EP2732446B1 - Highly absorptive sound insulation component, in particular for the motor vehicle interior - Google Patents

Description

The invention relates to a highly absorptive sound insulation component and a method for its production. The invention relates in particular to the field of sound absorption, inter alia in the area of the front wall inside of motor vehicles with a highly absorptive sound insulation of low weight.

A low noise level in the vehicle interior contributes to a relaxed driving experience and thus to increased passive safety of a motor vehicle. The basic physical principles of absorption and insulation are known for reducing airborne noise. The coupling of the two systems is an optimal solution, which can differ for each application.

Suitable combinations of materials are used, for example, for vehicle carpets / floor cladding systems, front wall modules or in the headliner and make an essential contribution to reducing the background noise in the vehicle interior.

Components that provide insulation have a closed structure, i.e. no sound or air passage; they are most effective in a mass-spring configuration. Such a system includes not only a flexible heavy layer but also an elastic, soft absorptive lower layer. The elastic layer causes a partial vibration isolation of the individual elements and thus a reduction of the background noise. The isolation will determined by the mass of a heavy layer and the spring stiffness of an absorptive layer.

However, good sound absorption is not only required in vehicle construction. This is also important in aerospace engineering, in rail transport, in the manufacture of white goods or in house construction. A sound absorber for these purposes must be optimized in such a way that sound is absorbed in a certain frequency range, which varies depending on the application, by choosing suitable materials.

DE 203 20 102 U1 relates to a multi-layer, sound-absorbing lightweight component, in particular for motor vehicles.

What is claimed is a multilayer, sound-absorbing component, in particular for motor vehicles, with an air-permeable cover layer and at least one air-permeable fleece layer made of thermoplastic fibers, the cover layer being coupled to the fleece layer in a sound-permeable manner, characterized in that the fleece layer has a weight per unit area in the range from 500 to 1,500 g / m ^{2 has} a thickness in the range from 2 to 7 mm and is not or only partially connected to the cover layer with an area proportion of less than 20% of its surface facing the cover layer.

DE 102 51 327 A1 relates to a process for direct back-foaming of absorber systems. The subject matter of the document is a process for direct back-foaming of absorber systems, in which the absorber consists of a foam layer or fleece layer with a one- or two-sided cover layer, characterized in that one provides an absorber with a very low density on the mass side with a foam-resistant cover layer, positions the absorber in the foaming tool and builds up pressure in the absorber on the side facing away from the mass in the closed foaming tool before the foaming process is triggered.

DE 10 2007 020 832 A1 describes a lightweight, sound-insulating cladding for a body part of a motor vehicle and a method for its production.

In particular, a light sound-insulating cladding for a body part of a motor vehicle, in particular in the form of a light front wall cladding, comprising a sound absorber layer, an essentially airtight sound insulation layer directly connected to the sound absorber layer and an adjoining foam layer, the sound absorber layer being composed of a porous absorber, preferably a fiber fleece or foam is formed, which has an air permeability in the range of 150 to 2000 liters / m ² d at a test pressure of 100 Pa. The sound insulation layer consists of an integral, at least 0.5 mm thick skin layer of the foam layer and is firmly bonded to the porous absorber by foaming back the porous absorber, essentially without foam penetration. A method for producing such a covering is also described.

DE 100 44 761 A1 relates to a floor covering with a noise-reducing effect for the interior of means of transport. The floor covering is equipped on the passenger side with a textile or non-textile surface, this surface being acoustically coupled to a floor covering sub-layer consisting of fiber fleece and / or foamed plastic via at least one micro-perforated film.

DE 103 60 427 A1 relates to a sound-reducing surface element with improved properties in terms of sound insulation and sound absorption, which has a heavy layer, a light layer which form a mass-spring system, and a first fleece layer attached by needling to the side of the heavy layer opposite the light layer. The heavy layer has through-holes which are filled with the fleece material of the first fleece layer as a result of the needling process, so that a high level of structure-borne noise damping, ie a high loss factor, is ensured even over a long period of time.

DE 10 2007 036 952 A1 describes a sound insulation, in particular for the motor vehicle interior, consisting of a foam layer and a barrier layer (absorption fleece), which is characterized in that an optionally micro-perforated fleece layer, a micro-perforated film or a micro-perforated film fleece is located between the foam layer and the barrier layer over the whole or part of the surface.

DE 10 2006 027 230 A1 describes an acoustically and thermally effective insulation with a defined layer structure, in particular for internal combustion engines of motor vehicles.

In the prior art, sound absorbers made of fiber materials, which are used in bound form, for example as nonwovens, are known, in particular from the automotive sector. In addition to natural fibers, polymers, inorganic or metallic fibers are also used as fibers. So is in EP 1 182 087 A2 an absorber described which comprises cellulose fibers and an artificial resin. In EP 0 909 680 A1 polyester fibers are used as sound absorbers. The diameter of the fibers used, the thickness, and the air resistance determines the efficiency and the frequency range in which the sound is absorbed.

DE 20 2004 009 726 U1 comprises a sound-absorbing, self-supporting front wall cladding for motor vehicles to shield the passenger compartment from the engine compartment, with a sound absorber formed from at least partially compressed fleece material, which is characterized in that it is provided with a plastic frame which is formed by back injection molding or back pressing of the compressed fleece material and has at least one integrated fastening means. Instead of fibrous materials, the same or similar components are also known from foams, preferably PUR or melamine with different densities.

The structure described as spring mass is known from the literature with different materials for the heavy layer (PUR, PE / EVA, EPDM and general TPO-based heavy layers); which are deep-drawn, foamed, injection-molded, sprayed, fleece-backed or foamed back as a film.

A lightweight, sound-insulating cladding for a body part of a motor vehicle and a method for its production is shown in DE 10 2007 020 832 A1 described. The cladding, which is described in particular in the form of a light front wall cladding, comprises a sound absorber layer, a substantially airtight sound insulation layer directly connected to the sound absorber layer and an adjoining foam layer, the sound absorber layer being composed of a porous absorber, preferably one Fiber fleece or foam, is formed. The sound insulation layer consists of an integral, at least 0.5 mm thick skin layer of the foam layer and is firmly bonded to the porous absorber by foaming back the porous absorber, essentially without foam penetration.

A vehicle interior part made of plastic, which also has sound insulation, is made of DE 34 48 259 C2 known. The plastic inner part contains polyolefin and / or polystyrene, synthetic rubber and filler.

If a foam is used as a sound absorber, preformed components are also often produced here. The composition of these has been optimized so that they have the required frequency-related sound absorption for the corresponding position in the vehicle.

DE 20 2004 008 165 U1 describes a sound-insulating component made from a highly filled thermoplastic elastomer based on styrene. The sound-insulating component is particularly suitable for transmission tunnel and / or front wall cladding and also has fillers.

A multilayer absorber based on the acoustic spring-mass system is shown in DE 199 09 046 A1 described. The heavy layer serving as a mass is applied in situ to the porous soft layer serving as a spring in different layer thicknesses and / or with different surface weights per unit area, in particular sprayed on, sprayed on or applied via a slot nozzle.

DE 10 2004 054 646 A1 relates to a light, sound-insulating cladding for a body part of a motor vehicle, in particular in the form of an end wall cladding, and a method for producing such a cladding. The cladding has a foam-molded sound insulation layer made of polyurethane foam and a foam-molded sound-absorbing layer made of open-cell flexible polyurethane foam.

A sound insulation component, in particular for motor vehicles, with at least one sound-absorbing layer and at least one heavy layer directly connected to it in a materially bonded manner, as well as methods for its production are in DE 10 2005 056 840 B3 described. In a corresponding sound insulation component, the heavy layer is designed as a microporous spray skin in such a way that it has at least one air-permeable partial surface area and at least one air-impermeable partial surface area.

In DE 10 2004 037 767 A1 a sound insulator for a passenger compartment of a vehicle is described. In the case of a corresponding sound insulator, an air cushion made of a damping-active shell made of an elastic material is provided between a sound-emitting component and the interior, a sound-absorbing layer that is adapted to the shape of the component and acts as a spring-mass system, which is closed on the interior side with a heavy foil, which a first shell of the air cushion forms, and a second shell of the air cushion connected in a sealing manner to the heavy film and made of an elastic, preferably preformed film is provided, wherein there is an air cushion between the first and the second shell.

DE 103 24 257 B3 comprises a sound absorber, which consists of two interconnected thermoplastically and / or thermosettingly bonded textile fiber fleeces. The two textile fiber fleeces have different layer thicknesses and densities in order to improve sound absorption.

A special form of absorbers are open 2-layer absorbers in which the flow resistances and thus the impedance of the two layers differ.

In general, this is understood to mean the combination of two layers; known are fleece / fleece, fleece / foam and foam / foam with different air flow resistance. The acoustic performance is based on the balance between absorption and isolation, see for example DE 103 24 257 B3 ; EP 0 934 180 B2 ( WO 98/18657 ); WO 98/18656 ; U.S. 6,145,617 ; WO 99/44817

In the DE 197 54 107 C1 and the state of the art referred to here, the absorption behavior of micro-perforated components is examined. Here, layered baffle structures made of micro-perforated foils are examined, which, as compact absorbers, depend on a ceiling or a roof. The micro-perforated foils are suitable for very effectively absorbing sound waves from the room that strike one or both sides, vertically, obliquely or in a grazing manner, especially at higher frequencies.

Components for use in motor vehicles are known from the prior art which, in addition to one or two microperforated films with fibrous or foamy absorbers, lie behind a film or between the two films; as an example, reference is made to the following publications: DE 100 22 902 A1 , DE 10 2005 041 707 A1 , DE 296 23 602 U1 , DE 196 33 839 C2 , EP 0 751 044 B1 , EP 0 439 432 A1 , EP 1 062 124 B1 , WO 99/46147 , EP 1 188 547 A1 , DE 198 49 366 A1 , DE 199 32 175 A1 , DE 199 20 969 B4 , DE 199 20 969 A1 , EP 1 161 360 B1 , WO 00/68039 , DE 299 15 428 U1 , DE 299 15 429 U1

With the variant that is in DE 10 2007 036 952 A1 is explained, an additional layer of non-woven or film is applied between the foam and the non-woven. This increases the cost and weight of the component. The required installation space is also often not given here. Furthermore, this structure increases the manufacturing effort considerably.

Instead of a fleece layer, a sound absorber can also have a foam layer. This is for example in DE 100 22 902 A1 described. The cladding or shaped element for means of transport described here comprises at least one micro-perforated film absorber, at least one foam and / or fleece absorber and / or air gap at a spatial distance from a reverberant wall.

1. a.) Schaum - Schwerfolie, tiefgezogen
2. b.) Schaum - Schwerfolie, gepresst
3. c.) Schaum - thermoplastischer Kunststoff
4. d.) Schaum - Schwerfolie, formgeschäumter hochgefüllter PUR-Schaum (RIM)
5. e.) Schaum - Schwerfolie, gesprühter hochgefüllter PUR-Schaum (RIM)
6. f.) Schaum - Schwerfolie, Compounding Injection Moulding
7. g.) Schaum - Schwerfolie - Vlies, oft nur partiell appliziert (Schaum - allg. eine Masseschicht - Vlies)
   [sogenannter Feder-Masse-Absorber - Aufbau]
8. h.) Schaum, einlagig
9. i.) Schaum - Vlies, formgepresst
10. j.) Schaum - Schaum, Schnittschaum
11. k.) Vlies, einlagig
12. l.) Vlies - Vlies, verpresste Vliese [mehrschichtiges Vlies]
13. m.) Vlies - Vlies, Faser-Flock-Technologie [mehrlagige Vliesstruktur].

The following material structures are known for the end walls used today in the interior of the passenger compartment:

1. a.) Foam - heavy foil, deep-drawn
2. b.) Foam - heavy foil, pressed
3. c.) Foam - thermoplastic plastic
4. d.) Foam - heavy foil, foam molded, highly filled PUR foam (RIM)
5. e.) Foam - heavy foil, sprayed, highly filled PUR foam (RIM)
6. f.) Foam heavy film, compounding injection molding
7. g.) Foam - heavy foil - fleece, often only partially applied (foam - generally a mass layer - fleece)
   [so-called spring-mass absorber - structure]
8. h.) foam, single layer
9. i.) Foam fleece, compression molded
10. j.) Foam - foam, cut foam
11. k.) fleece, single layer
12. l.) Fleece - fleece, pressed fleece [multi-layer fleece]
13. m.) Fleece - fleece, fiber-flock technology [multi-layer fleece structure].

The disadvantages of the variants a.) - g.) Are mainly the high weight and the high costs as well as the lack of sound absorption. If the variants h.) - m.) Are back-foamed with foam, the foam forms a closed layer through penetration into the fleece (the needle punched fleece or the flocked fleece (HMP process)) or the cut foam, whereby the fleece / the cut foam loses a large part of its porosity. This restricts the acoustic permeability and thus the desired absorption. Since this closed layer is not concentrated in a thin area and thus no pronounced barrier layer (insulation) is created, this component does not have an optimal insulating effect. At the same time, further acoustic losses occur as a result of the fact that the part of the fleece / cut foam that is soaked with foam no longer has full absorption. With k.) [And l.)] The so-called "dual impedance" effect is then impaired or destroyed.

In particular, the contours of fleece variants, as well as PUR lightweight foam and melamine resin foam variants (produced using the form-press or form-press-pinch process) are not as precise as with a foam-molded foam. Even the "rib formation" towards the body can only be implemented precisely with molded foam with regard to the form fit.

In the case of the foam-fleece variants presented in the prior art, the fleeces are usually pressed hard, and a layer is formed in which the foam collapses in the fleece (150-800 g / m ² ). Both of these impair the absorption considerably.

The disadvantages of previous foam-backed front wall claddings are that sound absorption is limited to the top layer or a thin bottom layer, so that optimum sound absorption can only take place to a limited extent. Depending on the embodiment, the use of a heavy foil as a mass in a spring-mass system also has the additional disadvantage of the increased weight of the entire cladding structure.

It is therefore problematic in vehicles with little installation space to implement a highly absorptive sound insulation component, in particular a front wall insulation on the inside with a low weight, in the material structure foam-fleece.

The present invention therefore sets itself the task of providing a flow-open (acoustically open) material structure which, due to its high absorptive effect, is advantageous as a front wall cladding structure or other components, for example Wheel arch cladding can be used inside the rear or in motor vehicle interiors, which at the same time enables a significant weight reduction compared to the current state of the art.

The present invention achieves the aforementioned object in a first embodiment by means of a highly absorptive, flow-open sound insulation component for sound insulation in motor vehicles as a front wall cladding or wheelhouse cladding according to claim 1 and a method for producing such a sound insulation component according to claim 12.

Further embodiments can be found in the subclaims. This structure increases the thickness of the absorber in the area with larger installation space (improved absorption), while in areas with less installation space the absorber is more compressed (dual impedance effect). The back-foaming has a constant thickness and / or density, the changes in thickness of the component taking place as a result of construction space variations in the fleece 2.

The loss of insulation that occurs in the case of absorptive insulation with a low weight is compensated for or reduced as best as possible through an optimized thickness adjustment of the absorber through increased absorption.

The coordinated choice of the fleece layer 2 and the foam layer 3 allows largely defined acoustic effects to be set. In addition, the crush resistance and / or the flexural rigidity can be influenced in a targeted manner, taking into account the absorptive effect, which means that such a material structure can be used, for example, as a front wall cladding or wheelhouse cladding inside motor vehicles.

An optionally micro-perforated fleece 4, a micro-perforated film 4, a micro-perforated film fleece 4 or a perforated heavy layer 4 is placed in front of the fleece layer. This layer 4 preferably has a weight per unit area in the range from 20 to 200 g / m ² , in the case of the optionally micro-perforated nonwoven layer 4; 35 to 100 g / m 2 in the case of the micro-perforated film 4; if it is a micro-perforated film fleece 4, then this preferably has a weight per unit area in the range from 65 to 280 g / m ² . The perforated heavy foil 4 has in particular a weight per unit area of 0.8 to 3 kg / m ² . This embodiment is in the Fig. 2 shown.

The foam layer (3) located partially or at certain points on the nonwoven layer (2) can consist of synthetic, in particular polyurethanes (PUR), or natural polymers, in particular latex. If the foam layer (3) is a PUR, it expediently has a density in the range from 20 to 120 g / l, in particular in the range from 45 to 85 g / l. Although higher volume weights result in an increase in the insulation, they also result in an undesirable increase in the mass of the material structure according to the invention. If the density is too low, the resulting material structure no longer has sufficient stability (such as compressive, tread or flexural strength).

An optionally micro-perforated non-woven layer 4, a micro-perforated film 4, a micro-perforated film non-woven 4 or a perforated heavy-duty film 4 is also partially or punctually arranged between foam 3 and fleece 2. A good compromise between absorption and insulation can thus be achieved.

The optionally micro-perforated fleece layer 4 or the micro-perforated film fleece 4 of the material structure according to the invention can contain various synthetic or natural fibers, also in the form of a mixture of these. For example, polyester fibers, especially PET, polyamide fibers, especially nylon 6 or nylon 66, polyolefin fibers, especially PP or PE, acrylic fibers, natural fibers, especially raw cotton, flax, hemp, flax, coconut, kenaf, jute and / or sisal fibers, or mixtures of these, in particular shredded cotton fibers with synthetic content or PET / PA nonwovens, or copolymers of these can be used.

Cellulose (paper) nonwovens are also increasingly used according to the invention.

A demand-oriented absorption distribution is achieved in that the fleece 2 is strongly compressed in areas with little installation space (for foam); and there is little compression in areas with sufficient installation space (for foam). The foam thickness can be kept much more constant over the entire component.

According to the invention, the fleece 2 is preferably calendered on the foam side, so that there is no collapsing layer between foam 3 and fleece 2 that would impair absorption. The foam is coupled in an open-flow manner, so that the absorption capacity of the foam contributes to the overall absorption.

The essence of the invention lies in the different degree of compression of the fleece 2 over the component surface, the relatively constant foam thickness 3, as well as the calendering of the fleece on the foam side, and thus none (a partially very small) formation of an intermediate layer as a result of foam collapse in the fleece 2. This "couples" the foam system to the absorber fleece to improve the absorption.

What is essential in a preferred embodiment of the invention is, on the one hand, the high absorption and, on the other hand, the additional use of the micro-perforated film 4, etc. between foam and fleece, in the coordination / setting of absorption and insulation.

The low component weight should also be mentioned here as an essential advantage of the invention.

The sound insulation component 1 according to the invention is preferably characterized in that the absorption fleece 2 is a fleece with a weight per unit area in the range from 180 to 1800 g / m ² , in particular in the range from 220 to 1300 g / m ² . Higher basis weights lead to an undesirably high increase in the mass of the material structure, while lower weights lead to a reduction in its stability.

The absorbent fleece 2 can contain various synthetic or natural fibers, also in the form of a mixture of these. For example, polyester fibers, in particular PET, polyamide fibers, in particular nylon 6 or nylon 66, polyolefin fibers, in particular PP or PE, acrylic fibers, natural fibers, in particular raw cotton, hemp, flax, coconut, kenaf, jute and / or sisal fibers , or mixtures of these, in particular shredded cotton fibers with synthetic content or PET / PA nonwovens, or copolymers of these can be used.

Layer 2 can also contain so-called bicomponent fibers (BiCo fibers) with a mass fraction of 10 to 50%, in particular 15 to 40%.

In the Fig. 1 a corresponding structure of a sound insulation component 1 with the fleece layer 2 and the foam layer 3 is shown.

On the side of the nonwoven layer 2 facing away from the foam layer 3, i.e. on the side facing the passenger compartment, there can also be at least one further textile or non-textile, possibly also perforated layer 5, partially or fully made of plastic, rubber, metal as required , Leather, artificial leather, wood, cork, cellulose (paper) or cardboard. This embodiment is in the Fig. 2 included, in which this structure is also combined with the micro-perforated intermediate layer 4.

It is a performance-optimized system (acoustically optimized system), which has a dual impedance effect through more strongly compressed fleece in areas with little space and improved absorption through less compressed fleece in areas with high spaces.

If the fiber flock technology is used instead of the fleece board, there is still a weight advantage and better acoustic effectiveness.

Claims (13)

1. A highly absorbing open-flow sound insulation component for sound insulation in motor vehicles as bulkhead trim or wheelhouse trim (1) having a non-woven layer (2) and, in partial area or punctual contact therewith, a foam layer (3) of constant thickness, wherein said non-woven layer (2) has regions of varying thickness and/or density,
   characterized in that said sound insulation component further has a non-woven layer (4), a microperforated non-woven layer (4), a microperforated sheet (4), a microperforated sheet non-woven (4), or a perforated heavy sheet (4), which is provided in part of the area between said non-woven layer (2) and said foam layer (3).
2. The sound insulation component (1) according to claim 1, characterized in that said non-woven layer (2) comprises synthetic fibers containing polyester fibers, especially PET, polyamide fibers, especially nylon 6 and/or nylon 66, polyolefin fibers, especially PP and/or PE, acrylic fibers, and their mixed fibers including bicomponent fibers and multicomponent fibers, and/or mixtures of natural fibers, especially raw cotton, flax, hemp, coconut, kenaf, jute and/or sisal fibers, with the above mentioned synthetic fibers.
3. The sound insulation component (1) according to claim 1 and 2, characterized in that said non-woven layer (2) has a basis weight within a range of from 180 to 1800 g/m², especially from 220 to 1300 g/m².
4. The sound insulation component (1) according to any of claims 1 to 3, characterized in that the thickness of said non-woven layer (2) varies within a range of from 1 to 75 mm.
5. The sound insulation component according to any of claims 1 to 4, characterized in that said foam layer (3) comprises a polyurethane (PUR) foam layer, especially having a density of from 20 to 120 g/l, preferably 45 to 85 g/l, or a melamine resin or high expansion foam layer having a density within a range of from 8 to 45 g/l.
6. The sound insulation component (1) according to any of claims 1 to 5, characterized by having a total thickness of from 3 to 95 mm.
7. The sound insulation component (1) according to claim 1, characterized in that said microperforated non-woven layer (4) has a basis weight within a range of from 20 to 200 g/m².
8. The sound insulation component (1) according to claim 1, characterized in that said microperforated sheet (4) has a basis weight within a range of from 35 to 100 g/m².
9. The sound insulation component (1) according to claim 1, characterized in that said microperforated sheet non-woven (4) has a basis weight within a range of from 65 to 280 g/m².
10. The sound insulation component (1) according to claim 1, characterized in that said perforated heavy sheet (4) has a basis weight within a range of from 0.8 to 3 kg/m².
11. The sound insulation component (1) according to any of claims 1 to 10, characterized in that said non-woven layer (2) has a calendar-treated or chemically pretreated surface in the region of contact with said foam layer (3).
12. A process for producing a sound insulation component (1) according to any of claims 1 to 11, characterized in that a non-woven layer (2) and a partial-area positioned non-woven layer (4), a partial-area positioned microperforated non-woven layer (4), a partial-area positioned microperforated sheet (4), a partial-area positioned microperforated sheet non-woven (4), or a partial-area positioned perforated heavy sheet (4) is laid into a foaming mold together with said non-woven layer (2), wherein said non-woven layer (4), microperforated non-woven layer (4), microperforated sheet (4), microperforated sheet non-woven (4), or perforated heavy sheet (4) have been prelaminated with said non-woven layer (2), and are foam-backed in the mold, which may be open or closed.
13. The process according to claim 12, characterized in that a polyurethane (PUR), melamine resin or high expansion foam layer is laminated with the prepressed non-woven layer (2) in a press mold.

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