A method for making improved elasticized fabrics and elasticized fabrics made thereby

Abstract

In order to manufacture an elastic fabric, a method comprises steps of: making a wound yarn (50), wherein a core yarn (30) and a winding yarn (40), preferably and independently from each other selected among: artificial fibres, e.g. Rayon; natural fibres such as linen, hemp, ramié, bamboo, jute, cotton, wool, silk; but also synthetic as nylon, polyester, acrylic etc.; tensioning the core yarn (30) by a predetermined pulling force; conveying the core yarn (30) and the winding yarn (40), in such a way that the latter laterally attains the former in a wrapping space (35), selecting the conveying speed; winding the winding yarn (40) about the core yarn (30) in a wrapping space (35) in such a way that, while being wound, in said wound yarn (50), said core yarn (30) and said winding yarn (40) are twisted with a respective twist directions opposite to each other, and said winding yarn (40) forms a number of turns T higher than a predetermined minimum number of turns T0, and lower than a predetermined maximum number of turns T1 of said winding wire (40) per length unit of said wound yarn (50), said minimum number of turns and maximum number of turns depending on said second linear mass density Nm,; making a fabric by a knitting process or a weaving process; washing the yarn (50) and / or the fabric.

Description

Field of the invention

[0001] The present invention relates to a method for making elasticised fabrics that can be disposed more easily than conventional elasticized fabrics, and to elasticized fabrics made by such method.

[0002] In particular, the invention relates to a method for making biodegradable fabrics consisting of biodegradable materials that can be disposed, for instance, by composting, and to elasticized fabrics made by such method.

[0003] The invention also relates to elasticized yarns to be used for making such fabricsReference to the prior art - Technical problems

[0004] Since some decades, elasticized fabrics made from elastic thread yarns of many kinds are used. The advantage of these fabrics is a high deformability of the items made therefrom. In particular, garments are made that do not hinder the movements of the limbs of the user, or conform themselves to these movements, thus generating a comfort sensation. This is particularly appreciated in underwear clothing or in sport and gym clothes, but is also appreciated in everyday life situations, such as sitting in a car, walking and whenever the joints must be bent. Moreover, elasticized fabrics are used to make bandages, dressings and garments for treating wounds, sprains, inguinal hernia and the like. Besides, elasticized fabrics are advantageous for making general-purpose gloves, as well as covers for sofas, armchairs and chairs, since rounded covers can be easily manufactured therefrom.

[0005] The features of currently-available elasticized fabrics depend on the high elasticity of the elasticized yarns used to make them. The elasticity of the elasticized yarns depends in turn on the use of a core elastomeric fibres in combination with covering yarns that are wrapped or form turns about the core elastomeric fibre and that can consist of various textile materials.

[0006] For instance, documents WO 2008 / 130563 A1 and WO 2012 / 062480 A2 describe ring-spun elastic composite yarns, in which an elastic core filament made of a synthetic elastomeric material is surrounded by a fibrous sheath consisting of a mass of synthetic or natural spun staple fibres, for instance cotton fibres. Other elasticized yarns, as those described in WO 2012 / 056436 and in WO 2019 / 159155, are obtained by winding machines, in which a substantially inextensible yarn is wound about the elastic core filament made of a synthetic elastomeric material to form a helix or a spiral about the elastic yarn. By applying a tensile force to elasticized yarn obtained this way, the turns of the helix formed about the core move away from one another and, by successively releasing the tensile force, the turns and the helix tend to return to the initial conformation. This behaviour allows an elastic recovery of the elasticized yarn and of the fabrics made thereof.

[0007] In the above prior art elasticized products, drawbacks arise from the use of a core elastic fibre made of a synthetic elastomeric material.

[0008] Firstly, these fabrics comprise an elastomeric portion and a fibrous portion of various materials. This heterogeneity makes it difficult to recycle the articles made of these fabrics when they are dismissed, since the two types of material should be separately recycled by specific techniques. Moreover, even if the fibrous sheath or the inextensible yarn wound about the core is made of a natural, tendentially biodegradable material, such as linen; hemp; ramie; bamboo; jute; cotton; wool; silk, the presence of the synthetic elastomeric portion, i.e. of a non-biodegradable portion, exclude composting as a possible disposal method for the items of clothing and similar textile products made of a related fabric, which would be one of the most preferred cheap and environment-friendly disposal methods known so far for such items. Briefly, the above-mentioned elasticised fabrics are scarcely environmentally sustainable and do not meet the requirements of a circular economy.

[0009] To cope with such a problem, WO 2020 / 084361 describes elasticized yarns having the same structure as in WO 2012 / 056436, in which elastomeric core is made of natural rubber, and the substantially inextensible yarn wound about the natural rubber core is based on cotton.

[0010] CN110528133A discloses a method for making an elastic loop composite yarn of a wrapped structure, according to which elastic yarns in a drafted state and non-elastic yarns are combined to form an elastic / non-elastic double-core yarn that is wrapped with an outer wrapping yarn to form the composite yarn of the wrapped structure and, finally, the drafting force for the elastic yarns in the composite yarn of the wrapped structure is removed, so that the elastic yarns in the composite yarn of the wrapped structure elastically retract to be in a non-drafted state, the non-elastic yarns are compressed and bent along the yarn axis direction due to the elastic retraction of the elastic yarns and protrude between spiral threads of the outer wrapping yarn to form a yarn loop, and the elastic loop composite yarn of the wrapped structure is prepared. The elastic loop composite yarn of the wrapped structure prepared by means of the method is wound and stored for use in the form of the composite yarn of the wrapped structure before the yarn loop is formed, and unwound to form the yarn loop during use. This way, the quality of the yarn loop is not influenced once the loop composite yarn is stored and conveyed for a long time, and the subsequent application of the loop composite yarn is facilitated.Summary of the invention

[0011] It is therefore an object of the present invention to provide a method for making an elasticized fabric having a homogeneous structure, i.e., a structure formed by materials that can be disposed by a same disposal process, thus simplifying the recyclability of items of clothing and similar products made by such an elasticized product.

[0012] It is a particular object of the invention to provide a method, different from prior art methods, for making a fully biodegradable elasticized fabric that can be disposed by composting items of clothing made thereof, once the latter have been dismissed.

[0013] It is also an object of the invention to provide a method for making an elasticized fabric that provides a pleasant and fresh touch feel to a user, as required, in particular, in the case of summer garments.

[0014] These and other objects are achieved by a method as defined by attached claims 1 and 15. Exemplary specific embodiments of the invention are defined by the respective dependent claims.

[0015] According to a first aspect of the invention, a method for making an elasticized fabric comprises the steps of: - forming a wound yarn, comprising the steps of: prearranging a core yarn having a first linear mass density Nm c : prearranging a winding yarn having a second linear mass density Nm w and twisted with an initial twist direction selected between "Z" and "S", wherein the core yarn is twisted with an initial twist direction equal to the initial twist direction of the winding yarn; applying a predetermined pulling force to the core yarn; conveying the core yarn and the winding yarn at respective conveying speeds towards a collecting bobbin of said wound yarn (51), wherein said step of conveying is carried out in such a way that the winding yarn laterally attains a proximity of the core yarn in a wrapping space; winding the winding yarn about the core yarn in the wrapping space, in such a way that, in the winding step, the winding yarn becomes twisted with a final twist direction opposite to the initial twist direction, i.e., with a final twist direction selected between "S" and "Z", respectively; - obtaining the wound yarn on the collecting bobbin; - forming a fabric from the wound yarn by a fabric-making process selected between a knitting process and a weaving process; wherein the method comprises a step of washing, selected between a step of washing the fabric or / and a step of washing the wound yarn, wherein - the core yarn is a non-elastomeric yarn; - the step of winding the winding yarn is carried out in such a way that the winding yarn forms a sequence of turns about the core yarn, the turns having a pitch longer than a diameter of the winding yarn, in such a way that free spaces are left between the turns; - the pulling force that is applied to the core yarn is lower than a minimum predetermined force value selected in such a way that the core yarn forms a sequence of ridges protruding between the free spaces, - the conveying speeds are selected in such a way that, in the winding step, a number of turns T higher than a predetermined minimum number of turns T0, and lower than a predetermined maximum number of turns T1 of the winding yarn is wound per length unit of the wound yarn, the minimum number of turns T0 and the maximum number of turns T1 depending on the second linear mass density Nmw, wherein, for each value of the second linear mass density Nmw indicated in a respective line of the following table Nm w T 0 T 1 120502405003606001015010002020013003025014004030015005030016007040017009050018001206002000 , the minimum and maximum number of turns T0, T1 are the numbers written in the respective line and in the columns headed by T0 and T1 of the table, respectively.

[0016] In the present specification, the word "wound" can relate to either a very loose winding conformation, in which a wide space (pitch) is present between subsequent turns, or a tighter conformation, in which said space is narrower, provided some space is left between contiguous turns.

[0017] The number of turns per meter of a wound yarn is meant as the number of turns that can be directly counted as the number of reverse turns that a piece of that wound yarn having a predetermined length should receive in order to completely remove the turns therefrom, such piece of yarn arranged between two fixed end points and having a predetermined initial tensile strain. In particular, the predetermined length and tensile strain are selected according to ISO rules 2061.

[0018] Accordingly, by the washing step, the wound yarn shrinks in such a way that the ridges of the core yarn are compressed between the turns of the winding yarn, causing such a wound yarn incorporated in a fabric to become elastic and, therefore, causing also the fabric itself to become elastic, which is a fully unexpected result.

[0019] Since the winding step is carried out by reversing the twist direction of the winding yarn, the winding yarn and the core yarn will have twist directions opposite to each other in the wound yarn.

[0020] In particular, since the two yarns forming the structure of the wound yarn, i.e., the core yarn and the winding yarn, are twisted in opposite twist directions in the wound yarn, namely they are Z- and S- twisted, respectively, or S- and Z-twisted, respectively, after the washing step, opposite inner reaction forces arise in the shrunk wound yarn between the winding yarn and the core yarn. This causes an intrinsic elasticity, such that, upon stretching and then releasing the fabric, the latter performs an elastic return.

[0021] For the same reason, the wound yarn will be inherently resistant to any further twisting action. Therefore, a balanced fabric is obtained, which is more difficult to obtain if the core yarn and the winding yarn had the same twist direction, in particular, if the wound yarn is intended to make fabrics by knitting. The dimensional stability and the regularity of the articles made by such a fabric will be improved.

[0022] Moreover, since the turns of the wound yarn are spaced apart from one another, full zones and empty zones are present side by side in the fabric. This way, the friction between the user's skin and a garment manufactured by the fabric made according to the invention is reduced, which assists the physiologic heat and moisture exchange between the user and the environment, briefly, a fresh touch is provided, which is not usual in the case of the currently-available elasticized fabrics. Therefore, summer garments can be advantageously manufactured with the fabric made by the method according to the invention.

[0023] The winding yarn, as prearranged, can have an initial "Z"-twist direction, which is usual for the yarns available on market, and the step of winding is carried out with a clockwise or counter-clockwise winding direction, so that the winding yarn, while being wound about the core yarn, is counter-twisted to such an extent to completely loose its initial "Z"-twist direction and to become twisted in the opposite "S"-twist direction, until a final twisting degree is attained depending on the final number of turns formed about the core yarn. As an alternative, the winding yarn, as prearranged, can have an initial "S"-twist direction and the step of winding is carried out in such a way that the winding yarn, while being wound about the core yarn, is counter-twisted to such an extent to completely loose its initial "S"-twist direction and to become twisted in the opposite "Z"-twist direction, until a final twisting degree is attained depending on the final number of coils formed about the core yarn. If, on the contrary, the step of winding were carried out in such a way to increase the torsions in the initial "Z" or "S"-twist direction, the resulting winding would be too "tight" to allow any elasticity to arise in the wound yarn, or the wound yarn would soon become tight enough to break before a desired number of coils is formed about the core yarn.

[0024] As well known, the linear mass density Nm (here Nm c and Nm w ) of a yarn or of a filament corresponds to the length in kilometres of 1 kg of wire or of yarn or filament, and can therefore be expressed in km / kg. In particular, the winding yarn and the core yarn have, independently from one another, a linear mass density set between 1 and 120 km / kg.

[0025] Preferably, the pulling force F applied to the core yarn is higher than a predetermined minimum force F 0 . A poor tensioning of the core yarn would make it substantially impossible for the winding yarn to be wound about the core yarn. Moreover, the pulling force applied to the core yarn must exceed a minimum value in order to assure uniform features to the wound yarns obtained by the multiple winding units of a same winding machine. The predetermined minimum force depends on the linear mass density of the core yarn.

[0026] In particular, for each first linear mass density value Nm c indicated in a respective line of table 1, the minimum force F 0 is equal to the force value F 0 written in the same line of table 1, expressed in grams, whereas, for values intermediate between two adjacent values of the first linear mass density Nm c indicated in respective adjacent lines of table 1, the minimum force F 0 can be obtained by linearly interpolating the force values F 0 written in the same adjacent lines of table 1. - Table 1 -Nm c F 0 1502453401062053044035027019011201 - Table 2 - Nm c F 1 170265360104020353035403350307030902912025

[0027] According to the invention, as anticipated, pulling force F applied to the core yarn is lower than a predetermined maximum force F 1 . If a pulling force is applied to the core yarn exceeding the above maximum force value, the core yarn would remain stiff and straight during and after the winding step, instead of forming the ridges, as previously described. For this reason, neither the wound yarn obtained in these conditions, nor a fabric made therefrom, would be able to behave elastically when stretched. For the same reason, the above-mentioned spacing effect of the ridges on the turns of the wound yarn would be missing, and the low-friction and high heat and moisture transfer properties of the fabrics would be lost, along with the pleasant and fresh touch feel provided to the users wearing garments made of such fabrics.

[0028] In particular, for each first linear mass density value Nm c indicated in a respective line of table 2, the maximum force F 1 is equal to the force value F 1 , expressed in grams, written in the same line of table 2. In particular, for values intermediate between two adjacent values of the first linear mass density Nm c indicated in respective adjacent lines of table 2, the maximum force F 1 is obtained by linearly interpolating the force values F 1 written in the same adjacent lines of table 2.

[0029] According to the invention, as stated above, during the step of winding the winding yarn, the conveying speeds of the core yarn and of the winding yarn are selected in such a way that the number of turns T per length unit of the yarn is higher than a predetermined minimum number of turns T 0 .

[0030] In particular, for each second linear mass density value Nm w indicated in a respective line of table 3, the minimum number of turns T 0 is equal to the number T 0 written in the same line of table 3. In particular, for values intermediate between two adjacent values of the second linear mass density Nm w indicated in respective adjacent lines of the table, the minimum number of turns T O is obtained by linearly interpolating the numbers T O written in the same adjacent lines of table 3. - Table 3 -Nm w T 0 12024036010150202003025040300503007040090500120600 - Table 4 - Nm w T 1 150250036001010002013003014004015005016007017009018001202000

[0031] Preferably, during the step of winding the winding yarn, the conveying speeds of the core yarn and of the winding yarn are selected in such a way that the number of turns T per length unit of the yarn is lower than a predetermined maximum number of turns T 1 . If a number of turns of the winding yarn is wound exceeding the above maximum number, the portions of core yarn between any two adjacent ridges, protruding between respective couples of turns, would be too short to allow an overall elongation / an elastic return of the wound yarn upon stretching / releasing the same, and therefore the wound yarn, as well as the fabric made thereof, would have poor elastic properties even once the washing step has been performed. Moreover, if too many turns were wound about the core yarn, the above-mentioned spacing effect of the ridges on the turns of the wound yarn would be missing, and the low-friction and high heat and moisture transfer properties of the fabrics would be lost, along with the pleasant and fresh touch feel provided to the users wearing garments made of such fabrics.

[0032] In particular, for each second linear mass density value Nm w indicated in a respective line of table 4, the maximum number of turns T 1 is equal to the number T 1 written in the same line of the table, whereas, for values intermediate between two values of the second linear mass density Nm w indicated in respective adjacent lines of the table, the maximum number of turns T 1 is obtained by linearly interpolating the numbers T 1 written in the same adjacent lines of table 4.

[0033] Preferably, the step of washing comprises a step of open-width washing or rope washing the fabric in water, in particular the step of washing is carried out in such conditions and during such a washing time that the fabric shrinks by 15% to 30%.

[0034] Advantageously, the core yarn and the winding yarn, independently from each other, are made of a natural fibre or an artificial fibre, or a combination of a natural fibre and an artificial fibre. If synthetic fibres are not used, such as nylon, polyester, acrylic fibres, the fabric and the articles made thereof will be more easily degradable by exposition to the environment, in particular by composting. In particular, the natural fibre used to manufacture the wound yarn can be selected from the group consisting of: linen; hemp; ramie; bamboo; jute; cotton; wool; silk; a combination of the above fibres. In particular, the artificial fibre used to manufacture the wound yarn can be selected from the group consisting of: Rayon (including viscose), Tencel, Lyocel, milk fibres, orange fibres, nettle fibres, kapok fibres, all biodegradable materials, and a combination of the above fibres.

[0035] In particular, the core yarn and the winding yarn have the same composition. This way, the fabric obtained is completely homogeneous, and can be disposed even more easily, according to the prescriptions for one kind of material.

[0036] In particular, the winding yarn is a discontinuous yarn, and the wrapping space is a protected space enclosed in a container. This is the case of natural fibres and most artificial fibres such as Rayon. As well known, the cohesion between the fibres, and therefore the resistance of the discontinuous yarn made thereof is mainly provided by a twisting process.. By the method described above, the discontinuous winding yarn, after losing its initial twist direction, e.g., "Z", and before becoming twisted in the opposite final twist direction, e.g. "S", crosses an untwisted condition in which the cohesion of the discontinuous fibres forming the yarn is very poor or absent. By protecting the wrapping space in a closed container, the friction between the fibres and the air is minimized, which prevents the risk of desegregating the discontinuous winding yarn when instantaneously untwisted, as described above.

[0037] The core yarn and the winding yarn can be, independently from each other, a one-filament yarn or a multi-filament yarn. For instance, the core yarn can be a two-filament yarn, wherein one filament is made of cashmere and the other filament is made of silk, whereas the winding yarn is made of linen or, in a similar but cheaper structure, the core yarn can be a two-filament yarn, wherein one filament is made of wool and the other filament is made of Rayon, whereas the winding yarn is made of hemp. This makes it possible to obtain an unusual combination of such properties as thermal comfort, brightness and touch of the garments made thereof, in particular, it allows the currently unusual use of such materials as cashmere and wool to manufacture summer garments, or in any case items of clothing that can be comfortably worn in a hot and wet environment.

[0038] In particular, the step of conveying comprises: steps of causing the core yarn and the winding yarn to pass through a longitudinal recess and along a side surface of a cylindrical hollow body turning at a predetermined speed, respectively, the longitudinal recess having an inlet and an outlet for the core yarn; a step of causing the core yarn and the winding yarn to pass through an orifice facing the outlet of the longitudinal recess of the cylindrical hollow body and arranged, at a predetermined distance from said outlet, and wherein the wrapping space is arranged between the outlet of the longitudinal recess of the cylindrical body and the orifice, in such a way that the container has an opening at the orifice and the core yarn and the winding yarn are caused to pass through the orifice in the form of wound yarn.

[0039] More in detail, the step of prearranging the core includes a step of prearranging a first bobbin containing the winding core yarn, while the step of prearranging the winding yarn includes a step of mounting a second bobbin or spool containing the winding yarn coaxially to a cylindrical hollow body. The step of conveying the core includes a step of pulling the core yarn from the first bobbin by a predetermined pulling force and at a predetermined unwinding speed equal to said conveying speed, before conveying it into a central through hole of the cylindrical hollow body. The step of conveying the core also includes a step of applying a pulling force to the core at the outlet of the orifice, the winding yarn being wound, and of collecting the wound yarn on a third collecting bobbin.

[0040] The method can be actuated by a conventional hollow-spindle machine, such as a Hamel-type machine. If a discontinuous winding yarn is used, the machine will be preferably equipped with a protected wrapping space enclosed in a container.

[0041] An alternative method for making an elasticized fabric, according to a second aspect of the invention, includes the steps of: forming a wound yarn, comprising the steps of: prearranging a core yarn having a first linear mass density Nm c ; prearranging a winding yarn having a second linear mass density Nm w applying a predetermined pulling force to the core yarn; conveying the core yarn and the winding yarn at respective conveying speeds towards a collecting bobbin of the wound yarn, wherein the step of conveying is carried out in such a way that the winding yarn laterally attains a proximity of the core yarn in a wrapping space; winding the winding yarn about the core yarn in the wrapping space; obtaining the wound yarn on the collecting bobbin; forming a fabric from the wound yarn by a fabric-making process selected between a knitting process and a weaving process; wherein the method comprises a step of washing selected between a step of washing the fabric or / and a step of washing the wound yarn, wherein: the core yarn is a non-elastomeric yarn; the step of winding is carried out in such a way that the winding yarn forms a sequence of turns about the core yarn, the turns having a pitch longer than a diameter of the winding yarn, in such a way that free spaces are left between the turns; in the wound yarn, the core yarn and the winding yarn are twisted with respective twist directions opposite to each other; the pulling force that is applied to the core yarn is lower than a predetermined force value selected in such a way that the core yarn forms a sequence of ridges protruding between the free spaces, such that, by the washing step, the wound yarn shrinks in such a way that the ridges of the core yarn are compressed between the turns of the winding yarn causing the wound yarn, which is incorporated in the fabric, to become elastic and, therefore, causing also the fabric to become elastic, wherein the conveying speeds are selected in such a way that, in the winding step, a number of turns T, higher than a predetermined minimum number of turns T 0 , and lower than a predetermined maximum number of turns T 1 of the winding yarn is wound per length unit of the wound yarn, the minimum number of turns T0 and the maximum number of turns T1 depending on the second linear mass density Nmw, wherein, for each value of the second linear mass density Nmw indicated in a respective line of the following table Nm w T 0 T 1 120502405003606001015010002020013003025014004030015005030016007040017009050018001206002000 , the minimum and maximum number of turns T0, T1 are the numbers written in the respective line and in the columns headed by T0 and T1 of the table, respectively.

[0042] The technical effects of the features common to the method according to the first aspect of the invention also applies in this case. The above-mentioned optional features can be optionally present in combination with the features of the method according to the second aspect as well, producing similar technical effects and advantages.

[0043] The above-mentioned objects of the invention are achieved also by an elasticized yarn as defined by attached claim 9, and by an elasticized fabric as defined by attached claim 15. Exemplary specific embodiments of the invention are defined by the dependent claims 10 to 14.

[0044] According to a third aspect of the invention, the elasticized yarn comprises: a core yarn having a first linear mass density Nm c ; a winding yarn having a second linear mass density Nm w ; wherein the core yarn is a non-elastomeric yarn; the winding yarn forms a sequence of turns about the core yarn, the turns having a pitch longer than a diameter of the winding yarn, in such a way that free spaces are left between the turns; in the wound yarn, the core yarn and the winding yarn are twisted with respective twist directions opposite to each other; the winding yarn forms a number of turns T higher than a predetermined minimum number of turns T 0 , and lower than a predetermined maximum number of turns T 1 of the winding wire per length unit of the wound yarn, the minimum number of turns and maximum number of turns depending on the second linear mass density Nm, wherein, for each value of the second linear mass density Nm indicated in a respective line of the table below N m T 0 T 1 120502405003606001015010002020013003025014004030015005030016007040017009050018001206002000 , the numbers of minimum and maximum turns T0, T1 are the numbers written in the respective line and in the columns respectively headed by T0 and T1 of the table.

[0045] Advantageously, for intermediate values between two adjacent values of the second linear mass density Nm w indicated in respective adjacent lines of the table, the minimum and maximum number of turns T 0 , T 1 are obtained by linearly interpolating the numbers, respectively, written in the respective lines and in the columns headed by T 0 and T 1 , respectively, of the table.

[0046] Advantageously, the core yarn and the winding yarn, one independently from the other, are obtained from a fibre selected between a natural fibre and a fibre artificial, or a combination of a natural fibre and an artificial fibre.

[0047] Advantageously, the natural fibre is selected from linen; hemp; ramie; bamboo; jute; cotton; wool; silk; a combination of the above.

[0048] Advantageously, the artificial fibre is selected from the group comprised of: Rayon, Tencel, Lyocel, milk, orange, nettle, kapok fibres, a combination of the above.

[0049] The elasticized yarn according to claim 17, wherein the core yarn and the winding yarn are, one independently from the other, selected from single-ply and multi-ply threads.

[0050] Advantageously, the core yarn is a two-ply thread of cashmere and silk respectively, while the winding yarn is of linen.

[0051] Advantageously, the core yarn is a two-ply thread of wool and viscose respectively, while the winding yarn is of hemp.

[0052] It falls within the scope of the invention also as an elasticized fabric at least in part made of the above-elasticised yarn.Brief description of the drawings

[0053] The method for making an elasticized fabric is described hereinafter with reference to the attached drawings, in which Figs. 1A and 1B diagrammatically illustrates the step of winding the winding yarn about the core yarn, so as to obtain the wound yarn; Fig. 2 diagrammatically shows a hollow spindle twisting machine to form the wound yarn in the process for manufacturing an elasticized fabric; Fig. 3 diagrammatically shows a wound yarn in an extended condition, as collected on a collecting bobbin; Fig.4 diagrammatically shows the yarn of Fig. 4, in a non-extended condition; Fig. 5 is a diagram showing the minimum and maximum values of the pulling force applied to the core yarn, plotted against the first linear mass density Nm c of the core yarn; Fig. 6 is a diagram showing the minimum number of turns per length unit of the wound yarn, plotted against the second linear mass density Nm w of the winding yarn. Description of preferred exemplary embodiments

[0054] With reference to Figs. 1A and 1B, in order to manufacture an elasticized fabric, the method according to the invention comprises a step of making a wound yarn by winding a winding yarn 40 having a second linear mass density Nm w and an initial twist direction "Z" (Fig. 1A) or "S" (Fig. 1B), about a core yarn 30 having a first linear mass density Nm c and an initial twist direction "Z" (Fig. 1A) or "S" (Fig. 1B), respectively, i.e., the same twist direction as winding yarn 40.

[0055] According to the present invention, and unlike the yarns commonly used to make elasticized yarns, core yarn 30 is a non-elastomeric yarn, or in any case a substantially inextensible yarn, i.e. a yarn having an ultimate elongation of 5% or lower.

[0056] Typically, the initial twist direction of winding yarn 40 is "Z", as well as the initial twist direction of core yarn 30, as normally available on market (Fig. 1A).

[0057] In order to carry out the step of winding winding yarn 40, a predetermined pulling force F is applied to core yarn 30, preferably in the way described more in detail hereinafter. Moreover, steps are carried out of conveying core yarn 30 and winding yarn 40 at speeds v 1 , v 2 , respectively, towards a wrapping space 35, where winding yarn 40 laterally, i.e. tangentially, reaches core yarn 30, a predetermined angle α being formed between an axis of core yarn 30 and an axis of winding yarn 40. Angle α is selected in such a way that a sequence of turns 45 is formed about core yarn 30 in which turns 45 are arranged at a pitch p with respect to each other, wherein pitch p is longer than diameter d of winding yarn 40, preferably longer than a predetermined number of times diameter d. This number of times is preferably set between 1 and 8, more preferably between 2 and 5. This way, free spaces 55 are left between turns 45 whose width depends on pitch p and diameter d of winding yarn 40.

[0058] Pulling force F applied to core yarn 30 is selected in such a way that core yarn 30 is not excessively stretched, i.e. in such a way that core yarn 30, due to and during the operation of winding, forms a sequence of ridges 31 that tends to protrude through free spaces 55 between turns 45 of winding yarn 40 already wound about core yarn 30.

[0059] Moreover, conveying speeds v 1 and v 2 are selected in such a way that, during the winding step, the twist direction of winding yarn 40 changes, turning from "Z" to "S" (Fig. 1A) or vice-versa (Fig. 1B), according to the initial twist direction of winding yarn 40 in use.

[0060] The method for making the elasticized fabric also comprises a step of forming the fabric from wound yarn 50. This can be a substantially conventional process of knitting or weaving, or the like.

[0061] A step is also provided of washing the yarn or the fabric, in the latter case an open-width washing step or a rope washing step, which is carried out during or before a step of dyeing the yarn or the fabric. The step of washing can be carried out both on wound yarn 50 and on fabric 60, the latter being typically the case of the fabrics manufactured by a process of weaving.

[0062] Fig. 3 diagrammatically shows wound yarn 50 as collected on a collecting bobbin. In wound yarn 50, yarns 30,40 forming the structure of wound yarn 50, i.e., core yarn 30 and winding yarn 40, are twisted in the opposite twist directions in wound yarn 50. Due to the washing, wound yarn 50 shrinks, as shown in Fig. 4, and ridges 31 of core yarn 30 are compressed between turns 45 of winding yarn 40. So, wound yarn 50 is brought from extended condition A of Fig. 3, in which a same piece of wound yarn 50 has a length L A , to non-extended condition B of Fig. 4, in which a same piece of wound yarn 50 has a length L B shorter than L A . Due to the opposite twist direction of core yarn 30 and winding yarn 40, shrunk wound yarn 50 opposite inner reaction forces arise between winding yarn 40 and core yarn 30. This causes an intrinsic elasticity, such that, upon stretching and then releasing a fabric containing wound yarn 50 (Fig. 3 and 4), , wound yarn 50 performs an elastic return. This way, the step of washing, carried out on both wound yarn 50 and on fabric 60, generates or increases an elasticity of wound yarn 50 incorporated in fabric 60 and, accordingly, generates or increases the elasticity of fabric 60.

[0063] The same applies to any elasticized yarn according to the third aspect of the invention, in which, i.a., core yarn 30 and winding yarn 40 are twisted with opposite twist directions in the wound yarn.

[0064] Apart from the limitation that core yarn 30 does not contain any elastomeric materials, which is the case, instead, in the yarns used for making conventional elasticized fabrics, core yarn 30 and winding yarn 40, independently from each other, can contain any textile material. However, core yarn 30 and winding yarn 40 can have the same composition.

[0065] In particular, core yarn 30 and winding yarn 40 can contain natural fibres such as hemp, ramie, bamboo, jute, cotton, wool, silk, etc., or combinations thereof.

[0066] As an alternative, core yarn 30 and winding yarn 40 can contain artificial fibres, such as Rayon, Tencel, Lyocel, milk fibres, orange fibres, nettle fibres, kapok fibres and so on, or combinations thereof.

[0067] The above materials are preferred, however, synthetic fibres can also be used in the invention, such as nylon, polyester, acrylic and other fibres, and combinations thereof. Combinations can also be used of natural material, artificial, synthetic materials, preferably, combinations containing natural and artificial materials.

[0068] In an exemplary embodiment, core yarn 30 and winding yarn 40, regardless of their combination and of their linear mass densities Nm c , Nm w , are wires twisted with the same initial twist direction "Z" or "S", with the above-mentioned advantages.

[0069] In some preferred exemplary embodiments, core yarn 30 and winding yarn 40 are selected, independently from each other, between a one-filament yarn and a multi-filament yarn. In an example thereof, core yarn 30 is a two-filament yarn, wherein one filament is made of cashmere and the other filament is made of silk, whereas winding yarn 40 is made of linen. In another example, core yarn 30 is a two-filament yarn, wherein one filament is made of wool and the other filament is made of Rayon, whereas winding yarn 40 is made of hemp.

[0070] In the present method, the pulling force applied to core yarn 30 is preferably higher than a predetermined minimum force value F 0 , so that core yarn 30 is stretched enough for winding yarn 40 to be easily wound about it, and to assure uniform features to the wound yarns obtained by the multiple winding units of a same winding machine.

[0071] Moreover, according to the invention, the pulling force applied to core yarn 30 is lower than a predetermined maximum force value F 1 that should not be exceeded in order not to lose the low-friction and high heat and moisture transfer properties of the fabrics, along with the pleasant and fresh touch feel provided to the users wearing garments made of such fabrics, and in order to obtain acceptable elastic properties of wound yarn 50, as the experience has shown.

[0072] Minimum and maximum values F 0 , F 1 of the pulling force depend on first linear mass density Nm c of core yarn 40, as tables 1 and 2 show. In the diagram of Fig. 5, minimum pulling force value F 0 and maximum pulling force value F 1 are plotted against first linear mass density Nm c of core yarn 40 as curves 71 and 72, respectively. Curves 71 and 72 are obtained by interpolating the values of tables 1 and 2, respectively.

[0073] According to the invention, in the present method, conveying speeds v 1 and v 2 are selected in such a way that, in the winding step, the number of turns formed by winding yarn 40 about core yarn 30 per length unit of wound yarn 50 is higher than a predetermined minimum number of turns T 0 , in order to make the stack of turns compact enough to create an elastic return force upon releasing a pulling force acting on it, and to avoid uneven winding conditions among the parallel winding units of a winding machine.

[0074] Moreover, regardless of the above, the number of turns formed by winding yarn 40 about core yarn 30 per length unit of wound yarn 50 is preferably lower than a predetermined maximum number of turns T 1 that should not be exceeded in order not to lose the low-friction and high heat and moisture transfer properties of the fabrics, along with the pleasant and fresh touch feel provided to the users wearing garments made of such fabrics, and in order to obtain acceptable elastic properties of wound yarn 50, as the experience has shown.

[0075] Minimum and maximum number of turns T 0 , T 1 depend on second linear mass density Nm w of winding yarn 40, as tables 3 and 4 show. In the diagram of Fig. 6, minimum number of turns T 0 and maximum number of turns T 1 are plotted against second linear mass density Nm w of winding yarn 40 as curves 81 and 82, respectively. Curves 81 and 82 are obtained by interpolating the values of tables 3 and 4, respectively.

[0076] As shown in Fig. 2, the steps of conveying core yarn 30 and covering yarn 40 are controlled by the speed by which wound yarn 50 is collected on collecting bobbin 51 of wound yarn 50, while, as a consequence, core yarn 30 and winding yarn 40 are drawn from respective spools, not shown and 41, respectively.

[0077] In an exemplary embodiment, the step of conveying core yarn 30 towards wrapping space 35 is carried out through a central hole 63 of a first cylindrical body 61 turning at a predetermined high speed about its own axis 63', i.e., core yarn 30 is conveyed along a substantially linear path. On the contrary, the step of conveying winding yarn 40 is carried out along the outer surface 62 of first cylindrical body 61, preferably along a guide arranged thereon. Preferably, first cylindrical body 61 is integrally and coaxially housed in a second hollow cylindrical body 64, cylindrical bodies 61,64 forming a conveying unit 60. Bobbin 41 of covering yarn 40 is fixed inside second cylindrical body 64, therefore covering yarn 40 is conveyed through a gap 65 between bobbin 41 and the outer surface of first cylindrical body 61.

[0078] In this exemplary embodiment and, in particular, if winding yarn 40 is a discontinuous yarn, wrapping space 35 is a space normally closed, i.e. a protected space, in order to limit the interaction of the involved material, in particular of winding yarn 40, with the surrounding air. In this case, as Fig. 2 still shows, wrapping space 35 is defined between the outlet end 69 of first cylindrical body 61, at which core 30 enters into wrapping space 35, and an orifice 66 preferably arranged on axis 63', through which wound yarn 50 leaves wrapping space 35 and is conveyed towards collecting bobbin 51. The protection of wrapping space 35 is provided by a preferably axisymmetric wall 67 that converges from the inner surface of second cylindrical hollow body 64 to orifice 66, thus forming a container, which is an outlet passageway of wound yarn 50 from wrapping space 35.

[0079] Fig. 4 is a diagram showing the predetermined minimum number of turns T 0 that must be wrapped per length unit of elastic core yarn 50, for each value of second linear mass density Nm w of covering yarn 40, as a curve 81. Curve 81 is obtained by interpolating the values of table 3.

[0080] The diagram of Fig. 6 also shows a curve 82 indicating, for each value of second linear mass density Nm w of covering yarn 40, the predetermined maximum number of turns T 1 wrapped per length unit of elastic core yarn 50 that should not be exceeded in order to obtain acceptable elastic properties of wound yarn 50, as the experience has shown. Curve 82 is obtained by interpolating the values of table 4.

Examples

Embodiment Construction

[0054]With reference to Figs. 1A and 1B, in order to manufacture an elasticized fabric, the method according to the invention comprises a step of making a wound yarn by winding a winding yarn 40 having a second linear mass density Nm w and an initial twist direction "Z" (Fig. 1A) or "S" (Fig. 1B), about a core yarn 30 having a first linear mass density Nm c and an initial twist direction "Z" (Fig. 1A) or "S" (Fig. 1B), respectively, i.e., the same twist direction as winding yarn 40.

[0055]According to the present invention, and unlike the yarns commonly used to make elasticized yarns, core yarn 30 is a non-elastomeric yarn, or in any case a substantially inextensible yarn, i.e. a yarn having an ultimate elongation of 5% or lower.

[0056]Typically, the initial twist direction of winding yarn 40 is "Z", as well as the initial twist direction of core yarn 30, as normally available on market (Fig. 1A).

[0057]In order to carry out the step of winding winding yarn 40, a predetermined pullin...

Field of the invention

[0001] The present invention relates to a method for making elasticised fabrics that can be disposed more easily than conventional elasticized fabrics, and to elasticized fabrics made by such method.

[0002] In particular, the invention relates to a method for making biodegradable fabrics consisting of biodegradable materials that can be disposed, for instance, by composting, and to elasticized fabrics made by such method.

[0003] The invention also relates to elasticized yarns to be used for making such fabricsReference to the prior art - Technical problems

[0004] Since some decades, elasticized fabrics made from elastic thread yarns of many kinds are used. The advantage of these fabrics is a high deformability of the items made therefrom. In particular, garments are made that do not hinder the movements of the limbs of the user, or conform themselves to these movements, thus generating a comfort sensation. This is particularly appreciated in underwear clothing or in sport and gym clothes, but is also appreciated in everyday life situations, such as sitting in a car, walking and whenever the joints must be bent. Moreover, elasticized fabrics are used to make bandages, dressings and garments for treating wounds, sprains, inguinal hernia and the like. Besides, elasticized fabrics are advantageous for making general-purpose gloves, as well as covers for sofas, armchairs and chairs, since rounded covers can be easily manufactured therefrom.

[0005] The features of currently-available elasticized fabrics depend on the high elasticity of the elasticized yarns used to make them. The elasticity of the elasticized yarns depends in turn on the use of a core elastomeric fibres in combination with covering yarns that are wrapped or form turns about the core elastomeric fibre and that can consist of various textile materials.

[0006] For instance, documents WO 2008 / 130563 A1 and WO 2012 / 062480 A2 describe ring-spun elastic composite yarns, in which an elastic core filament made of a synthetic elastomeric material is surrounded by a fibrous sheath consisting of a mass of synthetic or natural spun staple fibres, for instance cotton fibres. Other elasticized yarns, as those described in WO 2012 / 056436 and in WO 2019 / 159155, are obtained by winding machines, in which a substantially inextensible yarn is wound about the elastic core filament made of a synthetic elastomeric material to form a helix or a spiral about the elastic yarn. By applying a tensile force to elasticized yarn obtained this way, the turns of the helix formed about the core move away from one another and, by successively releasing the tensile force, the turns and the helix tend to return to the initial conformation. This behaviour allows an elastic recovery of the elasticized yarn and of the fabrics made thereof.

[0007] In the above prior art elasticized products, drawbacks arise from the use of a core elastic fibre made of a synthetic elastomeric material.

[0008] Firstly, these fabrics comprise an elastomeric portion and a fibrous portion of various materials. This heterogeneity makes it difficult to recycle the articles made of these fabrics when they are dismissed, since the two types of material should be separately recycled by specific techniques. Moreover, even if the fibrous sheath or the inextensible yarn wound about the core is made of a natural, tendentially biodegradable material, such as linen; hemp; ramie; bamboo; jute; cotton; wool; silk, the presence of the synthetic elastomeric portion, i.e. of a non-biodegradable portion, exclude composting as a possible disposal method for the items of clothing and similar textile products made of a related fabric, which would be one of the most preferred cheap and environment-friendly disposal methods known so far for such items. Briefly, the above-mentioned elasticised fabrics are scarcely environmentally sustainable and do not meet the requirements of a circular economy.

[0009] To cope with such a problem, WO 2020 / 084361 describes elasticized yarns having the same structure as in WO 2012 / 056436, in which elastomeric core is made of natural rubber, and the substantially inextensible yarn wound about the natural rubber core is based on cotton.

[0010] CN110528133A discloses a method for making an elastic loop composite yarn of a wrapped structure, according to which elastic yarns in a drafted state and non-elastic yarns are combined to form an elastic / non-elastic double-core yarn that is wrapped with an outer wrapping yarn to form the composite yarn of the wrapped structure and, finally, the drafting force for the elastic yarns in the composite yarn of the wrapped structure is removed, so that the elastic yarns in the composite yarn of the wrapped structure elastically retract to be in a non-drafted state, the non-elastic yarns are compressed and bent along the yarn axis direction due to the elastic retraction of the elastic yarns and protrude between spiral threads of the outer wrapping yarn to form a yarn loop, and the elastic loop composite yarn of the wrapped structure is prepared. The elastic loop composite yarn of the wrapped structure prepared by means of the method is wound and stored for use in the form of the composite yarn of the wrapped structure before the yarn loop is formed, and unwound to form the yarn loop during use. This way, the quality of the yarn loop is not influenced once the loop composite yarn is stored and conveyed for a long time, and the subsequent application of the loop composite yarn is facilitated.Summary of the invention

[0011] It is therefore an object of the present invention to provide a method for making an elasticized fabric having a homogeneous structure, i.e., a structure formed by materials that can be disposed by a same disposal process, thus simplifying the recyclability of items of clothing and similar products made by such an elasticized product.

[0012] It is a particular object of the invention to provide a method, different from prior art methods, for making a fully biodegradable elasticized fabric that can be disposed by composting items of clothing made thereof, once the latter have been dismissed.

[0013] It is also an object of the invention to provide a method for making an elasticized fabric that provides a pleasant and fresh touch feel to a user, as required, in particular, in the case of summer garments.

[0014] These and other objects are achieved by a method as defined by attached claims 1 and 15. Exemplary specific embodiments of the invention are defined by the respective dependent claims.

[0015] According to a first aspect of the invention, a method for making an elasticized fabric comprises the steps of: - forming a wound yarn, comprising the steps of: prearranging a core yarn having a first linear mass density Nm c : prearranging a winding yarn having a second linear mass density Nm w and twisted with an initial twist direction selected between "Z" and "S", wherein the core yarn is twisted with an initial twist direction equal to the initial twist direction of the winding yarn; applying a predetermined pulling force to the core yarn; conveying the core yarn and the winding yarn at respective conveying speeds towards a collecting bobbin of said wound yarn (51), wherein said step of conveying is carried out in such a way that the winding yarn laterally attains a proximity of the core yarn in a wrapping space; winding the winding yarn about the core yarn in the wrapping space, in such a way that, in the winding step, the winding yarn becomes twisted with a final twist direction opposite to the initial twist direction, i.e., with a final twist direction selected between "S" and "Z", respectively; - obtaining the wound yarn on the collecting bobbin; - forming a fabric from the wound yarn by a fabric-making process selected between a knitting process and a weaving process; wherein the method comprises a step of washing, selected between a step of washing the fabric or / and a step of washing the wound yarn, wherein - the core yarn is a non-elastomeric yarn; - the step of winding the winding yarn is carried out in such a way that the winding yarn forms a sequence of turns about the core yarn, the turns having a pitch longer than a diameter of the winding yarn, in such a way that free spaces are left between the turns; - the pulling force that is applied to the core yarn is lower than a minimum predetermined force value selected in such a way that the core yarn forms a sequence of ridges protruding between the free spaces, - the conveying speeds are selected in such a way that, in the winding step, a number of turns T higher than a predetermined minimum number of turns T0, and lower than a predetermined maximum number of turns T1 of the winding yarn is wound per length unit of the wound yarn, the minimum number of turns T0 and the maximum number of turns T1 depending on the second linear mass density Nmw, wherein, for each value of the second linear mass density Nmw indicated in a respective line of the following table Nm w T 0 T 1 120502405003606001015010002020013003025014004030015005030016007040017009050018001206002000 , the minimum and maximum number of turns T0, T1 are the numbers written in the respective line and in the columns headed by T0 and T1 of the table, respectively.

[0016] In the present specification, the word "wound" can relate to either a very loose winding conformation, in which a wide space (pitch) is present between subsequent turns, or a tighter conformation, in which said space is narrower, provided some space is left between contiguous turns.

[0017] The number of turns per meter of a wound yarn is meant as the number of turns that can be directly counted as the number of reverse turns that a piece of that wound yarn having a predetermined length should receive in order to completely remove the turns therefrom, such piece of yarn arranged between two fixed end points and having a predetermined initial tensile strain. In particular, the predetermined length and tensile strain are selected according to ISO rules 2061.

[0018] Accordingly, by the washing step, the wound yarn shrinks in such a way that the ridges of the core yarn are compressed between the turns of the winding yarn, causing such a wound yarn incorporated in a fabric to become elastic and, therefore, causing also the fabric itself to become elastic, which is a fully unexpected result.

[0019] Since the winding step is carried out by reversing the twist direction of the winding yarn, the winding yarn and the core yarn will have twist directions opposite to each other in the wound yarn.

[0020] In particular, since the two yarns forming the structure of the wound yarn, i.e., the core yarn and the winding yarn, are twisted in opposite twist directions in the wound yarn, namely they are Z- and S- twisted, respectively, or S- and Z-twisted, respectively, after the washing step, opposite inner reaction forces arise in the shrunk wound yarn between the winding yarn and the core yarn. This causes an intrinsic elasticity, such that, upon stretching and then releasing the fabric, the latter performs an elastic return.

[0021] For the same reason, the wound yarn will be inherently resistant to any further twisting action. Therefore, a balanced fabric is obtained, which is more difficult to obtain if the core yarn and the winding yarn had the same twist direction, in particular, if the wound yarn is intended to make fabrics by knitting. The dimensional stability and the regularity of the articles made by such a fabric will be improved.

[0022] Moreover, since the turns of the wound yarn are spaced apart from one another, full zones and empty zones are present side by side in the fabric. This way, the friction between the user's skin and a garment manufactured by the fabric made according to the invention is reduced, which assists the physiologic heat and moisture exchange between the user and the environment, briefly, a fresh touch is provided, which is not usual in the case of the currently-available elasticized fabrics. Therefore, summer garments can be advantageously manufactured with the fabric made by the method according to the invention.

[0023] The winding yarn, as prearranged, can have an initial "Z"-twist direction, which is usual for the yarns available on market, and the step of winding is carried out with a clockwise or counter-clockwise winding direction, so that the winding yarn, while being wound about the core yarn, is counter-twisted to such an extent to completely loose its initial "Z"-twist direction and to become twisted in the opposite "S"-twist direction, until a final twisting degree is attained depending on the final number of turns formed about the core yarn. As an alternative, the winding yarn, as prearranged, can have an initial "S"-twist direction and the step of winding is carried out in such a way that the winding yarn, while being wound about the core yarn, is counter-twisted to such an extent to completely loose its initial "S"-twist direction and to become twisted in the opposite "Z"-twist direction, until a final twisting degree is attained depending on the final number of coils formed about the core yarn. If, on the contrary, the step of winding were carried out in such a way to increase the torsions in the initial "Z" or "S"-twist direction, the resulting winding would be too "tight" to allow any elasticity to arise in the wound yarn, or the wound yarn would soon become tight enough to break before a desired number of coils is formed about the core yarn.

[0024] As well known, the linear mass density Nm (here Nm c and Nm w ) of a yarn or of a filament corresponds to the length in kilometres of 1 kg of wire or of yarn or filament, and can therefore be expressed in km / kg. In particular, the winding yarn and the core yarn have, independently from one another, a linear mass density set between 1 and 120 km / kg.

[0025] Preferably, the pulling force F applied to the core yarn is higher than a predetermined minimum force F 0 . A poor tensioning of the core yarn would make it substantially impossible for the winding yarn to be wound about the core yarn. Moreover, the pulling force applied to the core yarn must exceed a minimum value in order to assure uniform features to the wound yarns obtained by the multiple winding units of a same winding machine. The predetermined minimum force depends on the linear mass density of the core yarn.

[0026] In particular, for each first linear mass density value Nm c indicated in a respective line of table 1, the minimum force F 0 is equal to the force value F 0 written in the same line of table 1, expressed in grams, whereas, for values intermediate between two adjacent values of the first linear mass density Nm c indicated in respective adjacent lines of table 1, the minimum force F 0 can be obtained by linearly interpolating the force values F 0 written in the same adjacent lines of table 1. - Table 1 -Nm c F 0 1502453401062053044035027019011201 - Table 2 - Nm c F 1 170265360104020353035403350307030902912025

[0027] According to the invention, as anticipated, pulling force F applied to the core yarn is lower than a predetermined maximum force F 1 . If a pulling force is applied to the core yarn exceeding the above maximum force value, the core yarn would remain stiff and straight during and after the winding step, instead of forming the ridges, as previously described. For this reason, neither the wound yarn obtained in these conditions, nor a fabric made therefrom, would be able to behave elastically when stretched. For the same reason, the above-mentioned spacing effect of the ridges on the turns of the wound yarn would be missing, and the low-friction and high heat and moisture transfer properties of the fabrics would be lost, along with the pleasant and fresh touch feel provided to the users wearing garments made of such fabrics.

[0028] In particular, for each first linear mass density value Nm c indicated in a respective line of table 2, the maximum force F 1 is equal to the force value F 1 , expressed in grams, written in the same line of table 2. In particular, for values intermediate between two adjacent values of the first linear mass density Nm c indicated in respective adjacent lines of table 2, the maximum force F 1 is obtained by linearly interpolating the force values F 1 written in the same adjacent lines of table 2.

[0029] According to the invention, as stated above, during the step of winding the winding yarn, the conveying speeds of the core yarn and of the winding yarn are selected in such a way that the number of turns T per length unit of the yarn is higher than a predetermined minimum number of turns T 0 .

[0030] In particular, for each second linear mass density value Nm w indicated in a respective line of table 3, the minimum number of turns T 0 is equal to the number T 0 written in the same line of table 3. In particular, for values intermediate between two adjacent values of the second linear mass density Nm w indicated in respective adjacent lines of the table, the minimum number of turns T O is obtained by linearly interpolating the numbers T O written in the same adjacent lines of table 3. - Table 3 -Nm w T 0 12024036010150202003025040300503007040090500120600 - Table 4 - Nm w T 1 150250036001010002013003014004015005016007017009018001202000

[0031] Preferably, during the step of winding the winding yarn, the conveying speeds of the core yarn and of the winding yarn are selected in such a way that the number of turns T per length unit of the yarn is lower than a predetermined maximum number of turns T 1 . If a number of turns of the winding yarn is wound exceeding the above maximum number, the portions of core yarn between any two adjacent ridges, protruding between respective couples of turns, would be too short to allow an overall elongation / an elastic return of the wound yarn upon stretching / releasing the same, and therefore the wound yarn, as well as the fabric made thereof, would have poor elastic properties even once the washing step has been performed. Moreover, if too many turns were wound about the core yarn, the above-mentioned spacing effect of the ridges on the turns of the wound yarn would be missing, and the low-friction and high heat and moisture transfer properties of the fabrics would be lost, along with the pleasant and fresh touch feel provided to the users wearing garments made of such fabrics.

[0032] In particular, for each second linear mass density value Nm w indicated in a respective line of table 4, the maximum number of turns T 1 is equal to the number T 1 written in the same line of the table, whereas, for values intermediate between two values of the second linear mass density Nm w indicated in respective adjacent lines of the table, the maximum number of turns T 1 is obtained by linearly interpolating the numbers T 1 written in the same adjacent lines of table 4.

[0033] Preferably, the step of washing comprises a step of open-width washing or rope washing the fabric in water, in particular the step of washing is carried out in such conditions and during such a washing time that the fabric shrinks by 15% to 30%.

[0034] Advantageously, the core yarn and the winding yarn, independently from each other, are made of a natural fibre or an artificial fibre, or a combination of a natural fibre and an artificial fibre. If synthetic fibres are not used, such as nylon, polyester, acrylic fibres, the fabric and the articles made thereof will be more easily degradable by exposition to the environment, in particular by composting. In particular, the natural fibre used to manufacture the wound yarn can be selected from the group consisting of: linen; hemp; ramie; bamboo; jute; cotton; wool; silk; a combination of the above fibres. In particular, the artificial fibre used to manufacture the wound yarn can be selected from the group consisting of: Rayon (including viscose), Tencel, Lyocel, milk fibres, orange fibres, nettle fibres, kapok fibres, all biodegradable materials, and a combination of the above fibres.

[0035] In particular, the core yarn and the winding yarn have the same composition. This way, the fabric obtained is completely homogeneous, and can be disposed even more easily, according to the prescriptions for one kind of material.

[0036] In particular, the winding yarn is a discontinuous yarn, and the wrapping space is a protected space enclosed in a container. This is the case of natural fibres and most artificial fibres such as Rayon. As well known, the cohesion between the fibres, and therefore the resistance of the discontinuous yarn made thereof is mainly provided by a twisting process.. By the method described above, the discontinuous winding yarn, after losing its initial twist direction, e.g., "Z", and before becoming twisted in the opposite final twist direction, e.g. "S", crosses an untwisted condition in which the cohesion of the discontinuous fibres forming the yarn is very poor or absent. By protecting the wrapping space in a closed container, the friction between the fibres and the air is minimized, which prevents the risk of desegregating the discontinuous winding yarn when instantaneously untwisted, as described above.

[0037] The core yarn and the winding yarn can be, independently from each other, a one-filament yarn or a multi-filament yarn. For instance, the core yarn can be a two-filament yarn, wherein one filament is made of cashmere and the other filament is made of silk, whereas the winding yarn is made of linen or, in a similar but cheaper structure, the core yarn can be a two-filament yarn, wherein one filament is made of wool and the other filament is made of Rayon, whereas the winding yarn is made of hemp. This makes it possible to obtain an unusual combination of such properties as thermal comfort, brightness and touch of the garments made thereof, in particular, it allows the currently unusual use of such materials as cashmere and wool to manufacture summer garments, or in any case items of clothing that can be comfortably worn in a hot and wet environment.

[0038] In particular, the step of conveying comprises: steps of causing the core yarn and the winding yarn to pass through a longitudinal recess and along a side surface of a cylindrical hollow body turning at a predetermined speed, respectively, the longitudinal recess having an inlet and an outlet for the core yarn; a step of causing the core yarn and the winding yarn to pass through an orifice facing the outlet of the longitudinal recess of the cylindrical hollow body and arranged, at a predetermined distance from said outlet, and wherein the wrapping space is arranged between the outlet of the longitudinal recess of the cylindrical body and the orifice, in such a way that the container has an opening at the orifice and the core yarn and the winding yarn are caused to pass through the orifice in the form of wound yarn.

[0039] More in detail, the step of prearranging the core includes a step of prearranging a first bobbin containing the winding core yarn, while the step of prearranging the winding yarn includes a step of mounting a second bobbin or spool containing the winding yarn coaxially to a cylindrical hollow body. The step of conveying the core includes a step of pulling the core yarn from the first bobbin by a predetermined pulling force and at a predetermined unwinding speed equal to said conveying speed, before conveying it into a central through hole of the cylindrical hollow body. The step of conveying the core also includes a step of applying a pulling force to the core at the outlet of the orifice, the winding yarn being wound, and of collecting the wound yarn on a third collecting bobbin.

[0040] The method can be actuated by a conventional hollow-spindle machine, such as a Hamel-type machine. If a discontinuous winding yarn is used, the machine will be preferably equipped with a protected wrapping space enclosed in a container.

[0041] An alternative method for making an elasticized fabric, according to a second aspect of the invention, includes the steps of: forming a wound yarn, comprising the steps of: prearranging a core yarn having a first linear mass density Nm c ; prearranging a winding yarn having a second linear mass density Nm w applying a predetermined pulling force to the core yarn; conveying the core yarn and the winding yarn at respective conveying speeds towards a collecting bobbin of the wound yarn, wherein the step of conveying is carried out in such a way that the winding yarn laterally attains a proximity of the core yarn in a wrapping space; winding the winding yarn about the core yarn in the wrapping space; obtaining the wound yarn on the collecting bobbin; forming a fabric from the wound yarn by a fabric-making process selected between a knitting process and a weaving process; wherein the method comprises a step of washing selected between a step of washing the fabric or / and a step of washing the wound yarn, wherein: the core yarn is a non-elastomeric yarn; the step of winding is carried out in such a way that the winding yarn forms a sequence of turns about the core yarn, the turns having a pitch longer than a diameter of the winding yarn, in such a way that free spaces are left between the turns; in the wound yarn, the core yarn and the winding yarn are twisted with respective twist directions opposite to each other; the pulling force that is applied to the core yarn is lower than a predetermined force value selected in such a way that the core yarn forms a sequence of ridges protruding between the free spaces, such that, by the washing step, the wound yarn shrinks in such a way that the ridges of the core yarn are compressed between the turns of the winding yarn causing the wound yarn, which is incorporated in the fabric, to become elastic and, therefore, causing also the fabric to become elastic, wherein the conveying speeds are selected in such a way that, in the winding step, a number of turns T, higher than a predetermined minimum number of turns T 0 , and lower than a predetermined maximum number of turns T 1 of the winding yarn is wound per length unit of the wound yarn, the minimum number of turns T0 and the maximum number of turns T1 depending on the second linear mass density Nmw, wherein, for each value of the second linear mass density Nmw indicated in a respective line of the following table Nm w T 0 T 1 120502405003606001015010002020013003025014004030015005030016007040017009050018001206002000 , the minimum and maximum number of turns T0, T1 are the numbers written in the respective line and in the columns headed by T0 and T1 of the table, respectively.

[0042] The technical effects of the features common to the method according to the first aspect of the invention also applies in this case. The above-mentioned optional features can be optionally present in combination with the features of the method according to the second aspect as well, producing similar technical effects and advantages.

[0043] The above-mentioned objects of the invention are achieved also by an elasticized yarn as defined by attached claim 9, and by an elasticized fabric as defined by attached claim 15. Exemplary specific embodiments of the invention are defined by the dependent claims 10 to 14.

[0044] According to a third aspect of the invention, the elasticized yarn comprises: a core yarn having a first linear mass density Nm c ; a winding yarn having a second linear mass density Nm w ; wherein the core yarn is a non-elastomeric yarn; the winding yarn forms a sequence of turns about the core yarn, the turns having a pitch longer than a diameter of the winding yarn, in such a way that free spaces are left between the turns; in the wound yarn, the core yarn and the winding yarn are twisted with respective twist directions opposite to each other; the winding yarn forms a number of turns T higher than a predetermined minimum number of turns T 0 , and lower than a predetermined maximum number of turns T 1 of the winding wire per length unit of the wound yarn, the minimum number of turns and maximum number of turns depending on the second linear mass density Nm, wherein, for each value of the second linear mass density Nm indicated in a respective line of the table below N m T 0 T 1 120502405003606001015010002020013003025014004030015005030016007040017009050018001206002000 , the numbers of minimum and maximum turns T0, T1 are the numbers written in the respective line and in the columns respectively headed by T0 and T1 of the table.

[0045] Advantageously, for intermediate values between two adjacent values of the second linear mass density Nm w indicated in respective adjacent lines of the table, the minimum and maximum number of turns T 0 , T 1 are obtained by linearly interpolating the numbers, respectively, written in the respective lines and in the columns headed by T 0 and T 1 , respectively, of the table.

[0046] Advantageously, the core yarn and the winding yarn, one independently from the other, are obtained from a fibre selected between a natural fibre and a fibre artificial, or a combination of a natural fibre and an artificial fibre.

[0047] Advantageously, the natural fibre is selected from linen; hemp; ramie; bamboo; jute; cotton; wool; silk; a combination of the above.

[0048] Advantageously, the artificial fibre is selected from the group comprised of: Rayon, Tencel, Lyocel, milk, orange, nettle, kapok fibres, a combination of the above.

[0049] The elasticized yarn according to claim 17, wherein the core yarn and the winding yarn are, one independently from the other, selected from single-ply and multi-ply threads.

[0050] Advantageously, the core yarn is a two-ply thread of cashmere and silk respectively, while the winding yarn is of linen.

[0051] Advantageously, the core yarn is a two-ply thread of wool and viscose respectively, while the winding yarn is of hemp.

[0052] It falls within the scope of the invention also as an elasticized fabric at least in part made of the above-elasticised yarn.Brief description of the drawings

[0053] The method for making an elasticized fabric is described hereinafter with reference to the attached drawings, in which Figs. 1A and 1B diagrammatically illustrates the step of winding the winding yarn about the core yarn, so as to obtain the wound yarn; Fig. 2 diagrammatically shows a hollow spindle twisting machine to form the wound yarn in the process for manufacturing an elasticized fabric; Fig. 3 diagrammatically shows a wound yarn in an extended condition, as collected on a collecting bobbin; Fig.4 diagrammatically shows the yarn of Fig. 4, in a non-extended condition; Fig. 5 is a diagram showing the minimum and maximum values of the pulling force applied to the core yarn, plotted against the first linear mass density Nm c of the core yarn; Fig. 6 is a diagram showing the minimum number of turns per length unit of the wound yarn, plotted against the second linear mass density Nm w of the winding yarn. Description of preferred exemplary embodiments

[0054] With reference to Figs. 1A and 1B, in order to manufacture an elasticized fabric, the method according to the invention comprises a step of making a wound yarn by winding a winding yarn 40 having a second linear mass density Nm w and an initial twist direction "Z" (Fig. 1A) or "S" (Fig. 1B), about a core yarn 30 having a first linear mass density Nm c and an initial twist direction "Z" (Fig. 1A) or "S" (Fig. 1B), respectively, i.e., the same twist direction as winding yarn 40.

[0055] According to the present invention, and unlike the yarns commonly used to make elasticized yarns, core yarn 30 is a non-elastomeric yarn, or in any case a substantially inextensible yarn, i.e. a yarn having an ultimate elongation of 5% or lower.

[0056] Typically, the initial twist direction of winding yarn 40 is "Z", as well as the initial twist direction of core yarn 30, as normally available on market (Fig. 1A).

[0057] In order to carry out the step of winding winding yarn 40, a predetermined pulling force F is applied to core yarn 30, preferably in the way described more in detail hereinafter. Moreover, steps are carried out of conveying core yarn 30 and winding yarn 40 at speeds v 1 , v 2 , respectively, towards a wrapping space 35, where winding yarn 40 laterally, i.e. tangentially, reaches core yarn 30, a predetermined angle α being formed between an axis of core yarn 30 and an axis of winding yarn 40. Angle α is selected in such a way that a sequence of turns 45 is formed about core yarn 30 in which turns 45 are arranged at a pitch p with respect to each other, wherein pitch p is longer than diameter d of winding yarn 40, preferably longer than a predetermined number of times diameter d. This number of times is preferably set between 1 and 8, more preferably between 2 and 5. This way, free spaces 55 are left between turns 45 whose width depends on pitch p and diameter d of winding yarn 40.

[0058] Pulling force F applied to core yarn 30 is selected in such a way that core yarn 30 is not excessively stretched, i.e. in such a way that core yarn 30, due to and during the operation of winding, forms a sequence of ridges 31 that tends to protrude through free spaces 55 between turns 45 of winding yarn 40 already wound about core yarn 30.

[0059] Moreover, conveying speeds v 1 and v 2 are selected in such a way that, during the winding step, the twist direction of winding yarn 40 changes, turning from "Z" to "S" (Fig. 1A) or vice-versa (Fig. 1B), according to the initial twist direction of winding yarn 40 in use.

[0060] The method for making the elasticized fabric also comprises a step of forming the fabric from wound yarn 50. This can be a substantially conventional process of knitting or weaving, or the like.

[0061] A step is also provided of washing the yarn or the fabric, in the latter case an open-width washing step or a rope washing step, which is carried out during or before a step of dyeing the yarn or the fabric. The step of washing can be carried out both on wound yarn 50 and on fabric 60, the latter being typically the case of the fabrics manufactured by a process of weaving.

[0062] Fig. 3 diagrammatically shows wound yarn 50 as collected on a collecting bobbin. In wound yarn 50, yarns 30,40 forming the structure of wound yarn 50, i.e., core yarn 30 and winding yarn 40, are twisted in the opposite twist directions in wound yarn 50. Due to the washing, wound yarn 50 shrinks, as shown in Fig. 4, and ridges 31 of core yarn 30 are compressed between turns 45 of winding yarn 40. So, wound yarn 50 is brought from extended condition A of Fig. 3, in which a same piece of wound yarn 50 has a length L A , to non-extended condition B of Fig. 4, in which a same piece of wound yarn 50 has a length L B shorter than L A . Due to the opposite twist direction of core yarn 30 and winding yarn 40, shrunk wound yarn 50 opposite inner reaction forces arise between winding yarn 40 and core yarn 30. This causes an intrinsic elasticity, such that, upon stretching and then releasing a fabric containing wound yarn 50 (Fig. 3 and 4), , wound yarn 50 performs an elastic return. This way, the step of washing, carried out on both wound yarn 50 and on fabric 60, generates or increases an elasticity of wound yarn 50 incorporated in fabric 60 and, accordingly, generates or increases the elasticity of fabric 60.

[0063] The same applies to any elasticized yarn according to the third aspect of the invention, in which, i.a., core yarn 30 and winding yarn 40 are twisted with opposite twist directions in the wound yarn.

[0064] Apart from the limitation that core yarn 30 does not contain any elastomeric materials, which is the case, instead, in the yarns used for making conventional elasticized fabrics, core yarn 30 and winding yarn 40, independently from each other, can contain any textile material. However, core yarn 30 and winding yarn 40 can have the same composition.

[0065] In particular, core yarn 30 and winding yarn 40 can contain natural fibres such as hemp, ramie, bamboo, jute, cotton, wool, silk, etc., or combinations thereof.

[0066] As an alternative, core yarn 30 and winding yarn 40 can contain artificial fibres, such as Rayon, Tencel, Lyocel, milk fibres, orange fibres, nettle fibres, kapok fibres and so on, or combinations thereof.

[0067] The above materials are preferred, however, synthetic fibres can also be used in the invention, such as nylon, polyester, acrylic and other fibres, and combinations thereof. Combinations can also be used of natural material, artificial, synthetic materials, preferably, combinations containing natural and artificial materials.

[0068] In an exemplary embodiment, core yarn 30 and winding yarn 40, regardless of their combination and of their linear mass densities Nm c , Nm w , are wires twisted with the same initial twist direction "Z" or "S", with the above-mentioned advantages.

[0069] In some preferred exemplary embodiments, core yarn 30 and winding yarn 40 are selected, independently from each other, between a one-filament yarn and a multi-filament yarn. In an example thereof, core yarn 30 is a two-filament yarn, wherein one filament is made of cashmere and the other filament is made of silk, whereas winding yarn 40 is made of linen. In another example, core yarn 30 is a two-filament yarn, wherein one filament is made of wool and the other filament is made of Rayon, whereas winding yarn 40 is made of hemp.

[0070] In the present method, the pulling force applied to core yarn 30 is preferably higher than a predetermined minimum force value F 0 , so that core yarn 30 is stretched enough for winding yarn 40 to be easily wound about it, and to assure uniform features to the wound yarns obtained by the multiple winding units of a same winding machine.

[0071] Moreover, according to the invention, the pulling force applied to core yarn 30 is lower than a predetermined maximum force value F 1 that should not be exceeded in order not to lose the low-friction and high heat and moisture transfer properties of the fabrics, along with the pleasant and fresh touch feel provided to the users wearing garments made of such fabrics, and in order to obtain acceptable elastic properties of wound yarn 50, as the experience has shown.

[0072] Minimum and maximum values F 0 , F 1 of the pulling force depend on first linear mass density Nm c of core yarn 40, as tables 1 and 2 show. In the diagram of Fig. 5, minimum pulling force value F 0 and maximum pulling force value F 1 are plotted against first linear mass density Nm c of core yarn 40 as curves 71 and 72, respectively. Curves 71 and 72 are obtained by interpolating the values of tables 1 and 2, respectively.

[0073] According to the invention, in the present method, conveying speeds v 1 and v 2 are selected in such a way that, in the winding step, the number of turns formed by winding yarn 40 about core yarn 30 per length unit of wound yarn 50 is higher than a predetermined minimum number of turns T 0 , in order to make the stack of turns compact enough to create an elastic return force upon releasing a pulling force acting on it, and to avoid uneven winding conditions among the parallel winding units of a winding machine.

[0074] Moreover, regardless of the above, the number of turns formed by winding yarn 40 about core yarn 30 per length unit of wound yarn 50 is preferably lower than a predetermined maximum number of turns T 1 that should not be exceeded in order not to lose the low-friction and high heat and moisture transfer properties of the fabrics, along with the pleasant and fresh touch feel provided to the users wearing garments made of such fabrics, and in order to obtain acceptable elastic properties of wound yarn 50, as the experience has shown.

[0075] Minimum and maximum number of turns T 0 , T 1 depend on second linear mass density Nm w of winding yarn 40, as tables 3 and 4 show. In the diagram of Fig. 6, minimum number of turns T 0 and maximum number of turns T 1 are plotted against second linear mass density Nm w of winding yarn 40 as curves 81 and 82, respectively. Curves 81 and 82 are obtained by interpolating the values of tables 3 and 4, respectively.

[0076] As shown in Fig. 2, the steps of conveying core yarn 30 and covering yarn 40 are controlled by the speed by which wound yarn 50 is collected on collecting bobbin 51 of wound yarn 50, while, as a consequence, core yarn 30 and winding yarn 40 are drawn from respective spools, not shown and 41, respectively.

[0077] In an exemplary embodiment, the step of conveying core yarn 30 towards wrapping space 35 is carried out through a central hole 63 of a first cylindrical body 61 turning at a predetermined high speed about its own axis 63', i.e., core yarn 30 is conveyed along a substantially linear path. On the contrary, the step of conveying winding yarn 40 is carried out along the outer surface 62 of first cylindrical body 61, preferably along a guide arranged thereon. Preferably, first cylindrical body 61 is integrally and coaxially housed in a second hollow cylindrical body 64, cylindrical bodies 61,64 forming a conveying unit 60. Bobbin 41 of covering yarn 40 is fixed inside second cylindrical body 64, therefore covering yarn 40 is conveyed through a gap 65 between bobbin 41 and the outer surface of first cylindrical body 61.

[0078] In this exemplary embodiment and, in particular, if winding yarn 40 is a discontinuous yarn, wrapping space 35 is a space normally closed, i.e. a protected space, in order to limit the interaction of the involved material, in particular of winding yarn 40, with the surrounding air. In this case, as Fig. 2 still shows, wrapping space 35 is defined between the outlet end 69 of first cylindrical body 61, at which core 30 enters into wrapping space 35, and an orifice 66 preferably arranged on axis 63', through which wound yarn 50 leaves wrapping space 35 and is conveyed towards collecting bobbin 51. The protection of wrapping space 35 is provided by a preferably axisymmetric wall 67 that converges from the inner surface of second cylindrical hollow body 64 to orifice 66, thus forming a container, which is an outlet passageway of wound yarn 50 from wrapping space 35.

[0079] Fig. 4 is a diagram showing the predetermined minimum number of turns T 0 that must be wrapped per length unit of elastic core yarn 50, for each value of second linear mass density Nm w of covering yarn 40, as a curve 81. Curve 81 is obtained by interpolating the values of table 3.

[0080] The diagram of Fig. 6 also shows a curve 82 indicating, for each value of second linear mass density Nm w of covering yarn 40, the predetermined maximum number of turns T 1 wrapped per length unit of elastic core yarn 50 that should not be exceeded in order to obtain acceptable elastic properties of wound yarn 50, as the experience has shown. Curve 82 is obtained by interpolating the values of table 4.

Examples

Embodiment Construction

[0054]With reference to Figs. 1A and 1B, in order to manufacture an elasticized fabric, the method according to the invention comprises a step of making a wound yarn by winding a winding yarn 40 having a second linear mass density Nm w and an initial twist direction "Z" (Fig. 1A) or "S" (Fig. 1B), about a core yarn 30 having a first linear mass density Nm c and an initial twist direction "Z" (Fig. 1A) or "S" (Fig. 1B), respectively, i.e., the same twist direction as winding yarn 40.

[0055]According to the present invention, and unlike the yarns commonly used to make elasticized yarns, core yarn 30 is a non-elastomeric yarn, or in any case a substantially inextensible yarn, i.e. a yarn having an ultimate elongation of 5% or lower.

[0056]Typically, the initial twist direction of winding yarn 40 is "Z", as well as the initial twist direction of core yarn 30, as normally available on market (Fig. 1A).

[0057]In order to carry out the step of winding winding yarn 40, a predetermined pullin...

Claims

1. A method for making an elasticized fabric, wherein the steps are provided of: - forming a wound yarn, comprising the steps of: - prearranging a core yarn (30) having a first linear mass density Nmc; - prearranging a winding yarn (40) having a second linear mass density Nmw and twisted with an initial twist direction selected between "Z" and "S", wherein said core yarn (30) is twisted with an initial twist direction equal to said initial twist direction of said winding yarn (40); - applying a predetermined pulling force (F) to said core yarn (30); - conveying said core yarn (30) and said winding yarn (40) at respective conveying speeds (v1,v2) towards a collecting bobbin (51) of said wound yarn (50), wherein said step of conveying is carried out in such a way that said winding yarn (40) laterally attains a proximity of said core yarn (30) in a wrapping space (35); - winding said winding yarn (40) about said core yarn (30) in said wrapping space (35), in such a way that, in said winding step, said winding yarn (40) becomes twisted with a final twist direction opposite to said initial twist direction, i.e., with a final twist direction selected between "S" and "Z", respectively; - obtaining said wound yarn (50) on said collecting bobbin (51); - forming a fabric from said wound yarn (50) by a fabric-making process selected between a knitting process and a weaving process; wherein said method comprises a step of washing selected between a step of washing said fabric or / and a step of washing said wound yarn, characterized in that - said core yarn (30) is a non-elastomeric yarn; - said step of winding said winding yarn is carried out in such a way that said winding yarn (40) forms a sequence of turns (45) about said core yarn (30), said turns having a pitch (p) longer than a diameter (d) of said winding yarn (40), in such a way that free spaces (55) are left between said turns (45); - said pulling force (F) applied to said core yarn (30) is lower than a predetermined force value (F1) selected in such a way that said core yarn (30) forms a sequence of ridges (31) protruding between said free spaces (55), such that, by said washing step, said wound yarn (50) shrinks in such a way that said ridges (31) of said core yarn (30) are compressed between said turns (45) of said winding yarn (40) causing said wound yarn (50), which is incorporated in said fabric, to become elastic and, therefore, causing also said fabric to become elastic, wherein said conveying speeds (v1, v2) are selected in such a way that, in said winding step, a number of turns T, - higher than a predetermined minimum number of turns T0, and - lower than a predetermined maximum number of turns T1 of said winding yarn (40) is wound per length unit of said wound yarn (50), said minimum number of turns T0 and said maximum number of turns T1 depending on said second linear mass density Nmw, wherein, for each value of said second linear mass density Nmw indicated in a respective line of the following table NmwT0T1120502405003606001015010002020013003025014004030015005030016007040017009050018001206002000 , said minimum and maximum number of turns T0, T1 are the numbers written in said respective line and in the columns headed by T0 and T1 of said table, respectively.

2. The method according to claim 1, wherein said pulling force applied to said core yarn (30) is set between a predetermined minimum force value F0, and a predetermined maximum force value F1, said minimum force value and said maximum force value depending on a first linear mass density Nmc of said core yarn, wherein, for each first linear mass density value Nmc indicated in a respective line of the following table NmcF0F115070245653406010640205353043540333502307013090129120125 , said minimum and maximum force values F0, F1 are the force values expressed in grams written in said respective line and in the columns headed by F0 and F1, respectively, of said table, wherein, for values intermediate between two adjacent values of first linear mass density Nmc indicated in respective adjacent lines of the table, said minimum and maximum force values F0, F1 are obtained by linearly interpolating the force values, respectively, written in the respective lines and in the columns headed by F0 and F1 of said table.

3. The method according to claim 1, wherein for values intermediate between two adjacent values of said second linear mass density Nmw indicated in respective adjacent lines of the table, said minimum and maximum number of turns T0, T1 are obtained by linearly interpolating the numbers, respectively, written in the respective lines and in the columns headed by T0 and T1, respectively, of said table.

4. The method according to claim 1, wherein said step of washing comprises a step of open-width washing or rope washing said fabric in water, in particular, said step of washing is carried out in such conditions and during such a washing time that the fabric shrinks by 15% to 30%.

5. The method according to claim 1, wherein said core yarn (30) and said winding yarn (40), independently from each other, are made of a fibre selected between a natural fibre and an artificial fibre, or are made of a combination of a natural fibre and an artificial fibre.

6. The method according to claim 1, wherein said winding yarn (40) is a discontinuous yarn, and said wrapping space (35) is a protected space enclosed in a container (67).

7. The method according to claim 1, wherein said step of conveying comprises: - steps of causing said core yarn (30) and said winding yarn (40) to pass through a longitudinal recess (63) and along a side surface (62) of a cylindrical hollow body (61) turning at a predetermined speed, said longitudinal recess (63) having an inlet (68) and an outlet (69) for said core yarn (30); - a step of causing said core yarn (30) and said winding yarn (40) to pass through an orifice (66) facing said outlet (69) of said longitudinal recess (63) of said cylindrical hollow body (61) and arranged at a predetermined distance from said outlet (69), and wherein said wrapping space (35) is arranged between said outlet (69) and said orifice (66), in such a way that said container (67) has an opening at said orifice (66) and said core yarn (30) and said winding yarn (40) are caused to pass through said orifice in the form of said wound yarn (50).

8. A method for making an elasticized fabric, wherein the steps are provided of: - forming a wound yarn, comprising the steps of: - prearranging a core yarn (30) having a first linear mass density Nmc; - prearranging a winding yarn (40) having a second linear mass density Nmw; - applying a predetermined pulling force (F) to said core yarn (30); - conveying said core yarn (30) and said winding yarn (40) at respective conveying speeds (v1,v2) towards a collecting bobbin (51) of said wound yarn (50), wherein said step of conveying is carried out in such a way that said winding yarn (40) laterally attains a proximity of said core yarn (30) in a wrapping space (35); - winding said winding yarn (40) about said core yarn (30) in said wrapping space (35); - obtaining said wound yarn (50) on said collecting bobbin (51); - forming a fabric from said wound yarn (50) by a fabric-making process selected between a knitting process and a weaving process; wherein said method comprises a step of washing selected between a step of washing said fabric or / and a step of washing said wound yarn, characterized in that - said core yarn (30) is a non-elastomeric yarn; - said step of winding said winding yarn is carried out in such a way that - said winding yarn (40) forms a sequence of turns (45) about said core yarn (30), said turns having a pitch (p) longer than a diameter (d) of said winding yarn (40), in such a way that free spaces (55) are left between said turns (45); - in said wound yarn (50), said core yarn (30) and said winding yarn (40) are twisted with respective twist directions opposite to each other; - said pulling force (F) applied to said core yarn (30) is lower than a predetermined force value (F1) selected in such a way that said core yarn (30) forms a sequence of ridges (31) protruding between said free spaces (55), such that, by said washing step, said wound yarn (50) shrinks in such a way that said ridges (31) of said core yarn (30) are compressed between said turns (45) of said winding yarn (40) causing said wound yarn (50), which is incorporated in said fabric, to become elastic and, therefore, causing also said fabric to become elastic, wherein said conveying speeds (v1, v2) are selected in such a way that, in said winding step, a number of turns T, - higher than a predetermined minimum number of turns T0, and - lower than a predetermined maximum number of turns T1 of said winding yarn (40) is wound per length unit of said wound yarn (50), said minimum number of turns T0 and said maximum number of turns T1 depending on said second linear mass density Nmw, wherein, for each value of said second linear mass density Nmw indicated in a respective line of the following table NmwT0T1120502405003606001015010002020013003025014004030015005030016007040017009050018001206002000 , said minimum and maximum number of turns T0, T1 are the numbers written in said respective line and in the columns headed by T0 and T1 of said table, respectively.

9. An elasticized yarn, comprising: - a core yarn (30) having a first linear mass density Nmc; - a winding yarn (40) having a second linear mass density Nmw; wherein - said core yarn (30) is a non-elastomeric yarn; - said winding yarn (40) forms a sequence of turns (45) about said core yarn (30), said turns having a pitch (p) longer than a diameter (d) of said winding yarn (40), in such a way that free spaces (55) are left between said turns (45); - in said wound yarn (50), said core yarn (30) and said winding yarn (40) are twisted with respective twist directions opposite to each other; - said winding yarn (40) forms a number of turns T - higher than a predetermined minimum number of turns T0, and - lower than a predetermined maximum number of turns T1 of said winding wire (40) per length unit of said wound yarn (50), said minimum number of turns and maximum number of turns depending on said second linear mass density Nm, wherein, for each value of said second linear mass density Nm indicated in a respective line of the table below NmT0T1120502405003606001015010002020013003025014004030015005030016007040017009050018001206002000 , said numbers of minimum and maximum turns T0, T1 are the numbers written in said respective line and in the columns respectively headed T0 and T1 of said table.

10. The elasticized yarn according to claim 9, wherein said core yarn (30) and said winding yarn (40), independently from each other, are obtained from a fibre selected among a natural fibre, an artificial fibre, and a combination of a natural fibre and an artificial fibre.

11. The elasticized yarn according to claim 10, wherein said natural fibre is selected from the group comprised of linen; hemp; ramie; bamboo; jute; cotton; wool; silk; a combination of the above.

12. The elasticized yarn according to claim 10, wherein said artificial fibre is selected from the group comprised of: Rayon, Tencel, Lyocel, milk, orange, nettle, kapok fibres, a combination of the above.

13. The elasticized yarn according to claim 9, wherein said core yarn (30) is a two-filament yarn selected form the group comprised of: - a two-filament yarn wherein one filament is made of cashmere and the other filament is made of silk; - a two-filament yarn wherein one filament is made of wool and the other filament is made of Rayon; while said winding yarn (40) is made of linen or of hemp, respectively.

14. The elasticized yarn according to claim 9, wherein said core yarn (30) and said winding yarn (40), independently from each other, are obtained from a synthetic fibre, in particular from a fibre selected from the group comprised of: a nylon fibre; a polyester fibre; an acrylic fibre; a combination thereof.

15. An elasticized fabric including the elasticized wound yarn according to claims 9 to 14.