Electronically detachable tape system comprising a film D and a primer composition containing a heat-activatable reactive adhesive

Abstract

The present invention relates to a tape system comprising a film D consisting of a heat-activatable reactive adhesive and a primer composition, a method of manufacturing an adhesive composite using said tape system, an adhesive composite manufactured by said method, a method of electro-debonding said adhesive composite and the use of said adhesive composite. The tape system comprises: (i) a film D of a heat-activatable reactive adhesive, wherein said heat-activatable reactive adhesive comprises at least one electrolyte; and (ii) a primer composition which is intended to form a separate layer and comprises at least the following ingredients: (a) at least one thermoplastic polyurethane; and (b) at least one organosilane.

Description

Technical Field

[0001] This invention relates to adhesive tape systems comprising a film D composed of a thermally activated reactive adhesive and a primer composition, a method for manufacturing an adhesive compound using said tape system, the adhesive compound manufactured by said method, a method for electro-debonding said adhesive compound, and the use of said adhesive compound. Background Technology

[0002] Bonding metal parts to plastics is typically accomplished using double-sided pressure-sensitive adhesive tape. This requires sufficient adhesive strength to secure the metal parts firmly to the plastic. Preferred metals are steel, stainless steel, and aluminum. Examples of plastics used are PVC, ABS, PC, or blends based on these plastics. Furthermore, non-conductive materials can be made conductive through suitable conductive coatings and similar processes, and are also bonded.

[0003] However, the demands on portable consumer electronics are constantly increasing. These products are becoming smaller, and therefore the bonding area is also decreasing. These conditions are particularly problematic for metal bonding on plastics. Such bonding can be achieved particularly effectively by using a thermally activated film, which can produce exceptionally high adhesive strength after activation.

[0004] DE 10 2021 200 580 A1 discloses, for example, adhesive films that are cured by heat, wherein the adhesive film is based on a formulation in an organic solvent comprising a thermoplastic polymer that can react with an isocyanate via functional groups and a corresponding isocyanate-containing crosslinking agent component. However, not all substrates to be bonded are suitable for activation temperatures of 80°C or higher.

[0005] Recently, interest in "on-demand debonding" capabilities has been increasing, driven by environmental legislation, end-customer awareness of sustainability, and rising cost pressures in production. Debonding processes are used in rework, repair, recycling, and as processing aids.

[0006] Debonding techniques aim to achieve either cohesive splitting of the adhesive layer or detachment of the adhesive layer from the substrate. While the former requires cleaning at least one substrate before re-bonding in any case, the latter leaves the substrate residue-free. Therefore, adhesive splitting is preferred to avoid additional cleaning steps that could compromise substrate properties. However, adhesive debonding techniques that guarantee the required high and durable reliable bond strength are often relatively difficult to implement, or their application, such as debonding using penetrating solvents, is very time-consuming. For example, particularly in the rework or repair of electronic devices (such as smartphones and tablets), cohesive splitting adhesives are currently primarily used, typically in the form of pressure-sensitive tapes, whose cohesive force is reduced by increasing temperature to a level where manual cohesive separation of the bond is possible. This results in significant rework to prepare substrate surfaces contaminated with adhesive residue for re-bonding.

[0007] In addition to thermally mediated separation methods, electro-separation methods are being discussed. For example, EP 3 031 875 B1 discloses reducing the adhesive strength of acrylate adhesives containing surfactants by applying a voltage. This achieves, for example, a reduction in adhesive strength of 29% to 98%.

[0008] However, heat-activated adhesives typically exhibit very high bond strength. These tape solutions are generally not re-detachable, at least not without damaging the substrates they are bonded to and without applying very high forces. Summary of the Invention

[0009] Therefore, the object of the present invention is to provide a tape system for manufacturing composites that are thermally bonded and optionally re-detachable, wherein the adhesive can be removed by a gentle separation method with minimal residue levels and minimal applied force. Simultaneously, the method for manufacturing the adhesive composite should be feasible in a manner that allows for substrate-conserving. Furthermore, the bonded composite should possess improved adhesive strength and improved impact resistance.

[0010] This objective is achieved by the tape system according to the invention and by the method for manufacturing the adhesive compound according to the invention, and therefore also by the adhesive compound manufactured by the method according to the invention. This objective is also achieved by the method for electrically debonding the adhesive compound according to the invention and the use of the adhesive compound. Attached Figure Description

[0011] Preferred embodiments of the invention are illustrated and described in more detail below with reference to the accompanying drawings. These drawings show:

[0012] Figure 1A simplified schematic cross-sectional view of the adhesive compound according to the invention in a preferred embodiment; and

[0013] Figure 2 A simplified schematic cross-sectional view of the adhesive compound according to the invention in a preferred embodiment; and

[0014] Figure 3 A simplified schematic cross-sectional view of the adhesive compound according to the invention being subjected to voltage in a preferred embodiment; and

[0015] Figure 4 A simplified schematic cross-sectional view of the adhesive compound according to the invention after voltage has been applied and adhesive splitting has therefore occurred; and

[0016] Figure 5 A simplified schematic cross-sectional view of the adhesive compound according to the invention in a preferred embodiment. Detailed Implementation

[0017] The features referred to below as preferred embodiments, particularly preferred embodiments, and other preferred embodiments are combined. Therefore, combinations of two or more of the embodiments referred to below as particularly preferred are very particularly preferred. Equally preferred are embodiments in which a feature referred to as a preferred embodiment in any degree is combined with one or more further features referred to as other preferred embodiments in any degree. Thus, the invention includes various features combined with each other, and combinations having different levels of preference. For example, the invention includes, for instance, a combination of a first feature referred to as “preferred” and a second feature referred to as “particularly preferred.” The features of preferred adhesive compounds and methods of use and debonding will be particularly evident from the features of preferred tape systems and / or methods of manufacturing adhesive compounds.

[0018] The tape system according to the present invention comprises:

[0019] (i) a film D of a thermally activated reactive adhesive, wherein the thermally activated reactive adhesive comprises at least one electrolyte; and

[0020] (ii) A primer composition intended to form a single layer and comprising at least the following components:

[0021] (a) at least one thermoplastic polyurethane; and

[0022] (b) At least one organosilane.

[0023] The method for manufacturing an adhesive compound according to the present invention comprises at least the following method steps:

[0024] i. Provide a conductive substrate A or a conductive carrier layer T;

[0025] ii. A membrane D providing a thermally activatable reactive adhesive, wherein the thermally activatable reactive adhesive contains at least one electrolyte;

[0026] iii. Providing a primer composition, wherein the primer composition comprises at least the following components:

[0027] (a) at least one thermoplastic polyurethane; and

[0028] (b) at least one organosilane;

[0029] iv. Make the surface of substrate A or the surface of carrier layer T contact the first surface of film D;

[0030] v. Wherein prior to contact between substrate A and the first surface of film D or between carrier layer T and the first surface of film D, a primer composition from step iii. is applied as layer P; and

[0031] x. Activate membrane D by providing heat at 40°C or higher and by applying a pressing pressure greater than 1 bar.

[0032] Surprisingly, it has been found that using the tape system according to the invention, the method according to the invention produces an adhesive composite that has improved adhesive strength and impact resistance compared to the prior art, but is simultaneously capable of electro-debonding by applying voltage. Electro-debonding is permitted by the electrolyte present in the adhesive. Despite having high initial adhesive strength, the method of electro-debonding the composite allows the adhesive to be removed with very little force and without adhesive film residue. It has been found that this is possible only when using a specified primer composition, and not when using other primer compositions from the prior art. Furthermore, it has been found that in the manufacture of the adhesive composite, the activation temperature of the thermally activated reactive adhesive can be lowered, and adhesive strength as high as that achieved in the prior art at higher temperatures can be achieved.

[0033] This permits the use of tape systems and methods for manufacturing adhesive compounds using tape systems, or adhesive compounds and electro-debonding methods, in sensitive applications involving heat-sensitive substrates.

[0034] Methods for electrically re-detaching or electrically reducing adhesive strength are known in principle in the prior art. For example, as mentioned above, EP 3 031 875 B1 discloses such an electrical method. Here, the electrically detachable adhesive is based on acrylate.

[0035] However, it is not foreseen in the context of this invention that even thermally activated adhesives with relatively high bonding strength to different substrates can be electrically debonded after bonding, and surprisingly, when using the primer described in detail, there is an improvement in bonding strength before debonding, and as described, the activation temperature of reactive adhesives can even be reduced.

[0036] The invention is described in detail below.

[0037] The expressions "at least one" or equivalents "one or more" refer to the chemical properties of the entity in question, rather than its amount of substance, in a manner commonly used in the industry. Therefore, those skilled in the art will understand that the expression "electrolyte" refers to a plurality of electrolyte molecules.

[0038] As usual, "%weight" here represents a percentage of weight. This applies to all the details given.

[0039] In the context of this invention, "tape system" means a functional unit consisting of several coordinated components that together achieve a specific technical effect—particularly improved adhesion and electrical detachability. The tape system according to the invention always comprises a film D of a thermally activated reactive adhesive and a primer composition. It is necessary that the primer composition be provided within the system to form a separate, independent layer arranged to be applied between the film D and the substrate or carrier layer to be bonded.

[0040] Substrate A or carrier layer T (step i.)

[0041] In step i, a conductive substrate A or a conductive carrier layer T is provided.

[0042] Therefore, at least between the conductive substrate A and the film D of the thermally activated reactive adhesive, after appropriate activation, or at least between the conductive carrier layer T and the film D of the thermally activated reactive adhesive, after appropriate activation, an adhesive composite with improved adhesive strength and very good electrical detachability is produced.

[0043] In the context of this invention, a distinction is made between a substrate and a carrier layer. A substrate refers to an article component or article for which an adhesive film is to be used to provide adhesive bonding.

[0044] The carrier layer refers to the additional layer of the tape besides the reactive adhesive film D, which, as is known to those skilled in the art of tape, also has adhesive support, spatial stability, and therefore load-bearing functions.

[0045] The substrate and carrier layer are described in detail below in the description of possible structures involving the adhesive compound.

[0046] The thermally activated reactive adhesive film D (step ii) and the activation of the adhesive (step x).

[0047] In step ii, a film D composed of a thermally activated reactive adhesive is provided. Film D is part of the tape system according to the invention.

[0048] The film of an adhesive is a layer of any geometry, such as a circle, a square, any other form of rectangle, or any other geometric shape. This film is particularly in the form of an elongated sheet. An elongated sheet means an object whose length (in the x-direction) is many times greater than its width (in the y-direction), and whose width remains approximately and preferably identical throughout its length.

[0049] Thermally activated reactive adhesives are preferably non-adhesive before activation. To accurately represent this state, the adhesive layer is referred to as a film. However, in the context of this invention, when discussing adhesive films or tapes, particular emphasis is placed on the fact that the film achieves an adhesive effect, especially through activation.

[0050] Prior to use in the method according to the invention, the film can therefore be provided specifically as an activatable tape. Tape, particularly in the form of an elongated sheet, can be made in rolls, i.e., rolled up in the form of an Archimedean spiral, or manufactured as adhesive strips, such as in blank or die-cut pieces. For the purposes of this invention, the general expressions “film” or “adhesive film,” “tape,” and the synonymous “strip” encompass all sheet-like structures, such as films or film portions extending in two dimensions, strips having an extended length and a finite width, strip portions, etc., and finally, die-cut pieces or labels.

[0051] In addition to its longitudinal (x-direction) and transverse (y-direction) areas, the tape also has a thickness (z-direction) extending perpendicular to these two areas, with the transverse and longitudinal areas being many times larger than the thickness. The thickness is substantially very uniform across the entire area of ​​the tape, determined by its length and width, and preferably identical within tolerances.

[0052] Thermally activated reactive adhesives contain at least one electrolyte.

[0053] Based on the common understanding of those skilled in the art, “electrolyte” is understood in the present context to mean a compound that dissociates into ions in a solid, liquid, or dissolved state and moves in a directional manner under the influence of an electric field.

[0054] The electrolyte is selected from ionic liquids and metal salts, with ionic liquids being particularly preferred.

[0055] In particular, by using one or more ionic liquids as electrolytes, the tape can be easily detached without adversely affecting its adhesive properties. Ionic liquids offer the following advantages: they can be easily and uniformly dispersed in the polymer matrix of the adhesive, and the detachment is faster compared to using other electrolytes. Furthermore, the components of ionic liquids are non-volatile, especially at room temperature. Additionally, ionic liquids are relatively heat-resistant and non-flammable, and are chemically relatively stable.

[0056] Therefore, in the context of the separation / electro-deadhesion method of the present invention, ionic liquids are particularly well-suited as electrolytes. When a voltage is applied, the adhesion strength of the ionic liquid-containing adhesive to at least one substrate decreases, which achieves adhesive separation between the adhesive and the bonded surface.

[0057] In the context of this invention, all ionic liquids are applicable in principle.

[0058] In the context of this invention, an ionic liquid is a salt that is liquid at 100°C and preferably at room temperature, i.e., 23°C. Therefore, an ionic liquid contains both anions and cations. Ionic liquids that are liquid at 100°C but solid at 23°C are preferably processed by suitable process steps, particularly and for example by dissolving them in a solvent.

[0059] The preferred type is an ionic liquid that is liquid at 23°C.

[0060] In the context of this invention, the preferred ionic liquid comprises at least one anion and at least one cation. It is also conceivable that the ionic liquid comprises two or more types of anions and / or two or more types of cations. It is also conceivable to add two or more different ionic liquids to an adhesive, or for the adhesive to then comprise two or more different ionic liquids.

[0061] Preferably, the anions of the ionic liquid are selected from:

[0062] Br - AlCl4 - Al2Cl7 - NO3 - BF4 - PF6 - CH3COO - CF3COO - CF3CO3 - CF3SO3 - (CF3SO2)2N - (CF3SO2)3C - AsF6 - SbF6 -CF3(CF2)3SO3 - (CF3CF2SO2)2N - CF3CF2CF2COO - N(CN)2 - and (FSO2)2N - .

[0063] More preferably, the anion is selected from (CF3SO2)2N - and (FSO2)2N - By applying voltage, this achieves a particularly high reduction in adhesion strength, and thus particularly good electroremovability. In particular, re-detachment is particularly rapid and leaves no residue.

[0064] Preferably, the cation of the ionic liquid is selected from imidazolium-based cations, pyridinium-based cations, pyrrolidineium-based cations, and ammonium-based cations.

[0065] Particularly preferably, the cation is selected from imidazolium-based cations. By applying a voltage, this achieves a particularly high reduction in adhesion strength, and thus particularly good electroremovability. In particular, re-detachment is particularly rapid and leaves no residue.

[0066] Even more preferably, the cation is selected from 1-ethyl-3-methylimidazole and 1-butyl-3-methylimidazole.

[0067] The electrolyte is more preferably selected from the ionic liquids bis(trifluoromethanesulfonyl)imide-1-ethyl-3-methylimidazolium (EMIM-TFSI) and bis(fluorosulfonyl)imide-1-ethyl-3-methylimidazolium (EMIM-FSI). By applying a voltage, this achieves a particularly high reduction in adhesive strength, and thus achieves particularly good electroremovability. In particular, (re)removal is particularly rapid and leaves no residue.

[0068] Preferably, the thermally activatable reactive adhesive of membrane D contains 1% to 10% by weight, more preferably 2% to 8% by weight, an electrolyte, preferably an ionic liquid, based on the total weight of the solvent-free adhesive.

[0069] Using such a preferred or particularly preferred amount of electrolyte, and especially ionic liquid, makes relatively rapid electro-desorption possible, while there is no adverse damage to the adhesion of the adhesive layer to adjacent layers, especially at least one substrate or at least one carrier layer, before desorption.

[0070] The material of adhesive layer D is a thermally activated reactive adhesive.

[0071] Heat-activated adhesives can be broadly classified into two categories: those that are purely physically heat-activated and those that are reactive heat-activated.

[0072] Adhesives that can be thermally activated by physical means

[0073] These adhesives, also known as "hot melt adhesives," have little or no self-adhesiveness at room temperature. The adhesive acquires self-adhesiveness only through heat activation. This is due to the correspondingly high glass transition temperature of the adhesive, which makes the activation temperature—typically tens to hundreds of degrees Celsius—above room temperature to achieve sufficient tack. Due to its self-adhesive nature, the adhesive effect occurs before the adhesive has set. After the adherends are joined, the physically heat-activated adhesive is physically set during cooling as it solidifies, allowing the adhesive effect to persist in the cooled state and exhibiting the actual strength of the adhesive force there.

[0074] The more heat, pressure, and / or time applied during bonding, the stronger the bond between the two materials to be bonded will generally become. Thus, maximum bond strength can often be achieved under technically easy processing conditions. Physical melting results in high bond strength and therefore adhesive effect. Therefore, the compound is a purely physically thermally activated adhesive.

[0075] Thermally activated reactive adhesives

[0076] Thermally activated reactive adhesives (also known as "reactive adhesives") are polymer systems that possess functional groups that allow for a chemical reaction when heat is applied, resulting in the adhesive being chemically fixed and thus exhibiting relatively high internal strength. It is also potentially advantageous to design reactive adhesives in such a way that they become softer and / or more fluid at elevated temperatures to optimally conform to the adhesive compound; this is particularly and preferably achieved through thermoplastic components. High adhesive strength and therefore a superior adhesive effect are achieved due to the chemical reaction and physical melting.

[0077] As can be inferred from the term "thermally activated," the activation that leads to the adhesive effect is achieved by providing heat. This means that at room temperature, and more specifically at 23°C, these adhesives are not activated, i.e., do not trigger the effect that leads to permanent adhesion.

[0078] Therefore, the method for manufacturing an adhesive compound according to the invention includes step x. Activating the film D by providing heat, such as at 40°C or higher. Activation is preferably carried out at a temperature of 40-120°C, more preferably 50-120°C, and most preferably 50-75°C. The specified temperature for achieving activation specifically relates to the temperature in the adhesive to be activated. These temperatures are achieved by a suitable heat supply.

[0079] It has been discovered, surprisingly, that very high adhesive strength can be achieved even at temperatures of 40 to 75°C, particularly 50 to 75°C, using the method according to the invention, which means it is suitable for heat-sensitive substrates and, possibly, carrier materials.

[0080] The activation duration is preferably 10 seconds to 10 minutes, more preferably 10 seconds to 8 minutes. In a preferred embodiment of the invention, the duration is 40 seconds to 8 minutes. In a preferred embodiment of the invention, the duration is 30 seconds to 6 minutes, more preferably 60 seconds to 3 minutes. Using these relatively short activation times, rapid and very stable adhesion is achieved.

[0081] In this case, at high activation temperatures within the stated temperature range, a correspondingly shorter activation duration is preferred, while at low temperatures, a correspondingly longer activation duration is preferred. This also depends particularly on the desired adhesive strength.

[0082] Activation is also achieved by applying pressure (also known as pressing pressure). The pressing pressure is greater than 1 bar, preferably 1 to 15 bar, and more preferably 2 to 12 bar.

[0083] Activation is achieved, particularly and preferably, by applying a hot press to the parts to be bonded. This provides the necessary heat and pressure input to the entire system.

[0084] Prior to activation, especially in the case of a dry and therefore relatively rigid film D, it is preferable to perform so-called pre-lamination to achieve optimal wetting of the substrate or surface to be bonded by the adhesive to be thermally activated. This is done, in particular and for example, by preheating the substrate to be bonded.

[0085] Preferably, for this purpose, the substrate to be bonded is heated to a temperature of 50 to 70°C. The adhesive layer is applied to the respective substrate preferably under a pressure of 1 to 3 bar for a duration of 5 to 20 seconds. This ensures that the adhesive flows uniformly onto the substrate before activation.

[0086] In the case of bonding to a conductive carrier layer, particularly and preferably, the carrier layer is heated when the provided film D has dried, so as to also promote or ensure adaptation.

[0087] In the context of this invention, the primer composition is preferably applied to the substrate or carrier layer in advance during the preheating step.

[0088] The heat-activated reactive adhesive preferably contains at least one thermoplastic elastomer. The thermoplastic elastomer can, in principle, include all thermoplastic polymers suitable for heat-activated adhesives, such as more particularly polyurethane, polyester, and polyamide. Particularly preferred is thermoplastic polyurethane (TPU). The polyurethane is preferably a semi-crystalline polyurethane.

[0089] Suitable polyurethanes are, for example, IROSTIC from Huntsman. ® The family's commercially available products.

[0090] Preferably, the heat-activated adhesive comprises 65% to 98% by weight, more preferably 75% to 96% by weight, and most preferably 80% to 94% by weight of a thermoplastic elastomer, particularly a thermoplastic polyurethane, preferably a semi-crystalline, preferably hydroxyl-terminated thermoplastic polyurethane, based on the total weight of the solvent-free adhesive.

[0091] Thermally activated reactive adhesives can be based on different polymers and crosslinking chemicals and mechanisms.

[0092] The thermoplastic elastomer preferably contains functional groups that can react with isocyanates. The thermally activated reactive adhesive of film D contains an isocyanate-containing compound as a crosslinking agent.

[0093] Here, the preferred thermoplastic elastomer is at least one thermoplastic polyurethane, and more preferably a semi-crystalline thermoplastic polyurethane.

[0094] Functional groups that can react with isocyanates include, in particular, hydroxyl, amino, or urethane groups. In a particularly preferred embodiment of the invention, the functional group is a hydroxyl group.

[0095] Surprisingly, such thermally activated reactive adhesives exhibit exceptionally good electrical re-detachability after bonding, where the bond strength is drastically reduced by the application of voltage. Furthermore, separation occurs cleanly; this means that adhesive residue is not present on the substrate, or it can be easily removed, for example, manually.

[0096] Surprisingly, it has also been found that, depending on the type and area of ​​adhesive residue, it is possible to reuse the adhesive without removing it, and thus re-bond the substrate through the residue, which in turn brings environmental advantages.

[0097] In a preferred embodiment of the invention, a diisocyanate compound, particularly a toluene diisocyanate compound (TDI compound), such as a TDI dimer, is used as the isocyanate-containing compound, for example, as Dancure. ® 999 (1,3-bis(3-isocyano-4-methylphenyl)-1,3-diazacyclobutane-2,4-dione; solid form) is obtained, and / or isophorone diisocyanate (IPDI).

[0098] Preferably, the heat-activated adhesive contains 1% to 25% by weight, more preferably 2% to 15% by weight, and very advantageously 4% to 12% by weight of an isocyanate-containing compound, based on the total weight of the adhesive.

[0099] Preferably, the thermally activated reactive adhesive is based on an organic solvent and is therefore a solvent-based adhesive. In the context of this invention, solvent-based means that in the manufacture of the adhesive, one or more organic solvents are used when mixing the components—and if the viscosity requires it—but not water or any other inorganic solvent.

[0100] Organic solvents are used to dissolve polymers, particularly thermoplastic elastomers such as thermoplastic polyurethanes, used in adhesives. The organic solvents used are preferably anhydrous. According to preferred and illustrative embodiments, the organic solvent is selected from methyl ethyl ketone (MEK), butanone, acetone, toluene, ethyl acetate, and mixtures thereof.

[0101] Preferably, and for example, the solvent is anhydrous methyl ethyl ketone (MEK). However, the invention is not intended to be limited to the illustrative solvents mentioned. It will be apparent that other suitable solvents are those in which the polymer used, particularly thermoplastic elastomers such as thermoplastic polyurethanes, are soluble. Therefore, the organic solvent is selected from solvents in which thermoplastic polyurethanes are soluble.

[0102] In an advantageous embodiment of the invention, the thermally activatable reactive adhesive of film D preferably further comprises compounds derived from epoxides and / or epoxy compounds. Preferred are mono-, di-, tri-, or polyfunctional epoxides and / or epoxy compounds. These include, for example, compounds that are viscous / liquid at 23°C, such as N,N,N',N'-tetra(2,3-epoxypropyl)-m-xylene-a,a'-diamine and / or 7-oxabicyclo[4.1.0]heptane-3-carboxylic acid 7-oxabicyclo[4.1.0]hept-3-ylmethyl ester and / or compounds with melting / softening points above 23°C (so-called epoxy resins), such as Epiclon. ® N-673. Suitable examples are particularly bisphenol F epoxy resins, which, for example, can be marketed under the trade name Epiclon. ® The series of achievements.

[0103] The adhesive of membrane D may further contain conventional additives such as compatibilizers, emulsifiers, fillers, pigments, amines, and aging inhibitors.

[0104] The preferred compatibilizers are low molecular weight polyethers, such as polyethylene glycol (PEG) and / or polypropylene glycol (PPG), polyamines, polyvinylpyrrolidone, or aliphatic polyesters, which are uniformly miscible with the adhesive.

[0105] Thermoactive adhesives are manufactured by mixing the components, particularly as described, using organic solvents to dissolve the components, especially thermoplastic elastomers.

[0106] The substance is then spread—particularly from the solution—as a layer with a defined thickness and thus in the form of a film, and then dried to evaporate the solvent.

[0107] Primer composition and primer layer P (step iii)

[0108] The tape system according to the invention includes a primer composition provided for forming individual layers.

[0109] The term "primer" is a term known to those skilled in the art related to adhesive bonding.

[0110] In the context of this invention, the term "primer" specifically means a primer applied between two layers of material that is capable of interacting with the two layers (on a chemical or physical basis) and allowing them to adhere to each other.

[0111] A primer is generally considered a formulated product (usually containing more than one component) applied from the liquid phase by appropriate methods (immersion in the surface, coating, spraying, etc.). According to this definition, a primer should not only have the ability to allow adhesion, but also form a uniform primer layer on the substrate surface by adjusting its viscosity, wetting properties, drying speed, etc.

[0112] In the context of this invention, primer compositions are considered and described in particular with respect to their components and therefore with respect to “primer compositions”.

[0113] Because the primer composition used according to the present invention comprises a combination of (a) at least one thermoplastic polyurethane and (b) at least one organosilane, the adhesive composite of at least one substrate or at least one carrier layer with an activated adhesive film, using the primer composition between the substrate or carrier layer and the adhesive film, surprisingly exhibits improved adhesive strength. Simultaneously, the activation temperature of the adhesive film can be significantly reduced.

[0114] Therefore, the primer composition used according to the present invention allows for stronger adhesive bonding even in the case of temperature-sensitive substrates.

[0115] The thermoplastic polyurethane present according to the invention (a) preferably does not have free isocyanate groups. The content of free isocyanate groups is determined, in particular, by IR spectroscopy. Polyurethanes having free isocyanate groups, especially polyurethanes obtained as polyurethanes with terminal isocyanate groups, are moisture-curing and therefore cure upon contact with moisture due to the excess diisocyanate and / or polyisocyanate during the preparation of the polyurethane.

[0116] The thermoplastic polyurethane present according to the invention (a) is preferably hydroxyl-terminated, and therefore preferably has terminal OH groups. This polyurethane is not moisture-curing and therefore does not react with moisture. Therefore, it is particularly well-suited for preparing primer compositions according to the invention.

[0117] In a preferred embodiment, the polyurethane is a chemical reaction product of: a1) at least one diol and / or polyol, and a2) at least one diisocyanate and / or polyisocyanate, wherein the diol and / or polyol is preferably selected in excess relative to the diisocyanate and / or polyisocyanate in the reaction.

[0118] Useful diols / polyols are, in principle, all known aliphatic or aromatic dihydroxy or polyhydroxy functionalized substances, particularly all polyester diols / polyols, including all polycaprolactone diols / polyols, all polyester carbonate diols / polyols, all polyether diols / polyols, and all polybutadiene diols / polyols, as well as their related substances or derivatives. Furthermore, so-called chain extenders and / or crosslinking agents are also useful, meaning that di- or poly-hydroxy functionalized substances are understood to be not polymeric compounds.

[0119] The polyester diols / polyols available according to the present invention are polyesters having terminally bound hydroxyl groups.

[0120] Polyester glycols have two terminally bonded hydroxyl groups, i.e., they are bifunctional. In the case of polyester polyols, the number of terminally bonded hydroxyl groups is not well defined. Two or more hydroxyl groups may be present per molecule. Hereinafter, polyester polyols refer to those having more than two hydroxyl groups per molecule. Polyester glycols / polyols available according to the invention are generally obtained by the condensation polymerization of a glycol / polyol and a di / polycarboxylic acid, or, in the case of polycaprolactone polyols, by the ring-opening polymerization of ε-caprolactone and a di or polyfunctional initiator molecule.

[0121] Polyester carbonate diols are dihydroxy-functionalized polyesters whose molecular chains also include at least one carboxylic acid ester group. They can be obtained, for example, through the polymerization of diols, dicarboxylic acids, and dimethyl carbonate (DMC) or diphenyl carbonate (DPC). In the case of polyester carbonate polyols, the number of terminally bonded hydroxyl groups is not well defined. Two or more hydroxyl groups may be present per molecule. In this document, polyester carbonate polyols refer to those with more than two hydroxyl groups per molecule.

[0122] The polyether glycols / polyols available according to the present invention are polyethers having terminally bound hydroxyl groups. Polyether glycols have two terminally bound hydroxyl groups and are therefore bifunctional. The number of terminally bound hydroxyl groups is not well defined for polyether polyols. Two or more hydroxyl groups may be present per molecule. In this document, polyether polyols refer to those having more than two hydroxyl groups per molecule. The polyether glycols / polyols available according to the present invention are manufactured primarily from ethylene oxide, propylene oxide, or tetrahydrofuran by ring-opening polymerization or copolymerization using initiator molecules that determine functionality.

[0123] Polybutadiene glycol is a dihydroxy-functionalized polybutadiene produced from butadiene via anionic polymerization. Known commercial products include, for example, Krasol from Cray Valley. ® Products. Polybutadiene polyols can have two or more hydroxyl groups per molecule. In this article, polybutadiene polyols are those with more than two hydroxyl groups per molecule. They are manufactured from butadiene by free radical polymerization. Well-known commercial products are, for example, Poly bd® products from Cray Valley.

[0124] Examples of chain extenders are ethane-1,2-diol, propane-1,2-diol, propane-1,3-diol, 2-methylpropane-1,3-diol, butane-1,4-diol, butane-2,3-diol, propylene glycol, dipropylene glycol, cyclohexane-1,4-diethanol, or 2-ethylhexane-1,3-diol.

[0125] Examples of cross-linking agents are glycerol, trimethylolpropane, or butane-1,2,4-triol.

[0126] In a particularly advantageous embodiment of the invention, a1) at least one diol and / or polyol is selected from polyester diol, polyester polyol, polyester carbonate diol and polyester carbonate polyol, with polyester diol and / or polyester carbonate diol being particularly preferred.

[0127] a2) The diisocyanates and / or polyisocyanates available according to the present invention are all known aliphatic and / or aromatic diisocyanates and / or polyisocyanates. Diisocyanates have two isocyanate groups per molecule and are therefore bifunctional. Polyisocyanates have two or more isocyanate groups per molecule. In this document, polyisocyanate means those having more than two isocyanate groups per molecule.

[0128] Useful examples of di- and / or polyisocyanates are 1-isocyanomethyl-3-isocyano-1,5,5-trimethylcyclohexane (isophorone diisocyanate, IPDI), hexane 1,6-diisocyanate (hexamethylene diisocyanate, HDI), dicyclohexylmethane 4,4'-diisocyanate (H12MDI), toluene diisocyanate, diphenylmethane 4,4'-diisocyanate (4,4'-MDI) and / or m-tetramethylxylene diisocyanate (TMXDI), mixtures of said isocyanates, or chemically related isocyanates, such as dimers, trimers, or polymers containing, for example, urea, urea diketone, or isocyanurate groups.

[0129] Bifunctional starting materials, namely diols and diisocyanates, are particularly preferred.

[0130] In an advantageous embodiment, the diisocyanate used (a2) is diphenylmethane 4,4'-diisocyanate (4,4'-MDI) and / or hexane 1,6-diisocyanate (hexamethylene diisocyanate, HDI), more preferably diphenylmethane 4,4'-diisocyanate (4,4'-MDI).

[0131] According to an advantageous embodiment, polyester polyurethane is used as the thermoplastic polyurethane a). In this regard, the diol component obtained first is preferably a reaction product of a diol and a carboxylic acid, especially a dicarboxylic acid, which is a macromolecular diol. For example, the diol a1) used is hexane-1,6-diol and adicarboxylic acid adipic acid.

[0132] To accelerate the reaction of diols / polyols with diisocyanates / polyisocyanates, one or more catalysts known to those skilled in the art can be used, such as tertiary amines, organobismuths, or organotin compounds, to name just a few.

[0133] Bismuth and carbon-containing catalysts can be used very advantageously, preferably bismuth carboxylate or bismuth carboxylate derivatives, especially bismuth trinedecanoate, CAS No.: 34364-26-6. The concentration of the catalyst is matched with the diol / polyol and diisocyanate / polyisocyanate used. Typically, it is 0.01% to 0.5% by weight of the polyurethane to be manufactured.

[0134] The thermoplastic polyurethane (a) present according to the present invention is preferably a semi-crystalline thermoplastic polyurethane. This achieves the object of the present invention particularly effectively.

[0135] The thermoplastic polyurethane (a) according to the invention preferably has a storage modulus G' greater than 1 MPa as determined by DMA. More preferably, the storage modulus G' is greater than 5 MPa, more preferably greater than 15 MPa, particularly at most 100 MPa, and more preferably at most 50 MPa.

[0136] The energy storage modulus G' was determined by dynamic mechanical analysis (DMA) according to DIN EN ISO 6721-1:2019-09.

[0137] Measurements were performed using a TA HR20 (TA Instruments) rheometer. Approximately 0.1 g of particulate material was placed on the circular lower punch of the rheometer. The punching temperature was increased above the melting point of the material being tested, thus melting it. The molten material was flattened using a flat metal punch. This method was repeated 3 to 4 times until a layer thickness of approximately 1 mm was achieved. The upper punch was then brought into contact with the polymer film. Material leaking from the joint was removed.

[0138] The oven doors surrounding the parallel plates and shaft of the rheometer were closed, and the temperature was raised to 100°C and held for 5 minutes to release any residual stress. The axial force was then set to zero to maintain contact between the material and the plates. The temperature was set to -50°C and then increased from -50°C to 200°C at a rate of 5°C / min, while the parallel plates oscillated at a frequency of 1°Hz and 0.15% of the initial strain amplitude. Once the measured torque dropped below 1 g-cm, the strain was increased by 50% of the current value, with a maximum permissible strain amplitude of 10%.

[0139] For example, a suitable thermoplastic polyester polyurethane can be purchased from Coim under the trade name Laricol 1460. Another suitable thermoplastic polyester polyurethane can be purchased under the trade name IROSTIC. ® S-6558-06 was purchased from Huntsman.

[0140] In a preferred embodiment of the tape system, particularly during the process of manufacturing the adhesive compound, i.e., when the primer composition is applied to at least one surface of the substrate to be bonded and / or the carrier layer to be bonded and / or the film of the reactive adhesive, the primer composition used according to the invention comprises at least one solvent, particularly at least one organic solvent. The solvent in the primer composition is used to dissolve the thermoplastic polyurethane used in the primer composition. Therefore, it is preferred to use a tape system or a method for manufacturing the adhesive compound in which the primer composition provided for forming a single layer, or the primer composition provided in step iii and applied in step v, comprises at least one organic solvent, wherein the thermoplastic polyurethane (a) of the primer composition is soluble in said solvent.

[0141] Preferably, and for example, it is an anhydrous mixture of 80% by weight ethyl acetate and 20% by weight methyl ethyl ketone (MEK), or 100% methyl ethyl ketone or acetone. However, the invention is not intended to be limited to these illustrative solvents. It will be apparent that other solvents in which thermoplastic polyurethanes are soluble are also suitable.

[0142] The solvent evaporates, especially after the primer is applied, causing the primer or the applied primer layer P to dry.

[0143] Therefore, in the context of this invention, one considers an undried primer composition on the one hand, and a dried primer composition produced by the evaporation of solvent and water (particularly from the applied primer layer P) on the other hand.

[0144] In an advantageous embodiment of the invention, the primer composition before drying contains 2% to 10% by weight, preferably 3% to 8% by weight, more preferably 3% to 5% by weight of the at least one thermoplastic polyurethane(a), based on the total weight of the undried primer composition.

[0145] Preferably, the dried primer composition contains 70% to 90% by weight, more preferably 70% to 85% by weight, and most preferably 75% to 85% by weight of the at least one thermoplastic polyurethane(a), in each case based on the total weight of the dried primer composition.

[0146] If two or more different thermoplastic polyurethanes are present as component (a), then the amount refers to the total amount of thermoplastic polyurethanes.

[0147] These quantities result in particularly advantageous properties, especially the exceptionally high bond strength of adhesives bonded with primer compositions in adhesive compounds.

[0148] According to the present invention, the primer composition (b) contains at least one organosilane.

[0149] Organosilanes can, in principle, be R-Si(R...) known to those skilled in the art. 1 R 2 R 3 Any compound of type ) where R represents an organic group that may contain heteroatoms, and R 1 R 2 and R 3 The remaining groups on the silicon atom are preferably selected from alkoxy and alkyl groups. R 1 R 2 and R 3 Groups can be identical or different from each other independently.

[0150] More preferably, R 1 R 2 and R 3 It is an alkoxy group, and preferably further selected from methoxy and ethoxy groups.

[0151] In an advantageous embodiment of the invention, the organosilane (b) is selected from:

[0152] Trialkoxysilylalkyl succinic anhydride

[0153] Trialkoxyphenylsilane,

[0154] (3-Mercaptopropyl)trialkoxysilane,

[0155] (3-Aminopropyl)alkoxysilane,

[0156] 3-(2-Aminoethylamino)propyltrialkoxysilane,

[0157] Vinyltrialkoxysilane, and

[0158] (3-Glycidoxypropyl)trialkoxysilane.

[0159] In a particularly advantageous embodiment of the invention, the organosilane (b) is selected from:

[0160] Trialkoxysilylalkyl succinic anhydride

[0161] Trialkoxyphenylsilane,

[0162] (3-Mercaptopropyl)trialkoxysilane,

[0163] Vinyltrialkoxysilane, and

[0164] (3-Glycidoxypropyl)trialkoxysilane.

[0165] Preferred (3-glycidoxypropyl)trialkoxysilanes are (3-glycidoxypropyl)trimethoxysilane and / or (3-glycidoxypropyl)triethoxysilane.

[0166] The organosilane (b) present in the primer composition is most preferably at least one trialkoxysilyl alkyl succinic anhydride.

[0167] This surprisingly results in improved chemical stability and very good adhesive strength before and after storage in warm and humid conditions.

[0168] The alkyl moiety of the trialkoxysilyl alkyl succinic anhydride is preferably a straight-chain alkylene group having 1 to 10 carbon atoms, more preferably 3 to 8 carbon atoms. Propylene is particularly preferred. Therefore, the silane is preferably trialoxysilylpropyl succinic anhydride. Preferably, the trimektoxy groups within the molecule are identical. Preferably, the alkoxy group of the trialoxysilyl alkyl succinic anhydride is selected from methoxy and ethoxy groups.

[0169] In a particularly advantageous embodiment of the invention, the primer contains (3-triethoxysilylpropyl)succinic anhydride as a trialkoxysilylalkylsuccinic anhydride and thus as an organosilane (b).

[0170] In an advantageous embodiment of the invention, the amount of organosilane (b) present in the undried primer composition is 0.5% to 5.0% by weight, preferably 0.5% to 3.0% by weight, more preferably 0.5% to 1.5% by weight, based on the total weight of the undried primer composition.

[0171] In an advantageous embodiment of the invention, the amount of organosilane (b) present in the dried primer composition is 10% to 30% by weight, preferably 15% to 30% by weight, more preferably 15% to 25% by weight, based on the total weight of the dried primer composition.

[0172] In an advantageous embodiment of the invention, the total amount of thermoplastic polyurethane (a) to the total amount of organosilane (b), particularly (3-triethoxysilylpropyl)succinic anhydride, is 3:1 to 5:1, more preferably 3.5:1 to 4.5:1, even more preferably 3.75:1 to 4.25:1, particularly 4:1.

[0173] Organic solvents and water are not included in this ratio.

[0174] The particularly preferred dry primer composition used contains, based on the total weight of the dry primer composition:

[0175] (a) 75 to 85% by weight of at least one thermoplastic polyurethane

[0176] (b) 15% to 25% by weight of at least one organosilane.

[0177] Preferably, the total amount of components (a) and (b) is 98% to 100% by weight, particularly 100% by weight. In particular, if the total amount is less than 100% by weight, there is an amount of solvent that has not been evaporated or has not yet evaporated.

[0178] The primer composition is specifically manufactured by combining and mixing the components (a) and (b) with each other. This includes combining thermoplastic polyurethane and organosilane as separate substances. In particular, they are not reacted with each other beforehand, so that the manufacture of the primer composition according to the invention does not involve any silane-functionalized polyurethane.

[0179] The components are specifically mixed together in at least one organic solvent.

[0180] In the context of this invention, "solvent" means a solvent other than water, particularly an organic solvent.

[0181] The primer composition is particularly and preferably adjusted to the desired solids content, especially with respect to the desired viscosity, by adding an organic solvent, so that it is suitable for the corresponding conditions when applied to form an adhesive compound. In a preferred embodiment, the total amount of organic solvent is 85% to 98% by weight, preferably 93% to 98% by weight, particularly and for example 95% by weight, based on the total weight of the undried primer composition.

[0182] The primer is preferably applied manually (e.g., by brushing or spraying) or by machine (e.g., by coating or printing). If the primer contains solvents and / or water, it is then dried.

[0183] Therefore, applying a primer composition to a surface, such as a substrate, particularly a component and / or an adhesive, specifically and preferably produces an initially undried primer layer with a specific layer thickness.

[0184] The primer is preferably applied by a printing press, metering nozzle, scraper, brush or suitable stick.

[0185] In an advantageous embodiment, the primer is applied using a guided metering nozzle, such as the "EV Series Automatic Dispensing System" from Nordson EFD.

[0186] In a further advantageous embodiment, the primer is applied using a printing press.

[0187] Preferably, the primer is applied to the entire area (full area) of the substrate and / or adhesive film or carrier layer and / or adhesive film.

[0188] Alternatively, it is preferable to apply the primer at defined or arbitrary distances in each area, for example, in a circular motion.

[0189] The thickness of the primer layer was determined by laser optics (CLSM (confocal laser microscopy, from Keyence)).

[0190] Then, as already particularly and preferably described, the primer layer is dried before any additional layers are added to it, resulting in a dried primer layer with a correspondingly reduced layer thickness.

[0191] The primer layer P preferably has a thickness of 0.05 μm to 50 μm, particularly 0.05 μm to 10 μm, after drying. According to an advantageous embodiment, the primer layer P has a thickness of 0.5 to 5 μm after drying.

[0192] Primer application and contact (steps v. and iv.)

[0193] In the method according to the invention, in step iv., the surface of substrate A is brought into contact with the first surface of film D, or the surface of carrier layer T is brought into contact with the first surface of film D. This can, in principle, be accomplished by all methods known to those skilled in the art and by means of known devices and tools. This contact creates the adhesive surface for manufacturing the adhesive composite.

[0194] However, essential for this invention is that, in step v., prior to contact, the primer composition from step iii. is applied as layer P between the surfaces to be contacted. In this case, the primer composition is applied either to the first surface of film D and / or the surface of substrate A, or to the first surface of film D and / or the surface of carrier layer T. Thus, the primer composition can be applied to only one surface at a time or to both surfaces to be contacted.

[0195] After applying the primer, if a solvent is present in the applied primer composition, it is preferable to dry the primer layer P as described above. Depending on the layer thickness, drying can be relatively rapid.

[0196] The present invention also provides an adhesive compound manufactured by the method according to the invention.

[0197] The present invention also provides an adhesive composite comprising at least layers of APD or TPD in the order described above. Preferably, the adhesive composite according to the invention comprises layers in the order APDPB, wherein A and B are conductive substrates.

[0198] The adhesive compound according to the invention is applicable to all embodiments, especially those according to the method of the invention.

[0199] Other layers of the adhesive compound

[0200] The advantages achieved according to the invention are even reflected in the adhesion of the substrate or carrier layer to the thermally activated reactive adhesive film, because, as described, the specific primer composition has a surprising effect at this interface.

[0201] Meanwhile, the remaining structure of the adhesive composite can have any shape and additional layers. Therefore, the precursor product obtained from step v. can be combined with other substrates to create different tape geometries before activation to obtain the adhesive composite. For example, and preferably, the second surface of film D can be provided with a protective liner, and this surface can be bonded to another carrier layer, another substrate, or another adhesive at a later node through activation.

[0202] More preferably, in the method of manufacturing the adhesive compound, two substrates (substrate A and substrate B) are bonded together.

[0203] In a preferred embodiment of the invention, film D is a transfer tape, i.e., preferably without an additional layer, and the second substrate B is also conductive. In this case, the defined primer composition is more preferably also applied between the surface of the second substrate B and the second surface of film D.

[0204] Therefore, in a particularly preferred embodiment, the method according to the invention includes at least the following steps:

[0205] i. Provide conductive substrate A;

[0206] ii. A membrane D providing a thermally activatable reactive adhesive, wherein the thermally activatable reactive adhesive comprises at least one electrolyte;

[0207] iii. A primer composition is provided, wherein the primer composition contains at least the following components:

[0208] (a) at least one thermoplastic polyurethane; and

[0209] (b) at least one organosilane;

[0210] iv. Make the surface of the first substrate A contact with the first surface of the film D;

[0211] v. Wherein, prior to the contact between the first surfaces of substrate A and film D in step iv, a primer composition from step iii is applied as layer P;

[0212] vi. Provide conductive substrate B;

[0213] vii. Make the surface of substrate B contact the second surface of film D;

[0214] viii. In step vii., prior to the contact between the second surface of the substrate B and the film D, a primer composition from step iii. is applied as layer P';

[0215] x. Activate membrane D by providing heat at 40°C or higher and by applying a pressing pressure greater than 1 bar.

[0216] The adhesive composite obtained therefrom according to the invention comprises layers in the order APD-P'-B.

[0217] Depending on the characteristics of the second substrate B, especially if it is significantly different from the substrate A, the primer layer P' can be omitted, leading to the APDB implementation of the compound according to the invention.

[0218] Therefore, step viii in the above method is optional.

[0219] Alternatively, it can be conceivable that, in the aforementioned embodiments, another primer is applied between D and B.

[0220] In a further preferred embodiment, film D is bonded to conductive substrate A at a first surface and to conductive carrier layer T' at a second surface. This allows a voltage to be applied to carrier layer T' later in the adhesive compound, which is particularly advantageous if an additional non-conductive substrate is to be bonded to substrate A.

[0221] Depending on the properties of the carrier, the required adhesive strength between the film D and the carrier layer, and the chemical stability of the carrier layer to the primer, the primer can also be applied between the film D and the carrier layer T'.

[0222] In a particularly preferred embodiment, the defined primer composition is also applied between the surface of the conductive carrier layer T' and the second surface of the film D.

[0223] The resulting adhesive composite according to the invention comprises layers in the order APD-P'-T'. This advantageously achieves a higher bonding strength between the film D and the conductive carrier layer T', for example and particularly when the metallized film serves as the carrier layer T'.

[0224] However, if the adhesive strength of the membrane D to the carrier layer T' is sufficient, a structure without a second primer layer P' and therefore structure APD-T' is conceivable and preferred.

[0225] In a further preferred embodiment, film D is bonded to conductive carrier layer T. This adhesive compound is flexible in use and is particularly suitable for bonding other adhesive compounds of any structure, especially for bonding conductive and non-conductive substrates. According to the invention, the defined primer composition is also applied between film D and conductive carrier layer T.

[0226] Therefore, in a particularly preferred embodiment, the method according to the invention includes at least the following steps:

[0227] i. Provide a conductive carrier layer T;

[0228] ii. A membrane D providing a thermally activatable reactive adhesive, wherein the thermally activatable reactive adhesive comprises at least one electrolyte;

[0229] iii. A primer composition is provided, wherein the primer composition contains at least the following components:

[0230] (a) at least one thermoplastic polyurethane; and

[0231] (b) at least one organosilane;

[0232] iv. Make the surface of the carrier layer T contact the first surface of the membrane D;

[0233] v. Wherein prior to contact between the carrier layer T and the first surface of the film D, a primer composition from step iii. is applied as layer P; and

[0234] x. Activate membrane D by providing heat at 40°C or higher and by applying a pressing pressure greater than 1 bar.

[0235] The adhesive compound manufactured in this way according to the invention comprises layers in the order TPD.

[0236] In a further preferred embodiment, the composite APD-P'-T' or APD-T' is bonded to the second conductive substrate B via the still usable surface area T' of the carrier layer T' before or after thermal activation according to step x. Preferably, the carrier layer T' does not protrude beyond any other layer, particularly any adjacent adhesive layer. This allows the composite layers to be easily co-processed, particularly by stamping or otherwise transformed into the desired shape. Thus, such a structure has the advantages of simple manufacturability, and, in addition, the possibility of adjusting the tape stability via the carrier layer (one or more). A voltage can then be applied specifically to both conductive substrates A and B.

[0237] In this case, the adhesive layer between T' and B can also be a thermally activated reactive film D' containing at least one electrolyte, or a thermally activated reactive adhesive layer C' that does not contain an electrolyte and is otherwise made conductive, for example, by means of metal particles. Embodiments of the conductive adhesive layer C are listed below in the specification.

[0238] In addition, the adhesive layer C can be based on a conductive adhesive that cannot be thermally activated, such as a reactive adhesive that cures at low temperatures by UV or visible light energy, or, for example, a pressure-sensitive adhesive.

[0239] For example, and preferably, the adhesive compound APD-P'-T' or APD-T' is first generated by thermal activation. The compound CB is then generated separately. By contacting T' and C, and possibly subsequently activating the adhesive C, for example by UV, the compound APD-P'-T'-CB or APD-T'-CB is generated.

[0240] In a further preferred embodiment, the adhesive between T' and B is also a thermally activated reactive membrane D'. The composition of D' can particularly and preferably be the same as that of membrane D.

[0241] In the above embodiments, the primer may also be applied between T' and D' and / or between D' and B, or between T' and C' and / or between C' and B, to adjust the adhesive strength at these interfaces.

[0242] The primer is preferably applied between the substrate A / B and the corresponding adhesive film D / D', which, for example and preferably results in the configuration APD-T'-D'-P'-B.

[0243] In summary, the following embodiments are also preferred: wherein two conductive substrates A and B are bonded together by an adhesive tape system according to the invention, wherein the adhesive tape system further includes at least one conductive carrier layer, and the primer is applied to at least one surface of the adhesive film D and between adjacent layers according to the invention.

[0244] Therefore, in a preferred embodiment, the method for manufacturing an adhesive compound according to the invention includes additional method steps resulting from combinations with other layers mentioned depending on the type and implementation.

[0245] Therefore, the method for manufacturing the adhesive composite APD-T'-D'-P'-B according to the present invention, starting from the manufacture of APD-T', further includes, for example, the following steps before activation: providing a second thermally activatable reactive adhesive film D' containing at least one electrolyte, providing a second conductive substrate B, and applying a primer composition between D' and B to produce a second primer layer P'. The entire composite is then activated in step x.

[0246] In a further preferred embodiment, the membrane D is disposed between the first conductive carrier layer T and the second conductive carrier layer T'.

[0247] Depending on the properties of the carrier, the required adhesive strength between the film D and the carrier layer T', and the chemical stability of the carrier layer T' to the primer, the primer can also be applied between the film D and the carrier layer T'.

[0248] In a particularly preferred embodiment, the defined primer composition is also applied between the surface of the conductive carrier layer T' and the second surface of the film D.

[0249] The resulting adhesive composite according to the invention comprises layers in the order TPD-P'-T'. This advantageously achieves higher adhesive strength between the film D and the conductive carrier layer T', for example and particularly when the metallized film serves as the carrier layer T'.

[0250] However, if the adhesive strength of the membrane D to the carrier layer T' is sufficient, a structure without a second primer layer P' and therefore the structure TPD-T' is conceivable and preferred.

[0251] This adhesive compound, particularly in the implementation TPD-P'-T' or TPD-T', is flexible in use and can be used specifically for bonding two non-conductive substrates.

[0252] Therefore, in a preferred embodiment, the method according to the present invention includes at least the following steps:

[0253] i. Provide a conductive carrier layer T;

[0254] ii. A membrane D providing a thermally activatable reactive adhesive, wherein the thermally activatable reactive adhesive comprises at least one electrolyte;

[0255] iii. A primer composition is provided, wherein the primer composition contains at least the following components:

[0256] (a) at least one thermoplastic polyurethane; and

[0257] (b) at least one organosilane;

[0258] iv. Make the surface of the carrier layer T contact the first surface of the membrane D;

[0259] v. Wherein prior to contact between the carrier layer T and the first surface of the film D, a primer composition from step iii. is applied as layer P; and

[0260] vi. Provide a conductive carrier layer T';

[0261] vii. Make the surface of the carrier layer T' contact the second surface of the membrane D;

[0262] viii. Optionally, in step vii., a primer composition from step iii. is applied as layer P' prior to contact between the carrier layer T' and the second surface of the film D;

[0263] x. Activate membrane D by providing heat at 40°C or higher and by applying a pressing pressure greater than 1 bar.

[0264] The adhesive composite obtained therefrom according to the invention comprises layers in the order TPDP-T'.

[0265] When the adhesive composite of the present invention having the layer sequence TPD-P'-B (or TPDB) is produced by a similar method, and B is used as a conductive substrate, this corresponds to the case of APD-P'-T' (or AD-P'-T'). Therefore, this embodiment of the present invention will not be described in detail.

[0266] In summary, in the preferred embodiment, the method for manufacturing the adhesive compound according to the present invention includes at least the following method steps:

[0267] i. Provide a conductive substrate A or a conductive carrier layer T;

[0268] ii. A membrane D providing a thermally activatable reactive adhesive, wherein the thermally activatable reactive adhesive comprises at least one electrolyte;

[0269] iii. A primer composition is provided, wherein the primer composition contains at least the following components:

[0270] (a) at least one thermoplastic polyurethane; and

[0271] (b) at least one organosilane;

[0272] iv. Make the surface of the first substrate A or the surface of the carrier layer T contact the first surface of the film D;

[0273] v. Wherein in step iv. prior to the contact between substrate A and the first surface of film D or between carrier layer T and the first surface of film D, a primer composition from step iii. is applied as layer P;

[0274] vi. Provide a conductive substrate B or a conductive carrier layer T';

[0275] vii. Make the surface of substrate B or the surface of carrier layer T' contact the second surface of membrane D;

[0276] viii. Optionally, in step vii., the primer composition from step iii. is applied as layer P' before contact between the substrate B and the second surface of the film D or between the carrier layer T' and the second surface of the film D;

[0277] x. Activate membrane D by providing heat at 40°C or higher and by applying a pressing pressure greater than 1 bar.

[0278] For each step and feature of all embodiments of the method, all the above embodiments, including all preferred levels and embodiments, are directly applicable (steps i. to v. and x.) or similarly applicable (steps vi. to viii.).

[0279] The time order of steps i to iii is arbitrary.

[0280] The chronological order of steps iv and v is clear from the wording.

[0281] The activation in step x. is performed after the aforementioned steps.

[0282] If a carrier layer T and / or T' is present in the overall structure of the tape in the adhesive compound, and in each case the substrate is bonded to the opposite side of the film D, it is preferable to include an additional adhesive layer C or, if appropriate, a second adhesive layer C' between the carrier layer T or T' and the substrate.

[0283] Such a composite may, for example, have the structure SCTPDP-T'-C'-S', where S and S' refer to non-conductive substrates.

[0284] In all the above embodiments, the carrier layer T or T and T' is conductive.

[0285] These layers are further described in the text below. For simplicity, the term "conductive carrier layer" or simply "carrier layer" will be used. Depending on which of the above embodiments this refers to, it refers to carrier layer T or carrier layers T and T'.

[0286] The carrier layers T and T' are independent of each other and may be the same or different from each other. Preferably, the conductive carrier layer comprises at least one metal. In a preferred embodiment of the invention, the metal is selected from copper, nickel, zinc, tin, silver, gold, aluminum, iron, chromium, and alloys of said metals. Very preferably, the metal is selected from aluminum, tin, chromium-nickel, and nickel-iron. Tin is highly preferred.

[0287] Preferably, the conductive carrier layer has a layer thickness of 10 nm to 50 μm measured in the z-direction (i.e., parallel to the stacking direction of the layer arrangement).

[0288] In a preferred embodiment of the invention, the conductive carrier layer comprises a) at least one metal foil, such as aluminum foil or nickel-iron foil, and / or b) at least one conductive fabric comprising at least one metal, preferably selected from copper and nickel, and / or c) one or more layers of at least one applied metal, preferably selected from copper, tin and aluminum, and / or d) at least one metal mesh and / or e) a metallized foil and thus a foil coated with metal, wherein the metal is preferably selected from aluminum, zinc, chromium-nickel and nickel-iron.

[0289] In principle, it is also possible to consider a combination of two or more of the above options here.

[0290] Metal foil, such as, and preferably, aluminum foil or nickel-iron foil, is known to those skilled in the art. The metal foil preferably has a layer thickness of 5 to 50 μm, more preferably 10 to 30 μm, measured in the z-direction (i.e., the stacking direction parallel to the layer arrangement).

[0291] Conductive fabrics are known to those skilled in the art, particularly by way of the term "conductive mesh." This is a textile fabric coated with metals, such as copper and / or nickel, for example, a fabric made of PET (polyethylene terephthalate), which is how the fabric becomes conductive.

[0292] Those skilled in the art will also know that metals can be applied directly (e.g., vapor deposition) to a surface (e.g., the surface of the adhesive layer in this case) as a single layer or multiple layers. In the context of this invention, the conductive carrier layer can be provided by vapor deposition of metal onto film D or adhesive layer C or adhesive layer C'.

[0293] When a metal is applied as a carrier layer, in advantageous embodiments it is preferred that the carrier layer protrudes laterally beyond only one adjacent adhesive layer in at least one extending direction of the layer plane, with the corresponding other adhesive layer serving as mechanical support for the metal layer. In this case, the metal layer does not have a practical carrier function. Instead, the other adhesive layer serves as the carrier for the metal layer. For simplicity, the term carrier layer is also retained for the metal layer in these embodiments. Preferably, the thickness of layer T in this case is greater than or equal to 10 nm, more preferably 50 to 200 nm.

[0294] However, it is also conceivable and preferred that no layer protrudes beyond any other layer. This allows the composite of layers to be easily processed together, particularly by stamping or otherwise transformed into the desired shape. It is also conceivable and preferred here that two conductive substrates A and B are bonded together and a voltage is applied to these substrates.

[0295] Furthermore, those skilled in the art are familiar with metal meshes of different sizes. Metal meshes with appropriate layer thickness can be manufactured, for example, by laying a loosely sparse cloth of appropriately fine metal wires or by die-cutting a foil with at least one appropriate layer thickness.

[0296] In the case of metal-coated films, particularly non-conductive films coated with metal are made conductive. The metal is preferably selected from copper, nickel, zinc, tin, silver, gold, aluminum, iron, chromium, and alloys of these metals, with aluminum, tin, chromium-nickel, and nickel-iron being particularly preferred. In principle, the film material can be selected from all materials capable of being vapor-deposited with metal and used as a carrier film in tapes; polymers are particularly suitable. The material is particularly selected from polyesters and polyolefins, and mixtures of more than one material are also conceivable. Particularly preferred polyesters are polyethylene terephthalate (PET) and polyethylene naphthalate (PEN). Particularly preferred polyolefins are polypropylene (PP) and polyethylene (PE). In a preferred embodiment, the film material is selected from PET, PEN, PE, and PP. Preferably, it is a PET (polyethylene terephthalate) film. This film is dimensionally stable and therefore easy to process without significant stretching or tearing. This allows for the durable application of a uniform and gapless metal layer, resulting in durable conductivity throughout the film, particularly in the z-direction. Metal coatings can be applied in any manner known to a technician.

[0297] In embodiments where at least one conductive carrier layer T or at least two conductive carrier layers T and T' are present, in an advantageous embodiment, it is preferred that the at least one adjacent adhesive layer protrudes laterally in at least one extending direction of the layer plane, and thus includes a lateral overhang. Voltage can then be applied to this lateral overhang in a simple manner.

[0298] In a further advantageous embodiment, it is also conceivable and preferred that no carrier layer protrudes beyond any other layer, particularly adjacent adhesive layers. This allows the composite of layers to be easily processed together, particularly by stamping or otherwise transformed into the desired shape. Therefore, such a structure has the advantages of simple manufacturability, and, in addition, the possibility of adjusting the tape stability via the carrier layer (one or more). It is also conceivable and preferred here that two conductive substrates A and B are bonded together and a voltage is applied to these substrates. In this case, the conductive carrier layer is a layer that is continuously conductive in the z-direction, particularly and preferably a metal foil according to option a) above.

[0299] In the context of this invention, the expression "laterally overhanging" is understood to mean any kind of lateral protrusion of one or more layers involved, and to mean that the respective involved layers extend beyond the reference layer, more particularly in the "xy" plane and therefore laterally—perpendicularly to the stacking direction—beyond the reference layer. In the context of this invention, the terms "lateral extension" or "laterally extending portion" are also used instead of the term "lateral protrusion."

[0300] The term "lateral" here refers to each extending direction of the layer plane "xy" perpendicular to the stacking direction "z" of the layers. Therefore, this term is specifically unrelated to the geometry of the tape in the "xy" plane, which can be, for example, rectangular, which is conventional for tape (see above), but can also be square or circular. This term does not concern the minute variations in the dimensions of the individual layers in the "xy" plane caused by die-cutting methods or similar forming methods, particularly since the dimensions of such minute material protrusions preclude the planned application of voltage to them.

[0301] Adhesive layer C or C and C' can, in principle, be based on the same compound as adhesive layer D; the adhesive of layer C or C and C' need not contain any electrolyte, but may contain it. Preferably, layer C or C and C' does not contain any electrolyte.

[0302] Regardless, the adhesive of layers C or C and C' can be designed to be conductive, so that a voltage can also be applied to them depending on the rest of the structure. Preferably, the conductive adhesive layer for this purpose includes at least one metal, such as, in particular, nickel, copper, or silver, preferably in the form of conductive metal particles and / or metallized particles, more preferably metal particles. The metal particles can be in any suitable form, including dendritic metal particles.

[0303] The metallized particles are, particularly and preferably, glass or polymer particles metallized with at least one metal, resulting in previously non-conductive particles becoming conductive through metallization. More preferably, the conductive adhesive layer comprises conductive particles selected from nickel particles, copper particles, and silver-coated copper particles. In a particularly preferred embodiment, the conductive adhesive layer comprises nickel particles.

[0304] Preferably, based on 100 parts by weight of the polymer, the conductive adhesive layer contains 5 to 40 parts by weight, more preferably 20 to 40 parts by weight, and most preferably 25 to 35 parts by weight of conductive particles, and more particularly metal particles and / or metallized particles.

[0305] In the context of this invention, a layer is considered “conductive” in particular when the resistance measured in the corresponding direction, in this case more particularly in the z-direction, according to standard MIL-DTL-83528C:2001-01 is less than 1 ohm.

[0306] In the context of this invention, all conductive layers are conductive at least in the z-direction. In particular, the layers to which a voltage is applied are additionally conductive in the x and y planes perpendicular to the z-direction.

[0307] In the case of one (C) or two (C and C') conductive adhesive layers, the corresponding carrier layers T or T and / or T' do not need to be conductive, depending on the geometry and where adhesive splitting is expected. Therefore, conductivity is only permitted between layers to which a voltage is applied.

[0308] Regardless of whether adhesive layer C or C and / or C' is designed to be conductive, the following statements apply. The additional adhesive layer C or C and / or C' may be a layer based on a thermally activated reactive adhesive, which may be the same as or different from the adhesive described above in film D. The adhesive of the additional adhesive layer C or C and / or C' may also be an adhesive that can be activated by another type of activation, such as a structural adhesive activated by UV light energy. Furthermore, the adhesive of the additional layer C may be a pressure-sensitive adhesive.

[0309] The adhesive layer D and—depending on the implementation—an additional adhesive are manufactured and converted into a layer form by known methods, particularly by spreading. Additionally, one or more drying steps may optionally be performed.

[0310] All the described layers are laminated one on top of the other in a manner known to those skilled in the art.

[0311] Advantageously, the outer exposed surface of the adhesive layer of the tape of the present invention may be provided with an anti-adhesive material, such as release paper or release film, also known as a pad or protective pad. The pad may also be a material having an anti-adhesive coating on at least one side, preferably on both sides, such as a double-sided silicone material. The pad, or more generally, a temporary carrier, is not part of the tape, but merely an aid used in its manufacture and / or storage and / or for further processing by die-cutting. Furthermore, unlike a permanent carrier, the pad is not firmly bonded to the adhesive layer, but rather serves as a temporary carrier, i.e., a carrier that can be peeled off from the adhesive layer. "Permanent carrier" is also referred to as "carrier" in this application.

[0312] The thickness (in the z direction) of each adhesive layer including film D is preferably 10 to 300 μm, more preferably 15 to 150 μm, even more preferably 20 to 100 μm, and even more preferably 25 to 70 μm.

[0313] The present invention also provides a method for electro-debonding the composite according to the invention, comprising at least the following method steps:

[0314] i.) Apply a voltage, preferably 1 to 50V, to two different conductive points of the component.

[0315] In step i.) of the method according to the invention, a voltage is applied for the electrodebonding of the composite.

[0316] Based on the structure of the adhesive compound, a voltage is applied to the corresponding conductive layer.

[0317] When the described composite APD-P'-B or APDB comprises conductive substrates A and B, a voltage is applied to both substrates A and B. When the described composite APD-T'-D'-P'-B comprises conductive substrates A and B, a voltage is applied to both substrates A and B.

[0318] When the described composite APD-P'-T' (or TPD-P'-B) comprises a conductive substrate A (or B) and a conductive carrier layer T' (or T), the voltage is preferably applied to A and T' or B and T.

[0319] In the case where the described composite TPDP-T' comprises two conductive carrier layers T and T', and in particular two non-conductive substrates S and S' are bonded to the two conductive carrier layers T and T' to form, for example, SCTPDP-T'-C'-S', a voltage is applied to the two carrier layers T and T'.

[0320] In summary, the method for electrodebonding the composite according to the above embodiments includes at least the following method steps:

[0321] i.) Applying a voltage at two different conductive points of the component, preferably 1 to 50 V, more preferably 2 to 50 V.

[0322] in

[0323] Apply voltage to conductive substrate A and conductive substrate B, or

[0324] Applied to conductive substrate A and conductive carrier layer T', or

[0325] Applied to the conductive carrier layer T and the conductive substrate B, or

[0326] It is applied to conductive carrier layer T and conductive carrier layer T'.

[0327] The voltage is, in particular, a DC voltage. The voltage is especially preferred to be 2 to 50 V.

[0328] In an advantageous implementation, the voltage is 2 to 12 V, for example 9 V.

[0329] This voltage can be applied, in particular, by a battery in the immediate vicinity of the adhesive (e.g., especially in mobile phones, tablets, etc.), or by adding a battery from the outside.

[0330] According to a further preferred embodiment of the invention, the voltage is 12 to 50 V, for example 30 V. This relatively high voltage allows for particularly rapid re-disengagement; the voltage required for this only needs to be applied for a few seconds.

[0331] In particular, depending on the selected voltage, the duration of voltage application in step i.) can range from a few seconds, more specifically 2 seconds, up to 900 seconds, preferably up to 600 seconds. Of course, it is also conceivable that the voltage application period may be longer than 900 seconds, especially if the voltage is relatively low.

[0332] The method for electro-debonding the composite according to the invention allows, for example, substrates A and B to be debonded from each other in a rapid and easy manner without requiring excessive force. Furthermore, no residue of adhesive film D remains on at least one substrate.

[0333] In some cases, especially after long-duration separation methods, a thin residual film of the electrolyte used, particularly the ionic liquid, may remain on the detached substrate. However, it can be removed in a simple manner, such as by rinsing with a suitable solvent.

[0334] In all embodiments, the conductive substrate can be, for example, a mobile phone casing made of metal (e.g., aluminum or passivated aluminum) or steel. Furthermore, it can be, for example, a conductive coating on a substrate that is originally non-conductive or has been otherwise made conductive; this coating can be organic or inorganic.

[0335] In all embodiments, the non-conductive substrate may be, in particular, a housing made of a non-conductive material (e.g., plastic), or a battery or other non-conductive component, such as a speaker.

[0336] As explained, the present invention is particularly suitable for bonding heat-sensitive substrates, such as anodized aluminum, polymers, displays and / or glass.

[0337] The present invention also provides the use of the adhesive tape according to the invention for bonding components in electronic devices, automobiles, medical devices, and dental devices, as well as in the DIY field and in the home. Possible uses include DIY (“Do-It-Yourself”) applications.

[0338] The present invention also provides the use of the adhesive tape according to the invention for bonding components in electronic devices, automobiles, medical devices and dental devices.

[0339] Preferred embodiments of the invention are illustrated and described in more detail below with reference to the accompanying drawings. These drawings show:

[0340] Figure 1 A simplified schematic cross-sectional view of the adhesive compound according to the invention in a preferred embodiment; and

[0341] Figure 2 A simplified schematic cross-sectional view of the adhesive compound according to the invention in a preferred embodiment; and

[0342] Figure 3 A simplified schematic cross-sectional view of the adhesive compound according to the invention being subjected to voltage in a preferred embodiment; and

[0343] Figure 4 A simplified schematic cross-sectional view of the adhesive compound according to the invention after voltage has been applied and adhesive splitting has therefore occurred; and

[0344] Figure 5 A simplified schematic cross-sectional view of the adhesive compound according to the invention in a preferred embodiment.

[0345] Figure 1 A schematic diagram showing an adhesive compound according to the invention in a preferred embodiment. (See from...) Figure 1 Clearly, film D1 is bonded to a first surface of a first substrate A3 having a certain area, wherein primer layer P2 is applied between film D1 and substrate A3.

[0346] Figure 2 A schematic diagram showing an adhesive compound according to the invention in a preferred embodiment. (See from...) Figure 2 Clearly, film D1 is bonded to a first surface of a first substrate A3 having a certain area, wherein a primer layer P2 is applied between film D1 and substrate A3. Furthermore, film D1 is bonded to a second surface of a second substrate B4 having a certain area, wherein an additional primer layer P4 is applied between film D1 and substrate B5.

[0347] Substrates A3 and B5 are conductive, and therefore a voltage can be applied to these two substrates, such as... Figure 3 This is shown schematically.

[0348] The application of voltage significantly reduced the adhesion between adhesive layer D1 and substrate A3, and caused these layers to detach from each other, as shown in the image. Figure 4 It is clear in the diagram.

[0349] Figure 5 A schematic diagram showing an adhesive compound according to the invention in a preferred embodiment. (See from...) Figure 5Clearly, film D1 is bonded to a first surface of a first substrate A3 with a certain area, wherein a primer layer P2 is applied between film D1 and substrate A3. Additionally, film D1 is bonded to a second surface of a conductive carrier layer T'6 with a certain area. A second conductive substrate B'5 is bonded to the carrier layer T'6 via a second thermally activated film D'7. A second primer layer P'4 exists between the second film D' and the second substrate B5. The carrier layer T' is, in particular, a nickel-iron foil. Films D'1 and D'7 have, in particular, the same composition. A voltage can be applied to both substrates A3 and B5.

[0350] Alternatively, voltage may be applied to one of the substrates A or B and the carrier layer T'6, especially if it protrudes slightly laterally from the composite. Figure 5 (Not shown in the image).

[0351] Several embodiments are described below to further illustrate the invention.

[0352] Example

[0353] Test methods

[0354] Unless otherwise specified, all measurements were performed at 23°C and 50% relative humidity. Mechanical and adhesion data were determined as follows:

[0355] thickness

[0356] The thickness of the adhesive layer or film can be determined by measuring the thickness of the portion of the adhesive layer applied to the pad, defined by its length and width, and subtracting the thickness (known or separately measurable) of the same size portion of the pad used. For non-pressure-sensitive adhesive films, the pad can be omitted, and therefore direct measurement is possible. The thickness of the adhesive layer can be determined with an accuracy of less than 1 μm variance using a commercially available thickness gauge (sensor testing device). If a thickness variation is detected, the average of the measurements at no fewer than three representative sites should be reported; in other words, measurements should be avoided, particularly at creases, wrinkles, points, etc.

[0357] As described above regarding the thickness of the adhesive layer, the thickness of the tape (strip) or carrier can be similarly determined using a commercially available thickness gauge (sensor testing device) with an accuracy of less than 1 μm variance. If a thickness variation is detected, report the average of the measurements at no fewer than three representative locations; in other words, especially where no measurements were taken at creases, wrinkles, points, etc.

[0358] Adhesive strength – push-out

[0359] The rollout test enabled conclusions to be drawn regarding the adhesive strength of double-sided adhesive products in the adhesive compound along the normal direction of the adhesive layer.

[0360] For this purpose, a square substrate S1 with an external dimension of 33mm × 33mm is provided.

[0361] On one of the surfaces, a corresponding primer solution (or no primer, V1 and V2) is applied along an edge with a width of 5 mm to create a 5 mm wide frame with primer along the outer edge of the square substrate.

[0362] In addition, square die-cut specimens of thermally activated reactive adhesive films in the form of a frame are provided—prepared by punching from a flat adhesive film using a die-cutting machine: external dimensions 30 mm × 30 mm; frame width 3.0 mm; internal dimensions (window cutout) 27 mm × 27 mm. The total surface area of ​​the adhesive film frame to be inspected is 170 mm². 2 .

[0363] Additionally, square or frame-shaped substrate S2 is provided: external dimensions 40 mm × 40 mm; internal dimensions (window cutout) 20 mm × 20 mm.

[0364] On one of the surfaces, a corresponding primer solution (or no primer, V1 and V2) is applied along the inner edge of the 5 mm wide frame, thereby creating a 5 mm wide frame with primer along the inner edge of the square frame-shaped substrate.

[0365] Substrates S1 and S2 are made of SUS steel and are cleaned with methyl ethyl ketone (MEK) before applying the primer.

[0366] In each case, the primer is applied by printing using a Nordson printing press.

[0367] The solvent is then allowed to evaporate for at least two minutes and at most 20 minutes. The thickness of the dried base coat is 1.5 μm.

[0368] Place one of the substrates, such as S1, on a hot plate preheated to 60°C and preheat for at least 30 seconds.

[0369] The film, provided by a heat-activated reactive adhesive, is placed onto a preheated and primed substrate using tweezers, if necessary, after the protective liner has been removed. It is then pressed with a rubber roller and allowed to cool briefly.

[0370] Place the second substrate, such as S2, on a heating plate preheated to 60°C for at least 30 seconds. If necessary, remove any protective liner from the surface of membrane D away from the first substrate in the z-direction. Then place the second substrate on the free surface of membrane D and press it down. Allow the pre-laminated composite to cool.

[0371] The membrane is arranged between substrates S1 and S2 in such a way that the internal cutouts of the frame-shaped membrane and substrate S2 are centered on the other. As a result, the primer applied to the two substrates is suspended in opposite directions relative to the membrane, so that the primer-treated, membrane-free surfaces in the adhesive compound do not come into contact with each other.

[0372] In Examples E1, V2, V3, and V4, pressing was performed for 600 s in a laboratory hot press at a platen temperature of 65°C and 5 bar, thereby producing the corresponding thermally activated composites. In Example V1, pressing was performed for 300 s in a laboratory hot press at a platen temperature of 90°C and 5 bar, thereby producing the corresponding thermally activated composites. The obtained samples were stored at RT and 50% RH (standard climatic conditions) for 24 hours.

[0373] The frame format (substrate S2) protrudes beyond the format of the substrate S1, and therefore the composite can be placed on the layout stage through the protruding area of ​​the frame (substrate S2).

[0374] A punch clamped in a tensile testing machine applies vertical pressure to substrate S1 through an opening in substrate S2, thus exerting force on the adhesive bonded in the composite. The punch's testing speed is 10 mm / s. The recorded value is the maximum force required for substrate S1 to detach from the frame (substrate S2). The force is based on the punch area, and therefore the result is expressed in N / mm². 2 The pushing resistance is expressed in MPa. The test conditions are 23°C and 50% relative humidity.

[0375] Impact Resistance - Drop Tower

[0376] The sample preparation is the same as that of the push-out test and has the same geometry.

[0377] The obtained samples were stored at RT and 50%RH (standard climatic conditions) for 24 hours.

[0378] After storage, the sample was immediately placed in the sample holder of the instrumented drop device, ensuring the composite was horizontal and the steel window facing downwards. Measurements were automatically performed using the instrument with a 5 kg load and a drop height of 115 mm. The kinetic energy introduced by the load broke the adhesive bond through the breakage of the tape between the window and the frame, with the force recorded every μs by a piezoelectric sensor. Following the measurement, the relevant software reported a force-time curve. The force region below the curve was identified, from which the total energy was derived.

[0379] Five samples are tested for each sample, and the final result is the total energy, which is the average of the five samples.

[0380] The following examples (denoted by E) and comparative examples (denoted by V) describe the manufacture of the adhesive compound according to the invention:

[0381] Table 1: Chemicals Used

[0382]

[0383] Membrane D is used in Examples V1, V2, V3, V4 and E1, and is provided as follows:

[0384] Irostic® S 9827-12 (polyurethane) was dissolved in MEK at 87.0% by weight of the subsequent total amount of solvent-free adhesive. Then, 10.0% by weight of Dancure® 999 was added and thoroughly mixed with the dissolved polyurethane. Next, 3.0% by weight of the ionic liquid bis(trifluoromethanesulfonyl)imide 1-ethyl-3-methylimidazolium (EMIM-FSI) was added and mixed vigorously.

[0385] The heat-activated reactive adhesive was then applied from the solution onto the cellophane release paper (protective backing) and dried at 50°C for 20 minutes. After drying, the layer thickness was 100 μm.

[0386] The composition of the primer may be changed, and in some cases, the activation temperature may be altered. Embodiments of the invention are indicated by "E", and comparative examples by "V".

[0387] E1: The primer is a mixture of 4 g thermoplastic polyurethane (Laricol 1460, from Coim), 1 g (3-triethoxysilylpropyl) succinic anhydride (CAS No. 93642-68-3, GENIOSIL®GF 20, from Wacker) and 95 g of anhydrous ethyl acetate and 20% methyl ethyl ketone (MEK).

[0388] V1: No primer used;

[0389] V2: No primer used;

[0390] V3: The primer is made of 4 g polyacrylate (produced by polymerization of a monomer composition containing 70% by weight butyl acrylate and 30% by weight vinylcaprolactam, based on the total weight of the monomers present in the monomer composition in each case), 4 g titanium tetraisopropoxide (TYZOR® TPT, Lehmann & Voss, CAS 546-68-9) and 92 g isopropanol;

[0391] V4: The primer used is the commercially available product Sika® Primer-207 (from Sika).

[0392] Adhesive films and various primer solutions are used to prepare samples for examining corresponding properties. The preparation of thermally activatable reactive adhesives for film D, including activation, is detailed in the method description for the push-out test.

[0393] Adhesive strength and impact resistance were determined using the methods described above. The results are summarized in Table 2.

[0394] Subsequently, the samples of the above embodiments were manufactured again, and the electrical re-detachability was tested by ejection tests.

[0395] After bonding and activation, for this purpose, voltage is applied to two steel plates, which are represented by conductive substrates A and B.

[0396] The applied voltage and the results obtained are also listed in Table 2.

[0397] Table 2

[0398]

[0399] As is evident from the low adhesive strength of E1 after voltage application in Table 2, the composite manufactured according to the invention using a composition of (a) thermoplastic polyurethane and (b) organosilane and—in this case, for application—solvent as a primer is surprisingly electrodegradable. This is surprising because in the adhesive composite APDPB, there is no electrolyte in the primer layer P, and in particular no ionic liquid is added.

[0400] Therefore, in Examples V3 and V4, where different primers were compared, the adhesive strength after voltage application was significantly higher. Meanwhile, at the same activation temperature (65°C) of the reactive adhesive film D, a higher adhesive strength before voltage application was achieved in E1 compared to V2. The adhesive strength of E1 was similar to that of V1, which did not use a primer but used a significantly higher activation temperature (90°C). Therefore, it is surprising that the activation temperature can also be lowered, allowing for bonding of heat-sensitive substrates such as anodized aluminum, polymers, displays, and / or glass.

[0401] A comparison of V1 with other comparative examples V2 to V4 and E1 also shows that the composite manufactured according to the present invention exhibits higher impact resistance in the drop tower test.

[0402] • In terms of the order of magnitude of measurement, the comparative example is at a significantly lower level. This difference is not merely within the measurement tolerance range.

[0403] List of reference numerals

[0404] 1 membrane D

[0405] 2 Primer layer P

[0406] 3. Conductive substrate A

[0407] 4 Primer layer P'

[0408] 5. Conductive substrate B

[0409] 6 Conductive carrier layer T'

[0410] 7 Second membrane D'

Claims

1. A tape system, comprising: (i) a film D of a thermally activated reactive adhesive, wherein the thermally activated reactive adhesive comprises at least one electrolyte; and (ii) A primer composition intended to form a single layer and comprising at least the following components: (a) at least one thermoplastic polyurethane; and (b) At least one organosilane.

2. The tape system according to claim 1, characterized in that... The organosilane (b) is selected from trialkoxysilyl alkyl succinic anhydride, trialkoxyphenyl silane, (3-mercaptopropyl)trialkoxysilane, (3-aminopropyl)alkoxysilane, 3-(2-aminoethylamino)propyltrialkoxysilane, vinyltrialkoxysilane, and (3-glycidoxypropyl)trialkoxysilane.

3. The tape system according to claim 2, characterized in that... The alkyl portion of the trialkoxysilyl alkyl succinic anhydride is a straight-chain alkylene group having 1-10 carbon atoms, preferably 3-8 carbon atoms, more preferably propylene, and / or the alkoxy group of the trialkoxysilyl alkyl succinic anhydride is selected from methoxy and ethoxy groups.

4. The tape system according to any one of claims 1 to 3, characterized in that... The organosilane (b) of the primer composition is (3-triethoxysilylpropyl)succinic anhydride.

5. The tape system according to any one of the preceding claims, characterized in that... The thermoplastic polyurethane (a) of the primer composition does not have free isocyanate groups.

6. The tape system according to any one of the preceding claims, characterized in that... The heat-activated reactive adhesive comprises at least one thermoplastic elastomer, wherein the thermoplastic elastomer preferably includes functional groups capable of reacting with isocyanates, and the heat-activated reactive adhesive comprises an isocyanate-containing compound as a crosslinking agent.

7. The tape system according to claim 6, characterized in that... The thermoplastic elastomer is at least thermoplastic polyurethane.

8. The tape system according to any one of the preceding claims, characterized in that... The thermally activated reactive adhesive is based on an organic solvent.

9. The tape system according to any one of the preceding claims, characterized in that... The electrolyte is selected from ionic liquids and metal salts, with ionic liquids being more preferred.

10. The tape system according to claim 9, characterized in that... The anion of the ionic liquid is selected from Br₂. − AlCl4 − Al2Cl7 - NO3 - BF4 - PF6 - CH3COO - CF3COO - CF3CO3 - CF3SO3 - (CF3SO2)2N - (CF3SO2)3C - AsF6 - SbF6 - CF3(CF2)3SO3 - (CF3CF2SO2)2N - CF3CF2CF2COO - N(CN)2 - and (FSO2)2N - , And more preferably selected from (CF3SO2)2N - and (FSO2)2N - , And / or the cation of the ionic liquid is selected from imidazolium-based cations, pyridinium-based cations, pyrrolidine-based cations, and ammonium-based cations, more preferably from imidazolium-based cations.

11. A method for manufacturing an adhesive compound using the tape system according to any one of claims 1 to 10, characterized in that, It includes at least the following method steps: i. Provide a conductive substrate A or a conductive carrier layer T; ii. A membrane D providing a thermally activatable reactive adhesive, wherein the thermally activatable reactive adhesive comprises at least one electrolyte; iii. A primer composition is provided, wherein the primer composition contains at least the following components: (a) at least one thermoplastic polyurethane; and (b) at least one organosilane; iv. Make the surface of the first substrate A or the surface of the carrier layer T contact the first surface of the film D; v. Wherein in step iv. prior to the contact between substrate A and the first surface of film D or between carrier layer T and the first surface of film D, a primer composition from step iii. is applied as layer P; x. Activate membrane D by providing heat at 40°C or higher and by applying a pressing pressure greater than 1 bar.

12. The method according to claim 11, characterized in that, It also includes at least the following method steps: i. Provide a conductive substrate A or a conductive carrier layer T; ii. A membrane D providing a thermally activatable reactive adhesive, wherein the thermally activatable reactive adhesive comprises at least one electrolyte; iii. A primer composition is provided, wherein the primer composition contains at least the following components: (a) at least one thermoplastic polyurethane; and (b) at least one organosilane; iv. Make the surface of the first substrate A or the surface of the carrier layer T contact the first surface of the film D; v. Wherein in step iv. prior to the contact between substrate A and the first surface of film D or between carrier layer T and the first surface of film D, a primer composition from step iii. is applied as layer P; vi. Provide a conductive substrate B or a conductive carrier layer T'; vii. Make the surface of substrate B or the surface of carrier layer T' contact the second surface of membrane D; viii. Optionally, in step vii., before contact between the substrate B and the second surface of the film D or between the carrier layer T' and the second surface of the film D, the primer composition from step iii. is applied as layer P'; x. Activate membrane D by providing heat at 40°C or higher and by applying a pressing pressure greater than 1 bar.

13. An adhesive compound manufactured by the method according to claim 12.

14. A method for electrically debonding the composite according to claim 13, comprising at least the following method steps: i.) Applying a voltage to two different conductive sites on the composite, wherein the voltage is preferably 1 to 50 V, more preferably 2 to 50 V, wherein the voltage is applied to conductive substrate A and conductive substrate B or to conductive substrate A and conductive carrier layer T' or to conductive carrier layer T and conductive substrate B or to conductive carrier layer T and conductive carrier layer T'.

15. Use of the tape system according to any one of claims 1 to 10 or the adhesive compound according to claim 13 in electronic devices, automobiles, medical devices and dental devices, as well as in the DIY field and in the home.

Images