Core spun yarn comprising short cellulosic staple fibers and polymeric fibers and process for its production

Abstract

To provide a yarn in which all the cotton fibers are recycled, short length, cotton fibers and which has good to excellent mechanical properties and the look and aspect of a yam obtained from virgin cotton fibers.SOLUTION: There is provided a yarn comprising a filament core and a staple fiber sheath. Therein the staple fiber sheath is made of, or comprises at least 95 mass% of, a blend of first fibers and second fibers. Therein the first fibers are natural cellulosic fibers and the second fibers are synthetic fibers, characterized in that: a weight ratio of the first fibers to the second fibers is in a range of 65 / 35 to 35 / 65, preferably the ratio being in a range 40 / 60 to 60 / 40, more preferably about 50 / 50; wherein elongation at break of polyester filaments of the filament core, measured according to DIN ISO 2062, is in a range of 5 to 15%, more preferably between 10 and 12%.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to the field of yarn manufacturing and to textiles in general. More particularly, the present invention relates to yarns using short-staple cellulose, such as cotton staple fibers, typically obtained from recycling yarns and textiles, said yarns being suitable for workwear or medical clothing. [Background technology]

[0002] Due to the cost and environmental impact of natural fiber production, methods have been developed to regenerate natural fibers from textile waste and reuse them, a prominent example being the recycling of cotton from textile waste, particularly fabric and yarn waste, to obtain recycled cotton fibers.

[0003] Known recycling methods for fabrics and yarns involve mechanically breaking down the fabric into loose fibers that can be used to spin new yarns. This method uses machines that break down the fabric, for example, by means of a rotating drum with metal pins. The mechanical tension of the fabric in the yarn causes at least a portion of the original fibers to break down into shorter fibers.

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

[0005] Thus, it is difficult to properly use recycled (short length) cotton fibers in ring-spun yarn production.

[0006] Additionally, workwear and medical garments undergo frequent wash cycles that involve more aggressive temperatures and / or chemicals than domestic wash cycles, and recycled cotton yarns typically cannot withstand multiple industrial wash cycles.

[0007] Short cotton fibers produce yarns with too little strength (resulting in an unsatisfactory fabric) and cannot be processed into yarn due to the breakage of the composite fibers that occurs on the yarn-making machine. For this reason, recycled cotton fibers are blended with virgin cotton fibers to impart acceptable mechanical and physical properties, such as bulk and appearance, of yarns containing 100% virgin natural fibers, e.g., virgin cotton, to the final yarn. The ratio of the amount of virgin cotton fibers (CO) to recycled cotton fibers (RCO) in the yarn depends on the yarn manufacturing technology. Generally, open-end yarns contain less than 100% recycled cotton, while the RCO content in ring-spun yarns does not exceed 40% (by weight), with the CO / RCO ratio (by weight) typically ranging from 70 / 30 to 90 / 10.

[0008] It has also been proposed to use polyester filaments and fibers in the yarn composition to reduce the amount of cotton in the yarn. In one example, polyester staple fibers are mixed with cotton fibers before being spun into the yarn; these yarns suffer from a poor appearance, i.e., a non-cotton appearance, due to the presence of polyester.

[0009] US 20150176160 discloses a fabric provided from a core-spun yarn having a false twist textured yarn core and a cotton staple fiber sheath. JP362028426A discloses a polyolefin resin composition. EP3701840A1 discloses a method for recycling short staple cotton fiber residue.

[0010] Corespun yarns having a core containing polyester filaments are also known; the use of recycled cotton in corespun yarns is usually disadvantageous because the sheath of the recycled cotton tends to break down and slip relative to the core during manufacture. Summary of the Invention [Problem to be solved by the invention]

[0011] Thus, there is a need to solve the problems of the prior art and to provide a yarn in which cotton fibers are present in a good amount and all of the cotton fibers are recycled fibers, said yarn being a ring-spun yarn, having a good appearance and good to excellent mechanical properties, and in particular the yarn being suitable for workwear and medical clothing. [Means for solving the problem]

[0012] Thus, it is an object of the present invention to provide a yarn in which all the cotton fibers are recycled short staple cotton fibers and which has good to excellent mechanical properties and the appearance and texture of yarn obtained from virgin cotton fibers.

[0013] Another object of the present invention is to provide such yarns which can be easily woven into fabrics capable of withstanding repeated washing under harsh conditions and which are suitable for workwear and medical fabrics and garments.

[0014] Another object of the present invention is to provide a corespun yarn containing short cotton fibers that is elastic and stretchable.

[0015] The above object is achieved by the present invention according to one or more of the claims set forth in the appended claims.

[0016] In particular, the invention relates to yarns and suitable manufacturing methods according to the independent claims described above, while preferred embodiments are set out in the dependent claims. DETAILED DESCRIPTION OF THE INVENTION

[0017] The term "blend of fibers" is used herein to describe a mixture of various fibers suitable for use in a ring spinning process to provide the sheath of a core-spun yarn. The single fibers in the sheath of the present invention are identified, but physically excluded, from the blend that forms the sheath, as required.

[0018] For purposes of this invention, the term "virgin fiber" refers to cotton staple fiber that is derived from cotton that has a high average fiber length, for example, and is not recycled from yarn and fabric.

[0019] For the purposes of the present invention, the term "natural cellulose fibers" refers to fibers obtained from plants. Preferred natural cellulose fibers are fibers obtained or obtained from recycling processes of fabrics and fibers from plants, such as cotton, hemp, linen, etc. Generally, the natural cellulose fibers used in the present invention are recycled fibers having a similar count to each other.

[0020] The term "recycled cotton fibers" in the following description refers to cotton staple fibers derived from mechanical processing of yarns and fabrics, such as opening and sorting; a possible way to identify these fibers is by measuring their average fiber length. In a specific example, the average fiber length L(n) measured according to DIN 53805:1980-06 is in the range of 6 to 16 mm.

[0021] The term "synthetic fiber" refers to man-made fibers, especially fibers made from polymers synthesized from chemicals (see definition in ASTM D123, option (1) of "man-made fiber"). As such, synthetic fibers are polymeric, non-cellulosic fibers. Synthetic fibers are usually produced in filament (i.e., continuous) form. Synthetic staple fibers are commercially available and are obtained by cutting synthetic filaments. Preferred synthetic staple fibers are selected from polyesters and polyamides, preferably polyester fibers.

[0022] In a preferred embodiment, the polyester for the staple fibers is selected from semi-dull, dull, or full-dull polyesters; these polyesters are known and commercially available, for example, containing TiO to make the filaments dull. In a preferred embodiment, the polyester filaments for the staple fibers are not textured.

[0023] According to the present invention, the yarn is a core-spun yarn having a core comprising or consisting of polyester filaments. The linear density of the polyester filaments ranges from 20 to 300 denier. The number of filaments ranges from 6 to 288, with a total count of the final yarn ranging from 5 / 1 to 60 / 1 Ne.

[0024] In a preferred embodiment, the ratio of the mass of the polyester filaments to the total mass of the yarn is 30 to 70%, preferably 40 to 60%.

[0025] According to the present invention, the yarn comprises a filament core and a staple fiber sheath. The fiber sheath is comprised of first and second fibers. The first fibers are natural cellulose fibers, preferably cotton staple fibers having an average length in the range of 6-16 mm, more preferably about 10 mm, which is a typical average length for recycled cotton fibers.

[0026] The second fibers are synthetic fibers, i.e., polymeric non-cellulosic fibers. In a preferred embodiment, the second fibers are made of polyester or polyamide.

[0027] The preferred average length for the second fibers is greater than the average length of the first fibers, preferably in the range of 25 to 40 mm, more preferably 28 to 36 mm. High quality yarns are particularly achieved using second fibers in the range of about 32 mm, e.g., 30 to 34 mm.

[0028] At least 95% of the fibers in the sheath are the above-mentioned first and second fibers, and the mass ratio of the first fibers / second fibers is 65 / 35, preferably, the ratio is in the range of 40 / 60 to 60 / 40.

[0029] In a preferred embodiment, the first fibers are about 50% by weight of the blend and the second fibers are 50% by weight of the blend.

[0030] The blend of the fiber sheath with the presence of one or more polyester filaments in the core provides the claimed fibers and filaments that can be processed into yarns that themselves can be processed into fabrics with excellent commercial properties. In particular, the resulting yarns can be ring-spun, which has not previously been possible with yarns having a high percentage of short fibers, such as recycled cotton fibers.

[0031] The elongation at break of the polyester filaments of the filament core, when tested according to DIN ISO 2062, is 5 to 15%, preferably 5 to 12%, more preferably 10 to 12%.

[0032] The claimed elongation at break is the elongation of all filaments in the core tested together.

[0033] In particular, it has been found that the yarn manufacturing and weaving process is easier and significantly more efficient when the core has a low elongation (i.e., 15% or less as measured by DIN ISO 2062 as described above), particularly in these embodiments where the core elongation is typically similar to the sheath elongation.

[0034] In fact, when the final yarn is tensioned, a polyester core with a high elongation (e.g., 15% or more, or 20% or more) can cause slippage of the sheath from the core, not destroying the core filament but causing breaks in the staple fiber sheath.

[0035] The use of low-elongation polyester filaments in the core contributes to avoiding the above problems; in fact, when the yarn according to the invention breaks, the core filaments also break, so that there is no or very limited slippage of the sheath relative to the core. In this way, the broken yarn is joined in the usual way.

[0036] Low-elongation polyester filaments are known in the art and are commercially available. They can also be obtained by other methods. A possible solution is to provide a draft during the texturing process of the POY polyester filaments. Such a draft is preferably between 1.7 and 2.5, more preferably between 1.8 and 2.1.

[0037] The polyester filaments are, in fact, preferably textured and, as mentioned above, draft is applied during the texturing process, usually by heating the filaments during the drafting step in the texturing process.

[0038] According to one embodiment, the amount of polyester filaments in the core is between 30 and 70% of the mass of the yarn, more preferably between 40 and 60%, said percentages relating to the total count of polyester filaments, i.e. the total sum of the counts of the filaments.

[0039] According to one embodiment, the total count of the polyester filaments is 50 to 300 den, more preferably 80 to 200 den, and even more preferably 100 to 150 den.

[0040] As described above, the second fibers of the sheath have an average length greater than that of the first fibers. Generally, the average length of the second fibers is at least 200% greater than that of the first fibers, and preferably at least 250% greater than that of the first fibers. In other words, the ratio of the average length of the second fibers to the average length of the first fibers is at least 2.0, preferably at least 2.5.

[0041] Fiber length is measured by methods known in the art, for example AFIS (Advanced Fiber Information System) according to DIN 53805:1980-06 or ASTM D1447, via suitable equipment, for example an Uster Afis Pro 2 or a TexTechno FCS-Fibro test.

[0042] To determine the fiber characteristics and fiber length of the first and second fibers in the sheath of a finished yarn, the sheath must first be separated from the core and broken down into individual fibers. This can be done, for example, by untwisting the yarn (e.g., by applying an opposite twist to the yarn's twist, e.g., S-twisting a Z-twisted yarn). Fiber length is then tested, for example, via DIN 53805 or ASTM D1447, USTER AFIS PRO 2, or Textechno FCS-Fibrotest. In a fiber histogram, the amount of short fibers can be detected; similarly, synthetic staple fibers generally always have substantially the same length and are therefore visible in the histogram.

[0043] The first fibers are separated from the second fibers via known chemical or biological methods. For example, known methods are used to isolate natural cellulose fibers, particularly when the first fibers are cotton fibers and the second fibers are polyester or polyamide fibers, in which the synthetic fibers dissolve while the first fibers remain substantially intact.

[0044] Similarly, it is possible to isolate synthetic fibers from natural cellulose fibers, for example, through known enzymatic processes that break down cellulose, usually converting it to glucose.

[0045] The fibers are also separated by hand and tested.

[0046] A property of the first or second fiber, such as length, may be tested in this manner.

[0047] Preferably, the length of the second fibers is not much greater than the length of the first fibers to provide good interaction between the first and second fibers of the sheath. The ratio L(n) of the average length of the second fibers L(n) to the average length of the first fibers L(n) is second / L(n) first The value of this ratio is between 1.5 and 3.8, more preferably between 2 and 3.5. It has been found that the best results are obtained when the value of this ratio is between 2.5 and 3.3.

[0048] The yarns according to one or more of the above embodiments are used to manufacture fabrics, in particular woven fabrics and garments comprising said woven fabrics. In particular, it is possible to manufacture fabrics in which the yarns according to the invention are used in both the warp and weft directions.

[0049] Although such fabrics, and in particular garments made from such fabrics, are made without using virgin (i.e., common) cotton, they have been found to have similar wearability (handle, softness, etc.) as well as optical properties (luster, dyeability, etc.) to fabrics made from common cotton yarns. Also, compared to fabrics made from common cotton yarns, fabrics according to the present invention exhibit similar mechanical properties, e.g., similar tensile strength, as well as better abrasion properties. Thus, fabrics made from yarns according to the present invention are effectively used in the manufacture of garments in the fields of workwear and medical clothing.

[0050] As noted above, the core can be comprised of a plurality of polyester filaments, and in specific examples, the core can also comprise one or more elastic filaments. Preferably, elastomeric fibers are used as the elastic filaments to withstand the aggressive industrial washing cycles to which workwear and medical garments are subjected. Preferred elastomeric fibers are known and commercially available as XLANCE.

[0051] The elastomeric fibers are typically 30 to 160 den, preferably 40 to 140 den; before being applied to the sheath, the fibers are typically drafted at least 2.0 times, more preferably about 3.0 times, so that the yarn count will be similar (at 3.0 draft, the dimensions will be about 13 to 47 den). In particular, in certain embodiments, the elastomeric fibers have a draft of 2.0 to 4.0, more preferably at least 2.5, and most preferably about 3.0.

[0052] In another specific example, the draft of the elastomeric fiber is 4.0 or more, preferably 4.0 to 6.0, and more preferably 4.0 to 5.0.

[0053] The present invention also relates to a method of 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 synthetic fiber, preferably a polymeric non-cellulosic fiber; d) providing a staple fiber sheath comprising at least 95% by weight of a blend of the first fiber and the second fiber, wherein the mass ratio of the first fiber / second fiber is between 65 / 35 and 35 / 65, preferably the ratio is about 50 / 50; and combining the filament core and the staple fiber sheath via ring spinning to obtain a core-sheath yarn.

[0054] The present invention 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, wherein the elongation at break of the polyester filaments of the filament core is between 5 and 15%, more preferably between 10 and 12%, measured according to DIN ISO 2062; and b) selecting a staple fiber sheath, wherein at least 95% of the sheath is made of first fibers and second fibers, the first fibers being natural cellulose fibers, preferably having an average length between 6 and 16 mm, and the second fibers being synthetic filaments, preferably having an average length between 25 and 40 mm, that are larger than the first fibers.

[0055] As mentioned above, preferably recycled materials are used, so that the first fibers of the sheath are recycled cotton fibers and / or the polyester filaments are made from recycled polyester.

[0056] According to a preferred embodiment, the dyeing is carried out in a single bath (both the dye for cotton fibers and the dye for synthetic fibers are present).

[0057] The above process provides good quality and uniform dyeing of the yarn even if part of the sheath is made of polyester filaments.

[0058] According to a preferred embodiment, the fabric is typically stabilized during sanforizing by passing it over curved or bow-shaped rolls. As a result, the rolls impart different forces (at least in different directions) to different portions of the fabric. This, in turn, imparts twist (torque) forces to the fabric, preventing or at least limiting yarn movement (particularly in diagonal weaves, e.g., twill weaves) that would tend to impart shear forces to the final fabric, thereby causing movement of one outer edge of the fabric relative to the other edge in the warp direction.

[0059] Detailed Description of the Invention

[0060] Illustrative and non-limiting examples are now considered.

[0061] For ease of discussion, the following discussion will refer to recycled cotton fibers as the first fiber of the sheath. However, unless otherwise specified, the following description also applies to other natural cellulosic fibers as the first fiber of the sheath. The second fiber will be referred to as a synthetic fiber.

[0062] According to a preferred embodiment, the yarn is provided by polyester filaments and possibly also by elastomeric fibers; the sheath is made of staple fibers and comprises recycled cotton fibers and polyester fibers.

[0063] The core polyester filament comprises 20-70% of the total weight of the yarn, typically 30-60% of the yarn. The total polyester filament count is generally 20-300 den, although in the most preferred embodiment, a total polyester count of 100-150 den is used.

[0064] The elongation at break of the polyester filaments (i.e., the polyester component of the core) is 5 to 15%, more preferably 8 to 12%, and even more preferably 10 to 120%. The test method for measuring the elongation at break is DIN ISO 2062.

[0065] In contrast, conventional polyester yarns (first produced in the same manner, but without the draft of the present invention) are heavier (i.e., have a higher count) and have a higher elongation at break (15% or more, typically in the range of 17-25% when tested using the same test method).

[0066] When present, the elastomeric fin fibers are typically highly drafted (having a draft of 2.0 or greater, usually 3.0 or greater, and preferably 4.0-6.0) and are present in the yarn at a low mass, thus typically about 5-15% of the total mass of the yarn. It has been found that a high draft (4.0 or greater) reduces the occurrence of breaks and thus provides for easier processing of the elastomeric fin into yarn and easier weaving of the elastomeric fin filaments into fabrics.

[0067] According to one embodiment, the core polyester filaments and the elastomeric fin filaments are compounded together at least at a plurality of connection points by known methods, preferably by interweaving, twisting, or mechanical coextrusion. As noted above, the elastomeric fin filaments are preferably drafted before being compounded with the core polyester filaments.

[0068] In a preferred embodiment, the core polyester filaments and elastomeric fin filaments are bonded together in a continuous or substantially continuous manner, preferably under tension, by "mechanical co-extrusion" of the filaments. During such co-extrusion (also known as co-feeding), two (or more) bundles of fibers (under tension) are forced through an aperture (where the fibers are attached together to the extent that they remain attached after exiting the aperture).

[0069] The sheath is made of staple fibers, at least 95% of which is a blend of recycled cotton fibers, at least 35-65% by weight of the blend being recycled cotton fibers, and the remaining fibers in the blend being synthetic fibers.

[0070] A preferred embodiment has about 50% recycled cotton fibers and 50% synthetic fibers, with the remaining portion (5% or less) being other staple fibers, if any.

[0071] The average length of recycled cotton fibers is 6-16 mm.

[0072] Typically, 90% or more (by number) of the recycled cotton fibers are 30mm or less. Specific examples where 50% of the fibers are 15mm or less are possible.

[0073] The synthetic fibers are longer than the recycled cotton fibers to provide strength to the sheath, but as noted above, preferably not much longer than the recycled cotton fibers to promote coupling and intermingling of the fibers in the sheath.

[0074] The synthetic fibers have an average length of at least 25 mm, preferably at least 30 mm, typically 28-36 mm. Synthetic fibers that are too long can degrade the quality of the final yarn. In this regard, in the most preferred embodiment, synthetic fibers of about 32 mm, e.g., 30-34 mm, are used. Generally, the synthetic fibers have a uniform length (produced via cutting of synthetic filaments).

[0075] Preferably, the synthetic fibers are selected so that their average length is 1.5 to 3.8 times the average length of the recycled cotton fibers, preferably 2 to 3.5 times, more preferably 2.5 to 3.3 times the average length of the recycled cotton fibers.

[0076] Preferred synthetic fibers are polyester or polyamide fibers, more preferably polyester fibers.

[0077] To provide good mechanical properties for the final yarn used to make fabrics for heavy-duty applications, such as workwear and medical clothing, it is preferable to use high tenacity synthetic fibers. High tenacity synthetic fibers are fibers, preferably polyester staple fibers, having a tenacity of 6 g / den or more, preferably 7 g / den or more, and more preferably 8 g / den or more. High tenacity staple fibers are obtained by cutting high tenacity synthetic filaments into multiple parts (i.e., fibers), the synthetic filaments having a tenacity of 6 g / den or more, preferably 8 g / den or more. In addition, the tenacity is typically 10 g / den or less.

[0078] To test the toughness of synthetic fibers, the synthetic fibers are first isolated from the cotton fibers, for example, via mechanical separation or via degradation (via an enzymatic process), and then tested using machines and methods known in the art.

[0079] The synthetic fibers and recycled cotton fibers are mixed to form a blend that is at least 95% by weight of the sheath fibers; preferably, the blend is 100% by weight of the sheath, i.e., the sheath consists of such a blend. As discussed, the ratio (by weight) between the synthetic fibers and the recycled cotton fibers ranges from 35 / 65 to 65 / 35.

[0080] Yarn manufacturing equipment is known in the art and will not be discussed in detail here.

[0081] The process for making the yarn according to the invention comprises drawing polyester filaments and possibly combining them with elastomeric filaments to provide a core.

[0082] The core is then composited with a sheath (usually provided in the form of one or more rovings of staple fibers).

[0083] Synthetic staple fibers are obtained by cutting continuous filaments, such as polyester or polyamide filaments. As noted above, in preferred embodiments, the original filaments have a tenacity of 6 g / den or greater, preferably 8 g / den or greater. A preferred method for measuring tenacity is by applying ASTM D3822.

[0084] The resulting product is then spun into yarn, preferably through a ring.

[0085] The resulting yarns are used in textile products, in particular yarns according to the invention are used in fabrics for products in workwear in the medical industry, in particular the yarns are used as warp and / or weft threads in the fabrics.

[0086] According to a preferred embodiment, dyeing is performed in a single bath (where both dyes for natural cellulose fibers and dyes for synthetic fibers are present). Particularly when the sheath is comprised of a blend of cotton and polyester fibers, dyeing is preferably performed in a single bath. In a preferred embodiment, the single bath comprises a VAT dye (e.g., indanthrene) and a disperse dye to simultaneously dye the cotton staple fibers and polyester staple fibers of the sheath. The yarn may be dyed before or after it becomes part of the fabric (e.g., by weaving).

[0087] In particular, fabrics in which all warp and weft yarns are yarns according to the invention are an object of the invention. A preferred embodiment comprises warp yarns without elastomeric filaments and weft yarns with elastomeric filaments. However, fabric embodiments in which the yarns have no elastomeric filaments at all or in which both the warp and weft yarns have elastomeric filaments are also within the scope of the invention.

[0088] As mentioned above, fabrics made with yarns according to the present invention have improved abrasion performance relative to fabrics made with standard cotton yarns and recycled cotton yarns.

[0089] The composition and length of the fibers are tested according to the methods described above. They are tested by removing them from the fabric both before and after weaving, with similar results.

[0090] Below we consider examples of fabrics made with yarns according to the invention: Weave: 2 / 1 Z Twill Mass: 195 g / m 2 Width: 140cm Dye=VAT+disperse dye Fabric composition = Recycled PES: 46% (w / w), PES (non-recycled): 24% (w / w), Recycled cotton: 24% (w / w), Elastofin: 6% (w / w) Warp count = 20 / 1Ne Warp core = 150 den recycled polyester Warp sheath = 50% (w / w) recycled cotton and 50% (w / w) polyester Warp composition = 56.4% recycled PES, 21.8% PES, 21.8% recycled cotton Weft count = 18 / 1Ne Weft core = 100 den recycled polyester + 140 den elastomeric Weft composition = 33.9% recycled PES, 23.5% PES, 23.5% recycled cotton, 19.1% elastoflex Weft sheath = 50% (w / w) recycled cotton and 50% (w / w) polyester

[0091] The above exemplary fabrics were tested with the following results: Width (ISO 22198 - Unwashed) = 140 cm Mass (BS EN 12127-unwashed) = 195 g / m 2 (Min=-5%, Max=+5%) Dimensional stability to washing (ISO 15797-5x75°C) = Warp: -1% (min = -1%, max = 0%), Weft: -0.5% (min = -3%, max = 0%) Elasticity (ASTM D3107) = Weft: 15.2% Elongation (ASTM D3107) = Weft: 2% Colour fastness to crocking (BS EN ISO 105:X12) = Dry: 4.5 Color fastness to dry cleaning (BS EN ISO 105:D01) = Discoloration: 3.5 Color fastness to sweat (BS EN ISO 105:E04-Acid) = Discoloration: 4.5, Cotton Discoloration: 4.5, Polyester Discoloration: 4.5 Color fastness to sweat (BS EN ISO 105: E04 - alkaline) = Discoloration: 4.5, Cotton Discoloration: 4.5, Polyester Discoloration: 4.5 Color fastness to washing (ISO 105 C06-E1S-95°C) = Discoloration: 4, Cotton: 3.5, Polyester: 3 Anti-pilling (ISO 12945-2 -5000 Rev.-5x75℃) = Grade: 3.5 Tensile strength (ISO 13934-1) = Warp: 750 N, Weft: 350 N Wrinkle recovery (AATC 124-3x75℃) = Grade: 3.5

Claims

1. 1. A yarn comprising a filament core comprising polyester filaments and a staple fiber sheath, said staple fiber sheath comprising at least 95% by weight of a blend of first fibers and second fibers, or preferably consisting of 100% by weight of said blend, wherein said first fibers are natural cellulose fibers and said second fibers are synthetic fibers, wherein the mass ratio of said first fibers to said second fibers is in the range of 65 / 35 to 35 / 65, preferably said ratio is in the range of 40 / 60 to 60 / 40, more preferably about 50 / 50, and wherein the elongation at break of the polyester filaments of said filament core is in the range of 5 to 15%, more preferably in the range of 10 to 12%, as measured according to DIN ISO 2062.

2. 2. The yarn of claim 1, wherein the average length of the natural cellulose fibers is 6 to 16 mm.

3. 2. The yarn of claim 1, wherein the average length of the synthetic fibers is 25 to 40 mm.

4. The yarn of claim 1 , wherein the first fiber is a cotton fiber.

5. The yarn of claim 1 , wherein the second fiber is a polyester fiber or a polyamide fiber.

6. 2. The yarn of claim 1, wherein the second fiber has a tenacity of 6 g / den or greater, preferably 7 g / den or greater, more preferably 8 g / den or greater, wherein tenacity is measured according to ASTM D3822.

7. 10. The yarn of claim 1, wherein the core comprises at least one elastomeric fin filament.

8. 8. The yarn of claim 7, wherein at least one elastomeric fin filament has a draft of 4.0 to 6.

0.

9. 1. A method of making a yarn, comprising: selecting a filament core comprising a plurality of polyester filaments, wherein the elongation at break of the polyester filaments of the filament core is in the range of 5 to 15%, preferably 10 to 12%, when tested according to DIN ISO 2062; selecting a first fiber that is a natural cellulosic fiber; selecting a second fiber, the second fiber being a synthetic fiber; providing a staple fiber sheath comprising at least 95% by weight of a blend of said first fibers and said second fibers, wherein the weight ratio of said first fibers to said second fibers is in the range of 65 / 35 to 35 / 65, preferably in the range of 40 / 60 to 60 / 40, and more preferably about 50 / 50; combining said filament core and said staple fiber sheath, preferably via ring spinning. The method comprising:

10. 10. The method of claim 9, wherein the first fibers of the sheath are recycled cotton fibers.

11. 10. The method of claim 9, wherein the polyester filaments of the core are made from recycled polyester.

12. 10. The method of claim 9, wherein the second fibers of the sheath are obtained by cutting filaments into staple fibers, and the filaments have a tenacity of 6 g / den or more, preferably 7 g / den or more, more preferably 8 g / den or more, wherein the tenacity is measured according to ASTM D3822.

13. 10. The method of claim 9, wherein the yarn is dyed in a bath in the presence of two different dyes.

14. 14. The method of claim 13, wherein the first fibers are cotton fibers and the second fibers are polyester fibers, and the yarns are dyed preferably in a bath comprising a VAT dye and a disperse dye.