Composite yarn with core and sheath

Abstract

A composite yarn (1) having a core (2) and a sheath (3), wherein the sheath preferably comprises staple fibers (3a), the core (2) comprises at least one polymer core fiber (21), preferably a plurality of core fibers (21) made of a polymer material, the total amount of the core fibers being at least 35% by weight of the total weight of the composite yarn (1), and the core fiber (21) and the sheath (3) being spun together. [Selected Figure] Figure 1

Description

[Technical field]

[0001] The present invention relates to a composite yarn having a core fiber and a sheath fiber that encases or covers the core fiber. More particularly, the present invention relates to a composite yarn having a core fiber and a sheath fiber, the core containing a plurality of core fibers, preferably having elastic properties as a composite yarn. The yarn of the present invention is particularly suitable for the manufacture of casual, sports and comfort garments, including denim garments. [Background technology]

[0002] In the technical field of the present invention, a yarn having a core containing a polymer filament is known. Patent Document 1 discloses a yarn containing a core containing at least one elastic filament, most preferably spandex and / or lastol filament, and a non-elastic filament made of a false-twist textured polymer or copolymer of polyamide, polyester, polyolefin and mixtures thereof. According to Patent Document 1, the false-twist textured filament is loosely wound around the elastic filament.

[0003] The patent application WO 2005 / 023634, filed in the name of the present applicant, discloses an elastic yarn having a composite elastic core and a sheath of cotton fibres. The elastic core comprises first and second filaments, each having a different elasticity, the first filament being an elastomer and the second filament being a polyester-based (co)polymer having limited elasticity. The second polyester-based (co)polymer fibre constitutes in the range of 60-90% by weight (w / w) of the elastic core.

[0004] US Patent No. 5,399,633 discloses a core spun yarn having bicomponent polyester filaments and elastomeric fibers, in which the polyester filaments include poly(trimethylene terephthalate) and either poly(ethylene terephthalate) or poly(tetramethylene terephthalate) to prevent grinning of the elastic core, and the elastomeric fibers include spandex. The bicomponent polyester filaments are stretched at a ratio of 1.01 to 1.30, and the elastomeric fibers are stretched to 2.50 to 4.50 times their original length. Patent Document 4 discloses a core yarn having a false twisted monofilament core and a staple fiber sheath. The core has a fineness of 2 to 20 denier and is twisted with staple fibers. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] EP 3208371A1 [Patent Document 2] US 2013 / 0260129A1 [Patent Document 3] US 2008 / 0318485A1 [Patent Document 4] US 2008 / 0299855A1 Summary of the Invention [Problem to be solved by the invention]

[0006] A problem with known yarns having a composite elastic core, especially stretch yarns, is that a large amount of cotton must be used to avoid the so-called "greasing", i.e. surfacing, of the core through the sheath of the fibers. The use of large amounts of staple fibers, especially cotton fibers, is costly. In particular, it is known to use a certain number of long cotton fibers to make the fabric look good, which is expensive, and the use of short fibers with a high degree of twist can cause the yarn to become "curly" and uneven, which makes the fabric obtained from this yarn look less attractive.

[0007] Another problem with known art yarns is that the use of large amounts of cotton is not environmentally friendly because cotton cultivation requires large amounts of water and dyeing cotton requires large amounts of water and energy.

[0008] One object of the present invention is to solve the above problems and provide yarns and fabrics having a synthetic core with the required good elasticity, excellent appearance and low cost.

[0009] It is a further object of the present invention to provide a yarn having a synthetic core completely covered by a fiber sheath, preferably a cotton sheath, such that the core is not visible through the fiber at the surface, especially after use.

[0010] It is a further object of the present invention to provide a yarn and fabric that is soft to the touch and comfortable to the user.It is a further object of the present invention to provide a yarn that is environmentally friendly and inexpensive to produce. [Means for solving the problem]

[0011] These and other objects are achieved by the yarns, articles, and methods set forth in one or more of the claims of the present application.

[0012] In particular, the invention relates to yarns, articles and methods as set out in the independent claims, and preferred aspects of the invention are set out in the dependent claims.

[0013] One aspect of the invention relates to a composite yarn having a core and a sheath, said core comprising at least one, preferably a plurality of, fibers made of a polymeric material, the total amount of fibers of said core being present in an amount of at least 35% by weight of the total weight of said composite yarn. Preferred embodiments are set out in the dependent claims.

[0014] According to one embodiment of the invention, the core fiber has a linear density of 14 denier or less, preferably 10 denier or less, and more preferably the linear density is in the range of 0.2 to 8 denier. According to a possible embodiment, the denier of the core fiber is between 2 and 8 denier. The preferred core fibres are long fibres. Preferably there are at least 12 long fibres in the core.

[0015] The core fibers are preferably made of non-elastomeric fibers, some of which may be elastic. Elastomeric long fibers can also be added to the core and combined with the non-elastomeric core fibers. Therefore, the above percentage of the core fibers refers only to the non-elastomeric fibers present in the core. In other words, the non-elastomeric fibers present in the core are at least 35% by weight of the total weight of the yarn.

[0016] The present invention provides composite yarns having fewer sheath fibers than the corresponding yarns of the prior art. More specifically, the amount of sheath fibers used in the yarns of the present invention can be about 30-40% less than the amount of sheath fibers required in the corresponding average yarns of the prior art. Reducing the amount of sheath fibers brings several advantages. The first is the sustainability of the yarn manufacturing process: a yarn with less cotton content than the conventional technology requires less cotton and therefore less water to grow the cotton, leading to water savings. Also, since less cotton (or other sheath fibers) is dyed, less dye needs to be used in the dyeing process. Therefore, the drying process of the yarn is also shorter and requires less energy compared to the conventional technology.

[0017] Furthermore, the yarns of the present invention have a very good appearance, because the core yarn is substantially not exposed to the surface, despite the high amount of fibers used in the core. Furthermore, it has been found that it is possible to use a higher percentage of short fibers in the sheath than known techniques (which used longer cotton fibers).

[0018] According to one aspect of the invention, the sheath may be 100% cotton. Other embodiments are possible in which 10% to 90% of the sheath fibers are cotton yarns. The remainder of the sheath may contain other commercially available fibers. The cotton yarn can be regular cotton yarn, pre-consumer cotton yarn, or post-consumer cotton yarn, which can conserve water and increase the sustainability of yarn production.

[0019] Other fibres than cotton can also be used for the sheath. By way of example, artificial fibres (preferably cellulosic), such as rayon and its variants (modal, lyocell, cupro, viscose) can be used. Natural fibres such as linen, hemp, ramie, kapok can also be used. According to a possible solution, animal fibres such as wool, silk, cashmere can also be used.

[0020] Surprisingly, it has been found that twisting or spinning the above core fibers with an amount of short fibers results in a yarn having a core in which the twisted core fibers encapsulate the fibers used in the sheath, i.e., retain part of the core fibers. In particular, the smaller long fibers in the core better retain the fibers in the sheath.

[0021] In particular, according to a preferred embodiment, the fluff index of the composite yarn 1 according to the ASTM 5647 standard is preferably 1-20, and more preferably 5-20.

[0022] Garments made with hairy yarns have been found to be soft and comfortable. The preferred method for obtaining hairy composite yarns is to use a ring or silo spinning process (i.e. ring spinning with two roving sources for the sheath). Ring (and silo) spinning has also been found to provide softer yarns, e.g. in air-jet or open-end spinning.

[0023] According to a possible embodiment, the composite yarn has a tensile strength of 10 to 25 cN / tex, more preferably less than 23 cN / tex, even more preferably less than 20 cN / tex. The tensile strength is measured according to ENISO 2062.

[0024] The elongation at break of the composite yarn, measured according to ENISO2062, is preferably from 3% to 50%, more preferably from 15% to 35%.

[0025] The count of the composite yarn is preferably from Ne 3 / 1 to Ne 100 / 1, more preferably from Ne 5 / 1 to Ne 80 / 1.

[0026] The present invention also provides the following advantages in the manufacturing process:

[0027] Ball warping step: Considering the production of 1 million meters of yarn, the rope breakage rate of the produced fabric can be reduced by 10-20%, the amount of attached pile can be reduced by 5-10%, and the broken ends sent to rope dyeing can be reduced by 5%.

[0028] Rope dyeing step: The amount of water used to dye the fabric can be reduced by 30-45%. Less water is used, so the amount of chemicals and dyes used is reduced by 5-35%. Yarn drying is easier, so the amount of steam used can be reduced by 30-50%.

[0029] REBEAM: This yarn has a higher breaking strength compared to known yarns of the same count and made from the same material with a higher percentage of cotton. Therefore, 10 6 The break rate can increase by 10 to 35%. As a result of the higher yarn strength, 6 The break rate (i.e. the break rate considered in the production of 1 million meters of yarn) can be reduced by 5-25%. Yarn-to-yarn friction is also reduced, resulting in a 15-30% reduction in cotton-based breakage in the lead area. The problem of lost ends is also reduced due to reduced yarn breakage.

[0030] Sizing: Due to the properties of the yarn of the present invention, yarn breaks that may occur in the sizing area can be reduced by 5-25%. By reducing the number of yarn breaks, the number of missing ends in the woven section can be reduced by 10-20%. The amount of chemicals used in the sizing step can also be reduced by 8-35%. The steam consumption used to dry the yarn can be reduced by 30-50%. Due to the reduction in flying fibers, the fault score can be reduced by 5-8%.

[0031] According to one aspect of the invention, the core fiber comprises at least one, and preferably a plurality of, long fibers (ie, continuous fibers). In preferred embodiments of the invention, all core fibers are long fibers, however, in some embodiments the core may also comprise (or consist of) a bundle of short fibers, typically obtained by cutting and bonding long fibers.

[0032] The continuous core fiber may be a single filament, a single bundle of filaments, or filaments that are already combined to form one or more yarns. In particular, the plurality of filaments can be provided in the core as DTY yarns. As is known, DTY stands for Draw Textured Yarn. Known DTY yarns are available in the market. As a result, according to one embodiment, one or more DTY yarns are used to provide the core of the composite yarn of the present invention.

[0033] According to a possible manufacturing process of DTY yarns, the POY (partially oriented yarn) is fed to two different subsequent shafts rotating at different speeds, so that the POY is drawn, in particular the speed of the second shaft always being faster by a factor of the draw ratio required for the particular yarn and process. A friction device, such as a series of rotating friction plates, positioned between the two shafts imparts (pre-)twist to the yarn, so that the yarn is simultaneously twisted and drawn. Between the two shafts is a yarn heater, which heats the yarn to a heat-setting temperature. Immediately following the heater is usually a cooling plate, which must cool the yarn to a substantially lower temperature in order to permanently heat-set the twist. As the yarn exits the second shaft, each single filament in the DTY yarn attempts to conform to the shape of a three-dimensional helix, resulting in a voluminous, bulky stretch yarn.

[0034] In other words, according to the preferred manufacturing process for DTY yarn, a THUT (twist-heat-untwist set-up) operation is performed sequentially: the yarn is taken from a supply package, passed through a heating unit under controlled tension, passed over a false twist spindle or friction surface, which is a stack of rotating disks usually called an aggregate, passed over a series of take-up rolls, and then fed into a take-up package. This twist is set in the yarn by the action of the heater tube and then removed after the spindle or aggregate, resulting in a group of filaments capable of forming a helical spring, although other processes known in the art for obtaining DTY yarns are also possible.

[0035] Similarly, the chopped filaments may be part of a single bundle, or they may be part of two or more bundles.

[0036] Preferably, the core fiber is false twisted, which can be done on each filament individually or, more generally, if the filament is part of a bundle of filaments, the filaments can be false twisted. As an example, a yarn can be formed using continuous fibers (i.e., filaments) or staple fibers (e.g., obtained by cutting filaments) and such yarn can be false-twisted. In other words, a yarn can be formed using a plurality of filaments that are not false-twisted and such yarn can be subsequently false-twisted. The core fiber of this yarn is included in the definition of "false-twist textured fiber". Similarly, multiple (false-twist textured or not) filaments can be chopped into short fibers (staple fibers) and these short fibers can be used to make yarns that are then false-twist textured. The fibers of this yarn are included in the definition of "multiple false-twist textured fibers".

[0037] The core fiber preferably comprises a non-elastomeric fiber. Elastomeric long fibers can also be added to the core and combined with the non-elastomeric core fibers, i.e. according to a possible embodiment the core may comprise a non-elastomeric core fiber and further elastomeric long fibers.

[0038] The non-elastomeric yarns of the core may have elastic properties, i.e. the core of the composite yarn may contain different filaments with elastic properties, which may be non-elastomeric filaments that are part of the core fiber (i.e. continuous core fiber), as well as the elastomeric filaments.

[0039] The term "filaments having elastic properties" refers to elastomeric filaments, such as elastane filaments, and elastic non-elastomeric filaments (e.g. T400 filaments). Suitable elastomeric filaments have an elongation at break of 200% or more, preferably 400% or more, typically between 200% and 600%. The amount of the elastomeric filament is preferably in the range of 1% to 20% of the total weight of the yarn, more preferably 1.5% to 10%. Several filaments having elastic properties can be combined together. Preferred elastomeric filaments are elastane, polyurethane urea-based fibers, Lastol, and Dow XLA (registered trademark). The elastic filaments may be non-elastomeric filaments, preferably with an elongation at break of 15-50%. Preferred fibers for the elastic non-elastomeric filaments are T400 (copolymer of polyester, elastic multiester), PBT fibers and other bonded yarns such as PBT-PTT, PET-PTT, PET-PTMT. The total amount of elastic filaments is 1-60%, preferably 10-45% of the weight of the composite yarn.

[0040] Preferred synthetic fibers for the core fiber are PP, PET, PA6, and PA6,6.

[0041] The elongation at break of the abovementioned non-elastomeric filaments can be determined according to DIN ISO 2062, while the elastomeric filaments can be tested according to BISFA, Test Method for Exposed Elastane Yarns, Chapter 6. The recovery of the non-elastomeric filaments is at least 80%, preferably 93% of the fibers, and most preferably at least 96% or 97% or more, as measured according to DIN 53835 part 3 at a tensile strength of 0.2 cN / tex (centinewton tex) and an elongation of 3%.

[0042] Elastomeric filaments suitable for use in the present invention are commercially available under the trademark "Lycra" and are typically provided in the form of a bundle of filaments that are extruded together. In a preferred embodiment, the elastomeric filaments are provided as a bundle of separate filaments. Details of this type of elastomeric filament are disclosed in co-pending European patent application EP19169983.4 filed in the name of the present applicant. Simply put, in one embodiment, a composite yarn contains at least two "single elastic filaments". This definition of "single elastic filaments" means that they are not part of the same elastic bundle of continuously connected filaments. In fact, it is known that for elastic fiber elements, a certain amount of filaments can be bundled together to produce a desired thickness. This is because it is known that, for example, a spandex yarn is a bundle of filaments, and this spandex yarn can be composed of several smaller individual filaments that adhere to each other due to the natural tackiness of their surfaces. On the other hand, a "single elastic filament" means one monofilament yarn. According to a possible embodiment of the present invention, multiple "single elastic filaments" are first packed into a bundle and then loosely bonded to each other and separated (and become "single filaments") in a subsequent process step to produce a yarn.

[0043] The total count of the core is preferably from 5 denier to 1000 denier, more preferably from 50 denier to 300 denier.

[0044] The elongation at break of the core is preferably from 5% to 160%, and more preferably from 10% to 50%.

[0045] According to one aspect of the invention, the continuous core fiber and the elastomeric filaments are combined together at least at a number of connection points in a known manner, preferably by blending, twisting, or co-extrusion. The elastomeric filaments are preferably stretched or elongated before being combined with the core fiber, the stretch ratio being between 1.5 and 5.5, more preferably between 2.5 and 5.5.

[0046] According to one aspect of the invention, the continuous core fiber and the elastomeric filaments are connected together in a continuous or substantially continuous manner, preferably under tension, by "co-extrusion" of the filaments. During "coextrusion", also known as co-feeding, a bundle of fibers (under tension) is force-fed (co-fed) through a restrictor that causes the fibers to adhere together to the extent that they remain attached after passing through the restrictor. The coextruded filaments are preferably spun together with the sheath filaments immediately after the coextrusion step.

[0047] According to one embodiment of the invention, the core comprises at least 1, more preferably at least 12, more preferably at least 15 continuous core fibers, i.e., core filaments.

[0048] In an embodiment of the invention, the amount of core fiber (excluding elastomeric fiber) is at least 35% by weight of the total weight of the yarn, ie, the complete yarn including the sheath, and may be as much as 90% by weight of the complete yarn. Preferably, the amount of core fibre is at least 37% or 38% by weight of the final yarn. Preferably, the amount of core fibre is 35-73% by weight of the final yarn, more preferably the core is in the range of 37-53% by weight of the final yarn or 38-49% by weight of the final yarn.

[0049] According to one aspect of the invention, the core fiber is made from one or more materials selected from polypropylene, polyester polymers and copolymers, polyamide polymers and copolymers, and mixtures thereof.

[0050] According to one embodiment of the present invention, the twist multiple of the composite yarn is in the range of 1.2 to 3.5, preferably 1.6 to 3.3, and more preferably 2.2 to 2.9.

[0051] In particular, the twisting of the composite yarns helps to combine the long fibers of the sheath with the core, which helps to reduce the amount of sheath fiber needed to cover the core and prevents the above-mentioned "grinning" of the long fibers of the core. Also, the short fibers can be used to obtain a composite yarn that provides a "fluffy" feel to the user who comes into contact with the composite yarn, especially to the wearer of a garment that includes the above-mentioned yarn.

[0052] This twist factor can be obtained from the following formula:

[0053] Twists / inch = twist factor x √ English cotton count

[0054] Here, the twist value per inch (25.4 mm) can be calculated using the following formula:

[0055] Twist / inch = spindle revolutions per minute / yarn feed speed

[0056] An aspect of the invention also relates to a fabric comprising a composite yarn according to one or more of the above aspects.

[0057] One aspect of the invention relates to articles comprising such fabrics, which articles are preferably garments.

[0058] An aspect of the present invention also relates to a method of manufacturing the composite yarn of one or more of the above aspects of the present invention, comprising the steps of providing a core comprising a plurality of core fibers made of a polymeric material, providing a sheath of inelastic staple fibers to cover the core, and co-spinning the core filaments and the sheath staple fibers, the total amount of core fibers being at least 35% by weight of the total weight of the composite yarn.

[0059] The terms "spinning" and "twisting" refer to the known process of combining a core with staple fibers in a sheath. This process involves placing a core fiber on or adjacent to a sliver or bundle of sheath fibers and twisting the core and fibers together. As previously explained, preferred spinning methods include ring spinning (also silo spinning).

[0060] According to one embodiment of the invention, the elastomeric long fibers are stretched to a stretch ratio of 1.5 to 5.5. [Brief description of the drawings]

[0061] [Figure 1] 1 is a schematic diagram of a first embodiment of a composite yarn of the present invention. [Diagram 2] FIG. 2 is a schematic diagram of another embodiment of a composite yarn of the present invention. [Diagram 3] FIG. 1 is a schematic diagram of a "co-extrusion" method. [Figure 4] FIG. 2 is a schematic diagram of an article obtained with a woven fabric comprising a composite yarn according to the present invention. [Figure 4A] FIG. 5 is a schematic enlarged detail of FIG. 4. [Diagram 5] FIG. 1 illustrates one possible embodiment of an apparatus for producing an exemplary composite yarn according to the present invention. [Figure 6] FIG. 2 illustrates another embodiment of an apparatus for producing an exemplary composite yarn according to the present invention. [Figure 7] FIG. 13 illustrates yet another embodiment of an apparatus for producing an exemplary composite yarn according to the present invention. [Figure 8] FIG. 13 illustrates yet another embodiment of an apparatus for producing an exemplary composite yarn according to the present invention. [Figure 9] FIG. 13 illustrates yet another embodiment of an apparatus for producing an exemplary composite yarn according to the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0062] The invention will now be described in more detail with reference to the non-limiting drawings. A composite yarn 1 according to one embodiment of the invention has a core 2 and a sheath 3, which typically contains staple fibers 3a. The core 2 contains at least one, and preferably several, core fibers 21.

[0063] This core fibre 21 is preferably a continuous fibre, i.e. a long fibre (as shown diagrammatically in Figure 1). In other embodiments of the invention, the core fibre 21 may also comprise (or only comprise) a bundle of short fibres, e.g. obtained by cutting a long fibre. According to one embodiment of the present invention, the core fiber 21 may include a bundle of both long and short fibers.

[0064] The linear density of the core fiber 21 is preferably 14 denier or less, more preferably 10 denier or less, and even more preferably 0.2 to 8 denier.

[0065] Preferred materials for the core fiber 21 are polyester polymers and copolymers. Other suitable polymers are polyamides. Representative materials for the core fiber 21 are polyester polymers and copolymers, i.e. PET (polyethylene terephthalate), PBT (polybutylene terephthalate), PTT (polytrimethylene terephthalate), PTMT (polytetramethylene terephthalate), or polyester copolymers PTT / PET, PTT / PBT, PTMT / PET. Representative polyamides (i.e. nylons) are PA6 (polyamide), PA6,6 or copolymers of nylon. Materials also include acrylic polymers and polyacrylonitrile. The more preferred synthetic fibers for the core fiber are PP, PET, PA6, and PA6,6. However, it is not excluded to use other synthetic materials for the core fiber that are not explicitly mentioned in the above list. The core fibers are usually non-elastomeric, i.e., they do not contain elastomeric yarns.

[0066] Suitable staple fibers 3a used to provide the sheath 3 for the composite yarn 1 are known in the art, and include, for example, cotton, rayon and its commercial variations (modal, lyocell, cupro, viscose), linen, hemp, ramie, kapok, wool, silk, cashmere, etc.

[0067] The amount of core fibres 21 is at least 35% by weight of the total weight of the composite yarn 1 .

[0068] In an embodiment of the invention, the amount of core fibres 21 is at least 35% by weight of the total weight of the composite yarn 1. In an embodiment of the invention, the amount of core fibres 21 may be as much as 90% by weight of the total weight of the composite yarn 1. Preferably, the amount of core fibres 21 is at least 37% or 38% by weight of the final composite yarn. Preferably, the amount of core fibres is between 35% and 73% by weight of the final yarn, more preferably the core is in the range of 37% to 53% or 38% to 49% by weight of the yarn weight.

[0069] In the embodiment shown diagrammatically in FIG. 1, at least a portion of the core fibers may be provided as a bundle of fibers or as a core yarn 20, for example an FDY yarn. Other embodiments are possible, for example, where the core 2 comprises two or more bundles of fibers and / or yarns 20. Additionally, the core fiber 21 may be a common bundle of continuous core fibers that are not part of an FDY yarn. Preferably, according to one embodiment, the core 2 comprises continuous fibers, i.e. core filaments, in particular at least one continuous core fiber, and comprises at least 1, more preferably at least 12, more preferably at least 15 continuous core fibers 21. The number of continuous filaments is preferably less than 1160.

[0070] The total count of the core is preferably 5 to 1000 denier, and more preferably 50 to 300 denier. The elongation at break of each core fiber 21 is preferably 15-50%, and the elongation at break of the core yarn is preferably 5%-160%, more preferably 10%-50%.

[0071] According to a possible embodiment of the invention, the core 2 (and therefore the composite yarn 1) does not contain elastomeric fibers (see, for example, ASTM D4849 for the definition of elastomeric yarns). In other words, the core 2 (and therefore the composite yarn 1) consists essentially of non-elastomeric fibers. Some of these fibers may be elastic.

[0072] According to different possible embodiments, the core 2 comprises at least one elastomeric filament 22. According to a possible embodiment, the core 2 of the composite yarn 1 comprises at least two single elastic filaments 22, i.e. at least two different monofilament yarns.

[0073] In Figure 2, the elastomeric filaments 22 are shown as dotted lines. This is a representation to help the reader identify the elastomeric filaments 22. The size and arrangement of the actual elastomeric filaments 22 are not as shown in the figure.

[0074] As mentioned above, the core fibers 21 may comprise non-elastomeric continuous fibers (i.e., non-elastomeric filaments). The core may further comprise elastomeric filaments 22. That is, the core may comprise different filaments having elastic properties. As stated above, the above percentages of core fiber 21 (e.g., "at least 35%", "at least 37% or 38%", "in the range of 35% to 73%") refer to the non-elastomeric fibers present in core 2. In other words, the non-elastomeric fibers of core 2 (i.e., core fiber 21) are at least 35% of the total weight of the composite yarn. Preferred ranges are as previously stated (e.g., "at least 37% or 38%", "in the range of 35% to 73%").

[0075] The total number of the long fibers having elastic properties is preferably 5 to 500 denier, and more preferably 20 to 240 denier.

[0076] In an embodiment of the present invention, the continuous core fiber 21 and the elastomer filament 22 are connected to each other at multiple points. In a possible embodiment, the continuous core fiber 21 and the elastomer filament 22 are connected by intermixing, twisting, or co-extrusion, techniques known in the art.

[0077] 3 is a schematic diagram showing a method of "co-extrusion" or "co-feeding" of a bundle of fibers or core yarns 20 (e.g. FDY yarns) and elastomeric filaments 22. For ease of explanation, reference is made to DTY yarns, but the following description also applies generally to bundles of false twist textured filaments. The DTY yarns 20 and the elastomeric filaments 22 are fed (preferably under tension) through a restricting means 51 and are attached and connected to each other to the extent that they remain attached together after leaving the restricting means. More specifically, Figure 3 shows a roll 50 having a "V" shaped limiting means 51. The bundle of fibres or core yarns 20 and the elastomeric filaments 22 are fed into the roll 50 and forced into the bottom of the "V" shaped limiting means 51 where they are connected to each other, i.e. the bundle of fibres or core yarns 20 and the elastomeric filaments 22 are connected at least at a number of points, so that they exit the roll 50 as a substantially completed core 2 covered by a sheath 3.

[0078] According to the exemplary embodiment, the composite yarn 1 (i.e., the core 2 covered by the sheath 3) allows the twist level of the composite yarn 1 to be kept low as compared to the prior art. More specifically, the composite yarn is preferably twisted with a twist factor of 1.2 to 5.5, preferably 1.2 to 3.5. More preferably, the twist factor is between 1.6 and 3.3, and even more preferably between 2.2 and 2.9. This low level of twist results in a very soft fabric with excellent light reflection and bright colors. As previously explained, this twist factor can be obtained from the following formula:

[0079] Twists / inch = twist factor x √ English cotton count

[0080] Here, the twist value per inch (25.4 mm) can be calculated using the following formula:

[0081] Twist / inch = spindle revolutions per minute / yarn feed speed

[0082] For further details regarding low twist yarns and methods for their manufacture, reference may be made to European Patent Application EP 3064623 (A2) in the name of the present applicant, the teachings of which are incorporated herein by reference.

[0083] As shown in the comparative examples below, by using low twist it is possible to provide a coarser yarn, i.e. a larger dimension yarn, relative to the prior art. For comparison, three yarns were prepared: Yarn A was a yarn according to the invention, while Yarns B and C were 100% ring-spun cotton yarns according to the prior art. The data for each yarn are shown in the table.

[0084] [Table 1]

[0085] As can be seen from the table, Yarn A according to the invention has a larger diameter than Yarn B, which is a conventional 100% cotton yarn of the same count as Yarn A (i.e., 14 / 1 NE). The diameter of Yarn A is close to the diameter of Yarn C, which is a conventional 100% cotton yarn that is heavier than Yarn A (14 / 1 NE vs. 8 / 1 NE).

[0086] The diameter of each yarn was measured by USTER TESTER 4.

[0087] As previously discussed, the composite yarn 1 is typically soft. A factor that may help impart a soft feel may be the fuzziness of the yarn.

[0088] Possible methods for measuring hairiness are disclosed in the ASTM 5647 standard. The hairiness index according to the ASTM 5647 standard of the composite yarn is preferably between 1 and 20, more preferably between 5 and 20. As is well known, the hairiness index H corresponds to the total length of the protruding fibers within a measuring field of 1 cm length of the yarn.

[0089] In a possible embodiment of the present invention, the composite yarn has a tensile strength of 5 to 160 cN / tex, preferably 10 to 25 cN / tex, more preferably less than 23 cN / tex, even more preferably less than 20 cN / tex, the tensile strength being measured according to the EN ISO2062 standard.

[0090] The elongation at break of the composite yarn, as measured by EN ISO 2062, is between 3% and 50%, more preferably between 15% and 35%.

[0091] The count of the composite yarn is preferably from Ne 3 / 1 to Ne 100 / 1, more preferably from Ne 5 / 1 to Ne 80 / 1.

[0092] The yarns of the present invention may also have a combination of the above features.

[0093] Typically, during the manufacture of the composite yarn 1, a core is provided which comprises at least one, and preferably a plurality of, core fibres 21. As previously mentioned, the core may also comprise elastomeric filaments 22.

[0094] The core fiber 21 and the elastomeric filament 22 are preferably bonded to one another at multiple points.

[0095] The continuous core fiber 21 and the elastomeric filaments 22 may be connected together, for example, by intermixing, twisting, or "co-extrusion" (as shown diagrammatically in FIG. 4).

[0096] The formed core is covered by a sheath 3 by known methods, preferably by means of a ring or silo spinning machine.

[0097] In particular, the sheath 3 is provided in such a way that, at the final stage of manufacture, the weight of the core fibres 21 represents at least 35% of the weight of the composite yarn 1 .

[0098] At the final stage of manufacture, the composite yarn 1 can be used to provide the fabric 100. The fabric 100 can be woven or knitted. The fabric 100 can be manufactured by using only the composite yarn 1 according to the invention or by combining it with different yarns.

[0099] Such a fabric 100 can be used to manufacture an article 101, preferably a garment. As an example, in Figure 4, the composite yarn 1 is used to manufacture a denim fabric 100, which is in turn used to manufacture a pair of trousers.

[0100] Different processes can be performed on the final fabric 100. In one embodiment, the fabric 100 can be embossed into a three-dimensional design.

[0101] The fabric can be subjected to a chemical treatment to dissolve (some of) the cellulose fibers, resulting in a design or pattern on the fabric 100. This technique is known in the art as "burnout" or "devore".

[0102] Special effects on the final fabric 100 can be achieved by using different colors between the core and sheath fibers.

[0103] In a preferred embodiment, the composite yarn 1 is obtained by ring spinning. In particular, a preferred embodiment is one in which the composite yarn 1 is obtained with a core 2 bonded to a single roving (usually a cotton roving). This allows for better centering of the core 2 (i.e. reduced grinning) and therefore a softer and more attractive yarn (in terms of appearance). However, it is also possible to use two or more different rovings, as will be explained in more detail later.

[0104] 5 and 6 show one embodiment of a ring spinning apparatus for producing an exemplary composite yarn 1 according to the present invention.

[0105] The core 2 is taken from the bobbin 6 and guided between two pretension bars 10 which are used to apply a low pretension to the core yarn 2 in order to align it straight. This is very useful when the core 2 is obtained by mixing two different long fibres. The core 2 is fed from a pre-tension bar 10 to two tension rollers 11 on which weights 12 are placed. The core 2 is guided between a drive roller and weights 12 to avoid free movement of the core yarn relative to the tension rollers 11. It should be noted that instead of the combination of tension rollers 11 and weights 12, other suitable means for imparting a controlled speed to the core yarn 2 can also be used, such as, for example, stretching rollers, as known in the art.

[0106] The advantage of the above disclosed arrangement is mainly that the same equipment can be used to prepare standard elastane core yarns, where the elastane fibres are loaded into a package placed on the tension roller 11 instead of the weight 12.

[0107] From the first stretching device (11, 12) the core 2 (preferably a flat yarn, e.g. a bundle or yarn of filaments 20) is led to a rolling guide 13 and from there to a stretching roller 14, which is the foremost couple of stretching rollers for the cotton roving 8. This stretching roller 14 is known per se in the art.

[0108] The cotton roving 8 is guided from the spool 7 through a pre-tension bar (roller) 10, a tension roller 11, and then into a first guide 15 and a second guide 16. As shown in FIG. 6, the guide 15 is offset towards the front of the apparatus relative to the second guide 16 in order to create tension in the roving, keeping it in a fixed position and preventing it from moving freely.

[0109] From the guide 16, the cotton roving 8 is fed to a stretching roller 14. This stretching roller 14 is common to the core 2 and the cotton roving 8.

[0110] According to the invention, the core 2 is tensioned before being combined with the cotton roving, this tension or elongation being obtained by the speed difference between the tension roller 11 and the stretching roller 14, i.e. the speed difference between the tension roller 11 and the last stretching roller 14. The last roller 14 provides a stretch ratio to the composite core 2.

[0111] The stretch ratio is calculated as the ratio of the speed of roller 14 to the speed of tension roller 11, where these speeds are the angular velocities over the surface of each roller.

[0112] It should be noted that the pretension bar 10 also contributes to obtaining the required draw ratio. The additional pretension bar 10 provides alignment and slight tension of the core 2. It is therefore useful to further increase the draw ratio, as it aids the further stretching step. This has the effect that the core 2 is kept in the center of the final yarn 1 with very high precision.

[0113] The use of staggered positions of the first guide 15 and second guide 16 also allows the cotton roving to always be fed to the same position, preventing the cotton roving from shifting during long periods of production. The combination of better control to maintain the position of the cotton roving 8 and high tension on the core 2 allows the core 2 to always be kept in the center of the yarn 1 and the core to be completely covered with the staple fibers 3.

[0114] The two portions of the final yarn 1 exiting the spreading roller 14 are fed through a guide 17 to a spinning device 18 where they are spun together. This spinning device 18 is known per se in the art and in one embodiment includes a ring, a traveler and a spindle.

[0115] The composite yarn produced can be used, particularly as a weft yarn, in the production of stretch denim fabrics and garments. Machines and methods for producing denim are well known in the art, and by way of example, Morrison textile machines or Sulzer machines or modifications thereof can be used to produce denim fabrics with good elasticity and good stretch recovery.

[0116] 7 and 8 show examples of other possible devices 200 and manufacturing methods for the production of the composite yarn 1 according to the invention. In these embodiments, the sheath 3 is made from two different rovings, which are processed separately for part of their path and then combined to form the sheath. A similar method is known in the art as "silo spinning". Further embodiments with more rovings are possible.

[0117] The core 2 comprises polyester filaments 21 and elastane as elastomeric filaments 22. The polyester 21 is fed from a bobbin 201 and passes through a tube 202 where a first stretch is applied. Further stretch can be applied by rollers 203 at the exit of the tube 202.

[0118] Elastane 22 is provided from a bobbin 204 and directed to roller 205 where it is combined with polyester 21 to form core 2. By way of example, roller 205 may be of the type shown in FIG.

[0119] The sheath 3 is provided by two cotton rovings 8a, 8b supplied from spools 206a, 206b. The cotton rovings 8a, 8b are stretched separately, for example by one or more stretching rollers 207 (as best shown in FIG. 8).

[0120] The core yarn 2 is led to a stretching roller 208, where the cotton rovings 8a, 8b are also fed.

[0121] The core yarn 2 and the cotton rovings 8a, 8b are then spun by a spinning device 210.

[0122] Preferably, before the spinning device 210, the bundle of core yarn 2 and cotton rovings 8a, 8b further passes through a stretching and compression device 209, shown in a preferred embodiment in an enlarged view in FIG. In this embodiment, the stretching and compressing device 209 comprises two compression rollers 209a between which the core yarn 2, the bundle of cotton roughs 8a, 8b (not shown for greater clarity in the enlarged detail of FIG. 7) are pressed. Each compression roller 209 drives an endless belt 209b. The belts 209b face each other to define a passage 209c for the bundle of yarns 2, 8a, 8b between the belts 209b. This type of stretching and compression device is known in the art as a "double apron stretching system."

[0123] Generally, the bundle of yarns 2, 8a, 8b is guided and pressed by a stretching and compression device 209 (e.g., in a path 209c by belt 209b in the illustrated embodiment) to provide uniform pressing and stretching to all components of the bundle of yarns 2, 8a, 8b, i.e., the polyester 21 and elastane 22 of the core yarn 2, and the rovings 8a, 8b forming the sheath 3.

[0124] As before, the core 2 is stretched and guided so that it is centrally aligned with the sheath 3 of the final yarn 1 .

[0125] In other embodiments, the stretching and compressing device 209 may be omitted.

[0126] Furthermore, in a possible embodiment, in order to carry out a single roving ring spinning of the composite yarn 1, one of the two cotton rovings 8a, 8b is omitted (or in any case not used).

[0127] As an example, Figure 9 shows an embodiment of a ring spinning apparatus with a single source 7 of spool for cotton roving 8 and no compression device 209. Other elements are similar to those in Figures 7 and 8 and are indicated with the same reference numerals.

[0128] The present invention will now be described in further detail with reference to the following examples. EXAMPLES

[0129] Fabric X was prepared using yarns according to the invention, and comparative yarn Xcomp was prepared using yarns according to the prior art. The composition of the weft yarns of the samples is given in Table 1 under the column "Yarn composition". The warp yarn composition is the same as the weft yarn composition, except that elastane is absent and the amount of cotton is increased by the amount of said elastane. The PES (polyester filament) core of Fabric X yarn is a 150 denier bundle of core fibers formed of 36 filaments, each filament being a 4.5 denier filament.

[0130] Fabric testing was carried out to evaluate the tear and tensile strength of this fabric. The tensile strength was tested with ASTM D5034 and standard ASTM D1424 was used to evaluate the tear strength of the fabric.

[0131] The test results are summarized in Table 1 below. As can be seen from the values ​​in Table 1, the performance of the woven fabric according to the present invention is improved by more than 20%.

[0132] [Table 2] [Explanation of symbols]

[0133] 1. Composite Yarn 2 Core Yarn 3 Sheath 3a Short Fiber 6 Bobbin 7 Spool 8. Coarse Yarn 8a Cotton roving 8b Cotton roving 10 Pretension bar 11 Tension roller 12 Weight 13 Rolling Guide 14 Stretching Roller 15 First Guide 16 Second Guide 17 Guide 18 Spinning equipment 20 Core Yarn 21 Polyester filament (polymer core fiber) 22 Elastane (long elastomer fiber) 50 rolls 51 "V" Shaped Restrictive Measures 100 Cloth (Denim fabric) 101 Goods 200 equipment 201 Bobbin 202 tube 203 Roller 204 Bobbin 205 Roller 206a spool 206b Spool 207 Stretching Roller 208 Stretching Roller 209 Stretching and Compression Devices 209a Compression Roller 209b Endless Belt 209c aisle 210 Spinning equipment

Claims

1. A composite yarn (1) having a core (2) and a sheath (3), the core comprising a plurality of core fibres (21) made of a polymeric material and the sheath (3) comprising staple fibres (3a), the core fiber comprises a non-elastomeric fiber; the amount of said core fiber (21) is in the range of 35% to 90% by weight of the total weight of said yarn (1); The core fiber (21) is a false twisted fiber, The core further comprises an elastomeric filament (22); At least a portion of the core fiber (21) is a DTY yarn; the core fiber (21) and the elastomeric filament are connected to each other, bonded together, or attached to each other at least at a plurality of connection points; The core (2) and the sheath (3) are spun together around the core, and the core (2) is completely covered with the sheath, The composite yarn is characterized in that it has a tensile strength of 10 to 25 cN / tex, as measured according to the ENISO 2062 standard.

2. In claim 1, A composite yarn, wherein at least a portion of said core fibers (21) have a linear density of 14 denier or less.

3. In any one of claims 1 or 2, A composite yarn, characterized in that the core fiber (21) comprises a plurality of long fibers.

4. In claim 3, The composite yarn is characterized in that it contains 2 to 1160 of the long fibers.

5. In claim 4, A composite yarn, characterized in that the amount of said long fibers having elastic properties ranges from 1% to 60% of the total weight of said yarn.

6. In any one of claims 1 to 5, A composite yarn, characterized in that at least a portion of said core fibers (21) are provided as a bundle of said core fibers or as a core yarn (20).

7. In any one of claims 1 to 6, A composite yarn, characterized in that the core fiber (21) is made of a material selected from polyester polymers and copolymers, polyamide polymers and copolymers, and mixtures thereof.

8. In any one of claims 1 to 7, The twist factor of the yarn (1) is in the range of 1.2 to 5.5; The twist factor is obtained from the following formula: Twist / inch = twist factor x √ English cotton number The twist / inch value is calculated according to the following formula: Twist / inch = spindle revolutions per minute / yarn feed speed A composite yarn comprising:

9. A fabric (100) or article (101) comprising a composite yarn (1) according to any one of claims 1 to 8.

10. A method for producing the yarn (1) according to any one of claims 1 to 8, comprising the steps of: Providing cores (2) of a plurality of core fibers (21) made of a polymer material; providing a sheath (3) of inelastic staple fibers to cover said core (2); a spinning step of co-spinning the long fibers and the short fibers of the sheath (3) to completely cover the core (2) with the sheath (3) containing the short fibers; The core fiber provided comprises a non-elastomeric fiber, the core further comprising an elastomeric filament (22); the total amount of said core fibers (21) is in the range of at least 35% to 90% by weight of the total weight of said yarn (1), said core fibers (21) are false twist textured fibers, and at least a part of said core fibers (21) is a DTY yarn; the DTY yarn and the elastomeric filament (22) are forced together by feeding them through a restricting means (51), the DTY yarn and the elastomeric filament being joined, bonded together and attached to each other at multiple points; The core (2) and the sheath (3) are spun together around the core, and the core (2) is completely covered with the sheath, The method for producing a yarn, wherein the composite yarn has a tensile strength of 10 to 25 cN / tex as measured according to the ENISO 2062 standard.

11. A method for producing a composite yarn (1) according to claim 10, comprising the steps of: A method for producing a composite yarn, wherein at least a portion of said core fibers (21) have a linear density of 14 denier or less.

12. A method for producing a composite yarn (1) according to claim 10 or 11, comprising the steps of: A method for producing a composite yarn, characterized in that the core fiber (21) contains a plurality of continuous long fibers.

13. A method for producing a composite yarn (1) according to claim 12, comprising the steps of: A method for making a composite yarn, characterized in that said core fiber (21) and said elastomeric filament (22) are combined together by co-extrusion prior to said spinning step.

14. In any one of claims 10 to 13, In the spinning step, the yarn has a twist factor in the range of 1.2 to 5.5; The twist factor is obtained from the following formula: Twist / inch = twist factor x √ English cotton number The method of making a yarn, wherein the twist / inch value is calculated according to the following formula: Twist / inch = spindle revolutions per minute / yarn feed speed

15. In any one of claims 10 to 14, The core (2) and the sheath (3) are joined together by a ring spinning machine; A method for producing yarn, characterized in that the ring spinning machine is provided with one or more sources of roving for the sheath (3).

16. In claim 15, The ring spinning machine includes a first guide for applying tension to the roving and a second guide offset relative to the first guide, the offset being used to keep the core always at the center of the yarn.

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