Combination of an adhesive tape and a substrate that can be bonded to it

Abstract

Combination of an adhesive tape (1) and a substrate (2, 3) connectable thereto in connection with a flame-retardant equipment of the overall structure (1; 2, 3) realized in this way, preferably as a component of a motor vehicle and in particular an electric or hybrid motor vehicle, wherein the adhesive tape (1) is equipped with a flame-resistant carrier (1a) and the carrier (1a) is equipped at least on one side with an adhesive coating (1b) made of an adhesive, and wherein the adhesive coating (1b) contains a halogen-free flame retardant based on a single organophosphorus compound with a melting point of more than 85 °C.

Description

[0001] The invention relates to the combination of an adhesive tape and a substrate connectable thereto in connection with a flame-retardant finish of the overall construction thus realized, preferably as a component of a motor vehicle and in particular an electric or hybrid motor vehicle.

[0002] Adhesive tapes as composite elements are typically used, for example and not limited to, to manufacture battery packs or modules for electric vehicles. They can also be used to bond interior trim components in or on motor vehicles to the associated vehicle body. The overall structures created in this way, consisting of the two coupled substrates and the adhesive tape as the composite element between the two substrates, are usually those that are or must be flame-retardant. For example, in the interiors of motor vehicles and ships, there is a problem in that the two coupled substrates are often flame-retardant or guarantee a certain level of fire protection, whereas the adhesive tape as the composite element is typically made from flammable and combustible polymer materials.This generally applies to pressure-sensitive adhesives as the adhesive coating of such adhesive tapes as well as to the carriers used in practice, which are or can be, for example, plastic film carriers.

[0003] For this purpose, the generic prior art according to WO 2024 / 184507 A1, which represents the starting point, proceeds by creating a special sprayable pressure-sensitive adhesive composition with improved flame-retardant properties. For this purpose, a flame retardant is described in conjunction with a pressure-sensitive adhesive composition, and a polyester film is typically used as the carrier. The known pressure-sensitive adhesive composition for use in spray applications utilizes, among other things, an organophosphorus flame retardant in the adhesive composition.

[0004] Electric or hybrid vehicles and the batteries used in them can experience what is known as spontaneous combustion. To prevent potential fires at this point or at least minimize their spread, the prior art, according to WO 2024 / 184 507 A1, which forms the starting point, uses flame retardants in the adhesive coating, although improvements are still possible in this area. Indeed, such flame retardants can generally reduce flammability through a number of mechanisms. For example, they can extinguish free radicals in the gas phase. Furthermore, flame retardants can react with chemical fragments of the burning material to initiate the formation of char and thus contain the fire. Flame retardants are also used to form barrier layers within the burning material.

[0005] While the well-known polyester film with its detailed pressure-sensitive adhesive composition has proven itself in principle, it still offers room for further improvement. The focus is on the adhesive composition itself, and unlike the substrate, the carrier used is not specified in more detail.

[0006] Suitable adhesive tapes described in the prior art, for example, according to DE 101 50 453 A1 of the applicant, also incorporate a flame retardant in or on the backing to provide a flame-resistant finish, at least for the backing. This is often necessary in the described applications to reduce or completely suppress flammability.

[0007] Accordingly, the invention is based on the technical problem of further developing such a combination in such a way that the flame-retardant effect and thus the fire protection are further improved compared to the prior art.

[0008] To solve this technical problem, the subject of the invention is the combination according to claim 1.

[0009] In fact, the procedure within the scope of the invention is that the adhesive tape is first equipped with a carrier that is usually halogen-free and flame-resistant. This halogen-free and flame-resistant carrier means one that does not contain halogen-containing flame retardants. While such halogenated flame retardants, such as polychlorinated biphenyls, are generally known and extremely effective in preventing the development of fire in combustible materials and, consequently, in the entire structure, many of these halogenated flame retardants are now considered hazardous substances and are therefore banned regionally, for example, in the European Union.

[0010] According to the invention, a substrate is used that is generally halogen-free yet flame-resistant. The substrate can generally be a film substrate. Film substrates such as those based on polyester film have proven particularly advantageous in this case. In this case, a suitable flame retardant can be incorporated or applied, for example, by washing the film. Adding the flame retardant to the extrudate for the film is also conceivable.

[0011] In addition, the flame retardant can also be incorporated as a comonomer into the respective plastic used to produce the film. In fact, thermoplastics such as PP (polypropylene), PE (polyethylene), and especially PET (polyethylene terephthalate) in the form of special polyester films or polyamide are primarily used for this purpose.

[0012] Of particular importance for the invention is the fact that the adhesive coating is equipped with the halogen-free flame retardant based on a single organophosphorus compound. This means that, in contrast to the prior art according to WO 2024 / 184507 A1, the invention does not employ a first and a second organophosphorus compound. Rather, it has proven entirely sufficient for the adhesive coating to be equipped with a single organophosphorus compound. This reduces the manufacturing effort and thus the costs.

[0013] Furthermore, the interpretation is furthermore such that the single organophosphorus compound in question, and thus the flame retardant as a whole, has a melting point of more than 85°C. The maximum limit is generally a melting point of less than 200°C, preferably less than 150°C, and in particular 125°C or less.

[0014] In addition, it has proven advantageous if the film carrier is designed as a metal foil carrier or contains one. In this case, an aluminum foil carrier, a copper foil carrier, etc., is used as the film carrier for the adhesive tape used according to the invention. In principle, other metals are also suitable for the realization of the metal foil, such as silver, platinum, tin, zinc, titanium, as well as metal oxides such as tin oxides, zinc oxides, magnesium oxides, etc. Of course, combinations in the sense of a laminate are also conceivable, for example, in which such a metal foil carrier is combined with a polyester film carrier in the sense of a laminate.

[0015] For example, a polyester film can be vapor-deposited with aluminum, thus forming a film carrier containing a metal foil carrier, namely the aluminum layer on the polyester film carrier. In all these cases, it can be expected that the carrier for the adhesive tape can be designed not only to be halogen-free but also to be flame-resistant without the need for additional flame retardants. This is ensured by the metal foil carrier itself, or by the metal coating in the laminate of the polyester film carrier and the aluminum layer in the example case. In either case, it can be expected that such a design will minimize the risk of fire / flame, particularly in the engine compartment of the vehicle.

[0016] Furthermore, the plastic material used, such as polyester or polyamide, is characterized by high aging resistance and resistance to chemicals and operating fluids such as oil, gasoline, antifreeze, etc. This also results in high abrasion resistance, which is particularly relevant in the engine compartment considered here and also for interior applications.

[0017] If a film carrier made of a thermoplastic, especially PET, is used, this film carrier is designed to be halogen-free and flame-resistant. Specifically, this means that the carrier, and especially the film carrier, meets the VTM-0 standard for classifying its fire behavior. The VTM-0 standard is a standard for characterizing the fire protection behavior of "very thin material" films. This includes plastic materials that are too thin to pass the usual standards for classifying the fire behavior of plastics.

[0018] In fact, the so-called UL 94V (Underwriters Laboratories) criteria catalog is usually used for such thicker plastics. The VTM test proceeds as follows: The burning time of a sample is measured in seconds after a first and second flame application. Furthermore, the total burning time is determined in seconds for ten flame applications. Furthermore, the so-called burning and afterglow times are determined in seconds after the second flame application, and it is examined whether burning droplets occur. The sample is then burned down to the retaining clip.

[0019] To be classified as a VTM-0 film, the following values ​​must be achieved: - Burning time after first and second flame application of less than 10 seconds; - Total burning time for ten flame applications less than 50 seconds; - Burning and afterglow times of less than 30 seconds; - no burning dripping and - no burning down to the retaining clip.

[0020] As an alternative to this test according to the VTM standard, the substrate, and especially the film substrate, can also be classified in terms of its fire behavior so that it is considered self-extinguishing SE according to the FMVSS 302 / DIN 75200 standard. This is a test in which the flammability of a specimen is determined in a clamped frame. The specimen is exposed to a defined 38 mm high flame for a duration of 15 seconds.

[0021] The self-extinguishing characteristic (SE) means that the flame extinguishes within a total measuring distance, which corresponds to a burning rate taking into account a burning distance of 0 mm with a burning time of 16 minutes, i.e. 0 mm / min applies to the burning rate.

[0022] As soon as a carrier or film carrier meets the criteria explained above, it is characterized as flame-resistant within the scope of the present invention. This also applies if not a film carrier but a textile carrier made of plastic fibers or plastic threads or a metal foil carrier is used.

[0023] In fact, according to a further advantageous embodiment, the carrier is a textile carrier made of, for example, plastic fibers or plastic threads. In this context, the textile carrier can be woven, nonwoven, knitted, etc.

[0024] In this case, staple fibers made of polyester and / or polyamide can advantageously be used, for example, in a nonwoven fabric. It is also conceivable to use filament yarns or threads made of polyester and / or polyamide, for example. Such textile carriers can be manufactured particularly easily and cost-effectively for use in wrapping cables in automobiles, and in particular in the engine compartment of automobiles. This is especially true given that they allow the production of adhesive tapes that meet all the requirements of standard LV 312-1 (October 2009). The adhesive tape according to the invention can thus generally be designed to be hand-tearable, which typically corresponds to a breaking force in the transverse direction of the adhesive tape according to DIN EN 14410 of less than 90 N / cm.

[0025] Furthermore, for the claimed use of the adhesive tape, a certain abrasion resistance is required, which, according to the aforementioned standard LV 312-1, is manifested in the fact that at least abrasion class C is achieved. This corresponds to an abrasion test described in the relevant standard, which corresponds to a minimum of 500 to 999 strokes until abrasion class C is reached. Furthermore, the adhesive tapes used according to the invention are typically characterized in the described use by an elongation at break between the original sample length and the length at the moment of tearing of less than 200% and in particular of less than 50%. In addition, the adhesive tape used or its carrier generally has a basis weight of 350 g / m 2 does not exceed.

[0026] Another important criterion to consider is that in this context, a certain temperature resistance of the adhesive tape as a whole is generally observed, which in this case corresponds to the so-called temperature class C according to LV 312, which is associated with a continuous service temperature of 125 °C. The lower limit for the continuous service temperature in connection with temperature class C is -40 °C.

[0027] In addition, the special chemical resistance of the carrier or the adhesive tape as a whole is important, because in the demanding application area, the combinations created with the adhesive tape can come into contact with aggressive liquids and yet must be resistant to ensure their long-term functionality. For this purpose, cables are wrapped with adhesive tape, bent into a U-shape, and immersed in the chemical to be tested, for example, lubricating grease. The test specimens are then stored in a heating cabinet for a period of usually 1,000 hours and subjected to a visual and voltage test, as described in detail in the aforementioned standard LV 312-1. In particular, a resistance of at least 240 hours for all chemicals that are relevant in this context and listed in the standard LV 312-1 in question is essential.These requirements are typically met by using polyester or polyamide in particular as starting materials for the carrier, whether as a film carrier or as a textile carrier.

[0028] In addition, the adhesive tape in question is subjected to a flame resistance test, whereby at this point, the adhesive tape meets at least fire class C according to LV 312-1 with burning rates well below 100 mm / min, and in most cases even less than 50 mm / min. In some cases, even fire class B (self-extinguishing) or even A (non-flammable) can be achieved and implemented. The adhesive tapes in question generally pass the aforementioned test without any problems, provided the previously specified VTM-O or SE standards as defined by FMVSS 302 / DIN 75200 are met for the carrier and, in addition, the adhesive coating is designed to meet the requirements.

[0029] For this purpose, the plastic fibers or, in the case of the textile carrier, plastic threads are treated with an incorporated and preferably coextruded flame retardant. A similar approach can also be undertaken and implemented if the carrier is a film carrier. This means that the flame retardant is introduced into the extruder together with, for example, polymer granules during the production of the plastic fibers or plastic threads or the film carrier and coextruded together with the polymer material in order to produce the plastic fibers and thus the plastic threads or the film. This results in a particularly effective and homogeneous mixing with the polymer material for the plastic fibers or plastic threads or the film carrier.

[0030] The flame retardant added to the polymer material to create the carrier can be incorporated in a grammage of approximately 0.5 wt.% to approximately 20 wt.% based on the total weight of the carrier. The corresponding mixture of the flame retardant and the polymer material is usually prepared before extrusion, or the flame retardant is added to the extrudate in the specified grammage. This can be either an inorganic or an organic flame retardant, as explained in more detail below. A mixture is also conceivable.

[0031] The flame retardant can also be present as a comonomer in the respective plastic, either as a plastic for the production of the film of the film carrier or as a plastic for the production of the plastic fibers or threads in the textile carrier. In this case, the flame retardant is essentially incorporated into the plastic. Comparable grammages for the flame retardant compared to the polymer material are observed, as previously described.

[0032] The flame retardant used for the carrier can generally be an inorganic one, for example, based on metal oxides, metal hydroxides, and clays. A flame retardant based on, for example, a phosphate, such as aluminum polyphosphate, is also conceivable. An organophosphorus compound can also be considered as a flame retardant.

[0033] The adhesive coating, like the carrier, is designed to be flame-retardant or flame-resistant. For this purpose, the adhesive coating contains a halogen-free flame retardant with a melting point of more than 85°C. Furthermore, it has proven particularly advantageous if the flame retardant for the adhesive coating, consisting of the pressure-sensitive adhesive, has a melting point of less than 125°C. This typically leads to the formation of carbon in the event of a fire, which can lead to the extinguishing of any flame.

[0034] The flame retardant is generally present in the adhesive coating or pressure-sensitive adhesive in a grammage of approximately 0.5 wt.% to 30 wt.% based on the total weight of the adhesive. Inorganic-based additives for the flame retardant can also be used at this point. For example, the additive may be based on metal oxides, metal hydroxides, and clays. In this context, it is conceivable that the flame retardant for the adhesive coating contains exclusively the single organophosphorus compound and the additive or additives in question.

[0035] The flame retardant for the adhesive coating based on the single organophosphorus compound is, for example, phosphanate or phosphinate. If both organic and inorganic flame retardants are used, the invention recommends that the inorganic flame retardant or additive be present in the mixture in a concentration of up to 10 wt.%, based on the total mass or weight of the adhesive coating. The remaining up to 20 wt.%, however, is taken up by the organic flame retardant or the single organophosphorus compound.

[0036] Phosphaphenanthrenes, phosphonamidates, phosphazenes, and especially cyclotriphosphazenes and phosphoric acid esters have proven particularly suitable as flame retardants. The adhesive itself may otherwise be based on acrylate and additionally contain an adhesive resin. Alternatively, an adhesive based on a styrene block copolymer is also conceivable and is covered according to the invention.

[0037] Such organic-based flame retardants are characterized by the fact that they make the adhesive coating, and thus the adhesive tape, flame-retardant. This corresponds to the fact that, when exposed to a test flame, the adhesive tape burns for no longer than 60 seconds after a total of five 15-second applications of the test flame, according to the UL 510 standard. The standard in question is a regulation established in the USA, originally used for testing plastics in electrical devices, but has now become established worldwide for classifying the flame retardancy and fire safety of plastics. The adhesive tape is exposed to a test flame and must burn for no longer than 60 seconds after five 15-second applications. The term UL stands for Underwriters Laboratories.In this context, the stricter and previously referred to standards SE in the sense of FMV SS 302 / DIN 75200 or VTM-0 are usually met.

[0038] A comparable approach is used within the framework of LV 312-1, where at most a low burning speed of well below 100 mm / min, corresponding to the fire class C achieved for the adhesive tape used according to the invention, is observed and in most cases even the material exposed to the flame (adhesive tape) extinguishes before the previously described 15 second duration has been reached.

[0039] As a result, the combination of an adhesive tape and a substrate that can be bonded to it is provided in connection with use in automobiles, which is characterized in that the adhesive tape is equipped with both a generally halogen-free and flame-resistant carrier and an adhesive coating made of a pressure-sensitive adhesive that contains a halogen-free flame retardant with a melting point of more than 85 °C and generally less than 125 °C. This typically achieves at least fire class C according to LV 312, or the adhesive tape is characterized in that a test flame according to the UL 510 standard causes the adhesive tape to burn for a duration of less than 15 seconds.

[0040] This makes the adhesive tape used ideal for the described applications, not only because it provides flame-resistant properties but also because it otherwise meets the requirements for the described application. This applies particularly to the achieved hand tearability and abrasion resistance. Therefore, it can be expected that the adhesive tape will provide effective protection and a reliable bond to the substrate during normal use, and is easy to process. If a textile carrier is used for this purpose, it can be assumed that not only the required chemical and flame resistance will be achieved, but also that noise-dampening effects will be observed.In this context, it has proven advantageous if the adhesive tape in question also exhibits and demonstrates at least medium noise reduction according to Class C according to LV 312-1. This minimizes any rattling noise during operation.

[0041] The invention is explained in more detail below with reference to a drawing which merely represents an exemplary embodiment; in the drawings: Fig. 1 the combination of an adhesive tape and a substrate connectable thereto in the form of a battery cell and the production of a corresponding battery module in this context in perspective, Fig. 2 a top view of the battery module after Fig. 1, Fig. 3 the alternative combination of the adhesive tape in conjunction with a sensor and in particular seat occupancy sensor and here the sensor in a single view and Fig. 4 shows a schematic sectional view of the seat occupancy sensor mounted on a seat of a motor vehicle using the adhesive tape described above.

[0042] The figures show the combination of an adhesive tape 1 and a substrate 2, 3 that can be connected to it. The substrate 2, 3 is, in the variant according to the Fig. 1 and Fig. 2 is a battery cell 2. In the substrate 3 in the alternative embodiment according to the Fig. 3 and Fig. 4, on the other hand, is a single one in the Fig. 3 shown seat occupancy sensor 3. Using the seat occupancy sensor 3, the occupancy of a vehicle shown schematically in the Fig. 4 shown in section by a person inside a motor vehicle. Fig. 1 and Fig. The battery module 5 shown in Figure 2, consisting of the individual battery cells 2 connected to one another, is located inside a motor vehicle, in particular an electric or hybrid motor vehicle.

[0043] In this case, it is particularly important, and according to the invention, that the combination in question of the adhesive tape 1 and the substrate 2, 3 connectable thereto, specifically the respective battery cell 2 or the seat occupancy sensor 3 in the example case, is designed to provide a flame-retardant finish to the overall structure 1; 2, 3 thus realized as a component of the motor vehicle (not shown in detail), and in particular an electric or hybrid motor vehicle. For this purpose, the adhesive tape 1 is designed to be double-sided adhesive within the scope of the exemplary embodiment and not restrictively, as can be seen from the enlarged detailed illustration in the Fig. 1. In fact, the adhesive tape 1 is not limited to a flame-resistant carrier 1a, which may also be halogen-free, on the one hand, and an adhesive coating 1b applied to at least one side, on the other. According to the exemplary embodiment, the adhesive coating 1b is applied to both sides of the carrier 1a arranged between them.

[0044] According to the invention, the adhesive coating 1b contains a halogen-free flame retardant based on a single organophosphorus compound with a melting point of more than 85 °C, the specific design of which has been described in detail in the preceding description.

[0045] It can be seen that in the context of the combination according to the Fig. 1 and Fig. 2 the adhesive tape 1, which in this context is double-sided adhesive, connects two battery cells 2 to each other, wherein several battery cells 2 are combined in this way to form the battery module 5. The battery module 5 is in turn protected in an enclosing frame 6, as can be additionally seen from the top view in the Fig. 2. Even with the variant according to the Fig. 3 and Fig.4, the double-sided adhesive tape 1 with special properties is used. In this context, the adhesive tape 1 ensures that the seat occupancy sensor 3 shown there is adhesively bonded to the vehicle seat 4. In both or all applications, this means that the adhesive tape 1, in conjunction with the substrate 2, 3 connectable thereto, is designed inside or as a component of the motor vehicle in question, so that the described flame-retardant finish of the overall structure 1; 2, 3 realized in this way is particularly important in order to prevent the spread of a fire as much as possible. This represents the key advantages. QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] WO 2024 / 184 507 A1 [0003, 0004, 0012] DE 101 50 453 A1

[0006] Cited non-patent literature

[0000] DIN EN 14410

[0024]

Claims

[1] Combination of an adhesive tape (1) and a substrate (2, 3) connectable thereto in connection with a flame-retardant finish of the overall structure (1; 2, 3) thus realized, preferably as a component of a motor vehicle and in particular an electric or hybrid motor vehicle, wherein the adhesive tape (1) is provided with a flame-resistant carrier (1a) and the carrier (1a) is provided on at least one side with an adhesive coating (1b) made of a pressure-sensitive adhesive, and wherein the adhesive coating (1b) contains a halogen-free flame retardant based on a single organophosphorus compound with a melting point of more than 85 °C. [2] Combination according to claim 1, characterized by that the flame retardant of the adhesive coating (1b) has a melting point of less than 200 °C, preferably less than 150 °C and in particular less than 125 °C. [3] Combination according to claim 1 or 2, characterized bythat the flame retardant is present in the adhesive coating (1b) in a grammage of approximately 0.5 wt.% to 30 wt.%, based on the total weight of the pressure-sensitive adhesive. [4] Combination according to one of claims 1 to 3, characterized by that the flame retardant of the adhesive coating (1b) additionally comprises an inorganic-based component, for example based on metal oxides, metal hydroxides or clays. [5] Combination according to one of claims 1 to 4, characterized by that the flame retardant of the adhesive coating (1b) is produced, for example, on the basis of phosphanates, phosphinates, phosphaphenanthrenes, phosphoramidates, phosphazenes (in particular cyclotriphosphazenes) and phosphoric acid esters. [6] Combination according to one of claims 1 to 5, characterized by that the carrier (1a) is designed as a film carrier. [7] Combination according to claim 6, characterized bythat the film carrier is made of a thermoplastic material such as PP, PE and in particular PET. [8] Combination according to claim 6 or 7, characterized by that the substrate (1a) complies with the VTM-0 standard for classifying its fire behaviour or is classified as self-extinguishing SE in accordance with the FMVSS 302 / DIN 25200 standard. [9] Combination according to one of claims 1 to 8, characterized by that the flame retardant for the carrier (1a) is a phosphate such as ammonium polyphosphate and / or a metal oxide such as titanium dioxide and / or an organophosphorus compound. [10] Combination according to one of claims 1 to 9, characterized by that the substrate (2, 3) is a component of a battery pack or battery module and in particular of a battery cell (2). [11] Combination according to one of claims 1 to 10, characterized bythat the substrate (2, 3) is an interior trim component or a sensor, in particular a seat occupancy sensor (3).

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