Polyolefin-based nonwoven structure

Abstract

The present invention relates to a polyolefin-based recyclable nonwoven structure, methods for its production and uses thereof. The structure is comprises a plurality of entangled and bonded staple fibres employing polyolefin components with different melting points, and has a density within the range of 0.2-2 g / cm3. The structure can be provided with a low density while maintaining mechanical properties even at low thicknesses (and thus surface densities), such that even challenging mechanical applications (e.g. use in wheel arch liners) are viable utilizing a very low weight of nonwoven.

Description

Technical field

[0001] The present invention relates to a polyolefin-based recyclable nonwoven structure, methods for its production and uses thereof.Background of the invention

[0002] The use of nonwoven structures in various industries has become firmly established. These structures, which are typically composed of bonded and entangled fibres, offer a wide range of desirable properties including strength, durability, and flexibility. They are commonly utilized in various sectors such as healthcare, automotive, and construction, among others.

[0003] However, it is widely recognized that nonwovens made from a single type of polymer often lack sufficient mechanical strength, flexibility, or resistance to chemicals or heat. To address these shortcomings, nonwoven composites, which consist of at least two different types of polymers, are frequently employed. These composites achieve improved properties through the synergistic effects of combining polymers. Examples include PP / PET nonwoven composites and PET / coPET nonwoven composites.

[0004] Despite their extensive use in various industries, in particular the automotive industry, the aforementioned nonwoven composites do have certain limitations. Composites comprising multiple types of chemically unrelated polymers (such as PP and PET) pose significant challenges in terms of recycling. Consequently, they often end up as landfill or are incinerated. In light of the growing emphasis on adopting sustainable practices, this approach no longer aligns with the sustainability goals of most companies and countries.

[0005] While single-polymer products produced through injection moulding may be used, these tend to exhibit considerable weight, which is a notable drawback compared to nonwovens. This drawback is particularly inconvenient in the automotive sector, where the current focus is on constructing lightweight vehicles to reduce fuel consumption and increase the driving range of electric vehicles.

[0006] DE102020114941A1 discloses a method for producing a wheel arch liner for vehicles, incorporating a process involving thermoforming a nonwoven semi-finished product made of high- and low-melting thermoplastic fibres.

[0007] WO2016026875A1 discloses a method for manufacturing lightweight, durable luggage articles, specifically luggage shells, using a compacted, nonwoven sheet comprising randomly oriented, discontinuous reinforcing plastic fibres with a high melting point and randomly oriented discontinuous melting plastic fibres with a lower melting point.

[0008] It is an object of the present invention to provide nonwoven materials suitable for use in challenging mechanical applications (e.g. a wheel arch liner), which have improved recyclability, exhibit improved mechanical or acoustic properties and / or have a reduced weight.Summary of the invention

[0009] The inventors have discovered that a predominantly polyolefin nonwoven structure can be prepared, which combines good recyclability with excellent mechanical properties. The product can be provided with a low density while maintaining mechanical properties even at low thicknesses (and thus surface densities), such that even challenging mechanical applications (e.g. use in wheel arch liners) are viable utilizing a very low weight of nonwoven. These polyolefin based nonwoven materials have the further advantage of possessing excellent chemical resistance, hydrophobicity and durability due to their high polyolefin content.

[0010] Accordingly, a first aspect of the invention concerns a nonwoven structure comprising a plurality of entangled and bonded staple fibres, said nonwoven structure comprising: i. a first polyolefin component, said first polyolefin component having a melting temperature within the range of 130-170 °C; and ii. a second polyolefin component, wherein the melting temperature of the second polyolefin component is at least 10 °C higher than the melting temperature of the first polyolefin component, wherein said nonwoven structure comprises at least 90 wt.% polyolefin staple fibres, by total weight of the nonwoven structure, preferably at least 95 wt.%, more preferably at least 99 wt.%, and wherein the density of the nonwoven structure is within the range of 0.2-2 g / cm 3< , preferably within the range of 0.2-0.9 g / cm 3< , most preferably within the range of 0.2-0.8 g / cm 3< .

[0011] Preferably, the polyolefins in the first polyolefin component and the second polyolefin component each comprise at least 90 wt.%, by total weight of the polyolefin, of the same first polyolefin monomer. Preferably the first polyolefin monomer is propylene.

[0012] Preferably, the first and second polyolefin component are comprised in a first polyolefin staple fibre which is a multicomponent staple fibre, preferably a sheath-core-type bicomponent fibre wherein the second polyolefin component forms the core of the fibre and the first polyolefin component forms the sheath of the fibre.

[0013] In some embodiments, the nonwoven structure is provided comprising the first polyolefin staple fibres and third polyolefin staple fibres, said third staple fibres consisting of a third polyolefin component, wherein the third polyolefin staple fibre has a titer of 0.4-100 dtex, preferably 1-20 dtex, more preferably 2-15 dtex, and wherein the total combined amount of the first and third polyolefin staple fibres constitutes at least 80 wt.% of the nonwoven structure, preferably at least 90 wt.%, more preferably at least 95 wt.%, most preferably at least 99 wt.%. In this embodiment the weight ratio of first polyolefin fibre to third polyolefin fibre in the nonwoven structure is preferably in the range of 1:9 to 9:1, preferably in the range of 1:5 to 5:1, most preferably in the range of 1:2 to 2:1.

[0014] In some embodiments, the nonwoven structure is provided comprising the first polyolefin staple fibres, third polyolefin staple fibres, and fourth polyolefin staple fibres, wherein the third staple fibres consist of a third polyolefin component, and have a titer of 0.4-100 dtex, preferably 1-20 dtex, more preferably 2-15 dtex, wherein the fourth polyolefin staple fibres consist of a fourth polyolefin component, and have a titer which is at least 150% of the titer of the first polyolefin staple fibre, preferably at least 200% higher than the titer of the first polyolefin staple fibre, more preferably at least 300%. In this embodiment, the nonwoven structure preferably comprises: 25-60 wt.% of the first polyolefin staple fibres, by weight of the nonwoven structure, preferably 30-55 wt.%, more preferably 40-50 wt.%; 5-75 wt.% of the third polyolefin staple fibres, by weight of the nonwoven structure, preferably 7.5-70 wt.%, more preferably 10-60 wt.%; and 30-80 wt.% of the fourth polyolefin staple fibres, by weight of the nonwoven structure, preferably 40-75 wt.%, more preferably 40-70 wt.%.

[0015] The nonwoven structure is preferably a sheet, such as a sheet having a surface density within the range of 200-5000 g / m 2< , preferably within the range of 500-2000 g / m 2< , and / or a thickness within the range of 0.5-10 mm, preferably within the range of 1 and 7.5 mm, more preferably within the range of 1.5 to 5 mm.

[0016] The normalized modulus of the nonwoven structure is preferably higher than 750 MPa, more preferably higher than 900 MPa, more preferably higher than 1000 MPa , most preferably higher than 1150 MPa.

[0017] In another aspect, the invention provides a process of preparing a nonwoven structure, said process comprising: a) providing an entangled plurality of staple fibres, said staple fibres comprising: i. a first polyolefin component, said first polyolefin component having a melting temperature of 130-170 °C; and ii. a second polyolefin component, wherein the melting temperature of the second polyolefin component is at least 10 °C higher than the melting temperature of the first polyolefin component; and wherein the entangled plurality of staple fibres comprises at least 90 wt.% polyolefin staple fibres, by total weight of the entangled plurality of staple fibres, preferably at least 95 wt.%, more preferably at least 99 wt.%; and b) at least partially bonding the entangled plurality of staple fibres by heating to a temperature sufficiently high to melt the first polyolefin component, but not substantially the second polyolefin component, and preferably applying pressure while the first polyolefin component is in a molten state.

[0018] In another aspect, the invention provides a nonwoven structure obtainable by the process described herein.

[0019] In another aspect, the invention provides the use of a nonwoven structure according to the invention in a vehicle part, preferably a wheel arch liner, a door panel, an electric vehicle battery shield, an interior trim part, an air duct intake, a rear parcel shelf, a bumper or an underbody shield.Brief description of the figures

[0020] The present invention will now be described in more detail with reference to specific embodiments of the invention, given only by way of illustration, and with reference to the accompanying drawings. Figure 1 illustrates various configurations of bicomponent fibres, such as the preferred embodiments of the first polyolefin staple fibre described herein elsewhere. The exemplary configurations shown in Figure 1 include side-by-side, segmented pie, islands-in-the-sea, tipped, segmented ribbon and sheath-core bicomponent fibres. However, the designs presented in Figure 1 are not exhaustive of all possible configurations.Description of embodiments

[0021] The expression "comprise" and variations thereof, such as "comprises" and "comprising" as used herein, should be construed in an open, inclusive sense, meaning that the embodiment described includes the recited features, but that it does not exclude the presence of other features, as long as they do not render the embodiment unworkable.

[0022] The expressions "one embodiment", "a particular embodiment", "an embodiment" etc., as used herein, should be construed to mean that a particular feature, structure or characteristic described in connection with the embodiment is included in at least one embodiment. Thus, the appearances of such expressions in various places throughout this specification do not necessarily all refer to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. For example, certain features of the disclosure, which are described herein in the context of separate embodiments, are also explicitly envisaged in combination in a single embodiment.

[0023] The singular forms "a," "an," and "the" as used herein should be construed to include plural referents unless the content clearly dictates otherwise. It should also be noted that the term "or" is generally employed in its broadest sense, that is, as meaning "and / or" unless the content clearly dictates otherwise.

[0024] Numerical ranges expressed in the format "from x to y" are understood to include x and y.

[0025] When multiple preferred ranges are described in the format "from x to y" for a specific feature, it should be understood that all ranges combining the different endpoints are also contemplated.

[0026] If, for a particular component, a range of 0% to y% or less than y% is recited, said ingredient may be absent.

[0027] The term "molecular weight", as used herein, within the context of polymers, refers to the number-average molecular weight, preferably the number-average molecular weight as determined by gel permeation chromatography.

[0028] The staple fibres referred to herein may have been prepared via a multitude of methods, and the invention is not particularly limited in this regard. An example of a suitable method is melt spinning. The staple fibres can be solid or hollow, be round or shaped, e.g. multilobal such as trilobal. Preferably, the staple fibres are round.

[0029] The term "polyolefin", as used herein, encompasses all forms of polyolefins, including different forms of stereoisomers (isotactic, atactic, syndiotactic) and is not particularly limited by the average molecular weight of the polyolefin. Preferred molecular weights are set out herein elsewhere

[0030] The term "polyolefin component" as used herein refers to a plastic material comprising a majority (by weight) of polyolefin, but does not exclude the presence of additives which are commonly used in plastics such as antimicrobial agents (such as zinc oxide), plasticizers (such as phthalates, polymeric- and non-polymer plasticizers and adipates), flame retardants (such as aluminum trihydrate), fillers (such as fly ash, bottom ash, aluminum silicate, aluminum hydroxide, calcium silicate, magnesium silicate, dolomite, calcium carbonate, barium sulfate, calcium sulfate, hollow glass microspheres, soot, chalk, siloxanes or silica), reinforcers (such as glass fibers or minerals), pigments (such as carbon black) and / or UV stabilizers. Preferably the polyolefin components referred to herein comprise at least 75 wt.% polyolefin, by total weight of the polyolefin component, preferably at least 80 wt.%. Preferably the polyolefin components referred to herein comprise at least 95 wt.% polyolefin, by total weight of polymers in the polyolefin component, preferably at least 98 wt.%, more preferably at least 99 wt.%, such as 100 wt.%.

[0031] The "melting temperature", as used herein, is determined according to ISO 11357-3, preferably on a DSC Q2000 instrument by TA Instruments. In the context of the present invention, the melting temperature refers to the peak of the melting range of a polymer of the second heating when applying the following temperature protocol under a nitrogen atmosphere: heating from 25 to 200 °C at a rate of 10 °C / min; maintaining 200 °C for two minutes; cooling from 200 to -20 °C at a rate of 10 °C / min; maintaining -20 °C for three minutes; heating from -20 °C to 200 °C at a rate of 10 °C / min.

[0032] The term "titer", as used herein, refers to the linear density of the staple fibre as determined according to ISO 1973:2021, preferably on a Favimat+ by TexTechno.The nonwoven structure of the invention

[0033] A first aspect of the invention relates to a nonwoven structure comprising a plurality of entangled and bonded staple fibres, said nonwoven structure comprising: i. a first polyolefin component, said first polyolefin component having a melting temperature within the range of 130-170 °C; and ii. a second polyolefin component, wherein the melting temperature of the second polyolefin component is at least 10 °C higher than the melting temperature of the first polyolefin component, wherein said nonwoven structure comprises at least 90 wt.% polyolefin staple fibres, by total weight of the nonwoven structure, preferably at least 95 wt.%, more preferably at least 99 wt.%, and wherein the density of the nonwoven structure is within the range of 0.2-2 g / cm 3< , preferably within the range of 0.2-0.9 g / cm 3< , most preferably within the range of 0.2-0.8 g / cm 3< .

[0034] The density of the nonwoven structure may be within the range of 0.25-1.8 g / cm 3< , within the range of 0.25-1.5 g / cm 3< , or within the range of 0.25-1.3 g / cm 3< . The present inventors have found that excellent mechanical performance can be achieved without requiring high densities, thus the density may be within the range of 0.20-0.85 g / cm 3< , within the range of 0.20-0.7 g / cm 3< , or within the range of 0.20-0.6 g / cm 3< . In some embodiments the density is within the range of 0.20-0.75 g / cm 3< , within the range of 0.25-0.6 g / cm 3< , or within the range of 0.3-0.55 g / cm 3< . In some embodiments the density is higher than 0.3 g / cm 3< , preferably higher than 0.4 g / cm 3< .

[0035] The plurality of staple fibres may have been entangled by a variety of methods. It is particularly preferred that the plurality of staple fibres have been entangled by needling or hydroentanglement, most preferably needling.

[0036] The entangled and bonded staple fibres of the nonwoven structure may have been bonded in a multitude of ways. Suitable methods known in the art include chemical and / or thermal bonding, with or without the application of pressure during bonding. However, the inventors found that highly preferably, the entangled staple fibres have been thermally bonded, even more preferably thermally bonded with the application of pressure during bonding (i.e. heat- and pressure-bonded). As is known to the skilled person, heat- and pressure bonding is also referred to as "compression moulding". The exertion of pressure during the thermal bonding process contributes to achieving various properties described herein, including the density and mechanical properties of the nonwoven structure.The polyolefins used in the nonwoven structure of the invention

[0037] The invention employs two polyolefin components having different melting temperatures and may employ further polyolefin components, as described herein elsewhere in more detail. As is known to the skilled person, various polyolefin components exist which have different melting temperatures. The melting temperature of polyolefin components is influenced by a multitude of factors including, but not limited to, the polyolefin method of synthesis (e.g., using a metallocene catalyst or Ziegler Natta catalyst), the polyolefin average molecular weight, the polyolefin stereoisomeric form, branching, crosslinking, the crystal structure, the use of fillers in the polyolefin component, processing applied to the polyolefin components (which include stretching or drawing down, annealing and crosslinking) etc. It is within the routine capabilities of the skilled person, based on the guidance provided in the present document, to determine the melting temperature of a polyolefin (typically, this information is provided by the manufacturer) and select polyolefin components which comply with the requirements of the nonwoven of the present invention.

[0038] In an embodiment of the invention, the polyolefin components described herein, in particular the first and / or second component are synthesized using a metallocene and / or Ziegler Natta catalyst. In one embodiment of the invention, the polyolefin components described herein, in particular the first and / or second component underwent stretching, annealing and / or crosslinking, preferably stretching and / or annealing.

[0039] The polyolefin in the polyolefin components employed in the present invention can be a homopolymer or a copolymer.

[0040] When the polyolefin is a copolymer, it is preferably a copolymer prepared from at least two monomers selected from the group consisting of C 2 -C 5 alkenes, preferably selected from the group consisting of C 2 -C 4 alkenes, most preferably selected from the group consisting of C 2 -C 3 alkenes. The copolymer may be selected from an alternating copolymer, a random copolymer, a block polymer or a graft copolymer, preferably a random copolymer.

[0041] In all embodiments of the invention, the polyolefin in the polyolefin components described herein preferably has a propylene content of at least 80 wt.%, more preferably at least 85 wt.%, still more preferably at least 90 wt.%. In case a copolymer as described herein is used, the amount of monomers other than propylene is preferably 0.5-10 wt.%, preferably 1-8 wt.%, most preferably 3-8 wt.%.

[0042] Thus, the polyolefins in the polyolefin components described herein (in particular the first and second polyolefin component) are preferably each independently selected from a polypropylene homopolymer; and a copolymer prepared from at least two monomers selected from the group consisting of C 2 -C 5 alkenes, preferably selected from the group consisting of C 2 -C 4 alkenes, most preferably selected from the group consisting of C 2 -C 3 alkenes, more preferably selected from a polypropylene homopolymer; and a copolymer having a propylene content of at least 80 wt.%, more preferably at least 85 wt.%, still more preferably at least 90 wt.%, and prepared from at least two monomers selected from the group consisting of C 2 -C 5 alkenes, preferably selected from the group consisting of C 2 -C 4 alkenes, most preferably selected from the group consisting of C 2 -C 3 alkenes, more preferably selected from a polypropylene homopolymer; and a copolymer having a propylene content of at least 90 wt.%, and prepared from at least two monomers selected from the group consisting of C 2 -C 3 alkenes (in other words, prepared from ethylene and propylene).

[0043] In some embodiments of the invention, the polyolefin in at least one of the first and second polyolefin components is a copolymer, preferably a random copolymer, prepared from at least two monomers selected from the group consisting of C 2 -C 5 alkenes, preferably selected from the group consisting of C 2 -C 4 alkenes, most preferably selected from the group consisting of C 2 -C 3 alkenes, and having a propylene content of at least 80 wt.%, more preferably at least 85 wt.%, still more preferably at least 90 wt.%. In some embodiments the polyolefin in at least one of the first and second polyolefin components is a copolymer, preferably a random copolymer, prepared from at least two monomers selected from the group consisting of C 2 -C 3 alkenes (in other words, prepared from ethylene and propylene), and having a propylene content of at least 90 wt.%. The amount of monomers other than propylene, preferably the amount of ethylene, is preferably 0.5-10 wt.%, preferably 1-8 wt.%, most preferably 3-8 wt.%.

[0044] In preferred embodiments of the invention, the polyolefin in at least one of the first and second polyolefin components is a copolymer, preferably a random copolymer, prepared from at least two monomers selected from the group consisting of C 2 -C 5 alkenes, preferably selected from the group consisting of C 2 -C 4 alkenes, most preferably selected from the group consisting of C 2 -C 3 alkenes, and having a propylene content of at least 80 wt.%, more preferably at least 85 wt.%, still more preferably at least 90 wt.%; and the polyolefin in at least one of the first and second polyolefin components is a polypropylene homopolymer, preferably the polyolefin in at least one of the first and second polyolefin components is a copolymer, preferably a random copolymer, prepared from at least two monomers selected from the group consisting of C 2 -C 3 alkenes, and having a propylene content of at least 90 wt.%, wherein the ethylene content is 0.5-10 wt.%, preferably 1-8 wt.%, most preferably 3-8 wt.%; and the polyolefin in at least one of the first and second polyolefin components is a polypropylene homopolymer.

[0045] In highly preferred embodiments of the invention, the polyolefin in the first polyolefin component is a copolymer, preferably a random copolymer, prepared from at least two monomers selected from the group consisting of C 2 -C 5 alkenes, preferably selected from the group consisting of C 2 -C 4 alkenes, most preferably selected from the group consisting of C 2 -C 3 alkenes, and having a propylene content of at least 80 wt.%, more preferably at least 85 wt.%, still more preferably at least 90 wt.%; and the polyolefin in the second polyolefin component is a polypropylene homopolymer, preferably the polyolefin in the first polyolefin component is a copolymer, preferably a random copolymer, prepared from at least two monomers selected from the group consisting of C 2 -Cs alkenes, and having a propylene content of at least 90 wt.%, wherein the ethylene content is 0.5-10 wt.%, preferably 1-8 wt.%, most preferably 3-8 wt.%; and the polyolefin in the second polyolefin component is a polypropylene homopolymer.

[0046] In preferred embodiments of the invention, the polyolefins in the first polyolefin component and the second polyolefin component each comprise at least 90 wt.%, by total weight of the polyolefin, of the same first polyolefin monomer. Preferably the first polyolefin monomer is selected from the group consisting of C 2 -C 5 alkenes, preferably selected from the group consisting of C 2 -C 4 alkenes, most preferably propylene. In other words, the propylene content of the polyolefins in the first polyolefin component and the second polyolefin component is preferably at least 90 wt.%.

[0047] As will be understood by the skilled person, the monomer contents referred to herein refers to the amount of said monomer relative to the total monomers used in the preparation of the polyolefin.

[0048] In a preferred embodiment, the polyolefin components referred to herein have a numberaveraged molecular weight of 10-100 kDa, preferably 20-90 kDa.

[0049] The melting temperature of the first polyolefin component is preferably in the range of 130-160 °C, most preferably in the range of 135-160 °C. The melting temperature of the second polyolefin component is preferably within the range of 140-180 °C, more preferably in the range of 140-170 °C, most preferably in the range of 150-170 °C, with the proviso that the melting temperature of the second polyolefin component is at least 10 °C higher than the melting temperature of the first polyolefin component.

[0050] The polyolefin comprised in the polyolefin components referred to herein may be recycled.Preferred staple fibres used in the nonwoven structures of the invention

[0051] As will be understood by the skilled person, whenever it is mentioned herein that the nonwoven comprises a certain staple fibre, this should be construed to mean that the nonwoven comprises a plurality of said staple fibres since a nonwoven typically employs thousands of fibre particles collectively referred to as a certain staple fibre.

[0052] The first polyolefin component and the second polyolefin component can be present in the nonwoven structure in the same or in different staple fibres. Thus, the first and / or second polyolefin component are comprised in a first polyolefin staple fibre.

[0053] In preferred embodiments, the first polyolefin staple fibre comprises at least 90 wt.% of the first and / or second polyolefin component by weight of the first polyolefin staple fibre, preferably at least 95 wt.%, still more preferably at least 99 wt.%. Most preferably, the first polyolefin staple fibre is a polyolefin staple fibre consisting essentially of the first and / or second polyolefin component.

[0054] In preferred embodiments, the first polyolefin staple fibre has a titer of 0.4-100 dtex, preferably 1-20 dtex, more preferably 2-15 dtex.

[0055] The first polyolefin staple fibre preferably has an average length in the range of 10-200 mm, more preferably in the range of 20-150 mm, most preferably in the range of 30-100 mm.

[0056] In an embodiment of the invention, the first polyolefin staple fibre comprises the first polyolefin component, and the nonwoven structure further comprises a second polyolefin staple fibre comprising the second polyolefin component. In this embodiment, the first polyolefin staple fibre preferably comprises at least 90 wt.% of the first polyolefin component by weight of the first polyolefin staple fibre, more preferably at least 95 wt.%, still more preferably at least 99 wt.%. Most preferably, the first polyolefin staple fibre is a polyolefin staple fibre consisting essentially of the first polyolefin component. Similarly, in this embodiment it is preferred that the second polyolefin staple fibre comprises at least 90 wt.% of the second polyolefin component by weight of the second polyolefin staple fibre, preferably at least 95 wt.%, still more preferably at least 99 wt.%. Most preferably, the second polyolefin staple fibre is a polyolefin staple fibre consisting essentially of the second polyolefin component.

[0057] The second polyolefin staple fibre preferably has a titer in the range of 1-100 dtex, preferably in the range of 2.5-90 dtex, most preferably, the second polyolefin staple fibre has a titer of 0.4-100 dtex, preferably 1-20 dtex, more preferably 2-15 dtex.

[0058] Similar to the first polyolefin staple fibre, the second polyolefin staple fibre preferably has an average length in the range of 10-200 mm, more preferably in the range of 20-150 mm, most preferably in the range of 30-100 mm.

[0059] In those embodiments wherein the second polyolefin fibre is present, the weight ratio of first polyolefin fibre to second polyolefin fibre in the nonwoven structure is preferably in the range of 1:1 to 1:9, more preferably in the range of 1:1 to 1:5, most preferably in the range of 1:1.5 to 1:4.

[0060] In a particularly preferred embodiment, the first polyolefin component and the second polyolefin component are both part of the first polyolefin staple fibre. In other words, it is particularly preferred that said first polyolefin staple fibre is a multicomponent staple fibre comprising the first polyolefin component and the second polyolefin component. Yet more preferably, the first polyolefin staple fibre is a multicomponent staple fibre comprising at least 90 wt.% of a combination of the first polyolefin component and the second polyolefin component by weight of the multicomponent staple fibre, preferably at least 95 wt.%, still more preferably at least 99 wt.%. Most preferably, the multicomponent staple fibre is a bicomponent staple fibre consisting essentially of the first and second polyolefin component.

[0061] Figure 1 shows non-limiting examples of various possible configurations of a bicomponent fibre. Examples of such configurations include sheath-core-type fibres, side-by-side-type fibres or matrix-fibril-type fibres, each of which may be further subdivided into additional types. Bicomponent staple fibres are known to the skilled person. In those embodiments described herein where the first polyolefin staple fibre is a bicomponent fibre, the first polyolefin staple fibre is preferably a sheath-core-type bicomponent fibre, wherein the second polyolefin component forms the core of the fibre and the first polyolefin component forms the sheath of the fibre. In this configuration, the core consisting of the second polyolefin component acts as a matrix to ensure the integrity of the nonwoven structure, whereas the sheath consisting of the first polyolefin component acts as a binding agent upon thermal bonding. The inventors found that this configuration is advantageous with a view to achieving a nonwoven structure consisting essentially of polyolefin components with excellent mechanical properties whilst maintaining a low weight and being fully recyclable.

[0062] In embodiments where the first polyolefin staple fibre is a bicomponent staple fibre, the weight ratio of the first polyolefin component to the second polyolefin component in the bicomponent staple fibre is preferably in the range of 1:1 to 1:9, more preferably in the range of 1:1 to 1:5, most preferably in the range of 1:1.5 to 1:4.

[0063] As will be understood by the skilled person, in those embodiments wherein the first fibre comprises both the first and second component, the second fibre may be used, but this is not necessary.

[0064] In a preferred embodiment, the nonwoven structure according to the present invention comprises 5-70 wt.% of the first polyolefin component by total weight of the nonwoven structure, preferably 10-30 wt.%, most preferably 12-20 wt.% and / or 5-95 wt.% of the second polyolefin component by total weight of the nonwoven structure, preferably 15-80 wt.%, most preferably 30-75 wt.%.

[0065] The nonwoven structure may further comprise a third polyolefin staple fibre, said third polyolefin staple fibre preferably comprising at least 90 wt.% of a third polyolefin component by weight of the third polyolefin staple fibre, at least 90 wt.%, still more preferably at least 99 wt.%. Most preferably, the third polyolefin staple fibre is a polyolefin staple fibre consisting essentially of the third polyolefin component.

[0066] The inclusion of the third staple fibre in the nonwoven structure can enhance the mechanical properties.

[0067] The third polyolefin component preferably has a melting temperature which is at least 10 °C higher than the melting temperature of the first polyolefin component, preferably within the range of 140-180 °C with the proviso that it is at least 10 °C higher than the melting temperature of the first polyolefin component.

[0068] In preferred embodiments, the third polyolefin staple fibre has a titer of 0.4-100 dtex, preferably 1-20 dtex, more preferably 2-15 dtex. The third polyolefin staple fibre preferably has an average length in the range of 10-200 mm, more preferably in the range of 20-150 mm, more preferably the third polyolefin staple fibre has an average length in the range of 30-100 mm.

[0069] The nonwoven structure may further comprise a fourth polyolefin staple fibre, said fourth polyolefin staple fibre preferably comprising at least 90 wt.% of a fourth polyolefin component by weight of the fourth polyolefin staple fibre, preferably at least 95 wt.%, still more preferably at least 99 wt.%. Most preferably, the fourth polyolefin staple fibre is a polyolefin staple fibre consisting essentially of the fourth polyolefin component.

[0070] The fourth polyolefin component preferably has a melting temperature at least 10 °C higher than the first polyolefin component, preferably within the range of 140-180 °C with the proviso that it is at least 10 °C higher than the melting temperature of the first polyolefin component.

[0071] The inventors found that a lightweight nonwoven structure with excellent mechanical properties, such as stress at break or modulus may be provided when a fourth fibre is used and the titer of the fourth polyolefin staple fibres is significantly higher than the titer of the first fibre, whilst still maintaining favourable flexibility, making the nonwoven structure suitable for a multitude of applications. Thus, the use of a fourth fibre is highly preferred. In those embodiments where a fourth fibre is used, the second and / or third fibre may be used, but this is not necessary.

[0072] It is particularly preferred that the fourth polyolefin staple fibre has a titer which is at least 150% of the titer of the first polyolefin staple fibre, preferably at least 200% higher than the titer of the first polyolefin staple fibre, more preferably at least 300%. Preferably, the fourth polyolefin staple fibres have a titer in the range of 10-100 dtex, more preferably in the range of 25-90 dtex, most preferably, in the range of 50-80 dtex.

[0073] The fourth polyolefin staple fibre preferably has an average length in the range of 10-200 mm, more preferably in the range of 20-150 mm. Most preferably, the fourth polyolefin staple fibre has an average length in the range of 30-100 mm.

[0074] As will be understood based on the above, the nonwoven comprises the first polyolefin staple fibres described herein and optionally comprises the second, third and fourth polyolefin staple fibres described herein. In all embodiments, it is preferred that the first, second, third and fourth polyolefin staple fibres each have an average length in the range of 10-200 mm, more preferably in the range of 20-150 mm, most preferably in the range of 30-100 mm; and the first, second and third polyolefin staple fibres have a titer of 0.4-100 dtex, preferably 1-20 dtex, more preferably 2-15 dtex; and the fourth polyolefin staple fibres have a titer in the range of 10-100 dtex, more preferably in the range of 25-90 dtex, most preferably, in the range of 50-80 dtex. Preferred combinations of the different staple fibres used in the nonwovens of the invention

[0075] The nonwoven structure according to the present invention can consist of various combinations of the four staple fibres mentioned hereinbefore. The total combined amount of the first, second, third and fourth fibres employed in the nonwoven structure of the present invention cannot exceed 100 wt.%.

[0076] In one embodiment, the nonwoven structure is provided comprising the first polyolefin staple fibre and optionally the second polyolefin staple fibre wherein the total combined amount of the first and second polyolefin staple fibres constitutes at least 80 wt.% of the nonwoven structure, preferably at least 90 wt.%, more preferably at least 95 wt.%, most preferably at least 99 wt.%. In an embodiment the first polyolefin staple fibres are bicomponent fibres are described hereinbefore. In this embodiment the nonwoven structure may be free of the second polyolefin staple fibres (and thus consist essentially of the first staple fibres) or it may comprise the second polyolefin staple fibres. In another embodiments both the first and second polyolefin staple fibres are homopolymer fibres, such as polypropylene homopolymer fibres, and the nonwoven structure comprises both the first and second polyolefin staple fibres. The weight ratio of first polyolefin fibre to second polyolefin fibre in the nonwoven structure may be in the range of 9:1 to 1:9, such as in the range of 5:1 to 1:5. When the first polyolefin staple fibres are bicomponent fibres as described herein before and the nonwoven structure comprises the second polyolefin staple fibres, it is preferred that the weight ratio of first polyolefin fibre to second polyolefin fibre in the nonwoven structure is in the range of 1:1 to 1:9, more preferably in the range of 1:1 to 1:5, most preferably in the range of 1:1.5 to 1:4. When both the first and second polyolefin staple fibres are homopolymer fibres, such as polypropylene homopolymer fibres, and the nonwoven structure comprises both the first and second polyolefin staple fibres, it is preferred that the weight ratio of first polyolefin fibre to second polyolefin fibre in the nonwoven structure is in the range of 5:1 to 1:5, more preferably in the range of 2:1 to 1:2, most preferably in the range of 1.5:1 to 1:1.5.

[0077] In another embodiment, the nonwoven structure is provided comprising the first and third polyolefin staple fibres, wherein the total combined amount of the first and third polyolefin staple fibres constitutes at least 80 wt.% of the nonwoven structure, preferably at least 90 wt.%, more preferably at least 95 wt.%, most preferably at least 99 wt.%, wherein the first polyolefin staple fibres are preferably bicomponent fibres are described hereinbefore. In this embodiment it is preferred that the weight ratio of first polyolefin fibre to third polyolefin fibre in the nonwoven structure is in the range of 1:9 to 9:1, preferably in the range of 1:5 to 5:1, most preferably in the range of 1:2 to 2:1.

[0078] In another embodiment, the nonwoven structure is provided comprising the first, second and third polyolefin staple fibres, wherein the first polyolefin staple fibres preferably are bicomponent fibres are described hereinbefore. In this embodiment, the nonwoven structure preferably comprises: 5-50 wt.% of the first polyolefin staple fibres, by weight of the nonwoven structure, preferably 20-45 wt.%, more preferably 25-40 wt.%; 10-90 wt.% of the second polyolefin staple fibres, by weight of the nonwoven structure, preferably 15-80 wt.%, more preferably 20-70 wt.%; and 10-90 wt.% of the third polyolefin staple fibres, by weight of the nonwoven structure, preferably 15-80 wt.%, more preferably 20-70 wt.%. wherein the total combined amount of the first, second and third polyolefin staple fibres constitutes at least 80 wt.% of the nonwoven structure, preferably at least 90 wt.%, more preferably at least 95 wt.%, most preferably at least 99 wt.%.

[0079] In another embodiment, the nonwoven structure is provided comprising the first and fourth polyolefin staple fibres, wherein the total combined amount of the first and fourth polyolefin staple fibres constitutes at least 80 wt.% of the nonwoven structure, preferably at least 90 wt.%, more preferably at least 95 wt.%, most preferably at least 99 wt.%, wherein the first polyolefin staple fibres are preferably bicomponent fibres are described hereinbefore. In this embodiment, it is preferred that the weight ratio of first polyolefin fibre to fourth polyolefin fibre in the nonwoven structure is in the range of 1:9 to 9:1, preferably in the range of 1:5 to 5:1, most preferably, in the range of 1:2 to 2:1.

[0080] In another embodiment, the nonwoven structure is provided comprising the first, second and fourth polyolefin staple fibres, wherein the first polyolefin staple fibres preferably are bicomponent fibres are described hereinbefore. In this embodiment, the nonwoven structure preferably comprises: 5-50 wt.% of the first polyolefin staple fibres, by weight of the nonwoven structure, preferably 20-45 wt.%, more preferably 25-40 wt.%; 10-90 wt.% of the second polyolefin staple fibres, by weight of the nonwoven structure, preferably 15-80 wt.%, more preferably 20-70 wt.%; and 10-90 wt.% of the fourth polyolefin staple fibres, by weight of the nonwoven structure, preferably 15-80 wt.%, more preferably 20-70 wt.%. wherein the total combined amount of the first, second and fourth polyolefin staple fibres constitutes at least 80 wt.% of the total weight of the nonwoven structure, preferably at least 90 wt.%, more preferably at least 95 wt.%, most preferably at least 99 wt.%.

[0081] In a particularly preferred embodiment, the nonwoven structure is provided comprising the first, third and fourth polyolefin staple fibres, wherein the first polyolefin staple fibres preferably are bicomponent fibres are described hereinbefore. In this embodiment, the nonwoven structure preferably comprises: 25-60 wt.% of the first polyolefin staple fibres, by weight of the nonwoven structure, preferably 30-55 wt.%, more preferably 40-50 wt.%; 5-75 wt.% of the third polyolefin staple fibres, by weight of the nonwoven structure, preferably 7.5-70 wt.%, more preferably 10-60 wt.%; and 30-80 wt.% of the fourth polyolefin staple fibres, by weight of the nonwoven structure, preferably 40-75 wt.%, more preferably 40-70 wt.%. wherein the total combined amount of the first, third and fourth polyolefin staple fibres constitutes at least 80 wt.% of the total weight of the nonwoven structure, preferably at least 90 wt.%, more preferably at least 95 wt.%, most preferably at least 99 wt.%.

[0082] Whilst the nonwoven structure may comprise further components such as further layers or skin (e.g. a textile woven, a spunbond nonwoven layer, a film layer, local reinforcements,...), accordance with the invention the nonwoven structure comprises at least 90 wt.% polyolefin staple fibres, by total weight of the nonwoven structure, preferably at least 95 wt.%, more preferably at least 99 wt.%, such as 100 wt.%. However it will be understood that the nonwoven structure may be employed in an assembly where the nonwoven structure is combined with further layers or skins, for example by providing a textile layer on an outside surface of the nonwoven structure.

[0083] While small amounts of other polymers will be tolerated during recycling, to optimize recycling of the nonwoven structure it is preferred that the nonwoven structure contains little to no polymers other than polyolefins. Thus, it is preferred that the nonwoven structure comprises less than 10 wt.% of polymers other than polyolefins, by total weight of the nonwoven structure, preferably less than 5 wt.%, more preferably less than 1 wt.%, most preferably essentially none.Mechanical properties of the nonwoven structure of the invention

[0084] The nonwoven structure, as described herein, can be provided having excellent mechanical properties at a low density and thickness (leading to a low surface density).

[0085] In a particularly preferred embodiment, the nonwoven structure according to the invention has a normalized stress at break higher than 40 MPa, preferably higher than 42 MPa, more preferably higher than 43 MPa, most preferably higher than 44.5 MPa. The "normalized stress at break" referred to herein concerns the stress as break which is normalized for density as follows: Normalized stress at break = stress at break density Wherein the density is entered as a dimensionless value corresponding to the value for density expressed in g / cm 3< . The stress at break is determined in accordance with the ISO 527-4:2023 standard.

[0086] The nonwoven structure of the invention can further be provided with a high modulus. The normalized modulus of the nonwoven structure is preferably higher than 750 MPa, more preferably higher than 900 MPa, more preferably higher than 1000 MPa, most preferably higher than 1150 MPa. The "normalized modulus" referred to herein concerns the modulus which is normalized for density as follows: Normalized modulus = modulus density Wherein the density is entered as a dimensionless value corresponding to the value for density expressed in g / cm 3< . The modulus is determined in accordance with the ISO 527-4:2023 standard.

[0087] As mentioned previously, one of the benefits of a nonwoven structure according to the invention is that said nonwoven structure is surprisingly light, despite its excellent mechanical properties. Thus, it is particularly advantageous in the form of a sheet, such as a sheet having a low surface density. Accordingly, the nonwoven structure preferably has a surface density within the range of 200-5000 g / m 2< , preferably within the range of 500-2000 g / m 2< .

[0088] The thickness of the nonwoven structure may be varied depending on the use of said nonwoven structure. The thickness of the nonwoven structure is preferably within the range of 0.5-10 mm, preferably within the range of 1 and 7.5 mm, more preferably within the range of 1.5 to 5 mm.

[0089] Thus, in some preferred embodiments of the invention, the nonwoven structure is provided in the form of a sheet, preferably a sheet having a surface density within the range of 200-5000 g / m 2< , preferably within the range of 500-2000 g / m 2< , and / or a thickness within the range of 0.5-10 mm, preferably within the range of 1 and 7.5 mm, more preferably within the range of 1.5 to 5 mm.

[0090] The sheet preferably has a ratio of thickness (expressed in cm) to the surface area (expressed in cm 2< ) of one side of the sheet which is less than 0.01, preferably less than 0.005. As will be understood by the skilled person, the thickness is the smallest dimension of the sheet.

[0091] The sheet may be shaped or curved, as is the case for example when the sheet is shaped like a wheel arch liner. When the non-woven article, preferably the sheet, is curved this means that it is not flat. When the non-woven article, preferably the sheet, is curved, it is preferred that when the non-woven article is placed on a flat surface, the shortest distance between the non-woven article and the flat surface is at least 1 cm, preferably at least 10 cm at at least one location across the surface of the non-woven article. The nonwoven structure may be substantially riigid, such that the sheet may be a substantially rigid sheet.

[0092] It is particularly preferred that the nonwoven structure is prepared by means of heat- and pressure bonding, for example as described hereinafter.Process for preparing the nonwoven structure of the invention

[0093] A second aspect of the invention relates to a process for preparing a nonwoven structure, preferably a nonwoven structure as described herein earlier, said process comprising: a) providing an entangled plurality of staple fibres, said staple fibres comprising: i. a first polyolefin component, said first polyolefin component having a melting temperature of 130-170 °C; and ii. a second polyolefin component, wherein the melting temperature of the second polyolefin component is at least 10 °C higher than the melting temperature of the first polyolefin component; and wherein the entangled plurality of staple fibres comprises at least 90 wt.% polyolefin staple fibres, by total weight of the entangled plurality of staple fibres, preferably at least 95 wt.%, more preferably at least 99 wt.%; and b) at least partially bonding the entangled plurality of staple fibres by heating to a temperature sufficiently high to melt the first polyolefin component, but not substantially the second polyolefin component, and preferably applying pressure while the first polyolefin component is in a molten state.

[0094] The nonwoven structure produced by the process of the invention is preferably the nonwoven structure described herein earlier. Thus, the plurality of staple fibres provided in step (a) of the process according to the invention is preferably as described herein before. The properties of the fibres described in the context of the nonwoven structure apply mutatis mutandis in the context of the entangled fibres before bonding.

[0095] In a preferred embodiment, step (b) comprises heating the plurality of staple fibres to a core temperature sufficiently high to melt the first polyolefin component, but not substantially the second polyolefin component. This ensures bonding throughout the nonwoven structure. Said core temperature is preferably 130-170 °C, preferably 130-155 °C. It is important that the second polyolefin component, with a higher melting temperature, remains in a solid state throughout the process. This ensures that the nonwoven structure retains its integrity and does not lose its shape or structural integrity during the bonding process. The core temperature refers to the temperature of the core of the plurality of staple fibres, for example at half the thickness of the plurality of staple fibres.

[0096] The methods for applying heat to melt the first polyolefin component are not particularly limited. For example, ultrasonic radiation, contact heating (e.g. by heated rollers), heated air, infrared radiation, etc. may be used.

[0097] During the bonding process, pressure is preferably applied to the staple fibres. The pressure is preferably maintained at least until the first polyolefin component has solidified, resulting in a nonwoven structure with bonded fibres. Pressure may be applied by any means known to the skilled person, including compression moulding, calendering or double belt pressing (e.g. using Teflon or steel belts).

[0098] In accordance with preferred embodiments, the heat- and pressure bonding of step (b) preferably occurs at a pressure that is at least 10 bar. More preferably, the pressure for the heat- and pressure bonding is at least 20 bar. Still more preferably, the pressure for the heat- and pressure bonding is at least 30 bar, yet more preferably at least 40 bar. These pressures contribute to a firm entanglement and bonding, resulting in a strong and durable nonwoven structure.

[0099] Preferably, the plurality of entangled staple fibres are maintained at a temperature sufficiently high to melt the first polyolefin component, but not substantially the second polyolefin component, for a period of at least 30 seconds, preferably at least 60 seconds, still more preferably at least 90 seconds. Preferably, pressure is applied to the plurality of entangled staple fibres for at least 30 seconds. More preferably, at least 60 seconds.

[0100] In the process described above, heat- and pressure bonding preferably takes place in a mould and is also referred to as compression moulding. The mould is typically made of a heat-resistant material such as metal or ceramic and has a specific shape and size to provide the desired shape of the nonwoven structure once bonded. The mould may also have a textured surface to create a pattern or design on the nonwoven structure.

[0101] The mould used in the preferred process according to the invention is preferably curved such that the resulting nonwoven structure comprises one or more curves, i.e. it is not flat. When the non-woven article (preferably the sheet) is curved, this preferably means that when the non-woven article is placed on a flat surface, the shortest distance between the non-woven article and the flat surface is at least 1 cm, preferably at least 10 cm at at least one location across the surface of the non-woven article.Nonwoven structure obtainable by the process

[0102] Another aspect of the present invention is a nonwoven structure obtainable by the process described herein.

[0103] Preferably, said nonwoven structure is a nonwoven structure as described hereinbefore.Uses of the nonwoven structure

[0104] A final aspect of the present invention pertains to the use of a nonwoven structure of the invention. The nonwoven structure may be used for various mechanically demanding applications. The inventors have found that the nonwoven structure is useful amongst others in a vehicle part. The vehicle part, in this context, can be any component or element of a vehicle that is suitable for the incorporation of the nonwoven structure.

[0105] In one embodiment, the vehicle part is an air duct intake. In another embodiment, the vehicle part may be a rear parcel shelf. The use also encompasses a vehicle part that is a bumper. In yet another embodiment, the use further may comprise a vehicle part that is an underbody shield.

[0106] In a particularly preferred embodiment, the nonwoven structure according to the present invention is used as a wheel arch liner. The wheel arch liner is a component that is typically installed inside the wheel arch of a vehicle to protect the wheel well and other internal components from debris, water, and other external elements. As mentioned above, the nonwoven structure is excellently suited for this application due to its mechanical properties, wherein a light weight is combined with high strength and recyclability. In addition to this, the nonwoven structures made solely of polyolefin components may provide advantageous acoustic and water-repellent properties.

[0107] The invention is further illustrated by the following non-limiting examples.Examples Example 1

[0108] Several sheets of entangled staple fibres are prepared by needling according to the compositions described in Table 1. The sheets had a surface of 30x30 cm. Table 1 Sample Fibre 1 Fibre 1 wt.% Fibre 1 dtex Fibre 2 Fibre 2 wt.% Fibre 2 dtex Fibre 3 Fibre 3 wt.% Fibre 3 dtex Comparative APolypropylene homopolymer406.7PET homopolymer603.3---1Bicomponent fibre 1< (70 / 30)5011Polypropylene homopolymer5077---2Bicomponent fibre 1< (70 / 30)4011Polypropylene homopolymer1011Polypropylene homopolymer50773Bicomponent fibre' (70 / 30)405.5Polypropylene homopolymer105.5Polypropylene homopolymer50114Bicomponent fibre (70 / 30)1006.75Bicomponent fibre' (50 / 50)1006.76Polypropylene homopolymer 2< 506.7Polypropylene homopolymer506.77Polypropylene homopolymer 2< 406.7Polypropylene homopolymer606.7 1< Bicomponent fibre consisting of 70 wt.% polypropylene with a melting temperature of 165 °C (high-melting polypropylene homopolymer component) and 30 wt.% polypropylene copolymer with a melting temperature of 140 °C (low-melting polypropylene component). 2< Polypropylene homopolymer having a reduced melting point compared to the polypropylene homopolymer employed in fibre 2

[0109] The entangled staple fibre sheets of the above table were bonded to prepare bonded nonwoven structures as follows: The sheets were clamped in a stenter with springs. The clamped sheets were heated using infrared heaters to a core temperature above the melting temperature of the low-melting polypropylene component, but below the melting temperature of the high-melting polypropylene component. The samples were kept at this temperature for > 60 seconds The samples were then placed in a 30 cm x 30 cm mould, and pressure is applied with a press. The resulting samples are analysed in terms of their stress at break and modulus according to method ISO 527-4:2023.

[0110] The results of the mechanical analyses are shown in tables 2 and 3. The stress at break and modulus were normalized for density by dividing them by the value of the density expressed in g / cm 3< . Table 2 Sample Surface density (g / m 2< ) Porosity (%) Thickness (mm) Density (g / cm 3< ) A740320940.7871840511.880.4472900511.880.4463900501.960.4954573561.410.4075644491.370.4716609481270.4787608481.270.478 Sample Stress at break (MPa) Modulus (MPa) Normalized Stress at break (MPa) Normalized modulus (MPa) A32.5411.341.29522118.8425.242.06950219.4570.443.531278322.5595.245.571204418.67265.745.92653518.90383.740.30815623.28627.348.681312723.76533.849.651116

[0111] As can be seen from the tables above, the nonwoven structures according to the invention have excellent mechanical properties. In particular, the normalized modulus is much higher than the PP / PET reference material, meaning that improved mechanical properties can be obtained with less material consumption.

Examples

example 1

Example 1

[0108]Several sheets of entangled staple fibres are prepared by needling according to the compositions described in Table 1. The sheets had a surface of 30x30 cm.

Table 1

Sample Fibre 1 Fibre 1 wt.% Fibre 1 dtex Fibre 2 Fibre 2 wt.% Fibre 2 dtex Fibre 3 Fibre 3 wt.% Fibre 3 dtex

Comparative APolypropylene homopolymer406.7PET homopolymer603.3---

1Bicomponent fibre 15011Polypropylene homopolymer5077---

2Bicomponent fibre 14011Polypropylene homopolymer1011Polypropylene homopolymer5077

3Bicomponent fibre' (70 / 30)405.5Polypropylene homopolymer105.5Polypropylene homopolymer5011

4Bicomponent fibre (70 / 30)1006.7

5Bicomponent fibre' (50 / 50)1006.7

6Polypropylene homopolymer 2506.7Polypropylene homopolymer506.7

7Polypropylene homopolymer 2406.7Polypropylene homopolymer606.7

1

[0109]The entangled staple fibre sheets of the above table were bonded to prepare bonded nonwoven structures as follows:

The sheets were clamped in a stenter with springs. The clamped sheets were heated u...

Technical field

[0001] The present invention relates to a polyolefin-based recyclable nonwoven structure, methods for its production and uses thereof.Background of the invention

[0002] The use of nonwoven structures in various industries has become firmly established. These structures, which are typically composed of bonded and entangled fibres, offer a wide range of desirable properties including strength, durability, and flexibility. They are commonly utilized in various sectors such as healthcare, automotive, and construction, among others.

[0003] However, it is widely recognized that nonwovens made from a single type of polymer often lack sufficient mechanical strength, flexibility, or resistance to chemicals or heat. To address these shortcomings, nonwoven composites, which consist of at least two different types of polymers, are frequently employed. These composites achieve improved properties through the synergistic effects of combining polymers. Examples include PP / PET nonwoven composites and PET / coPET nonwoven composites.

[0004] Despite their extensive use in various industries, in particular the automotive industry, the aforementioned nonwoven composites do have certain limitations. Composites comprising multiple types of chemically unrelated polymers (such as PP and PET) pose significant challenges in terms of recycling. Consequently, they often end up as landfill or are incinerated. In light of the growing emphasis on adopting sustainable practices, this approach no longer aligns with the sustainability goals of most companies and countries.

[0005] While single-polymer products produced through injection moulding may be used, these tend to exhibit considerable weight, which is a notable drawback compared to nonwovens. This drawback is particularly inconvenient in the automotive sector, where the current focus is on constructing lightweight vehicles to reduce fuel consumption and increase the driving range of electric vehicles.

[0006] DE102020114941A1 discloses a method for producing a wheel arch liner for vehicles, incorporating a process involving thermoforming a nonwoven semi-finished product made of high- and low-melting thermoplastic fibres.

[0007] WO2016026875A1 discloses a method for manufacturing lightweight, durable luggage articles, specifically luggage shells, using a compacted, nonwoven sheet comprising randomly oriented, discontinuous reinforcing plastic fibres with a high melting point and randomly oriented discontinuous melting plastic fibres with a lower melting point.

[0008] It is an object of the present invention to provide nonwoven materials suitable for use in challenging mechanical applications (e.g. a wheel arch liner), which have improved recyclability, exhibit improved mechanical or acoustic properties and / or have a reduced weight.Summary of the invention

[0009] The inventors have discovered that a predominantly polyolefin nonwoven structure can be prepared, which combines good recyclability with excellent mechanical properties. The product can be provided with a low density while maintaining mechanical properties even at low thicknesses (and thus surface densities), such that even challenging mechanical applications (e.g. use in wheel arch liners) are viable utilizing a very low weight of nonwoven. These polyolefin based nonwoven materials have the further advantage of possessing excellent chemical resistance, hydrophobicity and durability due to their high polyolefin content.

[0010] Accordingly, a first aspect of the invention concerns a nonwoven structure comprising a plurality of entangled and bonded staple fibres, said nonwoven structure comprising: i. a first polyolefin component, said first polyolefin component having a melting temperature within the range of 130-170 °C; and ii. a second polyolefin component, wherein the melting temperature of the second polyolefin component is at least 10 °C higher than the melting temperature of the first polyolefin component, wherein said nonwoven structure comprises at least 90 wt.% polyolefin staple fibres, by total weight of the nonwoven structure, preferably at least 95 wt.%, more preferably at least 99 wt.%, and wherein the density of the nonwoven structure is within the range of 0.2-2 g / cm 3< , preferably within the range of 0.2-0.9 g / cm 3< , most preferably within the range of 0.2-0.8 g / cm 3< .

[0011] Preferably, the polyolefins in the first polyolefin component and the second polyolefin component each comprise at least 90 wt.%, by total weight of the polyolefin, of the same first polyolefin monomer. Preferably the first polyolefin monomer is propylene.

[0012] Preferably, the first and second polyolefin component are comprised in a first polyolefin staple fibre which is a multicomponent staple fibre, preferably a sheath-core-type bicomponent fibre wherein the second polyolefin component forms the core of the fibre and the first polyolefin component forms the sheath of the fibre.

[0013] In some embodiments, the nonwoven structure is provided comprising the first polyolefin staple fibres and third polyolefin staple fibres, said third staple fibres consisting of a third polyolefin component, wherein the third polyolefin staple fibre has a titer of 0.4-100 dtex, preferably 1-20 dtex, more preferably 2-15 dtex, and wherein the total combined amount of the first and third polyolefin staple fibres constitutes at least 80 wt.% of the nonwoven structure, preferably at least 90 wt.%, more preferably at least 95 wt.%, most preferably at least 99 wt.%. In this embodiment the weight ratio of first polyolefin fibre to third polyolefin fibre in the nonwoven structure is preferably in the range of 1:9 to 9:1, preferably in the range of 1:5 to 5:1, most preferably in the range of 1:2 to 2:1.

[0014] In some embodiments, the nonwoven structure is provided comprising the first polyolefin staple fibres, third polyolefin staple fibres, and fourth polyolefin staple fibres, wherein the third staple fibres consist of a third polyolefin component, and have a titer of 0.4-100 dtex, preferably 1-20 dtex, more preferably 2-15 dtex, wherein the fourth polyolefin staple fibres consist of a fourth polyolefin component, and have a titer which is at least 150% of the titer of the first polyolefin staple fibre, preferably at least 200% higher than the titer of the first polyolefin staple fibre, more preferably at least 300%. In this embodiment, the nonwoven structure preferably comprises: 25-60 wt.% of the first polyolefin staple fibres, by weight of the nonwoven structure, preferably 30-55 wt.%, more preferably 40-50 wt.%; 5-75 wt.% of the third polyolefin staple fibres, by weight of the nonwoven structure, preferably 7.5-70 wt.%, more preferably 10-60 wt.%; and 30-80 wt.% of the fourth polyolefin staple fibres, by weight of the nonwoven structure, preferably 40-75 wt.%, more preferably 40-70 wt.%.

[0015] The nonwoven structure is preferably a sheet, such as a sheet having a surface density within the range of 200-5000 g / m 2< , preferably within the range of 500-2000 g / m 2< , and / or a thickness within the range of 0.5-10 mm, preferably within the range of 1 and 7.5 mm, more preferably within the range of 1.5 to 5 mm.

[0016] The normalized modulus of the nonwoven structure is preferably higher than 750 MPa, more preferably higher than 900 MPa, more preferably higher than 1000 MPa , most preferably higher than 1150 MPa.

[0017] In another aspect, the invention provides a process of preparing a nonwoven structure, said process comprising: a) providing an entangled plurality of staple fibres, said staple fibres comprising: i. a first polyolefin component, said first polyolefin component having a melting temperature of 130-170 °C; and ii. a second polyolefin component, wherein the melting temperature of the second polyolefin component is at least 10 °C higher than the melting temperature of the first polyolefin component; and wherein the entangled plurality of staple fibres comprises at least 90 wt.% polyolefin staple fibres, by total weight of the entangled plurality of staple fibres, preferably at least 95 wt.%, more preferably at least 99 wt.%; and b) at least partially bonding the entangled plurality of staple fibres by heating to a temperature sufficiently high to melt the first polyolefin component, but not substantially the second polyolefin component, and preferably applying pressure while the first polyolefin component is in a molten state.

[0018] In another aspect, the invention provides a nonwoven structure obtainable by the process described herein.

[0019] In another aspect, the invention provides the use of a nonwoven structure according to the invention in a vehicle part, preferably a wheel arch liner, a door panel, an electric vehicle battery shield, an interior trim part, an air duct intake, a rear parcel shelf, a bumper or an underbody shield.Brief description of the figures

[0020] The present invention will now be described in more detail with reference to specific embodiments of the invention, given only by way of illustration, and with reference to the accompanying drawings. Figure 1 illustrates various configurations of bicomponent fibres, such as the preferred embodiments of the first polyolefin staple fibre described herein elsewhere. The exemplary configurations shown in Figure 1 include side-by-side, segmented pie, islands-in-the-sea, tipped, segmented ribbon and sheath-core bicomponent fibres. However, the designs presented in Figure 1 are not exhaustive of all possible configurations.Description of embodiments

[0021] The expression "comprise" and variations thereof, such as "comprises" and "comprising" as used herein, should be construed in an open, inclusive sense, meaning that the embodiment described includes the recited features, but that it does not exclude the presence of other features, as long as they do not render the embodiment unworkable.

[0022] The expressions "one embodiment", "a particular embodiment", "an embodiment" etc., as used herein, should be construed to mean that a particular feature, structure or characteristic described in connection with the embodiment is included in at least one embodiment. Thus, the appearances of such expressions in various places throughout this specification do not necessarily all refer to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. For example, certain features of the disclosure, which are described herein in the context of separate embodiments, are also explicitly envisaged in combination in a single embodiment.

[0023] The singular forms "a," "an," and "the" as used herein should be construed to include plural referents unless the content clearly dictates otherwise. It should also be noted that the term "or" is generally employed in its broadest sense, that is, as meaning "and / or" unless the content clearly dictates otherwise.

[0024] Numerical ranges expressed in the format "from x to y" are understood to include x and y.

[0025] When multiple preferred ranges are described in the format "from x to y" for a specific feature, it should be understood that all ranges combining the different endpoints are also contemplated.

[0026] If, for a particular component, a range of 0% to y% or less than y% is recited, said ingredient may be absent.

[0027] The term "molecular weight", as used herein, within the context of polymers, refers to the number-average molecular weight, preferably the number-average molecular weight as determined by gel permeation chromatography.

[0028] The staple fibres referred to herein may have been prepared via a multitude of methods, and the invention is not particularly limited in this regard. An example of a suitable method is melt spinning. The staple fibres can be solid or hollow, be round or shaped, e.g. multilobal such as trilobal. Preferably, the staple fibres are round.

[0029] The term "polyolefin", as used herein, encompasses all forms of polyolefins, including different forms of stereoisomers (isotactic, atactic, syndiotactic) and is not particularly limited by the average molecular weight of the polyolefin. Preferred molecular weights are set out herein elsewhere

[0030] The term "polyolefin component" as used herein refers to a plastic material comprising a majority (by weight) of polyolefin, but does not exclude the presence of additives which are commonly used in plastics such as antimicrobial agents (such as zinc oxide), plasticizers (such as phthalates, polymeric- and non-polymer plasticizers and adipates), flame retardants (such as aluminum trihydrate), fillers (such as fly ash, bottom ash, aluminum silicate, aluminum hydroxide, calcium silicate, magnesium silicate, dolomite, calcium carbonate, barium sulfate, calcium sulfate, hollow glass microspheres, soot, chalk, siloxanes or silica), reinforcers (such as glass fibers or minerals), pigments (such as carbon black) and / or UV stabilizers. Preferably the polyolefin components referred to herein comprise at least 75 wt.% polyolefin, by total weight of the polyolefin component, preferably at least 80 wt.%. Preferably the polyolefin components referred to herein comprise at least 95 wt.% polyolefin, by total weight of polymers in the polyolefin component, preferably at least 98 wt.%, more preferably at least 99 wt.%, such as 100 wt.%.

[0031] The "melting temperature", as used herein, is determined according to ISO 11357-3, preferably on a DSC Q2000 instrument by TA Instruments. In the context of the present invention, the melting temperature refers to the peak of the melting range of a polymer of the second heating when applying the following temperature protocol under a nitrogen atmosphere: heating from 25 to 200 °C at a rate of 10 °C / min; maintaining 200 °C for two minutes; cooling from 200 to -20 °C at a rate of 10 °C / min; maintaining -20 °C for three minutes; heating from -20 °C to 200 °C at a rate of 10 °C / min.

[0032] The term "titer", as used herein, refers to the linear density of the staple fibre as determined according to ISO 1973:2021, preferably on a Favimat+ by TexTechno.The nonwoven structure of the invention

[0033] A first aspect of the invention relates to a nonwoven structure comprising a plurality of entangled and bonded staple fibres, said nonwoven structure comprising: i. a first polyolefin component, said first polyolefin component having a melting temperature within the range of 130-170 °C; and ii. a second polyolefin component, wherein the melting temperature of the second polyolefin component is at least 10 °C higher than the melting temperature of the first polyolefin component, wherein said nonwoven structure comprises at least 90 wt.% polyolefin staple fibres, by total weight of the nonwoven structure, preferably at least 95 wt.%, more preferably at least 99 wt.%, and wherein the density of the nonwoven structure is within the range of 0.2-2 g / cm 3< , preferably within the range of 0.2-0.9 g / cm 3< , most preferably within the range of 0.2-0.8 g / cm 3< .

[0034] The density of the nonwoven structure may be within the range of 0.25-1.8 g / cm 3< , within the range of 0.25-1.5 g / cm 3< , or within the range of 0.25-1.3 g / cm 3< . The present inventors have found that excellent mechanical performance can be achieved without requiring high densities, thus the density may be within the range of 0.20-0.85 g / cm 3< , within the range of 0.20-0.7 g / cm 3< , or within the range of 0.20-0.6 g / cm 3< . In some embodiments the density is within the range of 0.20-0.75 g / cm 3< , within the range of 0.25-0.6 g / cm 3< , or within the range of 0.3-0.55 g / cm 3< . In some embodiments the density is higher than 0.3 g / cm 3< , preferably higher than 0.4 g / cm 3< .

[0035] The plurality of staple fibres may have been entangled by a variety of methods. It is particularly preferred that the plurality of staple fibres have been entangled by needling or hydroentanglement, most preferably needling.

[0036] The entangled and bonded staple fibres of the nonwoven structure may have been bonded in a multitude of ways. Suitable methods known in the art include chemical and / or thermal bonding, with or without the application of pressure during bonding. However, the inventors found that highly preferably, the entangled staple fibres have been thermally bonded, even more preferably thermally bonded with the application of pressure during bonding (i.e. heat- and pressure-bonded). As is known to the skilled person, heat- and pressure bonding is also referred to as "compression moulding". The exertion of pressure during the thermal bonding process contributes to achieving various properties described herein, including the density and mechanical properties of the nonwoven structure.The polyolefins used in the nonwoven structure of the invention

[0037] The invention employs two polyolefin components having different melting temperatures and may employ further polyolefin components, as described herein elsewhere in more detail. As is known to the skilled person, various polyolefin components exist which have different melting temperatures. The melting temperature of polyolefin components is influenced by a multitude of factors including, but not limited to, the polyolefin method of synthesis (e.g., using a metallocene catalyst or Ziegler Natta catalyst), the polyolefin average molecular weight, the polyolefin stereoisomeric form, branching, crosslinking, the crystal structure, the use of fillers in the polyolefin component, processing applied to the polyolefin components (which include stretching or drawing down, annealing and crosslinking) etc. It is within the routine capabilities of the skilled person, based on the guidance provided in the present document, to determine the melting temperature of a polyolefin (typically, this information is provided by the manufacturer) and select polyolefin components which comply with the requirements of the nonwoven of the present invention.

[0038] In an embodiment of the invention, the polyolefin components described herein, in particular the first and / or second component are synthesized using a metallocene and / or Ziegler Natta catalyst. In one embodiment of the invention, the polyolefin components described herein, in particular the first and / or second component underwent stretching, annealing and / or crosslinking, preferably stretching and / or annealing.

[0039] The polyolefin in the polyolefin components employed in the present invention can be a homopolymer or a copolymer.

[0040] When the polyolefin is a copolymer, it is preferably a copolymer prepared from at least two monomers selected from the group consisting of C 2 -C 5 alkenes, preferably selected from the group consisting of C 2 -C 4 alkenes, most preferably selected from the group consisting of C 2 -C 3 alkenes. The copolymer may be selected from an alternating copolymer, a random copolymer, a block polymer or a graft copolymer, preferably a random copolymer.

[0041] In all embodiments of the invention, the polyolefin in the polyolefin components described herein preferably has a propylene content of at least 80 wt.%, more preferably at least 85 wt.%, still more preferably at least 90 wt.%. In case a copolymer as described herein is used, the amount of monomers other than propylene is preferably 0.5-10 wt.%, preferably 1-8 wt.%, most preferably 3-8 wt.%.

[0042] Thus, the polyolefins in the polyolefin components described herein (in particular the first and second polyolefin component) are preferably each independently selected from a polypropylene homopolymer; and a copolymer prepared from at least two monomers selected from the group consisting of C 2 -C 5 alkenes, preferably selected from the group consisting of C 2 -C 4 alkenes, most preferably selected from the group consisting of C 2 -C 3 alkenes, more preferably selected from a polypropylene homopolymer; and a copolymer having a propylene content of at least 80 wt.%, more preferably at least 85 wt.%, still more preferably at least 90 wt.%, and prepared from at least two monomers selected from the group consisting of C 2 -C 5 alkenes, preferably selected from the group consisting of C 2 -C 4 alkenes, most preferably selected from the group consisting of C 2 -C 3 alkenes, more preferably selected from a polypropylene homopolymer; and a copolymer having a propylene content of at least 90 wt.%, and prepared from at least two monomers selected from the group consisting of C 2 -C 3 alkenes (in other words, prepared from ethylene and propylene).

[0043] In some embodiments of the invention, the polyolefin in at least one of the first and second polyolefin components is a copolymer, preferably a random copolymer, prepared from at least two monomers selected from the group consisting of C 2 -C 5 alkenes, preferably selected from the group consisting of C 2 -C 4 alkenes, most preferably selected from the group consisting of C 2 -C 3 alkenes, and having a propylene content of at least 80 wt.%, more preferably at least 85 wt.%, still more preferably at least 90 wt.%. In some embodiments the polyolefin in at least one of the first and second polyolefin components is a copolymer, preferably a random copolymer, prepared from at least two monomers selected from the group consisting of C 2 -C 3 alkenes (in other words, prepared from ethylene and propylene), and having a propylene content of at least 90 wt.%. The amount of monomers other than propylene, preferably the amount of ethylene, is preferably 0.5-10 wt.%, preferably 1-8 wt.%, most preferably 3-8 wt.%.

[0044] In preferred embodiments of the invention, the polyolefin in at least one of the first and second polyolefin components is a copolymer, preferably a random copolymer, prepared from at least two monomers selected from the group consisting of C 2 -C 5 alkenes, preferably selected from the group consisting of C 2 -C 4 alkenes, most preferably selected from the group consisting of C 2 -C 3 alkenes, and having a propylene content of at least 80 wt.%, more preferably at least 85 wt.%, still more preferably at least 90 wt.%; and the polyolefin in at least one of the first and second polyolefin components is a polypropylene homopolymer, preferably the polyolefin in at least one of the first and second polyolefin components is a copolymer, preferably a random copolymer, prepared from at least two monomers selected from the group consisting of C 2 -C 3 alkenes, and having a propylene content of at least 90 wt.%, wherein the ethylene content is 0.5-10 wt.%, preferably 1-8 wt.%, most preferably 3-8 wt.%; and the polyolefin in at least one of the first and second polyolefin components is a polypropylene homopolymer.

[0045] In highly preferred embodiments of the invention, the polyolefin in the first polyolefin component is a copolymer, preferably a random copolymer, prepared from at least two monomers selected from the group consisting of C 2 -C 5 alkenes, preferably selected from the group consisting of C 2 -C 4 alkenes, most preferably selected from the group consisting of C 2 -C 3 alkenes, and having a propylene content of at least 80 wt.%, more preferably at least 85 wt.%, still more preferably at least 90 wt.%; and the polyolefin in the second polyolefin component is a polypropylene homopolymer, preferably the polyolefin in the first polyolefin component is a copolymer, preferably a random copolymer, prepared from at least two monomers selected from the group consisting of C 2 -Cs alkenes, and having a propylene content of at least 90 wt.%, wherein the ethylene content is 0.5-10 wt.%, preferably 1-8 wt.%, most preferably 3-8 wt.%; and the polyolefin in the second polyolefin component is a polypropylene homopolymer.

[0046] In preferred embodiments of the invention, the polyolefins in the first polyolefin component and the second polyolefin component each comprise at least 90 wt.%, by total weight of the polyolefin, of the same first polyolefin monomer. Preferably the first polyolefin monomer is selected from the group consisting of C 2 -C 5 alkenes, preferably selected from the group consisting of C 2 -C 4 alkenes, most preferably propylene. In other words, the propylene content of the polyolefins in the first polyolefin component and the second polyolefin component is preferably at least 90 wt.%.

[0047] As will be understood by the skilled person, the monomer contents referred to herein refers to the amount of said monomer relative to the total monomers used in the preparation of the polyolefin.

[0048] In a preferred embodiment, the polyolefin components referred to herein have a numberaveraged molecular weight of 10-100 kDa, preferably 20-90 kDa.

[0049] The melting temperature of the first polyolefin component is preferably in the range of 130-160 °C, most preferably in the range of 135-160 °C. The melting temperature of the second polyolefin component is preferably within the range of 140-180 °C, more preferably in the range of 140-170 °C, most preferably in the range of 150-170 °C, with the proviso that the melting temperature of the second polyolefin component is at least 10 °C higher than the melting temperature of the first polyolefin component.

[0050] The polyolefin comprised in the polyolefin components referred to herein may be recycled.Preferred staple fibres used in the nonwoven structures of the invention

[0051] As will be understood by the skilled person, whenever it is mentioned herein that the nonwoven comprises a certain staple fibre, this should be construed to mean that the nonwoven comprises a plurality of said staple fibres since a nonwoven typically employs thousands of fibre particles collectively referred to as a certain staple fibre.

[0052] The first polyolefin component and the second polyolefin component can be present in the nonwoven structure in the same or in different staple fibres. Thus, the first and / or second polyolefin component are comprised in a first polyolefin staple fibre.

[0053] In preferred embodiments, the first polyolefin staple fibre comprises at least 90 wt.% of the first and / or second polyolefin component by weight of the first polyolefin staple fibre, preferably at least 95 wt.%, still more preferably at least 99 wt.%. Most preferably, the first polyolefin staple fibre is a polyolefin staple fibre consisting essentially of the first and / or second polyolefin component.

[0054] In preferred embodiments, the first polyolefin staple fibre has a titer of 0.4-100 dtex, preferably 1-20 dtex, more preferably 2-15 dtex.

[0055] The first polyolefin staple fibre preferably has an average length in the range of 10-200 mm, more preferably in the range of 20-150 mm, most preferably in the range of 30-100 mm.

[0056] In an embodiment of the invention, the first polyolefin staple fibre comprises the first polyolefin component, and the nonwoven structure further comprises a second polyolefin staple fibre comprising the second polyolefin component. In this embodiment, the first polyolefin staple fibre preferably comprises at least 90 wt.% of the first polyolefin component by weight of the first polyolefin staple fibre, more preferably at least 95 wt.%, still more preferably at least 99 wt.%. Most preferably, the first polyolefin staple fibre is a polyolefin staple fibre consisting essentially of the first polyolefin component. Similarly, in this embodiment it is preferred that the second polyolefin staple fibre comprises at least 90 wt.% of the second polyolefin component by weight of the second polyolefin staple fibre, preferably at least 95 wt.%, still more preferably at least 99 wt.%. Most preferably, the second polyolefin staple fibre is a polyolefin staple fibre consisting essentially of the second polyolefin component.

[0057] The second polyolefin staple fibre preferably has a titer in the range of 1-100 dtex, preferably in the range of 2.5-90 dtex, most preferably, the second polyolefin staple fibre has a titer of 0.4-100 dtex, preferably 1-20 dtex, more preferably 2-15 dtex.

[0058] Similar to the first polyolefin staple fibre, the second polyolefin staple fibre preferably has an average length in the range of 10-200 mm, more preferably in the range of 20-150 mm, most preferably in the range of 30-100 mm.

[0059] In those embodiments wherein the second polyolefin fibre is present, the weight ratio of first polyolefin fibre to second polyolefin fibre in the nonwoven structure is preferably in the range of 1:1 to 1:9, more preferably in the range of 1:1 to 1:5, most preferably in the range of 1:1.5 to 1:4.

[0060] In a particularly preferred embodiment, the first polyolefin component and the second polyolefin component are both part of the first polyolefin staple fibre. In other words, it is particularly preferred that said first polyolefin staple fibre is a multicomponent staple fibre comprising the first polyolefin component and the second polyolefin component. Yet more preferably, the first polyolefin staple fibre is a multicomponent staple fibre comprising at least 90 wt.% of a combination of the first polyolefin component and the second polyolefin component by weight of the multicomponent staple fibre, preferably at least 95 wt.%, still more preferably at least 99 wt.%. Most preferably, the multicomponent staple fibre is a bicomponent staple fibre consisting essentially of the first and second polyolefin component.

[0061] Figure 1 shows non-limiting examples of various possible configurations of a bicomponent fibre. Examples of such configurations include sheath-core-type fibres, side-by-side-type fibres or matrix-fibril-type fibres, each of which may be further subdivided into additional types. Bicomponent staple fibres are known to the skilled person. In those embodiments described herein where the first polyolefin staple fibre is a bicomponent fibre, the first polyolefin staple fibre is preferably a sheath-core-type bicomponent fibre, wherein the second polyolefin component forms the core of the fibre and the first polyolefin component forms the sheath of the fibre. In this configuration, the core consisting of the second polyolefin component acts as a matrix to ensure the integrity of the nonwoven structure, whereas the sheath consisting of the first polyolefin component acts as a binding agent upon thermal bonding. The inventors found that this configuration is advantageous with a view to achieving a nonwoven structure consisting essentially of polyolefin components with excellent mechanical properties whilst maintaining a low weight and being fully recyclable.

[0062] In embodiments where the first polyolefin staple fibre is a bicomponent staple fibre, the weight ratio of the first polyolefin component to the second polyolefin component in the bicomponent staple fibre is preferably in the range of 1:1 to 1:9, more preferably in the range of 1:1 to 1:5, most preferably in the range of 1:1.5 to 1:4.

[0063] As will be understood by the skilled person, in those embodiments wherein the first fibre comprises both the first and second component, the second fibre may be used, but this is not necessary.

[0064] In a preferred embodiment, the nonwoven structure according to the present invention comprises 5-70 wt.% of the first polyolefin component by total weight of the nonwoven structure, preferably 10-30 wt.%, most preferably 12-20 wt.% and / or 5-95 wt.% of the second polyolefin component by total weight of the nonwoven structure, preferably 15-80 wt.%, most preferably 30-75 wt.%.

[0065] The nonwoven structure may further comprise a third polyolefin staple fibre, said third polyolefin staple fibre preferably comprising at least 90 wt.% of a third polyolefin component by weight of the third polyolefin staple fibre, at least 90 wt.%, still more preferably at least 99 wt.%. Most preferably, the third polyolefin staple fibre is a polyolefin staple fibre consisting essentially of the third polyolefin component.

[0066] The inclusion of the third staple fibre in the nonwoven structure can enhance the mechanical properties.

[0067] The third polyolefin component preferably has a melting temperature which is at least 10 °C higher than the melting temperature of the first polyolefin component, preferably within the range of 140-180 °C with the proviso that it is at least 10 °C higher than the melting temperature of the first polyolefin component.

[0068] In preferred embodiments, the third polyolefin staple fibre has a titer of 0.4-100 dtex, preferably 1-20 dtex, more preferably 2-15 dtex. The third polyolefin staple fibre preferably has an average length in the range of 10-200 mm, more preferably in the range of 20-150 mm, more preferably the third polyolefin staple fibre has an average length in the range of 30-100 mm.

[0069] The nonwoven structure may further comprise a fourth polyolefin staple fibre, said fourth polyolefin staple fibre preferably comprising at least 90 wt.% of a fourth polyolefin component by weight of the fourth polyolefin staple fibre, preferably at least 95 wt.%, still more preferably at least 99 wt.%. Most preferably, the fourth polyolefin staple fibre is a polyolefin staple fibre consisting essentially of the fourth polyolefin component.

[0070] The fourth polyolefin component preferably has a melting temperature at least 10 °C higher than the first polyolefin component, preferably within the range of 140-180 °C with the proviso that it is at least 10 °C higher than the melting temperature of the first polyolefin component.

[0071] The inventors found that a lightweight nonwoven structure with excellent mechanical properties, such as stress at break or modulus may be provided when a fourth fibre is used and the titer of the fourth polyolefin staple fibres is significantly higher than the titer of the first fibre, whilst still maintaining favourable flexibility, making the nonwoven structure suitable for a multitude of applications. Thus, the use of a fourth fibre is highly preferred. In those embodiments where a fourth fibre is used, the second and / or third fibre may be used, but this is not necessary.

[0072] It is particularly preferred that the fourth polyolefin staple fibre has a titer which is at least 150% of the titer of the first polyolefin staple fibre, preferably at least 200% higher than the titer of the first polyolefin staple fibre, more preferably at least 300%. Preferably, the fourth polyolefin staple fibres have a titer in the range of 10-100 dtex, more preferably in the range of 25-90 dtex, most preferably, in the range of 50-80 dtex.

[0073] The fourth polyolefin staple fibre preferably has an average length in the range of 10-200 mm, more preferably in the range of 20-150 mm. Most preferably, the fourth polyolefin staple fibre has an average length in the range of 30-100 mm.

[0074] As will be understood based on the above, the nonwoven comprises the first polyolefin staple fibres described herein and optionally comprises the second, third and fourth polyolefin staple fibres described herein. In all embodiments, it is preferred that the first, second, third and fourth polyolefin staple fibres each have an average length in the range of 10-200 mm, more preferably in the range of 20-150 mm, most preferably in the range of 30-100 mm; and the first, second and third polyolefin staple fibres have a titer of 0.4-100 dtex, preferably 1-20 dtex, more preferably 2-15 dtex; and the fourth polyolefin staple fibres have a titer in the range of 10-100 dtex, more preferably in the range of 25-90 dtex, most preferably, in the range of 50-80 dtex. Preferred combinations of the different staple fibres used in the nonwovens of the invention

[0075] The nonwoven structure according to the present invention can consist of various combinations of the four staple fibres mentioned hereinbefore. The total combined amount of the first, second, third and fourth fibres employed in the nonwoven structure of the present invention cannot exceed 100 wt.%.

[0076] In one embodiment, the nonwoven structure is provided comprising the first polyolefin staple fibre and optionally the second polyolefin staple fibre wherein the total combined amount of the first and second polyolefin staple fibres constitutes at least 80 wt.% of the nonwoven structure, preferably at least 90 wt.%, more preferably at least 95 wt.%, most preferably at least 99 wt.%. In an embodiment the first polyolefin staple fibres are bicomponent fibres are described hereinbefore. In this embodiment the nonwoven structure may be free of the second polyolefin staple fibres (and thus consist essentially of the first staple fibres) or it may comprise the second polyolefin staple fibres. In another embodiments both the first and second polyolefin staple fibres are homopolymer fibres, such as polypropylene homopolymer fibres, and the nonwoven structure comprises both the first and second polyolefin staple fibres. The weight ratio of first polyolefin fibre to second polyolefin fibre in the nonwoven structure may be in the range of 9:1 to 1:9, such as in the range of 5:1 to 1:5. When the first polyolefin staple fibres are bicomponent fibres as described herein before and the nonwoven structure comprises the second polyolefin staple fibres, it is preferred that the weight ratio of first polyolefin fibre to second polyolefin fibre in the nonwoven structure is in the range of 1:1 to 1:9, more preferably in the range of 1:1 to 1:5, most preferably in the range of 1:1.5 to 1:4. When both the first and second polyolefin staple fibres are homopolymer fibres, such as polypropylene homopolymer fibres, and the nonwoven structure comprises both the first and second polyolefin staple fibres, it is preferred that the weight ratio of first polyolefin fibre to second polyolefin fibre in the nonwoven structure is in the range of 5:1 to 1:5, more preferably in the range of 2:1 to 1:2, most preferably in the range of 1.5:1 to 1:1.5.

[0077] In another embodiment, the nonwoven structure is provided comprising the first and third polyolefin staple fibres, wherein the total combined amount of the first and third polyolefin staple fibres constitutes at least 80 wt.% of the nonwoven structure, preferably at least 90 wt.%, more preferably at least 95 wt.%, most preferably at least 99 wt.%, wherein the first polyolefin staple fibres are preferably bicomponent fibres are described hereinbefore. In this embodiment it is preferred that the weight ratio of first polyolefin fibre to third polyolefin fibre in the nonwoven structure is in the range of 1:9 to 9:1, preferably in the range of 1:5 to 5:1, most preferably in the range of 1:2 to 2:1.

[0078] In another embodiment, the nonwoven structure is provided comprising the first, second and third polyolefin staple fibres, wherein the first polyolefin staple fibres preferably are bicomponent fibres are described hereinbefore. In this embodiment, the nonwoven structure preferably comprises: 5-50 wt.% of the first polyolefin staple fibres, by weight of the nonwoven structure, preferably 20-45 wt.%, more preferably 25-40 wt.%; 10-90 wt.% of the second polyolefin staple fibres, by weight of the nonwoven structure, preferably 15-80 wt.%, more preferably 20-70 wt.%; and 10-90 wt.% of the third polyolefin staple fibres, by weight of the nonwoven structure, preferably 15-80 wt.%, more preferably 20-70 wt.%. wherein the total combined amount of the first, second and third polyolefin staple fibres constitutes at least 80 wt.% of the nonwoven structure, preferably at least 90 wt.%, more preferably at least 95 wt.%, most preferably at least 99 wt.%.

[0079] In another embodiment, the nonwoven structure is provided comprising the first and fourth polyolefin staple fibres, wherein the total combined amount of the first and fourth polyolefin staple fibres constitutes at least 80 wt.% of the nonwoven structure, preferably at least 90 wt.%, more preferably at least 95 wt.%, most preferably at least 99 wt.%, wherein the first polyolefin staple fibres are preferably bicomponent fibres are described hereinbefore. In this embodiment, it is preferred that the weight ratio of first polyolefin fibre to fourth polyolefin fibre in the nonwoven structure is in the range of 1:9 to 9:1, preferably in the range of 1:5 to 5:1, most preferably, in the range of 1:2 to 2:1.

[0080] In another embodiment, the nonwoven structure is provided comprising the first, second and fourth polyolefin staple fibres, wherein the first polyolefin staple fibres preferably are bicomponent fibres are described hereinbefore. In this embodiment, the nonwoven structure preferably comprises: 5-50 wt.% of the first polyolefin staple fibres, by weight of the nonwoven structure, preferably 20-45 wt.%, more preferably 25-40 wt.%; 10-90 wt.% of the second polyolefin staple fibres, by weight of the nonwoven structure, preferably 15-80 wt.%, more preferably 20-70 wt.%; and 10-90 wt.% of the fourth polyolefin staple fibres, by weight of the nonwoven structure, preferably 15-80 wt.%, more preferably 20-70 wt.%. wherein the total combined amount of the first, second and fourth polyolefin staple fibres constitutes at least 80 wt.% of the total weight of the nonwoven structure, preferably at least 90 wt.%, more preferably at least 95 wt.%, most preferably at least 99 wt.%.

[0081] In a particularly preferred embodiment, the nonwoven structure is provided comprising the first, third and fourth polyolefin staple fibres, wherein the first polyolefin staple fibres preferably are bicomponent fibres are described hereinbefore. In this embodiment, the nonwoven structure preferably comprises: 25-60 wt.% of the first polyolefin staple fibres, by weight of the nonwoven structure, preferably 30-55 wt.%, more preferably 40-50 wt.%; 5-75 wt.% of the third polyolefin staple fibres, by weight of the nonwoven structure, preferably 7.5-70 wt.%, more preferably 10-60 wt.%; and 30-80 wt.% of the fourth polyolefin staple fibres, by weight of the nonwoven structure, preferably 40-75 wt.%, more preferably 40-70 wt.%. wherein the total combined amount of the first, third and fourth polyolefin staple fibres constitutes at least 80 wt.% of the total weight of the nonwoven structure, preferably at least 90 wt.%, more preferably at least 95 wt.%, most preferably at least 99 wt.%.

[0082] Whilst the nonwoven structure may comprise further components such as further layers or skin (e.g. a textile woven, a spunbond nonwoven layer, a film layer, local reinforcements,...), accordance with the invention the nonwoven structure comprises at least 90 wt.% polyolefin staple fibres, by total weight of the nonwoven structure, preferably at least 95 wt.%, more preferably at least 99 wt.%, such as 100 wt.%. However it will be understood that the nonwoven structure may be employed in an assembly where the nonwoven structure is combined with further layers or skins, for example by providing a textile layer on an outside surface of the nonwoven structure.

[0083] While small amounts of other polymers will be tolerated during recycling, to optimize recycling of the nonwoven structure it is preferred that the nonwoven structure contains little to no polymers other than polyolefins. Thus, it is preferred that the nonwoven structure comprises less than 10 wt.% of polymers other than polyolefins, by total weight of the nonwoven structure, preferably less than 5 wt.%, more preferably less than 1 wt.%, most preferably essentially none.Mechanical properties of the nonwoven structure of the invention

[0084] The nonwoven structure, as described herein, can be provided having excellent mechanical properties at a low density and thickness (leading to a low surface density).

[0085] In a particularly preferred embodiment, the nonwoven structure according to the invention has a normalized stress at break higher than 40 MPa, preferably higher than 42 MPa, more preferably higher than 43 MPa, most preferably higher than 44.5 MPa. The "normalized stress at break" referred to herein concerns the stress as break which is normalized for density as follows: Normalized stress at break = stress at break density Wherein the density is entered as a dimensionless value corresponding to the value for density expressed in g / cm 3< . The stress at break is determined in accordance with the ISO 527-4:2023 standard.

[0086] The nonwoven structure of the invention can further be provided with a high modulus. The normalized modulus of the nonwoven structure is preferably higher than 750 MPa, more preferably higher than 900 MPa, more preferably higher than 1000 MPa, most preferably higher than 1150 MPa. The "normalized modulus" referred to herein concerns the modulus which is normalized for density as follows: Normalized modulus = modulus density Wherein the density is entered as a dimensionless value corresponding to the value for density expressed in g / cm 3< . The modulus is determined in accordance with the ISO 527-4:2023 standard.

[0087] As mentioned previously, one of the benefits of a nonwoven structure according to the invention is that said nonwoven structure is surprisingly light, despite its excellent mechanical properties. Thus, it is particularly advantageous in the form of a sheet, such as a sheet having a low surface density. Accordingly, the nonwoven structure preferably has a surface density within the range of 200-5000 g / m 2< , preferably within the range of 500-2000 g / m 2< .

[0088] The thickness of the nonwoven structure may be varied depending on the use of said nonwoven structure. The thickness of the nonwoven structure is preferably within the range of 0.5-10 mm, preferably within the range of 1 and 7.5 mm, more preferably within the range of 1.5 to 5 mm.

[0089] Thus, in some preferred embodiments of the invention, the nonwoven structure is provided in the form of a sheet, preferably a sheet having a surface density within the range of 200-5000 g / m 2< , preferably within the range of 500-2000 g / m 2< , and / or a thickness within the range of 0.5-10 mm, preferably within the range of 1 and 7.5 mm, more preferably within the range of 1.5 to 5 mm.

[0090] The sheet preferably has a ratio of thickness (expressed in cm) to the surface area (expressed in cm 2< ) of one side of the sheet which is less than 0.01, preferably less than 0.005. As will be understood by the skilled person, the thickness is the smallest dimension of the sheet.

[0091] The sheet may be shaped or curved, as is the case for example when the sheet is shaped like a wheel arch liner. When the non-woven article, preferably the sheet, is curved this means that it is not flat. When the non-woven article, preferably the sheet, is curved, it is preferred that when the non-woven article is placed on a flat surface, the shortest distance between the non-woven article and the flat surface is at least 1 cm, preferably at least 10 cm at at least one location across the surface of the non-woven article. The nonwoven structure may be substantially riigid, such that the sheet may be a substantially rigid sheet.

[0092] It is particularly preferred that the nonwoven structure is prepared by means of heat- and pressure bonding, for example as described hereinafter.Process for preparing the nonwoven structure of the invention

[0093] A second aspect of the invention relates to a process for preparing a nonwoven structure, preferably a nonwoven structure as described herein earlier, said process comprising: a) providing an entangled plurality of staple fibres, said staple fibres comprising: i. a first polyolefin component, said first polyolefin component having a melting temperature of 130-170 °C; and ii. a second polyolefin component, wherein the melting temperature of the second polyolefin component is at least 10 °C higher than the melting temperature of the first polyolefin component; and wherein the entangled plurality of staple fibres comprises at least 90 wt.% polyolefin staple fibres, by total weight of the entangled plurality of staple fibres, preferably at least 95 wt.%, more preferably at least 99 wt.%; and b) at least partially bonding the entangled plurality of staple fibres by heating to a temperature sufficiently high to melt the first polyolefin component, but not substantially the second polyolefin component, and preferably applying pressure while the first polyolefin component is in a molten state.

[0094] The nonwoven structure produced by the process of the invention is preferably the nonwoven structure described herein earlier. Thus, the plurality of staple fibres provided in step (a) of the process according to the invention is preferably as described herein before. The properties of the fibres described in the context of the nonwoven structure apply mutatis mutandis in the context of the entangled fibres before bonding.

[0095] In a preferred embodiment, step (b) comprises heating the plurality of staple fibres to a core temperature sufficiently high to melt the first polyolefin component, but not substantially the second polyolefin component. This ensures bonding throughout the nonwoven structure. Said core temperature is preferably 130-170 °C, preferably 130-155 °C. It is important that the second polyolefin component, with a higher melting temperature, remains in a solid state throughout the process. This ensures that the nonwoven structure retains its integrity and does not lose its shape or structural integrity during the bonding process. The core temperature refers to the temperature of the core of the plurality of staple fibres, for example at half the thickness of the plurality of staple fibres.

[0096] The methods for applying heat to melt the first polyolefin component are not particularly limited. For example, ultrasonic radiation, contact heating (e.g. by heated rollers), heated air, infrared radiation, etc. may be used.

[0097] During the bonding process, pressure is preferably applied to the staple fibres. The pressure is preferably maintained at least until the first polyolefin component has solidified, resulting in a nonwoven structure with bonded fibres. Pressure may be applied by any means known to the skilled person, including compression moulding, calendering or double belt pressing (e.g. using Teflon or steel belts).

[0098] In accordance with preferred embodiments, the heat- and pressure bonding of step (b) preferably occurs at a pressure that is at least 10 bar. More preferably, the pressure for the heat- and pressure bonding is at least 20 bar. Still more preferably, the pressure for the heat- and pressure bonding is at least 30 bar, yet more preferably at least 40 bar. These pressures contribute to a firm entanglement and bonding, resulting in a strong and durable nonwoven structure.

[0099] Preferably, the plurality of entangled staple fibres are maintained at a temperature sufficiently high to melt the first polyolefin component, but not substantially the second polyolefin component, for a period of at least 30 seconds, preferably at least 60 seconds, still more preferably at least 90 seconds. Preferably, pressure is applied to the plurality of entangled staple fibres for at least 30 seconds. More preferably, at least 60 seconds.

[0100] In the process described above, heat- and pressure bonding preferably takes place in a mould and is also referred to as compression moulding. The mould is typically made of a heat-resistant material such as metal or ceramic and has a specific shape and size to provide the desired shape of the nonwoven structure once bonded. The mould may also have a textured surface to create a pattern or design on the nonwoven structure.

[0101] The mould used in the preferred process according to the invention is preferably curved such that the resulting nonwoven structure comprises one or more curves, i.e. it is not flat. When the non-woven article (preferably the sheet) is curved, this preferably means that when the non-woven article is placed on a flat surface, the shortest distance between the non-woven article and the flat surface is at least 1 cm, preferably at least 10 cm at at least one location across the surface of the non-woven article.Nonwoven structure obtainable by the process

[0102] Another aspect of the present invention is a nonwoven structure obtainable by the process described herein.

[0103] Preferably, said nonwoven structure is a nonwoven structure as described hereinbefore.Uses of the nonwoven structure

[0104] A final aspect of the present invention pertains to the use of a nonwoven structure of the invention. The nonwoven structure may be used for various mechanically demanding applications. The inventors have found that the nonwoven structure is useful amongst others in a vehicle part. The vehicle part, in this context, can be any component or element of a vehicle that is suitable for the incorporation of the nonwoven structure.

[0105] In one embodiment, the vehicle part is an air duct intake. In another embodiment, the vehicle part may be a rear parcel shelf. The use also encompasses a vehicle part that is a bumper. In yet another embodiment, the use further may comprise a vehicle part that is an underbody shield.

[0106] In a particularly preferred embodiment, the nonwoven structure according to the present invention is used as a wheel arch liner. The wheel arch liner is a component that is typically installed inside the wheel arch of a vehicle to protect the wheel well and other internal components from debris, water, and other external elements. As mentioned above, the nonwoven structure is excellently suited for this application due to its mechanical properties, wherein a light weight is combined with high strength and recyclability. In addition to this, the nonwoven structures made solely of polyolefin components may provide advantageous acoustic and water-repellent properties.

[0107] The invention is further illustrated by the following non-limiting examples.Examples Example 1

[0108] Several sheets of entangled staple fibres are prepared by needling according to the compositions described in Table 1. The sheets had a surface of 30x30 cm. Table 1 Sample Fibre 1 Fibre 1 wt.% Fibre 1 dtex Fibre 2 Fibre 2 wt.% Fibre 2 dtex Fibre 3 Fibre 3 wt.% Fibre 3 dtex Comparative APolypropylene homopolymer406.7PET homopolymer603.3---1Bicomponent fibre 1< (70 / 30)5011Polypropylene homopolymer5077---2Bicomponent fibre 1< (70 / 30)4011Polypropylene homopolymer1011Polypropylene homopolymer50773Bicomponent fibre' (70 / 30)405.5Polypropylene homopolymer105.5Polypropylene homopolymer50114Bicomponent fibre (70 / 30)1006.75Bicomponent fibre' (50 / 50)1006.76Polypropylene homopolymer 2< 506.7Polypropylene homopolymer506.77Polypropylene homopolymer 2< 406.7Polypropylene homopolymer606.7 1< Bicomponent fibre consisting of 70 wt.% polypropylene with a melting temperature of 165 °C (high-melting polypropylene homopolymer component) and 30 wt.% polypropylene copolymer with a melting temperature of 140 °C (low-melting polypropylene component). 2< Polypropylene homopolymer having a reduced melting point compared to the polypropylene homopolymer employed in fibre 2

[0109] The entangled staple fibre sheets of the above table were bonded to prepare bonded nonwoven structures as follows: The sheets were clamped in a stenter with springs. The clamped sheets were heated using infrared heaters to a core temperature above the melting temperature of the low-melting polypropylene component, but below the melting temperature of the high-melting polypropylene component. The samples were kept at this temperature for > 60 seconds The samples were then placed in a 30 cm x 30 cm mould, and pressure is applied with a press. The resulting samples are analysed in terms of their stress at break and modulus according to method ISO 527-4:2023.

[0110] The results of the mechanical analyses are shown in tables 2 and 3. The stress at break and modulus were normalized for density by dividing them by the value of the density expressed in g / cm 3< . Table 2 Sample Surface density (g / m 2< ) Porosity (%) Thickness (mm) Density (g / cm 3< ) A740320940.7871840511.880.4472900511.880.4463900501.960.4954573561.410.4075644491.370.4716609481270.4787608481.270.478 Sample Stress at break (MPa) Modulus (MPa) Normalized Stress at break (MPa) Normalized modulus (MPa) A32.5411.341.29522118.8425.242.06950219.4570.443.531278322.5595.245.571204418.67265.745.92653518.90383.740.30815623.28627.348.681312723.76533.849.651116

[0111] As can be seen from the tables above, the nonwoven structures according to the invention have excellent mechanical properties. In particular, the normalized modulus is much higher than the PP / PET reference material, meaning that improved mechanical properties can be obtained with less material consumption.

Examples

example 1

Example 1

[0108]Several sheets of entangled staple fibres are prepared by needling according to the compositions described in Table 1. The sheets had a surface of 30x30 cm.

Table 1

Sample Fibre 1 Fibre 1 wt.% Fibre 1 dtex Fibre 2 Fibre 2 wt.% Fibre 2 dtex Fibre 3 Fibre 3 wt.% Fibre 3 dtex

Comparative APolypropylene homopolymer406.7PET homopolymer603.3---

1Bicomponent fibre 15011Polypropylene homopolymer5077---

2Bicomponent fibre 14011Polypropylene homopolymer1011Polypropylene homopolymer5077

3Bicomponent fibre' (70 / 30)405.5Polypropylene homopolymer105.5Polypropylene homopolymer5011

4Bicomponent fibre (70 / 30)1006.7

5Bicomponent fibre' (50 / 50)1006.7

6Polypropylene homopolymer 2506.7Polypropylene homopolymer506.7

7Polypropylene homopolymer 2406.7Polypropylene homopolymer606.7

1

[0109]The entangled staple fibre sheets of the above table were bonded to prepare bonded nonwoven structures as follows:

The sheets were clamped in a stenter with springs. The clamped sheets were heated u...

Claims

1. A nonwoven structure comprising a plurality of entangled and bonded staple fibres, said nonwoven structure comprising: i. a first polyolefin component, said first polyolefin component having a melting temperature within the range of 130-170 °C; and ii. a second polyolefin component, wherein the melting temperature of the second polyolefin component is at least 10 °C higher than the melting temperature of the first polyolefin component, wherein the polyolefins in the first polyolefin component and the second polyolefin component each comprise at least 90 wt.%, by total weight of the polyolefin, of the same first polyolefin monomer; wherein said nonwoven structure comprises at least 90 wt.% polyolefin staple fibres, by total weight of the nonwoven structure, preferably at least 95 wt.%, more preferably at least 99 wt.%, and wherein the density of the nonwoven structure is within the range of 0.2-2 g / cm3, preferably within the range of 0.2-0.9 g / cm3, most preferably within the range of 0.2-0.8 g / cm3.

2. The nonwoven structure according to claim 1, wherein the first and / or second polyolefin component are comprised in a first polyolefin staple fibre, said first polyolefin staple fibre preferably having a titer of 0.4-100 dtex, preferably 1-20 dtex, more preferably 2-15 dtex.

3. The nonwoven structure according to claim 2 wherein the first polyolefin staple fibre consists of the first polyolefin component and wherein the nonwoven structure further comprises a second polyolefin staple fibre consisting of the second polyolefin component, wherein the second polyolefin staple fibre preferably has a titer of 0.4-100 dtex, preferably 1-20 dtex, more preferably 2-15 dtex.

4. The nonwoven structure according to any one of the previous claims having a density within the range of 0.20-0.6 g / cm3.

5. The nonwoven structure according to claim 4 wherein the first polyolefin staple fibre is a bicomponent fibre consisting of the first polyolefin component and the second polyolefin component, preferably a sheath-core-type bicomponent fibre wherein the second polyolefin component forms the core of the fibre and the first polyolefin component forms the sheath of the fibre.

6. The nonwoven structure according to any one of the previous claims, wherein the nonwoven structure the total combined amount of the first and second polyolefin staple fibres constitutes at least 80 wt.% of the nonwoven structure, preferably at least 90 wt%.

7. The nonwoven structure according to any one of the preceding claims, preferably according to any one of claims 4-6, wherein said nonwoven further comprises a third polyolefin staple fibre and / or a fourth polyolefin staple fibre wherein said third polyolefin staple fibre has a titer of 0.4-100 dtex, preferably 1-20 dtex, more preferably 2-15 dtex; and wherein said fourth polyolefin staple fibre has a titer of 10-100 dtex, preferably 25-90 dtex, more preferably 50-80 dtex.

8. The nonwoven structure according to any one of the preceding claims, wherein the polyolefins in the first and second polyolefin component are each independently selected from • a polypropylene homopolymer; and • a copolymer having a propylene content of at least 90 wt.%, and prepared from at least two monomers selected from the group consisting of C2-C5 alkenes, preferably selected from the group consisting of C2-C4 alkenes, most preferably selected from the group consisting of C2-C3 alkenes.

9. The nonwoven structure according to any one of the preceding claims, wherein the first and / or second polyolefin components are recycled.

10. The nonwoven structure according to any one of the preceding claims, wherein the nonwoven structure is provided in the form of a sheet having a surface density within the range of 200-5000 g / m2, preferably within the range of 500-2000 g / m2 and / or a thickness within the range of 0.5-10 mm, preferably within the range of 1 and 7.5 mm, more preferably within the range of 1.5 to 5 mm.

11. The nonwoven structure according to any one of the preceding claims, wherein the nonwoven structure is heat- and pressure-bonded.

12. The nonwoven structure according to any one of the preceding claims, wherein the nonwoven structure has a normalized modulus higher than 750 MPa, more preferably higher than 900 MPa, more preferably higher than 1000 MPa, most preferably higher than 1150 MPa.

13. Process for preparing a nonwoven structure according to any one of claims 1-12, said process comprising: a) providing an entangled plurality of staple fibres, said staple fibres comprising: i. a first polyolefin component, said first polyolefin component having a melting temperature of 130-170 °C; and ii. a second polyolefin component, wherein the melting temperature of the second polyolefin component is at least 10 °C higher than the melting temperature of the first polyolefin component; and wherein the entangled plurality of staple fibres comprises at least 90 wt.% polyolefin staple fibres, by total weight of the entangled plurality of staple fibres, preferably at least 95 wt.%, more preferably at least 99 wt.%; and b) at least partially bonding the entangled plurality of staple fibres by heating to a temperature sufficiently high to melt the first polyolefin component, but not substantially the second polyolefin component, and preferably applying pressure while the first polyolefin component is in a molten state.

14. Method of claim 13 wherein step (b) comprises compression moulding.

15. Use of the nonwoven structure according to any one of claims 1-12 in a vehicle part, said vehicle part preferably being a wheel arch liner, a door panel, an electric vehicle battery shield, an interior trim part, an air duct intake, a rear parcel shelf, a bumper or an underbody shield.

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