Multilayer composite system with optional textile support having polyvinyl chloride polyurethane composite layer as loudspeaker membrane with large frequency width

Description

[0001] Currently, loudspeakers, such as those used in car interiors, are constructed with magnets, a coil, and a plastic, paper, or metal diaphragm within a designated chassis. Due to the dimensions of these conventional loudspeakers, a specific volume must be maintained within the installed enclosure.

[0002] For some time now, structure-borne sound transducers have also been used to generate sound. In these systems, a sound driver vibrates surfaces, usually plastic components, that serve as diaphragms, enabling them to function as loudspeaker diaphragms. A commercial audio system based on this principle is, for example, Ac2ated Sound® from Continental AG. German patent DE 102019210296 B4, for instance, discloses a device for sound generation in which the diaphragm consists at least in part of the vehicle's interior trim.

[0003] Such audio systems based on tactile transducers are significantly lighter and require considerably less installation space compared to conventional loudspeakers.

[0004] However, the frequency bandwidth of systems based on structure-borne sound transducers depends on the surfaces or plastic parts that are excited by the sound driver. Therefore, usually only high-frequency or low-frequency dominant designs can be achieved.

[0005] Ideally, the audio system should reproduce all frequencies in the audible range (approximately 20 Hz to 20 kHz) at roughly the same sound pressure level.

[0006] EP 2918629 A1 describes methods for producing breathable films from polyvinyl chloride-polyurethane composites and artificial leather containing these breathable films.

[0007] The object of the present invention is to provide a material, in particular a surface material, as a membrane for a structure-borne sound transducer, which exhibits improved broadband properties in the audible range. In particular, the sound response of low, mid and high frequency ranges should be reproduced as homogeneously as possible.

[0008] It was found that this task could be accomplished by using a synthetic leather as a membrane, comprising at least one breathable layer of a polyvinyl chloride-polyurethane composite material. The composite material has a porous structure, which makes the layer breathable.

[0009] The invention thus relates to an audio system comprising at least one structure-borne sound transducer and an artificial leather serving as a membrane, wherein the artificial leather comprises at least one breathable layer made of a polyvinyl chloride-polyurethane composite material.

[0010] Surprisingly, this audio system demonstrated excellent broadband characteristics. In particular, the sound response across low, mid, and high frequencies was reproduced relatively homogeneously. The deviations in the measured sound pressure level across the high, mid, and low frequencies are acceptable for good sound quality throughout the entire audible range. In comparison, conventional surface materials could only cover either the high or low frequencies. It was found that the actuator with PVC film and PVC-coated synthetic leather membranes could only cover low frequencies, while those with polyurethane-coated synthetic leather and films could only cover high frequencies. Similarly, perforated PVC or polyurethane-based materials failed to achieve the desired broadband characteristics. Both micro-perforations and standard perforations were investigated.

[0011] Advantages of the audio system according to the invention are: An improvement in sound transmission across a broad frequency range, covering both high and low frequencies, is achieved through the porous structure of the composite material. Compared to other films or leathers, the synthetic leather used according to the invention can offer high sound fidelity. The surface can be textured, dyed, and its softness and feel can be customized so that the audio system is visually concealed. The synthetic leather used according to the invention can also be directly excited by a sound driver such as an actuator. Breathable synthetic leathers, such as laif®< VyP, are protected against environmental influences such as abrasion, UV radiation, heat, and soiling, for example, with appropriate stabilizers and dirt-resistant lacquers. Laif®< VyP also allows for moisture and air exchange and can thus contribute to the user's health and well-being.

[0012] The invention is explained in detail below.

[0013] The audio system according to the invention comprises at least one structure-borne sound transducer and an artificial leather serving as a diaphragm. The audio system can include one or more structure-borne sound transducers. If only one structure-borne sound transducer is present, it can be positioned at a suitable location on the artificial leather. If two or more structure-borne sound transducers are present, they are positioned at different locations on the artificial leather. The artificial leather typically forms the surface material, the covering, or the covering material of a component. The at least one structure-borne sound transducer is then located behind or inside the component, so that it is not visible.

[0014] Structure-borne sound transducers are also known as exciters. A structure-borne sound transducer typically includes an actuator, also called an acoustic actuator or structure-borne sound actuator. The actuator can be electrodynamic or piezoelectric. It converts electrical signals into mechanical displacements, causing adjacent components to vibrate and produce sound.

[0015] It goes without saying that the body sound transducer has electrical connections through which it can be connected, for example, to an amplifier or audio amplifier, which provides the body sound transducer with audio signals for processing. The amplifier, in turn, is driven by at least one audio source, such as an infotainment system or a control unit for warning or assistance messages.

[0016] The synthetic leather, serving as a membrane, is connected to the structure-borne sound transducer directly or indirectly via one or more interposed components, so that the structure-borne sound generated by the transducer can be transmitted to the synthetic leather to produce sound. The frequency band generated by the structure-borne sound transducer can preferably cover the entire audible range, e.g., from approximately 20 Hz to approximately 20 kHz. However, it is also possible that only a sub-range is covered.

[0017] The at least one structure-borne sound transducer can be attached directly to the artificial leather. Alternatively, at least one component, preferably a planar component, can be arranged between the at least one structure-borne sound transducer and the artificial leather.

[0018] The component positioned between the structure-borne sound transducer and the synthetic leather can be, for example, a foam material (reticulated or standard), particularly a foam cover or backing foam, a plastic plate, or an actuator holder. Such a foam material can improve user comfort, for example, in headrests. Alternatively, non-woven fabric or spacer fabric can also be used as an intermediate component. However, these should ideally have high mechanical rigidity.

[0019] The structure-borne sound transducer can be attached to the installation surface, for example by gluing and / or fasteners such as screws, with the installation surface being formed by the artificial leather or the component in between.

[0020] In addition to the actuator, the structure-borne sound transducer may optionally include a sound-emitting plate connected to the actuator. Such a plate is not required but can be advantageous for design reasons. For example, it can prevent visible movement of the synthetic leather during sound reproduction. It may also be used to adjust the sound quality. The plate connected to the actuator can be made of plastic, metal, or wood, with a plastic plate being preferred.

[0021] In one embodiment, the actuator is attached directly to the synthetic leather. In another embodiment, the plate connected to the actuator is attached directly to the synthetic leather. In a further embodiment, at least one component, preferably a flat component, is arranged between the actuator or the synthetic leather. In a further embodiment, at least one component, preferably a flat component, is arranged between the plate connected to the actuator and the synthetic leather.

[0022] In one embodiment, the structure-borne sound transducer comprises a mounting element that serves to attach the sound-generating plate to the actuator and / or to attach the structure-borne sound transducer to the installation surface.

[0023] The audio system according to the invention further comprises the artificial leather serving as a membrane, which includes at least one breathable layer made of a polyvinyl chloride-polyurethane composite material. It may contain one or more such breathable layers.

[0024] The layer made of a polyvinyl chloride-polyurethane composite material is breathable due to its porous structure. Specifically, the polyvinyl chloride-polyurethane composite material has pores (channels) extending from one side of the layer to the other. Water vapor can pass through these pores, resulting in breathable properties. The pores preferably have an average diameter of 0.1 µm to 1 mm.

[0025] The breathable layer made of polyvinyl chloride-polyurethane composite material is a composite with PVC phases and polyurethane phases, each of which can exist as microscopic and / or macroscopic areas.

[0026] The at least one breathable layer of polyvinyl chloride-polyurethane composite material preferably has a gas permeability of 0.1 to 200 dm⁻² < min⁻¹. The at least one breathable layer of polyvinyl chloride-polyurethane composite material preferably has a water vapor permeability of 0.1 to 200 mg cm⁻² < h⁻¹. The breathable layer of polyvinyl chloride-polyurethane composite material can have a water impermeability of 0.1 to 60 m² < pa⁻¹ < w⁻¹. The gas permeability can be determined in accordance with DIN 53887. The water vapor permeability can be determined in accordance with DIN ISO 14268.

[0027] Due to the in-situ generation of pores during the process, the pores are statistically arranged in the material both horizontally and vertically. It is evident that pores or channels in the polyvinyl chloride-polyurethane composite material are statistically distributed, including with regard to small and large pores. The pores and channels can preferentially be statistically oriented in all directions (horizontally and vertically) and thus interact.

[0028] The at least one breathable layer of polyvinyl chloride-polyurethane composite material preferably contains 98 to 40 wt.% polyvinyl chloride and 2 to 60 wt.% polyurethane, based on the total weight of polyvinyl chloride and polyurethane in the layer.

[0029] The at least one breathable layer of polyvinyl chloride-polyurethane composite material may further contain excipients and additives, e.g., one or more thermoplastic polyurethanes (TPU), but it may also consist solely of polyvinyl chloride and polyurethane. The amounts of excipients and additives can vary widely depending on requirements and desired properties and are therefore not subject to any general limitations. Generally, it is preferred that the polyvinyl chloride-polyurethane composite material has a total amount of polyvinyl chloride and polyurethane, based on the total weight of the breathable layer of polyvinyl chloride-polyurethane composite material, of 25 to 100 wt.%, preferably 35 to 90 wt.%. Excipients and additives usually constitute the remainder.

[0030] The polyvinyl chloride (PVC) of the polyvinyl chloride-polyurethane composite material preferably comprises emulsion PVC with a K-value of 65 to 80, more preferably 70 to 76, suspension PVC, or mixtures thereof, or is selected from these. The suspension PVC is preferably pasteable suspension PVC, including commercially available microsuspension PVC.

[0031] The polyurethane of the polyvinyl chloride polyurethane composite material preferably comprises polyether polyurethane, polyester polyurethane or polycarbonate polyurethane or mixtures thereof, or is selected from these.

[0032] The auxiliary and additive materials can include, for example, fillers, plasticizers, crosslinkers, stabilizers, kickers, silicones, thermoplastic polyurethanes (TPU), flame retardants, additives, and / or colorants and pigments. It is understood that added auxiliary and additive materials, such as crosslinkers, which can be included in the initial mixture, may undergo reactions during the production of the breathable layer and then be present in a modified form.

[0033] An example of suitable auxiliary and additive materials are one or more thermoplastic polyurethanes (TPU). This polyurethane component can be obtained, for example, by cryogenic milling processes and preferably has a particle size of less than 100 µm, preferably less than 80 µm. The TPU types can be polyester polyurethanes, polycarbonate polyurethanes, polyether polyurethanes, or mixtures thereof.

[0034] The thermoplastic polyurethane can be aliphatic TPU and / or aromatic TPU. With regard to thermal and yellowing aspects, aliphatic TPUs are preferred, as they exhibit a lower tendency to yellow.

[0035] Examples of suitable fillers include calcium carbonate, cellulose (especially Arbocel types), calcium sulfate, barium sulfate, silicon dioxide (such as TS 100), aluminum hydroxide, aluminum oxide, zinc oxide, and zinc bromide. Examples of pigments include organic or inorganic pigments, metallic pigments, and iriodines.

[0036] The selection of plasticizers, if any, used, as well as that of fillers, is not subject to any general restrictions. Examples of suitable plasticizers include phthalates, adipates, sebacates, citrates, 1,2-cyclohexanedicarboxylic acid diisononyl esters, non-aromatic cyclic ester compounds such as DINCH, dioctyl terephthalate (DOTP), epoxy plasticizers such as epoxidized soybean oil, oligoglycol- or polyethylene glycol-based plasticizers, castor oil-based plasticizers, polymer plasticizers, phosphate plasticizers, chlorinated and brominated plasticizers, sulfate plasticizers, and ionic liquids.

[0037] Examples of suitable crosslinking agents are isocyanates, aceridines, carbidiimides, melamines and peroxides.

[0038] Examples of stabilizers / kickers include those based on barium, calcium, cadmium, tin, lead, mercury, antimony, arsenic, thiols or mercaptans, phosphites or phosphates, OBS, zinc, magnesium and / or aluminum, as well as sterically hindered and unhindered phenols (e.g., Irganox types), UV stabilizers, especially HALS, nano-titanium oxides, β-diketones, epoxy-based, perchlorate-based stabilizers and / or amine-based stabilizers.

[0039] Examples of flame retardants include antimony oxide, aluminum oxide, hydrotalcite, magnesium hydroxide, magnesium carbonate, calcium carbonate, zinc borate, various phosphates such as ammonium phosphate, expandable graphites, and brominated and chlorinated plasticizers.

[0040] Examples of silicones include crosslinked, crosslinking and / or non-crosslinked silicones, such as platinum-catalyzed crosslinking silicones or condensation reaction-based crosslinking silicones.

[0041] Examples of suitable additives include emulsifiers and soaps, defoamers, rheological additives such as thickeners and viscosity reducers, nanotubes and quantum dots.

[0042] The at least one breathable layer of polyvinyl chloride-polyurethane composite material can, for example, have a basis weight in the range of 10 to 2000 g / m², preferably 50 to 1000 g / m², more preferably 120 to 500 g / m².

[0043] In a preferred embodiment, the at least one breathable layer of polyvinyl chloride-polyurethane composite material is obtainable by a method comprising a) Applying a pasty mass comprising polyvinyl chloride and polyurethane to a substrate and b) drying and gelling of the pasty mass, forming a breathable film of the polyvinyl chloride-polyurethane composite material.

[0044] To prepare the paste-like mass, PVC, polyurethane, and optionally one or more auxiliary and additive materials can be blended, dispersed, and / or mixed together as described above. PVC can be added, for example, in the form of a PVC paste. An aqueous polyurethane dispersion is suitable for the polyurethane. Water can be added to the paste as needed.

[0045] Water, e.g., from the polyurethane dispersion or added separately, can be used to adjust the viscosity of the pasty mass. This aqueous component positively influences pore formation during the drying of the pasty mass into a breathable film.

[0046] The pasty mass is dried on the substrate simply by applying heat, possibly reacted, and gelled. During this process, the film forms, and the pores responsible for the film's breathable properties are also formed in situ during film formation.

[0047] The spontaneous or self-organizing pore formation during the drying and gelling of the pasty mass under heat application results from the fact that the pasty mass is composed of chemically incompatible fractions, namely PVC and polyurethane. Furthermore, the polyurethane exhibits very low to virtually no wettability in the pasty mass. During drying and gelling, cracks and / or cavities form at the respective phase or grain boundaries of these incompatible fractions. These cracks and / or cavities extend from one surface of the film to the other, thus forming pores within the film. The size of these pores can be influenced and adjusted by appropriate settings of the process components and process control.

[0048] The pore size and the resulting breathability can be adjusted within wide limits, for example, by influencing formulation parameters of the pasty mass, such as viscosity, filler type and content, type of PVC used, type and content of plasticizer, type of polyurethane used, and the proportion of polyurethane.

[0049] The process makes it possible to produce a breathable film that is solvent-free except for water, since according to the invention the pasty mass can be formed without the addition of an organic solvent.

[0050] It is possible to produce a breathable film with a compact, i.e., non-foamed, structure, or with a foam structure. For the latter, additional blowing agents are added, such as physical blowing agents (e.g., Expancell) or chemical blowing agents (e.g., OBSH or azodicarbonamide). The compact film exhibits the aforementioned pore structure. The foam structure can be created by producing a whipped foam from the pasty mass before applying it to the substrate. Alternatively, blowing agents such as azodicarbonamide, microspheres such as Expancell, silica gel, sodium carbonate, disodium carbonate, OBSH, zeolites, and the like can be added to the pasty mass as auxiliary or additives. These form the foam's cell structure upon drying and gelling.

[0051] The paste-like material can be applied to the substrate using, for example, a reverse or roll coater, or by squeegeeing, spraying, pouring, or printing. The application can be repeated once or several times, provided that a drying step was performed after the previous layer. If the synthetic leather contains more than one breathable layer of polyvinyl chloride-polyurethane composite material, the layers can also be produced independently and then laminated together.

[0052] The drying and gelling of the pasty mass into a porous film preferably takes place at temperatures of 100°C to 220°C.

[0053] In a preferred embodiment, the pasty mass, after being applied to the substrate, is passed together with the substrate through a drying oven or hardening oven, which can have a length of 1 to 80 m and a speed of 2 to 80 m / min to ensure a sufficient drying time.

[0054] The backing can be removed from the film once it has formed. The backing can be, for example, unembossed or embossed paper, a shaping polymer / plastic mold, a suitable tape, or a steel die.

[0055] It is also possible to use a substrate as a base, which remains attached to it after the film has formed, in particular a textile carrier within a composite material for the production of artificial leather. The applied paste-like mass can, for example, be applied directly to the textile carrier by means of direct coating and subjected to heat input together with it, whereupon the paste-like mass dries and gels on the textile carrier or another suitable substrate, forming the layer of the breathable film and remaining bonded to the substrate, thus forming a multilayer composite.

[0056] The synthetic leather used in the audio system according to the invention can further comprise a single or multi-layer lacquer coating as a top layer. The lacquer coating can consist of one or more identical or different lacquer layers, which may have different functions. The lacquer coating is arranged over the at least one breathable layer of a polyvinyl chloride-polyurethane composite material; that is, it is located on the visible side of the synthetic leather when it is in use.

[0057] In addition to providing general protection, the lacquer layer can impart various properties to the synthetic leather, such as feel and gloss (via a single lacquer layer or the topmost lacquer layer), abrasion resistance, color (using pigments in the lacquer layer(s)), and / or adhesion to the composite material (via a single lacquer layer or the bottommost lacquer layer). Examples of suitable lacquers for the lacquer layer(s) include those based on polyurethane, acrylate, PVC, PVDF, aniline, epoxy, or polyamide-polyester.

[0058] The synthetic leather used in the audio system according to the invention can further comprise at least one carrier. The at least one carrier is preferably a textile carrier. For example, one or more textile carriers can be laminated into the synthetic leather, as described above.

[0059] Examples of textile substrates include woven fabrics, nonwovens, and meshes. The fibers used for the textile substrate can be organic or inorganic, such as polyester, rock wool, glass, and carbon fibers.

[0060] The synthetic leather used in the audio system according to the invention may optionally further comprise at least one foam layer, e.g., acoustic foam, although this is generally not preferred. The foam layer or acoustic foam can usually be laminated into the synthetic leather.

[0061] Furthermore, by applying suitable methods such as steel stamping, vacuum stamping, silicone cloth roller stamping and the like, the artificial leather can have an introduced surface embossing in the form of a leather grain structure on its visible side.

[0062] The synthetic leather of the audio system according to the invention may, in addition to at least one breathable layer of polyvinyl chloride-polyurethane composite material, optionally contain a lacquer layer as a top layer, one or more textile carriers, and / or foams. It is preferred that the synthetic leather otherwise contains no further layers, e.g., plastic layers made of a material other than the PVC-PUR composite.

[0063] Suitable breathable layers and films made of polyvinyl chloride-polyurethane composite material and synthetic leather, as well as methods for their production, are also described in EP 2918629 A1. A synthetic leather suitable for the audio system according to the invention, as described above, is commercially available under the brand name laif®< VyP from ContiTech AG.

[0064] The audio system according to the invention can be a component in the transport sector, particularly in the automotive sector, in interiors, e.g., furniture, mobility systems such as trains, airplanes or boats, or in industry (LivTec), particularly as a decorative covering material. The audio system according to the invention is particularly preferably a component of a motor vehicle, especially in the interior of a motor vehicle or automobile.

[0065] The artificial leather of the audio system according to the invention can be, for example, a covering material or an interior lining of a component, in particular a component of a motor vehicle or automobile, wherein the component is preferably a headrest, a dashboard, a seat, a door, a vehicle pillar, a center console or a headliner.

[0066] The artificial leather of the audio system according to the invention can, for example, also be a covering material or an interior lining of a component in the industrial sector (Livtec), e.g. furniture, chairs, wall coverings, ceiling coverings, cabinets, bed tops, e.g. in ships, airplanes, trains or buses.

[0067] For example, audio systems (speakers) according to the invention can be integrated directly into the seat surface of an armchair, car seat, or headrest. The synthetic leather conceals the audio system and is not visible (shy-tech) to the user. This eliminates the need for additional space, e.g., in the doors. Furthermore, this close proximity to the body also results in greater precision.

[0068] The invention also relates to a motor vehicle which has one or more audio systems according to the invention as described above.

[0069] The invention also relates to the use of an artificial leather comprising at least one breathable layer of a polyvinyl chloride-polyurethane composite material as a membrane for a structure-borne sound transducer. The use according to the invention is preferably implemented in an audio system according to the invention as described above.

[0070] All the above information regarding the synthetic leather, the breathable layer made of a polyvinyl chloride polyurethane composite material and the structure-borne sound transducer applies accordingly to the use, so reference is made to it.

[0071] The invention is explained in more detail below with reference to exemplary embodiments shown in the drawings. These show: Fig. 1a A partial view of a breathable layer made of a polyvinyl chloride-polyurethane composite material on a textile substrate for the artificial leather of the audio system according to the invention. Fig. 1b A partial view of another breathable layer made of a polyvinyl chloride-polyurethane composite material on a textile substrate for the artificial leather of the audio system according to the invention. Fig. 2 A graph showing the dependence of the sound pressure on the frequency in the audible range for an audio system according to the invention compared to conventional films or artificial leathers used as membranes. Fig. 3 Cross-sectional view of an audio system according to the invention, installed in the headrest of an automobile. Fig. 4 Exploded view of the audio system according to the invention. Fig. 3 Fig. 5 Schematic of a process flow for the production of a breathable film from a polyvinyl chloride-polyurethane composite material.

[0072] The Fig. 1a and 1b Each figure shows a partial illustration of a breathable layer of a polyvinyl chloride-polyurethane composite material on a textile substrate for the artificial leather of the audio system according to the invention, which is obtained according to the described method. The black areas represent the pores, while the whitish areas represent the composite. The textile substrate is visible in the lower area.

[0073] The following formulation can be used to produce a breathable layer from a polyvinyl chloride-polyurethane composite material: component Weighted parts PVC 100 Plasticizers 80 PU dispersion* 40 TPU 15 stabilizer 4 filler 20 pigment 10 *25-65 wt.% solids content

[0074] Commercially available aqueous polyurethane dispersions can be used as the polyurethane dispersion (PU dispersion). TPU and PVC are used in powder form. The components are mixed to a paste-like mass, applied to a substrate, and then dried and gelled to form a breathable film of polyvinyl chloride-polyurethane composite material. A textile carrier can then be attached to the resulting composite material, and the substrate is removed.

[0075] The composite material according to Fig. 1It comprises polyurethane and PVC and generates self-organizing, in-situ pores during the coating and drying / gelling process, which are statistically distributed throughout the layer. This distribution of pores allows sound waves to be refracted and scattered at the polymer-air interface, particularly when the pores and channels are statistically oriented in all directions and can thus interact.

[0076] Fig. 5 Figure 13 schematically shows an example of a process flow for the production of the breathable film or breathable layer from the polyvinyl chloride-polyurethane composite material.

[0077] A PVC plastisol 6, which can be produced from PVC powder and plasticizer, and an aqueous polyurethane dispersion 7 are mixed to form a polymer paste 8, with the addition of auxiliary agents and additives as required. The polymer paste 8 is applied to a release paper conveyed by rollers using a doctor blade 10 and conveyed with the release paper through a curing oven 11, in which the polymer paste is dried and gelled, for example, at a temperature in the range of 100 °C to 220 °C, and cooled via a cooling drum 12 after exiting the oven. A breathable PVC-polyurethane composite film 13 with self-organized, statistically distributed pores is obtained.

[0078] Fig. 2 shows a graph demonstrating the dependence of sound pressure on frequency in the audible range for an audio system according to the invention in comparison to conventional films or artificial leather used as membranes.

[0079] The following synthetic leathers were used as membranes for the audio system (PUR = polyurethane): CEP 799_28: PUR synthetic leather (has no pore structure) (comparison) CEP 801_36: breathable synthetic leather with polyvinyl chloride-polyurethane composite material on a textile backing (Laif ®< Vyp) (according to the invention) CEP 803_45: Perforated PUR synthetic leather (comparison)

[0080] In the graph of Fig. 2 The positive properties are clearly evident. The curve of the artificial leather according to the invention (CEP 801_36) shows that this system exhibits the properties of closed artificial leather (CEP 799_28) up to approximately 250 Hz and the properties of perforated material (CEP 803_45) from approximately 5000 Hz.

[0081] Surprisingly, it was demonstrated that the artificial leather used as a membrane according to the invention exhibits excellent broadband properties. In particular, the sound response across both low and high frequencies was reproduced homogeneously.

[0082] The broadband properties of the artificial leather used according to the invention can, without wishing to commit to a theory, be explained at this time by the construction and design: 1) The statistical distribution of the pores allows for the reproduction of a broad frequency band based on a locally varying density distribution. 2) The use of polyurethane and PVC mixtures results in inherent density differences within the material, relative to the polymers. 3) The phase boundaries between air and polymer cause frequency-dependent sound to be refracted and scattered. Due to the statistical distribution of small and large pores and their orientation within the material, frequency cancellation is minimal. 4) The material's porosity allows for air exchange and the transmission of low-frequency sound.

[0083] Additionally, this synthetic leather ensures a feel and appearance equivalent to that of standard speaker grilles made of hard plastic or thin material.

[0084] The Fig. 3 and 4 show a cross-sectional view or an exploded view of an audio system according to the invention, installed in the headrest of an automobile.

[0085] The headrest is covered with a synthetic leather 1 with a breathable layer of polyvinyl chloride-polyurethane composite material. A foam cover 2 provides padding beneath the synthetic leather. The tactile transducer comprises an actuator 4, a plastic plate for sound radiation 3, and a mounting element 5. The plate 3 is included primarily for aesthetic reasons and is not essential for sound reproduction. The tactile transducer is located inside the headrest 4 and is attached to the foam cover 2 via the plastic plate 3. The actuator has electrical connections for connection to an amplifier (not shown).

[0086] By being integrated within a component such as a headrest, these sound transducers are no longer visible, without any loss of sound quality or frequency range compared to conventional speakers. This actuator technology, combined with a cleanable, visually and haptically adaptable, soft synthetic leather as a diaphragm and sound source, represents a further step into the shy-tech world. The end user no longer recognizes the built-in speaker. Reference symbol list

[0087] 1 Artificial leather comprising at least one breathable layer of a polyvinyl chloride-polyurethane composite material 2 Foam cover 3 Sound-radiating plate 4 Actuator 5 Mounting element 6 PVC plastisol 7 Polyurethane dispersion 8 Paste-like mass or polymer paste 9 Release paper 10 Squeegee 11 Curing oven 12 Cooling drum 13 Breathable polyvinyl chloride-polyurethane composite film with self-organized, statistically distributed pores

Claims

1. Audio system, comprising at least one structure-borne sound transducer and an artificial leather serving as a membrane, wherein the artificial leather comprises at least one breathable layer of a polyvinyl chloride-polyurethane composite material.

2. An audio system according to claim 1, wherein at least one structure-borne sound transducer is attached directly to the artificial leather or between which at least one structure-borne sound transducer and the artificial leather at least one component, preferably a flat component, is arranged.

3. An audio system according to claim 2, wherein at least one component is a foam, preferably a foam cover or laminating foam, a plastic sheet or an actuator holder.

4. An audio system according to any of the preceding claims, wherein the structure-borne sound transducer comprises an actuator or actuator and a plate for sound radiation connected to the actuator, wherein the plate is preferably made of plastic, metal or wood, wherein a plastic plate is particularly preferred.

5. An audio system according to any of the preceding claims, wherein the artificial leather comprises a single or more layer of lacquer as a top layer and / or wherein the artificial leather comprises at least one support, preferably at least one textile support.

6. An audio system according to any of the preceding claims, wherein the audio system is part of a component of a motor vehicle, the artificial leather being a cover material or an interior trim of the component, the component being preferably a headrest, a dashboard, a seat, a door, a vehicle pillar, a center console or a headliner, or where the audio system is part of a component from the industrial sector, where the component is preferably a piece of furniture, a chair, a wall covering, a ceiling covering, a wardrobe or a bed top, e.g.in ships, planes, trains or buses.

7. An audio system according to any of the preceding claims, wherein at least one breathable layer of polyvinyl chloride-polyurethane composite material has pores running from one side to the other of the layer and / or pores with an average pore diameter of 0.1 µm to 1 mm.

8. An audio system according to any of the preceding claims, wherein the at least one breathable layer of polyvinyl chloride-polyurethane composite material has a gas permeability of 0.1 to 200 I dm-2 min-1 and / or a water vapor permeability of 0.1 to 200 mg cm-2 h-1.

9. An audio system according to any one of the preceding claims, wherein at least one breathable layer of polyvinyl chloride-polyurethane composite material contains 98 to 40% polyvinyl chloride by weight and 2 to 60% polyurethane by weight of the total weight of polyvinyl chloride and polyurethane in the layer.

10. An audio system according to any of the preceding claims, wherein the polyvinyl chloride of the polyvinyl chloride-polyurethane composite material comprises emulsion PVC with a K-value of 65 to 80, suspension PVC or mixtures thereof, and / or the polyurethane of the polyvinyl chloride-polyurethane composite material includes polyether polyurethane, polyester polyurethane or polycarbonate polyurethane or mixtures thereof.

11. An audio system according to any of the preceding claims, wherein at least one breathable layer of polyvinyl chloride-polyurethane composite material is obtained by a process comprising a) Application of a paste-like mass, including polyvinyl chloride and polyurethane, to a substrate and b) Drying and gelling of the paste-like mass to form a breathable film of polyvinyl chloride-polyurethane composite material.

12. An audio system according to claim 11, wherein the drying and gelling of the pasty mass is carried out at temperatures in the range of 100 °C to 220 °C.

13. A motor vehicle having one or more audio systems according to any one of claims 1 to 12.

14. Use of a synthetic leather, comprising at least one breathable layer of a polyvinyl chloride-polyurethane composite material, as a membrane for a structure-borne sound transducer.