Method for manufacturing seat upholstery, seat upholstery as such and seat as such

Abstract

A method for manufacturing a seat upholstery (12), comprising: a. providing a material (P) comprising at least one thermoplastic polymer, b. extruding said material (P) through an extrusion die (3) comprising a plurality of extrusion nozzles (4) to form a curtain (9) of molten fibers (5), c. injecting an inert gas into the extrusion die (3) at a predetermined elevated pressure so as to create air cavities (6) in the molten fibers (5), and d. forming a 3D tangle (10) with said molten fibers (5) having said air cavities (6), the molten fibers (5) being arranged irregularly, forming loops welded together in said 3D tangle (10), e. solidifying said 3D tangle (10) by cooling so as to obtain said seat upholstery (12).

Description

Title of the invention: Method for manufacturing seat upholstery, seat upholstery as such and seat as such Technical field

[0001] The present disclosure relates to a method for manufacturing seat upholstery, to seat upholstery obtained by said method, and to a seat comprising such upholstery. Prior art

[0002] The present disclosure relates to the field of automobile seats which comprise a generally metallic structure, with a lower seat frame and a seat back frame. The structure is conventionally obtained by stamping techniques. The seats further comprise padding, including a lower seat padding layer and a seat back padding layer which provide softness to the lower seat and the seat back, and contribute to the comfort of the seat. These paddings are generally covered by protectors which cover the paddings.

[0003] The seat bottom and back paddings are conventionally made of urethane polymer foam and are shaped in molds. The polyurethane padding is conventionally covered with a protective covering. Polyurethane foam paddings are satisfactory but may retain moisture in humid conditions. This may induce discomfort for an occupant of the vehicle seat, an element of which includes such padding.

[0004] Furthermore, polyurethane foam is conventionally made by mixing, among other things, polyols with isocyanates. The chemical reaction used emits CO2 to form a foam, the emitted CO2 contributing to global warming.

[0005] Furthermore, polyurethane foam is not recyclable. It therefore seems desirable to limit the use of polyurethane in the padding of vehicle seat elements.

[0006] SUMMARY

[0007] This disclosure improves the situation.

[0008] According to one aspect, a method is provided for manufacturing a seat upholstery, the method comprising:

[0009] a. providing a material comprising at least one thermoplastic polymer,

[0010] b. extruding said material in an extrusion die comprising a plurality of extrusion nozzles to form a curtain of molten fibers,

[0011] c. injecting an inert gas into the extrusion die at a predetermined high pressure so as to create air cavities in the molten fibers, and

[0012] d. forming a 3D entanglement with said fused fibers having said air cavities, the fused fibers being arranged irregularly, forming loops welded together in said 3D entanglement,

[0013] e. solidifying said 3D entanglement by cooling so as to obtain said seat padding.

[0014] The padding obtained by this method is made of a material other than polyurethane foam. This padding material is advantageously a recyclable polymer material, and its production generates fewer CO2 emissions than the production of polyurethane foam. In addition, the method using this material for padding can make it possible to create padding that is significantly lighter than similar padding made of polyurethane foam. In addition, the padding material can be more breathable, which allows air and any moisture to pass better through the padding.

[0015] Furthermore, due to the presence of air cavities in the fibers of the 3D entanglement, the density of the fibers is lower than that of similar fibers having no air cavities. However, the fiber network within the 3D entanglement imparts hardness so that even though the density is lower, the hardness of the 3D entanglement remains similar. Therefore, a seat upholstery having similar mechanical properties but prepared with a lower weight of raw material can be manufactured, which is also beneficial for the environment. The method makes it possible to prepare a lightweight upholstery, for example up to 30% weight saving, or even up to 50% weight saving.

[0016] It should be noted that the extrusion of said material and the injection of said inert gas are carried out simultaneously, i.e. the inert gas is injected during the extrusion process, into the extrusion die.

[0017] The following features may optionally be implemented, separately or in combination with each other:

[0018] The at least one thermoplastic polymer may be selected from the group consisting of a polyester, such as PET (polyethylene terephthalate), PTT (polytrimethylene terephthalate) or PBT (polybutylene terephthalate), and a polyolefin, such as EPP (expanded polypropylene), PE (polyethylene), LDPE (low density polyethylene), LLDPE (linear low density polyethylene). The material constituting the fibers can be recycled. Thus, padding containing such fibers can be recycled.

[0019] The composition of the fiber material preferably comprises at least 95% by weight of PET (polyethylene terephthalate). For example, the composition of the fibers, or even the padding, comprises:

[0020] - 95% to 99% by weight of a first polymer from the polyester family such as PET,

[0021] - 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 be 100% by weight of the fibers, or even the padding.

[0022] The fibers of the padding may have a diameter between 0.2 mm and 2 mm, preferably between 0.3 mm and 1.5 mm.

[0023] The inert gas may be a non-reactive gas. The inert gas may be selected from the group consisting of CO2, SO2, N2, O2 and H2O in the vapor state. The inert gas is advantageously CO2, preferably supercritical CO2. A supercritical fluid, for example supercritical CO2, is a fluid heated to a pressure and temperature above its critical point. Its properties are intermediate between those of gases and liquids. CO2 may be obtained by an environmentally friendly process. CO2 may be extracted or absorbed from the atmosphere.

[0024] The inert gas can be injected at the end of the extrusion process.

[0025] Extrusion is the process of converting a raw material into a product of uniform shape and density by passing it through a restriction under controlled conditions. The conveying is achieved by at least one screw rotating inside a fixed cylinder, and the pressure generated by the screw pushes the material through a restriction called the extrusion die.

[0026] In extrusion, the inert gas, for example supercritical CO2, modifies the rheological properties of the material in the extruder and acts as a blowing agent during expansion in the extrusion die. Its high solubilization in the polymer will result in the creation of air cavities and expansion of the fiber. Coupling the extrusion and injection of the inert gas generates extruded molten fibers having said air cavities. The amount of inert gas can be controlled by adjusting the operational conditions. The expansion of the fibers, the size of the cavities - or the size of the pores - and the density of the pore population can be controlled.

[0027] The injection of inert gas, in particular supercritical CO2, can be carried out at a certain distance from the hopper, in a pumping zone of the extrusion die, i.e. in the area where the channel depth is constant. A check valve can be inserted in the extrusion line to prevent gas pollution.

[0028] Said predetermined high pressure is advantageously between 50 and 300 bar, preferably between 50 and 250 bar. This high pressure makes it possible to create said air cavities in the molten fibers after passing through the extrusion nozzles.

[0029] An extrusion temperature may be between 210°C and 250°C. It should be noted that the injection of the inert gas can reduce the extrusion temperature and so that energy is saved. The choice of the extrusion temperature can regulate the shape and distribution of the air cavities.

[0030] The fused fiber curtain comprises continuous fiber filaments that preferably fall under gravity. "Continuous," as in "continuous fibers," means that the fibers have a length much greater than the fiber diameter and, due to the method of the disclosure, generally at least a ratio of 100, or even 500, or even 1000.

[0031] Forming the 3D entanglement may include receiving the curtain of molten fibers falling by gravity between two counter-rotating guide members, so as to form said 3D entanglement of molten fibers forming loops welded together in an irregular, generally random, distribution.

[0032] Cooling for solidification of the 3D entanglement may be carried out using a liquid or a gas. Cooling of the 3D entanglement may comprise immersing the 3D entanglement of fibres in a bath of cooling liquid, in particular in a water bath, the initial temperature of the liquid preferably being between 8°C and 10°C. It should be noted that cooling fibres having air cavities in a liquid may allow small and homogeneous air cavities to be created in the fibres.

[0033] The method may comprise cutting the padding, particularly when the amount of fibers is sufficient to create the padding. Such cutting may be carried out by any known means, particularly by laser or water jet cutting, using a cutting press or other techniques and equipment. The cutting consists, for example, of forming a flat padding, the opposite main faces extending in two parallel planes.

[0034] Preferably, the empty spaces between the fibers of the 3D interlocking of fibers of the padding are left free. A very air-permeable padding is obtained, thanks to the numerous interstices (empty spaces) between the fibers which promote air circulation.

[0035] In another aspect, in combination with all or part of the above, there is provided a seat upholstery obtainable according to the above method, comprising a 3D entanglement of said fused fibers arranged in a irregular, forming welded loops together between the fibers, and wherein the fused fibers include air cavities such that a density of the fused fibers is at least 20%, preferably at least 30%, lower than a density of similar fused fibers not having such air cavities.

[0036] The average size of said air cavities is between 10 pm and 600 pm, preferably between 10 pm and 400 pm.

[0037] The 3D interlocking of the padding has, for example, an apparent density of between 20 kg / m3 and 70 kg / m3, or even between 45 kg / m3 and 65 kg / m3.

[0038] In another aspect, in combination with the foregoing, there is provided a vehicle seat member comprising a seat upholstery as shown above.

[0039] The seat element may comprise a protection constituting the finishing element of the seat visible to the user. The protection is for example made of woven, non-woven, leather or artificial leather.

[0040] The vehicle seat element may consist of at least one of:

[0041] - a file,

[0042] - a seat;

[0043] - an armrest;

[0044] - a headrest;

[0045] - an upper backrest adjustment device; and

[0046] - a device for adjusting the length of the seat.

[0047] The vehicle seat element may in particular be a seat consisting of a backrest and a seat.

[0048] According to one example, the thickness of the padding, when the seat element is a backrest, may be between 30 mm and 60 mm and / or the thickness of the padding, when the seat element is a seat, may be between 40 mm and 120 mm.

[0049] In another aspect, in combination with the foregoing, there is provided a vehicle seat comprising a vehicle seat member as shown above. Brief description of the drawings

[0050] Other features, details and advantages will be illustrated in the following detailed description and in the figures, in which:

[0051] [Fig. 1] schematically shows an example of implementation of the method according to the disclosure.

[0052] [Fig.2] shows in isolation and schematically a part of the implementation of the method illustrated in [Fig.l].

[0053] [Fig.3] shows in isolation and schematically a molten fiber after passing through the extrusion die.

[0054] [Fig.4] schematically shows a side and partially exploded view of a example of a vehicle seat including an example of seat upholstery. Description of the embodiments

[0055] In the various figures, the same references designate identical or similar elements. For the sake of simplicity, only the elements which are useful for understanding the example described are illustrated in the figures and are described in detail below.

[0056] In the following description, when reference is made to terms qualifying an absolute position, such as the terms "front", "rear", "top", "bottom", "left", "right", etc., or relative, such as the terms "above", "below", "upper", "lower", etc., or to orientation qualifiers, such as "horizontal", "vertical", etc., reference is made, unless otherwise indicated, to the orientation of the figures or of a vehicle seat in its normal position of use.

[0057] Reference is made to Figures 1 to 3 illustrating an installation (1) for implementing an example of a method for manufacturing seat upholstery. The method, which is continuous in this example, comprises providing a material P comprising at least one thermoplastic polymer. The material P may be granules of polymer(s). The at least one thermoplastic polymer is for example a polyester, such as PET (polyethylene terephthalate), PTT (polytrimethylene terephthalate) or PBT (polybutylene terephthalate), or a polyolefin, such as EPP (expanded polypropylene) and / or similar copolymers, PE (polyethylene), LDPE (low density polyethylene), LLDPE (linear low density polyethylene). The material preferably comprises at least 95% PET by weight.

[0058] The material P is introduced into a hopper (2), as illustrated in Figures 1 and 2. The material P is guided towards an extrusion die (3). The method comprises extruding the material P into the extrusion die (3). The temperature of the extrusion may be between 210°C and 250°C, being equal to 230°C for example.

[0059] The extrusion die (3) comprises a plurality of extrusion nozzles (4). In this example, the extrusion nozzles (4) are regularly distributed in two perpendicular directions to form a matrix of extrusion nozzles, i.e. in the lengthwise direction and in the widthwise direction of the extrusion die (3). The extrusion of the material P forms, after passing through the extrusion nozzles (4), a curtain (9) of molten fibers (5), as illustrated in Figures 1 and 2. The curtain (9) is formed with continuous fiber filaments falling by gravity out of the extrusion die (3). Here, the extrusion nozzles (4) are distributed in a horizontal plane. Also, in order to keep the density of the fibers (5) substantially constant in the cross-section of the curtain (9) of fibers (5), the fibers (5) are here entrained by gravity at the outlet of the extrusion die (3), as illustrated by the arrow in figures 1 and 2.

[0060] The method also comprises, by means of a gas injector (7), the injection of an inert gas into the extrusion die (3) at a predetermined high pressure, advantageously between 50 bar and 300 bar, preferably between 50 bar and 250 bar, so as to create air cavities (6) in the melted fibers (5).

[0061] In this example, the inert gas is CO2, more particularly supercritical CO2. The inert gas can also be SO2, N2, O2 or H2O in the vapor state.

[0062] The inert gas can be injected at the end of the extrusion process. The high pressure makes it possible to create said air cavities (6) in the molten fibers (5) after passing through the extrusion nozzles (4).

[0063] During extrusion, the inert gas, for example supercritical CO2, modifies the rheological properties of the material in the extruder and acts as a blowing agent. The high solubilization of the inert gas in the polymer results in the creation of air cavities and the expansion of the fiber as illustrated in [Fig.2]. The coupling of extrusion and injection of the inert gas generates extruded molten fibers (5) having said air cavities (6). The amount of inert gas can be controlled by adjusting the operational conditions. The expansion of the fibers, the size of the cavities - or the size of the pores - and the density of the pore population can be controlled.

[0064] The injection of inert gas, in particular supercritical CO2, can be carried out at a certain distance from the hopper (2), in a pumping zone of the extrusion die (3), i.e. in the zone where the channel depth is constant. A non-return valve can be inserted in the extrusion die to prevent gas pollution.

[0065] An example of a portion of a molten fiber (5) is illustrated in [Fig.3], comprising a plurality of such air cavities (6) formed by the injection of the inert gas during the extrusion process, into the extrusion die (3). The air cavities (6) are in the fiber (5) in multiple locations, as illustrated. An average size of said air cavities is between 10 pm and 600 pm, preferably between 10 pm and 400 pm.

[0066] The fibers (5) may have a diameter of between 0.2 mm and 2 mm, preferably between 0.3 mm and 1.5 mm.

[0067] After passing through the extrusion nozzles (4), the method comprises forming a 3D entanglement (10) with the molten fibers (5) having the air cavities (6). In the 3D entanglement (10), the molten fibers (5) are arranged irregularly, forming loops welded together. The method further comprises solidifying the 3D interlock (10) by cooling so as to obtain a seat padding (12).

[0068] As illustrated in [Fig.l], the formation of the 3D entanglement (10) comprises guiding the curtain of molten fibers between two counter-rotating guide members (11) by forming a mass of fibers upstream of the two guide members (11), so as to form said 3D entanglement of molten fibers forming loops welded together. The thickness of the layer of the 3D entanglement is determined by the central distance between the two counter-rotating guide members (11). The thickness of the cushioning layer formed by the 3D entanglement can be adjusted by adjusting the central distance between the two guide members (11).

[0069] The cooling of the 3D entanglement can be carried out using a liquid or a gas. In this example, the cooling of the 3D entanglement consists of immersing the 3D entanglement of fibers in a bath (15) of cooling liquid, in particular in a water bath, the initial temperature of the liquid preferably being between 8 °C and 10 °C.

[0070] The two guide members (11) are rotated at a speed, generally lower than the falling speed of the fibers (5), ensuring an accumulation of the fibers causing the formation of loops which are welded together between the fibers, generating the irregular or random 3D entanglement (10). Solidification is obtained just after the formation of the 3D entanglement (10), the two guide elements (11) being immersed halfway up in the bath (15) provided for this purpose, in this example.

[0071] In this example, the empty spaces between the fibers (5) of the 3D tangle (10) of the padding are left free.

[0072] The continuously moving layer of fibers (5) of the 3D tangle (10) is then guided out of the bath (15) to be dried, generally by agitation / vibrations. The moving layer is then cut, by transverse cuts, making it possible to obtain different paddings (12), and as can be seen in [Fig.l]. These paddings (12) extend lengthwise along a longitudinal direction.

[0073] Cutting of the padding, see the scissors schematically illustrating the cutting in [Fig.l], can be implemented when the quantity of fibers (5) in the 3D tangle (10) is sufficient to create the padding (12). Such cutting can be carried out by any known means, in particular by laser or water jet cutting, using a cutting press or other techniques and equipment. The cutting can be implemented, in this example, on a flat scrolling layer, the opposite main faces of the padding (12) extending in two parallel planes.

[0074] As a possible alternative, the 3D interlocking may be solidified when profiled in a mold cavity by immersion in a cooling liquid.

[0075] According to one example, the extrusion nozzles (4) are adjustable, configured so as to be able to modify the shape of the fiber curtain (9). A logic processing unit may be provided which comprises a control module comprising a microprocessor and a memory comprising instructions for controlling the extrusion nozzles (4) so ​​as to generate a curtain (9) of molten fibers (5) of variable shape during extrusion in the lengthwise direction and / or in the widthwise direction of the extrusion die (3).

[0076] According to one example, in particular according to the method of [Fig. 1], the apparent density can be homogeneous along the length and width of the layer. The density of the number of extrusion nozzles (4) is thus homogeneous in the direction of the length of the extrusion die (3). According to another example, it is possible to have different areas of different apparent densities.

[0077] The seat padding (12) illustrated in [Fig.l] is therefore obtained according to the method explained with reference to Figures 1 to 3. More precisely, a plurality of seat paddings (12) are obtained and illustrated in [Fig.l].

[0078] The seat upholstery (12) comprises a 3D entanglement of the irregularly arranged melted fibers (5) forming loops welded together between the fibers (5). The melted fibers (5) comprise air cavities (6) such that a density of the melted fibers (5) is at least 20%, preferably at least 30%, lower than the density of similar melted fibers (5) not having such air cavities. Thus, the seat upholstery (12) is lighter and has less material than a seat upholstery having fibers without air cavities.

[0079] The 3D interlocking (10) of the padding (12) has for example an apparent density of between 45 kg / m3 and 65 kg / m3. The padding density is optimized to ensure comfort and support for the occupant.

[0080] The padding (12) is made of a material other than polyurethane foam. The material is advantageously a recyclable polymer material and its production generates less CO2 emissions than the production of polyurethane foam. In addition, the process using this material for the padding may allow for the creation of padding that is significantly lighter than similar padding made of polyurethane foam. In addition, the padding material may be more breathable, allowing air and any moisture to pass better through the padding.

[0081] Furthermore, due to the presence of air cavities (6) in the fibers (5) of the 3D entanglement (10), the density of the fibers (5) is lower than that of similar fibers having no air cavities, although the hardness of the 3D entanglement (10) remains similar because the hardness depends on the fiber network within the 3D entanglement which remains similar.

[0082] A vehicle seat element (20) comprising a seat upholstery (12) is illustrated in [Fig. 4], together with a vehicle seat (100) comprising such a vehicle seat element (20). The vehicle seat element (20) comprises, in this example, a backrest (21) and a seat (22). [Fig. 4] schematically illustrates a portion of a vehicle seat (100) as manufactured, mounted on a slide mechanism (32). This seat (100) comprises a metal frame, so as to form a seat frame (33) and a backrest frame (36).

[0083] The thickness of the padding (12), when the seat element (20) is a backrest (21), may be between 30 mm and 60 mm. The thickness of the padding (12), when the seat element (20) is a seat (22), may be between 40 mm and 120 mm.

[0084] In other examples, the vehicle seat member may consist of at least one of an armrest, a headrest, an upper backrest adjustment device, and a seat length adjustment device.

[0085] The seat element (20) may comprise a protection constituting the finishing element of the seat visible to the user. The protection is for example made of woven, non-woven, leather, artificial leather or leather.

Claims

Claims

1. A method for manufacturing a seat upholstery (12), comprising: a. providing a material (P) comprising at least one thermoplastic polymer, b. extruding said material (P) through an extrusion die (3) comprising a plurality of extrusion nozzles (4) to form a curtain (9) of molten fibers (5), c. injecting an inert gas into the extrusion die (3) at a predetermined elevated pressure so as to create air cavities (6) in the molten fibers (5), and d. forming a 3D tangle (10) with said molten fibers (5) having said air cavities (6), the molten fibers (5) being arranged irregularly, forming loops welded together in said 3D tangle (10), e. solidifying said 3D entanglement (10) by cooling so as to obtain said seat padding (12).

2. The method of claim 1, wherein the at least one thermoplastic polymer is selected from the group consisting of a polyester, such as PET (polyethylene terephthalate), PTT (polytrimethylene terephthalate) or PBT (polybutylene terephthalate), and a polyolefin, such as EPP (expanded polypropylene), PE (polyethylene), LD PE (low density polyethylene), LLDPE (linear low density polyethylene).

3. The method of claim 1 or 2, wherein the inert gas is selected from the group consisting of CO2, SO2, N2, O2 and H2O in vapor form.

4. Method according to the preceding claim, in which the inert gas is CO2, preferably supercritical CO2.

5. A method according to any preceding claim, wherein the gas is injected at the end of the extrusion process.

6. A method according to any preceding claim, wherein said predetermined high pressure is between 50 bar and 300 bar, preferably between 50 bar and 250 bar.

7. A method according to any preceding claim, wherein a temperature of the extrusion is between 210°C and 250°C.

8. A seat upholstery (12) obtained according to the method of claims 1 to 7, comprising a 3D entanglement (10) of said molten fibers (5) arranged irregularly, forming loops welded together between the fibers (5), and wherein the molten fibers (5) comprise air cavities (6) such that a density of the molten fibers (5) is at least 20%, preferably at least 30%, lower than a density of similar molten fibers not having such air cavities.

9. Seat padding (12) according to the preceding claim, wherein an average size of said air cavities (6) is between 10 pm and 600 pm, preferably between 10 pm and 400 pm.

10. A vehicle seat element (20) comprising a seat padding (12) according to claim 8 or 9.

Images