Method for permanently sealing holes with overpressure protection and adhesive element therefor

Abstract

To provide a method which can seal (block) an air gap penetrating the inside of a baseboard, and as a result of overpressure, can surely reduce pressure by a vent.SOLUTION: An adhesion element (14) includes a pressure opening region (20) which is at least partially surrounded by a fragile region (22) formed at a carrier layer (18), and an average thickness of the carrier layer in the fragile region is set thinner than an average thickness of the carrier layer in the pressure opening region. Here, an action of prescribed opening pressure to the pressure opening region at least partially and irreversibly fractures the adhesion element in the fragile region, and the adhesion element is constituted so as to form a penetration hole at the adhesion element. Then, the adhesion element is made to adhere so that the pressure opening region at least partially covers an air gap (10) which has penetrated the inside of a baseboard (12).SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a method for sealing a through void in a substrate, a corresponding overpressure protection substrate, an adhesive element for permanently sealing a hole with an overpressure protection means, and the use of the corresponding adhesive element for permanently sealing a hole in a substrate and for producing an overpressure protection means. [Background technology]

[0002] When producing complex products, for production reasons it is often necessary to provide holes in the processed parts or substrates, through which further work steps can be carried out during the production process. However, at the end of the production process, these holes are often no longer necessary and are even disadvantageous for many end uses, for example because they allow the ingress of moisture and impurities. For this purpose, it is known in the prior art that the use of adhesive elements, such as so-called die cuts, is an efficient way to permanently seal holes and, in turn, to permanently seal corresponding through-holes in the substrate during the production process, as for example in EP 3569406 A1, EP 3943283 A1 or EP 3992259 A1.

[0003] However, in many cases the through gap in the substrate does not only have a manufacturing purpose: rather, it may be necessary to be able to influence the pressure inside the substrate, e.g. a battery housing, and for this purpose a suitable pressure regulator, e.g. in the form of a valve, must be provided in the region of the through gap for the necessary pressure management.

[0004] So-called overpressure protection (overpressure protection means), sometimes also called "burst systems", are particularly important in the field of pressure management inside boards. Such overpressure protection is usually structurally more complex but is used, for example, to protect components installed in electronic devices and to allow the pressure to be equalized to the pressure of the surrounding environment when a defined internal pressure is reached, by releasing the excess pressure during venting.

[0005] The corresponding overpressure protection is particularly relevant for battery housings, such as are used today, for example in the field of electric vehicles. These battery housings are used for the storage and generation of electrochemical energy and are, for example, in the form of so-called pouch cells, contained within the components of the electrochemical cell. The corresponding electrochemical cells, for example lithium-ion batteries, are complex and in some cases, and especially in many cases, are systems prone to failure, since they contain flammable substances, in particular electrolytes, and high temperatures can occur during operation.

[0006] The resulting worst case scenario for a battery is known as thermal runaway, which often results in high pressure inside the battery housing due to released gases and evaporated liquid components, which can cause the battery housing to rupture uncontrollably, which can in turn damage the surrounding area, and in the worst case scenario, can result in an undesirable chain reaction.

[0007] For this reason, good overpressure protection is particularly relevant for the safety of battery housings. The growing importance of electric vehicles in the automotive industry and the increasing use of electrochemical energy storage devices means that there is a continuing interest in improved overpressure protection, particularly suitable for use in battery housings.

[0008] One overpressure protection known from the prior art is disclosed, for example, in CN107178638A. The overpressure protection devices known from the prior art are often technically complex parts that generally have to be fitted into the through gaps of the substrate, involve a lot of manufacturing costs and labor, and have a relatively high specific weight and a certain specific volume. Moreover, the corresponding prior art burst systems often have to be specially designed for a specific hole geometry, and often cannot be flexibly adapted to different dimensions of the holes to be sealed. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] CN107178638A Summary of the Invention [Problem to be solved by the invention]

[0010] SUMMARY OF THE PRESENT EMBODIMENT It is a primary object of the present invention to eliminate or at least reduce the disadvantages of the prior art.

[0011] In particular, it is an object of the present invention to provide a method for sealing (closing) through-voids in a substrate, which method allows a reliable and fluid-tight sealing of the through-voids and which allows a reliable reduction in pressure by venting as a result of excess pressure.

[0012] It was an object of the invention to be able to carry out the determination method using as few space-consuming and weightless components as possible.

[0013] Furthermore, it was an object of the present invention that the sealing of the through gap in a manner to be specified should be possible in a particularly simple manner and preferably an easy possibility for automation should be ensured.

[0014] It was a further object of the present invention that the method to be identified be capable of being carried out in a particularly time- and cost-efficient manner, in particular at high throughput rates, and also, desirably, with as low as possible storage costs associated with the storage of the components used in the method.

[0015] A complementary objective of the present invention was that the method specified should be particularly flexible for sealing through gaps having different hole shapes as a result of the components used and ideally should not require specific adaptation of the components used to the different hole geometries.

[0016] A further object of the invention was to provide a particularly reliable and long-lasting sealing of the hole in the specified manner until the overpressure protection is inserted (until the overpressure protection is started). In this respect, a supplementary object of the invention was that an overpressure protection produced in the specified manner allows a significant directional dependence of the overpressure protection, so that overpressure acting on the seal from the outside does not result in pressure equalization, even at high overpressures.

[0017] In light of the above observations, the object of the present invention was to specify an overpressure protection substrate manufactured in a specified manner.

[0018] Furthermore, it was an object of the present invention to identify a part for permanently sealing a hole with overpressure protection, which can be used in a defined manner, and further to identify applications based on this part. [Means for solving the problem]

[0019] The inventor has discovered that the above-mentioned object can surprisingly be achieved by using a specific adhesive element, which, instead of a complex structure of burst systems for sealing through-voids in a substrate, is able to bond through-voids in a fluid-tight manner, the adhesive element comprising, as a result of the weakening of the carrier layer, pressure opening areas which, when subjected to a predefined opening pressure, are largely irreversibly opened, so that pressure equalization takes place through the through holes of the adhesive element, which equalization is as defined in the claims.

[0020] Surprisingly, this design of the adhesive elements and their use in the corresponding method not only allows a reliable fluid-tight sealing of through gaps in the substrate, but also a reliable opening behavior in the event of overpressure, which is precisely adjustable via the degree of weakening of the carrier layer.The inventors have found that a particularly advantageous method results from the relatively simple design of the adhesive elements and their simple application.

[0021] With regard to its application, the corresponding adhesive element is particularly easy to automate and cost-effective to produce, as well as having a particularly low inherent weight and volume. Advantageously, the corresponding adhesive element, and thus the corresponding method, has a high tolerance to deviations in the shape of the hole, so that manufacturing tolerances can be low and the adhesive element can be used to seal through gaps of different dimensions.

[0022] Thus, the above mentioned object is achieved by the subject matter of the invention as defined in the claims. Preferred embodiments of the invention are evident from the dependent claims and the following description.

[0023] Such embodiments are referred to below as preferred, but in particular preferred embodiments, they are combined with features of other embodiments designated as preferred. Thus, combinations of two or more of the embodiments described below are highly preferred. Also preferred are embodiments in which features of one embodiment designated as preferred are combined with one or more further features of other embodiments designated as preferred. The preferred adhesive element, overpressure protected substrate (overpressure protected substrate) and application features are evident from the preferred method features.

[0024] The present invention relates to a method for sealing a through void in a substrate, the method comprising the steps of: a) manufacturing or providing an adhesive element comprising: i) an adhesive layer comprising an adhesive; ii) a carrier layer disposed on the adhesive layer, the carrier layer comprising a first carrier layer; b) adhering the adhesive element to the substrate by means of an adhesive layer, such that the adhesive element completely covers the through-hole and the through-hole is fluid-tightly sealed by the adhesive element; wherein the adhesive element (14) includes a pressure opening area (20) at least partially surrounded by a weakened area (22) formed in the carrier layer (18), wherein an average thickness of the carrier layer (18) in the weakened area (22) is less than an average thickness of the carrier layer (18) in the pressure opening area (20); wherein the adhesive element (14) is configured such that the application of a predetermined opening pressure to the pressure opening area (20) irreversibly breaks the adhesive element (14) at least partially in the weakened area (22) and forms a through hole (24) in the adhesive element (14), An adhesive element (14) is then adhered such that the pressure opening area (20) at least partially covers the through void (10) in the substrate (12).

[0025] The method of the invention serves for sealing through voids, more particularly holes, more particularly fluid-tight sealing in a substrate, and in fact is particularly relevant for sealing holes in a substrate, the interior of which is in fluid communication with the surroundings. Correspondingly preferred is a method of the invention, in which the substrate comprises an interior which is fluid-tight sealed by bonding an adhesive element in the through void.

[0026] An advantageous feature of the method of the invention is that there is virtually no restriction regarding the nature of the substrate. However, in the inventor's estimation, the method of the invention is particularly suitable for sealing battery housings, since these housings, which often have a large number of individual elements, particularly benefit from the low weight and low manufacturing costs of the solutions found in the context of the invention. Accordingly, it is particularly preferred that in the method of the invention, the substrate is a housing, preferably a housing of an electronic device or a battery, particularly preferably a housing of a battery. Additionally or alternatively, it is also preferred that in the method of the invention, the substrate is selected from the group consisting of metals, composite materials, for example composite materials containing glass fibers or carbon fibers, plastics, preferably plastics and metals, particularly preferably metals, more particularly coated metals.

[0027] Those skilled in the art will understand that the corresponding substrate may contain two or more through voids, but in that case, it is preferred that all voids are sealed by the method of the present invention.However, alternatively, the through voids present in the substrate may also be sealed by the method of the present invention, and may also be sealed by other methods, such as conventional adhesive elements without overpressure protection.Therefore, preferably, in the method of the present invention, the substrate contains two or more through voids, and preferably, all through voids are sealed by the method of the present invention.

[0028] In accordance with the understanding of the skilled artisan, the adhesive element used in the method of the invention is a sheet-like adhesive element, which means that in two spatial directions in a plane it has a significantly greater extent than in the direction perpendicular to the plane. The corresponding adhesive element here can be produced, for example, by methods known to the skilled artisan and can also be produced, for example, by methods of the kind employed in the production of other adhesive elements. Typically, the corresponding sheet-like adhesive element is separated by a suitable cutting method from a larger pre-produced adhesive composite, the adhesive element being available in large quantities. The separation is carried out, for example, by die-cutting (punching) the adhesive element, in which case the element is usually called die-cut. Thus, preferred in the method of the invention is that the adhesive element is die-cut from an adhesive composite comprising an adhesive layer and a carrier layer arranged on the adhesive layer, the weakened area being preferably produced before die-cutting. Particularly preferred is the method of the invention, according to which the adhesive element is die-cut.

[0029] In the method of the invention, instead of producing the adhesive element, for example by cutting, it is also possible to simply provide the adhesive element, for example by purchasing it from a supplier.

[0030] The adhesive element used comprises an adhesive layer and a carrier layer, which are bonded (bonded) to one another, as known to those skilled in the art of adhesive technology from numerous adhesive tapes and comparable bonding products. The adhesive layer serves to bond the adhesive element to the substrate and ensures the necessary adhesion of the adhesive element on the substrate in order to prevent unwanted premature detachment in the event of a relatively small pressure difference between the two sides of the substrate or other mechanical loads.

[0031] In order to carry out the process as efficiently as possible, the inventors propose to design the adhesive as a pressure-sensitive adhesive, in particular because it allows the adhesive element to be applied easily, but also makes it possible to easily correct imperfect application if necessary. Therefore, in the method according to the invention, preferably the adhesive is a pressure-sensitive adhesive.

[0032] A pressure-sensitive adhesive is understood by those skilled in the art to be an adhesive with pressure-sensitive adhesive properties, i.e., an adhesive capable of durable adhesion to a substrate even under relatively low applied pressure. The corresponding pressure-sensitive adhesive tapes generally have a permanent inherent tack even at room temperature, i.e., have a certain viscosity and contact adhesion so as to wet the surface of the substrate even under low applied pressure. Without being bound by this theory, it is often assumed that pressure-sensitive adhesives can be considered as extremely high viscosity fluids with an elastic component, and therefore have characteristic viscoelastic properties that result in the above-mentioned permanent inherent tack and pressure-sensitive adhesive capabilities. It is assumed that in such pressure-sensitive adhesives, a viscous flow process exists upon mechanical deformation, and elastic restoring forces are generated. The viscous flow component helps to achieve adhesion, while the elastic restoring forces are particularly necessary for achieving cohesion. The relationship between rheology and pressure-sensitive adhesion is known in the prior art and is described, for example, in Satas, "Handbook of Pressure Sensitive Adhesive Technology", third edition, (1999), pages 153 to 203. To characterize the degree of elastic and viscous components, it is common to employ the storage modulus (G') and loss modulus (G''), which can be ascertained, for example, by dynamic mechanical analysis (DMA) using a rheometer, as disclosed, for example, in WO2015 / 189323. For the purposes of the present invention, the adhesive preferably has a viscosity of 10 0 ~10 1 At a temperature of 23°C in the deformation frequency range of 10 rad / sec, G' and G'' are at least partially 10 3 ~10 7 When the adhesive has a pressure-sensitive adhesive property, it is understood to be a pressure-sensitive adhesive when the adhesive has a pressure-sensitive adhesive property.

[0033] As a possible alternative embodiment to the above-mentioned preferred embodiment as a PSA, it is conceivable to implement the adhesive as a reactive adhesive, i.e. as an adhesive which only hardens as a result of a curing step, so that the curing of the adhesive and its effect as a construction adhesive make this embodiment particularly interesting for applications in which a relatively high predefined opening pressure is set. Thus, preferred for certain applications in the method according to the invention is that the adhesive is a curable adhesive, preferably a radiation-curable and / or heat-curable adhesive, in which case the method preferably further comprises, after method step b), the following method steps: c) at least partially curing the curable adhesive.

[0034] According to the inventor's assessment, the main advantage of the method of the invention is considered to be the great flexibility with regard to the chemical nature of the adhesive used in the adhesive element. The basic functionality of the method of the invention results in particular from the interaction of the specifically weakened carrier layer with a common adhesive, and is therefore not limited to chemically specific adhesives, in the inventor's assessment. This allows the appropriate adhesive to be advantageously selected in terms of other application requirements, in particular the adhesive strength on the respective substrate and / or the temperature stability for the targeted application area. The inventor has therefore succeeded in identifying adhesives which are presumed to result in particularly good performing adhesive elements. In practice, it is preferred that in the method of the invention the adhesive comprises one or more polymers selected from the group consisting of polyurethanes, poly(meth)acrylates and synthetic rubbers, preferably poly(meth)acrylates and synthetic rubbers, particularly preferably poly(meth)acrylates.

[0035] In the context of the present invention, the expression "poly(meth)acrylate" also includes polyacrylates and polymethacrylates, as well as copolymers of these polymers, in accordance with the understanding of the skilled person. Poly(meth)acrylates may contain relatively small amounts of monomer units not derived from (meth)acrylates. Thus, "poly(meth)acrylate" is understood in the context of the present invention to be a (co)polymer in which the mass fraction of monomers selected from the group consisting of acrylic acid, methacrylic acid, acrylic acid esters and methacrylic acid esters is 70% or more, preferably 90% or more, particularly preferably 98% or more, based on the weight of the monomer base. The mass fraction of acrylic acid esters and / or methacrylic acid esters is preferably 50% or more, particularly preferably 70% or more. Poly(meth)acrylates are generally obtainable by radical polymerization of acrylic and / or methacrylic monomers and, optionally, copolymerizable monomers.

[0036] According to the inventor's assessment, it is advantageous for certain end uses to implement the adhesive as a foam adhesive, for example as a synthetic foam adhesive with expanded microballoons as basically known from the prior art, or as a physical foam adhesive, which can be produced, for example, with blowing gas. Such foam adhesives often have advantages, especially with regard to impact resistance. According to the inventor's assessment, it can therefore be considered as an advantage of the method of the invention that the foaming of the adhesive does not interfere with the basic functionality of the adhesive element of the invention. Therefore, in the method according to the invention, which is preferred for certain applications, the adhesive is a foam adhesive, which is preferably a physically foamed adhesive and / or comprises one or more components selected from the group consisting of hollow spheres and at least partially expanded microballoons.

[0037] From the viewpoint of the most material-saving production possible and good handling properties, the inventors propose that the dimensions of the adhesive layer and the carrier layer are as similar as possible. Although in some applications it may be preferable for the carrier layer to protrude above the adhesive layer, it is preferred, particularly from the viewpoint of production efficiency, that this layer is completely covered by the adhesive layer. Preference is therefore given to a method according to the invention in which the carrier layer on one side is covered by the adhesive layer by at least 50%, preferably at least 70%, particularly preferably at least 90%, particularly preferably at least 95%, and more particularly preferably substantially completely.

[0038] According to the invention, the carrier layer comprises, and in many cases in practice the carrier layer essentially consists of, a first carrier layer, and further, in the method of the invention, in connection with the majority of embodiments, an adhesive layer is disposed on the first carrier layer.

[0039] In this context, it is recognized that the method of the present invention has the advantage that it is fundamentally very flexible with regard to the choice of material for the first carrier layer, and the skilled person can rely on typical materials already known in the field of adhesive technology as carrier materials. However, the inventors have succeeded in identifying suitable materials with which in all cases very reliable and strong adhesive elements can be obtained for use in the method of the present invention. More preferred in the present invention is that the first carrier layer is a foil selected from the group consisting of polymer foils, for example polyester foils, PEEK foils, PAEK foils, polyimide foils or polyamide foils, more particularly polyester foils, and metal foils, preferably metal foils. Additionally or alternatively, the method according to the present invention is preferred.

[0040] Particularly in the case of relatively demanding applications, such as adhesive sealing, which is subjected to high thermal and / or chemical and / or mechanical loads that are expected during use, it is possible for the carrier layer to comprise further carrier layers in addition to the first carrier layer, for example to optimize the physicochemical properties, in particular the surface properties. In a preferred method according to the invention, the carrier layer comprises one or more, preferably two or more, particularly preferably three or more further carrier layers, the carrier layers in the carrier layer being preferably connected to one another by intermediate adhesive layers.

[0041] According to the inventor's assessment, in a preferred embodiment, in particular the carrier layer comprises as an additional layer a protective foil which shields the underlying carrier layer, in particular the first carrier layer, from environmental influences, which is particularly advantageous when the first carrier layer is made of metal, and which can prevent damage that would occur to the first carrier layer as a result of this unwanted corrosion, even in the long term. More preferably, in the method of the invention, the carrier layer comprises as an additional carrier layer a protective foil on that side of the first carrier layer remote from the adhesive layer, the protective foil being preferably selected from the group consisting of polymer foils, and particularly preferably the protective foil substantially completely covers the surface of the carrier layer.

[0042] According to the invention, the through gap is completely covered with the corresponding adhesive element and is thereby sealed fluid-tight. The skilled person will understand that this kind of overpressure protection, which will be described in detail below, means that this fluid-tight seal can be ruptured in the event of an application pressure. For this purpose, the adhesive element according to the invention comprises a weakened area in which the average thickness of the carrier layer is reduced relative to the remaining part of the adhesive element, in which the carrier layer exhibits a reduced mechanical robustness and thereby represents a kind of predetermined breaking point of the carrier layer. The predetermined opening pressure, i.e. the pressure at which the overpressure protection acts, can advantageously be adjusted via the degree of weakening in the weakened area. In a preferred method according to the invention, the carrier layer in the weakened area has an average thickness in the range of 5 to 150 μm, preferably in the range of 10 to 100 μm, particularly preferably in the range of 15 to 60 μm, and / or the average thickness of the carrier layer in the weakened area is 5% to 95%, preferably 10% to 80%, particularly preferably 20% to 60% smaller than the average thickness of the carrier layer in the pressure opening area.

[0043] Thus, the skilled person understands that the adhesive element is configured to form a through hole when a predefined opening pressure acts on the pressure opening area. As understood by the skilled person, the action of this predefined opening pressure means, for example, a pressure difference between the two sides of the adhesive element, which occurs when the adhesive element covers a void in a closed container and the pressure in the container increases. It is clear to the skilled person that the predefined opening pressure does not mean the ambient pressure that is experienced in the same way on all sides and areas of the adhesive element, and therefore there is no effect of the force acting on the pressure opening area on the other parts of the adhesive element. In other words, the predefined opening pressure therefore indicates an opening pressure difference.

[0044] The description "at least partially irreversibly destroyed" used in the context of the present invention means, as understood by the skilled artisan, that complete destruction of the weakened area is not necessary, as long as the destruction is sufficient to form a through hole in the adhesive element. For example, a circular weakened area completely surrounding the pressure opening area can be destroyed only over a part of the circumference for a given opening pressure, so that the pressure opening area is only partially removed from the adhesive element. It is also not necessary that the destruction is completely irreversible. As a result of the physicochemical properties of typical adhesives, in particular their flow behavior, it is at least theoretically conceivable that the pressure opening area pushed back into the adhesive element can be at least provisionally closed through the interaction of the adhesive, despite the irreversibly destroyed carrier layer, so that the lifted pressure opening is held in place by the adhesive layer.

[0045] Although theoretically it is conceivable to provide relatively large and extensive areas of reduced thickness, and such relatively complex weakened areas may be reasonable for certain applications, the inventors are aware that with a view to precise opening of the weakened areas in combination with simple production it is preferable to embody these areas in the form of substantially groove-like voids, i.e. elongated depressions, in the carrier layer. Correspondingly, in the preferred method according to the invention, the weakened areas are designed as groove-like voids in the carrier layer.

[0046] Those skilled in the art understand that the resistance that the adhesive element can provide to the applied pressure difference after the hole is sealed is predominantly influenced by the mechanical robustness of the carrier layer and the first carrier layer, while the contribution of the adhesive layer is lower, especially in many cases, since the adhesive layer is to some extent fluid. Therefore, if the predetermined opening pressure is not intended to be effective at very low pressures, it is useful to form the carrier layer without a completely through-hole in order to prevent premature passage of fluid at low pressures. In the method of the present invention, preferably, the weakened area does not include a void that completely penetrates the carrier layer, especially the first carrier layer.

[0047] Due to the defined opening pressure by the carrier layer, which is usually present in any case, and the above-mentioned decisive influence on the flow behavior of the adhesive, it is advantageously not necessary to provide a corresponding reduction in the average thickness in the adhesive layer in a manner complementary to the weakened areas, which can simplify production accordingly.Against this background, in a preferred method according to the invention, the average thickness of the adhesive layer in the weakened areas is at most 20%, preferably at most 10%, particularly preferably at most 5%, particularly preferably at most 1%, more particularly preferably at most 0.1% less than the average thickness of the adhesive layer in the pressure opening areas.

[0048] The skilled person will understand that the dimensions of the pressure opening area depend on the profile of the weakened area. Its shape and dimensions are therefore determined by the predefined breaking point, i.e. the weakened area, which is at least partially removed from the adhesive element in the event of excessive pressure. According to the inventor's evaluation, the pressure opening area can therefore be provided with a number of basic shapes, whereby, from the viewpoint of ease of application and a reliable holding of the adhesive element on the substrate, it is often preferred to adapt the shape of the pressure opening area to the shape of the void to be covered and to locate the pressure opening area relatively centrally in the adhesive element. Preference is therefore given to the method of the invention, in which the pressure opening area has a basic shape selected from the group consisting of a circle, a part circle, in particular a semicircle, an ellipse or a polygon, preferably selected from the group consisting of a circle, a semicircle and an ellipse. Additionally or alternatively preferred is the method of the invention, in which the pressure opening area has a basic shape that substantially corresponds to the cross section of the pierced void. Particularly preferred in all embodiments of the method of the invention is that the center point of the adhesive element is within the pressure opening area.

[0049] The inventors have realized that the method of the invention and the adhesive element used therein advantageously make it possible, by relatively small changes in the manufacturing process of the adhesive element, to influence factors including how far the adhesive element is opened when overpressure protection intervenes, and thus to influence the flow of fluids. Here, in particular, a very wide opening of a pierced hole (through hole) is obtained if the pressure opening area is surrounded as widely as possible by the weakened area. In this case, in one embodiment, it is particularly interesting to substantially completely surround the pressure opening area with the weakened area, which makes it particularly easy to completely remove the pressure opening area from the adhesive element, which has been lifted (raised) from the adhesive element as a result of the acting overpressure. Correspondingly, it is preferred in the method of the invention if, based on the circumference of the pressure opening area, the pressure opening area is surrounded by the weakened area to an extent of at least 50%, preferably at least 70%, particularly preferably at least 90%, particularly preferably at least 95%, more particularly preferably substantially 100% of the circumference.

[0050] As an alternative embodiment to this, the inventors propose that it is possible to purposely provide no weakened area on the circumferential part of the pressure opening area, so that an unweakened connection remains between the raised pressure opening area and the remaining part of the adhesive element, which advantageously makes it possible to prevent the raised pressure opening area from being too easily detached as a result of mechanical load and remaining, for example, as a foreign body in the housing. Therefore, in the method according to the invention, it is preferable that, based on the circumference of the pressure opening area, the pressure opening area is not surrounded by a weakened area in the range of 0.1% to 10%, preferably 0.2% to 5%, particularly preferably 0.5% to 2% of the circumference.

[0051] The weakened areas in the adhesive element, i.e. the local reduction in the average thickness in the carrier layer, can be advantageously produced, according to the inventor's estimation, using a wide range of possible methods, with die cutting being particularly suitable for mass production of adhesive elements, while the use of laser structuring is particularly suitable for establishing precise weakened areas. Accordingly, preferred is a method according to the invention, in which the weakened areas in the adhesive element are produced by means of a material ablation or cutting process, preferably laser structuring or die cutting.

[0052] In the course of the development of the invention, the inventors experimented with different directions in which the material of the adhesive element could be processed. In a first attempt, the material was processed from the direction of the carrier layer, i.e. from the side facing away from the adhesive layer. This resulted in satisfactory weakened areas, but nevertheless, a hindrance was that, in some cases, especially in the case of mechanical processing methods, the action of forces on the carrier layer can also affect the underlying adhesive layer, for example pressing it against the underlying surface, which can lead to undesirable adhesion of the adhesive layer and / or deformation of the adhesive layer. The inventors surprisingly realized that the weakened areas are more easily generated if the carrier layer is processed from the side covered with the adhesive layer, i.e. the processing is carried out, so to speak, through the adhesive layer. This is possible, surprisingly, because the adhesive layer has a certain flowability due to the adhesive, and the local displacements of the material occurring in the course of processing the carrier layer are relatively easily compensated over time. In the method of the invention, which is preferred for some applications, the weakened areas in the adhesive element are generated by processing the side of the carrier layer facing away from the adhesive layer. Alternatively, however, particularly preferred is a method according to the invention, in which the weakened area in the adhesive element is produced by processing the surface covered with the adhesive layer, the processing preferably taking place through the adhesive layer.

[0053] The skilled person will understand that the predetermined opening pressure is crucially influenced by the design of the adhesive element used, in particular the dimensions and embodiment of the weakened area, and thus the structural design of the adhesive element allows the desired opening behavior to be precisely adjusted. According to the inventors' assessment, if the predetermined opening pressure is too low, in many cases the structural integrity of the entire adhesive element is essentially reduced, where manufacturing-related deviations in the weakened area and, as a result, absolute variations in the predetermined opening pressure can appear as relatively large uncertainties. Accordingly, the inventors propose to select a predetermined opening pressure that is not too low. At the same time, a particularly high predetermined opening pressure imposes, at least indirectly, relatively strict requirements on the adhesive used and / or the adhesive strength on the substrate, the intention being to prevent adhesion failure of the entire adhesive element and thus premature degassing (venting) before the opening of the pressure opening area. Accordingly, the inventors propose not only a valid lower limit for the opening pressure, but also a range and associated upper limit that, according to the inventors' assessment, is suitable for many applications and can be effectively established with typical adhesive and carrier materials. In the method of the present invention, the predetermined opening pressure is preferably 10 kPa or more, more preferably 15 kPa or more, particularly preferably 20 kPa or more, particularly preferably 25 kPa or more, and / or the predetermined opening pressure is in the range of 5 to 200 kPa, preferably in the range of 10 to 150 kPa, particularly preferably in the range of 15 to 100 kPa, particularly preferably in the range of 2 to 50 kPa.

[0054] The advantage of the method according to the invention, in particular in comparison with the burst systems known from the prior art, is that the application of the required adhesive elements is particularly easy and therefore also easy to automate. Correspondingly, it is preferred in the method according to the invention that the application of the adhesive elements is carried out automatically, preferably by means of a robot arm.

[0055] In order to obtain an optimal opening effect in the event of overpressure, the inventors propose to arrange the pressure opening area substantially concentrically on the through gap, which is preferably the case in the method according to the invention.

[0056] A particularly convenient embodiment, which shows great flexibility, especially with regard to the hole shape to be sealed with it, is obtained when the pressure opening area is smaller than the through-void to be sealed and the through-void is completely located above the pressure opening area in a plan view. In such a case, the method according to the invention preferably has a pressure opening area which has a smaller area than the cross-section of the through-void and the adhesive element is preferably glued in such a way that the pressure opening area is completely located above the through-void.

[0057] However, in the case of the above-mentioned embodiments in which the pressure opening area is completely surrounded by the edge of the through-hole, the inventor's own experiments have proven the disadvantage that it is more difficult to establish an anisotropic opening behavior. In other words, the corresponding embodiment is more likely to open into the inside of the sealed housing, for example as a result of excess pressure acting on the substrate from the outside on the surface of the carrier layer, i.e. in most applications, as a result of excess pressure acting on the substrate from the outside. Even if this is desirable for certain embodiments, it is recognized that this type of opening behavior is disadvantageous for the majority of applications, especially in the area of ​​the battery housing. In the course of development, the inventor recognized that in order to establish a directional dependence of the opening behavior, the adhesive element should be bonded in such a way that the pressure opening area overhangs at least partially beyond the edge of the through-hole. The effect of this is advantageously that the overlap between the edge of the through-hole and the pressure opening area, together with the rigidity of the carrier layer, counteracts undesired opening of the pressure opening area in the direction of the sealed gap. It is therefore particularly preferred in the method according to the invention that the pressure opening area is at least partially, preferably at least 50%, particularly preferably at least 70%, particularly preferably at least 90%, very particularly preferably at least 95% and very particularly preferably essentially 100% of the circumference of the through gap, bonded in such a way that the adhesive element extends beyond the edge of the through gap and / or the pressure opening area has an area larger than the cross-section of the through gap.

[0058] Based on this finding, the inventors realized that, using the degree of overlap, it is advantageously possible to adjust the load pressure at which the pressure opening area is not removed from the adhesive element when pressure acts from the outside, i.e. from the direction of the carrier layer, so that not only an advantageous anisotropy of the opening behavior can be achieved, but also a precise adjustment in both directions is possible. Particularly preferably and correspondingly in the method according to the invention, by means of at least a partial overhang of the pressure opening area beyond the end of the through-gap, the adhesive element is bonded in the pressure opening area in such a way that it can withstand the action of a predefined load pressure on the carrier layer, so that the adhesive element in the weakened area is not irreversibly destroyed and no through holes are formed in the adhesive element. Particularly preferred here in the method according to the invention is a predefined load pressure of 100 kPa or more, preferably 200 kPa or more, particularly preferably 300 kPa or more, particularly preferably 400 kPa or more.

[0059] In the above-mentioned advantageous embodiment with at least a partial overlap of the pressure opening area with the end of the gap, the inventors have observed the effect that the freest adjustment of the predetermined opening pressure can be limited while simultaneously adjusting the predetermined load pressure. In particular at high levels of overlap, which may be necessary to set high load pressures, at least when it is preferred to substantially cover the carrier layer with the adhesive layer, the adhesive interaction of the adhesive layer in the overlap area can contribute significantly to the required opening pressure, since in this case it is also necessary to overcome the adhesive interaction between the adhesive layer and the end of the gap in order to lift the pressure opening area. In this case, the predetermined opening pressure is therefore no longer essentially determined by the weakening of the carrier layer, but instead the pressure required for opening must also overcome the adhesive interaction of the adhesive layer with the substrate. In order to be able to realize even small predetermined opening pressures despite large predetermined load pressures, i.e. for example despite a high resistance to external load factors, the solution proposed by the inventors is to provide an additional cover element, which can be applied to the adhesive layer and whose dimensions correspond as flexibly as possible to the dimensions of the pressure opening area. In this case, the cover element reduces or prevents adhesive interaction between the adhesive layer and the substrate in the region of the pressure opening area, so that the adhesive element is fixed on the substrate, for example, exclusively via adhesive interaction of the adhesive layer outside the pressure opening area. Under the action of pressure from the outside, i.e. from a surface remote from the adhesive layer, as a result of the overlap, the adhesive element shows resistance to undesired opening, which can be advantageously further increased by the additional structural integrity of the cover element, since it must first be deformed in order to break open. However, viewed from the other direction, the cover element prevents adhesive interaction between the relevant part of the adhesive layer and the edge of the substrate in the region that is lifted up during overpressure opening, thus making it possible to even establish a low predetermined opening pressure.Therefore, in the method of the present invention, it is particularly preferred that the adhesive element further comprises a cover element which is attached to the pressure opening area on the side of the adhesive layer remote from the carrier layer, the cover element preferably does not substantially overhang the pressure opening area and / or the dimensions of the cover element preferably substantially correspond to the dimensions of the pressure opening area, or the through gap is at least partially, preferably completely, covered with the cover element before the adhesive element is bonded, the dimensions of the cover element preferably substantially correspond to the dimensions of the pressure opening area, and the adhesive element is bonded such that the pressure opening area at least partially, preferably completely covers the cover element. Those skilled in the art will understand that in the method of the present invention, it is advantageous for the cover element to be adhesive-free. Instead, it is preferred in the method of the present invention that the cover element comprises a foil selected from the group consisting of polymer foils and metal foils.

[0060] The inventors have succeeded in defining suitable dimensions for the adhesive layer, the carrier layer and the cover element. In the method according to the invention, preferably, in practice, the adhesive layer has an average thickness in the range of 5 to 1500 μm, preferably in the range of 10 to 500 μm, particularly preferably in the range of 35 to 100 μm, and / or the carrier layer has an average thickness in the range of 30 to 2000 μm, preferably in the range of 40 to 1000 μm, particularly preferably in the range of 50 to 500 μm, and / or the cover element has an average thickness in the range of 5 to 340 μm, preferably in the range of 10 to 200 μm, particularly preferably in the range of 12 to 100 μm.

[0061] The skilled person will understand that the present invention also relates to an adhesive element that can be used in the method of the present invention and that allows obtaining the above-mentioned advantages. The present invention therefore also relates to an adhesive element for permanently sealing a through hole with overpressure protection, preferably in the method of the present invention, comprising: i) an adhesive layer comprising an adhesive; and ii) a carrier layer disposed on the adhesive layer and consisting of a first carrier layer; wherein the adhesive element comprises a pressure opening area at least partially surrounded by a weakened area formed in the carrier layer, the average thickness of the carrier layer in the weakened area being smaller than the average thickness of the carrier layer in the pressure opening area, The adhesive element is characterized in that the application of a predetermined opening pressure to the pressure opening area irreversibly destroys the adhesive element at least partially in the weakened area (22) and forms a through hole (24) in the adhesive element.

[0062] According to the inventor's assessment, it is not only the inventive method and the inventive adhesive element used therein that are advantageous; instead, the advantages are directly transferred to the substrates produced therewith, which, in particular due to the low specific weight and low specific volume of the inventive adhesive element, have advantageous overpressure protection and also reliably open at a predefined opening pressure, so that the overpressure-protected substrate is particularly suitable for a large number of applications, in particular in the field of electric vehicles, for example in the form of a battery housing. The invention also relates correspondingly to an overpressure-protected substrate, preferably producible by the inventive method, which comprises a fluid-tight interior with at least one fluid-tight opening, said sealed opening being fluid-tightly sealed with the inventive adhesive element, the pressure opening area of ​​said adhesive element at least partially covering said sealed opening, said overpressure-protected substrate being configured such that as a result of a predefined overpressure in its interior, the adhesive element is at least partially irreversibly destroyed in the weakened area, and the pressure in the interior can be relieved by the through-holes formed in the adhesive element.

[0063] Finally, the present invention also relates to the use of the adhesive element of the present invention for permanently sealing a hole on a substrate and generating overpressure protection, the hole being sealed with the adhesive element such that the pressure opening area at least partially covers the hole on the substrate.

[0064] Preferred embodiments of the invention will now be described in more detail with reference to the accompanying drawings, in which: [Brief description of the drawings]

[0065] [Figure 1] FIG. 1 is a first schematic exploded view showing the structure of the adhesive element of the present invention before application to a substrate in a preferred embodiment; [Diagram 2] FIG. 2 is a second schematic exploded view showing the structure of the adhesive element of the present invention before application to a substrate in a preferred embodiment; [Diagram 3] FIG. 3 is a schematic cross-sectional view through an adhesive element of the present invention in a preferred embodiment; [Figure 4] FIG. 4 is a schematic diagram showing the overpressure protection substrate of the present invention with its overpressure protection in a closed state; [Diagram 5] FIG. 5 is a schematic diagram showing the overpressure protection substrate of the present invention with the overpressure protection open.

[0066] FIG. 1 is a first schematic exploded view illustrating the structure of an adhesive element 14 of the present invention prior to application to a substrate 12 in a method of the present invention.

[0067] The adhesive element 14 of the present invention comprises an adhesive layer 16 through which the adhesive element can be attached to the substrate 12 and can fluid-tightly, and in particular gas-tightly, seal the through-hole 10 in the substrate 12. In the example shown in Figure 1, the substrate 12 is a metal battery housing, and only one wall of the battery housing defining its interior is shown.

[0068] In the illustrated embodiment, adhesive layer 16 comprises a poly(meth)acrylate-based pressure sensitive adhesive, which may also be synthetically foamed using, for example, expanded microballoons.

[0069] The adhesive layer 16 is arranged on a first carrier layer 19 of the multilayer carrier layer 18 and is connected via adhesive bonding. In the example shown in Fig. 1, as is evident from the exploded view, the first carrier layer 19 is substantially completely covered on one side by the adhesive layer 16. This becomes evident from the view in Fig. 2, which is a partial integration of the exploded view of Fig. 1, and in which the connection between the first carrier layer 19 and the adhesive layer 16 becomes clear.

[0070] 1 and 2, the first carrier layer 19 is a metal foil having an average thickness of about 80 μm. In addition to the first carrier layer 19, the carrier layer 18 comprises as a further layer a protective foil 26 of polyethylene terephthalate, which is connected to the first carrier layer 19 via an intermediate adhesive layer 30 which is also applied extensively.

[0071] 1 and 2 each show that the adhesive element 14 in the carrier layer 18 comprises a pressure opening area 20 formed by a weakened area 22. The pressure opening area 20 is here located in the center of the adhesive element 14 and is substantially circular in the example shown, so that in terms of basic shape it substantially corresponds to the through gap 10 of the substrate 12 to be sealed in the method of the invention.

[0072] As a result of this structure, the adhesive element 14 of the present invention is configured such that the action of a predetermined opening pressure on the pressure opening area 20, for example as a result of excess pressure prevailing inside the substrate 12, can result in at least partial irreversible destruction at the weakened area 22, thereby forming a through hole 24 in the adhesive element 14.

[0073] In the shown example, the weakened area 22 is formed as a groove-like void in the carrier layer 18, which extends through the protective foil 26 into the first carrier layer 19 and substantially completely surrounds the pressure opening area 20, with the average thickness of the carrier layer 18 in the area of ​​the weakened area 22 being reduced by approximately 20-60% depending on the desired opening pressure with respect to the original thickness of the carrier layer 18 and therefore also smaller with respect to its average thickness in the pressure opening area 20.

[0074] In FIG. 1, in the example shown, the adhesive layer 16 has a substantially constant average thickness, which in this case is evident from the direction of the carrier layer 18, due to the mechanical formation of the weakened areas 22 caused by the die-cutting, the adhesive layer 16 being unaffected by this die-cutting.

[0075] 1 and 2, in the method according to the invention, the adhesive element 14 according to the invention is automatically glued, for example by means of a robot arm, and in the illustrated embodiment the pressure opening area 20 and the through gap 10 are arranged concentrically. In order to achieve an advantageous anisotropy of the opening behavior, the gluing here is carried out in such a way that the pressure opening area 20 overhangs the end of the through gap 10 over the entire circumference thereof, so that the overlapping area can exhibit resistance to externally applied load pressures.

[0076] In order to allow precise adjustment of the desired opening pressure despite the overlap of the adhesive element 14 of the present invention with the ends of the through gap 10, the adhesive element 14 of the present invention comprises a cover element 28, which is made of a polymer foil, the dimensions of which substantially correspond to the dimensions of the pressure opening area 20 and which substantially completely covers the adhesive layer 16 in the pressure opening area 20.

[0077] Figure 3 visualizes the structure of the adhesive element 14 of the invention in a cross-section, the diagrammatically represented adhesive element 14 having a structure which in many respects corresponds to the adhesive element 14 of Figures 1 and 2. However, in Figure 3 it is shown that the processing of the carrier layer 18 for the purpose of generating the weakened areas 22 can also take place at least partially through the adhesive layer 16, whereby, advantageously as a result of the flow behavior of the adhesive layer 16, no traces of the processing, for example in the form of a reduced thickness, remain in this layer after a short time.

[0078] 4 now shows an overpressure protection substrate 12 of the invention, with a through gap 10 sealed fluid-tight by an adhesive element 14, for example as obtained from FIGS. 1 and 2. Due to the above-mentioned structure of the adhesive element 14 and its arrangement on the through gap 10, the overpressure protection substrate 12 can be designed to withstand a load pressure of 400 kPa or more acting from the direction of the carrier layer 18, without destruction of the adhesive element 14 in the weakened area 22. In fact, the corresponding structure was even able to withstand, in the inventor's experiments, a blasting of the overpressure protection substrate 12 with a high-pressure water jet cleaner (IPX9K, ISO 20653:2013) without sealing failure (without the seal being destroyed).

[0079] At the same time, it is possible to target-wise establish a predefined opening pressure, for example in the range of 5-200 kPa, which, when acting in the desired opening direction, i.e. for example from the inside towards the outside of the battery housing, results in the pressure opening area 20 being lifted off the adhesive element 14 as a result of at least partial destruction of the weakened area 22, thereby forming a through hole 24 through which the overpressure can be released. The final state resulting from the intervention of the overpressure protection is diagrammatically visualized in FIG. 5. Here, a complete detachment of the pressure opening area 20 from the adhesive element 14 is additionally prevented by the fact that in an advantageous embodiment, the weakened area 22 is not formed over the entire circumference, so that an unweakened connection remains between the pressure opening area 20 and the remaining part of the adhesive element 14.

[0080] Reference symbol list 10. Through-hole 12 Substrate 14 Adhesive elements 16 Adhesive layer 18 Carrier Layer 19 First Carrier Layer 20 Pressure Opening Area 22 Areas of vulnerability 24 Through holes 26 Protective foil 28 Cover Elements 30 Intermediate adhesive layer Furthermore, the present invention includes the following items. [Item 1] A method for sealing a through void (10) in a substrate (12), comprising the steps of: a) manufacturing or providing an adhesive element (14) comprising: i) an adhesive layer (16) comprising an adhesive, and ii) a carrier layer (18) disposed on the adhesive layer (16) and comprising a first carrier layer (19); b) adhering the adhesive element (14) to the substrate (12) by means of an adhesive layer (16) such that the adhesive element (14) completely covers the through gap (10) and the through gap (10) is fluid-tight sealed by the adhesive element (14); Including, wherein the adhesive element (14) includes a pressure opening area (20) at least partially surrounded by a weakened area (22) formed in the carrier layer (18), wherein an average thickness of the carrier layer (18) in the weakened area (22) is less than an average thickness of the carrier layer (18) in the pressure opening area (20); wherein the adhesive element (14) is configured such that the application of a predetermined opening pressure to the pressure opening area (20) irreversibly breaks the adhesive element (14) at least partially in the weakened area (22) and forms a through hole (24) in the adhesive element (14), and wherein the adhesive element (14) is adhered such that the pressure opening area (20) at least partially covers the through void (10) in the substrate (12). [Item 2] 2. The method according to claim 1, wherein the weakened areas (22) are formed as groove-like voids in the carrier layer (18). [Item 3] 3. The method according to item 1 or 2, wherein the predetermined opening pressure is 10 kPa or more. [Item 4] 4. The method according to any one of items 1 to 3, wherein the carrier layer (18) comprises a protective foil (26) as a further carrier layer on the layer of the side of the first carrier layer (19) opposite the adhesive layer (16). [Item 5] 5. The method according to any one of items 1 to 4, wherein the adhesive element (14) further comprises a cover element (28) attached to the pressure opening area (20) on the side of the adhesive layer (16) opposite the carrier layer (18). [Item 6] 6. The method according to any of claims 1 to 5, wherein the bonding of the adhesive element (14) is effected by at least a partial overhang of the pressure opening area (20) beyond the edge of the through gap (10) in such a way that the bonded adhesive element (14) withstands the action of a predefined load pressure on the carrier layer (18) in the pressure opening area (20), so that the adhesive element (14) is not irreversibly destroyed in the weakened area (22) and no through holes (24) are formed in the adhesive element (14). [Item 7] 7. The method according to item 6, wherein the predetermined load pressure is 100 kPa or more. [Item 8] An adhesive element (14) for permanently sealing the through gap with overpressure protection, i) an adhesive layer (16) comprising an adhesive; and ii) a carrier layer (18) disposed on the adhesive layer (16) and including a first carrier layer (19); Including, wherein the adhesive element (14) includes a pressure opening area (20) at least partially surrounded by a weakened area (22) formed in the carrier layer (18), wherein an average thickness of the carrier layer (18) in the weakened area (22) is less than an average thickness of the carrier layer (18) in the pressure opening area (20); Here, the adhesive element (14) is configured such that the application of a predetermined opening pressure to the pressure opening area (20) irreversibly destroys the adhesive element (14) at least partially at the weakened area (22) and forms a through hole (24) in the adhesive element (14). [Item 9] An overpressure protection substrate (12) including a fluid-tight sealed interior having at least one fluid-tight sealed opening, wherein the sealed opening is fluid-tight sealed with an adhesive element (14) according to item 8, and a pressure opening area (20) of the adhesive element (14) at least partially covers the sealed opening, Here, the overpressure protection substrate (12) is configured such that, as a result of a predetermined internal overpressure, the adhesive element (14) is at least partially irreversibly destroyed at the weakened area (22), thereby causing an internal pressure drop due to the through hole (24) formed in the adhesive element (14). [Item 10] 9. Use of the adhesive element according to item 8 for permanently sealing a through void in a substrate (12) and for generating overpressure protection, wherein the through void is sealed with the adhesive element (14) such that the pressure opening area (20) at least partially covers the through void in the substrate (12).

Claims

1. A method for sealing a through void (10) in a substrate (12), comprising the steps of: a) manufacturing or providing an adhesive element (14) comprising: i) an adhesive layer (16) comprising an adhesive, and ii) a carrier layer (18) disposed on the adhesive layer (16) and comprising a first carrier layer (19); b) adhering the adhesive element (14) to the substrate (12) by means of an adhesive layer (16) such that the adhesive element (14) completely covers the through gap (10) and the through gap (10) is fluid-tightly sealed by the adhesive element (14); Including, wherein the adhesive element (14) comprises a pressure opening area (20) at least partially surrounded by a weakened area (22) formed in the carrier layer (18), wherein an average thickness of the carrier layer (18) in the weakened area (22) is less than an average thickness of the carrier layer (18) in the pressure opening area (20); wherein the adhesive element (14) is configured such that the application of a predetermined opening pressure to the pressure opening area (20) irreversibly breaks the adhesive element (14) at least partially in the weakened area (22) and forms a through hole (24) in the adhesive element (14), and wherein the adhesive element (14) is adhered such that the pressure opening area (20) at least partially covers the through gap (10) in the substrate (12); The method, wherein the adhesive element (14) further comprises a cover element (28) attached to the pressure opening area (20) on the side of the adhesive layer (16) opposite the carrier layer (18).

2. 2. The method according to claim 1, wherein the weakened area (22) is formed as a groove-like void in the carrier layer (18).

3. 3. The method according to claim 1 or 2, wherein the predetermined opening pressure is 10 kPa or more.

4. 3. The method according to claim 1, wherein the carrier layer (18) comprises a protective foil (26) as a further carrier layer on the side of the first carrier layer (19) facing away from the adhesive layer (16).

5. 3. The method according to claim 1, wherein the bonding of the adhesive element (14) is effected by at least a partial overhang of the pressure opening area (20) beyond the edge of the through gap (10) in such a way that the bonded adhesive element (14) withstands the action of a predefined load pressure on the carrier layer (18) in the pressure opening area (20), so that the adhesive element (14) is not irreversibly destroyed in the weakened area (22) and no through holes (24) are formed in the adhesive element (14).

6. The method of claim 5 , wherein the predetermined load pressure is 100 kPa or more.

7. An adhesive element (14) for permanently sealing the through gap with overpressure protection, i) an adhesive layer (16) comprising an adhesive; and ii) a carrier layer (18) disposed on the adhesive layer (16) and comprising a first carrier layer (19); Including, wherein the adhesive element (14) comprises a pressure opening area (20) at least partially surrounded by a weakened area (22) formed in the carrier layer (18), wherein an average thickness of the carrier layer (18) in the weakened area (22) is less than an average thickness of the carrier layer (18) in the pressure opening area (20); wherein the adhesive element (14) is configured such that the application of a predetermined opening pressure to the pressure opening area (20) irreversibly breaks the adhesive element (14) at least partially in the weakened area (22) and forms a through hole (24) in the adhesive element (14); Here, the adhesive element (14) further comprises a cover element (28) attached to the pressure opening area (20) on the side of the adhesive layer (16) opposite the carrier layer (18).

8. An overpressure protection substrate (12) including a fluid-tight sealed interior having at least one fluid-tight sealed opening, wherein the sealed opening is sealed in a fluid-tight manner with an adhesive element (14) according to claim 7, the pressure opening area (20) of the adhesive element (14) at least partially covering the sealed opening, Here, the overpressure protection substrate (12) is configured such that, as a result of a predetermined internal overpressure, the adhesive element (14) is at least partially irreversibly destroyed at the weakened area (22), thereby causing an internal pressure drop due to the through hole (24) formed in the adhesive element (14).

9. 8. Use of an adhesive element according to claim 7 for permanently sealing a through void in a substrate (12) and for generating overpressure protection, wherein the through void is sealed with the adhesive element (14) such that the pressure opening area (20) at least partially covers the through void in the substrate (12).

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