Method for manufacturing a sound-absorbing interior lining for a vehicle, in particular for a motor vehicle

Abstract

A method for manufacturing a sound-absorbing interior lining for a vehicle, particularly for a motor vehicle. The manufacturing process comprises a step of supplying a first pre-needled layer (19) of first fibers (15) onto a conveyor (34) with brushes (33); a step of needle-punching the first layer (19) to form a first layer having a first thickness; a step of supplying a second layer (29) pre-needled with second fibers (17) onto said first layer; a step of needle-punching the second layer (29) with the first layer to join them, at the end of which the second layer forms a base (16) of the lining (12). The second needle-punching device (50) is configured so that the second fibers (17) of the second layer (29) penetrate the first layer to a height less than said first thickness of the first layer.The first (19) and second (29) layers each contain bi-component fibers. Figure for the abbreviation: Figure 1.

Description

Title of the invention: Method for manufacturing an acoustically absorbing interior covering for a vehicle, in particular for a motor vehicle

[0001] The present invention relates to a method of manufacturing an acoustically absorbing interior covering for a vehicle, in particular for a motor vehicle.

[0002] The production of an acoustically absorbent interior covering is already known in the prior art, by producing a layer of velvet and then bonding the velvet layer to a layer of acoustically insulating material. The velvet layer is produced by a Dilour® type needling machine. Such a needling machine has the particularity of comprising a conveyor covered with brushes which are used to form a homogeneous velvet. For this purpose, needles of the needling machine draw fibers from a sheet deposited on the conveyor through the bristles of the brushes.

[0003] The operation of such a machine as well as the components constituting it is for example described in EP 0 183 952.

[0004] The invention aims in particular to reduce the cost of producing an acoustically absorbent coating, as well as to reduce its surface weight, while improving its recyclability, and without reducing its effectiveness.

[0005] To this end, the invention relates in particular to a method for manufacturing an interior covering for a vehicle, comprising:

[0006] - a first step of providing a first pre-needled sheet of first fibers on a brush conveyor;

[0007] - a first step of needling the first sheet, by means of a first needling device comprising first needles, at the end of which the first sheet becomes a first layer having a first predefined thickness;

[0008] - a second step of providing a second pre-needled sheet of seconds fibers on said first layer,

[0009] - a second step of needling the second sheet with the first layer in order to assemble them, by means of a second needling device comprising second needles, at the end of which the second sheet forms a sole of the covering;

[0010] characterized in that:

[0011] - the second needling device is configured so that the second fibers of the second layer penetrates into the first layer to a height less than said first thickness of the first layer,

[0012] - the first and second sheets each contain bi-component fibers.

[0013] The coating according to the invention is obtained directly on the Dilour machine, and does not require the addition of glue. This results in a significant economic gain linked to the absence of glue.

[0014] Furthermore, the use of bi-component fibers allows the velvet to be fixed during a thermoforming step of the covering, without requiring an additional consolidation step, which further implies an economic gain. In addition, the absence of glue allows the covering to be recycled.

[0015] Finally, it should be noted that the fact that the second needles penetrate into the first layer to a height less than the thickness of the first layer makes it possible not to make the fibers of the second layer visible on the surface of the velvet, the second fibers extending into the first layer being shorter than the first fibers in this first layer.

[0016] A manufacturing method according to the invention may further comprise one or more of the following characteristics, taken alone or in any technically conceivable combination.

[0017] - The first and second sheets contain, by mass, between 10 and 30% of bi-fibers component.

[0018] - The manufacturing process includes a subsequent step of thermoforming the inner coating, during which the inner coating is shaped in a heating mold, heated to a temperature above the melting temperature of one component of the bi-component fibers.

[0019] - The heating mold has an air gap configured to compress the coating interior until the sole has a density between 200 and 500 kg / m3.

[0020] - The heating mold has an air gap configured to compress the coating interior until the sole has an Air Passage Resistance (APR) of between 350 and 500 Ns / m3.

[0021] - The second sheet comprises fibers having a count of less than 3.3 dTex.

[0022] - The second sheet contains recycled fibers.

[0023] - The first and second fibers are of the same nature, preferably recyclable, for example in polyester.

[0024] - The manufacturing process comprises, following the second needling, a step of shearing of the top of the first fibers of the first layer, carried out at a height greater than the penetration depth of the second fibers into the first layer so that the second fibers do not appear on the surface of the coating.

[0025] Various aspects and advantages of the invention will be highlighted in the following description, given solely by way of non-limiting example, and made with reference to the appended figures, among which:

[0026] [Fig-1] [Fig.l] is a schematic view of a device for manufacturing coating according to an exemplary embodiment of the invention;

[0027] [Fig.2] [Fig.2] is a schematic sectional view of a coating obtained by the method of the invention.

[0028] [Fig.l] shows a device 10 for manufacturing a coating 12.

[0029] The covering 12 is shown in more detail in [Fig. 2]. This covering 12 forms, for example, an interior covering of a vehicle, and more particularly of a motor vehicle, intended to be placed on the floor or on a wall of the vehicle.

[0030] The covering 12 has a face layer 14 of first fibers 15 substantially parallel to each other, and a backing layer 16 forming a sole formed essentially of second fibers 17 bonded together. It should be noted that the second fibers 17 extend partly into the face layer 14, where they are bonded with the first fibers 15.

[0031] The fibers 15 and 17 are for example made from a thermoplastic polymer, such as polypropylene, polyethylene terephthalate (PET), polyamide, polylactic acid, their mixtures or their copolymers. Alternatively, the fibers 15 and 17 may be fibers of natural origin such as flax or hemp fibers used alone or in mixtures.

[0032] The fibers 15 and 17 may be of different natures. For example, the fibers 15 may be based on polyamide while the fibers 17 will be based on PET.

[0033] Preferably, the fibers 15 and 17 are of the same nature, and recyclable, for example polyester (PET).

[0034] Each layer 14 and 16 is formed from a mixture of the fibers 15 and 17 with two-component binder fibers, one of the components of which has a melting temperature lower than the melting temperature of the other component.

[0035] More particularly, a bi-component fiber comprises a core formed from a first component and a sheath, surrounding the core, formed from a second component whose melting temperature is lower than that of the first component. The first component is preferably of the same nature as the fibers 15 or 17 of the corresponding layer. Thus, when the bi-component fibers are brought to the melting temperature of the second component, the latter melts, becoming a binder for the fibers, and all that remains of the bi-component fibers is their cores, which become similar to the other fibers of the corresponding layer.

[0036] The face layer 14 has a velvety exterior appearance. This velvet is made up of fibers 15 in the form of loops or individual fibers (shorn loops). The thickness of the face layer 14 is generally greater than that of the sole 16. The face layer 14 has, for example, a first thickness of between 2 and 8 mm.

[0037] The length of the fibers used is generally between 40 and 90 mm.

[0038] The fiber count is preferably less than 17 dtex.

[0039] The manufacturing device 10 comprises a conventional device 18 for producing a first sheet 19 of pre-needled fibers.

[0040] This production device 18 comprises conventional means 20 for producing at least one web of first fibers, means 22 for superimposing this at least one web, and a pre-needling device 24 for consolidating the web or the superimposed webs, and thus obtaining the first pre-needled sheet 19.

[0041] It should be noted that the production device 18 can be integrated into the manufacturing device 10, or separated from it, in which case the first pre-needled sheet 19 can be produced beforehand and then added to the manufacturing device 10. In the latter case, the first sheet 19 can be produced on another site.

[0042] The manufacturing device 10 also comprises a conveyor 34 provided with brushes 33.

[0043] The first sheet is intended to be deposited on the brushes 33 of the conveyor 34, upstream of a first needling device 40. For this purpose, the manufacturing device 10 comprises a device 36 for applying the first sheet 19 to the brushes 33 of the conveyor 34.

[0044] The needling device 40 comprises at least one board of first needles 4L

[0045] The needle board 41 is arranged opposite the conveyor belt 34, and it can be deployed vertically towards this belt to pierce the first sheet.

[0046] The needle board 41 carries a plurality of needles 41, allowing a needling density of the order of 200 to 800 cps / cm2.

[0047] During the first needling, carried out by the first needling device 40, a portion of the fibers 15 of the first sheet 19 is drawn by the needles through the brushes 33, transversely relative to the first sheet 19. The first sheet 19 thus becomes a first layer having a first thickness EL

[0048] The manufacturing device 10 also comprises a conventional device 28 for producing a second sheet 29 of pre-needled fibers.

[0049] This production device 28 comprises conventional means 30 for producing at least one second web of second fibers, means 31 for superimposing this at least one second web, and a pre-needling device 32 for consolidating the second veil or the second superimposed veils, and thus obtain the second pre-needled sheet 29.

[0050] Preferably, at least a portion of the second fibers 17 are recycled fibers. In this case, these recycled fibers do not necessarily have the same color between them, nor the same color as the first fibers 15.

[0051] According to a preferred embodiment, the second fibers comprise fine fibers, for example whose count is less than 3.3 dTex.

[0052] It should be noted that the production device 28 can be integrated into the manufacturing device 10, or separated from it, in which case the second pre-needled sheet 29 can be produced beforehand and then added to the manufacturing device 10. In the latter case, the second sheet 29 can be produced on another site.

[0053] The second sheet 29 is intended to be deposited on the first layer, downstream of the first needling device 40, and upstream of a second needling device 50. For this purpose, the manufacturing device 10 comprises a device 46 for applying the second sheet 29 to the first layer.

[0054] The second needling device 50 comprises at least one board of second needles 51.

[0055] The second needling device 50 makes it possible to secure the second sheet 29 to the first layer, by extracting fibers from the second sheet 29 and making them penetrate into the first layer.

[0056] The depth of penetration of the fibers of the second sheet 29 into the first layer is less than the thickness E1 of the first layer, so that the second fibers are not visible on the surface of the final pile. Thus, the appearance of the pile is not deteriorated, even when the second fibers have one or more colors different from the color of the first fibers.

[0057] The penetration depth depends in particular on the type of needles fitted to the needling head of the Dilour® machine and their length.

[0058] The type of needle used may be the same as that used for producing the first layer on the first needling device 40.

[0059] A person skilled in the art will know how to choose the needles adapted so that the depth of penetration of the fibers of the second sheet 29 into the first layer is less than the thickness E1 of this first layer.

[0060] During this step, the face layer 14 and the sole 16 are formed, by intermingling the fibers 15 of the first layer with the fibers 17 of the second reinforcing ply.

[0061] More particularly, the face layer 14 is formed by said first layer, in which second fibers 17 are intermingled with the first fibers 15, and the sole 16 is formed by the second ply.

[0062] Optionally, the device 10 then comprises a device for mowing the top of the fibers 15, which makes it possible to equalize the height of the fibers 15. The mowing is carried out at a height greater than the penetration depth of the second fibers in the face layer, so that the second fibers do not appear on the surface of the covering.

[0063] Finally, the device 10 comprises a device for winding the formed covering 12, for handling.

[0064] The device according to the invention makes it possible to carry out a method of manufacturing a coating which will now be described according to a first embodiment.

[0065] The manufacturing method comprises the production of a first pre-needled sheet of fibers 19, by means of the production device 18.

[0066] For this purpose, at least one web of first fibers 15 is produced, to possibly superimpose several webs, before pre-needling the web or the superimposed webs, and thus obtaining the first pre-needled sheet 19.

[0067] The first sheet 19 is then deposited on the brushes 33 of the conveyor 34, upstream of the first needling device 40, by the application device 36.

[0068] The method then comprises a first needling step, carried out by the first needling device 40, a portion of the fibers 15 of the first sheet 19 then being drawn by the needles through the brushes 33, transversely relative to the first sheet 19. The first sheet thus becomes a first layer having a first thickness EL

[0069] The manufacturing method also includes the production of the second pre-needled fiber sheet 29.

[0070] To this end, at least one second web of second fibers 17 is produced, then several second webs are optionally superimposed, before pre-needling the second web or the second superimposed webs, and thus obtaining the second pre-needled sheet 29.

[0071] The second sheet 29 is then deposited on the first layer, downstream of the first needling device 40, and upstream of the second needling device 50.

[0072] During a second needling step, the second needling device 50 secures the second sheet 29 to the first layer, by extracting fibers from the second sheet 29 and causing them to penetrate into the first layer.

[0073] As indicated previously, the depth of penetration of the fibers of the second sheet 29 into the first layer is less than the thickness E1 of the first layer, so that the second fibers are not visible on the surface of the final pile.

[0074] During this step, the face layer 14 is formed, as well as the sole 16, by intermingling the fibers 15 with the fibers 17 of the second reinforcing ply.

[0075] Optionally, the method then comprises shearing the top of the fibers 15, thereby forming a pile of vertical fibers.

[0076] Finally, the method comprises rolling up the formed covering 12, with a view to handling it.

[0077] The coating 12 can subsequently be thermoformed, in a heating mold.

[0078] In this mold, the two layers of the coating are heated in their thickness by convection.

[0079] The air gap of the thermoforming mold is chosen according to the desired porosity (and therefore sound absorption performance). Indeed, the porosity of the coating depends on its compression.

[0080] It will be noted that the porosity of the sole 16 is further reduced when it comprises fine fibers.

[0081] For optimal sound absorption, the covering 12 is compressed to a density of the sole 16 of between 200 and 500 kg / m3.

[0082] Heating is carried out above the melting temperature of the fusible component of the bi-component fibers, so that this component melts and spreads between the fibers to bind them together.

[0083] Preferably, the coating is preheated on heating plates, just before thermoforming, in order to improve the absorption of the binder into the fibers.

[0084] Alternatively, the heating can be carried out by infrared with a wavelength of between 0.7 and 4 micrometers.

[0085] Upon leaving the hot trays, the product is placed in a thermoforming mold which is itself heated to a temperature between 30 and 70°C. These conditions make it possible to obtain a finished product with better dimensional stability.

[0086] It will be noted that, due to the compactness of the sole 16, the acoustic absorption properties of the covering 12 are satisfactory, that is to say that the Air Passage Resistance (APR) is between 350 and 500 Ns / m3. The APR is measured according to the ISO 9053 standard.

[0087] The method according to the invention therefore makes it possible to obtain an acoustically absorbent coating 12, economically. In particular, the two layers of the coating are bonded together by needling, without requiring gluing, then consolidated by the fusion of the two-component fibers.

[0088] It will also be noted that the coating 12 has good recyclability, due to the fact that it does not contain latex or glue. For example, the coating 12 is entirely made of polyester fibers (PET).

Claims

Claims

1. A method of manufacturing an interior covering (12) for a vehicle, comprising: - a first step of providing a first ply (19) pre-needled with first fibers (15) on a conveyor (34) with brushes (33); - a first step of needling the first ply (19), by means of a first needling device (40) comprising first needles (41), at the end of which the first ply becomes a first layer having a first predefined thickness; - a second step of providing a second ply (29) pre-needled with second fibers (17) on said first layer, - a second step of needling the second ply (29) with the first layer in order to assemble them, by means of a second needling device (50) comprising second needles (51), at the end of which the second ply forms a sole (16) of the covering (12);characterized in that: - the second needling device (50) is configured so that the second fibers (17) of the second sheet (29) penetrate into the first layer over a height less than said first thickness of the first layer, - the first (19) and second (29) sheets each contain bi-component fibers - the manufacturing method comprises compressing the inner coating (12), by means of a heating mold having an air gap configured to compress said inner coating (12).;

2. A manufacturing method according to claim 1, wherein the first (19) and second (29) sheets contain, by mass, between 10 and 30% of bi-component fibers.

3. Manufacturing method according to claim 1 or 2, comprising a subsequent step of thermoforming the inner coating, during which the inner coating (12) is shaped in the heating mold, heated to a temperature above the melting temperature of a component of the bi-component fibers.

4. A manufacturing method according to any preceding claim, wherein the air gap is configured to compress the inner liner (12) until the sole (16) has a density of between 200 and 500 kg / m3.

5. Manufacturing method according to any one of the preceding claims, in which the air gap is configured to compress the inner lining (12) until the sole (16) has an Air Passage Resistance (APR) of between 350 and 500 Ns / 3

6. ni. Manufacturing method according to any one of the preceding claims, in which the second sheet (29) comprises fibers having a count of less than 3.3 dTex.

7. A manufacturing method according to any preceding claim, wherein the second web (29) comprises recycled fibers.

8. Manufacturing method according to any one of the preceding claims, in which the first and second fibers are of the same nature, preferably recyclable, for example polyester.

9. Manufacturing method according to any one of the preceding claims, comprising, following the second needling, a step of shearing the top of the first fibers (15) of the first layer, carried out at a height greater than the depth of penetration of the second fibers into the first layer so that the second fibers do not appear on the surface of the coating.

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