Light weight acoustic trim part

Abstract

Multilayer sound attenuating trim part for a vehicle, in particularly for a trim part or cladding used in the interior of a car, for instance as an inner dash or as part of the floor covering or for the exterior of a vehicle, for instance as a trim part or cladding in the engine bay area or as part of an under body trim part as well as to the method of producing a part, comprising at least two fibrous layers (10, 30) and at least one air permeable intermediate film layer (20) between the at least two fibrous layers, whereby all layers together have a variable thickness.

Claims

1. Multilayer Automotive trim part for noise attenuation comprising at least two fibrous layers and at least one air permeable intermediate film layer between the at least two fibrous layers, whereby all layers together have a variable thickness characterized in that at least for an area with a thickness between 4 and 12.5 mm the overall air flow resistance (AFR.sub.overall) and the overall density relate as follows 1500<AFR.sub.overall?10<3800 with AFR.sub.overall in Nsm.sup.?3 and in kg/m.sup.3.

2. Multilayer Automotive trim part for noise attenuation comprising at least two fibrous layers and at least one air permeable intermediate film layer between the at least two fibrous layers, whereby all layers together have a variable thickness characterized in that at least for an area with an overall density above 250 kg/m.sup.3 the overall air flow resistance (AFR.sub.overall) and the overall density relate as follows 1500<AFR.sub.overall?10<3800 with AFR.sub.overall in Nsm.sup.?3 and in kg/m.sup.3.

3. Automotive trim part according to claim 1, wherein the air flow resistance of the top layer and the intermediate layer together represents at least 55% of the overall AFR of the multilayer, preferably between 65% and 80% of the overall AFR of the multilayer.

4. Automotive trim part according to claim 1, wherein the AFR of the intermediate film layer is higher than the AFR of the at least two fibrous layers.

5. Automotive trim part according claim 1, wherein at least one of the fibrous layers comprises a mixture of fibers consisting of 10 to 40% by weight of binder fibers, 10 to 70% by weight of recycled fibers, and 10 to 70% by weight of self-crimped fibers or synthetic fibers, wherein the total amount of said fibers adds to 100% by weight.

6. Automotive trim part according to claim 1, wherein at least one of the fibrous layers comprises a mixture of fibers consisting of 10 to 40% by weight of binder fibers, 10 to 70% by weight of recycled fibers, wherein the total amount of said fibers adds to 100% by weight.

7. A multilayer acoustic trim part according to claim 1, wherein the air permeable intermediate film layer is one of a single layer film or a multilayer film.

8. A multilayer acoustic trim part according claim 7, wherein the film is made with at least one of the following polymers: copolymer or polymer of acetate, like Ethylene Vinyl Acetate (EVA), copolymers of acrylate for instance Ethylene Acrylic Acid (EAA), a polyolefin for instance a polyethylene (PE) based polymer, like linear density polyethylene (LDPE), linear long density polyethylene (LLDPE) or a metallocene linear long density polyethylene (mLLDPE) or derivatives, or a multilayer film, preferably a combination of a polyethylene based copolymer film covered with an adhesive EAA layer at least at one side.

9. A multilayer acoustic trim part according to claim 1, wherein the film is replaced by one of: a nonwoven scrim, a hot melt layer, a gluing web or adhesive layer.

10. A multilayer acoustic trim part according to claim 5, wherein the binder fibers are one of a mono-component fiber or bi-component fiber made with at least one of the following materials, polyester, in particularly polyethylene terephthalate, polyolefins, in particularly Polypropylene or polyethylene, polylactic acid (PLA) or polyamide.

11. A multilayer acoustic trim part according to claim 5, wherein the recycling fibers are one of a cotton shoddy, a synthetic shoddy, a polyester shoddy, a natural fiber shoddy, or a mixed synthetic fiber and natural fiber shoddy.

12. A multilayer acoustic trim part according to claim 5, wherein the self-crimped or synthetic fibers are made with at least one of the following materials polyamide (nylon) preferably polyamide 6 or polyamide 6,6, polyester and or its copolymers, preferably polyethylene terephthalate or polybutylene terephthalate, or polyolefin, preferably polypropylene or polyethylene, or made of a polymer and its copolymer, preferably polyethylene terephthalate and its copolymer.

13. A multilayer acoustic trim part according to claim 5, wherein the self-crimped fibers are conjugate fibers made of at least two sides with a difference between the two sides inducing an intrinsic self-crimping of the fiber in a random 3 dimensional form.

14. A multilayer acoustic trim part according to claim 1, further comprising at least one of a covering scrim layer, an acoustic scrim layer, a decorative top layer, for instance a tufted carpet layer or nonwoven carpet layer.

15. Use of the multilayer acoustic trim part according to claim 1, as an interior trim part for instance as an inner-dash, as part of an interior flooring system, or as an inner wheel house lining or as an acoustic cladding, or as an engine bay trim part, for instance a hood liner or outer-dash.

16. Automotive trim part according to claim 2, wherein the air flow resistance of the top layer and the intermediate layer together represents at least 55% of the overall AFR of the multilayer, preferably between 65% and 80% of the overall AFR of the multilayer.

17. Automotive trim part according to claim 2, wherein the AFR of the intermediate film layer is higher than the AFR of the at least two fibrous layers.

18. Automotive trim part according claim 2, wherein at least one of the fibrous layers comprises a mixture of fibers consisting of 10 to 40% by weight of binder fibers, 10 to 70% by weight of recycled fibers and 10 to 70% by weight of self-crimped fibers or synthetic fibers, wherein the total amount of said fibers adds to 100% by weight.

19. Automotive trim part according to claim 2, wherein at least one of the fibrous layers comprises a mixture of fibers consisting of 10 to 40% by weight of binder fibers, 10 to 70% by weight of recycled fibers, wherein the total amount of said fibers adds to 100% by weight.

20. A multilayer acoustic trim part according to claim 2, wherein the air permeable intermediate film layer is one of a single layer film or a multilayer film.

21. A multilayer acoustic trim part according claim 7, wherein the film is made with at least one of the following polymers: copolymer or polymer of acetate, like Ethylene Vinyl Acetate (EVA), copolymers of acrylate for instance Ethylene Acrylic Acid (EAA), a polyolefin for instance a polyethylene (PE) based polymer, like linear density polyethylene (LDPE), linear long density polyethylene (LLDPE) or a metallocene linear long density polyethylene (mLLDPE) or derivatives, or a multilayer film, preferably a combination of a polyethylene based copolymer film covered with an adhesive EAA layer at least at one side.

22. A multilayer acoustic trim part according to claim 2, wherein the film is replaced by one of: a nonwoven scrim, a hot melt layer, a gluing web or adhesive layer.

23. A multilayer acoustic trim part according to claim 18, wherein the binder fibers are one of a mono-component fiber or bi-component fiber made with at least one of the following materials, polyester, in particularly polyethylene terephthalate, polyolefins, in particularly Polypropylene or polyethylene, polylactic acid (PLA) or polyamide.

24. A multilayer acoustic trim part according to claim 18, wherein the recycling fibers are one of a cotton shoddy, a synthetic shoddy, a polyester shoddy, a natural fiber shoddy, or a mixed synthetic fiber and natural fiber shoddy.

25. A multilayer acoustic trim part according to claim 18, wherein the self-crimped or synthetic fibers are made with at least one of the following materials polyamide (nylon) preferably polyamide 6 or polyamide 6,6, polyester and or its copolymers, preferably polyethylene terephthalate or polybutylene terephthalate, or polyolefin, preferably polypropylene or polyethylene, or made of a polymer and its copolymer, preferably polyethylene terephthalate and its copolymer.

26. A multilayer acoustic trim part according to claim 18, wherein the self-crimped fibers are conjugate fibers made of at least two sides with a difference between the two sides inducing an intrinsic self-crimping of the fiber in a random 3 dimensional form.

27. A multilayer acoustic trim part according to claim 2, further comprising at least one of a covering scrim layer, an acoustic scrim layer, a decorative top layer, for instance a tufted carpet layer or nonwoven carpet layer.

28. Use of the multilayer acoustic trim part according to claim 2, as an interior trim part for instance as an inner-dash, as part of an interior flooring system, or as an inner wheel house lining or as an acoustic cladding, or as an engine bay trim part, for instance a hood liner or outer-dash.

29. A multilayer acoustic trim part according to claim 1, wherein the entirety of the trim part is air permeable.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1A is a schematic showing an exploded view of a trim part of one embodiment of the present invention;

(2) FIG. 1B is a schematic of the trim part of FIG. 1A; and

(3) FIG. 2 shows the acoustic performance of one embodiment of the present invention.

(4) FIGS. 1A and 1B show schematically the set-up of the product according to the claim with the at least 2 fibrous layers 10 and 30 and the thin intermediate film layer 20. Blanks of the fibrous layers and the intermediate layer are stacked as indicated in FIG. 1A and the stack of materials is molded to form a trim part with a 3 dimensional shape shown as an example in FIG. 1B. During the molding the top and/or bottom fibrous layers are compressed and the fibers are bound to set the final shape of the part. Optionally as part of the process the intermediate film layer might become air-permeable, for instance by forming micro perforations or by the process of melting and solidifying of the material. Although layer 10 after molding is relatively constant in its final thickness, slight variations in thickness might be given. In this example, the lower layer 30 has a more pronounced 3 dimensional shape to enable a good fit to the body-in-white of the car. Preferably, at least the layer directed to the body in white of the car comprises crimped fibers as claimed. de

(5) An example of a part according to invention can be as follows:

(6) The top layer 10 is facing away from the noise source and is made of a first fibrous layer with an area weight of 750 gsm comprising 18% of PET/CoPET bicomponent fibers as binder fibers and 82% of recycled fibers, preferably a shoddy cotton.

(7) The air permeable intermediate layer 20 is a film layer with a weight per square meter of between 19 gsm. The film layer is made permeable during the steam molding process of the part, thereby fine tuning the air flow resistance of the film using steam pressure.

(8) The second fibrous layer 30 is a fibrous layer with an area weight of 550 gsm consisting of 18% by weight of PET/CoPET bicomponent fibers as binder fibers and 40% by weight of PET conjugated self-crimped fibers and 42% of recycled fibers, preferably cotton shoddy. Giving an overall area weight of around 1300 gsm.

(9) An comparative example according to the state of the art has a top layer of 18% bicomponent fibers as binder fibers and 82% of shoddy material with an area weight of 750 gsm, roughly the same film layer and a second fibrous layer of the same material as the top layer, however at 1100 gsm to compensate for thickness requirements of the trim part. As this material does not achieve the required initial thickness to fill the maximum thickness areas of the part at a lower area weight. Hence the part has a total area weight of 1850 gsm.

(10) FIG. 2 is showing a simulation of the acoustic performance for the same trim part optimized according to the invention as claimed. The absorption is based on actual measurements in an Alpha Cabin of flat samples and on the thickness distribution as mentioned in the background section. The absorption of a part according to the state of the art is shown in dotted line, while the absorption of a part according to the invention is shown in continuous line. The better acoustic performance for the part according to the invention is specifically linked to the performance in the areas of low thickness (high density) which is better for the part according to the invention because of the optimal overall AFR.

(11) The multilayer part according to invention can be used as an interior trim part for instance as an inner-dash, or hush panel, as part of an interior flooring system, as an acoustic cladding, or as an engine bay trim part, for instance a hood liner, or outer-dash or as an outer or inner wheel arch liner.

(12) A multilayer acoustic trim part according to the invention may further comprise additional layers such as a covering scrim layer, an acoustic scrim layer, a decorative top layer, for instance a tufted or nonwoven carpet layer. To keep the benefit of the acoustic attenuation these additional layers should be air permeable at least on the side directed to the noise source.

(13) The Production of the Trim Part

(14) In the following possible production processes will be explained in more detail. However, a skilled person might also be expected to know how to use alternative processes to come to a similar result.

(15) The different fibers are blended in the advantageous combination according to the teachings of the invention and the properties needed for the specific part, such that the fibers are evenly blended throughout the material formed. The blended fibers are formed in a mat or bat, by known technologies available on the market. Preferably by using a card or garnet, which gives a more orientated fiber material or by using an airlay process, for instance using a Rando-Webber or other known air lay machine, which gives a more random laid web or mat. The thus obtained web or mat can be further processed in a continuous process. If there is a need for later processing the web or mat formed can be consolidated for instance in a thermal process step or by using needling. Needling is not preferred for the fibrous webs or mats containing the self-crimped fibers, since it has a negative impact on the loftiness and resilience of the layer obtained.

(16) The product can be made by using hot and/or cold molding processes. An example of such a process can be a combination of preheating the material in a hot air oven followed by a cold molding step to obtain the 3D shaped trim part. Alternatively the material is heated directly in the mold for instance by a hot fluid, like hot air or steam, to obtain a consolidated part. In particular, the use of steam is preferable if the film is to be made air permeable during the molding step.