Covering yarn comprising short cellulosic staple fibers and process for production thereof

Abstract

A yarn comprising a filament core and a staple fiber sheath comprising or consisting of at least 95% by weight of a mixture of a first fiber and a second fiber wherein the first fiber is a natural cellulose fiber and the second fiber is a regenerated cellulose fiber. The weight ratio of the first fibers to the second fibers is in the range of 70 / 30 to 80 / 20, preferably the ratio is about 75 / 25, the average length of the fibers of the sheath is in the range of 10 to 25 mm, preferably in the range of 12 mm to 20 mm, the 5% (n) index of the fibers of the sheath is between 25 mm and 40 mm, preferably between 28 and 36 mm, more preferably between 30 and 34 mm; the sheath has a staple fiber content, SFC (n), between 30% and 70%, preferably between 40% and 60%; and the filament core comprises a plurality of polyester filaments.

Description

TECHNICAL FIELD

[0001] The present invention relates to the field of yarn production. More specifically, the present invention relates to yarns using short cellulose (e.g. cotton) fibers typically obtained from the recycling of yarns and fabrics, and to processes for producing said yarns. The present invention also relates to a method of recycling cotton fabrics. BACKGROUND

[0002] Due to the cost and environmental impact of natural fiber production, methods have been developed to recycle natural fibers from textile waste in order to re-use them. A prominent example is the recycling of cotton from waste textiles (in particular fabric and yarn waste) to obtain recycled cotton fibers.

[0003] Known processes for the recycling of fabrics and yarns generally involve mechanically disassembling the textiles into loose fibers that can be used to spin new yarns. In this process, machines are used (e.g. by means of rotating drums with metal pins) to disassemble the fabric. The mechanical strain on the fibers in the yarns causes the original fibers to break into shorter fibers.

[0004] A problem with recycled cotton fibers is that their content of short length fibers makes them unsuitable or very unsuitable for use in the manufacture of yarns, in particular in ring spinning machines for the production of denim. Virgin cotton staple fibers have a higher amount of long fibers than recycled cotton fibers; for example, the average length L(n) (considering all fibers of the yarn) of virgin cotton is typically greater than 20 mm, while the average length L(n) of recycled short cotton fibers is typically less than 15 mm, typically between 6 and 15 mm, more often between 9 - 12 mm.

[0005] Therefore, it is difficult to properly use recycled (short) cotton fibers in yarn production by ring spinning.

[0006] The short length of cotton fibers results in yarns that are too weak, leading to poor fabrics, or can even be unworkable into yarns due to the breakage of fibers that occurs in the yarn manufacturing machine. For this reason, recycled cotton fibers have been mixed with virgin cotton fibers to impart acceptable mechanical properties and physical characteristics to the final yarn, such as the bulkiness and outer appearance of a yarn containing 100% virgin natural fibers (e.g. virgin cotton). The amount of virgin cotton fibers (CO) to recycled cotton fibers (RCO) in the yarn by weight depends on the yarn production technology. Typically, free end yarns can include up to 100% recycled cotton, while in ring yarns the RCO content does not exceed 40% by weight and generally the CO / RCO ratio by weight is in the range of 70 / 30 to 90 / 10.

[0007] It has also been proposed to use polyester filaments and fibres to improve the mechanical properties of yarns containing recycled cotton fibres. In the examples, polyester staple fibres are mixed with cotton fibres before being spun into yarns; these yarns have the disadvantage that they are not easily dyeable and have an undesirable appearance, i.e. a non-cotton appearance, due to the presence of polyester. The proposed examples in which polyester filaments are provided as core filaments in recycled cotton sheaths have the disadvantage that the recycled cotton fibre content is necessarily low, as mentioned above. Furthermore, they also fail to solve the problem, in particular because recycled cotton fibre sheaths are prone to breakage when stretched or tensioned.

[0008] There is therefore a need to solve the problems of the prior art and to provide a yarn in which all the cotton fibres are recycled fibres, which is ring spun and has a good appearance and good to excellent mechanical characteristics. SUMMARY

[0009] It is therefore an object of the present application to provide a yarn in which all the cotton fibres can be recycled short length cotton fibres and which has good to excellent mechanical properties and the appearance and external aspect of a yarn containing virgin cotton fibres.

[0010] It is a further object of the present application to provide a core-spun yarn containing elastic and stretchable short length cotton fibres.

[0011] Said object is achieved by virtue of the present application, which relates to a yarn according to claim 1.

[0012] The present application also relates to a method for producing a core-spun yarn having a sheath containing recycled (i.e. short length) cotton fibres according to claims 13 and 16. A further object of the present application is a staple fibre mixture according to claim 12.

[0013] In particular, the present application relates to a yarn and to a related production method according to the appended independent claims, while preferred aspects are recited in the dependent claims.

[0014] The expression "mixture of fibres" in the present description is used to identify a mixture of different fibres suitable for use in a ring spinning process to provide a sheath of a core-spun yarn. The individual fibres in the sheath of the yarn of the present application can be identified and, if necessary, physically removed from the mixture forming the sheath.

[0015] For the present invention, the term "regenerated cellulose fiber" or "man-made fiber" refers to any kind of cellulose-based staple fiber produced industrially. The term encompasses all kinds of regenerated cellulose fibers, such as Lyocell, viscose, Modal, bamboo (marketed bamboo fibers are usually regenerated cellulose fibers made from bamboo, i.e. synthetic rayon made from cellulose extracted from bamboo), Fortex, Cupro, acetate fibers, etc. These man-made staple fibers have a substantially constant length, such that the length of these fibers falls into a very small range, i.e. they have a low CV value (i.e. coefficient of variation). For the present invention, the average length of these fibers, measured with DIN 53805:1980-06, is in the range of 25 mm to 38 mm, preferably in the range of 29 mm to 35 mm. The preferred count of the regenerated fibers suitable for the present invention is in the range of 1 dtex to 3 dtex, preferably about 1.2 dtex. Preferred regenerated cellulose fibers for the present invention are sustainable cellulose fibers, such as FSC certified regenerated cellulose fibers.

[0016] For the present invention, the term "primary fiber" refers to cotton staple fibers derived from cotton that has not been processed into yarn and fabric and thus has a high fiber average length.

[0017] For the present invention, the term "natural cellulose fiber" refers to fibers obtained from animal or plant bodies. Preferred natural cellulose fibers are fibers as obtained or obtainable from the recycling of fabrics as well as fibers from plants such as cotton, hemp, flax, etc. Typically, the natural cellulose fibers used in the present invention are recycled fibers, which have a count close to each other, and they are usually within the count range of the regenerated cellulose fibers.

[0018] The term "recycled cotton fiber" in the following description refers to staple fibers of cotton derived from the mechanical processing (e.g. opening and classifying) of yarn and fabric; one possible way to identify these fibers is by measuring their average fiber length. In embodiments, the fiber average length L(n), as measured with DIN 53805:1980-06, is in the range of 6 to 16 mm. Linter falls within the definition of recycled cotton fibers. It is known that linters are staple fibers produced as waste in yarn production, typically they are removed from the yarn during the combing process.

[0019] The following Table 1 summarizes the fiber sizes of the fiber mixtures used as sheath in the yarn according to the present invention. These results can be obtained by known methods (e.g. DIN 53805:1980-06 or ASTM D1447) and known machines (e.g. Uster Afis Pro 2 or Textechno FCS-Fibrotest).

[0020] Table 1

[0021] Please note that the above values are obtained according to DIN 53805:1980-06, i.e. as average values. The minimum (Min) and maximum (Max) values in the above table are the minimum and maximum values of such average values. Thus, with reference to e.g. the average length, the average length of embodiments of the present invention is between 10 and 25 mm, preferably between 12 and 20 mm.

[0022] The following tables 2 and 3 summarize the corresponding values for the artificial or regenerated staple fibers used in the present invention.

[0023] Table 2

[0024] Table 3

[0025] For example, the recycled cotton fibers (short length fibers) can have the following values according to the count average fiber length L n defined specification.

[0026] Count average fiber length (L n ): 10.0 mm

[0027] CV %: 70.0

[0028] Staple content (less than 12.0 mm) %: 60.0

[0029] The same histogram applied to the viscose staple fibers generally provides the following values: Average fiber length (count) (L n ): 32,0 mm CV %: 24 Staple content (length less than 12 mm) SFC(n) %: 2,8 The above results are obtained by Uster Afis Pro 2.

[0030] Count average fiber length L n may be calculated by the following formula:

[0031] wherein: L n is the count average fiber length, n i is the number of fibers of length l i , and l i is the length of the fiber i .

[0032] And, as known in the art, the coefficient of variation (CV%) is the ratio between the standard deviation s of a distribution and its mean value

[0033] In the final mixture of the sheath, the high 5% (n) index is mainly due to the presence of longer regenerated cellulose fibers, while the high SFC (n) value is mainly due to the presence of short first fibers, for example the presence of recycled cotton fibers with a high percentage of short fibers.

[0034] According to the present application, the yarn is a core-spun yarn having a core comprising or consisting of polyester filaments. The linear density of the polyester filaments is in the range of 20 to 300 denier. The number of filaments is in the range of 6 to 288, while the total number of ends of the final yarn is in the range of 5 / 1 to 60 / 1 Ne. In a preferred embodiment, the weight ratio of the polyester filaments to the total weight of the yarn is in the range of 10 to 30%.

[0035] In an embodiment, the polyester filaments of the core of the yarn have an elongation at break of less than 15%, more preferably between 8% and 12%, even more preferably between 10% and 12%, when tested according to DIN ISO 2062.

[0036] According to an aspect of the present application, the yarn comprises a core of filaments and a sheath of fibers. The fiber sheath is made of first and second fibers. The first fibers are natural cellulose fibers, preferably recycled cotton staple fibers having an average length in the range of 6 to 16 mm, even more preferably of about 10 mm.

[0037] The second fibers are man-made fibers, preferably viscose, i.e. regenerated staple fibers, having an average length greater than the average length of the first fibers, preferably between 25 mm and 40 mm, more preferably between 28 mm and 36 mm. Particularly, a high quality yarn has been achieved when the second fibers are of about 32 mm, e.g. between 30 and 34 mm.

[0038] At least 95% of the fibers of the sheath are the above-mentioned first and second fibers, wherein the weight ratio of the first fibers to the second fibers is between 70 / 30 and 80 / 20.

[0039] In other words, the preferred embodiment has a sheath comprising (at least 95% by weight thereof) a mixture made of 70% to 80% of first fibers, i.e. recycled cotton fibers, while the remaining 20% to 30% by weight of the mixture is made of second fibers, i.e. viscose.

[0040] In a preferred embodiment, the recycled cotton fibers are of about 75% by weight of the mixture, and the regenerated cellulose fibers, e.g. viscose, are of 25% by weight of the mixture.​

[0041] The mixture of the fibrous sheath and the one or more polyester filaments present in the core allow the claimed fiber and filaments to be processed into yarns, which in turn can be processed into fabrics on the market with excellent properties. In particular, the resulting yarns can be ring spun, a process that was not possible before in yarns with a high percentage of staple fibers, such as recycled cotton fibers.

[0042] The average length of the fibers of the sheath, i.e. all the fibers of the sheath, is between 10 and 25 mm, preferably between 12 and 20 mm. The average length is the L(n) value measured according to DIN 53805:1980-06.

[0043] Test machines known in the art that can measure the above indices, i.e. L(n), 5%(n), SFC(n), are for example USTER AFIS PRO 2 or Textechno FCS-Fibrotest.

[0044] In the sheath, the 5%(n) index of the fibers, still measured according to DIN 53805:1980-06, is at least 25 mm, preferably between 25 mm and 40 mm, more preferably between 28 and 38 mm, and wherein the staple fiber content SFC(n) of the sheath, measured according to DIN 53805:1980-06, is between 30% and 70%, with a preferred value being higher than 35%, more preferably higher than 40%, i.e. between 40 and 70%.

[0045] According to a preferred aspect, the polyester filaments of the core have an elongation at break, when tested according to DIN ISO 2062, of less than 15%, preferably between 5% and 15%, more preferably between 8% and 12%, even more preferably between 10 and 12%.

[0046] The claimed elongation at break is the elongation of all the filaments of the core, tested together.

[0047] In particular, it was found that if the elongation of the core is low, i.e. less than 15% as previously described, the yarn production and weaving processes are easier. In particular, in these embodiments, the elongation of the core is typically similar to the elongation of the cotton fibers.

[0048] In fact, if the final yarn is tensioned, a polyester core with a high elongation, i.e. more than 15% or more than 20%, can cause the sheath to slip off the core and / or can cause breakage in the staple sheath.

[0049] The use of polyester filaments with a low elongation in the core favors the avoidance of the above problems.

[0050] Low elongation polyester filaments are known in the art and commercially available. They can be obtained by different methods. One possible solution is to provide a draft during the texturing step of the POY polyester filaments. This draft is preferably between 1.7 and 2.5, more preferably between 1.8 and 2.1.

[0051] In fact, the polyester filaments are preferably textured and, as mentioned above, a draft can be applied during the texturing process, usually also by heating the filaments during the texturing process during the draft step.

[0052] According to one aspect, the amount of polyester filaments of the core is between 10% and 35%, more preferably between 15% and 25%, even more preferably about 20% of the weight of the yarn. The above percentages are related to the total number of filaments of the polyester filaments, i.e. to the sum of the number of filaments.

[0053] According to one aspect, the total number of filaments of the polyester filaments is between 50 and 150 denier, more preferably between 60 and 120 denier, even more preferably between 75 and 100 denier.

[0054] As mentioned above, the average length of the second fibers of the sheath is greater than the average length of the first fibers.

[0055] The fiber length can be measured via a suitable machine (e.g. Uster Afis Pro 2 or Textechno FCS-Fibro test) with methods known in the art (e.g. AFIS (Advanced Fiber Information System) according to DIN 53805:1980-06 or ASTM D1447).

[0056] In order to measure the fiber properties and the fiber length of the sheath of the finished yarn (i.e. the L(n), SFC(n) and 5%(n) values), the sheath should first be separated from the core. This can be done by untwisting the yarn (i.e. applying a twist opposite to the twist of the yarn, e.g. S twist to a Z twisted yarn). This can be done manually or by a twister.

[0057] The obtained fibers can then be tested to determine their properties, i.e. to determine the presence of natural cellulose fibers and regenerated cellulose fibers. Possible known methods are AATCC 20 and 20A, or ISO 1833.

[0058] Subsequently, the fiber length can be tested, e.g. by DIN 53805 or ASTM D1447, by USTER AFIS PRO 2 or Textechno FCS-Fibrotest.

[0059] Preferably, in order to provide a better interaction between the first and second fibers of the sheath, the length of the second fibers is not too much longer than the length of the first fibers. The preferred ratio between the average length L(n) of the second fibers and the average length L(n) of the first fibers is between 1.5 and 3.8, more preferably between 2 and 3.5. It was found that the best results are obtained when the above ratio is between 2.5 and 3.3.

[0060] The yarn according to one or more of the preceding aspects can be used for the production of a fabric, in particular a woven (preferably denim) fabric and a garment comprising such a woven fabric. In particular, a fabric can be produced in which both in the warp and in the weft direction yarns according to the present application are used.

[0061] It was found that such a fabric and in particular a garment made from such a fabric can be made not from virgin (i.e. conventional) cotton, yet has similar wearing properties (hand, softness, etc.) and optical properties (brightness, dyeability, etc.) relative to a fabric made from conventional cotton yarns. Moreover, the fabric according to the present application shows similar mechanical properties, such as similar tensile strength, and better abrasion properties compared to a fabric made from conventional cotton yarns.

[0062] As an example, the abrasion of the fabric can be tested with the BS EN ISO 12947-2 method e test, whereby 25,000 to 30,000 cycles are performed.

[0063] If the test is continued even after these number of cycles, until the fabric breaks, the fabric according to the present application has a greater resistance (i.e. it breaks after a greater number of cycles) relative to a standard cotton yarn fabric or a fabric made from recycled cotton yarns.

[0064] It was tested that if three identical garments are tested, the only difference between these garments is that the first garment is made from virgin cotton yarns, the second garment is made from yarns comprising recycled cotton, and the third garment according to the present application is made with recycled cotton fibers as first fibers, if the abrasion test is continued until the garment under test breaks, the third garment will last 2 to 3 times as long as the first garment and 3 to 4 times as long as the second garment.

[0065] The core can consist of a plurality of polyester filaments, or can also comprise elastomeric filaments, such as elastane. Typically, in this case the core consists of polyester and elastomeric filaments.

[0066] The elastomeric filaments are typically in the range of 40 to 140 denier, and are typically drawn at least 2.0 times, more preferably about 3 times, prior to application of the sheath, such that they are of a lower count in the yarn (a count with a draw of 3.0 will be between about 13 and 47 denier). In particular, the draw of the elastomeric filaments is preferably between 2.0 and 4.0, more preferably at least 2.5, most preferably about 3.0.

[0067] An aspect of the present application also relates to a mixture of natural cellulosic staple fibers, preferably cotton staple fibers, and regenerated cellulosic staple fibers, preferably viscose staple fibers, for use in the yarn according to any of the preceding aspects, wherein: the weight ratio of the natural cellulosic fibers to the regenerated cellulosic fibers is in the range of 70 / 30 to 80 / 20, preferably the ratio is about 75 / 25; the average length of the fibers of the mixture is in the range of 10 to 25 mm, preferably in the range of 12 mm to 20 mm; the 5% (n) index of the fibers of the mixture is at least 25 mm, preferably at least 28, more preferably in the range of 28 and 38 mm; the staple fiber content SFC(n) of the sheath is at least 35%, preferably at least 40%.

[0068] The present application also relates to a method for producing a yarn, the method comprising the steps of: a) selecting a filament core comprising a plurality of polyester filaments; b) selecting a first fiber which is a natural cellulosic fiber; c) selecting a second fiber which is a regenerated cellulosic fiber; d) providing a staple fiber sheath comprising a mixture of at least 95% by weight of the first fiber and the second fiber, wherein the weight ratio of the first fiber to the second fiber is in the range of 70 / 30 to 80 / 20, preferably the ratio is about 75 / 25, wherein the average length of the fibers of the sheath is between 10 and 25 mm, preferably between 12 and 20 mm, wherein the 5% (n) index of the fibers of the sheath is between 25 mm and 40 mm, preferably between 28 and 38 mm, and wherein the staple fiber content SFC(n) of the sheath is between 30% and 70%, preferably between 40% and 70%; combining the filament core and the staple fiber sheath via ring spinning; The present invention also relates to a process for producing a yarn comprising the steps of: a) selecting a core comprising a plurality of polyester filaments; b) selecting a staple sheath, wherein at least 95% of the sheath is made of first fibers and second fibers, said first fibers being natural cellulose fibers, preferably having an average length between 6 and 16 mm, said second fibers being regenerated cellulose fibers, preferably having an average length greater than said first fibers and preferably greater than 25 mm, more preferably greater than 30 mm, said first fibers being recycled cotton fibers, said second fibers being regenerated cellulose fibers, the weight ratio of said first fibers to said second fibers being in the range of 70 / 30 to 80 / 20, preferably said ratio being about 75 / 25; c) combining said core and said staple sheath, preferably via ring spinning.

[0069] As mentioned above, preferably recycled materials are used, thus the first fibers of the sheath are recycled cotton fibers and / or the polyester filaments are made of recycled polyester. DETAILED DESCRIPTION

[0070] Exemplary and non-limiting embodiments will now be discussed with reference to the non-limiting drawings, in which: - Figure 1 is a histogram of recycled cotton fibers, - Figure 2 is a histogram of the mixture of fibers of the sheath of the yarn according to the invention; - Figure 3a and 3b is a comparison of tests performed on fibers of the same yarn made according to the invention, after being removed from a fabric ( Figure 3a ) and before being knitted ( Figure 3b ).

[0071] For the sake of discussion, the following general discussion will refer to: - recycled cotton fibers as first fibers of the sheath. However, the following description applies to other natural cellulose fibers as first fibers of the sheath, unless otherwise specified; - viscose fibers as second fibers of the sheath. However, the following description applies to other regenerated cellulose fibers as second fibers of the sheath, unless otherwise specified; - elastomeric filaments possibly present in the core in one or more elastomeric filaments. However, the following description applies to cores comprising a single elastomeric filament as well as one or more different elastomeric filaments, unless otherwise specified.

[0072] In a preferred embodiment, the yarn comprises a core provided with polyester filaments and possibly also with elastomeric filaments; the sheath is made of staple fibers comprising recycled cotton fibers and viscose fibers.

[0073] The polyester filaments are typically within 10% to 35% of the total weight of the yarn, typically about 20% of the yarn. The total denier of the polyester filaments is typically between 20 and 300 denier, with the most preferred embodiments using a total amount of polyester between 75 and 100 denier.

[0074] The polyester filaments (i.e. the polyester component of the core) have an elongation at break of less than 15%, more preferably between 8% and 12%, even more preferably between 10% and 12%. The test used to measure the elongation at break is DIN ISO 2062.

[0075] By way of comparison, a conventional polyester yarn produced initially in the same way but without the claimed drawing would be heavier (i.e. have a greater denier) and have a greater elongation at break of above 15%, typically in the range of about 17% - 25% when tested using the same test.

[0076] The elastomeric filaments (if present) are typically highly drawn (at a draw of greater than 2.0, typically about 3.0), and are present in the yarn in a low weight amount, and thus typically about 5 to 15% of the total weight of the yarn.

[0077] According to one aspect, the polyester filaments are joined together with the elastomeric filaments at least at a plurality of connection points in a known manner, and preferably by means of interlacing, twisting or mechanical co-extrusion. As mentioned above, the elastomeric filaments are preferably drawn prior to being joined with the polyester filaments.

[0078] According to one aspect, the continuous core fibre and elastomeric filaments are joined together in a continuous or substantially continuous manner by "mechanical co- extrusion" of the filaments, preferably under tension. In this co-extrusion process, also known as co-feeding, two (or more) fibre bundles (in a state of tension) are forced (fed together) through a restriction zone where the fibres adhere together to an extent such that they remain adhered after exiting the restriction zone.

[0079] The sheath is composed of staple fibres. At least 95% of the staple fibres of the sheath are a mixture of recycled cotton fibres, the mixture being made from 70% to 80% by weight of recycled cotton fibres, while the mixture is viscose.

[0080] Preferred embodiments have about 75% recycled cotton fibres and 25% viscose. If present, the remainder (up to 5%) can be other staple fibres. Typically, even if the mixture of recycled cotton and viscose fibres is not 100% of the fibres of the sheath, the recycled cotton fibres are at least 60%, typically at least 65% of the weight of the sheath. When the mixture of recycled cotton and viscose fibres is substantially 100% of the fibres of the sheath, the recycled cotton fibres are between 70% and 80% of the weight of the sheath.

[0081] The average length of the recycled cotton fibers is between 6 and 16 mm.

[0082] Typically, more than 90% (by number) of the recycled cotton fibers are below 30 mm. Embodiments in which 50% of the fibers are below 15 mm are possible.

[0083] The viscose fibers are longer than the recycled cotton fibers in order to provide strength to the sheath. However, as mentioned, it is preferred that they are not too much longer than the recycled cotton fibers in order to facilitate coupling and mixing of the fibers of the sheath.

[0084] The average length of the viscose fibers is greater than 25 mm, preferably greater than 30 mm, typically between 28 mm and 36 mm. In particular, it has been noticed that too long viscose fibers can reduce the quality of the final yarn. In view of this, the most preferred embodiments use viscose fibers of about 32 mm (for example between 30 mm and 34 mm). Typically, regenerated cellulose staple fibers (for example viscose staple fibers) produced by cutting viscose filaments have a uniform length.

[0085] The viscose filaments are preferably chosen so that their average length is between 1.5 times and 3.8 times, preferably between 2 times and 3.5 times, even more preferably between 2.5 times and 3.3 times the average length of the recycled cotton fibers.

[0086] The viscose fibers are mixed with the recycled cotton fibers to form a mixture which is at least 95% by weight of the fibers of the sheath. As mentioned, the ratio (by weight) between the viscose fibers and the recycled cotton fibers is between 20 / 80 and 70 / 30.

[0087] The average length of the fibers of the sheath is between 10 and 25 mm, preferably between 12 and 20 mm, while the 5% (n) index of the fibers of the sheath is at least 25 mm, preferably between 25 mm and 40 mm, more preferably between 28 and 38 mm. The short fiber content SFC(n) of the sheath is at least 35%, preferably at least 40%.

[0088] The apparatus for yarn production is known in the art and will not be discussed in detail here.

[0089] The method for production of the yarn according to the present application comprises providing a core by drawing the polyester filaments, and possibly combining them with the elastic fiber filaments.

[0090] The core is then combined with the sheath, which is typically provided in the form of one or more roves of staple fibers.

[0091] The obtained product is then spun into a yarn, preferably by ring spinning.

[0092] The obtained yarns can be used in textile articles, and in particular, the yarns according to the present application can be used in a fabric. In particular, they can be used as warp and / or weft yarns of a fabric.

[0093] In particular, it is an object of the present application a fabric, preferably a denim fabric, wherein all the warp and weft yarns are yarns according to the present application.

[0094] The warp yarns can be dyed (e.g. indigo dyed) while the weft yarns can not be dyed (although dyeing is possible).

[0095] As mentioned above, the fabric obtained with the yarns according to the present application provides an improved abrasion resistance with respect to a fabric made of standard cotton yarns and recycled cotton yarns.

[0096] Below an exemplary comparison is presented.

[0097] Fabric 1 is a fabric made of standard cotton yarns, while fabric 2 is a fabric made of warp and weft yarns according to the present application.

[0098] Fabric 1 was made according to the following parameters: - Warp composition: 100% cotton - Warp count: 10 / 1 Ne - Weft composition: 94% cotton / 6% elastane - Weft count: 16 / 1 Ne - Fabric weave: 3 / 1 denim weave, - Fabric composition: 98% cotton / 2% elastane.

[0099] Fabric 2 was made according to the following parameters: - Warp composition: 61% recycled cotton / 20% viscose / 19% recycled polyester - Warp count: 10 / 1 Ne (same as fabric 1) - Weft composition: 60% recycled cotton / 20% viscose / 14 recycled polyester / 6% elastane - Weft count: 16 / 1 Ne (same as fabric 1) - Fabric weave: 3 / 1 denim weave (same as fabric 1), - Fabric composition: 60% cotton / 20% viscose / 18% recycled polyester / 2% elastane.

[0100] The tests of these two fabrics were as follows: Table 4

[0101] The tear test was performed according to ISO 13937-1 with 5 and 10 home washes at 40°C with normal program followed by tumble drying. In each cell, the upper row indicates the value in the weft direction and the lower row indicates the value in the warp direction.

[0102] Table 5

[0103] The tensile strength test was performed according to ISO 1393-1 with 5 and 10 home washes at 40°C with normal program followed by tumble drying. In each cell, the upper row indicates the value in the weft direction and the lower row indicates the value in the warp direction.

[0104] Table 6

[0105] The abrasion test was performed according to ISO 12947-2 and was continued until the fabric under test broke.

[0106] From the above tests, it can be seen that the fabric according to the application has a similar tensile strength, a slightly improved tear strength, relative to the standard virgin cotton fabric. Thus, the fabric according to the application has a similar wearing performance, while retaining a similar optical performance, relative to the standard virgin cotton fabric.

[0107] In addition, the fabric of the application shows a better resistance to abrasion, improving the service life of the fabric.

[0108] The fiber composition and length can be tested according to the above method. They can be tested before weaving and after weaving by removing them from the fabric, while the results are similar. In this regard, Figure 1 and Figure 2 are tests performed on fibers that are not woven into a fabric. Figure 3a and Figure 3b show a comparison between the fibers of the yarn according to the application from the same group, where Figure 3a the test fibers come from yarn removed from the fabric, while Figure 3b the test fibers come from yarn after yarn production, before being woven into a fabric. It can be seen that the fiber length distribution is essentially the same.

Claims

1. Yarn comprising a filament core and a staple sheath, the staple sheath comprising or consisting of a mixture of at least 95% by weight of first and second fibers, wherein the first fibers are natural cellulosic fibers and the second fibers are regenerated cellulosic fibers, characterized in that: the weight ratio of the first fibers to the second fibers is in the range of 70 / 30 to 80 / 20, preferably the ratio is about 75 / 25; the average length of the fibers of the sheath is in the range of 10 to 25 mm, preferably in the range of 12 mm to 20 mm; the 5%(n) index of the fibers of the sheath is between 25 mm and 40 mm, more preferably in the range of 28 and 36 mm, even more preferably between 30 and 34 mm; the staple content SFC(n) of the sheath is between 30% and 70%, preferably between 40% and 60%; and the filament core comprises a plurality of polyester filaments.

2. The yarn of claim 1, wherein, the elongation at break of the polyester filaments of the filament core, measured according to DIN ISO 2062, is in the range of 5% to 15%, more preferably between 10% and 12%.

3. The yarn of claim 1 or 2, wherein, the natural cellulosic fibers are recycled cotton fibers.

4. The yarn according to any one of the preceding claims, wherein, the ratio of the average length of the regenerated cellulosic fibers to the average length of the first fibers is in the range of 1.5 and 3.8, preferably between 2 and 3.5, more preferably between 2.5 and 3.

3.

5. The yarn according to any one of the preceding claims, wherein, the core comprises one or more elastomeric filaments, preferably having a draft of 2.0 to 4.0, more preferably a draft of at least 2.5, most preferably a draft of about 3.

0.

6. The yarn according to any one of the preceding claims, wherein, the polyester filaments have a draft comprised between 1.5 and 2.5, preferably between 1.8 and 2.

2.

7. The yarn according to any one of the preceding claims, wherein, the polyester filaments are textured filaments.

8. The yarn according to any one of the preceding claims, wherein, the amount of the polyester filaments of the core is in the range of 10% to 30% by weight of the yarn, preferably between 15% and 25% by weight, more preferably about 20% by weight.

9. The yarn according to any one of the preceding claims, wherein, the total number of the polyester filaments is between 50 and 150 denier, preferably between 60 and 120 denier, more preferably between 75 and 100 denier.

10. The yarn according to any one of the preceding claims, wherein, the filament core and staple sheath are combined via ring spinning.

11. A textile article, preferably a denim fabric or garment, comprising the yarn according to one or more of the preceding claims.

12. A mixture of natural cellulosic staple fibers, preferably cotton staple fibers, and regenerated cellulosic staple fibers, preferably viscose staple fibers, for use in the yarn according to any one of claims 1 to 10, characterized in that: the weight ratio of the natural cellulosic fibers to the regenerated cellulosic fibers is in the range of 70 / 30 to 80 / 20, preferably the ratio is about 75 / 25; the average length of the fibers of the mixture is in the range of 10 to 25 mm, preferably in the range of 12 mm to 20 mm; the 5%(n) index of the fibers of the mixture is at least 25 mm, preferably at least 28, more preferably in the range of 28 and 38 mm; the average length of the fibers of the mixture is in the range of 10 to 25 mm, preferably in the range of 12 mm to 20 mm; The staple of said sheaf has a short fiber content SFC(n) of at least 35%, preferably at least 40%.

13. A method for producing a yarn, the method comprising the steps of: a. selecting a core comprising a plurality of polyester filaments; b. selecting a first fiber that is a natural cellulosic fiber; c. selecting a second fiber that is a regenerated cellulosic fiber; d. providing a staple sheaf comprising a mixture of at least 95 wt.% of said first fiber and said second fiber, wherein the weight ratio of said first fiber to said second fiber is in the range of 70 / 30 to 80 / 20, preferably said ratio is about 75 / 25, wherein the average length of the fibers of said sheaf is between 10 and 25 mm, preferably between 12 and 20 mm, wherein the 5%(n) index of the fibers of said sheaf is between 25 mm and 40 mm, preferably between 28 and 36 mm, and wherein the short fiber content SFC(n) of said sheaf is between 30% and 70%, preferably between 40% and 60%; e. combining said core and said staple sheaf via ring spinning.

14. The method of claim 13, wherein, The first fiber of said sheaf is a recycled cotton fiber.

15. The method of claim 13 or 14, wherein, The polyester filaments are made of recycled polyester.

16. A method for producing a yarn, the method comprising the steps of: a. selecting a core comprising a plurality of polyester filaments; b. selecting a staple sheaf, wherein at least 95% of said sheaf is made of a first fiber and a second fiber, said first fiber being a recycled cotton fiber, said second fiber being a regenerated cellulosic fiber, the weight ratio of said first fiber to said second fiber being in the range of 70 / 30 to 80 / 20, preferably said ratio is about 75 / 25. c. combining said core and said staple sheaf via ring spinning; 17. The method of any one of claims 13 to 16, wherein, The polyester filaments of said core have an elongation at break in the range of 5% to 15%, preferably between 10% and 12% when tested according to DIN ISO 2062. The polyester filaments of said core have an elongation at break in the range of 5% to 15%, preferably between 10% and 12% when tested according to DIN ISO 2062.

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