Fibre for Fabric and Fabric

[0001] This application claims priority from Australian provisional application 2022901518 filed on 2 June 2022, the contents of which are incorporated herein by this reference.

Technical Field

[0002] The invention relates to a fibre with improved heat reflective abilities. The invention further relates to a fabric with improved heat reflective abilities.

Background of Invention

[0003] The following discussion of background art is included to explain the context of the present invention. A reference herein to a matter which is given as prior art is not to be taken as an admission that the matter was known or that the information it contains was part of the common general knowledge as at the priority date of any of the claims.

[0004] Fabrics are commonly used to provide shade in the form of shade cloths, or provide protection from external elements such as wind and rain. The same or similar fabrics are also used in the construction of outdoor furniture such as chairs and day beds. The majority of these fabrics are made of plastic / synthetic fibres.

[0005] Where fabrics are exposed to sunlight they absorb heat. Specifically plastic articles, including synthetic fibres, heat up when exposed to sunlight because the base polyethylene structure along with the plastic pigments absorb infrared wavelengths from the sun and convert them into heat energy. The darker the plastic, the warmer it item becomes when exposed to the sunlight, with a black fibre being the highest heat absorber.

[0006] The amount of heat absorbed can be unbearable, for example, on a clear summer day. This is evident particularly when one sets up a fabric tent, a fabric chair, a mat or marquee on a hot summer day. In such instances, the fabric absorbs a great amount of radiant heat making the fabric unbearable to touch and uncomfortable to use. The fabric often becomes hotter than its surrounding environment, resulting in heat transfer to the surrounding environment through conduction and/or convection.

[0007] Mitigating heat absorption is an important consideration when designing fabrics which are exposed to sunlight. One such measure employed to mitigate heat absorption is to provide apertures throughout the fabric to facilitate ventilation. These apertures may be in the form of perforations or may result from a particular weave or knit pattern. The ventilation enabled by these apertures is particularly beneficial as it allows air to flow through the fabric, cooling it down. Where the fabric is used as an enclosure or a sunshade, the apertures allow air to flow through to an enclosed/shaded area or the contact area.

[0008] Ventilation holes are effective to an extent, and other measures are often required to minimise heat absorption. One such measure involves applying a light colouring to the fabric surface to reduce heat absorption. Although this is effective, it has aesthetic limitations on the fabric colour, and may not be practical in instances where darker colours are required.

[0009] Another method used to address fabric heat absorption is to apply a heat reflective coating, or an illuminised film to the surface of the fabric or to the individual fibres. Although the heat reflective coatings and films are effective, they degrade over time resulting in the shedding of fragments and chemicals. The shedding and decomposition of these fragments, which may contain metals and harmful chemicals may be toxic and contaminate surrounding land and water. Further, as the coatings/films have a limited life span, there is a cost and inconvenience involved in having to re-apply the coatings and films, or having to regularly replace the fabric.

[0010] It is desirable to address the shortcomings of the existing fabrics by providing a relatively more durable heat reflective fibre and fabric, without significantly compromising the strength and other qualities of the fabric.

Summary of Invention

[001 1] The invention seeks to provide a fabric with innate heat resistant properties. In this respect, the present invention seeks to remove the need to apply a heat resistant coating or film to the fabric, whilst maintaining the structural integrity of the fabric. In this respect, in the present invention, infrared reflective pigments and additives are incorporated in the chemical makeup of the fibres used to form the fabric.

[0012] According to one form of the invention there is provided a fibre for use in a warp knitted shade cloth, wherein the fibre is comprised of at least the following elements: high density polyethylene (HDPE), hindered amine light stabilizers ultra violet (HALS UV), a dispersive additive, an infrared (IR) reflective pigment, and/or an IR reflective additive. The IR reflective pigment and additive is an integral component of the fibre and forms part of the fibre polymer matrix. This removes a need to apply a potentially harmful heat resistant coating post-manufacturing. Having an IR reflective pigment and/or additive included in the chemical makeup of the fibre provides the benefit of longevity of the heat reflective capability of the fibre. The IR reflective pigment and/or additives become locked within the polymer matrix of the fibre and are not expected to leach out or diminish in performance over time. Further, the inclusion of infrared reflective pigments and/or additives in the polymer matrix of the fibres of a fabric allows for the sector of IR wavelength that carries heat to be reflected when the fibres are exposed to sunlight, or an equivalent light source, thus reducing the surface temperature of the fibres and subsequently the fabric.

[0013] The fibre may be manufactured in any number of ways. For example, the fibre may be manufactured through an extrusion manufacturing process. In this respect, the high density polyethylene (HDPE), hindered amine light stabilizers ultra violet (HALS UV), the dispersive additive, the IR reflective pigment, and/or the IR reflective additive, are fed into a hopper by a feeder. The contents in the hopper are then blended in a blending system, with the blended contents being extruded out in the form of a fibre in a desired size and configuration.

[0014] Adding additives to a base formulation is not a straightforward exercise. Generally, the more additives added to a formula, the harder it becomes to process during the extrusion process and the harder it becomes to use during a fabric manufacturing process. With respect to a HDPE based polymer, the addition of an IR reflective pigment and/or additive result in a lower concentration of other constituents such as HDPE. This can have an adverse effect on strength and fibre resilience. This has been a deterrent to incorporating IR reflective pigments and additives in fibres to be used in the manufacture of shade cloths and similar fabrics. There are significant challenges in identifying the correct additives to use so as to ensure compatibility with other additives and constituents and to not impact useful life and performance of the fibres.

[0015] In arriving at the present invention, the inventors have found a formulation of compatible constituents that provides the fibres with acceptable strength properties whilst enhancing heat reflective capabilities. In one aspect of the invention, the fibre comprises a HDPE content of approximately 91 to 95%, a HALS UV stabiliser content of approximately 0.2-1 .0%, an IR reflective pigment content of approximately 0.5-4.0%, a dispersive additive content of approximately 0.4-0.8%, and an IR reflective additive content of approximately 0.0 to 0.5%.

[0016] The shape and configuration of the fibre may vary depending on the end use of the fibre and fabric for which it will be used. In one embodiment the fibre may be a monofilament fibre. It may have a generally round shape with a diameter of approximately 0.1 mm to 0.5mm and a yarn tex of approximately 40 to 55.

[0017] In an alternative embodiment, the fibre may be a tape filament fibre. It may be generally flat in appearance and have a width of approximately 0.5mm to 3.0mm and a yarn tex of approximately 40 to 55.

[0018] In a further alternative embodiment, the fibre may be a multifilament fibre. In this respect, it may comprise of multiple small filaments/strands twisted together. The multifilament fibre may comprise up to 200 individual filaments/strands, and a yarn dernier of approximately 400 to 1000.

[0019] The IR reflective pigment contributes significantly to the colour of the fibre. The IR reflective pigment may be any one of or a combination of Colanyal™ Oxide Yellow BV531 , Colanyl™ Scarlet GO532, Colanyl™ Oxide Red G531 or Colanyl™ Oxide Blue COR531 , titanium dioxide, mica, and silicon dioxide. The reference to Colanyl is a reference to a product line developed by a division of Clariant AG. It is to be appreciated that the list of IR reflective pigments is not exhaustive.

[0020] It is to be appreciated that titanium dioxide, mica, and silicon dioxide can also be considered IR reflective additives. These additives also have pigmentation characteristics. Therefore, in one embodiment, the IR reflective additive may be titanium dioxide, or mica, or silicon dioxide. It is to be appreciated that the list of IR reflective additives is not exhaustive.

[0021] In another form of the invention there is provided a fabric for use as a shade cloth comprising a plurality of warp knitted fibre filaments according to any one of above fibre embodiments. The fibre filaments may be warp knitted on a raschel knitting machine, or woven, or tufted. In essence, the fibre filaments may be used to form a fabric in any variety of ways that fibres can be attached or interlocked with one another. In a further embodiment, the fabric may combine fibres disclosed in the earlier paragraph along with other fibres not discussed. For example, the fabric may be comprised of fibres according to the present invention along with carbon fibre fibres and or steel filaments.

[0022] In one aspect, the fabric may have a warp density of approximately 4 to 12 gauge, and preferably a warp density of approximately 6 gauge. As the fabric can be used for a variety of purposes, it may have a weight of between 125gsm and 500gsm, and preferably a weight of 205gsm. The fabric may also have a cover factor between approximately 80-95%, and in a preferred embodiment, it may have a cover factor of 90%.

[0023] The fabric density can be tailored to the purpose for which the fabric is to be used. It need not be tailored to providing properties fit for purpose for a shade cloth if the fabric is to be used for a different purpose. Further, the fabric may comprise a variety of knit patterns and may even include re-enforcing yarns. For example, the fabric may be a shade sail comprising a weight of approximately 340gsm, or a window furnishing comprising a weight of approximately 160gsm.

[0024] In another form of the invention there is provided a shade cloth comprising a plurality of fibres according to any one of the previously mentioned embodiments, wherein the fibres are manufactured by an extrusion manufacturing process, or any other suitable manufacturing process. The fibres of the shade cloth may be warp knitted together to form a fabric according any one of the aforementioned fabric embodiments. That is the shade cloth may comprise a warp density of approximately 4 to 12 gauge, a weight of between 125gsm and 500gsm, and a cover factor between approximately 80-95%. [0025] In the present invention the fundamental structure of a fibre comprises infrared reflective additives and/or pigments in its polymer matrix, thus locking the additives within the fibre’s chemical makeup. Doing so provides the advantage of ensuring the IR reflective capabilities of the fibre do not leak, degrade or diminish in performance over time. The present invention has developed a fibre using select additives which are compatible with other constituents, and in which the additive rate is sufficiently high to ensure an innate heat reflective aspect, whilst also giving the fibre sufficient strength and resilience to be used during fabric manufacture/knitting.

[0026] In essence, the present invention has doubled the amount of additives used in the makeup of a fibre compared to other pre-existing fibres, whilst providing an acceptable structural integrity such that the fibre is suitable for use during manufacturing of a fabric and is fit for purpose.

[0027] The fibre of the present invention exhibits relatively lower infrared wavelength absorption, and thus limits heat build-up of the HDPE base fabric exposed to the sun or similar light sources when compared to conventional shade fabrics. As a result, the newly developed fibre and fabric remains cooler and more comfortable to touch and use.

[0028] Where the terms “comprise”, “comprises”, “comprised” or “comprising” are used in this specification (including the claims) they are to be interpreted as specifying the presence of the stated features, integers, steps or components, but not precluding the presence of one or more other features, integers, steps or components, or group thereto.

Brief Description of Drawing

[0029] It will be convenient to hereinafter describe a preferred embodiment of the invention and its benefits with reference to the accompanying drawing. The particularity of the drawing is to be understood as not limiting the preceding broad description of the invention.

[0030] In Figure 1 there is provided a graph depicting the surface temperature of two fabrics over time, whereby one fabric is comprised of fibres having IR reflective pigments and additives incorporated in the polymer matrix. Detailed Description

[0031] Referring to Figure 1 , there is a graph 2 illustrating the heat absorption over time of a fabric 4 having IR reflective pigments and additives incorporated in the polymer matrix of the fibres. There is also illustrated the heat absorption over time of a second fabric 6, which does not have any IR reflective pigments or IR reflective additives incorporated into the fibre polymer matrix structure. The second fabric 6 is identical in makeup constituents to fabric 4, with the exception of the IR reflective pigments and additives. Both fabric 4 and fabric 6 are beige in colour.

[0032] As can be seen in Figure 1 , fabric 4 maintains a generally lower surface temperature compared to fabric 6. The infrared reflective additives and/or pigments in the polymer matrix of the fibres of fabric 4 allow sunlight to pass through and at the same time reflects a larger portion of the IR wavelength that carries heat, thus reducing the surface temperature of the fabric 4. In Figure 1 , the surface temperature of fabric 4, is approximately 20% lower than that of fabric 6 at its peak surface temperature.

[0033] Fabric 4 is a warp knitted fabric and can be used as a shade cloth, or for other purposes. For example, the fabric 4 may be an element in furniture such as a pet bed, day bed, or a chair. The fabric 4 is comprised of synthetic polymer fibres. The fibres are made up of high-density polyethylene (HDPE), hindered amine light stabilizers ultra-violet (HALS UV), a dispersive additive, an IR reflective pigment, and an IR reflective additive.

[0034] The fibre used to make up fabric 4 is manufactured through an extrusion manufacturing process. The HDPE, the HALS UV, the dispersive additive, the IR reflective pigment, and the IR reflective additive, are fed into a hopper by a feeder. The contents in the hopper are then blended in a blending system, with the blended contents being extruded out in the form of a fibre in a desired size and configuration. It is to be appreciated that extrusion manufacturing is one of a number of methods that the fibre can be manufactured. Other methods include extrusion spinning, solution spinning, direct spinning, and electrospinning.

[0035] The fibres of fabric 4 have a fundamental structure in which infrared reflective additives and/or pigments are integral within the polymer matrix, thus locking the additives within the fibre’s chemical makeup. This provides the advantage of ensuring the IR reflective capabilities of the fibre do not leak, degrade or diminish in performance over time.

[0036] The fibres used in fabric 4 comprise a HDPE content of approximately 94.4%, a HALS UV stabiliser content of approximately 0.6%, an IR reflective pigment content of approximately 4.4%, a dispersive additive content of approximately 0.4%, and an IR reflective additive content of approximately 0.2%. The content values stated were specified at manufacture, however due to equipment tolerances the values may have deviated slightly.

[0037] It is to be appreciated that the present invention is not restricted to the specific content percentages noted above. In developing the fibre, it was found that the following content ranges were acceptable: a HDPE content of 91 to 95%, a HALS UV stabiliser content of 0.2-1 .0%, an IR reflective pigment content of 0.5-4.0%, a dispersive additive content of 0.4-0.8%, and an IR reflective additive content of 0.0 to 0.5%.

[0038] In comparison to the fibres of fabric 4, the fibres of fabric 6 comprise a generally higher HDPE content. Specifically, the fibres of fabric 6 comprises the following: a HDPE content of approximately 97.6%, a HALS UV stabiliser content of approximately 0.6%, a standard pigment additive of approximately 1 .5%, and a dispersive additive content of approximately 0.3%.

[0039] It is understood that decreasing the HDPE content and increasing the content of additives in a fibre impacts the mechanical properties of a fibre. The ranges noted above for fabric 4 factor in the compatibility of the constituents, whilst providing a sufficiently high infrared reflective rate to ensure an innate heat reflective aspect to the fibre. The ranges noted above have also been found to provide a fibre fit for purpose when used on a knitting machine to create a fabric for use as a shade cloth. In this respect, fibres for use in a shade cloth tend to be thinner compared to other fibres used to form fabrics such as synthetic grass, whereby such fibres tend to be tufted. It is to be appreciated most fibres designed specifically for tufting tend to be unsuitable for use in the makeup of a shade cloth, as such fibres are relatively thicker. The resultant fabric was also found to possess acceptable mechanical properties suitable for use as a shade cloth.

[0040] As noted in the ‘Background’ section, colour makes a significant contribution to the heat absorption of a fibre or fabric. The IR reflective pigment contributes significantly to the colour of the fibre, and the resultant fabric. The fibre used in the makeup of fabric 4 comprises the following IR reflective pigments and additives: Colanyal™ Oxide Yellow BV531 and Titanium Dioxide, blended with additional pigments to create a Beige fabric colour.

[0041] The IR reflective pigment used in the fibre makeup is not restricted to Colanyal™ Oxide Yellow BV531 . In alternative embodiments the IR reflective pigment is altered to provide a different fibre and fabric colour. For example, Colanyl™ Scarlet GO532 and/or Colanyl™ Oxide Red G531 are used to give the fibre a red colour; and Colanyl™ Oxide Blue is used to give the fibre a blue colour. The Colanyl™ additives are proprietary additives and colours developed by Clariant AG which is owned by Heubach GmbH. These IR reflective pigments can be mixed and matched to obtain a desired colour. Thus, in a further alternative aspect, a combination of IR reflective pigments is used to obtain a desired colour. Further, any other suitable IR reflective pigment may be used, for example, titanium dioxide, mica, and silicon dioxide all have a pigmentation effect, and may be used alone or in combination with each other and the Colanyl™ pigments to obtain a desirable colour. It is to be appreciated that the list of IR reflective pigments is not exhaustive. Other branded IR reflective pigments, or other IR reflective pigments not listed may be used.

[0042] The IR reflective additive used in the fibre makeup is not restricted to titanium dioxide. In alternative embodiments, the IR reflective additive used is titanium dioxide, or mica, or silicon dioxide, or a combination thereof. It is to be appreciated that additives such as titanium dioxide, mica, and silicon dioxide have a pigmentation effect. As a result, in certain embodiments, the IR reflective additives are used in place of the IR reflective pigments noted above, or in combination with those IR reflective pigments, or in combination with any other suitable IR reflective pigment or additive. It is to be appreciated that the list of IR reflective additives is not exhaustive. Other branded IR reflective additives not listed may be used. [0043] The fibres used in the fabric 4 are tape fibres. Such fibres have a generally flat cross-section. The width of such a tape filament may vary between 0.5mm to 3.0mm. A yarn tex range of between 40 to 55 was found to be fit for use in the manufacturing of a fabric and for use in a shade cloth fabric or a fabric to be exposed to external elements such as sun, wind and rain.

[0044] The fibres used in the fabric 4 are not restricted to tape fibres. In an alternative embodiment to that contemplated in Figure 1 , the fibres are a monofilament filament fibres, having a generally round cross-section. The diameter of such a monofilament fibre may vary between 0.1 to 0.5mm with a yarn tex range of between 40 to 55.

[0045] In a further alternative embodiment to that contemplated in figure 1 , the fibre of fabric 4 is a multifilament fibre. A multifilament fibre is comprised of a plurality of small fibres twisted together. The multifilament fibre may comprise up to 200 individual filaments/strands and have a yarn denier of approximately 400 to 1000. In a further alternative embodiment, the fibre may be a tape filament fibre having a width of between 0.5mm to 3.0mm, and a yarn tex range of approximately 40 to 55.

[0046] The fabric 4 of Figure 1 need not only comprise a single type of fibre. In an alternative embodiment to that contemplated in Figure 1 , the fabric 4 may comprise a combination of monofilament and/or multifilament and/or tape filament fibres. To provide additional strength, the fabric in a further alternative embodiment may comprise reinforcing fibres of a different material such as stainless steel.

[0047] The fabric 4 of Figure 1 is comprised of a plurality of monofilament fibres warp knitted together on a raschel knitting machine. The fabric 4 has a warp density of 6 gauge, with a weight of 205 gsm and a fabric cover factor of 90%, in accordance to AS4174:2018.

[0048] As noted in the preceding paragraphs above, alternative embodiments of the fabric may be comprised of a plurality of warp knitted monofilament fibres, or multifilament fibres, or tape filament fibres, or a combination thereof. The method in which the fibre filaments are attached is not restricted to warp knitting. In alternative embodiments, the fibres may be woven or tufted. The warp density of the fabric 4 may deviate from 6 gauge and may range between 4 to 12 gauge in alternative embodiments depending on the end use of the fabric. Similarly, the fabric weight may be adjusted to anywhere between 125 gsm and 500gsm in alternative embodiments depending on the end use of the fabric. A higher weight and warp density may be required in instances where a fabric may be subjected to higher forces, and a generally stronger fabric is required. The warp density and weight can be altered to compensate for the reduction in innate mechanical properties such as tensile strength of the fibre due to the lower concentration of HDPE and the higher additive concentration.

[0049] The fabric 4, having an IR reflective pigment and/or additive included in the chemical makeup of the fibre provides the benefit of longevity of the heat reflective capacity of the fibre, and ultimately the fabric. The IR reflective pigment and/or additives are locked within the polymer matrix of the fibre and are not expected to leach out or diminish in performance over time. Further, the inclusion of infrared reflective pigments and/or additives in the polymer matrix of the fibres of the fabric 4 allow for the sector of IR wavelengths that carry heat to be reflected when the fibres are exposed to sunlight, or an equivalent light source, thus reducing the surface temperature of the fibres and subsequently the fabric, as is demonstrated in Figure 1 .

[0050] Although fabric 4 is merely referred to as a fabric, it is envisaged in an embodiment that the fabric 4 be a shade cloth comprising a plurality of fibres being either a monofilament fibre, a multifilament fibre, or a tape filament fibre, with the fibres having a HDPE content of 91 to 95%, a HALS UV stabiliser content of 0.2- 1 .0%, an IR reflective pigment content of 0.5-4.0%, a dispersive additive content of 0.4-0.8%, and an IR reflective additive content of 0.0 to 0.5%. The fibres of such a shade cloth fabric are manufactured by extrusion manufacturing, or any other feasible manufacturing process. The IR reflective pigment and additives used in the fibre make up may be any one or a combination of those previously noted in this description. The shade cloth is preferably formed by warp knitting the fibres together, for example on a raschal knitting machine, but can be attached in a plurality of other ways such as tufting or weaving. The shade cloth has been found to be fit for purpose when comprising a warp density of approximately 4 to 12 gauge, having a weight of between 125gsm and 500gsm, and a cover factor between approximately 80-95%. [0051] In alternative embodiments, the fabric 4, may comprise lower or higher warp densities and weights, and fulfil the role of for example a window furnishing which has a desired weight of 160gsm, or a shade sail which has a desired weight of 340gsm.

[0052] In further alternative forms and embodiments, HDPE content of the fibre in fabric 4 may be substituted with another similar material. Options include and are not limited to low density polyethylene, silicone, polypropylene, acrylonitrile butadiene styrene, polycarbonate, polylactic acid, polyhydroxyalkanoates, cellulose acetate.

While a polymer having similar properties to HDPE may be used as a substitute to HDPE, the % amount of the alternative polymer used in the make up of the fibre may need to be varied to accommodate for the different polymer properties.

[0053] It is to be understood that various alterations, modifications and/or additions may be introduced into the construction and arrangement of the parts previously described without departing from the spirit or ambit of this invention.