JP2020051005A - Composite spun yarn and knitted fabric therewith - Google Patents

Abstract

To provide composite spun yarn and knitted fabric having superior water absorption and quick-drying not to be provided in a conventional technology and simple combination of the conventional technologies, and having soft texture of short fiber.SOLUTION: In composite spun yarn, continuous fiber and more than two kinds of short fiber are compounded, and average monofilament fineness of the short fiber forming the spun yarn switches intermittently in yarn length direction. Water absorption and quick-drying knitted fabric includes the composite spun yarn. It is preferable that the average monofilament fineness of the short fiber varies in the range of 0.1 to less than 2.0 dtex before and after the switching.SELECTED DRAWING: None

Description

  The present invention relates to a composite spun yarn and a knitted fabric containing the same.

  2. Description of the Related Art Conventionally, knitted fabrics containing spun yarns are widely used for inner uses and sportswear because of their soft texture. On the other hand, in these applications, when wearing, the feeling of stickiness when the knitted fabric gets wet due to sweat and the feeling of cold generated after sweating due to poor dryness are felt discomfort, etc. As a performance of a knitted fabric, water absorption and quick drying are strongly required.

  From such circumstances, various types of knitted fabrics having excellent water absorbency and quick drying properties have been studied, and as a representative example, one surface of the knitted fabric has a modified cross-section polyester fiber having one or more concave portions in a single yarn cross section. A knitted fabric composed of a yarn composed of a polyester fiber having a single fiber fineness of 3 decitex or less (Patent Document 1) has been proposed.

  Further, as a spun yarn having water absorption and quick drying properties, there is a spun yarn obtained by blending 60 to 80% by mass of a flat multi-lobed high-profile cross-section polyester fiber and 20 to 40% by mass of a low-profile cross-section fiber (Patent Document 2). .

  Further, as a spun yarn having a unique texture of short fibers, a mixed spun yarn in which the mixing ratio of two or more types of short fibers is intermittently switched in a column direction (Patent Document 3) has been proposed.

JP 2010-255139 A JP-A-2006-89284 JP, 2017-31523, A

  However, the knitted product described in Patent Document 1 has a severe limitation in the amount of knitted structure, the amount of irregular cross-section fibers having one or more concave portions in the single yarn cross section, and has a problem that it is not easy to manufacture as a general-purpose product.

  In addition, the spun yarn described in Patent Document 2 described above still requires improved performance in order to be suitable for inner uses and sportswear. Further, when used in textiles, a certain effect was recognized. The water-absorbing quick-drying property of a knitted fabric was not sufficient. This is because the knitted fabric has a smaller gap between the yarns than the woven fabric, so it cannot release water as a fabric structure, and the yarn itself easily retains water. Adaptation to the land is a challenge.

  Furthermore, in the knitted fabric containing the blended yarn described in Patent Document 3, there is no water-absorbing quick-drying effect, and there is a problem that it is difficult to apply the knitted fabric to innerwear and sportswear applications. Furthermore, in the case of a knitted fabric including a composite spun yarn in which the blended yarn is combined with a long fiber having a water-absorbing quick-drying property, the short fibers constituting the knitted fabric retain water, so that the knitted fabric moves from the inside to the outside. There was a problem that water could not be released and the water-absorbing quick-drying property was not sufficient.

  As described above, the present invention provides a composite spun yarn and a knitted fabric exhibiting excellent water-absorbing quick-drying properties, which cannot be obtained by conventional techniques or a simple combination of the conventional techniques, and further having a soft texture of short fibers. Make it an issue.

The present invention has one of the following configurations in order to solve the above problems.
(1) A composite spun yarn in which a long fiber and two or more types of short fibers are composited, wherein the average single fiber fineness of the short fibers constituting the spun yarn switches intermittently in the yarn length direction.
(2) The composite spun yarn according to claim 1, wherein the average single fiber fineness of the short fibers changes in a range of 0.1 dtex or more and less than 2.0 dtex before and after switching.
(3) The composite spun yarn according to claim 1 or 2, wherein the long fiber includes a fiber having a round cross section and a fiber having an irregular cross section.
(4) A water-absorbing quick-drying knitted fabric comprising the composite spun yarn according to any one of claims 1 to 3.

  According to the present invention, a composite spun yarn exhibiting excellent water-absorbing quick-drying properties and further having a soft texture of short fibers is obtained, and a knitted fabric containing this spun yarn is excellent in production while being easy to manufacture. Since it has quick drying properties, it becomes a knitted fabric that can be widely used for clothing.

  First, a composite spun yarn of the present invention and a form of a knitted fabric containing the spun yarn will be described.

  The fibers constituting the composite spun yarn of the present invention include a mixture of long fibers and short fibers of two or more types having different single fiber finenesses. The yarn type of the staple fiber described here includes not only materials such as polyester and polyamide, but also those having the same fiber but different in fiber length, fineness, cross-sectional shape, and dyeing difference. It is counted as one thread type. That is, for example, even if the polyester is the same material, the yarn types are different if the cross-sectional shape is different from the circular cross-section and the triangular cross-section, and the black yarn dyed with raw cotton and the white yarn not dyed with raw cotton are also different yarn types.

  The type of fiber used in the conjugate spun yarn of the present invention is not particularly limited, either short fiber or long fiber, and depending on the purpose and application, in addition to ordinary synthetic fibers, cellulosic fibers, vegetable fibers and It can be appropriately selected from animal fibers and the like.

  Among them, the frequency of use for sports clothing is high, polyester-based fibers that require higher quick-drying when made into fabrics and products, polyamide fibers, acrylic fibers, including at least one selected from rayon fibers in part In this case, since it is a general-purpose product and can be manufactured at a general processing site, it is preferable because it can be easily manufactured.

  Examples of the polyester constituting the polyester fiber used in the present invention include a polymer produced by a condensation reaction of terephthalic acid with ethylene glycol, trimethylene glycol or butylene glycol, and sebacic acid, adipic acid, trimellitic acid. And condensates of isophthalic acid and p-hydroxybenzoic acid with ethylene glycol and the like, and polyester polymers including other polyesters.

  Further, the cross-sectional shape of the fiber used in the conjugate spun yarn of the present invention is not particularly limited to any of short fibers and long fibers, but a solid cross section, a hollow cross section, a round cross section, a triangular cross section, and a cross cross section It is also possible to use fibers having other irregular cross-sections such as. In the above, examples of the irregular cross section include a flat cross section, a polygon cross section, and a multi-leaf cross section. Further, in order to take advantage of the capillary phenomenon, the fiber may have an angled slit or micropore, or a concave portion in the fiber cross section.

  As the long fiber used in obtaining the composite spun yarn of the present invention, the total fineness is preferably 20 dtex or more and 300 dtex or less, and preferably 22 to 180 dtex, since the water absorption quick-drying property and the soft texture are both obtained. Is particularly preferred. The effect is also exhibited by a single yarn type, but when a mixed fiber of two or more long fibers having different fineness or fiber cross section is used, the effect of the present invention is increased, preferable.

  As a combination of two types of long fibers having different finenesses, among the two or more types of long fibers, the fineness ratio of the large yarn type and the small type yarn is 1.1 times or more and 5.0 times or more. It is preferable that the ratio is equal to or less than 1.1, and it is particularly preferable that the ratio is 1.1 to 3.0 times.

  As a combination of two types of long fibers having different fiber cross sections, a combination of a round cross section fiber and a modified cross section fiber is preferable, and the yarn form is a plying yarn in which the long fibers are aligned, a yarn processing step, or the like. And the like are preferred.

  Furthermore, it is more preferable to use a combination of two types of long fibers having different fineness and fiber cross section, because the performance is greatly exhibited by a synergistic effect.

  When such a mixed yarn is selected, the attached water is diffused by a capillary phenomenon in a gap formed between cross sections of different sizes, so that a particularly fast drying effect is exhibited. The effect of the invention is increased, which is more preferable.

  Further, as the short fibers used for obtaining the composite spun yarn of the present invention, two or more yarn types having different single fiber deniers are used in combination.

  In the present invention, "the average single fiber fineness of the short fibers constituting the spun yarn is intermittently switched in the yarn length direction" means that the average single fiber fineness of the short fibers constituting the yarn cross section according to the application or performance is the yarn. It switches in the long direction.

  Here, the average single fiber fineness of the short fibers means an average value of the single fiber fineness of the short fibers constituting the cross section when a certain yarn cross section is observed.

  For example, as a combination of two types of short fibers having different single fiber finenesses, a short fiber having a single fiber fineness of 0.5 dtex and a short fiber having a single fiber fineness of 2.5 dtex are selected. When there are 30 and 20 fibers respectively, the average single fiber fineness of the short fibers constituting the cross section is (0.5 dtex × 30 fibers / (30 fibers + 20 fibers)) + (2.5 dtex × 20 fibers / ( 30 + 20)) = 1.3 dtex. In the case where three or more types of short fibers are combined, the average fineness is calculated similarly.

  In the present invention, when water is attached to the spun yarn, the size formed between the short fibers differs by intermittently switching the average single fiber fineness of the short fibers constituting the spun yarn in the yarn length direction. The water quickly moves through the gap by the capillary phenomenon, so that a water-absorbing quick-drying effect is obtained. Further, the effect of the present invention is further exhibited because the speed of the effect is increased by being combined with the long fiber.

  When the cross section of the spun yarn is observed at least 10 times continuously at intervals of 50 mm, if at least one portion where the average single fiber fineness of the short fibers is different is present, the composite spun yarn of the present invention is constituted. It can be said to be a spun yarn in which the average single fiber fineness of short fibers changes.

  When the difference in the average single fiber fineness of the short fibers that changes in the yarn length direction of the spun yarn is in the range of 0.1 dtex or more, it is preferable because the capillary effect occurs in the short fiber portion to obtain a quick-drying effect. If it is 3 dtex or more, the effect is greater, and therefore it is more preferable.

  On the other hand, when the difference in the average single fiber fineness of the short fibers is too large exceeding 2.0 dtex, the water absorption quick-drying property is preferable, but the difference in the number of short fibers constituting the spun yarn in the yarn length direction becomes large. This is not preferable because the strength fluctuation of the entire yarn becomes large, and yarn breakage occurs in a knitting process for manufacturing a knitted fabric, making it difficult to manufacture. A more preferable difference in single fiber fineness of the short fibers is 0.1 dtex or more and 2.0 dtex or less.

  The single fiber fineness of the short fibers can be easily calculated by the JIS L 1015 8.5 method (2010 version).

  The single fiber fineness of the short fibers used in obtaining the composite spun yarn of the present invention is, in consideration of the yarn count used for apparel, the yarn type having a large single fiber fineness and 0.5 dtex or more for any of the small yarn types. 3.3 dtex or less is preferable.

  The pitch at which the average single fiber fineness of the short fibers switches is preferably 40 mm or more and 200 mm or less. Switching the average single fiber fineness at a short pitch improves the water absorption quick-drying property. Therefore, it is preferably 200 mm or less.However, the yarn strength is reduced at the portion where the average single fiber fineness is switched. If a spun yarn having a changed fiber fineness is used, the yarn is broken in a knitting step of obtaining a knitted fabric, and the production is not easy. Therefore, it is preferable that the thickness be 40 mm or more.

  The fiber length of the short fiber used in the present invention is appropriately selected according to the application. For example, 20 mm to 100 mm, which is typically selected for use in clothing, is preferred. In particular, a fiber having a shorter fiber length is more excellent in quick-drying properties. On the other hand, if the length is too long or too short, production in a general spinning factory tends to be difficult. Further, the fiber length is appropriately selected according to the length of the switching pitch.

  Further, the composite spun yarn of the present invention is a composite spun yarn in which long fibers and short fibers are composited. The mass ratio of short fibers is preferably 50% by mass or more and 80% by mass or less, and the ratio of long fibers is 20% by mass. It is preferably from 50% by mass to 50% by mass. Among them, the ratio of short fibers is more preferably 55% by mass or more and 75% by mass or less, and the ratio of long fibers is more preferably 25% by mass or more and 45% by mass or less. A knitted fabric using a spun yarn obtained in this range is preferable because the effect of the present invention is exerted because the movement of water by capillary action is more smoothly performed when water adheres.

  In addition, among the short fibers of two or more yarn types, the fineness ratio of the large yarn type to the small yarn type is 1.1 times or more and 6.6 times or less for general use for clothing. It is preferable because it can be used.

  As a method of obtaining the composite spun yarn of the present invention, as in a general spun yarn, for example, in a drawing process such as a drawing machine or a gil machine, two or more types of slivers are prepared, and the creel is driven alone, A sliver is manufactured by intermittently switching two or more types of slivers in the column direction, and the sliver is converted to roving as necessary and set on a ring spinning machine, air spinning machine, binding spinning machine, etc. It can be easily manufactured by adopting a method of performing, or a method of combining with a long fiber using a spinning machine having a mechanism for independently supplying two or more rovings in a spinning process. . In addition, using a spun yarn obtained by a ring spinning machine, an air spinning machine, a binding spinning machine, etc., the average single fiber fineness of the short fibers constituting the spun yarn in the yarn length direction switches intermittently. A method of compounding with a fiber may be used.

  The yarn count of the composite spun yarn of the present invention can be appropriately selected depending on the application. For general clothing applications used for inner uses and sportswear, it is preferably in the range of 20 to 100 counts (cotton type), and for frequently used T-shirts and thin outer uses, 20 to 60 counts ( Cotton type) is more preferably used.

  Next, a knitted fabric containing the composite spun yarn of the present invention will be described.

  The knitted fabric can be knitted in a normal weft knitting or vertical knitting process. The knitting process may be a commonly used process, and the production can be easily performed without any problem. The structure and density of the knitted fabric are selected according to the required use, physical properties, and functionality.

  In the composite spun yarn of the present invention, the spun yarn can be used for a part of a knitted fabric, or can be used for the entire knitted fabric, and a design can be determined according to its use and purpose. Of the fibers constituting the knitted fabric, if the composite spun yarn of the present invention is 50% by mass or more, the effect is exhibited, so that it is preferable.

  Next, the composite spun yarn of the present invention will be described more specifically based on examples and the like. However, the present invention is not limited to only these examples. Each physical property value in the examples was measured by the following method.

(1) Average single fiber fineness of the short fibers constituting the spun yarn The yarn cross section was observed at a total length of 500 mm at one place every 50 mm of the spun yarn and continuously at 10 places. The average single fiber fineness of the short fibers is calculated. After calculating the difference in the average single fiber fineness from the adjacent one or two yarn cross sections for all 10 yarn cross sections, the arithmetic average of the difference in the average single fiber fineness is further obtained. The arithmetic average value was evaluated as follows.
：: Difference in average single fiber fineness is not less than 0.1 dtex and 2,0 dtex or less〇: Difference in average single fiber fineness is greater than 2.0 dtex △: Difference in average single fiber fineness is less than 0.1 dtex ×: No difference in average single fiber fineness.

  The single fiber fineness was measured in advance for each short fiber type according to 8.51.1 of JIS L1015: 2010, the number of various short fibers was confirmed by observing the yarn cross section, and averaged by the method described above. The single fiber fineness was calculated.

(2) Manufacturability of knitted fabric 〇: Yarn breakage does not occur and manufacturing is easy.
Δ: Thread breakage occurs partially, and production is possible but not easy.
×: Thread breakage occurs frequently and production is not possible.

(3) Soft texture of the knitted fabric A test piece was cut out into a 10 cm square, and five test subjects gripped the cut out test piece. The score was evaluated according to the following criteria, and the average score was calculated. And "O" were accepted.
3 points: soft texture of span is felt, soft 2 points: soft texture is felt partly, but slightly hard,
1 point: Hard texture ◎: 2.8 points or more ○: 2.4 points or more and less than 2.8 points △: 1.9 to less than 2.4 x: less than 1.9 points

(4) Water-absorbing quick-drying property of knitted fabric <Evaluation of water absorption>
The evaluation was performed according to JIS L1907 (2013) (Bilec method). The content of the evaluation was as follows, and “◎” and “○” were accepted.
◎: 80 mm or more ○: 70 to less than 80 mm Δ: 50 to less than 70 mm ×: less than 50 mm

<Quick drying evaluation>
A test piece left at room temperature of 25 ° C. and a humidity of 40% RH for 24 hours is cut into a 10 cm square, and the mass (A) is measured. Next, the test piece is immersed in ion-exchanged water for 30 seconds, and then one corner of the test piece is pinched with tweezers and taken out of the liquid. The test piece taken out is similarly left for 1 hour in an atmosphere of room temperature of 25 ° C. and a humidity of 40% RH, air-dried, and the mass (B) is measured. The residual moisture content (C) is calculated by the following equation.
C (%) = (BA) / A × 100
The content of the evaluation was as follows, and “◎” and “○” were accepted.
：: 30% or less ：: More than 30% and 40% or less Δ: More than 40% and 50% or less ×: More than 50% or more

(Example 1)
As the short fiber, a roving composed of a polyester short fiber having a single fiber fineness of 1.0 dtex and a fiber length of 38 mm (manufactured by Toray Industries, Inc., type: T401) (short fiber 1) and a single fiber fineness of 1.5 dtex and a fiber length of 38 mm A roving composed of normal pressure cationic dyeable polyester short fiber (manufactured by Toray Industries, Inc., type: A461, Lumilet (registered trademark)) (short fiber 2) was produced. As the long fiber, a 56dtex filament processed yarn (manufactured by Toray Industries, Inc., product type: SEO α (registered trademark)) (long fiber 1) prepared by combining a round section polyester filament and a six-lobe section polyester filament was prepared. These rovings and filaments are compound-spun using a spinning machine manufactured by Toyoda Automatic Loom Co., Ltd. in such a setting that the two types of rovings are spun out so that the switching pitch is 100 mm. A spun yarn was obtained. The mass ratio between the short fibers and the long fibers in the present composite spun yarn was 72% by mass and 28% by mass, respectively. The spinnability was good and there was no yarn breakage. Using this spun yarn, a knitted fabric having an inlaid fabric was produced using a 28 gauge, 30 inch (76.2 cm) knitting machine. At the time of knitting, no yarn break occurred, and it was easy to manufacture. Dyeing and finishing were performed in the general steps of pre-setting, scouring / bleaching and finishing. The knitted fabric obtained had a basis weight of 156 g / m ² .

(Example 2)
As the short fiber, a roving composed of a polyester short fiber (short fiber 1; manufactured by Toray Industries, Inc., type: T401) having a single fiber fineness of 1.0 dtex and a fiber length of 38 mm, and a single fiber fineness of 3.3 dtex and a fiber length of 51 mm A spun yarn and a knitted fabric were produced in the same manner as in Example 1 except that a roving composed of polyester staple fiber (manufactured by Toray Industries, product: T201) (staple fiber 3) was used. The mass ratio between the short fibers and the long fibers in the present composite spun yarn was 72% by mass and 28% by mass, respectively. The knitted fabric obtained had a basis weight of 151 g / m ² .

(Example 3)
As short fibers, polyester short fibers having a single fiber fineness of 1.0 dtex and a fiber length of 38 mm (manufactured by Toray Industries, Inc., type: T401) (short fiber 1), and a normal fiber cation having a single fiber fineness of 1.5 dtex and a fiber length of 38 mm are available. A roving yarn compounded in a blended cotton process under the condition that dyed polyester staple fiber (manufactured by Toray Industries, Inc., type: A461, Lumilet (registered trademark)) (staple fiber 2) is uniformly mixed, and a single fiber fineness of 1.7 dtex A spun yarn and a knitted fabric were produced in the same manner as in Example 1 except that a roving composed of polyester short fiber (short fiber 1) manufactured by Toray Industries, Inc., having a fiber length of 51 mm (short fiber 1) was used. The mass ratio between the short fibers and the long fibers in the present composite spun yarn was 72% by mass and 28% by mass, respectively. The obtained knitted fabric had a basis weight of 143 g / m ² .

(Example 4)
As the short fiber, a roving composed of a polyester short fiber (manufactured by Toray Industries, Inc., type: T401) (short fiber 1) having a single fiber fineness of 1.0 dtex and a fiber length of 38 mm, and a single fiber fineness of 1.7 dtex and a fiber length of 38 mm A roving yarn composed of irregular-shaped polyester short fibers (manufactured by Toray Industries, Inc., product type: Pentas α (registered trademark)) (short fibers 4) was prepared. A spun yarn and a knitted fabric were produced in the same manner as in Example 1 except that 84 dtex polyester filament processed yarn (manufactured by Toray Industries, Inc., type: B20Z) (long fiber 2) was prepared as the long fiber. In addition, the mass ratio of the short fiber and the long fiber in the spun yarn was 57% by mass and 43% by mass, respectively. The obtained knitted fabric had a basis weight of 170 g / m ² .

(Comparative Example 1)
A roving composed of a polyester short fiber having a single fiber fineness of 1.0 dtex and a fiber length of 38 mm (manufactured by Toray Industries, Inc., type: T401) (short fiber 1) and a normal pressure cation having a single fiber fineness of 1.5 dtex and a fiber length of 38 mm are available. A roving yarn made of dyed polyester staple fiber (manufactured by Toray Industries, Inc., type: A461, Lumilet (registered trademark)) (staple fiber 2) was produced. These rovings and filaments are spun using a spinning machine manufactured by Toyoda Automatic Loom Co., Ltd. in such a setting that the two types of rovings are spun so that the switching pitch is 100 mm, and the cotton count is 30th. Yarn was obtained. The mass ratio between the short fibers and the long fibers in the spun yarn was 100% by mass and 0% by mass, respectively. The spinnability was good and there was no yarn breakage. Using this spun yarn, a knitted fabric was produced in the same manner as in Example 1. The obtained knitted fabric had a basis weight of 139 g / m ² .

(Comparative Example 2)
28 gauge, 30 inches (76.2 cm) using 84 dtex filament processed yarn (manufactured by Toray Industries, Inc., product type: SEO α (registered trademark)) (long fiber 1) in which a round section polyester filament and a hexagonal section polyester filament are combined. The knitting machine of (1) was used to fabricate a knitted fabric having a sheeting structure. In addition, the mass ratio of the short fiber and the long fiber in the present fiber was 0% by mass and 100% by mass, respectively. At the time of knitting, no yarn break occurred, and it was easy to manufacture. The obtained knitted fabric had a basis weight of 172 g / m ² .

(Comparative Example 3)
As short fibers, polyester short fibers with a single-fiber fineness of 1.0 dtex and a fiber length of 38 mm (manufactured by Toray Industries, Inc., type: T401) (short fiber 1) and single-fiber fineness of 1.5 dtex and normal-pressure cationic dyeing with a fiber length of 38 mm A roving yarn composited in the blended cotton wool process under conditions where polyester staple fibers (manufactured by Toray Industries, Inc., type: A461, Lumilet (registered trademark)) (staple fibers 2) were mixed evenly. 84 dtex polyester filament processed yarn (manufactured by Toray Industries, Inc., type: B20Z) (long fiber 2) was prepared as the long fiber. These rovings and long fibers were subjected to composite spinning using a spinning machine manufactured by Toyoda Automatic Loom Co., Ltd. to obtain a spun yarn having a cotton count of 30. In addition, the mass ratio of the short fiber and the long fiber in the spun yarn was 57% by mass and 43% by mass, respectively. Using this spun yarn, a knitted fabric was produced in the same manner as in Example 1. The obtained knitted fabric had a basis weight of 161 g / m ² .

(Comparative Example 4)
As the short fiber, a roving composed of a polyester short fiber (short fiber 1; manufactured by Toray Industries, Inc., type: T401) having a single fiber fineness of 1.0 dtex and a fiber length of 38 mm, and a single fiber fineness of 3.3 dtex and a fiber length of 51 mm A roving composed of polyester staple fiber (manufactured by Toray Industries, Inc., type: T201) (staple fiber 3) was prepared. 84 dtex polyester filament processed yarn (manufactured by Toray Industries, Inc., type: B20Z) (long fiber 2) was prepared as the long fiber. These two rovings are spun at a constant mass ratio of 1: 1 and the above two rovings and long fibers are composite-spun using a spinning machine manufactured by Toyota Industries Corporation, A spun yarn having a cotton count of 30 was obtained. In addition, the mass ratio of the short fiber and the long fiber in the spun yarn was 57% by mass and 43% by mass, respectively. Using this spun yarn, a knitted fabric was produced in the same manner as in Example 1. The obtained knitted fabric had a basis weight of 148 g / m ² .

  ADVANTAGE OF THE INVENTION According to the composite spun yarn of the present invention, it is possible to obtain a composite spun yarn exhibiting excellent water-absorbing quick-drying property and further having a soft texture possessed by short fibers. It can be widely used for inner uses and sportswear.

Claims (4)

A composite spun yarn in which a long fiber and a short fiber of two or more yarn types having different finenesses are compounded, wherein the average single fiber fineness of the short fibers constituting the spun yarn switches intermittently in the yarn length direction. Spun yarn. The composite spun yarn according to claim 1, wherein the average single fiber fineness of the short fibers changes in a range of 0.1 dtex or more and less than 2.0 dtex before and after switching. The conjugate spun yarn according to claim 1 or 2, wherein the long fiber includes a round cross-section fiber and a modified cross-section fiber. A knitted fabric comprising the composite spun yarn according to claim 1.