Stretch-Processed Yarn, Fiber Product, Composite Spinneret, and Composite Fiber Production Method

This application is divisional application of U.S. Ser. No. 17/291,346, filed May 5, 2021, which is a US national stage filing under 35 U.S.C. § 371 of International Application No. PCT/JP2019/043169, filed Nov. 1, 2019, which claims priority to Japanese Patent Application Nos. 2018-209024 and 2018-209025, both filed Nov. 6, 2018, each of which is incorporated herein by reference in its entirety.

This disclosure relates to a stretch yarn formed of a multifilament having coiled crimps, and a composite spinneret for manufacturing the stretch yarn.

Since fibers using a thermoplastic polymer such as polyester or polyamide have various excellent properties such as mechanical properties and dimensional stability, the fibers are used in a wide range of applications, from clothing applications to interiors, vehicle interiors, and industrial materials. As a more comfortable life is desired, the demand for fiber materials also requires more advanced properties, and materials for clothing that are located at the most familiar range have been actively advanced to obtain the comfort.

The comfort of the materials for clothing has various properties depending on the environment and atmosphere in which the materials are used. However, it is no exaggeration to say that so-called “stretch performance,” which means the property associated with extension and shrinkage of the fabric, is one of the basic properties directly linked to the wearing comfort.

Stretch materials are often used in high-functionality sports clothing for athletes who perform harsh exercise in unique environments. In recent years, the stretch materials are also recognized by general users in terms of ease of wearing and ease of motion, and tend to be adopted in a wide range of apparel materials. Along with such trends, it is not enough to simply achieve stretchability such as simply extension and shrinkage, high-performance stretch materials in which other functions are added and the behavior of extension and shrinkage is controlled to express stretchability more complicatedly and highly has been actively developed.

It is common that when a person wears clothing and motions, the person feels stress due to the rubbing between the clothing and the skin and the tension when the person makes a large motion, and being free from the stress leads to wearing comfort. That is, it leads to a stress-free comfortable clothing material to enhance the motion followability, which means following the motion of a person. To achieve a stress-free stretch material, it is important that the clothing fits the shape of the body and is properly tightened when worn, that is, it extends well while having an appropriate hold sense. To solve these problems, there is a technique related to a latent crimp-expressing fiber in which different polymers are bonded to each other in a side-by-side manner and a spiral structure is expressed by the shrinkage difference.

JP-B-S44-2504 discloses a composite fiber having a side-by-side cross section in which two kinds of polyethylene terephthalate (PET) having different intrinsic viscosities or ultimate viscosities are bonded to each other on the left and right, and JP-A-2005-113369 discloses a technique related to a side-by-side composite fiber made of polytrimethylene terephthalate (PTT) and PET. As described above, it is known that the side-by-side composite fiber in which the two kinds of polymers are bonded to each other develops crimps depending on the difference in shrinkage rate between the polymers when subjected to heat treatment or the like, and such a fiber is typically referred to as a latent crimping fiber. The crimp of the three-dimensional spiral structure can extend and shrink, and the latent crimping fiber becomes a fiber having the stretchability as a good point.

In addition, the latent crimping fiber as described above can express a resistance force during elongation, which is not indispensable to a fabric having an appropriate hold feeling, by utilizing the elongation property due to the polymer structure or controlling the form of crimping, in addition to the elasticity resulting from the elongation of the crimping structure.

JP-A-2000-256918 discloses a technique related to a side-by-side composite fiber made of PTT having different intrinsic viscosities or copolymerization rates. The composite fiber disclosed in JP '918 causes the fiber itself to elongate in a high strain region during elongation deformation by expressing crimp, and becomes a fabric having stretch performance with high resilience and a power feeling depending on the elastic polymer properties of PTT.

In addition to the stretchability due to latent crimping expressed by the shrinkage difference as described above, to further improve the stretchability of the clothing material, it is possible to perform yarn processing, which is disclosed in WO 2002/086211 and JP-A-2017-172080.

WO '211 proposes a PTT false twisted fiber obtained by subjecting side-by-side composite fibers made of PTT to false twisting process. In the technique of WO '211, since crimping by the false twisting is applied in addition to the latent crimping by the false twisting process, the crimp extension and shrinkage force of one fiber can be effectively used, and the fabric having excellent stretchability and instantaneous elongation recoverability is obtained.

JP '080 proposes a composite crimping yarn having a convergence portion and a non-convergence portion in the length direction of the processed yarn by mixing at least two kinds of latent crimping fibers by post-processing. In the processed yarn disclosed in JP '080, the non-convergence portion has stretchability, the convergence portion has a resilience feeling, and the fabric has stretchability with a resilience feeling.

In addition, the latent crimp-expressing fiber expresses more advanced crimping as the shrinkage difference in the yarn manufacturing process of the polymer A on the high shrink-age side and the polymer B on the low shrinkage side is larger, and exhibit excellent stretchability even when the fiber is made into a fabric. To achieve this, for example, it is considered to increase the difference in the melt viscosity between the polymer A and the polymer B to be combined, but it is known that as the difference in melt viscosity between polymers is increased, the discharge stability is lowered, and stable manufacture may become difficult.

is a typical composite spinneret used for spinning a latent crimp-expressing fiber having a composite cross section as shown in. When two kinds of thermoplastic polymers having different melt viscosities are spun using such a composite spinneret, a polymer on a high viscosity side (high-viscosity polymer A) is pressed by a polymer on a low viscosity side (low-viscosity polymer B), a discharge bending phenomenon in which the composite polymer is discharged in a bent state occurs, and yarn jitter or yarn breakage due to contact with the spinneret surface occurs. Therefore, to perform stable discharge, the discharge conditions may be limited.

It is considered that this discharge bending phenomenon is caused by the flow behavior of the composite polymer flow in the composite spinneret. When two kinds of polymers having different melt viscosities are spun using the composite spinneret as shown in, as shown in, the polymer flow of the high-viscosity polymer A guided through an induction holeand the polymer flow of the low-viscosity polymer B guided by an induction holeare joined by an introduction hole. Since the melt viscosities of the two kinds of polymers are different from each other, it is estimated the resistance received from the wall surface of the introduction holeis different for each polymer flow, such that the velocity distribution in the radial direction in the introduction holebecomes an asymmetrical velocity distribution Vas shown inas the velocity distribution advances in the introduction hole, and the discharge bending phenomenon occurs in the polymer flow G discharged from a spinneret discharge hole.

When the composite polymer having the asymmetric velocity distribution is discharged, a difference in discharge linear velocity is caused between the polymers immediately after the discharge, and a state of being bent toward the high viscosity polymer side is obtained.

To solve such a problem of spinnability, for example, JP-A-H2-307905 proposes a composite spinneret that inhibits the discharge bending phenomenon by controlling the flow velocity when merging polymer flows.

The composite spinneret described in JP 'will be described with reference to. In the composite spinneret disclosed in JP ', the polymer flow (high-viscosity polymer flow) of the high-viscosity polymer A guided by the induction holeand the polymer flow (low-viscosity polymer flow) of the low-viscosity polymer B guided by the induction holeare joined by the introduction hole. At this time, as shown in, in the low-viscosity polymer flow, there is a flow pathin which the groove width W is continuously widened along the flow direction of the low-viscosity polymer B between the induction holeand the introduction hole. Therefore, when the low-viscosity polymer flow is joined to the high-viscosity polymer flow, the flow velocity of the low-viscosity polymer flow is sufficiently low, and as shown in, the velocity distribution in the cross-sectional direction of the composite polymer flow can be made close to symmetry at the lower portion of the introduction hole(reference numeral “V” in), and the discharge bending phenomenon of the polymer flow G discharged from the spinneret discharge holecan be inhibited.

In addition, a proposal related to a composite spinneret that inhibits discharge bending phenomenon by controlling a composite cross section is also disclosed in JP-B-S55-27175.

The composite spinneret disclosed in JP '175 will be described with reference to. In the composite spinneret disclosed in JP '175, the polymer flow (high-viscosity polymer flow) of the high-viscosity polymer A guided by the induction holeand the polymer flow (low-viscosity polymer flow) of the low-viscosity polymer B guided by the induction holeare joined at the introduction hole, the joined polymer flow is allowed to flow down to an introduction hole, and the low-viscosity polymer flow entering another induction holeis introduced into the introduction holevia the flow path. By allowing the low-viscosity polymer flow guided from the another induction holeto flow down to the spinneret discharge holewhile covering the periphery of the joined polymer flow, it is possible to obtain an eccentric core-sheath cross-section as shown inin which the first component polymer A is surrounded by the second component polymer B. As a result, the resistance received from the wall surface of the introduction holeof each polymer flow becomes constant. Although the velocity distribution in the cross-sectional direction of the composite polymer flow when the first component polymer A is the high-viscosity polymer and the second component polymer B is the low-viscosity polymer has three peaks as shown in(reference numeral “V” in), the radial velocity distribution in the introduction holecan be made close to symmetry. Therefore, the bending of the polymer flow G discharged from the spinneret discharge holetoward the high-viscosity polymer side is reduced, and the discharge bending phenomenon can be inhibited. Typically, when the entire periphery of the side-by-side cross section is coated, it is known that, by shortening the distance between the centers of gravity of the polymers on the composite cross-section, the bending toward the high shrinkage component side during the heat treatment is inhibited, and the crimp-expressing property is lowered. It has been proposed that, in the composite spinneret of JP '175, the low-viscosity polymer flow guided to the induction holeis controlled by adjusting the pressure applied to the induction holeand the induction holeso that the coating portion is made thin and the crimp-expressing property equivalent to that of the side-by-side cross section can be maintained.

In the crimping of substantially the same size that is expressed by the simple side-by-side composite fibers proposed in JP '504 and JP '369, when a load is applied to the fibers or the fabric, entanglement does not occur in the fibers, and eventually, since each fiber bears the stress alone, the fibers extend well with a relatively weak force, an appropriate holding feeling that is the desired effect cannot be obtained, and it is difficult to obtain an excellent motion followability.

Further, in JP '918, the behavior in which the crimping structure is similar to JP '504 and JP '369, and it is difficult to obtain an appropriate holding feeling. Furthermore, with regard to a resistance force which results from the elastic characteristics of the polymer and is applied when the crimped structure is completely extended, depending on the structure of the fabric and the portion used, the resistance may work excessively, and it may be felt as a taut feeling.

In WO '211, by applying the actualized crimping by the false twisting process, crimping of different sizes is mixed in the multifilament so that a wide distribution of the coil pitch and the coil diameter is exhibited among the fibers. In such a state, a fiber having a large coil diameter is slackened and fixed on the multifilament. Since the slack fibers do not contribute to the extension and shrinkage of the multifilament and the resistance force therewith, the resistance force during extension and shrinkage may decrease. Further, since the yarn is a false twisted yarn of the side-by-side composite fiber, in the false twisting process in which the multifilament is twisted while being heated, if the multifilament is processed under an unreasonable condition, peeling between the polymers may occur due to friction or impact during processing or use, and there may be problems such as whitening when a fabric is formed. For this reason, use of the yarn for sports clothing and outdoor clothing for which high wear resistance is required for use in a harsh environment may be limited.

In JP '080, since the convergence portion responsible for the resistance force during yarn extension forms one large spiral structure regardless of the crimping form of the fiber, the spiral structure could not be formed well under the constraint of the fabric structure, and the resilience feeling during elongation was lacking when used as the fabric. Further, focusing on the non-convergence portion, since the difference in the crimping form between the constituent fibers is large, the same kind of fiber is unevenly distributed in the multifilament cross section, and the crimp phases of the plurality of fibers may be aligned by causing the crimping of the same size to bite each other. Therefore, the fibers on the low crimp side float on the surface of the multifilament, and the fabric surface may have an unnecessarily rough feel.

Further, a common feature of the composite spinneret used when spinning the conventional latent crimp-expressing fiber is that there is a flow path between the induction hole and the introduction hole.

The flow path is a groove flow path arranged in a direction perpendicular to the induction hole or the introduction hole, and at least one of the polymer flows is joined to the other polymer in front of the introduction hole via the flow path. At this time, since the polymer flows collide with each other in the vertical direction, there are problems such as a composite cross-sectional change due to a minute change in the flow velocity of the polymer flow and an occurrence of abnormal retention during long-term spinning. In some instances, there is a problem in yarn manufacturing stability such as a sudden decrease in crimpability and yarn breakage due to discharge bending.

In addition, although it is possible to improve the dimensional stability of the composite cross section and inhibit abnormal retention by not providing a flow path between the induction hole and the introduction hole, in this example the flow velocity cannot be controlled through the flow path, and the asymmetry of the velocity distribution at the introduction hole is expanded, the discharge bending phenomenon may be exacerbated.

Further, in the composite spinneret described in JP '175, since the thin skin composite cross section can be formed, the discharge bending can be inhibited even with a sharp change in the viscosity, but since the flow path is provided between the induction hole and the introduction hole, the dimensional stability of the composite cross section is not guaranteed. In addition, to form a coating film, it is necessary to form a pool of a low-viscosity polymer flow guided from another induction holein the flow pathand allow the joined polymer flow of the introduction holeto flow down thereto. However, to make the coating thin, the amount of low-viscosity polymer flow derived from another induction holemust be extremely small, abnormal retention is likely to occur inevitably in the polymer pool in the flow pathby using a very small amount of polymer flow, and there was a problem with yarn manufacturing stability.

Further, in the technique of JP '175, since the spinneret flow path joins the polymer flows twice, it is necessary to increase the processing area in the spinneret, and accordingly, the number of fibers (the number of filaments) obtained from one composite spinneret is limited. For this reason, the productivity is significantly reduced, and the development to a wide variety of products may be restricted.

As described above, the composite spinneret that can stably discharge in a wide range of conditions is an extremely important element in manufacturing latent crimp-expressing fibers. However, the composite spinneret has the above-mentioned problems, and there has been a demand for a composite spinneret of latent crimp-expressing fibers that solves these problems.

It could therefore be helpful to provide a stretch yarn capable of providing good stretchability to clothing, a fiber product including the stretch yarn, a composite spinneret for manufacturing the stretch yarn, and a method of manufacturing composite fibers, specifically, to provide a stretch yarn which can be used as a fiber material that has good stretchability, motion followability due to appropriate resistance during extension, and a flexible surface feel according to the crimping form by precisely controlling and improving the crimp forms of the fibers that form the crimp yarn, and a composite spinneret capable of forming a composite cross section capable of significantly inhibiting the discharge bending phenomenon while maintaining the same crimp-expressing property as in the conventional side-by-side cross section (see) in the composite spinneret for manufacturing the stretch yarn and capable of stably discharging within a wide range of conditions since the dimensional stability of the composite cross section can be maintained at a high level regardless of the discharge range.

We thus provide (1) to (8):

(1) A stretch yarn including a multifilament including fibers having a coiled crimping form in a fiber axial direction, in which a coil diameter distribution of crimping in the fiber has two or more groups, a ratio of a maximum group average value to a minimum group average value of the coil diameter (a maximum group average value/a minimum group average value) is less than 3.00, and a cross section of the fibers constituting the multifilament is an eccentric core-sheath cross section.(2) The stretch yarn according to (1), in which the number of fibers included in the group having the minimum group average value of the coil diameter is 20% or more of the total number of fibers constituting the multifilament.(3) The stretch yarn according to (1) or (2), in which an average diameter of the fibers constituting the multifilament is 15 μm or less.(4) The stretch yarn according to any one of (1) to (3), in which the extension energy is 1.5 μJ/dtex or more.(5) A fiber product including the stretch yarn according to any one of (1) to (4) in at least a part of the fiber product.(6) A composite spinneret for discharging a composite polymer flow constituted by a first component polymer and a second component polymer, in which the composite spinneret includes a measurement plate having a plurality of measurement holes for measuring each polymer component, one or more distribution plates having distribution holes for distributing each polymer component, and a discharge plate, in which in a lowermost layer on a downstream side of the distribution plate in a polymer spinning path direction, a polymer distribution hole group in which a plurality of first component polymer distribution holes of semicircular arrangement are surrounded by a plurality of second component polymer distribution holes is bored, in which at least a part of the second component polymer distribution holes in the polymer distribution hole group is arranged in semicircular arc arrangement on an outer side of a circumferential portion of the plurality of first component polymer distribution holes of semicircular arrangement.(7) The composite spinneret according to (6), in which the total number of holes Ht of the second component polymer distribution holes in the polymer distribution hole group and the number of holes Ho of the second component polymer distribution holes arranged in semicircular arc arrangement on the outer side of the circumferential portion of the plurality of first component polymer distribution holes of semicircular arrangement satisfy relationship (1):

(8) A method of manufacturing a composite fiber using the composite spinneret according to (6) or (7).

Our stretch yarn includes a mixture of a plurality of coiled crimping groups in which the coil diameter is controlled in a multifilament, and exhibits an appropriate elongation resistance from the initial stage of elongation according to the size of the coil diameter, and when the stretch yarn is made into a woven or knitted fabric, the stretch yarn elongates and deforms well while having an appropriate holdability. Therefore, it is possible to provide a stretch material that exhibits stress-free motion followability, and application to a wide range of fiber products can be expected from sports and apparel clothing applications to industrial material applications such as hygienic materials.

In addition, in the composite spinneret used in manufacturing our stretch yarn, it is possible to form a composite cross section capable of significantly inhibiting the discharge bending phenomenon while maintaining the same crimp-expressing property as that of the conventional latent crimp-expressing fiber, and it is possible to maintain the dimensional stability of the composite cross section at a high level regardless of the viscosity and the discharge range of the polymer combined. Therefore, it is possible to manufacture composite fibers having excellent stretchability in a wide range of conditions.

Hereinafter, our stretch yarns, fiber products and methods will be described in detail together with preferred examples.

Our stretch yarn refers to a textured yarn having a property of extending or shrinking when elongation deformation is applied, and the stretch yarn is formed of a multifilament including fibers having a coiled crimping form in the fiber axial direction, and the first requirement is that the crimp coil diameter distribution in the fiber has two or more groups.

The coil diameter of the coiled crimping mentioned here means one of the indexes indicating the crimp size of the fibers constituting the stretch yarn, and when the fibers separated from the multifilament are observed two-dimensionally from the side surface (direction perpendicular to the fiber axis direction), mountains and valleys are alternately observed in the fiber width direction as illustrated in, and the coil diameter can be measured from the observation image. The coil diameter of the crimping will be described in more detail by using an example () in which the images of the fibers constituting our stretch yarn are captured by the above method.

First, a 10-meter skein of a multifilament sample to be evaluated is prepared by using a sizing reel or the like, immersed in boiling water of 98° C. or more with a load of 0.2 mg/d, and is subjected to an boiling water treatment for 15 minutes. After the multifilament sample having been treated with boiling water is sufficiently dried by air drying, the multifilament sample is applied with a load of 1 mg/d for 30 seconds or more, and then is marked on any part of the multifilament such that the distance between the two points becomes 3 cm. Thereafter, the fiber is separated from the multifilament to not be plastically deformed, and is fixed on the slide glass by adjusting the distance between the markings set in advance to be 3 cm as the original, and an image of the sample is captured at a magnification at which five to ten peaks of crimping can be observed with a digital microscope or the like. In each captured image (), when peaks of any adjacent mountains are M, M, and a vertex of a valley between the peaks M, Mof the mountain is V, the shortest distance between a line connecting the peak Mof the mountain and the peak Mof the mountain and the vertex Vof the valley is the coil diameter (Dc) of the crimping. The coil diameter Dc of the crimping is measured up to the first decimal place with a unit of μm.

The same operation is randomly performed on different fibers constituting the multifilament, and this operation is repeated to measure the coil diameter such that the total number of data becomes 100. When the measured values of the coil diameter are divided into classes with a boundary value of 10×n (n: natural number) μm and a width of 10 μm and the vertical axis is a frequency histogram, having two or more groups (mountains) as illustrated inmeans that “the coil diameter distribution of crimping has two or more groups.” The term “group” refers to when either of the following (1) and (2) is satisfied, andillustrates a coil diameter measurement result of the stretch yarn having two groups (black colored portions) shown by-() and-().

(1) When there are two or more consecutive classes with a frequency of 5% or more, one group including all the classes is set as one group (illustrated as an example in-() of).

(2) When the frequency of the class exceeds 10% and the frequency of any of the classes before and after the continuous class is less than 5%, the class of 10% or more is set as one group (illustrated as an example in-() of).

The textured yarn having a coil diameter distribution as illustrated inmeans that a multifilament is constituted by two or more kinds of fiber groups having a clear difference in crimp size (average coil diameter). In a textured yarn with crimping, when the crimping coil extends and shrinks, the resistance force (stress) during elongation deformation is expressed, and in a multifilament including only one kind of coil diameter, since the fibers constituting the multifilament are uniformly deformed, the profile is monotonous as shown by a dotted line-() inin which stress (resistance force) does not appear until almost the crimping is fully extended. On the other hand, when two or more kinds of fibers having different coil diameters are present in the multifilament, fibers having different sizes are deformed in an inclined manner according to the elongation of the textured yarn. That is, the profile is a specific deformation profile in which stress is expressed from the range of low elongation as shown by the solid line-() insuch that the fiber having a small coil diameter is deformed in the low elongation region and the fiber having a large coil diameter is deformed in the high elongation region.

This is an important characteristic showing the characteristics of our stretch yarn, and since stress is applied in an inclined manner from the range of the low elongation and an appropriate resistance force is expressed according to the elongation deformation, a good hold feeling is generated when worn as clothes. In an actual textured yarn, a multifilament is formed in a state in which a fiber having a large coil diameter is partially entangled with a fiber having a small coil diameter. Therefore, the multifilament itself is integrally formed without being separated and is easy to handle, and the fiber having a large coil diameter is partially deformed to follow the elongation deformation of the fiber having a small coil diameter so that the entire multifilament has a good elongation deformation.

This effect can be evaluated by the elongation energy as seen in the tensile properties.

First, the stretch yarn not subjected to the heat treatment is left to stand under no load for 24 hours at a temperature of 20±2° C. and a relative humidity of 65±2%. After the lapse of 30 seconds or more by applying a load of 1 mg/d to the yarn sample after standing for 24 hours, the yarn sample is fixed to a tensile tester (“TENSILON” UCT-100, manufactured by Orientec Co., Ltd., for example) with the initial sample length set to 50 mm with the load applied. The tensile test of the yarn sample is performed at a tensile velocity of 50 mm/min, and an elongation-stress curve is created as illustrated inwith the horizontal axis as elongation (unit: mm) and the vertical axis as stress (unit: cN/dtex). In the obtained elongation-stress curve, when a point at which the strength is 0.05 cN/dtex is set as-() and an intersection of a perpendicular line drawn from the point-() toward the horizontal axis (stress is 0 cN/tex) and the horizontal axis is set as-(), the area Ae surrounded by the points-(),-() and the origin represents the elongation energy, and can be calculated with a unit of μJ/dtex. The simple number average of the results obtained by performing the same operation on ten different yarn samples is obtained, and the value rounded off to the first decimal place is the elongation energy.

The elongation energy refers to the amount of energy required for elongation deformation of the material. When the elongation-stress curve of the yarn has a monotonous profile as shown by the dotted line-() in, the elongation energy is a low elongation energy which means that the material is deformed without any resistance during the low elongation deformation that the human exerts in a normal operation, and there is a difference between the deformation of the fabric and the motion of the human. On the other hand, in a multifilament having high elongation energy as shown by the solid line-() in, a resistance force is expressed from the range of the low elongation deformation, and the multifilament is deformed while fitting the motion of the human, and the good hold feeling and the good motion followability can appeal.