This invention relates to an elastic cord and a method of manufacturing the same. The cord of the invention is particularly suitable for use with disposable or limited use apparel, although it is not limited to such.

Disposable or limited use apparel is a significant and essential requirement in medical, manufacturing, and cleanroom environments where cleanliness and sterilization is essential for the health and protection of the wearer as well as the consumers and customers. A few examples of such products are isolation gowns, aprons, face masks, surgical caps, hair nets/ covers, hair ties, beard covers, scrubs, shoe covers and gloves. Medical, pharmaceutical, health and wellness, food processing, restaurants, electronics, chemical processing and janitorial are few examples of industries where such products are used.

A narrow elastic cord is typically used in these types of articles so that adjustability across multiple sizes is provided, thus eliminating the need to make the garments in wide range of sizes which would increase manufacturing and stock holding cost. Furthermore, these cords also assist to offer a better fit, keep the article in place and also makes it easier wearing and removing the garment.

Elastic cords are conventionally manufactured using cord knitting machines, braiding machines, narrow diameter circular knitting machines and narrow tape weaving machines. It is also possible to use double needle bar Raschel knitting machines but due to the high cost of the machinery and slow speed, it is not typically price competitive to use this machine in the disposable or limited use apparel applications. All these machines can achieve a circular shape either due to the circular nature of the fabric making mechanism of the machinery or the ability of the machinery to do multilayer structures including tubular constructions. In terms of cost competitiveness, typically the cord knitting machinery offers the cheapest cords, then braiding machines, then narrow diameter knitting machines and then the woven machines. This conclusion is based on the following factors: cost of the machinery, output (speed it can run, number of tapes that can be made per machine, the running efficiency), advantages of the constructions possible, material preparation required, the amount of material required, frequency of material replenishment, floor space required and power consumption. The number of tapes that can be produced ranges typically between 1 and 40 tapes per machine depending on the type and the configuration of the machine. Elastic cords typically have a uniform and rather dense construction which does not have much cushioning to them. Therefore, when used as ear-loops of disposable masks, hair covers/ nets and similar other articles, they can be uncomfortable on the skin due to the compression it applies to support the functions of the garment. This is especially as the profile is narrow as well, which can cause a pinching on the skin. A wider product may offer better comfort but will be more expensive.

Due to the single or limited use and the disposable nature of the articles, cost of the product is a significant aspect that all manufactures must manage. As such, given that the highest priority must be given to the functional aspects of the article to meet regulatory requirements, comfort is often compromised in order to stay within sensible price points.

This invention relates to an elastic cord which is low cost, easy to manufacture and offers a higher comfort for disposable or limited use apparel, or any other type of apparel that cords may be used with.

According to a first aspect of the invention there is provided an elastic cord comprising: an elastomeric yarn and a set of crimped textured yarns, the crimped textured yarns being arranged to form a cushioned sheath at least partly around the elastomeric yarn, the sheath having a series of cushion portions and pinched portions along its length, the pinched portions being formed where the set of crimped textured yarns cross paths and the cushion portions being created by the bulk of the crimped textured yarns in between the pinched portions.

It will be understood that a crimped textured yarn is one in which the filaments have been deformed in a crimped manner by mechanical and/or thermal processes. Such crimped textured yarns may be referred to as draw textured yarn ("DTY"), The elastomeric yarn provides the stretch and the power required by an elastic cord. Meanwhile, the crimp textured yarns provide comfort to the wearer, as outlined in more detail below.

The bulky form of the crimp textured yarns helps to achieve the sheath around the elastomeric yarn (in some embodiments, the sheath is tubular in shape). Moreover, its cushioned nature and soft touch together with the construction creates a cushioned sheath around the elastomeric yarn to provide comfort and help reduce the pressure that gets applied to the skin by the cord. In particular, the open, high volume and low dense nature of crimped textured yarn means that the chosen construction forms cushion or bubble-like portions on the surface of the sheath which dampen the pressure against the wearer's skin. The open and low dense nature of the textured yarn also provides a soft feel to the touch as well as helping with air circulation through the cord which assists to significantly reduce sweat build up on the skin surface that it is resting on.

Furthermore, the same low dense cushioned nature of this cord surface allows for the distribution of the pressure of the cord against the skin over a wider surface area in comparison to a cord that is circular and high in density (hard), thus reducing the compression that the wearer experiences. This is graphically illustrated in Figure lb where the "bubble cord" represents the cord of the invention. This is due to the contact area of the cord that is against the skin being flattened when it is forced against the skin which is the case when its worn.

In addition, the pinched portions that are formed between the cushion portions means that a gap is created between the cord and the wearer's skin at each pinched portion, i.e. due to the peaks (at the cushioned portions) and valleys (at the pinched portions) along the length of the sheath. These gaps allow for better air circulation between the cord and the skin, thus reducing sweating.

Furthermore, the discomfort on the skin by the cord is also reduced because it is only the cushion portions (i.e. the peaks of the sheath) that press against the skin. As the pinched portions are thinner than the overall thickness of the cord, these portions stay at a higher plane than the peaks of the cushioned area (in relation to the surface that contact the skin), thus do not compress the skin that is directly underneath. This allows the blood flow in those areas to continue with no or minimal restrictions. The above features and associated benefits are unlike conventional elastic cords which are dense in nature and have a uniform surface which is in contact with the skin along its entire length. Compression is applied on the skin along the entire length of the cord which interrupts the blood flow and also causes sweat build up in that area, thus causing discomfort.

The set of crimped textured yarns that cross paths at the pinched portions may be held in place relative to the elastomeric yarn by a warp yarn. The warp yarn may be a crimped textured yarn. The crimped textured yarns at the cushion portions may float the warp yarn.

The elastic cord may include more than one set of crimped textured yarns, wherein each set of crimped textured yarn cross paths at different points to create separate pinched portions.

The cushioned sheath may have a nonuniform surface along its length. The cushioned sheath may be tubular.

The elastic cord may further include one or more secondary cushion portions, the or each secondary cushion portion being smaller in size to the cushion portions and being formed inside a respective cushion portion. The series of pinched portions may be formed on a shared axis along the length of the cord, The shared axis may run along the central length of the cord.

The series of pinched portions may be formed on different axes along the length of the cord, the axes being offset from one another.

The desired density of the cushion portions may be created by one or more of the following characteristics of the textured yarn: the number of ends per weft, the number of counts of the yarn, the ply of the yarn, denier. The elastomeric yarn may be made from a single yarn or a combination of elastomeric threads. The elastomeric yarn may be a single or double covered elastic yarn.

The width of the cord may be 7mm or less. According to second aspect of the invention there is provided a method of manufacturing an elastic cord comprising forming a textile structure using a set of crimped textured yarns to form a cushioned sheath at least partly around an elastomeric yarn, the sheath having a series of cushion portions and pinched portions along its length, the pinched portions being formed where the set of crimped textured yarns cross paths and the cushion portions being created by the bulk of the crimped textured yarns in between the pinched portions. The method may further comprise using a warp yarn to hold the crimped textured yarns in place relative to the elastomeric yarn to form the pinched portions and floating the crimped textured yarns relative to the warp yarn to create the cushion portions. The warp yarn may be a crimped textured yarn.

A first sub-set of the set of the crimped textured yarns may be arranged to work on one side of the elastomeric yarn, and a second sub-set of the set of crimped textured yarns may be arranged to work on another side of the elastomeric yarn,

The method may further comprise the step of forming secondary cushion portions of a smaller size to the cushion portions and being positioned inside a respective cushion portion.

The textile structure may be formed by any conventional process, such as weaving, knitting or braiding.

The method may be carried out on one of: narrow tape weaving machine, shuttle or needle loom, twin needle bar Rachel knitting machine, single needle bar raschel knitting machines (lace industry), a crochet knitting machine.

The advantages of the product of the first aspect of the invention and its embodiments applies mutatis mutandis to the method of the second aspect of the invention and its embodiments.

A preferred embodiment of the invention will now be described, by way of non-limiting examples, with reference to the accompanying drawings in which:

Figure la shows the cord according to the invention in use on a face mask;

Figure lb shows a cross section view of the cord and its effect on the skin;

Figures 2a and 2b show a first example of the construction of the cord;

Figures 2c and 2d show a cross section of the cushion portion and the pinched portion of the cord;

Figure 2e shows how the warp stitches and the elastomeric yarn is knitted in a stretched and relaxed configuration;

Figures 2f and 2g show how the weft yarns are configured and knitted with the warp stiches;

Figure 3 is a table illustrating the construction and materials of four examples of cord; and Figure 4 is a table illustrating the relative effect of changing variables on the properties of the cord.

Figure 1 shows an elastic cord 10 according to the invention being used in combination with a medical face mask 100. The cord 10 is secured to either side of the face mask 100 to from ear loops 110 that loop around the back of both ears of the wearer to secure the mask 100 in place over the nose, mouth and chin.

The elastic cord 10 has a nonuniform surface which is formed by a series of cushion portions 14 and pinched portions 16 formed between the cushion portions 14. As such, the surface experiences a series of peaks (at the cushion portions 14) and valleys (at the pinched portions 16). The cushion portions 14 may also be described as billow or bubble-like portions, and the pinched portions 16 may be described as constricted or nipped portions.

The cushion portions 14 are created by the construction of crimped textured yarns that are arranged to form a cushioned sheath around an elastomeric yarn (not shown in Figure la). It will be understood that there are many ways in which the crimped textured yarns can be arranged and constructed around the elastomeric yarn.

Figure lb illustrates how the cushion portions 14 (of a cushioned sheath 22 that is formed, as described in more detail below) distributes the pressure of the cord against the skin over its low dense surface area so as to absorb the pressure and reduce compression. This is in contrast to a conventional ("regular") cord which has a uniform and high dense construction that causes high compression on the skin.

One example of how the yarns of the cord according to the invention are arranged and constructed relative to one another is shown in Figures 2a and 2b. It is further illustrated by graphically representing the cross section of a cushion portion 14 and a pinched portion 16 in Figures 2c and 2d. As before, crimped textured yarns 18, 18F1, 18F2m 18R1, 18R2 are arranged around an elastomeric yarn 20 to form a cushioned sheath 22 which mimics a tubular shape. The construction of the crimped textured yarns 18, 18F1, 18F2, 18R1, 18R2 form a series of cushion portions 14 with pinched portions 16 formed therebetween. The pinched portions 16 are formed where the warp yarn (warp stitch) 23 holds the textured yarns 18, 18F1, 18F2, 18R1, 18R2 against the elastomeric yarn 20. Where the crimp textured weft yarns 18, 18F1, 18F2, 18R1 and 18R2 float without getting held by the warp stitch 23, it creates the bubble-like cushion portions 14 due to the bulky nature of the crimp textured yarns 18, 18F1..18R2 (this is described in more detail below).

The cord 10 shown in the figures is made using a warp knitting machine, more specifically a crochet warp knitting machine where each needle forms a series of stitches along the length direction (warp direction) of the fabric. In typical warp knitted fabric, the stitches are formed in a zig-zag pattern on adjacent needles so that all the stitches are connected to form a fabric. In crochet knitting, the stitches are formed as individual rows independent of each other. These stitch rows are called chain stitch, pillar stitch, warp stich or in shorten form as warp or pillar. In order to create a fabric, they are connected with one or more weft yarns, a yarn that gets laid across the width direction, in order to form a fabric. The width of the fabric depends on how many warp stitch rows are connected with the weft yarn/s. If all the warps are connected, it creates a full width broad fabric like lace. If only a few needles are connected, but with a minimum of 2, it creates a narrow width tape. The number of warp stitch rows being connected will determine the width of the tape.

Different fabric designs, narrow or broad fabric, can be made depending on the number of weft yarns used and the pattern in which they connect to the warp stitch. More sophisticated machines used in the lace industry are equipped with up to 95 design bars to perform this function. The more basic machines used in the narrow tape industry are equipped between 3 to 20 design bars. Most common machines are equipped with 8 design bars, A design bar, often referred as "bar" in shorten form, is a component on the machine that moves the weft yarn/s across the fabric width to connect the warp stitches. A set of guides are fitted on to the weft bar in order to present the weft yarn/s to the knitting zone of each needle. The guides are also referred to as weft guides, weft tubes or in shorten form guides/ tubes. The weft yarns are drawn through these guides and the tip of the guide is position near the knitting zone. When the design bar moves, the guides also move in the same pattern.

In order to create a stretch fabric, an elastomeric yarn 20 is fed as a weft yarn, typically to a 0-1-0-1 pattern, a basic zig-zag movement, so that the warp stitches 23 are formed around it as elaborated in Figure 2e. The elastomeric yarn 20 is laid in its stretched form so that when the fabric/ tape comes out of the take down rollers of the machine, it forces the fabric to contract, thus giving the fabric its stretch ability. This is elaborated in Figure 2e where the two states are shown side by side. As the elastomeric yarn 20 is much thicker and stiffer in comparison to the crimp textured yarns 18, 18F1...18R2, it dominates within the fabric structure/ construction. Therefore, as the fabric contracts, the elastomeric yarn 20 straightens, and the warp stitch row gets to a zig-zag state. The relatively high stiffness of the elastomeric yarn 20 and the knit pattern causes it to end up like a warp stitch when it contracts coming out of the machine. The stretch of the fabric is greatly dependent on the stretch in which the elastomeric yarn 20 is fed into the machine.

In the cord 10 of the invention, the warp stitches are not connected with each other using the wefts like in the case of typical elastic tapes. Instead, the weft yarns only work on the same needle, on the same warp stitch raw, thus creating a cord rather than a fabric or a tape. The construction and the choice of material allows it to have a tube-like appearance with a cushion sheath 22 around the elastomeric 20. Two of the weft yarns, 18F1 and 18F2 are arranged to work above the elastomeric yarn 20 and two more of the weft yarns 18R1, 18R2 are arranged behind it, as demonstrated in Figures 2f and 2g, so that they all get held with the warp stitch 23 when they cross its path. On the embodiment explained as an example, all 4 of these wefts cross each other on the same point to create the "nipped area" (i.e. the pinched portion 16) as demonstrated in Figures 2d, 2fand 2g. The tension of the warp stitch 23 compresses the bulky crimp textured yarn 18, 18F1...18R2, and so this yarn ends up being thinner than the rest of the area. In order to create the cushion area 14, these four warp yarns are floated by the side of the warp stitch 23 so that they don't get held by it, as graphically demonstrated in Figures 2c, 2f and 2g. Therefore, the crimped texture yarns 18, 18F1...18R2, that are bulky in their free form, are free to create an area with a higher volume than the nipped area 16. A natural property of crimp textured yarn 18 is that, as its pulled/ stretched it reduces its volume and as it is compressed, it increases its volume. Therefore, when the elastomeric thread 20 contracts the cord 10, the crimp textured yarns amplify in volume creating a bubble-like form between two pinched portions 16 as well as offer a cushion like sheath around the elastomeric yarn 20, as graphically illustrated in figure 2c. It is also possible to use additional weft bars to create further cushion bubbles within the cushion bubble portions 14 already created as described above. The example given above uses a float over 6 courses before the textured yarns cross over. A further four bars can be used to float over 4 courses positioned within the longer float (6 courses) so that a smaller cushion bubble is formed within the larger one to create a fuller bubble. Many other constructions also can be made make using the wide design capabilities and features present in the machine. The order in which these weft yarns are floated by the side and across the path of the warp stitches enables the creation of various designs and aesthetics.

Similar thick and thin areas (bubble-like and pinched areas) can be created by altering the pick/course density intermittently. Areas where the pick density is higher will be thinner than the area in which the prick density is low. Higher the difference, higher will be the difference between the thick and the thin regions.

It is also possible to change the feed rate or the tension of the weft yarns intermittently so that it changes the size of the bubble or the cushion thickness it creates.

The weft and warp configurations and materials for four examples of the elastic cord construction are shown in the table at Figure 3. The cord 10 shown in Figures 2a and 2b is the first listed cord in the table. The cords were formed on a Mueller RD3.8 type crochet knitting machine. As can be seen, two ends of 4/78/24 draw textured yarn ("DTY") was used as the crimped textured yarns 18, 18F1...18R2 on each weft and 1/78/24 DTY was used as the warp stitch 23. The warp stitch 23 may not be a textured yarn. A 620 Elastane was used as the elastomeric yarn 20. As can be seen in the second and fourth examples in the table of Figure 3, the crimped textured yarns 18 may be constructed so that the pinched portions 16 are formed in an offset manner as they are arranged in a rather helical fashion around the elastomeric yarn 20, This also allows for a more uniform surface as opposed to the prominent bubbles of the example of Figures 2a and 2b. This configuration may be used where it is preferred that the cord has a more uniform appearance but without compromising the cushion nature and the other comfort features of the cord 10. The surface nature can be altered greatly to be more uniform to achieve a similar appearance to conventional cords or with highly exaggerated bubbles by changing the course/ pick density and/or the length of the floats and/or thickness of the yarn and/or changing the pattern in which the weft yarns interlace while being able to keep the soft low dense sheath construction and it benefits described in this application.

The material of the crimped textured yarns 18, 18F1...18R2 may be Nylon, polyester, polypropylene or any similar material. These may be in standard or micro fiber form. They may also be virgin, recycled, bio based or degradable/ biodegradable.

The crimped textured yarns 18, 18F1...18R2 may be chosen to provide a desired bulkiness and density that is required on the cord, e.g. based on buyer preference or functionality. The characteristics of the crimped textured yarns 18 that can influence these factors are for example "the number of ends per weft tube" (e.g. 1, 2, 3 or any sensible number), different counts of yarns, different ply or different filament counts (e.g. on the weft configuration: 1/78/24, 2/78/24, 8/78/24, 1/156/48, 2/156/48, 4/156/48, 2/312/96, 3/312/96, 1/624/192); and the warp configuration: 1/44/24, 2/44/24, 2/78/24, 1/110/24...or similar), or a combination thereof.

The count and ply that is chosen on the warp stitch will depend on the breaking strength that is required. An example of breaking strength in the context of the invention is 10 N or more.

Moreover, the crimp textured yarn in the warp configuration (i.e. the warp stitch 23) may be a fine denier single covered or air covered elastomeric yarn, e.g. Dtex: 22, 44, 78, 156 or similar. The covering yarn may be single or multiple ply.

The elastomeric yarn 20 can have 1, 2, 3 or 4 ends fed through one yarn guide/tube to achieve the required modulus using a knit construction on one needle. Manufacturing on a single needle assists to achieve a more rounded cord like appearance as well as optimize the use of the needle bed to allow a maximum number of cords to be made on the machine.

For example, an elastic cord used on face masks needs a minimum of 20gf modulus at 40% stretch point when tested at l.5kgf load using a CRE (constant rate of elongation) machine. In order to achieve that, it requires a minimum of 1 end (preferably 2) of 620dtex elastomer or a combination of strands that amount to it, either as the body rubber or together with covered elastomer that may be used as the warp. Furthermore, the body rubber/elastane can also be a single or double covered elastomeric yarn if it is required to hide the grinning of the bare elastane or yield a higher modulus. Examples of higher denier elastanes are: dtex 940, 1240, 1880, 2500 or even 5000. It is also important to note multiple ends of an elastomer gives a better flexibility to the cord than a single end of the total count. It also makes it easier to fuse to the mask on modern semi and fully automated mask making machines. Body elastane can be natural or synthetic (virgin, recycled, biodegradable or degradable). Grinning or grin through is the phenomenon where the glossy elastomeric yarn being shown through the fabric/ tape or cord.

The elastic cord of the invention can be achieved using a narrow tape weaving machine, shuttle or needle loom or a twin needle bar Rachel knitting machine. It can even be made on raschel machines used for manufacturing lace, broad fabric, galloon lace or edge lace. Another type of knitting machinery used, predominantly in the narrow tape industry is crochet knitting machines, a machine typically designed and used for making low cost narrow elastic and rigid tapes. Crochet knitting machines are a type of warp knitting machinery that has only one needle bar. Therefore, making a tubular cord is not natural, usual or obvious. This invention addresses this with a novel and unique construction to achieve a tubular cord like tape.

Examples of crochet knitting machine are: Swiss brand Mueller's RD3, RD3.8, RD3 MT3, Italian brand Comez's, Comez 609, Comez 829, Comeztronic CT600 and Taiwanese brand Dah Heer's Dahu DH600, Dahu 608/ 750, Dahu 608/ R12BAC, DH 750-DNFAC.