the substrate surface contaminated with adhesive residues for bonding again.

[0006] In addition to thermally mediated separation processes, electrical separation methods have also been discussed. For example, EP 3031875 B1 discloses reducing the adhesion (bond strength) of acrylate adhesives by applying an electrical voltage.

[0007] However, especially to low-energy surfaces, acrylate adhesives often do not have sufficient adhesion. Summary of the invention

[0008] The object of the present invention is therefore to provide a pressure-sensitive adhesive which should also adhere well to substrates with low-energy surfaces and should also be able to be peeled off again from at least one substrate without difficulty. At the same time, the peeling off again should be carried out in a simple and clean manner as far as possible. A supplementary object is to provide corresponding advantageous adhesive tapes.

[0009] A further object is to specify a bonded composite and a method for re-separating the adhesive connection produced by the adhesive or adhesive tape.

[0010] Furthermore, it is an object of the present invention to provide the use of the provided adhesive or adhesive tape for bonding two or more substrates.

[0011] The above-mentioned object is achieved by the subject matter of the present invention defined according to the present invention. Preferred designs according to the present invention result from further developments according to the present invention and the following embodiments.

[0012] These embodiments, which are referred to as preferred below, are combined in particularly preferred embodiments with features of other embodiments, which are referred to as preferred. Therefore, it is very particularly preferred to combine two or more embodiments, which are referred to as particularly preferred below. It is also preferred that the features of one embodiment, which is referred to as preferred to a certain extent, are combined with one or more other features of other embodiments, which are referred to as preferred to a certain extent. Therefore, the combination of the individual features with each other is included in the present invention, and in this case also includes different levels of preference. Therefore, for example, the combination of the first feature, which is referred to as "preferred", with the second feature, which is referred to as "particularly preferred", is included in the present invention. Here, the subject matter, which is also referred to as being in the framework (scope) of "embodiment", also includes different levels of preference. The features of the preferred adhesive tapes, the bonded composites, and the uses and methods are derived from the features of the preferred pressure-sensitive adhesives. The features of the preferred bonded composites, uses and methods are also derived from the features of the preferred adhesive tapes.

[0013] The pressure-sensitive adhesive of the present invention comprises at least one electrolyte and a base material, wherein the base material comprises at least one polydiene block copolymer and at least one tackifying resin.

[0014] By means of the electrolyte contained, the adhesive can also be electrically separated (peeled off) by applying a voltage after bonding.

[0015] Surprisingly, it has been found that a pressure-sensitive adhesive comprising at least one polydiene block copolymer and at least one electrolyte can be electrically separated again from the bonded substrates in a simple and rapid manner without any difficulty by applying an electrical voltage, and at the same time the adhesion of the pressure-sensitive adhesive, even to substrates to be bonded having low-energy surfaces, is not negatively affected before separation.

[0016] Adhesives and methods for electrical separation or electrical reduction of adhesion are known in principle in the prior art. Thus, as mentioned above, EP 3031875 B1 discloses such an electrical method. The electrically separable adhesive is an adhesive based on acrylates.

[0017] However, it was unexpected that even pressure-sensitive adhesives comprising at least one polydiene block copolymer can be electrically separated after bonding and that the adhesion to the substrates to be bonded is not negatively affected before separation. In particular, it was unexpected that polydiene-based pressure-sensitive adhesives, which exhibit a nonpolar character due to a high proportion of hydrocarbon compounds, can be mixed with electrolytes in such a way that, on the one hand, attractive pressure-sensitive adhesive properties are obtained and, on the other hand, separation can be achieved by applying a voltage.

[0018] At the same time, separation is clean and convenient.

[0019] Hereinafter, the pressure-sensitive adhesive according to the present invention will be described in more detail.

[0020] The pressure-sensitive adhesive comprises a base substance and at least one electrolyte in an amount related to the amount of the base substance.

[0021] "Electrolyte" is understood here to mean a compound "which dissociates into ions in the solid, liquid or dissolved state and moves in a directed manner under the influence of an electric field", as listed under the Wikipedia entry "Electrolyte" on January 4, 2023.

[0022] Preferably, the electrolyte is selected from ionic liquids and metal salts, with ionic liquids being particularly preferred.

[0023] In particular, one or more ionic liquids as electrolytes make it possible to easily re-detach the adhesive tape without negatively affecting the adhesive properties of the adhesive tape. Ionic liquids have the advantage that they are well and evenly distributed in the polymer matrix of the adhesive and re-detach more quickly than with other electrolytes.

[0024] In addition, the components of ionic liquids are non-volatile, particularly at room temperature. Ionic liquids are also relatively thermally stable and are non-flammable and relatively chemically stable.

[0025] In the context of the present invention, ionic liquids are salts which are liquid at room temperature, ie 23° C. Ionic liquids accordingly comprise anions and cations.

[0026] Ionic liquids are therefore particularly suitable as electrolytes within the context of the separation method or electrical separation method according to the invention.

[0027] When a voltage is applied, anions move to the anode side and cations move to the cathode side. Without intending to be limited thereto, it can be mechanically assumed that this results in a reduction in the adhesion of the adhesive containing the ionic liquid to the at least one substrate, thereby achieving a cleavage of the adhesive bond between the adhesive and the at least one substrate.

[0028] In principle, all ionic liquids are suitable within the scope of the present invention.

[0029] The ionic liquid used within the scope of the present invention comprises at least one anion and at least one cation. Here, it is also conceivable that the ionic liquid comprises two or more types of anions and / or two or more types of cations. In addition, it is conceivable that two or more different ionic liquids are added to the adhesive or that the adhesive then comprises two or more different ionic liquids.

[0030] Preferably, the anion of the ionic liquid is selected from: Br - 、AlCl4 - 、Al2Cl7 - 、NO3 - 、BF4 - PF6 - 、CH3COO - CF3COO - CF3CO3 - CF3SO3 - 、(CF3SO2)2N - 、(CF3SO2)3C - 、AsF6 - 、SbF6 - CF3(CF2)3SO3 - (CF3CF2SO2)2N - 、CF3CF2CF2COO - 、(FSO2)2N - .

[0031] Particularly preferably, the anion is tetrafluoroborate (BF4 - ).

[0032] Thus, by applying a voltage, a particularly high reduction in the adhesive force and thus a particularly good electrical separability of the pressure-sensitive adhesive according to the invention or the adhesive tape according to the invention is achieved. In particular, with these anions, (re)separation is achieved particularly quickly and without residues.

[0033] 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.

[0034] Particularly preferably, the cation is selected from imidazolium-based cations.

[0035] Thus, by applying a voltage, a particularly high reduction in the adhesive force and thus a particularly good electrical separability of the pressure-sensitive adhesive according to the invention or the adhesive tape according to the invention is achieved. In particular, with these cations, (re)separation is achieved particularly quickly and without residues.

[0036] Very particularly preferably, the cation is selected from 1-ethyl-3-methylimidazolium and 1-butyl-3-methylimidazolium.

[0037] Again preferably, the cation is 1-ethyl-3-methylimidazolium.

[0038] Particularly preferably, the electrolyte is 1-ethyl-3-methylimidazolium tetrafluoroborate.

[0039] Thus, by applying a voltage, a particularly high reduction in the adhesive force and thus a particularly good electrical separability of the pressure-sensitive adhesive according to the invention or the adhesive tape according to the invention is achieved. In particular, with these cations, (re)separation is achieved particularly quickly and without residues.

[0040] It has proven to be particularly advantageous here if the pressure-sensitive adhesive according to the invention comprises at least one styrene-butadiene-styrene block copolymer (SBS) in combination with 1-ethyl-3-methylimidazolium tetrafluoroborate as electrolyte and preferably at least one tackifying resin selected from polar resins such as, in particular, rosin resins and terpene-phenol resins.

[0041] Preferably, the pressure-sensitive adhesive contains 2 to 10% by weight, particularly preferably 4 to 9% by weight, of an electrolyte, preferably an ionic liquid, based on 100% by weight of the base substance.

[0042] The use of electrolytes, in particular ionic liquids, in preferred or particularly preferred amounts of this type enables relatively rapid electrical separation, while at the same time the adhesion of the adhesive to, in particular, the at least one substrate is not negatively affected before separation.

[0043] The pressure-sensitive adhesive according to the present invention comprises a base substance, wherein the base substance comprises at least one polydiene block copolymer and at least one tackifying resin.

[0044] The pressure-sensitive adhesive according to the invention preferably comprises 80 to 95% by weight, preferably 85 to 95% by weight, very particularly preferably 85 to 92% by weight, of base substances, in each case based on the total mass of the pressure-sensitive adhesive.

[0045] The total amount of polydiene block copolymers in the base substance is preferably 35 to 65% by weight, preferably 38 to 60% by weight, very particularly preferably 40 to 55% by weight, based on the total weight of the base substance.

[0046] Preference is therefore given to pressure-sensitive adhesives according to the invention in which the base substance comprises 35 to 65% by weight, particularly preferably 38 to 60% by weight, very particularly preferably 40 to 55% by weight, of at least one polydiene block copolymer, based on the total weight of the base substance.

[0047] Preferably, the at least one polydiene block copolymer is a polyvinyl aromatic-polydiene block copolymer.

[0048] According to a preferred embodiment, at least one polyvinyl aromatic compound-polydiene block copolymer has ABA, (AB) n , (AB) n X or (ABA) n A structure of the form X, where

[0049] - the blocks A are independently of one another polymers formed by polymerization of at least one vinyl aromatic compound;

[0050] - the blocks B are independently of one another polymers formed by polymerization of one or more conjugated dienes having 4 to 18 carbon atoms (C atoms);

[0051] -X is a group (residue) of a coupling reagent or a multifunctional initiator; and

[0052] -n is an integer ≥ 2.

[0053] Coupling agents and polyfunctional initiators are known to the person skilled in the art, as described, for example, in N. Hadjichristidis, M. Pitsikalis, S. Pispas, H. Iatrou, Chem. Rev., 2001, 101, 3747-3792; RP Quirk in Thermoplastic Elastomers, G. Holden, GH Richeldorf, RP Quirk (Hrsg.), 3. Aufl., 2004, C. Hanser, München, pp. 71-75.

[0054] The polyvinyl aromatic-polydiene block copolymers preferably each comprise one or more rubbery blocks B (elastomeric blocks, soft blocks) and at least two glassy blocks A (hard blocks).

[0055] Particularly preferred in the embodiments described herein is at least one polyvinyl aromatic compound-polydiene block copolymer having an ABA, (AB)2X, (AB)3X or (AB)4X structure, wherein A, B and X are as defined above.

[0056] Preferably, the base material comprises at least one triblock copolymer or a higher multiblock copolymer, which may be linear or multiarmed, for example radial or star-shaped.

[0057] Preference is given to polyvinyl aromatic compound-polydiene block copolymers having a peak molar mass of at least 90 000 g / mol, more preferably at least 120 000 g / mol, based on the totality of all polyvinyl aromatic compound-polydiene block copolymers in the base material. Preferably, the peak molar mass of the polyvinyl aromatic compound-polydiene block copolymer used does not exceed 300 000 g / mol, particularly preferably does not exceed 250 000 g / mol. The peak molar mass can be determined by GPC (test 1a) according to the method described in the "test methods" section.

[0058] Within the above-mentioned peak molar mass range, the adhesive has very good processability and at the same time very good hot shear strength, wherein the adhesive is correspondingly further optimized with respect to the conflicting goals of processability and hot shear strength within the peak molar mass range resulting from the selection of a higher preferred lower limit and upper limit.

[0059] The base substance may also contain one or more diblock copolymers AB. However, too high a content of diblock copolymers is detrimental to the thermal shear strength. Therefore, their content in the pressure-sensitive adhesive should not be too high. Particularly preferably, the average diblock content of the polyvinyl aromatic compound-polydiene block copolymer, based on the total of all polyvinyl aromatic compound-polydiene block copolymers of the base substance, does not exceed 50% by weight, in particular does not exceed 35% by weight and is preferably at least 10% by weight.

[0060] Using the above-mentioned diblock proportions, the adhesive has very good flowability and adhesion and at the same time very good hot shear strength, wherein using the diblock proportion range resulting from the selection of the lower and upper limits of the higher preference level, the adhesive is correspondingly further optimized with respect to the conflicting objectives of flowability and adhesion on the one hand and flowability and hot shear strength on the other hand.

[0061] In particular, the base material of the pressure-sensitive adhesive comprises a mixture of polyvinyl aromatic compounds-polydiene block copolymers with AB, ABA, (AB)3X or (AB)4X structure, which particularly preferably comprises radial block copolymers and / or triblock copolymers ABA. Also preferred are triblock copolymers and (AB)4X in which n is greater than / equal to 3. n or (AB) n Mixtures of X block copolymers. The block copolymers resulting from the A and B blocks may in principle contain identical or different B blocks. The block copolymers may have a linear ABA structure, may have a radial shape, and may include star-shaped and linear multiblock copolymers.

[0062] The vinyl aromatic compounds used for the structure (construction) of block A preferably include styrene and styrene derivatives, particularly preferably styrene and α-methylstyrene. Block A can be present in the form of a homopolymer or a copolymer. Particularly preferably, block A is a polystyrene block.

[0063] Therefore, it is particularly preferred that the at least one polydiene block copolymer is a polystyrene-polydiene block copolymer.

[0064] However, instead of the preferred polystyrene blocks, it is also possible to use as vinylaromatic compounds polymer blocks based on homopolymers and copolymers comprising other aromatic compounds, preferably homopolymers and copolymers of C8 to C12 aromatic compounds, in particular having a glass transition temperature of more than 75° C., for example aromatic blocks comprising α-methylstyrene. The glass transition temperature can be determined, for example, by DSC (test II).

[0065] The polyvinyl aromatic-polydiene block copolymers used according to the invention may comprise identical or different A blocks. Preferably, the polyvinyl aromatic-polydiene block copolymers have polystyrene end blocks.

[0066] 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 any mixtures of these monomers. Block B may also be in the form of a homopolymer or copolymer. Particularly preferably, the monomers for the soft block B are selected from the group consisting of butadiene and isoprene.

[0067] 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. Very particularly preferably, the block B is polyisoprene or polybutadiene, again preferably polybutadiene.

[0068] In particular, the use of polybutadiene as block B leads to high hot shear strength and long-term stability of the adhesive.

[0069] The A blocks of the polyvinyl aromatic-polydiene block copolymer preferably have a glass transition temperature of at least 25°C, in particular at least 50°C.

[0070] For the B blocks, glass transition temperatures of not more than 0° C., in particular not more than −25° C., are preferred. These data relate to the pure, unblended block copolymers and were determined according to the invention by DSC (test II).

[0071] The proportion of the A blocks in the polyvinylaromatic-polydiene block copolymer is preferably at least 12% by weight and not more than 40% by weight, more preferably at least 15% by weight and preferably not more than 35% by weight.

[0072] In particular and preferably, the polydiene block copolymer is a polystyrene-polydiene block copolymer having a polystyrene content of 14 to 40% by weight, preferably 18 to 35% by weight, particularly preferably 20 to 35% by weight.

[0073] Preferably, the total proportion of all polyvinylaromatic-polydiene block copolymers is preferably at least 35% by weight and not more than 65% by weight, more preferably at least 40% by weight and not more than 60% by weight, based on the total base material. It has been found that too small a proportion of polyvinylaromatic-polydiene block copolymers leads to a reduction in the hot shear strength of the pressure-sensitive adhesive, while too high a proportion of polyvinylaromatic-polydiene block copolymers leads to an excessive loss of adhesiveness of the pressure-sensitive adhesive, so that the pressure-sensitive adhesive or the corresponding adhesive tape according to the invention is no longer suitable for certain applications.

[0074] The figures of the molar masses of the above-mentioned block copolymers each relate to a polymer mode to which a person skilled in the art can attribute the block copolymer structure mentioned in the respective context. In this case, the figures of the molar masses are to be understood as peak molar masses. GPC generally allows the determination of the molar masses of each polymer mode in a mixture of different block copolymers.

[0075] According to a particularly preferred embodiment, the at least one polyvinyl aromatic-polydiene block copolymer is a styrene-butadiene-styrene block copolymer (SBS) or a styrene-isoprene-styrene block copolymer (SIS), in particular an SBS block copolymer.

[0076] In particular, the use of SBS block copolymers leads to high hot shear strength and long-term stability of the adhesive.

[0077] The base material also comprises at least one tackifying resin.

[0078] Tackifying resins are particularly used to set adhesion and / or adhesion (adhesive strength) in a desired manner. According to the general understanding of those skilled in the art, "tackifying resin" is understood to refer to an oligomeric or polymeric resin that improves the adhesion (i.e., inherent adhesion) of a pressure-sensitive adhesive compared to an otherwise identical pressure-sensitive adhesive without any tackifying resin. Tackifying resins are specific compounds with low molar mass compared to elastomers such as contained polydiene block copolymers, typically with a weight average molecular weight M less than 5000 g / mol. wTypically, the tackifying resins used within the scope of the present invention have a weight average molecular weight of 400 to 5000 g / mol, preferably 500 to 2000 g / mol, determined by GPC (test 1b).

[0079] The at least one tackifying resin is preferably compatible with the soft blocks of the polydiene block copolymer, and thus is compatible with the polydiene blocks, and is preferably substantially incompatible with the hard blocks of the polydiene block copolymer.

[0080] Within the scope of the present invention, the expressions “substantially incompatible” or “substantially incompatible” are understood in particular to mean that the ingredients or components mentioned are miscible with one another to an extent of at most 10% by weight, preferably at most 5% by weight.

[0081] In the context of the present invention, the expression “substantially compatible” is understood in particular to mean that the ingredients or components mentioned are miscible with one another to an extent of at least 90% by weight, preferably at least 95% by weight.

[0082] The at least one tackifying resin has a softening temperature (Ring & Ball, Test III) of at least 70° C., preferably at least 90° C. and at most +140° C.

[0083] Preferably, the tackifying resin component is selected from non-polar hydrocarbon resins, preferably hydrogenated and non-hydrogenated polymers of dicyclopentadiene (DCPD); non-hydrogenated, partially, selectively or fully hydrogenated hydrocarbon resins based on C5 or C5 / C9 monomer streams, or partially, selectively or fully hydrogenated hydrocarbon resins based on C9 monomer streams; polyterpene resins based on α-pinene and / or β-pinene and / or δ-limonene, which may also be hydrogenated; oxygen-containing polar tackifying resins such as terpene-phenolic resins or rosin-containing resins, in particular rosin esters.

[0084] At least one polyterpene resin based on α-pinene is especially preferred. In particular, if the polyvinyl aromatic compound-polydiene block copolymer is a polybutadiene block copolymer, it is preferred that the pressure-sensitive adhesive according to the invention comprises at least one polyterpene resin based on α-pinene.

[0085] Rosin resins and rosin ester resins may be hydrogenated or non-hydrogenated or disproportionated or otherwise stabilized. Their acid number is preferably at most 100 mg KOH / g (according to ASTM D465-15 / 2020).

[0086] The terpene-phenol resins may be hydrogenated or non-hydrogenated. Their OH value is preferably at most 100 mg KOH / g.

[0087] According to a preferred embodiment, at least one tackifying resin is included, which is selected from rosin resins and terpene phenol resins. Therefore, the base substance contains relatively polar resins. As a result, the pressure-sensitive adhesive according to the invention or the adhesive tape according to the invention has particularly good electrical re-peelability.

[0088] For example, in particular, hydrogenated resins based on pentaerythritol esters esterified with rosin are preferred.

[0089] Preferably, the base substance comprises at least 25% by weight, particularly preferably 25 to 65% by weight, very particularly preferably 30 to 55% by weight, again preferably 35 to 55% by weight, of at least one tackifier resin, based on the total weight of the base substance.

[0090] Therefore, preferably, the total amount of tackifier resins in the base substance is at least 25% by weight, particularly preferably 25 to 65% by weight, very particularly preferably 30 to 55% by weight, again preferably 35 to 55% by weight, based on the total weight of the base substance.

[0091] Within the total amount range of the tackifying resin, the adhesive has attractive thermal shear strength while having attractive adhesion and electrical peelability, wherein the adhesive is correspondingly further optimized with respect to the conflicting goals of adhesion and thermal shear strength and re-detachability within the amount range resulting from the selection of the lower and upper limits of the higher preferred level.

[0092] The quantitative proportion of polar resins, such as, in particular, rosin resins and terpene-phenol resins, is preferably high.

[0093] Preferably, the proportion of polar resins, such as in particular rosin resins and terpene-phenol resins, is 50 to 100% by weight, preferably 55 to 100% by weight, based on the total amount of tackifier resins contained in the base substance.

[0094] This results in the pressure-sensitive adhesive according to the invention or the adhesive tape according to the invention having particularly good electrical releasability.

[0095] Besides the components mentioned, the base material of the adhesive according to the invention may also comprise further components.

[0096] In particular, the base substance additionally comprises at least one plasticizer.

[0097] Plasticizers are primarily used for the final fine-tuning of the cohesion / adhesion (cohesion / adhesion) balance. Preferably, the plasticizer is one or more plasticizer resins and / or one or more mineral oils having a softening temperature of less than 30° C., determined according to test III. Plasticizer resins or plasticizer-resin mixtures are preferred, and very preferably plasticizer resins or plasticizer-resin mixtures having a melt viscosity (test IV) of at least 20 Pa*s, preferably at least 50 Pa*s at 25° C. and 1 Hz. The plasticizer resin is very preferably a plasticizer resin based on hydrocarbons or polyterpenes. Mineral oils or vegetable oils with a weight-average molecular weight of at least 500 g / mol, preferably at least 800 g / mol, are also conceivable. Plasticizers based on poly(iso)butylene are also conceivable.

[0098] The total amount of plasticizers in the base substance is preferably 0 to 15% by weight, particularly preferably 0 to 10% by weight. In the case of containing at least one plasticizer, the total amount of plasticizers is preferably 1 to 15% by weight, particularly preferably 1 to 10% by weight, very particularly preferably 1 to 5% by weight, based on the total weight of the base substance.

[0099] In order to adjust further properties, the base substance may contain further additives. Preferably, however, their proportion does not exceed 18% by weight, preferably not more than 10% by weight, of the base substance.

[0100] These additives are mainly protective agents. This includes primary and secondary (primary and secondary) types of aging inhibitors, light stabilizers and UV protective agents, as well as flame retardants, in addition to fillers, dyes and pigments. Pressure-sensitive adhesives can be colored as required, or white, gray or black. Typically, these or other additives that can be used are:

[0101] primary antioxidants such as sterically hindered phenols, preferably in a fraction of 0.2 to 1% by weight, based on the total weight of the base substance;

[0102] Secondary antioxidants such as phosphites and thioethers, preferably in a fraction of 0.2 to 1% by weight, based on the total weight of the base substance;

[0103] process stabilizers such as C free-radical scavengers, preferably in a proportion of 0.2 to 1% by weight, based on the total weight of the base substance,

[0104] Light stabilizers such as UV absorbers and sterically hindered amines, preferably in a fraction of 0.2 to 1% by weight, based on the total weight of the base substance;

[0105] Processing aids, preferably in a fraction of 0.2 to 1% by weight, based on the total weight of the base substance;

[0106] Optionally further polymers, preferably further polymers having elastomeric properties; elastomers which can be used therefore include, in particular: those based on pure hydrocarbons, for example unsaturated polydienes such as naturally or synthetically produced polyisoprenes and polybutadienes; chemically essentially saturated elastomers, for example saturated ethylene-propylene copolymers, olefin copolymers, polyisobutylene, butyl rubber, ethylene-propylene rubber; and chemically functionalized hydrocarbons, for example halogen-containing, acrylate-containing and allyl- or vinyl ether-containing polyolefins, preferably in a fraction of 0.2 to 10% by weight, based on the total weight of the base substance.

[0107] If the pressure-sensitive adhesive is in contact with a layer from which so-called rubber poisons such as copper, manganese II, iron II, cobalt or nickel ions can be released, it is advantageous to add at least one type of metal deactivator, also called "metal scavenger". Specific examples are ADK-Stab CDA-1, CDA-1H, CDA-6 and CDA-10 and ADK-Stab 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 substance.

[0108] In addition to the base material and the electrolyte, the pressure-sensitive adhesive according to the present invention comprises at least one compatibilizer according to a preferred embodiment, which is selected, for example, from polyethers, polyamines, polyvinyl pyrrolidones or aliphatic polyesters, wherein the compatibilizer preferably has a weight average molecular weight distribution Mw of 100 to 5000 g / mol, particularly preferably 200 to 2000 g / mol. In addition, amphoteric substances such as alkaline or alkaline earth soaps, anionic, cationic or nonionic surfactants can be used.

[0109] According to a particularly preferred embodiment, the pressure-sensitive adhesive according to the invention comprises at least one polyether as a compatibilizer, preferably at least one substance selected from the following: polyethylene glycol (PEG), polypropylene glycol (PPG), polytetrahydrofuran, wherein PEG and PPG are particularly preferred. Block copolymers formed by PEG and PPG and polyethers carrying hydrocarbon segments are also conceivable.

[0110] Surprisingly, particularly good re-detachability is achieved using the mentioned substances. Without wishing to be bound by a particular theory, it is conceivable that due to the mentioned substances, in particular and for example PEG, the ion flow of the electrolyte is accelerated through the substance layer (adhesive layer).

[0111] According to a preferred embodiment in which at least one compatibilizer is contained therein, the total amount of compatibilizer in the adhesive is 1 to 10% by weight, preferably 1 to 5% by weight, based on 100% by weight of the base substance.

[0112] The adhesive is thus further optimized with regard to the conflicting objectives of adhesion and electrical re-detachability.

[0113] According to a particularly preferred embodiment of the present invention, the pressure-sensitive adhesive according to the present invention comprises: the above-mentioned base material (including all embodiments or preferred levels of the present invention), preferably in an amount of 88 to 94% by weight, based on the total weight of the adhesive, and

[0114] an ionic liquid 1-ethyl-3-methylimidazolium tetrafluoroborate as an electrolyte, preferably in an amount of 4 to 10 wt %, based on the total weight of the adhesive, and

[0115] PEG as a compatibilizer is preferably used in an amount of 2 to 8 wt %, based on the total weight of the adhesive.

[0116] Preferably, the at least one polyvinylaromatic-polydiene block copolymer is at least one styrene-butadiene-styrene block copolymer, with two different styrene-butadiene-styrene block copolymers being particularly preferably contained.

[0117] Preferably, hydrogenated pentaerythritol ester rosin resin is also contained here as tackifier resin, preferably in a quantitative proportion of 55 to 100% by weight, based on the total amount of tackifier resin contained.

[0118] The use of an adhesive of this type results in particularly good releasability with simultaneously good adhesion prior to releasability.

[0119] The adhesive according to the invention is a pressure-sensitive adhesive.

[0120] As is generally customary, pressure-sensitive adhesives are to be understood according to the invention in this specification as meaning substances which are permanently tacky and adhesive, in particular at room temperature. Pressure-sensitive adhesives are characterized in that they can be applied to a substrate by pressure and remain adhered there, without the pressure to be applied and the duration of the action of this pressure having to be defined in detail. In some cases, depending on the exact nature of the pressure-sensitive adhesive, the temperature and air humidity and the substrate, the action of a short minimum pressure of no more than a gentle contact for a short period of time is sufficient to achieve the adhesive effect, in other cases, a longer action time of high pressure may also be necessary.

[0121] Pressure-sensitive adhesives have specific characteristic viscoelastic properties, which lead to long-lasting (permanent) adhesiveness and adhesiveness. Their characteristic is that when they are mechanically deformed, there is both a viscous flow process and the formation of elastic restoring forces. The two processes are in a specific relationship to each other in terms of their respective proportions, which depends not only on the precise composition, structure and degree of crosslinking of the pressure-sensitive adhesive substance, but also on the rate and duration of deformation, and on the temperature.

[0122] Proportional (a certain proportion) viscous flow is necessary for the realization of adhesion. The viscous components (components) produced only by the macromolecules with relatively large mobility allow effective wetting of the substrate to be bonded and effectively flow thereon. High viscous flow components cause high pressure-sensitive adhesive (also referred to as viscosity or surface viscosity) and therefore often also cause high adhesion. Due to the lack of flowable components, in general, highly crosslinked systems, crystalline or glass-like cured polymers at least have only very little pressure-sensitive adhesive or do not have pressure-sensitive adhesive at all.

[0123] Proportional (a certain proportion) elastic resilience forces are necessary for the realization of cohesion. They are generated, for example, by very long-chain and highly coiled macromolecules and by physical or chemical crosslinking and allow the forces acting on the adhesive bond to be transmitted. They lead to the adhesive bond being able to fully withstand the long-term loads acting on it (for example in the form of long-term shear loads) for a relatively long time.

[0124] In order to more precisely describe and quantify the measure of the elastic and viscous components, as well as the relationship between the components, the variables which can be determined with the aid of dynamic mechanical analysis (DMA, in accordance with DIN EN ISO 6721) can be used: the storage modulus (G′) and the loss modulus (G″). G′ is a measure of the elastic component of a substance, G″ is a measure of its viscous component. Both parameters depend on the deformation frequency and the temperature.

[0125] The variables can be determined with the aid of a rheometer. Here, for example, the material to be investigated is exposed to a sinusoidally oscillating shear stress in a plate-plate arrangement. In the case of an instrument operating in shear stress control, the deformation is measured as a function of time and the time shift of this deformation is measured relative to the introduction of the shear stress. This time shift is referred to as the phase angle δ.

[0126] The storage modulus G′ is defined as follows:

[0127] G′=(τ / γ)·cos(δ) (τ=shear stress, γ=deformation, δ=phase angle=phase shift between shear stress vector and deformation vector).

[0128] The loss modulus G″ is defined as follows:

[0129] G″=(τ / γ)·sin(δ) (τ=shear stress, γ=deformation, δ=phase angle=phase shift between shear stress vector and deformation vector).

[0130] If at room temperature, defined here as 23°C, at 10 0 -10 1 rad / s (radians / s), G′ is at least partially located in the range of 10 3 -10 7 Pa, and if G" also lies at least partially in this range, the substance is generally regarded as pressure-sensitively adhesive and is defined as pressure-sensitively adhesive in the sense of the present invention. "Partially" means that at least a part (at least a section) of the G' curve lies within the range from 10 0 rad / sec (including endpoints) to 10 1 rad / s (including the end points) and the deformation frequency range (abscissa) from 10 3 (Inclusive of endpoints) Pa to 10 7 The range of G' values ​​(ordinate) for Pa (including the endpoints) is within the window spanned by this. For G", this applies correspondingly.

[0131] Preferably, the pressure-sensitive adhesive has a thermal conductivity of 10 0 Up to 10 1 rad / s deformation frequency range and the storage modulus G′ in the range of 10 3 Up to 10 7 Pa range of loss modulus G".

[0132] In order to achieve viscoelastic properties, the monomers on which the polymer on which the pressure-sensitive adhesive is based and the optionally present other components of the pressure-sensitive adhesive are particularly selected so that the pressure-sensitive adhesive has a glass transition temperature (according to DIN 53765) below the use temperature, i.e., typically below room temperature (23° C.). The temperature range in which the polymer substance has pressure-sensitive adhesive properties can be expanded and / or shifted by suitable cohesion-enhancing measures such as crosslinking reactions (forming bridges between macromolecules). Thus, the application range of the pressure-sensitive adhesive can be optimized via the adjustment between the flowability and cohesion of the substance.

[0133] In particular, the pressure-sensitive adhesive has a glass transition temperature, determined in accordance with DIN 53765, of ≤23° C.

[0134] In contrast to pressure-sensitive adhesives, hot-melt adhesives, for example based on polyamide, polyurethane or modified polyethylene, are not adhesive at room temperature (23° C.), also in hot-melt adhesive compositions.

[0135] A further subject matter of the invention is an adhesive tape comprising at least one adhesive layer D of at least one adhesive according to the invention.

[0136] The adhesive tape according to the invention is preferably a double-sided adhesive tape. For the sake of convenience, within the scope of the invention, the adhesive tape according to the invention is also referred to as "adhesive tape" in the double-sided embodiment.

[0137] The invention relates to adhesive tapes which can be present in any assembled form, with adhesive tape rolls being preferred. The adhesive tapes, in particular in web form, can be produced in roll form (i.e. wound on itself in the form of an Archimedean spiral) or obtained as adhesive strips (e.g. in the form of cut or die-cut pieces).

[0138] The adhesive tape according to the invention is in particular in the form of a web. A web is understood to be an object whose length (extension (extent) in the x-direction) is a multiple of its width (extension (extent) in the y-direction) and whose width is formed approximately, preferably identically, along the entire length.

[0139] The general (generic) term "adhesive tape", also synonymously referred to as "adhesive strip", in the sense of the present invention comprises all flat structures, such as foils or foil parts (foil segments) extending in two dimensions, tapes with extended length and limited width, tape parts (tape segments), etc., and finally also die-cut parts or labels.

[0140] In addition to the length (x-direction) and width (y-direction), the adhesive tape also has a thickness (z-direction) extending perpendicularly to the two extents, wherein the width and length extents are many times greater than the thickness. The thickness is as constant as possible over the entire area determined by the length and width of the adhesive tape, preferably completely identical within a tolerance range.

[0141] These embodiments apply analogously to the carrier which, as a component of the adhesive tape, forms a layer in the x and y direction.

[0142] It will be appreciated that the layers are arranged on top of each other in the z-direction.

[0143] Another subject of the invention is a bonded composite comprising at least the following layers:

[0144] A first substrate A; and

[0145] A second substrate B; and

[0146] The adhesive tape according to the present invention, which is arranged between a substrate A and a substrate B and bonds the substrates A and B to each other.

[0147] Another subject of the present invention is a method for the electrical separation of the complexes according to the invention, comprising at least the following method steps:

[0148] i.) applying a voltage at two different sites of the complex, wherein the voltage is preferably 2 to 50V.

[0149] The application of voltage is carried out according to step i.) of the method for electrical separation of complexes according to the invention.

[0150] In particular, the voltage is a DC voltage.

[0151] According to a preferred embodiment of the invention, the voltage is 3 to 12 V. Such a voltage can in particular be applied by using a battery located in the vicinity of the bond, as in particular and for example in mobile phones, tablet computers and the like.

[0152] According to a further preferred embodiment of the invention, the voltage is 12 to 50 V. This relatively high voltage allows particularly rapid re-separation; the voltage only needs to be applied for a few seconds.

[0153] The duration of application of the voltage in step i.) can be a few seconds, in particular 2 seconds, up to 900 seconds, preferably up to 600 seconds, depending in particular on the voltage chosen.

[0154] Of course, it is also conceivable that the voltage may be applied for a period of time exceeding 900 seconds, particularly when the voltage is relatively low.

[0155] The method according to the invention for electrical separation of the composite according to the invention enables substrates A and B to be separated from one another in a rapid and easy manner without requiring a great expenditure of force.

[0156] If, after application of the voltage, the layers do not separate from one another without further action, the method according to the invention comprises at least the further method steps:

[0157] ii.) applying force to the adhesive layer D and / or the substrate A and / or the substrate B, thereby increasing the distance between the substrates A and B.

[0158] The force which may still be required according to step ii.) is significantly lower than the adhesive force before the application of the voltage according to step i.).

[0159] The application of the voltage according to step i.) is carried out at two different points of the bonded composite according to the invention. The point at which the voltage is applied appropriately depends on the construction of the adhesive tape and the bonded composite and therefore on the properties of the individual layers and the mutually bonded substrates A and B.

[0160] Hereinafter, some preferred embodiments are implemented.

[0161] According to a preferred embodiment, the adhesive tape is a transfer tape and consists of an adhesive layer D.

[0162] This adhesive tape can be advantageously electrically separated again in a bonded composite with two substrates A and B in the following manner: both substrate A and substrate B are conductive. For this purpose, a voltage is applied to substrates A and B so that migration of anions to the anode and cations to the cathode occurs in the adhesive. Without wishing to be bound by a particular theory, the inventors assume the following mechanism: by applying a voltage, migration of electrolytes, in particular separation of anions and cations of ionic liquids, occurs in the adhesive layer D. Thus, the adhesion of the adhesive layer D to substrates A and B is greatly reduced and these layers are separated (loosened) from each other.

[0163] According to a preferred embodiment of the invention, the bonded composite thus comprises the following layers:

[0164] a first substrate A which is electrically conductive; and

[0165] a second substrate B which is electrically conductive; and

[0166] The adhesive tape according to the present invention, which is composed of an adhesive layer D and is arranged between a substrate A and a substrate B, and bonds the substrates A and B together.

[0167] According to a further preferred embodiment, in addition to the first adhesive layer D, the adhesive tape further comprises at least the following layers:

[0168] A second adhesive layer C; and

[0169] • At least one electrically conductive carrier layer T arranged between layers D and C.

[0170] Such an adhesive tape can be used as a double-sided adhesive tape for a wide variety of substrates via the second adhesive layer C. In principle, this can be the same substrate as in the previous embodiment in which the adhesive tape is a transfer tape.

[0171] Furthermore, such an adhesive tape can be used in particular and also advantageously for later separation of substrates A and B from one another, wherein only one substrate, for example substrate A, is electrically conductive.

[0172] According to a preferred embodiment, either xi.) only the carrier layer T or xii.) the carrier layer T and the second adhesive layer C are designed to be electrically conductive.

[0173] Thus, a voltage can be applied to xi.) the electrically conductive carrier layer or to xii.) the second adhesive layer C and the electrically conductive substrate A.

[0174] The tape is advantageously previously bonded as a double-sided tape, so that the electrically separable adhesive layer D is bonded to the conductive substrate A and the second adhesive layer is bonded to the substrate B, which can be conductive, but need not be.

[0175] Without wishing to be bound by a particular theory, the inventors assume the following mechanism: by applying a voltage, migration of electrolytes, in particular separation of anions and cations of the ionic liquid, occurs in the adhesive layer D. As a result, the adhesion of the adhesive layer D to the substrate A is greatly reduced and the layers are separated (loosened) from each other.

[0176] According to a preferred embodiment of the invention, xi.) only the carrier layer is electrically conductive. In particular and preferably, a voltage can be applied to the carrier layer particularly effectively when the carrier layer protrudes laterally beyond the at least one adhesive layer.

[0177] According to a further preferred embodiment of the invention, xii.) the carrier layer and the second adhesive layer C are electrically conductive. This structure has the advantage that a voltage can be applied to the adhesive layer C. A lateral projection of the carrier layer is unnecessary. Thus, the adhesive tape can be produced in a simple manner, in particular because the layers D, T and C can be stamped (die-cut) together.

[0178] Preferably, according to the above-described embodiment, the adhesive tape consists of three layers D, T and C. For this reason, the term three-layer composite DTC is also used within the scope of the present application.

[0179] According to a preferred embodiment of the invention, the bonded composite thus comprises the following layers:

[0180] a first substrate A which is electrically conductive; and

[0181] A second substrate B; and

[0182] An adhesive tape according to the invention, which consists of a three-layer composite DTC, and the substrates A and B are bonded to one another in such a way that the adhesive layer D is bonded to the electrically conductive substrate A.

[0183] According to a further preferred embodiment, the adhesive tape comprises at least the following layers in addition to the first adhesive layer D:

[0184] A second adhesive layer C; and

[0185] at least one first electrically conductive carrier layer T arranged between layers D and C; and

[0186] at least one second electrically conductive carrier layer T′ arranged on the face of said adhesive layer D opposite to the first electrically conductive carrier layer T; and

[0187] • A third adhesive layer C' arranged on the face of the second electrically conductive carrier layer T' opposite to the first adhesive layer D.

[0188] This adhesive tape has at least a layer structure CTD-T'-C' and can be used as a double-sided adhesive tape for various substrates via the adhesive layers C and C'.

[0189] In principle, this can be the same substrate as in the previous embodiment, wherein the adhesive tape is a transfer tape or has a three-layer structure DTC.

[0190] However, such an adhesive tape can also be used in particular and advantageously to later separate substrates A and B from one another, wherein neither substrate A nor B is electrically conductive.

[0191] According to a preferred embodiment, 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 designed to be electrically conductive.

[0192] A voltage can thus be applied to xi.) both electrically conductive carrier layers or xii.) to at least one adhesive layer C and C′ and to one of the carrier layers or to the other adhesive layer.

[0193] Similar to the above embodiment, it is assumed that by applying a voltage, migration of electrolytes, in particular separation of anions and cations of the ionic liquid, occurs in the adhesive layer D. As a result, the adhesion of the adhesive layer D to the conductive support layers T and T' is greatly reduced and these layers are separated (loosened) from each other.

[0194] According to a preferred embodiment of the invention, xi.) only the carrier layers T and T' are electrically conductive. In particular and preferably, a voltage can be applied to the carrier layers T and T' particularly effectively when the carrier layers T and T' protrude laterally beyond at least one of the respective adjacent adhesive layers.

[0195] According to a further preferred embodiment of the invention, xii.) the carrier layers T and T' and the second and third adhesive layers C or C' are electrically conductive. This structure has the advantage that a voltage can be applied to the adhesive layers C and C'. Lateral projections of the carrier layers T and T' are unnecessary. Thus, the adhesive tape can be manufactured in a simple manner, in particular because the layers C, T, D, T' and C' can be stamped (die-cut) together.

[0196] Preferably, according to the above-described embodiment, the adhesive tape consists of five layers C, T, D, T' and C'. For this reason, within the scope of the present application, the term five-layer composite CTD-T'-C' is also used.

[0197] According to a preferred embodiment of the invention, the bonded composite thus comprises the following layers:

[0198] A first substrate A; and

[0199] A second substrate B; and

[0200] An adhesive tape according to the invention, which consists of five layers of the composite CTD-T'-C' and in which the substrates A and B are bonded to one another.

[0201] The conductive substrate of all embodiments may be, for example, a metal housing of a mobile phone.

[0202] In all embodiments, the non-conductive substrate may be, in particular, a housing made of a non-conductive material, such as plastic, or a battery or other components of non-conductive design, such as a loudspeaker.

[0203] A further subject matter of the present invention is the use of the adhesive tape according to the invention for bonding components in electronic devices, vehicles, medical devices and dental devices.

[0204] The carrier layers T as well as T and T' of all the above-described embodiments are electrically conductive.

[0205] In the following, these layers are further explained. For simplicity, the term "conductive carrier layer" or even just "carrier layer" is used. According to the above embodiments, this refers to the carrier layer T or the carrier layers T and T'.

[0206] The carrier layers T and T′ are independent of one another and can be designed identically or differently from one another.

[0207] Preferably, the electrically conductive carrier layer comprises at least one metal.

[0208] 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. Aluminum is very preferred.

[0209] 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 10 nm (nanometers) to 50 μm (micrometers).

[0210] According to a preferred embodiment of the present invention, the conductive carrier layer comprises a) at least one metal foil, preferably an aluminum foil, and / or b) at least one conductive textile, which comprises at least one metal, preferably a metal selected from copper and nickel, and / or c) one or more layers of at least one vapor-deposited metal, which is preferably selected from copper and aluminum, and / or d) at least one metal grid and / or e) a foil vapor-deposited with a metal.

[0211] In principle, it is also conceivable here for the layer T to have a combination of two or more of the abovementioned possibilities.

[0212] Metal foils, such as and preferably aluminum foils, are known to those skilled in the art.

[0213] Preferably, the metal foil, for example and preferably an aluminum foil, has a layer thickness measured in the z direction, ie parallel to the stacking direction of the layer arrangement, of 5 to 50 μm, particularly preferably of 10 to 30 μm.

[0214] Conductive textiles are known to the person skilled in the art, in particular by the English expression “conductive mesh”. Here, for example, they are textile fabrics made of PET (polyethylene terephthalate) which are coated with metal, for example copper and / or nickel, thereby producing the electrical conductivity of the fabric.

[0215] It is also known to those skilled in the art that the metal can be vapor-deposited as a single layer or multiple layers directly onto a surface, such as the surface of the adhesive layer in this case.

[0216] Within the scope of the present invention, the electrically conductive support layer can be provided by evaporation of the metal onto the adhesive layer D or the adhesive layer C or the adhesive layer C′.

[0217] Furthermore, metal grids of different sizes are known to the person skilled in the art.Metal grids with appropriate layer thicknesses can be produced, for example, by a mesh composed of corresponding thin metal wires or by punching out at least one foil of corresponding layer thickness.

[0218] In the case of metal-deposited foils, in particular, non-conductive foils are metal-deposited to make them conductive. The material of the foil can in principle be selected from all materials that are suitable for metal deposition and used as carrier foil in the adhesive tape. The material is selected in particular from polyesters and polyolefins, wherein mixtures of various materials are conceivable. As polyesters, in particular polyethylene terephthalate (PET) and polyethylene naphthalate (PEN) are preferred. As polyolefins, in particular polypropylene (PP), polyethylene (PE) are preferred. According to a preferred embodiment, the material of the foil is selected from PET, PEN, PE, PP.

[0219] Preferably, it is a foil made of PET (polyethylene terephthalate). Such a foil is dimensionally stable and can therefore be easily processed without significant stretching or tearing. This makes it possible to apply a uniform and gap-free metal layer permanently (permanently), so that electrical conductivity, in particular in the z-direction, is permanently (permanently) ensured over the entire foil.

[0220] In embodiments in which at least one electrically conductive carrier layer T or at least two electrically conductive carrier layers T and T' is present, it is preferred that these protrude laterally beyond at least one adjacent adhesive layer in at least one extension direction of the layer plane and thus have a lateral projection. A voltage can then be applied to this lateral projection in a simple manner.

[0221] In the case of a five-layer composite, according to an advantageous embodiment, the lateral projections of the electrically conductive carrier layers T and T' are spatially separated from one another. This makes it easier to apply a voltage to these two projections.

[0222] In the case of a vapor-deposited metal as a carrier layer, it is preferred that the carrier layer only protrudes laterally from the adjacent adhesive layer in at least one extension direction of the layer plane and the other adhesive layer is used accordingly as a mechanical support for the metal layer. Here, the metal layer has no actual carrier function (support function). On the contrary, the other adhesive layer serves as a carrier for the metal layer. However, for simplicity, the term carrier layer is still retained for the metal layer in these embodiments. Preferably, in this case, the layer thickness of layer T is greater than or equal to 10 nm (nanometer), preferably 50 to 200 nm.

[0223] According to a preferred embodiment of the present invention, the conductive carrier layer T or T and / or T' has a) at least one metal foil, preferably an aluminum foil, and / or b) at least one conductive textile, which has at least one metal, preferably a metal selected from copper and nickel, and / or d) at least one metal grid and / or e) a foil evaporated with metal, and protrudes in at least one extension 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'.

[0224] As a result, a voltage can be applied to the carrier layer in a simple and safe manner. At the same time, the adhesive tape can be produced in a relatively simple manner.

[0225] According to a preferred embodiment of the 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 a metal selected from the group consisting of copper and aluminum.

[0226] According to a particularly preferred embodiment of the present invention, the electrically conductive carrier layer T or T and / or T' comprises e) a foil on which metal is evaporated and protrudes in at least one extension direction beyond the first adhesive layer D. In this case, the foil is in particular evaporated with metal on the surface, and the respective carrier layer is bonded to the first adhesive layer D and thus to the electrically separable layer via the metallized surface.

[0227] As a result, a voltage can be applied to the carrier layer in a simple and safe manner.

[0228] The expression "transversely protruding" refers within the scope of the present invention to any type of lateral protrusion of the layer or layers described and means that the layer described extends in particular in the "xy" plane and therefore extends laterally - perpendicular to the stacking direction - further than a reference layer. In the scope of the present invention, the terms "lateral extension" or "lateral extension" are also used instead of the term "lateral protrusion".

[0229] The term "transversely" here refers to any extension direction of the layer plane "xy" perpendicular to the stacking direction of the layer "z". The term is therefore in particular independent of the geometric shape of the adhesive tape in the "xy" plane, which can be, for example, rectangular, as is customary for adhesive tapes (see above), but can also be square or circular.

[0230] Slight changes in the dimensions of the individual layers in the “xy” plane due to punching methods or similar forming methods are not mentioned here, particularly since such slight material protrusions are not suitable for the intended application of voltage due to their size.

[0231] The adhesive layer C or C and C' can in principle be based on the same substances as the adhesive layer D, wherein the adhesive of the layer C or C and C' does not necessarily have to contain an electrolyte, but can do so. Preferably, the layer C or C and C' contains no electrolyte.

[0232] According to some embodiments of the above three-layer composite DTC, the adhesive layer C is electrically conductive.

[0233] Similarly, the adhesive layer C and / or the adhesive layer C' of the five-layer composite CTD-T'-C' may be designed to be electrically conductive.

[0234] In the following, these layers are further explained. For the sake of simplicity, the term "conductive adhesive layer" is used where appropriate. According to the above-mentioned embodiment, this relates to the adhesive layer C or the adhesive layer C and / or C'. In addition, for the sake of simplicity, the expression "adhesive layer C or C and / or C'" is used to refer to the corresponding layer in the embodiment of the adhesive tape comprising at least three layers of composite or at least five layers of composite.

[0235] The adhesive layers C and C' are independent of each other and may be the same as or different from each other.

[0236] Preferably, the electrically conductive adhesive layer contains 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.

[0237] The metallized particles are in particular and preferably glass or polymer particles which are metallized with at least one metal, so that the previously non-conductive particles are made conductive by the metallization.

[0238] Particularly preferably, the conductive adhesive layer contains conductive particles selected from nickel particles, copper particles and silver-plated copper particles.

[0239] According to a particularly preferred embodiment, the conductive adhesive layer contains nickel particles.

[0240] The conductive adhesive layer preferably contains 5 to 40% by weight, preferably 20 to 40% by weight, very particularly preferably 25 to 35% by weight, of conductive particles, in particular metal particles and / or metallized particles, based on 100% by weight of polymers and tackifier resins contained.

[0241] The conductive particles should preferably be no larger or no significantly larger than the corresponding thickness of the conductive adhesive layer in the z direction measured with an optical microscope.

[0242] Preferably, the electrically conductive particles have an average particle size of 1 to 10 μm, particularly preferably 1 to 6 μm, further preferably 3 to 5 μm, such as in particular 4 μm.

[0243] The conductive adhesive layer is in particular electrically conductive at least in the z-direction.

[0244] However, it can also be conductive in the xy plane. When the conductive adhesive layer is designed to be conductive only in the z direction, but not necessarily in the xy direction, according to a preferred embodiment in which metals, in particular metal particles, are added to achieve conductivity, small amounts of these materials are required. As a result, the adhesive is optimized with respect to the required conductivity, adhesion, flow behavior and cost.

[0245] According to standard MIL-DTL-83528C, a layer is then considered to be “conductive” within the scope of the invention in particular if the resistance measured in the corresponding direction (here in particular the z direction) is less than 1 ohm.

[0246] The following embodiments apply regardless of whether the adhesive layer C or C and / or C′ is designed to be electrically conductive.

[0247] According to a preferred embodiment, the adhesive layer C or C and / or C′ is not a pressure-sensitive adhesive.

[0248] According to a particularly preferred embodiment of the present invention, the adhesive of the adhesive layer C or C and C′ is a pressure-sensitive adhesive and therefore the adhesive layer C or C and C′ is a pressure-sensitive adhesive layer.

[0249] According to a preferred embodiment of the present invention, the adhesive layer C or C and / or C′, such as the adhesive layer D, is an adhesive based on at least one polydiene block copolymer and at least one tackifying resin.

[0250] According to a preferred embodiment of the present invention, the same polydiene block copolymer and the same tackifier resin as those in the adhesive layer D are used in the adhesive layer C or C and / or C′.

[0251] In this way, in particular similar substrates, referred to here as A and B, can be bonded to one another.

[0252] According to a further preferred embodiment of the present invention, an adhesive different from the adhesive of the adhesive layer D is used in the adhesive layer C or C and / or C′.

[0253] The properties of the conductive layer can thus be adapted particularly well to the substrates bonded via the adhesive layer C or C and / or C′. Since the adhesive layer C or C and / or C′ preferably contains no electrolytes, such as ionic liquids, the components do not need to be adapted accordingly.

[0254] According to a preferred embodiment of the present invention, an adhesive different from the adhesive of adhesive layer D is used in adhesive layer C or C and / or C', wherein the adhesive of adhesive layer C or C and / or C' may be heat-activatable or may be an acrylate-based pressure-sensitive adhesive.

[0255] The adhesive of the adhesive layer D and, depending on the embodiment, the further adhesives are produced by known methods and applied in layers, in particular by painting. This can be done using one or more suitable solvents or also in a solvent-free manner.

[0256] Furthermore, one or more drying steps may optionally be carried out. However, the production of the adhesive according to the invention is preferably carried out by extrusion in a solvent-free manner, which is a further advantage of the invention. In this way, in the production of the adhesive and adhesive layer according to the invention, in addition to the possibility of later re-stripping, the degree of sustainability can be further increased by avoiding the use of solvents.

[0257] A plurality of layers are laminated together in a manner known to the person skilled in the art, wherein the layers are stacked in such a way that in particular a layer composite DTC (with T arranged between D and C) or C′-T′-DTC is obtained as a double-sided adhesive tape.

[0258] As mentioned above, the carrier layer T or T' can be provided in different ways.

[0259] It is therefore conceivable to place a) a metal foil, in particular an aluminum foil, and / or b) a conductive mesh and / or d) at least one metal grid and / or e) a metal-evaporated PET foil between the respective adhesive layers.

[0260] In addition, c) the metal particles may be directly evaporated onto the surface of the adhesive layer D, C or C'.

[0261] The adhesive tape according to the invention represents in particular a double-sided adhesive tape in which, depending on the embodiment, both sides of the first adhesive layer D (transfer tape) or one side of the first adhesive layer D and one side of the second adhesive layer C (three-layer composite DTC) or one side each of the adhesive layers C and C' (five-layer composite CTD-T'-C') can be used in each case for bonding the substrates.

[0262] Advantageously, the exposed outer surface of the adhesive layer of the adhesive tape according to the invention can be provided with an anti-adhesive material, such as a release paper or a release film (also referred to as a liner). In the liner, it can also be a material that is anti-adhesive coated (with an anti-adhesive coating) on ​​at least one side, preferably on both sides, for example a siliconized material on both sides. The liner, or more generally, the temporary carrier, is not part of the adhesive tape, but is merely an aid for its manufacture, storage and / or further processing by stamping. In addition, unlike a permanent carrier, the liner is not firmly bonded to the adhesive layer, but acts as a temporary carrier, i.e. a carrier that can be removed from the adhesive layer. "Permanent carrier" is also referred to synonymously in this application as "carrier".

[0263] The thickness of the individual adhesive layers (in the z direction) is preferably 15 to 2000 μm, particularly preferably 20 to 500 μm, very particularly preferably 25 to 200 μm. However, thicknesses which are as small as possible are preferred, for example less than 100 μm.

[0264] In the embodiments of the three-layer composite DTC and the five-layer composite CTD-T'-C', the adhesive layers D and C or D and C and D and C' have different layer thicknesses according to a preferred embodiment, wherein the thickness of the adhesive layer D is, for example, smaller than the thickness of the adhesive layers C or C and C'.

[0265] According to a further preferred embodiment, the layers D and C or D, C and C′ have the same layer thickness.

[0266] If the layer thickness of layer D is too high, this can be uneconomically cost-intensive due to the electrolyte contained.

[0267] If necessary, in order to increase the anchoring of the adhesive layer to the carrier layer, the carrier layer can be subjected to a chemical and / or physical pretreatment, in particular a physical pretreatment. Corona, plasma or flame pretreatments are conceivable. Surface treatment of metallized foils by corona is also known to those skilled in the art and is described, for example, in EP 0355622 A2. BRIEF DESCRIPTION OF THE DRAWINGS

[0268] In the following, preferred embodiments of the present invention are explained and described in more detail with reference to the accompanying drawings. The accompanying drawings show:

[0269] Figure 1 A simplified schematic cross-sectional view of a double-sided adhesive tape according to the invention in a preferred embodiment; and

[0270] Figure 2 A simplified schematic cross-sectional view of a double-sided adhesive tape according to the invention in a preferred embodiment; and

[0271] Figure 3 A simplified schematic cross-sectional view of a double-sided adhesive tape according to the invention in a preferred embodiment; and

[0272] Figure 4 A simplified schematic cross-sectional view of a bonded composite according to the invention in a preferred embodiment; and

[0273] Figure 5 A simplified schematic cross-sectional view of a preferred embodiment of a bonded composite according to the invention, to which a voltage is applied; and

[0274] Figure 6 A simplified schematic cross-sectional view of a bonded composite according to the invention after application of a voltage and thus adhesive cleavage; and

[0275] Figure 7 A simplified schematic cross-sectional view of a bonded composite according to the invention in a preferred embodiment; and

[0276] Figure 8 Simplified schematic cross-sectional view of a preferred embodiment of a bonded composite according to the invention. DETAILED DESCRIPTION

[0277] like Figure 1 As shown in FIG, the adhesive layer D1 is bonded via one of its faces to the carrier layer T2. On the face of the carrier layer T opposite to the layer D, a second adhesive layer C3 is arranged.

[0278] As in Figure 1 As can likewise be seen in FIG. 1 , the layer composite represents a double-sided adhesive tape, wherein the side of the adhesive layer D and the side of the second adhesive layer C are available in each case for bonding.

[0279] exist Figure 2 A preferred embodiment of the present invention is shown in . In this case, the conductive carrier layer T2 protrudes laterally beyond the adhesive layer D1 and the second adhesive layer C3 in at least one extension direction of the layer plane, so that the conductive carrier layer T2 has a protrusion with at least one free surface 2a.

[0280] Figure 3A further preferred embodiment of the present invention is shown in FIG. Here, the conductive carrier layer T 2 protrudes laterally beyond the adhesive layer D 1 in at least one extension direction of the layer plane, so that the conductive carrier layer T 2 has a protrusion with a free surface 2 a. Figure 3 The middle adhesive layer C3 is designed such that it also has a protrusion relative to the layer D1. In particular, the carrier layer T2 is a PET film coated with aluminum on one side, wherein the aluminum-coated side is bonded to the layer D1.

[0281] Figure 4 A schematic diagram of a bonded composite according to the invention in a preferred embodiment is shown in FIG. Figure 4 As can be seen in FIG. 1 , the adhesive tape is arranged on one side of a first substrate A4 via an adhesive layer D1 , wherein the first substrate is conductive.

[0282] Furthermore, the adhesive tape is arranged on one side of the second substrate B5 via a second adhesive layer C3.

[0283] exist Figure 4 It is also shown in the example that the conductive carrier layer T2 protrudes laterally beyond the first adhesive layer D1 in at least one extension direction of the layer plane, so that the conductive carrier layer T has a protrusion with a free surface 2a.

[0284] Now a voltage can be applied to the free surface 2a, as in Figure 5 As shown in the schematic diagram.

[0285] By applying a voltage, migration of the electrolyte, in particular separation of anions and cations of the ionic liquid, occurs in the adhesive layer D1.

[0286] As a result, the adhesion of the adhesive layer D1 to the substrate A4 is greatly reduced, and the layers are separated from each other, as shown in FIG. Figure 6 As shown in the schematic diagram.

[0287] exist Figure 7 A further schematic diagram of a bonded composite according to the invention in a preferred embodiment is shown in FIG. Figure 7 As can be seen in the figure, the adhesive tape is arranged on one side of the first substrate A4 via the adhesive layer C3.

[0288] Furthermore, the adhesive tape is disposed on one side of the second substrate B5 via a third adhesive layer C'7.

[0289] Between the layers C3 and C′7 there is an electrically separable adhesive layer D1 and two electrically conductive carrier layers T2 and T′6 , wherein the layer D1 is arranged between the carrier layers.

[0290] exist Figure 7It is also shown in the figure that the conductive carrier layer T2 and the conductive carrier T'6 respectively protrude laterally from the first adhesive layer D1 in at least one extension direction of the layer plane, so that the conductive carrier layer T has a protrusion with a free surface 2a and the conductive carrier T'6 has a protrusion with a free surface 6a.

[0291] exist Figure 8 A further schematic diagram of a preferred embodiment of the bonded composite according to the invention is shown in FIG. Figure 7 However, unlike Figure 7 Differently, the projections of the electrically conductive carrier layer T2 and of the electrically conductive carrier layer T′6 point in different directions, so that the resulting free surfaces 2 a or 6 a of these layers are spatially separated.

[0292] Now a voltage can be applied to these free surfaces 2a and 6a, similar to Figure 5 . According to Figure 5 Unlike the embodiment of the present invention, a voltage can be applied to both surfaces 2a and 6a, so that neither substrate A nor B need to be electrically conductive.

[0293] By applying a voltage, the migration of electrolytes, in particular the separation of anions and cations of the ionic liquid, occurs in the adhesive layer D1. As a result, the adhesion of the adhesive layer D1 to the carrier layer T2 and / or T'6 is greatly reduced, and these layers are separated from each other. In particular, separation occurs at the layer where the negative electrode is applied.

[0294] In accordance with Figure 8 The application of the voltage is simplified in the case of spatially separated surfaces 2 a and 6 a.

[0295] Figures 1 to 8 The figure in is a schematic diagram of the invention. In particular, the layer thicknesses of the individual layers D, T and C may differ from one another. In addition, the substrates A and B are also only schematically shown as further layers. Of course, these may have any other spatial geometry.

[0296] Hereinafter, some examples are described to further illustrate the present invention.

[0297] Test Method

[0298] Unless otherwise specified, all measurements are carried out at 23°C and 50% relative air humidity. The mechanical and adhesive technical data are determined as follows:

[0299] Test I - Molar Mass (GPC)

[0300] (a) Peak molar masses of individual block copolymer modes

[0301] In terms of molar mass distribution, polymers are multimodal systems. A mixture of different polymers can be understood as a multimodal system, wherein each polymer contributes its own molar mass distribution. A mixture of block copolymers with structures having different molar mass distributions can also be understood as a multimodal system. Thus, each block copolymer contributes its own molar mass distribution. For simplicity, these are referred to as block copolymer modes here.

[0302] GPC (gel permeation chromatography) is a metrological method for determining the molar masses of individual polymer modes in a mixture of different polymers. For block copolymers prepared by living anionic polymerization which can be used in the sense of the present invention, the molar mass distribution is generally narrow enough to allow polymer modes assignable to triblock copolymers, diblock copolymers or multiblock copolymers to appear with sufficient resolution from one another in the elution spectrum. The peak molar masses of the individual polymer modes can then be read off from the elution spectrum.

[0303] The peak molar mass of the elastomer (peak M W ) was determined by GPC. The eluent used was THF. The measurement was carried out at 23°C. The preparatory column used was PSS-SDV, 5μ, ID 8.0mm x 50mm. For separation, the column used was PSS-SDV, 5μ, as well as and Each had an ID of 8.0 mm x 300 mm. The sample concentration was 4 g / l and the flow rate was 1.0 ml / min. Calibration was performed using ReadyCalkit Poly(styrene) high commercially available from PSS Polymer Standard Service GmbH, Mainz (μ = μm; ).

[0304] (b) Weight average molar mass

[0305] The weight average molecular weight M of the tackifying resin, plasticizer and reinforcing agent w Determined by GPC. The eluent used was THF. The measurement was carried out at 23°C. The preparatory column used was PSS-SDV, 5μ, ID 8.0mm x 50mm. For separation, the column used was PSS-SDV, 5μ, as well as and Each had an ID 8.0 mm x 300 mm. The sample concentration was 4 g / l and the flow rate was 1.0 ml / min. The calibration was performed using the ReadyCal kit Poly(styrene) high commercially available from PSS Polymer Standard Service GmbH, Mainz.

[0306] Test II-DSC

[0307] In particular, the glass transition point of a polymer or polymer block, synonymously referred to as glass transition temperature, is reported as the result of measurement by differential scanning calorimetry (DSC) according to DIN 53 765, in particular Sections 7.1 and 8.1, but with a uniform heating and cooling rate of 10 K / min in all heating and cooling steps (see DIN 53 765; Section 7.1; Note 1). The sample weight is 20 mg. The melting temperature or softening temperature of a polymer or polymer block is also determined in this way.

[0308] Test III - (Tackifying Resin) Softening Temperature

[0309] For the individual substances: The (tackified) resin softening temperature (softening point; Erw point) was carried out according to the relevant methodology known as Ball & Ring and standardized according to ASTM E28.

[0310] Test IV - Melt Viscosity

[0311] In order to measure the melt viscosity of plasticizer resin, shear stress scanning was performed in a rotational manner in a DSR 200N rheometer with regulated shear stress from Rheometrics Scientific. A cone / plate measuring system with a 25 mm diameter (cone angle 0.01002 rad) was used, the measuring head being air bearing and suitable for standard force measurement. The gap was 0.053 mm and the measuring temperature was 25 ° C. The frequency varied from 0.002 Hz to 200 Hz and the melt viscosity was recorded at 1 Hz.

[0312] Test V – Peel Adhesion, Steel

[0313] The mensuration of peel adhesion is carried out as follows.Use the polished steel plate (ASTM D3330 that thickness is 2mm; Use cellulose cloth to clean three times with acetone and evaporate for 10 minutes) as the adhesive substrate of definition.The bondable sheet element to be studied is cut into the width of 20mm and the length of about 25cm, equipped with handle part (unless otherwise specified), and immediately after this, press on the adhesive substrate with 4kg steel roller at the speed of 10m / minute back and forth five times.After this, immediately with tensile testing machine (from Zwick company) at speed v=300mm / minute, bondable sheet element is pulled away from the adhesive substrate at 180 ° angle, and measure the power required for this at room temperature.Measured value obtains (in N / cm) as the average value from three separate measurements.

[0314] Test VI - Thickness

[0315] The thickness of the adhesive layer can be determined by measuring the thickness of a portion (segment) of such adhesive layer applied to the liner, defined according to its length and its width, minus the thickness of a portion (segment) of the liner used with the same dimensions (known or individually determinable). The thickness of the adhesive layer can be determined using commercial thickness gauges (probe instruments) with an accuracy of less than 1 μm deviation. If fluctuations in the thickness are determined, the average of the measured values ​​at at least three representative locations is reported, i.e. in particular not measuring at folds, creases, tips, etc.

[0316] Like the thickness of the adhesive layer, the thickness of the adhesive tape (adhesive strip) or carrier can also be determined similarly using a commercial thickness gauge (probe instrument) with an accuracy of less than 1 μm deviation. If fluctuations in the thickness are determined, the average value of the measured values ​​at at least three representative locations is reported, i.e. in particular not measuring at folds, creases, tips, etc.

[0317] The following embodiments according to the invention of an adhesive according to the invention and of an adhesive tape comprising at least one adhesive layer D of an adhesive according to the invention are produced in the form of a transfer tape, adhered between substrates and then electrically separated again by applying a voltage.

[0318] Embodiment 1 according to the present invention

[0319] The adhesive and the transfer tape produced therefrom are provided as follows:

[0320] 30% Kraton D1152 ES (15% diblock, polystyrene content: 29%, linear SBS), 13% Kraton D1116 AT (PS 23%, diblock 16%, radial SBS),

[0321] 23% Dercolyte A115 (tackifying resin, EP: 115°C, α-pinene)

[0322] 30% Foral 105 (tackifying resin, EP 105°C, hydrogenated pentaerythritol ester-rosin, high polarity),

[0323] 3% of Wingtack 10 (plasticizer resin, EP 10°C, fl. C5 resin), 0.5% of Irganox 1010 (primary antioxidant), 0.5% of Irgafos 168 (secondary antioxidant) are mixed with a solvent (e.g. acetone, special boiling point gasoline 60 / 95, toluene) and mixed with each other until a homogeneous solution is obtained. The figures expressed in % represent the weight percentage based on the total weight of the solvent-free base material composed of the above components. The total concentration of the pressure-sensitive adhesive in the solvent is 35% by weight.

[0324] 7% by weight of 1-ethyl-3-methylimidazolium tetrafluoroborate and 3.5% by weight of polyethylene glycol 400 were subsequently added, these amounts being based on 100% by weight of the previously prepared base substance.

[0325] The solution was coated onto a siliconized polyester carrier (siliconized liner) layer using a comma rod and then the solvent was released in a drying oven at 120° C. for 15 minutes. Before further use, the open side of the pressure-sensitive adhesive was covered with another siliconized polyester carrier (siliconized liner) layer.

[0326] After drying, the layer thickness of the pressure-sensitive adhesive layer was 50 μm.

[0327] The siliconized liner was removed. The exposed side of the pressure-sensitive adhesive was then laminated to the aluminized side of an aluminum-evaporated PET foil with a total thickness of 23 μm, resulting in a lateral overhang of 4 cm relative to the pressure-sensitive adhesive. Immediately before lamination, the aluminized side of the foil was corona treated (30 W*min / m 2 dosage).

[0328] The samples were stored at 23° C. and 50% relative humidity for 24 hours.

[0329] Subsequently, the adhesive force was measured according to the above method. The force was 7.1 N / cm.

[0330] Likewise, a corresponding comparative example V1 was prepared in the same manner except that 7 wt % of 1-ethyl-3-methylimidazolium tetrafluoroborate and 3.5 wt % of polyethylene glycol 400 were not added, and its adhesive force was tested according to the above method. The adhesive force was 9.3 N / cm.

[0331] To test the electrical separability, a duplicate sample of Example 1 according to the present invention described above was manufactured according to the above process, thus including the addition of 7 wt % 1-ethyl-3-methylimidazolium tetrafluoroborate and 3.5 wt % polyethylene glycol 400, and the electrical separability was tested again.

[0332] Here too, the exposed side of the pressure-sensitive adhesive was laminated to the aluminized side of an aluminum-evaporated PET foil having a total thickness of 23 μm, so that a lateral overhang of 4 cm relative to the pressure-sensitive adhesive resulted.

[0333] Subsequently, a voltage was applied, wherein a first alligator clip (jaws insulated with a rubber exterior) was applied with the positive pole to the protrusion and a second alligator clip was applied with the negative pole to the steel plate.

[0334] The voltage here was 12 V and was applied for 1 minute.

[0335] After one minute, the voltage was removed and the adhesion was immediately measured according to the method described above.

[0336] The adhesive force is only 4.9N / cm.

[0337] In terms of adhesive residue, the steel panels are residue-free.

[0338] Thus, surprisingly, adhesive layers based on polydiene block copolymers were successfully produced which were electrically separable and residue-free.

[0339] As shown in the adhesion and re-separability tests in Example 1 according to the present invention, the adhesion of the adhesive layer D to a substrate such as steel is large before the application of voltage, and is reduced to such a low value only by the application of voltage that the substrates can be more easily separated from each other.

[0340] Reference numerals list

[0341] 1 Adhesive layer D

[0342] 2 Conductive carrier layer T

[0343] 2a Free surface of the conductive carrier layer T

[0344] 3 Second adhesive layer C

[0345] 4First substrate A

[0346] 5 Second substrate B

[0347] 6 Second conductive carrier layer T'

[0348] 6a Free surface of the conductive carrier layer T'

[0349] 7 Third adhesive layer C'

Claims

1. A pressure-sensitive adhesive comprising at least one electrolyte and a base material, wherein the base material comprises at least one polydiene block copolymer and at least one tackifying resin.

2. The pressure-sensitive adhesive according to claim 1, characterized in that The electrolyte is selected from ionic liquids and metal salts, with ionic liquids being particularly preferred.

3. The pressure-sensitive adhesive according to claim 2, characterized in that The anion of the ionic liquid is selected from Br - 、AlCl4 - 、Al2Cl7 - 、NO3 - 、BF4 - PF6 - 、CH3COO - CF3COO - CF3CO3 - CF3SO3 - 、(CF3SO2)2N - 、(CF3SO2)3C - 、AsF6 - 、SbF6 - CF3(CF2)3SO3 - 、(CF3CF2SO2)2N - CF3CF2CF2COO - 、(FSO2)2N - , and in this case particularly preferably selected from (CF3SO2)2N - and (FSO2)2N - , and / or the cation of the ionic liquid is selected from imidazolium-based cations, pyridinium-based cations, pyrrolidine-based cations and ammonium-based cations, and in this case is particularly preferably selected from imidazolium-based cations, wherein the cation is particularly preferably selected from 1-ethyl-3-methylimidazolium and 1-butyl-3-methylimidazolium, wherein the cation is particularly preferably 1-ethyl-3-methylimidazolium.

4. The pressure-sensitive adhesive according to any one of the preceding claims, characterized in that The electrolyte is 1-ethyl-3-methylimidazolium tetrafluoroborate.

5. The pressure-sensitive adhesive according to any one of the preceding claims, characterized in that They comprise 2 to 10% by weight, preferably 4 to 9% by weight, of an electrolyte, preferably an ionic liquid, based on 100% by weight of the base substance.

6. The pressure-sensitive adhesive according to any one of the preceding claims, characterized in that The at least one polydiene block copolymer is a polyvinyl aromatic-polydiene block copolymer, preferably a polystyrene-polydiene block copolymer.

7. The pressure-sensitive adhesive according to any one of the preceding claims, characterized in that It contains at least one compatibilizer selected from polyethers, polyamines, polyvinyl pyrrolidone or aliphatic polyesters, wherein the compatibilizer preferably has a weight average molecular weight distribution M of 100 to 5000 g / mol, particularly preferably 200 to 2000 g / mol. w .

8. The pressure-sensitive adhesive according to any one of the preceding claims, characterized in that The tackifying resin is selected from rosin resins and terpene phenol resins, among which hydrogenated resins based on pentaerythritol esters esterified with rosin are particularly preferred.

9. An adhesive tape comprising an adhesive layer D of the adhesive according to any one of claims 1 to 8.

10. The adhesive tape according to claim 9, characterized in that The adhesive tape is a transfer tape and consists of the adhesive layer D.

11. The adhesive tape according to claim 9, characterized in that It further 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.

12. The adhesive tape according to claim 9, characterized in that It further comprises at least the following layers: A second adhesive layer C; and at least one first electrically conductive carrier layer T arranged between layers D and C; and at least one second electrically conductive carrier layer T′ arranged on the face of said adhesive layer D opposite to the first electrically conductive carrier layer T; and • A third adhesive layer C' arranged on the side of the second carrier layer T' opposite the first adhesive layer D.

13. A bonded composite comprising at least the following layers: A first substrate A; and A second substrate B; and The adhesive tape according to any 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 each other.

14. A method for the electrical separation of the complex according to claim 13, comprising at least the following method steps: i.) applying a voltage at two different sites of the complex, wherein the voltage is preferably 2 to 50V.

15. Use of the adhesive 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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