Island-in-sea composite fiber and fiber product containing island-in-sea composite fiber

Abstract

A fiber is characterized by being an island-in-sea composite fiber in which a main constituent of a sea portion is an aromatic polyester, a moisture absorption and release parameter ΔMR is 2.0% or more, and a figure obtained by connecting a center of gravity of an island portion disposed at an outermost circumference in a fiber cross section with a line segment is a regular polygon having the center of gravity as a vertex. A polyester fiber is provided which can disperse stress generated along volume swelling of the fiber at the time of moisture absorption without causing cracking of a fiber surface, does not cause dyeing unevenness, fluff, and the like when a fabric or the like is produced, is excellent in quality, and does not decrease moisture absorption due to hot water treatment or the like.

Description

TECHNICAL FIELD

[0001] The present application relates to a polyester fiber having moisture absorption. BACKGROUND

[0002] Polyester fibers represented by polyethylene terephthalate are widely used in clothing applications, industrial applications, and the like, because of their excellent mechanical properties, chemical resistance, heat resistance, elastic force, characteristic stiffness, non-absorption of moisture, less change in wetting properties, non-crease, excellent dimensional stability, and the like. However, as described above, polyester fibers do not have moisture absorption, and have problems such as sweating and stickiness in a high-temperature and high-humidity environment in summer. Therefore, composite fibers are produced with a polymer having moisture absorption, and the polyester fibers are given moisture absorption.

[0003] For example, in Patent Literature 1, a sea-island composite fiber having moisture absorption is proposed in which polyethylene terephthalate is used as the sea part, and a polyether block amide copolymer is used as the island part.

[0004] In Patent Literature 2, a sea-island composite fiber is proposed in which a polymer having moisture absorption is used for the island part to impart moisture absorption to the fiber, and the thickness of the sea part present in the outermost layer of the cross section of the fiber is controlled to suppress cracking of the sea part during hot water treatment.

[0005] PRIOR ART DOCUMENTS

[0006] PATENT LITERATURE

[0007] Patent Literature 1: Japanese Patent Application Publication No. 2016-69770

[0008] Patent Literature 2: International Publication No. WO 2018 / 012318 SUMMARY

[0009] PROBLEMS TO BE SOLVED BY THE INVENTION

[0010] With the sea-island composite fiber disclosed in Patent Literature 1 and Patent Literature 2, regarding the arrangement of the island portions in the fiber cross section, although the thickness of the sea portion and the number of the island portions are specified, if the single fiber fineness is made fine in order to obtain the soft hand feeling required in clothing use, sometimes the stress generated accompanying the volume swelling of the polymer having moisture absorbability at the time of hot water treatment is not dispersed, and cracking such as cracking on the fiber surface occurs. In this case, there is a possibility that the quality of the fabric or the like is reduced due to the occurrence of dyeing unevenness, fluff or the like. Further, there is also a problem that the elution of the polymer having moisture absorbability also occurs through the surface cracking of the fiber, and the moisture absorbability is reduced. In addition, in the case of such a fiber, in the case where the fiber or a textile formed thereof is worn, there is also a possibility that the cracking on the fiber surface easily occurs, and there is a problem in the application to clothing such as a T-shirt or the like which is repeatedly washed, clothing such as sportswear or the like to which rubbing is repeatedly applied, and the like.

[0011] Therefore, the present application aims at solving the above problems, and by dispersing the stress generated accompanying the volume swelling of the fiber at the time of moisture absorption, the cracking on the fiber surface is greatly improved. Further, as a problem, to provide a polyester fiber which does not generate dyeing unevenness, fluff or the like when a fabric or the like is produced, and which is excellent in quality, and in which the moisture absorbability is not reduced by hot water treatment or the like.

[0012] Means for solving the problem

[0013] The present application aims at solving the above problems, and has the following configuration.

[0014] (1) A fiber characterized by being a sea-island composite fiber in which the main constituent of the sea portion is an aromatic polyester, the moisture regain parameter ΔMR is 2.0% or more, and a figure obtained by connecting the centers of gravity of the island portions arranged at the outermost periphery in the fiber cross section with line segments is a regular polygon having the centers of gravity as vertices.

[0015] (2) The fiber according to (1), characterized in that the number of the island portions arranged at the outermost periphery in the fiber cross section is odd.

[0016] (3) The fiber according to (1) or (2), characterized in that the ratio C / L of the radius of curvature C (μm) of the side of the outer periphery of the island portion arranged at the outermost periphery on the fiber surface side in the fiber cross section to the radius L (μm) of the circumscribed circle including the island portion arranged at the outermost periphery in the fiber cross section is 0.50 to 0.90.

[0017] (4) A fiber product containing the sea-island composite fiber according to any one of (1) to (3).

[0018] Effects of the invention

[0019] According to the present application, since stress dispersion accompanying volume swelling of the fiber at the time of moisture absorption is suppressed, cracking of the fiber surface is suppressed, and thus a polyester fiber having excellent quality, in which dyeing unevenness, fluff, and the like are not generated when a fabric is produced, is obtained. Further, since a decrease in moisture absorption does not occur, the polyester fiber has excellent moisture absorption, and is particularly suitable for use in clothing applications. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 (a), (b), (c) are schematic diagrams of cross-sectional structures of the polyester fiber of the present application.

[0021] Figure 2 (a), (b), (c), (d) are schematic diagrams of cross-sectional structures of the polyester fiber of the present application.

[0022] Figure 3 (a), (b), (c) are schematic diagrams of cross-sectional structures of the polyester fiber of the present application. DETAILED DESCRIPTION

[0023] The main component of the polyester fiber of the present application is an aromatic polyester. By making the main component an aromatic polyester, excellent mechanical properties and heat resistance are obtained, and thus a good tactile sensation such as elasticity, stiffness, and dryness is obtained. Further, the polyester fiber of the present application has excellent moisture absorption having a moisture absorption and desorption parameter ΔMR of 2.0% or more, and thus a fiber structure having excellent wearing comfort as a cool material is obtained.

[0024] A fiber having moisture absorption incorporates water molecules by physical adsorption of water molecules to the fiber and / or formation of interactions between functional groups in the molecular structure of the components constituting the fiber and water molecules. In particular, in the case of having high moisture absorption, water molecules are incorporated into the fiber, and thus volume swelling of the fiber occurs. However, since an aromatic polyester has a rigid aromatic ring in the polymer structure, it is not easily deformed, and stress generated at the time of volume swelling due to moisture absorption is not dispersed, and sometimes cracks and the like occur on the fiber surface.

[0025] Therefore, for the polyester fiber of the present application, which suppresses cracking of the fiber surface due to volume swelling at the time of moisture absorption, it is important that a figure obtained by connecting the centers of gravity of components disposed at the outermost periphery among components disposed inside the fiber in the cross section of the fiber with line segments is a regular polygon having the centers of gravity as vertices.

[0026] The cross-sectional shape of the fiber having a component disposed inside the fiber in the fiber cross section is an island-in-sea composite fiber composed of two or more polymers, and the component disposed inside the fiber is an island. The figure obtained by connecting the centers of gravity of the components disposed at the outermost periphery among the components disposed inside the fiber in the fiber cross section, i.e., the centers of gravity of the islands disposed at the outermost periphery in the fiber cross section with line segments is drawn in such a manner that the centers of gravity are selected so as not to cross each other except at the centers of gravity, as shown in Figure 1 (a). On the other hand, if the centers of gravity of the islands are connected with line segments as shown in Figure 1 (b), the line segments cross each other at portions other than the centers of gravity of the islands, and the figure drawn at this time is not included in the figure obtained by connecting the centers of gravity of the islands disposed at the outermost periphery in the fiber cross section with line segments. Further, as shown in Figure 1 (c), since other islands (2a, 2b, 2c, 2d, 2e) are disposed between the island 2f and the fiber surface, the island 2f is not included in the islands disposed at the outermost periphery in the fiber cross section.

[0027] The definition of the regular polygon, which is the arrangement of the island component characteristic of the present application, is described.

[0028] With respect to the figure obtained by connecting the centers of gravity of the islands disposed at the outermost periphery in the fiber cross section with line segments, the figure composed of n line segments is set as an n-gon, and the lengths of the line segments are set as Al, A2, A3,..., An. The average value of the lengths of the line segments is set as Lx, and the ratios of the lengths of the line segments to the average value Lx (Al / Lx, A2 / Lx, A3 / Lx,..., An / Lx) are rounded off at the third digit after the decimal point, and when all of them are 0.97 to 1.03, it means that the figure obtained by connecting the centers of gravity of the islands disposed at the outermost periphery in the fiber cross section with line segments is a regular n-gon.

[0029] The polyester fiber of the present application is such that the figure obtained by connecting the centers of gravity of the island portions disposed at the outermost periphery in the fiber cross section with line segments is a regular polygon with the centers of gravity as vertices, whereby the vectors of the stress generated upon volume swelling caused by moisture absorption become positive and opposite between adjacent island portions, the stress between the island portions canceling each other, and thus the stress propagated to the sea portion on the fiber surface side can be reduced. Since the stress propagated to the sea portion on the fiber surface side is reduced, the fiber surface is less likely to crack, and uneven dyeing, generation of fluff, and the like can be suppressed. On the other hand, in the case where the figure obtained by connecting the centers of gravity of the island portions disposed at the outermost periphery in the fiber cross section with line segments is not a regular polygon with the centers of gravity as vertices, the stress generated upon volume swelling upon moisture absorption is less likely to be dispersed, and a point of stress concentration is likely to occur at the interface between the island portion and the sea portion. Thus, cracking of the fiber surface, uneven dyeing, generation of fluff, and the like are likely to occur, and the quality of a woven fabric or a knitted fabric produced therefrom is likely to be reduced.

[0030] As described above, the polyester fiber of the present application is such that the island components disposed at the outermost periphery are disposed as a regular polygon, thereby greatly improving the problems in the conventional composite fiber having moisture-absorbing components, but it is preferable that the number of the island portions disposed at the outermost periphery in the fiber cross section be odd.

[0031] By making the number of the island portions disposed at the outermost periphery odd, the stress generated upon volume swelling caused by moisture absorption is suppressed from being linearly concentrated, and the stress can be dispersed, and cracking of the fiber surface can be suppressed. Thus, uneven dyeing, generation of fluff, and the like due to cracking of the fiber surface can be suppressed, and a superior quality can be obtained when a fabric is produced therefrom. It is more preferable that the number of the island portions disposed at the outermost periphery in the fiber cross section be odd and be 9 or less, and it is further preferable that the number of the island portions be odd and be 5 or less, and the minimum number of the island portions be 3.

[0032] It is preferable that the total number of the island portions in the fiber cross section of the polyester fiber of the present application be 15 or less. By making the total number of the island portions in this range, the stress generated upon volume swelling caused by moisture absorption is suppressed from being linearly concentrated, and the stress can be dispersed, and cracking of the fiber surface can be suppressed. Thus, uneven dyeing, generation of fluff, and the like due to cracking of the fiber surface can be suppressed, and a superior quality can be obtained when a fabric is produced therefrom. It is more preferable that the total number of the island portions in the fiber cross section be 10 or less, and it is further preferable that the total number of the island portions be 6 or less, and the minimum number of the island portions be 3.

[0033] It is preferable that the ratio C / L of the radius of curvature C (μm) of the edge on the fiber surface side of the outer periphery of the island portion disposed at the outermost periphery in the fiber cross section to the radius L (μm) of the circumscribed circle including the island portion disposed at the outermost periphery in the fiber cross section be 0.50 to 0.90 in the polyester fiber of the present application. Here, the circumscribed circle including the island portion disposed at the outermost periphery in the fiber cross section means Figure 2The radius of the circle 4 of (b) is L. Further, the radius of curvature C of the edge on the fiber surface side of the outer periphery of the island portion disposed at the outermost periphery in the fiber cross section is obtained by the method described in the examples Figure 2 The radius of the circle 5 of (c).

[0034] C / L indicates the sharpness of the bend of the edge on the fiber surface side of the outer periphery of the island portion disposed at the outermost periphery in the fiber cross section with respect to the fiber surface. If C / L is 0.50 or more, the stress generated by the volume swelling at the time of moisture absorption is evenly applied to the sea portion and dispersed, and the fiber surface is less likely to crack. More preferably, it is 0.55 or more, and further preferably, it is 0.60 or more. Further, if C / L is 0.90 or less, the bend of the portion of the edge on the fiber surface side of the outer periphery of the island portion disposed at the outermost periphery in the fiber cross section does not become large, and further, an angle is not formed, and thus the stress generated by the volume swelling at the time of moisture absorption is not concentrated in these portions, and the fiber surface is less likely to crack. More preferably, it is 0.85 or less, and further preferably, it is 0.80 or less. Note that C / L of 1.0 indicates that the bend of the edge on the fiber surface side of the outer periphery of the island portion disposed at the outer periphery is the same as the fiber surface, and as a specific example of the fiber cross section in this case, a core-sheath composite fiber in which the island portion is one can be given.

[0035] The ratio L / R of the radius L (μm) of the circumscribed circle including all the island portions disposed at the outermost periphery in the fiber cross section to the fiber radius R (μm) in the polyester fiber of the present application is preferably 0.50 to 0.90.

[0036] L / R indicates the thickness of the sea portion between the fiber surface and the island portion disposed at the outermost periphery in the fiber cross section. If L / R is 0.90 or less, the thickness of the sea portion is sufficiently ensured with respect to the fiber diameter, and thus cracking of the sea portion due to stress occurring by volume swelling at the time of moisture absorption can be suppressed, and uneven dyeing, generation of fluff due to cracking of the fiber surface resulting from cracking of the sea portion can be suppressed, and excellent quality when made into a fabric is obtained. If based on this idea, more preferably, it is 0.80 or less, and further preferably, it is 0.60 or less. Further, if L / R is 0.50 or more, the rigidity due to the thickness of the aromatic polyester disposed in the sea portion can be reduced, and the stress generated by volume swelling at the time of moisture absorption can be reduced.

[0037] The ratio S / L of the minimum distance S (μm) between the island portions in the fiber cross section to the radius L (μm) of the circumscribed circle including all the island portions disposed at the outermost periphery in the fiber cross section in the polyester fiber of the present application is preferably 0.05 to 0.50. Here, the minimum distance between the island portions in the fiber cross section is obtained by the method described in the examples Figure 2 The line segment 7 of (d).

[0038] Here, the minimum distance between the island portions in the fiber cross section is the thickness of the sea portion sandwiched by the two adjacent island portions. If S / L is 0.05 or more, the stress relaxation by the sea portion between the island portions can reduce the propagation of stress to the sea portion, and the cracking of the fiber surface caused by the stress generated by the volume swelling upon moisture absorption can be suppressed. More preferably, S / L is 0.10 or more, and further preferably 0.15 or more. In addition, if S / L is 0.50 or less, the distance between the island portions is not far, and thus the stress relaxation effect by the sea portion between the island portions can reduce the propagation of stress to the sea portion on the fiber surface side, and the cracking of the fiber surface can be suppressed. Based on this idea, more preferably, S / L is 0.40 or less, and further preferably 0.30 or less.

[0039] The polyester fiber of the present application preferably has a minimum thickness of the sea portion of 0.3 μm or more.

[0040] Here, the minimum thickness of the sea portion is the minimum distance among the distances between the intersection of the outer periphery of the island portion and a straight line, and the intersection of the fiber surface and the straight line, when a straight line is drawn from the center of gravity of an arbitrary island portion in the fiber cross section toward an arbitrary fiber surface, and is Figure 2 (c) the segment 6. If the minimum thickness of the sea portion is 0.3 μm or more, the cracking of the sea portion caused by the stress generated by the volume swelling upon moisture absorption can be suppressed, and the uneven dyeing, the generation of fluff caused by the cracking of the fiber surface due to the cracking of the sea portion can be suppressed, and a superior quality can be obtained when a fabric is produced. More preferably, the minimum thickness of the sea portion is 1.0 μm or more, and further preferably 2.5 μm or more.

[0041] The sea portion / island portion complex ratio of the polyester fiber of the present application is preferably 50 / 50 to 90 / 10 by weight. If the complex ratio of the sea portion is 50% by weight or more, the mechanical properties, the heat resistance, the elasticity, the stiffness, the dry feel, and the wearing comfort of the fiber structure are excellent due to the aromatic polyester of the sea portion. In addition, the cracking of the sea portion caused by the stress generated by the volume swelling upon moisture absorption can be suppressed, and the uneven dyeing, the generation of fluff caused by the cracking of the fiber surface due to the cracking of the sea portion can be suppressed, and a superior quality can be obtained when a fabric is produced. More preferably, the complex ratio of the sea portion is 60% by weight or more, and further preferably 70% by weight or more. On the other hand, if the complex ratio of the sea portion of the polyester fiber is 90% by weight or less, that is, the complex ratio of the island portion is 10% by weight or more, the rigidity caused by the thickness of the aromatic polyester disposed in the sea portion can be reduced, and the stress generated by the volume swelling upon moisture absorption can be reduced. Based on this idea, more preferably, the complex ratio of the sea portion is 85% by weight or less, and further preferably 80% by weight or less.

[0042] The moisture absorption and desorption parameter ΔMR of the polyester fiber of the present application, which is an index of moisture absorption, is 2.0% or more. ΔMR is the difference between the moisture absorption rate of the fiber at high temperature and high humidity represented by 30°C x 90% RH and the moisture absorption rate at the standard temperature and humidity represented by 20°C x 65% RH, and the higher ΔMR is, the higher the moisture absorption of the fiber is. If ΔMR is 2.0% or more, the feeling of stuffiness in clothes is less, and the wearing comfort is exhibited. More preferably, ΔMR is in the range of 2.5% or more, further preferably in the range of 3.0% or more, and particularly preferably in the range of 4.0% or more. There is no particular upper limit to the range of ΔMR, but the level that can be achieved in the present application is about 10%, which becomes a practical upper limit. Furthermore, the polyester fiber of the present application satisfies the above range of ΔMR before and after hot water treatment such as dyeing.

[0043] The so-called aromatic polyester, which is the main component of the polyester fiber of the present application, is a polymer formed from the combination of aromatic dicarboxylic acid and aliphatic diol, aliphatic dicarboxylic acid and aromatic diol, or aromatic dicarboxylic acid and aromatic diol. In general, from the viewpoint of mechanical properties, heat resistance, and workability at the time of production, it is preferable to use an aromatic polyester formed from the combination of aromatic dicarboxylic acid and aliphatic diol.

[0044] As specific examples of the aromatic dicarboxylic acid, terephthalic acid, isophthalic acid, phthalic acid, sodium 5-sulfonate isophthalic acid, lithium 5-sulfonate isophthalic acid, 5-sulfonate isophthalic acid (tetraalkyl) phosphonium, 4,4'-biphenyldicarboxylic acid, 2,6-naphthalene dicarboxylic acid, and the like can be given, but are not limited thereto. 4,4'-biphenyldicarboxylic acid, 2,6-naphthalene dicarboxylic acid, and the like can be given, but are not limited thereto.

[0045] As specific examples of the aliphatic diol, ethylene glycol, 1,3-propanediol, 1,4-butanediol, hexanediol, cyclohexanediol, diethylene glycol, 1,6-hexanediol, neopentyl glycol, and the like can be given, but are not limited thereto.

[0046] The method of producing the aromatic polyester in the present application is not limited, and if the raw material at the time of production is set as a monomer, the monomer can be synthesized by a general polycondensation reaction, polyaddition reaction, or the like to produce it. As the monomer, monomers derived from petroleum, monomers derived from biomass, a mixture of monomers derived from petroleum and monomers derived from biomass, and the like are not limited.

[0047] Furthermore, in the aromatic polyester in the present application, a second component and a third component can be copolymerized or mixed in addition to the main component, within a range that does not exceed the object of the present application. Since the main constituent component is an aromatic polyester, the copolymerization amount is 10 mol% or less, based on the amount of the monomer of the copolymerization component with respect to the total amount of the monomers.

[0048] The main component of the polyester fiber of the present application is an aromatic polyester as described above. However, in general, aromatic polyesters do not have a functional group or the like that forms a strong interaction with water molecules in the polymer structure. Therefore, as examples of methods for making the ΔMR of the polyester fiber of the present application fall within the above range, there are, for example, the addition of a hygroscopic compound, the provision of a polymer having high hygroscopicity (hereinafter, also referred to as a hygroscopic polymer), the generation of a hygroscopic functional group by treating the polymer molecules on the surface of the fiber with ozone or the like, and the like. Among these, if a polyester fiber having excellent hygroscopicity is to be obtained, it is preferable to provide a hygroscopic polymer in the island portion.

[0049] As examples of hygroscopic polymers that are suitable for provision in the island portion of the polyester fiber of the present application, there are, for example, polyether esters, polyether amides, polyether ester amides, polyamides, thermoplastic cellulose derivatives, polyvinylpyrrolidones, and the like. Among these, polyether esters, polyether amides, and polyether ester amides that contain a polyether as a copolymer component are excellent in stability during melt molding, and are high in hygroscopicity as a target, and are more preferably used in the polyester fiber of the present application. Further, polyether esters are excellent in affinity with the aromatic polyester of the sea portion, and are also excellent in heat resistance of the hygroscopic polymer, and thus have the effect that the mechanical properties of the resulting sea-island composite fiber become good, and the like, and are particularly preferably used in the present application. Furthermore, it is more preferable that the polyether ester be formed of polybutylene terephthalate and a polyether, because the dissolution of the hygroscopic polymer into hot water can be inhibited, and the crystallinity is excellent.

[0050] The hygroscopic polymer described above has high affinity with water, and is easily dissolved if it comes into contact with water or hot water during dyeing. If cracking of the surface of the fiber occurs due to stress generated by volume swelling during hygroscopicity, the hygroscopic polymer of the island portion is sometimes dissolved to the outside of the fiber by contact with hot water, and the hygroscopicity of the fiber decreases. Therefore, in the case where a hygroscopic polymer is provided in the island portion, the effect of inhibiting cracking of the surface of the fiber that is brought about by the composite cross-sectional shape of the polyester fiber of the present application is significantly exerted, and a polyester fiber having excellent hygroscopicity is obtained.

[0051] In the hygroscopic polymer of the present application, a second component and a third component can be copolymerized or mixed in addition to the main component, within a range that does not exceed the object of the present application, and the copolymerization amount is 10 mol% or less, based on the amount of the monomer of the copolymer component with respect to the total amount of the monomers.

[0052] The cross-sectional shape of the polyester fiber of the present application can adopt not only a circular cross-section, but also a variety of cross-sectional shapes such as flat, Y-shaped, T-shaped, hollow, and the like.

[0053] The polyester fiber of the present application can be in any form such as long fiber (filament), short fiber (spun fiber), etc. In the case of long fiber, it can be a single filament composed of one filament or a multifilament composed of a plurality of filaments. In the case of short fiber, there is no limitation on the cutting length or the number of crimps.

[0054] The total denier of the polyester fiber of the present application is appropriately set according to the use, and if it is a long fiber for clothing, it is preferably 8 dtex or more and 150 dtex or less in practical use. Further, the strength is preferably 1.5 cN / dtex or more as a clothing use, but by coping with the use in combination with other fibers at the time of making cloth, etc., it can be used without problems even if it is 1.5 cN / dtex or less. The elongation is appropriately set according to the use, but from the viewpoint of the processability at the time of processing into cloth, it is preferably 25% or more and 60% or less.

[0055] The polyester fiber of the present application is preferably a single fiber denier of 6.0 dtex or less. By being in such a range, the rigidity caused by the thickness of the aromatic polyester disposed in the sea portion can be reduced, and further, a fiber structure having excellent mechanical properties, heat resistance, elasticity, stiffness, dryness, and wearing comfort can be obtained. Further, the cracking of the sea portion caused by the stress generated by the volume swelling at the time of moisture absorption can be suppressed, and the generation of dyeing unevenness and hairiness caused by the cracking of the fiber surface due to the cracking of the sea portion can be suppressed, and an excellent quality can be obtained when made into a fabric. More preferably, the single fiber denier is 4.0 dtex or less, and further preferably 2.0 dtex or less.

[0056] The polyester fiber of the present application can be obtained by a publicly known melt spinning or composite spinning method, and if exemplified, it is as described below. However, the spinning method and the composite method are not limited to the methods exemplified here.

[0057] As a method of producing the polyester fiber of the present application formed of two or more kinds of polymers, it can also be produced by a melt spinning method, a solution spinning method such as a wet method and a dry-wet method, a melt-blowing method and a spun-bonding method, etc. which are aimed at the production of long fiber, but from the viewpoint of improving productivity, the melt spinning method is suitable. Further, in the melt spinning method, it is suitable to use a composite die described later. In the case of using the melt spinning method, the spinning temperature at that time is a temperature at which the main high-melting point, high-viscosity polymer among the polymers used shows fluidity. As this temperature at which fluidity is shown, it differs depending on the molecular weight, but if it is set between the melting point of the polymer and the melting point + 60°C, it can be stably produced.

[0058] As a manufacturing method employing melt spinning, examples include melting polymers from the sea and island regions separately, metering / transporting them using a gear pump, directly forming a composite stream with a specific composite structure using conventional methods, and discharging it from the spinneret. The filaments are then cooled to room temperature by jetting cooling air through a filament cooling device such as a chimney, supplied with oil and bundled using an oil supply device, interlaced using a fluid interlacing nozzle device, and passed through traction rollers and stretch rollers, being stretched according to the ratio of the circumferential speeds of the traction rollers and stretch rollers. Further, the filaments are heat-set by passing them through stretch rollers and then wound using a winding machine (winding device). Alternatively, a two-step method can be used, where the circumferential speeds of the traction rollers and stretch rollers are made the same, and then the filaments are wound using a winding machine at the same speed to produce unstretched filaments in one step, followed by stretching in a separate process.

[0059] In the polyester fiber of the present invention, by making the melt viscosity ratio of the two or more polymers used in the sea area and the island area less than 5.0, a composite polymer flow can be stably formed, and a fiber with a good composite cross section can be obtained, which is therefore preferred.

[0060] As the composite die used in manufacturing the polyester fiber of the present invention, the composite die described in Japanese Patent Application Publication No. 2011-208313 is preferably used. This application's... Figure 3 The composite die shown is incorporated into the spinning assembly in a configuration consisting of approximately three components stacked from top to bottom: a metering plate 8, a distribution plate 9, and a discharge plate 10, and is used for spinning. Incidentally... Figure 3 This example uses two polymers, polymer A and polymer B. For conventional composite dies, as described above, it is difficult to control the shape of the island portion; therefore, it is preferable to use... Figure 3 The example illustrates a composite die that utilizes a micro-flow path.

[0061] for Figure 3 The illustrated die component has a metering plate 8 that measures the amount of polymer flowing into each discharge hole and each distribution hole, a distribution plate 9 that controls the composite cross-section and its shape in the cross-section of the single fiber, and a discharge plate 10 that compresses the composite polymer flow formed by the distribution plate 9 to discharge it.

[0062] To avoid the complicated explanation of the composite die, although not shown, as to the member laminated above compared with the metering plate 8, a member which forms a flow path in combination with the spinning machine and the spinning assembly can be used. By designing the metering plate 8 in combination with the existing flow path member, the existing spinning assembly and its members can be directly and effectively utilized, so that the spinning machine need not be specialized for this die. Further, a plurality of flow path plates can be laminated between the flow path-metering plate 8 or between the metering plate 8-distribution plate 9. Thereby, a flow path which is efficiently set to transfer the polymer in the direction of the cross section of the die and the cross section of the single fiber can be introduced to the constitution of the distribution plate 9. The composite polymer flow discharged from the discharge plate 10 is cooled and solidified according to the above production method, is applied with an oil agent, is drawn by a roller to become a predetermined peripheral velocity, and thereby a fiber having a desired composite cross section is obtained.

[0063] The polyester fiber of the present application can be subjected to false twisting, twisting, etc. as post-processing, and can be treated in the same manner as general fibers as to weaving and knitting.

[0064] The polyester fiber and / or the post-processed yarn of the present application can be made into a fiber structure such as a woven fabric, a knitted fabric, a terry fabric, a nonwoven fabric, a staple yarn, batting, etc. in accordance with a known method. Further, the fiber structure composed of the polyester fiber and / or the post-processed yarn of the present application can be any woven or knitted structure, and can be appropriately used in a plain weave, a twill weave, a satin weave, or a variation thereof, a warp knitting, a weft knitting, a circular knitting, a lace mesh weave, or a variation thereof, etc.

[0065] The polyester fiber of the present application can be combined with other fibers by interweaving, interknitting, etc. when made into a fiber structure, or can be made into a fiber structure after being made into a blended yarn with other fibers.

[0066] The fiber structure composed of the polyester fiber and / or the post-processed yarn of the present application is excellent in moisture absorption, and thus can be appropriately used in applications requiring comfort and quality. Examples include general clothing applications, sportswear applications, bedding applications, interior applications, material applications, etc., but are not limited to these.

[0067] Examples

[0068] The present application is explained in detail using examples, but the present application is not limited to these examples. Note that each property value in the examples is measured using the following method.

[0069] A. Melt viscosity of polymer

[0070] As for the polymer sample whose moisture content was made to be 300 ppm or less by a vacuum drier, using an Orientec Corporation Capillograph, the sample was put in a heating furnace set at the same temperature as the spinning temperature, melted under a nitrogen atmosphere, and the viscosity was measured by extruding the sample from a capillary at the front end of the heating furnace while changing the strain rate in stages. Note that the measurement was started after the sample was left in the heating furnace for 5 minutes, and the value of the shear rate at 1216 seconds -1 was set as the melt viscosity of the polymer.

[0071] B. Melting point (Tm) of the polymer

[0072] Using a differential scanning calorimeter (DSC) Q2000 manufactured by TA instruments, a polymer sample of 20 mg was warmed at a rate of 20°C / min from 20°C to 300°C, kept at 300°C for 5 minutes, then cooled at a rate of 20°C / min from 300°C to 20°C, kept at 20°C for 1 minute, and further warmed at a rate of 20°C / min from 20°C to 280°C, and the peak top temperature of the endothermic peak observed at this time was set as the melting point. Note that in the case where multiple endothermic peaks were observed, the endothermic peak top on the highest temperature side was set as the melting point.

[0073] C. Total fineness

[0074] A fiber sample was wound 200 times using a length measuring machine with a frame circumference of 1.125 m to make a skein, dried using a hot air drier (105 ± 2°C x 60 minutes), and the total fineness was calculated from the value obtained by weighing the skein using a balance and multiplying by the standard moisture regain. The measurement was performed 4 times, and the average value was set as the total fineness.

[0075] D. Tensile strength and elongation

[0076] For a fiber sample, using "TENSILON" (registered trademark) UCT-100 manufactured by Orientec Corporation as a measuring device, the measurement was performed under the constant rate of elongation conditions shown in the chemical fiber filament yarn test method (JIS L1013 (2010)). The elongation was calculated from the elongation of the point showing the maximum strength in the tensile strength-elongation curve. In addition, the tensile strength was set as the value obtained by dividing the maximum strength by the total fineness. The measurement was performed 10 times, and the average value was set as the tensile strength and the elongation.

[0077] E. Boiling water shrinkage

[0078] A fiber sample was wound 20 times with a frame perimeter of 1.125 m to make a skein, and the initial length L0was determined under a load of 0.09 cN / dtex. Next, after being treated in boiling water for 30 minutes under no load, it was air-dried. Then, the length L1after the treatment was determined under a load of 0.09 cN / dtex, and ΔMR was calculated from the formula (1).

[0079] Boiling water shrinkage (%) = [(L0- L1) / L0] x 100 (1)

[0080] F. ΔMR before hot water treatment

[0081] A fiber sample or cloth sample of about 1 to 2 g was weighed into a weighing bottle, and the mass was determined after drying at 110°C for 2 hours, and this mass was set as w0. Next, the mass was determined after the dried fiber sample was kept at a temperature of 20°C and a relative humidity of 65% for 24 hours, and this mass was set as w 65％ . Next, the temperature was adjusted to 30°C and the relative humidity to 90%, and the mass was determined after the fiber sample was kept for 24 hours, and this mass was set as w 90％ .

[0082] MR1= [(w 65％ - w0) / w0] x 100 (2)

[0083] MR2= [(w 90％ - w0) / w0] x 100 (3)

[0084] ΔMR = MR2- MR1 (4)

[0085] At this time, the values calculated using the formulas (2) to (4) were set as ΔMR.

[0086] G. ΔMR after hot water treatment

[0087] The fiber samples were used to create a tubular knitted fabric using an Eiko Sangyo NCR-BL circular knitting machine (3.5 inches (8.9 cm) cylinder diameter, gauge 27) with a loop density of 50. When the fiber's total fineness was less than 80 dtex, the yarn was appropriately combined to achieve a total fineness of 80-160 dtex when fed to the circular knitting machine. When the total fineness exceeded 80 dtex, the yarn was fed to the circular knitting machine one strand at a time, and the same method was used to create the fabric with a loop density of 50. Next, the resulting tubular knitted fabric was placed in an aqueous solution containing 1 g / L sodium carbonate and Nichika Chemicals' surfactant Sunmore BK-80. The aqueous solution was heated to 80°C and treated for 20 minutes, followed by drying in a hot air dryer at 60°C for 60 minutes. Furthermore, the dried tubular knitted fabric was subjected to hot water treatment at a liquor ratio of 1:100, a treatment temperature of 130°C, and a treatment time of 60 minutes, followed by drying in a hot air dryer at 60°C for 60 minutes, thus obtaining a hot water-treated tubular knitted fabric. Regarding the obtained hot water-treated tubular knitted fabric, ΔMR was calculated according to the description in section F.

[0088] H. Radius of curvature C

[0089] The fiber sample was embedded using an embedding agent such as epoxy resin. The cross-section of the fiber, perpendicular to the fiber axis, was imaged using a HITACHI scanning electron microscope (SEM) at a magnification that allowed observation of more than 10 individual fibers. The obtained images were analyzed using the computer software WinROOF (manufactured by Mitani Shoji), thereby determining the radius of curvature C of the edge on the outer periphery of the fiber surface in the cross-section of the fiber, specifically the island located at the outermost periphery.

[0090] When determining the radius of curvature, first refer to Figure 2 (c) Draw a straight line from the center of gravity G of the island to any fiber surface. Measure the length of line segment BF formed by the intersection point B of the island's outer perimeter and the straight line, and the intersection point F of the fiber surface and the straight line, up to two decimal places. Find the intersection point B where the length of line segment BF is minimized. Find the radius of the circle that is connected to and circumscribed by the island at intersection point B, up to three decimal places. Perform this operation on all islands contained in a single fiber, and further perform this operation on three randomly selected single fibers. Calculate the average of the obtained radii, rounding to the third decimal place, and set the resulting value as the radius of curvature C (μm).

[0091] I. Radius L of the circumcircle

[0092] An image of the fiber cross section was taken with SEM as in the case of H, and the image taken using WinROOF was analyzed to measure the radius of the circumscribed circle of the entire island portion disposed at the outermost periphery in the fiber cross section to the third decimal place. This operation was performed on 10 single fibers randomly sampled, and the simple number average of the results obtained was calculated. The value obtained by rounding off the third decimal place was set as the radius L (μm) of the circumscribed circle.

[0093] J. Fiber radius R

[0094] An image of the fiber cross section was taken with SEM as in the case of H, and the radius of the single fiber randomly sampled from each image taken within the same image was measured to the third decimal place in units of μm. This operation was performed on 10 single fibers randomly sampled, and the simple number average of the results obtained was calculated. The value obtained by rounding off the third decimal place was set as the fiber radius R (μm). Here, in the case where the fiber cross section in the direction perpendicular to the fiber axis is not a perfect circle, the value calculated by conversion to a circle was used.

[0095] K. Minimum distance S between islands

[0096] An image of the fiber cross section was taken with SEM as in the case of H, and the image taken using WinROOF was analyzed to calculate the minimum distance S between islands in the fiber cross section.

[0097] In calculating the minimum distance between islands, reference was made to Figure 2 (d), in two adjacent islands 2a and 2b, a straight line was drawn from the center of gravity Ga of the island 2a to the island 2b, and the intersection with the periphery of each island was set as Da and Db. The minimum value of the length of this line segment Da-Db was measured to the third decimal place. This operation was performed on 10 adjacent two islands randomly sampled from the islands included in one single fiber. Note that in the case where the number of line segments Da-Db formed between two adjacent islands is less than 10, the minimum value of the line segment Da-Db was measured among all the islands included in one single fiber. Further, this operation was performed on 3 single fibers randomly sampled, and the average of the lengths of the line segments Da-Db obtained was calculated. The value obtained by rounding off the third decimal place was set as the minimum distance S (μm) between islands.

[0098] L. Minimum thickness of sea portion

[0099] The minimum thickness of the sea portion was calculated as in the case of the length of the line segment BF described in H, with reference to Figure 2(c), a straight line is drawn from the center of gravity Ga of the island portion toward an arbitrary fiber surface, the length of the line segment BF constituted by the intersection point B of the outer periphery of the island portion and the straight line and the intersection point F of the fiber surface and the straight line is measured up to the second decimal place, and the intersection point B at which the length of the line segment BF becomes the minimum value is found. This measurement is performed on all island portions included in one single fiber, and further, on three single fibers randomly selected, and the average of the lengths of the line segments BF obtained is found, and the value obtained by rounding off the second decimal place is set as the minimum thickness of the sea portion (μm).

[0100] M. Number of cracks in the sea portion

[0101] A platinum-palladium alloy evaporation for a tubular knitted fabric after hot water treatment was produced by the method described in item G, and observed at 1000 times using a scanning electron microscope (SEM) S-4000 type manufactured by Hitachi, Ltd., and the microscope photographs of 10 fields of view were randomly taken. In the 10 photographs obtained, the fiber surface constituting the tubular knitted fabric was observed, and the positions of the cracks in the sea portion were counted. If the number of cracks in the sea portion was 10 or less, it was set as acceptable.

[0102] N. Dyeing unevenness

[0103] A tubular knitted fabric was produced by the method described in item G, and after the tubular knitted fabric was put into an aqueous solution containing sodium carbonate 1 g / L and a surfactant Sanmol BK-80 manufactured by Nikko Chemicals Co., Ltd., the aqueous solution was warmed to 80°C and treated for 20 minutes, and then dried in a hot air dryer at 60°C for 60 minutes. Next, dry heat setting was performed at 160°C for 2 minutes, and the tubular knitted fabric after dry heat setting was put into a dyeing solution in which Kayalon Polyester Blue UT-YA manufactured by Nippon Kayaku Co., Ltd. was added as a disperse dye at 1.3% by weight and the pH was adjusted to 5.0, or a dyeing solution in which Kayacryl Blue 2RL-ED manufactured by Nippon Kayaku Co., Ltd. was added as a cationic dye at 1.0% by weight and the pH was adjusted to 4.0, and dyed under the conditions of a bath ratio of 1 : 100, a dyeing temperature of 130°C, and a dyeing time of 60 minutes.

[0104] The tubular knitted fabric after dyeing was used as a test sample, and the L value was measured three times for each 1 test sample using a spectrophotometer CM-3700d type manufactured by Minolta Co., Ltd. with a D65 light source, a field angle of 10°, and the optical condition set to SCE (specular component excluded), and the average value was rounded off at the second decimal place to obtain the L value of the test sample. This operation was performed on 10 test samples randomly selected, and the variation rate was found from the average value and the standard deviation of the L values of the 10 test samples. In the case where the variation rate of the L values of the 10 test samples was 5.0% or less, it was judged that there was no dyeing unevenness.

[0105] O. Number of fluffs

[0106] Using a multi-point fluff counting device (MFC-120 manufactured by Toray Engineering Co., Ltd.), a fiber sample was moved at 600 m / min, 10,000 m was measured, and the number of fluffs displayed on the device was counted. Note that a beaming reed (stainless steel, reed interval 1 mm) was disposed near the measurement point, and the fiber was passed therethrough. This measurement was repeated 10 times, and the average value in 10,000 m was set as the number of fluffs, and if the number of fluffs was 10 or less per 10,000 m, it was set as acceptable.

[0107] P. Water absorption and quick drying property

[0108] The mass of the tube knitted fabric produced by the method described in item G and subjected to hot water treatment was measured after being kept at a temperature of 20°C and a relative humidity of 65% for 24 hours, and this mass was set as w a . Next, the mass of the sample was measured after 0.3 ml of water was added to the center of the sample, and this mass was set as w 0分钟 . The instant when water was added to the sample was set as 0 minutes, and the mass of the sample was measured at 5-minute intervals, and this mass was set as w n分钟 . Here, n minutes indicates an arbitrary time at which the mass of the sample was measured, and indicates a time at 5-minute, 10-minute, 15-minute, and 5-minute intervals. The water retention rate WR at the arbitrary time was calculated using equation (5).

[0109] WR = [(w 0分钟 - w n分钟 ) / (w 0分钟 - w a )] x 100 (5)

[0110] In the case where the water retention rate WR calculated from equation (5) is 30% or less at 60 minutes or less, it was set as having a water absorption and quick drying property.

[0111] Q. Maintenance of moisture absorption property before and after hot water treatment

[0112] The change in the moisture absorption property of the fiber before and after hot water treatment was evaluated from the difference in ΔMR obtained by subtracting ΔMR before hot water treatment calculated in item F from ΔMR after hot water treatment calculated in item G. If the change in ΔMR was 2.0% or less, it was set as maintaining the moisture absorption property of the fiber before and after hot water treatment.

[0113] (Example 1)

[0114] Polyethylene terephthalate (melt viscosity 120 Pa·s, melting point 254℃) was designated as the sea section, and 50% by weight of polybutylene terephthalate (melt viscosity 50 Pa·s, melting point 217℃), copolymerized with polyethylene glycol (PEG6000S, Sanyo Chemical Industry Co., Ltd., with a number average molecular weight of 8300 g / mol), was designated as the island section. At a spinning temperature of 285℃, the polymers of the sea and island sections were melted separately and then metered at a weight ratio of 80:20 (island-to-island ratio) before flowing into the [unspecified component]. Figure 3 The spinning assembly of the composite die shown discharges the incoming polymer through a discharge hole (0.30 mm diameter, 36 holes) in a sea-island composite configuration, with 3 islands arranged on the outermost periphery and a total of 3 islands. The discharged composite polymer stream is cooled and solidified using a cooling device. After being oiled with an aqueous oiling agent via an oiling device, the circumferential speeds of the first traction roller (2000 m / min), the second stretching roller (2000 m / min), and the winding speed of the winding machine are set to 2000 m / min, resulting in unstretched polyester fiber with a 200 dtex-36 filament. Next, the unstretched filament is stretched at a temperature of 90°C for the first roller, 130°C for the second roller, and a stretch ratio of 2.38 (expressed as the ratio of the circumferential speeds of the first and second rollers), resulting in drawn polyester fiber with an 84 dtex-36 filament. In the cross-section of the obtained polyester fiber, the ratio of the length of each line segment to the average length of the line segment in the triangle obtained by connecting the centroids of the islands to be arranged on the outermost periphery is 0.97, 1.03, and 0.99, confirming that the shape obtained by connecting the centroids of the islands to be arranged on the outermost periphery is an equilateral triangle. The evaluation results of the obtained polyester fiber are shown in Table 1.

[0115] (Example 2)

[0116] The seabed was copolymerized with 1.5 mol% sodium isophthalate 5-sulfonate and 1.0 wt% polyethylene terephthalate (melt viscosity 170 Pa·s, melting point 244 °C) of polyethylene glycol (PEG1000, number average molecular weight 1000 g / mol) (Sanyo Kasei Corporation). Except for this, under the same conditions as in Example 1, drawn polyester fibers of 84 dtex-36 filaments were obtained. In the cross-section of the obtained polyester fibers, the ratio of the length of each line segment to the average length of the triangle obtained by connecting the centroids of the islands to be arranged on the outermost periphery was 0.99, 1.02, and 0.99, confirming that the shape obtained by connecting the centroids of the islands to be arranged on the outermost periphery was an equilateral triangle. The evaluation results of the obtained polyester fibers are shown in Table 1.

[0117] (Example 3)

[0118] The number of discharge holes was made 72 holes to obtain 155 dtex-72 filament unstretched yarn polyester fiber, the obtained unstretched yarn was stretched with a draw ratio of 1.84 times, and otherwise, under the same conditions as in Example 2, a drawn yarn of 84 dtex-72 filament polyester fiber was obtained. In the fiber cross section of the obtained polyester fiber, with respect to a triangle obtained by connecting the centers of gravity of the island portions arranged at the outermost periphery with line segments, the ratio of the length of each line segment to the average of the lengths of the line segments was 0.99, 0.99, 1.02, and it was confirmed that the figure obtained by connecting the centers of gravity of the island portions arranged at the outermost periphery with line segments was an equilateral triangle. The evaluation results of the obtained polyester fiber are shown in Table 1.

[0119] (Example 4)

[0120] The number of discharge holes was made 14 holes to obtain 258 dtex-14 filament unstretched yarn polyester fiber, the obtained unstretched yarn was stretched with a draw ratio of 3.07 times, and otherwise, under the same conditions as in Example 2, a drawn yarn of 84 dtex-14 filament polyester fiber was obtained. In the fiber cross section of the obtained polyester fiber, with respect to a triangle obtained by connecting the centers of gravity of the island portions arranged at the outermost periphery with line segments, the ratio of the length of each line segment to the average of the lengths of the line segments was 0.97, 1.00, 1.03, and it was confirmed that the figure obtained by connecting the centers of gravity of the island portions arranged at the outermost periphery with line segments was an equilateral triangle. The evaluation results of the obtained polyester fiber are shown in Table 1.

[0121] (Example 5)

[0122] The island-sea ratio was made 50:50 in terms of weight ratio, and otherwise, under the same conditions as in Example 3, a drawn yarn of 84 dtex-72 filament polyester fiber was obtained. In the fiber cross section of the obtained polyester fiber, with respect to a triangle obtained by connecting the centers of gravity of the island portions arranged at the outermost periphery with line segments, the ratio of the length of each line segment to the average of the lengths of the line segments was 1.00, 0.99, 1.01, and it was confirmed that the figure obtained by connecting the centers of gravity of the island portions arranged at the outermost periphery with line segments was an equilateral triangle. The evaluation results of the obtained polyester fiber are shown in Table 1.

[0123] (Example 6)

[0124] The sea portion was made of polyethylene terephthalate (melt viscosity: 40 Pa-s, melting point: 254°C), and, except for this, under the same conditions as in Example 1, drawn yarn of polyester fiber of 84 dtex-36 filament was obtained. In the fiber cross section of the obtained polyester fiber, with respect to a triangle obtained by connecting the centers of gravity of the island portions to be arranged at the outermost periphery with line segments, the ratio of the length of each line segment to the average value of the lengths of the line segments was 0.98, 1.03, 0.99, and it was confirmed that the figure obtained by connecting the centers of gravity of the island portions to be arranged at the outermost periphery with line segments was an equilateral triangle. The evaluation results of the obtained polyester fiber are shown in Table 1.

[0125] (Example 7)

[0126] The sea portion was made of polyethylene terephthalate (melt viscosity: 40 Pa-s, melting point: 254°C), the sea-island ratio was made 50:50 in terms of weight ratio, and, except for this, under the same conditions as in Example 3, drawn yarn of polyester fiber of 84 dtex-72 filament was obtained. In the fiber cross section of the obtained polyester fiber, with respect to a triangle obtained by connecting the centers of gravity of the island portions to be arranged at the outermost periphery with line segments, the ratio of the length of each line segment to the average value of the lengths of the line segments was 1.03, 1.01, 0.97, and it was confirmed that the figure obtained by connecting the centers of gravity of the island portions to be arranged at the outermost periphery with line segments was an equilateral triangle. The evaluation results of the obtained polyester fiber are shown in Table 1.

[0127] (Example 8)

[0128] The discharge hole was made 0.23 mm in hole diameter and 96 in number of holes, drawn yarn of polyester fiber of 115 dtex-96 filament was obtained, the obtained undrawn yarn was drawn at a draw ratio of 1.72 times, and, except for this, under the same conditions as in Example 3, drawn yarn of polyester fiber of 66 dtex-96 filament was obtained. In the fiber cross section of the obtained polyester fiber, with respect to a triangle obtained by connecting the centers of gravity of the island portions to be arranged at the outermost periphery with line segments, the ratio of the length of each line segment to the average value of the lengths of the line segments was 0.99, 1.01, 0.99, and it was confirmed that the figure obtained by connecting the centers of gravity of the island portions to be arranged at the outermost periphery with line segments was an equilateral triangle. The evaluation results of the obtained polyester fiber are shown in Table 1.

[0129] (Example 9)

[0130] Undrawn polyester fibers with an 88 dtex-144 filament were obtained by setting the discharge holes to a diameter of 0.20 mm and a number of holes of 144. The undrawn filament was then drawn to a draw ratio of 1.57. Alternatively, under the same conditions as in Example 3, drawn polyester fibers with a 56 dtex-144 filament were obtained. In the cross-section of the obtained polyester fibers, the ratio of the length of each line segment to the average length of the triangle formed by connecting the centroids of the islands located on the outermost periphery was 0.98, 1.03, and 0.99, confirming that the triangle formed by connecting the centroids of the islands located on the outermost periphery was an equilateral triangle. The evaluation results of the obtained polyester fibers are shown in Table 2.

[0131] (Example 10)

[0132] A copolymer of polyethylene glycol (PEG6000S manufactured by Sanyo Chemical Industry) with a number average molecular weight of 8300 g / mol and 16% by weight of polyethylene terephthalate (melt viscosity 68 Pa·s, melting point 251℃) was designated as the sea portion, and polyethylene terephthalate (melt viscosity 120 Pa·s, melting point 254℃) was designated as the island portion. After melting the sea and island polymers separately at a spinning temperature of 285℃, they were metered at a weight ratio of 90:10 (island to island ratio) and flowed into the [polymer / ... Figure 3 The spinning assembly of the composite die shown discharges the incoming polymer through a discharge hole (0.30 mm diameter, 36 holes) in a sea-island composite configuration, with 3 islands arranged on the outermost periphery and a total of 3 islands. The discharged composite polymer stream is cooled and solidified using a cooling device. After being oiled with an aqueous oiling agent by an oiling device, the circumferential speed of the first traction roller is set to 2000 m / min, the circumferential speed of the second stretching roller is set to 2000 m / min, and the winding speed of the winding machine is set to 2000 m / min, resulting in unstretched polyester fiber with a 215 dtex-36 filament. Next, the unstretched filament is stretched at a temperature of 90°C for the first roller, 130°C for the second roller, and a stretch ratio of 2.48 (expressed as the ratio of the circumferential speeds of the first and second rollers), resulting in stretched polyester fiber with an 84 dtex-36 filament. In the cross-section of the obtained polyester fiber, the ratio of the length of each line segment to the average length of the line segment in the triangle obtained by connecting the centroids of the islands located on the outermost periphery is 0.98, 1.02, and 0.99, confirming that the shape obtained by connecting the centroids of the islands located on the outermost periphery is an equilateral triangle. The evaluation results of the obtained polyester fiber are shown in Table 2.

[0133] (Example 11)

[0134] The sea part was made of polyethylene terephthalate (melt viscosity 170 Pa-s, melting point 244°C) to which 1.5 mol% of sodium salt of 5-sulfonic acid isophthalic acid and 1.0 wt% of polyethylene glycol (PEG 1000 manufactured by Sanko Chemical Industry) having a number average molecular weight of 1000 g / mol were copolymerized. Next, a polycaprolactam master batch to which 20 wt% of polyvinylpyrrolidone ("Luvitec" K30SP manufactured by BASF, K value = 30) was added in polycaprolactam not containing an additive was prepared. Then, the above master batch was granulated and blended in polycaprolactam (sulfuric acid relative viscosity 2.71, melting point 220°C) not containing an additive, and a polycaprolactam blend polymer having a polyvinylpyrrolidone addition rate of 5.0 wt% was prepared, and this blend polymer (melt viscosity 130 Pa-s, melting point 220°C) was used as the island part. The sea part and the island part were combined as described above, and the sea-island ratio was made 50:50 in terms of weight ratio, and otherwise, under the same conditions as in Example 1, a drawn yarn of a polyester fiber of 84 dtex - 36 filaments was obtained. In the fiber cross section of the obtained polyester fiber, with respect to a triangle obtained by connecting the centers of gravity of the island parts arranged at the outermost periphery with line segments, the ratio of the length of each line segment to the average value of the lengths of the line segments was 0.98, 1.02, 0.99, and it was confirmed that the figure obtained by connecting the centers of gravity of the island parts arranged at the outermost periphery with line segments was an equilateral triangle. The evaluation results of the obtained polyester fiber are shown in Table 2.

[0135] (Example 12)

[0136] The island part was made of "PEBAX MH1657" manufactured by Arkema (melt viscosity 45 Pa-s, melting point 203°C), and otherwise, under the same conditions as in Example 2, a drawn yarn of a polyester fiber of 84 dtex - 36 filaments was obtained. In the fiber cross section of the obtained polyester fiber, with respect to a triangle obtained by connecting the centers of gravity of the island parts arranged at the outermost periphery with line segments, the ratio of the length of each line segment to the average value of the lengths of the line segments was 1.01, 1.01, 0.98, and it was confirmed that the figure obtained by connecting the centers of gravity of the island parts arranged at the outermost periphery with line segments was an equilateral triangle. The evaluation results of the obtained polyester fiber are shown in Table 2.

[0137] (Example 13)

[0138] The sea part was made of polyethylene terephthalate (melt viscosity 170 Pa-s, melting point 244°C) to which 1.5 mol% of sodium salt of 5-sulfonic acid isophthalic acid and 1.0 wt% of polyethylene glycol (PEG 1000 manufactured by Sanko Chemical Industry) having a number average molecular weight of 1000 g / mol were copolymerized. Next, a polycaprolactam master batch to which 20 wt% of polyvinylpyrrolidone ("Luvitec" K30SP manufactured by BASF, K value = 30) was added in polycaprolactam not containing an additive was prepared. Then, the above master batch was granulated and blended in polycaprolactam (sulfuric acid relative viscosity 2.71, melting point 220°C) not containing an additive, and a polycaprolactam blend polymer having a polyvinylpyrrolidone addition rate of 5.0 wt% was prepared, and this blend polymer (melt viscosity 130 Pa-s, melting point 220°C) was used as the island part. The sea part and the island part were combined as described above, and the sea-island ratio was made 50:50 in terms of weight ratio, and otherwise, under the same conditions as in Example 1, a drawn yarn of a polyester fiber of 84 dtex - 36 filaments was obtained. In the fiber cross section of the obtained polyester fiber, with respect to a triangle obtained by connecting the centers of gravity of the island parts arranged at the outermost periphery with line segments, the ratio of the length of each line segment to the average value of the lengths of the line segments was 0.98, 1.02, 0.99, and it was confirmed that the figure obtained by connecting the centers of gravity of the island parts arranged at the outermost periphery with line segments was an equilateral triangle. The evaluation results of the obtained polyester fiber are shown in Table 2. Figure 3The spinning assembly of the composite die shown discharges the inflowing polymer through the discharge port (0.30 mm diameter, 72 holes) in a sea-island composite configuration, with 5 islands arranged on the outermost periphery and a total of 6 islands. Under the same conditions as in Example 3, drawn polyester fibers of 84 dtex-72 filament were obtained. In the cross-section of the obtained polyester fibers, the ratio of the length of each line segment to the average length of the pentagon obtained by connecting the centroids of the islands arranged on the outermost periphery with line segments was 1.01, 1.00, 0.98, 0.99, and 1.02, confirming that the shape obtained by connecting the centroids of the islands arranged on the outermost periphery with line segments is a regular pentagon. The evaluation results of the obtained polyester fibers are shown in Table 2.

[0139] (Example 14)

[0140] It flowed into the merged Figure 3 The spinning assembly of the composite die shown discharges the inflowing polymer through the discharge port (0.30 mm diameter, 36 holes) in a sea-island composite configuration, with 9 islands arranged on the outermost periphery and a total of 12 islands. Under the same conditions as in Example 2, drawn polyester fibers of 84 dtex-36 filament were obtained. In the cross-section of the obtained polyester fibers, the ratio of the length of each line segment to the average length of the nonagon obtained by connecting the centroids of the islands arranged on the outermost periphery with line segments was 1.03, 1.01, 0.98, 0.99, 1.00, 1.00, 0.98, 0.99, and 1.02, confirming that the shape obtained by connecting the centroids of the islands arranged on the outermost periphery with line segments is a regular nonagon. The evaluation results of the obtained polyester fibers are shown in Table 2.

[0141] (Example 15)

[0142] The island-to-island ratio was set to 65:35 by weight. Otherwise, under the same conditions as in Example 2, drawn polyester fibers with a length of 84 dtex-36 were obtained. In the cross-section of the obtained polyester fibers, the ratio of the length of each line segment to the average length of the triangle formed by connecting the centers of gravity of the islands positioned on the outermost periphery was 1.01, 0.98, and 1.01, confirming that the shape obtained by connecting the centers of gravity of the islands positioned on the outermost periphery was an equilateral triangle. The evaluation results of the obtained polyester fibers are shown in Table 2.

[0143] [Table 1]

[0144]

[0145] [Table 2]

[0146]

[0147] (Comparative Example 1)

[0148] Polyethylene terephthalate (melt viscosity 120 Pa·s, melting point 254℃) was designated as the sea section, and 50% by weight of polybutylene terephthalate (melt viscosity 50 Pa·s, melting point 217℃), copolymerized with polyethylene glycol (PEG6000S, Sanyo Chemical Industry Co., Ltd., with a number average molecular weight of 8300 g / mol), was designated as the island section. At a spinning temperature of 285℃, the polymers of the sea and island sections were melted separately and then metered at a weight ratio of 80:20 (island-to-island ratio) before flowing into the [unspecified component]. Figure 3 The spinning assembly of the composite die shown discharges the inflowing polymer through a discharge hole (0.30 mm diameter, 36 holes) in a core-sheath composite configuration where one island is located on the outermost periphery and the total number of islands is one. The discharged composite polymer stream is cooled and solidified using a cooling device. After being oiled with an aqueous oiling agent by an oiling device, the circumferential speeds of the first traction roller (2000 m / min), the second stretching roller (2000 m / min), and the winding speed of the winding machine are set to 2000 m / min, resulting in undrawn polyester fibers with a 200 dtex-36 filament. Next, the undrawn filament is stretched at a temperature of 90°C for the first roller, 130°C for the second roller, and a stretch ratio of 2.38 (expressed as the ratio of the circumferential speeds of the first and second rollers), resulting in drawn polyester fibers with an 84 dtex-36 filament. In the cross-section of the obtained polyester fiber, since there is only one island, it is impossible to obtain a pattern by connecting the centroids of the islands located on the outermost periphery with line segments. Therefore, the resulting polyester fiber experiences seam cracking upon moisture absorption, resulting in uneven dyeing and fuzziness when made into fabric. Furthermore, polymer from the islands dissolves from the cracked seams, leading to poor moisture absorption and release properties after hot water treatment. The evaluation results of the obtained polyester fiber are shown in Table 3.

[0149] (Comparative Example 2)

[0150] A drawn yarn of a polyester fiber of 84 dtex-36 filaments was obtained under the same conditions as in Example 1, except that the sea-island ratio was made 40:60 in terms of weight ratio. In the fiber cross section of the obtained polyester fiber, with respect to a triangle obtained by connecting the centers of gravity of the island portions arranged at the outermost periphery with line segments, the ratio of each line segment length to the average of the line segment lengths was 1.09, 0.96, 0.95, and the figure obtained by connecting the centers of gravity of the island portions arranged at the outermost periphery with line segments was not an equilateral triangle. Therefore, the obtained polyester fiber cracked at the sea portion at the time of moisture absorption, and uneven dyeing and fluff were generated at the time of fabric production. In addition, since the amount of the polyethylene terephthalate of the sea portion was small, the water absorption and quick drying properties were poor. The evaluation results of the obtained polyester fiber are shown in Table 3.

[0151] (Comparative Example 3)

[0152] A drawn yarn of a polyester fiber of 84 dtex-36 filaments was obtained under the same conditions as in Example 1, except that the sea-island ratio was made 40:60 in terms of weight ratio. In the fiber cross section of the obtained polyester fiber, with respect to a triangle obtained by connecting the centers of gravity of the island portions arranged at the outermost periphery with line segments, the ratio of each line segment length to the average of the line segment lengths was 1.09, 0.96, 0.95, and the figure obtained by connecting the centers of gravity of the island portions arranged at the outermost periphery with line segments was not an equilateral triangle. Therefore, the obtained polyester fiber cracked at the sea portion at the time of moisture absorption, and uneven dyeing and fluff were generated at the time of fabric production. In addition, since the amount of the polyethylene terephthalate of the sea portion was small, the water absorption and quick drying properties were poor. The evaluation results of the obtained polyester fiber are shown in Table 3.

[0153] (Comparative Example 4)

[0154] A drawn yarn of a polyester fiber of 84 dtex-10 filaments was obtained under the same conditions as in Example 2, except that the number of discharge holes was made 10 holes, and the obtained undrawn yarn was drawn at a draw ratio of 3.21 times. In the fiber cross section of the obtained polyester fiber, with respect to a triangle obtained by connecting the centers of gravity of the island portions arranged at the outermost periphery with line segments, the ratio of each line segment length to the average of the line segment lengths was 0.98, 1.02, 1.00, and it was confirmed that the figure obtained by connecting the centers of gravity of the island portions arranged at the outermost periphery with line segments was an equilateral triangle, but since the sea portion was thick, the moisture absorption and desorption properties were poor, and in addition, since the single fiber fineness was thick, the rigidity of the fiber was high, and the hand of the obtained fabric was also poor. The evaluation results of the obtained polyester fiber are shown in Table 3.

[0155] [Table 3]

[0156] Table 3

[0157]

[0158] PET: polyethylene terephthalate

[0159] SPIA-PET: 5-sulfoisophthalic acid copolymerized polyethylene terephthalate

[0160] PBT-PEG: polyethylene glycol copolymerized polybutylene terephthalate

[0161] Industrial availability

[0162] The polyester fiber of the present application is excellent in quality because it does not cause uneven dyeing, fluff, etc. when made into a fabric, since it inhibits cracking of the fiber surface due to dispersion of stress generated accompanying volume swelling of the fiber upon moisture absorption. Further, it has excellent moisture absorption because it does not undergo a decrease in moisture absorption, and is particularly suitable for use in clothing applications.

[0163] Explanation of symbols

[0164] 1: sea portion

[0165] 2a, 2b, 2c, 2d, 2e, 2f: island portion

[0166] 3a, 3b, 3c: line segment obtained by connecting the intersection points (centroids) of any two straight lines that bisect the area of the island portion in adjacent island portions among the island portions disposed at the outermost periphery of the fiber cross section

[0167] 4: inscribed circle (circumscribed circle) that circumscribes two or more of all the island portions disposed at the outermost periphery in the fiber cross section

[0168] 5: inscribed circle (circumscribed circle) that circumscribes two or more points in one island portion

[0169] 6: minimum thickness of the sea portion

[0170] 7: minimum distance between island portions

[0171] 8: gauge plate

[0172] 9: distribution plate

[0173] 10: discharge plate

[0174] B: intersection point of a straight line drawn from the intersection point (centroid) of any two straight lines that bisect the area of the island portion toward an arbitrary fiber surface and the outer periphery of the island portion

[0175] Da, Db: intersection point of the outer periphery of the island portion with a straight line drawn from the intersection point (center of gravity) of any two straight lines that bisect the area of the island portion toward any adjacent island portion

[0176] F: intersection point of the fiber surface with a straight line drawn from the intersection point (center of gravity) of any two straight lines that bisect the area of the island portion toward the fiber surface

[0177] Ga, Gb, Gc, Gd, Ge: intersection point (center of gravity) of any two straight lines that bisect the area of the island portion

Claims

1. A fiber, characterized by, is a sea-island composite fiber in which a main component of a sea portion is an aromatic polyester, a moisture absorption and release parameter ΔMR is 2.0% or more, and a figure obtained by connecting a center of gravity of the island portion disposed at the outermost periphery in the fiber cross section with a line segment is a regular polygon having the center of gravity as a vertex, a ratio C / L of a radius of curvature C of a side of the fiber surface side of the outer periphery of the island portion disposed at the outermost periphery in the fiber cross section to a radius L of a circumscribed circle of the island portion disposed at the outermost periphery in the fiber cross section is 0.50 to 0.81, and the radius of curvature C and the radius L are both in μm.

2. The fiber according to claim 1, characterized in that, the number of the island portions disposed at the outermost periphery in the fiber cross section is an odd number.

3. A fiber product comprising the sea-island composite fiber according to claim 1 or 2.

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