Adhesive tape, adhesive assembly and method for electrically separating adhesive assembly

Abstract

The invention relates to an adhesive tape, to a method for producing an adhesive tape, to an adhesive assembly, to a method for electrically separating an adhesive assembly, and to the use of an adhesive tape for bonding components in electronic, automotive, medical and dental devices. The adhesive tape comprises at least the following layers: a first adhesive layer D, wherein the adhesive layer D comprises at least one electrolyte; and a second adhesive layer C; and an electrically conductive carrier layer T arranged between layers D and C, where the electrically conductive carrier layer comprises a polymer film, where the polymer film has a metal coating on a surface facing layer D, where the metal of the metal coating is selected from the group consisting of tin, chromium, nickel, titanium and iron to an extent of at least 70 wt%, preferably at least 80 wt%, particularly preferably at least 90 wt%.

Description

Technical Field

[0001] The present invention relates to tapes, methods for manufacturing tapes, adhesive assemblies, methods for electrically separating adhesive assemblies, and the use of tapes for adhering components in electronic devices, automobiles, medical devices, and dental devices. Background Art

[0002] Most tape solutions are non-peelable or cannot be peeled without damaging the substrate. Recently, there has been an increasing interest in the "on-demand debonding" function, which has arisen due to environmental laws or end-customers' awareness of sustainability and increasing cost pressure in the manufacturing industry. The application scenarios of the debonding process are divided into rework (or post-processing), repair, recycling, and processing assistance.

[0003] Debonding techniques aim to achieve cohesive splitting of the adhesive layer or adhesive separation between the adhesive layer and the substrate. The former requires cleaning of the substrate before re-bonding, while the latter does not require such cleaning.

[0004] However, adhesive separation techniques that ensure the required high and durable reliable adhesion strength are usually more difficult to implement or require a long time in applications, such as separation (or peeling) by means of a penetrating solvent.

[0005] Therefore, currently, especially in the rework or repair of electronic devices such as smartphones and tablets, cohesive-splitting adhesive compounds (usually designed as pressure-sensitive tapes) are mainly used, and the cohesiveness of the adhesive compound decreases with increasing temperature so that manual cohesive separation can be performed for bonding. As a result, large-scale rework is required to prepare the substrate surface contaminated with adhesive residues for re-bonding.

[0006] In addition to the heat-mediated separation process, electrical separation methods have also been discussed. For example, EP 3363873 B1 discloses such an electrical separation method or a corresponding double-sided tape, which can achieve electrical separation of mutually adhered substrates. Thus, it is particularly intended to be able to achieve separation of rigid substrates. The tape proposed in EP 3363873 B1 has a centrally arranged conductive layer surrounded by two adhesive layers for this purpose, wherein the adhesive layer contains an electrolyte and can thus be electrically separated from the conductive layer or the conductive substrate. The conductive carrier layer consists of a conductive layer and a load-bearing carrier layer here.

[0007] However, the carrier layer used tends to corrode under humid heat storage, which on the one hand exposes optical defects, but also limits the separability (or peelability) in the case of long-term corrosion. Summary of the Invention

[0008] Accordingly, the object of the present invention is to provide a tape and a method for manufacturing a tape starting from the prior art, wherein the tape should be separable (or peelable) again from at least one substrate without residue and should be more corrosion-resistant than corresponding separable tapes in the prior art.

[0009] According to the present invention, said object is achieved by a tape according to the present invention.

[0010] The tape according to the present invention comprises at least the following layers:

[0011] A first adhesive layer D, wherein the adhesive layer D contains at least one electrolyte; and

[0012] A second adhesive layer C; and

[0013] A conductive carrier layer T arranged between layers D and C, wherein the conductive carrier layer comprises a polymer film (foil), wherein the polymer film has a metal coating on the surface facing layer D, and wherein the metal of the metal coating is selected from tin, chromium, nickel, titanium, and iron to an extent of at least 70% by weight.

[0014] Since the tape comprises a first adhesive layer containing at least one electrolyte, it is electrically separable again.

[0015] Since the carrier layer T is conductive, a voltage can be applied thereto to separate the tape from the substrate via the first adhesive layer D.

[0016] Due to the combination of the separable adhesive layer D and the conductive layer T, the tape can be adhesively separated from at least one substrate. This has the advantage that there is no residue of the tape on the same substrate.

[0017] Since the conductive metal layer on the polymer film mainly comprises at least one metal selected from tin, chromium, nickel, titanium, and iron to 70% by weight, the tape is corrosion-resistant even under humid heat conditions. In particular, there is no deterioration in the separability of the metal layer or optical defects.

[0018] The expression "humid heat conditions" within the scope of the present invention should be understood to mean specific conditions including a relative humidity of more than 60% and an ambient temperature of more than 25 °C.

[0019] "Storage" under humid heat conditions in particular means that the material or article under consideration is stored under humid heat conditions for more than one day. In this case, longer storage times, such as more than 100 hours, for example 500 or 1000 hours, are particularly meaningful.

[0020] Within the scope of the present invention, for testing, a temperature of 60 °C and a relative air humidity of 95% are particularly used as a standardized humid heat ambient climate.

[0021] The tape according to the invention is preferably a double-sided tape. For the sake of convenience, within the scope of the present invention, the tape according to the invention is also referred to as a "tape" in the double-sided embodiment.

[0022] The present invention relates to a tape which can exist in any assembled form, preferably a tape roll. The tape, especially in the form of a web, can be manufactured in the form of a roll (i.e., wound around itself in the form of an Archimedean spiral), or obtained as an adhesive strip (e.g., in the form of a die-cut part).

[0023] The tape according to the invention exists especially in the form of a web. A web is to be understood as an object whose length (extension (or extent) in the x-direction) is many times its width (extension (or extent) in the y-direction) and whose width is formed to be substantially the same throughout the length.

[0024] The general (or common) term "tape", also synonymously referred to as an "adhesive strip", in the sense of the present invention includes all flat structures, such as foils or foil parts (or foil segments) extending in two dimensions, tapes with an extended length and a limited width, tape parts (or tape segments), etc., and finally die-cut parts or labels.

[0025] In addition to the length range (x-direction) and the width range (y-direction), the tape also has a thickness (z-direction) extending perpendicular to the two ranges, where the width range and the length range are many times larger than the thickness. The thickness is as identical as possible, preferably completely identical, over the entire area range determined by the length and width of the tape.

[0026] The said embodiment similarly applies to the carrier which forms a layer in the x- and y-directions as a component part of the tape.

[0027] It should be understood that the layers are arranged on top of each other in the z-direction.

[0028] All embodiments of this specification apply to the tape according to the invention, the method for manufacturing the tape according to the invention, the bonding assembly according to the invention, and the method for the electrical separation assembly and the use of the tape according to the invention.

[0029] The present invention also includes all features as the subject of any extension. In addition, the combinations of the individual features with each other are included in the present invention, and in this case, different preferred levels are also included. Thus, for example, the combination of a first feature called "preferred" and a second feature called "particularly preferred" is included in the present invention. Here, the subject also called an "embodiment" equally includes different preferred levels.

[0030] The adhesive layer D contains at least one electrolyte.

[0031] "Electrolyte" is understood here to mean a compound that "dissociates into ions in solid, liquid or dissolved form and moves in a directed manner under the influence of an electric field", as listed, for example, in the Wikipedia entry "Electrolyte" of 4 January 2023 or, correspondingly, in Carl H. Hamann, Wolf Vielstich: Electrochemistry I: Elektrolytische Leitfähigkeit, Potentiale, Phasengrenzen, 2nd Edition, VCH Verlagsgesellschaft mbH, Oldenburg / Bonn 1985, 1985, ISBN 3-527-21100-4, p. 4.

[0032] Preferably, the electrolyte of the adhesive layer D is selected from ionic liquids and metal salts, with ionic liquids being particularly preferred.

[0033] In particular, by means of one or more ionic liquids as electrolytes, the tape can be separated again in a simple manner without negatively affecting the adhesive properties of the tape. Ionic liquids have the following advantages here: they can be distributed well and evenly in the polymer matrix of the adhesive and can be separated again more quickly than when using other electrolytes.

[0034] Furthermore, the components of ionic liquids, particularly at room temperature, are non-volatile. Ionic liquids are also relatively thermally stable and are non-flammable and chemically relatively stable.

[0035] Within the scope of the present invention, ionic liquids are salts that are liquid at room temperature (i.e., 23 °C). Ionic liquids accordingly contain anions and cations.

[0036] Therefore, ionic liquids are particularly suitable as electrolytes within the scope of the separation method or electro-separation method according to the present invention.

[0037] When a voltage is applied, the anions move to the anode side and the cations move to the cathode side. This results in a reduction in the adhesion force between the adhesive layer containing the ionic liquid (here layer D) and the substrate (here in particular substrate A), thus enabling an adhesive split between the adhesive layer D and the substrate A.

[0038] Within the scope of the present invention, in principle all ionic liquids are applicable.

[0039] The ionic liquids used within the scope of the present invention comprise at least one anion and at least one cation. Here, it is also conceivable that the ionic liquid includes two or more types of anions and / or two or more types of cations. Furthermore, it is conceivable that two or more different ionic liquids are added to the adhesive layer D, or the adhesive layer D then contains two or more different ionic liquids.

[0040] Preferably, the anion of the ionic liquid is selected from: , , , , , , , , , , , , , , , , , .

[0041] These anions dissolve particularly effectively in polymers used in the adhesive, such as (meth)acrylate, and can diffuse through the matrix quickly enough to allow a relatively rapid separation process. At the same time, there are no residues.

[0042] Particularly preferably, the anion is selected from , and .

[0043] These anions are particularly suitable because optimal electro-separability is achieved thereby. In particular, (re)separation is achieved particularly quickly with these anions and there are no residues.

[0044] Preferably, the cation of the ionic liquid is selected from cations based on imidazole , cations based on pyridine , cations based on pyrrolidine, and cations based on ammonium.

[0045] These cations dissolve particularly effectively in polymers used in the adhesive, such as (meth)acrylate, and can diffuse through the matrix quickly enough to allow a relatively rapid separation process. At the same time, there are no residues.

[0046] Particularly preferably, the cation is selected from cations based on imidazole .

[0047] These cations are particularly suitable because optimal electrical separability is achieved thereby. In particular, (re)separation is achieved particularly quickly with these cations and without residues.

[0048] Very particularly preferably, the cation is selected from 1-ethyl-3-methylimidazole and 1-butyl-3-methylimidazole , again preferably, the cation is 1-ethyl-3-methylimidazole .

[0049] Particularly preferably, the electrolyte of the adhesive layer D is selected from the following ionic liquids: 1-ethyl-3-methylimidazole bis(trifluoromethylsulfonyl)imide (or 1-ethyl-3-methylimidazole bis(trifluoromethylsulfonyl)imide salt) (EMIM-TFSI), 1-ethyl-3-methylimidazole bis(fluorosulfonyl)imide (or 1-ethyl-3-methylimidazole bis(fluorosulfonyl)imide salt) (EMIM-FSI), 1-ethyl-3-methylimidazole hexafluorophosphate, and 1-butyl-3-methylimidazole hexafluorophosphate. These ionic liquids dissolve particularly effectively in the polymers used in the adhesive, such as (meth)acrylates, and can diffuse through the matrix quickly enough to allow a relatively rapid separation process. At the same time, there are no residues.

[0050] In principle, the substance (or composition) of the first adhesive layer D can be any adhesive known to the person skilled in the art.

[0051] Here, the substance of the first adhesive layer D can be a pressure-sensitive adhesive and / or an adhesive that can be cured by heat activation or cured at room temperature.

[0052] The substance of the first adhesive layer D preferably contains at least one polymer.

[0053] Particularly preferably, the first adhesive layer D is based on poly(meth)acrylate.

[0054] Within the scope of the present invention, the term “based on (meth)acrylate(s)” should be understood to mean the following poly(meth)acrylates, which are the main polymers of the adhesive and are thus present in the adhesive layer D in an amount of 90 to 100% by weight, based on 100% by weight of the polymers contained in the adhesive layer D, i.e., based on the total amount of polymers contained in the adhesive layer D. Any adhesive resin (tackifying resin) contained in the adhesive layer D is not counted towards the 100% by weight of the polymers contained.

[0055] If the adhesive layer comprises less than 100% by weight (based on the total amount of polymers comprised) of poly(meth)acrylate, the adhesive layer comprises at least one type of additional polymer.

[0056] The additional polymer comprised in the adhesive layer D can in particular be selected from natural and synthetic polymers, such as in particular natural rubber and synthetic rubber.

[0057] Particularly preferably, the polymer comprised in the adhesive layer D is poly(meth)acrylate to the extent of 100% by weight.

[0058] The poly(meth)acrylate of all embodiments can in principle be any poly(meth)acrylate suitable for adhesives.

[0059] "Poly(meth)acrylate" is to be understood as meaning a polymer which can in particular be obtained by free-radical polymerization of acrylic and / or methacrylic monomers and optionally further copolymerizable monomers. More particularly, "poly(meth)acrylate" is to be understood in particular as meaning a polymer whose monomer base consists to an extent of at least 50% by weight of acrylic acid, methacrylic acid, acrylate and / or methacrylate, where the acrylate and / or methacrylate are present at least in part, preferably to an extent of at least 30% by weight, based on the total monomer base of the polymer in question.

[0060] The poly(meth)acrylate preferably comprises at least one proportionally copolymerized functional monomer, particularly preferably at least one type of monomer having at least one functional group selected from the following: carboxylic acid group, sulfonic acid group, phosphoric acid group, hydroxyl group, acid anhydride group, epoxy group and amino group.

[0061] With the exception of the epoxy group, the groups mentioned have reactivity with the epoxy group, whereby the poly(meth)acrylate can advantageously be thermally crosslinked with the introduced epoxide.

[0062] Very particularly preferably, the poly(meth)acrylate comprises at least one proportionally copolymerized functional monomer, particularly preferably at least one type of monomer having at least one (a) functional group selected from the following: carboxylic acid group and epoxy group; in particular, it comprises at least one (a) carboxylic acid group.

[0063] According to a particularly advantageous embodiment, the poly(meth)acrylate comprises proportionally polymerized acrylic acid and / or methacrylic acid. The poly(meth)acrylate thus has reactivity with the epoxy group due to the carboxylic acid group, whereby the poly(meth)acrylate can advantageously be thermally crosslinked with the introduced epoxide.

[0064] The poly(meth)acrylate can preferably be based on the following monomer composition:

[0065] a) At least one acrylate and / or methacrylate of the following formula (1):

[0066] (1)

[0067] wherein R I = H or CH3 and is an alkyl group having 4 to 18 carbon atoms;

[0068] b) At least one ethylenically unsaturated monomer having at least one functional group selected from the group consisting of: carboxylic acid group, sulfonic acid group, phosphoric acid group, hydroxyl group, acid anhydride group, epoxy group and amino group;

[0069] c) Optionally additional acrylates and / or methacrylates and / or ethylenically unsaturated monomers copolymerizable with component (a).

[0070] According to a particularly advantageous embodiment, the poly(meth)acrylate is based on the following monomer composition: the monomers of group a) are present in a proportion of 93 to 99% by weight and the monomers of group b) are present in a proportion of 1 to 7% by weight.

[0071] Using this type of poly(meth)acrylate in the adhesive layer D of the tape according to the invention achieves a particularly good property profile, including tack, impact resistance and separability in a residue-free manner.

[0072] The monomers of component a) are generally plasticizing, relatively non-polar monomers. Particularly preferably, R in monomer a) II is an alkyl group having 4 to 10 carbon atoms. The monomers of formula (1) are particularly selected from n-butyl acrylate, n-butyl methacrylate, n-pentyl acrylate, n-pentyl methacrylate, 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.

[0073] Particularly preferably, the monomers of formula (1) or group a) are selected from n-butyl acrylate, n-hexyl acrylate, n-octyl acrylate, isooctyl acrylate, 2-ethylhexyl acrylate and 2-propylheptyl acrylate.

[0074] The monomers mentioned can be polymerized particularly well and can particularly well adjust the glass transition temperature of the poly(meth)acrylate produced. This in turn allows the achievement of optimized properties with respect to flowability and tack, which are also adapted to the corresponding substrates or components to be bonded.

[0075] Here, the monomer of formula (1) or of group a) is preferably further selected from n-butyl acrylate, isooctyl acrylate, and 2-ethylhexyl acrylate.

[0076] Very particularly preferably, n-butyl acrylate and 2-ethylhexyl acrylate are used as the monomer of formula (1) or of group a).

[0077] The monomers of 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, 2-hydroxyethyl acrylate, hydroxyethyl acrylate, 3-hydroxypropyl acrylate, hydroxypropyl acrylate, 4-hydroxybutyl acrylate, hydroxybutyl acrylate, 6-hydroxyhexyl acrylate, hydroxyhexyl acrylate, 2-hydroxyethyl methacrylate, hydroxyethyl methacrylate, 3-hydroxypropyl methacrylate, hydroxypropyl methacrylate, 4-hydroxybutyl methacrylate, hydroxybutyl methacrylate, 6-hydroxyhexyl methacrylate, hydroxyhexyl methacrylate, allyl alcohol, glycidyl acrylate, glycidyl methacrylate.

[0078] Preferably, the monomers of group b) are selected from acrylic acid, methacrylic acid, and 2-hydroxyethyl acrylate.

[0079] Particularly preferably, acrylic acid is used as the monomer of group b).

[0080] Exemplary monomers of component c) are:

[0081] Methyl acrylate, ethyl acrylate, propyl acrylate, methyl methacrylate, ethyl methacrylate, benzyl acrylate, benzyl methacrylate, sec-butyl acrylate, tert-butyl acrylate, phenyl acrylate, phenyl methacrylate, isobornyl acrylate, isobornyl methacrylate, tert-butylphenyl acrylate, tert-butylphenyl methacrylate, dodecyl methacrylate, isodecyl acrylate, lauryl acrylate, n-undecyl acrylate, stearyl acrylate, tridecyl acrylate, docosyl 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-biphenylyl acrylate, 4-biphenylyl 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, butyldiglycol methacrylate, ethylene glycol acrylate, ethylene glycol monomethyl acrylate, methoxypolyethylene glycol methacrylate 350, methoxypolyethylene glycol methacrylate 500, propylene glycol monomethyl acrylate, butoxydiglycol 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, 2,2,3,3,4,4,4-hexafluorobutyl methacrylate, 2,2,3,3,4,4,4-heptafluorobutyl acrylate, 2,2,3,3,4,4,4-heptafluorobutyl methacrylate, 2,2,3,3,4,4,5,5,6,6,7,7,8,8,8-pentadecafluorooctyl methacrylate, dimethylaminopropyl acrylamide, dimethylaminopropyl methacrylamide, N-(1-methylundecyl)acrylamide, N-(n-butoxymethyl)acrylamide, N-(butoxymethyl)methacrylamide, N-(ethoxymethyl)acrylamide, N-(n-octadecyl)acrylamide; N,N-dialkyl-substituted amides such as N,N-dimethylacrylamide and N,N-dimethylmethacrylamide; N-benzylacrylamide, N-isopropylacrylamide, N-tert-butylacrylamide, N-tert-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; vinyl halides, vinylidene halides, vinyl pyridines, 4-vinyl pyridine, N-vinyl phthalimide, N-vinyl lactams, N-vinyl pyrrolidone, styrene, α-methyl styrene and p-methyl styrene; -butyl styrene, 4-n-butyl styrene, 4-n-decyl styrene, 3,4-dimethoxy styrene; macromonomers such as 2-polystyrene ethyl methacrylate (weight average molecular weight M w ) determined by GPC in the range of 4000 to 13,000 g / mol, poly(methyl methacrylate) ethyl methacrylate (M w ) in the range of 2000 to 8000 g / mol.

[0082] The monomers of component (c) can also be advantageously selected such that they contain functional groups that assist subsequent radiation chemical crosslinking (e.g., by electron beam or UV irradiation). Suitable copolymerizable photoinitiators are, for example, benzoin acrylate and acrylate-functionalized benzophenone derivatives. Monomers for crosslinking assisted by electron bombardment are, for example, tetrahydrofurfuryl acrylate, N-tert-butyl acrylamide, and allyl acrylate.

[0083] Preferably, the poly(meth)acrylate is a polyacrylate prepared by polymerizing n-butyl acrylate and / or n-hexyl acrylate and / or n-octyl acrylate and / or isooctyl acrylate and / or 2-ethylhexyl acrylate and / or 2-propylheptyl acrylate with acrylic acid.

[0084] Particularly preferably, the poly(meth)acrylate is a polyacrylate prepared by polymerizing n-butyl acrylate, 2-ethylhexyl acrylate with acrylic acid.

[0085] This results in a particularly high adhesive force of the adhesive layer D. Therefore, the tape according to the present invention has a particularly high adhesive force, especially when the tape is adhered through at least one side of the adhesive layer D.

[0086] The preparation of the poly(meth)acrylate is preferably carried out by conventional free radical polymerization or controlled free radical polymerization. The poly(meth)acrylate can be prepared by copolymerizing monomers using common polymerization initiators and optionally chain transfer agents, where polymerization is carried out in bulk, in emulsion such as in water or liquid hydrocarbons, or in solution at common temperatures.

[0087] The poly(meth)acrylate is preferably prepared by copolymerizing monomers with 0.01 to 5% by weight, particularly 0.1 to 2% by weight (in each case based on the total weight of the monomers) of a polymerization initiator in a solvent, more particularly in a solvent having a boiling range of 50 to 150 °C, particularly 60 to 120 °C.

[0088] In principle, all common initiators are suitable. Examples of free radical sources are peroxides, hydroperoxides and azo compounds such as bis-(4-tert-butylcyclohexyl) peroxydicarbonate, benzoyl peroxide, cumene hydroperoxide, cyclohexanone peroxide, di-tert-butyl peroxide, cyclohexylsulfonylacetyl peroxide, diisopropyl peroxydicarbonate, tert-butyl peroxyoctanoate and benzoin. Preferred free radical initiators are 2,2'-azobis(2-methylbutyronitrile) (DuPont's ) or 2,2'-azobis(2-methylpropanenitrile) (2,2'-azobisisobutyronitrile; AIBN; DuPont's ).

[0089] According to a preferred embodiment, bis-(4-tert-butylcyclohexyl) peroxydicarbonate is used.

[0090] Preferred solvents for the preparation of poly(meth)acrylates are alcohols such as methanol, ethanol, n-propanol and isopropanol, n-butanol and isobutanol, in particular isopropanol and / or isobutanol; hydrocarbons such as toluene and in particular volatile oils (solvent naphtha, gasoline) having a boiling range of 60 to 120 °C; ketones, in particular acetone, methyl ethyl ketone, methyl isobutyl ketone; esters such as ethyl acetate, and mixtures of the aforementioned solvents. Particularly preferred solvents are mixtures comprising isopropanol in an amount of 2 to 15% by weight, in particular 3 to 10% by weight, in each case based on the solvent mixture used.

[0091] After the preparation of the poly(meth)acrylate, the poly(meth)acrylate can be further processed from the solution, or concentrated, and the poly(meth)acrylate is further processed in the substantially absence of solvent. The concentration of the polymer can be carried out in the absence of crosslinking agents and promoter substances. However, it is also possible to add one of these classes of compounds to the polymer even before concentration, such that the concentration is then carried out in the presence of this substance.

[0092] After the concentration step, the polymer can be transferred to a mixer. Optionally, concentration and mixing can also be carried out in the same reactor.

[0093] The weight average molecular weight (average value of the molecular weight distribution) Mw of the poly(meth)acrylate is preferably in the range from 20 000 to 2 000 000 g / mol, particularly preferably in the range from 100 000 to 1 500 000 g / mol, very particularly preferably in the range from 150 000 to 1 000 000 g / mol. For this, it is advantageous to carry out the polymerization in the presence of a suitable polymerization chain transfer agent such as a thiol, a halogen compound and / or an alcohol to establish the desired average molecular weight.

[0094] With such Mw of poly(meth)acrylate (including all preferred levels), sufficient cohesion is achieved while the adhesive has good flowability and good adhesion, where it should be understood that the adhesive is optimized to a higher degree at higher preferred levels in terms of the property distribution of said properties.

[0095] The determination of Mw is carried out according to GPC as described in the test method.

[0096] The poly(meth)acrylate preferably has a K value measured in toluene (1% concentration solution, 21 °C) of 30 to 90, particularly preferably 40 to 70. The K value according to Fikentscher is a measure of the molecular weight and viscosity of the polymer.

[0097] The principle of this method is based on the capillary-viscometric determination of the relative solution viscosity. For this purpose, the test substance is dissolved in toluene by shaking for 30 minutes to obtain a 1% concentration solution. The flow time is measured in a Vogel-Ossag viscometer at 25 °C, and therefrom, the relative viscosity of the sample solution is determined relative to the viscosity of the pure solvent. The K value (K = 1000 k) can be read from a table according to the method of Fikentscher [P.E. Hinkamp, Polymer, 1967, 8, 381].

[0098] The poly(meth)acrylate preferably has a polydispersity of PD < 4 and thus a relatively narrow molecular weight distribution. Although having a relatively low molecular weight after crosslinking, the substances based on it have particularly good shear strength. In addition, the lower polydispersity facilitates processing from the melt because the flow viscosity is lower when the applied properties are roughly the same than that of polyacrylates with a wider range. The narrow-distribution poly(meth)acrylate can be advantageously prepared by anionic polymerization or by controlled radical polymerization methods, with the latter being particularly suitable. The corresponding poly(meth)acrylate can also be prepared via N-oxyl. In addition, advantageously, atom transfer radical polymerization (ATRP) can be used to synthesize narrow-distribution polyacrylates, where monofunctional or bifunctional secondary or tertiary halides are preferably used as initiators and the halides are extracted using Cu-, Ni-, Fe-, Pd-, Pt-, Ru-, Os-, Rh-, Co-, Ir-, Ag- or Au-complexes. RAFT polymerization is also suitable.

[0099] The poly(meth)acrylate is preferably crosslinked by the linking reaction of the functional groups it contains (such as particularly carboxylic acid groups) with a thermal crosslinking agent, particularly in the sense of an addition reaction or a substitution reaction. This results in the advantages that the adhesive is not too soft and has a cold flow that is not too high. This has a favorable impact on the cohesion of the adhesive as well as on the storage and processability of the adhesive.

[0100] All of the following thermal crosslinking agents can be used:

[0101] Not only ensure a sufficiently long processing life so that no gelling occurs during processing operations, especially extrusion operations,

[0102] but also cause the polymer to rapidly post-crosslink to the desired degree of crosslinking at temperatures below the processing temperature, more particularly at room temperature.

[0103] For example, it is possible to combine polymers containing carboxyl groups (carboxylic acids), amino groups and / or hydroxyl groups with isocyanates, more particularly aliphatic or blocked isocyanates such as amine-inactivated trimeric isocyanates, as crosslinking agents. Suitable isocyanates are in particular the following trimerization derivatives: MDI [4,4'-methylenebis(phenyl isocyanate)], HDI [hexamethylene diisocyanate, 1,6-hexanediyl diisocyanate] and IPDI [isophorone diisocyanate, 5-isocyanato-1-isocyanatomethyl-1,3,3-trimethylcyclohexane].

[0104] The thermal crosslinking agent is preferably used in an amount of 0.1 to 5% by weight, more particularly 0.2 to 1% by weight, based on the total amount of the polymer to be crosslinked.

[0105] Crosslinking by means of complexing agents (also known as chelates) is also possible. Preferred complexing agents are, for example, aluminium acetylacetonate.

[0106] Poly(meth)acrylates are preferably crosslinked by means of one or more epoxides or by means of one or more substances containing epoxy groups. This ensures a permanent, irreversible crosslinking.

[0107] The substances containing epoxy groups are more particularly polyfunctional epoxides, in other words those having at least two epoxy groups; the overall result is thus an indirect linking of the functional group-carrying structural units of the poly(meth)acrylate. The substances containing epoxy groups can be both aromatic and aliphatic compounds.

[0108] Very suitable polyfunctional epoxides are oligomers of epichlorohydrin; epoxy ethers of polyols (more particularly ethylene glycol, propylene glycol and butylene glycol, polyglycols, thiodiglycol, glycerol, pentaerythritol, sorbitol, polyvinyl alcohol, polyallyl alcohol, etc.); epoxy ethers of polyphenols (more particularly resorcinol, hydroquinone), bis(4-hydroxyphenyl)methane, bis(4-hydroxy-3-methylphenyl)methane, bis(4-hydroxy-3,5-dibromophenyl)methane, bis(4-hydroxy-3,5-difluorophenyl)methane, 1,1-bis(4-hydroxyphenyl)ethane, 2,2-bis(4-hydroxyphenyl)propane, 2,2-bis(4-hydroxy-3-methylphenyl)propane, 2,2-bis(4-hydroxy-3-chlorophenyl)propane, 2,2-bis(4-hydroxy-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, epoxy ethers of 4,4'-dihydroxydiphenyl sulfone, and their hydroxyethyl ethers; phenol-formaldehyde condensation products such as novolacs and phenolic resins; S-containing epoxides and N-containing epoxides (e.g., N,N-diglycidylaniline, N,N'-dimethyldiglycidyl-4,4-diaminodiphenylmethane, tetraglycidyl-m-xylenediamine); and epoxides prepared by conventional methods from mono-unsaturated carboxylic acid esters or poly-unsaturated carboxylic acids of unsaturated alcohols; glycidyl esters; polyglycidyl esters, which can be obtained by polymerization or copolymerization of glycidyl esters of unsaturated acids or can be obtained from other acidic compounds such as cyanuric acid, diglycidyl sulfide or cyclic trimethylene trisulfone and / or their derivatives.

[0109] Very suitable ethers are, for example, 1,4-butanediol diglycidyl ether, polyglycerol-3-glycidyl ether, cyclohexanedimethanol diglycidyl ether, glycerol triglycidyl ether, neopentyl glycol diglycidyl ether, pentaerythritol tetraglycidyl ether, 1,6-hexanediol diglycidyl ether, polypropylene glycol diglycidyl ether, trimethylolpropane triglycidyl ether, pentaerythritol tetraglycidyl ether, bisphenol A diglycidyl ether and bisphenol F diglycidyl ether.

[0110] Further preferred epoxides are alicyclic epoxides such as 3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate (UVACure 1500).

[0111] According to a preferred embodiment, tetraglycidyl-m-xylenediamine is used as a crosslinking agent.

[0112] According to a preferred embodiment, the poly(meth)acrylate is crosslinked by means of a crosslinker-promoter system (“crosslinking system”) to obtain a more effective control over the processing life, crosslinking kinetics and degree of crosslinking. The crosslinker-promoter system comprises at least one epoxy group-containing substance as crosslinker and at least one substance as promoter which has a promoting effect on the crosslinking reaction by means of the epoxy group-containing compound at a temperature below the melting temperature of the polymer to be crosslinked.

[0113] According to the invention, amines are particularly preferably used as promoters. The amines are formally interpreted as substitution products of ammonia; the substituents particularly include alkyl and / or aryl groups. Particular preference is given to using those amines which do not react or only react slightly with the polymer to be crosslinked.

[0114] In principle, primary amines (NRH2), secondary amines (NR2H) and tertiary amines (NR3) can be selected as promoters, and of course also those having more than one (two or more) primary amine and / or secondary amine and / or tertiary amine groups. Particularly preferred promoters are tertiary amines such as triethylamine, triethylenediamine, benzyldimethylamine, dimethylaminomethylphenol, 2,4,6-tris(N,N-dimethylaminomethyl)phenol, N,N'-bis(3-(dimethylamino)propyl)urea. Further preferred promoters are polyfunctional amines such as diamines, triamines and / or tetraamines, such as diethylenetriamine, triethylenetetramine, trimethylhexamethylenediamine.

[0115] Further preferred promoters are amino alcohols, in particular secondary amino alcohols and / or tertiary amino alcohols, where in the case of more than one (two or more) amine functionalities (functional groups) per molecule, preferably at least one, preferably all of the amine functionalities are secondary and / or tertiary. Particularly preferred promoters 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)-1,3-propanediol, 1-[bis(2-hydroxyethyl)amino]-2-propanol, triisopropanolamine, 2-(dimethylamino)ethanol, 2-(diethylamino)ethanol, 2-(2-dimethylaminoethoxy)ethanol, N,N,N'-trimethyl-N'-hydroxyethylbisaminoethyl ether, N,N,N'-trimethylaminoethylethanolamine and N,N,N'-trimethylaminopropyl-ethanolamine.

[0116] Other suitable accelerators are pyridine, imidazoles (such as 2-methylimidazole), and 1,8-diazabicyclo[5.4.0]undec-7-ene. Alicyclic polyamines can also be used as accelerators. Also suitable are phosphorus-based accelerators such as phosphines and / or compounds, such as triphenylphosphine or tetraphenyl tetraphenylborate.

[0117] Quaternary ammonium compounds can also be used as accelerators; examples are tetrabutylammonium hydroxide, cetyltrimethylammonium bromide, and benzalkonium chloride.

[0118] Preferably, the first adhesive layer D contains 2 to 10% by weight, preferably 4 to 8% by weight, of an electrolyte, preferably an ionic liquid, based on 100% by weight of the polymer contained, where the polymer is, to the extent of 100% by weight according to a preferred embodiment, a poly(meth)acrylate.

[0119] Using such a preferred or particularly preferred amount of electrolyte, especially an ionic liquid, enables relatively rapid electrical separation (electrical stripping), where at the same time the adhesion of the adhesive layer to the substrate before separation is not negatively affected.

[0120] The adhesive of the first adhesive layer D can also contain other common additives, such as an adhesive resin, a plasticizer, a compatibilizer, and a filler.

[0121] As a compatibilizer, a low molecular weight polyether, polyamine, polyvinylpyrrolidone, or aliphatic polyester is preferably used, which is miscible with the adhesive.

[0122] Some plasticizers can also be compatibilizers, such as polyethylene glycol (PEG).

[0123] According to a particularly preferred embodiment, the adhesive of the first adhesive layer D contains at least one polyether, preferably at least one substance selected from: polyethylene glycol (PEG), polypropylene glycol (PPG), polytetrahydrofuran, where PEG is particularly preferred. This particularly well supports (promotes) separability. Without wishing to be bound by a particular theory, it is conceivable that the ionic flow of the electrolyte is accelerated through the material layer by the above substances, especially PEG.

[0124] The molecular weight (according to GPC) of the above substances is preferably between 100 and 5000 g / mol here, particularly preferably between 200 and 2000 g / mol.

[0125] As described above, the tape according to the invention comprises at least one first adhesive layer D, a second adhesive layer C and at least one conductive carrier layer T, wherein the adhesive layer D comprises at least one electrolyte, the conductive carrier layer T being arranged between the layers D and C, wherein the conductive carrier layer T comprises a polymer film, wherein the polymer film has a metal coating on the surface facing the layer D, wherein the metal of the metal coating is selected from tin, chromium, nickel, titanium and iron to an extent of at least 70% by weight.

[0126] Accordingly, the carrier layer T is a metallized polymer layer, wherein the metal layer (M) is applied, in particular sputtered and / or evaporated, onto the polymer film (P).

[0127] Here, it is understood that the film is a flat structure extending in the xy plane and having two surfaces in the z direction.

[0128] Within the scope of the present invention, the metal coating is applied in particular and preferably only on one of the surfaces. Thereby, the carrier layer has a polymer side and a metallized side.

[0129] Within the scope of the present invention, the terms "polymer film" and "polymer layer" are used synonymously with each other.

[0130] The application of the metal can be carried out by all methods and devices known to those skilled in the art. Preferably, the metal is sputtered or evaporated under reduced air pressure.

[0131] The polymer of the polymer film is preferably selected from polyester, polyethylene, polypropylene, polyolefin or polyurethane.

[0132] Particularly preferred is a polymer film made of polyester, in particular a polymer film based on polyethylene terephthalate (PET) or polybutylene terephthalate, wherein polyethylene terephthalate is again preferred.

[0133] The metal of the conductive carrier layer T is selected from tin, chromium, nickel, titanium and iron to an extent of at least 70% by weight. This means that at least one metal (selected from tin, chromium, nickel, titanium and iron) is present in the metal coating in an amount of at least 70% by weight, based on the total weight of the metal coating, wherein alloys can also be used.

[0134] Particularly preferably, the metal is present in the metal coating to an extent of at least 80% by weight, very particularly preferably at least 90% by weight, in particular at least 95% by weight or even 98 to 100% by weight, especially 100% by weight.

[0135] In the case of less than 100% by weight, additional components, such as carbon or other metals, are present in the metal coating.

[0136] If only one metal is applied, the fraction of this metal is ideally 100% by weight. Due to any residues and / or impurities, the metal coating thus particularly comprises 98 to 100% by weight of the respective metal in the case of using only one metal. However, within the scope of the present invention, the metal present in the metal coating in an amount of 98 to less than 100% by weight in the case of residues and / or impurities is the metal that determines the properties with respect to the object concerned in the present invention.

[0137] According to an advantageous embodiment of the present invention, the metal is selected from tin, nickel, titanium and iron, and preferably from tin, nickel and iron.

[0138] According to a particularly advantageous embodiment of the present invention, the polymer film is coated with tin, wherein the tin is present in the metal coating in an amount of at least 80% by weight, very particularly preferably at least 90% by weight, in particular at least 95% by weight or even 100% by weight.

[0139] According to a further particularly advantageous embodiment of the present invention, the polymer film is coated with iron, wherein the iron is present in the metal coating in an amount of at least 80% by weight, very particularly preferably at least 85% by weight, in particular at least 95% by weight or even 100% by weight.

[0140] According to a further advantageous embodiment of the present invention, the polymer film is coated with titanium, wherein the titanium is present in the metal coating in an amount of at least 80% by weight, very particularly preferably at least 90% by weight, in particular at least 95% by weight or even 100% by weight.

[0141] According to a further advantageous embodiment of the present invention, the polymer film is coated with chromium, wherein the chromium is present in the metal coating in an amount of at least 80% by weight, very particularly preferably at least 90% by weight, in particular at least 95% by weight or even 100% by weight.

[0142] According to an advantageous embodiment of the present invention, the polymer film is coated with at least two metals selected from tin, chromium, nickel, titanium and iron.

[0143] According to an advantageous embodiment of the present invention, the total weight fraction of the metals selected from tin, chromium, nickel, titanium and iron is at least 80% by weight, preferably at least 90% by weight, particularly at least 98% to 100% by weight, based on the total weight of the metal coating.

[0144] Iron can be used particularly and for example in the form of steel.

[0145] In an advantageous embodiment, the steel comprises at least 80% by weight of iron and preferably at least 10% by weight of chromium. For example, a steel comprising 88% by weight of iron and 12% by weight of chromium is used for the metal coating.

[0146] Preferably, the polymer film of the carrier layer T has a layer thickness of 4 to 50 µm, particularly preferably 12 to 36 µm.

[0147] The metal coating preferably has a thickness of 10 nm (nanometers) to 5 µm (micrometers), particularly preferably 50 nm (nanometers) to 1 µm (micrometers).

[0148] The carrier layer comprising the polymer film and its metal coating is arranged between the adhesive layers D and C in such a way that the metal coating faces the electroseparable electrolyte-containing adhesive layer D.

[0149] Thereby, the metal coating is arranged between the polymer film and the adhesive layer D.

[0150] In this case, according to a preferred embodiment, the adhesive layer D is in direct contact with the metal coating.

[0151] However, according to a further advantageous embodiment, a further layer can also be arranged between the metal coating and the adhesive layer D, for example in the form of a relatively thin layer and / or an intermittent or perforated layer. Here, the further layer is also conductive or is designed to still ensure the conductivity between the metal coating and the adhesive layer D.

[0152] For example, for such a layer, it can be a thin layer applied to the metal layer for corrosion protection.

[0153] Such a corrosion protection layer can include, for example, polyurethane.

[0154] Advantageously, the layer thickness of the corrosion protection layer in the z direction is 300 nm (nanometers) or less, particularly and for example 10 to 50 nm.

[0155] The further corrosion protection layer still has sufficient conductivity due to its thickness and / or structure.

[0156] Furthermore, it is conceivable to arrange a further layer between the polymer film and the metal coating. For example, for the further layer between the polymer film and the metal, it can be a thin primer layer applied to the polymer film to improve the adhesion of the metal to the polymer.

[0157] Another subject of the invention is an adhesive assembly, which at least comprises the following layers:

[0158] A first substrate A; and

[0159] A second substrate B; and

[0160] A tape according to the invention, which is arranged between the substrates A and B and bonds the substrates A and B to each other.

[0161] Another subject matter of the present invention is a method for electrically separating the components according to the present invention, which at least includes the following method steps:

[0162] i.) Applying a voltage at two different sites of the component, wherein the voltage is preferably 2 to 50 V.

[0163] The application of the voltage is carried out according to step i.) of the method for electrically separating the component according to the present invention.

[0164] In particular, the voltage is a direct current voltage.

[0165] Preferably, the voltage is 2 to 30 V.

[0166] According to a preferred embodiment of the present invention, the voltage is 3 to 12 V. Such a voltage can be applied particularly by using a battery located near the adhesive, such as in particular and for example in mobile phones, tablets, etc.

[0167] According to a further preferred embodiment of the present invention, the voltage is 12 to 50 V. With such a relatively high voltage, re-separation can be carried out particularly quickly; here, the voltage, especially up to 50 V, only needs to be applied for a few seconds.

[0168] Those skilled in the art generally know how to apply the voltage without unwanted short circuits.

[0169] The duration of applying the voltage in step i.) particularly depends on the selected voltage and can be a few seconds, particularly 2 seconds, at most 900 seconds, preferably at most 600 seconds, particularly preferably at most 300 seconds, and again preferably at most 120 seconds.

[0170] Of course, it is also conceivable to apply the voltage for a period exceeding 900 seconds, especially in the case of a relatively low voltage.

[0171] By the method for electrically separating the components according to the present invention, the substrates A and B can be separated from each other quickly and easily without much cost.

[0172] If the layers do not separate from each other without further action after applying the voltage, the method according to the present invention at least includes additional method steps:

[0173] ii.) Applying a force to the adhesive layer D and / or the substrate A and / or the substrate B to increase the distance between the substrates A and B.

[0174] The force that may still be required according to step ii.) is significantly lower than the adhesive force before applying the voltage according to step i.).

[0175] The application of the voltage according to step i.) is carried out at two different sites of the bonding assembly according to the invention. The sites at which the voltage is suitably applied depend on the construction of the tape and the bonding assembly and thus on the nature of the individual layers and the substrates A and B bonded to each other.

[0176] In the following, some preferred embodiments are implemented.

[0177] According to a preferred embodiment of the invention, the tape consists of the following layers:

[0178] A first adhesive layer D, wherein the adhesive layer D contains at least one electrolyte; and

[0179] A second adhesive layer C; and

[0180] At least one conductive carrier layer T arranged between the layers D and C, wherein the conductive carrier layer T comprises a polymer film, wherein the polymer film has a metal coating on the surface facing the layer D, wherein the metal of the metal coating is selected from tin, chromium, nickel, titanium and iron to an extent of at least 70% by weight; and

[0181] Optionally, a corrosion protection layer between the metal coating and the adhesive layer D.

[0182] Such a tape can be applied as a double-sided tape to various different substrates through the second adhesive layer C.

[0183] Such a tape can be particularly and advantageously used for later separating the substrates A and B from each other, where only one of the substrates is conductive, for example substrate A.

[0184] In this case, a voltage can then be applied to the conductive carrier layer and the conductive substrate A.

[0185] The tape is advantageously pre-bonded as a double-sided tape such that the electrically separable adhesive layer D is bonded to the conductive substrate A and the second adhesive layer is bonded to the substrate B, which may or may not be conductive.

[0186] Without wishing to be bound by a particular theory, the inventors assume the following mechanism: By applying a voltage, migration of the electrolyte occurs in the adhesive layer D, in particular separation of the anions and cations of the ionic liquid. Thereby, the adhesion of the adhesive layer D to the substrate A is greatly reduced and these layers are separated from each other (loosened).

[0187] According to a preferred embodiment of the invention, the conductive carrier layer T laterally projects beyond the first adhesive layer D in at least one extension direction of the layer plane, such that the conductive carrier layer T has a projection with a free surface, wherein the second adhesive layer C is formed such that it bears the conductive carrier layer T on the surface opposite to the free surface and thus also has a projection.

[0188] Such a layer assembly is prepared in particular by connecting, for example laminating, the adhesive layer C to the polymer side of the carrier layer T, where the metal coating has either been applied to the face of the polymer film opposite to the adhesive layer C or the metal is applied to the free surface of the polymer film only after laminating the polymer film to the adhesive layer C.

[0189] Then, in any case, the formed layer assembly CT is applied to one side, i.e., one face, of the adhesive layer D, and the adhesive layer D does not completely cover the carrier layer T. As a result, the carrier layer T (carried by the adhesive layer D) laterally protrudes from the adhesive layer D in at least one extension direction of the layer plane, where the metal coating is arranged between the polymer film and the adhesive layer D and optionally bears an anti-corrosion layer in the direction of layer D.

[0190] Thus, a voltage can be applied to the free surface of the metallized polymer film of the carrier layer T in a particularly simple manner.

[0191] Within the scope of the present application, for the three layers D, T, and C, the term three-layer assembly D-T-C is also used.

[0192] According to a preferred embodiment of the invention, the adhesive assembly thus comprises the following layers:

[0193] A first substrate A, which is conductive; and

[0194] A second substrate B; and

[0195] The tape according to the invention, which consists of a three-layer assembly D-T-C, and the substrates A and B are bonded to each other such that the adhesive layer D is bonded to the conductive substrate A.

[0196] According to a further preferred embodiment of the invention, the tape comprises one or more additional layers, such as in particular adhesive layers and / or carrier layers.

[0197] According to a preferred embodiment of the invention, the tape comprises:

[0198] A first adhesive layer D, where the adhesive layer D contains at least one electrolyte; and

[0199] A second adhesive layer C; and

[0200] At least a first conductive carrier layer T arranged between layers D and C, where the conductive carrier layer T comprises a polymer film, where the polymer film has a metal coating on the surface facing layer D, and the metal of the metal coating is selected from tin, chromium, nickel, titanium, and iron to an extent of at least 70% by weight; and

[0201] at least one second electrically conductive carrier layer T′, which is arranged on the surface of the adhesive layer D opposite the carrier layer T, wherein the second electrically conductive carrier layer T′ likewise comprises a polymer film, wherein the polymer film has a metal coating on the surface facing the layer D, wherein the metal of the metal coating is selected from tin, chromium, nickel, titanium and iron to an extent of at least 70% by weight; and

[0202] A third adhesive layer C′ is arranged on the surface of the second carrier layer T′ opposite to the first adhesive layer D.

[0203] This adhesive tape has at least the layer structure CTD-T'-C' and can be used as a double-sided adhesive tape for various substrates via the adhesive layers C and C'.

[0204] In principle, this can be the same substrate as in the previous embodiment, where the adhesive tape has a three-layer structure DTC.

[0205] However, such an adhesive tape can also be used in particular and advantageously to later separate substrates A and B from one another, neither of which substrates A nor B is electrically non-conductive, wherein a voltage is applied to the layers T and T′.

[0206] Similar to the above embodiment, it is assumed that by applying a voltage, migration of electrolytes, in particular separation of anions and cations of the ionic liquid, occurs in the adhesive layer D. As a result, the adhesion of the adhesive layer D to the conductive support layers T and T' is greatly reduced and these layers separate (loosen) from each other.

[0207] For the second electrically conductive carrier layer T′, all embodiments of the first carrier layer T apply analogously.

[0208] In this case, the metallic coating of the first carrier layer T and / or the second carrier layer T′ can optionally have an anti-corrosion layer in the direction of the adhesive layer D.

[0209] According to a preferred embodiment of the present invention, the first conductive carrier layer T and the second carrier layer T' in each case laterally protrude beyond the first adhesive layer D in at least one extension direction of the layer plane, so that the first conductive carrier layer T and the second conductive carrier layer T' each have a protrusion with a free surface, wherein the second adhesive layer C and the third adhesive layer C' are formed at least in such a way that they carry the respective adjacent conductive carrier layer T or T' on the surface opposite to the free surface and therefore also have a protrusion.

[0210] Such a layer assembly is produced in particular by connecting, for example laminating, an adhesive layer C to the polymer side of a carrier layer T and connecting, for example laminating, an adhesive layer C' to a carrier layer T', wherein the corresponding metal coating is either already applied to the side of the polymer film opposite the adhesive layer C or C', or the metal is applied to the corresponding free surface of the polymer film only after the polymer film has been laminated to the adhesive layer C or C'.

[0211] The resulting layer assembly CT or C'T' is then applied in each case to both sides of the adhesive layer D in such a way that the adhesive layer D does not completely cover the carrier layers T and T'. As a result, the carrier layers T and T' (supported by the respective adhesive layer C or C') protrude laterally beyond the adhesive layer D in at least one direction of extension of the layer plane, wherein the metal coating of the respective carrier layer T and T' is arranged in each case between the adhesive layer D and the respective polymer film.

[0212] In each case, a voltage can be applied in a particularly simple manner to the free surface of the metallized polymer film of the carrier layers T and T′.

[0213] Preferably, the free surfaces are spatially separated from one another, which facilitates the application of voltage to these layers which are relatively close to one another.

[0214] Preferably, according to the above embodiment, the adhesive tape consists of five layers C, T, D, T' and C'.

[0215] For this reason, within the scope of this application, the term five-layer assembly CTD-T'-C' is also used.

[0216] According to a preferred embodiment of the invention, the adhesive assembly thus comprises the following layers:

[0217] a first substrate A; and

[0218] a second substrate B; and

[0219] The adhesive tape according to the invention consists of a five-layer component CTD-T'-C' and the substrates A and B are bonded to one another.

[0220] According to the embodiment of the adhesive tape according to the invention which comprises or consists of a five-layer assembly, the carrier layers T and T′ are independent of one another and can be designed identically or differently.

[0221] According to a preferred embodiment of the adhesive tape according to the invention which comprises or consists of a five-layer assembly, the first electrically conductive carrier layer T and the second electrically conductive carrier layer T′ are designed in an identical manner, in particular with regard to metal and layer thickness.

[0222] According to a preferred embodiment, the second conductive carrier layer T’ consists of the same material as the carrier layer, that is to say, the same polymer and the same metal coating, as well as the same layer thickness of the polymer film and the metal coating.

[0223] According to a further preferred embodiment of the tape according to the invention comprising or consisting of a five-layer assembly, the first conductive carrier layer T and the second conductive carrier layer T’ are designed in different ways.

[0224] Layer T and preferably also T’ are particularly conductive in the x,y directions.

[0225] Measured according to standard MIL-DTL-83528C, a layer is particularly considered to be "conductive" within the scope of the present invention when the surface resistance is less than 10 ohms per square meter (Ohm / sq).

[0226] The term "laterally protruding" within the scope of the present invention refers to any type of lateral protrusion of the said one or more layers and means that the corresponding layer extends particularly in the "xy" plane and thus extends further laterally (perpendicular to the stacking direction) than a reference layer. The terms "lateral extension" or "lateral extension portion" are also used within the scope of the present invention instead of the term "lateral protrusion".

[0227] The term "laterally" herein refers to any extension direction of the layer plane "xy" perpendicular to the stacking direction of the layer "z". Thus, the term is particularly independent of the geometry of the tape in the "xy" plane, which can be, for example, rectangular, as is common for tapes (see above), but can also be square or circular.

[0228] Minor variations in the dimensions of the individual layers in the "xy" plane due to stamping methods or similar forming methods are not mentioned here, especially since such minor material protrusions are not suitable for applying voltage thereto as planned due to their dimensions.

[0229] According to the present invention, the tape comprises a second adhesive layer C.

[0230] According to an embodiment of the tape according to the invention comprising or consisting of a five-layer assembly, the tape comprises a third adhesive layer C’.

[0231] The adhesive layer C or C and C’ can in principle be based on the same substance (composition) as the adhesive layer D, where the adhesive of layer C or C and C’ does not necessarily have to contain an electrolyte, but can contain an electrolyte. Preferably, layer C or C and C’ does not contain an electrolyte.

[0232] The adhesive layers C and C’ are independent of each other and can be the same or different from each other.

[0233] According to a preferred embodiment of the present invention, the adhesive layer C or C and / or C’ is based on poly(meth)acrylate as is the adhesive layer D. Herein, all the explanations regarding the definition, type and amount of poly(meth)acrylate-based or poly(meth)acrylate apply.

[0234] According to a preferred embodiment of the present invention, the same poly(meth)acrylate as used in the adhesive layer D is used in the adhesive layer C or C and / or C’.

[0235] Thereby, in particular similar substrates, herein referred to as A and B, can be adhered to each other. Furthermore, the aging resistance and temperature resistance of the tape are increased thereby.

[0236] According to a further preferred embodiment of the present invention, a polymer different from the poly(meth)acrylate used in the adhesive layer D is used in the adhesive layer C or C and / or C’.

[0237] Thereby, the properties can be particularly well adapted to the substrates adhered via the adhesive layer C or C and / or C’. Since the adhesive layer C or C and / or C’ preferably does not contain or does not have to contain an electrolyte, such as an ionic liquid, the components do not need to be adjusted accordingly.

[0238] According to a further preferred embodiment of the present invention, a poly(meth)acrylate different from the poly(meth)acrylate used in the adhesive layer D is thereby used in the adhesive layer C or C and / or C’.

[0239] According to a further preferred embodiment of the present invention, at least one vinyl aromatic block copolymer is included in the adhesive layer C or C and / or C’.

[0240] According to a preferred embodiment of the present invention, the adhesive layer C or C and / or C’ is based on a vinyl aromatic block copolymer, that is to say, according to these embodiments, the vinyl aromatic block copolymer is the main polymer in the adhesive layer and is present therein to the extent of 70 to 100% by weight, and precisely based on 100% by weight of the polymers contained in layer C.

[0241] Within the scope of this specification, any adhesive resin (tackifying resin) contained in the adhesive layer is not counted among the polymers contained in 100% by weight.

[0242] The vinyl aromatic block copolymer can in principle be of any type known to the person skilled in the art.

[0243] The vinyl aromatic block copolymer preferably has the structure A-B, A-B-A and / or (A-B) n X, where X represents the residue (group) of a coupling agent or initiator and n is greater than or equal to 2.

[0244] Particularly preferably, the vinyl aromatic block copolymer has the structure A-B-A, optionally in the form of a mixture having an A-B moiety (content), where the latter represents a diblock moiety.

[0245] Very particularly preferably, the vinyl aromatic block copolymer is present in the form of a mixture of a polymer of structure A-B-A and a polymer of structure A-B.

[0246] Block A represents a block made from vinyl aromatic compound monomers.

[0247] Preferably, block A is prepared from a polymerization mixture comprising at least styrene and -methylstyrene, preferably from a polymerization mixture comprising at least styrene. Very particularly preferably, block A is a block prepared from styrene and is thus a polystyrene block.

[0248] Block B represents the remaining block of the block copolymer. Preferably, block B is prepared from a polymerization mixture comprising 1,3-diene and isobutene monomers, more preferably from a polymerization mixture comprising butadiene and / or isoprene. Very particularly preferably, block B is a block prepared from butadiene and is thus a polybutadiene block.

[0249] Particularly preferably, the vinyl aromatic block copolymer is a styrene block copolymer, and further preferably a styrene-butadiene block copolymer of structure A-B-A and an optional A-B moiety.

[0250] According to a particularly advantageous embodiment, the pressure-sensitive adhesive layer as the vinyl aromatic block copolymer has a mixture composed of at least two styrene-butadiene block copolymers, wherein the first block copolymer has a diblock A-B content of 50 to 85%, and the second block copolymer has a diblock A-B content of 5 to 35%.

[0251] The diblock content is determined by GPC and can be adjusted by selecting a suitable preparation method as known to those skilled in the art.

[0252] Preferably, the weight average value of the molecular weight distribution Mw of the A-B-A polymer chain of the vinyl aromatic block copolymer contained is 50,000 g / mol to 300,000 g / mol, particularly preferably 80,000 to 180,000 g / mol (according to GPC).

[0253] As described above, the adhesive layers C and C' can be the same as or different from each other. For example, one of the adhesive layers, such as C, can be composed of an acrylate-based adhesive, while the other layer, in the same example C', is composed of an adhesive based on a vinyl aromatic block copolymer.

[0254] According to a preferred embodiment of the present invention, the adhesive layer C or C and / or C' has at least one adhesive resin, especially when it is based on a vinyl aromatic block copolymer as the main polymer.

[0255] Thereby, the adhesiveness of the adhesive is improved.

[0256] As understood by those skilled in the art, "adhesive resin (or tackifying resin)" should be understood to mean an oligomer or polymer resin that improves the adhesiveness (tack, self - adhesiveness) of the adhesive layer compared to an adhesive layer that does not contain the adhesive resin but is otherwise the same.

[0257] Preferably, at least one adhesive resin has a weight - average molecular weight M of from 400 to 15000 g / mol, particularly preferably from 400 to 5000 g / mol, and very particularly preferably from 500 to 2000 g / mol. w 。

[0258] Preferably, at least one adhesive resin is selected from unhydrogenated, partially or fully hydrogenated resins based on rosin or rosin derivatives, hydrogenated polymers of dicyclopentadiene, unhydrogenated, partially, selectively or fully hydrogenated hydrocarbon resins based on C - 5, C - 5 / C - 9 or C - 9 monomer mixtures, and polyterpene resins based on -pinene and / or -pinene and / or -limonene.

[0259] It is clear to those skilled in the art that he can select those adhesive resins that can be uniformly mixed with the vinyl aromatic block copolymer.

[0260] The adhesive of the adhesive layer C or C and / or C' may also contain other common additives such as plasticizers and fillers.

[0261] According to a preferred embodiment, the first adhesive layer D and / or the second adhesive layer C or the first adhesive layer D and / or the second adhesive layer C and / or the third adhesive layer C' is foamed.

[0262] Thereby, the impact resistance of the tape according to the present invention is improved and thus the impact resistance of the bonded assembly is also improved. This ensures that premature and undesirable mutual separation of the substrates does not occur, especially when a force (e.g., generated by a drop) acts on the bonded assembly.

[0263] Preferably, the foaming is produced by expanding expandable microspheres. "Microspheres" are understood to mean elastic and thus expandable hollow microspheres in their basic state, which have a thermoplastic polymer shell. These spheres are filled with a low-boiling liquid or a liquefied gas. The shell materials used are in particular polyacrylonitrile, PVDC, PVC or polyacrylates. Suitable low-boiling liquids or gases are in particular hydrocarbons of lower alkanes, such as isobutane or isopentane, which are encapsulated as liquefied gases under pressure in the polymer shell, with isopentane being particularly preferred.

[0264] The softening of the polymer outer shell is caused by the action on the microspheres, in particular by heat. At the same time, the liquid propellant present in the shell changes to its gaseous state. Here, the microspheres expand irreversibly and in three dimensions. The expansion ends when the internal pressure and the external pressure are balanced. Since the polymer shell is retained, a closed-cell foam is obtained.

[0265] Many types of microspheres are commercially available, which basically differ in their size (diameter in the unexpanded state: 6 to 45 µm) and the starting temperature required for their expansion (75 to 220 °C). Examples of commercially available microspheres are those of the company Nuryon type (DU = dry unexpanded).

[0266] Unexpanded microsphere types are also available as aqueous (water-containing) dispersions with a solids content or microsphere content of about 40 to 45% by weight, and additionally as polymer-bound microspheres (masterbatches), for example with a microsphere concentration of about 65% by weight in ethylene-vinyl acetate. As with the DU type, not only microsphere dispersions but also masterbatches are suitable for the preparation of foamed adhesives.

[0267] So-called pre-expanded microspheres can also be used to manufacture foamed adhesive layers. In the case of pre-expanded microspheres, the expansion occurs before they are introduced into the polymer matrix. For example, pre-expanded microspheres can be commercially obtained under the name or in the Expancel xxx DE yy (dry expanded) model from the company Nuryon. "xxx" represents the composition of the microsphere mixture. "yy" indicates the size of the microspheres in the expanded state. In the processing of already expanded microsphere types, the following can occur: due to their low density, the microspheres tend to float in the polymer matrix into which they are to be introduced, i.e., they "float upwards" during the processing operation in the polymer matrix. This results in an irregular distribution of the microspheres in the layer. More microspheres appear in the upper region (z-direction) of the layer compared to the lower region of the layer, creating a density gradient across the layer thickness.

[0268] In order to largely or almost completely prevent such density gradients, according to the invention, non-pre-expanded or only slightly pre-expanded microspheres are preferably introduced into the polymer matrix. The microspheres expand only after being introduced into the layer. In this way, a more uniform distribution of the microspheres in the polymer matrix is produced.

[0269] Preferably, the microspheres are selected such that the ratio of the density of the polymer matrix to the density of the (non-pre-expanded or slightly pre-expanded) microspheres to be introduced into the polymer matrix is between 1 and 1.6, i.e.:

[0270] (Density of the polymer matrix) / (Density of the microspheres to be introduced) = 1 to 1.6.

[0271] Expansion takes place only after introduction or immediately upon introduction. For solvent-containing substances (or compositions), the microspheres preferably expand only after introduction, coating, and drying (evaporation of the solvent). Therefore, according to the invention, DU types are preferably used.

[0272] Preferably, the average diameter of the cavities formed by the microspheres in the foamed adhesive layer is from 10 to 200 μm, particularly preferably from 15 to 200 μm, very particularly preferably from 15 to 150 μm, further preferably from 20 to 100 μm, and further particularly preferably from 25 to 70 μm. With the mentioned preferred and particularly preferred size ranges, particularly good impact resistance is achieved. At the same time, the size is adjusted according to the layer thickness of the adhesive layer.

[0273] Since the diameter of the cavities formed by the microspheres is measured in the foamed adhesive layer here, this diameter is that of the cavities formed by the expanded microspheres. The average diameter here refers to the arithmetic mean of the diameters of the cavities formed by the microspheres in the adhesive layer. In a scanning electron microscope (SEM) at 500-fold magnification, the average diameter of the cavities formed by the microspheres in the adhesive layer is determined based on 5 different cryo-fracture edges of the tape. The diameter of the microspheres visible in the micrographs is determined by means of drawing in such a way that the maximum extent (or size) of each individual microsphere in the adhesive layer to be examined in any (two-dimensional) direction is obtained from the SEM micrograph and recognized as its diameter.

[0274] If foaming is carried out with microspheres, the microspheres can be added to the formulation as a batch, paste, or undoped (unblended) or doped (blended) powder. They can also be suspended in a solvent.

[0275] According to a preferred embodiment of the invention, the content of the microspheres in the adhesive layer is between greater than 0 wt% and 12 wt%, particularly preferably between 0.25 wt% and 5 wt%, very particularly preferably between 0.5 and 3 wt%, in each case based on the total composition of the respective layer (including the mixed microspheres). These data relate to non-expanded microspheres.

[0276] The objective conflicts of properties including tackiness, flow behavior, and foaming are particularly well resolved by the amounts mentioned.

[0277] The polymer material of the adhesive layer containing expandable hollow microspheres may additionally contain non-expandable hollow microspheres. The only decisive factor is that almost all gas-containing cavities are enclosed by a permanently dense membrane, whether the membrane consists of an elastic and thermoplastically stretchable polymer mixture or of an elastic and (within the temperature range possible in plastic processing) non-thermoplastic glass. Additionally, suitable for the adhesive layer are (independent of the choice of other additives) polymer solid spheres such as PMMA spheres, glass hollow spheres, glass solid spheres, phenolic resin spheres, ceramic hollow spheres, ceramic solid spheres, and / or carbon solid spheres ("carbon microspheres").

[0278] The absolute density of the foamed adhesive layer is preferably 350 to 950 kg / m 3 、particularly preferably 450 to 930 kg / m 3 、very particularly preferably 570 to 880 kg / m 3 . The relative density describes the ratio of the density of the correspondingly foamed layer to the density of the unfoamed layer with the same corresponding formulation. The relative density of the adhesive layer is preferably 0.35 to 0.99, more preferably 0.45 to 0.97, especially 0.50 to 0.90.

[0279] Preferably, the adhesive of the adhesive layer D is a pressure-sensitive adhesive, and the adhesive layer D is therefore preferably a pressure-sensitive adhesive layer D.

[0280] This makes it easy for the tape to adhere on this side, especially because no heat input is required compared to a heat-activatable adhesive system. Additionally, due to the relatively low crosslinking density, the components of the electrolyte, such as in particular the ions of the ionic liquid, migrate faster in the pressure-sensitive adhesive.

[0281] The adhesive of the adhesive layer C or C and / or C' is not a pressure-sensitive adhesive according to a preferred embodiment.

[0282] According to a further preferred embodiment of the invention, the adhesive of the adhesive layer C or C and / or C' is a pressure-sensitive adhesive and the adhesive layer C or C and / or C' is therefore a pressure-sensitive adhesive layer.

[0283] In an embodiment in which all outer adhesive layers are pressure-sensitive adhesive layers, the tape according to the invention is a pressure-sensitive tape.

[0284] As is customary, pressure-sensitive adhesives are to be understood in the context of this invention as substances which are permanently (or permanently) tacky and adhesive (especially at room temperature). Pressure-sensitive adhesives are characterized in that they can be applied to a substrate by pressure and adhere there, without the pressure to be applied and the duration of action of this pressure being defined in detail. In some cases, depending on the exact nature of the pressure-sensitive adhesive, the temperature and air humidity, and the substrate, the action of a short-term minimum pressure of only a gentle contact for no more than a short time is sufficient to achieve the adhesion effect, in other cases, a longer action time of a high pressure may also be necessary.

[0285] Pressure-sensitive adhesives have specific characteristic viscoelastic properties which result in permanent (or permanent) adhesiveness and tackiness. Their characteristic is that when they are mechanically deformed, both a viscous flow process and the formation of an elastic restoring force exist. The two processes are in a specific relationship to each other in terms of their respective proportions, depending not only on the exact composition, structure and degree of crosslinking of the pressure-sensitive adhesive substance, but also on the rate and duration of the deformation, and on the temperature.

[0286] Proportional (or a certain proportion of) viscous flow is necessary for the achievement of adhesiveness. The viscous component (or fraction) produced only by macromolecules with relatively high mobility allows effective wetting of the substrate to be bonded and effective flowing onto it. A high viscous flow component results in high pressure-sensitive adhesiveness (also called tackiness or surface tackiness) and thus often also results in high adhesion. In general, highly crosslinked systems, crystalline or vitrified polymers have at least only very little pressure-sensitive adhesiveness or no pressure-sensitive adhesiveness at all due to the lack of a flowable component.

[0287] Proportional (or a certain proportion of) elastic restoring forces are necessary for the achievement of cohesion. They are produced, for example, by very long-chain and highly coiled and physically or chemically crosslinked macromolecules and allow the transmission of forces acting on the adhesive bond. They result in the adhesive bond being able to withstand the long-term loads acting on it (for example in the form of long-term shear loads) for a relatively long time.

[0288] To more precisely describe and quantify the measure of the elastic and viscous components, and the relationship between the components, variables which can be determined by means of dynamic mechanical analysis (DMA, according to DIN EN ISO 6721) can be used: storage modulus ( ) and loss modulus ( ). is a measure of the elastic component of the substance, is a measure of the viscous component of the substance. Both parameters depend on the deformation frequency and the temperature.

[0289] The variable can be determined with the aid of a rheometer. Here, for example, the material to be investigated is exposed to a sinusoidally oscillating shear stress in a plate-plate arrangement. In the case of an instrument operating in shear stress control, the deformation is measured as a function of time, and the time shift of this deformation is measured relative to the introduction of the shear stress. This time shift is referred to as the phase angle .

[0290] Storage modulus is defined as follows:

[0291] ( = shear stress, = deformation, = phase angle = the phase displacement between the shear stress vector and the deformation vector).

[0292] Loss modulus is defined as follows:

[0293] ( = shear stress, = deformation, = phase angle = the phase displacement between the shear stress vector and the deformation vector).

[0294] If, at room temperature, here defined as 23 °C, in the deformation frequency range from 10 0 to 10 1 rad / s (radians per second), is at least partly in the range from 10 3 to 10 7 Pa, and if is likewise at least partly in this range, then the substance is generally regarded as pressure-sensitive adhesive and is defined as such in the sense of the present invention. "Partly" means at least a part (at least one segment) of the curve lies within the window spanned by the deformation frequency range (abscissa) from 10 0 rad / s (including the endpoints) to 10 1 rad / s (including the endpoints) and the range of values (ordinate) from 10 3 (including the endpoints) Pa to 10 7 (including the endpoints) Pa. This applies correspondingly for . .

[0295] Preferably, the pressure-sensitive adhesive has, as determined according to DIN EN ISO 6721, at 23 °C in the range from 10 0 to 10 1Storage modulus in the range of deformation frequencies from and loss modulus in the range from 10 3 to 10 7 Pa. .

[0296] To achieve viscoelastic properties, the monomers on which the polymers of the pressure-sensitive adhesives are based and any other components optionally present in the pressure-sensitive adhesives are specifically selected such that the pressure-sensitive adhesives have a glass transition temperature (in accordance with DIN 53765) below the use temperature, i.e., typically below room temperature (23 °C). By suitable measures for enhancing cohesion, such as crosslinking reactions (forming bridging connections between macromolecules), the temperature range in which the polymeric material has pressure-sensitive adhesive properties can be broadened and / or shifted. Thus, the application range of the pressure-sensitive adhesives can be optimized via the regulation between the flowability and cohesion of the substances.

[0297] Preferably, the pressure-sensitive adhesive has a glass transition temperature of ≤ 23 °C determined in accordance with DIN 53765.

[0298] In contrast to pressure-sensitive adhesives, hot-melt adhesives, such as those based on polyamides, polyurethanes or modified polyethylenes, do not have adhesiveness at room temperature (23 °C), and this also applies in the case of hot-melt adhesive compositions.

[0299] Another subject of the present invention is a method for manufacturing a tape according to the present invention.

[0300] The method preferably comprises at least the following method steps:

[0301] a) Providing a first adhesive layer D, wherein the adhesive layer D contains at least one electrolyte; and

[0302] b) Providing a second adhesive layer C; and

[0303] c) Providing a polymer film with a metal coating as a conductive carrier layer T, wherein the metal of the metal coating is selected from tin, chromium, nickel, titanium and iron to an extent of at least 70% by weight; and

[0304] d) Laminating the metal-coated polymer film T from step c) onto the adhesive layer C, wherein the metal coating is arranged on the side of the polymer film opposite to the adhesive layer C; and

[0305] e) Laminating the layers D and T onto each other to form a layer assembly DTC, wherein the metal coating of the layer T faces the layer D.

[0306] The provision of the first adhesive layer D according to step a) is carried out, in particular, by providing at least one adhesive and adding at least one electrolyte to the adhesive. For the adhesive and the electrolyte, all of the above embodiments apply.

[0307] The adhesive is applied using known methods, in particular by coating in the form of a layer.

[0308] Furthermore, one or more drying steps can optionally be carried out.

[0309] The provision of the second adhesive layer C according to step b) is carried out, in particular, by providing at least one additional adhesive.

[0310] The adhesive is applied using known methods, in particular by coating in the form of a layer.

[0311] Furthermore, one or more drying steps can optionally be carried out.

[0312] The provision of the polymer film with a metal coating according to step c) can be achieved by purchasing a metallized polymer film.

[0313] However, the provision according to step c) can also be achieved by applying a metal to the polymer film.

[0314] For the material, structure and process of the metal coating, all of the above embodiments apply.

[0315] Here, the polymer film is coated with metal, in particular on one side, so that it now has a "polymer side" or "polymer face" and a "metallized side" or "metallized face".

[0316] The lamination according to step d) is carried out in a manner known to a person skilled in the art, in which the layers are stacked on top of each other such that the metallized face of the polymer film points upwards and is thus still available for lamination with layer D according to step e).

[0317] The lamination according to step e) is carried out in a manner known to a person skilled in the art, in which the layers are stacked on top of each other such that a layer assembly DTC can be obtained as a double-sided adhesive tape, where T is arranged between D and C and the metallized side of T points in the direction of layer D. If no additional layer, such as an anti-corrosion layer, is applied to the metal coating, the metal coating and the adhesive layer D will come into contact with each other.

[0318] Preferably, the layers are laminated on top of each other such that layer T protrudes laterally from layer D. Here, the layer assembly consisting of the adhesive layer C and the carrier layer T is arranged on the adhesive layer D such that a free face of layer T is produced, i.e., the adhesive layer D does not completely cover layer T.

[0319] A list of method steps (where not required) does not necessarily represent a chronological order, and only those steps that must succeed one another are carried out consecutively in time.

[0320] Crucial to the present invention is that the layer according to step d) is arranged spatially such that a layer assembly DTC is produced.

[0321] In an embodiment of a five-layer assembly, the method for manufacturing the tape includes similar steps, wherein additionally layers T’ and C’ are provided and also laminated into the assembly, resulting in the layer assembly CTDT’C’. The second conductive carrier layer T’ is preferably provided in a manner similar to the first conductive carrier layer T by laminating a metallized polymer film onto the surface of the first adhesive layer D.

[0322] The tape according to the present invention particularly represents a double-sided tape, wherein depending on the embodiment, one surface of the first adhesive layer D and one surface of the second adhesive layer C (three-layer assembly D-T-C) or one surface of each of the adhesive layers C and C’ (five-layer assembly C-T-D-T’-C’) can be used for bonding to a substrate in each case.

[0323] Advantageously, the exposed outer surface of the adhesive layer of the tape according to the present invention can be equipped with an anti-stick material, such as release paper or release film, also referred to as a liner. For the liner, it can also be a material that is anti-adhesively coated (with an anti-stick coating) on at least one side, preferably on both sides, such as a material that is silicified on both sides. The liner, or more generally, the temporary carrier, is not part of the tape, but only an aid for its manufacture, storage, and / or further processing by stamping. In addition, unlike the permanent carrier, the liner is not firmly bonded to the adhesive layer, but acts as a temporary carrier, i.e., a carrier that can be removed from the adhesive layer. The “permanent carrier” is also synonymously abbreviated as “carrier” in this application.

[0324] The thickness (in the z-direction) of the individual adhesive layer is preferably 15 to 150 µm, particularly preferably 20 to 100 µm, and very particularly preferably 25 to 70 µm.

[0325] In embodiments of the three-layer assembly D-T-C and the five-layer assembly C-T-D-T’-C’, the adhesive layers D and C or D and C and D and C’ have different layer thicknesses according to a preferred embodiment, wherein the thickness of the adhesive layer D is, for example, less than the thickness of the adhesive layer C or C and C’.

[0326] According to a further preferred embodiment, the layers D and C or D, C, and C’ have the same layer thickness.

[0327] If the layer thickness of layer D is too high, this may be uneconomical and costly due to the electrolyte contained therein.

[0328] The conductive substrate in all embodiments can be, for example, the metal housing of a mobile phone.

[0329] The non-conductive substrate in all embodiments can in particular be a housing or a battery made of a non-conductive material such as plastic or other non-conductive components such as speakers.

[0330] Another subject of the present invention is the use of the tape according to the present invention for bonding components in electronic devices, automotive, medical and dental devices. Description of the Drawings

[0331] Hereinafter, preferred embodiments of the present invention will be explained and described in more detail with reference to the drawings. The drawings show:

[0332] Figure 1 A simplified schematic cross-sectional view of the double-sided adhesive element according to the present invention through the preferred embodiment; and

[0333] Figure 2 A simplified schematic cross-sectional view of the double-sided adhesive element according to the present invention through the preferred embodiment; and

[0334] Figure 3 A simplified schematic cross-sectional view of the adhesive assembly according to the present invention through the preferred embodiment; and

[0335] Figure 4 A simplified schematic cross-sectional view of the adhesive assembly according to the present invention to which a voltage is applied through the preferred embodiment; and

[0336] Figure 5 A simplified schematic cross-sectional view of the adhesive assembly according to the present invention after applying a voltage and thereby achieving adhesive splitting; and

[0337] Figure 6 A simplified schematic cross-sectional view of the adhesive assembly according to the present invention through the preferred embodiment; and

[0338] Figure 7 A simplified schematic cross-sectional view of the adhesive assembly according to the present invention through the preferred embodiment. Detailed Description of the Invention

[0339] As Figure 1 shown, the adhesive layer D1 is bonded to the carrier layer T2 through one of its faces. A second adhesive layer C3 is arranged on the face of the carrier layer T opposite to the layer D. The carrier layer T includes a polymer film 2b connected to the adhesive layer C3 and a metal coating 2a on the polymer film 2b, wherein the metal coating 2a faces the adhesive layer D1.

[0340] As in Figure 1As can also be seen therein, the layer assembly represents a double-sided adhesive tape, where the surfaces of the adhesive layer D and the second adhesive layer C can be used for adhesion in each case.

[0341] In Figure 2 a preferred embodiment of the present invention is shown. In this case, the conductive carrier layer T2 laterally protrudes from the adhesive layer D1 in at least one extending direction of the layer plane, such that the conductive carrier layer T2 has a protrusion with a free surface 2c having a metal coating 2a. In Figure 2 it, the second adhesive layer C3 is designed such that the conductive carrier layer T2 is carried on the surface opposite to the free surface 2a, and thus also has a protrusion relative to the layer D.

[0342] Figure 3 a schematic view of the adhesive assembly according to the present invention in a preferred embodiment is shown. From Figure 3 it can be seen that the tape is arranged on the surface of the first substrate A4 through the adhesive layer D1, where the first substrate is conductive as described above.

[0343] In addition, the tape is arranged on the surface of the second substrate B5 through the second adhesive layer C3.

[0344] In Figure 3 it is also exemplified that the conductive carrier layer T2 laterally protrudes from the first adhesive layer D1 in at least one extending direction of the layer plane, such that the conductive carrier layer T has a protrusion with a free surface 2c. In Figure 3 it, the second adhesive layer C3 is designed such that the conductive carrier layer T2 is carried on the surface opposite to the free surface 2a, and thus also has a protrusion relative to the layer D.

[0345] Now a voltage can be applied to the free surface 2c, as shown in the schematic view according to Figure 4 .

[0346] By applying the voltage, the migration of the electrolyte occurs in the adhesive layer D1, especially the separation of the anions and cations of the ionic liquid.

[0347] Thereby, the adhesion of the adhesive layer D1 to the substrate A4 is greatly reduced, and these layers are separated from each other, as shown in the schematic view according to Figure 5 .

[0348] In Figure 6 another schematic view of the adhesive assembly according to the present invention in a preferred embodiment is shown. From Figure 6 it can be seen that the tape is arranged on the surface of the first substrate A4 through the adhesive layer C3.

[0349] Furthermore, the tape is arranged on the face of the second substrate B 5 by means of a third adhesive layer C’ 7.

[0350] Between the layers C 3 and C’ 7 are an electrically separable adhesive layer D 1 and two conductive carrier layers T 2 and T’ 6, with the layer D 1 being arranged between the carrier layers.

[0351] The conductive carrier layer T 2 comprises a polymer film 2b connected to the adhesive layer C 3 and a metal coating 2a on the polymer film 2b, with the metal coating 2a being arranged facing the adhesive layer D 1.

[0352] The conductive carrier layer T’ 6 comprises a polymer film 6b connected to the adhesive layer C’ 7 and a metal coating 6a on the polymer film 6b, with the metal coating 6a being arranged facing the adhesive layer D 1.

[0353] In Figure 6 it is also shown by way of example that the conductive carrier layer T 2 and the conductive carrier T’ 6 each project laterally in at least one extension direction of the layer plane beyond the first adhesive layer D 1, such that the conductive carrier layer T has a projection with a free face 2c and the conductive carrier T’ has a projection with a free face 6c. The second adhesive layer C 3 is designed such that it bears the conductive carrier layer T 2 on the face opposite the free face 2c and thus also has a projection relative to the layer D. The third adhesive layer C’ 7 is also designed such that it bears the conductive carrier layer T’ 6 on the face opposite the free face 6c and thus also has a projection relative to the layer D.

[0354] In Figure 7 a further schematic illustration of the adhesive assembly according to the invention in a preferred embodiment is shown, which is similar to the schematic illustration according to Figure 6 However, different from Figure 6 the projections of the conductive carrier layer T 2 and the conductive carrier layer T’ 6 point in different directions, such that the resulting free faces 2c or 6c of these layers are spatially separated.

[0355] In the case of the spatially separated faces 2c and 6c according to Figure 7 the application of the voltage is simplified.

[0356] Figures 1 to 7 The figures in

[0357] are purely schematic diagrams as shown, for the purpose of illustrating the layer structure and layer sequence. In particular, the layer thicknesses of the individual layers can differ from one another. Any differences in layer thickness between the figures are determined by the drawing without any statement, unless otherwise specified.

[0358] In the following, some embodiments are described to further clarify the present invention.

[0359] Test method

[0360] Unless otherwise specified, all measurements are carried out at 23 °C and 50% relative air humidity. The mechanical and adhesive technical data are determined as follows:

[0361] Molecular weight M n 、M w

[0362] The number average molecular weight M n or the weight average molecular weight M w data in this specification relate to the determination by gel permeation chromatography (GPC). The determination is carried out on 100 μl of a sample that has been subjected to clarification filtration (sample concentration 4 g / l). The eluent used is tetrahydrofuran containing 0.1% by volume of trifluoroacetic acid. The measurement is carried out at 25 °C. The pre-column used is a PSS-SDV type column, 5 µm, 10 3 , 8.0 mm 50 mm (herein and hereinafter described in the following order: type, particle size, porosity, inner diameter length; 1 = 10 -10 m). Columns of type PSS-SDV, 5 µm, 10 3 and 10 5 and 10 6 (each 8.0 mm 300 mm) columns (columns from Polymer Standards Service; detected with a differential refractometer Shodex RI71) are used for separation. The flow rate is 1.0 ml / minute. For polar molecules such as polyurethane starting materials, calibration is carried out against a PMMA standard (polymethyl methacrylate calibration), otherwise calibration is carried out against a PS standard (polystyrene calibration).

[0363] Softening temperature of the adhesive resin

[0364] The softening temperature of the adhesive resin is carried out according to the relevant methodology known as the ball ring and standardized according to ASTM E28.

[0365] Thickness

[0366] The thickness of the adhesive layer can be determined as follows: Measure the thickness of such an adhesive layer applied to the backing over a portion (or section) defined by its length and its width, and subtract the thickness of a portion (or section) of the backing used, having the same dimensions (known or separately determinable). A commercial thickness gauge (probe instrument) with a precision of less than 1 μm deviation can be used to determine the thickness of the adhesive layer. If fluctuations in the thickness are measured, report the average of the measured values at at least three representative locations, i.e., in particular, do not measure at wrinkles, creases, tips, etc.

[0367] Similar to the thickness of the adhesive layer, the thickness of the tape (adhesive strip) or the carrier can also be measured analogously using a commercial thickness gauge (probe instrument) with a precision of less than 1 μm deviation. If fluctuations in the thickness are measured, report the average of the measured values at at least three representative locations, i.e., in particular, do not measure at wrinkles, creases, tips, etc.

[0368] Adhesive force

[0369] 180° Adhesive force test:

[0370] To test the adhesive force of the electrically separable layer D to steel: A 20 mm wide strip of the tape according to the invention is adhered with the side of the adhesive layer C to a 23 µm thick PET film.

[0371] The assembly is applied with the electrically separable side (layer D) onto a steel plate, which has been washed twice with acetone and once with isopropanol beforehand. The adhesive strip is pressed onto the substrate with a pressing force corresponding to a weight of 2 kg twice. Then immediately pull the tape off the substrate at a speed of 300 mm / min and an angle of 180°. All measurements are carried out at room temperature.

[0372] The measurement results are reported in N / cm and are the average of three measurements.

[0373] To measure the adhesive force after applying a voltage, the tape is adhered to the steel plate in the manner described above. Apply a DC voltage of 12 V, and precisely, place the negative pole at the steel plate and the positive pole at the protrusion of the metallized polymer film, or more precisely: at the free surface of the metal coating.

[0374] After 60 seconds, turn off the voltage and immediately tension the sample in the measuring device and measure the adhesive force.

[0375] To test the adhesive force of layer C to steel: The measurement is carried out in a similar manner, where first a 20 mm wide strip of the tape according to the invention is adhered with the electrically separable adhesive side (layer D) to a 23 µm thick PET film, and then the assembly is applied with the other side (layer C) to the steel plate, etc.

[0376] Optical density (OD)

[0377] Optical density OD is a measure of the attenuation experienced by light as it passes through a substance. If the illumination intensity before passing through is E0 and the illumination intensity after passing through is E, then the transparency , and the opacity is . OD is the decimal logarithm of opacity. OD 1 represents attenuation to one-tenth of the original illumination intensity, and OD 2 represents attenuation to one-hundredth of the original illumination intensity. The optical density is determined by a densitometer from Heiland electronic GmbH.

[0378] Optical defects

[0379] Samples of the examples are stored under damp heat conditions, where they are stored for 7 days at a temperature of 60 °C and a humidity of 95%, and then inspected for optical defects, in particular defects that may be caused by corrosion.

[0380] Example 1 according to the invention

[0381] The adhesive layer D is provided in the following manner:

[0382] The acrylate-based base polymer is prepared as follows: A reactor conventionally used for free radical polymerization is charged with 48 kg of 2-ethylhexyl acrylate, 48 kg of n-butyl acrylate, 4 kg of acrylic acid, and 66 kg of volatile oil / acetone (70 / 30). After passing nitrogen through for 45 minutes, the reactor is heated to 58 °C with stirring, and 50 g of AIBN is added. Then the external heating bath is heated to 75 °C, and the reaction is continued at this external temperature. After a reaction time of 1 hour, another 50 g of AIBN is added, and after 4 hours, it is diluted with 20 kg of a gasoline / acetone (70 / 30) mixture. Post-initiation is carried out with 150 g of bis(4-tert-butylcyclohexyl) peroxydicarbonate at 5.5 hours and at 7 hours, respectively. The polymerization reaction is stopped after a reaction time of 22 hours and cooled to room temperature. The polyacrylate has an average molecular weight of M w = 386000 g / mol, and a polydispersity PD (M w / M n ) = 3.6.

[0383] Based on the amount of the solvent-free polymer by 100% by weight, 5.5% by weight of the ionic liquid 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (EMIM-TFSI) is added.

[0384] Furthermore, 0.1% by weight of the crosslinking agent Erysis GA240 (tetraglycidyl m-xylene diamine) is added based on the amount of the solvent-free acrylate polymer.

[0385] The obtained mixture is then applied with a spreading rod onto a PET liner equipped with a silicone release, thereby producing a layer thickness of 50 µm after drying at 110 °C.

[0386] The adhesive layer C is provided in the following manner:

[0387] An acrylate-based polymer is prepared as described above for the adhesive layer D. 0.1 wt% of the crosslinker Erysis GA 240 based on the amount of the solvent-free acrylate polymer is added.

[0388] This adhesive is also applied onto a PET liner equipped with a silicone release. After drying at 110 °C, the layer thickness is also 50 µm here.

[0389] As the carrier T layer, a 23-µm-thick PET film is used, which is vapor-deposited with tin (98 to 100 wt% tin) on one side and thus has a polymer side and a metallized side. After vapor deposition, the optical density of the film is 2.3.

[0390] Then, the carrier layer is laminated onto the adhesive C, with the polymer side of the carrier layer T facing the adhesive layer C.

[0391] Then the assembly is laminated with the metal side of the assembly onto the adhesive D, such that the metal layer (98 to 100 wt% tin), together with the adhesive C, projects in at least one direction beyond the adhesive layer D, preferably by at least 1 cm. The thickness of the assembly is 123 µm.

[0392] The adhesion of the assembly to steel is measured according to the method described above.

[0393] On the electrically separable side, i.e., on the free surface of the adhesive layer D, it is 4.5 N / cm, and on the adhesive layer C it is 6.4 N / cm.

[0394] As described above, the separation force is measured after applying a voltage of 12 V for 1 minute.

[0395] Then the adhesion of the tape to the steel plate is measured again. Now the adhesion is only 0.2 N / cm.

[0396] The adhesion can be significantly reduced by applying a voltage.

[0397] Then, another tape sample (including the liner) is stored at a temperature of 60 °C and a humidity of 95% for 7 days.

[0398] After being taken out of the humidity cabinet, the tape is conditioned at 23 °C and 50% humidity for 2 hours. Thereafter, the tape is optically inspected to detect defects, and the adhesion and the separation force are measured again in the manner described above.

[0399] No defects were recognized, neither the surface transparency of the specimen nor separate small metal-free points.

[0400] The adhesive force on the separable side was 4.7 N / cm.

[0401] The separation force after applying voltage was 0.2 N / cm.

[0402] According to Example 2 of the present invention

[0403] According to Example 2 of the present invention, corresponding to Example 1, the difference is that instead of tin, a film with chromium (98 to 100% by weight chromium) metallization is used.

[0404] According to Example 3 of the present invention

[0405] According to Example 3 of the present invention, corresponding to Example 1, the difference is that instead of tin, a film with nickel (98 to 100% by weight nickel) metallization is used.

[0406] According to Example 4 of the present invention

[0407] According to Example 4 of the present invention, corresponding to Example 1, the difference is that instead of tin, a film with titanium (98 to 100% by weight titanium) metallization is used.

[0408] According to Example 5 of the present invention

[0409] According to Example 5 of the present invention, corresponding to Example 1, the difference is that instead of tin, a film with steel (88% iron and 12% chromium) metallization is used.

[0410] Comparative Example V1

[0411] Comparative Example V1 corresponds to Example 1, the difference is that instead of tin, a film with aluminum (98 to 100% by weight aluminum) metallization is used.

[0412] Comparative Example V2

[0413] Comparative Example V2 corresponds to Example , the difference is that a film with copper (98 to 100% by weight copper) metallization is used.

[0414] Comparative Example V3

[0415] Comparative Example V3 corresponds to Example 1, the difference is that a film with silver (98 to 100% by weight silver) metallization is used.

[0416] The results of the examples and comparative examples according to the present invention are summarized in Table 1.

[0417] Table 1

[0418]

[0419] These examples show that high adhesion can be obtained on steel before applying voltage. This also applies to samples stored under humid and hot conditions.

[0420] By applying voltage, in all embodiments according to the present invention, the adhesion can be reduced to such an extent that the substrates can be separated from each other without consuming a large amount of force.

[0421] In this case, the adhesive layer D can be separated from the corresponding substrate in a residue - free manner in particular.

[0422] However, as shown in Table 1, only for embodiments according to the present invention, where the metal of the metal coating of the polymer film is selected from tin, chromium, nickel, titanium, and iron, can it be successfully ensured that even after storage under humid and hot conditions, the tape has no optical defects and thus no signs of corrosion.

[0423] List of reference numerals

[0424] 1 Adhesive layer D

[0425] 2 Conductive carrier layer T

[0426] 2a Metal coating of the conductive carrier layer T

[0427] 2b Polymer film of the conductive carrier layer T

[0428] 2c Free surface of the conductive carrier layer

[0429] 3 Second adhesive layer C

[0430] 4 First substrate A

[0431] 5 Second substrate B

[0432] 6 Second conductive carrier layer T’

[0433] 6a Metal coating of the conductive carrier layer T’

[0434] 6b Polymer film of the conductive carrier layer T’

[0435] 6c Free surface of the conductive carrier layer T’

[0436] 7 Third adhesive layer C’

Claims

1. A tape, comprising at least the following layers: - A first adhesive layer D, wherein the adhesive layer D contains at least one electrolyte; and - A second adhesive layer C; and - A conductive carrier layer T disposed between layers D and C, wherein the conductive carrier layer comprises a polymer film, and wherein the polymer film has a metal coating on the surface facing layer D, and wherein the metal of the metal coating is selected from tin, chromium, nickel, titanium, and iron to an extent of at least 70 wt%, preferably at least 80 wt%, particularly preferably at least 90 wt%.

2. The tape according to claim 1, wherein, The electrolyte of the adhesive layer D is selected from ionic liquids and metal salts, with ionic liquids being particularly preferred.

3. The tape according to claim 2, wherein The anions of the ionic liquid are selected from: , , , , , , , , , , , , , , , , , , and are particularly preferably selected from , and .

4. The adhesive tape according to claim 2 or 3, characterized in that, The cation of the ionic liquid is selected from cations based on imidazole cations, cations based on pyridine cations, cations based on pyrrolidine and cations based on ammonium, and is particularly preferably selected from cations based on imidazole cations, wherein the cations are particularly preferably selected from 1-ethyl-3-methylimidazole and 1-butyl-3-methylimidazole , and the cation is very particularly preferably 1-ethyl-3-methylimidazole .

5. The adhesive tape according to one of the preceding claims, characterized in that, The electrolyte of the adhesive layer D is selected from the following ionic liquids: 1-ethyl-3-methylimidazole bis(trifluoromethylsulfonyl)imide (EMIM-TFSI), 1-ethyl-3-methylimidazole bis(fluorosulfonyl)imide (EMIM-FSI), 1-ethyl-3-methylimidazole hexafluorophosphate and 1-butyl-3-methylimidazole hexafluorophosphate.

6. The adhesive tape according to one of the preceding claims, characterized in that, The first adhesive layer D is based on poly(meth)acrylate.

7. The adhesive tape according to one of the preceding claims, characterized in that, The first adhesive layer D contains 2 to 10 wt%, preferably 4 to 8 wt%, of an electrolyte, preferably an ionic liquid, based on 100 wt% of the contained polymer.

8. The adhesive tape according to one of the preceding claims, characterized in that, The polymer of the polymer film is selected from polyester, polyethylene, polypropylene, polyolefin, or polyurethane, and wherein the polymer film is particularly preferably made of polyester, particularly a polymer film based on polyethylene terephthalate (PET) or polybutylene terephthalate, with polyethylene terephthalate being preferred.

9. The tape according to any one of claims 1 to 8, characterized in that, The tape comprises at least the following layers: A first adhesive layer D, wherein the adhesive layer D contains at least one electrolyte; and A second adhesive layer C; and A conductive carrier layer T disposed between layers D and C, wherein the conductive carrier layer comprises a polymer film, and wherein the polymer film has a metal coating on the surface facing layer D, and wherein the metal of the metal coating is selected from tin, chromium, nickel, titanium, and iron to an extent of at least 70 wt%, preferably at least 80 wt%, particularly preferably at least 90 wt%; and At least one second conductive carrier layer T', which is disposed on the surface of the adhesive layer D opposite to the carrier layer T, and wherein the second conductive carrier layer T' also comprises a polymer film, and wherein the polymer film has a metal coating on the surface facing layer D, and wherein the metal of the metal coating is selected from tin, chromium, nickel, titanium, and iron to an extent of at least 70 wt%, preferably at least 80 wt%, particularly preferably at least 90 wt%; and A third adhesive layer C', which is disposed on the surface of the second carrier layer T' opposite to the first adhesive layer D.

10. An adhesive assembly, comprising at least the following layers: The first substrate A; and A second substrate B; and The tape according to any one of claims 1 to 9, which is disposed between the substrates A and B and bonds the substrates A and B to each other.

11. A method for electrically separating the adhesive assembly according to claim 10, comprising at least the following method steps: i.) Applying a voltage at two different sites of the assembly, wherein the voltage is preferably 2 to 50 V.

12. Use of the tape according to any one of claims 1 to 9 for bonding components in electronic devices, automobiles, medical devices, and dental devices.

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