Composite fiber, structural yarn, woven and knitted fabric, and clothing

Abstract

Provided are: a composite fiber which satisfies both stretch performance and abrasion resistance and exhibits high sensitivity of a woolen material having the characteristics of softness, deep color development, and bulkiness among wool materials; and a combined filament composite fiber, a woven and knitted fabric, and clothing containing the same. To this end, a composite fiber according to the present invention contains a polyester-based thermoplastic resin A and a polyester-based thermoplastic resin B and satisfies the following requirements. (1) The difference (MA-MB) between the weight-average molecular weight MA of the polyester-based thermoplastic resin A and the weight-average molecular weight MB of the polyester-based thermoplastic resin B is 2,000-15,000. (2) The apparent thick-thin ratio (Dthick / Dthin) of the composite fiber is 1.00-1.04. (3) The crimp elongation rate of the composite fiber is 3.0-25.0%. (4) In a cross section of the composite fiber, the polyester-based thermoplastic resin B covers the polyester-based thermoplastic resin A, and the ratio (tmin / D) of the minimum value tmin of the thickness t of the polyester-based thermoplastic resin B to the fiber diameter D of the composite fiber is 0.01-0.10. (5) In the cross section of the composite fiber, the length Ct of a portion, in which a region having the thickness t satisfying 1.00 tmin≤t≤1.05 tmin and the circumferential line of the composite fiber are overlapped, satisfies Ct≥0.33C with respect to the circumferential length C of the total composite fiber.

Description

Composite fibers, structural yarns, woven and knitted fabrics and clothing

[0001] The present invention relates to composite fibers, structural yarns, woven and knitted fabrics, and garments.

[0002] Among wool materials, there has long been a demand for woolen-like fabrics that combine the texture of woolen materials, which are characterized by softness, deep color development, and bulkiness, with functionality and durability such as stretchability and abrasion resistance.

[0003] As a wool-like fabric, for example, a fabric made of a mixed and intertwined mixture of two types of latent crimp fibers with different heat shrinkage rates, as disclosed in Patent Document 1, has been proposed.

[0004] Japanese Patent Application Laid-Open No. 2004-197231

[0005] A known method for achieving a wool-like heathered appearance is to impart thickness and thinness in the longitudinal direction of the fiber by drawing at a ratio lower than the natural drawing ratio. This method can achieve the heathered appearance that is one of the characteristics of various wool materials. However, this method does not sufficiently achieve the characteristics of wool, such as uniform and deep coloring, bulkiness, and softness. In addition, the fiber structure of the thick part of the heathered fiber is underdeveloped, making it difficult to achieve abrasion resistance.

[0006] One possible means for achieving a soft, fluffy woolen-like texture is to produce a fabric using a blended yarn of long fibers that has the crimp structure seen in wool. However, in the technology disclosed in Patent Document 1, if the boiling water shrinkage rate of the high-shrinkage fiber is 10% or more, the fiber is constrained in the fabric, and sufficient softness cannot be obtained. Furthermore, the low-shrinkage fiber disclosed in Patent Document 1 suffers from a significant deterioration in physical properties due to alkali treatment, which means that durability and texture cannot be achieved at the same time. In other words, it was not possible to simultaneously satisfy the softness, deep color development, bulkiness, and other woolen-like textures, as well as stretchability and abrasion resistance.

[0007] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a composite fiber, a structural yarn, a woven or knitted fabric, and clothing that satisfy both the properties of stretch performance and abrasion resistance, and that exhibit the high sensitivity of a woolen material that is characterized by softness, deep color development, and bulkiness among woolen materials, and in particular, a soft woolen texture.

[0008] The present invention has the following configuration: [1] A composite fiber containing a polyester-based thermoplastic resin A and a polyester-based thermoplastic resin B, and satisfying the following requirements: (1) The weight average molecular weight M of the polyester-based thermoplastic resin A is 1.0 ... Ａ and the weight average molecular weight M of the polyester-based thermoplastic resin B Ｂ The difference between Ａ -M Ｂ (2) The apparent thickness ratio (D ｔｈｉｃｋ / D ｔｈｉｎ (3) The crimp elongation of the conjugate fiber is 3.0 to 25.0%. (4) In the cross section of the conjugate fiber, the polyester-based thermoplastic resin B covers the polyester-based thermoplastic resin A, and the minimum value t of the thickness t of the polyester-based thermoplastic resin B is 1.00 to 1.04. ｍｉｎ and the ratio of the fiber diameter D of the composite fiber (t ｍｉｎ (5) In the cross section of the composite fiber, the thickness t is 1.00t ｍｉｎ ≦t≦1.05t ｍｉｎ The length C of the overlapping portion of the region satisfying the above and the periphery of the composite fiber ｔ is the perimeter C of the entire composite fiber, ｔ≧0.33C. [2] The conjugated fiber according to [1] above, wherein at least one other yarn coexists in the form of a mixed conjugated fiber. [3] The conjugated fiber according to [2] above, wherein the other yarn is a latent crimp yarn. [4] A structured yarn obtained by forming cracks around the entire surface of the conjugated fiber according to [1] above. [5] The structured yarn according to [4] above, wherein at least one other yarn coexists in the form of a mixed conjugated fiber. [6] The structured yarn according to [5] above, wherein the other yarn is a visibly crimped yarn. [7] A woven or knitted fabric obtained by weaving or knitting at least a portion of the conjugated fiber according to any one of [1] to [3] above. [8] A woven or knitted fabric at least a portion of which comprises the structured yarn according to any one of [4] to [6] above. [9] A garment at least a portion of which comprises the woven or knitted fabric according to [7] or [8] above.

[0009] According to the present invention, a conjugated fiber can be obtained which satisfies both the properties of stretchability and abrasion resistance, and which has the high sensitivity of a woolen material characterized by softness among woolen materials, deep color development, and bulkiness, particularly exhibiting a soft woolen texture. In particular, structural yarns, woven or knitted fabrics, and clothing using the conjugated fiber of the present invention can be made into outerwear items worn by women and men, such as jackets, suits, and bottoms.

[0010] Fig. 1 is a cross-sectional view illustrating the state of polyester-based thermoplastic resin A and polyester-based thermoplastic resin B in the conjugate fiber of the present invention. Fig. 2 is a perspective view illustrating one embodiment of the surface of the conjugate fiber of the present invention. Fig. 3 is a schematic diagram of a drawing and relaxation heat treatment device used in producing the conjugate fiber of the present invention. Fig. 4 is a schematic diagram of a final distribution plate related to Example 1 of the conjugate fiber of the present invention. Fig. 5 is a schematic diagram of a final distribution plate related to Comparative Example 5 of the conjugate fiber of the present invention.

[0011] The conjugate fiber of the present invention contains a polyester-based thermoplastic resin A and a polyester-based thermoplastic resin B, and satisfies the following requirements (1) to (5): (1) The weight average molecular weight M of the polyester-based thermoplastic resin A is Ａ and the weight average molecular weight M of the polyester-based thermoplastic resin B Ｂ The difference between Ａ -M Ｂ(2) The apparent thickness ratio (D ｔｈｉｃｋ / D ｔｈｉｎ (3) The crimp elongation of the conjugate fiber is 3.0 to 25.0%. (4) In the cross section of the conjugate fiber, the polyester-based thermoplastic resin B covers the polyester-based thermoplastic resin A, and the minimum value t of the thickness t of the polyester-based thermoplastic resin B is 1.00 to 1.04. ｍｉｎ and the ratio of the fiber diameter D of the composite fiber (t ｍｉｎ (5) In the cross section of the composite fiber, the thickness t is 1.00t ｍｉｎ ≦t≦1.05t ｍｉｎ The length C of the overlapping portion of the region satisfying the above and the periphery of the composite fiber ｔ is the perimeter C of the entire composite fiber, ｔ ≧0.33C.

[0012] The present invention will be described in detail below, but the present invention is not limited to the scope of the following description as long as it does not deviate from the gist of the invention.

[0013] [Polyester-based thermoplastic resin A, polyester-based thermoplastic resin B] The conjugated fiber of the present invention contains polyester-based thermoplastic resin A and polyester-based thermoplastic resin B.

[0014] The polyester resin used in the conjugated fiber of the present invention is preferably a polyethylene terephthalate resin whose main repeating unit is ethylene terephthalate, a polytrimethylene terephthalate resin whose main repeating unit is trimethylene terephthalate, or a polybutylene terephthalate resin whose main repeating unit is butylene terephthalate. More preferably, the main repeating unit of both polyester thermoplastic resin A and polyester thermoplastic resin B is ethylene terephthalate. Here, "the main repeating unit is ethylene terephthalate" means that the proportion of ethylene terephthalate-derived structures contained in the repeating units is 60 mol % or more. The same applies hereinafter.

[0015] The polyethylene terephthalate resin, polytrimethylene terephthalate resin, and polybutylene terephthalate resin may optionally contain a small amount (usually less than 30 mol%) of copolymerization component. When the copolymerization component of polyester thermoplastic resin A is 8 mol% or less, the crimp elongation can be increased and strength can be maintained even after alkali reduction, making it easier to achieve softness. Furthermore, by setting the copolymerization component to 8 mol% or less, dimensional stability can be improved by maintaining molecular orientation in the composite fiber even after dyeing. Preferably, both polyester thermoplastic resin A and polyester thermoplastic resin B contain copolymerization components of 5 mol% or less, and more preferably, neither polyester thermoplastic resin A nor polyester thermoplastic resin B contains copolymerization components. The absence of copolymerization components allows the boiling water shrinkage of the composite fiber to be 10% or less, making it easier to achieve a softer texture for woven and knitted fabrics.

[0016] The polyester thermoplastic resin A and the polyester thermoplastic resin B in the present invention may contain, as necessary, one or more of a micropore-forming agent, a cationic dyeable agent, a coloration inhibitor, a heat stabilizer, a flame retardant, a fluorescent brightening agent, a matting agent, a colorant, an antistatic agent, a moisture absorbent, an antibacterial agent, inorganic fine particles, etc., within the scope of the object of the present invention.

[0017] The composite fiber of the present invention has a weight average molecular weight M Ａ and the weight average molecular weight M of polyester thermoplastic resin B Ｂ The difference between Ａ -M Ｂ (hereinafter sometimes referred to simply as "difference in weight-average molecular weight") is 2,000 to 15,000. If the difference in weight-average molecular weight is less than 2,000, the resilience and stretchability of the composite fiber will be reduced, and color development will also be reduced because cracks due to alkali treatment will not be formed. The difference in weight-average molecular weight is preferably 5,000 or more. On the other hand, if the difference in weight-average molecular weight is more than 15,000, the strength of the raw yarn will be reduced and spinning will be unstable. The difference in weight-average molecular weight is preferably 13,000 or less.

[0018] The weight average molecular weight M of the polyester thermoplastic resin A Ａ The range of the value of is preferably 20,000 to 28,000, and the weight average molecular weight M of the polyester thermoplastic resin B is Ｂ The range of the value of is preferably 12000 to 20000. When each of these ranges is satisfied, the functionality and durability of the composite fiber are improved, and the process stability when spinning the composite fiber is also improved.

[0019] The weight average molecular weight in the present invention is measured by the method described in the Examples.

[0020] [Conjugated fiber or structural yarn] In the conjugated fiber of the present invention, polyester thermoplastic resin B covers polyester thermoplastic resin A. That is, as illustrated schematically in Figure 1, in a cross section substantially perpendicular to the fiber axis of the conjugated fiber, polyester thermoplastic resin A1 and polyester thermoplastic resin B2 exist in a bonded state without being substantially separated, and polyester thermoplastic resin B2 covers polyester thermoplastic resin A1 on the fiber surface, thereby providing a conjugated cross section.

[0021] At this time, in the cross section of the composite fiber, the minimum value t of the thickness t16 of the polyester thermoplastic resin B covering the polyester thermoplastic resin A ｍｉｎ and the ratio of the fiber diameter D of the composite fiber (t ｍｉｎ / D) is 0.01 to 0.10. ｍｉｎ If (t / D) is less than 0.01, the quality of the fabric, abrasion resistance, and color development will be reduced due to fluffing, etc. Preferably, it is 0.02 or more. ｍｉｎ If the ratio (t / D) exceeds 0.10, it becomes difficult to obtain sufficient bulkiness and softness due to sufficient crimp development. ｍｉｎ / D) is preferably 0.08 or less. ｍｉｎ As a method for adjusting the ratio (f / D) within the above range, for example, a method of carrying out the spinning process using a specific distribution plate, as will be described later, can be mentioned.

[0022] The cross section of the composite fiber of the present invention is preferably an eccentric core-sheath type.

[0023] In addition, in the cross section of the composite fiber of the present invention, the thickness t is 1.00t ｍｉｎ ≦t≦1.05t ｍｉｎ The length C of the overlapping portion of the region satisfying the above and the periphery of the composite fiber ｔ is the circumference of the entire composite fiber C, ｔ ≧0.33C. Here, the thickness t is 1.00t ｍｉｎ ≦t≦1.05t ｍｉｎ If the overlapping portion of the region satisfying the above and the peripheral line of the composite fiber is discontinuous, the individual total values ​​are calculated as C ｔ By doing so, the area (S Ａ ) and the area of ​​polyester-based thermoplastic resin B (S Ｂ Compared with conventional eccentric core-sheath composite fibers having the same ratio of C, the centers of gravity of the regions where each resin exists are farther apart, so that the resulting crimped fibers can form a finer spiral, and good crimp can be expressed, resulting in woven and knitted fabrics with excellent bulkiness and softness. Furthermore, in order to obtain crimps suitable for woven and knitted fabrics with bulkiness and softness, ｔ It is more preferable that the C is ≧0.40C. ｔ <C, but C ｔ ≦0.70C is preferred. ｔ As a method for achieving a value of ≧0.33C, for example, a spinning process using a specific distribution plate can be performed, as will be described later.

[0024] Furthermore, the composite fiber of the present invention has an apparent thickness-thinness ratio (D ｔｈｉｃｋ / D ｔｈｉｎ In the present invention, the apparent thick-thin ratio (D ｔｈｉｃｋ / D ｔｈｉｎ The width of a 50 cm composite fiber bundle at a load of 0.11 cN / dtex in the direction perpendicular to the fiber axis direction is measured, and the bundle is divided into a relatively thick portion and a thin portion by the method described in the Examples. The average fiber diameter (D ｔｈｉｃｋ ) and the average fiber diameter (D ｔｈｉｎ The apparent thickness ratio (D ｔｈｉｃｋ / Dｔｈｉｎ ) is theoretically 1.0 or more. ｔｈｉｃｋ / D ｔｈｉｎ If the value of D is greater than 1.04, the abrasion resistance is reduced, and the bulkiness and softness are also reduced. ｔｈｉｃｋ / D ｔｈｉｎ ) is preferably 1.02 or less. ｔｈｉｃｋ / D ｔｈｉｎ ) can be set within the above range by performing pin drawing in a range exceeding the natural draw ratio and then performing a relaxation heat treatment.

[0025] Specific methods for measuring the thickness t, fiber diameter D, thickness ratio, perimeter C, etc. are as described in the Examples.

[0026] The conjugated fiber of the present invention has a crimp elongation of 3.0 to 25.0%. If the crimp elongation is less than 3.0%, bulkiness and abrasion resistance cannot be obtained. The crimp elongation is preferably 5.0% or more. On the other hand, if the crimp elongation is more than 25.0%, the crimp becomes too fine, impairing the bulkiness and softness of the surface of the woven or knitted fabric. Furthermore, if the crimp elongation is too high, the orientation of the thermoplastic resin constituting the conjugated fiber is high, preventing crack formation and resulting in poor color development. The crimp elongation is preferably 15.0% or less. The crimp elongation can be measured by the method described in the Examples.

[0027] The crimp elongation can be set within the above range by subjecting the yarn obtained in the spinning process to pin drawing and a relaxation heat treatment. Pin drawing alone results in a large difference in orientation of the thermoplastic resin constituting the composite fiber, resulting in an excessively large crimp elongation. On the other hand, relaxation heat treatment alone results in a too small difference in orientation of the thermoplastic resin constituting the composite fiber, resulting in an excessively small crimp elongation.

[0028] By simultaneously satisfying the above-mentioned requirements (1) to (5), the present invention can simultaneously solve the problems of conventional blended fiber materials, such as softness, deep coloring, and bulkiness, which are characteristic of woolen fibers, as well as the properties of stretch performance and abrasion resistance.

[0029] The cross-sectional shape of the composite fiber is not particularly limited, and a circular, elliptical, triangular, or other cross-sectional shape can be adopted. However, a circular shape is more preferable because it allows a composite fiber that satisfies the requirements (1) to (5) to be spun stably.

[0030] In the conjugated fiber of the present invention, the area (S Ａ ) and the area of ​​polyester-based thermoplastic resin B (S Ｂ ) and the ratio S Ａ :S Ｂ However, if the ratio is preferably 70:30 to 30:70, more preferably 60:40 to 40:60, the physical properties will be improved. Ａ ≧S Ｂ It is preferable that:

[0031] The average fiber diameter D of the composite fiber in the present invention ａｖｅ The average fiber diameter D is preferably 10 μm to 30 μm. By setting the average fiber diameter D in this range, when the fabric is made into a woven or knitted fabric, it is possible to obtain firmness, stiffness, stretchability, and a soft feel that is closer to that of natural wool materials. ａｖｅ is a value calculated from the fineness of the composite fiber.

[0032] Furthermore, the conjugated fiber of the present invention is preferably twisted to suit the desired purpose. The twisted yarn preferably has a twist coefficient (K) of 6,000 to 24,000. By setting the twist coefficient in this range, it is easier to obtain stretchability and resilience for woven or knitted fabrics. Here, the twist coefficient can be calculated using the following formula.

[0033] Twist coefficient (K) = twist number (T / m) × √(fineness (dtex) × 0.9).

[0034] The conjugated fiber of the present invention usually develops a structure such as crimp due to a thermal history. Examples of the thermal history include hot water treatment and alkali weight reduction treatment, which are carried out in the dyeing process described below. In the present invention, a conjugated fiber that has developed such a structure such as crimp is called a structured yarn.

[0035] The structural yarn of the present invention preferably has cracks around the entire surface of the structural yarn in at least a portion of the fiber length direction. Having cracks around the entire surface of the structural yarn can further enhance the color development of woven and knitted fabrics. Here, "having cracks around the entire surface" may mean that a single crack forms cracks around the entire surface of the structural yarn, or that two or more cracks form cracks around the entire surface of the structural yarn. Furthermore, it is preferable that 10 or fewer cracks form cracks around the entire surface of the structural yarn. More preferably, the cracks are formed in a direction approximately perpendicular to the longitudinal direction of the structural yarn. Even more preferably, the depth of the cracks in the direction approximately perpendicular to the structural yarn varies in the circumferential direction of the fiber. Furthermore, the crack depth is preferably 0.5 to 5.0 μm. Furthermore, the frequency of crack formation is preferably such that 10 or fewer cracks form cracks around the entire surface of the structural yarn within a range of 1 cm in the fiber axis direction. This allows woven and knitted fabrics using the structural yarn to have greater softness and deeper color development.

[0036] Here, the depth of the crack is measured at the deepest point of the crack. Furthermore, "approximately perpendicular to the longitudinal direction of the structural yarn" means that the crack 4 is formed along the circumference, approximately perpendicular to the longitudinal direction of the structural yarn 3, as illustrated schematically in Figure 2. In the present invention, the depth and length of the crack are observed using an electron microscope, and the average value of 10 cracks measured within one structural yarn is used. Specific measurement methods are as described in the Examples. Furthermore, if it is difficult to continuously observe the entire circumference of the structural yarn, it can also be considered that the cracks cover the entire surface if they are uniformly present in any part of the multifilament.

[0037] [Mixed composite fiber, woven / knitted fabric, and clothing containing composite fiber or structural yarn] The composite fiber of the present invention may be one in which at least one other yarn coexists in the form of a mixed mixed composite fiber. That is, the mixed composite fiber of the present invention is one in which at least one other yarn is mixed with the composite fiber of the present invention. This can further improve the abrasion resistance when made into a woven / knitted fabric.

[0038] The other yarns are not particularly limited as long as they are different from the conjugated fiber of the present invention. However, polyester-based resins are preferred because they have good crimp and mechanical properties and are excellent in dimensional stability against changes in humidity and temperature. As polyester-based resins, polyethylene terephthalate resins whose main repeating unit is ethylene terephthalate, polytrimethylene terephthalate resins whose main repeating unit is trimethylene terephthalate, or polybutylene terephthalate resins whose main repeating unit is butylene terephthalate are preferred. The polyethylene terephthalate resins or polybutylene terephthalate resins may optionally contain a small amount (usually less than 30 mol % (assuming the total of the acid component and the diol component is 100 mol %)) of a copolymer component. From the viewpoints of soft texture and fiber-to-fiber recycling, it is more preferred that all of the yarns constituting the mixed-fiber conjugated fiber be polyethylene terephthalate resins containing no covalent components.

[0039] Furthermore, the boiling water shrinkage rate of the other yarns is preferably 10% or less, and particularly preferably 8% or less. When the boiling water shrinkage rate is 10% or less, the softness of the woven or knitted fabric can be further improved. Furthermore, the boiling water shrinkage rate is preferably 0% or more. When the boiling water shrinkage rate is 0% or more, the dimensional stability is excellent. The boiling water shrinkage rate can be determined by measuring the dimensions before and after immersion in hot water at 100°C in accordance with JIS L1013 (2021) 8.18.1a method.

[0040] Furthermore, the other yarns are preferably latently crimped yarns. Here, "latently crimped yarns" refers to yarns with a crimp elongation of 5.0% or more. By using latently crimped yarns as the other yarns, stretchability and bulkiness can be improved.

[0041] When the other yarn is a latent crimp yarn, the crimp elongation of the other yarn is preferably 10.0 to 30.0% higher than the crimp elongation of the composite fiber. By achieving a crimp expression rate within this range, crimps with different coil diameters from the composite fiber are mixed in the mixed composite fiber, thereby achieving bulkiness and softness closer to that of woolen spun yarn. When the difference in crimp expression rate is 10% or more, bulkiness and softness can be further improved. When the difference in crimp expression rate is 30% or less, the difference in coil diameter with the composite fiber is small, preventing separation of the composite fiber from the other yarn.

[0042] In such mixed and composite fibers, the composite fibers in the mixed and composite fibers usually develop a structure such as crimps due to thermal history, as described above. Therefore, the structural yarn of the present invention may be a structural yarn in which at least one other yarn coexists in the form of a mixed mixed and composite fiber. When the other yarn coexisting with the composite fiber in the mixed and composite fiber is a latent crimp fiber, the other yarn will develop a structure such as crimps due to the above thermal history, and will coexist as a visibly crimped fiber with the structural yarn that has developed a structure from the composite fiber.

[0043] The woven or knitted fabric of the present invention contains at least a portion of the conjugate fiber and / or mixed conjugate fiber of the present invention. The woven or knitted fabric may also be composed of only the conjugate fiber or mixed conjugate fiber.

[0044] That is, the woven or knitted fabric of the present invention can be produced by weaving or knitting at least a portion of the composite fiber of the present invention. After the weaving or knitting process, the composite fiber in the woven or knitted fabric becomes a structural yarn with a structure developed therein through a dyeing process and, if necessary, an alkali reduction process. Although the structural yarn with a structure developed in advance may be woven or knitted, the former method is preferred. Such a woven or knitted fabric is a woven or knitted fabric that contains a structural yarn at least in part. As mentioned above, the composite fiber or structural yarn used in the weaving or knitting process may be a composite mixed fiber mixed with other yarns.

[0045] The mixed composite fiber may be a mixed yarn, a composite false twist yarn, or a doubled-twist yarn of the mixed composite fiber and another yarn. Furthermore, by forming a woven or knitted fabric from the mixed composite fiber and another yarn in the form of interlacing or interweaving, greater bulkiness and softness can be obtained.

[0046] In the woven or knitted fabric of the present invention, the proportion of the conjugated fiber and / or mixed conjugated fiber of the present invention used is preferably 30% by mass or more, more preferably 40% by mass or more, based on the mass of the woven or knitted fabric. In another preferred embodiment, all of the fibers constituting the woven or knitted fabric are made of the conjugated fiber and / or mixed conjugated fiber of the present invention.

[0047] The fabric structure of the woven or knitted fabric of the present invention is a woven or knitted fabric. The weave is selected from plain weave, twill weave, satin weave, and variations thereof depending on the texture and design. Furthermore, a multiple weave such as a double weave may be used. The knit weave may be selected depending on the desired texture and design. Examples of weft knitting include plain weave, rib knit, purl knit, tuck knit, float knit, lace knit, and variations thereof. Examples of warp knitting include single denbigh knit, single vandyke knit, single cord knit, Berlin knit, double denbigh knit, atlas knit, cord knit, half tricot knit, satin knit, sharkskin knit, and variations thereof. Among these, relatively simple weave / knit structures such as plain weave or variations thereof, twill weave or variations thereof, and satin weave are more preferred to achieve a delicate worsted texture and a deep, natural appearance.

[0048] Furthermore, the clothing of the present invention at least partially comprises the conjugated fiber (including the structural yarn in which the conjugated fiber has a structure developed), or the mixed conjugated fiber, or the woven or knitted fabric of the present invention. This allows the clothing to satisfy both the stretch performance and abrasion resistance properties of the conjugated fiber (including the structural yarn in which the conjugated fiber has a structure developed), or the mixed conjugated fiber, or the woven or knitted fabric of the present invention, and to exhibit softness, deep color development, and bulkiness. The clothing of the present invention includes items in the field of outerwear worn as women's and men's clothing, sportswear, and outdoor clothing, particularly jackets, suits, bottoms, and parts thereof, such as those including the front body, back body, collar, sleeves, chest pocket, and side pocket, as well as innerwear, socks, hats, etc.

[0049] [Methods for producing the conjugated fiber, structural yarn, mixed conjugated fiber, and woven / knitted fabrics from which the structure is developed] Next, an example of a preferred method for producing the conjugated fiber of the present invention, structural yarn, mixed conjugated fiber, and woven / knitted fabrics from which the structure is developed will be described.

[0050] The conjugated fiber of the present invention can be produced by winding up the extruded thermoplastic resin as an undrawn or semi-drawn yarn, drawing it once, and subjecting it to a relaxation heat treatment. In particular, conjugated fibers obtained by winding up the extruded thermoplastic resin as a semi-drawn yarn and then drawing it are preferred because the difference in orientation between the polyester-based thermoplastic resin A and the polyester-based thermoplastic resin B results in excellent stretchability when made into a woven or knitted fabric and dyed, and the high orientation of the polyester resin A results in excellent resistance to embrittlement due to alkali reduction.

[0051] [Spinning Step] In the method for producing the conjugated fiber of the present invention, first, polyester-based thermoplastic resin A and polyester-based thermoplastic resin B are each melted, extruded from a spinneret, and wound up as an undrawn yarn or a semi-drawn yarn at a spinning speed of preferably 1400 m / min to 3800 m / min. In the present invention, it is preferable to wind up as a semi-drawn yarn at a spinning speed of 2500 to 3800 m / min.

[0052] The semi-drawn yarn is preferably made into a composite fiber because it has excellent abrasion resistance after alkali reduction. The semi-drawn yarn is more crystallized than the undrawn yarn, which can prevent localized fiber breakage due to alkali reduction.

[0053] The spinning temperature was determined based on the melting points (T ｍＡ , T ｍＢ ) is preferably +20°C to +50°C. ｍＡ , T ｍＢ ) +20°C or higher, it is possible to prevent the molten polyester-based thermoplastic resin A and the molten polyester-based thermoplastic resin B from solidifying and clogging the inside of the spinning machine piping. ｍＡ , T ｍＢ ) +50°C or less, thermal degradation of the molten polyester-based thermoplastic resin A and the molten polyester-based thermoplastic resin B can be suppressed.

[0054] The spinneret used in the method for producing the composite fiber of the present invention may have any known internal structure as long as it is capable of spinning with high quality and stable operation.

[0055] Here, in the cross section of the conjugated fiber of the present invention, as described above, the polyester-based thermoplastic resin A is completely covered with the polyester-based thermoplastic resin B. By forming the conjugated fiber into such a cross section, it is possible to suppress the bending of the discharge line caused by the difference in flow speed between the two types of thermoplastic resins discharged from the spinneret, which is an issue during the production of conjugated fibers.

[0056] As described above, the composite fiber of the present invention has a minimum thickness t of the polyester thermoplastic resin B covering the polyester thermoplastic resin A. ｍｉｎ The thickness t of the cross section of the composite fiber is 1.00t ｍｉｎ ≦t≦1.05t ｍｉｎ The length C of the overlapping portion of the region satisfying the above and the periphery of the composite fiber ｔ It is preferable to precisely control the temperature and the amount of the fiber, and a spinning method using a distribution plate, as exemplified in JP-A Nos. 2011-174215, 2011-208313, and 2012-136804, is preferably used. By using such a distribution plate, ｍｉｎ can be within the ranges described above, and t ｍｉｎ This can suppress the exposure of the polyester thermoplastic resin A that occurs as a result of excessively small t, and can also suppress whitening and fluffing of the woven or knitted fabric. ｍｉｎ In the method using such a distributor plate, the cross-sectional form of the single yarn can be controlled by the arrangement of the distribution holes in the final distributor plate, which is the most downstream of the plurality of distributor plates.

[0057] [Drawing and relaxation heat treatment process] Next, the yarn produced through the spinning process described above is drawn at a draw ratio exceeding the natural draw ratio of the yarn using a drawing and relaxation heat treatment device such as the one shown in Figure 3, and then subjected to a relaxation heat treatment to form a relaxation heat-treated yarn. Through this process, a desired composite fiber can be obtained.

[0058] 3 is a schematic diagram of a drawing and relaxation heat treatment apparatus used in producing the composite fiber of the present invention. Specifically, after passing through a guide 6, a semi-drawn yarn 5 is heated and drawn by a hot pin 8 between a first feed roller 7 and a second feed roller 9, and is further subjected to a relaxation heat treatment by a heater 10 between the second feed roller 9 and a third feed roller 11 to form a composite fiber 12, which is then wound up on a winding section 13.

[0059] For example, a semi-drawn yarn obtained by conjugate spinning at a spinning speed of 2500 to 3800 m / min is pin-drawn at a draw ratio of 1.5 to 2.2, a hot pin temperature of 70 to 150°C, and a yarn speed of 200 to 800 m / min, and then subjected to a relaxation heat treatment at a heater temperature of 130 to 180°C and an overfeed rate of +25 to 55% (as an example, a semi-drawn yarn obtained by conjugate spinning at a spinning speed of 2600 m / min is pin-drawn at a draw ratio of 1.8, a hot pin temperature of 95°C, and a yarn speed of 300 m / min, and then subjected to a relaxation heat treatment at a heater temperature of 140°C and an overfeed rate of +10%), thereby obtaining a conjugate fiber having an apparent thickness ratio of 1.00 to 1.04 and a crimp elongation of 3.0 to 25.0%. The stretching is preferably performed in a range equal to or greater than the upper limit of the natural stretch ratio, and the overfeed rate in the relaxation heat treatment is preferably 50% or less of the stretch ratio. By stretching within the above range, it becomes easier to control the degree of fiber weight loss due to alkali treatment, and both softness and abrasion resistance can be achieved.

[0060] Furthermore, the drawn composite fiber may be mixed with other yarns before or after winding to form a mixed composite fiber. The mixing method is not particularly limited, and general methods such as interlace mixing and taslan mixing are also acceptable.

[0061] [Process for forming woven or knitted fabrics] The composite fibers obtained in the drawing process are made into woven or knitted fabrics. In the case of woven fabrics, they are woven using an air jet loom, water jet loom, rapier loom, projectile loom, shuttle loom, etc. In the case of knitted fabrics, they are knitted using a weft knitting machine such as a flat knitting machine, fully fashioned knitting machine, circular knitting machine, computer jacquard knitting machine, sock knitting machine, or tubular knitting machine, or a warp knitting machine such as a tricot knitting machine, Russell knitting machine, air jet loom, or Milanese knitting machine.

[0062] [Alkali weight reduction step] Furthermore, the woven or knitted fabric obtained in the above-mentioned woven or knitted fabric formation step is subjected to an alkali weight reduction treatment, if necessary, so that the alkali weight reduction rate is 5 to 20%, more preferably 10 to 15%. This step makes it possible to create a state in which cracks exist on the entire surface of the above-mentioned composite fiber. Furthermore, a continuous weight reduction process is preferred to avoid embrittlement due to selective weight reduction.

[0063] [Dyeing Process] Furthermore, if necessary, before and / or after, or simultaneously with, the above-mentioned alkali weight reduction process, conventional scouring, relaxation treatment, intermediate heat setting, dyeing processing, and finishing heat setting may be performed (in the present invention, these processes may be collectively referred to as the "dyeing process"). To obtain the bulkiness and softness of the present invention, the feed and tension in each process are appropriately controlled. For example, in equipment such as a roll-to-roll system that can control the feed amount in the axial direction of the composite fiber of the present invention, it is desirable to control the overfeed to within 10%, and in a batch-type jet dyeing machine, the liquid volume and flow rate to avoid excessive tension in the direction of travel. Dyeing is carried out using a disperse dye or a cationic dye in a dyeing solution preferably at 110 to 130°C, although this depends on the dyeability of the thermoplastic resin that constitutes the composite fiber or the other yarns that are combined.

[0064] The conjugated fiber of the present invention usually develops structure and crimp due to the heat history in the dyeing step or the alkali reduction step, and cracks are formed on the surface of the conjugated fiber by the alkali reduction step.

[0065] Next, the present invention will be specifically described based on examples. However, the present invention is not limited to these examples. In addition, in the measurement of each physical property, unless otherwise specified, the measurement was performed according to the above-mentioned method.

[0066] [Measurement Method] (1) Measurement of Weight Average Molecular Weight of Thermoplastic Resin The weight average molecular weight of the polyester thermoplastic resin A and polyester thermoplastic resin B used in the composite fiber was measured using a gel permeation chromatography (GPC) tester "TOSO GMHHR-H(S)HT" manufactured by Tosoh Corporation.

[0067] Detector: Differential refractive index detector RI (Waters-2414, sensitivity 128x) Column: Shodex HFIP806M (two columns connected) manufactured by Showa Denko K.K. Solvent: Tetrahydrofuran (25 cm ３ ) Flow rate: 1.0 mL / min Column temperature: 30°C Injection volume: 0.10 mL Standard material: polystyrene.

[0068] (2) Average fiber diameter D ａｖｅ The fineness and number of filaments of the composite fiber were measured in accordance with JIS L1013 (2010) 8.3.1B and JIS L1013 (2010) 8.4, respectively, and the single fiber fineness was obtained by dividing the fineness by the number of filaments. The average fiber diameter was calculated from the obtained single fiber fineness using the following formula.

[0069]

[0070] ρ: Density (g / m ３ ) For polyethylene terephthalate, 1.38 x 10 ６ g / m ３ .

[0071] (3) Measurement of fiber diameter D, thickness t of polyester thermoplastic resin B covering polyester thermoplastic resin A, and fiber perimeter C. A multifilament made of composite fiber was embedded in an embedding agent such as epoxy resin at 10 consecutive locations at 1 cm intervals along the fiber axis. Images of each sample were taken using a transmission electron microscope (TEM) at a magnification that allowed observation of 10 or more fibers. Metal staining was applied to enhance the contrast of the junctions between polyester thermoplastic resin A and polyester thermoplastic resin B. Using image analysis software "WinROOF2015" manufactured by Mitani Shoji Co., Ltd., the fiber diameter D, the perimeter C, the thickness t of polyester thermoplastic resin B, and the area Sa of polyester thermoplastic resin A in the cross section were measured for all single yarns in the observed image. The fiber diameter D is the equivalent circle diameter. Ten sets of fiber diameter D, perimeter C, thickness t, and area fraction Sa of polyester thermoplastic resin A were prepared and averaged. The fiber diameter D was calculated to three significant figures, and the perimeter C, thickness t, and area ratio Sa were calculated to two significant figures, and these were defined as the fiber diameter D, perimeter C, thickness t, and area ratio Sa of the present invention. The thickness t was measured at 360 points every 1° in the circumferential direction of the fiber, and the smallest one was determined as t ｍｉｎ , thickness t is 1.00t ｍｉｎ ≦t≦1.05t ｍｉｎ The length of the overlapping portion of the region satisfying the above and the periphery of the composite fiber is defined as C ｔ The area ratio Sa of the polyester thermoplastic resin A was subtracted from the total area S of the cross section to obtain the area ratio Sb of the polyester thermoplastic resin B.

[0072] (4) Crimp Elongation Ratio The crimp elongation ratio of the composite fiber was calculated using the following formula.

[0073] Crimp elongation (%) = [(L1 - L0) / L0] x 100 L0: 50 cm of composite fiber was wrapped in gauze in a free state and left for 24 hours, then treated with hot water at 100°C for 15 minutes under no load, dried at 20°C and 65% RH for 24 hours, and then the crimp elongation was 1.1 x 10 －３L1: The length 30 seconds after hanging a load of 0.22 cN / dtex after measuring L0. The measurement was performed 10 times, and the average value was rounded to one decimal place. In the case of a mixed fiber composite fiber, the composite fiber was separated and measured before measuring L0.

[0074] (5) Apparent Thickness / Thinness Ratio (D ｔｈｉｃｋ / D ｔｈｉｎ Both ends of the composite fiber were fixed under a load of 0.11 cN / dtex. The side of the fixed sample was photographed at 200x magnification using a digital microscope "VHX2000" manufactured by Keyence Corporation, and the diameter of the fiber bundle was measured at 500 points at 1.0 mm intervals in the fiber axis direction. The fiber diameter (D ｔｈｉｃｋ ) and the fiber diameter (D ｔｈｉｎ The apparent thickness ratio was calculated by determining the average value of the thick and thin parts. The apparent thickness ratio was calculated by rounding off the third decimal place to two decimal places.

[0075] In addition, the apparent thickness ratio was determined in the same manner for structural yarns extracted from woven or knitted fabrics after the dyeing process (finishing heat setting).

[0076] (6) Measurement of the Presence and Depth of Cracks A random location of the structural yarn from the dyed woven or knitted fabric was observed using an electron microscope, a Hitachi, Ltd. S-3400N scanning electron microscope. The composite fiber was pulled out of the woven or knitted fabric after the final heat setting without applying external force, and the presence or absence of cracks and their shape were confirmed. If cracks were present, the side surface in a direction approximately perpendicular to the cracks was observed at 2000x magnification. The deepest depth and length of the crack were measured, and the average value of 10 cracks measured within one composite fiber was taken as the crack depth. The crack shape was evaluated according to the following criteria: A. A form in which 10 or fewer cracks form cracks around the entire surface of the structural yarn within a 1 cm range in the fiber axis direction. B. A form in which 10 or fewer cracks form cracks around the entire surface of the structural yarn. C. Cracks are formed, but the cracks are intermediate between B and C. D. Cracks are formed, but only extend halfway around the surface of the structural yarn. E. Between D and F. F. No cracks form.

[0077] (7) Stretchability of woven / knitted fabrics The elongation percentage in the direction along the conjugated fiber of the present invention was measured according to JIS L1096 (2010) 8.16.1B. When the conjugated fiber of the present invention was used in both the warp and weft directions, the elongation percentages in each direction were measured, and the average value was used as the result.

[0078] (8) Abrasion Resistance The woven / knitted fabric was dyed black, and the dyed woven / knitted fabric was cut into a circle with a diameter of 10 cm. The circle was then moistened with distilled water and attached to a disk. Further, 30 cm square pieces of the woven / knitted fabric were cut out and fixed on a horizontal plate while still dry. The disk with the woven / knitted fabric moistened with distilled water attached was brought into horizontal contact with the woven fabric fixed on the horizontal plate, and the disk was moved circularly at a speed of 50 rpm for 10 minutes so that the center of the disk drew a circle with a diameter of 10 cm, causing friction between the two woven / knitted fabrics. After the friction was completed and the fabric was left to stand for 4 hours, the degree of discoloration of the woven / knitted fabric attached to the disk was graded from 1 to 5 in increments of 0.5 using a gray scale for discoloration.

[0079] (9) Evaluation of color development, bulkiness, and softness of woven and knitted fabrics using composite fiber and mixed composite fiber Samples of woven and knitted fabrics formed using the composite fiber of the present invention were evaluated by 10 healthy adults (5 men and 5 women) who visually inspected the color development of the woven and knitted fabrics and by touching the bulkiness and softness, evaluating them on a 5-point scale of excellent (5 points), good (4 points), average (3 points), not very good (2 points), and poor (1 point). The average values ​​of the examiners were rounded to one decimal place. For comparison, woven fabrics made of polyethylene terephthalate false twist textured yarns with the same total fineness and filament count as those in the Examples and Comparative Examples were rated average (3 points).

[0080] Example 1 Polyester thermoplastic resin A was polyethylene terephthalate with a weight-average molecular weight of 25,000, and polyester thermoplastic resin B was polyethylene terephthalate with a weight-average molecular weight of 15,000. The spinning temperature was 290°C, and the polyester thermoplastic resins A and B were mixed in a mass conjugation ratio of 50:50. The distribution holes in the final distributor plate, which was the most downstream of the multiple distributor plates, were arranged as shown in Figure 4, and the resins were allowed to flow into a conjugate fiber spinneret with 12 outlet holes. Figure 4 shows the final distributor plate, with a group of distribution holes 15 for polyester thermoplastic resin B arranged around a group of distribution holes 14 for polyester thermoplastic resin A. In this way, an eccentric core-sheath type (Figure 1) composite cross section was formed in which polyester thermoplastic resin A was contained in polyester thermoplastic resin B. The yarn discharged from the spinneret was cooled by an air cooler, oiled, and then wound up at a speed of 2600 m / min by a winder, and stably wound up as a semi-drawn yarn with a total fineness of 100 dtex and 12 single filaments.

[0081] Subsequently, the obtained semi-drawn yarn was fed to a drawing device at a speed of 300 m / min, and pin-drawn using a drawing device such as that shown in FIG. 3 at a draw ratio of 1.80 and a hot pin temperature of 95°C. After that, a relaxation heat treatment was performed at a heater temperature of 140°C and an overfeed rate of +20%, thereby obtaining an apparent thickness ratio (D ｔｈｉｃｋ / D ｔｈｉｎ A composite fiber having a t ) of 1.02 was obtained.ｍｉｎ / D) is 0.020, C ｔ The relationship between and C is C ｔ = 0.40C (C ｔ / C=0.40). Ａ :S Ｂ The ratio was 50:50.

[0082] Next, the above composite fibers were twisted at 1200 T / m and used as warp and weft yarns to produce a 3 / 1 twill fabric with a warp density of 115 threads / 2.54 cm and a weft density of 105 threads / 2.54 cm.

[0083] The fabric was further subjected to scouring, relaxation, and intermediate heat setting. Thereafter, in the dyeing process, the fabric was dyed using the disperse dye "Dystar Navy Blue S-GL" at a concentration of 1.0 owf% at a temperature of 130°C for 30 minutes, and then subjected to a finishing heat setting at 160°C. The results are shown in Table 1.

[0084] [Example 2] A composite fiber and a woven fabric were obtained in the same manner as in Example 1, except that in the dyeing process, an alkali weight reduction process (weight reduction rate 10%) was performed after the intermediate setting to form cracks on the surface of the single yarn of the composite fiber. The results are shown in Table 1.

[0085] [Example 3] The conjugated fiber produced in Example 1 was mixed and entangled with polyethylene terephthalate fiber (56 dtex-24f, boiling water shrinkage of 8%, crimp elongation of 0.0%) as another yarn using an interlace nozzle to obtain a mixed conjugated fiber with a conjugated fiber blend ratio of 54%, and a woven fabric was obtained in the same manner as in Example 2, except that the warp density was 88 threads / inch and the weft density was 79 threads / inch (2.54 cm). The results are shown in Table 1. The boiling water shrinkage was determined by measuring the dimensional change before and after immersion in hot water at 100°C in accordance with JIS L1013 (2021) 8.18.1a.

[0086] [Example 4] A woven fabric was obtained in the same manner as in Example 3, except that the following drawn yarn was used as the other yarn. The results are shown in Table 1.

[0087] Drawn yarn: Polyethylene terephthalate having a weight-average molecular weight of 25,000 and polyethylene terephthalate having a weight-average molecular weight of 15,000 were fed into a side-by-side conjugated fiber spinneret having 12 outlet holes so that the spinning temperature was 290°C and the mass conjugation ratio of the respective polyethylene terephthalates was 50:50. The yarn discharged from the spinneret was cooled and oiled with an air cooler, then taken up at 1,500 m / min, and stretched to 2.67 times its original length between a preheated roller at 80°C and a roller at 4,000 m / min. After heat setting at 130°C, the yarn was wound up on a winder and stably wound up as a drawn yarn having a total fineness of 56 dtex, 12 single filaments, and a crimp elongation of 32.0%.

[0088] [Example 5] A woven fabric was obtained in the same manner as in Example 2, except that polyester-based thermoplastic resin A was a polyester having a weight-average molecular weight of 19,000 and polyester-based thermoplastic resin B was a polyester having a weight-average molecular weight of 15,000. The results are shown in Table 1.

[0089] [Example 6] A woven fabric was obtained in the same manner as in Example 2, except that polyester-based thermoplastic resin A was a polyester having a weight average molecular weight of 25,000, in which isophthalic acid (IPA) was copolymerized at 10 mol % relative to the acid component. The results are shown in Table 1.

[0090] [Example 7] A woven fabric was obtained in the same manner as in Example 4, except that the heat setting temperature of the other yarns was 125°C and the boiling water shrinkage was 10%. The results are shown in Table 1.

[0091] [Example 8] A woven fabric was obtained in the same manner as in Example 3, except that the following drawn yarn was used as the other yarn. The results are shown in Table 1.

[0092] Drawn yarn: A polyethylene terephthalate having a weight-average molecular weight of 25,000, in which 10 mol % of isophthalic acid (IPA) was copolymerized with respect to the acid component, and a polyethylene terephthalate having a weight-average molecular weight of 15,000, were fed into a side-by-side conjugated fiber spinneret with 12 nozzle holes so that the spinning temperature was 290°C and the mass conjugation ratio of the respective polyethylene terephthalates was 50:50. The yarn discharged from the spinneret was cooled by an air cooler, oiled, and then taken up at 1,500 m / min. It was then stretched 2.67 times between a preheated roller at 80°C and a roller at 4,000 m / min, heat-set at 130°C, and then wound up by a winder to stably wind up as a drawn yarn with a total fineness of 56 dtex and 12 single filaments.

[0093] Comparative Example 1 A woven fabric was obtained in the same manner as in Example 4, except that the spinneret used in Example 4 was replaced from a distributor plate type spinneret with a spinneret of the type described in JP-A-09-157941, and side-by-side composite fibers composed of polyester-based thermoplastic resin A and polyester-based thermoplastic resin B were used. The resulting woven fabric had low abrasion resistance due to peeling of the side-by-side composite cross section caused by abrasion, and poor color development due to exposure of the high-molecular-weight polyethylene terephthalate, which has low color development properties. The results are shown in Table 2.

[0094] Comparative Example 2 A woven fabric was obtained in the same manner as in Example 4, except that a relaxation heat treatment was performed without pin drawing. The resulting woven fabric had poor abrasion resistance due to local fiber breakage caused by the alkali treatment, and poor bulkiness due to a low crimp elongation of the composite fiber. The results are shown in Table 2.

[0095] Comparative Example 3 A woven fabric was obtained in the same manner as in Example 4, except that pin drawing was performed and no relaxation heat treatment was performed. The obtained woven fabric had poor color development due to the high orientation of the composite fibers, and was also poor in bulkiness and softness due to an excessively high crimp elongation. The results are shown in Table 2.

[0096] Comparative Example 4 A woven fabric was obtained in the same manner as in Example 4, except that the pin draw ratio was 1.50, the heat treatment overfeed rate was 0%, and the composite fiber had an apparent thickness ratio of 1.22 and a crimp elongation of 27.0%. The resulting woven fabric had low abrasion resistance in the thick portions and poor softness due to the high crimp elongation. The results are shown in Table 2.

[0097] Comparative Example 5 A woven fabric was obtained in the same manner as in Example 4, except that the pin draw ratio was set to 1.50 to produce a conjugate fiber with an apparent thickness-to-thin ratio of 1.22. The resulting woven fabric had poor abrasion resistance in the thick portions and a low crimp elongation, resulting in poor bulkiness and softness. The results are shown in Table 2.

[0098] [Comparative Example 6] In Example 4, the minimum value t of the thickness t of the polyester thermoplastic resin B covering the polyester thermoplastic resin A was ｍｉｎ The arrangement of the distribution holes of the final distribution plate of the spinneret used was changed from that shown in FIG. 4 to that shown in FIG. 5 so that the value of (t ｍｉｎ A woven fabric was obtained in the same manner as in Example 4, except that the core-sheath type composite fiber having a fiber-reinforced bond ratio (fiber-reinforced bond ratio) of 0.20 was used. The results are shown in Table 2.

[0099] Comparative Example 7 A woven fabric was obtained in the same manner as in Example 2, except that polyester-based thermoplastic resin A was polyethylene terephthalate having a weight-average molecular weight of 20,000 and polyester-based thermoplastic resin B was polyethylene terephthalate having a weight-average molecular weight of 19,000. The results are shown in Table 2.

[0100]

[0101]

[0102] 1: Polyester-based thermoplastic resin A 2: Polyester-based thermoplastic resin B 3: Composite fiber 4: Crack 5: Semi-stretched yarn 6: Guide 7: First feed roller 8: Hot pin 9: Second feed roller 10: Heater 11: Third feed roller 12: Composite fiber 13: Winding section 14: Distribution hole for polyester-based thermoplastic resin A 15: Distribution hole for polyester-based thermoplastic resin B 16: Thickness t of polyester-based thermoplastic resin B covering polyester-based thermoplastic resin A

Claims

1. A composite fiber comprising polyester thermoplastic resin A and polyester thermoplastic resin B, and satisfying the following requirements. (1) The weight-average molecular weight M of the polyester thermoplastic resin A. Ａ and the weight-average molecular weight M of the polyester thermoplastic resin B. Ｂ The difference (M Ａ -M Ｂ ) is between 2000 and 15000. (2) The apparent thickness ratio of the composite fiber (D ｔｈｉｃｋ / D ｔｈｉｎ The value is between 1.00 and 1.

04. (3) The crimp elongation rate of the composite fiber is 3.0 to 25.0%. (4) In the cross-section of the composite fiber, the polyester thermoplastic resin B covers the polyester thermoplastic resin A, and the minimum value of the thickness t of the polyester thermoplastic resin B is t ｍｉｎ The ratio (t) of the fiber diameter D of the composite fiber ｍｉｎ The value of / D) is between 0.01 and 0.

10. (5) In the cross-section of the composite fiber, the thickness t is 1.00t ｍｉｎ ≦ t ≦ 1.05t ｍｉｎ The length C of the overlapping part between the region satisfying this and the peripheral line of the composite fiber ｔ is such that C ｔ ≧ 0.33C. (6) At least one other type of yarn coexists in the form of a blended composite fiber, wherein the other yarn is a latent crimped yarn.

2. A composite fiber comprising the composite fiber described in Claim 1 and at least one other yarn, wherein the other yarn is a latent crimped yarn.

3. A structural yarn having cracks formed around the entire surface of the composite fiber according to claim 1.

4. The structural yarn according to claim 3, wherein the other yarn is a visible crimped yarn.

5. A woven or knitted fabric made by weaving or knitting using at least a portion of the composite fiber described in claim 1.

6. A woven or knitted fabric made by weaving or knitting using at least a portion of the blended composite fibers described in Claim 2.

7. A woven or knitted fabric comprising at least a portion of the structural yarn described in claim 3.

8. A garment comprising at least a portion of the woven or knitted fabric described in any one of claims 5 to 7.