JP2022040592A - Method for producing fibers - Google Patents

Abstract

To provide efficiently fibers exhibiting excellent capacity of water absorption at a room temperature into a polymer for enhanced productivity.SOLUTION: A method for producing fibers comprises directly melt-spinning a polyester composition A and a polyester composition B having different compositions in which crystal melting temperatures of both the compositions obtained by differential scanning calorimetry are in the range of 120 to 200°C and crystal melting heat amounts of both the compositions are in the range of 20 to 45 J/g, after melt-kneading both the compositions using an extruder.SELECTED DRAWING: None

Description

The present invention relates to a method for efficiently producing a fiber having excellent water absorption capacity.

Materials that can absorb a large amount of water inside the polymers that make up the fibers are in demand from a wide range of fields such as diaper applications and face mask applications, and have extremely high industrial value. This is because the amount of water absorption required for these applications is extremely high, and the performance of the fiber structure, which does not have the ability to absorb water inside the polymer and only absorbs water into the fiber surface layer or the woven or knitted structure, is insufficient.

Sodium polyacrylate is well known as a polymer having excellent water absorption ability inside the polymer, but its use as a fiber requires solution spinning and post-crosslinking treatment (Patent Document 1), so that the molding cost is very high. It is expensive and difficult to develop as a textile product. In addition, since melt spinning is not possible, composite fibers with nylon, polyester compositions, or the like cannot be obtained.

Therefore, as a fiber obtained by melt spinning and capable of absorbing water inside the polymer, a composite fiber partially using polybutylene terephthalate obtained by copolymerizing a large amount of a polyalkylene glycol compound has been proposed (Patent Document). 2, 3).

However, it has been found that the composite fibers described in Patent Documents 2 and 3 have insufficient water absorption capacity inside the polymer constituting the fibers for use in applications such as diapers and face masks. That is, the amount of water absorbed into the polymer constituting these composite fibers per hour in water at 30 ° C. was less than 0.4 g per 1 g of the composite fiber, but this level of water absorption meets the demands of the industry. I can't.

Therefore, as a result of diligent studies to develop a polyester composition having excellent water absorption capacity inside the polymer and capable of melt spinning, the water absorption per hour in water at 30 ° C. was 0.4 g per 1 g of the polymer. We have invented a polyester composition having the above-mentioned low crystallinity and low crystallinity melting temperature (Patent Document 4). However, when performing melt spinning of this polyester composition, it was found that long-term drying in the state of polymer pellets and the addition of a large amount of anti-fusing agent were indispensable, and the productivity was not excellent. ..

Japanese Unexamined Patent Publication No. 4-80234 Japanese Patent Application Laid-Open No. 2003-253100 Japanese Unexamined Patent Publication No. 2004-137418 Japanese Patent Application No. 2020-536696

An object of the present invention is to overcome the problems of prolonged drying of polymer pellets and addition of a large amount of anti-fusing agent, and to provide an efficient method for producing a fiber having an excellent water absorption capacity inside the polymer. ..

The above-mentioned problems are polyester composition A and polyester composition having different compositions, in which the crystal melting temperature obtained by differential scanning calorimetry is 120 to 200 ° C. and the crystal melting heat is in the range of 20 to 45 J / g. B is achieved by a fiber production method characterized by directly melt-spinning after melt-kneading using an extruder.

According to the present invention, by using two kinds of polyester compositions that can be dried in a short time under high temperature conditions and do not cause severe pellet fusion, the productivity at the time of spinning is significantly improved, and the polyester composition is melted into a fiber form. By melt-kneading two kinds of polyester compositions at the time of processing, they are modified into polyester compositions having excellent water absorption capacity and low crystal melting temperature, and then directly melt-spun, which is extremely excellent at room temperature. It is possible to produce fibers that exhibit the ability to absorb water inside the polymer. The water-absorbing fiber produced by this method can be suitably used for products for the purpose of water retention and cooling such as diapers, face masks, cooling agents, and cooling sheets.

In the fiber manufacturing method of the present invention, polyester compositions having different compositions have a crystal melting temperature of 120 to 200 ° C. and a crystal melting heat of 20 to 45 J / g, which are obtained by differential scanning calorimetry. It is essential that A, the polyester composition and B are directly melt-spun after melt-kneading using an extruder. Different compositions mean that the composition of the dicarboxylic acid residue or diol residue that composes polyester is different, or that the composition of both residues is the same (the same kind of combination) but the composition ratio is different. Point to.

In order to significantly improve the productivity at the time of spinning, the polyester compositions A and B can be dried in a short time under high temperature conditions, and severe pellet fusion does not occur, and the polyester composition is melt-extruded from the pellet feeder immediately after drying. It is important that the polyester composition is capable of supplying pellets. In order to complete the drying of the pellets of the polyester composition quickly, that is, within 24 hours, it is necessary to raise the drying temperature to about 105 ° C. For example, the crystal melting temperature is required so that the pellets do not fuse when dried at 105 ° C. Should be approximately 120 ° C or higher. The crystal melting temperature is more preferably 130 ° C. or higher, further preferably 140 ° C. or higher, and most preferably 150 ° C. or higher because the drying temperature can be raised and the pellets can be dried more quickly. On the other hand, in order to exhibit excellent water absorption capacity in the produced fiber, the kneaded product of the polyester compositions A and B must be set to exhibit low crystallinity and low crystallinity melting temperature. When the crystal melting temperature of either one of the polyester compositions A and B is higher than 200 ° C., the kneaded product has low crystallinity at a level at which the kneaded product exhibits water absorption capacity unless the crystal melting temperature of the other is set to less than 120 ° C. Since the low crystal melting temperature cannot be reached, the productivity during spinning is reduced. From this, in order to achieve the improvement of productivity, it is essential that the crystal melting temperature of the polyesters A and B is 200 ° C. or lower, and preferably 180 ° C. or lower.

Even if the crystal melting temperature of the polyester compositions A and B is 120 ° C. or higher, if the heat of crystal melting is less than 20 J / g, the pellets are deformed and melted when dried at 105 ° C. or higher. .. Therefore, long-term drying at a low temperature is required, and the production efficiency is extremely lowered. Therefore, it is essential that the amount of heat of crystal melting of the polyester compositions A and B is 20 J / g or more. Further, it is more preferable that the amount of heat for crystallization melting is 35 J / g or more because crystallization in pellets proceeds rapidly and the drying time can be shortened. On the other hand, in order to exhibit excellent water absorption capacity in the produced fiber, the kneaded product of polyesters A and B must be set to exhibit low crystallinity and low crystallinity melting temperature. When the amount of heat of crystal melting of either polyester A or B is higher than 45 J / g, the amount of heat of crystal melting of the other is 20 J / g in order to bring the kneaded material to a level of low crystallinity and low crystal melting temperature at which water absorption capacity is exhibited. A polyester composition of less than g must be selected, reducing productivity during spinning. From this, it is essential that the amount of heat of crystal melting of the polyesters A and B is 45 J / g or less in order to achieve the improvement of productivity.

From the above, it is essential that the polyester compositions A and B have a crystal melting temperature of 120 to 200 ° C. and a crystal melting heat amount of 20 to 45 J / g, but they are excellent in the produced fibers. In order to develop the water absorption capacity, the kneaded polyester A and B are preferably set to have low crystallinity (less than 12 J / g) and low crystal melting temperature (less than 120 ° C.). When the polyester compositions A and B are the same composition, the composition of the kneaded product does not change at all, and excellent water absorption capacity is exhibited while the crystal melting temperature is in the range of 120 to 200 ° C. and the crystal melting heat amount is in the range of 20 to 45 J / g. There is nothing to do. Only by melt-kneading polymers with different compositions, the kneaded product has a lower crystal melting temperature and crystal melting heat than the base composition, and can exhibit excellent water absorption capacity. Therefore, the polyester composition. It is essential that A and B have different compositions.

In the fiber production method of the present invention, it is essential that the polyester compositions A and B are melt-kneaded using an extruder and then directly melt-spun. Immediately after melt-kneading, the kneaded product of the polyester compositions A and B quickly changes to low crystallinity, low crystal melting temperature, and high water absorption, so it should be processed again into pellets or the like without spinning and stored. Will result in a significant reduction in productivity.

In the fiber production method of the present invention, the weight ratio of the polyester composition A: B at the time of melt-kneading is preferably in the range of 25:75 to 75:25. If the weight ratio on the other hand is less than 25 or larger than 75, kneading may not proceed sufficiently depending on the specifications of the melt extruder, and the fineness variation during spinning may increase and the quality of the fiber may deteriorate. In the range of A: B = 25: 75 to 75:25, the fiber has excellent water absorption capacity not only in kneading by a general twin-screw kneading extruder but also in a simple pressure melter type heating melt extruder. Can be obtained with high quality, the range of application of the spinning machine is widened, and the productivity is improved.

The fiber obtained in the fiber production method of the present invention may be a single component yarn composed of only the kneaded product of the polyester compositions A and B, but the polyester compositions A and B are directly melt-spun after melt-kneading. At this time, the thermoplastic resin C may be separately melt-extruded and merged in the spinneret to obtain a composite fiber composed of two components of the kneaded polyester compositions A and B and the thermoplastic resin C. A single-component yarn composed of only a kneaded product of the polyester compositions A and B is extremely excellent in water absorption performance, but exhibits low crystallinity and low crystal melting temperature, and requires cost control such as temperature control for product storage. Therefore, the core-sheath composite fiber or C-type composite fiber in which the thermoplastic resin C is separately melt-extruded and merged in the mouthpiece, and the kneaded material of the polyester compositions A and B is arranged as the core component and the thermoplastic resin C is used as the sheath component. , It is more preferable to produce in the form of a star-shaped composite fiber.

At least one of the polyester compositions A and B used in the fiber production method of the present invention has a volume increase when the pellets are allowed to stand at 50 ° C. under a nitrogen stream for 1 week and then immersed in ion-exchanged water at 30 ° C. for 1 hour. The rate is preferably in the range of 1 to 50%. When the volume increase rate of the polyester compositions A and B is less than 0.1%, that is, when none of the polyester compositions A and B show water absorption performance, the kneaded product of the polyester compositions A and B exhibits excellent water absorption performance. That is difficult. On the other hand, if the volume increase rate is excessively high, that is, if the water absorption performance is unnecessarily high, it is easy to absorb water during pellet storage, and the pellet drying time tends to be long. The rate is preferably 50% or less, more preferably 15% or less.

The polyester compositions A and B used in the fiber production method of the present invention preferably have a weight average molecular weight in the range of 35,000 to 80,000. If the weight average molecular weight is out of this range, kneading does not proceed sufficiently depending on the specifications of the melt extruder, and the fluctuation in fineness during spinning becomes large, and there is a concern that the quality of the fiber may deteriorate.

None of the polyester compositions A and B used in the fiber production method of the present invention requires the addition of an extreme anti-fusing agent. When the fiber is produced by directly spinning the polyester composition itself having a low crystallinity and a low crystallinity temperature having excellent water absorption capacity without using the fiber production method of the present invention, it takes a long time to dry the pellets. In addition, it is necessary to add a large amount of aliphatic metal salt as a fusion inhibitor to forcibly dry and spin while suppressing deformation and fusion of pellets. Conventionally, magnesium stearate, aluminum stearate, and zinc stearate have been preferably used as the anti-fusing agent, but an addition amount of more than 20 ppm is required as the metal atom content regardless of the type of metal salt. It is very disadvantageous in terms of manufacturing process and cost. On the other hand, the polyester compositions A and B used in the fiber production method of the present invention can be dried for a short time without adding a large amount of anti-fusing agent, and the production process is simple and cost-effective. The total of the metal atom content, particularly the magnesium metal atom content, the aluminum metal atom content, and the zinc metal atom content is preferably 20 ppm or less, more preferably 10 ppm or less, and further preferably 5 ppm or less. It is preferably less than 0.1 ppm, most preferably less than 0.1 ppm.

Hereinafter, the copolymerized polyester composition suitable for the polyester compositions A and B used in the fiber production method of the present invention will be described in detail.

The dicarboxylic acid residues constituting the polyester compositions A and B include aromatic dicarboxylic acid compounds typified by terephthalic acid and isophthalic acid, aliphatic dicarboxylic acid compounds typified by adipic acid and sebacic acid, and cyclohexanedicarboxylic acid. It is preferable to contain a residue derived from a representative alicyclic dicarboxylic acid compound. For example, it is more preferable that it is mainly composed of terephthalic acid and isophthalic acid residues from the viewpoint of excellent thermal stability.

The type of diol residue constituting the polyester compositions A and B is not particularly limited, but is derived from any one of 1,4-butanediol, 1,3-propanediol, and ethylene glycol from the viewpoint of excellent thermal stability. It preferably contains residues. Among them, it is most preferable that the polyester composition is composed only of residues derived from 1,4-butanediol because it is easy to set the crystal melting temperature of the polyester composition in the range of 120 to 200 ° C.

In order to exhibit excellent water absorption performance in the kneaded product of the polyester compositions A and B, it is preferable that the polyester composition A and / or B contains a residue derived from the metal sulfonate group-containing isophthalic acid. Having a metal sulfonate group-containing isophthalic acid residue improves hydrophilicity and facilitates the development of water absorption capacity after kneading. From the viewpoint of improving the water absorption capacity, the copolymerization amount is preferably 5.0 mol% or more, and more preferably 10.0 mol% or more with respect to the total acid component. On the other hand, if the amount of the metal sulfonate group-containing isophthalic acid residue is excessive, the drying time is prolonged, and the fineness fluctuation during spinning becomes large and the quality of the fiber deteriorates. Therefore, the copolymerization amount may be 20 mol% or less. preferable.

Further, the polyester compositions A and B may contain polyethylene glycol. Since the polyester composition containing polyethylene glycol is excellent in molecular mobility and hydrophilicity, it contributes to the improvement of water absorption capacity after kneading. The contained polyethylene glycol may be copolymerized in the polyester or may be present in the polyester composition in an unreacted state. The polyethylene glycol contained in the polyester compositions A and B has a number average molecular weight of 1000 as measured by gel permeation chromatography from the viewpoint of achieving both efficient hydrophilicity improvement and quality after melt-kneading and spinning. The above is preferable, and the amount is preferably 10,000 or less. If the number average molecular weight is less than 1000, drying takes a long time, which is not preferable, and if it is larger than 10,000, the improvement in water absorption capacity is small, which is not preferable. If the polyethylene glycol contained in the polyester compositions A and B is excessive, the drying takes a long time. Therefore, the content is preferably 15.0% by weight or less, more preferably 10.0% by weight or less. .. Of course, it does not have to contain polyethylene glycol. The content described here can be determined by NMR measurement.

The polyester compositions A and B may contain terephthalic acid residues. The copolymerization of the terephthalic acid component improves the thermal stability of the polymer. However, if the terephthalic acid residue in either polyester composition A or B is higher than 80.0 mol% with respect to the total amount of acid, the other crystal melting temperature or crystal melting is performed in order to make the kneaded product low in crystallinity. Since the calorific value must be set low, the productivity during spinning is reduced. From this, it is preferable that the content of the terephthalic acid residue of the polyesters A and B is in the range of 80.0 mol% or less in order to achieve the improvement of productivity. Further, since the kneaded product of the polyester compositions A and B tends to have lower crystallinity, one of the polyester compositions contains a terephthalic acid residue in the range of 55.0 to 80.0 mol%, and the other is terephthalic acid. Most preferably, the acid residue is contained in the range of 0 to 5.0 mol%.

Further, the polyester compositions A and B may contain a residue of a dicarboxylic acid component selected from one of isophthalic acid, cyclohexanedicarboxylic acid, naphthalenedicarboxylic acid, adipic acid and sebacic acid. Among them, it is most preferable that the residue derived from isophthalic acid is contained in a specific range from the viewpoint that the calorific value of crystal melting of the polyester composition can be easily set in the range of 200 to 45 J / g. Since the kneaded product of the polyester compositions A and B tends to have low crystallinity, one of the polyester compositions contains these dicarboxylic acid components in the range of 35.0 mol% or less, and the other is 85.0 to 100. It is preferably contained in the range of 0 mol%. On the other hand, if it is more than 35.0 mol% or less than 85.0 mol%, it is difficult to set the crystal melting temperature to 120 ° C. or higher, which is not preferable.

In the fiber production method of the present invention, in order to finely control the physical properties of the kneaded product of the polyester compositions A and B, the polyester compositions A and B have a metal sulfonate group-containing isophthalic acid component, a terephthalic acid component, an isophthalic acid component and cyclohexane, respectively. It is preferable to use two or more kinds from the combination of the copolymerization component of any one of the dicarboxylic acid component, the naphthalenedicarboxylic acid component, the adipic acid component, and the sebacic acid component, and the polyethylene glycol as the contained component within the above-mentioned range. By combining these two or more, a synergistic effect can be obtained, and the water absorption capacity of the polyester compositions A and B kneaded products, that is, the produced fibers can be further improved. As a combination, it is preferable to use the metal sulfonate group-containing isophthalic acid component and polyethylene glycol at the same time, and it is more preferable to use the terephthalic acid component and the isophthalic acid component in addition.

Further, the polyester compositions A and B may be modified in various ways by adding a secondary additive. Specific examples of secondary additives include antioxidants, compatibilizers, plasticizers, UV absorbers, infrared absorbers, optical brighteners, mold release agents, antibacterial agents, nucleating agents, heat stabilizers, and charging. Examples include, but are not limited to, inhibitors, color inhibitors, modifiers, matting agents, defoaming agents, preservatives, gelling agents, latexes, fillers, inks, colorants, dyes, pigments, fragrances and the like. These secondary additives may be used alone or in combination of two or more. In particular, when the polyester compositions A and B contain polyethylene glycol, it is preferable to contain an antioxidant for the purpose of preventing the decomposition of polyethylene glycol. Preferred examples of the antioxidant include pentaerythritol-tetrakis (3- (3,5-di-t-butyl-4-hydroxyphenol) propionate) (BASF, IRGANOX1010), which is a hindered phenolic antioxidant. Be done.

When the thermoplastic resin C is separately used in the fiber manufacturing method of the present invention, the suitable polymer for the thermoplastic resin C is a thermoplastic polymer having a crystalline property that can be melt-spun in the range of 200 to 300 ° C. Preferred examples thereof include polyethylene terephthalate, polytrimethylene terephthalate, polybutylene terephthalate, nylon 6, nylon 66, nylon 610, polypropylene, polylactic acid, and blend polymers and copolymer polymers containing 50% or more of these as main components. , Not limited to these. When the thermoplastic resin C is used, it is preferable to have a high heat of crystal melting so that thermal deformation or fusion between single fibers does not occur from the thermoplastic resin C in the thermal stretching step or the false twisting step. Specifically, the amount of heat of crystal melting obtained by differential scanning calorimetry is preferably 20 J / g or more, and more preferably 40 J / g or more.

In the fiber manufacturing method of the present invention, the fiber may be manufactured by freely setting the area ratio of the thermoplastic resin C to the cross section of the fiber within a range in which the desired water absorption capacity can be achieved. The area ratio of the thermoplastic resin C is preferably 60% or less, more preferably 40% or less, in order to easily exert excellent water absorption capacity.

In the fiber manufacturing method of the present invention, the pellets of the dried polyester compositions A and B are simultaneously supplied to one melt spinning machine such as a pressure melter type or an extruder type, and weighed by a measuring pump while being melt-kneaded. .. After that, the polymer is introduced into a heated spinning pack in the spinning block, the molten polymer is filtered in the spinning pack, and discharged from the spinneret to form a fiber yarn. When the thermoplastic resin C is separately used to obtain a core-sheath composite fiber, a C-type composite fiber, or a star-shaped composite fiber, the thermoplastic resin C is separately supplied to a different melt spinning machine, weighed, and added in a spinning block. It is introduced into a warm spinning pack, the molten polymer is filtered in the spinning pack, and then merged with the kneaded polymer of the polyester compositions A and B to form a composite fiber structure, which is discharged from the spinneret to form a fiber thread.

In the fiber manufacturing method of the present invention, the fiber yarn discharged from the mouthpiece is cooled and solidified by a cooling device, taken up by a first godet roller, wound up by a winder via a second godet roller, and wound. It becomes a thread take-up. In addition, in order to improve spinning operability, productivity, and mechanical properties of the fiber, a heating cylinder or a heat insulating cylinder having a length of 2 to 20 cm may be installed at the lower part of the spinneret, if necessary. Further, the fiber thread may be lubricated using a lubrication device, or the fiber thread may be entangled using an entanglement device.

The spinning temperature of the melt spinning in the fiber manufacturing method of the present invention can be appropriately selected depending on the melting point and heat resistance of the polyester compositions A and B or the thermoplastic resin C, but is 220 to 300 ° C. Is preferable. When the spinning temperature is 220 ° C. or higher, the extensional viscosity of the fiber yarn discharged from the spinneret is sufficiently lowered to stabilize the discharge, and further, the spinning tension does not become excessively high and the yarn breakage is suppressed. It is preferable because it can be used. On the other hand, when the spinning temperature is 300 ° C. or lower, thermal decomposition during spinning can be suppressed, and deterioration of mechanical properties and coloring of the fiber can be suppressed, which is preferable.

The spinning speed of melt spinning in the fiber manufacturing method of the present invention can be appropriately selected depending on the composition of the polyester compositions A and B, the thermoplastic resin C, the spinning temperature, and the like. In the case of the two-step method in which melt spinning is performed once, winding is performed, and then stretching or false twisting is performed separately, the spinning speed is preferably 500 to 6000 m / min. When the spinning speed is 500 m / min or more, the running yarn is stable and the yarn breakage can be suppressed. On the other hand, when the spinning speed is 6000 m / min or less, the yarn breakage is not caused by the suppression of the spinning tension. , It is preferable because stable spinning can be performed. Further, in the case of the one-step method in which spinning and drawing are performed at the same time without winding once, the spinning speed is preferably 500 to 5000 m / min for the low-speed roller and 2500 to 6000 m / min for the high-speed roller. When the low-speed roller and the high-speed roller are within the above range, the running yarn is stable, yarn breakage can be suppressed, and stable spinning can be performed, which is preferable.

In the fiber manufacturing method of the present invention, when stretching is carried out by a one-step method or a two-step method, either a one-step stretching method or a two-step or more multi-step stretching method may be used. The heating method in drawing is not particularly limited as long as it is a device capable of directly or indirectly heating the running yarn. Specific examples of the heating method include, but are not limited to, heating rollers, hot pins, hot plates, hot water, liquid baths such as hot water, hot air, gas baths such as steam, and lasers. These heating methods may be used alone or in combination of two or more. As the heating method, control of the heating temperature, uniform heating of the running thread, contact with the heating roller, contact with the hot pin, contact with the hot plate, and immersion in the liquid bath are performed from the viewpoint of not complicating the device. It can be suitably adopted.

In the fiber manufacturing method of the present invention, the stretching temperature at the time of stretching can be appropriately selected depending on the strength, elongation and the like of the fiber after stretching, but is preferably 25 to 150 ° C. When the stretching temperature is 50 ° C. or higher, the yarn supplied for stretching is sufficiently preheated, the thermal deformation during stretching becomes uniform, the occurrence of fineness spots can be suppressed, the dyeing spots and fluff are few, and the quality is high. Is preferable because it becomes good. On the other hand, when the stretching temperature is 90 ° C. or lower, fusion and thermal decomposition of the fibers due to contact with the heating roller can be suppressed, and process passability and quality are good, which is preferable. Further, heat setting at 30 to 150 ° C. may be performed if necessary.

The draw ratio in the case of stretching can be appropriately selected depending on the elongation of the fiber before stretching, the strength and elongation of the fiber after stretching, and the like, but is 1.02 to 7.0 times. It is preferable to have. When the draw ratio is 1.02 times or more, it is preferable because the mechanical properties such as the strength and elongation of the fiber can be improved by stretching. On the other hand, when the draw ratio is 7.0 times or less, yarn breakage during stretching is suppressed and stable stretching can be performed, which is preferable.

Further, the stretching speed in the case of stretching can be appropriately selected depending on whether the stretching method is a one-step method or a two-step method. In the case of the one-step method, the speed of the high-speed roller at the spinning speed corresponds to the drawing speed. When stretching by the two-step method, the stretching speed is preferably 30 to 1000 m / min. When the drawing speed is 30 m / min or more, the running yarn is stable and the yarn breakage can be suppressed, which is preferable. On the other hand, when the stretching speed is 1000 m / min or less, yarn breakage during stretching is suppressed and stable stretching can be performed, which is preferable.

In the fiber manufacturing method of the present invention, when performing false twisting, so-called bulería processing, which uses both a one-stage heater and a two-stage heater, is appropriately selected in addition to the so-called woolly processing, which uses only a one-stage heater. be able to. The heating method of the heater may be either a contact type or a non-contact type. Specific examples of the false twisting machine include, but are not limited to, a friction disc type, a belt nip type, and a pin type.

In the fiber manufacturing method of the present invention, the heater temperature when performing false twisting is preferably 105 to 210 ° C. When the heater temperature is 105 ° C or higher, the yarn supplied for false twisting is sufficiently preheated, the thermal deformation due to stretching becomes uniform, the occurrence of fineness spots can be suppressed, and there are few dyeing spots and fluff. , It is preferable because the quality is good. On the other hand, when the heater temperature is 210 ° C. or lower, fusion and thermal decomposition of fibers due to contact with the heater are suppressed, so that there is little thread breakage and stains on the heater, and process passability and quality are improved. It is preferable because it is good.

The draw ratio in the case of false twisting can be appropriately selected depending on the elongation of the fiber before false twisting and the strength and elongation of the fiber after false twisting, but 1.01. It is preferably about 2.5 times. When the draw ratio is 1.01 times or more, it is preferable because the mechanical properties such as the strength and elongation of the fiber can be improved by stretching. On the other hand, when the draw ratio is 2.5 times or less, yarn breakage during false twisting is suppressed and stable false twisting can be performed, which is preferable.

Further, the processing speed in the case of performing false twisting can be appropriately selected, but is preferably 200 to 1000 m / min. When the processing speed is 200 m / min or more, the running yarn is stable and the yarn breakage can be suppressed, which is preferable. On the other hand, when the processing speed is 1000 m / min or less, yarn breakage during false twisting is suppressed and stable false twisting can be performed, which is preferable.

The form of the fiber obtained by the fiber manufacturing method of the present invention is not particularly limited, and may be any form such as monofilament, multifilament, and staple. In addition, processing such as false twisting and twisting may be carried out in the same manner as general fibers.

The form of the fiber structure using the fiber obtained by the fiber manufacturing method of the present invention is not particularly limited, and can be made into a woven fabric, a knitted fabric, a pile fabric, a non-woven fabric, a spun yarn, a stuffed cotton, or the like according to a known method. .. In the case of woven fabrics and knitted fabrics, any woven or knitted structure may be used, such as plain weave, twill weave, satin weave or their variations, warp knits, weft knits, circular knits, lace knits or their variations. It can be suitably adopted.

The fiber obtained by the fiber manufacturing method of the present invention may be combined with other fibers by cross-weaving or cross-knitting when forming a fiber structure, or may be used as a fiber structure after being made into a mixed fiber yarn with other fibers. good.

The fiber obtained by the fiber production method of the present invention may be dyed in any state of the fiber or the fiber structure. The dyeing method is not particularly limited, and a cheese dyeing machine, a liquid flow dyeing machine, a drum dyeing machine, a beam dyeing machine, a jigger, a high pressure jigger and the like can be preferably adopted according to a known method. There are no particular restrictions on the dye concentration and dyeing temperature, and known methods can be preferably adopted. Further, if necessary, refining may be performed before the dyeing process, or reduction cleaning may be performed after the dyeing process.

Hereinafter, the present invention will be described in more detail by way of examples, but the present invention is not limited to the following examples as long as the gist of the present invention is not exceeded. Further, the polyester composition used in the fiber production method of the present invention and the evaluation method of the obtained fiber are as follows.

A. Measurement of Crystal Melting Temperature and Crystal Melting Heat of Polyester Composition As a pretreatment, columnar polyester composition pellets with a diameter of 3.0 ± 1.5 mm and a height of 4.0 ± 1.0 mm were placed at 50 ° C. for 1 week under nitrogen. The crystal state was stabilized by allowing it to stand still, and the crystal melting temperature and the amount of heat of crystal melting were measured using a suggested scanning calorimeter.
Equipment: Q-2000 manufactured by TA Instruments
Temperature rise rate: 2 ° C / min Measurement temperature: From -20 ° C to 300 ° C.

B. Volume increase rate of polyester composition in water The volume increase rate of polyester composition in water was measured using a dry automatic densitometer and a pycnometer. As a pretreatment, columnar polyester composition pellets having a diameter of 3.0 ± 1.5 mm and a height of 4.0 ± 1.0 mm were allowed to stand at 50 ° C. under nitrogen for 1 week to stabilize the crystalline state (). Preprocessing). 0.8 g of the pretreated polyester composition was weighed, and the volume of the polyester composition before immersion in water was determined using a dry densitometer under the following conditions: A [m3].
Equipment: Micromeritics dry automatic densitometer Accupic 1340T-10CC
Filling gas: He
Measurement temperature: 25 ° C
Subsequently, 2.0 g of the pretreated polyester composition was immersed in 200 mL of ion-exchanged water at 30 ° C. and allowed to stand for 1 hour. After 1 hour of standing, the polyester composition was immediately taken out, all the water adhering to the surface was wiped off, and the volume of the polyester composition after immersion: B [m3] was determined using a pycnometer under the following conditions.
Equipment: SANSYO Harvard type pycnometer constant temperature bath: Yamato Scientific constant temperature bath BK33
Measurement temperature: 25 ° C
Immersion liquid: 20 mL of ion-exchanged water
Finally, the volume increase rate before and after immersion of the polyester composition is calculated by the following formula: volume increase rate [%] = (BA) / A × 100.
I asked for it.

C. Measurement of Weight Average Molecular Weight of Polyester Composition The weight average molecular weight of the polyester composition was measured by using gel permeation chromatography under the following conditions.
Instrument: Gel Permeation Chromatograph (GPC) (Waters-e2695)
Detector: Differential Refractometer Detector RI (Waters-2141, Sensitivity 128x)
Column: Showa Denko Co., Ltd. Shodex HFIP806M (two connected)
Solvent: Hexafluoroisopropanol (with 0.01N sodium trifluoroacetate added)
Flow velocity: 1.0 mL / min
Column temperature: 30 ° C
Injection volume: 0.10 mL
Standard sample: Standard polymethyl methacrylate.

D. Analysis of magnesium, aluminum, and zinc metal atom content in the polyester composition The metal content in the polyester composition is determined by melt-molding the polyester composition into a plate shape at 260 ° C. and then fluorescent X-rays manufactured by Rigaku Denki Co., Ltd. The measurement was performed using an analyzer (model number: 3270).

E. Composition analysis of the polyester composition The composition analysis of the polyester composition was carried out using a nuclear magnetic resonance apparatus (NMR).
Equipment: AL-400 manufactured by JEOL Ltd.
Deuterated solvent: Deuterated HFIP
Number of integrations: 128 times Sample concentration: Measurement sample 50 mg / deuterated solvent 1 mL.

F. Measurement of Number Average Molecular Weight of Polyethylene Glycol The number average molecular weight of polyethylene glycol was measured by gel permeation chromatography under the following conditions. For the polyethylene glycol component contained in the polyester composition, 0.05 g of the polyester composition was heated and dissolved in 1 mL of 28% ammonia water at 120 ° C. for 5 hours, and 1 mL of purified water and 1.5 mL of 6M hydrochloric acid were added. , 5 mL of purified water, centrifuge, and then filter through a 0.45 μm filter to extract into the filtrate.
Instrument: Gel Permeation Chromatograph (GPC) (Waters-2690)
Detector: Differential refractometer detector RI (Waters-2410, sensitivity 128x)
Column: TSKgelG3000PWXL (1) (Tosoh)
Solvent: 0.1 M sodium chloride aqueous solution Flow rate: 0.8 mL / min
Column temperature: 40 ° C
Injection volume: 0.05 mL
Standard sample: polyethylene glycol, polyethylene oxide.

G. Evaluation of Upper Drying Temperature of Polyester Composition 3 kg of columnar polyester composition pellets having a diameter of 3.0 ± 1.5 mm and a height of 4.0 ± 1.0 mm were put into a vat having a length of 400 mm, a width of 400 mm and a height of 5 mm. .. It was allowed to stand at a constant temperature for 24 hours under a reduced pressure condition of 0.1 kPa or less, and the temperature obtained by subtracting 10 ° C. from the temperature at which the pellets were fused was determined to be the upper limit drying temperature.

H. Evaluation of Drying Time at Upper Drying Temperature of Polyester Composition 3 kg of columnar polyester composition pellets with a diameter of 3.0 ± 1.5 mm and a height of 4.0 ± 1.0 mm are placed in a bat with a length of 400 mm, a width of 400 mm, and a height of 5 mm. The drying upper limit temperature obtained in Example G and the time required for the moisture content of the pellets to reach 200 ppm or less under reduced pressure conditions of 0.1 kPa or less were measured. The moisture content of the pellets was measured at a temperature condition of 230 ° C. using a coupling device of a moisture titrator AQ-2000 manufactured by Hiranuma Sangyo Co., Ltd. and a moisture vaporizer EV-2000.

I. Area ratio of thermoplastic resin C in fiber cross section The drawn yarns obtained in Examples and Comparative Examples were embedded in epoxy resin, frozen in a Reichert FC / 4E type cryosectioning system, and equipped with a diamond knife. -Cut with Nissei ultracut N (ultramicrotome). Then, the cut surface, that is, the cross section of the fiber was observed at 1000 times using a transmission electron microscope (TEM) H-7100FA manufactured by Hitachi, Ltd., and a micrograph of the cross section of the fiber was taken. Ten single fibers were randomly extracted from the obtained photographs. The fiber cross-sectional area of all the single fibers extracted using image processing software (WINROOF manufactured by Mitani Corporation) and the area of the thermoplastic resin C were calculated, respectively. From the average value of the fiber cross-sectional area and the average value of the area of the thermoplastic resin C, the area ratio occupied by the core component A is calculated by the following formula: Area ratio (%) = {(Average value of the area of the thermoplastic resin C) / (Fiber cross-section) Average area)} x 100
It was calculated as follows.

J. Total Fineness The drawn yarns obtained in the Examples and Comparative Examples were squeezed 100 m using an INTEC electric measuring machine in an environment of a temperature of 20 ° C. and a humidity of 65% RH. The weight of the obtained skein was measured, and the total fineness (dtex) was calculated as follows.

Total fineness (dtex) = weight of 100 m of fiber (g) x 100
The measurement was performed 5 times per sample, and the average value was taken as the total fineness.

K. Strength and Elongation Using the drawn yarns obtained in Examples and Comparative Examples as samples, calculations were made according to JIS L1013: 2010 (chemical fiber filament yarn test method) 8.5.1. In an environment of temperature 20 ° C. and humidity 65% RH, a tensile test was conducted using a Tensilon UTM-III-100 manufactured by Lientech under the conditions of an initial sample length of 20 cm and a tensile speed of 20 cm / min. The strength (cN / dtex) is calculated by dividing the stress (cN) at the point indicating the maximum load by the total fineness (dtex), and the elongation (L1) and the initial sample length (L0) at the point indicating the maximum load are used. The elongation (%) was calculated according to the following formula.

Elongation (%) = {(L1-L0) / L0} x 100
The measurement was performed 10 times per sample, and the average value was taken as the intensity and elongation.

L. Toughness E. The following toughness = (strength) × (elongation) ^1/2 using the strength (cN / dtex) and elongation (%) calculated by the method described.
The toughness was calculated as shown in.

M. Fineness fluctuation value U%
The fineness fluctuation value U% is measured at a measurement speed of 200 m / min, a measurement time of 2.5 minutes, and a measurement fiber using a Wooster tester 4-CX manufactured by Zelveger Wooster, using the drawn yarn obtained in Examples and Comparative Examples as a sample. U% was measured under the conditions of a length of 500 m and a twist number of 12000 / m (S twist). The measurement was performed 5 times per sample, and the average value was defined as the fineness fluctuation value U%. If it cannot be measured, it is described as not measurable.

N. As a pretreatment for measuring the crystal melting temperature and the heat of crystal melting of the kneaded product of the polyester compositions A and B in the fiber, the drawn yarns obtained in Examples and Comparative Examples were allowed to stand at 50 ° C. under nitrogen for 1 week to crystallize. The state was stabilized and the amount of heat of crystal melting was measured using a suggested scanning calorimeter. When the thermoplastic resin C is contained in the fiber, the fiber is immersed in chloroform to extract only the polyester compositions A and B kneaded products, and the extracted polymer after removing chloroform is used at 50 ° C. under nitrogen for 1 week. The crystal state may be stabilized by allowing it to stand still, and the heat of crystal melting may be measured using a suggested scanning calorimeter.
Equipment: Q-2000 manufactured by TA Instruments
Temperature rise rate: 2 ° C / min Measurement temperature: From -20 ° C to 300 ° C.

O. Volume increase rate of the kneaded polyester compositions A and B in the fiber in water The volume increase rate of the drawn yarns obtained in Examples and Comparative Examples in water was measured using a dry automatic densitometer and a pycnometer. As a pretreatment, the drawn yarn was allowed to stand at 50 ° C. under nitrogen for 1 week to stabilize the crystalline state. 0.8 g of the pretreated drawn yarn was weighed, and the volume of the drawn yarn before immersion in water was determined using a dry densitometer under the following conditions: A [m ³ ].
Equipment: Micromeritics dry automatic densitometer Accupic 1340T-10CC
Filling gas: He
Measurement temperature: 25 ° C
Subsequently, 2.0 g of the pretreated drawn yarn was immersed in 200 mL of ion-exchanged water at 30 ° C. and allowed to stand for 1 hour. After 1 hour of standing, the drawn yarn was immediately taken out, the water adhering to the fiber surface was wiped off, and the volume of the drawn yarn after immersion: B [m ^ 3] was determined using a pycnometer under the following conditions.
Equipment: SANSYO Harvard type pycnometer constant temperature bath: Yamato Scientific constant temperature bath BK33
Measurement temperature: 25 ° C
Immersion liquid: 20 mL of ion-exchanged water
The area ratio of the thermoplastic resin C in the fiber cross section is defined as X, and the volume increase rate before and after immersion of the drawn yarn is the following formula. Volume increase rate [%] = {(BA) / A} × 100 / (1) -X / 100)
Asked by.

P. As a pretreatment for measuring the water absorption of the fiber, the drawn yarns obtained in Examples and Comparative Examples were allowed to stand at 50 ° C. under nitrogen for 1 week to stabilize the crystalline state. Subsequently, about 2.0 g of the pretreated drawn yarn was immersed in 200 mL of ion-exchanged water at 30 ° C. and allowed to stand for 1 hour. After 1 hour of standing, the drawn yarn was immediately taken out, the water adhering to the fiber surface was wiped off, and the weight: A [g] was measured. Further, the fibers after the weight measurement were dried for 6 hours in a blower dryer set at 105 ° C., and the weight after drying: B [g] was measured, and the following formula water absorption amount [g / g] = (AB). ) / B
The water absorption amount [g / g] per 1 g of the drawn yarn was calculated.

[Example 1]
(Manufacturing)
Fiber production was carried out using the polyester compositions A and B having the characteristics shown in Table 1. The polyester composition A has a drying upper limit temperature (a temperature at which pellets fuse with each other and becomes difficult to recover when set to + 10 ° C.) at 120 ° C. It took 15 hours under decompression conditions of ° C. and 0.1 kPa or less. The polyester composition B had a drying upper limit temperature of 105 ° C., and it took 24 hours under reduced pressure conditions of 105 ° C. and 0.1 kPa or less until the pellet moisture content became 200 ppm or less. Dry pellets were put into the pressure melter (1) from different side feeders so that the weight ratio of the polyester composition A: polyester composition B was 30.0: 70.0, melt-kneaded at 260 ° C., and spun as it was. Supplied in the pack. At the same time, using the pressure melter (2), nylon 6 having a relative viscosity ηr: 2.6 is separately melted and supplied into the spinning pack, and is combined with the kneaded polyester compositions A and B supplied from the pressure melter (1). The yarns were merged in the spinneret and discharged to form a composite yarn. The spinning temperature is 260 ° C., after discharging from the spinneret, the spun yarn is cooled with a cooling air having an air temperature of 25 ° C. and a wind speed of 20 m / min, and an oil agent is applied by a refueling device to converge the yarn at 1000 m / min. It was picked up by a rotating first godet roller and wound by a winder via a second godet roller rotating at the same speed as the first godet roller. The obtained undrawn yarn was drawn by a horizontal drawing machine having a first hot roller of 30 ° C. and a second hot roller of 130 ° C. so as to be 3.0 times, and a drawn yarn of 84 dtex-36f was obtained. The obtained fiber is a core-sheath type composite fiber in which the kneaded product of the polyester compositions A and B is the core component and the nylon 6 is the sheath component, and more specifically, the kneaded material of the polyester compositions A and B is a part of the fiber. It was a C-type composite fiber exposed on the outer layer.

(evaluation)
Various fiber characteristics were evaluated using the obtained drawn yarn. The results of various evaluations are shown in Table 1. The kneaded polyester compositions A and B in the fiber showed a low heat of crystal melting unlike those before kneading, and a high volume increase rate in water was exhibited. The water absorption of the entire fiber was 1.12 g / g, which greatly exceeded the target of 0.4 g / g.

[Example 2]
The melt extruder in Example 1 was changed from a pressure melter to a twin-screw kneading extruder (KZW15TWIN-30MG-FSS manufactured by Technobel Co., Ltd., set temperature 260 ° C.) in the same manner as in Example 1 to produce fibers. did. Table 1 shows the results of various evaluations.

[Example 3]
Nylon 6 used as the thermoplastic resin C in Example 1 was changed to polybutylene terephthalate having a weight average molecular weight of 17,000, and the same procedure as in Example 1 was carried out to produce fibers. Table 1 shows the results of various evaluations.

[Example 4]
Example 1 except that the thermoplastic resin C was not used in Example 1 and the single component yarn was composed of only the kneaded product of the polyester compositions A and B, and the temperature of the second hot roller of the horizontal drawing machine was changed to 30 ° C. The same procedure was carried out to produce fibers. Table 1 shows the results of various evaluations.

[Examples 5, 7, 8]
The fibers were produced in the same manner as in Example 1 except that the kneading ratios of the polyester compositions A and B used in Example 1 were changed as shown in Table 1. Table 1 shows the results of various evaluations.

[Example 6]
The kneading ratios of the polyester compositions A and B used in Example 1 were changed as shown in Table 1, and the melt extruder was changed from a pressure melter to a twin-screw kneading extruder (KZW15TWIN-30MG-FSS manufactured by Technobel Co., Ltd.). The same procedure as in Example 1 was carried out except that the set temperature was changed to 260 ° C.) to produce fibers. Table 1 shows the results of various evaluations.

[Examples 9 to 14]
The polyester composition A or B used in Example 1 was changed to the polyester composition having the characteristics shown in Table 2 in the same manner as in Example 1 to produce fibers. Table 2 shows the results of various evaluations.

[Examples 15 to 20]
The polyester compositions A and B used in Example 1 were changed to the polyester compositions having the characteristics shown in Table 3 in the same manner as in Example 1 to produce fibers. Table 3 shows the results of various evaluations.

[Comparative Example 1]
The polyester compositions A and B used in Example 1 were changed to the polyester compositions having the characteristics shown in Table 4 in the same manner as in Example 1 to produce fibers. Table 4 shows the results of various evaluations.

Since the polyester compositions A and B used in Comparative Example 1 are the same composition and have high water absorption performance by themselves, they also have excellent water absorption performance in the fiber after spinning, but at low crystallinity and low crystal melting temperature. Therefore, the pellets could be dried only at a low temperature of 60 ° C., and it took 180 hours to dry, which was inferior in productivity.

In addition, it is necessary to add a large amount of aliphatic metal salt for the purpose of preventing deformation of the pellet during drying, and the total metal content of magnesium / aluminum / zinc must be set higher than 20 ppm, which is inferior in terms of cost. rice field.

[Comparative Example 2]
The polyester composition A used in Example 1 was changed to the polyester composition having the characteristics shown in Table 4 in the same manner as in Example 1 to produce fibers. Table 4 shows the results of various evaluations.

Both the crystal melting temperature and the amount of heat of crystal melting of the polyester composition A used in Comparative Example 2 were high, and it was not possible to exhibit excellent water absorption performance in the fibers after kneading.

[Comparative Example 3]
The polyester composition B used in Example 1 was changed to the polyester composition having the characteristics shown in Table 4 in the same manner as in Example 1 to produce fibers. Table 4 shows the results of various evaluations.

Both the crystal melting temperature and the amount of heat of crystal melting of the polyester composition B used in Comparative Example 3 are low, and the pellets can be dried only at a low temperature of 85 ° C., and it takes 120 hours to dry, so that the productivity is inferior. there were. Furthermore, it was not possible to exhibit excellent water absorption performance in the fibers after kneading.

In addition, it is necessary to add a large amount of aliphatic metal salt for the purpose of preventing deformation of the pellet when the polyester composition B is dried, and the total metal content of magnesium / aluminum / zinc must be set higher than 20 ppm, which is cost effective. It was inferior to.

[Comparative Example 4]
The polyester compositions A and B used in Example 1 were changed to the polyester compositions having the characteristics shown in Table 4 in the same manner as in Example 1 to produce fibers. Table 4 shows the results of various evaluations.

The polyester compositions A and B used in Comparative Example 4 had low crystal melting temperatures, and the pellets could only be dried at a low temperature of 85 ° C., and it took 120 hours to dry, so that the productivity was inferior. ..

In addition, it is necessary to add a large amount of aliphatic metal salt for the purpose of preventing deformation of the pellet when the polyester composition B is dried, and the total metal content of magnesium / aluminum / zinc must be set higher than 20 ppm, which is cost effective. It was inferior to.

[Comparative Example 5]
Except that the polyester compositions A and B used in Example 1 were changed to polyester compositions having the characteristics shown in Table 4, and the kneading ratios of the polyester compositions A and B were changed as shown in Table 4. The same procedure as in Example 1 was carried out to produce fibers. Table 4 shows the results of various evaluations.

The crystal melting temperature and the amount of heat of crystal melting of the polyester composition A used in Comparative Example 5 are both high, and in order to exhibit excellent water absorption performance in the fibers after kneading, the crystal melting temperature of the polyester composition B to be kneaded , The amount of heat of crystal melting had to be set low. As a result, the pellets of the polyester composition B could be dried only at a low temperature of 85 ° C., and it took 120 hours to dry, which was inferior in productivity.

In addition, it is necessary to add a large amount of aliphatic metal salt for the purpose of preventing deformation of the pellet when the polyester composition B is dried, and the total metal content of magnesium / aluminum / zinc must be set higher than 20 ppm, which is cost effective. It was inferior to.

[Comparative Example 6]
Except that the polyester compositions A and B used in Example 1 were changed to polyester compositions having the characteristics shown in Table 4, and the kneading ratios of the polyester compositions A and B were changed as shown in Table 4. The same procedure as in Example 1 was carried out to produce fibers. Table 4 shows the results of various evaluations.

The crystal melting temperature of the polyester composition A used in Comparative Example 6 is high, and in order to exhibit excellent water absorption performance in the fibers after kneading, the crystal melting temperature and the amount of heat of crystal melting of the polyester composition B to be kneaded are set. I had to set it low. As a result, the pellets of the polyester composition B could be dried only at a low temperature of 95 ° C., and it took 60 hours to dry, which was inferior in productivity.

[Comparative Example 7]
The polyester compositions A and B used in Example 1 were changed to polyester compositions having the characteristics shown in Table 4, and the kneading ratios of the polyester compositions A and B were changed as shown in Table 4. Example 1 except that the melt kneading and spinning temperature was set to 290 ° C, the first hot roller temperature of the horizontal stretching machine was set to 90 ° C, the second hot roller temperature was set to 140 ° C, and the drawing ratio was set to 2.8 times. The same procedure was carried out to produce fibers. Table 4 shows the results of various evaluations.

Since the amount of heat of crystal melting of the polyester composition B used in Comparative Example 7 was low, the pellets could only be dried at a low temperature of 85 ° C., and it took 60 hours to dry, which was inferior in productivity.

The fiber production method described in Comparative Example 7 is generally a method for producing a cationic dyeable PET fiber or an alkaline easily soluble PET fiber, and the kneaded product of the polyester compositions A and B is expensive. The water absorption performance was not exhibited because the amount of heat of crystal melting was shown.

Claims (5)

Extruded polyester composition A and polyester composition B having different compositions, in which the crystal melting temperature obtained by differential scanning calorimetry is 120 to 200 ° C. and the crystal melting heat is in the range of 20 to 45 J / g. A fiber manufacturing method characterized by directly melt-spinning after melt-kneading using a machine. Either the polyester composition A or the polyester composition B has a volume increase rate in the range of 1 to 50% when the pellets are allowed to stand at 50 ° C. under a nitrogen stream for 1 week and then immersed in ion-exchanged water at 30 ° C. for 1 hour. The fiber manufacturing method according to claim 1, wherein the fiber is produced. The invention according to claim 1 or 2, wherein the polyester composition A and the polyester composition B having a total of the magnesium metal atom content, the aluminum metal atom content, and the zinc metal atom content in the range of 20 ppm or less are used. Fiber manufacturing method. The polyester composition A and / or B is a polyester composition obtained by a polycondensation reaction of a dicarboxylic acid and / or an ester-forming derivative thereof and an alkylene glycol, and the terephthalic acid component is 80.0 mol with respect to the total acid component. % Or less, the metal sulfonate group-containing isophthalic acid component is copolymerized in the range of 5.0 to 20.0 mol% with respect to the total acid component, and a polyester glycol having a number average molecular weight of 1000 to 20000 is obtained. The fiber production method according to any one of claims 1 to 3, which is a polyester composition contained in the range of 15.0% by weight or less with respect to the entire composition. Claim 1 is characterized in that when the polyester composition A and the polyester composition B are directly melt-spun after melt-kneading, the thermoplastic resin C is separately melt-extruded and merged in the mouthpiece to form a composite fiber composed of two components. The fiber manufacturing method according to 4.