Vehicle seat comprising padding formed of a random entanglement of thermoplastic continuous fibers

Abstract

The present disclosure relates to a seat (1) comprising: - a typically metallic structure (2), - padding (3), - an interface (4) located between the structure (2) and the padding (3), the padding (3) comprising a 3D entanglement of randomly arranged thermoplastic continuous fibers (5) forming welded loops between the fibers.

Description

Description Title: Vehicle seat comprising padding formed from a random entanglement of continuous thermoplastic fibers

[0001] This disclosure relates to a vehicle seat comprising a structure, typically metallic, padding, and an interface interposed between the structure and the padding.

[0002] According to this disclosure, the padding comprises a random entanglement of continuous, thermoplastic, three-dimensional fibers, the fibers welded together by loops between the fibers. technical field

[0003] This disclosure relates to the field of automotive seats, which typically have a metallic structure, including a seat frame and a backrest frame. The structure is conventionally produced using stamping techniques. The seats also include padding, including a seat cushion layer and a backrest cushion layer, which provide softness to the seat and backrest and contribute to overall seating comfort. Previous technique

[0004] The seat and back cushions are typically made of urethane polymer foam and molded into shape. Polyurethane foam cushions are satisfactory, but can retain moisture in humid conditions.

[0005] Furthermore, polyurethane foam is typically made by mixing, among other things, polyols with isocyanates. The chemical reaction involved releases CO2 to form the foam, and this CO2 contributes to global warming.

[0006] Furthermore, polyurethane foam is difficult to recycle.

[0007] Therefore, it appears desirable to limit the use of polyurethane in the padding of vehicle seat components. Summary

[0008] This disclosure improves the situation.

[0009] A seat is offered that includes: - a typically metallic structure, - padding, - an interface located between the structure and the padding, wherein the padding comprises a 3D entanglement of randomly arranged continuous thermoplastic fibers, forming loops welded together between the fibers, and wherein: - the fibers are hollow and / or solid fibers, with a diameter between 0.2 mm and 2 mm, preferably between 0.3 mm and 1.5 mm, - the fibers comprise a thermoplastic polymer, the fiber composition comprising at least 95% by weight of PET, and in which the 3D entanglement of the padding has an apparent density of between 35 kg / m³ 3 and 55 kg / m 3 .

[0010] Thus, the padding is made at least in part, and preferably primarily, from a material other than polyurethane foam. This padding material is advantageously a recyclable plastic, and its production generates less CO2 emissions than the production of polyurethane foam, thereby reducing the environmental impact of the seat with this padding. In addition to the environmental benefits, the process using this material for the padding can result in padding that is significantly lighter than similar padding made of polyurethane foam. Furthermore, the padding material can be more breathable, allowing air and any moisture to pass through the padding more effectively.

[0011] According to one embodiment, the padding is a seat padding in the form of a layer of seat padding, extending lengthwise along a longitudinal direction of the seat from a rear edge to a front edge of the seat, and in width along a transverse direction of the seat from a first lateral edge to a second lateral edge, as well as in thickness along an orthogonal direction which is orthogonal to the longitudinal direction and to the transverse direction of the seat.

[0012] According to one embodiment, the padding is a backrest padding in the form of a layer of backrest padding extending lengthwise along a longitudinal direction of the backrest from a lower edge to an upper edge of the backrest, and widthwise along a transverse direction of the backrest from a first lateral edge to a second lateral edge, as well as thicknesswise along an orthogonal direction that is orthogonal to the longitudinal and transverse directions of the backrest.

[0013] According to one embodiment, the thickness of the backrest padding layer can be between 15 mm and 50 mm and / or the thickness of the seat padding layer can be between 60 mm and 100 mm

[0014] According to one embodiment, the backrest padding layer may comprise different zones having different apparent densities, distributed along the longitudinal direction of the backrest padding layer and / or the seat padding layer may comprise different zones having different apparent densities, along the longitudinal direction of the seat padding layer.

[0015] In one embodiment, the interface may comprise a material made entirely or partially of plastic. This interface may be made of ABS and / or PC and / or PE.

[0016] In particular, the interface can be a folder interface comprising: - at least one deformable backrest shell, receiving the padding which is a backrest padding, said deformable shell being configured to take different shapes from an initial position of lumbar lordosis to a final position of lumbar kyphosis in response to a variable load applied by the back of the seat occupant, - a system coupling said deformable backrest shell to the structure comprising upper movement control links, and lower movement control links.

[0017] According to one embodiment, the seat padding layer and / or the backrest padding layer comprises, depending on the thickness: - a lower, structural sublayer, formed from an interweaving of hollow fibers, of thickness Epinf, - a soft top underlayer, formed from an interweaving of solid Epsup fibers, - an intermediate sub-layer between the lower sub-layer and the upper sub-layer, of bonding comprising an entanglement of solid and hollow fibers welded together, of thickness Epint.

[0018] According to one embodiment, the padding layer comprises, by weight: - 95% to 99% of a primary polymer from the polyester family, such as PET, - 1% to 5% of a second polymer from the polyester family other than PET, such as PTT or PBT. The second polymer is distinct from the first polymer.

[0019] Preferably, the gaps between the fibers of the 3D fiber entanglement of the quilting are left free.

[0020] In one embodiment, the padding comprising said 3D entanglement of continuous thermoplastic fibers is supported by an inner face of said 3D entanglement of continuous thermoplastic fibers on said interface. A cap may optionally cover an outer face of said entanglement of continuous thermoplastic fibers. The cap is fixed to said interface, configured so as to ensure that the padding remains attached to said interface.

[0021] According to one embodiment, said padding comprising said 3D entanglement of continuous thermoplastic fibers is simply supported on said interface, namely that said padding is not glued (or not welded) to said interface, so as to allow separation of the padding and said interface after removal of said cap.

[0022] This disclosure further relates to a manufacturing process for a seat according to this disclosure, in which the padding is obtained comprising a 3D entanglement of continuous thermoplastic fibers, randomly arranged to form loops welded together by a continuous process comprising: - / A / Extrusion of a thermoplastic polymer in an extrusion die comprising extrusion nozzles distributed along a longitudinal direction and along a widthwise direction of the extrusion die, generating a curtain of continuous molten fibers, falling by gravity, - / B / Reception of the curtain of continuous fused fibers falling by gravity between two counter-rotating guide members, with the generation of a 3D entanglement of fibers according to a random distribution with fusion of loops between the continuous fibers and according to a layer of thickness determined by the center distance between the two counter-rotating members, - / C / Solidification of the 3D fiber entanglement by immersion in a coolant.

[0023] According to one embodiment of the process, the extrusion die comprises, along the longitudinal direction of the extrusion die, several distinct zones comprising distinct nozzle-number surface densities, including at least a first zone with a low nozzle-number surface density, and at least a second zone with a high nozzle-number surface density, such as to obtain at least a first zone with a low apparent density and at least a second zone with a high apparent density, along the direction of the 3D fiber entanglement extending along the longitudinal direction of the extrusion die.

[0024] According to one embodiment, which may possibly be combined with the previous one, the extrusion die comprises, depending on the width dimension of the extrusion die, a first section provided with first extrusion nozzles for the generation of hollow fibers, and a second section provided with second extrusion nozzles for the generation of solid fibers.

[0025] According to one embodiment, the extrusion temperature implemented in / A / in the extrusion die is between 180°C and 240°C. Brief description of the drawings

[0026] Other features, details, and advantages will become apparent upon reading the detailed description below and analyzing the attached drawings, on which: Fig. 1

[0027] [Fig. 1] is a view of a motor vehicle seat, according to one embodiment, illustrating the metal structure of the seat supporting a plastic backrest interface intended to receive a layer of backrest padding and a plastic seat interface intended to receive a layer of seat padding, the backrest and seat padding not being shown. Fig. 2

[0028] [Fig. 2] is a cross-sectional view of the seat in Figure 1, on which a layer of back padding and a layer of seat padding are added, according to the present disclosure comprising a random entanglement, in three 3D dimensions of continuous thermoplastic fibers comprising loops between fibers heat-welded to each other. Fig. 3

[0029] [Fig. 3] is a schematic view of the manufacturing process enabling the production of the 3D tangle comprising an extrusion of a thermoplastic polymer in an extrusion die generating a curtain of continuous molten fibers, falling by gravity, the reception of the curtain of continuous molten fibers between two counter-rotating guide members, with a generation of a 3D tangle of fibers and the solidification of the 3D tangle of fibers by immersion in a coolant, then the obtaining of padding by transverse cuts in the direction of scrolling. Fig. 4

[0030] [Fig. 4] illustrates different extrusion dies that can be implemented according to the process of this disclosure, namely an extrusion die comprising extrusion nozzles for extruding solid fibers to obtain a quilt from solid fibers according to a first possibility, an extrusion die comprising extrusion nozzles for extruding hollow fibers to obtain a quilt from hollow fibers according to a second possibility, and a mixed extrusion die comprising extrusion nozzles for extruding hollow fibers and extrusion nozzles for extruding solid fibers according to a third possibility, allowing the obtaining of a quilt comprising, depending on the thickness, a lower, structural underlayer formed from an entanglement of hollow fibers, a soft upper underlayer formed from an entanglement of solid fibers, and an underlayer,intermediate layer between the lower and upper sublayers, acting as a bonding layer. Fig. 5

[0031] [Fig. 5] shows, on the one hand, at the top an extrusion die having a surface density of the number of extrusion nozzles configured to obtain a cushion of homogeneous apparent density, along the length direction of the extrusion die, and at the bottom an extrusion die comprising several distinct zones comprising respectively distinct surface densities of the number of nozzles, comprising zones with low surface density of the number of nozzles, and zones with high surface density of the number of nozzles in such a way as to obtain, two zones with low apparent density and three zones with high apparent density, along the direction of the 3D entanglement of fibers extending along the longitudinal direction of the extrusion die, the low density zones and the high density zones being distributed alternately along the length of the die. Fig. 6

[0032] [Fig. 6] illustrates, in a cross-sectional view, an assembly between said interface, the padding, and a cover over the padding, fixed to said interface, the shell forming the interface having raised edges ensuring the shaping of lateral support portions, projecting on either side of a central portion of the interface. Fig. 7

[0033] [Fig. 7] is a detail view of figure 7, illustrating the mechanical coupling of the cap to said shell forming interface, by a couple of hooking ribs and hooking grooves. Description of the implementation methods

[0034] The drawings and description below contain, for the most part, elements of a definite nature. They may therefore not only serve to better explain this disclosure, but also contribute to its definition, if necessary.

[0035] Therefore, this disclosure relates to seat 1 comprising: - a typically metallic structure 2, - a 3-layer quilted layer, - an interface 4 located between structure 2 and padding 3.

[0036] The padding 3 can be covered by a cap 9. The cap 9 can typically be fixed by its edges to the interface 4. The fixing of the cap to said interface 4 can ensure that the padding 3 is held on said interface 4, preferably by simple support.

[0037] In Figure 2, an XYZ coordinate system is shown, with the X direction oriented along the sliding direction of slide G between the seat structure 2 and a vehicle floor, the Y direction oriented along a transverse direction of the seat, and the Z direction along the vertical

[0038] The structure 2 typically made of metal comprises a seat frame 20 and a backrest frame 21, typically articulated around a transverse axis of rotation, typically by means of continuous type joints.

[0039] The seat frame 20 typically includes: - two side flanges, extending from a rear edge of the seat to a front edge, along the X direction, or slightly inclined relative to the direction longitudinal X (typically plus or minus 30 degrees) around a transverse axis and, - a front piece, connecting two front ends of the flanges, and extending in the transverse direction. The front piece and the flanges are typically formed sheet metal, for example, by stamping techniques.

[0040] The backrest frame typically comprises side uprights extending vertically, as well as a top rail connecting the two upper ends of the uprights. The uprights and top rail are typically made of sheet metal formed, for example, by stamping techniques.

[0041] The padding 3 typically includes a seat padding layer 3a which provides seating comfort and is received on a seat interface 4a interposed between the seat frame 20 and the seat padding layer 3a and / or the padding 3 typically includes a backrest padding layer 3b which provides backrest comfort and is received on a backrest interface 4b which is interposed between the backrest frame 21 and the backrest padding layer 3b.

[0042] The padding 3, in particular the seat padding layer 3a and / or the back padding layer 3b, comprises a three-dimensional (in "3D" >>) entanglement 30 of continuous, thermoplastic fibers 5, randomly arranged, forming loops welded together between the fibers 5.

[0043] The fibers can be hollow fibers 5a and / or solid fibers 5b. The fibers can have a diameter between 0.2 mm and 2 mm, preferably between 0.3 mm and 1.5 mm. The term "continuous" in "continuous fibers" refers to fibers whose length is much greater than their diameter, and due to the process described below, typically by a ratio of at least 100, or even 500, or 1000.

[0044] Fibers 5 comprise a thermoplastic polymer, the fiber composition preferably comprising at least 95% PET by weight. For example, the fiber composition, or even the padding composition, may include: - 95% to 99% by weight of a first polymer from the polyester family such as PET (Polyethylene terephthalate), - 1% to 5% by weight of a second polymer from the polyester family, such as PTT (polytrimethylene terephthalate) or PBT (polybutylene terephthalate). The sum of PET and PTT (or PBT) can represent 100% by weight of the fibers, or even the entire quilting. The 3D interlocking of the quilting can have an apparent density of between 35 kg / m³ 3 and 55 kg / m 3 .

[0045] Preferably, the gaps between the fibers 5 of the 3D fiber interweave of the quilting 3 are left open. This results in a highly breathable quilt, due to the numerous spaces between the fibers which promote air circulation.

[0046] The seat cushion layer 3a extends lengthwise along a longitudinal direction Xa from a rear edge of the seat to a front edge, and widthwise along a transverse direction a from a first lateral edge of the seat to a second lateral edge. Its thickness is also along an orthogonal direction Za, which is orthogonal to both the longitudinal and transverse directions of the seat. The thickness of the seat cushion layer can range from 60 mm to 100 mm.

[0047] The backrest padding layer 3b extends lengthwise along a longitudinal direction Xb from one lower edge to one upper edge of the backrest, and widthwise along a transverse direction Yb from one lateral edge to a second lateral edge. It also extends in thickness along an orthogonal direction Zb, which is perpendicular to both the longitudinal and transverse directions of the backrest. The thickness of the backrest padding layer can range from 15 mm to 50 mm.

[0048] Interface 4, in particular the seat interface 4a or the backrest interface 4b, may comprise a material made entirely or partially of plastic. For example, said interface 4 may be made of ABS (acrylonitrile butadiene styrene) and / or PC (polycarbonate) and / or P / E (polypropylene / polyethylene copolymer).

[0049] Generally, the interface 4, in particular the seat interface 4a or the backrest interface 4b, may include a shell. The shell may be a molded part or a thermoformed part. The cover 9 may be attached to the shell by the edges of the cover 9 to the edges of the shell. A seat cover covers the The seat cushion 3a is attached to the seat interface 4a, specifically at the edges of the shell. A backrest cover covers the backrest cushion 3b and is attached to the backrest interface 4b, specifically at the edges of the shell.

[0050] For this purpose and according to one fixing variant, the shell of the interface 4 may include hooking grooves 10 extending along the edges of the shell inside which hooking ribs 11, of complementary shape, fixed along the edges of the cap 9, can be locked.

[0051] According to other variations, the fastening system between the shell and the liner can be: - a zipper, or - a self-gripping fastening system (loops and hooks).

[0052] The said 3D entanglement of continuous thermoplastic fibers 5 is supported by an internal face of the said 3D entanglement of continuous thermoplastic fibers 5 on the said interface 4, in particular on the shell of the seat interface 4a or the backrest interface 4b, the cover covering an external face of the said entanglement of continuous thermoplastic fibers 5.

[0053] According to one embodiment, the padding 3, in particular the seat padding 3a or the backrest padding 3b, is simply supported on said interface 4, namely not glued or welded to the latter.

[0054] Recycling is advantageously simplified, said padding 3, in particular said 3D entanglement of continuous thermoplastic fibers 5 being able to be easily separated from said interface 4, for example after removal of the cap 9.

[0055] In particular, said folder interface 4b may include: - at least one deformable backrest shell 40, receiving the padding which is a backrest padding 3b, said deformable shell 40 being configured to take different shapes in particular from an initial position of lumbar lordosis and in particular to a final position of lumbar kyphosis, in response to a variable load applied by the back of the seat occupant, - a system coupling said deformable 40 backrest shell to the structure including upper 41s displacement control links, and lower 41i displacement control links.

[0056] The upper 41s displacement control links and / or the lower 41i displacement control links are typically articulated links which may include connecting rods.

[0057] The backrest padding 3b resting on the deformable shell 40 and held on the shell by the cover 9, as well as said cover 9 covering the backrest padding, accompany the deformation of the deformable shell 40, in response to a variable load applied by the back of the seat occupant.

[0058] In general, said interface 4, in particular the seat interface 4a or the backrest interface 4b may include along a transverse direction Ya, Yb upturned edges 41 comprising a vertical component Za, Zb, on either side of a central portion 42 of said interface 4, in particular of the shell, in particular of the deformable shell 40.

[0059] The raised edges of said interface 4 ensure the shaping of the padding 3 in particular the seat padding 3a or the backrest padding 3b, which is typically a 3D interlocking layer of thermoplastic fibers 5 of constant thickness to form a seat or a backrest includes, along the transverse direction Ya, Yb, a central portion and lateral support portions, projecting from the central portion.

[0060] In the case of the seat, the central portion receives the thigh and / or buttocks of the seat occupant, and the said lateral support portions, arranged on either side of the central portion along the Ya direction, ensure lateral support, typically in turns.

[0061] In the case of the backrest, the central portion receives the back of the seat occupant and the said lateral support portions, arranged on either side along the transverse direction Yb, ensure lateral support, typically in turns.

[0062] This disclosure relates to a manufacturing process for a seat as detailed in this disclosure. According to this disclosure, the following is obtained: padding 3 comprising a 3D entanglement of continuous thermoplastic fibers 5 arranged randomly forming loops welded together by a continuous manufacturing process.

[0063] This continuous process includes, as schematically illustrated in Figure 3: - / A / Extrusion of a thermoplastic polymer in an extrusion die 6 comprising extrusion nozzles 60 distributed along a longitudinal direction X6 and along a widthwise direction Y6 of the extrusion die, generating a curtain of continuous molten fibers 50, falling by gravity, - / B / Reception of the curtain of continuous fused fibers falling by gravity between two counter-rotating guide members 7, 8, with the generation of a 3D entanglement of fibers 5 according to a random distribution with fusion of loops between the continuous fibers, in particular according to a layer of thickness determined by the center distance ETR between the two counter-rotating members 7, 8 - / C / Solidification of the 3D fiber entanglement by immersion in a cooling liquid, such as water.

[0064] The extrusion nozzles 60 are preferably distributed regularly along the length direction X6 of the extrusion die, and in width along the width direction Y6.

[0065] The thickness of the padding layer formed by the interlocking can be adjusted by adjusting the center distance between the two guide elements 7,8.

[0066] In / B / , the two guiding elements 7 and 8 are rotated at a speed typically lower than the fiber fall speed, ensuring fiber accumulation that leads to the formation of loops which heat-weld each other, generating the random three-dimensional entanglement. Solidification in ICI is achieved immediately after step / B / , with the two guiding elements being partially immersed for this purpose.

[0067] The extrusion temperature implemented in / A / in the extrusion die is typically between 180°C and 240°C. The extrusion die is fed with polymer granules.

[0068] The continuously moving 3D fiber tangle layer is then guided out of the coolant reservoir to dry, typically by shaking / vibrating. The moving layer is then cut by cross-sections, resulting in different quilting layers, as seen in Figure 3. These quilting layers extend lengthwise, for example, lengthwise along the longitudinal direction Xa of the seat quilting layer (or lengthwise along the longitudinal direction Xb of the backrest quilting layer), typically along the transverse direction to the moving layer.

[0069] In one embodiment, the apparent density can be homogeneous along the length and width of the layer, as illustrated in Figure 5, top. The density of the number of extrusion nozzles is thus homogeneous along the longitudinal direction of the extrusion die.

[0070] According to another embodiment visible at the bottom of Figure 5, the extrusion die 6 can include, along the length direction X6 of the extrusion die, several distinct zones Z61, Z62, Z63, Z64, Z65 comprising distinct surface densities of number of nozzles, comprising at least a first zone Z62, Z64 with low surface density of number of nozzles, and at least a second zone Z61, Z63, Z65 with high surface density of number of nozzles.

[0071] Such a process makes it possible to obtain at least a first zone Z2, Z4 exhibiting a low apparent density and at least a second zone Z1, Z3, Z5 exhibiting a high apparent density, following the direction of the 3D entanglement of fibers extending along the longitudinal direction X6 of the extrusion die.

[0072] For example, and according to the embodiment shown in Figure 5, two obturators are inserted and close some of the extrusion nozzles, dividing the extrusion die 6 into five consecutive zones Z61 to Z65, following the longitudinal direction X6 of the die. The five zones alternate between areas with a high density of extrusion nozzles (respectively, the zones labeled Z61, Z63, Z65) and areas with low density of the number of nozzles (respectively the areas identified as Z62 and Z64).

[0073] Thus, and advantageously: - the resulting seat padding layer 3a can thus comprise different zones Z1, Z2, Z3, Z4, Z5 exhibiting different apparent densities, depending on the longitudinal direction Xa of the seat padding layer 3a and / or, - the resulting backrest padding layer 3b can thus comprise different zones Z1, Z2, Z3, Z4, Z5 exhibiting different apparent densities, distributed along the longitudinal direction Xb of the backrest padding layer 3b.

[0074] According to one embodiment, the extrusion die may include extrusion nozzles configured for the extrusion of solid fibers only, and as illustrated in the upper left of Figure 4, allowing the production of solid fiber padding.

[0075] According to another embodiment, the extrusion die may include extrusion nozzles configured for the extrusion of hollow fibers only, and as illustrated at the bottom left in Figure 4, allowing the production of hollow fiber padding.

[0076] According to another illustrated embodiment, the extrusion die 6 can include not only extrusion nozzles for the extrusion of solid fibers but also extrusion nozzles for the extrusion of hollow fibers.

[0077] Thus, and as illustrated in Figure 4 on the middle view, the extrusion die 6 can include, according to the width dimension Y6 of the extrusion die, a first section 60a provided with first extrusion nozzles for the generation of hollow fibers 5a which extend lengthwise along the length of the die 6, and a second section 60b provided with second extrusion nozzles for the generation of solid fibers 5b which extend lengthwise along the length of the die 6.

[0078] As illustrated in the right-hand view in Figure 4, the seat padding layer 3a and / or the backrest padding layer 3b may comprise the following the thickness: - a lower, structural sublayer, formed from an entanglement of hollow fibers 5a thick (Epinf), - a soft, top underlayer made of an intertwining of solid Epsup fibers, - an intermediate sub-layer between the lower sub-layer and the upper sub-layer, of bonding comprising an entanglement of solid and hollow fibers welded together, of thickness Epint.

[0079] The apparent density of the lower sublayer and the apparent density of the upper sublayer may be identical or close to + or - 5% depending on the thickness of the layer, at least locally along the longitudinal direction and the transverse dimension of the layer.

[0080] In general and in Figure 4, the thickness Epsup of the upper sublayer formed by the solid fibers 5b, is less than the thickness Epinf of the structural sublayer, formed by the hollow fibers 5a. List of reference signs

[0081] - 1: Seat, - 2: Structure, - 3: Matelassure, - 3a: Seat padding layer, - Xa, Ya, Za: Directions in length, width, and thickness of the seat padding layer, - 3b: Backrest padding layer, - 30. 3D fiber entanglement, - Xb, Yb, Zb: Directions in length, width, and thickness of the backrest padding layer, - 4: Interface, - 41s, 41i. Upper and lower displacement control links, - 5: Fibers, - 5a. Hollow fibers, - 5b. Solid fibers, - Z1, Z2, Z3, Z4, Z5: Zones of the padding layer exhibiting different apparent densities. - 6 Extrusion die, - 60 Extrusion Nozzles, - 60a. Extrusion nozzles for hollow fiber extrusion, - 60b. Extrusion nozzles for the extrusion of solid fibers, - 7, 8. Counter-rotating guiding elements, - 9 Headdress.

[0082] .

Claims

Demands

1. Seat (1) comprising: - a typically metallic structure (2), - a padding (3), - an interface (4) located between the structure (2) and the padding (3) and in which the padding (3) comprises a 3D entanglement of continuous thermoplastic fibers (5) arranged randomly, forming loops welded together between the fibers, and in which: - the fibers are hollow fibers (5a) and / or solid fibers (5b), with a diameter between 0.2 mm and 2 mm, preferably between 0.3 mm and 1.5 mm, - the fibres (5) comprise a thermoplastic polymer, the composition of the fibres comprising at least 95% by weight of PET, and wherein the 3D entanglement of the padding (5) has an apparent density of between 35 kg / m³ 3 and 55 kg / m 3 .

2. Seat according to claim 1 in which: - the padding (3) is a seat padding in the form of a layer of seat padding (3a), extending lengthwise along a longitudinal direction (Xa) of the seat from a rear edge to a front edge of the seat, and widthwise along a transverse direction (Ya) of the seat from a first lateral edge to a second lateral edge, as well as thicknesswise along an orthogonal direction (Za) which is orthogonal to the longitudinal and transverse directions of the seat, and wherein the thickness of the layer of seat padding is between 60mm and 100mm, and / or - the padding (3) is a backrest padding in the form of a layer of backrest padding (3b) extending in length along a longitudinal direction (Xb) of the backrest from a lower edge to a higher edge of the backrest, and in width along a transverse direction (Yb) of the backrest from a first lateral edge to a second lateral edge, as well as in thickness along an orthogonal direction (Zb) which is orthogonal to the longitudinal direction and to the transverse direction of the backrest, and in which the thickness of the layer of backrest padding is between 15 mm and 50 mm.

3. Seat according to claim 1 or 2, wherein the interface (4) comprises a material entirely or partially made of plastic.

4. Seat according to claim 3, wherein said interface (4) is made of ABS and / or PC and / or P / E.

5. A seat according to any one of claims 1 to 4 wherein the interface (4) is a folder interface (4b) comprising: - at least one deformable backrest shell (40), receiving the padding which is a backrest padding (3b), said deformable shell (40) being configured to take different shapes from an initial position of lumbar lordosis to a final position of lumbar kyphosis in response to a variable load applied by the back of the seat occupant, - a system coupling said deformable backrest shell (40) to the structure comprising upper displacement control links (41 s), and lower displacement control links (41 i).

6. A seat according to any one of claims 1 to 5, wherein the padding is a seat padding in the form of a layer of seat padding (3a), extending lengthwise along a longitudinal direction (Xa) of the seat from a rear edge to a front edge of the seat, and widthwise along a transverse direction (Ya) of the seat from a first lateral edge to a second lateral edge, as well as thicknesswise along a direction orthogonal (Za) to the longitudinal and transverse directions of the seat, and / or the padding is a backrest padding in the form of a layer of backrest padding (3b) extending lengthwise along a longitudinal direction (Xb) of the backrest from a lower edge to a upper edge of the backrest, and widthwise along a transverse direction (Yb) of the backrest from a first lateral edge to a second lateral edge,as well as in thickness along a direction orthogonal (Zb) to the longitudinal and transverse directions of the backrest and in which the backrest padding layer (3b) comprises different zones (Z1, Z2, Z3, Z4, Z5) having different apparent densities, distributed along the longitudinal direction (Xb) of the backrest padding layer (3b) and / or, and in which the padding layer of the seat (3a) comprises different zones (Z1, Z2, Z3, Z4, Z5) having different apparent densities, along the longitudinal direction (Xa) of the padding layer of the seat (3a).

7. Seat according to claims 1 to 6, wherein the padding is seat padding in the form of a layer of seat padding (3a) extending lengthwise along a longitudinal direction (Xa) of the seat from a rear edge to a front edge of the seat, and widthwise along a transverse direction of the seat from a first lateral edge to a second lateral edge, as well as thicknesswise along a direction orthogonal to the longitudinal and transverse directions of the seat and / or the padding is backrest padding in the form of a layer of backrest padding (3b) extending lengthwise along a longitudinal direction (Xb) of the backrest from a lower edge to an upper edge of the backrest, and widthwise along a transverse direction (Yb) of the backrest from a first lateral edge to a second lateral edge,as well as in thickness along a direction orthogonal (Zb) to the longitudinal and transverse directions of the backrest, and in which the seat padding layer (3a) and / or the backrest padding layer (3b) comprises, depending on the thickness:, - a lower, structural sublayer, formed of an entanglement of hollow fibers (5a), of thickness Epinf, - a soft top underlayer, formed from an interweaving of solid Epsup fibers, - an intermediate sub-layer between the lower sub-layer and the upper sub-layer, of bonding comprising an entanglement of solid and hollow fibers welded together, of thickness Epint.

8. Seat according to claim 7, wherein the apparent density of the lower sublayer and the apparent density of the upper stump are identical or close to ± 5% depending on the thickness of the layer, at least locally along the longitudinal direction and the transverse dimension of the layer.

9. A seat according to any one of claims 1 to 8, wherein the padding layer comprises, by weight: - 95% to 99% PET, - 1% to 5% of a second polymer distinct from PET such as PTT or PBT.

10. Seat according to any one of claims 1 to 9, wherein the voids between the fibers (5) of the 3D fiber entanglement (5) of the padding (3) are left free.

11. Seat according to any one of claims 1 to 10, wherein the padding (3) comprising said 3D entanglement of continuous thermoplastic fibers (5) is supported by an inner face of said 3D entanglement of continuous thermoplastic fibers (5) on said interface (4), a cap covering an outer face of said entanglement of continuous thermoplastic fibers (5) and wherein said cap is fixed to said interface (4), configured so as to ensure the retention of the padding on said interface (4).

12. Seat according to claim 11, wherein said padding (3) comprising said 3D entanglement of continuous thermoplastic fibers (5) is simply supported on said interface (4), said padding not glued or welded to said interface, so as to permit separation of the padding (3) and said interface after removal of said cap (9).

13. A method for manufacturing a seat according to any one of claims 1 to 12, wherein the padding (3) is obtained, comprising a 3D entanglement of continuous, randomly arranged thermoplastic fibers (5) forming loops welded together by a continuous process comprising: - / A / Extrusion of a thermoplastic polymer in an extrusion die (6) comprising extrusion nozzles (60) distributed along a longitudinal direction (X6) and along a widthwise direction (Y6) of the extrusion die, generating a curtain of continuous molten fibers (50), falling by gravity, - / B / Reception of the curtain of continuous fused fibers falling by gravity between two counter-rotating guide members (7, 8), with a generation of a 3D entanglement of fibers (5) according to a random distribution with loop fusion between the continuous fibers and along a layer of thickness determined by the center distance (ETR) between the two counter-rotating organs (7, 8) - / C / Solidification of the 3D fiber entanglement by immersion in a coolant (9).

14. A method according to claim 13, for manufacturing a seat according to claim 6, wherein the extrusion die (6) comprises, along the longitudinal direction (X6) of the extrusion die, several distinct zones (Z61, Z62, Z63, Z64, Z65) comprising distinct nozzle number surface densities, comprising at least a first zone (Z62, Z64) with a low nozzle number surface density, and at least a second zone (Z61, Z63, Z65) with a high nozzle number surface density such as to obtain at least a first zone (Z2, Z4) having a low apparent density and at least a second zone (Z1, Z3, Z5) having a high apparent density, along the direction of the 3D fiber entanglement extending along the longitudinal direction (X6) of the extrusion die.

15. A method according to claim 13 or 14, for manufacturing a seat according to claim 7 in which the extrusion die (6) comprises, according to the width dimension (Y6) of the extrusion die, a first section (60a) provided with first extrusion nozzles for the generation of hollow fibers (5a), and a second section (60b) provided with second extrusion nozzles for the generation of solid fibers (5).

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