TWI882170B - Island-shaped composite fiber and fiber product containing the island-shaped composite fiber - Google Patents

Abstract

The fiber of the present invention is an island-type composite fiber whose main component of the sea part is an aromatic polyester, and the moisture absorption and release parameter ΔMR is 2.0% or more. The figure obtained by connecting the center of gravity of the island part arranged at the outermost periphery in the fiber cross section with a line segment is a regular polygon with the center of gravity as the vertex. It can provide a polyester fiber that can disperse the stress generated by the volume expansion of the fiber when absorbing moisture, and inhibit the occurrence of cracks on the fiber surface, and will not cause uneven dyeing or hairiness when forming knitted/woven fabrics, and has excellent quality, and the moisture absorption will not be reduced due to hot water treatment.

Description

Island-shaped composite fiber and fiber product containing the island-shaped composite fiber

The present invention relates to polyester fibers having hygroscopic properties.

For example, polyester fibers represented by polyethylene terephthalate have excellent mechanical properties, chemical resistance, and heat resistance, and have a characteristic feel of tension and toughness. They are not easy to absorb moisture, and even if they are wet, their characteristics still change little, they are not easy to crack, and they have excellent dimensional stability. Therefore, they are widely used in clothing and industrial purposes. However, as mentioned above, polyester fibers are not hygroscopic, especially in the high temperature and high humidity environment in summer, they will cause problems such as stuffiness and stickiness. Therefore, there is a proposal to form a composite fiber with a hygroscopic polymer to give polyester fibers hygroscopicity.

For example, the hygroscopic sea-island composite fiber proposed in Patent Document 1 has polyethylene terephthalate as the sea part and polyether block amide copolymer as the island part.

The sea-island composite fiber proposed in Patent Document 2 is a fiber that is made hygroscopic by using a hygroscopic polymer in the island part, and the sea-island composite fiber is inhibited from cracking during hot water treatment by controlling the thickness of the sea-island composite fiber that is located on the outermost layer of the fiber cross section.

[Prior Art Literature] [Patent Literature]

[Patent document 1] Japanese Patent Publication No. 2016-69770

[Patent Document 2] International Publication No. 2018/012318

The sea-island composite fibers disclosed in Patent Documents 1 and 2 have a predetermined sea thickness and number of islands in the fiber cross section. However, if the single fiber is made thinner in order to obtain the soft feel required for clothing applications, the stress generated by the volume expansion of the hygroscopic polymer during hot water treatment cannot be dispersed, and cracks such as cracks may occur on the fiber surface. In this case, uneven dyeing or hairiness may occur, which may lead to a decrease in the quality of knitted/woven fabrics. In addition, there is also the problem of elution of the hygroscopic polymer due to cracks on the fiber surface, resulting in a decrease in hygroscopicity. In addition, in the case of such fibers, when the fibers or textiles made of them are worn, there is also the possibility that cracks may easily occur on the fiber surface, which may cause problems when used in clothing such as underwear that is repeatedly washed, or clothing such as sportswear that is repeatedly rubbed.

Therefore, the present invention aims to solve the above-mentioned problems by dispersing the stress generated by the fiber volume expansion when absorbing moisture, thereby greatly improving the cracking of the fiber surface. In addition, the subject is to provide: polyester fiber that will not cause uneven dyeing and hairiness when forming knitted/woven fabrics, has excellent quality, and will not reduce moisture absorption due to hot water treatment, etc.

This invention is to solve the above-mentioned problems and has the following structure.

(1) A fiber is a sea-island type composite fiber whose main component of the sea portion is an aromatic polyester, whose moisture absorption and release parameter △MR is 2.0% or more, and a figure obtained by connecting the centroids of the island portions arranged at the outermost periphery in the cross section of the fiber with line segments is a regular polygon with the centroid as the vertex.

(2) A fiber as described in (1), wherein the number of island portions arranged at the outermost periphery in the cross-section of the fiber is an odd number.

(3) The fiber as described in (1) or (2), wherein the ratio C/L of the radius of curvature C (μm) of the edge on the fiber surface side at the periphery of the outermost island portion in the fiber cross section to the radius L (μm) of the circumscribed circle containing the outermost island portion in the fiber cross section is 0.50 to 0.90.

(4) A fiber product comprising the island-in-the-sea composite fiber described in any one of (1) to (3).

According to the present invention, the stress generated by the fiber volume expansion during moisture absorption can be dispersed to suppress cracking of the fiber surface, so that high-quality polyester fibers can be obtained without uneven dyeing and hairiness when forming knitted/woven fabrics. In addition, since the moisture absorption does not decrease, it has excellent moisture absorption and is particularly suitable for clothing applications.

1: Kaibu

2a, 2b, 2c, 2d, 2e, 2f: Island part

3a, 3b, 3c: The fiber cross section is arranged in the outermost island part, and the connecting line segment between the intersection points (centers of gravity) of any two straight lines that divide the area of the adjacent island part into two equal parts

4: All islands located at the outermost periphery in the fiber cross section are circumscribed by two or more perfect circles (circumscribed circles)

5: A perfect circle circumscribed to an island with two or more points (circumscribed circle)

6: Minimum thickness of sea part

7: The line segment representing the minimum distance S between islands in the fiber cross section

8: Metering board

9: Distribution board

10: Discharge plate

B: From the intersection point (center of gravity) of any two straight lines that divide the island area into two equal parts, draw a straight line toward any fiber surface, and the intersection point with the outer periphery of the island

Da, Db: The intersection point (center of gravity) of any two straight lines that divide the island area into two equal parts toward any adjacent island, and the intersection point with the outer periphery of the island

F: Draw a straight line from the intersection point (center of gravity) of any two straight lines that divide the island area into two equal parts toward any fiber surface, and the intersection point with the fiber surface

Ga, Gb, Gc, Gd, Ge: The intersection point (center of gravity) of any two straight lines that divide the island area into two equal parts

Figure 1 is a schematic diagram of the cross-sectional structure of the polyester fiber of the present invention (a), (b), and (c).

Figure 2 is a schematic diagram of the cross-sectional structure of the polyester fiber of the present invention (a), (b), (c), (d).

Figure 3 is a cross-sectional view illustrating the manufacturing method of the polyester fiber of the present invention.

The main component of the polyester fiber of the present invention is aromatic polyester. The main component is aromatic polyester, which makes the mechanical properties and heat resistance excellent, so it can become a good touch such as tension, toughness, and dryness. In addition, because the polyester fiber of the present invention has excellent moisture absorption with a moisture absorption and release parameter △MR of more than 2.0%, it can obtain a fiber structure with excellent wearing comfort when it becomes a cool material.

Hygroscopic fibers absorb water molecules through physical adsorption of water molecules to the fibers and/or the interaction between the functional groups in the molecular structure of the fiber components and water molecules. Especially when the fibers are highly hygroscopic, the fibers will swell in volume because water molecules are absorbed into the fibers. However, since aromatic polyesters have rigid aromatic rings in their polymer structure, they are not easily deformed, making it difficult to disperse the stress generated by volume swelling due to moisture absorption, which may cause cracks on the fiber surface.

Here, the polyester fiber of the present invention suppresses cracking of the fiber surface due to volume expansion during moisture absorption, and the key point is that among the components arranged inside the fiber in the fiber cross section, the figure obtained by connecting the centroids of the outermost components arranged with line segments is a regular polygon with the centroid as the vertex.

In the fiber cross section, the fiber cross section morphology having components arranged inside the fiber is preferably a sea-island composite fiber composed of two or more polymers, and the components arranged inside the fiber belong to the island portion. In the fiber cross section, the center of gravity of the components arranged at the outermost periphery among the components arranged inside the fiber, that is, the center of gravity of the island portion arranged at the outermost periphery in the fiber cross section, is connected by line segments. When the center of gravity of the island portion is connected by line segments, as shown in Figure 1(a), the center of gravity is selected in such a way that the line segments do not cross at places other than the center of gravity. On the other hand, as shown in FIG1(b), if the centroids of the islands are connected by line segments, the line segments intersect at the portion other than the centroids of the islands. The figure drawn at this time is not included in the figure obtained by connecting the centroids of the islands arranged at the outermost periphery with line segments in the present invention. Also, as shown in FIG1(c), in the island 2f, since other islands (2a, 2b, 2c, 2d, 2e) are arranged between the island and the fiber surface, the island 2f is not included in the island arranged at the outermost periphery in the fiber cross section.

The definition of regular polygons for the island component configuration that is a characteristic of the present invention is explained.

The figure obtained by connecting the center of gravity of the island part arranged 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 length of each line segment is set as A1, A2, A3‧‧‧An. The average value of the line segment length is set as Lx, and the ratio of each line segment length to the average value Lx (A1/Lx, A2/Lx, A3/Lx‧‧‧An/Lx) is calculated, and the third decimal place is rounded off. When they are all between 0.97 and 1.03, it means that the figure obtained by connecting the center of gravity of the island part arranged at the outermost periphery in the fiber cross section with line segments is a regular n-gon.

The polyester fiber of the present invention is formed by connecting the center of gravity of the island part arranged at the outermost periphery in the cross section of the fiber with a line segment. The figure is a regular polygon with the center of gravity as the vertex. When the volume expands due to moisture absorption, the vector of the stress generated between the adjacent island parts is completely opposite, so that the stress between the island parts is offset, so that the stress propagating toward the sea part at the surface end of the fiber can be reduced. Because the stress propagating toward the sea part of the fiber surface is reduced, the fiber surface is not easy to crack, and the occurrence of uneven dyeing and hairiness can be suppressed. On the other hand, when the figure obtained by connecting the center of gravity of the outermost island part in the fiber cross section with a line segment is not a regular polygon with the center of gravity as the vertex, the stress generated by the volume expansion during moisture absorption is not easy to disperse, and stress concentration points are likely to occur at the interface between the island part and the sea part. Therefore, there may be cracks on the fiber surface, uneven dyeing or hairiness, and the quality of woven or knitted fabrics will be reduced.

As mentioned above, the polyester fiber of the present invention can greatly improve the problems of the known composite fiber with hygroscopic components by configuring the island components at the outermost periphery in the shape of regular polygons, and the number of island components arranged at the outermost periphery in the fiber cross section is preferably an odd number.

By setting the number of islands arranged at the outermost periphery to an odd number, the stress generated by volume expansion due to moisture absorption can be suppressed from being concentrated in a straight line, and the stress can be dispersed to suppress cracking on the fiber surface. Therefore, uneven dyeing or hairiness caused by cracking on the fiber surface can be suppressed, so that the knitted/woven fabric can have excellent quality. The number of islands arranged at the outermost periphery in the fiber cross section is preferably an odd number of 9 or less, particularly preferably an odd number of 5 or less, and the minimum number of islands is 3.

The total number of islands in the fiber cross section of the polyester fiber of the present invention is preferably 15 or less. By setting the total number of islands within this range, the stress generated by volume expansion due to moisture absorption can be suppressed from being concentrated in a straight line, and the stress can be dispersed, so that cracking on the fiber surface can be suppressed. Therefore, uneven dyeing or hairiness caused by cracking on the fiber surface can be suppressed, so that knitted/woven fabrics can have excellent quality when formed. The number of islands in the fiber cross section is more preferably 10 or less, particularly preferably 6 or less, and the minimum number of islands is 3.

In the polyester fiber of the present invention, the ratio C/L of the radius of curvature C (μm) of the edge on the fiber surface side at the periphery of the outermost island portion in the fiber cross section and the radius L (μm) of the circumscribed circle including the outermost island portion in the fiber cross section is preferably 0.50~0.90. Here, the circumscribed circle including the outermost island portion in the fiber cross section is circle 4 in Figure 2(b), and L is the radius of circle 4. In addition, the radius of curvature C of the edge on the fiber surface side at the periphery of the outermost island portion in the fiber cross section is the radius of circle 5 in Figure 2(c) obtained according to the method described in the embodiment.

C/L represents the sharpness of the bend of the edge on the fiber surface side arranged at the outermost island portion in the fiber cross section relative to the fiber surface. If C/L is above 0.50, the stress generated by the volume expansion during moisture absorption is evenly dispersed in the sea portion, making it difficult for the fiber surface to crack. It is more preferably above 0.55, and particularly preferably above 0.60. In addition, if C/L is below 0.90, the bend of the edge on the fiber surface side arranged at the outermost island portion in the fiber cross section will not be too large, and there will be no sharp corners, so the stress generated by the volume expansion during moisture absorption will not be concentrated in these parts, so the fiber surface will not crack. A better value is 0.85 or less, and a particularly better value is 0.80 or less. In addition, C/L of 1.0 means that the edge of the fiber surface side of the outer periphery of the island portion arranged at the periphery is equal to the fiber surface curvature. A specific example of the fiber cross-section in this case is a core-sheath composite fiber with one island portion.

The polyester fiber of the present invention is a fiber cross-section in which the ratio L/R of the radius of the circumscribed circle L (μm) including all the islands arranged at the outermost periphery to the fiber radius R (μm) is preferably 0.50~0.90.

L/R represents the thickness of the sea between the fiber surface and the outermost island in the fiber cross section. If L/R is below 0.90, the sea thickness can be sufficiently ensured relative to the fiber diameter, and the sea cracking caused by the stress generated by volume expansion during moisture absorption can be suppressed. The sea cracking can also suppress the uneven dyeing or hairiness caused by the cracking of the fiber surface, and can achieve excellent quality when it becomes a knitted/woven fabric. Based on this idea, it is more preferably below 0.80, and particularly preferably below 0.60. In addition, if L/R is above 0.50, the rigidity caused by the thickness of the aromatic polyester configured in the sea can be reduced, and the stress generated by volume expansion during moisture absorption can be reduced.

In the polyester fiber of the present invention, the ratio S/L of the minimum distance S (μm) between islands in the fiber cross section and the radius L (μm) of the circumscribed circle in the fiber cross section including all islands arranged at the outermost periphery is preferably 0.05 to 0.50. Here, the minimum distance S between islands in the fiber cross section is obtained according to the method described in the embodiment, line segment 7 in Figure 2 (d).

Here, the minimum distance S between the islands in the fiber cross section refers to the thickness of the sea portion sandwiched by two adjacent islands. If S/L is 0.05 or more, the stress generated by the volume expansion during moisture absorption can be relieved by the sea portion between the islands, which can reduce the propagation of stress toward the sea portion, and can inhibit the occurrence of turtle cracks on the fiber surface. It is more preferably 0.10 or more, and particularly preferably 0.15 or more. In addition, if S/L is less than 0.50, because the distance between the islands is not separated, the stress relief effect caused by the sea portion between the islands can be shown, which can reduce the propagation of stress toward the sea portion on the fiber surface, and can inhibit the occurrence of turtle cracks on the fiber surface. Based on this idea, the S/L is more preferably below 0.40, and particularly preferably below 0.30.

The minimum thickness of the sea portion of the polyester fiber of the present invention is preferably greater than 0.3μm.

The so-called minimum sea thickness here refers to the method described in the embodiment. When a straight line is drawn from the center of gravity of any island in the fiber cross section to any fiber surface, the distance between the outer periphery of the island and the intersection of the straight line, and the distance between the fiber surface and the intersection of the straight line is the smallest, which is line segment 6 in Figure 2(c). If the minimum sea thickness is 0.3μm or more, the sea cracking caused by the stress generated by volume expansion during moisture absorption can be suppressed, and the uneven dyeing or hairiness caused by the cracking of the fiber surface due to the sea cracking can be suppressed, so that the knitted/woven fabric can have excellent quality. It is more preferably 1.0μm or more, and particularly preferably 2.5μm or more.

The seam/island composite ratio of the polyester fiber of the present invention is preferably 50/50 to 90/10 by weight. If the seam composite ratio reaches 50% by weight or more, the aromatic polyester in the seam makes the mechanical properties and heat resistance excellent, and can obtain tension, toughness, and dryness, and can obtain a fiber structure with excellent wearing comfort. In addition, it can inhibit the seam cracking caused by the stress generated by volume expansion during moisture absorption, and can inhibit the uneven dyeing or hairiness caused by the seam cracking that causes the fiber surface to crack, so that the knitted/woven fabric can have excellent quality. The seam composite ratio is more preferably 60% by weight or more, and particularly preferably 70% by weight or more. On the other hand, if the sea portion composite ratio of the polyester fiber is below 90% by weight, that is, the island portion composite ratio is above 10% by weight, the rigidity caused by the thickness of the aromatic polyester configured in the sea portion can be reduced, and the stress generated by volume expansion during moisture absorption can be reduced. Based on this idea, the sea portion composite ratio is preferably below 85% by weight, and particularly preferably below 80% by weight.

The moisture absorption and release parameter △MR of the moisture absorption index of the polyester fiber of the present invention is more than 2.0%. △MR is the difference in fiber moisture absorption rate at high temperature and high humidity represented by 30℃×90%RH and at standard temperature and humidity represented by 20℃×65%RH. The higher the △MR, the higher the fiber moisture absorption. If △MR reaches more than 2.0%, the feeling of stuffiness inside the clothes is less and the wearing comfort can be shown. The better △MR range is more than 2.5%, the particularly good range is more than 3.0%, and the better range is more than 4.0%. There is no special upper limit for the △MR range. The level that can be achieved by the present invention is about 10%, which becomes the actual upper limit. In addition, the polyester fiber of the present invention meets the above △MR range even before and after hot water treatment such as dyeing.

The aromatic polyester as the main component of the polyester fiber of the present invention is a polymer composed of, for example, aromatic dicarboxylic acid and aliphatic diol, aliphatic dicarboxylic acid and aromatic diol, aromatic dicarboxylic acid and aromatic diol, etc. Generally speaking, from the perspective of mechanical properties, heat resistance, and operability during manufacturing, it is better to use an aromatic polyester composed of a combination of aromatic dicarboxylic acid and aliphatic diol.

Specific examples of aromatic dicarboxylic acids include, but are not limited to, terephthalic acid, isophthalic acid, phthalic acid, 5-sodium sulfonate isophthalic acid, 5-lithium sulfonate isophthalic acid, 5-(tetraalkyl)phosphoniumsulfoisophthalic acid, 4,4'-diphenyldicarboxylic acid, 2,6-naphthalene dicarboxylic acid, etc.

Specific examples of aliphatic diols include ethylene glycol, 1,3-propylene glycol, 1,4-butanediol, hexanediol, cyclohexanediol, diethylene glycol, hexanediol, neopentyl glycol, etc., but are not limited thereto.

The manufacturing method of the aromatic polyester of the present invention is not limited. If the raw materials during manufacturing are collectively referred to as monomers, the monomers can be synthesized and manufactured using general polycondensation reactions, addition polymerization reactions, etc. Monomers can be, for example: monomers derived from petroleum, monomers derived from biomass, and mixtures of monomers derived from petroleum and monomers derived from biomass, but are not limited thereto.

In addition, in the aromatic polyester of the present invention, in addition to the main component, the second and third components can also be copolymerized or mixed within the scope of the purpose of the present invention. Because the main component is aromatic polyester, the copolymerization amount is set to a monomer amount of the copolymerization component relative to the total monomer amount of less than 10 mol%.

As mentioned above, the main component of the sea portion of the polyester fiber of the present invention is aromatic polyester. However, generally aromatic polyester does not have functional groups that form strong interactions with water molecules in the polymer structure. Therefore, examples of methods for setting the △MR of the polyester fiber of the present invention to the above range include: adding hygroscopic compounds, configuring highly hygroscopic polymers (hereinafter also referred to as "hygroscopic polymers"), and treating polymer molecules on the fiber surface with ozone to generate hygroscopic functional groups. Among these, if you want to obtain a polyester fiber with excellent hygroscopicity, it is better to configure the hygroscopic polymer in the island portion.

Preferred examples of hygroscopic polymers suitable for being arranged in the island part of the polyester fiber of the present invention include polyether ester, polyether amide, polyether ester amide, polyamide, thermoplastic cellulose derivatives, polyvinyl pyrrolidone, etc. Among them, from the perspective of excellent stability during melt molding and high target hygroscopicity, the polyester fiber of the present invention is preferably polyether ester, polyether amide, polyether ester amide, etc. containing a copolymer component polyether. In addition, because polyether ester has excellent affinity with the aromatic polyester of the sea part and the heat resistance of the hygroscopic polymer is also excellent, it also has the effect of making the mechanical properties of the obtained sea island composite fiber good, and is a particularly good user of the present invention. In addition, from the perspective of inhibiting the dissolution of hygroscopic polymers into hot water, polyether ester composed of polybutylene terephthalate and polyether with excellent crystallinity is more preferred.

As mentioned above, the hygroscopic polymer has a high affinity with water and is easily dissolved if it comes into contact with water or hot water during dyeing. If the stress generated by volume expansion during moisture absorption causes cracks on the fiber surface, the hygroscopic polymer in the island portion will come into contact with hot water and dissolve out of the fiber, causing the fiber's hygroscopicity to decrease. Therefore, when the hygroscopic polymer is configured in the island portion, the polyester fiber of the present invention can significantly exert the effect of suppressing cracks on the fiber surface by utilizing the composite cross-sectional shape, and a polyester fiber with excellent hygroscopicity can be obtained.

In the hygroscopic polymer of the present invention, in addition to the main component, the second and third components can also be copolymerized or mixed within the scope of the purpose of the present invention, and the copolymerization amount is set to a monomer amount of the copolymerization component relative to the total monomer amount is less than 10 mol%.

The cross-sectional shape of the polyester fiber of the present invention is not limited to a circular cross-sectional shape, but can also adopt a variety of cross-sectional shapes such as flat, Y-shaped, T-shaped, hollow, field-shaped, and well-shaped.

The polyester fiber of the present invention can be in any form such as long fiber (filament), short fiber (staple), etc. In the case of long fiber, it can be a single filament yarn composed of one single filament, or a multifilament yarn composed of a plurality of single filaments. In the case of short fiber, there is no limitation on the cut length and the number of windings.

The total fiber density of the polyester fiber of the present invention can be appropriately set according to the purpose. If long fibers are used for clothing, it is preferably 8 dtex or more and 150 dtex or less. In addition, the strength is preferably 1.5 cN/dtex or more for clothing. If other fibers are used in combination when making fabrics, it can be used without problems even if it is below 1.5 cN/dtex. The elongation can be appropriately set according to the purpose. From the perspective of processability when processing fabrics, it is preferably 25% or more and 60% or less.

The single fiber fineness of the polyester fiber of the present invention is preferably below 6.0 dtex. By setting it within this range, the rigidity caused by the thickness of the aromatic polyester configured in the seam can be reduced, and the mechanical properties and heat resistance are excellent, and the tension, toughness, and dryness can be obtained, and a fiber structure with excellent wearing comfort can be obtained. In addition, the seam cracking caused by the stress generated by volume expansion during moisture absorption can be suppressed, and the uneven dyeing or hairiness caused by the seam cracking that causes the fiber surface to crack can be suppressed, so that the knitted/woven fabric can have excellent quality. The single fiber fineness is more preferably below 4.0 dtex, and particularly preferably below 2.0 dtex.

The polyester fiber of the present invention can be obtained by using known melt spinning, composite spinning and other methods, which can be exemplified as follows. However, the spinning method and composite method are only exemplified and are not limited to these.

The polyester fiber of the present invention, which is composed of two or more polymers, can be produced by, for example, melt spinning for the purpose of producing long fibers, solution spinning such as wet spinning and dry-wet spinning, and melt blowing and spunbonding suitable for obtaining sheet-like fiber structures. From the perspective of improving productivity, melt spinning is preferred. In the case of melt spinning, it is best to use the composite spinning nozzle described below. When the melt spinning method is used, the spinning temperature at this time is set to a temperature at which the main high-melting point or high-viscosity polymer among the polymers used exhibits fluidity. The fluidity temperature varies according to the molecular weight. If it is set between the melting point of the polymer and the melting point + 60°C, it can be manufactured stably.

The manufacturing method using the melt spinning method is, for example, to melt the sea polymer and the island polymer separately, meter and transport them using a gear pump, and then form a composite flow in a specific composite structure using a common method, and then spit out from the spinning nozzle, and use a yarn cooling device such as a chimney duct to spray cooling air to cool the yarn to room temperature, and use an oil supply device to supply oil and bundle it, and then use a fluid interlacing nozzle device to interlace it, and pass through a traction roller and a stretching roller, and at this time, stretch it according to the circumferential speed ratio of the traction roller and the stretching roller. In addition, for example, the yarn can be heat-set using a stretching roller and then wound using a winding machine (winding device). In addition, a two-step method can be used, for example: the circumferential speeds of the pulling roller and the stretching roller are set to the same speed, and then the unstretched yarn is first formed by winding with a winding machine at the same speed, and then the stretching is performed according to other steps.

In the polyester fiber of the present invention, by setting the melt viscosity ratio of two or more polymers used in the sea part and the island part to 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 preferred.

The composite spinning nozzle used in manufacturing the polyester fiber of the present invention is preferably the composite spinning nozzle described in Japanese Patent Publication No. 2011-208313. The composite spinning nozzle shown in FIG3 of the present case is a state assembly of three major types of components, such as a metering plate 8, a distribution plate 9 and a discharge plate 10, which are stacked in sequence from the top in a nozzle assembly to provide spinning. FIG3 shows an example of using two polymers, polymer A and polymer B. It is known that it is difficult to control the shape of the island portion of the composite spinning nozzle as described above, and it is better to use a composite spinning nozzle using a fine flow path as shown in FIG3.

The spinning nozzle component shown in FIG3 has the function of measuring the amount of polymer in each discharge hole and each distribution hole by the metering plate 8 and flowing in, controlling the composite cross section and cross-sectional shape of the single fiber cross section by the distribution plate 9, and then compressing the composite polymer flow formed by the distribution plate 9 by the discharge plate 10 and discharging it.

In order to avoid making the description of the composite spinning nozzle complicated, although not shown in the figure, the components stacked on the surface of the metering plate 8 can be used in conjunction with the spinning machine and the nozzle assembly to form a flow path. By designing the metering plate 8 in conjunction with the existing flow path components, the existing nozzle assembly and components can be directly used, so there is no need to specialize the spinning machine specifically for the spinning nozzle. In addition, multiple flow path plates can be stacked between the flow path and the metering plate 8, or between the metering plate 8 and the distribution plate 9. In this way, the flow path for transferring the polymer can be designed efficiently in the direction of the spinning nozzle cross section and the direction of the single fiber cross section, and a structure introduced into the distribution plate 9 is formed. The composite polymer flow discharged from the discharge plate 10 is cooled and solidified according to the above-mentioned manufacturing method, and then oil is applied and pulled by a roller with a specified circumferential speed to obtain a fiber with the required composite cross-section.

The polyester fiber of the present invention can be subjected to post-processing such as false twisting and yarn twisting, and can also be processed in the same way as ordinary fibers for weaving and knitting.

The polyester fiber and/or post-processed yarn of the present invention can be formed into fiber structures such as fabrics, knitted fabrics, fleece fabrics, non-woven fabrics, twisted yarns, batting and other fiber structures according to known methods. In addition, the fiber structure composed of the polyester fiber and/or post-processed yarn of the present invention can be any knitted tissue or braided tissue. Preferably, it can be plain weave, woven weave, satin weave or variations thereof; and warp knitting, weft knitting, circular knitting, lace tissue or variations thereof, etc.

The polyester fiber of the present invention can also be combined with other fibers by interweaving or knitting when forming a fiber structure, or can be formed into a fiber structure after forming a mixed yarn with other fibers.

The fiber structure composed of the polyester fiber and/or post-processed yarn of the present invention is suitable for applications requiring comfort and quality due to its excellent moisture absorption. For example: general clothing applications, sportswear applications, bedding applications, interior decoration applications, material applications, etc., but not limited to these.

[Implementation example]

The present invention is described in detail using embodiments, but the present invention is not limited to such embodiments. In addition, the characteristic values in the embodiments are measured using the following method.

A. Melt viscosity of polymer

For polymer samples with a water content of 300ppm or less formed by a vacuum dryer, a capillary rheometer manufactured by Toyo Seiki Co., Ltd. was used to put the sample into a heating furnace set at the same temperature as the spinning temperature, melt it in a nitrogen environment, and stepwise change the strain rate. The sample was extruded from the capillary at the front end of the heating furnace and the viscosity was measured. In addition, the measurement was started after the sample was placed in the heating furnace for 5 minutes, and the value at the shear rate of 1216sec ^-1 was set as the melt viscosity of the polymer.

B. Polymer melting point (Tm)

Using a differential scanning calorimeter (DSC) Q2000 manufactured by TA instruments, 20 mg of a polymer sample was heated from 20°C to 300°C at a heating rate of 20°C/min, kept at 300°C for 5 minutes, cooled from 300°C to 20°C at a cooling rate of 20°C/min, kept at 20°C for 1 minute, and then heated from 20°C to 280°C at a heating rate of 20°C/min. The peak temperature of the observed endothermic peak was set as the melting point. In addition, when multiple endothermic peaks were observed, the highest endothermic peak was set as the melting point.

C. Total fiber density

The fiber sample was taken up 200 times using a reel with a yarn frame circumference of 1.125m to make a reel. After drying in a hot air dryer (105±2℃×60 minutes), the reel weight was measured using a scale and the total fiber content was calculated by multiplying the value by the standard moisture regain. The measurement was performed 4 times and the average value was set as the total fiber content.

D. Tensile strength and elongation

The fiber samples were measured using a measuring instrument "TENSILON" (registered trademark) UCT-100 manufactured by ORIENTEC Co., Ltd., under the constant rate elongation conditions specified in the chemical fiber long yarn test method (JIS L1013 (2010)). The elongation was obtained from the elongation at the maximum strength in the tensile strength-elongation curve. The tensile strength was the value obtained by dividing the maximum strength by the total fiber length. The measurement was performed 10 times, and the average values were set as the tensile strength and elongation.

E. Boiling water shrinkage rate

The fiber sample was taken up 20 times using a reel with a yarn frame circumference of 1.125m to make a spun yarn, and the initial length L ₀ was determined under a load of 0.09 cN/dtex. Then, it was treated in boiling water for 30 minutes without load and then air-dried. Then, the length L ₁ after treatment under a load of 0.09 cN/dtex was determined and calculated according to formula (1): Boiling water shrinkage (%) = [(L ₀ -L ₁ )/L ₀ ] × 100‧‧‧(1)

F.△MR before hot water treatment

Weigh about 1~2g of fiber sample or fabric sample in a weighing bottle, dry it at 110℃ for 2 hours, measure the mass, and set the mass as _w0 . Then, keep the dried fiber sample at 20℃ and relative humidity 65% for 24 hours, measure the mass, and set the mass as w65 _% . Then, adjust the temperature to 30℃ and relative humidity 90%, keep the fiber sample for 24 hours, measure the mass, and set the mass as _w90% .

MR ₁ =[(w _65% -w ₀ )/w ₀ ]×100‧‧‧(2)

MR ₂ =[(w _90% -w ₀ )/w ₀ ]×100‧‧‧(3)

△MR=MR ₂ -MR ₁ ‧‧‧(4)

At this time, the value calculated by equations (2) to (4) is set as △MR.

G.△MR after hot water treatment

The fiber samples were knitted using a circular knitting machine NCR-BL (needle cylinder diameter 3.5 inches (8.9cm), 27 gauge) manufactured by Yingguang Industry Co., Ltd., with the needle mesh adjusted to 50, to produce the original tube knitted fabric. When the positive fiber fineness of the fiber is less than 80dtex, the yarn is appropriately plyed in such a way that the total fiber fineness of the yarn fed to the tube knitting machine becomes 80~160dtex. When the total fiber fineness exceeds 80dtex, one yarn is fed to the tube knitting machine and the needle mesh is adjusted to 50 as described above for production. Next, the obtained tubular knitted fabric was placed in an aqueous solution containing 1g/L sodium carbonate and SANMOL BK-80 surfactant produced by Nichika Chemical Co., Ltd. The aqueous solution was heated to 80°C and treated for 20 minutes, and then dried in a 60°C hot air dryer for 60 minutes. Furthermore, the dried tubular knitted fabric was subjected to hot water treatment according to the conditions of bath ratio 1:100, treatment temperature 130°C, and treatment time 60 minutes, and then dried in a 60°C hot air dryer for 60 minutes to obtain the tubular knitted fabric after hot water treatment. The obtained tubular knitted fabric after hot water treatment was calculated according to the record in item F to obtain △MR.

H. Radius of curvature C

The fiber sample was embedded with an embedding agent such as epoxy resin, and the fiber cross section perpendicular to the fiber axis was imaged using a scanning electron microscope (SEM) manufactured by HITACHI at a magnification that allows observation of more than 10 single fibers. The image was analyzed using computer software WinROOF manufactured by Mitani Shoji to obtain the radius of curvature C of the outermost island portion in the fiber cross section, which is close to the fiber surface.

When calculating the radius of curvature, first refer to Figure 2(c) and draw a straight line from the center of gravity Ga of the island to the surface of any fiber. Then measure the length of the line segment BF formed by the intersection B of the island periphery and the straight line and the intersection F of the fiber surface and the straight line to the second decimal place, and calculate the intersection B where the length of the line segment BF is the minimum. From the island that is touched by the intersection B, calculate the minimum radius to the third decimal place in the circle circumscribed to the island. This operation is performed on all islands contained in a single fiber, and this operation is performed on three randomly sampled single fibers. The average value of the obtained radii is calculated, and the value rounded to the third decimal place is set as the radius of curvature C (μm).

I. Circumscribed circle radius L

In the same way as in item H, the fiber cross-section images were taken using SEM, and the images were analyzed using WinROOF. The radius of the circumscribed circle of the fiber cross-section, including all islands arranged at the outermost periphery, was measured to the third decimal place. This operation was performed on 10 randomly sampled single fibers, and the simple quantitative average was obtained from the results. The value rounded to the third decimal place was set as the circumscribed circle radius L (μm).

J. Fiber radius R

In the same way as item H, use SEM to take fiber cross-section images. From each image taken, measure the radius of a randomly sampled single fiber in the same image to the third decimal place in μm units. Perform this operation on 10 randomly sampled single fibers, and obtain a simple numerical average from the result. Set the value rounded to the third decimal place as the fiber radius R (μm). Here, when the fiber cross-section perpendicular to the fiber axis is not a perfect circle, its area is measured and the value obtained by converting to a circle is used.

K. Minimum distance S between islands

Similar to item H, use SEM to take fiber cross-section images, use WinROOF to analyze the images, and find the minimum distance S between islands in the fiber cross-section.

When obtaining the minimum distance S between islands, refer to Figure 2(d). In two adjacent islands 2a and 2b, draw a straight line from the center of gravity Ga of island 2a to island 2b, set the intersection points with the outer periphery of each island as Da and Db, and measure the minimum length of the line segment Da-Db to the third decimal place. This operation is performed for two adjacent islands randomly sampled from 10 islands in a single fiber. In addition, when 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 is measured from all islands contained in a single fiber. In addition, this operation is performed on three randomly sampled single fibers, and the average length of the obtained line segment Da-Db is obtained, and the value rounded to the third decimal place is set as the minimum distance S (μm) between islands.

L. Minimum thickness of the sea area

In the same way as the method for obtaining the length of the line segment BF described in item H, refer to Figure 2(c), draw a straight line from the center of gravity Ga of the island to the surface of any fiber, measure the length of the line segment BF formed by the island periphery and the straight line intersection B, and the fiber surface and the straight line intersection F to the second decimal place, and obtain the intersection B where the length of the line segment BF is the minimum. This measurement is performed on all islands contained in a single fiber, and on three randomly sampled single fibers, and the average value of the obtained line segment BF is obtained, and the value rounded to the second decimal place is set as the minimum thickness of the sea (μm).

M. Number of sea turtle cracks

For the tubular knitted fabric produced by the method described in item G and subjected to hot water treatment, platinum-palladium alloy was used for evaporation, and then a Hitachi scanning electron microscope (SEM) S-4000 was used to observe at 1000 times, and 10 microscope photos of the field of view were randomly taken. In the 10 photos obtained, the fiber surface constituting the tubular knitted fabric was observed, and the number of seam cracks was counted. If the number of seam cracks is less than 10, it is considered to be passed.

N. Uneven dyeing

According to the method described in item G, a tubular knitted fabric is prepared, and the obtained tubular knitted fabric is placed in an aqueous solution containing 1g/L sodium carbonate and SANMOL BK-80, a surfactant manufactured by Nikka Chemical Co., Ltd., and the aqueous solution is heated to 80°C and treated for 20 minutes, and then dried in a hot air dryer at 60°C for 60 minutes. Then, dry heat setting is performed at 160°C for 2 minutes, and the tubular knitted fabric after dry heat setting is placed in a dyeing solution to which disperse dye Kayalon Polyester Blue UT-YA manufactured by Nippon Kayaku: 1.3% by weight is added and the pH is adjusted to 5.0, or a dyeing solution to which cationic dye Kayacryl Blue 2RL-ED manufactured by Nippon Kayaku: 1.0% by weight is added and the pH is adjusted to 4.0, and dyeing is performed under the conditions of a bath ratio of 1:100, a dyeing temperature of 130°C, and a dyeing time of 60 minutes.

The dyed tubular original fabric was used as the sample. The Minolta spectrophotometer CM-3700d was used to measure the L value three times for one sample under the D65 light source, 10° viewing angle, and SCE (specular reflection exclusion method) optical conditions. The average value rounded to the second decimal place was set as the L value of the sample. This operation was performed on 10 randomly sampled samples, and the variation rate was calculated from the L value average and standard deviation of the 10 samples. When the L value variation rate of the 10 samples was less than 5.0%, it was judged that there was no uneven dyeing.

O. Hairiness

Using a multi-point hairiness counter (MFC-120 manufactured by Toray Engineering Co., Ltd.), the fiber sample is run at 600 m/min, and the hairiness count displayed on the counter is measured for 10,000 meters. In addition, a warp reed tooth (stainless steel, 1 mm interval between reed teeth) is set just in front of the measuring point, and the fiber is passed through it. This measurement is repeated 10 times, and the average value of 10,000 meters is set as the hairiness count. If the hairiness count is less than 10/10,000 meters, it is considered to be passed.

P. Water absorption and quick drying

The tubular knitted original fabric produced according to the method described in G and subjected to hot water treatment is kept at a temperature of 20°C and a relative humidity of 65% for 24 hours, and the mass is set. The mass is set as w _a . Then, 0.3 ml of water is dripped on the center of the sample and the mass is measured. The mass is set as w _{0 min} . The moment when water is dripped on the sample is set as 0 min, and the mass of the sample is measured at 5-minute intervals. The mass is set as w _{n min} . Here, n min represents an arbitrary time for measuring the mass of the sample, and represents a 5-minute interval of 5 min, 10 min, and 15 min. The moisture residual rate WR at any time is calculated by formula (5).

WR=[(w _{0 points} - _{w n points} )/(w _{0 points} -w _a )]×100‧‧‧(5)

If the time for which the moisture residual rate WR calculated by formula (5) is less than 30% is less than 60 minutes, it is considered to have water absorption and quick drying properties.

Q.Maintenance of moisture absorption before and after hot water treatment

From the △MR after hot water treatment calculated in item G, subtract the △MR difference before and after hot water treatment calculated in item F to evaluate the change in fiber moisture absorption before and after hot water treatment. If the △MR change is less than 2.0%, it is considered that the fiber moisture absorption is maintained before and after hot water treatment.

(Implementation Example 1)

Polyethylene terephthalate (melting viscosity 120Pa‧s, melting point 254℃) was set as the sea part, and polybutylene terephthalate (melting viscosity 50Pa‧s, melting point 217℃) copolymerized with 50 wt% of polyethylene glycol (PEG6000S manufactured by Sanyo Chemical Industries) with a number average molecular weight of 8300g/mol was set as the island part. After the polymers of the sea part and the island part were melted at a spinning temperature of 285℃, they were measured in a way that the weight ratio of the sea-island ratio became 80:20, and flowed into the nozzle assembly assembled by the composite spinning nozzle shown in Figure 3, and the inflowing polymer was discharged from the discharge hole (hole diameter 0.30mm, hole number 36 holes) in a way that the number of island parts arranged on the outermost periphery was 3 islands and the total number of islands was 3 islands. The discharged composite polymer stream was cooled and solidified by a cooling device, and after the water-containing oil was supplied from the oil supply device, it was taken up at the circumferential speed of the first roll of the traction roll of 2000m/min, the circumferential speed of the second roll of the stretching roll of 2000m/min, and the winding speed of the winding machine of 2000m/min, and the polyester fiber of 200dtex-36 yarn count undrawn yarn was obtained. Then, the undrawn yarn was stretched under the conditions of 90℃ of the first roll temperature, 130℃ of the second roll temperature, and 2.38 times the stretching ratio expressed by the circumferential speed ratio of the first roll and the second roll, and the polyester fiber stretched yarn of 84dtex-36 yarn count was obtained. In the fiber cross section of the obtained polyester fiber, the ratios of the length of each line segment to the average length of each line segment were 0.97, 1.03, and 0.99 for the triangle obtained by connecting the centroids arranged at the outermost island part with line segments, and it was confirmed that the figure obtained by connecting the centroids arranged at the outermost island part with line segments was an equilateral triangle. The evaluation results of the obtained polyester fiber are shown in Table 1.

(Example 2)

Except that the sea portion was set to polyethylene terephthalate (melt viscosity 170 Pa‧s, melting point 244°C) copolymerized with 1.5 mol% of 5-sulfonated sodium salt of isophthalic acid and 1.0 wt% of polyethylene glycol (PEG1000 manufactured by Sanyo Chemical Industries) with a number average molecular weight of 1000 g/mol, the rest was carried out under the same conditions as in Example 1 to obtain a polyester fiber drawn yarn with a count of 84 dtex-36. For the triangle obtained by connecting the centroids arranged at the outermost island portion with line segments, the ratios of the lengths of each line segment to the average value of the lengths of each line segment were 0.99, 1.02, and 0.99, confirming that the figure obtained by connecting the centroids arranged at the outermost island portion with line segments was an equilateral triangle. The evaluation results of the obtained polyester fiber are shown in Table 1.

(Implementation Example 3)

Except that the number of holes of the discharge hole was set to 72 holes, an unstretched polyester fiber of 155dtex-72 yarn count was obtained, and the unstretched yarn obtained was stretched at a stretching ratio of 1.84 times, the rest were in accordance with the same conditions as Example 2, and a stretched polyester fiber of 84dtex-72 yarn count was obtained. For the triangle obtained by connecting the centroids arranged in the outermost island part with line segments, the ratios of the lengths of each line segment to the average length of each line segment were 0.99, 0.99, and 1.02, and it was confirmed that the figure obtained by connecting the centroids arranged in the outermost island part with line segments was an equilateral triangle. The evaluation results of the obtained polyester fiber are shown in Table 1.

(Implementation Example 4)

Except that the number of discharge holes was set to 14 holes, an unstretched polyester fiber of 258dtex-14 yarn count was obtained, and the unstretched yarn was stretched at a stretching ratio of 3.07 times, the rest were in accordance with the same conditions as Example 2 to obtain a stretched polyester fiber yarn of 84dtex-14 yarn count. For the triangle obtained by connecting the centroids arranged in the outermost island part with line segments, the ratios of the lengths of each line segment to the average value of the lengths of each line segment were 0.97, 1.00, and 1.03, confirming that the figure obtained by connecting the centroids arranged in the outermost island part with line segments is an equilateral triangle. The evaluation results of the obtained polyester fiber are shown in Table 1.

(Example 5)

Except that the sea-island ratio was set to 50:50 by weight, the rest was in accordance with the same conditions as Example 3, and a polyester fiber stretch yarn of 84dtex-72 yarn count was obtained. For the triangle obtained by connecting the centroids arranged in the outermost island part with line segments, the ratios of the lengths of each line segment to the average length of each line segment were 1.00, 0.99, and 1.01, confirming that the figure obtained by connecting the centroids arranged in the outermost island part with line segments is an equilateral triangle. The evaluation results of the obtained polyester fiber are shown in Table 1.

(Implementation Example 6)

Except that the sea portion was set to polyethylene terephthalate (melt viscosity 40Pa‧s, melting point 254℃), the rest were in accordance with the same conditions as Example 1, and a polyester fiber stretched yarn with 84dtex-36 yarn count was obtained. For the triangle obtained by connecting the centroids arranged on the outermost island portion with line segments, the ratios of the lengths of each line segment to the average length of each line segment were 0.98, 1.03, and 0.99, confirming that the figure obtained by connecting the centroids arranged on the outermost island portion with line segments is an equilateral triangle. The evaluation results of the obtained polyester fiber are shown in Table 1.

(Implementation Example 7)

Except that the sea portion was set to polyethylene terephthalate (melt viscosity 40Pa‧s, melting point 254℃), and the sea-island ratio was set to 50:50 by weight, the rest was in accordance with the same conditions as Example 3, and a polyester fiber stretch yarn of 84dtex-72 filaments was obtained. For the triangle obtained by connecting the centroids arranged in the outermost island portion with line segments, the ratios of the lengths of each line segment to the average length of each line segment were 1.03, 1.01, and 0.97, confirming that the figure obtained by connecting the centroids arranged in the outermost island portion with line segments is an equilateral triangle. The evaluation results of the obtained polyester fiber are shown in Table 1.

(Implementation Example 8)

Except that the discharge hole was set to 0.23mm in diameter and 96 holes, an unstretched polyester fiber with a yarn count of 115dtex-96 was obtained, and the unstretched yarn was stretched at a stretching ratio of 1.72 times, the rest were in accordance with the same conditions as Example 3 to obtain a stretched polyester fiber yarn with a yarn count of 66dtex-96. For the triangle obtained by connecting the centroids arranged in the outermost island part with line segments, the ratios of the lengths of each line segment to the average length of each line segment were 0.99, 1.01, and 0.99, confirming that the figure obtained by connecting the centroids arranged in the outermost island part with line segments is an equilateral triangle. The evaluation results of the obtained polyester fiber are shown in Table 1.

(Implementation Example 9)

Except that the discharge hole was set to a hole diameter of 0.20 mm and the number of holes was 144, an unstretched polyester fiber with a yarn count of 88 dtex-144 was obtained, and the unstretched yarn was stretched at a stretching ratio of 1.57 times, the rest were in accordance with the same conditions as Example 3, and a stretched polyester fiber with a yarn count of 56 dtex-144 was obtained. For the triangle obtained by connecting the centroids arranged in the outermost island part with line segments, the ratios of the lengths of each line segment to the average length of each line segment were 0.98, 1.03, and 0.99, confirming that the figure obtained by connecting the centroids arranged in the outermost island part with line segments is an equilateral triangle. The evaluation results of the obtained polyester fiber are shown in Table 2.

(Example 10)

Polyethylene terephthalate (melting viscosity 68 Pa‧s, melting point 251°C) copolymerized with 16% by weight of polyethylene glycol (PEG6000S manufactured by Sanyo Chemical Industries) having a number average molecular weight of 8300 g/mol was set as the sea part, and polyethylene terephthalate (melting viscosity 120 Pa‧s, melting point 254°C) was set as the island part. After the polymers of the sea part and the island part were melted at a spinning temperature of 285°C, they were measured in a manner such that the weight ratio of the sea-island ratio became 90:10, and flowed into the nozzle assembly assembled in the composite spinning nozzle shown in Figure 3, and the inflowing polymer was discharged from the discharge hole (hole diameter 0.30 mm, number of holes 36 holes) in a manner such that the number of island parts arranged on the outermost periphery was 3 islands and the total number of islands was 3 islands. The discharged composite polymer stream was cooled and solidified by a cooling device, and after the water-containing oil was supplied from the oil supply device, it was taken up at the circumferential speed of the first roll of the pulling roll of 2000m/min, the circumferential speed of the second roll of the stretching roll of 2000m/min, and the winding speed of the winding machine of 2000m/min, and the polyester fiber of 215dtex-36 yarn count undrawn yarn was obtained. Then, the undrawn yarn was stretched under the conditions of 90℃ of the first roll temperature, 130℃ of the second roll temperature, and 2.48 times the stretching ratio expressed by the circumferential speed ratio of the first roll and the second roll, and the polyester fiber stretched yarn of 84dtex-36 yarn count was obtained. For the triangle obtained by connecting the centroids arranged at the outermost island part with line segments, the ratios of the lengths of each line segment to the average lengths of each line segment were 0.98, 1.02, and 0.99, confirming that the figure obtained by connecting the centroids arranged at the outermost island part with line segments is an equilateral triangle. The evaluation results of the obtained polyester fiber are shown in Table 2.

(Implementation Example 11)

The sea part was set to polyethylene terephthalate (melting viscosity 170 Pa‧s, melting point 244°C) copolymerized with 1.5 mol% of 5-sulfonated sodium salt of isophthalic acid and 1.0 wt% of polyethylene glycol (PEG1000 manufactured by Sanyo Chemical Industries) with a number average molecular weight of 1000 g/mol. Then, 20 wt% of polyvinyl pyrrolidone (Luviskol K3 0SP manufactured by BASF, K value = 30) was added to polycaprolactam without additives to prepare polycaprolactam masterbatch chips. Next, the master batch fragments were mixed with the additive-free polycaprolactam (relative viscosity of sulfuric acid 2.71, melting point 220°C) to prepare a polycaprolactam mixed polymer with a polyvinyl pyrrolidone addition rate of 5.0% by weight, and the mixed polymer (melting viscosity 130Pa‧s, melting point 220°C) was set as the island part. Except that the polymers of the sea part and the island part formed the above combination and the sea-island ratio was set to 50:50 by weight, the rest were in accordance with the same conditions as in Example 2 to obtain a polyester fiber stretched yarn of 84dtex-36 yarn count. For the triangle obtained by connecting the centroids arranged at the outermost island with line segments, the ratios of the lengths of each line segment to the average length of each line segment were 0.98, 1.02, and 0.99, confirming that the figure obtained by connecting the centroids arranged at the outermost island with line segments is an equilateral triangle. The evaluation results of the obtained polyester fiber are shown in Table 2.

(Example 12)

Except that the island part was set to "PEBAX MH1657" made by ARKEMA (melt viscosity 45Pa‧s, melting point 203℃), the rest were in accordance with the same conditions as Example 2, and a polyester fiber stretched yarn with 84dtex-36 yarn count was obtained. For the triangle obtained by connecting the centroids arranged in the outermost island part with line segments, the ratio of each line segment length to the average value of each line segment length was 1.01, 1.01, and 0.98, confirming that the figure obtained by connecting the centroids arranged in the outermost island part with line segments is an equilateral triangle. The evaluation results of the obtained polyester fiber are shown in Table 2.

(Implementation Example 13)

Except for the polymer being discharged from the discharge hole (hole diameter 0.30 mm, hole number 72 holes) in the jetting assembly of the composite spinning nozzle assembly shown in FIG3 in accordance with the formation of the sea-island composite form in which the number of islands arranged at the outermost periphery is 5 islands and the total number of islands is 6 islands, the rest are in accordance with the same conditions as in Example 3, and a polyester fiber drawn yarn of 84 dtex-72 filaments is obtained. In the fiber cross section of the obtained polyester fiber, for the pentagon obtained by connecting the center of gravity arranged at the outermost island portion with a line segment, the ratio of each line segment length to the average value of each line segment length is 1.01, 1.00, 0.98, 0.99, 1.02, and it is confirmed that the figure obtained by connecting the center of gravity arranged at the outermost island portion with a line segment is a regular pentagon. The evaluation results of the obtained polyester fiber are shown in Table 2.

(Example 14)

Except for the polymer flowing into the jet assembly of the composite spinning nozzle assembly shown in FIG3 , which is formed in a sea-island composite form with 9 islands arranged at the outermost periphery and a total of 12 islands, and being discharged from the discharge hole (hole diameter 0.30 mm, number of holes 36 holes), the rest are in accordance with the same conditions as in Example 2, and a polyester fiber stretched yarn of 84 dtex-36 yarn count is obtained. In the fiber cross section of the obtained polyester fiber, the ratios of the length of each line segment to the average length of each line segment were 1.03, 1.01, 0.98, 0.99, 1.00, 1.00, 0.98, 0.99, and 1.02 for the octagon obtained by connecting the centroids arranged at the outermost island part with line segments, and it was confirmed that the figure obtained by connecting the centroids arranged at the outermost island part with line segments was a regular octagon. The evaluation results of the obtained polyester fiber are shown in Table 2.

(Example 15)

Except for setting the sea-island ratio to 65:35 by weight, the rest were in accordance with the same conditions as Example 2 to obtain a polyester fiber stretched yarn of 84dtex-36 yarn count. For the triangle obtained by connecting the centroids arranged in the outermost island part with line segments, the ratios of the lengths of each line segment to the average length of each line segment were 1.01, 0.98, and 1.01, confirming that the figure obtained by connecting the centroids arranged in the outermost island part with line segments is an equilateral triangle. The evaluation results of the obtained polyester fiber are shown in Table 2.

(Comparative example 1)

Polyethylene terephthalate (melting viscosity 120Pa‧s, melting point 254℃) was set as the sea part, and polybutylene terephthalate (melting viscosity 50Pa‧s, melting point 217℃) copolymerized with 50% by weight of polyethylene glycol (PEG6000S manufactured by Sanyo Chemical Industries) with a number average molecular weight of 8300g/mol was set as the island part. After the polymers of the sea part and the island part were melted at a spinning temperature of 285℃, they were measured in a way that the weight ratio of the sea and island ratio became 80:20, and flowed into the nozzle assembly assembled in the composite spinning nozzle shown in Figure 3, and the inflowing polymer was discharged from the discharge hole (hole diameter 0.30mm, number of holes 36 holes) in a core-sheath composite form in which the number of islands arranged on the outermost periphery was 1 island and the total number of islands was 1 island. The discharged composite polymer flow is cooled and solidified by a cooling device, and after the water-containing oil is supplied from the oil supply device, it is wound at a circumferential speed of 2000m/min for the first roll of the pulling roll, a circumferential speed of 2000m/min for the second roll of the stretching roll, and a winding speed of 2000m/min for the winding machine, and a polyester fiber of 200dtex-36 yarn count undrawn yarn is obtained. Then, the undrawn yarn is stretched under the conditions of 90°C for the first roll, 130°C for the second roll, and a stretching ratio of 2.38 times expressed by the circumferential speed ratio of the first roll to the second roll, and a polyester fiber stretched yarn of 84dtex-36 yarn count is obtained. In the fiber cross section of the obtained polyester fiber, since the total number of islands is 1, it is impossible to obtain a figure connected by a line segment from the center of gravity of the outermost island. Therefore, the obtained polyester fiber has sea cracks when absorbing moisture, and uneven dyeing or hairiness occurs when forming fabrics. In addition, the polymer of the island is dissolved from the sea cracks, and the moisture absorption and release properties after hot water treatment are also poor. The evaluation results of the obtained polyester fiber are shown in Table 3.

(Comparative example 2)

Except that the sea portion is set to polyethylene terephthalate (melt viscosity 500Pa‧s, melting point 254℃), the rest is in accordance with the same conditions as Example 1, and a polyester fiber stretched yarn with 84dtex-36 yarn count is obtained. For the triangle obtained by connecting the centroids arranged at the outermost island portion with line segments, the ratios of the lengths of each line segment to the average length of each line segment are 1.10, 1.04, and 0.86. Because the figure obtained by connecting the centroids arranged at the outermost island portion with line segments is not an equilateral triangle, the obtained polyester fiber has sea cracks when absorbing moisture, and uneven dyeing or hairiness occurs when forming a fabric. In addition, the polymer of the island portion is dissolved from the sea cracks, and the moisture absorption and release properties after hot water treatment are also poor. The evaluation results of the obtained polyester fiber are shown in Table 3.

(Comparative example 3)

Except for setting the sea-island ratio to 40:60 by weight, the rest are in accordance with the same conditions as Example 1 to obtain a polyester fiber stretch yarn with 84dtex-36 yarn count. For the triangle obtained by connecting the center of gravity arranged in the outermost island part with a line segment, the ratio of each line segment length to the average value of each line segment length is 1.09, 0.96, and 0.95. Because the figure obtained by connecting the center of gravity arranged in the outermost island part with a line segment is not an equilateral triangle, the obtained polyester fiber has sea cracks when absorbing moisture, and uneven dyeing or hairiness occurs when forming a fabric. In addition, because the amount of polyethylene terephthalate in the sea part is relatively small, the water absorption and quick-drying properties are poor. The evaluation results of the obtained polyester fiber are shown in Table 3.

(Comparative example 4)

Except that the number of the ejection holes was set to 10 holes to obtain an unstretched polyester fiber of 270 dtex-10 yarn count, and the unstretched yarn was stretched at a stretching ratio of 3.21 times, the rest was carried out under the same conditions as in Example 2 to obtain a stretched polyester fiber of 84 dtex-10 yarn count. For the triangle obtained by connecting the centroids arranged at the outermost island with line segments, the ratios of the lengths of each line segment to the average length of each line segment are 0.98, 1.02, and 1.00. It is confirmed that the figure obtained by connecting the centroids arranged at the outermost island with line segments is an equilateral triangle, but because the sea part is thick, the moisture absorption and release are poor, and because the single fiber is thick and the fiber is rigid, the feel of the obtained fabric is also poor. The evaluation results of the obtained polyester fiber are shown in Table 3.

(Industrial availability)

The polyester fiber of the present invention can disperse the stress generated by the fiber volume expansion when absorbing moisture, thereby inhibiting cracks on the fiber surface. Therefore, when knitted/woven fabrics are formed, uneven dyeing or hairiness will not occur, resulting in excellent quality. In addition, since the moisture absorption is not reduced, it has excellent moisture absorption and is particularly suitable for clothing applications.

1: Kaibu

2a, 2b, 2c: Island area

3a, 3b, 3c: The fiber cross section is arranged in the outermost island part, and the connecting line segment between the intersection points (centers of gravity) of any two straight lines that divide the area of the adjacent island part into two equal parts

4: All islands located at the outermost periphery in the fiber cross section are circumscribed by two or more perfect circles (circumscribed circles)

5: A perfect circle circumscribed to an island with two or more points (circumscribed circle)

6: Minimum thickness of sea part

7: Minimum distance between islands

B: From the intersection point (center of gravity) of any two straight lines that divide the island area into two equal parts, draw a straight line toward any fiber surface, and the intersection point with the outer periphery of the island

Da, Db: The intersection point (center of gravity) of any two straight lines that divide the island area into two equal parts toward any adjacent island, and the intersection point with the outer periphery of the island

F: Draw a straight line from the intersection point (center of gravity) of any two straight lines that divide the island area into two equal parts toward any fiber surface, and the intersection point with the fiber surface

Ga, Gb, Gc: The intersection point (center of gravity) of any two straight lines that divide the island area into two equal parts

Claims (3)

A fiber is a sea-island type composite fiber whose main constituent component of the sea portion is an aromatic polyester, and the moisture absorption and release parameter ΔMR is 2.0% or more. The figure obtained by connecting the centroids of the island portions arranged at the outermost periphery in the fiber cross section with line segments is a regular polygon with the centroid as the vertex; the ratio C/L of the curvature radius C (μm) of the edge on the fiber surface side outside the island portions arranged at the outermost periphery in the fiber cross section and the radius L (μm) of the circumscribed circle containing the island portions arranged at the outermost periphery in the fiber cross section is 0.50~0.90. The fiber of claim 1, wherein the number of island portions arranged at the outermost periphery in the cross-section of the fiber is an odd number. A fiber product comprising the island-in-the-sea composite fiber of claim 1 or 2.