Removable laminate, process for removing permanent bonds and use

Abstract

Laminate 2, designed and prepared to be separated after permanent bonding, comprising the following layers: a) a first adhesive layer 21, b) a separation layer 23, c) a second adhesive layer 24, characterized by the fact that the separation layer 23 - contains a laser-sensitive pigment that also provides color, - consists of a hardened lacquer that can be at least partially removed by laser irradiation 22, wherein the first adhesive layer 21 and / or the second adhesive layer 24 are laser beam translucent, characterized by the fact that The separating layer 23 consists of a single layer of lacquer.

Description

[0001] The present invention relates to a laminate designed and configured to be separated after permanent bonding, comprising a first adhesive layer, a release layer, and a second adhesive layer. The present invention further comprises a method for separating a permanent bond formed by means of such a laminate.

[0002] In repair shops and in end-of-life recycling of electronic devices, the desire to be able to repair electronic devices or even automobiles, or to dismantle and / or recycle them as much as possible, is gaining importance for ecological as well as economic reasons.

[0003] There are different types of electronic devices, which differ in their recyclability and also in the degree of recycling: • Large household appliances (also called white goods): for example washing machines, refrigerators and freezers, stoves; • Small household appliances (also classified as white goods): for example, vacuum cleaners, coffee machines, microwaves; • Information and communication technology equipment: for example, computers, monitors, printers, mobile phones, telephones; • Consumer electronics (also called brown goods): for example, televisions, video recorders, digital cameras;

[0004] Electrical and electronic devices contain a wide variety of substances and materials. If these devices are not disposed of properly, for example, with regular household waste, the pollutants they may still contain can pose environmental risks. Besides pollutants such as heavy metals and CFCs, these devices also contain a number of valuable materials that should be recovered and recycled. By disposing of these devices properly, primary raw materials (and thus their costly extraction) can be replaced, making a significant contribution to conserving natural resources.

[0005] To achieve these goals, the German Electrical and Electronic Equipment Act (ElektroG), implementing Directive 2012 / 19 / EU on Waste Electrical and Electronic Equipment (WEEE), establishes specific obligations for all relevant stakeholders (manufacturers, retailers, municipalities, owners, and waste management companies). By preventing waste, conducting reasonable assessments of the possibilities for preparing entire devices or individual components for reuse, and setting requirements for the further recovery of waste, a significant contribution is to be made to conserving natural resources and reducing pollutant emissions.

[0006] Appropriate recycling-friendly designs are necessary, enabling disassembly on demand. Reusable adhesive bonds are also considered recycling-friendly designs.

[0007] This is because, especially in small electronic devices, the tendency to permanently glue parts instead of mechanically connecting them is increasing very strongly.

[0008] Laminated films in the form of double-sided adhesive tapes are used, for example, to bond two components together. These components are typically intended to be permanently bonded using such a laminate. This is meant to result in a correspondingly durable and resilient bond and product. Examples of components bonded in this way include touch panels, as used in computer monitors or mobile electronic devices. If one of the two components is damaged, the bonded assembly cannot be separated at all, or only with considerable force, to replace the component. There is also a risk of damaging the undamaged component during separation.

[0009] DE 10 2020 209 557 A1 discloses a film laminate, designed and configured to be separated after permanent bonding, comprising the following layers: - a first layer of adhesive compound, - a separating layer, - a second adhesive layer, wherein the release layer has a thickness of 40 nm to 500 nm, the first adhesive layer is laser-beam translucent, and the release layer consists of a metal that can be at least partially removed by laser irradiation. Here, a metal is removed by means of a laser, which leads to the separation.

[0010] Translucency is the partial transmission of light through a material. The word is derived from the Latin word "lux," meaning light. Wax, human skin, leaves, and many other materials are translucent because they allow some light to pass through but are not transparent. In contrast to transparency, translucency can be described as light transmission. The reciprocal property of translucency is opacity. Therefore, a material with high translucency has low opacity, and vice versa.

[0011] In the context of the invention, light transmittance means permeability at the respective wavelength of light. This means, for example, that a black body (e.g., a black-colored polymer) is opaque in the visible spectrum, but translucent in the non-visible range, such as NIR, meaning that light can pass through it in this wavelength range.

[0012] EP 3 390 553 A1 relates to a method for bonding two surfaces using a reactive adhesive film system comprising at least two adhesive films (F1 and F2), wherein the adhesive films each comprise at least one reactive component (R1 and R2), wherein the bonding is effected by a reaction that requires the presence of both reactive components (R1 and R2), wherein a separating layer (T) impermeable to the reactive components (R1 and R2) is provided between the adhesive films (F1 and F2) to be brought into contact with each other prior to the bonding. To effect the bonding, the separating layer (T) is at least partially removed by means of a laser, so that the adhesive films (F1 and F2) come into direct contact with each other and the reaction begins in the presence of both reactive components (R1 and R2).

[0013] The separating layer can be a metal layer. This can be a metal foil that is inserted between the adhesive films during the manufacturing of the adhesive tape; for example, through a lamination process.

[0014] JP 2014 091 755 A describes an adhesive tape primarily designed to create a particularly strong bond between two components. This is achieved using an adhesive compound containing a laser-sensitive pigment. Laser irradiation does not remove the adhesive compound; instead, it softens or melts due to the heat absorbed by the laser pigment, allowing the adhesive to flow smoothly onto the components, thus improving adhesion.

[0015] WO 2004 / 006 296 A2 describes a laminated body comprising a substrate, namely a semiconductor wafer, a rock crystal wafer, sapphire, or glass; an adhesive as a bonding layer in contact with the substrate; a photothermal conversion layer comprising a light-absorbing agent and a heat-degradable resin, arranged beneath the bonding layer; and a translucent support arranged beneath the photothermal conversion layer. The light-absorbing agent converts absorbed radiant energy into thermal energy.

[0016] DE 81 30 861 U1 discloses laser-markable labels with an outer and a second underlying varnish layer, the varnish layer being made of polyurethane acrylate and hexanediol bisacrylate. Building on this, DE 100 48 665 A1 discloses laser-markable labels with an electron-beam-cured varnish layer. A method for producing such laser-markable labels is described in DE 101 42 638 A1, in which an engraving layer with a UV-curable varnish is incorporated. DE 10 2005 061 125 A1 provides labels that buffer against damage from high temperatures above 140 °C by means of an additional compensation layer.

[0017] The use of lasers for ablation is widespread; for example, in micromachining, some laser beam sources can be used for ablative processes. Extremely thin layers of substrates can be removed because the local heating leads to particulate debris or carbonization / evaporation. To achieve the gentlest possible ablation processes, lasers in the wavelength range of 800 to 2000 nm are predominantly used. Excimer lasers are frequently employed for photochemical reactions with low heat input. Excimer lasers are characterized by laser beams in the ultraviolet (UV) wavelength range.

[0018] In the Fig. Figure 1 clearly shows the emission wavelengths of the most important lasers.

[0019] The following table lists the typical properties of an Nd:YAG laser. Table 1: Typical properties of an Nd:YAG laser Wavelength: 1064 nm Pulse duration: a few horsepower to a few milliseconds Pulse energy: mJ up to approximately 100 J Photon energy 1.16 eV Applications: Micro welding, cutting and drilling of metals and plastics Note: Typical plastics and glass have high transparency → therefore poor processing.

[0020] Furthermore, ultrashort pulse (USP) lasers have proven particularly suitable. Ultrashort pulse lasers are laser beam sources that emit pulsed laser light with pulse durations in the picosecond and femtosecond range.

[0021] Ultrashort pulse lasers emit light pulses in which the light energy is compressed into extremely short durations, achieving light powers in the megawatt range during the pulse. With appropriate spatial focusing, intensities of many gigawatts per square centimeter can be achieved. At such high intensities, nonlinear effects occur in the interaction of light and matter. One of these effects is multiphoton absorption, which, at sufficiently high intensities, allows for the ablation of virtually any material. This is particularly true for femtosecond lasers. Neither their absorption, nor their hardness or evaporation temperature, plays a role, and even challenging materials such as composites can be processed without difficulty.

[0022] Another advantage of ultrashort pulse lasers is their high precision. Focus diameters in the micrometer range and the low energy input per pulse enable spatially high-resolution laser ablation. The shorter the pulse duration, the less the surrounding material is damaged by the laser beam, and the more precisely the material can be removed. The result is clean cut edges without burrs, eliminating the need for post-processing. In metalworking, nanosecond pulses are usually sufficient; picosecond pulses are required for more intricate work, and femtosecond pulses are used for non-metallic materials such as ceramics, polymers, and many composites. However, the reduced material removal rate with shorter pulse durations means that the overall processing time is longer.One goal of current development work on ultrashort pulse lasers is therefore to increase the pulse repetition rate (number of laser pulses per second). This increases the average power and thus the throughput in manufacturing. In the laboratory, femtosecond lasers with an average power of over 1 kilowatt have already been demonstrated. They have pulse repetition rates of 20 megahertz, pulse energies of 55 microjoules, and pulse durations of 600 femtoseconds. Commercially available femtosecond lasers today have average powers of a few hundred watts at most, and these typically operate with ytterbium-doped laser crystals.

[0023] The object of the present invention is therefore to provide a laminate that, on the one hand, enables a permanent and secure bonding of two components together, but on the other hand, allows a clean and safe separation of the components if necessary.

[0024] The problem is solved according to the invention by a film laminate as described in claim 1. Advantageous embodiments are described in the dependent claims. Furthermore, the invention includes a method for breaking a permanent bond formed by a laminate according to the invention, by removing at least part of the separating layer by laser irradiation and separating the laminate into a first partial laminate and a second partial laminate, as well as suggestions for the use of the laminate according to the invention.

[0025] Accordingly, the present invention relates to a laminate, designed and configured to be separated after permanent bonding, comprising the following layers: a) a first adhesive layer, b) a separating layer, c) a second adhesive layer

[0026] According to the invention, the separating layer is characterized by the following properties: - The separating layer has a thickness of preferably 0.5 to 100 µm, more preferably 1 to 30 µm, and most preferably 5 to 25 µm. - The separation layer contains a laser-sensitive pigment that also imparts color, preferably producing a black color. - The separating layer consists of a hardened lacquer, preferably an electron beam or UV-cured lacquer, which can be at least partially removed by laser irradiation.

[0027] The first adhesive layer and / or the second adhesive layer are laser beam translucent.

[0028] With such a laminate, two substrates, for example glass / glass, glass / metal, glass / plastic, or plastic / plastic, can be permanently bonded. By selectively removing the thin release layer, the bond strength between the two adhesive layers can be reduced to such an extent that the layers can be separated very easily; in the best-case scenario, the bond strength is almost completely eliminated. This allows for reworkability, meaning that a bond that was initially considered irreversible can still be undone. The release layer is removed by ablation.

[0029] The present invention further relates to a method for breaking a permanent bond effected by means of a laminate according to the invention, in which the separating layer is removed at least partially by means of laser irradiation and the laminate is separated into a first partial laminate and a second partial laminate.

[0030] Preferably, forces are applied to at least one of the sublaminates, increasing the distance between the two sublaminates. This allows for a particularly good and reliable separation of the laminate into two sublaminates.

[0031] A typical structure of a laminate according to the invention is therefore as follows: a) first layer of adhesive compound b) Separation layer c) second layer of adhesive compound.

[0032] It is important that either the first adhesive layer is translucent to the laser radiation used and / or the second adhesive layer is translucent, so that the laser can penetrate to the release layer. The same applies to the substrate to be bonded, at least on the side from which the laser radiation is applied. This substrate must also be transparent to the laser radiation. The release layer itself absorbs the laser radiation.

[0033] The separating layer consists of a hardened lacquer, preferably a radiation-cured lacquer, in particular an electron beam or UV-cured lacquer.

[0034] According to the invention, laser absorbers, i.e., laser-absorbing pigments, are added to the coating to achieve the most efficient energy absorption possible during laser treatment. These laser-sensitive pigments simultaneously color the release layer. Titanium dioxide and / or carbon black therefore serve as typical laser absorbers that also produce a coloring effect.

[0035] If a laser-sensitive pigment is present in the separation layer, for example through the addition of titanium dioxide and / or carbon black, other color-imparting pigments can also be added, making it possible to produce a paint layer of any desired color. The actual color-imparting pigment of the paint then no longer needs to fulfill any special absorption properties with regard to laser absorption.

[0036] Suitable release layers include radiation-curable systems such as unsaturated polyesters, epoxy, polyester and urethane acrylates, as are also used for UV printing inks, in particular those made from base polymers according to DE G 81 30 816, namely aliphatic urethane acrylate oligomers.

[0037] In principle, four types of lacquer are particularly suitable for use in the release layer according to the invention, for example, acid-curing alkyd melamine resins, addition-curing polyurethanes, radical-curing styrene lacquers, and similar materials. However, radiation-curing lacquers are particularly advantageous because they cure very quickly without lengthy solvent evaporation or the application of heat. Such lacquers have been described, for example, by A. Vrancken (Farbe und Lack 83,3 (1977) 171).

[0038] According to the invention, the separating layer consists of a single layer of lacquer, which is in particular cured by electron beam.

[0039] The preferred lacquer layer is applied to a liner and hardened by exposure to a high-energy electron beam (150 to 500 kV) under effectively oxygen-free conditions.

[0040] Particularly advantageously, the lacquer comprises a hardened acrylic lacquer composition. According to a particularly advantageous embodiment, the hardened acrylic lacquer composition is based on a composition comprising • 30 to 80 wt% of a trifunctional oligomer A, • 0 to 20 wt% of a trifunctional monomer B, • 1 to 30 wt% of a difunctional monomer C as well as • 2 to 40 wt% of a laser-sensitive pigment that also provides color.

[0041] In a preferred embodiment of the present invention, the composition on which the acrylate lacquer composition is based comprises 50 to 60 wt.%, preferably 52 to 58 wt.% of the trifunctional oligomer A, 5 to 15 wt.%, preferably 8 to 12 wt.% of the trifunctional monomer B, and 5 to 15 wt.%, preferably 8 to 12 wt.% of the difunctional monomer C.

[0042] The amount of laser-sensitive pigment within the acrylate lacquer compositions of preferred embodiments depends on the type of pigment used. Generally, the laser-sensitive pigments are added in amounts ranging from 1 wt.% to a maximum of 40 wt.%, preferably in amounts of 2 to 28 wt.% or in amounts of 5 to 15 wt.% based on the total weight of the lacquer layer.

[0043] In the case of carbon black as the coloring pigment (to achieve the preferred black color), for example, 2 to 7 wt.% are preferred, while in the case of TiO₂ for white coloring, 15 to 40 wt.%, and particularly preferably 22 to 28 wt.%, are used. Titanium dioxide in the rutile modification ("TiO₂", for example, rutile grades from Kronos) is preferably used.

[0044] The trifunctional oligomer A, the trifunctional monomer B, and the difunctional monomer C are hereinafter also referred to as component A, component B, and component C, respectively. Compositions containing components A, B, and C, as well as the coloring pigment in the specified amounts, result in particularly temperature-resistant, cured acrylic lacquer compositions.

[0045] The release layer can be provided by curing a composition comprising components A, B, and C, as well as the laser-sensitive pigment. For this purpose, the composition is crosslinked using IR radiation, UV radiation, or electron beam curing (hereinafter referred to as ESH). Crosslinking is preferably carried out using ESH.

[0046] The trifunctional oligomer A is an oligomer with three unsaturated (meth)acrylate units per molecule, whose number-averaged molecular weight M n (determined by gel permeation chromatography (GPC)) preferably between 1000 and 5000 g / mol, preferably between 1400 and 3600 g / mol, preferably between 1800 and 2200 g / mol, particularly preferably between 1900 and 2100 g / mol. If the molecular weight M is nIn the aforementioned area, this has a positive influence on the long-term temperature resistance of the hardened acrylate lacquer composition, so that particularly dimensionally stable contrast layers can be obtained.

[0047] In a preferred embodiment, the trifunctional oligomer A is selected from the group consisting of polyurethane tri(meth)acrylates and polyester tri(meth)acrylates, of which polyurethane tri(meth)acrylates are particularly preferred. The term (meth)acrylate includes acrylates, methacrylates, and mixtures thereof. Preferably, the trifunctional oligomer A is a polyurethane tri(meth)acrylate, and particularly preferably a polyurethane triacrylate. Polyurethane tri(meth)acrylates are oligomers with three unsaturated (meth)acrylate groups per molecule and several, i.e., at least two, urethane units. Examples of preferred polyurethane triacrylates are the aliphatic urethane triacrylates CN9260D75® and CN9278D80® from Sartomer, of which CN9260D75® is particularly preferred.

[0048] The trifunctional monomer B contains three unsaturated (meth)acrylate units per molecule and, in a preferred embodiment of the invention, has a molecular weight of 300 to 1000 g / mol, preferably 350 to 800 g / mol, more preferably 350 to 600 g / mol, and particularly preferably 400 to 450 g / mol. Component B is preferably selected from the group consisting of propoxylated and ethoxylated glycerol tri(meth)acrylates and propoxylated and ethoxylated trimethylolpropane tri(meth)acrylates of general formula (I) or mixtures thereof, wherein R in formula I represents hydrogen or a methyl group; A is hydrogen or an ethyl group; X, Y, and Z each independently represent a propylene or ethylene unit. and a, b and c are each independently an integer from 1 to 4, preferably 1 to 3, and a+b+c represents a number between 3 and 12, preferably 3 to 9.In a particularly preferred embodiment of the invention, X, Y, and Z are propylene units. A propoxylated glycerol triacrylate is particularly preferred as the trifunctional monomer. If the trifunctional monomer B is selected such that its molecular weight falls within the ranges mentioned above and / or that monomer B follows the formula I mentioned above, then component B also has a positive influence on the temperature resistance of the contrast layer and thus of the laser-markable film.

[0049] The difunctional monomer C is a monomer with two unsaturated acrylate units per molecule. Component C preferably has a molecular weight of 100 to 1000 g / mol, more preferably 180 to 350 g / mol, and more preferably 220 to 280 g / mol, and is preferably selected from the group consisting of ethylene glycol diacrylates of general formula (II) and propylene glycol diacrylates of general formula (III), or mixtures thereof, wherein n in formulas II and III is each independently an integer from 1 to 15, more preferably from 1 to 9, more preferably from 2 to 6, and most preferably 3 or 4. In a particularly preferred embodiment of the present invention, the difunctional monomer C is triethylene glycol diacrylate.If the difunctional monomer C is selected such that the molecular weight falls within the above-mentioned ranges and / or that the monomer C falls under the above-mentioned formula II or III, then component C also has a positive influence on the temperature resistance of the contrast layer and thus of the laser-markable film.

[0050] In a particularly preferred embodiment of the invention, the separating layer is based on a composition comprising at least one polyurethane triacrylate, preferably CN9260D75® or CN9278D80® from Sartomer as component A, a propoxylated glycerol triacrylate of the formula I shown above as component B, triethylene glycol diacrylate as component C and a pigment, for example titanium dioxide in the rutile modification.

[0051] Further suitable types of coatings are described in the book “CHEMISTRY & TECHNOLOGY OF UV & EB FORMULATIONS FOR COATINGS, INKS & PAINTS” (VOLUME II: “PREPOLYMERS & REACTIVE DILUENTS FOR UV & EB CURABLE FORMULATIONS” by NS Allan, MS Johnson, PKT Oldring, S Salim.

[0052] Especially in display bonding, a metallic, glossy appearance of adhesive tapes is undesirable. Therefore, adhesive tapes for fixing / mounting displays are typically deep black and have very high opacity. They also serve as a design element in the displays. For this reason, a black release liner is preferred.

[0053] The separating layer is therefore preferably black.

[0054] Black pigments are added for coloring.

[0055] Suitable black pigments include, for example, the commonly used carbon black, organic azo dyes, and / or chromium complexes. Examples of black pigments based on chromium complexes are [1-[(2-hydroxy-4-nitrophenyl)azo]-2-naphthalenolato(2-)][1-[(2-hydroxy-5-nitrophenyl)azo]-2-naphthalenolato(2-)]chromate(1-), bis[1-[(2-hydroxy-4-nitrophenyl)azo]-2-naphthalenolato (2-)]chromate(1-), and bis[1-[(2-hydroxy-5-nitrophenyl)azo]-2-naphthalenolato(2-)]chromate(1-).

[0056] Suitable carbon blacks are: • Pigment soot • Flame soot • Furnace black • Furnace black • Acetylene carbon black • Oxidized gas soot • Thermal soot

[0057] The Printex types from the company Evonik can be mentioned as an example.

[0058] In addition to the release layer, one of the adhesive layers can also be colored. If carbon black particles are added as black pigments, they are preferably used in an amount of up to 12% by weight, based on the colored (i.e., mixed with color pigments) adhesive. To achieve excellent coloration, it is advantageous to use carbon black in an amount of at least 1.2% by weight. It is highly preferred that, when carbon black is used as a black pigment, it is used in an amount such that the adhesive contains carbon black in a weight fraction of 2.1 to 3.1% by weight.

[0059] As already described, the separation layer can contain additives other than color pigments in addition to the color-giving and laser-sensitive pigments.

[0060] In particular, if the separating layer consists of several layers of lacquer, the individual layers can have different colors, with at least one layer containing laser-sensitive pigments.

[0061] Suitable additives, some of which also exhibit laser-sensitive properties, include, for example, color pigments and metal salts, especially copper hydroxide phosphate or iriodin, a pearlescent pigment commercially available from Merck. These additives are mixed with the base polymer (such as that described in DE G 81 30 861) in amounts ranging from 0.05 wt.% to a maximum of 10 wt.%, preferably in amounts of 0.1 to 10 wt.%, and particularly 0.5 to 5 wt.%, based on the total weight of the coating layer.

[0062] Coloring additives within the meaning of the present invention include, without limitation, all coloring additives that are used as dyes and / or brighteners in paints and varnishes, such as those mentioned, for example, in the textbook on paints and coatings, Vol. 5 (Hans Kittel and Jürgen Spille, Hirzel Verlag (Stuttgart), 2003).

[0063] Preferably, the coating layer is a single layer. In one embodiment, it is multi-layered, and the layers consist of hardened, i.e., cross-linked, coating. In a preferred embodiment, the coating layers are arranged directly on top of each other, meaning that no further intermediate layers are provided. This is particularly advantageous with regard to achieving the thinnest and most cost-effective design of the separating layer.

[0064] The removal layer is a layer that can be ablated using a single laser beam or multiple laser beams. In this process, the engraved layer is ablated at the points where a laser beam with sufficient energy is directed. With adequate energy input, the removal layer is locally and completely removed.

[0065] It is also conceivable that the separation layer is only partially ablated in some places.

[0066] The separating layer provided according to the invention is very preferably located over the entire surface and as a closed layer between the first adhesive layer and the second adhesive layer.

[0067] The separating layer provided according to the invention is advantageously applied in a thickness of 0.5 to 100 µm, in particular 1 to 30 µm, and more particularly 5 to 25 µm.

[0068] The separation layer is removed using a laser, specifically by ablation. The process involves shining the laser beam through the laminate from one side. The separation layer can be completely removed, or only in one or more areas or sections. This allows control over the size of the remaining contact area. In this way, a predetermined breaking point can be created, at which separation occurs under minimal further stress, while a bond is initially maintained (i.e., after laser irradiation). Similarly, complete removal of the separation layer allows for 100% separation of the laminate in less than one second. Substrates originally bonded as permanent components can thus be separated quickly, cleanly, and easily.

[0069] Standard lasers can generally be used. The laser wavelength is preferably selected such that the laser radiation can be emitted with maximum transmission through the adhesive and any other layers of the laminate. In the wavelength range of 800 to 2000 nm, for example, there is no or only very low absorption tendency for conventional acrylate pressure-sensitive adhesives. The adhesive systems used according to the invention are also translucent in this range.

[0070] Preferably, solid-state lasers are used whose wavelength is ideally suited for illuminating conventional adhesives and release materials. Nd:YAG solid-state lasers are particularly preferred. An Nd:YAG laser (short for neodymium-doped yttrium aluminum garnet laser) is a solid-state laser that uses a neodymium-doped YAG crystal as its active medium and typically emits infrared radiation with a wavelength of 1064 nm. Further transitions exist at 946 nm, 1320 nm, and 1444 nm. The wavelength of the emitted light from this laser is—as described above—in the range of 1064 µm. This wavelength is generally not absorbed by the adhesive layers used, so these materials are translucent at this wavelength. Furthermore, the substrate layers—for example, made of polyethylene terephthalate (PET)—can also be irradiated with this wavelength without damage.Conversion of the radiation to other wavelengths can be achieved, if required, by generating the second (532 nm) and third (355 nm) harmonics. In principle, however, all gas lasers, dye lasers, solid-state lasers, metal vapor lasers, and excimer lasers with suitable wavelengths are appropriate.

[0071] The laser parameter sets used for an application and the associated laser strategy depend on the adhesive systems used (absorbing and non-absorbing adhesives).

[0072] The following parameters are preferred: • Power: 0.1 to 12 watts • Speed: 100 to 12,000 mm / sec • Frequency: 1 to 200 kHz • Focus: 25 to 250 µm • Pulse time: 30 to 300 ns

[0073] In this document, as in common usage, an adhesive is understood to be a substance that is permanently sticky and adhesive, particularly at room temperature. A characteristic of an adhesive is that it can be applied to a substrate by applying pressure and adheres there, although the required pressure and its duration are not precisely defined. In some cases, depending on the specific type of adhesive, the temperature, humidity, and substrate, a brief, minimal pressure, not exceeding a light touch for a short moment, is sufficient to achieve adhesion; in other cases, a longer period of high pressure may be necessary.

[0074] Pressure-sensitive adhesives have special, characteristic viscoelastic properties that lead to permanent stickiness and adhesion.

[0075] A characteristic feature of these adhesives is that, when mechanically deformed, both viscous flow processes and the development of elastic restoring forces occur. The respective proportions of these two processes are in a specific ratio to each other, depending on the precise composition, structure, and degree of cross-linking of the adhesive in question, as well as the speed and duration of the deformation and the temperature.

[0076] The proportion of viscous flow is necessary to achieve adhesion. Only the viscous components, caused by macromolecules with relatively high mobility, enable good wetting and flow onto the substrate to be bonded. A high proportion of viscous flow leads to high tack (also known as surface tack) and thus often also to high adhesive strength. Highly cross-linked systems, crystalline or glassy polymers, are generally not tacky or at least only slightly tacky due to a lack of flowable components.

[0077] The elastic restoring forces are necessary for achieving cohesion. They are generated, for example, by very long-chain and highly entangled macromolecules, as well as by physically or chemically cross-linked macromolecules, and enable the transmission of forces acting on an adhesive bond. They ensure that an adhesive bond can withstand sustained stress, such as continuous shear stress, to a sufficient degree over an extended period. To describe and quantify the degree of elastic and viscous components, as well as their ratio, the storage modulus (G') and loss modulus (G''), which can be determined using Dynamic Mechanical Analysis (DMA), can be used. G' is a measure of the elastic component, and G'' is a measure of the viscous component of a material. Both quantities depend on the deformation frequency and the temperature.

[0078] The parameters can be determined using a rheometer. The material under investigation is subjected, for example, to a sinusoidally oscillating shear stress in a plate-plate arrangement. In shear-stress controlled devices, the deformation is measured as a function of time, along with the time lag of this deformation relative to the application of the shear stress. This time lag is called the phase angle δ.

[0079] The storage modulus G' is defined as follows: G' = (τ / γ) ·cos(δ) (τ = shear stress, γ = deformation, δ = phase angle = phase shift between the shear stress and deformation vectors). The definition of the loss modulus G'' is: G'' = (τ / γ) ·sin(δ) (τ = shear stress, γ = deformation, δ = phase angle = phase shift between the shear stress and deformation vectors).

[0080] A material is generally considered to be adhesive and is defined as such for the purposes of this document if, at room temperature (here defined as 23 °C), it exhibits the following properties within the deformation frequency range of 10 0 up to 10 1 rad / sec, G' at least partly in the range of 10 3 up to 10 7 Pa lies within this range, and G'' also lies at least partially within this range. Partially means that at least a section of the G' curve lies within the window defined by the deformation frequency range including 10 0 up to and including 10 1 rad / sec (abscissa) and the range of G' values ​​including 10 3 up to and including 10 7 Pa (ordinate) is spanned, and if at least one section of the G'' curve lies within this window.

[0081] The two adhesive layers preferably contain at least one polymer selected from the group consisting of poly(meth)acrylates, natural rubber, synthetic rubbers, in particular vinyl aromatic block copolymers, silicones, polyurethanes, and mixtures of two or more of the aforementioned polymers. The outer adhesive layer particularly preferably contains at least one poly(meth)acrylate. Furthermore, it is preferred that at least one of the two adhesive layers contains at least 40 wt.% of one or more poly(meth)acrylates. In particular, the outer adhesive layer contains no other polymers besides one or more poly(meth)acrylates.

[0082] The term "poly(meth)acrylates" refers—according to the general understanding—to polymers that are accessible through radical polymerization of acrylic and / or methylacrylic monomers, and optionally other copolymerizable monomers. According to the invention, the term "poly(meth)acrylate" encompasses polymers based on acrylic acid and its derivatives, as well as those based on acrylic acid and methacrylic acid and their derivatives, and those based on methacrylic acid and its derivatives, wherein the polymers always contain acrylic acid esters, methacrylic acid esters, or mixtures of acrylic and methacrylic acid esters. The poly(meth)acrylates of the outer adhesive layer preferably have a mean molar mass M w from a maximum of 2,000,000 g / mol.

[0083] Preferably, the monomers of the poly(meth)acrylates of the outer adhesive layer and their quantitative composition are chosen such that, according to the so-called Fox equation (G1) 1TG=∑nwnTG,n (see TG Fox, Bull. Am. Phys. Soc. 1 (1956) 123) a T G This results in a temperature-resulting value for the polymer of ≤ 25 °C. Such a value is particularly advantageous for pressure-sensitive adhesives that are primarily used at room temperature.

[0084] In equation G1, n represents the number of iterations over the monomers used, w n the mass fraction of the respective monomer n (wt%) and T G ,n the respective glass transition temperature of the homopolymer made from the respective monomers n in Kelvin.

[0085] Preferably, the two adhesive layers contain one or more poly(meth)-acrylate(s) which can be traced back to the following monomer composition: a) Acrylic acid esters and / or methacrylic acid esters of formula (F1) CH2 = C(R I )(COOR II ) (F1), where R I = H or CH3 and R II an alkyl group with 1 to 30 C atoms, more preferably with 4 to 14 C atoms and particularly preferably with 4 to 9 C atoms; b) olefinically unsaturated monomers with functional groups that exhibit reactivity with crosslinking substances; c) optionally further olefinically unsaturated monomers that can be copolymerized with monomers (a) and (b).

[0086] Examples of monomers a) are methyl acrylate, methyl methacrylate, ethyl acrylate, n-butyl acrylate, n-butyl methacrylate, n-pentyl acrylate, n-hexyl acrylate, n-heptyl acrylate, n-octyl acrylate, n-octyl methacrylate, n-nonyl acrylate, lauryl acrylate, stearyl acrylate, behenyl acrylate and their branched isomers, such as isobutyl acrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, isooctyl acrylate, isooctyl methacrylate. Particularly preferably, R'' represents a methyl, an n-butyl, and a 2-ethylhexyl group, especially an n-butyl and a 2-ethylhexyl group, or the monomers a) are selected from n-butyl acrylate and 2-ethylhexyl acrylate.

[0087] The monomers b) are preferably olefinically unsaturated monomers with functional groups capable of reacting with epoxide groups. Particularly preferably, the monomers b) each contain at least one functional group selected from the group consisting of hydroxy, carboxy, sulfonic, and phosphonic acid groups, acid anhydride functional groups, epoxide groups, and substituted or unsubstituted amino groups. In particular, the monomers b) are selected from the group consisting of acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, crotonic acid, aconitic acid, dimethylacrylic acid, β-acrylic acid, trichloroacrylic acid, vinylacetic acid, vinylphosphonic acid, maleic anhydride, 2-hydroxyethyl acrylate, 3-hydroxypropyl acrylate, 2-hydroxyethyl methacrylate, 3-hydroxypropyl methacrylate, 6-hydroxyhexyl methacrylate, allyl alcohol, glycidyl acrylate, and glycidyl methacrylate.The monomers b) acrylic acid and / or methacrylic acid, especially acrylic acid, are particularly preferred.

[0088] In principle, all vinylically functionalized compounds that can be copolymerized with monomers a) and monomers b) are suitable as monomers c). The properties of the pressure-sensitive adhesive compound according to the invention can be advantageously controlled by selecting and adjusting the quantity of monomers c).

[0089] The monomers c) are particularly preferably selected from the group consisting of methyl acrylate, ethyl acrylate, n-propyl acrylate, methyl methacrylate, ethyl methacrylate, benzyl acrylate, benzyl methacrylate, sec-butyl acrylate, tert-butyl acrylate, phenyl acrylate, phenyl methacrylate, isobornyl acrylate, isobornyl methacrylate, tert-butylphenyl acrylate, tert-butylphenyl methacrylate, dodecyl methacrylate, isodecyl acrylate, lauryl acrylate, n-undecyl acrylate, stearyl acrylate, tridecyl acrylate, behenyl acrylate, cyclohexyl methacrylate, cyclopentyl methacrylate, phenoxyethyl acrylate, 2-butoxyethyl methacrylate, 2-butoxyethyl acrylate, 3,3,5-trimethylcyclohexyl acrylate, 3,5-dimethyladamantyl acrylate, 4-cumyl-phenyl methacrylate, cyanoethyl acrylate, cyanoethyl methacrylate, 4-biphenyl acrylate, 4-biphenyl methacrylate, 2-naphthyl acrylate, 2-naphthyl methacrylate, tetrahydrofurfuryl acrylate, diethylaminoethyl acrylate, diethylaminoethyl methacrylate, dimethylaminoethyl acrylate, dimethylaminoethyl methacrylate, methyl 3-methoxyacrylate,3-Methoxybutylacrylat, Phenoxyethylacrlylat, Phenoxy-ethylmethacrylat, 2-Phenoxyethylmethacrylat, Butyldiglykolmethacrylat, Ethylenglycolacrylat, Ethylenglycolmonomethylacrylat, Methoxy-Polyethylenglykolmethacrylat 350, Methoxy-Polyethylenglykolmethacrylat 500, Propylenglycolmonomethacrylat, Butoxydiethylenglykolmethacrylat, Ethoxytriethylenglykolmethacrylat, Octafluoropentyl-acrylat, Octafluoropentylmethacrylat, 2,2,2-Trifluoroethylmethacrylat, 1,1,1,3,3,3-Hexa-fluoroisopropylacrylat, 1,1,1,3,3,3-Hexafluoroisopropylmethacrylat, 2,2,3,3,3-Pentafluoro-propylmethacrylat, 2,2,3,4,4,4-Hexafluorobutylmethacrylat, 2,2,3,3,4,4,4-Heptafluoro-butylacrylat, 2,2,3,3,4,4,4-Heptafluorobutylmethacrylat, 2,2,3,3,4,4,5,5,6,6,7,7,8,8,8-Pentadecafluorooctylmethacrylat, Dimethylaminopropylacrylamid, Dimethylaminopropylmethacrylamid, N-(1-Methylundecyl)acrylamid, N-(n-Butoxymethyl)acrylamid, N-(Butoxymethyl) methacrylamid, N-(Ethoxymethyl)acrylamid, N-(n-Octadecyl)acrylamid, N,N-Dialkyl-substituted amides, in particular N,N-dimethylacrylamide, N,N-dimethylmethacrylamide, N-benzylacrylamide, N-isopropylacrylamide, N-tert-butylacrylamide, N-tert-octylacrylamide, N-methylolacrylamide, N-methylolmethacrylamide; furthermore acrylonitrile, methacrylonitrile; vinyl ethers such as vinyl methyl ether, ethyl vinyl ether, vinyl isobutyl ether; vinyl esters such as vinyl acetate; Vinyl chloride, vinyl halides, vinylidene halides, vinylpyridine, 4-vinylpyridine, N-vinylphthalimide, N-vinyllactam, N-vinylpyrrolidone, styrene, α- and p-methylstyrene, α-butylstyrene, 4-n-butylstyrene, 4-n-decylstyrene, 3,4-dimethoxystyrene, 2-Polystyrene ethyl methacrylate (molecular weight M, w from 4000 to 13000 g / mol) and poly(methyl methacrylate)ethyl methacrylate (M w from 2000 to 8000 g / mol). In particular, the monomer c) is methyl acrylate.

[0090] The monomers c) can advantageously be chosen to contain functional groups that support radiation-chemical crosslinking (for example, by electron beams or UV radiation). Suitable copolymerizable photoinitiators include, for example, benzoin acrylate and acrylate-functionalized benzophenone derivatives. Monomers that support crosslinking by electron irradiation include, for example, tetrahydrofurfuryl acrylate, N-tert-butylacrylamide, and allyl acrylate.

[0091] Particularly preferred, if the pressure-sensitive adhesive layers contain several poly(meth)acrylates, is that all poly(meth)acrylates of the pressure-sensitive adhesive layers are derived from the monomer composition described above. In particular, all poly(meth)acrylates of the pressure-sensitive adhesive layers are derived from a monomer composition consisting of acrylic acid, n-butyl acrylate, 2-ethylhexyl acrylate, and methyl acrylate.

[0092] The poly(meth)acrylate is particularly preferred, or rather, all poly(meth)acrylates of the pressure-sensitive adhesive layers are based on the following monomer composition: Acrylic acid 1 to 10 wt.% Methyl acrylate 1 to 15 wt% 2-Ethylhexyl acrylate 30 to 60 wt% n-Butyl acrylate 25 to 50 wt.%, where the proportions of the monomers add up to 100 wt.%.

[0093] According to one variant of the invention, an adhesive compound is selected which comprises at least the following two components: - a first polymer component based on polyacrylate (hereinafter referred to as polyacrylate component) in the adhesive mass to a weight of 60 wt.% to 90 wt.%, preferably 65 wt.% to 80 wt.% - a second polymer component based on elastomers, in particular a synthetic rubber (hereinafter referred to as elastomer component), which is essentially immiscible with the polyacrylate component, in the adhesive mass to a weight of 10 wt.% to 40 wt.%, preferably 15 wt.% to 30 wt.%.

[0094] The above weight percentages refer to the sum of the polyacrylate component and elastomer components as 100 wt.%.

[0095] The second polymer component is essentially immiscible with the first polymer component, so the adhesive mass exists in at least two separate phases within the adhesive layer. In particular, one phase forms a matrix and the other phase forms a plurality of domains arranged within the matrix.

[0096] Homogeneous mixtures are substances mixed at the molecular level; homogeneous systems are correspondingly single-phase systems. The underlying substances are synonymously described as "homogeneously miscible," "compatible," and "conformable." Accordingly, two or more components are synonymously described as "not homogeneously miscible," "incompatible," and "inconformable" if, after intimate mixing, they do not form a homogeneous system but at least two phases. Components that, upon intimate mixing (for example, through shearing, in the melt, or in solution followed by solvent elimination), form at least two phases, each rich in one of the components, are considered synonymous with "partially homogeneously miscible," "partially compatible," "partially conformable," and "partially compatible." However, one or both of these phases may contain a more or less significant homogeneous mixture of the other components.

[0097] The polyacrylate component preferably represents a homogeneous phase. The elastomer component can be homogeneous or multiphase, as is known from microphase-separating block copolymers. The polyacrylate and elastomer components are selected such that, after thorough mixing, they are essentially immiscible at 23 °C (the usual application temperature for adhesives). "Essentially immiscible" means that the components are either not homogeneously miscible at all, so that neither phase contains a homogeneously mixed portion of the other component, or that the components are only so slightly compatible that one or both components can only homogeneously absorb such a small portion of the other component. The corresponding components are then considered "essentially free" of each other.

[0098] The adhesive compound used is therefore present in at least a two-phase morphology at room temperature (23 °C). The polyacrylate component and the elastomer component are very preferably not essentially miscible in a temperature range of 0 °C to 50 °C, and even more preferably from -30 °C to 80 °C.

[0099] The first polymer component based on polyacrylate is preferably predominantly based on acrylic and / or methacrylic monomers, in particular to at least 50 wt.%.

[0100] The second polymer component, based on elastomers, is preferably predominantly attributable to one or more synthetic rubbers, in particular to more than 60 wt.%.

[0101] The synthetic rubbers are further preferably selected from the group of thermoplastic block copolymers, the structure of which can be represented by one of the following formulas: A−B A−B−X−(A'−B')n A−B−X−(B'−A')n QmY where - A or A' is a polymer formed by polymerization of a vinyl aromatic compound, such as styrene or α-methylstyrene, - B or B' is a polymer consisting of isoprene, butadiene or a mixture of butadiene and isoprene or a mixture of butadiene and styrene, or containing wholly or partly ethylene, propylene, butylene and / or isobutylene and - X, Y are each an optional linking group, - Q is each an arm of a multi-arm block copolymer bonded to Y, wherein advantageously each Q is independently articulated by (A*-B*) n is formed, and A* and B* are chosen independently of each other according to the above definition of A and B. - n is an integer between 1 and 4 - m is an integer greater than 2.

[0102] This adhesive compound is described in detail and in particularly suitable embodiments in WO 2015 / 014582 A1, to which explicit reference is hereby made.

[0103] In one embodiment of the invention, the pressure-sensitive adhesive layers contain at least one tackifying resin selected from the group consisting of pinene, indene, and rosin resins and their disproportionate, hydrogenated, polymerized, esterified derivatives and salts; aliphatic and aromatic hydrocarbon resins; terpene resins; terpene phenolic resins; and mixtures of two or more of the aforementioned tackifying resins. All hydrocarbon resins compatible (soluble) with the corresponding poly(meth)acrylate can be used, in particular all aliphatic, aromatic, and alkylaromatic hydrocarbon resins; hydrocarbon resins based on pure monomers; hydrogenated hydrocarbon resins; functional hydrocarbon resins; and natural resins, especially C5 to C9 hydrocarbon resins.The pressure-sensitive adhesive layers preferably contain at least one tackifying resin selected from terpene phenolic resins and C5 to C9 hydrocarbon resins. In particular, the pressure-sensitive adhesive layers contain a terpene phenolic resin.

[0104] Substrates particularly suitable for bonding using the adhesive system according to the invention are metals, glass, and / or plastics. The substrates to be bonded can be the same or different.

[0105] In some cases, it may be necessary to pretreat the surfaces of the substrates to be bonded using a physical, chemical, and / or physicochemical process. Applying a primer or adhesion promoter, for example, is advantageous in this regard.

[0106] Suitable plastic substrates include, for example, acrylonitrile butadiene styrene copolymers (ABS), polycarbonates (PC), ABS / PC blends, PMMA, polyamides, glass fiber reinforced polyamides, polyvinyl chloride, polyvinyl fluoride, cellulose acetate, cycloolefin copolymers, liquid crystal polymers (LCP), polylactide, polyetherketones, polyetherimide, polyethersulfone, polymethacrylmethylimide, polymethylpentene, polyphenyl ether, polyphenylene sulfide, polyphthalamide, polyurethanes, polyvinyl acetate, styrene acrylonitrile copolymers, polyacrylates or polymethacrylates, polyoxymethylene, acrylate-styrene-acrylonitrile copolymers, polyethylene, polystyrene, polypropylene and / or polyesters such as polybutylene terephthalate (PBT) and / or polyethylene terephthalate (PET).

[0107] Substrates can be painted, printed, vapor-deposited, or sputtered. The substrates to be bonded can take on any shape required for the use of the resulting composite body. In their simplest form, the substrates are flat.

[0108] The laminate according to the invention is in particular in the form of a double-sided adhesive tape.

[0109] The general term “adhesive tape” (self-adhesive tape), also synonymous with “adhesive strip” (self-adhesive strip), encompasses, within the meaning of this invention, all planar structures such as films or film sections extended in two dimensions, tapes with extended length and limited width, tape sections and the like, ultimately also die-cut pieces or labels.

[0110] The adhesive tape thus has a longitudinal extent (x-direction) and a lateral extent (y-direction). The adhesive tape also has a thickness (z-direction) perpendicular to both extents, with the lateral and longitudinal extents being many times greater than the thickness. The thickness is as uniform as possible, preferably exactly uniform, over the entire surface area of ​​the adhesive tape, which is defined by its length and width.

[0111] To adjust the properties of double-sided adhesive tape, different adhesive layers can be used. Properties that can be influenced in this way include the tape's thickness, stiffness, flexibility, temperature resistance, elasticity, and flame retardancy. However, the same adhesive can also be used for both adhesive layers.

[0112] The laminate or adhesive tapes according to the invention are usually wound into a roll in the form of an Archimedean spiral at the end of the manufacturing process. To prevent the adhesive components of double-sided adhesive tapes from coming into contact with each other, the tapes are applied to a release liner (also called a separating material) before winding. This release liner is wound together with the tape. Such release liners are known to those skilled in the art as release liners or simply liners. Besides covering double-sided adhesive tapes, liners are also used to cover labels.

[0113] A liner (release paper, release film) is not a component of an adhesive tape or label, but merely an aid in their manufacture, storage, or further processing by die-cutting. Furthermore, unlike an adhesive tape backing, a liner is not permanently bonded to an adhesive layer.

[0114] The laminate or adhesive tape can be supplied in fixed lengths, such as by the meter, or as continuous material on rolls (Archimedean spiral), i.e., disc-shaped adhesive tape rolls, which are referred to in technical terms as "pancake".

[0115] Alternatively, the adhesive tape can be wound onto a core, similar to a textile yarn, whose length is significantly greater than the width of the tape. By superimposing a rotational movement of the core and an axial movement of the core or the tape guide element, the tape initially forms a first, radially innermost layer of helical turns. At the end of the first layer and the transition to the second layer, the orientation of the axial movement is inverted while the rotational movement remains unchanged. At the end of the second layer and the transition to the third layer, the orientation of the axial movement is inverted again, thus reverting to the original orientation, while the rotational movement remains unchanged. The pitch angle remains constant between each of these orientation reversal points. In this way, numerous layers of turns can be formed, with each turn intersecting the others (cross-wound coils).

[0116] Laminates according to the invention are preferably used in widths of 9 to 50 mm, particularly 19 to 25 mm. Roll widths of 10, 15, 19, 25, and 30 mm are typically chosen. Alternatively, the laminates can be sold as bar stock, for example, in widths of 1000 to 1300 mm.

[0117] The laminate according to the invention has a wide variety of applications. The disassembly of touch panels has already been mentioned. Given the great importance of mobile phones, this is a particularly significant area of ​​application. On the one hand, a very strong and, above all, sealing bond for mobile phone displays is desired. On the other hand, it is often necessary to remove the display. The laminate according to the invention is ideally suited for this purpose.

[0118] Finally, so-called "reworkability" is a topic of increasing importance. For example, in the automotive industry, the requirements for the single-material disposal of products at the end of their life cycle are rising. Therefore, it is important that components made of different materials be separated back into their individual components before disposal, even if these components were previously "inseparably" bonded together. The present invention enables a very strong and permanent bond between different components while still allowing for their separation on demand. Measurement methods

[0119] Unless explicitly stated otherwise, measurements are carried out under a test climate of 23 ± 1 °C and 50 ± 5 % relative humidity. Molecular weight

[0120] The molecular weight determinations of the number-mean molecular weights M nand the weight-mean molecular weights M w The measurements are performed using gel permeation chromatography (GPC). THF (tetrahydrofuran) with 0.1 vol% trifluoroacetic acid is used as the eluent. The measurement is performed at 23 °C. PSS-SDV, 10 µm, 10 3 Å, ID 8.0 mm x 50 mm is used. The columns PSS-SDV, 10 µ, 10 are used for separation. 3 as well as 10 5 and 10 7 Each probe has an ID of 8.0 mm x 300 mm. The sample concentration is 0.5 g / l, and the flow rate is 0.5 ml per minute. Calibration is performed using the commercially available ReadyCal kit for poly(styrene) high from PSS Polymer Standard Service GmbH, Mainz, Germany. The values ​​are then universally converted to polymethyl methacrylate (PMMA) using the Mark Houwink parameters K and alpha, so that the data are given in PMMA mass equivalents.

[0121] The invention will be explained in more detail below by means of an example and two figures, without thereby limiting the invention. Example

[0122] A FAYb (fiber laser) is used, emitting at 1.06 µm. The laser is manufactured by SUNX / Panasonic Electric Works and is marketed under the name LP-V10.

[0123] The laser is characterized by the following parameters: Panasonic LP-V10 Series wavelength 1060 nm Laser type Y-fiber laser Laser class 4 Focal length 190 mm Marking field 90 x 90 mm Laser mode 12 watts Laser power single mode Quality switch pulsed Beam quality M2=1,2 Peak heart rate 20 kW Pulse rate 1 - 200 Hz Pulse duration 30 ns Focus size 50 µm Deviation speed 6000 mm / s Production of the samples

[0124] To produce samples of the laminates according to the invention, in the following examples 1 to 4 a lacquer layer was first coated as a separating layer on the underside of a film with a thickness of 50 µm, which consists of a transparent PET film.

[0125] To produce the lacquer layer, the raw materials specified in the examples were combined in a disperser (VMA Getzmann CN10 dissolver) with a water-cooled dispersion vessel (capacity 1 L) and a 60 mm dissolver disc, and homogenized at a temperature of 40 °C for 20 minutes at 8000 rpm. The resulting composition was applied to the film surface using a doctor blade in a layer thickness of 15 µm and cross-linked by electron beam curing at 80 kGy and 240 kV to form a solid lacquer layer. Example 1: Composition of the paint layer (black) 84 pieces Ebecryl 284® Difunctional urethane acrylate (oligomer) from Cytec (contains approx. 12% HDDA), M n 1200 g / mol 4 parts Laromer HDDA® Difunctional acrylate (reactive diluent) from BASF, Hexanediol diacrylate, M n 226 g / mol 8 parts DVE-3® Triethylene glycol divinyl ether (reactive diluent) from BASF, M n 202 g / mol 7 parts Printex 25® soot Example 2: Composition of the paint layer (white) 51 pieces Ebecryl 284® Difunctional urethane acrylate (oligomer) from Cytec (contains approx. 12% HDDA), M n 1200 g / mol 3 parts Laromer HDDA® Difunctional acrylate (reactive diluent) from BASF, Hexanediol diacrylate, M n 226 g / mol 6 parts DVE-3® Triethylene glycol divinyl ether (reactive diluent) from BASF, M n 202 g / mol 40 pieces Kronos 2160® titanium dioxide Example 3: Composition of the paint layer (black) 69 pieces CN 9260® Trifunctional urethane acrylate (oligomer) from Sartomer, M n 2000 g / mol 12 parts SR9020® Trifunctional acrylate (reactive diluent) from Sartomer; Propoxylated glyceryl triacrylate, M n 428 g / mol 12 parts SR 272® Difunctional acrylate (reactive diluent), from the company Sartomer, triethylene glycol diacrylate, M n 258 g / mol 7 parts Printex 25® soot Example 4: Composition of the paint layer (white) 55 pieces CN 9260® Trifunctional urethane acrylate (oligomer) from Sartomer, M n 2000 g / mol 10 pieces SR9020® Trifunctional acrylate (reactive diluent) from Sartomer; Propoxylated glyceryl triacrylate, M n 428 g / mol 10 pieces SR 272® Difunctional acrylate (reactive diluent), from the company Sartomer, triethylene glycol diacrylate, M n 258 g / mol 25 pieces Kronos 2160® titanium dioxide

[0126] The exposed surface of the paint layer was coated with an acrylate-based adhesive with an application weight of 50 g / m². 2 The surface was coated. A resin-modified acrylate adhesive was used as the pressure-sensitive adhesive, consisting of 80 wt% acrylate copolymer and 20 wt% terpene phenol resin. The copolymer was obtained by polymerizing 47.5 wt% n-butyl acrylate, 47.5 wt% 2-ethylhexyl acrylate, 2 wt% glycidyl methacrylate, and 1 wt% acrylic acid. This adhesive layer was covered with a liner. The PET film was then removed.

[0127] The now exposed surface of the paint layer was also coated with the same acrylate-based adhesive at an application rate of 50 g / m². 2 coated.

[0128] The resulting double-sided adhesive tape is applied – after removing the liner – between two glass bodies, thus bonding them together. Each glass body is 2 mm thick.

[0129] The optimal ablation of the separating layer between the two adhesive layers is set using a test matrix of laser power, frequency and deflection speed. The following parameters are set on the laser: parameter Laser Power 45,0 % Scan speed 1000 mm / sec. Laser Pulse Cycle 50 µs Line width 0.15 mm Marking pitch 0.15 mm

[0130] In the Fig. Figure 2 shows the structure of the double-sided adhesive tape 2 and its use. The laminate 2 is located between two substrates 11, 12, which here both consist of glass layers.

[0131] The adhesive tape 2 has a 15 µm release layer 23. Adhesive layers 21 and 24 are applied to the top and bottom of the release layer 23.

[0132] The laser beam 22 ablates the separation layer 23.

Claims

[1] Laminate 2, designed and prepared to be separated after permanent bonding, comprising the following layers: a) a first adhesive layer 21, b) a separation layer 23, c) a second adhesive layer 24, characterized by , that the separation layer 23 - contains a laser-sensitive pigment that also provides color, - consists of a hardened lacquer that can be at least partially removed by laser irradiation 22, wherein the first adhesive layer 21 and / or the second adhesive layer 24 are laser beam translucent, characterized by , that The separating layer 23 consists of a single layer of lacquer. [2] Laminate 2 according to claim 1, characterized by, that the hardened lacquer of the release layer 23, which preferably consists of an electron beam or UV-cured lacquer, comprises radiation-curable systems such as unsaturated polyesters, epoxy, polyester and urethane acrylates, in particular aliphatic urethane acrylate oligomers. [3] Laminate 2 according to claim 1 or 2, characterized by that the lacquer of the release layer 23 comprises a hardened acrylate lacquer composition, in particular with the following composition • 30 to 80 wt% of a trifunctional oligomer A, • 0 to 20 wt% of a trifunctional monomer B, • 1 to 30 wt% of a difunctional monomer C as well as • 2 to 40 wt% of a coloring pigment. [4] Laminate 2 according to at least one of claims 1 to 3, characterized bythat the laser-sensitive pigment is added in an amount ranging from 1 wt.% to a maximum of 40 wt.%, preferably in amounts of 2 to 28 wt.% or in amounts of 5 to 15 wt.% based on the total weight of the coating layer. [5] Laminate 2 according to at least one of the preceding claims, characterized by , that the laser-sensitive pigment produces a black coloration of the separation layer 23. [6] Laminate 2 according to at least one of the preceding claims, characterized by , that carbon black or titanium dioxide are used as laser-sensitive pigments. [7] Laminate 2 according to claim 6, characterized by , that if soot is present as a laser-sensitive pigment, the soot is used at a concentration of 2 to 7 wt.%. [8] Laminate 2 according to claim 6, characterized by , that if titanium dioxide is present as a laser-sensitive pigment, titanium dioxide is used in a concentration of 15 to 40 wt.%, preferably 22 to 28 wt.%. [9] Laminate 2 according to at least one of the preceding claims, characterized by , that the separating layer 23 is applied in a thickness of 0.5 to 100 µm, preferably 1 to 30 µm, in particular 5 to 25 µm. [10] Laminate 2 according to at least one of the preceding claims, characterized by , that at least one of the two adhesive layers 21, 24 contains at least 40 wt.% of one or more poly(meth)acrylates / e. [11] Laminate 2 according to at least one of the preceding claims, characterized by , that at least one of the two adhesive layers 21, 24 is an adhesive compound comprising at least the following two components: - a first polymer component based on polyacrylate (hereinafter referred to as polyacrylate component) in the adhesive mass to a weight of 60 wt.% to 90 wt.%, preferably 65 wt.% to 80 wt.% - a second polymer component based on elastomers, in particular a synthetic rubber (hereinafter referred to as elastomer component), which is essentially immiscible with the polyacrylate component, in the adhesive mass to a weight of 10 wt.% to 40 wt.%, preferably 15 wt.% to 30 wt.%. [12] Method for breaking a permanent bond formed by means of a laminate 2 according to any one of claims 1 to 11, characterized by , that the separating layer 23 is at least partially removed by means of laser irradiation 22 and the film laminate 2 is separated into a first partial laminate and a second partial laminate. [13] Method according to claim 12, characterized by , that forces are applied to at least one of the sub-laminates that increase the distance between the two sub-laminates. [14] Method according to at least one of claims 12 or 13, characterized by , that an infrared laser is used for laser irradiation 22. [15] Method according to at least one of claims 12 to 14, characterized by , that the separating layer 23 is completely removed. [16] Use of a film laminate 2 according to at least one of claims 1 to 10 in the automotive industry. [17] Use of a film laminate 2 according to at least one of claims 1 to 10 in the electronics industry.

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