The present invention relates to a water-repellent fibre, a yarn, plied yarn or garment comprising a water-repellent fibre and a method of manufacturing a water-repellent fibre.

BACKGROUND

Yarns used in making clothing fabrics such as sportswear fabric often require a number of properties including being water repellent and oil repellent, being anti-stain or stain resistant, being lightweight and being abrasion resistant.

Typically, water repellency, oil repellency and anti -stain properties are provided by using a repellent surface coating such as a durable water repellent (DWR) coating applied to a fabric surface, in line with industry standards. DWR surface coatings are often made from perfluorinated compounds (PFCs) such as perfluorinated sulfonic acids (PFOS) and perfluorinated carboxylic acids (PFOA), or a silicone -based material.

However, PFCs are toxic and therefore PFC -based DWR coatings based on PFCs are harmful to the environment. In addition, DWR coatings wear away due to abrasion during use, resulting in a decrease in water repellency, oil repellency and anti -stain properties over time.

The present invention has been devised with the foregoing in mind.

SUMMARY OF INVENTION

According to a first aspect, there is provided a water-repellent fibre for a yarn and/or a fabric or textile. The fibre may comprise a hydrophobic material. The fibre may have or comprise a shape or configuration comprising one or more micro and/or nano -sized structures.

One or more micro and/or nano-sized structures may enhance or amplify the inherent characteristics (e.g., physical and/or chemical properties) of a material. In the case of a hydrophobic material (which is due to a low surface energy of the material) , the chemical property of hydrophobicity of the material may be enhanced by one or more micro and/or nano-sized structures. The one or more micro and/or nano-sized structures of the fibre may therefore enhance the inherent properties of the hydrophobic material of the fibre. In addition to hydrophobicity, other chemical properties that are commonly exhibited by materials with a low surface energy, such as oleophobicity, anti-stain properties and anti-fouling properties, may similarly be enhanced by one or more micro and/or nano-sized structures. That may result in a fibre having enhanced water repellent, oil repellent, anti-fouling and anti-stain properties without requiring a separate coating on a surface of the fibre. In addition, because the enhanced hydrophobic properties (and other enhanced properties such as oleophobicity, anti -stain and anti-fouling properties) of the fibre are not reliant on a surface coating which can be worn away due to abrasion, the enhanced hydrophobic properties of the fibre may be retained for an increased length of time. The fibre may be used to form fabrics and/or textiles and/or garments having enhanced hydrophobic performance without requiring a separate coating on the surface of the fabric and/or textile and/or garment. It will be appreciated that when referring to enhanced hydrophobic properties in this disclosure, reference is also made to other enhanced properties such as oleophobicity, anti-stain and anti-fouling properties.

The one or more micro and/or nano -sized structures may have or comprise a size of between substantially lOnm and substantially lOOpm, or between substantially 50nm and substantially 10pm, or between substantially lOOnm and substantially lpm. In principle, the smaller the structure(s), the greater the enhancement of the hydrophobic properties. However, the above size ranges may be an optimal size range providing an optimal balance between enhancement of hydrophobic properties and manufacturability.

The one or more micro and/or nano -sized structures may form at least a part of, or be located on, an outer surface of the fibre. The structures forming part of or being located on an outer surface of the fibre may ensure the structures are easily able to provide the enhanced hydrophobic properties when the fibres are brought into contact with a liquid.

The fibre may have or comprise a cross-sectional shape or configuration that forms or provides the one or more micro and/or nano-sized structures. The cross-sectional shape or configuration may be substantially uniform along at least a part of a length of the fibre or substantially a full length of the fibre. The one or more micro and/or nano-sized structures may each extend partially or substantially fully along a length of the fibre. The fibre may have or comprise a diameter of between substantially lOOnm and substantially 500pm. In this disclosure, the term diameter also encompasses a width and/or thickness of substantially non-circular fibres. The small radius of curvature of the outer surface of a fibre having a size in that range may enable the outer surface of the fibre to act as or provide a micro and/or nano -sized structure. That may provide the fibre with enhanced hydrophobic properties.

The one or more micro and/or nano-sized structures may be or comprise one or more projections from and/or recesses in an outer surface of the fibre. The fibre may have or comprise a cross-sectional shape or configuration that forms or provides the one or more projections and/or recesses. A height and/or depth of the one or more projections and/or recesses may be between substantially lOOnm and substantially 10pm. A height and/or depth of the one or more projections and/or recesses may be up to substantially 10% of a diameter or thickness of the fibre. A greater height and/or depth of the one or more projections and/or recesses may provide greater enhancement of the hydrophobic properties of the fibre. A fibre comprising an outer surface having a high radius of curvature in addition to one or more projections and/or recesses in the outer surface of the fibre may have a hierarchical surface structure that further enhances the hydrophobic properties of the fibre. The hierarchical surface structure may create one or more air pockets that prevent or inhibit water (or other liquids) from contacting the surface of the fibre.

The one or more micro and/or nano -sized structures may comprise a plurality of micro and/or nano-sized structures. The fibre may have or comprise a cross-sectional shape or configuration that forms or provides the plurality of structures. The fibre may have or comprise a multi-lobal cross-section (e.g., trilobal, quadlobal, pentalobal, hexalobal and so on). The fibre may have a star-shaped (e.g., a n-pointed star, where n is greater than or equal to 3) cross-section, a cross-shaped cross-section, a v-shaped cross-section, or a substantially flat or planar cross-section, although any suitable cross-sectional shape or configuration may be used. The cross-sectional shape or configuration (e.g., lobes, star points, cross arms, v arms) may at least partially form or define the micro and/or nano-sized structures, such as projections from and/or recesses in an outer surface of the fibre. The fibre may have between substantially 3 and substantially 50 micro and/or nano-sized structures, although any suitable number of structures may be used. In principle, the higher the number or density of micro and/or nano-sized structures, the greater the enhancement of the hydrophobic properties. However, that number of micro and/or nano-sized structures may provide an optimal balance between enhancement of hydrophobic properties and manufacturability.

A spacing between adjacent micro and/or nano -sized structures may be between substantially lOOnm and substantially 10pm, or between substantially lOOnm and substantially lpm. A smaller spacing between adjacent structures may provide greater enhancement of the hydrophobic properties of the fibre. A cross-section of the fibre may have a substantially regular shape. The structures may be distributed around a cross-section of the fibre substantially uniformly or homogeneously. For example, a substantially uniform or similar spacing may be provided between adjacent structures. Alternatively, a cross-section of the fibre may have a substantially irregular shape. The structures may be concentrated at one or more locations around a cross-section of the fibre. A spacing between the structures may be variable or non-uniform.

The hydrophobic material may be or comprise an oleophobic material. Oleophobic materials are inherently hydrophobic, due to oleophobicity requiring a lower surface energy than hydrophobicity.

The hydrophobic material may be or comprise a hydrophobic or oleophobic polymeric material. A polymeric material may be simple to manufacture into a fibre having or comprising one or more micro and/or nano-sized structures.

The fibre may be or comprise a mixture of the hydrophobic polymeric material and one or more other polymeric materials. The one or more other polymeric materials may not be or comprise hydrophobic polymeric materials, or may be or comprise one or more polymeric materials that are less hydrophobic than the hydrophobic polymeric material. The one or more other polymeric materials may be included to improve one or more other properties of the fibre, for example one or more mechanical properties such as tensile strength, elongation at break, stiffness or flexibility, temperature resistance, and/or one or more aesthetic properties such as colour etc.

The mixture may comprise or be arranged in a core -sheath structure, an island-in-sea structure or a random blend structure. In a core -sheath structure, the hydrophobic polymeric material may be or comprise or form the sheath and substantially surround the non-hydrophobic or less hydrophobic polymeric material(s) to form an outer surface of the fibre. Similarly, in an island-in-sea structure, the hydrophobic polymeric material may be or comprise or form the sea and substantially surround the non -hydrophobic or less hydrophobic polymeric material(s) to form an outer surface of the fibre. In a random blend, the hydrophobic polymeric material may form a greater proportion of an outer surface of the fibre than the non-hydrophobic or less hydrophobic polymeric material(s). That arrangement may occur naturally during formation of the fibre, or during post- formation annealing of the fibre. In either case the lower-surface energy of the hydrophobic polymeric material may cause the hydrophobic polymeric material in the random blend to diffuse towards an outer surface of the fibre. A random blend may comprise a higher proportion (e.g., by volume) of the hydrophobic polymeric material than the non-hydrophobic or less hydrophobic materials. Additionally or alternatively, the hydrophobic polymeric material and the one or more other polymeric materials in a random blend may have a similar melting point, or the hydrophobic polymeric material may have a lower melting point than the one or more other polymeric materials. One or more of those features may enable the lower surface energy hydrophobic polymeric material to more easily diffuse towards an outer surface of the fibre.

The mixture may comprise substantially 5% or more by volume of the hydrophobic polymeric material, or between substantially 60% and substantially 80% by volume of the hydrophobic polymeric material. The mixture may comprise up to substantially 95% by volume of the one or more other polymeric materials, or between substantially 20% and substantially 40% by volume of the one or more other polymeric materials.

The hydrophobic polymeric material may be or comprise a polymethylpentene polymer or polymethylpentene based material. Polymethylpentene inherently has a low surface energy, meaning that polymethylpentene is strongly hydrophobic and oleophobic. Polymethylpentene is also a thermoplastic polymer, which may enable easy processing of the material to form a fibre. Polymethylpentene also has a low density, which may result in a lightweight water-repellent fibre. Polymethylpentene also has a high melting point and good chemical resistance, making it suitable for use in a wide variety of applications. The polymethylpentene polymer may be or comprise a 4 -methyl- 1-pentene polymer. The polymethylpentene polymer may be or comprise a copolymer of 4 -methyl- 1-pentene with one or more a-olefins. The one or more a-olefins may each have or comprise between 2 and 20 carbon atoms.

Additionally or alternatively, the hydrophobic polymeric material may be or comprise one or more of an a-polyolefin (such as polypropylene, polyethylene, polybutylene, polybutene etc.), a polyester, a nylon, a thermoplastic polymer, a polysaccharide (such as cellulosic polymers, chitosan etc.) or a protein -based material.

According to a second aspect, there is provided a water-repellent yarn for a fabric or textile comprising at least one water-repellent fibre according to the first aspect. The yarn may be or comprise a plurality of fibres twisted together, wherein at least one of the fibres is a water-repellent fibre according to the first aspect.

The yarn may have or comprise a diameter of between substantially 200nm and substantially lOOOpm. The yarn may have or comprise between substantially 15 twists/m and substantially 2000 twists/m.

According to a third aspect, there is provided a water-repellent plied yarn for a fabric or textile comprising at least one water-repellent yarn according to the second aspect. The plied yarn may be or comprise a plurality of yarns twisted together, wherein at least one of the yarns is a water-repellent yarn according to the second aspect.

The plied yarn may have or comprise a diameter of between substantially 400nm and substantially 5000pm. The plied yarn may have or comprise between substantially 15 twists/m and substantially 2000 twists/m.

According to a fourth aspect, there is provided a fabric or textile comprising at least one water-repellent fibre according to the first aspect, and/or at least one water-repellent yarn according to the second aspect and/or at least one waterproof plied yarn according to the third aspect.

The fabric or textile may be woven. The at least one water-repellent fibre, at least one water-repellent yarn and/or at least one water-repellent plied yarn may form or provide one or more warp threads and/or one or more weft threads of the fabric or textile. Alternatively, the fabric or textile may be knitted, or may be non-woven.

According to a fifth aspect, there is provided a garment comprising the fabric or textile of the fourth aspect. The garment may be or comprise a top such as a t-shirt, a vest, a shirt, a jumper, a sweatshirt, a hoodie or a coat. Alternatively or additionally, the garment may be or comprise a pair of shorts, a pair of trousers, a pair of tights, a pair of leggings, a sock or a shoe. The garment may be or comprise an item of personal protective equipment (PPE), for example an item of PPE for healthcare such as a mask.

According to a sixth aspect, there is provided an apparatus comprising the fabric or textile of the fourth aspect. The apparatus may be or comprise an item of outdoor equipment, for example camping equipment such as a tent, sleeping bag, or a geotextile. Alternatively, the apparatus may be an upholstered item, for example an item of furniture such as a chair or sofa, or a vehicle seat etc. The apparatus may be an interior textile product for a building (for example a house) such as a carpet, curtains etc. , or for a vehicle (for example a car, train, aeroplane etc.) such as a vehicle floor, vehicle seat etc.

According to a seventh aspect, there is provided a method of manufacturing a fibre for a yarn and/or a fabric or textile. The method may comprise forming a fibre comprising a hydrophobic material. The method may comprise providing the fibre with a shape or configuration comprising one or more micro and/or nano -sized structures.

The method may comprise extruding a material comprising a hydrophobic material to form a fibre. Providing the fibre with a shape or configuration comprising one or more micro and/or nano-sized structures may comprise extruding the material through a nozzle. The nozzle may have or comprise a structure configured to impart one or more micro and/or nano-sized structures on an outer surface of the fibre (for example, during extrusion of the fibre).

The material may comprise a mixture of a hydrophobic material and a filler material. Providing the fibre with a shape or configuration comprising one or more micro and/or nano-sized structures may comprise removing the filler material after formation of the fibre. Removing the filler material may comprise dissolving the filler material. Removing the filler may provide the fibre with one or more recesses and/or projections in an outer surface of the fibre.

The method of the seventh aspect may be used to produce a fibre according to the first aspect. The method of the sixth aspect may be particularly suitable for producing a fibre according to the first aspect comprising a hydrophobic polymeric material.

Features which are described in the context of separate aspects and embodiments of the invention may be used together and/or be interchangeable wherever possible. Similarly, where features are described in the context of a single embodiment for brevity, those features may also be provided separately or in any suitable sub -combination. Features described in connection with the fibre of the first aspect may have corresponding features definable with respect to one or more of the yarns of the second and third aspects, the fabric or textile of the fourth aspect, the garment of the fifth aspect , the apparatus of the sixth aspect or the method of the seventh aspect, and vice versa, and these embodiments are specifically envisaged.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

FIGs. 1A and IB show a conventional DWR coating onto a fabric or textile;

FIGs. 2A and 2B show how surface roughness affects the hydrophobic properties of a material;

FIG. 3 shows a water-repellent fibre in accordance with the invention;

FIG. 4 shows an example of how diameter, structure height and structure spacing of a water-repellent fibre in accordance with the invention are determined;

FIGs. 5 A to 5J show alternative cross-sectional shapes of water-repellent fibres in accordance with the invention; FIG. 6 shows the water-repellent fibre of Figure 51 in more detail;

FIGs. 7A and 7B show how a hierarchical arrangement of micro and/or nano- sized structures provides enhanced hydrophobic properties for water-repellent fibres in accordance with the invention;

FIGs. 8A to 8D show material compositions of water-repellent fibres in accordance with the invention;

FIG. 9 shows the fibre of Figure 3 incorporated into a yarn, and the yarn incorporated into a plied yarn in accordance with the invention;

FIG. 10 shows a method of forming a water-repellent fibre according to the invention;

FIG. 11 shows an apparatus used in the method of FIG. 10; and

FIGs. 12A to 12C show examples of shaped nozzles used in the apparatus of FIG. 11 to form a water-repellent fibre according to the invention.

Like reference numerals in different Figures may represent like elements.

DETAILED DESCRIPTION

Figures 1A and IB show a conventional durable water repellent (DWR) coating 102 disposed on or applied to a fabric or textile substrate 100. The coating 102 is a separate and distinct layer from the substrate 100. DWR coatings are typically made from perfluorinated compounds (PFCs) or silicone-based materials. The molecular structure of the coating 102 is shown schematically in Figures 1A and IB.

Figure 1A shows the coating 102 on or shortly after initial application onto the substrate 100. On or shortly after initial application, the coating 102 is substantially intact and provides a substantially continuous water repellent (and typically oil repellent and anti stain) layer across the substrate 100 that protects the fabric from moisture. Figure IB shows the coating 102 after a period of use. After a period of use, the coating 102 is no longer intact or continuous across the substrate 100. Rather, due to abrasion and/or contamination of the coating during use, areas of the coating 102 become ineffective or are removed from the substrate entirely. That means that the coating 102 no longer provides a water repellent layer across the substrate. Where the underlying substrate 100 is exposed or no longer protected due to abrasion and/or contamination of the coating 102, moisture can easily reach the substrate 102 as shown. The water repellent properties of the coating 102 are therefore significantly compromised. In addition, the water repellent performance of the coating 102 continues to decrease as the coating 102 is further abraded and/or contaminated during further use.

Figures 2A and 2B show schematically how surface roughness can alter, for example enhance or amplify, the inherent physical and/or chemical properties of a material or surface. In particular, Figures 2A and 2B show how surface roughness can alter the hydrophobic or hydrophilic nature of a material or surface. For an inherently hydrophobic material, the contact angle of a liquid droplet 208 on a surface is significantly higher for a rough surface 205b than for a smooth surface 205a, as shown in Figure 2A. Similarly, for an inherently hydrophilic surface, the contact angle of a liquid droplet 208 on the surface is significantly lower for a rough surface 205b than for a smooth surface 205a. Although surface roughness is depicted schematically by a plurality of substantially rectangular projections in Figures 2A and 2B, it will be appreciated that the same principle of altering the inherent physical and/or chemical properties of a material or surface may be applied using any suitable structure to provide surface roughness.

Figure 3 shows a water-repellent fibre 300 in accordance with an embodiment of the invention. The fibre 300 is formed from or comprises a hydrophobic material, and comprises one or more micro and/or nano -sized structures. In the embodiment shown, the fibre 300 is formed from a polymethylpentene polymer and comprises a star -shaped cross-section. The star-shaped cross-section has six micro and/or nano-sized structures 310, each structure 310 forming a point or arm of the star, but that is not essential. The fibre 300 has a diameter of approximately lpm (e.g., from an outer point of one structure 310 to an outer point of another structure 310 positioned directly opposite), but that is not essential. Each structure 310 has a height or depth of approximately lOOnm (e.g., from a base of the structure 310 where it joins a central part of the fibre 300 to an outer point of the structure 310), but that is not essential. The structures 310 have a substantially uniform height and are distributed around the cross-section of the fibre 300 substantially uniformly (e.g., the fibre 300 has a substantially regular cross- sectional shape), but that is not essential.

By combining a hydrophobic material with one or more micro and/or nano -sized structures, the fibre 300 has enhanced hydrophobic performance relative to the inherent hydrophobic properties of the hydrophobic material. Incorporating the fibre 300 into a yarn for a fabric or textile, or directly into a fabric or textile, may provide a yarn, fabric or textile having enhanced water repellent, oil repellent, anti-fouling and anti-stain properties without requiring a separate coating. The improved properties of the yarn, fabric or textile may be more durable and longer lasting than those provided by a separate coating. A separate coating is susceptible to contamination and abrasion during use of the yarn, fabric or textile, leading to reduced hydrophobic performance over time. In contrast, because the hydrophobic properties of the fibre 300 are integral to the fibre 300 itself, the hydrophobic performance of the yarn, fabric or textile is also integral to the yarn, fabric or textile and is not dependent upon a coating that can be removed from the yarn, fabric or textile.

The star-shaped cross-section may alternatively have any suitable number of micro and/or nano-sized structures 310 that each form a point or arm of the star, for example three or more structures 310. The fibre 300 may alternatively have any suitable diameter, for example between substantially lOOnm and substantially 500pm. Each structure 310 may alternatively have any suitable height or depth, for example between substantially lOnm and substantially lOOpm, or up to substantially 10% of the diameter or thickness of the fibre 300. Adjacent structures 310 may be spaced any suitable distance apart, for example between substantially lOnm and substantially lOOpm apart. Figure 4 shows an example of how the diameter D, structure height I and structure spacing L may be determined or measured for a fibre such as the fibre 300.

Figures 5A to 5J show other possible cross-sectional shapes or configurations for a water-repellent fibre 300 in accordance with embodiments of the invention.

Figure 5 A shows a fibre 300 having a cross -shaped cross-section. Each arm of the cross forms or provides a micro and/or nano-sized structure 310. Figure 5B shows a fibre 300 having a v-shaped cross-section. Each arm of the v-shape forms or provides a micro and/or nano -sized structure 310. Figure 5C shows a fibre 300 having a substantially flat or planar cross-section (e.g., the fibre 300 has a tape-like configuration) comprising serrations or undulating ridges in an outer surface. The tape-like configuration of the fibre 300 may have a slight curve to form an overall C-shape or lima bean shape. Figure 5D shows a fibre 300 having an annular cross-section comprising a bore through a length of the fibre 300. In that embodiment, the internal bore forms or provides a micro and/or nano-sized structure 310. The internal bore may enable the fibre 300 to be lightweight as well as having enhanced hydrophobic properties. Figures 5E to 5H respectively show a fibre 300 having a multi -lobal cross-section. In particular, Figure 5E shows a fibre 300 having a trilobal cross-section (three lobes), Figure 5F shows a fibre 300 having a quadlobal cross-section (four lobes), Figure 5G shows a fibre 300 having a hexalobal cross-section (six lobes), and Figure 5H shows a fibre 300 having a decalobal cross-section (10 lobes). In each of Figures 5E to 5H, the lobes of the fibre 300 form or provide a plurality of micro and/or nano -sized structures 310 in or on an outer surface of the fibre 300. The lobes of the fibre 300 form a series of projections and/or recesses in an outer surface of the fibre 300 that form the micro and/or nano-sized structures 310. In each of Figure 5E to 5H, the fibre 300 has a substantially regular cross-sectional shape with the lobes distributed substantially uniformly around a cross-section of the fibre 300, although that is not essential.

Figure 51 shows a fibre 300 having an oval cross-section. As illustrated in Figure 6, the oval cross-section of the fibre 300 has a major axis A and a minor axis B, wherein a radius of the oval cross-section is greater along the major axis A than along the minor axis B. The small radius of curvature near the outer surface of the fibre 300 along the major axis A provides a micro and/or nano-sized structure if the diameter or thickness of the fibre 300 is selected appropriately (for example, having a diameter or thickness of between substantially lOOnm and substantially 500pm). In addition, if a plurality of fibres 300 are twisted into a yarn, the outer surfaces of the fibres 300 in contact with one another will together form one or more micro and/or nano -sized structures in the yarn (for example, undulations in an outer surface of the yarn due to adjacent fibres in contact with one another).

Figure 5J shows a fibre 300 having a substantially oval cross-section comprising a plurality of lobes each forming a micro and/or nano -sized structure 310.

It will be appreciated that a fibre 300 may comprise both internal and external (e.g., on an outer surface) micro and/or nano-sized structures 310. For example, the annular fibre 300 of Figure 5D may additionally comprise one or more micro and/or nano-sized structures 310 on an outer surface of the fibre 300 (e.g., lobes, projections, recesses etc.). In addition, the fibres 300 of any of Figures 5A to 5C and 5E to 5J may additionally provide an internal bore providing an internal micro and/or nano-sized structure 310. It will also be appreciated that the cross-sectional shapes and configurations shown in Figures 5A to 5J and described above are examples only, and that the fibre 300 may have any suitable cross-sectional shape or configuration.

Figures 7A and 7B illustrate the synergistic effect of a fibre 300 having both a small diameter or thickness and one or more projections and/or recesses in its outer surface. Figure 7A shows a water droplet on fibres 300 having a small diameter or thickness forming a micro and/or nano-sized structure of each fibre 300. The curvature of each fibre 300 forms pockets of air which prevent or inhibit the water droplet from touching the fibres 30. Figure 7B shows a water droplet on fibres 300 having both a small diameter or thickness and one or more projections and/or recesses in the outer surfaces of the fibres 300. That combination forms a hierarchical structure that reduces an area of the outer surface of each fibre 300 that is available to contact the water droplet. Compared to the fibres 300 of Figure 7A, a greater number of air pockets are formed that increase the hydrophobicity of the fibres 300. Although Figures 7A and 7B show a plurality of fibres, it will be appreciated that the same principle of a hierarchical structure further enhancing hydrophobic properties applies equally to individual fibres 300.

Figures 8A to 8D show possible material compositions and/or arrangements of the water-repellent fibre 300. For simplicity, the material compositions and/or arrangements of the fibre 300 are shown schematically without any micro and/or nano sized structures 310 depicted, but it will be appreciated that the material compositions and/or fibre arrangements shown in Figures 8A to 8D can be used in combination with fibres 300 having structures 310 as described above (and such embodiments are specifically envisaged).

Figure 8 A shows a fibre 300 having or comprising a monomaterial composition 312, similar to the embodiment shown in Figure 3 and described above. In the embodiment shown in Figure 3 and described above, the fibre 300 is formed from a 4 -methyl- 1- pentene polymer, although any polymethylpentene polymer may alternatively be used. For example, the polymethylpentene polymer may be a polymethylpentene homopolymer, or may be or comprise a copolymer of a polymethylpentene polymer (such as 4-methyl- 1-pentene) with one or more a-olefins. The one or more a-olefins preferably each have between 2 and substantially 20 carbon atoms, although that is not essential. The molecular chain of the one or more a-olefins may be linear or branched. Specific examples of such a-olefins include ethylene, propylene, 1 -butene, 1-pentene, 1 -hexene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-dexadecene, 1-octadecene, 1-eicosene, 3-methyl-l-butene, 3-methyl-l-pentene, 3-ethyl-l-pentene, 3-ethyl-l- hexene and the like. Alternatively, the fibre 300 may be formed from or comprise any suitable hydrophobic material. For example, the hydrophobic polymeric material may be or comprise a hydrophobic polymeric material, such as an a -olefin polymer (for example polypropylene, polyethylene, polybutylene, polybutene etc.), a polyester, a nylon, a thermoplastic polymer etc.

Figures 8B to 8D each show a fibre 300 having or comprising a multimaterial composition. In the embodiments shown in Figures 6A to 6C, each fibre 300 comprises a mixture of a hydrophobic polymeric material 312 and one or more other polymeric materials 314. The one or more other polymeric materials 314 may not be or comprise hydrophobic polymeric materials, or may be or comprise one or more polymeric materials that are less hydrophobic than the hydrophobic polymeric material 312. Figure 8B shows a fibre 300 having such a mixture in a core -sheath arrangement or configuration. Figure 8C shows a fibre 300 having such a mixture in an island -in-sea arrangement or configuration. Figure 8D shows a fibre 300 having such a mixture in a random blend arrangement or configuration. As can be seen in Figure 8D, the hydrophobic polymeric material 312 forms a greater proportion of an outer surface of the fibre 300 than the other polymeric material(s) 314, to ensure the enhanced hydrophobic performance of the fibre 300 is achieved. In the embodiments shown, the hydrophobic polymeric material 312 is a polymethylpentene polymer substantially as described above, although that is not essential. In the embodiment shown, the one or more other polymeric materials 314 is or comprises a different hydrophobic polymer such as an a-olefin polymer, a polyester, a nylon, a thermoplastic polymer etc. For example, the one or more other polymeric materials 314 may be or comprise polypropylene. Polypropylene may improve the mechanical properties of the fibre 300 without substantially reducing the hydrophobic properties of the fibre 300 (because polypropylene is also hydrophobic). However, that is not essential, and any other suitable polymeric material 314 may alternatively be used, hydrophobic or not.

In the embodiment shown, the mixture (e.g., the fibre 300) comprises substantially 60% by volume of the hydrophobic polymeric material 312. The mixture (e.g., the fibre 300) comprises substantially 40% by volume of the one or more other polymeric materials 314. However, that is not essential, and any mixture ratio of the two may alternatively be used.

Figure 9 shows an example of a water-repellent fibre 300 incorporated into a yarn 320, and an example of a yarn 320 incorporated into a plied yarn 330.

The yarn 320 is formed by twisting a plurality of fibres together using conventional techniques. One of the fibres is a fibre 300 comprising a hydrophobic material and having a shape or configuration comprising one or more micro and/or nano -sized structures, as described above. By incorporating at least one fibre 300 in the yarn 320, the enhanced hydrophobic properties of the fibre 300 are also incorporated into the yarn 320, thereby making the yarn 320 water-repellent. In the embodiment shown, the fibre 300 is an eight-pointed star as described above with respect to Figure 3, but the fibre 300 may have any suitable shape or configuration comprising one or more micro and/or nano-sized structures. Alternatively, the yarn 320 may comprise a plurality of fibres 300 twisted together, optionally with one or more other fibres. The yarn 320 may have a diameter or thickness of between substantially 200nm and substantially lOOOpm, depending on a diameter or thickness of each fibre and the number of fibres in the yarn 320. The plied yarn 330 is formed by twisting a plurality of yarns together using conventional techniques. One of the yarns is the yarn 320 described above. By incorporating at least one water-repellent yarn 320 in the plied yarn 330, the plied yarn 330 is also water- repellent (by virtue of the enhanced hydrophobic properties of the at least one fibre 300 in one or more of the yarns 320). Alternatively, the plied yarn 330 may comprise a plurality of yarns 320 twisted together, optionally with one or more other yarns. The plied yarn 330 may have a diameter or thickness of between substantially 400nm and substantially 5000pm, depending on a diameter or thickness of each yarn and the number of yarns in the plied yarn 330.

The yarn 320 may have between substantially 15 and substantially 2000 twists/m. The plied yarn 330 may have between substantially 15 and substantially 2000 twists/m. Increasing twists/m of the yarn 320 and/or the plied yarn 330 generally increases mechanical properties of the yarn 320 and/or plied yarn 330 such as tensile strength and stiffness. The twists/m may be varied in order to provide the yarn 320 and/or plied yarn 330 with suitable mechanical properties for an intended application of the yarn 320 and/or plied yarn 330.

Each of the fibre 300, the yarn 320 and/or the plied yarn 330 may be incorporated into or used to form a fabric or textile, for example woven or knitted into a fabric or textile or incorporated into or used to form a non-woven fabric or textile. Incorporating one or more fibres 300, yarns 320 and/or plied yarns 330 into a fabric or textile may provide a substantially waterproof fabric or textile, due to the water-repellent or enhanced hydrophobic properties of the fibre(s) 300, yarn(s) 320 and/or plied yarn(s) 330.

For a woven fabric or textile, the fibre(s), yarn(s) 320 and/or plied yarn(s) 330 may form one or warp threads and/or one or weft threads of the fabric or textile. The twists/ m of a yarn 320 or plied yarn 320 may be higher for a warp thread than a weft thread, because typically warp threads require greater strength and stiffness than weft threads during weaving. One or more other fibres or yarns may be incorporated into the fabric or textile to provide the fabric or textile with additional functional properties. For example, silver or copper fibres or yarns may be incorporated into the fabric or textile to provide anti-bacterial and anti-viral properties. The fabric or textile may be used in a variety of applications. For example, it may be used to form substantially waterproof garments such as for outdoor pursuits including walking, hiking, climbing, mountaineering etc., or personal protective equipment (PPE) such as masks and gowns for healthcare. Similar, the fabric or textile may be used to form substantially waterproof apparatus such as tents, hammocks, sleeping bags, umbrellas, bags, rucksacks etc., or upholstered items such as chairs, sofas, vehicle sets etc., or an interior textile product such as for a house (e.g., carpet, curtains) or a car (e.g., a car floor) The fabric or textile may also be used for construction or landscaping purposes, for example as a geotextile or geomembrane to prevent water from travelling through an area or retain water in a specific location.

Figure 10 shows a method 400 for manufacturing a fibre 300 in accordance with an embodiment of the invention. The method 400 may be carried out using, and is described with respect to, an apparatus 500 as shown in Figure 11, in accordance with an embodiment of the invention.

At step 405, the method 400 comprises forming a fibre 300 comprising a hydrophobic material. At step 410, the method 400 comprises providing the fibre 300 with a shape or configuration comprising one or more micro and/or nano-sized structures.

In the embodiment shown, the method 400 comprises extruding a material comprising a hydrophobic material to form the fibre 300. The apparatus 500 comprises a vessel 505 configured to contain a polymer feedstock (for example, a melt or solution). The apparatus 500 includes a metering pump 505a is included to control feed of the polymer feedstock, but that is not essential. The apparatus 500 a spinneret 510 configured to form one or more fibres 300 from the polymer feedstock. In the embodiment shown, the spinneret 510 comprises one or more nozzles (not shown) through which the polymer feedstock passes. In the embodiment shown, one or more of the nozzles comprises a structure configured to provide the formed fibres 300 with one or more micro and/or nano-sized structures. In the embodiment shown, steps 405 and 410 therefore take place substantially simultaneously. For example, the nozzle may be shaped (e.g., have a cross - sectional shape) or configured to impart one or more micro and/or nano -sized structures on an outer surface of the fibre 300 during extrusion of the fibre. Examples of such nozzles are shown in Figures 12A-C, which depict X-shaped, hexalobal and trilobal nozzles respectively. The shaped nozzles produce fibres 300 having a modified cross- section and comprising one or micro and/or nano -sized structures (for example, the respective arms of the arms or lobes of the shapes). It will be appreciated that a nozzle having any form suitable to form a fibre having a shape or configuration comprising one or more micro and/or nano-sized structures may alternatively be used. For example, the nozzle may have a form substantially corresponding to a shape or configuration of any of the fibres 300 described above, such as those shown in Figures 3 to 6.

The apparatus 500 comprises a filter 508 to filter the polymer feedstock prior to passing through the spinneret 510, although that is not essential. A flow of cooling air F is provided to solidify the fibres 300 following exit from the spinneret, although that is not essential. A series of spools 512a-c are then provided to capture the fibres 300, although that is not essential.

The method 400 described above comprises a conventional melt -spinning process in combination with one or more specific nozzles configured to produce a fibre 300 comprising one or more micro and/or nano-sized structures. It will be appreciated that any suitable manufacturing technique may alternatively be used to form the fibre 300, for example melt-blowing, dry-spinning, wet-spinning, dry-jet wet-spinning etc. It will also be appreciated that similar techniques may be used to form fibres 300 having multi - material compositions, for example core-sheath structures, island-in-sea structures and random blend structures.

If the polymer feedstock comprises a random blend of a hydrophobic material and one or more other materials, an annealing step may be performed after formation of the fibre 300. The reason for that is to cause the hydrophobic material to diffuse towards an outer surface of the fibre 300. The low surface energy of the hydrophobic material makes it energetically favourable for the hydrophobic material to be located at an outer surface of the fibre 300. Annealing may provide a sufficient temperature to enable the hydrophobic material to diffuse towards an outer surface of the fibre 300. However, annealing may not be necessary if the temperature used during formation of the fibre 300 is sufficient to enable the hydrophobic material to diffuse towards an outer surface of the fibre 300 during formation. A suitable temperature may be between substantially 80°C and substantially 230°C, depending on the polymer(s) chosen. Alternatively, a different technique may be used to form a fibre 300 comprising a shape or configuration comprising one or more micro and/or nano -sized structures. For example, step 405 may comprise forming a fibre using a mixture of a hydrophobic material and a filler material. The filler material may be or comprise polymer particles and/or fibres (for example, micro and/or nano -sized particles and/or fibres), for example polyester (PES), polylactic acid (PLA), polyvinyl alcohol (PVA) etc. Additionally or alternatively, the filler material may be or comprise inorganic particles and/or fibres (for example, micro and/or nano-sized particles and/or fibres) such as calcium carbonate, clays, salt, silica, titanium dioxide (T1O2), Zinc Oxide (ZnO) etc. It will be appreciated that a number of conventional filler materials may be suitable, such as filler materials soluble in water or industry standard solvents. Forming the fibre may comprise using the method 400 substantially as described above. However, the fibre may be formed using a conventional nozzle having a substantially circular cross-section.

Step 410 may comprise at least partially removing the filler material from the formed fibre to form a fibre 300 comprising a shape or configuration comprising one or more micro and/or nano-sized structures, for example one or more projections and/or recesses in an outer surface of the fibre. Removing the filler material may comprise dissolving the filler material. That may require the fibre to be placed into a bath of a suitable reagent to allow the filler material to be dissolved, for example water, alcohols, esters, acids, dimethylformamide (DMF), or any other suitable organic or water based conventional solvent or mixture. One or more other methods such as ultrasonication and/or heating of the solvent may be used in conjunction with the dissolving, in order to aid with removal of the filler material.

From reading the present disclosure, other variations and modifications will be apparent to the skilled person. Such variations and modifications may involve equivalent and other features which are already known in the art of textiles, in particular waterproof fibres, yarns and/or fabrics or textiles, and which may be used instead of, or in addition to, features already described herein.

Although the appended claims are directed to particular combinations of features, it should be understood that the scope of the disclosure of the present invention also includes any novel feature or any novel combination of features disclosed herein either explicitly or implicitly or any generalisation thereof, whether or not it relates to the same invention as presently claimed in any claim and whether or not it mitigates any or all of the same technical problems as does the present invention.

Features which are described in the context of separate embodiments may also be provided in combination in a single embodiment. Conversely, various features which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable sub -combination. The applicant hereby gives notice that new claims may be formulated to such features and/or combinations of such features during the prosecution of the present application or of any further application derived therefrom.

For the sake of completeness, it is also stated that the term "comprising" does not exclude other elements or steps, the term "a" or "an" does not exclude a plurality, and any reference signs in the claims shall not be construed as limiting the scope of the claims.