WO2024070726A1

WO2024070726A1 - Composite fiber, multifilament, woven article, and textile product

Info

Publication number: WO2024070726A1
Application number: PCT/JP2023/033522
Authority: WO
Inventors: 知彦松浦; 正人増田; 健太郎小河; 慎也川原; 康二郎稲田
Original assignee: 東レ株式会社
Priority date: 2022-09-29
Filing date: 2023-09-14
Publication date: 2024-04-04

Abstract

The problem to be solved by the invention is to provide: a composite fiber that is suited for clothing textile, inhibits a lowering of surface quality caused by friction/wear etc., with another material, while having a flexible texture with a soft feel or resilient feel, and exhibits high water repellency when having been subjected to water repellent processing; a multifilament; a woven article; and a textile product.　This composite fiber has two types of segments A and B present in a cross-section of the fiber, wherein the segment B has a smaller cross-sectional area than the segment A and is formed of two types of polymers composited into a side-by-side type or eccentric core-sheath type.

Description

Composite fibers, multifilaments, woven fabrics and textile products

The present invention relates to composite fibers, multifilaments, woven and knitted fabrics, and textile products.

Synthetic fibers made from polyester, polyamide, etc. have excellent mechanical properties and dimensional stability, so they are widely used in a variety of applications, from clothing to non-clothing.

Work clothes, school uniforms, etc. are often worn every day, but the factory workers and students who wear them are very active and prone to pilling and wear, so relatively durable fabrics are used. Therefore, in order to increase durability, the fabrics used for these products often use thick, highly rigid fibers and are made with a structure in which the warp and weft threads are tightly crossed and strongly bound to each other. For this reason, they can be inferior in feel and flexibility compared to textiles used in general clothing, which can hinder comfort and ease of wear.

Furthermore, because these textiles have low warp and weft elasticity, the constituent fibers are constrained, and as a result of friction and abrasion with other materials, such as rubbing against the floor or ironing, or wearing for long periods of time, the glossiness of the parts that wear over time increases, resulting in a so-called shine phenomenon, which can reduce the surface quality of the textile. This shine phenomenon occurs when the uneven structure of the textile surface becomes flattened due to deformation and wear of the fibers, increasing light reflection, and a method of adding smoothing agents such as silicone or polyethylene wax in post-processing has been proposed as a method of suppressing this phenomenon.

The method of adding a smoothing agent in post-processing aims to reduce the friction of the fiber surface with the smoothing agent, thereby suppressing deformation and wear of the fibers and preventing the occurrence of a shiny phenomenon caused by flattening the textile surface. However, this method can lead to hardening of the texture due to the smoothing agent adhering to the fabric, and can also result in poor durability due to the smoothing agent falling off during washing, etc.

As a result, various textile technologies have been proposed that, rather than relying on post-processing, can reduce the shine phenomenon in textiles without compromising texture or durability by modifying the cross-section and shape of the fibers.

Patent Document 1 proposes a composite fiber in which a low-melting-point polymer with a melting point lower than that of polyester is disposed inside polyester fibers. In this composite fiber, frictional heat generated by rubbing against the floor, etc., is absorbed by the heat absorption action caused by melting of the low-melting-point polymer in the core before the polyester melts, suppressing fiber deformation caused by melting of the polyester and suppressing the shine phenomenon in textiles.

Furthermore, Patent Document 2 proposes a false twist textured yarn obtained from an air entangled yarn in which a multifilament made of self-extensible polyester fiber is used as the sheath yarn, and a multifilament made of polyester fiber having a higher boiling water shrinkage rate than the sheath yarn is used as the core yarn. In textiles using this textured yarn, the sheath yarn is looped around the core yarn by air entanglement to form a gap between the core yarn and the sheath yarn, resulting in a soft texture, while false twisting further imparts slight crimping, reducing the collapse of the gap between the core yarn and the sheath yarn due to pressure, and suppressing the shine phenomenon when ironing.

JP 2017-186680 A (Claims) JP 2000-314038 A (Claims)

If frictional heat can be absorbed by using a low-melting point polymer, as in Patent Document 1, it may be possible to suppress fiber deformation caused by melting of the polymer.

However, the technical idea behind Patent Document 1 is to suppress the shine caused by frictional heat that is generated momentarily when the textile rubs against the floor, etc., and when the textile made of the composite fiber of Patent Document 1 is worn for a long period of time, the textile surface may gradually become flattened due to wear against other materials and crushing due to pressure, resulting in the shine phenomenon. Furthermore, from the perspective of interfacial peeling between polyester and low-melting point polymer, the fiber diameter and fiber form are limited to ensure abrasion resistance, which may result in inferior feel and flexibility.

In addition, as in Patent Document 2, by looping the sheath yarn around the core yarn through air entanglement to form a gap between the core yarn and the sheath yarn, and then imparting a slight crimp through false twisting, it is possible to reduce the collapse of the gap between the core yarn and the sheath yarn due to pressure, and to suppress the shine phenomenon caused by momentary pressure when ironing, etc.

However, when a textile made of the processed yarn of Patent Document 2 is worn for a long period of time, friction is applied to the sheath yarn when it is crushed by pressure, which can cause the core yarn and sheath yarn to wear together and gradually flatten the surface of the processed yarn, resulting in a shiny phenomenon. Furthermore, friction can cause the sheath yarn to be pulled out, leading to fuzzing, and thus poor durability.

As mentioned above, although there is fiber technology that can suppress the shine caused by momentary frictional heat or pressure, there is no fiber technology that can suppress the shine caused by wear against other materials when worn for long periods of time, making it difficult to simultaneously achieve the feel, texture, and functionality that are important for clothing textiles.

The present invention aims to solve the problems of the conventional technology described above, and to provide composite fibers, multifilaments, woven and knitted fabrics and textile products suitable for clothing textiles that have a smooth feel and a soft texture with a sense of resilience, while suppressing the deterioration of surface quality caused by friction and abrasion with other materials, and that exhibit high water repellency when subjected to a water repellent treatment.

The object of the present invention is achieved by the following means:
(1) A composite fiber having two types of segments A and B in the fiber cross section, where segment B has a smaller cross-sectional area than segment A and is formed of two types of polymers that are composited in a side-by-side or eccentric core-sheath configuration;
(2) The composite fiber according to (1) above, in which three or more segments B are arranged on the outer periphery of a segment A in a fiber cross section.
(3) The composite fiber according to (1) or (2) above, in which the cross-sectional area S _B of each segment B in the fiber cross section is 1 μm ² ≦ S _B < 65 μm ² .
(4) A sea-island composite fiber according to any one of (1) to (3) above, in which the segments A and B are island components, and the sea component is formed of a polymer that has the highest dissolution rate in a solvent among the polymers constituting the sea-island composite fiber.
(5) A multifilament obtained by dividing segments A and B from the conjugate fiber according to any one of (1) to (4) above.
(6) A textile product at least partially containing the multifilament according to (5).
(7) A multifilament consisting of two types of filaments A and B, in which one or more filaments B are present between any two filaments A in the multifilament, and the filament B has a smaller fiber diameter than the filament A, and is formed of two types of polymers composited in a side-by-side type or eccentric core-sheath type.
(8) The multifilament according to (7) above, wherein the fiber diameter D _B of the filament B is 1 μm≦D _B <9 μm.
(9) A woven or knitted fabric at least partially containing the multifilament according to (7) or (8).
(10) The woven or knitted fabric according to (9) above, which has been subjected to a water-repellent treatment.
(11) A water-repellent woven or knitted fabric comprising a multifilament consisting of two types of filaments A and B, in which one or more filaments B are present between any two filaments A in the multifilament, the filament B having a smaller fiber diameter than the filament A and formed of two types of polymers composited in a side-by-side or eccentric core-sheath type, and having a water drop sliding angle of 1 to 20 degrees.
(12) The woven or knitted fabric according to (11), wherein the difference in water droplet sliding angle before and after 20 cycles of washing according to JIS L1930-2014-C4M method and drying according to A method (hang-dry) is 0 to 20 degrees;
(13) The woven or knitted fabric according to (11) or (12), which has a fluorine content of 25 ng/g or less as measured by combustion ion chromatography.
It is.

The composite fibers, multifilaments, woven/knitted fabrics, and textile products of the present invention have a special fiber morphology in which the cross-sectional arrangement within the composite fibers and the fiber arrangement within the multifilaments are precisely controlled, so that they have a smooth feel and a soft texture with a bouncy feel, while suppressing the deterioration of surface quality caused by friction and abrasion with other materials, and furthermore, due to their fine and complex surface irregularities, it is possible to obtain textiles that exhibit high water-repellent performance when water-repellent processing is applied.

1A, 1B, 1C, and 1D are schematic diagrams showing an example of a cross-sectional structure of the conjugate fiber of the present embodiment. 2(a), (b), and (c) are schematic diagrams showing an example of a cross-sectional structure of the conjugate fiber of the present embodiment. 3(a) and (b) are schematic diagrams showing an example of a cross-sectional structure of a conventional composite fiber. FIG. 4 is a diagram for understanding that one or more filaments B exist between any two filaments A in the multifilament of this embodiment, and the dashed lines of the outer frame represent the top, bottom, left and right sides of the photographed image. 5(a) and (b) are schematic diagrams showing an example of the cross-sectional structure of the filaments constituting the multifilament of this embodiment, where (a) of Fig. 5 is a schematic diagram of the cross-sectional structure of filament A, and (b) of Fig. 5 is a schematic diagram of the cross-sectional structure of filament B. 6A, 6B, and 6C are schematic diagrams showing an example of a cross-sectional structure of a filament constituting the multifilament of this embodiment, in which 6A is a schematic diagram of the cross-sectional structure of a filament A, and 6B and 6C are schematic diagrams of the cross-sectional structure of a filament B. 7A and 7B are schematic diagrams showing an example of the cross-sectional structure of the filaments constituting the multifilament of this embodiment, where (a) of Fig. 7 is a schematic diagram of the cross-sectional structure of filament A, and (b) of Fig. 7 is a schematic diagram of the cross-sectional structure of filament B. 8A and 8B are schematic diagrams showing an example of the cross-sectional structure of the filaments constituting the multifilament of this embodiment, where FIG. 8A is a schematic diagram of the cross-sectional structure of filament A, and FIG. 8B is a schematic diagram of the cross-sectional structure of filament B. 9(a) and 9(b) are schematic diagrams showing an example of the cross-sectional structure of the filaments constituting the multifilament of this embodiment, where (a) of Fig. 9 is a schematic diagram of the cross-sectional structure of filament A, and (b) of Fig. 9 is a schematic diagram of the cross-sectional structure of filament B. 10(a) and (b) are schematic diagrams showing an example of a cross-sectional structure of a filament constituting a conventional multifilament. FIG. 11 is a schematic diagram showing an example of a cross-sectional structure of a filament constituting a conventional multifilament. FIG. 12 is a cross-sectional view of a spinneret for explaining the method for producing the composite fiber and multifilament of this embodiment.

The present invention will be described in detail below along with preferred embodiments.

A detailed analysis of the shine phenomenon that occurs when conventional materials are worn against other materials revealed that the shine does not necessarily increase in areas where a single fiber is worn away and flattened due to fiber wear, but rather where the flat parts of multiple fibers are lined up side by side. This is presumably because, even if the flat part formed on a single fiber with a fiber diameter of about tens of μm strongly reflects light, only a small amount of light reaches the human eye. However, when a fiber bundle made of multiple fibers is worn across its surface to form a large flat part of about several hundred μm, part of the fabric strongly reflects light, allowing humans to perceive the light.

In other words, in order to suppress the shine phenomenon that occurs over time, which was an issue with conventional materials, it is important to form a fiber morphology that suppresses the area of flat parts that occur due to friction and wear of the fibers. To achieve this, the inventors conducted extensive research and discovered that by making a multifilament that is a mixture of ultrafine fibers with fiber diameters reduced to a certain range and normal fibers, it is possible to obtain a textile that has sufficient durability and does not form flat parts in the fiber bundle even when repeatedly worn with other materials. Furthermore, they discovered that the effect of the ultrafine fibers improves the flexibility of the textile, while the mixture of normal fibers maintains a resilient feel, resulting in a clothing textile that combines friction resistance and texture not found in conventional materials. Note that the terms normal fibers and ultrafine fibers refer to fibers with relatively large fiber diameters in a system in which single fibers with different fiber diameters are mixed, and fibers with small fiber diameters are called ultrafine fibers.

In addition, in the present invention, the ultrafine fibers arranged on the surface of the fiber bundle are crimped, and the steric hindrance caused by this crimp creates minute gaps between the fibers, allowing the friction surface to move flexibly without being fixed. This makes the material more resistant to friction than fiber bundles with normal ultrafine fibers arranged on the surface, and significantly reduces the shine phenomenon that was an issue with conventional materials.

Furthermore, by arranging a mixture of ultrafine fibers with crimping and normal fibers on the surface, fine and complex irregularities are formed on the textile surface, which not only provides a soft yet smooth feel, which is important for clothing textiles, but also reveals high water-repellent performance when a water-repellent finish is applied, which led to the present invention.

Specifically, the requirements of the present invention are that two types of segments A and B are present in the cross section of the composite fiber, that segment B has a smaller cross-sectional area than segment A, and that the composite fiber is formed from two types of polymers that are combined in a side-by-side or eccentric core-sheath configuration.

In the present invention, a segment refers to a portion of the composite fiber that can be separated from the composite fiber by solvent treatment, heat treatment, pressure treatment, etc., in the cross section of the composite fiber. If any two segments are made of the same polymer and the difference in cross-sectional area is within 10%, they will be considered to be part of the same segment group.

When the composite fiber of this embodiment is used in a textile, in order to stably form a multifilament containing a mixture of ultrafine fibers, regardless of the structure of the weaving or knitting, it is necessary that there are two types of segments A and B in the cross section of the fiber, with segment B having a smaller cross-sectional area than segment A.

If two types of segments A and B are present in the cross section of a composite fiber, segments A and B can be separated from the composite fiber after it has been made into a textile, and ultrafine fibers consisting of segment B, which has a smaller cross-sectional area than segment A, can be uniformly mixed in the multifilament. Therefore, in a textile using the composite fiber of this embodiment, the area of flat parts that occur due to friction, wear, etc. can be reduced, and further, since the ultrafine fibers have low bending rigidity, flexibility can be improved, while the normal fibers have high bending recovery, so a resilient feel can be maintained.

In addition, from the viewpoint that the presence of ultrafine fibers made of segment B can reduce the area of flat parts generated by friction, wear, etc., it is preferable that three or more segments B are arranged on the periphery of segment A. By arranging segment B on the periphery of segment A, the multifilament obtained after division has a structure in which the normal fiber made of segment A is surrounded by ultrafine fibers made of segment B, and the ultrafine fibers made of segment B are preferentially worn during wear with other materials, thereby making it possible to further reduce the area of flat parts that are generated. From this viewpoint, the more segments B arranged on the periphery of segment A, the more preferable, more preferably 5 or more, and particularly preferably 7 or more. On the other hand, from the viewpoint of maintaining the repulsive feeling obtained from normal fibers made of segment A, the more preferable the number of segments B arranged on the periphery of segment A is 50 or less, more preferably 35 or less, and particularly preferably 20 or less.

In the fiber cross section of the composite fiber of this embodiment, it is preferable that the cross-sectional area S _B of each segment B satisfies 1 μm ² ≦S _B <65 μm ² .

When the cross-sectional area S _B of each segment B is less than 65 ^μm2 , in the multifilament obtained by dividing the segment B from the composite fiber, the ultrafine fibers having a small cross-sectional area made of the segment B provide a shine suppression effect by reducing the area of flat parts generated by friction, wear, etc., and a flexibility improvement effect by having low bending rigidity. From this viewpoint, the smaller the S _B , the more prominent the shine suppression effect and the flexibility improvement effect can be achieved, so more preferably, S _B is less than 50 ^μm2 , and even more preferably, S _B is less than ⁴⁰ μm2.

On the other hand, if the cross-sectional area S _B of each segment B is too small, it may cause a decrease in color development when dyed with a dye, or a decrease in durability such as a tendency to fluff when worn, so the cross-sectional area S _B of each segment B is preferably ¹ _μm2 or more, more preferably ³ μm2 or more, and even more preferably ⁷ _μm2 or more.

In the fiber cross section of the composite fiber of this embodiment, it is preferable that the cross-sectional area S _A of each segment A satisfies 65 μm ² ≦S _A <700 μm ² .

When the cross-sectional area S _A of each segment A is ⁶⁵ μm2 or more, in a multifilament obtained by dividing the composite fiber into segments A and B, the normal fiber having a large cross-sectional area composed of segment A maintains the bending recovery required to express the resilience preferred in clothing textiles, while the ultrafine fiber having a small cross-sectional area composed of segment B provides flexibility and shine suppression effects.

From this viewpoint, the larger the S _A is, the higher the bending recovery and thus the higher the resilience, so S _A is more preferably ⁸⁰ μm2 or more, and even more preferably ⁹⁵ μm2 or more. On the other hand, if _S _A is too large, the normal fibers made of segment A are easily scraped off by friction, wear, etc., _and the area of the resulting flat parts increases, which may inhibit the shine suppression effect of the ultrafine fibers made of segment B, so S _A is preferably less than ^{700 μm2} , more preferably less than ⁵⁰⁰ μm2, and even more _preferably less than ³⁵⁰ μm2.

In this invention, the cross-sectional area of a segment is determined by embedding the composite fiber in an embedding agent such as epoxy resin, and taking an image of the fiber cross section perpendicular to the fiber axis with a scanning electron microscope (SEM) at a magnification that allows the composite fiber to be observed. The captured image is analyzed using image analysis software to calculate the cross-sectional area of one segment present in the fiber cross section of the composite fiber, and the value rounded off to the first decimal place is used as the cross-sectional area of the segment.In addition, when there are multiple segments of the same type, the simple number average of the cross-sectional areas determined for all segments of the same type is calculated, and the value rounded off to the first decimal place is used.

When the composite fiber of this embodiment is used in a textile, in order to induce crimping in the ultrafine fibers obtained by dividing segment B from the composite fiber, and to form minute gaps between the fibers to further suppress the shine phenomenon, to form minute and complex irregularities on the textile surface to give it a smooth feel, and to obtain high water-repellent performance when a water-repellent treatment is applied, it is necessary that segment B is formed of two types of polymers in a side-by-side or eccentric core-sheath type composite in the cross section of the fiber.

The two types of polymers that make up segment B are combined in a side-by-side or eccentric core-sheath type with different centers of gravity as shown in Figure 1(a). By dividing segment B and then subjecting it to heat treatment, the ultrafine fibers made up of segment B will bend significantly toward the polymer side with high shrinkage, and this continuous process will produce a coiled crimped form. Furthermore, by controlling the distance between the polymer centers of gravity, it is possible to produce any crimped form, which is the object of the present invention to further suppress the shine phenomenon by forming fine gaps between the fibers, and to achieve a smooth feel by forming fine and complex irregularities on the textile surface.

In addition, the presence of fine and complex irregularities on the textile surface makes it possible to achieve high water repellency when a water repellent treatment is applied by reducing the contact area with water. The composite structure of segment B may be either a side-by-side type or an eccentric core-sheath type. A side-by-side type maximizes the distance between the centers of gravity of the polymers, improving the expression of crimp, while an eccentric core-sheath type coats a high-shrinkage polymer with poor abrasion resistance with a low-shrinkage polymer with excellent abrasion resistance, further improving the abrasion resistance of the ultrafine fiber made of segment B.

In the composite fiber of this embodiment, the two types of polymers forming segment B are not particularly limited as long as they are a combination that produces a shrinkage difference upon heat treatment. Combinations of polymers with different viscosities or different melting points are possible, but from the perspective of making it easier to control the occurrence of shrinkage, it is preferable to use a combination of polymers with different melting points. By using a combination of polymers with different melting points, the polymer with the lower melting point shrinks first when heat treatment is performed, making it easy to produce a shrinkage difference between the polymers.

In the composite fiber of this embodiment, it is preferable that the polymer forming segment A is the polymer with the lowest melting point of the polymers forming segments A and B. If this relationship is established, the normal fiber made of segment A obtained by splitting the composite fiber will have high shrinkage, creating a difference in thread length between it and the ultrafine fiber made of segment B, which increases the gap between the fibers and further enhances the suppression of the shine phenomenon, which is the object of the present invention.

Furthermore, the textile surface has more complex irregularities that combine the fine irregularities caused by the crimping of the ultrafine fibers made up of segment B with the coarse irregularities caused by the normal fibers made up of segment A, which gives the textile a smooth feel and enhances its water-repellent properties when a water-repellent finish is applied.

In addition, when segment A is made up of two types of polymers, it is preferable that segment A, as shown in Figure 1(b) or Figure 2, is made up of two types of polymers that are combined in a side-by-side or eccentric core-sheath type, and that one of the two types of polymers is the polymer with the lowest melting point among the polymers that make up segments A and B, from the viewpoint that the fibers made up of segments A and B both have crimps, thereby enabling the textile to exhibit stretch performance.

In the composite fiber of this embodiment, when segment B is formed of two types of polymers combined in a side-by-side or eccentric core-sheath type, and the two types of polymers are a combination of polymers with different melting points, it is preferable that the area ratio of the low melting point polymer to the high melting point polymer is in the range of 70/30 to 30/70 (low melting point polymer/high melting point polymer). If the area ratio is in this range, the low melting point polymer is not affected by texture hardening due to clogging when it shrinks highly during heat treatment, and the crimp morphology due to shrinkage difference can be fully expressed, and larger interfiber voids can be obtained.

The cross-sectional shape of segment B present in the fiber cross section of the composite fiber of this embodiment is not limited, but from the viewpoint of forming a fiber form having minute gaps between the fibers by expressing crimps in the ultrafine fibers made of segment B after dividing segment B, it is preferable that the cross-sectional shape of segment B is flat as shown in Figure 1(a).

Here, "flat" refers to a long and narrow shape in a plan view, and more specifically, to a segment with a "flatness" of 1.1 or more, as described below.

By making the cross-sectional shape of segment B present in the fiber cross section of the composite fiber of this embodiment flat, the length of the long axis becomes the rate limiting factor and steric hindrance is generated, so that the void effect due to the expression of shrinkage can be maximized, and the smooth feel due to the fine unevenness of the textile surface and the water-repellent performance when water-repellent processing is applied can be more prominent. From this viewpoint, the longer the length of the long axis is compared to the length of the short axis, the better, and the flatness is preferably 1.2 or more, more preferably 1.5 or more, and even more preferably 2.0 or more. On the other hand, if the flatness is too large, the area of the flat part when worn may increase, so the flatness is preferably 6.0 or less, more preferably 5.0 or less, and even more preferably 4.0 or less.

In this embodiment, the flatness of the segments is determined by the following method.

First, the composite fiber is embedded in an embedding agent such as epoxy resin, and an image of the fiber cross section perpendicular to the fiber axis is taken with a scanning electron microscope (SEM) at a magnification that allows the composite fiber to be observed. The captured image is analyzed using image analysis software to determine the flatness, as shown in Figure 1 (a), by dividing the length of the major axis by the length of the minor axis, with the line connecting the two most distant points (a1, a2) among any points on the periphery of the segment as shown in Figure 1 (a) as the major axis, and the line connecting the intersection point (b1, b2) of the periphery of the fiber with the line passing through the midpoint of the major axis and perpendicular to the major axis as the minor axis, and rounding the value to one decimal place to obtain the flatness. Note that if there are multiple segments of the same type, the simple number average of the flatnesses determined for all segments of the same type is calculated, and the value rounded to one decimal place is used.

The cross-sectional shape of the segment A present in the fiber cross section of the composite fiber of this embodiment is not limited, but from the viewpoint of being able to reduce flat areas even when the fibers consisting of the segment A are worn when a textile obtained by dividing the segment A from the composite fiber is worn, it is preferable that the cross-sectional shape of the segment A is a multi-lobe cross section having three or more convex parts on the periphery as shown in Figure 1 (a). By having convex parts on the periphery, the contact area with other materials during wear can be reduced, and the area that becomes flattened due to wear can be reduced. From this viewpoint, the number of convex parts is more preferably 5 or more, and even more preferably 7 or more. On the other hand, if the number of convex parts becomes too large, the effect gradually decreases, so the number of convex parts is preferably 20 or less, more preferably 15 or less, and even more preferably 10 or less.

In the composite fiber of this embodiment, since the purpose is to divide the composite fiber segments A and B after making it into a textile, and to uniformly mix ultrafine fibers consisting of segment B in the multifilament, the cross-sectional form of the composite fiber is preferably a sea-island composite fiber in which segments A and B are island components as shown in FIG. 1(a), or a core-sheath composite fiber in which segment A is the core and segment B is the sheath as shown in FIG. 1(c). In the case of a sea-island composite fiber as shown in FIG. 1(a), segments A and B can be divided by removing the sea component z, and in the case of a core-sheath composite fiber as shown in FIG. 1(c), the polymer constituting segment A and the polymer constituting segment B are formed from incompatible polymers with different bonds in the main chain, and the interface between segments A and B can be peeled off and divided by heat treatment, physical impact, etc.

In addition, from the viewpoint of being able to stably separate segments A and B regardless of the polymers that form segments A and B, it is more preferable for the sea-island composite fiber to have segments A and B as island components, and for the sea component to be formed from a polymer that has the fastest dissolution rate in a solvent among the polymers that make up the sea-island composite fiber.

In consideration of simplifying the dissolution process and shortening the time in advanced processing, the dissolution rate of the polymer forming the sea component is preferably 100 or more, and more preferably 1000 or more, when the polymer forming the island components has the fastest dissolution rate as the standard (sea component/island component). If the dissolution rate ratio is 1000 or more, the dissolution process can be completed in a short time, and in addition to increasing the process speed, a higher quality fabric can be obtained without unnecessarily deteriorating the island component polymer. From this perspective, the higher the dissolution rate ratio, the better, but the practical upper limit is 10,000 or less due to the stability of the polymer forming the sea component.

The polymer that forms the sea component is preferably selected from polymers that are melt-moldable and more easily soluble than other components, such as polyesters and their copolymers, polylactic acid, polyamides, polystyrene and their copolymers, polyethylene, and polyvinyl alcohol.

From the viewpoint of simplifying the dissolution process of the sea component, the polymer forming the sea component is preferably a copolymerized polyester, polylactic acid, polyvinyl alcohol, etc., which is easily soluble in aqueous solvents or hot water. In particular, since it is easily soluble in aqueous solvents such as an alkaline aqueous solution while maintaining crystallinity, from the viewpoint of high-level processing passability, in which fusion between composite fibers does not occur even in false twist processing in which rubbing is applied under heat, polyesters copolymerized with 5 mol % to 15 mol % of 5-sodium sulfoisophthalic acid and polyesters copolymerized with the above-mentioned 5-sodium sulfoisophthalic acid and polyethylene glycol having a weight average molecular weight of 500 to 3000 in the range of 5 mass % to 15 mass % are preferred.

The composite fiber of this embodiment is first subjected to advanced processing such as weaving and knitting, and then divided into segments A and B. It is then subjected to heat treatment to obtain a multifilament in which normal fibers consisting of segment A and ultrafine fibers having crimp consisting of segment B are uniformly mixed. Due to the special fiber form of this multifilament, it is possible to obtain a clothing textile that has a smooth feel and a soft texture with a bouncy feel that is not found in conventional materials, while suppressing the deterioration of surface quality caused by friction and abrasion with other materials, and when further subjected to water-repellent processing, exhibits high water-repellent performance.

In the multifilament of this embodiment, in order to reduce the area of flat parts caused by friction, wear, etc., and to achieve a soft texture with a sense of resilience, the multifilament must be made up of two types of filaments A and B, with one or more filaments B present between any two filaments A in the multifilament, and the filaments B having a smaller fiber diameter than the filaments A.

In the present invention, if any two filaments in a multifilament are made of the same polymer and the difference in fiber diameter is within 10%, they are considered to be the same filament.

In addition, the presence of one or more filaments B between any two filaments A in the multifilament in the present invention means that filaments A and B are uniformly mixed. Specifically, in the textile made of the multifilament in this embodiment, an image of the cross section of the textile perpendicular to the length direction of the textile and perpendicular to the fiber axis direction of the multifilament is taken with a scanning electron microscope (SEM) at a magnification at which 15 or more filaments including two or more filaments A can be observed, and the circumscribing circles R1 and R2 of any two filaments A are drawn on the taken image using image analysis software as shown in Figure 4, and one or more filaments B are present within the range surrounded by the two common circumscribing lines (J1 and J2) and the two circumscribing lines (R1 and R2) of the two circumscribing lines drawn. For example, in Figure 4, four filaments B are present within the range surrounded by the two common circumscribing lines (J1 and J2) and the two circumscribing lines (R1 and R2), and it can be said that one or more filaments B are present between any two filaments A in the multifilament.

The presence of filament B, which has a smaller fiber diameter than filament A, between any two filaments A in the multifilament results in a fiber form in which filament A, which is a normal fiber, and filament B, which is an ultrafine fiber, are evenly mixed in the multifilament, reducing the area of flat areas that occur due to friction, wear, etc. Furthermore, since filament B, which is an ultrafine fiber, has low bending rigidity, flexibility is improved, while filament A, which is a normal fiber, has high bending recovery, allowing the resilience to be maintained.

In the multifilament of the present embodiment, it is preferable that the fiber diameter D _B of the filament B satisfies 1 μm≦D _B <9 μm.

By making the filament B an ultrafine fiber with a fiber diameter D _B of less than 9 μm, it is possible to obtain a shine-suppressing effect by reducing the area of flat parts generated by friction, wear, etc., and a flexibility-improving effect by having low bending rigidity. From this viewpoint, the smaller D _B is, the more prominent the shine-suppressing effect and the flexibility-improving effect can be obtained, so D _B is more preferably less than 8 μm, and even more _preferably less than 7 μm.

On the other hand, if the fiber diameter D _B of the filament B is too small, this may result in a decrease in color development when dyed with a dye, or a decrease in _durability such as a tendency to fluff when worn, and therefore the fiber diameter D _B of the filament B is preferably 1 μm or more, more preferably 2 μm or more, _and even more preferably 3 μm or more.

In the multifilament of the present embodiment, it is preferable that the fiber diameter D _A of the filament A satisfies 9 μm≦D _A <30 μm.

By making the fiber diameter D _A of the filament A 9 μm or more, it is possible to maintain the bending recovery required to produce the resilience preferred in clothing textiles, while simultaneously achieving the flexibility and shine-reducing effect provided by the ultrafine fibers with a small cross-sectional area made up of the segment B.

From this viewpoint, the larger the _DA , the higher the bending recovery and thus the higher the resilience, so that the _DA is more preferably 10 μm or more, and even more preferably 11 μm or more. On the other hand, if _{the DA} _is too large, the filament A, which is a normal fiber, is easily scraped off due to friction, wear, etc., and the area of the generated flat portion increases, which may inhibit the shine suppressing effect of the filament B, which is an ultrafine fiber, so that the _DA is preferably less than 30 μm, more preferably less than 25 _μm , and even _more preferably less than 20 μm.

In the multifilament of this embodiment, in order to induce crimping in the ultrafine filament B, which forms minute gaps between the fibers to further suppress the shine phenomenon, to form minute and complex irregularities on the textile surface to give it a smooth feel, and to obtain high water-repellent performance when a water-repellent treatment is applied, it is necessary that the filament B is formed of two types of polymers that are combined in a side-by-side or eccentric core-sheath type in the cross section of the fiber.

The two types of polymers that form filament B are combined in a side-by-side or eccentric core-sheath type with different centers of gravity as shown in Figure 5(b), so that when heat-treated, filament B bends significantly toward the polymer side that shrinks more, and this continues to create a coiled crimped form. Furthermore, by controlling the distance between the polymer centers of gravity, it is possible to create any crimped form, which is the object of the present invention to further suppress the shine phenomenon by forming fine gaps between the fibers, and to achieve a smooth feel by forming fine and complex irregularities on the textile surface.

In addition, the presence of minute and complex irregularities on the textile surface makes it possible to achieve high water-repellent performance when a water-repellent treatment is applied, as the contact area with water is reduced.

The composite structure of filament B may be either a side-by-side type or an eccentric core-sheath type. If it is a side-by-side type, the distance between the centers of gravity of the polymers is maximized, which improves the expression of crimp. If it is an eccentric core-sheath type, the wear resistance of the ultrafine fiber made of filament B can be further improved by coating a high-shrinkage polymer with poor wear resistance with a low-shrinkage polymer with excellent wear resistance.

In the multifilament of this embodiment, the two types of polymers forming filament B are not particularly limited as long as they are a combination that produces a shrinkage difference upon heat treatment, but from the viewpoint of making it easier to control the occurrence of crimp, it is preferable to use a combination of polymers with different melting points. By using a combination of polymers with different melting points, the polymer with the lower melting point shrinks first when heat treatment is performed, making it easy to produce a shrinkage difference between the polymers.

In the multifilament of this embodiment, it is preferable that the polymer forming filament A is the polymer with the lowest melting point of the polymers forming filaments A and B. Within this range, filament A, which is a normal fiber, will shrink highly, creating a difference in thread length between it and filament B, which is an ultrafine fiber, and increasing the gap between the fibers. Not only can this further enhance the suppression of the shine phenomenon, which is the object of the present invention, but it also forms more complex irregularities on the textile surface, combining fine irregularities caused by the crimping of filament B, which is an ultrafine fiber, with coarse irregularities caused by filament A, which is a normal fiber, and this can further accentuate the smooth texture and water-repellent performance when water-repellent processing is applied.

In addition, when filament A is made up of two types of polymers, it is preferable that filament A is made up of two types of polymers combined in a side-by-side or eccentric core-sheath type as shown in Figure 6(a) in order to provide stretch performance to the textile when both filaments A and B have crimps, and that one of the two types of polymers is the polymer with the lowest melting point among the polymers that make up filaments A and B.

In the multifilament of this embodiment, when filament B is formed of two types of polymers combined in a side-by-side or eccentric core-sheath type, and the two types of polymers are a combination of polymers with different melting points, it is preferable that the area ratio of low melting point polymer to high melting point polymer is in the range of 70/30 to 30/70 (low melting point polymer/high melting point polymer). If the area ratio is in this range, the low melting point polymer is not affected by texture hardening due to clogging when it shrinks highly during heat treatment, and the crimp morphology due to shrinkage difference can be fully expressed, and larger interfiber voids can be obtained.

In the multifilament of this embodiment, the cross-sectional shape of filament B is not limited, but from the viewpoint of forming a fiber form having minute gaps between the fibers by inducing crimping in filament B, which is an ultrafine fiber, after splitting filament B, it is preferable that the cross-sectional shape of filament B be flat, as shown in Figure 5(b).

Here, "flat" refers to a long and narrow shape when viewed from above, and more specifically, to filaments with a "flatness" of 1.1 or more, as described below.

In the multifilament of this embodiment, the cross-sectional shape of filament B is flattened, which increases the bulk in the long axis direction, thereby maximizing the void effect caused by the expression of crimp, and the smooth feel due to the fine and complex unevenness of the textile surface and the water-repellent performance when water-repellent processing is applied can be more prominent. From this perspective, the longer the length of the long axis is compared to the length of the short axis, the better, and the flatness is preferably 1.2 or more, more preferably 1.5 or more, and even more preferably 2.0 or more. On the other hand, if the flatness is too large, the area of the flat part when worn may increase, so the flatness is preferably 6.0 or less, more preferably 5.0 or less, and even more preferably 4.0 or less.

First, the multifilament extracted from the textile is embedded in an embedding agent such as epoxy resin, and an image is taken of the fiber cross section perpendicular to the fiber axis with a scanning electron microscope (SEM) at a magnification that allows the multifilament to be observed. The captured image is analyzed using image analysis software, and the long axis is taken as the straight line connecting the two most distant points (a1, a2) among any points on the outer periphery of the filament, as shown in Figure 5 (b), and the short axis is taken as the straight line connecting the intersection point (b1, b2) of the outer periphery of the fiber with the straight line passing through the midpoint of the long axis and perpendicular to the long axis, and the value obtained by dividing the length of the long axis by the length of the short axis is calculated and rounded to one decimal place to obtain the flatness. Note that if there are multiple filaments of the same type in the multifilament, the simple number average of the flatnesses obtained for all filaments of the same type is calculated and the value rounded to one decimal place is used.

In the multifilament of this embodiment, the cross-sectional shape of filament A is not limited, but from the viewpoint of being able to reduce flat areas when the textile is worn, even when filament A, which is a normal fiber, is worn, it is preferable that the cross-sectional shape of filament A is a multi-lobe cross section having three or more protrusions on the periphery as shown in Figure 5 (a). By having protrusions on the periphery, the contact area with other materials during wear can be reduced, and the area that becomes flattened due to wear can be reduced. From this viewpoint, the number of protrusions is more preferably five or more, and even more preferably seven or more. On the other hand, if the number of protrusions becomes too large, the effect gradually decreases, so the number of protrusions is preferably 20 or less, more preferably 15 or less, and even more preferably 10 or less.

The polymer used in this embodiment is preferably a thermoplastic polymer because of its excellent processability. As the thermoplastic polymer, for example, a polymer group such as polyester, polyethylene, polypropylene, polystyrene, polyamide, polycarbonate, polymethyl methacrylate, polyphenylene sulfide, and copolymers thereof are preferable. In particular, from the viewpoint of being able to impart high interfacial affinity and obtaining fibers without abnormalities in the composite cross section, it is preferable that all of the thermoplastic polymers used in this embodiment are the same polymer group and copolymers thereof. Among these, from the viewpoint of obtaining good color development when dyeing the composite fiber and multifilament of this embodiment when it is made into a textile, it is more preferable that the thermoplastic polymer used for the composite fiber and multifilament is a polyester or polyamide polymer group and copolymers thereof, and among them, polyethylene terephthalate and copolymers thereof are even more preferable because they provide a moderate resilience due to their high bending recovery.

Furthermore, as environmental issues are gaining attention, the use of plant-derived biopolymers and recycled polymers in this embodiment is also suitable from the perspective of reducing the environmental impact. Therefore, the polymers used in this embodiment described above can be recycled polymers that have been recycled using any of the methods of chemical recycling, material recycling, and thermal recycling.

Even if biopolymers or recycled polymers are used, as mentioned above, polyester-based or polyamide-based polymers and their copolymers are preferred from the viewpoint of obtaining good color development when dyed, and among these, recycled polyethylene terephthalate and its copolymers are even more suitable because they provide a moderate bounce due to their high bending recovery.

The polymer may also contain various additives such as inorganic compounds such as titanium oxide, silica, and barium oxide, colorants such as carbon black, dyes, and pigments, flame retardants, fluorescent brighteners, antioxidants, and ultraviolet absorbers.

Among these, it is preferable to incorporate titanium oxide into the polymer. By incorporating titanium oxide into the polymer, not only can the titanium oxide in the fiber diffusely reflect light, thereby improving the quality of appearance by suppressing uneven appearance (glare) caused by increases and decreases in reflection depending on the angle of incidence of light, but the titanium oxide inside the fiber also provides functionality such as anti-transparency and UV protection. To fully obtain the above effects, the content of titanium oxide in the composite fiber is preferably 0.5 mass% or more, more preferably 1.0 mass% or more, and even more preferably 3.0 mass% or more. Furthermore, since increased diffuse reflection of light by titanium oxide can cause a decrease in color development, the content of titanium oxide in the fiber is preferably 10.0 mass% or less.

In this embodiment, a combination of polymers with different melting points refers to a combination of polymers whose melting points differ by 10°C or more from a group of melt-moldable thermoplastic polymers such as polyesters, polyethylenes, polypropylenes, polystyrenes, polyamides, polycarbonates, polymethyl methacrylates, and polyphenylene sulfide, and their copolymers, and a combination of polymers whose melting points differ by 5°C or more from a group of the same polymers with the same bonds in the main chain, such as polyesters with ester bonds and polyamides with amide bonds.

In particular, from the viewpoint of preventing peeling and imparting stability to advanced processing and durability to textiles, it is more preferable to select polymer combinations from the same polymer group in which the bonds present in the main chain are the same, such as polyesters with ester bonds and polyamides with amide bonds.

Combinations of low-melting point polymers and high-melting point polymers in the same polymer group include, for example, polyester-based combinations such as copolymerized polyethylene terephthalate/polyethylene terephthalate, polypropylene terephthalate/polyethylene terephthalate, polybutylene terephthalate/polyethylene terephthalate, thermoplastic polyurethane/polyethylene terephthalate, polyester-based elastomer/polyethylene terephthalate, polyester-based elastomer/polybutylene terephthalate, polyamide-based combinations such as nylon 6 or 66/nylon 610, nylon 6-nylon 66 copolymer/nylon 6 or 610, PEG copolymerized nylon 6/nylon 6 or 610, thermoplastic polyurethane/nylon 6 or 610, and polyolefin-based combinations such as ethylene-propylene rubber finely dispersed polypropylene/polypropylene, and propylene-α-olefin copolymer/polypropylene.

Among these, from the viewpoint of obtaining good color development by dyeing when the composite fiber and multifilament of this embodiment are made into textiles, it is more preferable that the polymers having different melting points are a combination of polyesters or polyamides, and among these, a combination of copolymerized polyethylene terephthalate/polyethylene terephthalate as the polyester is a particularly preferable combination because it provides a moderate resilience due to its high bending recovery.

Furthermore, examples of the copolymerized components in the copolymerized polyethylene terephthalate include succinic acid, adipic acid, azelaic acid, sebacic acid, 1,4-cyclohexanedicarboxylic acid, maleic acid, phthalic acid, isophthalic acid, and 5-sodium sulfoisophthalic acid. Among these, from the viewpoint of maximizing the difference in shrinkage with polyethylene terephthalate, it is preferable to use polyethylene terephthalate copolymerized with 5 to 15 mol% isophthalic acid.

In the textile of which the multifilament of this embodiment is a part, the multifilament has a fiber form in which normal fibers and ultrafine fibers are uniformly mixed, which reduces the area of flat parts that occur due to friction, wear, etc. Furthermore, the ultrafine fibers have low bending rigidity, which improves flexibility, while the normal fibers have high bending recovery, which maintains a resilient feel, resulting in a textile that combines friction resistance and texture not found in conventional materials.

In addition, because the ultrafine fibers have shrinkage, the steric hindrance caused by this shrinkage creates tiny gaps between the fibers, allowing the friction surface to move flexibly without being fixed, further increasing resistance to friction and significantly improving shine resistance. In addition, because the ultrafine fibers with shrinkage are arranged on the surface, fine and complex irregularities are formed on the surface of the textile, giving it a smooth feel and, when a water-repellent finish is applied, providing high water-repellent performance.

　Therefore, it can be used suitably for a wide range of textile products, from general clothing such as jackets, skirts, pants, and underwear, to sports clothing and clothing materials, and by taking advantage of its properties, it can be used for a wide range of textile products, including interior products such as carpets and sofas, vehicle interior products such as car seats, cosmetics, masks, health products, and other daily uses. However, from the viewpoints that it can suppress the shine phenomenon caused by friction with other materials when worn, that it is flexible yet has a smooth feel, and that it can exhibit high water-repellent performance when water-repellent processing is applied, its use in clothing applications is particularly preferable.

The multifilament of this embodiment can be used in various textiles such as nonwoven fabrics and woven and knitted fabrics, but from the viewpoint of suitability for the above-mentioned clothing applications, it is preferable that the multifilament of this embodiment be used as a part of a woven or knitted fabric.

The weave of the woven or knitted fabric of the present invention is not particularly limited, and examples of the weave in the case of a woven fabric include plain weave, twill weave, satin weave, variation plain weave, variation twill weave, variation satin weave, variegated weave, patterned weave, one-sided overlap weave, double weave, multiple weave, warp pile weave, weft pile weave, and twill weave. Examples of the knitted fabric include circular knit, weft knit, warp knit (including tricot knit and raschel knit), pile knit, plain knit, jersey knit, rib knit, smooth knit (double-sided knit), rubber knit, pearl knit, Denbigh weave, cord weave, atlas weave, chain weave, and insertion weave. Any weave is acceptable for both woven and knitted fabrics, but a weave that is more likely to produce unevenness, such as a twill weave, is preferable compared to a plain weave, because the multifilament of this embodiment is more likely to shrink and fine and complex unevenness is more likely to be formed on the surface of the fabric. When mixed with other fibers, a weave in which the multifilament of this embodiment appears more on the surface is preferable.

When the woven or knitted fabric of the present invention is a woven fabric, the total cover factor (CF) of the warp and weft directions is preferably 1000 to 3500. A CF of 1000 or more reduces voids at the weave points, making it possible to obtain a highly durable fabric that is less susceptible to pilling and abrasion. From this perspective, a CF of 1500 or more is more preferable.

On the other hand, if the CF is 3500 or less, the fine and complex irregularities of the multifilament described above will not be lost due to excessive binding force from the weaving points, and the shine caused by friction with other materials when worn can be suppressed, a soft yet smooth feel can be obtained, and high water repellency can be achieved when a water repellent finish is applied. From this perspective, a CF of 2800 or less is more preferable.

The total cover factor (CF) referred to here is a value obtained by measuring the warp density and weft density of a woven fabric in a 2.54 cm section in accordance with JIS L1096:2010 8.6.1 and calculating the value from the formula: warp weave density [pieces/2.54 cm] × (total warp fineness [dtex]) ^1/2 + weft weave density [pieces/2.54 cm] × total weft fineness [dtex]) ^1/2 .

In order for the woven or knitted fabric of this embodiment to exhibit high water-repellent performance, it is preferable that the woven or knitted fabric contains a multifilament consisting of two types of filaments A and B, with one or more filaments B present between any two filaments A in the multifilament, with filament B having a smaller fiber diameter than filament A, being formed from two types of polymers combined in a side-by-side or eccentric core-sheath type, and being subjected to a water-repellent treatment.

In the present invention, the presence of one or more filaments B between any two filaments A means that filaments A and B are uniformly mixed. Specifically, in the woven or knitted fabric of this embodiment, a cross section perpendicular to the length direction and perpendicular to the fiber axis direction of the filaments is photographed with a scanning electron microscope (SEM) at a magnification at which 15 or more filaments including two or more filaments A can be observed. The photographed image is analyzed using image analysis software to draw circumscribing circles R1 and R2 for any two filaments A as shown in Figure 4, and one or more filaments B are present within the range surrounded by the two common circumscribing lines (J1 and J2) and the two circumscribing circles (R1 and R2) of the two circumscribing circles. For example, in Figure 4, four filaments B are present within the range surrounded by the two common circumscribing lines (J1 and J2) and the two circumscribing circles (R1 and R2), and it can be said that one or more filaments B are present between any two filaments A.

The presence of filament B, which has a smaller fiber diameter than filament A, between any two filaments A in the multifilament results in a fiber form in which filament A, which is a normal fiber, and filament B, which is an ultrafine fiber, are uniformly mixed in the multifilament. Furthermore, the two types of polymers that form filament B are combined in a side-by-side type or eccentric core-sheath type with different centers of gravity as shown in Figure 5(b), so that when heat treatment is applied, filament B is greatly curved toward the polymer side that shrinks highly, and this continues to create a coil-like crimped form. As a result, the crimped ultrafine fibers and normal fibers are mixed and arranged on the surface layer, and fine and complex irregularities are formed on the surface of the textile, and when water-repellent processing is applied, the contact area with water is reduced, resulting in high water-repellent performance.

In the present invention, the water-repellent woven or knitted fabric is a woven or knitted fabric that has substantial water-repellent properties, and examples thereof include a woven or knitted fabric in which the water droplets slide off the surface of the woven or knitted fabric at an angle of less than 90 degrees. When the woven or knitted fabric of the present invention is made of polyolefin, it has sufficient water-repellent properties without the addition of a water-repellent agent, and is a water-repellent woven or knitted fabric as is. However, when the woven or knitted fabric is made of polyester or polyamide, which are preferably used for clothing applications, it is preferable to add a water-repellent agent to the surface of the woven or knitted fabric, since sufficient water-repellent properties cannot be obtained as is. The water-repellent treatment is performed so that at least one side of the woven or knitted fabric has water-repellent properties. It is possible to select appropriately as needed whether to perform the water-repellent treatment on only one side that requires water repellency, or on both sides so that they have water-repellent properties.

When a water repellent is applied to a woven or knitted fabric to perform a water repellent treatment, the water repellent may be fluorine-based or non-fluorine-based (e.g., silicone-based, hydrocarbon-based, or any other water repellent). There is no particular limit to the type of water repellent, and fluorine-based water repellents made of fluorine compounds having perfluoroalkyl groups in which two or more hydrogen atoms of the alkyl group are replaced with fluorine atoms, and non-fluorine-based water repellents that do not contain fluorine elements can be used. From the viewpoint of environmental consideration, it is preferable to use C6 fluorine-based water repellents in which the perfluoroalkyl group has six or fewer carbon atoms, or non-fluorine-based water repellents, and from the viewpoint of recyclability, it is more preferable to use non-fluorine-based water repellents so that the woven or knitted fabric does not substantially contain fluorine elements.

In this context, "substantially free of elemental fluorine" means that the fluorine content is below the detection limit of 25 ng/g or less as measured by combustion ion chromatography. Examples of non-fluorine-based water repellents include silicone-based water repellents that are primarily made up of silicone compounds, and hydrocarbon-based water repellents such as paraffin-based water repellents that are primarily made up of paraffin compounds.

In order to obtain a woven or knitted fabric that is soft yet has a smooth feel and high water repellency, which is a feature of the present invention, it is preferable that the amount of water repellent applied is 0.1 to 1 mass %. If the amount of water repellent applied is increased, not only will the fibers be fixed together by the water repellent, hardening the texture, but the water repellent will also fill in the gaps between the irregularities, making the texture smoother. On the other hand, if the amount of water repellent applied is small, the water repellency will not be fully expressed, and from these perspectives, the amount of water repellent applied is more preferably 0.2 to 0.8 mass %, and particularly preferably 0.3 to 0.5 mass %.

In the water-repellent woven or knitted fabric of the present invention, a mixture of ultrafine fibers with crimp and normal fibers is arranged on the surface, forming fine and complex irregularities on the textile surface, which allows the fabric to exhibit excellent water-repellent properties similar to the lotus leaf effect when water droplets are dropped onto the woven or knitted fabric surface. The water-repellent properties are preferably such that the water droplet sliding angle, which indicates the ability to remove water droplets, is 1 to 20 degrees.

The water droplet sliding angle referred to here is the angle at which the water droplet begins to slide down when a water droplet is gently dropped onto the surface of a woven or knitted fabric attached flat on a horizontal plate and the plate is gently tilted at a uniform speed; the smaller the water droplet sliding angle, the better the water droplet removal ability. The water droplet sliding angle refers to the tilt angle (°) at which the droplet slides down when 20 μL of 20°C water is placed on the surface of the woven or knitted fabric using a solid-liquid interface analyzer (DropMaster 700, manufactured by Kyowa Interface Science Co., Ltd.) and the device is gently tilted from 0 degrees at a uniform speed (approximately 1 degree/second) in 1 degree increments.

If the water droplet sliding angle is 1 to 20 degrees, when used in clothing, for example, water droplets are less likely to remain on the woven or knitted fabric when worn, and excellent water droplet removal properties can be obtained without causing discomfort due to wetness, etc. From this perspective, the smaller the water droplet sliding angle, the more unlikely it is that water droplets will remain on the woven or knitted fabric when worn, and extremely high water droplet removal properties can be obtained, so a water droplet sliding angle of 1 to 15 degrees is more preferable, and a water droplet sliding angle of 1 to 10 degrees is particularly preferred as it provides super-water repellency that exceeds that of lotus leaves in nature.

When a textile with water-repellent properties is used for clothing applications, not only is initial water-repellent performance required, but practical durability is also required, in which the water-repellent performance does not decrease much when worn repeatedly in everyday situations. From this perspective, it is preferable that the difference in the water droplet sliding angle before and after 20 washing and drying cycles is 0 to 20 degrees for at least the water-repellent woven or knitted fabric of the present invention.

The difference in the water droplet sliding angle before and after 20 cycles of washing and drying means the absolute value of the water droplet sliding angle after 20 cycles of washing according to JIS L1930-2014-C4M method and drying according to method A (line drying) for a woven or knitted fabric that has been at least water-repellent treated according to the present invention, minus the water droplet sliding angle before washing and drying.

If the difference in water droplet sliding angle before and after 20 repeated washing and drying cycles is 0 to 20 degrees, excellent water droplet removal properties can be obtained for the long term without discomfort due to wetness, etc., and the material can be used suitably as casual clothing. Furthermore, if the difference is 0 to 10 degrees, it can be used suitably as sports clothing and uniform clothing, which require excellent durable water repellency for use in harsh environments, and is therefore considered to be in the more preferable range.

An example of a method for producing the composite fiber and multifilament of this embodiment is described in detail below.

In order to obtain the multifilament containing ultrafine fibers, which is the object of the present invention, various methods can be used, such as a method of separating normal fibers and ultrafine fibers from composite fibers, a method of mixing normal fibers and ultrafine fibers that have been spun separately using an air nozzle, or a spinning blending method in which normal fibers and ultrafine fibers are discharged from the same spinneret and wound up simultaneously. However, in order to stably form a multifilament containing ultrafine fibers when used in textiles, regardless of the structure of the weaving or knitting, it is preferable to use a method of separating normal fibers and ultrafine fibers from composite fibers, which has two types of segments A and B in the fiber cross section and has a smaller cross-sectional area than segment A.

In the composite fiber of this embodiment, which is made of two or more types of polymers, it is preferable to set the melt viscosity ratio of the polymers used to less than 5.0 and the difference in solubility parameter values to less than 2.0, since this allows a stable formation of a composite polymer flow and allows the production of fibers with a good composite cross section.

As a composite spinneret used in producing the composite fiber of this embodiment made of two or more types of polymers, for example, the composite spinneret described in JP 2011-208313 A is preferably used.

The composite spinneret of the present invention shown in Figure 12 is assembled into a spinning pack with three main components stacked from the top: a metering plate 1, a distribution plate 2, and a discharge plate 3, and is used for spinning. Incidentally, Figure 12 shows an example in which three types of polymers, A polymer, B polymer, and C polymer, are used. With conventional composite spinnerets, it is difficult to composite three or more types of polymers, so it is preferable to use a composite spinneret that utilizes fine flow paths as shown in Figure 12.

In the nozzle member shown in Figure 12, the metering plate 1 measures and introduces the amount of polymer per each discharge hole and each distribution hole, the distribution plate 2 controls the composite cross section and its cross-sectional shape in the cross section of the single fiber, and the discharge plate 3 compresses the composite polymer flow formed by the distribution plate 2 and discharges it.

To avoid confusing the explanation of the composite spinneret, it is not shown in the figure, but for the components stacked above the metering plate 1, components with flow paths formed to match the spinning machine and spinning pack can be used. By designing the metering plate 1 to match the existing flow path components, the existing spinning pack and its components can be used as is. For this reason, there is no need to dedicate a spinning machine specifically for this spinneret. In practice, it is also a good idea to stack multiple flow path plates between the flow path and metering plate or between the metering plate 1 and distribution plate 2. The purpose of this is to provide a flow path that efficiently transports the polymer in the cross-sectional direction of the spinneret and the cross-sectional direction of the single fiber, and to configure it so that it is introduced into the distribution plate 2.

The polymer flow thus formed by the distribution plate 2 is contracted by the discharge plate 3 and discharged. At this time, the purpose of the discharge hole is to re-measure the flow rate of the composite polymer flow, i.e., the discharge amount, and to control the draft (= take-up speed/discharge linear speed) on the spinning line. It is preferable to determine the hole diameter and length taking into consideration the viscosity of the polymer and the discharge amount.

The composite fiber and multifilament of this embodiment can be spun by melt spinning, which is intended to produce long fibers, wet and dry-wet solution spinning, or melt-blowing and spunbonding, which are suitable for obtaining sheet-like fiber structures. From the viewpoint of increasing productivity, however, melt spinning is preferred. In addition, in the melt spinning method, production is possible by using a composite spinneret, which will be described later, and the spinning temperature in this case is preferably set to a temperature at which the polymers used, mainly those with high melting points or high viscosity, exhibit fluidity. The temperature at which this fluidity is exhibited varies depending on the molecular weight, but stable production is possible when it is set between the melting point of the polymer and melting point + 60°C.

In the composite fiber and multifilament of this embodiment, a discharge rate per hole in the spinneret of 0.1 g to 10 g/min/hole allows for stable production. In this case, it is preferable to determine the discharge rate according to the desired fiber diameter, taking into account the winding conditions and the draw ratio, etc.

After the polymer flow from the discharge hole is cooled and solidified, an oil agent is applied and the flow is taken up by a roller set to a specified peripheral speed. Here, this take-up speed is determined from the discharge amount and the target fiber diameter. In the present invention, from the viewpoint of stable production of composite fibers and multifilaments, the take-up speed of the roller during spinning is preferably about 500 to 6000 m/min, and can be changed depending on the physical properties of the polymer and the purpose of use of the fiber. In particular, from the viewpoint of high orientation and improved mechanical properties, it is preferable to set the take-up speed to 500 to 4000 m/min and then draw the fibers, since this not only promotes uniaxial orientation of the fibers, but also allows the occurrence of shrinkage to be controlled by the thermal contraction difference resulting from the stress difference during drawing between the composite polymers and the orientation difference during drawing.

When stretching, for example, in a stretching machine consisting of one or more pairs of rollers, if the fiber is made of a polymer that exhibits thermoplasticity and can be melt-spun, it is stretched smoothly in the fiber axis direction by the peripheral speed ratio between the first roller set to the preheating temperature and the second roller set to the crystallization temperature, and then heat-set by the second roller and wound up. Here, it is preferable to set the preheating temperature appropriately based on the temperature at which the polymer can be softened, such as the glass transition temperature. The upper limit of the preheating temperature is preferably a temperature at which the fiber does not spontaneously elongate during the preheating process, causing yarn path disturbance. For example, in the case of PET, which has a glass transition temperature of around 70°C, this preheating temperature is usually set to about 80 to 95°C. In addition, in the case of a polymer that does not exhibit a glass transition, the dynamic viscoelasticity measurement (tan δ) of the composite fiber is performed, and a temperature equal to or higher than the peak temperature on the high-temperature side of the obtained tan δ can be selected as the preheating temperature.

As for the stretching, the spun composite fiber and multifilament may be stretched after being wound up, or may be stretched immediately after spinning without being wound up, but it is more preferable to carry out yarn processing that involves stretching. By carrying out yarn processing, the unevenness of the textile surface becomes more complex, which improves the resistance to friction, texture, and water repellency that are the features of the present invention.

Here, when performing yarn processing involving drawing, it is preferable to use highly oriented undrawn yarn obtained from high-speed spinning. Highly oriented undrawn yarn has a structure with oriented amorphous and moderate crystal nuclei, has a fast crystallization rate, and is suitable for yarn processing because it can prevent yarn breakage by preventing fusion in the heater and can suppress fuzz due to a decrease in drawing tension. Methods for producing such highly oriented undrawn yarn vary slightly depending on the fiber diameter, polymer type, and viscosity, but in the studies of the present inventors, a composite fiber with good yarn processability can be obtained by selecting a winding speed during spinning from the range of 2000 to 4000 m/min.

The yarn processing is not particularly limited as long as it is a normal yarn processing technique such as false twist processing or non-uniform stretch processing, but from the viewpoint of changing the crimp form into a non-uniform form and making the resulting feel and texture more complex, false twist processing and non-uniform stretch processing are more preferable.

The method of false twisting is not particularly limited as long as it is a commonly used method, but considering productivity, it is preferable to use a friction false twist machine using a disk or belt. False twisting creates a multiple crimp form that combines shrinkage difference shrinkage and mechanical crimp imparted by false twisting, making the unevenness of the textile surface more complex and improving the resistance to friction, texture, and water repellency that are the features of this invention.

To stably produce crimped yarn using the present invention through false twist processing, it is preferable to control the crimp form by the actual number of twists of the yarn bundle in the twisting region.

In other words, the false twist number T (unit: turns/m), which is the number of twists of the yarn bundle in the twisting region, is determined according to the total fineness Df (unit: dtex) of the yarn bundle after false twist processing. It is preferable to set the false twist conditions, such as the rotation speed and processing speed of the twisting mechanism, so as to satisfy the following condition.
20000/ ^Df0.5 ≦T≦40000/ ^Df0.5

The false twist number T here is measured by the following method. That is, a yarn bundle running in the twisting area of the false twist process is sampled at a length of 50 cm or more so as not to untwist just before the twister. The sampled yarn sample is then attached to a twist detector, and the twist number is measured by the method described in JIS L1013 (2010) 8.13, which is the false twist number T. When the false twist number satisfies the above conditions, a multiple crimp form is achieved in which the crimp due to shrinkage difference and the mechanical crimp imparted by the false twist process are combined.

Furthermore, under the above false twist conditions, it is advisable to adjust the draw ratio in the twisting region. The draw ratio here is calculated as Vd/V0, using the peripheral speed V0 of the roller that supplies the yarn to the twisting region and the peripheral speed Vd of the roller installed immediately after the twisting mechanism. When a drawn yarn is used for the supply yarn, Vd/V0 can be set to 0.9 to 1.4 times, and when a highly oriented undrawn yarn is used for the supply yarn, Vd/V0 can be set to 1.2 to 2.0 times, and drawing can be performed simultaneously with the false twisting process. By setting the draw ratio in this range, it is possible to impart crimp to the entire composite fiber in the multifilament without causing excessive tension or slack in the yarn bundle in the twisting region.

Furthermore, from the viewpoint of firmly fixing the crimp obtained in the false twisting process, it is preferable to determine the false twisting temperature in the range of Tg + 50 to Tg + 150°C, based on the Tg of the polymer with the higher Tg in the composite polymers. The false twisting temperature here means the temperature of the heater installed in the twisting region. By setting the false twisting temperature in this range, the polymer that has been significantly twisted and deformed in the cross section of the composite fiber can be sufficiently structurally fixed, thereby improving the dimensional stability of the crimp obtained in the false twisting process.

It is also preferable to use non-uniform stretching to obtain thick and thin fibers with stretched and unstretched parts randomly arranged in the fiber axis direction, by performing stretching at a stretch ratio that does not exceed the natural stretch ratio of the composite fiber. By performing non-uniform stretching, in addition to the difference in dyeability between the single yarns, differences in dyeability also occur between the stretched and unstretched parts, so that the color shading is emphasized, and the crimp form differs between the stretched and unstretched parts, making it possible to express a heathered look and texture like natural materials when made into a fabric. Furthermore, if false twisting is performed consecutively after non-uniform stretching, a material that combines heathered look and texture due to multiple crimp forms can be obtained, so this is considered to be a more preferable range.

Furthermore, other fibers may be mixed with the composite fiber and multifilament of one embodiment of the present invention before or after yarn processing. The method of mixing is not particularly limited, and general mixing methods such as interlace mixing and taslan mixing can be used.

When the composite fiber of this embodiment is a sea-island composite fiber and segments A and B are separated by removing the sea component, the sea component may be composed of a known polymer that is soluble in a solvent or hot water, and the composite fiber may be immersed in a solvent in which the sea component polymer is soluble to remove the sea component polymer. For example, when the sea component polymer is a copolymerized polyethylene terephthalate or polylactic acid in which 5-sodium sulfoisophthalic acid or polyethylene glycol is copolymerized, an alkaline aqueous solution such as a sodium hydroxide aqueous solution may be used. As a method for treating the composite fiber of this embodiment with an alkaline aqueous solution, for example, a woven or knitted fabric or a fiber structure made of the composite fiber may be immersed in the alkaline aqueous solution. At this time, it is preferable to heat the alkaline aqueous solution to 50°C or higher, since this can hasten the progress of hydrolysis. Furthermore, if a fluid dyeing machine or the like is used, it is preferable from an industrial point of view, since a large amount can be treated at once.

When the multifilament of this embodiment is used as a textile product, after the composite fiber and multifilament of this embodiment are made into a textile, water repellency, antistatic, flame retardant, moisture absorption, antibacterial, softening, and other known post-processing can be used in combination as necessary. However, in textile products, particularly woven and knitted fabrics, which contain the multifilament of this embodiment in part, the presence of fine and complex irregularities on the textile surface reduces the contact area with water when water repellent processing is applied, and therefore water repellent processing is particularly preferred as a post-processing step. In addition, the presence of fine and complex irregularities on the textile surface can also improve the washing durability of functional processing agents such as water repellency, antistatic, flame retardant, moisture absorption, antibacterial, and softening.

When applying water-repellent treatment, fluorine-based or non-fluorine-based water-repellent agents (e.g., silicone-based, hydrocarbon-based, or any other water-repellent agent) can be used. The water-repellent treatment process is not particularly limited to padding, spraying, coating, etc., but the padding method is preferred in order to allow the water-repellent agent to penetrate deep into the woven or knitted fabric.

In order to improve the durability of the water repellency, it is preferable to use a crosslinking agent in combination with the water repellent. As the crosslinking agent, at least one of melamine-based resins, blocked isocyanate-based compounds (polymerization), glyoxal-based resins, and imine-based resins can be used, and there is no particular limitation on the crosslinking agent.

The method of weaving or knitting the woven or knitted fabric of which the multifilament of this embodiment is a part is not particularly limited, and the fabric can be woven or knitted by a normal method. When the woven or knitted fabric is a woven fabric, examples of the method include a water jet loom, an air jet loom, a rapier loom, and a jacquard loom. When the woven or knitted fabric is a knitted fabric, examples of the method include a circular knitting machine and a warp knitting machine.

The following examples are provided to specifically explain the composite fiber and multifilament of the present invention.

The following evaluations were carried out for the examples and comparative examples.

A. Melt Viscosity of Polymer The chip-shaped polymer was dried to a moisture content of 200 ppm or less using a vacuum dryer, and the melt viscosity was measured using a Capillograph manufactured by Toyo Seiki Co., Ltd. The measurement temperature was the same as the spinning temperature, and the time from the sample being put into the heating furnace in a nitrogen atmosphere to the start of the measurement was 5 minutes. The value at a shear rate of 1216 s ^-1 was evaluated as the melt viscosity of the polymer.

B. Melting point of polymer The chip-shaped polymer was dried in a vacuum dryer to a moisture content of 200 ppm or less, and about 5 mg was weighed out. Using a TA Instruments differential scanning calorimeter (DSC) Q2000 model, the temperature was raised from 0°C to 300°C at a heating rate of 16°C/min, and then the temperature was held at 300°C for 5 minutes to perform DSC measurement. The melting point was calculated from the melting peak observed during the heating process. The measurement was performed three times for each sample, and the average value was taken as the melting point. When multiple melting peaks were observed, the melting peak top on the highest temperature side was taken as the melting point.

C. Fineness The mass of 100 m of fiber was measured, and the mass was multiplied by 100. This operation was repeated 10 times, and the average value was rounded off to the nearest whole number to obtain the fineness (dtex).

D. Flatness of a segment in a composite fiber The composite fiber is embedded in an embedding agent such as epoxy resin, and an image of the fiber cross section perpendicular to the fiber axis is taken with a scanning electron microscope (SEM) manufactured by Hitachi at a magnification that allows observation of a single composite fiber. The captured image is analyzed using computer software WinROOF manufactured by Mitani Shoji, and the long axis is taken as a straight line connecting the two points (a1, a2) that are the farthest apart among any points on the periphery of the segment as shown in FIG. 1 (a), and the short axis is taken as a straight line connecting the intersection point (b1, b2) of the periphery of the fiber with a straight line that passes through the midpoint of the long axis and intersects the long axis at right angles. The value obtained by dividing the length of the long axis by the length of the short axis is calculated, and the value is rounded to one decimal place. In addition, when there are multiple segments of the same type, the simple number average of the flatnesses obtained for all the segments of the same type is calculated, and the value rounded to one decimal place is adopted.

E. Cross-sectional areas of segments in composite fibers ( _SA , _SB )
The composite fiber is embedded in an embedding agent such as epoxy resin, and an image of the fiber cross section perpendicular to the fiber axis is taken with a scanning electron microscope (SEM) manufactured by Hitachi at a magnification at which a single composite fiber can be observed. The captured image is analyzed using computer software WinROOF manufactured by Mitani Shoji to calculate the cross-sectional area ( ^μm2 ) of one segment present in the fiber cross section of the composite fiber, and the value rounded off to the first decimal place is used as the cross-sectional area of the segment. Note that when there are multiple segments of the same type, the simple number average of the cross-sectional areas ( ^μm2 ) of all the segments of the same type is calculated, and the value rounded off to the first decimal place is used.

F. Filament flatness A multifilament consisting of 10 or more filaments extracted from a textile is embedded in an embedding agent such as epoxy resin, and an image of the fiber cross section perpendicular to the fiber axis is taken with a scanning electron microscope (SEM) manufactured by Hitachi at a magnification at which the multifilament can be observed. The image taken is analyzed using computer software WinROOF manufactured by Mitani Shoji, and as shown in FIG. 5(b), a straight line connecting the two most distant points (a1, a2) among any points on the outer periphery of the filament is taken as the long axis, and a straight line connecting the intersection point (b1, b2) of the outer periphery of the fiber with a straight line passing through the midpoint of the long axis and perpendicular to the long axis is taken as the short axis, and the value obtained by dividing the length of the long axis by the length of the short axis is calculated, and the value rounded off to the first decimal place is taken as the flatness. In addition, when there are multiple filaments of the same type in the multifilament, a simple number average of the flatnesses obtained for all filaments of the same type is calculated, and the value rounded off to the first decimal place is adopted.

G. Filament fiber diameter (D _A , D _B )
A multifilament consisting of 10 or more filaments extracted from a textile is embedded in an embedding agent such as epoxy resin, and an image of the fiber cross section perpendicular to the fiber axis is taken with a scanning electron microscope (SEM) manufactured by Hitachi at a magnification at which the multifilament can be observed. The image is analyzed using computer software WinROOF manufactured by Mitani Shoji to measure the cross-sectional area of one filament present in the fiber cross section of the multifilament, and the diameter calculated as a perfect circle is measured in μm units to one decimal place, and the value rounded off to the nearest decimal place is taken as the fiber diameter (μm). In addition, when there are multiple filaments of the same type, the simple number average of the fiber diameters calculated for all filaments of the same type is calculated, and the value rounded off to the nearest decimal place is adopted.

H. Fluorine Content The fluorine content was calculated by the following combustion ion chromatography measurement method.
(1) Preparation of sample: After cutting the test fabric into small pieces, the samples were freeze-pulverized and dried under reduced pressure (at room temperature for 2 hours).
(2) Preparation of standard solution: A fluorine ion standard solution (1005 μg/mL, Wako Pure Chemical Industries, Lot. KPP6061) is successively diluted with the bromine internal standard solution to prepare standard solutions. A calibration curve is prepared using the analytical data of the standard solution that is appropriate for the analysis of the concentration in the sample.
(3) Combustion ion chromatography of sample: A sample was weighed and burned in a combustion tube of a combustion apparatus ("AQF-100", manufactured by Mitsubishi Chemical Analytech Co., Ltd.) under the following conditions. The gas generated in an absorption unit ("GA-100", manufactured by Mitsubishi Chemical Analytech Co., Ltd.) was absorbed into a solution, and a part of the absorbed solution was analyzed by ion chromatography ("ICS1500", manufactured by DIONEX). The sample was measured with n=2 from the weight, and the average value of the measured values (ng/g) was calculated. Note that a measured value of 25 ng/g or less was regarded as "below the detection limit."
<Combustion and absorption conditions>
Electric furnace temperature: Inlet 900°C, Outlet 1000°C
Gas: Ar/O ₂ 200 mL/min, O ₂ 400 mL/min Absorption solution: H ₂ O 290 μg/mL, internal standard Br 2 μg/mL
Absorption volume: 10 mL
<Ion chromatography/anion analysis conditions>
Mobile phase: 2.7 mmol/L _Na2CO3 / _0.3 mmol/L _NaHCO3
Flow rate: 1.50 mL/min Detector: Electrical conductivity detector Injection volume: 100 μL

I. Textile texture evaluation (flexibility, resilience, smoothness)
The number of composite fibers is adjusted so that the cover factor in the warp direction (CFA) is 800 and the cover factor in the weft direction (CFB) is 1200, to prepare a 2/1 twill fabric.

Here, the CFA and CFB are values obtained by measuring the warp density and weft density of the fabric in a 2.54 cm section in accordance with JIS L1096:2010 8.6.1 and calculating from the formulas: CFA = warp weave density [pieces/2.54 cm] × (total warp fineness [dtex]) ^1/2 , and CFB = weft weave density [pieces/2.54 cm] × (total weft fineness [dtex]) ^1/2 . The fabric obtained was subjected to scouring, alkali treatment, moist heat treatment, heat setting, dyeing, and water repellency in this order, and then evaluated for three textures, namely softness, resilience, and smoothness, using the following methods.

I-1. Flexibility: The flexibility was evaluated using a pure bending tester (KES-FB2) manufactured by Kato Tech Co., Ltd., in the following manner. That is, a 20 cm x 20 cm woven fabric was held with an effective sample length of ²⁰ cm x 1 ^cm , and bent in the weft direction under the condition of a maximum curvature of ±2.5 cm ^-1 . The average value of the difference between the bending moment (gf cm/cm) per unit width of the curvatures of 0.5 cm ^-1 and 1.5 cm ^{-1 divided by the curvature difference of 1 cm -1 and the difference between the bending moment (gf cm/cm) per unit width of the curvatures of -0.5 cm -1 and -1.5 cm -1} ^divided by the curvature difference of 1 cm ^-1 was calculated. This operation was performed three times per location, and a simple number average of the results of performing this for a total of 10 locations was calculated, and the value rounded off to the fourth decimal place and multiplied by 100 was taken as the bending hardness B x 10 ^-2 (gf cm ² /cm). Here, 1 gf·cm ² /cm=9.8 mN·cm ² /cm. From the obtained bending hardness B×10 ⁻² (gf·cm ² /cm), flexibility was judged into four stages based on the following criteria.
S: Excellent flexibility (bending hardness B×10 ⁻² ≦0.5)
A: Good flexibility (0.5<bending hardness B×10 ⁻² ≦1.0)
B: Flexible (1.0<bending hardness B×10 ⁻² ≦1.5)
C: Poor flexibility (1.5<bending hardness B×10 ⁻² ).

I-2. Resilience Using a pure bending tester (KES-FB2) manufactured by Kato Tech, a 20 cm x 20 cm woven fabric was held with an effective sample length of 20 cm x 1 cm and bent in the weft direction to calculate the hysteresis width (gf cm/cm) at a curvature of ±1.0 cm ^-1 . This operation was performed three times per location, and a simple number average of the results of performing this for a total of 10 locations was calculated, rounded off to the fourth decimal place, and multiplied by 100 to obtain the bending recovery 2HB x 10 ^-2 (gf cm/cm). Note that 1 gf cm/cm = 9.8 mN cm/cm. The resilience was judged into four stages based on the following criteria from the obtained bending recovery 2HB x 10 ^-2 (gf cm/cm).
S: Excellent resilience (bending recovery 2HB×10 ⁻² ≦0.5)
A: Good resilience (0.5<bending recovery 2HB×10 ⁻² ≦1.0)
B: Resilient (1.0<bending recovery 2HB×10 ⁻² ≦1.5)
C: Poor resilience (1.5<bending recovery 2HB×10 ⁻² ).

I-3. Smooth feeling Using an automated surface tester (KES-FB4) manufactured by Kato Tech, a load of 50 g was applied to a 1 cm x 1 cm terminal wound with piano wire in a 10 cm x 10 cm area of a 20 cm x 20 cm woven fabric, and the terminal was slid at a speed of 1.0 mm/sec to obtain the variation MMD of the average friction coefficient. This operation was performed three times per location, and a simple number average was obtained from the results of performing this for a total of 10 locations, and the value obtained by rounding off to the fourth decimal place and multiplying by 100 was taken as the friction variation (x 10 ^-2 ). The smooth feeling was judged from the obtained friction variation into four stages based on the following criteria.
S: Excellent smooth feeling (friction fluctuation 2.0 or less)
A: Good smooth feeling (1.5≦friction fluctuation<2.0)
B: Smooth feeling (1.0≦friction variation<1.5)
C: Poor smooth feeling (friction variation < 1.0).

J. Textile function evaluation (stretchability, water repellency)
The number of composite fibers is adjusted so that the cover factor in the warp direction (CFA) is 800 and the cover factor in the weft direction (CFB) is 1200, to prepare a 2/1 twill fabric.

Here, the CFA and CFB are values obtained by measuring the warp density and weft density of the fabric in a 2.54 cm section in accordance with JIS L1096:2010 8.6.1 and calculating from the formulas: CFA = warp weave density [pieces/2.54 cm] × (total warp fineness [dtex]) ^1/2 , and CFB = weft weave density [pieces/2.54 cm] × (total weft fineness [dtex]) ^1/2 . The fabric obtained was subjected to scouring, alkali treatment, wet heat treatment, heat setting, dyeing, and water-repellent treatment in this order, and then the two functions of water repellency and stretchability were evaluated using the following methods.

J-1. Stretchability Stretchability was measured according to the elongation A method (constant speed elongation method) described in Section 8.16.1 of JIS L1096:2010. The strip method was used with a load of 17.6 N (1.8 kg), and the test conditions were a sample width of 5 cm x length of 20 cm, clamp interval of 10 cm, and tensile speed of 20 cm/min. The initial load was a weight equivalent to a sample width of 1 m according to the method of JIS L1096:2010. The simple number average of the results of the test performed three times in the weft direction of the woven fabric was calculated, and the value rounded off to the nearest whole number was used as the elongation rate (%). The stretchability was evaluated based on the obtained elongation rate in three stages according to the following criteria.
S: Excellent stretchability (elongation rate 30 or less)
A: Good stretchability (20≦elongation rate<30)
B: Stretchable (10≦elongation rate<20)
C: Poor stretchability (elongation rate < 10).

J-2. Water repellency (water drop sliding angle)
Water repellency was measured by placing 20 μL of water at 20° C. on a 20 cm×20 cm fabric surface on a horizontal platform using a solid-liquid interface analyzer (DropMaster 700, manufactured by Kyowa Interface Science Co., Ltd.), gently tilting the fabric from 0 degrees at a constant speed (approximately 1 degree/sec) at 1 degree increments, and determining the inclination angle (°) at which the droplet slid down. This operation was performed at any five points on the fabric, and the simple number average of the results was calculated, and the value rounded off to the nearest whole number was used as the water droplet sliding angle (°). Water repellency was evaluated based on the obtained water droplet sliding angle in three stages according to the following criteria.
S: Excellent water repellency (water drop sliding angle ≦10)
A: Good water repellency (10<water drop sliding angle≦15)
B: Water repellent (15<water drop sliding angle≦20)
C: Poor water repellency (water drop sliding angle < 20).

K. Textile surface quality evaluation (gloss resistance, abrasion resistance)
The number of composite fibers is adjusted so that the cover factor in the warp direction (CFA) is 800 and the cover factor in the weft direction (CFB) is 1200, to prepare a 2/1 twill fabric.

Here, the values are calculated from the formulas: CFA = warp weave density [pieces/2.54 cm] × (total warp fineness [dtex]) ^1/2 , and CFB = weft weave density [pieces/2.54 cm] × (total weft fineness [dtex]) ^1/2 . The obtained woven fabric was subjected to scouring, alkali treatment, moist heat treatment, heat setting, dyeing treatment, and water repellent treatment in this order, and then the two surface qualities of shine resistance and abrasion resistance were evaluated using the following methods.

K-1. Shine Resistance Using a frosting tester, a woven fabric was attached to a sample holder at the center of the upper part of the device and rubbed against the friction surface at the bottom of the device for a certain period of time. The woven fabric that was actually worn and had a shine was used as a sample, and the number of times that it was rubbed until it had a shine-like luster equivalent to that of the above-mentioned actually worn sample was determined as the specified number of times, and the sample after rubbing at that time was determined as a sample of grade 1. In addition, the sample after rubbing when the sample sample was rubbed half the specified number of times was determined as a sample of grade 3, and the sample before rubbing was determined as a sample of grade 5. The evaluation sample was rubbed, and the glossiness of the sample after rubbing was visually compared with the sample under a D65 light source, and a grade rating of 1 to 5 was performed in increments of 1 grade. In addition, if it was less glossy than grade 3 and more glossy than grade 5, it was determined as grade 4, and if it was less glossy than grade 1 and more glossy than grade 3, it was determined as grade 2. From the results of the obtained grade ratings, the shine resistance was rated in four stages based on the following criteria.
S: Excellent shine resistance (Grade: Grade 5)
A: Good shine resistance (grade: grade 4)
B: Resistant to shine (Grade: Grade 2, Grade 3)
C: Poor shine resistance (grade: Grade 1).

K-2. Abrasion resistance Abrasion resistance was measured by using an appearance retention tester (manufactured by Daiei Scientific Instruments Co., Ltd.) to wet a woven fabric cut into a circle with a diameter of 6 cm with distilled water and attach it to a disk. A further woven fabric cut into a circle with a diameter of 11 cm was fixed on a horizontal plate while still dry. The disk with the woven fabric wetted with distilled water attached was horizontally brought into contact with the woven fabric fixed on the horizontal plate, and the disk was moved circularly for 10 minutes at a load of 420 g and a speed of 85 rpm so that the center of the disk drew a circle with a diameter of 38 mm, causing friction between the two pieces of woven fabric. After the friction was completed, the degree of discoloration of the woven fabric attached to the disk was graded from 1 to 5 in 0.5 grade increments using a gray scale for discoloration. From the results of the grades obtained, the abrasion resistance was graded in four stages based on the following criteria.
S: Excellent abrasion resistance (grade: 4.5 or higher)
A: Good abrasion resistance (grade: 3.5 grade, 4 grade)
B: Good abrasion resistance (grade: 2.5 grade, 3 grade)
C: Poor abrasion resistance (grade: grade 2 or lower).

[Example 1]
As polymer 1, polyethylene terephthalate copolymerized with 8 mol% of 5-sodium sulfoisophthalic acid and 9 mass% of polyethylene glycol (SSIA-PEG copolymerized PET, melt viscosity: 100 Pa s, melting point: 233°C), as polymer 2, polyethylene terephthalate copolymerized with 7 mol% of isophthalic acid (IPA copolymerized PET, melt viscosity: 140 Pa s, melting point: 232°C), and as polymer 3, polyethylene terephthalate (PET, melt viscosity: 30 Pa s, melting point: 254°C) were prepared.

After melting these polymers separately at 290°C, polymer 1/polymer 2/polymer 3 were weighed out to a mass ratio of 20/40/40 and fed into a spin pack equipped with a composite spinneret as shown in Figure 12. The fed polymers were discharged from the discharge holes to produce a sea-island composite fiber as shown in Figure 1(b), with polymer 1 located at z, polymer 2 located at x1 and y1, and polymer 3 located at x2 and y2.

After the extruded composite polymer stream was cooled and solidified, an oil agent was added, the stream was wound up at a spinning speed of 1,500 m/min, and stretched between rollers heated to 90°C and 130°C to produce a composite fiber of 110 dtex-24 filaments.

The obtained composite fiber had, in the fiber cross section, eight flattened segments B (flatness 3.0) having a side-by-side composite structure consisting of y1 and y2 in Fig. 1(b) arranged around an eight-lobed segment A having a side-by-side composite structure consisting of x1 and x2 in Fig. 1(b). The cross-sectional area S _A per segment A was 167 µm ² and the cross-sectional area S _B per segment B was 13 µm ² , and the segment B had a smaller cross-sectional area than the segment A, confirming that the composite fiber was the present invention.

A 2/1 twill fabric was obtained using the resulting composite fibers as warp and weft. The resulting fabric was scoured for 10 minutes in 80°C warm water containing a surfactant, and heated to 90°C using a 1% by mass aqueous solution of sodium hydroxide in a jet dyeing machine to remove over 99% of the easily soluble polymer, Polymer 1. The fabric was then subjected to a wet heat treatment at 130°C for 30 minutes in the jet dyeing machine, and then heat set at 180°C for 1 minute with a tentering ratio of 5%.

Next, as a dyeing process, the fabric was immersed in an aqueous solution containing a disperse dye (black) and dyeing assistants, and dyed at 130°C for 60 minutes, followed by rinsing with water. Next, the fabric was immersed in an aqueous solution containing a reducing cleaner, and reduced and cleaned at 80°C for 20 minutes, followed by rinsing with water and air drying. After that, as a water-repellent process, the fabric was immersed in a treatment solution containing 4% by mass of "Neoseed" (registered trademark) NR-158 (Nicca Chemical Co., Ltd., non-fluorine (paraffin-based) water repellent, solid content 30%), 0.2% by mass of "Beckamin" (registered trademark) M-3 (DIC Corporation), 0.15% by mass of Catalyst ACX (DIC Corporation), 1% by mass of isopropyl alcohol, and 94.65% by mass of water, and squeezed out at a wringing rate of 60% with a mangle, then dried at 130°C for 2 minutes with a pin tenter, and cured at 170°C for 1 minute.

The obtained woven fabric was composed of a multifilament in which eight-lobed filament A having a side-by-side composite structure consisting of X1 and X2 in FIG. 6(a) and flat filament B having a side-by-side composite structure consisting of Y1 and Y2 in FIG. 6(b) were uniformly mixed. The fiber diameter of filament A was 15 μm, and the fiber diameter of filament B was 4 μm, and filament B had a smaller fiber diameter than filament A, confirming that it was a multifilament of the present invention.

The woven fabric composed of the multifilament had a good resilience (bending recovery 2HB: 0.8×10 ^-2 gf·cm/cm (7.8×10 -2 mN·cm/cm)) and good flexibility (bending hardness B: 0.8×10 ^-2 gf·cm ² /cm (7.8×10 ^-2 mN·cm ² /cm)) because filament A, which is a normal fiber, and filament B ^, which is an ultrafine fiber, were uniformly mixed in the multifilament. In addition, since the ultrafine fiber filament B has a side-by-side composite structure and is therefore crimped, fine gaps are formed between the fibers due to steric hindrance caused by this crimping, and the friction surface is not fixed but can move flexibly, resulting in high resistance to friction and good shine resistance (shine resistance: grade 4) and abrasion resistance (discoloration: grade 3.5). In addition, since the ultrafine fibers having crimping are arranged on the surface layer, fine irregularities are formed on the surface of the fabric, giving it a good smooth feel (friction fluctuation: 1.7 x ^10-2 ), and this was a woven fabric that combined resistance to friction and texture not found in conventional materials.

Furthermore, since filament A also has a side-by-side composite structure, all filaments in the multifilament are crimped, resulting in good stretchability (elongation rate: 25%). In addition, fine and complex irregularities are formed that combine the fine irregularities caused by the crimping of filament B, which is an ultrafine fiber, with the coarse irregularities caused by filament A, which is a normal fiber. As a result, the fluorine content in the fabric measured by combustion ion chromatography is below 25 ng/g, which is below the detection limit, and yet the fabric contains a non-fluorine-based water repellent agent, and yet the fabric has good water repellency (water droplet sliding angle: 11°). The results are shown in the table.

[Examples 2 and 3]
The procedure of Example 1 was followed except for changing the extrusion rate so that the cross-sectional area S _A of the composite fiber segment A was 66 μm ² , the cross-sectional area _S _B of the composite fiber segment B was 5 μm ² (Example 2), and the cross-sectional area S A of the composite fiber segment A was 670 μm ² , and the cross-sectional area S _B of the composite fiber segment B was 50 μm ² (Example 3).

In Example 2, the cross-sectional area of the composite fiber segments A and B is reduced, and the fiber diameter of the filaments A and B of the multifilament that constitutes the resulting woven fabric is also reduced, improving the flexibility and shine resistance of the woven fabric. As the fiber diameter is reduced, the crimp loops that appear are also finer, so the unevenness formed on the woven fabric surface is also finer, and the contact area with water droplets is reduced, improving water repellency.

In Example 3, the cross-sectional area of the composite fiber segments A and B increased, and the fiber diameter of the filaments A and B of the multifilament that constitutes the resulting woven fabric also increased, improving the resilience of the woven fabric. As the fiber diameter increased, the resulting crimp loops also became coarser, and the irregularities formed on the woven fabric surface also became coarser, improving the smooth feel. The results are shown in the table.

[Example 4]
The same procedures as in Example 1 were carried out except that the cross-sectional shape of segment B was changed to a trilobal shape (flatness: 1.4) as shown in FIG. 2(a).

In Example 4, irregularities were formed in filament B in the resulting woven fabric, amplifying the diffuse reflection of light and suppressing uneven gloss (glare) in the woven fabric. The results are shown in the table.

[Examples 5 and 6]
The same operations as in Example 1 were carried out except that the cross-sectional shape of segment A was changed to a four-lobe shape as shown in FIG. 2(b) (Example 5) or a round shape as shown in FIG. 2(c) (Example 6).

In Example 5, the resilience improved as the degree of irregularity of filament A in the resulting fabric increased. In addition, as the fiber diameter of filament B increased, the crimp loops that appeared also became coarser, and the unevenness formed on the fabric surface also became coarser, improving the smooth feel.

In Example 6, the filament A in the resulting woven fabric was round, which not only reduced bending stiffness and improved flexibility, but also increased the distance between the centers of gravity of the polymers that make up filament A, improving crimp expression and improving stretchability. The results are shown in the table.

[Examples 7 and 8]
The same procedures as in Example 1 were repeated except that polymer 2 was changed to high viscosity polyethylene terephthalate (high viscosity PET, melt viscosity: 300 Pa·s, melting point: 254°C) (Example 7) or polypropylene terephthalate (PPT, melt viscosity: 130 Pa·s, melting point: 231°C) (Example 8).

In Example 7, the multifilaments constituting the resulting woven fabric were made only of PET without any copolymerization components, providing an excellent resilience.

In Example 8, the rubber elasticity of PPT is also combined to give the resulting woven fabric a more flexible feel, and the crimp expression of filaments A and B is improved, so not only is the stretch function significantly improved, but the unevenness that appears on the fiber surface becomes more complex, improving the smooth feel and water repellency. The results are shown in the table.

[Example 9]
The same procedure as in Example 8 was repeated except that the cross-sectional shape of segment B was changed to have an eccentric core-sheath type composite structure as shown in FIG. 1(c).

In Example 9, the surface of filament B in the resulting woven fabric was coated with PET, suppressing wear of the PPT and providing good wear resistance. The results are shown in the table.

[Comparative Example 1]
As polymer 1, polyethylene terephthalate copolymerized with 8 mol% of 5-sodium sulfoisophthalic acid and 9 mass% of polyethylene glycol (SSIA-PEG copolymerized PET, melt viscosity: 100 Pa s, melting point: 233°C), as polymer 2, polyethylene terephthalate copolymerized with 7 mol% of isophthalic acid (IPA copolymerized PET, melt viscosity: 140 Pa s, melting point: 232°C), and as polymer 3, polyethylene terephthalate (PET, melt viscosity: 30 Pa s, melting point: 254°C) were prepared.

After melting these polymers separately at 290°C, the weight ratio of polymer 1/polymer 2/polymer 3 was measured to be 30/35/35, and the mixture was poured into a spin pack equipped with a known composite spinneret. The polymers were discharged from the discharge hole to produce a composite structure such as the sea-island composite fiber shown in Figure 3(b), where polymer 1 is located at z, polymer 2 is located at y1, and polymer 3 is located at y2 in Figure 3(b).

The obtained composite fiber had 12 segments of one type arranged in the fiber cross section, each having a side-by-side composite structure consisting of y1 and y2 in Figure 3(b). The cross-sectional area of each segment was ²⁰ μm2.

A 2/1 twill fabric was obtained using the obtained composite fibers as warp and weft. The obtained fabric was subjected to refining, alkali treatment, wet heat treatment, heat setting, dyeing, and water repellent treatment in that order under the same conditions as in Example 1, to obtain a fabric composed of one type of filament having a side-by-side composite structure consisting of Y1 and Y2 in Figure 11. The fiber diameter of the filament was 5 μm.

In Comparative Example 1, the fabric was made only of ultrafine filaments, which not only lacked a sense of resilience, but also flattened the fine irregularities formed on the fabric surface, impairing the smooth feel. The results are shown in the table.

[Comparative Example 2]
As polymer 1, polyethylene terephthalate copolymerized with 7 mol % isophthalic acid (IPA copolymerized PET, melt viscosity: 140 Pa·s, melting point: 232° C.) was prepared, and as polymer 2, polyethylene terephthalate (PET, melt viscosity: 30 Pa·s, melting point: 254° C.) was prepared.

After melting these polymers separately at 290°C, the polymer 1/polymer 2 were weighed out to a mass ratio of 50/50 and poured into a spinning pack equipped with a known composite spinneret. The incoming polymers were discharged from the discharge hole to produce a composite fiber as shown in Figure 11, with polymer 1 located at X1 and polymer 2 located at X2 in Figure 11.

After the extruded composite polymer stream was cooled and solidified, an oil agent was added, the stream was wound up at a spinning speed of 1,500 m/min, and stretched between rollers heated to 90°C and 130°C to produce a composite fiber of 110 dtex-48 filaments.

A 2/1 twill fabric was obtained using the obtained composite fibers as warp and weft. The obtained fabric was subjected to scouring, alkali treatment, wet heat treatment, heat setting, dyeing, and water repellent treatment in that order under the same conditions as in Example 1, to obtain a fabric composed of one type of filament having a side-by-side composite structure consisting of X1 and X2 in Figure 11. The fiber diameter of the filament was 15 μm.

In Comparative Example 2, the material consisted only of filaments, which are normal fibers, and thus not only did it lack flexibility, but it also had poor shine resistance due to the large area of flat areas caused by friction and wear of the fibers. The results are shown in the table.

[Comparative Example 3]
As polymer 1, polyethylene terephthalate copolymerized with 7 mol % isophthalic acid (IPA copolymerized PET, melt viscosity: 140 Pa·s, melting point: 232° C.) was prepared, and as polymer 2, polyethylene terephthalate (PET, melt viscosity: 30 Pa·s, melting point: 254° C.) was prepared.

After the extruded composite polymer stream was cooled and solidified, an oil agent was added, the stream was wound up at a spinning speed of 1,500 m/min, and stretched between rollers heated to 90°C and 130°C to produce a composite fiber of 55 dtex-24 filaments.

Furthermore, a 55 dtex-72 filament composite fiber was produced using the same method as above, except for changing the number of nozzles in the composite spinneret.

The two types of composite fibers obtained were mixed using a known air nozzle, and then a 2/1 twill fabric was obtained as the warp and weft. The resulting fabric was subjected to refining, alkali treatment, wet heat treatment, heat setting, dyeing, and water repellent treatment in that order under the same conditions as in Example 1, to obtain a fabric composed of multifilaments in which filament A having a side-by-side composite structure consisting of X1 and X2 in Figure 11 and filament B having a side-by-side composite structure consisting of Y1 and Y2 in Figure 11 were mixed. The fiber diameter of filament A was 15 μm, and the fiber diameter of filament B was 8 μm.

In Comparative Example 2, the filament A, which is a normal fiber, and the filament B, which is a superfine fiber, were not mixed evenly, so in the areas where the filament A was unevenly present, the area of flat areas caused by friction, wear, etc. was large, and the shine resistance was poor. The results are shown in the table.

[Example 10]
As polymer 1, polyethylene terephthalate copolymerized with 8 mol% of 5-sodium sulfoisophthalic acid and 9 mass% of polyethylene glycol (SSIA-PEG copolymerized PET, melt viscosity: 100 Pa s, melting point: 233°C), as polymer 2, polyethylene terephthalate copolymerized with 7 mol% of isophthalic acid (IPA copolymerized PET, melt viscosity: 140 Pa s, melting point: 232°C), and as polymer 3, polyethylene terephthalate (PET, melt viscosity: 30 Pa s, melting point: 254°C) were prepared.

After melting these polymers separately at 290°C, the weight ratio of polymer 1/polymer 2/polymer 3 was measured to be 20/15/65, and the mixture was poured into a spin pack equipped with a composite spinneret as shown in Figure 12. The polymers were discharged from the discharge hole to produce a composite structure such as the sea-island composite fiber shown in Figure 1(a) where polymer 1 is located at z, polymer 2 is located at y1, and polymer 3 is located at x1 and y2.

In the cross section of the obtained composite fiber, eight flattened segments B having a side-by-side composite structure consisting of y1 and y2 in Fig. 1(a) (flatness of 3.0) were arranged around an eight-lobed segment A consisting of x1 in Fig. 1(a). The cross-sectional area S _A per segment A was 167 ^µm2 , and the cross-sectional area S _B per segment B was 13 ^µm2 . The cross-sectional area of the segment B was smaller than that of the segment A, and it was confirmed that the composite fiber was the present invention.

A 2/1 twill fabric was obtained using the resulting composite fibers as warp and weft. The resulting fabric was scoured for 10 minutes in 80°C warm water containing a surfactant, and heated to 90°C using a 1% by mass aqueous solution of sodium hydroxide in a jet dyeing machine to remove more than 99% of the easily soluble polymer, Polymer 1. The fabric was then subjected to a wet heat treatment at 130°C for 30 minutes in the jet dyeing machine, followed by a heat set at 180°C for 1 minute with a tentering ratio of 5%.

Next, for the dyeing process, the fabric was immersed in an aqueous solution containing a disperse dye (black) and dyeing assistants, and dyed at 130°C for 60 minutes, after which it was rinsed with water. Next, the fabric was immersed in an aqueous solution containing a reducing detergent, and reduced-cleaned at 80°C for 20 minutes, after which it was rinsed with water and air-dried.

Then, for water repellency, the fabric was immersed in a treatment solution containing 4% by weight of "Neoseed" (registered trademark) NR-158 (Nicca Chemical Co., Ltd., non-fluorinated (paraffin-based) water repellent, solids content 30%), 0.2% by weight of "Beckamin" (registered trademark) M-3 (DIC Corporation), 0.15% by weight of Catalyst ACX (DIC Corporation), 1% by weight of isopropyl alcohol, and 94.65% by weight of water, and squeezed out with a mangle to a squeezing rate of 60%, then dried with a pin tenter at 130°C for 2 minutes and cured at 170°C for 1 minute.

The obtained woven fabric was composed of a multifilament in which eight-lobed filament A consisting of X1 in Fig. 5(a) and flat filament B consisting of Y1 and Y2 in Fig. 5(b) with a side-by-side composite structure (flatness of 3.0) were uniformly mixed. In addition, the fiber diameter of filament A was 15 μm, and the fiber diameter of filament B was 4 μm, and filament B had a smaller fiber diameter than filament A, confirming that it was a multifilament of the present invention.

The woven fabric composed of the multifilament had a good resilience (bending recovery 2HB: 0.6×10 ^-2 gf·cm/cm (5.9×10 -2 mN·cm/cm)) and good flexibility (bending hardness B: 1.0×10 ^-2 gf·cm ² /cm (9.8×10 ^-2 mN·cm ² /cm)) because filament A, which is a normal fiber, and filament B ^, which is an ultrafine fiber, were uniformly mixed in the multifilament. In addition, since the ultrafine fiber filament B has a side-by-side composite structure and is therefore crimped, fine gaps are formed between the fibers due to steric hindrance caused by this crimping, and the friction surface is not fixed but can move flexibly, resulting in high resistance to friction and providing shine resistance (shine level: 6%) and abrasion resistance (discoloration: grade 4). In addition, since the ultrafine fibers having crimping are arranged on the surface layer, fine irregularities are formed on the surface of the woven fabric, giving it a smooth feel (friction fluctuation: 1.3 x ^10-2 ), and this woven fabric combines friction resistance and texture, something not found in conventional materials.

Furthermore, by arranging a mixture of crimped ultrafine fibers and normal fibers on the surface, fine and complex irregularities are formed on the textile surface, and the fluorine content in combustion ion chromatography is below the detection limit of 25 ng/g, and the fabric contains a non-fluorinated water repellent agent, yet is water repellent (water droplet sliding angle: 18°). The results are shown in the table.

[Example 11]
The procedures of Example 9 were repeated except that polymer 1/polymer 2/polymer 3 were weighed out to give a mass ratio of 20/65/15 and flowed into a spin pack equipped with the composite spinneret shown in FIG. 12 , and the flowed-in polymers were discharged from the discharge hole to obtain a sea-island composite fiber as shown in FIG. 1(a), in which polymer 1 was located at z, polymer 2 was located at x1 and y1, and polymer 3 was located at y2.

In Example 11, segment A of the composite fiber is formed only from low-melting point IPA copolymerized PET, and filament A of the multifilament constituting the resulting woven fabric shrinks highly during heat treatment, resulting in a difference in thread length between filament A and filament B, which results in coarse irregularities formed on the woven fabric surface and a good smooth feel. In addition, the difference in thread length increases the gaps between the fibers, which reduces the area of flat parts caused by friction, wear, etc., and provides excellent shine resistance. The results are shown in the table.

[Example 12]
As polymer 1, nylon 6 (N6, melt viscosity: 190 Pa·s, melting point: 223°C) was prepared. As polymer 2, polyethylene terephthalate copolymerized with 7 mol% isophthalic acid (IPA copolymerized PET, melt viscosity: 140 Pa·s, melting point: 232°C) was prepared. As polymer 3, polyethylene terephthalate (PET, melt viscosity: 30 Pa·s, melting point: 254°C) was prepared.

After melting these polymers separately at 290°C, polymer 1/polymer 2/polymer 3 were weighed out to a mass ratio of 20/40/40 and fed into a spinning pack incorporating the composite spinneret shown in Figure 12. The fed polymers were discharged from the discharge hole to produce a core-sheath composite fiber as shown in Figure 1(c), with polymer 1 located at x1, polymer 2 located at y1, and polymer 3 located at y2 in Figure 1(c).

In the cross section of the obtained composite fiber, eight flattened segments B having a side-by-side composite structure consisting of y1 and y2 in Fig. 1(a) (flatness of 3.0) were arranged around an eight-lobed segment A consisting of x1 in Fig. 1(c) in the outer periphery. The cross-sectional area S _A per segment A was 209 ^µm2 , and the cross-sectional area S _B per segment B was 15 ^µm2 , and the segment B had a smaller cross-sectional area than the segment A, confirming that the composite fiber was the present invention.

A 2/1 twill fabric was obtained using the resulting composite fibers as warp and weft. The resulting fabric was scoured for 10 minutes in 80°C warm water containing a surfactant, then subjected to a wet heat treatment at 130°C for 30 minutes in a jet dyeing machine to separate segments A and B, after which it was heat set at 180°C for 1 minute with a tentering ratio of 5%.

Then, for water repellency, the fabric was immersed in a treatment solution containing 4% by mass of "Neoseed" (registered trademark) NR-158 (Nicca Chemical Co., Ltd., non-fluorinated (paraffin-based) water repellent, solids content 30%), 0.2% by mass of "Beckamin" (registered trademark) M-3 (DIC Corporation), 0.15% by mass of Catalyst ACX (DIC Corporation), 1% by mass of isopropyl alcohol, and 94.65% by mass of water, and after squeezing the liquid out at a squeezing rate of 60% using a mangle, it was dried at 130°C for 2 minutes using a pin tenter and cured at 170°C for 1 minute. The obtained fabric was composed of a multifilament in which eight-lobed filament A consisting of X1 in Figure 5(a) and flat filament B (flatness 3.0) having a side-by-side composite structure consisting of Y1 and Y2 in Figure 5(b) were uniformly mixed. In addition, the fiber diameter of filament A was 16 μm and the fiber diameter of filament B was 4 μm, and filament B had a smaller fiber diameter than filament A, confirming that it was a multifilament of the present invention.

The fabric composed of this multifilament has excellent flexibility because filament A is made of nylon 6, which has low elasticity and a low melting point. In addition, because filament A shrinks highly when heat treated, a difference in thread length is created between filament A and filament B, which results in large irregularities on the surface of the fabric, giving the fabric a smooth feel. In addition, the difference in thread length increases the gaps between the fibers, which reduces the area of flat areas caused by friction, wear, etc., giving the fabric excellent shine resistance. The results are shown in the table.

[Example 13]
The same operations as in Example 1 were carried out except that the 110 dtex-24 filament composite fiber obtained in Example 1 was false twisted at a twist ratio of 1.05 to form a 105 dtex-24 filament false twist textured yarn.

In Example 13, the false twist processing improves the crimping property, which not only significantly improves the stretch function, but also improves the smooth feel and water repellency by making the unevenness on the fiber surface more complex. The results are shown in the table.

[Example 14]
As polymer 1, polyethylene terephthalate copolymerized with 8 mol % of 5-sodium sulfoisophthalic acid and 9 mass % of polyethylene glycol (SSIA-PEG copolymerized PET, melt viscosity: 100 Pa s, melting point: 233° C.) was prepared. As polymer 2, nylon 66 (N66, melt viscosity: 200 Pa s, melting point: 255° C.) was prepared. As polymer 3, nylon 610 (N610, melt viscosity: 80 Pa s, melting point: 225° C.) was prepared.

After melting these polymers separately at 280°C, polymer 1/polymer 2/polymer 3 were weighed out to a mass ratio of 20/40/40 and fed into a spin pack equipped with a composite spinneret as shown in Figure 12. The fed polymers were discharged from the discharge holes to produce a sea-island composite fiber as shown in Figure 1(b), with polymer 1 located at z, polymer 2 located at x1 and y1, and polymer 3 located at x2 and y2.

After the extruded composite polymer stream was cooled and solidified, an oil agent was added, the stream was wound up at a spinning speed of 1,500 m/min, and stretched between rollers heated to 40°C and 130°C to produce a composite fiber of 90 dtex-24 filaments.

A 2/1 twill fabric was obtained using the resulting composite fibers as warp and weft. The resulting fabric was scoured in 80°C warm water containing a surfactant, and more than 99% of the easily soluble polymer, Polymer 1, was removed using a jet dyeing machine in warm water containing an aqueous sodium hydroxide solution. The fabric was then subjected to a wet heat treatment at 110°C using a jet dyeing machine, and heat set at 180°C.

Next, for the dyeing process, the fabric was immersed in an aqueous solution containing an acid dye (black) and dyeing assistants, and dyed at 100°C for 60 minutes, after which it was rinsed with water. Next, the fabric was immersed in an aqueous solution containing a fixing agent, and fixed at 80°C for 20 minutes, after which it was rinsed with water and air-dried.

Then, as a water-repellent treatment, the fabric was immersed in an aqueous solution containing 4% by weight of "Neoseed" (registered trademark) NR-158 (a non-fluorinated water-repellent agent manufactured by Nicca Chemical Co., Ltd.), a cross-linking agent, and a penetrating agent, and the fabric was squeezed out at a wringing rate of 60% using a mangle, after which it was dried at 130°C using a pin tenter and cured at 170°C.

The obtained woven fabric was composed of a multifilament in which eight-lobed filament A consisting of X1 in Fig. 5(a) and flat filament B consisting of Y1 and Y2 in Fig. 5(b) with a side-by-side composite structure (flatness of 3.0) were uniformly mixed. In addition, the fiber diameter of filament A was 16 μm, and the fiber diameter of filament B was 4 μm, and filament B had a smaller fiber diameter than filament A, confirming that it was a multifilament of the present invention.

The fabric made of this multifilament is made of low-elasticity nylon, so it has excellent flexibility, and because nylon is less likely to wear away when worn, it also has excellent shine resistance and abrasion resistance. The results are shown in the table.

[Comparative Example 4]
As polymer 1, polyethylene terephthalate copolymerized with 8 mol % of 5-sodium sulfoisophthalic acid and 9 mass % of polyethylene glycol (SSIA-PEG copolymerized PET, melt viscosity: 100 Pa s, melting point: 233° C.) was prepared, and as polymer 2, polyethylene terephthalate (PET, melt viscosity: 30 Pa s, melting point: 254° C.) was prepared.

After melting these polymers separately at 290°C, the polymer 1/polymer 2 was weighed out to a mass ratio of 20/80 and poured into a spinning pack equipped with a known composite spinneret. The polymers were discharged from the discharge hole to produce a composite fiber as shown in Figure 3(a), with polymer 1 positioned at z and polymer 2 positioned at x1 and y1.

In the cross section of the obtained composite fiber, eight flattened segments B (flatness 3.0) consisting of y1 in FIG. 3(a) were arranged around the outer periphery of the eight-lobed segment A consisting of x1 in FIG. 3(a). The cross-sectional area S _A per segment A was 167 μm ² , and the cross-sectional area S _B per segment B was 13 μm ^2. The obtained composite fiber was used as the warp and weft to obtain a 2/1 twill fabric. The obtained fabric was subjected to refining, alkali treatment, wet heat treatment, heat setting, dyeing, and water repellent treatment in this order under the same conditions as in Example 1, to obtain a fabric composed of a multifilament in which eight-lobed filaments A consisting of X1 in FIG. 10(a) and flattened filaments B consisting of Y1 in FIG. 10(b) were uniformly mixed. The fiber diameter of the filaments A was 15 μm, and the fiber diameter of the filaments B was 4 μm.

In Comparative Example 4, the ultrafine fiber filament B did not have any crimps, so not only was there no unevenness on the woven surface, and it lacked a smooth feel, but the frictional surface became fixed when the fibers were rubbed and worn, so both filament A and filament B were worn away, and the area of the resulting flat area became larger, resulting in poor shine resistance. The results are shown in the table.

The composite fibers, multifilaments, and woven/knitted fabrics of the present invention have a special fiber morphology in which the cross-sectional arrangement within the composite fibers and the fiber arrangement within the multifilaments are precisely controlled, resulting in textiles that have a smooth feel and a soft, bouncy texture while suppressing the deterioration of surface quality that occurs due to friction and abrasion with other materials, and that exhibit high water-repellent performance when treated with a water-repellent finish.

　Therefore, it can be used for a wide range of textile products, from general clothing such as jackets, skirts, pants, and underwear, to sports clothing and clothing materials, and by taking advantage of its properties, it can be used for a wide range of textile products, including interior products such as carpets and sofas, vehicle interior products such as car seats, cosmetics, masks, health products, and other daily uses. However, from the viewpoints that it can suppress the shine phenomenon caused by friction with other materials when worn, it is flexible yet has a smooth feel, and it can exhibit high water repellency when water repellent processing is applied, it is particularly preferable to use it for clothing applications.

x1, x2: polymers forming segment A; y1, y2: polymer z forming segment B; polymers forming the sea component; a1, a2: two most distant points; b1, b2: intersection points R1, R2 of a straight line passing through the midpoint of a line connecting the two most distant points (a1 and a2) and intersecting at right angles with the outer periphery of the fiber; circumscribing circles J1, J2: common circumscribing lines X1, X2: polymers Y1, Y2 forming filament A; polymer 1 forming filament B; metering plate 2: distribution plate 3: discharge plate

Claims

A composite fiber in which two types of segments A and B exist in the cross section of the fiber, where segment B has a smaller cross-sectional area than segment A, and is formed from two types of polymers that are combined in a side-by-side or eccentric core-sheath configuration.
The composite fiber according to claim 1, in which three or more segments B are arranged around the outer periphery of segment A in the cross section of the fiber.
The composite fiber according to claim 1 or 2, wherein in the fiber cross section, the cross-sectional area S B of each segment B is 1 μm 2 ≦S B <65 μm 2 .
The composite fiber according to claim 1 or 2, which is a sea-island composite fiber having segments A and B as island components, and in which the sea component is formed of a polymer that has the fastest dissolution rate in a solvent among the polymers that make up the sea-island composite fiber.
A multifilament obtained by dividing segments A and B from the composite fiber described in claim 1 or 2.
A textile product at least partially containing the multifilament according to claim 5.
A multifilament consisting of two types of filaments A and B, in which one or more filaments B are present between any two filaments A in the multifilament, and filament B has a smaller fiber diameter than filament A, and is formed from two types of polymers combined in a side-by-side or eccentric core-sheath configuration.
The multifilament according to claim 7, wherein the fiber diameter D B of the filament B is 1 μm≦D B <9 μm.
A woven or knitted fabric at least partially containing the multifilament according to claim 7 or 8.
The woven or knitted fabric according to claim 9, which has been treated with a water-repellent finish.
A water-repellent woven or knitted fabric that includes a multifilament consisting of two types of filaments A and B, in which one or more filaments B are present between any two filaments A in the multifilament, and filament B has a smaller fiber diameter than filament A and is formed from two types of polymers that are combined in a side-by-side or eccentric core-sheath type, and has a water drop sliding angle of 1 to 20 degrees.
The woven or knitted fabric according to claim 11, in which the difference in water droplet sliding angle before and after 20 cycles of washing according to JIS L1930-2014-C4M method and drying according to A method (line drying) is 0 to 20 degrees.
The woven or knitted fabric according to claim 11 or 12, having a fluorine content of 25 ng/g or less as measured by combustion ion chromatography.