JP5222492B2 - Core-sheath composite spun yarn and fabric - Google Patents

Description

  The present invention relates to a core-sheath composite spun yarn excellent in yarn anti-pilling property and further excellent in yarn anti-pilling property and leveling property, and a fabric using the core-sheath structure composite spun yarn.

  Conventionally, many researches and developments have been made on long and short composite yarns of filaments and short fibers. Among them, as long and short composite yarns imparted with stretch properties, for example, from short fibers having polyurethane elastic yarn as a core. Composite yarn with a sheath (core spun yarn) (Patent Documents 1, 2, etc.) and a composite yarn consisting of a polyester-based long fiber consisting of a polytrimethylene terephthalate layer and a polyethylene terephthalate layer and a sheath consisting of short fibers (patent Literature 3 etc.).

However, such a long and short composite yarn lacks the entanglement and restraint properties of the core component (filament yarn) and the sheath component (short fiber) due to its yarn structure, and a frictional force in the direction parallel to the yarn is generated. In such a case, there is a problem that the short fibers constituting the sheath are displaced and easily become irregular, and fluff is likely to occur. In addition, since this problem becomes apparent particularly when the number of twists is small, it is necessary to set the twist of the long and short composite yarns higher than usual, and the convergence between the sheath component and the core component becomes strong, and a fabric is obtained. In some cases, the soft texture was lost.
Japanese Patent Laid-Open No. 10-077538 JP 2002-155442 A JP 2000-45141 A

  The present invention has been made in view of the circumstances as described above, and the problem to be solved is a core-sheath structure composite spun yarn excellent in anti-pilling property and soft feeling, and the core-sheath structure composite spun yarn. It is to provide a fabric with a soft texture that is less likely to cause fluff.

  In particular, a core-sheath structure composite spun yarn having excellent stretch properties with excellent anti-pilling property and soft feeling and good elongation and recovery rate, and fluff using the core-sheath structure composite spun yarn It is an object of the present invention to provide a fabric that is difficult to generate, has a soft texture, and has a good elongation and recovery rate.

  As a result of diligent research to solve the above-mentioned problems, the present inventors made the core a twisted yarn of two or more filament yarns, aligned the twisted yarn with short fibers, and what is the twist direction of the twisted yarn? By twisting in the opposite twist direction, the short fiber is caught and restrained between two or more filament yarns of the twisted yarn, and it is found that the occurrence of fluff due to the short fiber shift can be suppressed. The present invention has been completed by further research based on the knowledge.

That is, the present invention
(1) A core-sheath composite spun yarn, characterized in that the core is a twisted yarn of at least two filament yarns and the sheath is made of short fibers;
(2) The two or more filament yarns are twisted in a twist direction opposite to the twist direction of the two or more filament yarns after the filaments are aligned with the short fibers. 1) The core-sheath structure composite spun yarn as described above,
(3) The core-sheath structure composite spun yarn according to (1) or (2) above, wherein the core is a stretch core-sheath structure composite spun yarn composed of a polyester composite long fiber yarn and a polyurethane elastic yarn. ,
(4) The stretchable core-sheath structure according to (3), wherein the polyester-based composite long fiber yarn is a composite long fiber comprising a polyester layer mainly composed of polytrimethylene terephthalate and a polyester layer mainly composed of polyethylene terephthalate. Composite spun yarn,
(5) The stretchable core-sheath structure composite spun yarn according to (3) or (4), wherein the sheath is made of cellulose short fibers, and the content of the cellulose short fibers is 60% or more by weight.
(6) A stretch core-sheath structure composite spun yarn according to any one of the above (3) to (5), which is a spun yarn of 5 to 30 in English cotton count,
(7) The core-sheath structure composite spun yarn according to any one of the above (1) to (6), wherein the twist coefficient K of the core-sheath structure composite spun yarn is in the range of 3.6 to 5.0, and ( 8) A fabric comprising at least a portion of the core-sheath composite spun yarn according to any one of (1) to (7) above.

Hereinafter, the present invention will be described with reference to preferred embodiments thereof.
The core-sheath structure composite spun yarn of the present invention (hereinafter also simply referred to as “composite spun yarn”) is a composite spun yarn in which the core is a twisted yarn of at least two filament yarns and the sheath is made of short fibers. Preferably, a composite of two or more filament yarns twisted in a twist direction opposite to the twist direction of the two or more filament yarns after aligning two or more filament yarns with a short fiber. It is spun yarn.

  Conventionally, long and short composite yarns have been developed as a fiber material that can simultaneously exhibit the natural feel and appearance that spun yarn provides, and the favorable waist and rebound characteristics that long fibers provide. However, a composite spun yarn having a core-sheath structure using a twisted yarn of two or more filament yarns as a core has not been proposed. The core-sheath structure composite spun yarn of the present invention is a conventional core-sheath composite spun yarn having a single filament yarn (long fiber) as a core because the core is a twisted yarn of two or more filament yarns. A composite spun yarn having a core-sheath structure satisfying the required characteristics that has been difficult to achieve can be obtained, and the short fiber of the sheath component is wound and restrained between two or more filament yarns of the core component, thereby causing fluff Therefore, a composite spun yarn excellent in anti-pilling property can be realized. In addition, since the number of twists can be set relatively low, a composite spun yarn excellent in soft feeling can be realized. Furthermore, since the core-sheath structure composite spun yarn of the present invention is a twisted yarn of two or more filament yarns, the friction force between the core component and the sheath component (short fiber) when subjected to external force is increased. There is also an advantage that a spun yarn having a high level of uniformity is obtained in which the sheath component (short fiber) is hardly displaced in the parallel direction (axial direction).

  Also in the core-sheath structure composite spun yarn of the present invention, the filament yarn as the core component is not particularly limited as long as it has the basic characteristics of imparting waist and resilience to the target composite spun yarn. Filament yarn can be used. For example, synthetic fibers such as polyester fiber, polyamide fiber, polyurethane fiber, polypropylene fiber, acrylic fiber, water (hot water) insoluble polyvinyl alcohol fiber, polyvinylidene chloride fiber; semi-synthetic fiber such as acetate fiber; rayon, cupra, etc. A single filament yarn composed of one type of fiber selected from the above-mentioned recycled fibers, and a mixed filament yarn composed of two or more types of fibers.

  In the present invention, the composite properties of two or more filament yarns (usually 2 to 3) are suitable for the intended composite spun yarn application and the fabric application using the composite spun yarn. Select more than one filament yarn and twist them together.

  The thickness of each filament yarn in the two or more filament yarns is not particularly limited, but when the composite spun yarn is for clothing, it is generally about 20 to 150 dtx, and more than two or more filament yarns The difference in the yarn thickness between the two yarns is preferably 60 dtx or less from the viewpoint of handling when combined and handling with a spinning machine. Further, twisting of two or more filament yarns may be performed by ordinary twisting means such as a ring spinning machine or a double twister.

  The twist direction of two or more filament yarns may be either the S direction or the Z direction, but is generally the S direction. In addition, the number of twists (number of times per inch) varies depending on the type of filament yarn to be twisted. However, if the number of twists is too small, peeling between filament yarns to be twisted is likely to occur, and handling in subsequent processes is difficult. In addition, if the number of twists is too large, the degree of entanglement between the twisted yarn and the short fibers constituting the sheath will be low in the post-process, and the core and sheath will tend to shift more and fluff tends to occur. It becomes. Therefore, the number of twists of two or more filament yarns is generally about 5 to 20 times (preferably 8 to 16 times).

  Specific examples of the twisted yarn used as the core component include, for example, (a) a polyester-based composite continuous fiber yarn and a polyurethane for realizing a composite spun yarn having excellent stretch properties in which both the elongation rate and the recovery rate are good. (B) Synthetic yarn consisting of polyester long fiber and polyurethane elastic yarn to realize a composite spun yarn having stretch properties with excellent fabric tear strength, (c) Antistatic Examples thereof include a twisted yarn composed of a polyester continuous fiber with antistatic function and a polyurethane elastic yarn for realizing a composite spun yarn having a function and stretchability.

  In addition, the weight ratio of the two or more filament yarns constituting the core twisted yarn may be adjusted according to the intended use of the composite spun yarn. The yarn is appropriately adjusted within a range of at least 5% by weight or more of the total twisted yarn. For example, in the case of two filament yarns, the weight ratio is adjusted within a range of 5/95 to 95/5.

  On the other hand, the short fiber which is a sheath component of the core-sheath composite spun yarn of the present invention can be appropriately selected according to the use of the composite spun yarn. For example, natural cellulosic fibers such as cotton and hemp; regenerated cellulose fibers such as cotton, hemp, cupra, viscose rayon, polynosic rayon; polyester fibers such as acetate, polyethylene terephthalate, polybutylene terephthalate, polytrimethylene terephthalate, Various artificial fibers such as nylon and acrylic; various short fibers such as animal hair fibers such as wool can be used. Moreover, the cross-sectional shape of the short fiber is not particularly limited, and may be a round shape, a modified shape such as a polygonal shape, an H shape, or a hollow shape. Although the fineness of the short fiber is not particularly limited, 3.0 to 5.8 micronea is preferable in consideration of spinnability. The fiber length is preferably a fiber length corresponding to various spinning methods.

  In the core-sheath composite spun yarn of the present invention, a twisted yarn of two or more filament yarns is applied with a predetermined tension by a spinning machine, supplied from the front roller of the spinning machine, and the surroundings are made of the above short fibers. Obtained by covering and spinning. It is important that the twist added to the core-sheath composite spun yarn by the fine spinning machine is a twist in the direction opposite to the twist direction of the two or more filament yarns. That is, when the twist direction of two or more filament yarns is the S direction, twist is applied in the Z direction, and when the twist direction of two or more filament yarns is the Z direction, Add twist. The thickness of the core-sheath composite spun yarn is appropriately determined according to the use of the composite spun yarn and the use of the fabric using the composite spun yarn.

  The number of twists (the number of actual twists) is a range in which the twist coefficient K is 3.6 to 5.0, defined by the following formula (1), in relation to the thickness of the spun yarn (English cotton count) Is the number of twists.

  By making the direction of twist applied to the spun yarn opposite to the direction of twisted yarn, the twisted yarn is untwisted and untwisted when twisted immediately after coming out of the front roller in the spinning machine. A short fiber fleece is sandwiched between the portions, and twist is further added to obtain a core-sheath composite spun yarn. Therefore, the degree of entanglement between the twisted yarn constituting the core and the short fiber constituting the sheath is increased, and the composite spun yarn is less likely to be displaced from the core and the sheath and less likely to generate fluff. When the twist coefficient K is less than 3.6, the core and the sheath tend to be displaced when resistance is applied to the yarn, and when it exceeds 5.0, the texture of the product tends to be firm. Become.

  In the core-sheath structure composite spun yarn of the present invention, the content of short fibers constituting the sheath in the composite spun yarn is 60% or more by weight, preferably 70-97%. When the content ratio of the short fibers constituting the sheath exceeds 97% by weight, the sheath thread winding structure has a remarkable and beautiful appearance, but the characteristics of the core component (long fibers) tend to decrease, and the weight ratio If it is less than 60%, the thread processability is lowered, and the winding form of the sheath yarn is also loosened, so that the passability in the knitting process or weaving process when obtaining the fabric tends to be lowered.

  The present invention is particularly suitable for improvement of stretchable long and short composite yarns. As described above, a core using a twisted yarn comprising a polyester composite long fiber yarn and a polyurethane elastic yarn as a core, and using a short fiber as a sheath. By obtaining a sheath-structure composite spun yarn, it is possible to realize an excellent stretch composite spun yarn having both good elongation and recovery. Hereinafter, the preferable aspect of this stretch core-sheath structure composite spun yarn is demonstrated.

  The polyester composite long fiber yarn, which is one filament yarn of the twisted yarn that becomes the core, is a polyester composite of a side-by-side type composite or an eccentric seascore type composite containing at least one polyester layer mainly composed of polytrimethylene terephthalate. Long fiber yarn is preferable, more preferably, a polyester-based composite long fiber yarn in which a polyester layer mainly composed of polyethylene terephthalate and a polyester layer mainly composed of polytrimethylene terephthalate are combined in a side-by-side type or an eccentric seascore type. Particularly preferred is a polyester-based composite long fiber yarn in which a polyester layer mainly composed of polyethylene terephthalate and a polyester layer mainly composed of polytrimethylene terephthalate are combined in a side-by-side manner.

  The polyester layer mainly composed of polyethylene terephthalate is an ester polymer layer mainly composed of ethylene terephthalate units, and a copolymer component capable of forming an ester bond other than ethylene terephthalate units in a proportion of 20 mol% or less. It may be included. Examples of the copolymerizable compound include dicarboxylic acids such as isophthalic acid, sebacic acid, azelaic acid, dimer acid, adipic acid, oxalic acid and decanedicarboxylic acid, hydroxycarboxylic acids such as p-hydroxybenzoic acid and ε-caprolactone, Examples include diols such as triethylene glycol, polyethylene glycol, propanediol, butanediol, pentanediol, hydroquinone, and bisphenol A. Further, if necessary, titanium dioxide serving as a matting agent, fine particles of silica or alumina as a lubricant, hindered phenol derivatives, coloring pigments or the like as an antioxidant may be added.

  The polyester layer mainly composed of polytrimethylene terephthalate is an ester polymer having a trimethylene terephthalate unit as a main repeating unit (that is, a polyester obtained by using terephthalic acid as a main acid component and 1,3 propanediol as a main glycol component). It is a layer and the copolymer component which can form other ester bonds other than a trimethylene terephthalate unit may be contained in the ratio of 20 mol% or less. Examples of copolymerizable compounds include dicarboxylic acids such as isophthalic acid, succinic acid, cyclohexanedicarboxylic acid, adipic acid, dimer acid, sebacic acid, and 5-sodium sulfoisophthalic acid, ethylene glycol, diethylene glycol, butanediol, and neopentyl glycol. And diols such as cyclohexanedimethanol, polyethylene glycol, and polypropylene glycol. Further, if necessary, titanium dioxide serving as a matting agent, fine particles of silica or alumina as a lubricant, hindered phenol derivatives, coloring pigments or the like as an antioxidant may be added.

  In the case of a side-by-side type composite, the single yarn cross-sectional shape may be a round cross-section, but is preferably a deformed cross-sectional shape. Examples of the deformed cross-sectional shape include a non-circular shape such as an eyebrow shape and a snowman shape, and a deformed circular shape such as an ellipse. In the case of an eyebrows-shaped or snowman-shaped cross-sectional shape, a complex shape in which approximately round polymer layers are connected is taken.

  The weight ratio of the polyester layer mainly composed of polyethylene terephthalate / the polyester layer mainly composed of polytrimethylene terephthalate in the polyester composite continuous fiber yarn is preferably in the range of 30/70 to 70/30. The single yarn fineness is preferably about 44 to 145 dtx.

  Such polyester-based composite continuous fiber yarn has latent crimpability, and therefore has stretchability (rubber elasticity), and in particular, has a recovery rate, chemical resistance, long-term durability, and dimensional stability compared to polyurethane-based elastic yarn. It is superior compared.

  On the other hand, the polyurethane-based elastic yarn that is the other filament yarn of the twisted yarn is made of a polyurethane-based elastic material such as polyether-based polyurethane and polyester-based polyurethane, and is obtained by a normal spinning means. The length is preferably about 44 to 145 dtx. Polyurethane elastic yarns have very good extensibility, but are inferior in chemical resistance, long-term durability, and dimensional stability compared to polyester composite long fiber yarns.

  A twisted yarn composed of a polyester-based composite long fiber yarn and a polyurethane-based elastic yarn has a twist number (number of times per inch) of 5-20 times in a state where the polyester-based composite long fiber yarn and the polyurethane-based elastic yarn are stretched 3 to 5 times. It is appropriate to twist them together (preferably 8 to 16 times). The twist direction is usually the S direction. If the number of twists is 5 to 20, the slippage between the polyester-based composite long fiber yarn and the polyurethane-based elastic yarn can be prevented at a high level, and the twisted yarn constituting the core in the subsequent step (spinning step) The entanglement degree of the short fibers constituting the sheath becomes a preferable state, and a spun yarn excellent in soft feeling can be obtained.

  The weight ratio of the polyester-based composite long fiber yarn / polyurethane-based elastic yarn in the twisted yarn is preferably 70/30 to 95/5, more preferably from the viewpoint of the elongation rate and the recovery rate in the case of a fabric. Is 80/20 to 90/10.

  The resultant twisted yarn is spun by applying a tension of 1.1 times or more with a spinning machine, supplying it from the front roller of the spinning machine, covering the periphery with short fibers. At this time, the twisting direction applied to the spun yarn is set to be opposite to the twisting direction of the combined yarn of the polyester-based composite long fiber yarn and the polyurethane-based elastic yarn (usually, the Z direction). Both are excellent, and an excellent stretch-sheathed core-sheath composite spun yarn having both good elongation and recovery can be realized.

  When the tension applied by the spinning machine to the combined twisted yarn of polyester-based composite long fiber yarn and polyurethane elastic yarn constituting the core is less than 1.1 times, the polyester-based composite long fiber yarn and polyurethane elastic yarn are peeled off. In such a state, there is a risk of being supplied to the front roller of the spinning machine, and if the supply to the front roller in such a peeled state is made, it will cause deterioration of the covering state and dyeing unevenness, and elongation as a fabric This is not preferable because it also affects the rate and recovery rate. If the tension applied by the spinning machine is too high, the load on the drafting section of the spinning machine becomes large, and parts are consumed, resulting in poor quality. Therefore, the tension is 1.2 times or less. preferable.

  As described above, in the core-sheath structure composite spun yarn of the present invention, the short fibers constituting the sheath are not particularly limited. However, the stretch core-sheath structure composite spun yarn has both an elongation rate and a recovery rate. It has good stretch properties and is suitable for clothing (especially jeans). Therefore, the short fibers constituting the sheath are natural cellulosic fibers such as cotton and hemp, hemp, cupra and viscose rayon. Cellulose short fibers such as regenerated cellulose fibers such as polynosic rayon are preferably used.

  In addition, as described above, the content of the short fiber constituting the sheath in the composite spun yarn of the present invention is such that moderate yarn unevenness (expressing characteristics of the sheath component (short fiber)) and knitting when obtaining a fabric From the viewpoint of operability in the process and weaving process, the weight ratio is 60% or more (preferably 70 to 97%), but in the case of the stretch core / sheath structure composite spun yarn, the elongation rate and the recovery rate are points. Therefore, the content of the cellulose short fibers in the composite spun yarn is more preferably 70 to 90% by weight.

  The thickness of the stretchable core-sheath composite spun yarn is usually 5-30 in English cotton count, preferably 7-30, more preferably 8-20. In addition, the number of twists (the number of actual twists) of the stretchable core-sheath composite spun yarn basically has the twist coefficient K defined by the above formula (1) of 3.6 to 5. The number of twists is in the range of 0, but is preferably the number of twists in which the twist coefficient K defined by the formula (1) is in the range of 4.0 to 4.6.

  The fabric of the present invention is a fabric using at least part of the core-sheath composite spun yarn of the present invention. The “fabric” as used in the present invention is a general term for a sheet-like material composed of fibers, and is a concept including not only a woven fabric but also a knitted fabric and a non-woven fabric. The fabric may be composed of the core-sheath structure composite spun yarn of the present invention alone or may be composed of the core-sheath structure composite spun yarn of the present invention and another yarn. A stretch-sheathed sheath-synthetic composite spun yarn having a polyester composite long fiber yarn and a polyurethane elastic yarn as a core is most suitable for fabrics, especially for fabrics for clothing.

  Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples. The scope of the present invention is not limited to the following examples.

In addition, the physical property evaluation of the textile fabric (fabric) obtained by the Example and the comparative example was performed with the following method.
1. Width before washing, weight, vertical shrinkage and horizontal shrinkage JIS L 1042 F-2T method (old JIS standard)

2. Vertical tension, horizontal tension, vertical tear, horizontal tear JIS L 1096 Strip method (after washing)

3. Elongation rate (after 60 seconds), recovery rate (after 1 hour)
JIS L 1096 constant load method (after washing)

4). Anti-pilling properties Composite spun yarns (long and short composite fibers) are knit and tested in accordance with JIS L 1076 A method (ICI type)

Example 1
As a polyester-based composite long fiber yarn, a polytrimethylene terephthalate layer / polyethylene terephthalate layer = 50/50 side-by-side type composite fiber (56 dtx 24 filament, T-400 manufactured by Toray Industries, Inc.) is prepared, and as a polyurethane-based elastic yarn, A spandex (LYCRA, T127C, 44 dtx) manufactured by Operontex was prepared. Moreover, a short fiber roving made of 100% cotton (spun gelen 20.0 g / 30 yd) was prepared as a cellulose-based short fiber.
First, using a blender 608 made by Murata Manufacturing Co., Ltd., the draft of spandex was drafted 3.5 times and the side-by-side type composite fiber (T-400) of polytrimethylene terephthalate layer / polyethylene terephthalate layer was aligned and combined. Using a double twister, a twist of 9.5 turns / inch was added in the S direction to make a composite twisted yarn.
This composite twisted yarn is supplied to the front roller part in the spinning process with a 1.19 times tension, and 100% cotton short fiber roast (fineness: 4.8 micronaire) is supplied from the back roller to the front roller. In the Z direction, twisting was applied at a twisting coefficient of K = 4.5 to produce a stretch core-sheath structure composite spun yarn with 10th cotton count.
The resulting stretchable core-sheath composite spun yarn was used as a weft, and a woven fabric was produced with a 3 / 1R structure having a weft density of 58.
The characteristics of the woven fabric are as shown in Table 1. The fabric had excellent anti-pilling properties (hard to generate fuzz), was excellent in softness, and had good elongation and recovery.

(Comparative Example 1)
Only a side-by-side type composite fiber (300 dtx, T-400 manufactured by Toray Industries, Inc.) of a polytrimethylene terephthalate layer / polyethylene terephthalate layer is used for the core, and a 100% cotton short fiber roving (spun gelen 20.0 g / s) 30yd), a polytrimethylene terephthalate layer / polyethylene terephthalate layer side-by-side type composite fiber (T-400) is supplied to the front roller part in the spinning process with a 1.19 times tension applied, and 100% cotton Short fiber coarse yarn is fed from the back roller to the front roller and twisted in the Z direction with a twist coefficient of K = 4.5 to produce 10th stretchable core-sheath composite spun yarn with English cotton count did.
The resulting stretchable core-sheath composite spun yarn was used as a weft, and a woven fabric was produced with a 3 / 1R structure having a weft density of 58.
The characteristics of the woven fabric are as shown in Table 1. Fluff is easily generated, and the recovery rate is good, but the elongation rate is inferior.

(Comparative Example 2)
A front roller in the spinning process using only spandex (LYCRA, T127C, 44dtx) manufactured by OperonTex as the core and 100% cotton short fiber roving (spun gelen 20.0 g / 30 yd) as the sheath 3.5 times draft is added to the part and supplied, 100% cotton short fiber roving is supplied from the back roller to the front roller, twisted in the Z direction with a twist coefficient K = 4.5, A 10th stretchy core / sheath structure composite spun yarn was manufactured using an English cotton count.
The resulting stretchable core-sheath composite spun yarn was used as a weft, and a woven fabric was produced with a 3 / 1R structure having a weft density of 58.
The characteristics of the woven fabric are as shown in Table 1. It was easy to generate fluff, and the elongation rate was good but the recovery rate was poor.

Since the core-sheath structure composite spun yarn of the present invention is excellent in anti-pilling property and soft feeling, it is possible to provide a fabric with a soft texture in which fluff is hardly generated.
In particular, the stretch core-sheath structure composite spun yarn using a polyester composite long fiber yarn and a polyurethane elastic yarn as the core is superior in yarn uniformity, anti-pilling property and soft feeling. In addition, it has excellent stretchability with good elongation and recovery rate, and also has excellent long-term durability. Therefore, the fabric obtained from the stretchable core-sheath composite spun yarn does not generate fuzz, and has a well-balanced elongation and recovery rate, so that it is possible to provide a clothing product that is comfortable to wear and wear. It becomes possible.

Claims (7)

Core Ri is Do from a folded and twisted yarn of the polyester composite long fiber yarn and a polyurethane-based elastic yarn, characterized in that the sheath is composed of short fibers, stretch-sheath structure composite yarn. After the polyester composite long fiber yarn and the polyurethane elastic yarn are aligned with the short fiber, the polyester composite long fiber yarn and the polyurethane elastic yarn are twisted in the direction opposite to the twist direction. The stretch core-sheath structure composite spun yarn according to claim 1, which is twisted in the direction. The stretchable core-sheath structure composite spinning according to claim 1 or 2 , wherein the polyester composite long fiber yarn is a composite long fiber comprising a polyester layer mainly composed of polytrimethylene terephthalate and a polyester layer mainly composed of polyethylene terephthalate. yarn. The stretch core-sheath structure composite spun yarn according to any one of claims 1 to 3 , wherein the sheath comprises cellulose short fibers, and the content of the cellulose short fibers is 60% or more by weight. The stretchable core-sheath composite spun yarn according to any one of claims 1 to 4 , which is a spun yarn of British cotton count and 5th to 30th count. The stretch-sheath structure composite yarn of twist coefficient K is in the range of 3.6 to 5.0, stretch core-sheath structure composite spun yarn of any one of claims 1-5. A fabric comprising at least part of the stretchable core-sheath composite spun yarn according to any one of claims 1 to 6 .