Adhesive compound, adhesive tape, bonded composite and method for electrically debonding bonded composite

Abstract

The invention relates to an adhesive compound, an adhesive tape, a bonded composite, a method for electrically debonding a bonded composite, and the use of the adhesive compound for bonding components in electronic, motor, medical and dental devices. The invention relates to an adhesive compound comprising a base compound and at least one electrolyte wherein the base compound comprises at least one first phase (i) comprising at least one poly (meth) acrylate and at least one second phase (ii) comprising at least one vinyl aromatic block copolymer, such as, in particular, a styrene block copolymer, wherein the adhesive compound comprises at least 2.5 parts by weight of electrolyte, based on 100 parts by weight of the base compound.

Description

TECHNICAL FIELD

[0001] The present invention relates to an adhesive compound, an adhesive tape, a bonded composite, a method for electrically debonding a bonded composite, and the use of the adhesive compound for bonding components in electronic devices, motor vehicles, medical devices and dental devices. BACKGROUND

[0002] Recently, there is a growing interest in "on-demand debonding" functionality, driven by environmental regulations and customer awareness of sustainability and increasing cost pressure in production. The use scenarios for debonding processes are classified as rework, repair, recycling and processing aids.

[0003] Debonding technologies aim at achieving either cohesive splitting in the adhesive layer or adhesive detachment of the adhesive layer from the substrate. The former, however, requires cleaning of the substrate prior to re-bonding, while in the latter case this is not necessary.

[0004] However, adhesive debonding technologies that guarantee the required high and durable reliable bonding strength are often relatively difficult to achieve, or their application, for example debonding using a penetrating solvent, is very time-consuming.

[0005] For example, especially in rework or repair of electronic devices such as smartphones and tablets, the currently employed main cohesive splitting adhesive bonds, typically in the form of pressure sensitive adhesive tapes, have their cohesion reduced by temperature increase to such an extent that manual, cohesive detachment for bonding is possible. This leads to a large amount of rework in order to prepare the substrate surface contaminated with adhesive residues for re-bonding.

[0006] In addition to heat-mediated debonding methods, electric debonding methods are also being discussed. For example, EP 3031875 B1 discloses reducing the adhesive strength of an acrylate adhesive compound by applying a voltage.

[0007] However, in addition to the electrically debondable property by applying a voltage, the initial adhesive strength and the high shear strength are also desirable for the applicability of the debondable adhesive compound in electronic devices. SUMMARY

[0008] It was therefore an object of the present invention to provide an adhesive compound which can be electrically debonded and at the same time has a high initial adhesive strength and a good or improved shear strength, more particularly static and dynamic shear strength. At the same time, the re-debonding should be possible as easily and cleanly as possible. An additional object was to provide a corresponding advantageous adhesive tape.

[0009] A further object was to specify a bonded composite and a method for re-debonding an adhesive bond produced from an adhesive compound or adhesive tape.

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

[0011] The above objects are achieved by the subject matter of the present application as defined in the claims. Preferred configurations of the present application result from the further dependent claims and the statements below.

[0012] Embodiments specified below as preferred are particularly preferred embodiments in combination with the features of other embodiments specified as preferred. Thus, very particularly preferred are combinations of two or more of the embodiments specified below as particularly preferred. Also preferred are embodiments in which the features of one embodiment specified as preferred in any preferred level are combined with one or more other features of other embodiments specified as preferred in any preferred level. Thus, the present application comprises combinations of individual features with each other and also with different preferred levels in said combinations. For example, the present application comprises a combination of a first feature specified as "preferred" with a second feature specified as "particularly preferred". This also encompasses different levels of preference for the subject matter mentioned in the context of "embodiments". Preferred features of the adhesive tape, the bonded composite, and also the use and the method result from the features of the preferred adhesive compound. Preferred features of the bonded composite, the use and the method also result from the features of the preferred adhesive tape.

[0013] The adhesive compound of the present application comprises a base compound and at least one electrolyte, wherein the base compound comprises at least one first phase (i) and at least one second phase (ii), the first phase (i) comprising at least one poly(meth)acrylate (poly(meth)acrylic acid compound, poly(meth)acrylic acid / ester), the second phase (ii) comprising at least one vinyl aromatic block copolymer, for example in particular a styrene block copolymer, wherein the adhesive compound contains at least 2.5 parts by weight of electrolyte, based on 100 parts by weight of the base compound.

[0014] Due to the presence of the electrolyte, the adhesive compound can be electrically detached from the bonded substrates without major force in a simple and fast manner by applying a voltage, even after the bonding.

[0015] It was unexpectedly found that an adhesive compound comprising a blend of at least one first phase (i) comprising at least one poly(meth)acrylate and at least one second phase (ii) comprising at least one vinyl aromatic block copolymer and at least one electrolyte can be electrically re-detached from bonded substrates without major force in a simple and fast manner by applying a voltage and at the same time improves the dynamic and static shear strength of the adhesive compound. Furthermore, the adhesive compound has a high adhesive strength before applying the voltage.

[0016] Adhesive compounds and methods for electrically redetachability and for electrically reducing the adhesive strength are known in principle from the prior art. For example, as mentioned above, EP 3031875 B1 discloses such an electric method. In this case, the electrically detachable adhesive compound is an acrylate-based adhesive compound.

[0017] However, it was not foreseeable in the present case that an adhesive compound comprising a blend of acrylate (acrylate compound, methacrylate) and a vinyl aromatic block copolymer can also be electrically detached after bonding and does not adversely affect the adhesive strength to the substrates to be bonded before debonding. In particular, an adhesive compound with a vinyl aromatic block copolymer having nonpolar properties due to a high proportion of hydrocarbon compounds cannot be assumed at all to be combinable with an electrolyte in a form which not only achieves attractive adhesive properties, in particular pressure-sensitive adhesive properties, but also allows detachment by the application of a voltage.

[0018] The detachment is at the same time clean and easy.

[0019] Furthermore, it was not foreseeable that the adhesive compound of the present application will have both improved static and dynamic shear strength.

[0020] The adhesive compound of the present application is set out more specifically hereinafter.

[0021] The adhesive compound comprises a base compound and at least one electrolyte in an amount related to the amount of the base compound.

[0022] According to the general understanding of the person skilled in the art, an "electrolyte" is understood in the present case 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.

[0023] The electrolyte is preferably selected from the group consisting of ionic liquids and metal salts, particularly preferably ionic liquids.

[0024] In particular, the adhesive tape can be easily redetached by one or more ionic liquids as electrolyte without adversely affecting the adhesive properties of the adhesive tape. Ionic liquids have the advantage here of being easily and uniformly dispersible in the polymer matrix of the adhesive compound, and redetachment occurs more quickly than in the case of the use of other electrolytes.

[0025] Furthermore, the constituents of ionic liquids are non-volatile, in particular at room temperature. Furthermore, ionic liquids are relatively heat-resistant and not flammable and are chemically relatively stable.

[0026] In the context of this invention, an ionic liquid is a salt that is liquid at room temperature, i.e., 23°C. Ionic liquids therefore contain both anions and cations.

[0027] Therefore, in the context of the separation method / method for electro-debinding of the present invention, ionic liquids are particularly well suited as electrolytes.

[0028] When a voltage is applied, anions migrate to the anode side and cations migrate to the cathode side. Undesirably, this can be mechanistically assumed to result in a decrease in the adhesive strength of the adhesive compound containing the ionic liquid to at least one substrate, thereby causing adhesive separation between the adhesive compound and at least one substrate.

[0029] In the context of this invention, all ionic liquids are applicable in principle.

[0030] The ionic liquids used in the context of this invention comprise at least one anion and at least one cation. It is also conceivable that the ionic liquids comprise two or more types of anions and / or two or more types of cations. It is also conceivable to add two or more different ionic liquids to an adhesive formulation, or for an adhesive formulation to then comprise two or more different ionic liquids.

[0031] Preferably, the anions of the ionic liquid are selected from:

[0032] Br - AlCl4 - Al2Cl7 - NO3 - BF4 - PF6 - CH3COO - CF3COO - CF3CO3 - CF3SO3 - (CF3SO2)2N - (CF3SO2)3C - AsF6 - SbF6 - CF3(CF2)3SO3 - (CF3CF2SO2)2N - , CF3CF2CF2COO - , N(CN)2 - , and (FSO2)2N - .

[0033] Particularly preferred, the anion is selected from (CF3SO2)2N - N(CN)2- (FSO2)2N - PF6 - and tetrafluoroborate (BF4) - ).

[0034] By applying voltage, this achieves a particularly high reduction in the adhesive strength of the adhesive formulation or tape of the present invention, and therefore particularly good electrodegradability. In particular, the anion achieves particularly rapid (re)degradation without leaving any residue.

[0035] Alternatively, the anions of the ionic liquid are preferably selected from:

[0036] Br - AlCl4 - Al2Cl7 - NO3 - BF4 - PF6 - CH3COO - CF3COO - CF3CO3 - CF3SO3 - (CF3SO2)2N - (CF3SO2)3C - AsF6 - SbF6 - CF3(CF2)3SO3 - (CF3CF2SO2)2N - , CF3CF2CF2COO - , and (FSO2)2N - .

[0037] Alternatively, the anion is particularly preferably selected from (CF3SO2)2N. - (FSO2)2N - PF6 - and tetrafluoroborate (BF4) - ).

[0038] By applying voltage, this achieves a particularly high reduction in the adhesive strength of the adhesive formulation or tape of the present invention, and therefore particularly good electrodegradability. In particular, the anion achieves particularly rapid (re)degradation without leaving any residue.

[0039] Preferably, the cation of the ionic liquid is selected from imidazolium-based cations, pyridinium-based cations, pyrrolidine-based cations, and ammonium-based cations.

[0040] Particularly preferred, the cation is selected from imidazolium-based cations.

[0041] By applying voltage, this achieves a particularly high reduction in the adhesive strength of the adhesive formulation or tape of the present invention, and therefore particularly good electrodegradability. In particular, the anion achieves particularly rapid (re)degradation without leaving any residue.

[0042] Very particularly preferred, the cation is selected from 1-ethyl-3-methylimidazolium and 1-butyl-3-methylimidazolium.

[0043] Even more preferably, the cation is 1-ethyl-3-methylimidazolium.

[0044] Particularly preferred, the electrolyte is selected from ionic liquids 1-ethyl-3-methylimidazolium dicyandiamide, 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide (EMIM-TFSI), 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide (EMIM-FSI), 1-butyl-3-methylimidazolium hexafluorophosphate, and 1-ethyl-3-methylimidazolium tetrafluoroborate.

[0045] By applying voltage, this achieves a particularly high reduction in the adhesive strength of the adhesive formulation or tape of the present invention, and therefore particularly good electrodegradability. In particular, the anion achieves particularly rapid (re)degradation without leaving any residue.

[0046] Alternatively, the electrolyte is particularly preferably selected from ionic liquids 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide (EMIM-TFSI), 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide (EMIM-FSI), 1-butyl-3-methylimidazolium hexafluorophosphate and 1-ethyl-3-methylimidazolium tetrafluoroborate.

[0047] Very particularly preferred are 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide (EMIM-TFSI) and / or 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide (EMIM-FSI).

[0048] Even more preferred is 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide (EMIM-FSI).

[0049] Based on 100 parts by weight of the base compound, the adhesive compound of the present invention contains at least 2.5 parts by weight of electrolyte.

[0050] Preferably, based on 100 parts by weight of the base compound, the adhesive compound contains 2.5 to 10 parts by weight, more preferably 2.5 to 8 parts by weight of an electrolyte, preferably an ionic liquid.

[0051] The preferred or particularly preferred amount of electrolyte, especially ionic liquid, makes relatively rapid electrodesorption possible, while at the same time, this does not have any adverse effect on the adhesion of the adhesive compound to, in particular, at least one substrate, before desorption.

[0052] The adhesive formulations of the present invention comprise a base formulation comprising at least one first phase (i) and at least one second phase (ii), the first phase (i) comprising at least one poly(meth)acrylate and the second phase (ii) comprising at least one vinyl aromatic block copolymer (e.g., particularly styrene block copolymer).

[0053] As can be deduced from the term "phase," phases (i) and (ii) exist separately from each other and side by side in adhesive formulations.

[0054] Poly(meth)acrylate and vinyl aromatic block copolymers exist as separate phases surrounding each other in the adhesive formulations of the present invention.

[0055] Specifically, the vinyl aromatic block copolymer may be dispersed in the poly(meth)acrylate, thereby forming domains in the poly(meth)acrylate matrix, or conversely, the poly(meth)acrylate may be dispersed in the vinyl aromatic block copolymer, thereby forming domains in the vinyl aromatic block copolymer matrix. The above description similarly applies to the cases where phase (i) comprises more than one poly(meth)acrylate, particularly two or more poly(meth)acrylates, and / or phase (ii) comprises more than one vinyl aromatic block copolymer, particularly two or more vinyl aromatic block copolymers.

[0056] The poly(meth)acrylate and vinyl aromatic block copolymers present in the adhesive formulation are preferably selected such that they are not homogeneously miscible with each other at 23°C. Therefore, the adhesive formulation of the present invention preferably exists in at least two phases, at least microscopically and at least at room temperature. Particularly preferably, the poly(meth)acrylate (one or more) and vinyl aromatic block copolymer (one or more) are not homogeneously miscible with each other in a temperature range of 0°C to 50°C, particularly -30°C to 80°C, such that the adhesive formulation exists in at least two phases, at least microscopically, within these temperature ranges.

[0057] For the purposes of this document, a component is defined as “not homogeneous miscible with each other” when, even after close mixing, the formation of at least two stable phases can be physically and / or chemically detected at least microscopically, one phase being rich in one component and the second phase being rich in another component. The presence of negligible amounts of one component in the other components that do not impede the development of multiphase characteristics is hereby considered negligible. For example, small amounts of vinyl aromatic block copolymers may be present in the poly(meth)acrylate phase and / or small amounts of poly(meth)acrylate may be present in the vinyl aromatic block copolymer phase, provided that these amounts are not significant amounts affecting phase desorption.

[0058] Phase separation can be particularly achieved, such that discrete regions (“domains”) rich in vinyl aromatic block copolymers (i.e., formed essentially of vinyl aromatic block copolymers) exist within a continuous matrix rich in poly(meth)acrylates (i.e., formed essentially of poly(meth)acrylates).

[0059] An example of a suitable analytical system for phase separation is a scanning electron microscope. However, phase separation can also be identified, for example, by different phases having two independent glass transition temperatures in differential scanning calorimetry (DSC) or dynamic mechanical analysis (DMA). Phase separation exists according to the invention when it can be clearly demonstrated by at least one analytical method.

[0060] Within the domain rich in vinyl aromatic block copolymers, further multiphase structures can exist as fine structures, wherein vinyl aromatic block copolymers typically have A blocks and B blocks, and thus the A blocks form the first phase and the B blocks form the second phase.

[0061] Preferably, phase (ii) in the adhesive formulation of the present invention, and thus the vinyl aromatic block copolymer, exists in a dispersed form in phase (i) and therefore in the poly(meth)acrylate. Therefore, phases (i) and (ii) themselves are preferably homogeneous.

[0062] Preferably, based on the total weight of phase (i), phase (i) comprises 60% to 99.5% by weight, preferably 70% to 85% by weight, of poly(meth)acrylate.

[0063] Preferably, phase (ii) comprises 90% to 100% by weight of a vinyl aromatic block copolymer, based on the total weight of phase (ii).

[0064] Preferably, the base mixture contains 51% to 90% by weight, preferably 60% to 80% by weight, of phase (i) and 10% to 49% by weight, preferably 20% to 40% by weight, of phase (ii), the weight fractions of which preferably add up to 100%, which correspondingly preferably means that there are no other additives not dispersed in phases (i) and (ii).

[0065] This results in the particularly good achievement of the objectives of the present invention.

[0066] Preferably, the base blend contains 40% to 70% by weight, more preferably 45% to 60% by weight, of at least one poly(meth)acrylate in phase (i) and 15% to 50% by weight of at least one vinyl aromatic block copolymer in phase (ii), based on the total weight of the base blend in each case.

[0067] The object of the invention is particularly well achieved when the preferred amounts of polymer in the total amount of the adhesive compound or in each phase are taken into account.

[0068] "Poly(meth)acrylate" is understood to mean a polymer preferably obtainable by free radical polymerization of acrylic and / or methacrylic monomers and optionally other copolymerizable monomers. Specifically, "poly(meth)acrylate" is understood to mean a polymer whose monomer base consists, to a certain extent, at least 50% by weight of acrylic acid, methacrylic acid, acrylates, and / or methacrylates, wherein the acrylates and / or methacrylates are present in at least a certain proportion, preferably at least 30% by weight, based on the total monomer base of the polymer in question.

[0069] The glass transition temperature of the poly(meth)acrylate of the adhesive formulation of the present invention, as determined by DSC (as described below "DSC" in the Test Methods section), is preferably <0°C, more preferably -5 to -50°C (between -5 and -50°C).

[0070] This achieves particularly good flow-on behavior and good reformability in adhesive formulations, especially with the addition of suitable tackifier resins in specific cases.

[0071] The glass transition temperature of poly(meth)acrylate is mainly determined by the choice of monomers.

[0072] Preferably, the poly(meth)acrylate of the adhesive formulation contains at least a certain proportion of functional monomers introduced by polymerization, and particularly preferably, monomers having at least one type of functional group selected from carboxylic acid group, sulfonic acid group, phosphonic acid group, hydroxyl group, acid anhydride group, epoxy group and amino group.

[0073] In addition to the epoxy group, the functional groups are reactive to the epoxy group, thereby advantageously facilitating the thermal crosslinking of the poly(meth)acrylate with the introduced epoxide.

[0074] Very particularly preferred, the poly(meth)acrylate of the adhesive formulation contains at least a certain proportion of functional monomers introduced by polymerization, particularly preferably monomers having at least one type of functional group selected from carboxylic acid groups and epoxy groups; in particular, it contains at least one carboxylic acid group.

[0075] According to a particularly advantageous embodiment, the poly(meth)acrylate of the adhesive formulation contains a certain proportion of acrylic acid and / or methacrylic acid introduced through polymerization. Therefore, the carboxylic acid groups make the poly(meth)acrylate reactive to epoxy groups, thereby advantageously facilitating the thermal crosslinking of the poly(meth)acrylate with the introduced epoxides.

[0076] The poly(meth)acrylate of the adhesive formulation can preferably be derived from the following monomer compositions:

[0077] a) at least one acrylate and / or methacrylate of formula (1)

[0078] CH2=C(R I (COOR) II (1),

[0079] Where R I =H or CH3 and R II It is an alkyl group having 4 to 18 carbon atoms;

[0080] b) At least one olefinic unsaturated monomer having at least one functional group selected from carboxylic acid group, sulfonic acid group, phosphonic acid group, hydroxyl group, acid anhydride group, epoxy group and amino group;

[0081] c) Optionally, other acrylates and / or methacrylates and / or olefinic unsaturated monomers that can be copolymerized with component (a).

[0082] According to an advantageous embodiment, the poly(meth)acrylate is based on a monomer composition comprising, in proportions of 25% to 99% by weight, more preferably 40% to 86% by weight, monomers of group a), in proportions of 1% to 15% by weight, more preferably 1% to 7% by weight, monomers of group b), and optionally 0% to 60% by weight, preferably 15% to 53% by weight, monomers of group c), wherein each amount is based on a monomer mixture of a polymer that does not contain any additional additives such as resins.

[0083] The presence of this poly(meth)acrylate in adhesive formulations achieves particularly good property characteristics, including tack, shear strength, and removability without residue.

[0084] According to a particularly advantageous embodiment of the invention, the poly(meth)acrylate is based on a monomer composition comprising 40% to 60% by weight of monomers from group a), 1% to 7% by weight of monomers from group b), and 33% to 53% by weight of monomers from group c), wherein the amounts are based on a monomer mixture of a polymer that does not contain any additional additives such as resins.

[0085] According to a particularly advantageous embodiment of the invention, the poly(meth)acrylate is based on a monomer composition comprising 50% to 86% by weight of monomers from group a), 1% to 7% by weight of monomers from group b), and 13% to 43% by weight of monomers from group c), wherein the amounts are based on a monomer mixture of a polymer excluding any additional additives such as resins.

[0086] According to a particularly advantageous embodiment of the invention, the poly(meth)acrylate is based on a monomer composition comprising 50% to 65% by weight of monomers from group a), 1% to 5% by weight of monomers from group b), and 34% to 45% by weight of monomers from group c), wherein the amounts are based on a monomer mixture of a polymer that does not contain any additional additives such as resins.

[0087] According to a particularly advantageous embodiment of the invention, the poly(meth)acrylate is based on a monomer composition comprising 75% to 86% by weight of group a) monomers, 1% to 5% by weight of group b) monomers, and 13% to 20% by weight of group c) monomers, wherein the amounts are based on a monomer mixture of a polymer excluding any additional additives such as resins.

[0088] The monomer in component a) is typically a relatively nonpolar monomer used for plasticizing. Particularly preferred is R in monomer a). II It is an alkyl group having 4 to 10 carbon atoms. The monomers of formula (1) are specifically selected from:

[0089] n-Butyl acrylate, n-Butyl methacrylate, n-Pentyl acrylate, n-Pentyl methacrylate, n-Amyl acrylate, n-Hexyl acrylate, n-Hexyl methacrylate, n-Heptyl acrylate, n-Octyl acrylate, n-Octyl methacrylate, n-Nonyl acrylate, Isobutyl acrylate, Isooctyl acrylate, Isooctyl methacrylate, 2-Ethylhexyl acrylate, 2-Ethylhexyl methacrylate, 2-Propylheptyl acrylate, and 2-Propylheptyl methacrylate.

[0090] Particularly preferably, the monomers of formula (1) / a) are selected from n-butyl acrylate, n-hexyl acrylate, n-octyl acrylate, isooctyl acrylate, 2-ethylhexyl acrylate and 2-propylheptyl acrylate.

[0091] The listed monomers are particularly easy to polymerize, and the glass transition temperature of the resulting poly(meth)acrylate is particularly easy to adjust. This, in turn, allows for the achievement of optimized properties regarding flowability and tack, which are also adjusted in accordance with the corresponding substrate or component to be bonded.

[0092] The monomers of formula (1) / a) are even more preferably selected from n-butyl acrylate, isooctyl acrylate and 2-ethylhexyl acrylate.

[0093] It is highly preferred to use n-butyl acrylate and 2-ethylhexyl acrylate as monomers of formula (1) / a).

[0094] According to a particularly advantageous implementation scheme, n-butyl acrylate is used as the monomer.

[0095] The monomers in group b) are particularly preferably selected from acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, crotonic acid, aconitic acid, dimethacrylic acid, β-acryloyloxypropionic acid, trichloroacrylic acid, vinylacetic acid, vinylphosphonic acid, maleic anhydride, hydroxyethyl acrylate, 2-hydroxyethyl acrylate, hydroxypropyl acrylate, 3-hydroxypropyl acrylate, hydroxybutyl acrylate, 4-hydroxybutyl acrylate, hydroxyhexyl acrylate, 6-hydroxyhexyl acrylate, hydroxyethyl methacrylate, 2-hydroxyethyl methacrylate, hydroxypropyl methacrylate, 3-hydroxypropyl methacrylate, hydroxybutyl methacrylate, 4-hydroxybutyl methacrylate, hydroxyhexyl methacrylate, 6-hydroxyhexyl methacrylate, allyl alcohol, glycidyl acrylate, and glycidyl methacrylate.

[0096] It is highly preferred to use acrylic acid as the monomer of group b).

[0097] Examples of monomers in component c) are:

[0098] Methyl acrylate, ethyl acrylate, propyl acrylate, methyl methacrylate, ethyl methacrylate, benzyl acrylate, benzyl methacrylate, sec-butyl acrylate, tert-butyl acrylate, phenyl acrylate, phenyl methacrylate, isobornyl acrylate, isobornyl methacrylate, tert-butyl acrylate, tert-butyl methacrylate, dodecyl methacrylate, isodecyl acrylate, lauryl acrylate, n-undecyl acrylate, stearyl acrylate, tridecyl acrylate, dodecyl acrylate (behenyl acrylate), cyclohexyl methacrylate, cyclopentyl methacrylate, phenoxyethyl acrylate, phenoxyethyl methacrylate, 2-butoxyethyl methacrylate 2-Butoxyethyl acrylate, 3,3,5-trimethylcyclohexyl acrylate, 3,5-dimethyladamantyl acrylate, 4-cumylphenyl methacrylate, cyanoethyl acrylate, cyanoethyl methacrylate, 4-biphenyl acrylate, 4-biphenyl methacrylate, 2-naphthyl acrylate, 2-naphthyl methacrylate, tetrahydrofurfuryl acrylate, diethylaminoethyl acrylate, diethylaminoethyl methacrylate, dimethylaminoethyl acrylate, dimethylaminoethyl methacrylate, methyl 3-methoxyacrylate, 3-methoxybutyl acrylate, 2-phenoxyethyl methacrylate, butyl glycol methacrylate, ethylene glycol acrylate, ethylene glycol monomethyl ether acrylate acrylate), methoxy polyethylene glycol methacrylate 350, methoxy polyethylene glycol methacrylate 500, propylene glycol monomethacrylate, butoxydiethylene glycol methacrylate, ethoxytriethylene glycol methacrylate, octafluoropentyl acrylate, octafluoropentyl methacrylate, 2,2,2-trifluoroethyl methacrylate, 1,1,1,3,3,3-hexafluoroisopropyl acrylate, 1,1,1,3,3,3-hexafluoroisopropyl methacrylate, 2,2,3,3,3-pentafluoropropyl methacrylate, 2,2,3,4,4,4-hexafluorobutyl methacrylate, 2,2 3,3,4,4,4-Hepanobutyl methacrylate, 2,2,3,3,4,4,4-Hepanobutyl methacrylate, 2,2,3,3,4,4,5,5,6,6,7,7,8,8,8-Pentadecylfluorooctyl methacrylate, Dimethylaminopropylacrylamide, Dimethylaminopropylmethacrylamide, N-(1-Methylundecyl)acrylamide, N-(n-Butoxymethyl)acrylamide, N-(Butoxymethyl)methacrylamide, N-(Ethoxymethyl)acrylamide, N-(n-Octadecyl)acrylamide, N,N-Dialkylsubstituted amides such as N,N-dimethylacrylamide and N,N-Dimethylmethacrylamide, N-Benzylacrylamide, N-Isopropylacrylamide, N-T-Butylacrylamide, N-T-Octylacrylamide, N-Hydroxymethylacrylamide, N-Hydroxymethylmethacrylamide, Acrylonitrile, Methacrylonitrile, Vinyl ethers, such as vinyl methyl ether, ethyl vinyl ether, vinyl isobutyl ether, Vinyl esters, such as vinyl acetate, Haloethylene, Vinylidene haloethylene, Vinylpyridine, 4-Vinylpyridine, N-Vinylphthalimide, N-Vinyl lactam, N-Vinylpyrrolidone, Styrene, α- and p-methylstyrene, α-Butylstyrene, 4-n-Butylstyrene, 4-n-Decylstyrene, 3,4-Dimethoxystyrene, Macromonomers, such as 2-Polystyrene ethyl methacrylate (weight-average molecular weight Mw of 4000 to 13000 g / mol as determined by GPC), poly(methyl methacrylate) ethyl methacrylate (Mw of 2000 to 8000 g / mol).

[0099] The monomers of component c) can also be advantageously selected such that they contain functional groups that facilitate subsequent radiochemical crosslinking (e.g., by electron beam or UV irradiation). Suitable copolymerizable photoinitiators are, for example, benzoin acrylates and acrylate-functionalized benzophenone derivatives. Monomers that facilitate crosslinking via electron bombardment are, for example, tetrahydrofurfuryl acrylate and allyl acrylate.

[0100] Preferably, the monomers in group c) are selected from methyl acrylate and benzyl acrylate.

[0101] According to a preferred embodiment of the present invention, the monomers in group c) are selected from methyl acrylate and benzyl acrylate, and are also selected from polar monomers, preferably nitrogen-containing monomers.

[0102] Preferably, the poly(meth)acrylate is a polyacrylate produced by the polymerization of n-butyl acrylate and / or 2-ethylhexyl acrylate and / or methyl acrylate and / or benzyl (meth)acrylate and acrylic acid.

[0103] According to a particularly preferred embodiment, the poly(meth)acrylate is a polyacrylate produced by the polymerization of n-butyl acrylate, methyl acrylate, benzyl acrylate, and acrylic acid. Preferably, the corresponding monomer composition on which the above-mentioned poly(meth)acrylate is based contains 40% to 65% by weight of n-butyl acrylate and 1% to 5% by weight of acrylic acid, and a combination ratio of 34% to 55% by weight of methyl acrylate and benzyl acrylate, wherein the ratio of methyl acrylate to benzyl acrylate is preferably 1.5:1 to 1:1.5, particularly 1:1.

[0104] Therefore, the tape of the present invention has particularly high adhesive strength and high shear strength, and can be detached without leaving any residue.

[0105] According to a further preferred embodiment, the monomer composition further comprises a polar monomer, preferably at least one nitrogen-containing monomer.

[0106] "Nitrogen-containing monomer" is understood here to mean a compound that has at least one functional group including at least one nitrogen atom.

[0107] Preferably, the nitrogen-containing monomer of the monomer composition or at least one of the nitrogen-containing monomers is selected from nitrogen-containing (meth)acrylate (nitrogen-containing (meth)acrylate) monomers, vinylpyridine, 4-vinylpyridine, N-vinylphthalimide, N-vinyllactam, N-vinylpyrrolidone and N-vinylformamide.

[0108] Nitrogen-containing (meth)acrylate monomers are preferred. Therefore, the nitrogen-containing monomer or at least one nitrogen-containing monomer in the monomer composition is preferably a nitrogen-containing (meth)acrylate monomer.

[0109] "Nitrogen-containing (meth)acrylate monomer" is understood herein to mean a compound having at least one methacrylate or at least one acrylate functional group and additionally having a functional group including at least one nitrogen atom.

[0110] According to a preferred embodiment of the invention, at least one of the nitrogen-containing (meth)acrylate monomers or nitrogen-containing (meth)acrylate monomers in the monomer composition is selected from (meth)acrylamide, substituted (meth)acrylamide, amino (meth)acrylate, substituted amino (meth)acrylate, (meth)acrylonitrile, (meth)acrylate cyanoalkyl ester and 4-(meth)acryloyloxymorpholine.

[0111] According to a preferred embodiment of the present invention, at least one of the nitrogen-containing (meth)acrylate monomers or nitrogen-containing (meth)acrylate monomers in the monomer composition is selected from cyanoethyl acrylate, cyanoethyl methacrylate, diethylaminoethyl acrylate, diethylaminoethyl methacrylate, dimethylaminoethyl acrylate, dimethylaminoethyl methacrylate, dimethylaminopropylacrylamide, dimethylaminopropylmethacrylamide, N-(1-methylundecyl)acrylamide, N-(n-butoxymethyl)acrylamide, N-(butoxymethyl)methyl Acrylamide, N-(ethoxymethyl)acrylamide, N-(n-octadecyl)acrylamide; N,N-dialkyl-substituted amides, such as N,N-dimethylacrylamide, N,N-dimethylmethylacrylamide, N,N-diethylacrylamide and N,N-diethylmethylacrylamide, N-benzylacrylamide, N-isopropylacrylamide, N-tert-butylacrylamide, N-tert-octylacrylamide, N-hydroxymethylacrylamide, N-hydroxymethylmethylacrylamide, 4-(meth)acryloyloxymorpholine, acrylonitrile and methacrylonitrile.

[0112] According to a particularly advantageous embodiment, the monomer composition contains more than 15% by weight of at least one acrylamide as a nitrogen-containing (meth)acrylate monomer, preferably selected from dimethylaminopropylacrylamide, dimethylaminopropylmethacrylamide, N-(1-methylundecyl)acrylamide, N-(n-butoxymethyl)acrylamide, N-(butoxymethyl)methacrylamide, N-(ethoxymethyl)acrylamide, N-(n-octadecyl)acrylamide, N,N-dialkyl-substituted amides, such as N,N-dimethylacrylamide, N,N-dimethylmethacrylamide, N,N-diethylacrylamide and N,N-diethylmethacrylamide, N-benzylacrylamide, N-isopropylacrylamide, N-tert-butylacrylamide, N-tert-octylacrylamide, N-hydroxymethylacrylamide, and N-hydroxymethylmethacrylamide.

[0113] Very particularly preferred, at least one substituted acrylamide is present as a nitrogen-containing (meth)acrylate monomer selected from N,N-dimethylacrylamide (NNDMA) and N,N-diethylacrylamide (NNDEA).

[0114] According to a particularly advantageous embodiment, the monomer composition contains more than 15% by weight of the nitrogen-containing (meth)acrylate monomer N,N-dimethylacrylamide.

[0115] Particularly preferred, the poly(meth)acrylate is a polyacrylate produced by the polymerization of n-butyl acrylate and / or 2-ethylhexyl acrylate and / or methyl acrylate and / or benzyl (meth)acrylate and acrylic acid and at least one nitrogen-containing monomer, preferably N,N-dimethylacrylamide.

[0116] According to a particularly preferred embodiment, the poly(meth)acrylate is a polyacrylate produced by the polymerization of n-butyl acrylate, 2-ethylhexyl acrylate, N,N-dimethylacrylamide, and acrylic acid. Preferably, the corresponding monomer composition on which the above-mentioned poly(meth)acrylate is based contains 40% to 65% by weight of n-butyl acrylate, 1% to 5% by weight of acrylic acid, 10% to 25% by weight, preferably 15% to 25% by weight of N,N-dimethylacrylamide, and 20% to 35% by weight of 2-ethylhexyl acrylate.

[0117] Therefore, the tape of the present invention has particularly high adhesive strength and high shear strength, and can be detached without leaving any residue.

[0118] Poly(meth)acrylates are preferably prepared by conventional free radical polymerization or controlled free radical polymerization. Poly(meth)acrylates can be prepared by copolymerizing monomers using conventional polymerization initiators and optional chain transfer agents, wherein polymerization is carried out in bulk, in emulsion (e.g., in water or liquid hydrocarbons), or in solution at normal temperatures.

[0119] Poly(meth)acrylate is preferably prepared by copolymerization of monomers in a solvent, more preferably in a solvent with a boiling point range of 50 to 150°C, particularly 60 to 120°C, using a polymerization initiator of 0.01% to 5% by weight, particularly 0.1% to 2% by weight (based on the total weight of the monomers in each case).

[0120] In principle, all conventional initiators are suitable. Examples of radical sources are peroxides, hydroperoxides, and azo compounds, such as benzoyl peroxide, cumene hydroperoxide, cyclohexanone peroxide, di-tert-butyl peroxide, cyclohexylsulfonylacetyl peroxide, diisopropyl percarbonate, tert-butyl peroctanoate, and benzipineol. Preferred radical initiators are 2,2'-azobis(2-methylbutyronitrile) (Vazo® 67™ from DuPont) or 2,2'-azobis(2-methylpropionitrile) (2,2'-azobisisobutyronitrile; AIBN; Vazo® 64™ from DuPont).

[0121] Preferred solvents for the production of poly(meth)acrylates are alcohols, such as methanol, ethanol, n-propanol, isopropanol, n-butanol, and isobutanol, especially isopropanol and / or isobutanol; hydrocarbons, such as toluene, and especially gasoline with a boiling point range of 60-120°C; ketones, especially acetone, methyl ethyl ketone, and methyl isobutyl ketone; esters, such as ethyl acetate; and mixtures of the above solvents. Particularly preferred solvents are mixtures containing 2% to 15% by weight, especially 3% to 10% by weight, of isopropanol, depending on the solvent mixture used in each case.

[0122] Preferably, the production (polymerization) of poly(meth)acrylate is followed by a concentration step, and further processing of the poly(meth)acrylate is carried out substantially in the absence of solvents. The concentration of the polymer can be carried out in the absence of crosslinking agents and accelerators. However, it is also possible to add a compound from one of these categories to the polymerization product prior to concentration, such that concentration is then carried out in the presence of said substance.

[0123] The polymerization product can be transferred to a blender after the concentration step. Concentration and blending can also optionally be carried out in the same reactor.

[0124] The weight-average molecular weight M of poly(meth)acrylate wPreferably, the polymerization concentration is in the range of 20,000 to 2,000,000 g / mol, particularly preferably in the range of 100,000 to 1,500,000 g / mol, and very particularly preferably in the range of 150,000 to 1,200,000 g / mol. For this purpose, it may be advantageous to carry out the polymerization in the presence of a suitable polymerization chain transfer agent, such as a thiol, halogen compound, and / or alcohol, in order to adjust the desired average molecular weight.

[0125] Therefore, the preferred weight-average molecular weight M of the poly(meth)acrylate is... w The adhesive formulation has a concentration of 20,000 to 2,000,000 g / mol, particularly preferably 100,000 to 1,500,000 g / mol, and very particularly preferably 150,000 to 1,200,000 g / mol.

[0126] According to a preferred embodiment of the present invention, the M of poly(meth)acrylate w The values ​​range from 600,000 to 1,200,000 g / mol, particularly from 700,000 to 900,000 g / mol.

[0127] Poly(meth)acrylates preferably have a K value of 30 to 90, more preferably 40 to 80, as measured in toluene (1% solution, 21°C). The Fikentscher K value is a measure of the molecular weight and viscosity of the polymer.

[0128] Preferably, the poly(meth)acrylates of the adhesive formulations of the present invention have a polydispersity PD of <4 and therefore a relatively narrow molecular weight distribution. The formulations based on this exhibit particularly good shear strength after crosslinking, despite the relatively low molecular weight. Furthermore, the relatively low polydispersity allows for easier processing from the melt, as the flow viscosity is lower compared to poly(meth)acrylates with a wider distribution, while maintaining substantially the same performance characteristics. Poly(meth)acrylates with a narrow distribution can advantageously be prepared by anionic polymerization or by controlled free radical polymerization, the latter being particularly suitable. The corresponding poly(meth)acrylates can also be produced via N-oxygenation. It is also advantageous to synthesize poly(meth)acrylates with a narrow distribution using atom transfer radical polymerization (ATRP), preferably using monofunctional or bifunctional secondary or tertiary halides as initiators, employing complexes of Cu, Ni, Fe, Pd, Pt, Ru, Os, Rh, Co, Ir, Ag, or Au to abstract the halogen. RAFT polymerization is also suitable.

[0129] The poly(meth)acrylate of the adhesive formulation of the present invention is preferably crosslinked with a thermal crosslinking agent by means of the coupling reaction of the functional groups present therein—particularly in the sense of addition or substitution reaction. All thermal crosslinking agents can be used.

[0130] -Ensure a sufficiently long processing time so that gelation does not occur during processing, especially during extrusion.

[0131] This leads to the polymer rapidly post-crosslinking to the desired degree of crosslinking at temperatures below the processing temperature, especially at room temperature.

[0132] For example, polymers can be used in combination with the following as crosslinking agents: isocyanates containing carboxyl, amino, and / or hydroxyl groups, particularly aliphatic or blocked isocyanates, such as trimer isocyanates passivated with amines. Suitable isocyanates are, in particular, trimer derivatives of MDI [4,4-methylene di(phenyl)isocyanate], HDI [hexamethylene diisocyanate, 1,6-hexanediisocyanate], and IPDI [isophorone diisocyanate, 5-isocyano-1-isocyanomethyl-1,3,3-trimethylcyclohexane], such as products Desmodur® N3600 and XP2410 (both from Bayer AG: aliphatic polyisocyanates, low-viscosity HDI trimers). Also suitable are micronized, trimerized dispersions of IPDI BUEJ 339® (now HF9®) (Bayer AG) that have been surface-passivated.

[0133] It is also preferred that the crosslinking is performed via a complexing agent, also known as a chelate. A preferred complexing agent is, for example, aluminum acetylacetonate, which can be obtained from Sachen, for example, under the trade name Catana™ CAA 2072.

[0134] Preferably, the poly(meth)acrylate in the adhesive formulation of the present invention is crosslinked using an epoxide or one or more substances containing epoxy groups. The epoxy-containing substances are particularly polyfunctional epoxides, i.e., polyfunctional epoxides having at least two epoxy groups; therefore, this generally results in indirect coupling of the functionalized structural units of the poly(meth)acrylate. The epoxy-containing substances can be aromatic or aliphatic compounds.

[0135] Particularly suitable polyfunctional epoxides are oligomers of epichlorohydrins, epoxy ethers of polyols, particularly ethylene glycol, propylene glycol, and butanediol, polyethylene glycol, thiodiethylene glycol, glycerol, pentaerythritol, sorbitol, polyvinyl alcohol, polyallyl alcohol, etc.; and epoxy ethers of polyphenols, particularly resorcinol, hydroquinone, bis(4-hydroxyphenyl)methane, bis(4-hydroxy-3-methylphenyl)methane, bis(4-hydroxy-3,5-dibromo ... 5-Difluorophenyl)methane, 1,1-bis(4-hydroxyphenyl)ethane, 2,2-bis(4-hydroxyphenyl)propane, 2,2-bis(4-hydroxy-3-methylphenyl)propane, 2,2-bis(4-hydroxy-3-chlorophenyl)propane, 2,2-bis(4-hydroxy-3,5-dichlorophenyl)propane, 2,2-bis(4-hydroxy-3,5-dichlorophenyl)propane, bis(4-hydroxyphenyl)phenylmethane, bis(4-hydroxyphenyl)phenylmethane, bis(4-hydroxyphenyl) Diphenylmethane, bis(4-hydroxyphenyl)-4'-methylphenylmethane, 1,1-bis(4-hydroxyphenyl)-2,2,2-trichloroethane, bis(4-hydroxyphenyl)-(4-chlorophenyl)methane, 1,1-bis(4-hydroxyphenyl)cyclohexane, bis(4-hydroxyphenyl)cyclohexylmethane, 4,4'-dihydroxybiphenyl, 2,2'-dihydroxybiphenyl, 4,4'-dihydroxydiphenyl sulfone, and their hydroxyethyl ethers; phenol-aldehyde condensation products, such as phenol-alcohols and phenol-aldehyde resins; containing... Epoxides having both S and N, such as N,N-diglycidylaniline and N,N'-dimethyldiglycidyl-4,4-diaminodiphenylmethane, and epoxides prepared by standard methods from polyunsaturated or monounsaturated carboxylic acids; glycidyl esters; polyglycidyl esters, which can be obtained by polymerization or copolymerization of glycidyl esters of unsaturated acids, or from other acidic compounds, such as from cyanuric acid, diglycidyl sulfide, or cyclic trimethylene trisulfone or derivatives thereof.

[0136] Very suitable ethers are, for example, butane-1,4-diol diglycidyl ether, polyglycerol-3-glycidyl ether, cyclohexanediethanol diglycidyl ether, glycerol triglycidyl ether, neopentyl glycol diglycidyl ether, pentaerythritol tetraglycidyl ether, hexane-1,6-diol diglycidyl ether, polypropylene glycol diglycidyl ether, trimethylolpropane triglycidyl ether, pentaerythritol tetraglycidyl ether, bisphenol A diglycidyl ether, and bisphenol F diglycidyl ether.

[0137] Other preferred epoxides are alicyclic epoxides, such as methyl 3,4-epoxycyclohexanecarboxylic acid, which is available from Synesqo under the trade name Uvacure® 1500.

[0138] Further preferred epoxides are epoxy-functionalized organoalkoxysilanes, and particularly those selected from alicyclic epoxysilanes such as: (3-glycidoxypropyl)trimethoxysilane (CAS No. 2530-83-8, e.g., Dynasylan® GLYMO, Evonik), (3-glycidoxypropyl)triethoxysilane (CAS No. 2602-34-8, e.g., Dynasylan® GLYEO, Evonik), (3-glycidoxypropyl)methyldimethoxysilane (CAS No. 65799-47-5, e.g., Gelest Inc.), (3-glycidoxypropyl)methyldiethoxysilane (CAS No. 2897-60-1, e.g., Gelest Inc.), and 5,6-epoxyhexyltriethoxysilane (CAS No. 86138-01-4, e.g., Gelest Inc.). Inc.), 2-(3,4-epoxycyclohexyl)ethyl]trimethoxysilane (CAS No. 3388-04-3, e.g. Sigma-Aldrich), 2-(3,4-epoxycyclohexyl)ethyl]triethoxysilane (CAS No. 10217-34-2, e.g. ABCRGmbH), and triethoxy[3-[(3-ethyl-3-oxetane)methoxy]propyl]silane (CAS No. 220520-33-2, e.g. Aron Oxetane OXT-610, Toagosei Co., Ltd.). According to a preferred embodiment, (3-glycidyloxypropyl)triethoxysilane is used.

[0139] Preferably, the crosslinking agent is used to a total extent of 0.1% to 5% by weight, particularly to a extent of 0.2% to 1% by weight, based on the total weight of the polymer to be crosslinked.

[0140] The amount of crosslinking agent is not defined as part of the base mixture, but is added separately to the base mixture.

[0141] Particularly preferably, the poly(meth)acrylate is crosslinked by means of a crosslinking agent-accelerator system (“crosslinking system”) to obtain better control over processing time, crosslinking kinetics, and degree of crosslinking. The crosslinking agent-accelerator system preferably comprises at least one epoxy group-containing substance as a crosslinking agent and at least one substance as an accelerator that promotes the crosslinking reaction of the epoxy group-containing substance at temperatures below the melting temperature of the polymer to be crosslinked.

[0142] The epoxy-containing substances used as crosslinking agents preferably and particularly include the aforementioned epoxy-containing substances, and all the above statements apply to such substances.

[0143] According to the invention, amines are particularly preferred as promoters. These are formally understood to be substituted products of ammonia; in the following formula, the substituent is represented by "R" and particularly covers alkyl and / or aryl groups. Those amines that do not react with the polymer to be crosslinked or react only negligibly are particularly preferred.

[0144] In principle, primary amines (NRH2), secondary amines (NR2H), and tertiary amines (NR3) can all be selected as accelerators, including those having multiple primary and / or secondary and / or tertiary amines. Particularly preferred accelerators are tertiary amines, such as triethylamine, triethylenediamine, benzyldimethylamine, dimethylaminomethylphenol, 2,4,6-tris(N,N-dimethylaminomethyl)phenol, and N,N'-bis(3-(dimethylamino)propyl)urea. Other preferred accelerators are polyfunctional amines, such as diamines, triamines, and / or tetraamines, such as diethylenetriamine, triethylenetetramine, and trimethylhexamethylenediamine.

[0145] Other preferred accelerators are organosilanes containing at least one amino group and at least one alkoxy or acyl group. These allow for further improvements in product performance. In particular and preferably, the accelerator selected herein is at least one of the following organosilanes: N-cyclohexyl-3-aminopropyltrimethoxysilane (CAS No. 3068-78-8), N-cyclohexylaminomethyltriethoxysilane (CAS No. 26495-91-0), 3-aminopropyltrimethoxysilane (CAS No. 13822-56-5), 3-aminopropyltriethoxysilane (CAS No. 919-30-2), 3-aminopropylmethyldiethoxysilane (CAS No. 3179-76-8), 3-(2-aminomethylamino)propyltriethoxysilane (CAS No. 5089-72-5), 3-(N,N-dimethylaminopropyl)trimethoxysilane (CAS No. 2530-86-1), and bis(2-hydroxyethyl)-3-aminopropyltriethoxysilane (CAS No. 13822-56-5). 7538-44-5).

[0146] 3-Aminopropyltriethoxysilane (CAS No. 919-30-2) and / or 3-aminopropylmethyldiethoxysilane (CAS No. 3179-76-8) are particularly preferred.

[0147] Other preferred promoters are amino alcohols, especially secondary / or tertiary amino alcohols; when more than one amino functional group is present per molecule, it is preferred that at least one, more preferably all amino functional groups are secondary / or tertiary amino functional groups. Particularly preferred accelerators of this type are triethanolamine, N,N-bis(2-hydroxypropyl)ethanolamine, N-methyldiethanolamine, N-ethyldiethanolamine, 2-aminocyclohexanol, bis(2-hydroxycyclohexyl)methylamine, 2-(diisopropylamino)ethanol, 2-(dibutylamino)ethanol, N-butyldiethanolamine, N-butylethanolamine, 2-[bis(2-hydroxyethyl)amino]-2-(hydroxymethyl)-propane-1,3-diol, 1-[bis(2-hydroxyethyl)amino]-2-propanol, triisopropanolamine, 2-(dimethylamino)ethanol, 2-(diethylamino)ethanol, 2-(2-dimethylaminoethoxy)ethanol, N,N,N'-trimethyl-N'-hydroxyethyldiaminoethyl ether, N,N,N'-trimethylaminoethylethanolamine, and N,N,N'-trimethylaminopropylethanolamine.

[0148] Other suitable accelerators are pyridine, imidazoles (e.g., 2-methylimidazole), and 1,8-diazabicyclo[5.4.0]undec-7-ene. Alicyclic polyamines can also be used as accelerators. Phosphorus-based accelerators, such as phosphine and / or phosphonium compounds, such as triphenylphosphine or tetraphenylphosphonium tetraphenylborate, are also suitable.

[0149] Quaternary ammonium compounds can also be used as accelerators; examples are tetrabutylammonium hydroxide, hexadecyltrimethylammonium bromide, and benzalkonium chloride.

[0150] Preferably, such an accelerator is used in amounts ranging from 0.1% to 5% by weight, particularly from 0.2% to 1% by weight, based on the total weight of the polymer to be crosslinked. The amount of accelerator is not defined as part of the base mixture, but is added separately to the base mixture.

[0151] Vinyl aromatic block copolymers can, in principle, be any type known to those skilled in the art.

[0152] Vinyl aromatic block copolymers preferably have structures AB, ABA, or (AB). n (AB) n X or (ABA) n X,

[0153] In it

[0154] -A blocks are polymers formed independently by the polymerization of at least one vinyl aromatic compound;

[0155] -B blocks are each independently polymers formed by polymerization of conjugated dienes and / or isobutylenes having 4 to 18 carbon atoms, or partially or fully hydrogenated derivatives of such polymers.

[0156] -X is a group in the coupling agent or initiator, and

[0157] -n is an integer ≥2.

[0158] Suitable coupling agents and initiators are known to those skilled in the art.

[0159] More specifically, all the vinyl aromatic block copolymers in the adhesive formulations of the present invention are block copolymers having the structure detailed above. Therefore, the adhesive formulations of the present invention may also comprise mixtures of different block copolymers having the above-described structure.

[0160] Therefore, preferred vinyl aromatic block copolymers comprise one or more rubbery blocks B (soft blocks) and one or more glassy blocks A (hard blocks). Particularly preferably, at least one vinyl aromatic block copolymer in the adhesive formulations of the present invention is a block copolymer having an AB, ABA, (AB)3X, or (AB)4X structure, wherein A, B, and X are as defined above. Very particularly preferably, all vinyl aromatic block copolymers in the adhesive formulations of the present invention are block copolymers having an AB, ABA, (AB)3X, or (AB)4X structure, wherein A, B, and X are as defined above. In particular, at least one vinyl aromatic block copolymer in the adhesive formulations of the present invention is a mixture of block copolymers having an AB, ABA, (AB)3X, or (AB)4X structure, preferably comprising at least a diblock copolymer AB and / or a triblock copolymer ABA.

[0161] Block copolymers derived from A and B blocks may contain the same or different B blocks.

[0162] According to a preferred embodiment, the block copolymer has a linear ABA structure as described above.

[0163] According to another embodiment, a radial block copolymer, namely (AB)3X or (AB)4X, is preferred.

[0164] According to a preferred embodiment, the AB diblock copolymer is present as an additional component.

[0165] All of the above polymers can be used individually or in mixtures with each other.

[0166] A-blocks, particularly glassy blocks, have a preferred glass transition temperature (T0) above room temperature. gParticularly preferred, the T-cell of the glassy segment. g The temperature is at least 40°C, particularly at least 60°C, very particularly preferably at least 80°C, and most preferably at least 100°C. The proportion of vinyl aromatic block A in the total block copolymer is preferably from 10% to 40% by weight, more preferably from 10% to 20% by weight. The vinyl aromatic compound used to form block A preferably includes styrene and α-methylstyrene. Therefore, block A can be in the form of a homopolymer or a copolymer.

[0167] Particularly preferred, block A is polystyrene.

[0168] The at least one vinyl aromatic block copolymer is preferably at least one styrene block copolymer.

[0169] Block B is particularly a rubbery block or soft block having a Tg preferably below room temperature. The Tg of the soft block is particularly preferably less than 0°C, especially less than -10°C, for example less than -40°C, and very particularly preferably less than -60°C.

[0170] Preferred conjugated dienes used as monomers for the soft block B are particularly selected from butadiene, isoprene, ethylbutadiene, phenylbutadiene, pentadiene, hexadiene, ethylhexadiene, dimethylbutadiene, and farnesene isomers, as well as any desired mixtures of these monomers. The B block may also be in the form of a homopolymer or copolymer.

[0171] Particularly preferably, the conjugated diene used as the monomer for soft block B is selected from butadiene and isoprene. For example, soft block B is polyisoprene, polybutadiene, or a partially or fully hydrogenated derivative of one of these polymers, such as, in particular, polybutene-butadiene, or a polymer formed from a mixture of butadiene and isoprene. Very particularly preferably, block B is polyisoprene.

[0172] Especially when polyisoprene is used as a B-block, the adhesive compound exhibits high shear strength.

[0173] According to a particularly preferred embodiment, at least one polyvinyl aromatic compound-polydiene block copolymer is a styrene-butadiene-styrene block copolymer (SBS) or a styrene-isoprene-styrene block copolymer (SIS), especially a styrene-isoprene-styrene block copolymer (SIS).

[0174] Suitable styrene-isoprene-styrene block copolymers (SIS) containing a linear styrene-isoprene-styrene structure are available, for example, from Versalis under the trade name Europrene® SOL T 190.

[0175] According to a preferred embodiment, the adhesive formulation of the present invention includes at least one tackifier resin in the base formulation.

[0176] Based on the general understanding of those skilled in the art, "tackifier resin" is understood to mean an oligomeric or polymeric resin that increases the adhesiveness (adhesive strength) of an adhesive compound compared to an adhesive compound that does not contain any tackifier resin but is otherwise identical.

[0177] According to a preferred embodiment, the tackifier resin is present in phase (i) and is therefore a tackifier resin compatible with the at least one poly(meth)acrylate.

[0178] "Tackifier resins compatible with poly(meth)acrylate" are understood to mean tackifier resins that cause a change in the glass transition temperature (Tg) of the system obtained after a thorough mixing of poly(meth)acrylate and the tackifier resin compared to pure poly(meth)acrylate, and where only one Tg is attributable to the mixture of poly(meth)acrylate and the tackifier resin. Tackifier resins incompatible with poly(meth)acrylate will result in a system obtained after a thorough mixing of poly(meth)acrylate and the tackifier resin having two Tg values, one attributable to the poly(meth)acrylate and the other to the resin domain. Tg was determined calorimetrically in this paper by DSC (differential scanning calorimetry).

[0179] The tackifier resin compatible with poly(meth)acrylate preferably has a DACP value of less than 0°C, very preferably at most -20°C, and / or preferably less than 40°C, very preferably at most 30°C.

[0180] Particularly preferred is that the tackifying resin compatible with poly(meth)acrylate is selected from rosin derivatives, particularly rosin esters, (meth)acrylate resins and terpene-phenol resins.

[0181] (Meth)acrylate resins are particularly preferred. This is especially beneficial for improving adhesion to polar adhesive substrates. The adhesive formulations of the present invention may also contain a mixture of more than one tackifier resin. Suitable resins are available from Dow under the trade name Paraaloid™ DM-55.

[0182] The total amount of tackifier resin in the base compound is preferably 5% to 20% by weight, and particularly preferably 10% to 20% by weight.

[0183] Within the range of the total amount of tackifier resin, the adhesive blend exhibits very good shear strength and attractive adhesive strength, while still maintaining electrical re-detachability. Therefore, within the range of amounts resulting from the lower and upper limits of the selected higher preferred levels, the adhesive blend is further optimized in terms of the conflicting objectives of adhesive strength, shear strength, and re-detachability.

[0184] According to a further preferred embodiment, the adhesive formulation of the present invention does not include a tackifying resin, that is, it neither includes a tackifying resin in the base formulation nor additionally includes a tackifying resin. According to these embodiments, crosslinking is preferably performed via a complexing agent such as aluminum acetylacetonate.

[0185] In addition to the aforementioned components, the basic formulation of the adhesive compound of the present invention may also contain other components.

[0186] Particularly preferably, the base compound further comprises at least one filler.

[0187] According to a preferred embodiment of the invention, the amount of filler present as part of the base compound, i.e., based on the total weight of the base compound, is 0.3% to 5% by weight, preferably 0.5% to 2% by weight.

[0188] According to a preferred embodiment, the filler is selected from microspheres.

[0189] "Microspheres" are understood to refer to hollow microspheres that are elastic and therefore expandable in their ground state, and have a thermoplastic polymer shell. These beads are filled with a low-boiling-point liquid or liquefied gas. The shell material used is, in particular, polyacrylonitrile, PVDC, PVC, or polyacrylate. Suitable low-boiling-point liquids or gases are, in particular, hydrocarbons of lower alkanes, such as isobutane or isopentane, which are encapsulated in the polymer shell as liquefied gas under pressure; isopentane is particularly preferred.

[0190] The action on the microspheres, particularly through heat, softens the outer polymer shell. Simultaneously, the liquid propellant gas within the shell transforms into its gaseous state. This leads to the irreversible elongation and three-dimensional expansion of the microspheres. Expansion ceases when the internal and external pressures are equal. Because the polymer shell is retained, a closed-cell foam is achieved.

[0191] Several types of microspheres are commercially available, differing fundamentally in their size (6 to 45 μm in diameter in the unexpanded state) and their required onset temperature for expansion (75 to 220 °C). Examples of commercially available microspheres are the Expancel® DU type (DU = dry and unexpanded) from Nuryon and the Microsphere® FN type from Matsumoto.

[0192] It is also possible to distinguish between expandable (and therefore unexpanded) microspheres and pre-expanded microspheres.

[0193] In the context of this invention, it is conceivable in principle to use unexpanded and / or pre-expanded microspheres.

[0194] Here, unexpanded microspheres are typically added to the unexpanded mixture, and expansion then occurs, particularly by heating.

[0195] Unexpanded microsphere products can also be obtained as aqueous (aqueous) dispersions with a solids / microsphere content of about 40% to 45% by weight, and additionally as polymer-bonded microspheres (masterbatches), for example, with a microsphere concentration of about 65% by weight in ethylene-vinyl acetate. Like DU products, both microsphere dispersions and masterbatches are suitable for preparing foamed adhesive formulations.

[0196] According to an advantageous embodiment, the microspheres are expandable and used without expansion in the adhesive formulation. It is further preferred that the microspheres neither expand in the adhesive formulation nor in the adhesive formulation layer of the tape of the present invention formed therefrom. Therefore, the tape of the present invention preferably includes unexpanded microspheres in an electrically detachable adhesive formulation layer.

[0197] Microspheres typically have an inorganic layer on their surface for stabilization. This can be, for example, silicates or aluminosilicates. However, carbonates such as calcium carbonate, or various oxides can also be used.

[0198] In the context of this invention, it is surprisingly found that, preferably, when using unexpanded microspheres having a layer of magnesium hydroxide (Mg(OH)2) on their surface, an electrolyte-containing, electrically detachable adhesive formulation for this purpose is obtained, which has good adhesive strength and good shear strength, and at the same time has high corrosion resistance.

[0199] Preferably, the adhesive formulation accordingly includes at least one filler in the base formulation, said filler being selected from unexpanded microspheres having a layer of magnesium hydroxide (Mg(OH)2) on their surface.

[0200] Therefore, the tape of the present invention preferably includes unexpanded microspheres having a magnesium hydroxide (Mg(OH)2) layer on its surface in an electrically detachable adhesive compound layer.

[0201] According to a preferred embodiment of the invention, the amount of unexpanded microspheres having a magnesium hydroxide (Mg(OH)2) layer on their surface is 0.3% to 5% by weight, particularly preferably 0.5% to 2% by weight, as part of the base mixture, i.e., based on the total weight of the base mixture.

[0202] According to other preferred embodiments, the filler is magnesium hydroxide.

[0203] To adjust for other properties, the base mixture may contain additional additives. However, they are preferably present in a proportion not exceeding 18% by weight, and more preferably not exceeding 10% by weight of the base mixture.

[0204] These additives are primarily protective agents. These include primary and secondary types (major and auxiliary) of aging inhibitors, light stabilizers, and UV protectants, as well as flame retardants, and additional dyes and pigments. The adhesive compound layer can be colored accordingly to any desired color, or it can be white, gray, or black. Commonly used additives of this or other types include:

[0205] • The primary antioxidant, such as a sterically hindered phenol, is preferably present at a ratio of 0.2% to 1% by weight, based on the total weight of the base mixture.

[0206] • Auxiliary antioxidants, such as phosphites or thioethers, are preferably present at a ratio of 0.2% to 1% by weight, based on the total weight of the base mixture.

[0207] • Process stabilizers, such as carbon radical scavengers, are preferably used at a ratio of 0.2% to 1% by weight, based on the total weight of the base mixture.

[0208] • Light stabilizers, such as UV absorbers or sterically hindered amines, are preferably present in a proportion of 0.2% to 1% by weight, based on the total weight of the base mixture.

[0209] • Processing aids, preferably at a ratio of 0.2% to 1% by weight, based on the total weight of the base mixture.

[0210] • Optional other polymers with preferred elastomer properties; therefore, available elastomers particularly include elastomers based on pure hydrocarbons, such as unsaturated polydienes, such as naturally or synthetically produced polyisoprene or polybutadiene, chemically substantially saturated elastomers, such as saturated ethylene-propylene copolymers, olefin copolymers, polyisobutylene, butyl rubber, ethylene-propylene rubber, and chemically functionalized hydrocarbons, such as halogenated, acrylate-containing, allyl ether-containing, or vinyl ether-containing polyolefins, preferably in a proportion of 0.2% to 10% by weight, based on the total weight of the base compound.

[0211] When adhesive formulations come into contact with layers that may potentially release so-called rubber toxins (e.g., copper, manganese(II), iron(II), cobalt, or nickel ions), it is advantageous to add at least one type of metal passivator, also known as a metal remover. Specific examples are ADK-Stab CDA-1, CDA-1H, CDA-6, and CDA-10 from Adeka, and ADK-Stab ZS-27 or ZS-90; Hostanox OSP1 from Clariant; Naugard XL-1 from SIGroup; and Irganox MD-1024 from BASF. The amount used is typically up to 0.5% by weight, based on the base formulation.

[0212] According to a preferred embodiment, the adhesive formulation of the present invention contains at least one compatibilizer in the base formulation, said compatibilizer being selected, for example, from polyethers, polyamines (polyamines), polyvinylpyrrolidone, or aliphatic polyesters, and said compatibilizer preferably having a weight-average molecular weight (Mw) distribution of 100-5000 g / mol, more preferably 200-2000 g / mol. Furthermore, amphoteric substances, such as alkali metal or alkaline earth metal aliphatic soaps, or anionic, cationic, or nonionic surfactants, can advantageously be used.

[0213] According to a particularly preferred embodiment, the adhesive formulation of the present invention comprises, as a compatibilizer, at least one polyether, preferably at least one substance selected from polyethylene glycol (PEG), polypropylene glycol (PPG), and polytetrahydrofuran, with PEG and PPG being particularly preferred. Block copolymers composed of PEG and PPG are also conceivable, as are polyethers containing hydrocarbon segments.

[0214] The listed substances surprisingly achieve exceptionally good re-detachability. Without being bound by any particular theory, it is conceivable that the ion flow of the electrolyte through the mixture layer is accelerated by the listed substances, particularly and for example, PEG and / or PPG.

[0215] The total amount of compatibilizer in the adhesive compound is according to a preferred embodiment, wherein at least one compatibilizer is present at 1% to 10% by weight, preferably 1% to 5% by weight, based on the total weight of the base compound.

[0216] This further optimizes adhesive formulations in terms of the conflicting objectives of adhesive strength and electrical redetachability.

[0217] Preferably, the adhesive compound of the present invention has a base mixture comprising 80% to 97.5% by weight, particularly preferably 85% to 95% by weight, and very particularly preferably 85% to 92% by weight, based on the total mass of the adhesive mixture in each case.

[0218] According to a particularly preferred embodiment of the invention, the adhesive formulation of the invention comprises the above-described basic formulation, including all embodiments or preferred levels, preferably in an amount of 88% to 94% by weight based on the total weight of the adhesive formulation; and 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide (EMIM-FSI) as an electrolyte, preferably in an amount of 3% to 10% by weight based on the total weight of the adhesive formulation.

[0219] In addition to the base compound and electrolyte, the adhesive compound preferably also contains at least one crosslinking agent, and all the above-described embodiments and preferred levels also apply to the crosslinking agent.

[0220] The adhesive formulation of the present invention is preferably a pressure-sensitive adhesive formulation.

[0221] In this context, pressure-sensitive adhesive formulations are understood to mean, as commonly understood, substances that possess durable tack and adhesiveness—particularly at room temperature. A pressure-sensitive adhesive formulation is characterized by its ability to be applied to a substrate and remain adhered there, the applied pressure and the duration of exposure to that pressure not defined in more detail. In some cases, depending on the exact properties of the pressure-sensitive adhesive formulation, temperature, and humidity, and depending on the substrate, a short-lived minimum pressure of no more than slight contact is sufficient to achieve an adhesive effect; in other cases, longer exposure to high pressure may be required.

[0222] Pressure-sensitive adhesive formulations possess specific characteristic viscoelasticity, resulting in durable tack and adhesive strength. They are characterized by the development of a viscous flow process and an elastic rebound force upon mechanical deformation. These two processes are interrelated, depending not only on the exact composition, structure, and degree of cross-linking of the pressure-sensitive adhesive formulation, but also on the speed and duration of deformation, and on temperature.

[0223] A viscous flow component (part) is essential for achieving adhesive bonding. Only the viscous component (part) generated by macromolecules with relatively high mobility allows for good wetting and flow to the substrate to be bonded. A high proportion of viscous flow results in high pressure-sensitive adhesive properties (also known as tack or surface tack), and therefore usually also high adhesive strength. Highly cross-linked systems or crystalline or glassy polymers typically have at least low pressure-sensitive adhesive properties (if any) due to the lack of free-flowing components.

[0224] Elastic resilience components are necessary for achieving cohesion. They are generated, for example, by very long chains and entangled macromolecules that are physically or chemically cross-linked, and are capable of transmitting forces that attack the adhesive bond. They have the effect that the adhesive bond can withstand sustained stress, such as sustained shear stress, to a sufficient degree over an extended period of time.

[0225] To more accurately describe and quantify the measurements of the elastic and viscous components and the relationships between them, variable storage modulus (G') and loss modulus (G'') can be used, which can be determined by dynamic mechanical analysis (DMA, according to DIN EN ISO 6721). G' is a measure of the elastic component of the material, and G'' is a measure of the viscous component. Both parameters depend on the deformation frequency and temperature.

[0226] This parameter can be measured using a rheometer. The material under examination is subjected to sinusoidal oscillating shear stress, for example, in a plate-to-plate arrangement. In the case of a shear stress-controlled device, the deformation as a function of time and the time delay of this deformation are measured relative to the onset of shear stress. This time delay is called the phase angle δ.

[0227] The energy storage modulus G' is defined as follows:

[0228] G'=(τ / γ)·cos(δ) (τ=shear stress, γ=deformation, δ=phase angle=phase shift between shear stress vector and deformation vector).

[0229] The loss modulus G'' is defined as:

[0230] G''=(τ / γ)·sin(δ) (τ=shear stress, γ=deformation, δ=phase angle=phase shift between shear stress vector and deformation vector).

[0231] If at room temperature, this is defined here as 23°C, at 10 0 Up to 10 1 Within the rad / sec deformation frequency range, G' is at least partially within 10 3 Up to 10 7 If the G' curve is within the range of Pa and if G'' is also at least partially within this range, the substance is generally considered a pressure-sensitive adhesive and, for the purposes of this invention, is defined as a pressure-sensitive adhesive. "Partially" means that at least a portion of the G' curve is within the deformation frequency range of 10. 0 rad / sec (inclusive) to 10 1 rad / sec (inclusive) (x-axis) and G' value range 10 3 Pa (inclusive) to 10 7Pa (inclusive) (vertical axis) covers the window. For G'', this applies with the necessary modifications.

[0232] Preferably, the pressure-sensitive adhesive compound is subjected to 10 [units of temperature] at 23°C. 0 Up to 10 1 The deformation frequency range in rad / sec has values ​​within 10 as determined according to DIN EN ISO 6721. 3 Up to 10 7 Storage modulus G' and loss modulus G'' within the Pa range.

[0233] To achieve viscoelastic properties, the monomers upon which the polymer underlying the pressure-sensitive adhesive formulation is based, and any other components present in the formulation, are specifically selected such that the glass transition temperature (according to DIN 53765) of the pressure-sensitive adhesive formulation is lower than its service temperature (i.e., typically lower than room temperature (23°C)). By employing suitable cohesive strengthening measures, such as crosslinking reactions (forming bridging links between macromolecules), the temperature range in which the polymer composition exhibits pressure-sensitive adhesive properties can be expanded and / or modified. Therefore, the application range of the pressure-sensitive adhesive formulation can be optimized by setting the balance between the composition's flowability and cohesion.

[0234] In particular, the pressure-sensitive adhesive formulation has a glass transition temperature of ≤23°C as determined according to DIN 53765.

[0235] In contrast to pressure-sensitive adhesive formulations, hot melt adhesives, such as those based on polyamides, polyurethanes (polyurethanes), or modified polyethylene, typically exhibit no tack at room temperature (23°C), even when present in hot melt adhesive compositions.

[0236] The present invention also provides an adhesive tape comprising at least one adhesive blend layer D of at least one adhesive blend of the present invention.

[0237] The tape of the present invention is preferably a double-sided tape. For simplicity, the tape of the present invention is also referred to as "tape" in the context of the double-sided embodiment of the present invention.

[0238] This invention relates to an adhesive tape that can exist in any desired finished form, but is preferably in roll form. The tape, particularly in the form of an elongated sheet, can be produced in rolls, i.e., wound around itself in the form of an Archimedean spiral, or as adhesive strips, for example, in the form of blanks or die-cut pieces.

[0239] The tape of the present invention is particularly present in the form of an elongated sheet. An elongated sheet is understood to mean an object whose length (in the x-direction) is many times greater than its width (in the y-direction), while the width remains substantially the same and preferably identical throughout the length.

[0240] For the purposes of this invention, the general term "tape" or the synonym "adhesive strip" encompasses all sheet-like structures, such as films or film segments extending in two dimensions, strips having an extended length and a finite width, segments of strips, and finally die-cut pieces or labels.

[0241] In addition to its longitudinal (x-direction) and transverse (y-direction) dimensions, the tape also has a thickness (z-direction) extending perpendicular to both dimensions, with the transverse and longitudinal dimensions being many times larger than the thickness. The thickness is very substantially uniform across the entire surface of the tape, determined by its length and width, and preferably identical within tolerances.

[0242] This statement is applied by analogy to a carrier layer that forms layers in the x and y directions as elements of an adhesive tape according to some preferred embodiments.

[0243] It should be understood that individual layers are stacked on top of each other along the z-direction.

[0244] The present invention also provides an adhesive composite comprising at least the following layers:

[0245] • First substrate A; and

[0246] • Second substrate B; and

[0247] • The adhesive tape of the present invention is disposed between substrate A and substrate B and bonds substrate A and B together.

[0248] Specifically, at least one of substrate A and substrate B, or substrate and tape, is designed to be conductive at two different points, or neither substrate nor tape is designed to be conductive at two different points.

[0249] The present invention also provides a method for electrically debonding the composite of the present invention, comprising at least the following method steps:

[0250] i.) Apply a voltage at two different points in the complex, preferably 2 to 50 V.

[0251] In step i.) of the method according to the invention, a voltage is applied to cause the composite to debond electrically.

[0252] Voltage, especially DC (direct current) voltage.

[0253] According to a preferred embodiment of the invention, the voltage is 3 to 12 V. This voltage can be applied, in particular, by means of a battery located in an adjacent area of ​​the adhesive (adhesive), such as, and especially, for example, in mobile phones, tablet computers, etc.

[0254] According to a further preferred embodiment of the invention, the voltage is 12 to 50 V. This relatively high voltage allows for particularly rapid disengagement; the voltage used for this purpose only needs to be applied for a few seconds.

[0255] Depending on the voltage chosen, the duration of the applied voltage in step i.) can be from a few seconds, more specifically 2 seconds, up to 900 seconds, and preferably up to 600 seconds.

[0256] It is also conceivable that the voltage application period is longer than 900 seconds, especially if the voltage is relatively low.

[0257] The method of the present invention for electrically debonding the composite of the present invention allows substrates A and B to debond from each other quickly and easily without requiring much force.

[0258] If the layers do not separate from each other after the application of voltage without further action, the method of the present invention includes at least the following further method steps:

[0259] ii.) Apply force to adhesive compound layer D and / or substrate A and / or substrate B such that the distance between substrate A and B increases.

[0260] According to step ii), the force that may still be required is significantly lower than the adhesive strength before applying voltage according to step i).

[0261] The voltage applied according to step i.) is performed at two different points on the bonded composite of the present invention. Advantageously, the points at which the voltage is applied depend on the construction of the tape and the bonded composite, and therefore on the individual layers bonded together and the properties of substrates A and B.

[0262] The following section describes some preferred implementation schemes.

[0263] According to a preferred embodiment, the tape is a transfer tape and consists of an adhesive compound layer D.

[0264] In an adhesive composite comprising two substrates A and B, the tape can advantageously debond electrically again due to the fact that both substrates A and B are conductive. For this purpose, applying a voltage to substrates A and B causes anions in the adhesive blend to migrate towards the anode and cations towards the cathode. Not wishing to be bound by a particular theory, the inventors hypothesize the following mechanism: the applied voltage causes the migration of electrolytes in the adhesive blend layer D, and more particularly the separation of anions and cations in the ionic liquid. This results in a significant reduction in the adhesion of the adhesive blend layer D to substrates A and B, and causes these layers to debond from each other.

[0265] According to a preferred embodiment of the invention, the bonded composite therefore comprises the following layers:

[0266] • A conductive first substrate A; and

[0267] • A conductive second substrate B; and

[0268] • The tape of the present invention comprises an adhesive compound layer D and is disposed between a substrate A and a substrate B, thereby bonding the substrates A and B together.

[0269] According to a further preferred embodiment, in addition to the first adhesive compound layer D, the tape further comprises at least the following layers:

[0270] • Second adhesive compound layer C; and

[0271] • At least one conductive carrier layer T is disposed between layers D and C.

[0272] This type of tape can be adapted to various substrates as a double-sided tape via a second adhesive compound layer C. In principle, these can be the same substrates as those in the above-described embodiments where the tape is a transfer tape.

[0273] However, particularly and advantageously, this type of tape can also be used when only one substrate, such as substrate A, is conductive so that substrates A and B can be debonded from each other later.

[0274] According to the preferred embodiment, xi.) only the carrier layer T or xii.) the carrier layer T and the second adhesive compound layer C are designed to be conductive.

[0275] This means that a voltage can be applied to the xi.) conductive carrier layer or the xii.) second adhesive compound layer C and the conductive substrate A.

[0276] The tape is initially advantageously used as a double-sided adhesive tape, such that an electrically removable adhesive compound layer D is attached to a conductive substrate A, and a second adhesive compound layer is attached to a substrate B, which may be conductive, but is not required to be.

[0277] Unwilling to be bound by any particular theory, the inventors hypothesize the following mechanism: applying voltage causes the migration of electrolytes in the adhesive blend layer D, and more specifically, the separation of anions and cations in the ionic liquid. This results in a significant reduction in the adhesion between the adhesive blend layer D and the substrate A, and causes these layers to decouple from each other.

[0278] According to a preferred embodiment of the invention, xi.) only the carrier layer is conductive. In particular and preferably, when the carrier layer laterally protrudes above at least one of the adhesive compound layers, a voltage can be applied to it particularly easily.

[0279] According to another preferred embodiment of the invention, xii.) the carrier layer and the second adhesive compound layer C are conductive. This configuration has the advantage that voltage can be applied to the adhesive compound layer C. Lateral overhang of the carrier layer is not required. Therefore, the tape can be manufactured in a simple manner, especially because layers D, T, and C can be die-cut together.

[0280] Preferably, the tape according to the above embodiment consists of three layers: D, T, and C. This is also referred to in the context of this invention as a three-layer composite DTC.

[0281] According to a preferred embodiment of the invention, the bonded composite therefore comprises the following layers:

[0282] • A conductive first substrate A; and

[0283] • Second substrate B; and

[0284] • The tape of the present invention is composed of a three-layer composite DTC that bonds substrates A and B together, such that the adhesive compound layer D is attached to the conductive substrate A.

[0285] According to a further preferred embodiment, in addition to the first adhesive compound layer D, the tape also comprises at least the following layers:

[0286] • Second adhesive compound layer C; and

[0287] • At least one first conductive carrier layer T disposed between layers D and C; and

[0288] • At least one second conductive carrier layer T' is disposed on the surface of the adhesive compound layer D on the side opposite to the first conductive carrier layer T; and

[0289] • A third adhesive compound layer C' is disposed on the surface of the second conductive carrier layer T' on the side opposite to the first adhesive compound layer D.

[0290] This tape has at least a layered structure CTD-T'-C', and as a double-sided tape, it is applicable to a variety of different substrates via adhesive compound layers C and C'.

[0291] In principle, these can be the same substrate as the substrate in the above embodiments where the tape is a transfer tape or a DTC with a three-layer structure.

[0292] However, when neither substrate A nor B is conductive, this tape can be used, particularly and advantageously, so that substrates A and B can be debonded from each other later.

[0293] According to the preferred embodiment, xi.) only carrier layers T and T' or xii.) carrier layers T and T' and the second adhesive blend layer C and / or the third adhesive blend layer C' are designed to be conductive.

[0294] This means that voltage can be applied to either of the two conductive carrier layers xi.) or to at least one of the adhesive blend layers C and C', as well as to one of the carrier layers or to other adhesive blend layers.

[0295] By analogy with the above implementation scheme, assume that applying voltage causes the migration of electrolytes in the adhesive blend layer D, and more specifically, the separation of anions and cations in the ionic liquid. This results in a significant reduction in the adhesion of the adhesive blend layer D to the conductive carrier layers T and T', and causes these layers to decouple from each other.

[0296] According to a preferred embodiment of the invention, xi.) only the carrier layers T and T' are conductive. In particular and preferably, when the carrier layers T and T' laterally protrude over at least one of the respective adjacent adhesive compound layers, a voltage can be applied to them particularly easily.

[0297] According to a further preferred embodiment of the invention, xii.) the carrier layers T and T', as well as the second and third adhesive blend layers C and C', are conductive. This configuration has the advantage that voltage can be applied to the adhesive blend layers C and C'. Lateral overhangs of the carrier layers T and T' are not required. Therefore, the tape can be manufactured in a simple manner, especially since layers C, T, D, T', and C can be die-cut together.

[0298] Preferably, the tape according to the above embodiment consists of five layers: C, T, D, T', and C'. This is also referred to in the context of the present invention as a five-layer composite CTD-T'-C'.

[0299] According to a preferred embodiment of the invention, the bonded composite therefore comprises the following layers:

[0300] • First substrate A; and

[0301] • Second substrate B; and

[0302] • The tape of the present invention is composed of a five-layer composite CTD-T'-C' that bonds substrates A and B together.

[0303] The conductive substrate in all embodiments can be, for example, the metal casing of a mobile phone.

[0304] In all embodiments, the non-conductive substrate can be a housing made of a non-conductive (conductive) material (such as plastic), or a battery or other non-conductive component (e.g., a speaker).

[0305] The present invention also provides the use of the adhesive formulations of the present invention for bonding components in electronic devices, motor vehicles, medical devices and dental devices.

[0306] The present invention also provides the use of the tape of the present invention for bonding components in electronic devices, motor vehicles, medical devices and dental devices.

[0307] In all the above embodiments, the carrier layer T or T and T' are conductive.

[0308] These layers are described below. For simplicity, the term "conductive carrier layer" or simply "carrier layer" is used. Depending on which of the above embodiments, this refers to carrier layer T or carrier layers T and T'.

[0309] The carrier layers T and T' are independent of each other and can be the same or different from each other.

[0310] Preferably, the conductive carrier layer comprises at least one metal.

[0311] According to a preferred embodiment of the invention, the metal is selected from copper, nickel, zinc, tin, silver, gold, aluminum, iron, chromium, and alloys of said metals. Very particularly preferably, the metal is selected from aluminum, zinc, copper, and nickel. Most preferably, aluminum is selected.

[0312] Preferably, the conductive carrier layer has a layer thickness of 10 nm to 50 μm measured in the z-direction (i.e., parallel to the stacking direction of the layer arrangement).

[0313] According to a preferred embodiment of the invention, the conductive carrier layer comprises a) at least one metal foil, preferably aluminum foil, and / or b) at least one conductive textile comprising at least one metal, preferably selected from copper and nickel, and / or c) at least one metal deposited by vapor deposition of one or more plies, preferably selected from copper and aluminum, and / or d) at least one metal mesh and / or e) a foil coated with metal by vapor deposition.

[0314] In principle, it is also conceivable that layer T includes a combination of two or more of the above options.

[0315] Metal foil, such as, and preferably, aluminum foil, is known to those skilled in the art.

[0316] The metal foil (e.g., preferably aluminum foil) preferably has a layer thickness of 5 to 50 μm, more preferably 10 to 30 μm, measured in the z-direction (i.e., the stacking direction parallel to the layer arrangement).

[0317] Conductive textiles are known to those skilled in the art, particularly under the designation "conductive mesh". This refers to textile fabrics, such as those made of PET (polyethylene terephthalate), which are coated with metals, such as copper and / or nickel, which is how the fabric becomes conductive.

[0318] Those skilled in the art will also recognize that metals can be directly vapor-deposited onto a surface as a single or multiple layer, for example, on the surface of an adhesive compound layer in this case.

[0319] In the context of this invention, the conductive carrier layer can be provided by depositing a metal vapor phase onto the adhesive blend layer D, adhesive blend layer C, or adhesive blend layer C'.

[0320] Furthermore, those skilled in the art are familiar with metal meshes of different sizes. Metal meshes with suitable layer thicknesses can be produced, for example, by laying a base fabric with appropriately fine metal wires or by die-cutting a foil with at least one suitable layer thickness.

[0321] In the case of coating a film with metal by vapor deposition, particularly coating a non-conductive film with metal by vapor deposition to make it conductive, the film material can be selected from all materials that can be vapor-deposited with metal and can be used as a carrier film in an adhesive tape. The material is particularly selected from polyesters and polyolefins, and mixtures of more than one material are also conceivable. Particularly preferred polyesters are polyethylene terephthalate (PET) and polyethylene naphthalate (PEN). Particularly preferred polyolefins are polypropylene (PP) and polyethylene (PE). According to a preferred embodiment, the film material is selected from PET, PEN, PE, and PP.

[0322] Preferably, it is a PET (polyethylene terephthalate) film. This film is dimensionally stable and therefore easy to process without significant stretching or tearing. This allows for the durable application of a uniform and gapless metal layer, resulting in persistent conductivity throughout the film, particularly in the z-direction.

[0323] In embodiments where at least one conductive carrier layer T or at least two conductive carrier layers T and T' are present, preferably, the at least one adjacent adhesive compound layer laterally protrudes in at least one extending direction of the layer plane and thus includes a lateral overhang. A voltage can then be applied to this lateral overhang in a simple manner.

[0324] In the case of a five-layer composite, in an advantageous embodiment, the lateral overhangs of the conductive carrier layers T and T' are arranged spatially spaced apart from each other. This makes it easier to apply voltage to the two overhangs.

[0325] When the metal deposited by vapor deposition serves as the carrier layer, it is preferable that the carrier layer laterally protrudes beyond only one adjacent adhesive compound layer in at least one extending direction of the layer plane, with the corresponding other adhesive compound layer serving as a mechanical support for the metal layer. In this case, the metal layer does not function as a physical carrier. Instead, the other adhesive compound layer serves as the carrier for the metal layer. However, for simplicity, the term carrier layer is also retained for the metal layer in these embodiments. Preferably, the thickness of layer T is greater than or equal to 10 nm in this case, more preferably 50 to 200 nm.

[0326] According to a preferred embodiment of the invention, the conductive carrier layer T or T and / or T' comprises a) at least one metal foil, preferably aluminum foil, and / or b) at least one conductive textile comprising at least one metal, preferably selected from copper and nickel, and / or d) at least one metal mesh and / or e) a film coated with metal by vapor deposition, and protruding beyond the first adhesive blend layer D and the second adhesive blend layer C or the first adhesive blend layer D and the second adhesive blend layer C and / or the first adhesive blend layer D and the third adhesive blend layer C' in at least one extension direction.

[0327] This allows voltage to be applied to the carrier layer in a simple and safe manner. Meanwhile, the tape can be produced in a relatively simple way.

[0328] According to a preferred embodiment of the invention, the conductive carrier layer T or T and / or T' comprises one or more sheets of at least one vapor-deposited metal, preferably one sheet, wherein the at least one vapor-deposited metal is preferably selected from copper and aluminum.

[0329] According to a particularly preferred embodiment of the invention, the conductive carrier layer T or T and / or T' comprises e) a film coated with metal by vapor deposition, and protruding beyond the first adhesive compound layer D in at least one extension direction. In this case, the film is coated with metal by vapor deposition, particularly on one surface, and the corresponding carrier layer is attached to the first adhesive compound layer D via the metallized surface, and thus to the electrically detachable layer.

[0330] This allows voltage to be applied to the carrier layer in a simple and safe manner.

[0331] In the context of this invention, the term "lateral extension" is understood to mean any kind of lateral overhang of the layer involved, and to mean that the respective layer extends beyond the reference layer, more particularly in the "xy" plane and therefore laterally, i.e., perpendicular to the stacking direction. In the context of this invention, the terms "lateral extension" or "segment of lateral extension" are also used instead of the term "lateral overhang."

[0332] The term “lateral” here refers to the directions of extension of the layer plane “xy” perpendicular to the stacking direction of the layers “z”. Therefore, the term is particularly independent of the geometry of the tape in the “xy” plane, which can be, for example, rectangular, as is the convention for tape (see above), but can also be square or circular.

[0333] The term does not cover minute fluctuations in the dimensions of individual layers in the “xy” plane caused by die-cutting or similar forming processes, especially since the dimensions of such minute material overhangs preclude the application of voltage to them in a planned manner.

[0334] In principle, adhesive compound layer C or C and C' can be based on the same compound as adhesive compound layer D; the adhesive compound of layer C or C and C' need not contain any electrolyte, but may contain it. Preferably, layer C or C and C' does not contain any electrolyte.

[0335] According to some embodiments of the three-layer composite DTC described above, the adhesive compound layer C is conductive.

[0336] Similarly, the adhesive compound layer C and / or adhesive compound layer C' of the five-layer compound CTD-T'-C' can be designed to be conductive.

[0337] These layers are described below. For simplicity, the term "conductive adhesive blend layer" is used where appropriate. Depending on which of the above embodiments this refers to, this means adhesive blend layer C or adhesive blend layer C and / or C'. Furthermore, for simplicity, the expression "adhesive blend layer C or C and / or C'" is used, which means the corresponding layer in the described embodiments of the tape comprising at least three or at least five layers of the composite.

[0338] The adhesive compound layers C and C' are independent of each other and can be the same or different from each other.

[0339] Preferably, the conductive adhesive compound layer contains at least one metal for this purpose, such as, in particular, nickel, copper or silver, preferably in the form of conductive metal particles and / or metallized particles, more preferably metal particles.

[0340] Metallized particles are, in particular and preferably, glass or polymer particles metallized with at least one metal, resulting in previously non-conductive particles becoming conductive through metallization.

[0341] Particularly preferred, the conductive adhesive compound layer comprises conductive particles selected from nickel particles, copper particles, and silver-coated copper particles.

[0342] According to a particularly preferred embodiment, the conductive adhesive compound layer comprises nickel particles.

[0343] Preferably, based on 100% by weight of the present polymer and tackifying resin, the conductive adhesive compound layer contains 5% to 40% by weight, particularly preferably 20% to 40% by weight, and very particularly preferably 25% to 35% by weight of conductive particles, especially metal particles and / or metallized particles.

[0344] The conductive particles should preferably be no larger than or not significantly larger than the corresponding thickness in the z-direction of the conductive adhesive compound layer as measured by an optical microscope.

[0345] Preferably, the average particle size of the conductive particles is 1 to 10 μm, more preferably 1 to 6 μm, even more preferably 3 to 5 μm, for example, particularly 4 μm.

[0346] The conductive adhesive compound layer is conductive, at least in the z-direction.

[0347] However, it can also be conductive in the xy plane. If the conductive adhesive compound layer is designed to conduct electricity only in the z-direction, but not necessarily in the xy-direction, then a preferred embodiment in which metal, particularly metal particles, is added to achieve conductivity requires a smaller amount of these materials. This optimizes the adhesive compound in terms of desired conductivity, adhesive strength, flow behavior, and cost.

[0348] In the context of this invention, the layer is considered “conductive” in particular when the resistance is less than 1 ohm, the resistance being measured in the corresponding direction as per standard MIL-DTL-83528C, and in this case more particularly in the z-direction.

[0349] The following statements apply regardless of whether the adhesive compound layer C or C and / or C' is designed to be conductive.

[0350] According to a preferred embodiment, the adhesive compound in adhesive compound layer C or C and / or C' is not a pressure-sensitive adhesive compound.

[0351] According to a particularly preferred embodiment of the invention, the adhesive blend in adhesive blend layer C or C and C' is a pressure-sensitive adhesive blend, and adhesive blend layer C or C and C' is therefore a pressure-sensitive adhesive layer.

[0352] According to a preferred embodiment of the invention, adhesive blend layer C or C and / or C' is an adhesive blend comprising phases (i) and (ii) (like adhesive blend layer D).

[0353] According to a preferred embodiment of the invention, in adhesive blend layers C or C and / or C', the poly(meth)acrylate and (if present) tackifier resin used in phase (i) and the vinyl aromatic block copolymer used in phase (ii) are the same as those used in adhesive blend layer D.

[0354] This makes it particularly possible to bond similar substrates (here referred to as A and B) together.

[0355] According to a further preferred embodiment of the invention, the adhesive compound used in adhesive compound layer C or C and / or C' is a different adhesive compound from the adhesive compound used in adhesive compound layer D.

[0356] This allows the properties of the conductive layer to be adapted particularly well to the substrates (one or more) bonded via adhesive compound layers C or C and / or C'. Since adhesive compound layers C or C and / or C' preferably do not contain any electrolytes, such as ionic liquids, or do not need to contain electrolytes, the components do not need to be adapted to them.

[0357] According to a preferred embodiment of the invention, the adhesive compound used in adhesive compound layer C or C and / or C' is a different adhesive compound from the adhesive compound used in adhesive compound layer D; the adhesive compound in adhesive compound layer C or C and / or C' may be a heat-activated adhesive compound or an acrylate-based pressure-sensitive adhesive compound.

[0358] The adhesive compound in adhesive compound layer D and (depending on the embodiment) additional adhesive compound are produced by known methods and, in particular, by coating to form a layer. This can be accomplished by using one or more suitable solvents or without using a solvent.

[0359] In addition, one or more drying steps may optionally be performed. However, the adhesive formulations of the present invention are preferably produced by extrusion without the use of solvents, which is another advantage of the present invention. This means that even during the production of the adhesive formulations and adhesive formulation layers of the present invention, the degree of sustainability can be further improved by avoiding the use of solvents, in addition to the possibility of later re-detachment.

[0360] Multiple layers are laminated on top of each other in a manner known to those skilled in the art, such that this specifically provides a layer composite DTC (where T is arranged between D and C), or C'-T'-DTC as a double-sided tape.

[0361] The carrier layers T and T' can be provided in the various ways described above.

[0362] Therefore, it is conceivable that a) a metal foil, particularly aluminum foil, and / or b) a conductive mesh and / or d) at least one metal mesh and / or e) a PET film coated with metal by vapor deposition is positioned between the respective adhesive compound layers.

[0363] In addition, c) the metal particles can be deposited directly into the surface of the adhesive compound layer D, C, or C' via vapor deposition.

[0364] The tapes of the present invention are particularly double-sided tapes, wherein, depending on the embodiment, two surfaces of the adhesive blend layer D (transfer tape), or the surface of the first adhesive blend layer D and the surface of the second adhesive blend layer C (triple-layer compound DTC), or one surface of each of the adhesive blend layers C and C' (five-layer compound CTD-T'-C') can be used to bond to a substrate.

[0365] Advantageously, the outer exposed surface of the adhesive compound layer of the tape of the present invention may be provided with an anti-adhesion material, such as release paper or release film, also known as a pad. The pad may also be a material having an anti-adhesion coating on at least one side, preferably on both sides, such as a double-sided silicone material. The pad, or more generally a temporary carrier, is not part of the tape, but merely an aid for its production and / or storage and / or for further processing by die-cutting. Furthermore, unlike a permanent carrier, the pad is not firmly bonded to the adhesive layer, but rather serves as a temporary carrier, i.e., a carrier that can be peeled off from the adhesive layer. "Permanent carrier" is also referred to as "carrier" in this application.

[0366] The thickness (in the z-direction) of each adhesive compound layer is preferably 15 to 2000 μm, particularly preferably 20 to 500 μm, and very particularly preferably 25 to 200 μm. However, the thickness is preferably as small as possible, for example 100 μm or less.

[0367] In embodiments of the three-layer composite DTC and the five-layer composite CTD-T'-C', adhesive blend layers D and C, as well as D, C, and C', have different layer thicknesses in preferred embodiments, with the thickness of adhesive blend layer D being, for example, less than the thickness of adhesive blend layers C and C'.

[0368] In a further preferred embodiment, layers D and C, or D, C and C', have the same layer thickness.

[0369] If the thickness of layer D is too high, it may become uneconomical and expensive due to the electrolyte present therein.

[0370] To facilitate the anchoring of the adhesive compound layers (one or more) onto the carrier layer, the carrier layer may be chemically and / or physically pretreated, particularly physically. Corona, plasma, or flame pretreatment are conceivable. Corona surface treatment for metallized films is also known to those skilled in the art and is described, for example, in EP 0355622 A2. Attached Figure Description

[0371] Preferred embodiments of the invention are illustrated and described more specifically below with reference to the accompanying drawings. In these drawings,

[0372] Figure 1 A simplified schematic cross-sectional view of the double-sided tape of the present invention through a preferred embodiment is shown; and

[0373] Figure 2 A simplified schematic cross-sectional view of the double-sided tape of the present invention through a preferred embodiment is shown; and

[0374] Figure 3 A simplified schematic cross-sectional view of the double-sided tape of the present invention through a preferred embodiment is shown; and

[0375] Figure 4 A simplified schematic cross-sectional view of the bonded composite of the invention in a preferred embodiment is shown; and

[0376] Figure 5 A simplified schematic cross-sectional view of the bonded composite material of the present invention under applied voltage, in a preferred embodiment, is shown; and

[0377] Figure 6 A simplified schematic cross-sectional view of the bonded composite of the present invention is shown after voltage has been applied and adhesive splitting has therefore occurred; and

[0378] Figure 7A simplified schematic cross-sectional view of the bonded composite of the invention in a preferred embodiment is shown; and

[0379] Figure 8 A simplified schematic cross-sectional view of the bonded composite of the present invention in a preferred embodiment is shown. Detailed Implementation

[0380] from Figure 1 As can be seen, adhesive compound layer D1 is attached to carrier layer T2 via one of its surfaces. Second adhesive compound layer C3 is disposed on the surface of carrier layer T on the side opposite to layer D.

[0381] from Figure 1 It can also be seen that the layer compound represents a double-sided tape, wherein the surface of the adhesive compound layer D and the surface of the second adhesive compound layer C can each be used for bonding.

[0382] Figure 2 A preferred embodiment of the invention is shown. In this embodiment, the conductive carrier layer T2 protrudes laterally beyond the adhesive blend layer D1 and beyond the second adhesive blend layer C3 in at least one extending direction of the layer plane, such that the conductive carrier layer T2 includes a hanging portion having at least one free surface 2a.

[0383] Figure 3 Another preferred embodiment of the invention is shown. In this case, the conductive carrier layer T2 protrudes laterally beyond the adhesive compound D1 in at least one extending direction of the layer plane, such that the conductive carrier layer T2 includes a hanger having a free surface 2a. Figure 3 In this process, the adhesive compound layer C3 is formed such that it also includes a hanger relative to layer D1. The carrier layer T2 is specifically a PET film coated with aluminum on one side, the aluminum-coated side being attached to layer D1.

[0384] Figure 4 A schematic illustration of the bonded composite of the present invention in a preferred embodiment is shown. From Figure 4 As can be seen, the tape is disposed on the surface of the first substrate A4 through the adhesive compound layer D1, and the first substrate is conductive.

[0385] In addition, the tape is disposed on the surface of the second substrate B5 through the second adhesive compound layer C3.

[0386] Figure 4 Also shown by way of example, the conductive carrier layer T2 protrudes laterally beyond the adhesive compound layer D1 in at least one extending direction of the layer plane, such that the conductive carrier layer T includes a hanging portion having a free surface 2a.

[0387] A voltage can now be applied through this free surface 2a, such as Figure 5 The schematic diagram is shown in the figure.

[0388] Applying voltage causes the electrolyte to migrate in the adhesive compound layer D1, and more specifically, the separation of anions and cations of the ionic liquid.

[0389] This results in a significant reduction in the adhesive adhesion of adhesive compound layer D1 to substrate A4, and causes these layers to debond from each other, such as... Figure 6 The schematic diagram is shown in the figure.

[0390] exist Figure 7 In a preferred embodiment, another schematic illustration of the bonded composite of the present invention is shown. From Figure 7 It can be seen that the tape is disposed on the surface of the first substrate A4 through the adhesive compound layer C3.

[0391] In addition, the tape is disposed on the surface of the second substrate B5 through the third adhesive compound layer C' 7.

[0392] Between layers C3 and C'7 lies an electrically detachable adhesive compound layer D1 and two conductive carrier layers T2 and T'6, with layer D1 disposed between the carrier layers.

[0393] Figure 7 Also shown by way of example, conductive carrier layer T2 and conductive carrier layer T'6 in each case laterally protrude beyond adhesive compound layer D1 in at least one extending direction of the layer plane, such that conductive carrier layer T includes a hanger having a free surface 2a, and conductive carrier layer T' includes a hanger having a free surface 6a.

[0394] exist Figure 8 In, in similar Figure 7 The preferred embodiment illustrated in the diagram shows another schematic illustration of the bonded composite of the present invention. However, compared with... Figure 7 Conversely, the overhangs of conductive carrier layer T2 and conductive carrier layer T'6 are in different directions, resulting in the spatial separation of the resulting free surfaces 2a and 6a of these layers.

[0395] Now we can Figure 5 A similar method is used to apply voltage through these free surfaces 2a and 6a. Figure 5 In contrast, the embodiment shown can apply voltage to surfaces 2a and 6a, meaning that neither of the substrates A and B needs to be conductive.

[0396] The applied voltage causes the electrolyte to migrate within the adhesive blend layer D1, and more specifically, the separation of anions and cations of the ionic liquid. This results in a significant reduction in the adhesion of the adhesive blend layer D1 to the carrier layers T2 and / or T'6, and causes these layers to decouple from each other. More specifically, the decoupling occurs at the layer where the negative electrode is applied.

[0397] According to Figure 8 In the case of spatially separated surfaces 2a and 6a, the application of voltage is simplified.

[0398] Figures 1 to 8 The illustrations shown are schematic. Specifically, the thicknesses of the individual layers D, T, and C may differ from one another. Furthermore, substrates A and B are only schematically represented as additional layers. These can, of course, have any other spatial geometry.

[0399] Numerous embodiments are described below to further illustrate the invention. Embodiments marked with "I" are examples of adhesive formulations of the present invention, while embodiments marked with "C" are comparative examples.

[0400] Tables 1 and 3 show the composition of the adhesive formulations whose electrodetachability is being studied. Values ​​are parts by weight, where the total weight of the base formulation is 100, and the amounts of crosslinking agent and electrolyte added thereto.

[0401] Substances used

[0402] P1: Polymethacrylate, prepared as described below;

[0403] P2: Polymethacrylate, prepared as described below;

[0404] SOL T 190: Europrene® SOL T 190, SIS: Styrene-isoprene-styrene block copolymer from Versalis;

[0405] Kraton® D1118: A styrene-butadiene block copolymer from Kraton Polymers;

[0406] Calprene® 718: A styrene-butadiene-styrene block copolymer from Dynasol Elastomers;

[0407] Tackifier resin: Paraaloid™ DM-55 from Dow;

[0408] Filler: Unexpanded microspheres, Expancel® 920DU40 from Nouryon;

[0409] PPG: Polypropylene glycol;

[0410] Uvacure® 1500: Crosslinking agent: 3,4-epoxycyclohexanecarboxylic acid methyl ester from Synsqo;

[0411] Al chelate: Crosslinking agent: Catana™ CAA 2072 from Sachen

[0412] EMIM-FSI: Electrolyte: Ionic liquid 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide;

[0413] EMIM-TFSI: Electrolyte: Ionic liquid 1-ethyl-3-methylimidazolium bis(trifluorosulfonyl)imide;

[0414] BMIM-PF6: Ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate

[0415] Polymethacrylate P1 is prepared as follows:

[0416] 57 kg of n-butyl acrylate, 20 kg of methyl acrylate, 20 kg of benzyl acrylate, 3 kg of acrylic acid, and 100 kg of acetone / isopropanol (96:4) were charged into a conventional 300 L reactor for free radical polymerization. After passing nitrogen through the reactor with stirring for 45 minutes, the reactor was heated to 58°C and 38 g of Vazo® 67 (2,2'-azobis(2-methylbutyronitrile)) was added. The jacket temperature was then raised to 65°C, and the reaction was carried out continuously at this external temperature. Another 38 g of Vazo® 67 was added after 1 hour of reaction and again after 2 hours. After 3 hours, the reaction mixture was diluted with 20 kg of acetone / isopropanol (96:4), and after 6 hours with 10 kg of acetone / isopropanol (96:4). To reduce residual monomer, 0.15 kg of Perkadox® 16 (bis(4-tert-butylcyclohexyl)peroxydicarbonate) was added again after 5.5 hours and 7 hours. The reaction was terminated after a 24-hour reaction time, and the reaction mixture was cooled to room temperature. The solution was then adjusted to a solids content of 38% by weight.

[0417] Polymethacrylate P2 is prepared as follows:

[0418] 47 kg of n-butyl acrylate, 20 kg of methyl acrylate, 30 kg of benzyl acrylate, 3 kg of acrylic acid, and 100 kg of ethyl acetate / isopropanol (96 / 4) were charged into a conventional 300 L reactor for free radical polymerization. After passing nitrogen through the reactor with stirring for 45 minutes, the reactor was heated to 58 °C and 38 g of Vazo® 67 (2,2'-azobis(2-methylbutyronitrile)) was added. The jacket temperature was then raised to 65 °C, and the reaction was carried out continuously at this external temperature. Another 38 g of Vazo® 67 was added after 1 hour of reaction and again after 2 hours. After 3 hours, the reaction mixture was diluted with 20 kg of ethyl acetate / isopropanol (96 / 4), and after 6 hours with 10 kg of ethyl acetate / isopropanol (96 / 4). To reduce residual monomer, 0.15 kg of Perkadox® 16 (bis(4-tert-butylcyclohexyl)peroxydicarbonate) was added again after 5.5 hours and 7 hours. The reaction was terminated after a 24-hour reaction time, and the reaction mixture was cooled to room temperature. The solution was then adjusted to a solids content of 38% by weight.

[0419] Polymethacrylate P3 is prepared as follows:

[0420] 204 g of n-butyl acrylate, 72 g of N,N-dimethylacrylamide, 116 g of 2-ethylhexyl acrylate, 8 g of acrylic acid, and 400 g of ethyl acetate / isopropanol (96 / 4) were charged into a conventional 4 L reactor for free radical polymerization.

[0421] After passing nitrogen through the reactor with stirring for 45 minutes, the reactor was heated to 58°C and 0.2 g of Vazo® 67 (2,2'-azobis(2-methylbutyronitrile)) was added, along with the metered addition of the solvent and monomer mixture. The mixture, with the following composition, was added metered over a 2-hour period: 306 g n-butyl acrylate, 108 g N,N-dimethylacrylamide, 174 g 2-ethylhexyl acrylate, 12 g acrylic acid, and 600 g ethyl acetate / isopropanol (96 / 4). The jacket temperature was then raised to 65°C and the reaction was continued at this external temperature. After 45 minutes, the temperature was increased to 72°C and maintained for 2 hours. After 2 hours, it was lowered to 70°C and the reaction was continued for the remaining 6.25 hours. In addition to the initial initiation at the start of the reaction, 0.3 g of Vazo® 67 was added after 30 minutes, 0.4 g after 45 minutes, and 0.4 g after 60 minutes. To reduce residual monomer, 0.15 g of Perkadox® 16 (bis(4-tert-butylcyclohexyl)peroxydicarbonate) was added after 5.5 hours, followed by another 0.1 g after 7 hours. The reaction was terminated after 9 hours, and the reaction mixture was cooled to room temperature. The solution was adjusted to a solids content of 38% by weight.

[0422] The adhesive formulations in Table 1 were prepared as follows:

[0423] Synthetic rubber (Europrene® SOLT190) in granular form is melted in a planetary roll extruder via a solid metering unit.

[0424] Then, concentrated and pre-melted polyacrylate P1, tackifier resin, and microspheres are metered in from a single-screw extruder. If an electrolyte / ionic liquid is present in the composition, it is added to the mixture.

[0425] In addition, a crosslinking agent is added. The melt is thoroughly mixed and formed into a layer with a thickness of 60 or 150 μm between two release films (silicified PET films) via a twin-roll calender.

[0426] Table 1

[0427]

[0428] Examples and comparative examples of the present invention concerning adhesive formulations for use in preparing tapes, with regard to their electrical detachability to be investigated.

[0429] Three-layer laminate

[0430] In the cases of adhesive formulations C1 to C3 and I1 to I3, a 60 μm thick first adhesive formulation layer is laminated with a 23 μm thick aluminum-coated PET carrier material in each case, and a 75 μm thick second adhesive formulation layer is laminated on the other side of the carrier material. The aluminum-coated side of the carrier is in contact with the first adhesive formulation layer here, for the purpose of investigating electrical detachability. The adhesive compound used for the second adhesive compound layer is a foamed acrylate-SIS adhesive compound (51 wt% polyacrylate, based on a monomer composition of 7 wt% acrylic acid, 68 wt% ethylhexyl acrylate, and 25 wt% methyl acrylate; 34 wt% SIS (Europrene® SOLT 190), 14 wt% Paraaloid™ DM-55; 1 wt% Expansion® 920DU 40; plus 0.1 wt% Uvacure® 1500; foamed online during extrusion and applied to the carrier material in a foamed state), which contains no electrolytes and is therefore not designed to be electrically detachable.

[0431] These layers are stacked on top of each other, such that the aluminum-coated carrier material and the second adhesive compound layer beneath it protrude laterally beyond the first adhesive compound layer, as... Figure 3 It is shown schematically in the diagram.

[0432] The resulting tape is identified as K - "Identifier of Adhesive Blend". Embodiments of the present invention are those in which one of the adhesive blends of the present invention is used.

[0433] The adhesive strength on steel was used to test the electrical detachability of the tape; the adhesive strength was tested before the voltage was applied, and another test specimen was subjected to a voltage of 12V for 60 seconds, after which the adhesive strength was measured.

[0434] In this case, a voltage is applied to one of the lateral overhangs of the Al-coated carrier material and the steel substrate.

[0435] The study also investigated the tape's static and dynamic shear strength.

[0436] Further details regarding the testing methodology are provided in the “Testing Methodology” section below.

[0437] The results are summarized in Table 2.

[0438] Table 2

[0439]

[0440] The adhesive formulations in Table 3 were prepared as follows:

[0441] The polymer P2 prepared in a solvent is supplemented with the appropriate vinyl aromatic block copolymer, the ionic liquid 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide (EMIM-TFSI), and the specified crosslinking agent. The amounts in each case refer to the substance without solvent.

[0442] Table 3

[0443]

[0444] The resulting mixture was then coated onto a PET pad equipped with a release silicone using a coating rod, resulting in a 60 μm layer thickness after drying at 110°C.

[0445] Examples and comparative examples of the present invention concerning adhesive formulations for use in preparing tapes, with regard to their electrical detachability to be investigated.

[0446] Three-layer laminate

[0447] As with Examples K-C1 to K-I3, the adhesive formulations whose electrical descalability is to be investigated are used in the three-layer composites.

[0448] In contrast to the above embodiments, a tin-coated PET film with a layer thickness of 23 μm was used as the carrier layer.

[0449] The above-mentioned foamed acrylate-SIS adhesive compound was used as the second adhesive layer.

[0450] These layers are also laminated on top of each other, such that the tin foil used as the carrier material and the second adhesive compound layer present below it protrude laterally beyond the first adhesive compound layer, as well as... Figure 3 It is shown schematically in the diagram.

[0451] The resulting tape was also tested for its electrical detachability and shear resistance.

[0452] The results are summarized in Table 4.

[0453] Table 4

[0454]

[0455] The adhesive formulations in Table 5 were prepared in a manner similar to that in the examples in Table 1 as follows:

[0456] Synthetic rubber (Europrene® SOLT190) in granular form is melted in a planetary roll extruder via a solid metering unit.

[0457] Then, concentrated and pre-melted polyacrylate P3, tackifier resin, PPG, and microspheres are metered in. An electrolyte / ionic liquid is added to the mixture.

[0458] Table 5

[0459]

[0460] In addition, a crosslinking agent is added. The melt is thoroughly mixed and formed into a layer with a thickness of 60 or 150 μm between two release films (silicified PET films) via a twin-roll calender.

[0461] Examples and comparative examples of the present invention concerning adhesive formulations for use in preparing tapes, with regard to their electrical detachability to be investigated.

[0462] Three-layer laminate

[0463] In the cases of adhesive formulations I7 to I9, a 60 μm thick first adhesive formulation layer is laminated with a 23 μm thick tin-coated PET carrier material in each case, and a 75 μm thick second adhesive formulation layer is laminated on the other side of the carrier material. The tin-coated side of the carrier is in contact with the first adhesive formulation layer here, for the purpose of investigating electrical descalability. The adhesive compound used for the second adhesive compound layer is a foamed acrylate-SIS adhesive compound (51 wt% polyacrylate, based on a monomer composition of 7 wt% acrylic acid, 68 wt% ethylhexyl acrylate, and 25 wt% methyl acrylate; 34 wt% SIS (Europrene® SOLT 190), 14 wt% Paraaloid™ DM-55; 1 wt% Expansion® 920DU 40; plus 0.1 wt% Uvacure® 1500; foamed online during extrusion and applied to the carrier material in a foamed state), which contains no electrolytes and is therefore not designed to be electrically detachable.

[0464] These layers are stacked on top of each other, such that the tin-coated carrier material and the second adhesive compound layer beneath it protrude laterally beyond the first adhesive compound layer, as... Figure 3 It is shown schematically in the diagram.

[0465] The resulting tape is identified as K - "Identifier of Adhesive Blend". Embodiments of the present invention are those in which one of the adhesive blends of the present invention is used.

[0466] The adhesive strength on steel was used to test the electrical detachability of the tape; the adhesive strength was tested before the voltage was applied, and another test specimen was subjected to a voltage of 12V for 60 seconds, after which the adhesive strength was measured.

[0467] In this case, a voltage is applied to one of the lateral overhangs of the Sn-coated carrier material and the steel substrate.

[0468] The study also investigated the tape's static and dynamic shear strength.

[0469] Further details regarding the testing methodology are provided in the “Testing Methodology” section below.

[0470] The results are summarized in Table 6.

[0471] Table 6

[0472]

[0473] When a voltage of 12V was applied for 60 seconds, all embodiments of the present invention showed a significant decrease in adhesive strength. The steel sheet contained no residue, i.e., residue of the adhesive formulation, in any case.

[0474] Furthermore, compared to the comparative examples, all embodiments of the present invention exhibit significantly enhanced shear resistance (static and / or dynamic). Therefore, only the embodiments of the present invention, and not the comparative examples, demonstrate excellent electrical detachability, possessing both high adhesive strength prior to the application of voltage and simultaneously high shear strength. Thus, in terms of the conflict of objectives regarding the considered properties, the embodiments of the present invention are at a higher level.

[0475] Furthermore, all embodiments of the present invention exhibit good corrosion resistance.

[0476] Transfer tape of the invention

[0477] In the case of adhesive blends I4 and I8, a 150 μm thick transfer tape consisting of the corresponding adhesive blend layer I4 or I8 is produced in a manner known to those skilled in the art.

[0478] These also showed a decrease in adhesive strength and good shear strength after applying a 12V voltage for 60 seconds.

[0479] Test methods

[0480] Unless otherwise specified, all measurements were performed at 23°C and 50% relative humidity. Mechanical and adhesive properties were determined as follows:

[0481] Molecular weight (GPC)

[0482] The number-average molecular weight M in this article n and weight average molecular weight M wThe reported values ​​pertain to known determinations by gel permeation chromatography (GPC). 100 μl of clarified, filtered sample (sample concentration 4 g / L) was measured. The eluent used was THF containing 0.1% (v / v) trifluoroacetic acid. Measurements were performed at 25°C.

[0483] The pre-column used was a PSS-SDV type column, 5 μm, 10 3 Å, 8.0 mm * 50 mm (values ​​here and below are in the following order: type, particle size, porosity, inner diameter * length; 1 Å = 10 -10 Separation was performed using the following combination: PSS-SDV column, 5 μm, 10 m. 3 Å and 10 5 Å and 10 6 Å, 8.0 mm * 300 mm in each case (column from Polymer Standards Service; measured using a Shodex RI71 differential refractometer). Flow rate was 1.0 ml per minute. Calibration was performed using the commercially available ReadyCal® Kit Poly(styrene)high from PSP Polymer Standard Service GmbH, Mainz. The obtained values ​​were converted (universal calibration) to polymethyl methacrylate (PMMA) using Mark-Hovink parameters K and α, so that the data are expressed in PMMA mass equivalents.

[0484] K value

[0485] The principle of this method is based on capillary viscosity determination of relative solution viscosity. For this purpose, the test substance is dissolved in toluene by agitation for 30 minutes to obtain a 1% solution. The flow time is measured in a Vogel-Ossag viscometer at 25°C, thereby determining the relative viscosity of the sample solution relative to the pure solvent. The K value can be read from a table (K = 1000 k) according to Fickentscher in a manner known to those skilled in the art.

[0486] DSC

[0487] The glass transition point, particularly the glass transition point of polymers or polymer blocks (synonymously referred to as the glass transition temperature), is reported as a result measured by differential scanning calorimetry (DSC). For this purpose, approximately 5 mg of untreated polymer sample was weighed into a small aluminum crucible (25 μl volume) and sealed with a perforated cap. A DSC 204 F1 from Netzsch was used for the measurement. The operation was performed under nitrogen inertization. The sample was first cooled to -150 °C, then heated to +150 °C at a heating rate of 10 K / min and cooled again to -150 °C. The subsequent second heating curve was recorded again at 10 K / min, and the change in heat capacity was recorded. The glass transition was identified as a step in the thermogram.

[0488] (Tackifier resin) Softening temperature

[0489] For individual substances: the softening temperature (softening point) of the tackifier resin is determined according to a relevant method known as the ring and ball method and standardized according to ASTM E28.

[0490] DACP

[0491] Weigh 5.0 g of the test substance (the tackifier resin sample under study) into a dry sample vial and add 5.0 g of xylene (mixture of isomers, CAS [1330-20-7], ≥98.5%, Sigma-Aldrich #320579 or equivalent). Dissolve the test substance at 130 °C and then cool to 80 °C. Replenish any escaping xylene with additional xylene to ensure a re-preparation of 5.0 g of xylene. Then add 5.0 g of diacetone alcohol (4-hydroxy-4-methyl-2-pentanone, CAS [123-42-2], 99%, Aldrich #H41544 or equivalent). Shake the sample vial until the test substance is completely dissolved. For this purpose, heat the solution to 100 °C. Then introduce the sample vial containing the resin solution into a Chemotronic Cool cloud point measuring device from Novomatics, where heat it to 110 °C. Then cool it at a cooling rate of 1.0 K / min. The cloud point is determined optically. Therefore, the temperature at which the solution reaches 70% turbidity is recorded. Results are reported in °C. A lower DAP value indicates higher polarity of the tested substance.

[0492] MMAP

[0493] Weigh 5.0 g of the test substance (the tackifier resin sample under study) into a dry sample vial, and add 10 mL of dry aniline (CAS [62-53-3], ≥99.5%, Sigma-Aldrich #51788 or equivalent) and 5 mL of dry methylcyclohexane (CAS [108-87-2], ≥99%, Sigma-Aldrich #300306 or equivalent). Shake the sample vial until the test substance is completely dissolved. For this purpose, heat the solution to 100°C. Then, introduce the sample vial containing the resin solution into a Chemotronic Cool cloud point measuring device from Novomatics, where it is heated to 110°C. Then, cool it at a cooling rate of 1.0 K / min. The cloud point is optically detected. For this purpose, record the temperature at which the turbidity of the solution is 70%. The results are reported in °C. The lower the MMAP value, the higher the aromaticity of the test substance.

[0494] Peel adhesive / steel

[0495] To test the adhesive strength (peel adhesion) of the layer under investigation to steel in terms of electrodetachability: a 20 mm wide strip of adhesive tape was bonded to a 23 μm thick PET film with one side (i.e., the electrolyte-free adhesive compound layer) facing out. This composite was applied to a steel plate pre-washed twice with acetone and once with isopropanol, with the side to be investigated for electrodetachability facing out. The adhesive strip was pressed onto the substrate twice with a contact pressure corresponding to 2 kg weight. After an adhesion time of 72 hours at 23°C and 50% RH (relative humidity) and at 60°C and 95% RH, respectively, the tape was peeled from the substrate at a speed of 300 mm / min and an angle of 180°. All measurements were performed at room temperature.

[0496] Test results are reported in N / cm and are the average of three measurements.

[0497] To measure the adhesive strength after applying voltage, the tape was bonded to the steel plate as described above. A DC voltage of 12V was applied, with the negative electrode on the steel plate and the positive electrode on the overhang of the metallized polymer film, or more precisely, on the free surface of the metal coating.

[0498] After 60 seconds, the voltage is turned off, and the sample is immediately clamped in the measuring device to measure the adhesive strength.

[0499] In the case of transfer tape, this is used to bond two steel substrates together, and voltage is applied to the two steel substrates.

[0500] Corrosion behavior

[0501] For evaluating corrosion behavior, two aspects are examined. First, a suitable sample is stored as a 2cm wide strip at 60°C and 95% RH for 72 hours, followed by visual inspection. The corrosion of the aluminum layer can then be assessed immediately. If corrosion has occurred, pitting corrosion will be detected, or the aluminum will be essentially absent and the sample will be translucent. Second, the adhesive strip is bonded as described in the peel adhesive method, and similarly stored under hot and humid conditions. After 72 hours, the bonded sample is removed from the oven, reconditioned for 2 hours, and a voltage is applied (see 180°C peel adhesive test). The loss of adhesive strength must be clearly measurable. If the aluminum is severely corroded, it will not conduct current and the adhesive strength will not decrease.

[0502] thickness

[0503] The thickness of the adhesive compound layer can be determined by measuring the thickness of a portion of the adhesive compound layer applied to the liner, defined by its length and width, and subtracting the thickness (known or separately measurable) of a portion of the liner of the same size. The thickness of the adhesive compound layer can be determined with an accuracy of less than 1 μm using a commercially available thickness measuring device (sensor testing device). If thickness fluctuations are detected, the average of the measurements at at least three representative locations should be reported, i.e., measurements should not be taken at areas of shrinkage, folds, spots, etc.

[0504] As described above regarding the thickness of the adhesive compound layer, the thickness of the tape (adhesive strip) or carrier can also be determined in a similar manner with an accuracy of less than 1 μm deviation using commercially available thickness measuring equipment (sensor testing equipment). If thickness fluctuations are detected, the average of the measurements at at least three representative locations should be reported, especially excluding measurements at areas of shrinkage, folds, spots, etc.

[0505] Static shear strength at 40℃

[0506] Adhere a 13 × 20 mm tape to a steel plate cleaned with acetone without trapping any air bubbles. Cover the back of the tape with aluminum foil. Roll the tape together four times using a 2 kg steel roller at a speed of 10 m / min. Suspend the test specimen in a shear test station with an integrated heating chamber (40°C). Apply a 10 N load to the specimen. The test is considered complete when the adhesion fails or the maximum test time (10,000 minutes) has been reached. Results are reported in minutes and are the median of three individual measurements.

[0507] A good result is retention time of >200 minutes.

[0508] Dynamic shear strength

[0509] A 25mm x 25mm strip of tape was bonded between two steel plates cleaned with acetone without trapping any air bubbles. The composite was then compressed under a force of 62N for 10 seconds and stored at 23°C and 50%RH for 72 hours. Measurements were then performed on a Zwick tensile testing machine by pulling the two steel plates apart at a speed of 50mm / min and at an angle of 180° at 23°C and 50%RH.

[0510] In N / mm 2 The report is the maximum force as the average of the three measurements.

[0511] List of reference numerals

[0512] 1. Adhesive compound layer D

[0513] 2 Conductive carrier layer T

[0514] 2a The free surface of the conductive carrier layer T

[0515] 3. Second adhesive compound layer C

[0516] 4 First substrate A

[0517] 5 Second substrate B

[0518] 6 Second conductive carrier layer T'

[0519] Free surface of 6a conductive carrier layer T'

[0520] 7 Third adhesive compound layer C'

Claims

1. An adhesive formulation comprising a base formulation and at least one electrolyte, wherein the base formulation comprises at least one first phase (i) and at least one second phase (ii), the first phase (i) comprising at least one poly(meth)acrylate, and the second phase (ii) comprising at least one vinyl aromatic block copolymer, such as, in particular, a styrene block copolymer, wherein the adhesive formulation comprises at least 2.5 parts by weight of the electrolyte based on 100 parts by weight of the base formulation.

2. The adhesive formulation as described in claim 1, wherein the electrolyte is selected from ionic liquids and metal salts, with ionic liquids being particularly preferred.

3. The adhesive formulation as described in claim 2, wherein 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 - N(CN)2 - and (FSO2)2N - And it is particularly preferred to be selected from (CF3SO2)2N - N(CN)2 - (FSO2)2N - PF6 - and tetrafluoroborate (BF4) - The cation of the ionic liquid is selected from imidazolium-based cations, pyridinium-based cations, pyrrolidine-based cations, and ammonium-based cations, and is particularly preferred from imidazolium-based cations, especially 1-ethyl-3-methylimidazolium and 1-butyl-3-methylimidazolium, with 1-ethyl-3-methylimidazolium being particularly preferred.

4. The adhesive formulation as claimed in any of the preceding claims, wherein the electrolyte is selected from ionic liquids 1-ethyl-3-methylimidazolium dicyandiamide, 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide (EMIM-TFSI), 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide (EMIM-FSI), 1-butyl-3-methylimidazolium hexafluorophosphate, and 1-ethyl-3-methylimidazolium tetrafluoroborate, preferably 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide (EMIM-FSI).

5. The adhesive formulation as claimed in any of the preceding claims, wherein it contains 2.5 to 10 parts by weight, preferably 2.5 to 8 parts by weight, of an electrolyte, preferably an ionic liquid, based on 100 parts by weight of a base formulation.

6. The adhesive formulation as claimed in any of the preceding claims, wherein the base formulation contains 51% to 90% by weight, preferably 60% to 80% by weight, of phase (i), and 10% to 49% by weight, preferably 20% to 40% by weight, of phase (ii).

7. The adhesive formulation as claimed in any of the preceding claims, wherein the base formulation contains 40% to 70% by weight, more preferably 45% to 60% by weight, of at least one poly(meth)acrylate in phase (i) and 15% to 50% by weight of at least one vinyl aromatic block copolymer in phase (ii), based on the total weight of the base formulation in each case.

8. The adhesive formulation as claimed in any of the preceding claims, wherein it is a pressure-sensitive adhesive formulation.

9. The adhesive formulation as claimed in any of the preceding claims, wherein the base formulation comprises at least one filler, preferably selected from microspheres, more preferably unexpanded microspheres, having a layer of magnesium hydroxide (Mg(OH)2) on its surface.

10. The adhesive formulation as claimed in any of the preceding claims, wherein the base formulation comprises at least one tackifier resin, which is preferably contained in phase (i).

11. The adhesive formulation as claimed in any of the preceding claims, wherein the tackifier resin is selected from rosin derivatives, particularly rosin esters, (meth)acrylate resins and terpene-phenol resins.

12. The adhesive formulation as claimed in any of the preceding claims, wherein the poly(meth)acrylate is prepared by polymerization of n-butyl acrylate and / or 2-ethylhexyl acrylate and / or methyl acrylate and / or benzyl (meth)acrylate and acrylic acid.

13. The adhesive formulation as claimed in any one of the preceding claims, wherein the weight-average molecular weight (Mw) of the poly(meth)acrylate is 20,000 to 2,000,000 g / mol, particularly preferably 100,000 to 1,500,000 g / mol, very particularly preferably 150,000 to 1,200,000 g / mol, even more preferably 600,000 to 1,200,000 g / mol, especially 700,000 to 900,000 g / mol.

14. A tape comprising at least one adhesive compound layer D of an adhesive compound as claimed in any one of claims 1 to 13.

15. The tape as claimed in claim 14, wherein the tape is a transfer tape and comprises an adhesive compound layer D.

16. The tape as claimed in claim 14, wherein it further comprises at least the following layers: • Second adhesive compound layer C; and • At least one conductive carrier layer T is disposed between layers D and C.

17. The tape as claimed in claim 14, wherein it further comprises at least the following layers: • Second adhesive compound layer C; and • At least one first conductive carrier layer T disposed between layers D and C; and • At least one second conductive carrier layer T' is disposed on the surface of the adhesive compound layer D on the side opposite to the first conductive carrier layer T; and • A third adhesive compound layer C' is disposed on the surface of the second carrier layer T' on the side opposite to the first adhesive compound layer D.

18. An bonded composite comprising at least the following layers: • First substrate A; and • Second substrate B; and • The tape as claimed in any one of claims 14-17 is disposed between substrate A and substrate B and bonds substrate A and B together, wherein, in particular, at least one of substrate A and substrate B, or substrate and tape, is designed to be conductive at two different points, or neither substrate nor tape is designed to be conductive at two different points.

19. A method for electrically debonding the composite as described in claim 18, comprising at least the following method steps: i.) Apply a voltage, preferably 2 to 50 V, at two different points in the composite.

20. Use of the adhesive formulation as described in any one of claims 1-13 for bonding components in electronic devices, motor vehicles, medical devices, and dental devices.

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