JP2007204878A - Composite yarn composed of filament and staple fiber and cloth made thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hollow composite yarn composed of filaments and staple fibers and having excellent water-absorption/antipilling property and remarkably light weight. <P>SOLUTION: The yarn is an essentially non-twisted composite yarn composed of filaments and staple fibers and containing hollow filaments at the core part and staple fibers of synthetic fiber/semisynthetic fiber and/or natural fiber at the sheath part. The hollow filament of the core part accounts for 15-60 wt.% of the whole spun yarn, the staple fiber of the sheath part accounts for 40-85 wt.% of the whole spun yarn and the hollow retention ratio of the composite yarn composed of filaments and staple fibers defined by the following formula is ≥80%. Hollow retention ratio (%)=[(hollowness of hollow filament before spinning)-(hollowness of hollow filament after spinning)]/(hollowness of hollow filament before spinning)×100. A cloth having texture with excellent springiness and stiffness can be produced by using the composite yarn composed of filaments and staple fibers. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a long / short composite yarn characterized by having a hollow filament in a core portion, short fibers in a sheath portion and being substantially untwisted, and a fabric using the same.

  Conventionally, many researches and developments have been conducted on long and short composite yarns consisting of filaments and short fibers. Among them, a number of long and short composite yarns for clothing with the characteristics of weight reduction and elasticity are proposed, produced, Sold.

  In addition, in order to form a hollow portion in order to give water-absorbing and lightweight feeling in long and short composite yarns, a fabric is once manufactured with a core-sheath composite fiber, and chemical processing is performed after processing the fabric etc. In order to obtain long and short composite yarns and fabrics made of fibers having a hollow part by eluting the core part, a proposal has been made. This is a means for avoiding the problem that the hollow portion is broken due to twisting, a roller nip, or the like in the spinning process when combining the lengths.

  However, at the same time, in order to obtain yarns and fabrics having these functions, it is necessary to modify the fiber itself, and it is necessary to use a special polymer in the production of the raw fiber. In other words, in the production of raw silk, the difficulty of spinning increases, the productivity decreases, it becomes necessary to carefully clean up when changing the type, etc., and in the next step in spinning etc. There is a problem that you have to worry about mixing. In addition, long and short composite yarns of filaments and short fibers lack the entanglement property and restraint property of the core component and the sheath component, so-called nude yarn is generated in which the sheath component and the core component are separated, and when passing through the subsequent knitting and knitting process There was a problem such as a decrease in quality such as generation of a nep due to friction.

  Therefore, in order to prevent the above-described problems, the conventional long and short composite yarns set the twist of the spun yarn to be higher than usual to strongly restrain the filaments of the core component and the short fibers of the sheath component. However, according to such a method, since the convergence of the short fiber component is strong, it is difficult to obtain a soft texture, and when the hollow part is used for the core part, the hollow part may be crushed. .

  In order to solve these problems, Japanese Patent Application Laid-Open No. 11-323688 (Patent Document 1) discloses that the core yarn has a cross-sectional shape of the fiber and a cross-sectional rigidity in order to keep the middle yarn hollow during the process. Thus, long and short composite yarns that maintain a hollow state after passing through the process have been proposed. However, at the same time, since the rigidity of the fiber itself is increased, there is a drawback that the texture of the fabric is roughly cured.

  Japanese Patent Application Laid-Open No. 7-278982 (Patent Document 2) discloses a method for solving a whitening phenomenon in a long and short composite yarn composed of a hollow filament and a short fiber, which is caused by fibrillation due to cracks, cracks, and repeated wear of the hollow fiber. The hollow fiber yarn and the short fiber bundle having a hollow rate of 10 to 40% and a boiling water shrinkage rate of 8% or more are used, and the mixing weight ratio is set to core / sheath ≦ 1.5, and the content of boiling water treatment after yarn formation is described. .

  However, twisting causes these problems, and in order to control the boiling water shrinkage rate of the filament and to suppress the occurrence of nude yarn, be sure to use boiling water treatment (perhaps the twisting that is usually performed in spinning). Since it was necessary to pay attention to the manufacturing from time to time, it was difficult to perform the check easily.

Japanese Patent Application Laid-Open No. 11-61558 (Patent Document 3) uses a polyester yarn having a hollow ratio of 10 to 40% for the core and a polyester short fiber having a denier of 0.3 denier or less for the sheath and is lightweight and firm.・ Proposals have been proposed that have features such as stiffness and are intended to provide comfort when worn as clothing. However, the short fibers and long fibers of the sheath use a modified polymer, which is melted by post-processing to remove the core component and hollow, requiring post-processing, and the fibers used must also be modified Therefore, it takes time and effort in manufacturing. Similarly, in JP-A-6-49730 (Patent Document 4), a sheath part having a C-shaped horizontal cross-sectional shape in the core and an FY yarn made of a core component made of a melting / decomposing and removing component are used. The core yarn using cotton as the sheath is made into a woven or knitted fabric, and the woven or knitted fabric is processed to remove the melting / decomposing / removing component to obtain a fabric having quick drying properties, which also requires post-processing. In addition, since a modified polymer is also required for the fibers used, it takes time to manufacture. Also, Japanese Patent Application Laid-Open No. 2003-55848 (Patent Document 5) discloses a long and short composite having anti-pill properties. Although it has been proposed to use a short fiber using a modified polymer as a sheath component to obtain a yarn, because it has a modified polymer and is a hollow fiber, there is a delicate aspect in passing through the process, Productivity was lacking.
JP-A-11-323688 JP-A-7-278982 JP-A-11-61558 JP-A-6-49730 JP 2003-55848 A

Therefore, the present invention provides a hollow fabric that has an excellent water absorption and anti-pill property, is excellent in light weight, and has an unprecedented sharpness that has not been obtained by the conventional technology as described above. It is an object of the present invention to provide a mold long / short composite yarn and a fabric using the same.

In order to solve the above-described problems, the present invention has the following configuration. That is,
(1) A long / short composite yarn characterized by having a hollow filament in a core portion and short fibers in a sheath portion and being substantially untwisted.

  (2) The hollow filament at the core occupies 15 to 60% by weight of the entire spun yarn, and the short fibers at the sheath occupy 40 to 85% by weight of the entire spun yarn. Long and short composite yarn.

  (3) A long / short composite yarn having a hollow retention rate of 80% or more according to the following formula.

(Hollow rate of hollow filament before spinning−hollow rate of hollow filament after spinning) / Hollow rate of hollow filament before spinning × 100 = Hollow retention rate (%)
(4) A fabric using the long and short composite yarn according to any one of (1) to (3), and having a hollow retention of 80% or more according to the following formula.
(Hollow rate of hollow filament before woven or knitted-hollow rate of hollow filament after woven or knitted) / Hollow rate of hollow filament before woven or knitted × 100 = Hollow retention rate (%)

  According to the present invention, it is possible to provide a long / short composite yarn capable of obtaining a fabric having excellent water absorption and anti-pilling properties, excellent lightness, and an unprecedented feel of elasticity, and a fabric using the same. it can.

  Hereinafter, the present invention will be described in detail.

  First, the yarn structure of the long and short composite yarn of the present invention will be described.

  In the long and short composite yarn of the present invention, it is a long and short composite yarn having a hollow fiber filament in the core portion and a short fiber in the sheath portion, and in addition, in order to obtain excellent covering properties and light weight, and a feeling of swelling, It is important that the spun yarn itself is substantially untwisted.

  That is, in the case of a substantially untwisted structure yarn, the above-described hollow type is obtained by a strong binding force to the filament component of the core portion by a short fiber component such as a real twist yarn or the actual twist imparted to the filament of the core portion. The hollow shape of the fiber filament is not destroyed, and excellent texture such as excellent lightness, water absorption, and swelling can be exhibited.

  Here, the substantially untwisted structure yarn in the present invention means that there is no occurrence of untwisting due to the action of twisting torque, or a very small state, and the average fiber length of the short fiber component is Ls. In this case, a real twist of 4.0 T / Ls or less or a non-twisted one is used. When the number of twists is 4.0 T / Ls or less, there is no occurrence of untwisting due to the action of twisting torque, so that it can be said to be a substantially untwisted structure yarn.

About the measuring method of a twist number, it can measure using a tester. That is, a method of grasping both ends of the yarn and applying an initial load to untwist is used, but the long / short composite yarn of the present invention cannot be untwisted by this method, or the number of twists is 4.0 T / Ls or less. It is.
Furthermore, in the case of a real twist structure yarn, the number of twists is set to be higher than usual in order to sufficiently cover the filament in the core with the short fibers in the sheath and prevent the short fiber components from falling off due to ironing or the like. There is a need. However, in this case, the force that restrains the filament in the core part becomes too high, and the hollow part of the hollow fiber is lost. This is not suitable as a means for obtaining an excellent texture intended by the present invention because the properties are lowered and a sufficient swell feeling cannot be obtained.

  In the long and short composite yarn of the present invention, the mixing ratio of the short fiber component in the sheath to the entire long and short composite yarn is preferably in the range of 40 to 85% by weight, and more preferably in the range of 50 to 70% by weight. It is more preferable. When the mixing ratio of the short fiber component is smaller than 40% by weight, the number of short fiber fibers is reduced, so that sufficient coverage cannot be obtained. The influence of physical properties becomes dominant, and a significant difference from ordinary fibers becomes small. Therefore, in order to obtain long and short composite yarns that have both excellent coverage as described above and excellent performance as described above, the mixing ratio of short fiber components Is more preferably in the range of 50 to 70% by weight.

  Next, a hollow fiber filament used in the long and short composite yarn of the present invention will be described.

  The cross-sectional shape of the hollow filament used in the long and short composite yarn of the present invention may be a round cross-section, flat cross-section, triangular cross-section, multi-loval cross-section, X-type cross-section, or other irregular cross-section, but it must be a hollow cross-section. There is.

  As used herein, the hollow cross section refers to a fiber having a space at the center of the fiber cross section as shown in FIG. 1, and the hollow part is the center of the fiber or the center point and hollow part of the fiber as shown in FIG. What shifted the center point of may be used. The hollow ratio is preferably in the range of 10 volume% to 70 volume%. If it is 10% by volume or less, sufficient lightness cannot be obtained, and if it exceeds 70% by volume, the fiber thickness becomes extremely thin, and it becomes difficult to obtain sufficient fiber strength.

Further, the cross-sectional shape of the hollow portion can be appropriately selected as long as the original function is not lost, such as a round shape, a polygonal shape such as an elliptical shape, a triangular shape or a square shape, or a star shape, and the number of hollow portions is also one. However, it is also preferable to provide a large number. An example is shown in FIG.
Although these hollow filaments can be produced by direct spinning, a hollow filament having a sharp cross-sectional shape of the hollow portion can be obtained by eluting the core portion after producing the core-sheath type composite fiber.

  The fineness of the hollow filament can be selected as appropriate, but in order to obtain the long and short composite yarn of the present invention, the single yarn fineness is preferably 5 dtex or less. The number of filaments is not particularly limited, and monofilaments may be used as long as they do not lose their original function. However, considering the productivity of long and short composite yarns and the entanglement between filaments and short fibers, multiple filaments may be used. It is preferable that In particular, the number is preferably 10 or more, but it is necessary to set the total fineness and the single yarn fineness in consideration of the single yarn fineness and the count of the long and short composite yarn to be obtained.

  As the fiber material, synthetic fibers such as polyester, acrylic, polyamide, and polypropylene can be appropriately selected. Among these, polyester is a preferable material because it is easy to obtain yarn properties excellent in stability.

  Next, the short fiber used for the long and short composite yarn of the present invention will be described.

  The fiber material used as the above short fiber is not particularly limited, and may be a natural fiber such as cotton, wool or hemp, a synthetic fiber such as polyester, acrylic, polyamide or polypropylene, or a semi-synthetic fiber such as rayon triacetate. Or two or more of these may be mixed.

  In addition, when synthetic fibers or semi-synthetic fibers are used as the short fibers, the cross-sectional shape is not particularly limited, and may be a round shape, an irregular shape such as a polygonal shape, an H shape, or a hollow shape. Further, the fineness of the short fiber is not particularly limited, but is preferably in the range of 0.6 to 5 dtex in consideration of the spinnability. The fiber length is preferably a fiber length corresponding to various spinning methods. However, when air spinning is used, about 25 mm to 51 mm can be preferably used in consideration of the spinning principle, and further, the range is 30 mm to 44 mm. More preferably, it is inside.

  With the above configuration, the long and short composite yarn of the present invention can have a hollow retention rate of 80% or more according to the following formula.

(Hollow rate of hollow filament before spinning−hollow rate of hollow filament after spinning) / Hollow rate of hollow filament before spinning × 100 = Hollow retention rate (%)
With the conventional method for producing a long / short composite yarn in which a hollow fiber is used as a core yarn and twisted, a hollow retention of 80% cannot be achieved.

  The long and short composite yarn of the present invention can be made into a fabric by weaving, knitting or the like by a known method. With the long and short composite yarns of the present invention, it is possible to obtain a fabric that has excellent water absorption and anti-pill properties, is excellent in lightness, and has an unprecedented sharpness. Of course, weaving and knitting with other yarns are possible within a range not impairing the effects of the present invention.

In addition, the fabric of this invention can make the hollow retention rate by following Formula 80% or more by using the long and short composite yarn of this invention.
(Hollow rate of hollow filament before woven or knitted-hollow rate of hollow filament after woven or knitted) / Hollow rate of hollow filament before woven or knitted × 100 = Hollow retention rate (%)
Here, the hollow ratio of the hollow filament before weaving or knitting is synonymous with the hollow ratio of the hollow filament of the spun yarn.
Next, a method for producing the long and short composite yarn of the present invention will be described.

  First, a hollow filament and a short fiber are prepared. Each fiber may be produced by a known method. Next, these fibers are spun into a spun yarn.

  The spinning method is not particularly limited as long as the resulting long and short composite yarns are substantially untwisted, but a general-purpose air spinning machine that binds short fiber components by the action of airflow to form a spun yarn In the method, a method obtained by supplying the filament to the center portion of the short fiber bundle in front of the yarn forming portion through a suitable feed roller and a long fiber facility such as a yarn path guide can be preferably used. Particularly preferred is a method using a Murata vortex spinner (Murata Kikai Co., Ltd .: hereinafter referred to as MVS). Various spinning methods that utilize the action of airflow have been proposed, developed, and used. However, in order to obtain the long and short composite yarns of the present invention, it is preferable that the coverage is good, and this is the most suitable for the spinning method using MVS. This is one of the spinning methods that can be achieved.

  Other methods include the following methods. First, a low-melting fiber having a low melting point of preferably 120 ° C. or lower is mixed in a certain ratio with the short fiber component, and a long / short composite yarn having a real twist structure is obtained by a general production method of a long / short composite yarn using a ring spinning machine. . Next, we put this long and short composite yarn on a ring twisting yarn machine with a hot roller or a non-contact type hot plate, giving the same number of twists in the opposite direction to the spinning machine, while completely returning the twist, It is also possible to obtain a non-twisted long / short composite yarn by fusing the low melting point fibers to the surrounding short fibers and filaments with a hot roller or a hot plate. In this method, the mixing ratio of the low melting point fiber to be mixed, the number of twists to be given, and the temperature setting value of the hot roller or hot plate may be appropriately designed so that the texture of the obtained long and short composite yarn is not impaired. is important.

  Hereinafter, the present invention will be described in detail with reference to examples.

(Spun yarn evaluation measurement method)
(1) Hollow retention rate of spun yarn A cross-sectional photograph of the filament (n = 5) before spinning was taken with SEM (magnification × 500), and the cross-sectional area of the fiber (total cross-sectional area including the hollow part) A and the fiber The cross-sectional area B of the hollow portion was obtained, and the filament hollow ratio C was shown as an average from the following formula.
(A−B) / A × 100 = Filament hollow ratio C (%)
Similarly, a SEM (magnification × 500) of the cross section of the spun yarn was photographed, and the cross-sectional area D of the hollow filament constituting the spun yarn and the cross-sectional area E of the hollow portion of the filament were determined for five points. The latter hollowness F was shown by the average.
(DE) / D × 100 = Filament hollow ratio after spinning F (%)
The hollow retention after spinning was determined by the following formula.
(C−F) / C × 100 = Hollow retention after spinning (%)
(2) Coverability evaluation Evaluation was made by observing the side surface of the obtained spun yarn with a 25-fold microscope and judging the number of locations where the filament of the core portion can be confirmed from the surface layer portion per 1 m of yarn length.
Judgment criteria were as follows: x: 10 or more places or occurrence of nude yarn, Δ: 5-9 places, ◯: 1-5 places, ◎: 0 places.

(Fabric evaluation measurement method)
(1) Hollow retention rate after weaving / knitting Cross-sectional area of hollow filaments (hollow part) taken by SEM (magnification × 500) by taking a cross-sectional photograph of yarn (n = 5) before weaving or knitting The cross-sectional area (b) of the hollow portion of the fiber and the fiber was obtained, and the average hollowness ratio of the filament was shown by the following formula.
(Iro) / I x 100 = Filament hollowness ratio (%)
Similarly, SEM (magnification × 500) of the yarn cross section before and after knitting or knitting was taken, and the cross-sectional area of one filament constituting the spun yarn and the cross-sectional area of the hollow portion of the filament were obtained for five points. From the following equation, the average hollowness after spinning is shown.
(Neho) / D x 100 = Filament hollow ratio after spinning (%)
The hollow retention after spinning was determined by the following formula.
(Ha ha) / ha x 100 = hollow retention after weaving and knitting (%)
(2) Wrinkle resistance Sample: Prepare a 9.6 cm diameter circle, prepare a 50 ml plastic beaker, place the sample on the top of the beaker, and place the sample in the beaker with a weight of 500 g (pressing area 43 g / cm2). Then, the load was applied for 10 minutes and de-weighted. Immediately after that, the state after 1 hour and 24 hours was discriminated by using the “appearance determination lateral ray” in the state of wrinkles.

(3) Pilling property JIS L-1076 (1992) Using the ICI method, the treatment time was 10 hours for the woven fabric and 5 hours for the knitted fabric, and the grade was determined.

(4) Bending rigidity Bending strength and hysteresis width were measured by the KES method with a KES FB-2 testing machine.

(5) Dimensional change rate It measured according to JIS L-1096 (1999).

(6) Quick-drying Sample size 40cm x 40cm is prepared, submerged in water for 5 minutes, then dehydrated in a household washing machine for 30 seconds, and weight every 5 minutes under conditions of temperature 20 ° C and humidity 65% RH. The moisture content (%) was determined by the following formula, and the time when the moisture content became 2% or less was defined as the drying time (minutes).

(7) Sensory evaluation Weaving plain weave fabric using both long and short composite yarns for both warp and weft, and the resulting green machine is relaxed and heat treated at 95 ° C with an open soaper, dried and then dried at 180 ° C in the middle Set and stain at 120 ° C. Thereafter, finish setting was performed by a pin tenter method with a dry heat of 160 ° C.

  The obtained fabric was subjected to a sensory test with 10 monitors per touch, feel of lightness, and touch, and the average of the determination results was taken as the evaluation result.

  The evaluation criteria are as follows: x: not felt at all, Δ: hardly felt, ◯: felt, ◎: felt strongly, x = 0 point, Δ = 1 point, ○ = 2 point, ＝= Replaced with 3 points and averaged, 0.0 to 0.9 points for x, 1.0 to 1.5 points for Δ, 1.6 to 2.5 points for ○, Five or more points were rated as ◎ for final evaluation results.

Example 1
A polyethylene terephthalate short fiber (T403, 1.45 dtex × 38 mm, manufactured by Toray) was used as the short fiber of the long / short composite yarn, and a sliver having a thickness of 1.0 g / m was prepared through a normal spinning method. Further, “body joy” (material: polyethylene terephthalate 44 dtex-12F, manufactured by Toray Industries, Inc.) was used as a hollow filament.

A sliver is mounted on the MVS, and the hollow filament is supplied from the front top roller to the second top roller to the center position in the width direction of the short fiber bundle via the filament feed roller device and the yarn path guide. A 30's long and short composite yarn was obtained with a count. The coating property was excellent, the occurrence of thread breakage was small, the hollow part was not damaged after processing, and the spinnability was good.
The obtained long / short composite yarn was used as a weft yarn, the warp yarn was used as polyethylene terephthalate FY, and using a normal loom, the woven structure was changed to 3/1 twill and a woven fabric having a woven density of 283 g / m was obtained. As a result of performing each evaluation on the obtained fabric, as shown in Table 1, there is no breakage of the hollow portion after processing, and as shown in FIG. 6, it is excellent in wrinkle resistance, and the texture is excellent in lightness. there were. An SEM photograph of the cross section of the obtained fabric is shown in FIG. 4 and a cross section of the yarn is shown in FIG.

(Example 2)
The same sliver as in Example 1 was prepared as a short fiber of a long / short composite yarn. Further, “Fariro” (material: nylon 6, 28 dtex-12F, manufactured by Toray Industries, Inc.) was used as a hollow filament.

A sliver is mounted on the MVS, and the hollow filament is supplied from the front top roller to the second top roller to the center position in the width direction of the short fiber bundle via the filament feed roller device and the yarn path guide. A 30's long and short composite yarn was obtained with a count. The coating property was excellent, the hollow part was not damaged after processing, the occurrence of yarn breakage was small, and the spinnability was good.
About the obtained long-short composite yarn, the same method as the Example was used, and the textile fabric of woven density 279g / m was obtained. As a result of each evaluation, as shown in FIG. 6, it was excellent in wrinkle resistance, and as shown in Table 1, the texture was excellent in lightness and good.

(Comparative Example 1)
Using the same polyester short fiber as in Example 1, a roving yarn having a thickness of 0.35 g / m was prepared through a normal spinning method and mounted on a ring spinning machine. On the other hand, the same hollow filament as in Example 1 is supplied from the front top roller to the second top roller to the center position of the short fiber bundle through the feed roller device for filament and the yarn path guide, and the draft rate of the ring spinning machine Was set to 40 times and the number of twists was set to 27.8 T / 2.54 cm, and a 30 'long / short composite yarn was obtained with a cotton count.
The obtained long and short composite yarns were excellent in spinnability, but the coating properties were inferior to those in Example 1, and the hollow part was damaged because the binding force to the hollow filaments by actual twisting was strong. It was. Similar to Example 1, a woven fabric having a weave density of 296 g / m was obtained as a weft, but a sufficient hollow ratio could not be maintained, so that the water absorption was poor and good texture could not be obtained even in sensory evaluation. .

(Comparative Example 2)
Using the same polyester short fiber as in Example 1, a roving yarn having a thickness of 0.35 g / m was prepared through a normal spinning method and mounted on a ring spinning machine. On the other hand, the same hollow filament as in Example 2 is supplied from between the front top roller to the second top roller to the center position of the short fiber bundle via the filament feed roller device and the yarn path guide, and the draft rate of the ring spinning machine Was set to 40 times and the number of twists was set to 27.8 T / 2.54 cm, and a 30 'long / short composite yarn was obtained with a cotton count.
The obtained long and short composite yarns were excellent in spinnability, but the coating properties were inferior to those of Example 2, and the hollow part was damaged because the binding force to the hollow filaments by actual twisting was strong. It was. Similar to Example 1, a woven fabric having a weave density of 296 g / m was obtained as a weft, but a sufficient hollow ratio could not be maintained, so that the water absorption was poor and good texture could not be obtained even in sensory evaluation. .

(Comparative Example 3)
The same sliver as in Example 1 was used, and it was subjected to MVS without supplying a filament to obtain a spun yarn of 30 s. Similar to Example 1, a woven fabric having a weave density of 287 g / m was obtained and evaluated. However, since a hollow filament was not used at the center, sufficient lightness could not be obtained, as shown in FIG. In addition, it was not wrinkle-proof and the texture was lacking in sharpness.

It is a schematic diagram of an example of the fiber cross section which has a hollow part in a concentric part. It is a schematic diagram of an example of the fiber cross section which has a hollow part in an eccentric part. It is a schematic diagram of an example of the fiber cross section which can be used for others. It is a cross-sectional SEM photograph of the fabric using the obtained long and short composite yarn in this invention. It is a SEM photograph of the section of the long and short composite yarn obtained in the present invention. It is the photograph which image | photographed the fabric state in the wrinkle-proof test.

Explanation of symbols

  1: Fiber hollow part

Claims (4)

A long / short composite yarn characterized by having a hollow filament in a core portion, short fibers in a sheath portion and being substantially untwisted. 2. The long / short composite yarn according to claim 1, wherein the hollow filaments in the core occupy 15 to 60% by weight of the whole, and the short fibers in the sheath occupy 40 to 85% by weight of the whole. 3. The long / short composite yarn according to claim 1 or 2, wherein the hollow retention rate according to the following formula is 80% or more.
(Hollow rate of hollow filament before spinning−hollow rate of hollow filament after spinning) / Hollow rate of hollow filament before spinning × 100 = Hollow retention rate (%) A fabric comprising the long and short composite yarn according to any one of claims 1 to 3 and having a hollow retention rate of 80% or more according to the following formula.
(Hollow rate of hollow filament before woven or knitted-hollow rate of hollow filament after woven or knitted) / Hollow rate of hollow filament before woven or knitted × 100 = Hollow retention rate (%)