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(11) | EP 4 379 099 A1 |
| (12) | EUROPEAN PATENT APPLICATION |
| published in accordance with Art. 153(4) EPC |
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| (54) | COMPOSITE FIBER BUNDLE AND FIBER PRODUCT |
| (57) The present invention pertains to a conjugate fiber bundle characterized by being
constituted by conjugate fibers comprising at least two types of polymers having different
melting points, and by being such that the variation coefficient CV for the value
of the ((distance between polymer centers of gravity)/(fiber diameter)) among the
conjugate fibers is 5-30%. |
TECHNICAL FIELD
[0001] The present invention relates to a conjugate fiber bundle suitable for a textile for clothing and a fiber product including the conjugate fiber bundle.
BACKGROUND ART
[0002] Synthetic fibers including polyester, polyamide, or the like have excellent mechanical characteristics and dimensional stability, and thus are widely utilized from clothing applications to non-clothing applications. However, in recent years, as the life of people has been diversified and better life has been demanded, there is a growing demand for fibers having more advanced tactile sensation and functions.
[0003] As such fibers having more advanced tactile sensation and functions, there has been proposed a method of using conjugate fibers having a side-by-side type cross section in which different polymers are attached.
[0004] The side-by-side type conjugate fiber is intended to impart a texture such as appropriate feeling of resilience and swelling by developing crimps by a difference in thermal contraction between polymers, but when a textile is formed using a conjugate fiber bundle in which a plurality of the conjugate fibers are bundled, since all the conjugate fibers develop the same crimp form, crimp phases may be aligned, and a flat texture lacking swelling feeling may be obtained.
[0005] On the other hand, a textile for clothing that comes into contact with human skin is often required to have excellent wearing comfortableness, and particularly has a strong demand for fibers having a texture directly related to wearing comfort of human, such as those including natural fibers. This is because a texture and functions of natural materials such as wool, cotton, and silk are extremely excellent in balance, and human feels attraction and a sense of high quality to a complex appearance and tactile sensation woven by texture and functions.
[0006] In order to solve the problem of obtaining a flat texture lacking swelling feeling due to alignment of crimp phases among the conjugate fibers in a synthetic fiber, there have been proposed various techniques of devising each individual conjugate fiber constituting the conjugate fiber bundle to make the obtained tactile sensation and texture complex and close to a specific tactile sensation and texture found in a natural material.
[0007] Patent Literature 1 discloses that, in a conjugate fiber bundle formed of conjugate fibers in which polyethylene terephthalates (PET) having different viscosities are conjugated into a side-by-side type product, a conjugate ratio is changed between the conjugate fibers to develop a variation in curvature of a polymer interface, thereby independently forming crimps without intermeshing of the crimps due to a difference in crimp form between the conjugate fibers corresponding to the conjugate ratio.
[0008] The conjugate fiber bundle formed of such conjugate fibers develops voids between the conjugate fibers corresponding to the difference in crimp form, and therefore, when the conjugate fiber bundle is formed into a textile, the textile is considered to have a texture of swelling feeling.
[0009] Patent Literature 2 discloses that a conjugate fiber in which polyethylene terephthalates (PET) having different viscosities are conjugated into a side-by-side type product is formed to have a modified cross section, and further, a conjugate fiber bundle is formed of three or more types of conjugate fiber groups having different states of a conjugate bonding surface which is a bonding surface of conjugate components, whereby each conjugate fiber group has a different flexural rigidity and conjugate fiber groups having different crimp development properties can be obtained.
[0010] By utilizing such a conjugate fiber bundle, a textile having both stretchability and feeling of resilience as well as a natural fiber-like swelling and bulkiness can be obtained.
CITATION LIST
PATENT LITERATURE
SUMMARY OF INVENTION
TECHNICAL PROBLEM
[0012] As disclosed in Patent Literature 1, when the conjugate ratio is changed between the conjugate fibers constituting the conjugate fiber bundle to develop the variation in curvature of the polymer interface, the difference in crimp form among the conjugate fibers may be developed.
[0013] However, in Patent Literature 1, the change in conjugate ratio that can be used as a way to change the crimp form of each conjugate fiber is substantially in a range of 40:60 to 60:40 in order to maintain stability of yarn production, the difference in crimp form change obtained here is small, and naturally, the obtained texture may also be monotonous.
[0014] In addition, as disclosed in Patent Literature 2, the conjugate fiber bundle includes three or more types of conjugate fiber groups having different states of the conjugate bonding surface, whereby each conjugate fiber group has a different flexural rigidity and conjugate fiber groups having different crimp development properties can be obtained.
[0015] However, since the conjugate fiber disclosed in Patent Literature 2 has a substantially multilobal cross section, and a distance between polymer gravity centers required for crimp development is naturally shortened, a crimp development ability is reduced, and the swelling and feeling of resilience required for comfortable clothing may be lacking.
[0016] In view of the above, an object of the present invention is to solve the above-mentioned problems of the related art and to provide a conjugate fiber bundle suitable for obtaining a textile for clothing having excellent wearing comfortableness including a texture having appropriate feeling of resilience and swelling in addition to a smooth tactile sensation by controlling the crimp form of each individual conjugate fiber constituting the conjugate fiber bundle.
SOLUTION TO PROBLEM
[0017] The object of the present invention is achieved by the following method. That is,
- (1) a conjugate fiber bundle formed of conjugate fibers, each of which includes at least two types of polymers having different melting points, in which a coefficient of variation CV of a value of (distance between polymer gravity centers/fiber diameter) between the conjugate fibers is 5% to 30%,
- (2) the conjugate fiber bundle according to (1), in which a difference between a maximum value of flatness and a minimum value of flatness between the conjugate fibers is less than 0.5,
- (3) the conjugate fiber bundle according to (1) or (2), in which an average value of flatness between the conjugate fibers is 1.2 to 3.0,
- (4) the conjugate fiber bundle according to any one of (1) to (3), in which a surface layer of the conjugate fibers is covered with one type of polymer, and
- (5) a fiber product partially including the conjugate fiber bundle according to any one of (1) to (4).
ADVANTAGEOUS EFFECTS OF INVENTION
[0018] Since the conjugate fiber bundle of the present invention has the above-mentioned characteristics, the crimp form of each individual conjugate fiber constituting the conjugate fiber bundle is precisely controlled. Therefore, by using the conjugate fiber bundle of the present invention, it is possible to obtain a textile for clothing having excellent wearing comfortableness including a texture having appropriate feeling of resilience and swelling in addition to a smooth tactile sensation.
BRIEF DESCRIPTION OF DRAWINGS
[0019]
[FIG. 1] (a), (b), and (c) of FIG. 1 are schematic views illustrating examples of a cross-sectional structure of conjugate fiber constituting a conjugate fiber bundle of the present embodiment.
[FIG. 2] (a) and (b) of FIG. 2 are schematic views illustrating examples of a cross-sectional structure of the conjugate fiber constituting the conjugate fiber bundle of the present embodiment.
[FIG. 3] FIG. 3 is a schematic view illustrating an example of a cross-sectional structure of conjugate fibers constituting a conjugate fiber bundle in the related art.
[FIG. 4] FIG. 4 is a schematic view illustrating examples of a cross-sectional structure of each of the conjugate fibers constituting the conjugate fiber bundle of the present embodiment.
[FIG. 5] FIG. 5 is a view for understanding a coefficient of variation CV of a value of (distance between polymer gravity centers/fiber diameter) between the conjugate fibers constituting the conjugate fiber bundle of the present embodiment, and a broken line of an outer frame indicates upper, lower, left, and right sides of a captured image.
[FIG. 6] FIG. 6 is a schematic view illustrating an example of a crimp form of the conjugate fiber constituting the conjugate fiber bundle of the present embodiment.
[FIG. 7] FIG. 7 is a cross-sectional view for illustrating a production method of the conjugate fibers constituting the conjugate fiber bundle of the present embodiment.
DESCRIPTION OF EMBODIMENTS
[0021] Analyzing cotton, which is widely developed as a natural material having a soft texture with a smooth tactile sensation and swelling, it is considered that each individual fiber has a different crimp form and when a plurality of fibers having different crimp forms are bundled, complex voids and irregularities are formed when a textile is formed, and specific tactile sensation and texture are achieved.
[0022] The inventors of the present invention have conducted extensive research to obtain complex voids and irregularities similar to those found in a natural material using a synthetic fiber, and have found that in a conjugate fiber bundle formed of conjugate fibers, each of which includes at least two types of polymers having different melting points, by controlling a distance between polymer gravity centers for each conjugate fiber to appropriately align crimp phases, complex voids and irregularities, which have been difficult to obtain in synthetic fibers in the related art, can be formed.
[0023] That is, in the case where all the conjugate fibers constituting the conjugate fiber bundle develop the same crimp form, the conjugate fiber bundle becomes a converged conjugate fiber bundle in which the crimp phases are aligned, and the voids between the conjugate fibers become small, so that when a textile is formed, the texture may be a flat texture lacking swelling feeling.
[0024] On the other hand, in the case where the conjugate fibers constituting the conjugate fiber bundle each develop a different crimp form, the crimp phases of the conjugate fibers tend to be shifted to form voids between the conjugate fibers. However, since the form of the conjugate fiber bundle does not change and a size of the void formed between the conjugate fibers is also uniform, an appearance and a texture when the conjugate fiber bundle is formed into a textile may be monotonic.
[0025] In contrast, in the case where the conjugate fiber bundle is controlled such that the crimp phases of the conjugate fibers are partially aligned even though the crimp development of the conjugate fibers constituting the conjugate fiber bundle changes, when the conjugate fiber bundle is formed into a textile, in addition to fine voids inherent in the conjugate fiber bundle, there will be a portion where the crimp phases are aligned between adjacent conjugate fibers and a portion where the crimp phases are not aligned between adjacent conjugate fibers. As a result, complex voids are generated between the conjugate fibers, and complex irregularities which have not been generated are generated in the conjugate fiber bundle, and when the conjugate fiber bundle is formed into a textile, a specific tactile sensation and texture similar to those found in a natural material can be developed.
[0026] The present invention is made based on this idea, and specifically is a conjugate fiber bundle formed of conjugate fibers, each of which includes at least two types of polymers having different melting points, and it is important that a coefficient of variation CV of a value of (distance between polymer gravity centers/fiber diameter) between the conjugate fibers is 5% to 30%.
[0027] The conjugate fiber bundle in the present embodiment is a conjugate fiber bundle in which, for example, 20 or more conjugate fibers, each of which includes at least two types of polymers, are bundled together, and refers to a multifilament formed of filaments, a spun yarn formed of staple fibers, and the like.
[0028] The polymer used for the conjugate fibers constituting the conjugate fiber bundle of the present embodiment is preferably a thermoplastic polymer for its excellent processability. Preferred examples of the thermoplastic polymer include polymer groups of polyesters, polyethylenes, polypropylenes, polystyrenes, polyamides, polycarbonates, polymethyl methacrylates, and polyphenylenesulfides, and copolymers thereof. In particular, from the viewpoint of being able to impart high interfacial affinity and obtaining fibers having no abnormality in a cross-sectional morphology, it is preferable that all thermoplastic polymers used in the conjugate fibers are of the same polymer group and copolymers thereof.
[0029] The polymer may contain various additives such as inorganic materials such as titanium oxide, silica, and barium oxide, coloring agents such as carbon black, dyes, and pigments, a flame retardant, a fluorescent whitening agent, an antioxidant, and an ultraviolet absorbent.
[0030] Among those, the titanium oxide is preferably contained in the polymer. When the titanium oxide is contained in the polymer, the titanium oxide on a surface of the conjugate fiber causes irregular reflection of light, so that not only improvement of appearance quality in which appearance unevenness (glare) caused by increase and decrease in reflection due to an incident angle of light can be prevented but also functionality of preventing transparency and shielding ultraviolet by the titanium oxide inside the conjugate fiber can be obtained. A content of the titanium oxide in the polymer is preferably 1.0 wt% or more in order to sufficiently obtain the above-mentioned effect. In addition, the content of the titanium oxide is preferably 10.0 wt% or less because an increase in the irregular reflection of light due to the titanium oxide may cause a decrease in a color development property.
[0031] In order to control the crimp form, each of the conjugate fibers constituting the conjugate fiber bundle of the present embodiment need to include at least two types of polymers having different melting points.
[0032] When the polymers having different melting points are arranged such that gravity centers thereof are different from each other in the cross section of the conjugate fibers, the conjugate fibers are largely curved to a low melting point polymer side at which the conjugate fibers are highly contracted after a heat treatment, and continuous curves can develop a coil-shaped crimp form. Further, any crimp form can be developed by controlling the distance between polymer gravity centers, and accordingly, control of the crimp phase which is the object of the present invention can be achieved.
[0033] The polymers having different melting points in the present embodiment refer to a combination of polymers having melting points different by 10°C or more from among melt-moldable thermoplastic polymer groups of polyesters, polyethylenes, polypropylenes, polystyrenes, polyamides, polycarbonates, polymethyl methacrylates, and polyphenylenesulfides, and copolymers thereof.
[0034] Since the object of the present invention is to develop a crimp form due to a contraction difference of the polymers having different melting points in the conjugate fibers constituting the conjugate fiber bundle of the present embodiment, as the combination of the polymers having different melting points, it is preferable that one type thereof is a low melting point polymer having a high contraction and the other type thereof is a high melting point polymer having a low contraction.
[0035] In particular, from the viewpoint of preventing peeling and imparting stability in textile processing process and durability for use to the textile, the combination of the polymers is more preferably selected from the same polymer group having the same bonds in a main chain, such as polyesters with ester bonds and polyamides with amide bonds.
[0036] Examples of the combination of the low melting point polymer and the high melting point polymer in the same polymer group as described above include various combinations of polyester polymers such as copolymerized polyethylene terephthalate/polyethylene terephthalate, polypropylene terephthalate/polyethylene terephthalate, polybutylene terephthalate/polyethylene terephthalate, thermoplastic polyurethane/polyethylene terephthalate, polyester elastomer/polyethylene terephthalate, polyester elastomer/polybutylene terephthalate, polyamide polymers such as nylon 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, polyolefin polymers such as ethylene-propylene rubber finely dispersed polypropylene/polypropylene, and propylene-α-olefin copolymer/polypropylene.
[0037] Among those, the polymers having different melting points are particularly preferably a combination of copolymerized polyethylene terephthalate/polyethylene terephthalate, from the viewpoint that when the conjugate fiber bundle is prepared into a textile, an appropriate feeling of resilience is obtained due to a high bending recovery property, and when the conjugate fiber bundle is dyed, a good color development property is obtained.
[0038] Examples of the copolymerization component in the copolymerized polyethylene terephthalate include succinic acid, adipic acid, azelaic acid, sebacic acid, 1,4 -cyclohexane dicarboxylic acid, maleic acid, phthalic acid, isophthalic acid, and 5-sodium sulfoisophthalic acid. Among those, polyethylene terephthalate obtained by copolymerizing 5 mol% to 15 mol% of isophthalic acid is preferable from the viewpoint of being able to maximize the contraction difference with polyethylene terephthalate.
[0039] While attention is paid to environmental problems, it is also preferable to use a plant-derived biopolymer or recycled polymer in the present embodiment from the viewpoint of reducing environmental load. Accordingly, as the above-mentioned polymer used in the present embodiment, a recycled polymer recycled by any of methods including chemical recycling, material recycling, and thermal recycling can be used.
[0040] Even in the case where a biopolymer or a recycled polymer is used, a polyethylene terephthalate-based resin can remarkably enhance characteristics of the present invention for its polymer properties. Accordingly, as described above, from the viewpoint of obtaining an appropriate feeling of resilience due to a high bending recovery property and obtaining a good color development property when dyeing is performed, recycled polyethylene terephthalate can be suitably used as the polymer used in the present embodiment.
[0041] The cross section of the conjugate fiber of the present embodiment is preferably a cross-sectional morphology in which polymers having different melting points are arranged such that gravity centers thereof are different. Examples of such a cross-sectional morphology include a side-by-side type as illustrated in (a) of FIG. 1 and an eccentric sheath-core type as illustrated in (b) of FIG. 1, and in addition, include a sea-island type, a blend type, and the like.
[0042] In the present embodiment, a surface layer of the conjugate fibers is preferably covered with one type of polymer. In the case where the surface layer of the conjugate fibers is covered with one type of polymer, even when a polymer having low heat resistance and abrasion resistance is used as one component of the conjugate fiber, fiber characteristics can be favorably maintained without generating peeling at an interface due to friction or impact.
[0043] In addition, in production of the conjugate fiber bundle of the present embodiment, when a melt of polymers having a large difference in melting point is spun out from a spinneret as a composite flow, yarn bending in which the high melting point polymer is curved to the low melting point polymer side is generated due to a difference in cooling after discharge, and the yarn is brought into contact with the spinneret or interferes with the composite flow spun out from another portion, which causes yarn breakage. However, when the surface layer of the conjugate fibers is covered with one type of polymer, the difference in cooling is reduced and the yarn bending can be prevented, and even when a combination of polymers having a large difference in melting point is used, stable yarn production is possible.
[0044] Examples of the one type of polymer covering the surface layer of the conjugate fibers include polyester-based polymers such as polyethylene terephthalate, copolymerized polyethylene terephthalate, polypropylene terephthalate, and polybutylene terephthalate, polyamide-based polymers such as nylon 6, nylon 66, and nylon 610, and polyolefin-based polymers such as polypropylene. Among those, it is preferable to use polyethylene terephthalate or copolymerized polyethylene terephthalate to cover the surface layer of the conjugate fibers from the viewpoint of excellent heat resistance and color development property.
[0045] In addition, a thickness of the one type of polymer covering the surface layer of the conjugate fibers can be appropriately adjusted, and for example, a ratio S/D of a minimum thickness S to a fiber diameter D of the polymer covering the surface layer of each conjugate fiber constituting the conjugate fiber bundle is preferably 0.01 to 0.1. Within such a range, even when friction or impact is applied to the conjugate fiber or the textile, yarn processing stability and textile quality can be maintained without causing a whitening phenomenon or fluffing. Further, when S/D is 0.02 to 0.08, the gravity center of the high melting point polymer and the gravity center of the low melting point polymer are separated from each other, and crimps due to the contraction difference can be developed at a maximum limit, and thus 0.02 to 0.08 is a more preferable range.
[0046] The ratio S/D of the minimum thickness S to the fiber diameter D of the polymer covering the surface layer of the conjugate fibers in the present embodiment is obtained by embedding the conjugate fiber bundle with an embedding agent such as an epoxy resin, then capturing an image of a cross section thereof with a transmission electron microscope (TEM) at a magnification at which 10 or more conjugate fibers can be observed, and observing the cross-sectional morphology. In this case, since a difference in dyeing between the polymers can be generated when metal staining is performed, the contrast of a bonding portion of the cross-sectional morphology can be clarified.
[0047] Further, in the case where the cross-sectional morphology in the captured image is an eccentric sheath-core type cross section as illustrated in (b) of FIG. 1, the minimum thickness of the polymer covering the surface layer of the conjugate fibers is calculated in units of µm for 10 conjugate fibers randomly extracted from the same image in respective images. Values are calculated by dividing the obtained value of the minimum thickness S by a value of the fiber diameter D, the value of the fiber diameter D being calculated by measuring an area of each conjugate fiber and measuring a diameter calculated in terms of a perfect circle and by rounding off to the first decimal place in units of µm, and an average value of the values is rounded off to the two decimal places to thereby obtain the ratio S/D of the minimum thickness S to the fiber diameter D of the polymer covering the surface layer of the conjugate fibers.
[0048] As an area ratio of the low melting point polymer and the high melting point polymer in the cross-sectional morphology of the conjugate fibers constituting the conjugate fiber bundle of the present embodiment, an area of the low melting point polymer/an area of the high melting point polymer is preferably in a range of 70/30 to 30/70, and more preferably in a range of 60/40 to 40/60. Within such a range, the low melting point polymer is not affected by texture hardening that occurs when the low melting point polymer is highly contracted due to the heat treatment, and the crimp form due to the contraction difference of the polymers can be sufficiently developed.
[0049] In the present embodiment, when the crimp phases between the conjugate fibers constituting the conjugate fiber bundle are partially aligned, a difference is generated in the void between a portion where the crimp phases are aligned between the adjacent conjugate fibers and a portion where the crimp phases are not aligned between the adjacent conjugate fibers, and therefore, when the conjugate fiber bundle is formed into a textile, irregularities can be formed on a surface thereof.
[0050] As a requirement for forming complex voids between the conjugate fibers and irregularities on a textile surface, which is a characteristic of the present invention as described above, it is important that the coefficient of variation CV of the value of (distance between polymer gravity centers/fiber diameter) between the conjugate fibers is 5% to 30%.
[0051] The coefficient of variation CV of the value of (distance between polymer gravity centers/fiber diameter) referred to in the present embodiment can be calculated by the following method.
[0052] First, in the textile formed of the conjugate fiber bundle, an image of a textile cross section perpendicular to a thickness direction of the textile and a fiber axis direction of the conjugate fiber is captured using a scanning electron microscope (SEM) at a magnification at which 20 or more conjugate fibers can be observed. One conjugate fiber randomly extracted from the same image in the captured image is analyzed to measure an area of the conjugate fiber, and a diameter calculated in terms of a perfect circle is measured up to the first decimal place in units of µm. The obtained value is defined as a fiber diameter (µm) of the conjugate fiber.
[0053] Next, for the same conjugate fiber as described above, a length of a straight line connecting gravity centers (Gx and Gy) of a low melting point polymer x and a high melting point polymer y in a cross section of the conjugate fiber as illustrated in (a) of FIG. 2 is measured up to the first decimal place in units of µm. The obtained value is defined as a distance between polymer gravity centers (µm).
[0054] With respect to the fiber diameter and the distance between polymer gravity centers calculated as described above, a simple number average of a ratio of (distance between polymer gravity centers/fiber diameter) is calculated, and a value obtained by rounding off to the nearest whole number is defined as the (distance between polymer gravity centers/fiber diameter).
[0055] This evaluation is performed for 20 conjugate fibers ((1) to (20) in FIG. 5) randomly extracted from the same image as described above, a standard deviation and an average value thereof are obtained, a value obtained by dividing the standard deviation by the average value and being multiplied by 100 is calculated, and decimal places of the value are rounded off. The obtained value is defined as the coefficient of variation CV (%) of the value of (distance between polymer gravity centers/fiber diameter).
[0056] In the conjugate fibers constituting the conjugate fiber bundle of the present embodiment, the crimp form can be controlled by the distance between polymer gravity centers and the fiber diameter, and the larger the distance between polymer gravity centers and the smaller the fiber diameter, the finer crimp form can be developed. That is, crimp development ability is expressed by the (distance between polymer gravity centers/fiber diameter), and by controlling the crimp development ability for each conjugate fiber, formation of the complex voids and the irregularities on the textile surface, which are developed by aligning the crimp phases between the conjugate fibers, can be controlled.
[0057] That is, in the present embodiment, the coefficient of variation CV of the value of (distance between polymer gravity centers/fiber diameter) between the conjugate fibers constituting the conjugate fiber bundle is 5% or more. By setting the coefficient of variation CV within the above-mentioned range, the crimp phases are partially aligned, and thus irregularities appear on the textile surface, and a smooth tactile sensation due to large friction variation is obtained when the surface is touched. In addition, complex voids are generated between the conjugate fibers, and it is also possible to exhibit an effect of preventing appearance unevenness (glare) due to a texture having appropriate feeling of resilience and irregular reflection of light.
[0058] Further, the coefficient of variation CV of the value of (distance between polymer gravity centers/fiber diameter) is more preferably in a range of 10% to 20%, and still more preferably in a range of 15% to 20%. In the case where the coefficient of variation CV is within the above-mentioned range, when the conjugate fiber bundle is formed into a textile, a pitch of the irregularities on the textile surface becomes fine, and the smooth tactile sensation becomes conspicuous. Further, as the number of voids between the conjugate fibers increases, an appearance density is reduced when the conjugate fiber bundle is formed into a textile, and an effect of improving swelling is also added.
[0059] In addition, when the coefficient of variation CV becomes too large, the irregularities developed on the textile surface become fine, and further the friction variation becomes small, so that the texture is close to a monotonic texture. Therefore, the coefficient of variation CV is 30% or less.
[0060] In the conjugate fibers constituting the conjugate fiber bundle of the present embodiment, as a method of controlling the (distance between polymer gravity centers/fiber diameter), a method of changing a cross-sectional shape and a conjugate ratio of the conjugate fiber for each conjugate fiber is conceivable. However, from the viewpoint of control of crimp phase alignment and stability of yarn production, a method is preferable in which the cross-sectional shape of the conjugate fibers constituting the conjugate fiber bundle is made a flat shape, and a difference between a maximum value and a minimum value of flatness between the conjugate fibers is less than 0.5. Here, the "flat shape" refers to an elongated shape in a plan view, and specifically refers to a shape having a "flatness" of 1.1 or more in a cross section of a conjugate fiber to be described later.
[0061] When the cross-sectional shape of the conjugate fiber is made a flat shape (flat cross section), the distance between polymer gravity centers becomes maximum in the case where the polymers having different melting points are bonded in a long axis direction of the flat cross section as illustrated in (a) of FIG. 2, and the distance between polymer gravity centers becomes minimum in the case where the polymers are bonded in a short axis direction of the flat cross section as illustrated in (b) of FIG. 2. In this manner, by making the cross-sectional shape of the conjugate fiber a flat shape, the value of (distance between polymer gravity centers/fiber diameter) can be controlled by changing a direction of a bonding surface of the conjugate fiber.
[0062] Therefore, it is preferable that the difference between the maximum value the flatness and the minimum value of the flatness between the conjugate fibers is less than 0.5, and further, as illustrated in FIG. 4, it is more preferable to form a cross-sectional morphology in which a bonding surface direction is changed for each conjugate fiber. When the conjugate fibers have the above-mentioned configuration, the crimp phases between the conjugate fibers are easily partially aligned, and the coefficient of variation CV of the value of (distance between polymer gravity centers/fiber diameter) can be easily set within a target range. Further, from the viewpoint of preventing yarn breakage caused by yarn interference or the like due to cooling irregularities and improving stability of yarn production as compared with the case where the cross-sectional shape or the conjugate ratio is changed for each conjugate fiber, the difference between the maximum value of the flatness and the minimum value of the flatness between the conjugate fibers is more preferably less than 0.2.
[0063] In order to further develop the above-mentioned effect, in the present embodiment, an average value of the flatness between the conjugate fibers is preferably 1.2 or more, more preferably 1.4 or more, and still more preferably 1.6 or more. When the average value of the flatness between the conjugate fibers is 1.2 or more, the coefficient of variation CV of the value of (distance between polymer gravity centers/fiber diameter) can be brought closer to an optimum range. Further, voids between the conjugate fibers are formed due to steric hindrance when the conjugate fibers having a flat cross section develop crimps, and swelling when the conjugate fiber bundle is formed into a textile is also obtained.
[0064] As described above, from the viewpoint of controlling the coefficient of variation CV of the value of (distance between polymer gravity centers/fiber diameter) and stably forming the voids between conjugate fibers, a higher average value of the flatness is preferable. On the other hand, when the average value of the flatness is too high, light reflected by the surface of the conjugate fiber becomes strong, and thus appearance unevenness (glare) may occur. In addition, when flexural rigidity is increased more than necessary due to the cross-sectional shape having an edge, the flexibility may be impaired. Therefore, the average value of the flatness in the present embodiment is preferably 3.0 or less, more preferably 2.5 or less, and still more preferably 2.0 or less.
[0065] In the present embodiment, the average value and the difference between the maximum value and the minimum value of the flatness of the conjugate fibers are calculated by the following method.
[0066] First, the conjugate fiber bundle is embedded in an embedding agent such as an epoxy resin, and an image of a fiber cross section in a direction perpendicular to a fiber axis is captured at a magnification at which 10 or more conjugate fibers can be observed with a scanning electron microscope (SEM). Next, one conjugate fiber randomly extracted from the captured image is analyzed using image analysis software, a value obtained by dividing a length of a long axis by a length of a short axis is calculated, where, as illustrated in (a) of FIG. 1, the long axis is a straight line connecting two points (a1 and a2) at a longest distance among any points on an outer periphery of the conjugate fiber, and the short axis is a straight line connecting intersection points (b1 and b2) of the outer periphery of the fiber and a straight line passing through a middle point of the long axis and orthogonal to the long axis, and the obtained value is defined as the flatness. A simple number average of results obtained in the same manner for 10 conjugate fibers randomly extracted in the same image is calculated, and the value obtained by rounding off to the first decimal place is defined as the average value of the flatness. In addition, a value obtained by subtracting a smallest value from a largest value among those of the conjugate fibers for which the flatness was obtained is calculated, and a value obtained by rounding off to the first decimal place is defined as the difference between the maximum value of the flatness and the minimum value of the flatness.
[0067] Examples of the cross-sectional shape of the conjugate fiber constituting the conjugate fiber bundle of the present embodiment include, in addition to the flat shape as illustrated in (a) of FIG. 1, a multilobal shape as illustrated in (c) of FIG. 1, and other shapes such as polygonal shape, a gear shape, a petal-like shape, and a star-like shape.
[0068] In the present embodiment, it is preferable to combine conjugate fibers having a cross-sectional shape having three or more convex portions on the surface of the conjugate fiber. By combining the conjugate fibers having a cross-sectional shape having three or more convex portions on the surface of the conjugate fiber, it is possible to prevent appearance unevenness (glare) due to irregular reflection of light and to increase the water absorption by fine voids between the conjugate fibers. The number of convex portions is more preferably 5 or more, and still more preferably 8 or more.
[0069] However, when the number of the convex portion is too large, the effect thereof gradually decreases, so that a substantial upper limit of the number of the convex portion is 20, and more preferably 12 or less.
[0070] In the conjugate fibers constituting the conjugate fiber bundle of the present embodiment, it is preferable to have a crimp form in which a crimp peak number is 5 peaks/cm or more.
[0072] First, the conjugate fiber is pulled out from the textile so as not to be plastically deformed, one end of the conjugate fiber is fixed, a load of 1 mg/dtex is applied to the other end thereof, and after a lapse of 30 seconds or longer, marking is applied to any portion where a distance between two points in the fiber axis direction of the conjugate fiber is 1 cm.
[0073] Thereafter, a distance between markings previously attached so as not to plastically deform the conjugate fibers is adjusted to be the original 1 cm and fixed on a slide glass, and an image of this sample is captured with a digital microscope at a magnification at which the marking of 1 cm can be observed. In a case where a conjugate fiber CF has a crimp form as illustrated in FIG. 6 in the captured image, the number of crimp peaks Cr present between the markings is calculated. A simple number average of results obtained by performing this operation on 10 conjugate fibers is calculated, and a value obtained by rounding off to the nearest whole number is defined as the crimp peak number (peak/cm).
[0074] When the conjugate fiber has a crimp form having a crimp peak number of 5 peaks/cm or more, complex voids between the conjugate fibers and irregularities on the textile surface, which are developed by aligning the crimp phases between the conjugate fibers, can be formed. The crimp peak number is more preferably 10 peaks/cm or more. When the crimp peak number is 10 peaks/cm or more, not only an effect of improving swelling due to the increase of the voids between the conjugate fibers by an excluded volume effect between the conjugate fibers is obtained, but also the stretchability is imparted because the crimp form has a fine spiral structure.
[0075] From the viewpoint of the swelling and the stretchability, it is preferable to increase the crimp peak number, but when the crimp peak number is excessive, the crimp phases are likely to shift, and the voids between the conjugate fibers become uniform, and thus the texture when the conjugate fiber bundle is formed into a textile may also become monotonic. Therefore, the crimp peak number in the present embodiment is preferably 50 peaks/cm or less, more preferably 40 peaks/cm or less, and still more preferably 30 peaks/cm or less.
[0076] The conjugate fibers constituting the conjugate fiber bundle of the present embodiment preferably have a fiber diameter of 20 µm or less. Within such a range, the irregular reflection of light of the conjugate fibers is increased, and not only the appearance unevenness (glare) when the textile is formed can be prevented, but also the feeling of resilience can be sufficiently obtained. Accordingly, the present invention is suitable for clothing applications required to have a texture with tenseness and stiffness such as pants and shirts.
[0077] Further, the fiber diameter is more preferably 15 µm or less. When the fiber diameter is 15 µm or less, the flexibility of the conjugate fiber bundle is increased, and the present invention can also be suitably used for clothing applications such as innerwear and blouses that come into contact with the skin. The fiber diameter is still more preferably 12 µm or less.
[0078] In addition, from the viewpoint of preventing reduction in the bending recovery property and color development property, the fiber diameter is preferably 5 µm or more, and more preferably 8 µm or more.
[0079] As described above, in the conjugate fiber bundle of the present embodiment, since a difference is generated in voids between the portion where the crimp phases are aligned between adjacent conjugate fibers and the portion where the crimp phases are not aligned between adjacent conjugate fibers, complex voids and irregularities are formed between the conjugate fibers.
[0080] Accordingly, when the fiber product at least partially includes the conjugate fiber bundle of the present embodiment, a textile having excellent wearing comfortableness can be obtained in which a specific smooth tactile sensation can be developed, and in addition, a texture having appropriate feeling of resilience and swelling due to complex voids between the conjugate fibers are also realized.
[0081] The conjugate fiber bundle of the present embodiment can be suitably used for various fiber products including daily life applications such as interior products such as carpets and sofas, vehicle interior products such as car seats, cosmetics, cosmetic masks, and health products in addition to general clothing such as jackets, skirts, pants, and underwear, sports clothing, and clothing materials by utilizing the comfortableness of the conjugate fiber bundle.
[0082] Hereinafter, an example of a production method of the conjugate fiber bundle of the present embodiment will be described in detail.
[0083] As a method of yarn production of the conjugate fiber bundle of the present embodiment, production can be performed by a melt spinning method for producing a multifilament or a spun yarn, a solution spinning method such as wet spinning or dry-wet spinning, a melt blowing method and a spunbonding method suitable for obtaining a sheet-like fiber structure, or the like. Among those, from the viewpoint of obtaining a conjugate fiber bundle that can be applied to a textile with high productivity, it is preferable to produce a multifilament or a spun yarn by the melt spinning method.
[0084] In addition, in the melt spinning method, the production can be performed by using a composite spinneret to be described later, and a spinning temperature in that case is preferably set to a temperature at which mainly a high melting point polymer or a high-viscosity polymer exhibits fluidity among the types of polymers used. The temperature at which the polymer exhibits fluidity also varies depending on a molecular weight, and when the temperature is set between a melting point of the polymer and the melting point + 60°C, the production can be stably performed.
[0085] The spinning speed is preferably about 500 m/min to 6,000 m/min, but can be appropriately changed depending on physical properties of the polymer and an intended use of the conjugate fiber bundle. In particular, from the viewpoint of achieving high orientation and improving mechanical characteristics, it is more preferable to set the spinning speed to 500 m/min to 4,000 m/min and then perform drawing. By setting the spinning speed to 500 m/min to 4,000 m/min, uniaxial orientation of the conjugate fibers can be promoted.
[0086] When the drawing is performed, it is preferable to appropriately set a preheating temperature based on a temperature at which softening is possible such as a glass transition temperature of the polymer. An upper limit of the preheating temperature is preferably set to a temperature at which yarn path disturbance does not occur due to spontaneous elongation of the conjugate fiber bundle in a preheating process. For example, in the case of PET having a glass transition temperature of about 70°C, the preheating temperature is usually set to about 80°C to 95°C.
[0087] A discharge amount per hole in the spinneret for producing the conjugate fiber bundle of the present embodiment is preferably 0.1 g/min per hole to 10 g/min per hole. By setting the discharge amount to the above-mentioned range, stable production is possible. A discharged polymer flow is cooled and solidified, then applied with an oil agent and taken up by a roller having a predetermined peripheral speed. Thereafter, the drawing is performed by a heating roller, and further the obtained polymer is subjected to post-processing as necessary to thereby obtain a conjugate fiber bundle in which desired conjugate fibers are bundled.
[0088] In the conjugate fibers constituting the conjugate fiber bundle of the present embodiment, a melt viscosity ratio of the polymer to be conjugated is preferably less than 5.0. When the melt viscosity ratio is in such a range, excessive crimp development is prevented, and it becomes easy to control the formation of the complex voids and the irregularities on the textile surface that are developed by alignment of the crimp phases between the conjugate fibers, which is the object of the present invention.
[0089] In addition, in production of the conjugate fiber bundle of the present embodiment, when a melt of polymers having a large difference in melt viscosity is spun out from a spinneret as a composite flow, yarn bending in which a polymer on a low viscosity side pushes out a polymer on a high viscosity side may be generated due to a difference in flow rate caused by a difference in resistance received from a wall surface in a spinneret hole, and the yarn may be brought into contact with the spinneret or interferes with the composite flow spun out from another portion, which causes yarn breakage. Also from the above-mentioned viewpoint, the melt viscosity ratio of the polymers to be conjugated is preferably less than 5.0.
[0090] In addition, it is preferable that a difference in solubility parameter value is less than 2.0 because a composite polymer flow can thus be stably formed and a conjugate fiber having a good cross-sectional morphology can be obtained.
[0091] As the spinneret used for producing the conjugate fiber bundle of the present embodiment, for example, a composite spinneret disclosed in JP2011-208313A is suitably used.
[0092] The composite spinneret illustrated in FIG. 7 is incorporated into a spinning pack in a state where roughly three types of members including a measuring plate 1, a distribution plate 2, and a discharge plate 3 are stacked from the top, and is used for spinning. Incidentally, FIG. 7 is an example in which three types of polymers including polymer A, polymer B, and polymer C are used. Since it is difficult to conjugate three or more types of polymers with a composite spinneret in the related art, it is preferable to use the composite spinneret utilizing a fine flow path as illustrated in FIG. 7 in the production of the conjugate fiber bundle of the present embodiment.
[0093] In the members of the spinneret illustrated in FIG. 7, the measuring plate 1 measures an amount of polymer per each discharge hole and each distribution hole and allows the polymer to flow thereinto, the distribution plate 2 controls a cross section of each conjugate fiber and a cross-sectional shape thereof, and the discharge plate 3 compresses and a composite polymer flow formed by the distribution plate 2 and then discharges it.
[0094] In this case, in order to achieve a cross-sectional morphology in which a bonding surface direction is changed for each conjugate fiber while all the conjugate fibers constituting the conjugate fiber bundle have a flat cross section as exemplified as a preferred range of the present embodiment, a shape of the discharge hole of the discharge plate 3 may be a flat hole, and the composite polymer flow may be controlled such that the bonding surface direction of the polymer is different for each discharge hole in the distribution plate 2. From the viewpoint that any cross-sectional morphology can be controlled for each discharge hole as described above, in the present embodiment, it is preferable to use the composite spinneret utilizing the fine flow path as illustrated in FIG. 7.
[0095] In order to avoid complication of description of the composite spinneret, although not illustrated, a member forming a flow path may be used in accordance with a spinning machine and the spinning pack as a member stacked above the measuring plate 1. By designing the measuring plate 1 in accordance with an existing flow path member, an existing spinning pack and a member thereof can be directly utilized. Therefore, it is unnecessary to exclusively use a spinning machine for the spinneret.
[0096] Actually, a plurality of flow path plates may be stacked between the flow path and the measuring plate 1 or between the measuring plate 1 and the distribution plate 2. The purpose of the above is to provide a flow path through which the polymer is efficiently transferred in a cross-sectional direction of the spinneret and a cross-sectional direction of the conjugate fiber and to introduce the polymer into the distribution plate 2. The composite polymer flow discharged from the discharge plate 3 is cooled and solidified according to the above-described production method, then applied with an oil agent, and taken up by a roller having a predetermined peripheral speed. Thereafter, the drawing is performed by a heating roller, and the obtained polymer is subjected to post-processing as necessary to thereby obtain a conjugate fiber bundle in which desired conjugate fibers are bundled.
[0097] The post-processing referred to herein is performed in the case where the spun yarn formed of staple fibers is to be produced, and it is preferable that, after the drawing, crimps are imparted by using a push-in type crimping machine (crimper) or the like, then yarns are cut into staple fibers having a fiber length of 20 mm to 120 mm, and then a known spinning technique is applied thereto.
[0098] In the case where a multifilament formed of filaments is to be produced, a known yarn processing technique such as false twist processing or non-uniform drawing processing may be applied thereto simultaneously with drawing.
[0099] In particular, from the viewpoint of changing the crimp form to a non-uniform form and making the obtained tactile sensation and texture complex, it is preferable to perform non-uniform drawing processing and to perform drawing processing at a drawing ratio in a range not exceeding a natural drawing ratio of the conjugate fiber, thereby obtaining a slub (thick and thin) yarn in which drawn portions and undrawn portions randomly appear in the fiber axis direction. By performing the non-uniform drawing processing, a difference in dyeability is generated between the drawn portions and the undrawn portions, and therefore, shades of colors are further emphasized, and a grain pattern like a natural material can be expressed when the textile is formed.
[0100] In a method of performing the non-uniform drawing processing, the drawing ratio is preferably in a range of a lower limit of the natural drawing ratio × 1.2 times to an upper limit thereof because a natural and clear grain pattern can be thus obtained, and the ratio may be determined according to a desired grain pattern.
[0101] In addition, in the case where the false twist processing is performed, the method is not particularly limited as long as the method is generally used in polyesters, but in consideration of productivity, it is preferable to perform the processing using a friction false twisting machine using a disc or a belt.
[0102] In order to stably produce crimped yarns of the present invention by the false twist processing, it is preferable to control a crimping diameter of the crimped yarns according to an actual number of twist of yarn bundles in a twisting region.
[0103] That is, it is preferable to set false twist conditions such as a rotational frequency and a processing speed of a twisting mechanism so as to satisfy the following conditions in which a false twist number T (unit: times/m), which is the number of twist of the yarn bundles in the twisting region, is determined according to a total fineness Df (unit: dtex) of the yarn bundles after the false twist processing.
[0104] Here, the false twist number T is measured by the following method. That is, the yarn bundles running in the twisting region in a false twist process are collected in a length of 50 cm or more so as not to untwist immediately before the twister. Then, the collected yarn sample is attached to a twist inspection machine, and the number of twist is measured by the method disclosed in 8.13 of JIS L1013 (2010), which is the false twist number T. When the false twist number satisfies the above-described conditions, by the obtained yarn bundles, a coarse crimping diameter of 300 µm or more can be controlled, and reduction in surface quality of the textile such as wrinkles or streaks can be prevented.
[0105] In addition, in the above-mentioned false twist conditions, in order to impart uniform crimps to the entire conjugate fibers constituting the conjugate fiber bundle and to obtain a processed yarn of the present invention with good quality, the drawing ratio in the twisting region may be adjusted. The drawing ratio referred to herein is calculated as Vd/V0 using a peripheral speed V0 of a roller that supplies a yarn to the twisting region and a peripheral speed Vd of a roller installed immediately downstream of the twisting mechanism, and is preferably determined according to characteristics of the supplied yarn.
[0106] In the case where a drawn yarn is used as the supplied yarn, Vd/V0 may be set to 0.9 times to 1.4 times, and in the case where an undrawn yarn is used as the supplied yarn, drawing may be performed simultaneously with the false twist processing with Vd/V0 being set to 1.2 times to 2.0 times. By setting the drawing ratio to such a range, uniform crimps can be imparted to the entire conjugate fibers constituting the conjugate fiber bundle without generating excessive tension or slack of the yarn bundle in the twisting region.
[0107] Further, from the viewpoint of firmly fixing the crimps obtained in a twisting process, a false twist temperature is preferably determined in a range of Tg+50°C to Tg+150°C based on Tg of a polymer on a high Tg side in the conjugated polymer.
[0108] The false twist temperature referred to herein means a temperature of the heater installed in the twisting region. By setting the false twist temperature within such a range, the structure of the polymer greatly twisted and deformed in a cross section of the conjugate fiber can be sufficiently fixed, and thus the crimps obtained in the twisting process have good dimensional stability, and a high-quality textile without wrinkles or streaks can be obtained. In order to fix the crimps obtained in the twisting process and not to impair development ability of the crimps obtained by the polymer conjugate, it is preferable to use a one-heater method in which a heater is disposed only in the twisting region.
EXAMPLES
[0109] Hereinafter, the conjugate fiber bundle of the present invention will be specifically described with reference to the examples.
[0110] The examples and comparative examples were evaluated as follows.
- A. Melt Viscosity of Polymer
A moisture content of a chip-like polymer was set to 200 ppm or less by a vacuum dryer, and the melt viscosity is measured by changing a strain rate in a stepwise manner by a Capillograph manufactured by Toyo Seiki Seisakusho Co., Ltd. Evaluation was performed by setting a measurement temperature be the same as the spinning temperature, setting a period from the time when a sample was put into a heating furnace under a nitrogen atmosphere to the time when a measurement was started to 5 minutes, and setting a value of a shear rate of 1,216 s-1 as the melt viscosity of the polymer. - B. Melting Point of Polymer
A moisture content of a chip-like polymer was set to 200 ppm or less using a vacuum dryer, about 5 mg of the chip-like polymer was weighed out, heated at a heating rate of 16°C/min from 0°C to 300°C using a differential scanning calorimeter (DSC) Q2000 manufactured by TA Instruments, and then held at 300°C for 5 minutes to perform DSC measurement. A melting point was calculated based on a melting peak observed during the heating process. The measurement was performed three times for each sample, and an average value thereof was defined as the melting point. In the case where a plurality of melting peaks was observed, a melting peak top on the highest temperature side was defined as the melting point. - C. Fineness
A weight of a conjugate fiber bundle of 100m was measured, and a value obtained by multiplying a value of the weight by 100 was calculated. This operation was repeated 10 times, and a value obtained by rounding off an average value thereof to the first decimal place was defined as the fineness (dtex). - D. Flatness
A conjugate fiber bundle was embedded in an embedding agent such as an epoxy resin, and an image of a fiber cross section in a direction perpendicular to a fiber axis was captured with a scanning electron microscope (SEM) manufactured by HITACHI, Ltd. at a magnification at which 10 or more conjugate fibers can be observed. One conjugate fiber randomly extracted from the captured image was analyzed using image analysis software, a value obtained by dividing a length of a long axis by a length of a short axis was calculated, where, as illustrated in (a) of FIG. 1, the long axis was a straight line connecting two points (a1 and a2) at a longest distance among any points on an outer periphery of the conjugate fiber, and the short axis was a straight line connecting intersection points (b1 and b2) of the outer periphery of the fiber and a straight line passing through a middle point of the long axis and orthogonal to the long axis, and the obtained value was defined as the flatness. A simple number average of results obtained in the same manner for 10 conjugate fibers randomly extracted in the same image was calculated, and the value obtained by rounding off to the first decimal place was defined as an average value of the flatness. In addition, a value obtained by subtracting a smallest value from a largest value among those of the conjugate fibers for which the flatness was obtained was calculated, and a value obtained by rounding off to the first decimal place was defined as the difference between the maximum value and the minimum value of the flatness. - E. Fiber Diameter
A conjugate fiber bundle was embedded in an embedding agent such as an epoxy resin, and an image of a fiber cross section in a direction perpendicular to a fiber axis was captured with a scanning electron microscope (SEM) at a magnification at which 10 or more conjugate fibers can be observed. An area of one conjugate fiber randomly extracted from the captured image was measured, and a diameter calculated in terms of a perfect circle was measured up to the first decimal place in units of µm. A simple number average of results obtained in the same manner for 10 conjugate fibers randomly extracted in the same image as above was calculated, and the value obtained by rounding off to the nearest whole number was defined as the fiber diameter (µm). - F. Coefficient of Variation CV of (Distance between Polymer Gravity Centers/Fiber Diameter)
[0111] In a textile formed of a conjugate fiber bundle, an image of a textile cross section perpendicular to a length direction of the textile and perpendicular to a fiber axis direction of the conjugate fiber was captured with a scanning electron microscope (SEM) manufactured by HITACHI, Ltd. at a magnification at which 20 or more conjugate fibers can be observed. One conjugate fiber randomly extracted from the captured image was analyzed using WinROOF manufactured by MITANI CORPORATION which is computer software to measure an area of the conjugate fiber, and a diameter calculated in terms of a perfect circle was measured up to the first decimal place in units of µm. The obtained value was defined as the fiber diameter (µm).
[0112] In addition, for the same conjugate fiber as described above, a length of a straight line connecting gravity centers (Gx and Gy) of a low melting point polymer x and a high melting point polymer y in a cross section of the conjugate fiber as illustrated in (a) of FIG. 2 was measured up to the first decimal place in units of µm. The obtained value was defined as the distance between polymer gravity centers (µm).
[0113] With respect to the fiber diameter and the distance between polymer gravity centers obtained as described above, a simple number average of a ratio of (distance between polymer gravity centers/fiber diameter) was calculated, and a value obtained by rounding off to the nearest whole number was defined as the (distance between polymer gravity centers/fiber diameter). This evaluation was performed in the same manner for 20 conjugate fibers ((1) to (20) in FIG. 5) randomly extracted from the same image, a standard deviation and an average value of results thereof were calculated, a value obtained by dividing the standard deviation by the average value and being multiplied by 100 was calculated, and the decimal places were rounded off. The obtained value was defined as the coefficient of variation CV (%) of the value of (distance between polymer gravity centers/fiber diameter).
G. Crimp Peak Number (peak/cm)
[0114] In a textile formed of the conjugate fiber bundle, the conjugate fiber was pulled out from the textile so as not to be plastically deformed, one end of the conjugate fiber was fixed, the other end thereof was applied with a load of 1 mg/dtex, and after a lapse of 30 seconds or longer, marking was applied to any portion where a distance between two points in the fiber axis direction of the conjugate fiber was 1 cm. Thereafter, a distance between markings previously attached so as not to plastically deform the conjugate fiber was adjusted to be the original 1 cm and fixed on a slide glass, and an image of this sample was captured with a digital microscope at a magnification at which the 1 cm markings can be observed. In the case where the conjugate fiber has a crimp form as illustrated in FIG. 6 in the captured image, the number of peaks of crimps present between the markings was calculated. A simple number average of results obtained by performing this operation on 10 conjugate fibers was calculated, and a value obtained by rounding off to the nearest whole number was defined as the crimp peak number (peak/cm).
H. Stability of Yarn Production
[0115] Yarn production was performed with respect to respective examples and comparative examples, and the stability of yarn production was respectively determined as four stages based on the following standards based on the number of times of yarn breakage per ten million meters (times/ten million meters).
S: Excellent stability of yarn production (number of times of yarn breakage < 1.0)
A: Good stability of yarn production (1.0 ≤ number of times of yarn breakage < 2.0)
B: Having stability of yarn production (2.0 ≤ number of times of yarn breakage < 3.0)
C: Poor stability of yarn production (3.0 ≤ number of times of yarn breakage).
I. Textile Texture Evaluation (Swelling Feeling, Feeling of Resilience, Smoothness)
[0116] The number of conjugate fibers was adjusted such that a cover factor (CFA) in a warp direction was 800 and a cover factor (CFB) in a weft direction was 1,200, thereby preparing a 3/1 twill fabric.
[0117] Incidentally, CFA and CFB referred to herein are values obtained by measuring a warp density and a weft density of the fabric in a section of 2.54 cm in accordance with 8.6.1 of JIS-L-1096:2010 and calculating based on formulae CFA = warp density × (fineness of warp)1/2 and CFB = weft density × (fineness of weft)1/2. The obtained fabric was subjected to refining, relaxation, and heat setting under the following conditions in this order, and then was subjected to evaluation using the following methods for three textures of swelling feeling, feeling of resilience, and smoothness.
(Refining, Wet Heat Treatment, and Heat Setting)
[0118] Refining was performed in warm water at 80°C containing a surfactant for 10 minutes, and then relaxation was performed in warm water at 130°C for 30 minutes. Next, heat setting was performed under conditions of 180°C and 5 minutes.
I-1. Swelling Feeling
[0119] A thickness (cm) of a fabric of 20 cm × 20 cm was measured under a constant pressure (0.7 kPa) using a constant-pressure thickness measuring device (PG-14J) manufactured by Terror Tech Co., Ltd., and a volume of the fabric was calculated. Next, a value obtained by dividing the weight (g) of the fabric by the obtained volume was calculated, and a value obtained by rounding off to the first decimal place was defined as appearance density (g/cm3) of the fabric. The swelling feeling was respectively determined as four stages based on the following standards based on the obtained appearance density.
S: Excellent swelling feeling (appearance density ≤ 0.5)
A: Good swelling feeling (0.5 < appearance density ≤ 0.8)
B: Having swelling feeling (0.8 < appearance density ≤ 1.1)
C: Poor swelling feeling (1.1 < appearance density).
I-2. Feeling of Resilience
[0120] Using a pure bending tester (KES-FB2) manufactured by KATO TECH CO., LTD., a fabric of 20 cm × 20 cm was gripped with an effective sample length of 20 cm × 1 cm, and a width (gf·cm/cm) of hysteresis in a curvature of ± 1.0 cm-1 when the fabric was bent in a weft direction was calculated. This operation was performed three times for each portion, and a simple number average of results obtained by performing this operation for 10 portions in total was calculated, and a value obtained by dividing the number average after rounding off to the three decimal places by 100 was defined as a bending recovery 2HB × 10-2 (gf·cm/cm). The feeling of resilience was respectively determined as four stages based on the following standards based on the obtained bending recovery 2HB × 10-2.
S: Excellent feeling of resilience (bending recovery 2HB × 10-2 ≤ 0.8)
A: Good feeling of resilience (0.8 < bending recovery 2HB × 10-2 ≤ 1.5)
B: Having feeling of resilience (1.5 < bending recovery 2HB × 10-2 ≤ 2.5)
C: Poor feeling of resilience (2.5 < bending recovery 2HB × 10-2).
I -3. Smoothness
[0121] Using an automatic surface tester (KES-FB4) manufactured by KATO TECH CO., LTD., a fabric of 20 cm × 20 cm was applied with a load of 50 g on a 1 cm × 1 cm terminal wound with a piano wire in a range of 10 cm × 10 cm thereof, and a variation MMD in an average friction coefficient was calculated by sliding the fabric at a speed of 1.0 mm/sec. This operation was performed three times for each portion, and a simple number average with respect to results obtained by performing this operation for 10 portions in total was calculated, and a value obtained by rounding off to the three decimal places was defined as a friction variation (× 10-2). The smoothness was determined as four stages based on the following standards based on the obtained friction variation.
S: Excellent smoothness (1.5 ≤ friction variation)
A: Good smoothness (1.2 ≤ friction variation < 1.5)
B: Having smoothness (0.9 ≤ friction variation < 1.2)
C: Poor smoothness (friction variation < 0.9).
J. Textile Function Evaluation (Water-absorbing and Quick-drying Property, Stretchability)
[0122] The number of conjugate fibers was adjusted such that a cover factor (CFA) in a warp direction was 800 and a cover factor (CFB) in a weft direction was 1,200, thereby preparing a 3/1 twill fabric. Incidentally, CFA and CFB referred to herein are values obtained by measuring a warp density and a weft density of the fabric in a section of 2.54 cm in accordance with 8.6.1 of JIS-L-1096:2010 and calculating based on formulae CFA = warp density × (fineness of warp)1/2 and CFB = weft density × (fineness of weft)1/2. The obtained fabric was subjected to refining, wet heat treatment, alkali treatment, and heat setting in this order, and then was subjected to evaluation using the following methods for two functions of water-absorbing and quick-drying property and stretchability. The refining, the relaxation, and the heat setting were performed under the same conditions as in the textile texture evaluation, and the alkali treatment was performed under the following conditions.
(Alkali Treatment)
[0123] The fabric was immersed in an aqueous solution of sodium hydroxide having a concentration of 0.5 mass% to 2 mass% at a temperature of 90°C for 30 minutes.
J-1. Water-absorbing and Quick-drying Property
[0124] Regarding the water-absorbing and quick-drying property, 0.1 cc of water was dropped to a fabric of 10 cm × 10 cm, then a weight of the fabric was measured every 5 minutes in an environment at a temperature of 20°C and a relative humidity of 65 RH%, and a time (minutes) when a residual moisture content was 1.0% or less was calculated. A simple number average of results obtained by performing this operation for three positions in total was calculated, and a value obtained by rounding off the decimal places was defined as a water diffusion time (minutes). The water-absorbing and quick-drying property was respectively determined as three stages based on the following standards based on the obtained water diffusion time.
S: Excellent water-absorbing and quick-drying property (water diffusion time ≤ 15)
A: Good water-absorbing and quick-drying property (15 < water diffusion time ≤ 30)
C: Poor water-absorbing and quick-drying property (30 < water diffusion time).
J-2. Stretchability
[0125] The stretchability was measured in accordance with method A of elongation rate (constant rate elongation method) described in section 8.16.1 of JIS-L-1096:2010. A case of a load of 17.6 N (1.8 kg) in a stripping method was used, and test conditions thereof were a sample width of 5 cm x a length of 20 cm, a clamp interval of 10 cm, and a tensile speed of 20 cm/min. In addition, as an initial load, a weight corresponding to a sample width of 1 m was used in accordance with the method of JIS-L-1096:2010. A simple number average of results obtained by performing the test three times in a lateral direction of the fabric was calculated, and a value obtained by rounding off the decimal places was defined as an elongation rate (%). The stretchability was respectively determined as three stages based on the following standards based on the obtained elongation rate.
S: Excellent stretchability (20 ≤ elongation rate)
A: Good stretchability (5 ≤ elongation rate < 20)
C: Poor stretchability (elongation rate < 5).
K. Textile Quality Evaluation (Appearance Quality)
[0126] The number of conjugate fibers was adjusted such that a cover factor (CFA) in a warp direction was 800 and a cover factor (CFB) in a weft direction was 1,200, thereby preparing a 3/1 twill fabric. Incidentally, CFA and CFB referred to herein are values obtained by measuring a warp density and a weft density of the fabric in a section of 2.54 cm in accordance with 8.6.1 of JIS-L-1096:2010 and calculating based on formulae CFA = warp density × (fineness of warp)1/2 and CFB = weft density × (fineness of weft) 1/2.
[0127] The obtained fabric was subjected to refining, relaxation, and heat setting under the same conditions as in the textile texture evaluation. Thereafter, light was incident on each sample at an incident angle of 60° using an automatic goniophotometer (GONIOPHOTOMETER GP-200 type) manufactured by Murakami Color Research Laboratory Co., Ltd., light intensity at a light receiving angle of 0° to 90° was calculated by two-dimensional reflection light distribution measurement every 0.1°, and a value obtained by dividing a maximum light intensity (specular reflection) near the light receiving angle of 60° by a minimum light intensity (diffuse reflection) near the light receiving angle of 0° was calculated. This operation was performed three times for each portion, and a simple number average with respect to results calculated by performing this operation for 10 portions in total was calculated, and a value obtained by rounding off to the first decimal place was defined as a degree of glare. The appearance quality of the textile was determined as four stages based on the following standards based on the obtained degree of glare.
S: Excellent appearance quality (degree of glare < 2.0)
A: Good appearance quality (2.0 ≤ degree of glare < 2.5)
B: Having appearance quality (2.5 ≤ degree of glare < 3.0)
C: Poor appearance quality (3.0 ≤ degree of glare).
L. Abrasion Resistance
[0128] The number of conjugate fibers was adjusted such that a cover factor (CFA) in a warp direction was 1,100 and a cover factor (CFB) in a weft direction was 1,100, thereby preparing a plain fabric. The obtained plain fabric was dyed black using a disperse dye of Sumikaron Black S-3B (10% owf). The dyed plain fabric was cut into a circular shape having a diameter of 10 cm, wet with distilled water, and attached to a disc. Further, a plain fabric cut into a 30 cm square was fixed on a horizontal plate while remaining dry. The disc to which the fabric wet with distilled water was attached was horizontally brought into contact with the fabric fixed on the horizontal plate, and the disc was circularly moved with a load of 420 g and at a speed of 50 rpm for 10 minutes such that a center of the disc stretched a circle having a diameter of 10 cm, thereby generating a friction between the two fabrics. After allowing the fabrics to stand for 4 hours after completion of the friction, a degree of discoloration of the fabric attached to the disc was subjected to a grade determination of grade 1 to grade 5 in increments of 0.5 using a gray scale for discoloration. The abrasion resistance was determined as four stages based on the following standards based on the obtained results of the grade determination.
S: Excellent abrasion resistance (grade discoloration: Grade 4.5 or more)
A: Good abrasion resistance (grade discoloration: Grade 3.5 and Grade 4)
B: Good abrasion resistance (grade discoloration: Grade 2.5 and Grade 3)
C: Poor abrasion resistance (grade discoloration: Grade 2 or lower).
[Example 1]
[0129] Polyethylene terephthalate (IPA copolymerized PET, melt viscosity: 140 Pa·s, melting point: 232°C) copolymerized with 7 mol% of isophthalic acid as Polymer 1 and polyethylene terephthalate (PET, melt viscosity: 130 Pa·s, melting point: 254°C) as Polymer 2 were prepared.
[0130] The polymers were separately melted at 290°C and then weighed such that an area ratio of cross-sectional morphology of the polymer 1 and the polymer 2 was 50/50. Next, the above-mentioned polymers were caused to flow into the spinning pack in which the composite spinneret illustrated in FIG. 7 was incorporated, and the inflow polymers were discharged from discharge holes such that the cross-sectional morphology having a flat shape and having the polymer 1 and the polymer 2 bonded in a side-by-side type as illustrated in (a) of FIG. 1 was changed in a bonding surface direction of each conjugate fiber (six types of cross-sectional morphology in FIG. 4 are examples of the cross-sectional morphology).
[0131] The discharged composite polymer flow was cooled and solidified, then applied with an oil agent, wound up at a spinning speed of 1,500 m/min, and drawn between rollers heated to 90°C and 130°C to form a conjugate fiber bundle of 84 dtex-36 filaments (fiber diameter: 15 µm). The number of yarn breakages in this case was 1.5 times/ten million meters, indicating good stability of yarn production.
[0132] Conjugate fibers constituting the obtained conjugate fiber bundle all had a flat cross-sectional shape, an average value of flatness between the conjugate fibers was 1.8, and a difference between a maximum value of the flatness and a minimum value of the flatness was 0.1. In addition, a coefficient of variation CV of a value of (distance between polymer gravity centers/fiber diameter) between the conjugate fibers was 18%, confirming that the obtained conjugate fiber bundle is the conjugate fiber bundle of the present embodiment.
[0133] The obtained conjugate fiber bundle was woven, subjected to a refining treatment at 80°C and a wet heat treatment at 130°C, and then subjected to a heat setting at 180°C, thereby obtaining a fabric formed of a conjugate fiber bundle having a crimp form in which the crimp peak number of the conjugate fibers was 18 peaks/cm.
[0134] The fabric formed of the conjugate fiber bundle developed a smooth tactile sensation (friction variation: 1.3 × 10-2) caused by a large friction variation when touching a surface of a cloth material due to irregularities of the textile surface developed by partial alignment of crimp phases. Further, the fabric formed of the conjugate fiber bundle had complex voids generated between the conjugate fibers, had a texture having appropriate feeling of resilience (bending recovery 2HB: 1.1 × 10-2 gf·cm/cm) and swelling (appearance density: 0.8 g/cm3), had excellent stretchability (elongation rate: 18%), and had water-absorbing and quick-drying property (water diffusion time: 25 minutes) due to the voids formed between the conjugate fibers. Accordingly, the fabric formed of the conjugate fiber bundle was a fabric having excellent wearing comfortableness in which both a texture directly related to wearing comfort of human and functions were achieved.
[0135] Further, regarding an appearance of the fabric, appearance unevenness (glare) was prevented by irregular reflection of light due to formation of the voids between the conjugate fibers, and good appearance quality (degree of glare: 2.4) was obtained. It was also found that when the conjugate fibers included polyethylene terephthalate and a copolymer thereof, the fabric had characteristics suitable for a textile for clothing, such as having good abrasion resistance (Grade 4) without causing discoloration due to fibrillating caused by the polymer. Results of the above are shown in Table 1.
[Comparative Example 1]
[0136] Regarding all the conjugate fibers constituting the conjugate fiber bundle, operations were carried out in accordance with Example 1 except that the bonding surface direction of each conjugate fiber was not changed.
[0137] In Comparative Example 1, since the coefficient of variation CV of the value of (distance between polymer gravity centers/fiber diameter) was 0%, all the conjugate fibers constituting the conjugate fiber bundle developed the same crimp form, resulting in a conjugate fiber bundle in which the crimp phases were aligned. Therefore, irregularities of the textile surface were small, the smoothness was poor, and in addition, the voids between the conjugate fibers were small, and the swelling feeling was poor. Results are shown in Table 1.
[Comparative Example 2]
[0138] Operations were carried out in accordance with Comparative Example 1 except that the polymer 1 was changed to the same PET as the polymer 2, and after the drawing, false twist processing was performed at a rotational frequency at which the false twist number was 3,000 T/m using a friction disc, while heating was performed by a heater set to 180°C between rollers having a processing speed of 250 m/min and a drawing ratio of 1.05 times.
[0139] In Comparative Example 2, since the conjugate fibers included the same polymer, all the conjugate fibers constituting the conjugate fiber bundle developed a uniform crimp form. Therefore, the irregularities of the textile surface became monotonic, and the smoothness was poor. Results are shown in Table 1.
[Comparative Example 3]
[0140] Polyethylene terephthalate (IPA copolymerized PET, melt viscosity: 140 Pa·s, melting point: 232°C) copolymerized with 7 mol% of isophthalic acid as Polymer 1 and polyethylene terephthalate (PET, melt viscosity: 130 Pa·s, melting point: 254°C) as Polymer 2 were prepared.
[0141] The polymers were separately melted at 290°C, then weighed such that an area ratio of cross-sectional morphologies thereof was 50/50, and inflow polymers were discharged from discharge holes such that a cross-sectional morphology having a round cross section and having the polymer 1 and the polymer 2 bonded in a side-by-side type as illustrated in FIG. 3 was obtained. In this case, a discharge amount of each discharge hole was adjusted such that the conjugate fiber bundle was formed of two types of conjugate fibers having different fiber diameters.
[0142] The discharged composite polymer flow was cooled and solidified, then applied with an oil agent, wound up at a spinning speed of 1,500 m/min, and drawn between rollers heated to 90°C and 130°C to form a conjugate fiber bundle of 84 dtex-36 filaments (fiber diameter: 14 µm (minimum value: 11 µm (18 filaments), maximum value: 17 µm (18 filaments)). The fiber diameter of the conjugate fiber bundle referred to herein was calculated by (minimum value + maximum value)/2.
[0143] The obtained conjugate fiber bundle was woven, subjected to a refining treatment at 80°C and a wet heat treatment at 130°C, and then subjected to a heat setting at 180°C, thereby obtaining a fabric formed of the above-mentioned conjugate fiber bundle.
[0144] In Comparative Example 3, since the coefficient of variation CV of the value of (distance between polymer gravity centers/fiber diameter) was 0%, the same crimp development ability was exhibited between the conjugate fibers constituting the conjugate fiber bundle, resulting in a conjugate fiber bundle in which the crimp phases were aligned. Therefore, irregularities of the textile surface were small, the smoothness was poor, and in addition, voids between the conjugate fibers were small, and the swelling feeling and feeling of resilience were poor.
[0145] In addition, since the conjugate fibers having different fiber diameters were simultaneously wound up during fiber production, yarn interference due to different behaviors of cooling solidification occurred, and the stability of yarn production was poor. Results are shown in Table 1.
[Comparative Example 4]
[0146] Polyethylene terephthalate (IPA copolymerized PET, melt viscosity: 140 Pa·s, melting point: 232°C) copolymerized with 7 mol% of isophthalic acid as Polymer 1 and polyethylene terephthalate (PET, melt viscosity: 130 Pa·s, melting point: 254°C) as Polymer 2 were prepared.
[0147] The polymers were separately melted at 290°C, then weighed such that an area ratio of cross-sectional morphologies thereof was 50/50, and inflow polymers were discharged from discharge holes such that a cross-sectional morphology having a flat shape and having the polymer 1 and the polymer 2 bonded in a side-by-side type as illustrated in (a) of FIG. 1 were obtained (the bonding surface direction of each conjugate fiber was not changed). In this case, the discharge holes were adjusted such that the average value of the flatness between the conjugate fibers constituting the conjugate fiber bundle was 1.8 and the difference between the maximum value of the flatness and the minimum value of the flatness was 0.5.
[0148] The discharged composite polymer flow was cooled and solidified, then applied with an oil agent, wound up at a spinning speed of 1,500 m/min, and drawn between rollers heated to 90°C and 130°C to form a conjugate fiber bundle of 84 dtex-36 filaments (fiber diameter: 15 µm).
[0149] The obtained conjugate fiber bundle was woven, subjected to a refining treatment at 80°C and a wet heat treatment at 130°C, and then subjected to a heat setting at 180°C, thereby obtaining a fabric formed of the above-mentioned conjugate fiber bundle.
[0150] In Comparative Example 4, since the coefficient of variation CV of the value of (distance between polymer gravity centers/fiber diameter) was 31%, when the textile was formed, the irregularities of the textile surface became fine, the friction variation was small, and the texture was monotonic.
[0151] In addition, since the conjugate fibers having largely different flatness were simultaneously wound up during fiber production, yarn interference due to different behaviors of cooling solidification occurred, and the stability of yarn production was poor.
[Example 2]
[0152] Operations were carried out in accordance with Example 1 except that a surface layer of the conjugate fibers was covered with PET and the cross-sectional morphology was changed to that illustrated in (b) of FIG. 1. A ratio S/D of a minimum thickness S of PET to a fiber diameter D calculated by the above-described method was 0.03.
[0153] In Example 2, not only the abrasion resistance was improved since the copolymerized PET was not exposed on the surface layer of the conjugate fibers, but also yarn bending after a yarn was discharged from the spinneret was prevented since a difference in cooling between PET and the copolymerized PET was reduced, and the stability of yarn production was also excellent. Results are shown in Table 1.
[Example 3]
[0154] Operations were carried out in accordance with Example 1 except that the cross-sectional shape of the conjugate fiber was changed to a flat and multilobal shape having eight convex portions on the surface as illustrated in (c) of FIG. 1.
[0155] In Example 3, since irregularities were formed on the surface of the conjugate fiber, the appearance unevenness (glare) of the textile due to irregular reflection of light was prevented, and the appearance quality was improved. Further, by combining the conjugate fibers having irregularities on the surface, fine voids between fibers were formed in the conjugate fiber bundle, and the smoothness and the water-absorbing and quick-drying property were also improved. Results are shown in Table 1.
[Example 4]
[0156] Operations were carried out in accordance with Example 1 except that the average value of the flatness between the conjugate fibers was changed to 1.3.
[0157] In Example 4, as the average value of the flatness of the conjugate fibers was reduced, the crimp form developed by the heat treatment became fine and was close to a coil shape. Accordingly, not only the stretchability is enhanced, but also the friction is reduced by reducing an edge having a flat shape, and the abrasion resistance is also improved. Results are shown in Table 2.
[Comparative Example 5]
[0158] Operations were carried out in accordance with Example 1 except that the cross-sectional shape of the conjugate fibers was changed to a round cross section as illustrated in FIG. 3 (the bonding surface direction of each conjugate fiber was not changed).
[0159] In Comparative Example 5, since the coefficient of variation CV of the value of (distance between polymer gravity centers/fiber diameter) was 0%, all the conjugate fibers constituting the conjugate fiber bundle developed the same crimp form, resulting in a converged conjugate fiber bundle in which the crimp phases were aligned. Therefore, no irregularity was generated in the surface of the textile, a flat texture was obtained, and in addition, no void was formed between the conjugate fibers, so that the swelling feeling, the feeling of resilience, and the water-absorbing and quick-drying property were poor. Results are shown in Table 2.
[Example 5]
[0160] Operations were carried out in accordance with Example 1 except that the polymer 2 was changed to PET having a melt viscosity of 30 Pa·s.
[0161] In Example 5, the crimp form was more strongly developed, and not only the swelling feeling of the obtained fabric was increased, but also the stretchability was improved. Results are shown in Table 2.
[Examples 6 and 7]
[0162] Operations were carried out in accordance with Example 1 except that the discharge amount was changed such that the fiber diameter of the conjugate fiber was 10 µm (Example 6) or 20 µm (Example 7).
[0163] In Example 6, since the fiber diameter of the conjugate fiber was set to 10 µm, the irregular reflection of light was increased, and the appearance unevenness (glare) when the textile was formed was prevented to improve the appearance quality, and in addition, the flexibility was also improved since the flexural rigidity of a single fiber was reduced. Results are shown in Table 2.
[0164] In Example 7, since the fiber diameter was set to 20 µm, a loop of the crimp form developed by the heat treatment was increased, the smoothness and the swelling feeling were improved, and in addition, bending hardness was increased, so that a characteristic elastic tactile sensation was obtained. Results are shown in Table 2.
[Example 8]
[0165] Operations were carried out in accordance with Example 1 except that the polymer 2 was changed to polyethylene terephthalate containing 5.0 wt% of titanium oxide (TiOj-containing PET).
[0166] In Example 8, since the titanium oxide on the surface of the conjugate fiber caused irregular reflection of light, the increase and decrease in reflection (glare) due to the incident angle of light was prevented, and the textile appearance quality was improved. In addition, functionality of preventing transparency and shielding ultraviolet can be obtained by the titanium oxide inside the conjugate fiber. Results are shown in Table 2.
[Examples 9 and 10]
[0167] Operations were carried out in accordance with Example 1 except that the polymer 1 was changed to polypropylene terephthalate (PPT) (Example 9) or polybutylene terephthalate (PBT) (Example 10).
[0168] In Examples 9 and 10, combined with properties of rubber elasticity of the PPT and PBT used as the polymer 1, when the conjugate fiber bundle was formed into a textile, not only a texture excellent in flexibility was developed, but also a stretching function was significantly improved. Results are shown in Table 2.
[Example 11]
[0169] Operations were carried out in accordance with Example 1 except that the conjugate polymer flow was wound up at a spinning speed of 2,500 m/min, stored under a standard state (temperature: 23°C, relative humidity: 65%) for one month, and then subjected to non-uniform drawing processing at a hot pin temperature of 70°C and a setting temperature of 130°C at the same drawing ratio as the upper limit of the natural drawing ratio of the conjugate fiber bundle.
[0170] In Example 11, since a difference in dyeability was also generated between the drawn portions and the undrawn portions of the conjugate fiber, when the conjugate fiber bundle was formed into a textile, shades of colors were further emphasized, and a grain pattern like a natural material was obtained. Results are shown in Table 2.
[Table 1]
| Example 1 | Comparative example 1 | Comparative example 2 | Comparative example 3 | ||
| Polymer | Polymer 1 | IPA copolymerized PET | IPA copolymerized PET | PET | IPA copolymerized PET |
| Polymer 2 | PET | PET | PET | PET | |
| Difference in melting point (polymer 2) - (polymer 1) | 22°C | 22°C | 0°C | 22°C | |
| Melt viscosity ratio (polymer 1)/(polymer 2) | 1.1 | 1.1 | 1.0 | 1.1 | |
| Area ratio (polymer 1)/(polymer 2) | 50/50 | 50/50 | 50/50 | 50/50 | |
| Conjugate fiber | Cross-sectional shape | Flat | Flat | Flat | Circular |
| Cross-sectional morphology | (a) of FIG. 1 | (a) of FIG. 1 | - | FIG. 3 | |
| Change in cross-sectional morphology for each composite fiber | Changed (FIG. 4) | No change | - | No change | |
| Average value of flatness | 1.8 | 1.8 | 1.8 | 1.8 | |
| Difference between maximum value of flatness and minimum value of flatness | 0.1 | 0.1 | 0.1 | 0.1 | |
| Fiber diameter (µm) | 15 | 15 | 15 | 14 (minimum value: 11, maximum value: 17) | |
| Coefficient of variation CV (%) of (distance between polymer gravity centers/fiber diameter) | 18 | 0 | - | 0 | |
| Crimp form | Crimp peak number (peak/cm) | 18 | 24 | 54 | 23 |
| Yarn production | Stability of yarn production (number of times of yarn breakage (times/ten million meters)) | A (1.5) | A (1.2) | S (0.5) | C (4.2) |
| Textile texture | Swelling feeling (appearance density (g/cm3)) | A (0.8) | B (1.0) | A (0.6) | B (1.1) |
| Feeling of resilience (bending recovery: 2HB × 10-2 (gf·cm/cm)) | A (1.1) | A (1.4) | A (0.9) | B (2.0) | |
| Smoothness (friction variation × 10-2) | A (1.3) | C (0.8) | C (0.6) | C (0.4) | |
| Textile function | Water-absorbing and quick-drying property (water diffusion time (min)) | A (25) | A (30) | A (25) | A (30) |
| Stretchability (elongation rate (%)) | A (18) | S (22) | A (10) | S (25) | |
| Textile quality | Appearance quality (degree of glare) | A (2.4) | C (3.0) | A (2.1) | S (1.6) |
| Abrasion resistance | A (Grade 4) | A (Grade 4) | A (Grade 4) | A (Grade 4) | |
| PET: polyethylene terephthalate, IPA: isophthalic acid, PPT: polypropylene terephthalate |
[Table 1] (continued)
| Comparative example 4 | Example 2 | Example 3 | Example 4 | ||
| Polymer | Polymer 1 | IPA copolymerized PET | IPA copolymerized PET | IPA copolymerized PET | IPA copolymerized PET |
| Polymer 2 | PET | PET | PET | PET | |
| Difference in melting point (polymer 2) - (polymer 1) | 22°C | 22°C | 22°C | 22°C | |
| Melt viscosity ratio (polymer 1)/(polymer 2) | 1.1 | 1.1 | 1.1 | 1.1 | |
| Area ratio (polymer 1)/(polymer 2) | 50/50 | 50/50 | 50/50 | 50/50 | |
| Conjugate fiber | Cross-sectional shape | Flat | Flat | Flat and multilobal | Flat |
| Cross-sectional morphology | (a) of FIG. 1 | (b) of FIG. 1 | (c) of FIG. 1 | (a) of FIG. 1 | |
| Change in cross-sectional morphology for each composite fiber | No change | Changed (FIG. 4) | Changed (FIG. 4) | Changed (FIG. 4) | |
| Average value of flatness | 1.8 | 1.8 | 1.7 | 1.3 | |
| Difference between maximum value of flatness and minimum value of flatness | 0.5 | 0.1 | 0.1 | 0.1 | |
| Fiber diameter (µm) | 15 | 15 | 15 | 15 | |
| Coefficient of variation CV (%) of (distance between polymer gravity centers/fiber diameter) | 31 | 15 | 18 | 18 | |
| Crimp form | Crimp peak number (peak/cm) | 22 | 16 | 16 | 25 |
| Yarn production | Stability of yarn production (number of times of yarn breakage (times/ten million meters)) | C (3.5) | S (0.9) | A (1.8) | A (1.2) |
| Textile texture | Swelling feeling (appearance density (g/cm3)) | A (0.6) | A (0.8) | A (0.7) | B (0.9) |
| Feeling of resilience (bending recovery: 2HB × 10-2 (gf·cm/cm)) | A (1.0) | A (1.1) | A (1.0) | A (1.4) | |
| Smoothness 10-2) (friction variation × | C (0.7) | A (1.3) | S (1.6) | A (1.2) | |
| Textile function | Water-absorbing and quick-drying property (water diffusion time (min)) | A (20) | A (25) | S (15) | A (25) |
| Stretchability (elongation rate (%)) | S (22) | A (16) | A (16) | S (20) | |
| Textile quality | Appearance quality (degree of glare) | A (2.2) | A (2.4) | S (1.9) | A (2.2) |
| Abrasion resistance | A (Grade 4) | S (Grade 4.5) | A (Grade 3.5) | S (Grade 4.5) | |
| PET: polyethylene terephthalate, IPA: isophthalic acid, PPT: polypropylene terephthalate |
[Table 2]
| Comparative example 5 | Example 5 | Example 6 | Example 7 | ||
| Polymer | Polymer 1 | IPA copolymerized PET | IPA copolymerized PET | IPA copolymerized PET | IPA copolymerized PET |
| Polymer 2 | PET | PET | PET | PET | |
| Difference in melting point (polymer 2) - (polymer 1) | 22°C | 22°C | 22°C | 22°C | |
| Melt viscosity ratio (polymer 1)/(polymer 2) | 1.1 | 4.5 | 1.1 | 1.1 | |
| Area ratio (polymer 1)/(polymer 2) | 50/50 | 50/50 | 50/50 | 50/50 | |
| Conjugate fiber | Cross-sectional shape | Circular | Flat | Flat | Flat |
| Cross-sectional morphology | FIG. 3 | (a) of FIG. 1 | (a) of FIG. 1 | (a) of FIG. 1 | |
| Change in cross-sectional morphology for each composite fiber | No change | Changed (FIG. 4) | Changed (FIG. 4) | Changed (FIG. 4) | |
| Average value of flatness | 1.0 | 1.8 | 1.8 | 1.8 | |
| Difference between maximum value of flatness and minimum value of flatness | 0.0 | 0.1 | 0.1 | 0.1 | |
| Fiber diameter (µm) | 15 | 15 | 10 | 20 | |
| Coefficient of variation CV (%) of (distance between polymer gravity centers/fiber diameter) | 0 | 18 | 18 | 18 | |
| Crimp form | Crimp peak number (peak/cm) | 32 | 52 | 24 | 15 |
| Yarn production | Stability of yarn production (number of times of yarn breakage (times/ten million meters)) | S (0.7) | B (2.5) | A (1.7) | A (1.3) |
| Textile texture | Swelling feeling (appearance density (g/cm3)) | C (1.2) | S (0.5) | A (0.9) | A (0.7) |
| Feeling of resilience (bending recovery: 2HB × 10-2 (gf·cm/cm)) | C (2.6) | A (0.9) | A (1.4) | A (0.9) | |
| Smoothness (friction variation × 10-2) | C (0.2) | B (1.0) | A (1.2) | A (1.4) | |
| Textile function | Water-absorbing and quick-drying property (water diffusion time (min)) | C (35) | A (20) | A (20) | A (30) |
| Stretchability (elongation rate (%)) | S (24) | S (35) | A (14) | A (12) | |
| Textile quality | Appearance quality (degree of glare) | S (1.7) | A (2.2) | S (1.9) | B (2.6) |
| Abrasion resistance | S (Grade 4.5) | A (Grade 4) | A (Grade 3.5) | A (Grade 4) | |
| PET: polyethylene terephthalate, IPA: isophthalic acid, PPT: polypropylene terephthalate |
[Table 2] (continued)
| Example 8 | Example 9 | Example 10 | Example 11 | ||
| Polymer | Polymer 1 | IPA copolymerized PET | PPT | PBT | IPA copolymerized PET |
| Polymer 2 | TiO2-containing PET | PET | PET | PET | |
| Difference in melting point (polymer 2) - (polymer 1) | 22°C | 21°C | 21°C | 22°C | |
| Melt viscosity ratio (polymer 1)/(polymer 2) | 1.1 | 1.2 | 1.2 | 1.1 | |
| Area ratio (polymer 1)/(polymer 2) | 50/50 | 50/50 | 50/50 | 50/50 | |
| Conjugate fiber | Cross-sectional shape | Flat | Flat | Flat | Flat |
| Cross-sectional morphology | (a) of FIG. 1 | (a) of FIG. 1 | (a) of FIG. 1 | (a) of FIG. 1 | |
| Change in cross-sectional morphology for each composite fiber | Changed (FIG. 4) | Changed (FIG. 4) | Changed (FIG. 4) | Changed (FIG. 4) | |
| Average value of flatness | 1.8 | 1.8 | 1.8 | 1.8 | |
| Difference between maximum value of flatness and minimum value of flatness | 0.1 | 0.1 | 0.1 | 0.1 | |
| Fiber diameter (µm) | 15 | 12 | 12 | 15 | |
| Coefficient of variation CV (%) of (distance between polymer gravity centers/fiber diameter) | 18 | 17 | 18 | 16 | |
| Crimp form | Crimp peak number (peak/cm) | 18 | 33 | 38 | 16 |
| Yarn production | Stability of yarn production (number of times of yarn breakage (times/ten million meters)) | A (1.8) | A (1.9) | A (1.8) | A (1.8) |
| Textile texture | Swelling feeling (appearance density (g/cm3)) | A (0.8) | A (0.6) | A (0.7) | A (0.9) |
| Feeling of resilience (bending recovery: 2HB × 10-2 (gf·cm/cm)) | A (1.1) | B (2.0) | B (2.3) | A (1.0) | |
| Smoothness (friction variation × 10-2) | A (1.2) | B (1.1) | B (1.0) | A (1.2) | |
| Textile function | Water-absorbing and quick-drying property (water diffusion time (min)) | A (25) | A (20) | A (25) | A (30) |
| Stretchability (elongation rate (%)) | A (18) | S (27) | S (29) | A (12) | |
| Textile quality | Appearance quality (degree of glare) | S (1.8) | A (2.3) | A (2.4) | A (2.4) |
| Abrasion resistance | A (Grade 4) | B (Grade 2.5) | B (Grade 3) | A (Grade 4) | |
| PET: polyethylene terephthalate, IPA: isophthalic acid, PPT: polypropylene terephthalate |
[0171] Although the present invention has been described in detail with reference to specific embodiments, it is apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and the scope of the present invention. The present application is based on a Japanese patent application (No. 2021-122063) filed on July 27, 2021, and the contents thereof are incorporated herein by reference.
INDUSTRIAL APPLICABILITY
[0172] In the conjugate fiber bundle of the present embodiment, by precisely controlling the crimp form of each individual conjugate fiber constituting the conjugate fiber bundle, a difference is generated in voids between a portion where the crimp phases are aligned and a portion where the crimp phases are not aligned between adjacent conjugate fibers, complex voids and irregularities can be formed between the conjugate fibers, and a unique smooth tactile sensation can be developed.
[0173] Accordingly, by utilizing the conjugate fiber bundle of the present invention, a textile having excellent wearing comfortableness can be obtained in which a texture having appropriate feeling of resilience and swelling due to complex voids between the conjugate fibers is also realized. Therefore, the present invention can be suitably used for various fiber products including, in addition to general clothing such as jackets, skirts, pants, and underwear, and sports clothing and clothing materials, daily life applications such as interior products such as carpets and sofas, vehicle interior products such as car seats, cosmetics, cosmetic masks, and health products by utilizing the comfortableness of the conjugate fiber bundle.
REFERENCE SIGNS LIST
[0174]
x: low melting point polymer
y: high melting point polymer
a1, a2: two points at longest distance on outer periphery of fiber
b1, b2: intersection points of straight line passing through midpoint of straight line connecting two points at longest distance on outer periphery of fiber and orthogonal to the straight line and outer periphery of fiber
Gx: gravity center of low melting point polymer
Gy: gravity center of high melting point polymer
CF: conjugate fiber
Cr: peak of crimp
1: measuring plate
2: distribution plate
3: discharge plate
1. A conjugate fiber bundle formed of conjugate fibers, each of which comprises at least
two types of polymers having different melting points, wherein
a coefficient of variation CV of a value of (distance between polymer gravity centers/fiber diameter) between the conjugate fibers is 5% to 30%.
a coefficient of variation CV of a value of (distance between polymer gravity centers/fiber diameter) between the conjugate fibers is 5% to 30%.
2. The conjugate fiber bundle according to claim 1, wherein
a difference between a maximum value of flatness and a minimum value of flatness between the conjugate fibers is less than 0.5.
a difference between a maximum value of flatness and a minimum value of flatness between the conjugate fibers is less than 0.5.
3. The conjugate fiber bundle according to claim 1 or 2, wherein
an average value of flatness between the conjugate fibers is 1.2 to 3.0.
an average value of flatness between the conjugate fibers is 1.2 to 3.0.
4. The conjugate fiber bundle according to any one of claims 1 to 3, wherein
a surface layer of the conjugate fibers is covered with one type of polymer.
a surface layer of the conjugate fibers is covered with one type of polymer.
5. A fiber product partially comprising the conjugate fiber bundle according to any one
of claims 1 to 4.
REFERENCES CITED IN THE DESCRIPTION
This list of references cited by the applicant is for the reader's convenience only. It does not form part of the European patent document. Even though great care has been taken in compiling the references, errors or omissions cannot be excluded and the EPO disclaims all liability in this regard.
Patent documents cited in the description