JP2018204157A - Core-sheath type composite fiber, false twist yarn and fibrous structure superior in hygroscopicity - Google Patents

Abstract

To provide a core-sheath type composite fiber superior in hygroscopicity that prevents fusion during stretching and false twisting processes; in which a process passing ability is excellent because of little occurrence of breakage of yarn and fuzz, and it is unlikely to cause dyeing unevenness and fuzz in a fibrous structure such as fabric and knit; that is superior in quality; in which separation is prevented by providing one opening, and cracks in a sheath of a hygroscopic polymer and elution of the polymer do not occur during a hot water treatment such as dyeing.SOLUTION: The core-sheath type composite fiber is a polymer whose core and sheath components are both crystalline, the core component having hygroscopicity. The core-sheath type composite fiber has one part in which the core component is exposed on a surface in a fiber transverse plane, and a ratio (r/R) of a length R of the circumference of the fiber transverse plane and a length r of a surface exposed part of the core component is 0.005 or more and less than 0.050. The extrapolation melting start temperature of the core-sheath type composite fiber is 150°C or more, and a difference in the moisture absorption rate (ΔMR) after a hot water treatment is 2.0 to 10.0%.SELECTED DRAWING: Figure 1

Description

  The present invention is a core having crystallinity in both the core component and the sheath component, the core component having hygroscopicity, and having one portion where the core component is exposed on the surface in the fiber cross section The present invention relates to a sheath type composite fiber. More specifically, since fusing in the stretching or false twisting process is suppressed, thread breakage and fluff are less likely to occur, the process is easy to pass through, and when dyeing spots are obtained when a fiber structure such as woven fabric or knitted fabric is obtained. Generation of fluff and fluff, excellent quality, and peeling is suppressed by providing one opening, sheath cracking due to volume swelling of the polymer having hygroscopicity of the core component during hot water treatment such as dyeing Further, the present invention relates to a core-sheath type composite fiber that suppresses elution of a hygroscopic polymer, is excellent in hygroscopicity even after hydrothermal treatment, and can be suitably used for clothing applications.

  Polyester fibers are used in a wide range of applications because they are inexpensive and have excellent mechanical properties. However, since it has poor hygroscopicity, it has problems to be solved from the viewpoint of wearing comfort, such as generation of stuffiness at high humidity in summer and generation of static electricity at low humidity in winter.

  In order to improve the above-mentioned drawbacks, various proposals have been made so far regarding methods for imparting hygroscopicity to polyester fibers. Examples of a general method for imparting hygroscopicity include copolymerization of a hydrophilic compound to polyester and addition of a hydrophilic compound. Polyethylene glycol is an example of the hydrophilic compound.

  For example, Patent Document 1 proposes a fiber using a polyester obtained by copolymerizing polyethylene glycol as a hygroscopic polymer with respect to a polyester. In this proposal, a hygroscopic polymer is made into a single fiber to impart hygroscopicity to the polyester fiber.

  Patent Document 2 proposes an eccentric core-sheath type composite fiber in which a hygroscopic polymer is disposed in the sheath and a hydrophobic polymer is disposed in the core. In this proposal, by placing a hydrophobic polymer in the core, form stability against reversible changes in moisture absorption and drying is imparted.

  Patent Documents 3 and 4 propose a core-sheath type composite fiber in which polyethylene glycol is copolymerized in the core and polyethylene terephthalate is disposed in the sheath. In this proposal, a hygroscopic property is imparted to the polyester fiber by arranging a hygroscopic polymer in the core.

  Patent Documents 5 and 6 propose core-sheath type composite fibers in which polyethylene glycol is copolymerized in the core, polyethylene terephthalate is disposed in the sheath, and an opening is formed in a part of the sheath. Although the core component has hygroscopicity, in these proposals, the core component is eluted to form a C-shaped hollow fiber, which gives lightness to the polyester fiber. As a specific example of the core component that is easily eluted, in Patent Document 5, a polyethylene terephthalate copolymerized with 8 to 70% by weight of polyethylene glycol having a weight average molecular weight of 500 to 8000, that is, a number average molecular weight of less than 8000, and Patent Document 6 has a molecular weight of 3000. Polyethylene terephthalate copolymerized with 17% by weight of polyethylene glycol is disclosed.

  However, in the method described in Patent Document 1, since the hygroscopic polymer exposed on the entire fiber surface is swollen by the spinning oil agent, the roller and the guide in the spinning, stretching, false twisting process, knitting process, and weaving process are used. As a result of falling off by rubbing and depositing on rollers and guides, thread breakage and fluffing occurred, and there were problems in process passability and quality. In addition, there is a problem that polyethylene glycol, which is a copolymer component of the hygroscopic polymer, is eluted during hot water treatment such as dyeing and the hygroscopicity is lowered after the hot water treatment.

  In the method described in Patent Document 2, since a hydrophobic polymer is arranged in the core, although the shape stability against reversible change of moisture absorption and drying can be obtained, the hygroscopic polymer is exposed on at least half of the fiber surface. For this reason, as in the method described in Patent Document 1, the hygroscopic polymer swells and falls off, and problems remain in process passability and quality.

  In the methods described in Patent Documents 3 and 4, since the hygroscopic polymer of the core component is completely covered with the sheath, swelling of the hygroscopic polymer due to the spinning oil and falling off due to rubbing with the roller and the guide are suppressed. Although the permeability was improved, there was a problem that the hygroscopic polymer of the core component swelled in volume during hot water treatment such as dyeing, and sheath cracking occurred and the quality was lowered. Furthermore, the hygroscopic polymer of the core component is eluted starting from the cracked portion of the sheath, and there is a problem that the hygroscopicity is lowered after the hot water treatment.

  In the methods described in Patent Documents 5 and 6, since the hygroscopic polymer of the core component is exposed on a part of the fiber surface, swelling of the hygroscopic polymer by the spinning oil agent and falling off due to rubbing with a roller or a guide are suppressed. The process passability is improved. However, the purpose is to elute the core component, and the core component is completely eluted by hot water treatment such as dyeing. Therefore, the resulting fiber is a C-shaped polyester hollow fiber and has no hygroscopicity. Met.

JP 2006-104379 A Japanese Patent Laid-Open No. 9-13257 JP 2001-172374 A JP 2017-43860 A Japanese Patent Laid-Open No. 6-200473 JP 2007-131980 A

  The problem of the present invention is to solve the problems of the prior art described above, and since fusion in the stretching and false twisting process is suppressed, the occurrence of yarn breakage and fluff is low, the process passability is good, When a fiber structure such as a knitted fabric is used, there is little generation of dyed spots and fluff, it is excellent in quality, and peeling is suppressed by providing one opening, and moisture absorption of the core component during hot water treatment such as dyeing Core-sheath type composite fiber that has excellent moisture absorption even after hydrothermal treatment, and can be suitably used for clothing applications. Is to provide.

The problem of the present invention is that the core component and the sheath component are both crystalline polymers, the core component has hygroscopicity, and a part of the core component is exposed on the surface in the fiber cross section. A sheath-core type composite fiber in which the ratio (r / R) of the length R of the outer periphery of the fiber cross section to the length r of the surface exposed portion of the core component is 0.005 or more and less than 0.050, and the core sheath Solving with a core-sheath type composite fiber characterized in that the extrapolated melting start temperature of the type composite fiber is 150 ° C. or more and the moisture absorption difference (ΔMR) after the hot water treatment is 2.0 to 10.0% Can do.
Moreover, it is preferable that the composite ratio (weight ratio) of the core component / sheath component is 10/90 to 70/30.

  The core component hygroscopic polymer is preferably at least one polymer selected from the group consisting of polyether ester, polyether amide and polyether ester amide containing polyether as a copolymer component. Moreover, it can employ | adopt suitably that polyether is polyethyleneglycol, polypropylene glycol, and polybutylene glycol.

The polyether ester has an aromatic dicarboxylic acid and an aliphatic diol as main components, and preferably a polyether as a copolymerization component, the aliphatic diol is ethylene glycol, and the polyether has a number average molecular weight of 8000 to 800. It can be suitably employed that it is 30000 g / mol and the copolymerization rate of the polyether is 10 to 35% by weight. Alternatively, the aliphatic diol is 1,4-butanediol, the number average molecular weight of the polyether is 2000 to 30000 g / mol, and the copolymerization ratio of the polyether is preferably 25 to 60% by weight. Can be adopted.
Furthermore, the sheath component of the core-sheath composite fiber is preferably a cationic dyeable polyester.

  The false twisted yarn of the present invention is obtained by twisting two or more of the core-sheath type conjugate fibers, and the fiber structure characterized in that the core-sheath type conjugate fibers and / or the false twisted yarns are used at least in part. It can employ | adopt suitably.

  According to the present invention, since fusion in the stretching or false twisting process is suppressed, the occurrence of yarn breakage and fluff is small, and the process passability is good. In addition, when a fiber structure such as a woven fabric or a knitted fabric is used, there is little generation of dyed spots and fluff, and the quality is excellent. Furthermore, since it has one opening, peeling is suppressed, and sheath cracking due to the volume swelling of the hygroscopic polymer of the core component during hot water treatment such as dyeing, and elution of the hygroscopic polymer as a result. Since the core-sheath-type composite fiber which is suppressed and excellent in hygroscopicity even after the hot water treatment can be provided, it can be suitably used particularly in clothing applications.

It is a figure which shows an example of the cross-sectional shape of the core-sheath-type composite fiber of this invention. 10 is a view showing a cross-sectional shape of a core-sheath type composite fiber manufactured in Comparative Example 7. FIG. 10 is a view showing a cross-sectional shape of a core-sheath type composite fiber manufactured in Comparative Example 8. FIG.

  The core-sheath type composite fiber of the present invention is a polymer in which both the core component and the sheath component are crystalline, and the core component is a hygroscopic polymer, and a part of the core component is exposed on the surface in the fiber cross section. A ratio of the length R of the outer circumference of the cross section of the fiber and the length r of the surface exposed portion of the core component (r / R) is 0.005 or more and less than 0.050, a core-sheath type composite fiber, The extracorporeal melting start temperature of the core-sheath type composite fiber is 150 ° C. or higher, and the difference in moisture absorption (ΔMR) after the hot water treatment is 2.0 to 10.0%.

  In general, hygroscopic polymers tend to swell with spinning oil, accumulate as dirt due to falling off by rubbing with rollers and guides, and cause thread breakage and fluff. When a fiber structure such as a knitted fabric is used, dyed spots and fluff are generated, which causes a problem of low quality. In addition, there is a problem that fibers are fused with each other in contact with a heating roller or a heater in a stretching or false twisting process. In order to improve process passability and quality, a core-sheath type composite fiber completely covered with a hygroscopic polymer of the core component has been proposed, but sheath cracking due to volume swelling of the core component during hot water treatment such as dyeing In addition, the elution of the hygroscopic polymer from the cracked portion of the sheath causes another problem that hygroscopicity does not appear after the hot water treatment. Therefore, a core-sheath type composite fiber in which a part of the core component is exposed on the surface in the fiber cross section has been proposed, but all of fusion during false twisting, sheath cracking during hydrothermal treatment, and elution of the core component. At the same time, no core-sheath type composite fiber having good and high process passability and exhibiting hygroscopicity even after hydrothermal treatment has not yet been obtained.

  As a result of intensive studies in view of the above problems, the present inventors have found that both the core component and the sheath component have crystallinity, and the core component has hygroscopicity, and the length R of the outer periphery of the fiber cross section, The ratio (r / R) of the length r of the surface exposed portion of the core component is not less than 0.005 and less than 0.050, and all that the extrapolated melting start temperature of the core-sheath type composite fiber is 150 ° C. or higher For the first time when the above conditions were satisfied, all of the above problems were solved, and a core-sheath type composite fiber having good and high process passability and exhibiting hygroscopicity even after hydrothermal treatment was successfully obtained.

  The core component of the core-sheath type composite fiber of the present invention is a polymer having crystallinity. If the core component has crystallinity, in the measurement of the extrapolation melting start temperature by the method described in the examples, a melting peak accompanying the melting of the crystal is observed. If the core component has crystallinity, fusion between fibers accompanying contact with the heating roller or heating heater in the stretching or false twisting process is suppressed, so the deposit on the heating roller, heating heater, or guide There are few occurrences of yarn breakage and fluff, and process passability is good. In addition, when a fiber structure such as a woven fabric or a knitted fabric is used, there is little generation of dyed spots and fluff, and the quality is excellent. Furthermore, in the case of having crystallinity, elution of the polymer having the hygroscopic property of the core component into the hot water during the hydrothermal treatment such as dyeing is suppressed, so that the hygroscopic property is maintained even after the hydrothermal treatment. Maintained.

  The core component of the core-sheath composite fiber of the present invention is a polymer having hygroscopicity. In the present invention, the hygroscopic polymer is a polymer having a difference in moisture absorption rate (ΔMR) of 2.0% or more. The difference in moisture absorption (ΔMR) in the present invention refers to a value measured by the method described in the examples. If the core component has hygroscopicity, a core-sheath type composite fiber excellent in hygroscopicity can be obtained by combining with the sheath component.

  Specific examples of the core component of the core-sheath type composite fiber of the present invention include hygroscopic polymers such as polyether ester, polyether amide, polyether ester amide, polyamide, thermoplastic cellulose derivative, and polyvinylpyrrolidone. It is not limited to these. Of these, polyether esters, polyether amides, and polyether ester amides containing polyether as a copolymerization component are preferable because of their excellent hygroscopicity. Particularly, polyether esters are excellent in heat resistance, and the resulting core-sheath type composite fiber machine It is preferable because of its good characteristics and color tone. These hygroscopic polymers may be used alone or in combination of two or more. Further, a polymer obtained by blending these hygroscopic polymers with polyester, polyamide, polyolefin or the like may be used as the hygroscopic polymer.

  Specific examples of the polyether of the copolymer component of the hygroscopic polymer include homopolymers such as polyethylene glycol, polypropylene glycol, polybutylene glycol, polyethylene glycol-polypropylene glycol copolymer, polyethylene glycol-polybutylene glycol copolymer. Copolymers such as coalescence can be mentioned, but the invention is not limited to these. Of these, polyethylene glycol, polypropylene glycol, and polybutylene glycol are preferable because they are easy to handle during production and use, and polyethylene glycol is particularly preferable because of its excellent hygroscopicity.

  From the viewpoint of heat resistance and mechanical properties, the polyether ester preferably comprises an aromatic dicarboxylic acid and an aliphatic diol as main components and a polyether as a copolymer component. Specific examples of the aromatic dicarboxylic acid include terephthalic acid, isophthalic acid, phthalic acid, 5-sodium sulfoisophthalic acid, 5-lithium sulfoisophthalic acid, 5- (tetraalkyl) phosphonium sulfoisophthalic acid, 4,4′-diphenyldicarboxylic acid Examples thereof include, but are not limited to, acid and 2,6-naphthalenedicarboxylic acid. Specific examples of the aliphatic diol include ethylene glycol, 1,3-propanediol, 1,4-butanediol, hexanediol, cyclohexanediol, diethylene glycol, hexamethylene glycol, neopentyl glycol, and the like. It is not limited. Among these, ethylene glycol, propylene glycol, and 1,4-butanediol are preferable because they have good handleability during production and use, and ethylene glycol can be suitably employed from the viewpoint of heat resistance and mechanical properties. From the viewpoint of crystallinity, 1,4-butanediol can be suitably employed.

  The number average molecular weight and copolymerization ratio of the polyether of the polyether ester copolymerization component can be appropriately selected within the range where the polyether ester has crystallinity, but the preferred range depends on the component of the polyether ester. Depending on it. For example, when ethylene glycol is used as an aliphatic diol that is a constituent of a polyether ester, if the polyether copolymerization rate is too high, the polyether ester elutes into hot water during hot water treatment such as dyeing, Hygroscopicity decreases after water treatment. In addition, when 1,4-butanediol is used as the aliphatic diol that is a constituent of the polyether ester, the polymer has higher crystallinity than when ethylene glycol is used. Even in a high case, elution of the polyether ester into hot water is suppressed. That is, when 1,4-butanediol is used as the aliphatic diol, the copolymerization rate of the polyether can be increased. Therefore, the hygroscopicity of the polyether ester, and thus the hygroscopicity of the resulting core-sheath composite fiber It is preferable because the properties can be increased.

  When the aliphatic diol that is a constituent of the polyether ester is ethylene glycol, the number average molecular weight of the polyether is preferably 8000 to 30000 g / mol, and the copolymerization rate of the polyether is 10 to 35% by weight. Is preferred. When the polyether has a number average molecular weight of 8000 g / mol or more, the polyether ester has a high hygroscopic property, and when used as a core component, a core-sheath type composite fiber having an excellent hygroscopic property can be obtained. In addition, since it is possible to suppress the decrease in the crystallinity of the polyether ester and the decrease in the extrapolation melting start temperature, and the fusion between the fibers accompanying the contact with the heating roller or the heating heater in the stretching or false twisting process is suppressed, Rollers, heaters, guide deposits, yarn breakage, fluff generation is low, process passability is good, and when fabric structure such as woven fabric or knitted fabric, dyeing spots and fluff generation is small, It is preferable because of its excellent quality. The number average molecular weight of the polyether is more preferably 8100 g / mol or more, and still more preferably 8300 g / mol or more. On the other hand, if the number average molecular weight of the polyether is 30000 g / mol or less, polycondensation reactivity is high, unreacted polyether can be reduced, and elution into hot water during hot water treatment such as dyeing is suppressed. Therefore, it is preferable because the hygroscopicity is maintained even after the hot water treatment. The number average molecular weight of the polyether is more preferably 25000 g / mol or less, and further preferably 20000 g / mol or less. A polyether copolymerization rate of 10% by weight or more is preferable because the polyether ester has a high hygroscopic property, and when used as a core component, a core-sheath type composite fiber having an excellent hygroscopic property can be obtained. The copolymerization ratio of the polyether is more preferably 15% by weight or more, and further preferably 20% by weight or more. On the other hand, if the copolymerization ratio of the polyether is 35% by weight or less, since fusion between fibers accompanying the contact with the heating roller or heating heater in the stretching or false twisting process is suppressed, the heating roller or heating heater, It is preferable because there are few deposits, yarn breakage and fluffing on the guide, good processability, and less dyeing spots and fluffing when producing fiber structures such as woven fabrics and knitted fabrics. . Moreover, since elution of the polyether ester of the core component into the hot water during hot water treatment such as dyeing is suppressed, it is preferable because hygroscopicity is maintained even after the hot water treatment. The copolymerization rate of the polyether is more preferably 32% by weight or less, and further preferably 30% by weight or less.

  When the aliphatic diol that is a constituent of the polyether ester is 1,4-butanediol, the number average molecular weight of the polyether is preferably 2000 to 30000 g / mol, and the copolymerization ratio of the polyether is 25 to 60 wt. % Is preferred. If the polyether has a number average molecular weight of 2000 g / mol or more, the polyether ester has a high hygroscopic property, and when used as a core component, a core-sheath type composite fiber having an excellent hygroscopic property can be obtained. Moreover, since the fall of the crystallinity of polyetherester can be suppressed, it is preferable. The number average molecular weight of the polyether is more preferably 3000 g / mol or more, and further preferably 5000 g / mol or more. Moreover, if the number average molecular weight of a polyether is 8000 g / mol or more, the fall of the crystallinity of a polyether ester and the fall of the extrapolation melting start temperature can be suppressed, and with a heating roller and a heater in an extending | stretching or false twist process, Since the fusion of fibers due to contact is suppressed, there is little generation of deposits, yarn breakage and fluff on heating rollers, heaters, guides, good processability, and fibers such as woven and knitted fabrics When a structure is formed, dyeing spots and fluff are less likely to occur, and it is particularly preferable because of its excellent quality. On the other hand, if the number average molecular weight of the polyether is 30000 g / mol or less, the polycondensation reactivity is high, unreacted polyethylene glycol can be reduced, and the core component to the hot water during hot water treatment such as dyeing can be reduced. Since elution of the polyether ester is suppressed, the hygroscopicity is maintained even after the hot water treatment, which is preferable. The number average molecular weight of the polyether is more preferably 27000 g / mol or less, further preferably 25000 g / mol or less, and particularly preferably 20000 g / mol or less. A polyether copolymerization rate of 25% by weight or more is preferable because the polyether ester has a high hygroscopic property, and when used as a core component, a core-sheath composite fiber having an excellent hygroscopic property can be obtained. The copolymerization rate of the polyether is more preferably 30% by weight or more, and further preferably 35% by weight or more. On the other hand, if the copolymerization ratio of the polyether is 60% by weight or less, since fusion of fibers due to contact with the heating roller or heating heater in the stretching or false twisting process is suppressed, the heating roller or heating heater, It is preferable because there are few deposits, yarn breakage and fluffing on the guide, good processability, and less dyeing spots and fluffing when producing fiber structures such as woven fabrics and knitted fabrics. . Moreover, since elution of the polyether ester of the core component into the hot water during hot water treatment such as dyeing is suppressed, it is preferable because hygroscopicity is maintained even after the hot water treatment. The copolymerization ratio of the polyether is more preferably 55% by weight or less, and further preferably 50% by weight or less.

  The sheath component of the core-sheath type composite fiber of the present invention has crystallinity. If the sheath component has crystallinity, a melting peak accompanying the melting of the crystal is observed in the measurement of the extrapolation melting start temperature by the method described in the Examples. If the sheath component has crystallinity, the fusion between fibers accompanying the contact with the heating roller or heater in the stretching or false twisting process is suppressed, so the deposit on the heating roller, heater, or guide In addition, there are few occurrences of yarn breakage and fluff, the process is easy to pass through, and there is little occurrence of dyed spots and fluff when a fiber structure such as a woven fabric or knitted fabric is produced, which is excellent in quality. Moreover, the elution of the sheath component to the hot water is suppressed during the hot water treatment such as dyeing.

  Specific examples of the sheath component of the core-sheath composite fiber of the present invention include polyesters such as polyethylene terephthalate and polybutylene terephthalate, polyamides such as nylon 6 and nylon 66, polyolefins such as polyethylene and polypropylene, and the like. Not. Of these, polyester is preferred because of its excellent mechanical properties and durability. In addition, when the sheath component is a hydrophobic polymer such as polyester or polyolefin, both the hygroscopicity due to the hygroscopic polymer of the core component exposed on the surface and the dry feel due to the hydrophobic polymer of the sheath component can be achieved. This is preferable because a fiber structure excellent in wearing comfort can be obtained.

  Specific examples of the polyester relating to the sheath component of the core-sheath composite fiber of the present invention include aromatic polyesters such as polyethylene terephthalate, polypropylene terephthalate, and polybutylene terephthalate, and aliphatic polyesters such as polylactic acid and polyglycolic acid. However, it is not limited to these. Among these, polyethylene terephthalate, polypropylene terephthalate, and polybutylene terephthalate are preferable because they are excellent in mechanical properties and durability, and are easy to handle during production and use. Polyethylene terephthalate is preferable because it provides a firmness and a firm feeling peculiar to polyester fibers, and polybutylene terephthalate is preferable because of its high crystallinity.

  The sheath component of the core-sheath composite fiber of the present invention is preferably a cationic dyeable polyester. If the polyester has an anion moiety such as a sulfonic acid group, it has cation dyeability due to interaction with a cationic dye having a cation moiety. If the sheath component is a cationic dyeable polyester, it is preferable because it exhibits clear color development and can prevent dye contamination when mixed with polyurethane fibers. Specific examples of the copolymerizable component of the cationic dyeable polyester include 5-sulfoisophthalic acid metal salt, and examples thereof include, but are not limited to, lithium salt, sodium salt, potassium salt, rubidium salt, and cesium salt. Of these, lithium salts and sodium salts are preferable, and sodium salts are particularly suitable because they are excellent in crystallinity. The copolymerization rate of 5-sulfoisophthalic acid metal salt is preferably 0.1 to 6 mol%, and more preferably 0.5 to 2 mol%.

  The core-sheath type composite fiber of the present invention has one portion where the core component is exposed on the surface in the fiber cross section. Unlike the core-sheath type composite fiber in which the core component is completely covered, since a part of the core component is exposed on the surface in the fiber cross section, the polymer having the hygroscopic property of the core component during hot water treatment such as dyeing is obtained. It is possible to suppress sheath cracking when the volume is swollen. Further, since the hygroscopic polymer of the core component is exposed on the surface, higher hygroscopicity is exhibited than the core-sheath type composite fiber in which the core component is completely covered. Here, when there are a plurality of exposed portions of the core component, the sheath becomes discontinuous in the fiber cross section, which causes the sheath to peel or fall off. Therefore, in order to achieve both suppression of sheath peeling / dropping and suppression of sheath cracking when the polymer having hygroscopicity of the core component is swelled during hot water treatment such as dyeing, the core component is exposed on the surface. There is only one portion and the exposed area is as small as possible. Specifically, the ratio (r / R) of the length R of the outer periphery of the fiber cross section described later and the length r of the surface exposed portion of the core component Must be 0.005 or more and less than 0.050.

  In the core-sheath type composite fiber of the present invention, the ratio (r / R) between the length R of the outer periphery of the fiber cross section and the length r of the surface exposed portion of the core component is 0.005 or more and less than 0.050. The ratio R (R / R) of the length R of the outer circumference of the fiber cross section and the length r of the surface exposed portion of the core component in the present invention refers to a value calculated by the method described in the examples. If the r / R of the core-sheath composite fiber is 0.005 or more, the hygroscopicity is higher than that of the core-sheath composite fiber in which the core component is completely covered by the surface exposure of the polymer having the hygroscopic property of the core component. To express. Moreover, since the polymer which has a hygroscopic property of a core component at the time of hot water treatment such as dyeing can be swollen in volume, sheath cracking can be suppressed. On the other hand, if the r / R of the core-sheath type composite fiber is less than 0.050, the fusion between the fibers accompanying the contact with the heating roller or the heating heater in the stretching or false twisting process is suppressed. There is little generation of deposits, yarn breakage, and fluff on the heater, guide, good process passage, and there are few dye spots and fluff when it is made into a fiber structure such as woven fabric or knitted fabric. Excellent. In addition, since elution of the polymer having the hygroscopic property of the core component into the hot water during hot water treatment such as dyeing is suppressed, the hygroscopicity is maintained even after the hot water treatment. The r / R of the core-sheath type composite fiber is more preferably 0.035 or less, and further preferably 0.030 or less.

  The core-sheath type composite fiber of the present invention may be one in which various modifications are performed by adding a secondary additive to the core component and / or the sheath component. Specific examples of secondary additives include compatibilizers, plasticizers, antioxidants, ultraviolet absorbers, infrared absorbers, fluorescent whitening agents, mold release agents, antibacterial agents, nucleating agents, thermal stabilizers, charging Examples include, but are not limited to, inhibitors, anti-coloring agents, regulators, matting agents, antifoaming agents, preservatives, gelling agents, latexes, fillers, inks, coloring agents, dyes, pigments, and fragrances. These secondary additives may be used alone or in combination.

  The extrapolated melting start temperature of the core-sheath composite fiber of the present invention is 150 ° C. or higher. The extrapolation melting start temperature of the core-sheath type composite fiber in the present invention refers to a value calculated by the method described in the examples. When a plurality of melting peaks were observed, the extrapolated melting start temperature was calculated from the melting peak on the lowest temperature side. If the extrapolated melting start temperature of the core-sheath type composite fiber is 150 ° C. or higher, the fusion between fibers accompanying the contact with the heating roller or heating heater in the stretching or false twisting process is suppressed, so the heating roller or heating There is little generation of deposits, yarn breakage, and fluff on heaters and guides, good processability, and less dyeing spots and fluff when used in textile structures such as woven fabrics and knitted fabrics. . The extracorporeal melting start temperature of the core-sheath type composite fiber is more preferably 170 ° C. or higher, further preferably 190 ° C. or higher, and particularly preferably 200 ° C. or higher.

  The core / sheath component composite ratio (weight ratio) of the core-sheath composite fiber of the present invention is preferably 10/90 to 70/30. The core / sheath component composite ratio (weight ratio) of the core-sheath composite fiber in the present invention refers to a value calculated by the method described in the examples. If the composite ratio of the core component of the core-sheath composite fiber is 10% by weight or more, a core-sheath composite fiber excellent in hygroscopicity is obtained, which is preferable. The composite ratio of the core component of the core-sheath composite fiber of the present invention is more preferably 20% by weight or more, and further preferably 30% by weight or more. On the other hand, if the composite ratio of the core component of the core-sheath-type conjugate fiber is 70% by weight or less, that is, the composite ratio of the sheath component is 30% by weight or more, it is preferable because the firmness, stiffness and dry feel of the sheath component can be obtained. . In addition, sheath cracking due to external force during stretching and false twisting, and sheath cracking due to volume swelling of the core component during moisture absorption are suppressed. This is preferable because a decrease in hygroscopicity due to elution of the hygroscopic polymer of the core component to the core is suppressed. The composite ratio of the core component of the core-sheath composite fiber of the present invention is more preferably 60% by weight or less, and further preferably 50% by weight or less.

  The fineness of the core-sheath composite fiber of the present invention as a multifilament is not particularly limited and can be appropriately selected depending on the application and required characteristics, but is preferably 10 to 500 dtex. The fineness in the present invention refers to a value measured by the method described in the examples. If the fineness of the core-sheath type composite fiber is 10 dtex or more, it is preferable because there is little yarn breakage and process passability is good, and there is little generation of fluff during use and excellent durability. The fineness of the core-sheath composite fiber is more preferably 30 dtex or more, and further preferably 50 dtex or more. On the other hand, if the fineness of the core-sheath type composite fiber is 500 dtex or less, the flexibility of the fiber and the fiber structure is not impaired, which is preferable. The fineness of the core-sheath type composite fiber is more preferably 400 dtex or less, and further preferably 300 dtex or less.

  The single yarn fineness of the core-sheath type composite fiber of the present invention is not particularly limited and can be appropriately selected according to the use and required characteristics, but is preferably 0.5 to 4.0 dtex. The single yarn fineness in the present invention refers to a value obtained by dividing the fineness measured by the method described in the examples by the number of single yarns. If the single-filament fineness of the core-sheath type composite fiber is 0.5 dtex or more, it is preferable because the yarn breakage is small, the process passing property is good, the generation of fluff is small during use, and the durability is excellent. The single yarn fineness of the core-sheath type composite fiber is more preferably 0.6 dtex or more, and still more preferably 0.8 dtex or more. On the other hand, if the single yarn fineness of the core-sheath composite fiber is 4.0 dtex or less, the flexibility of the fiber and the fiber structure is not impaired, which is preferable. The single-filament fineness of the core-sheath type composite fiber is more preferably 2.0 dtex or less, and further preferably 1.5 dtex or less.

  The strength of the core-sheath composite fiber of the present invention is not particularly limited and can be appropriately selected according to the use and required characteristics, but is 2.0 to 5.0 cN / dtex from the viewpoint of mechanical characteristics. Is preferred. The strength in the present invention refers to a value measured by the method described in the examples. If the strength of the core-sheath type composite fiber is 2.0 cN / dtex or more, it is preferable because the generation of fluff is small during use and the durability is excellent. The strength of the core-sheath type composite fiber is more preferably 2.5 cN / dtex or more, and further preferably 3.0 cN / dtex or more. On the other hand, if the strength of the core-sheath composite fiber is 5.0 cN / dtex or less, the flexibility of the fiber and the fiber structure is not impaired, which is preferable.

  The elongation of the core-sheath type composite fiber of the present invention is not particularly limited and can be appropriately selected according to the use and required characteristics, but is preferably 10 to 60% from the viewpoint of durability. The elongation in the present invention refers to a value measured by the method described in the examples. If the elongation of the core-sheath type composite fiber is 10% or more, the abrasion resistance of the fiber and the fiber structure is good, the occurrence of fluff is small during use, and the durability is good, which is preferable. The elongation of the core-sheath type composite fiber is more preferably 15% or more, and further preferably 20% or more. On the other hand, if the elongation of the core-sheath composite fiber is 60% or less, it is preferable because the dimensional stability of the fiber and the fiber structure becomes good. The elongation of the core-sheath type composite fiber is more preferably 55% or less, and further preferably 50% or less.

  The difference in moisture absorption (ΔMR) of the core-sheath type composite fiber of the present invention after hot water treatment is 2.0 to 10.0%. In the present invention, the moisture absorption difference (ΔMR) after the hot water treatment refers to a value measured by the method described in the examples. ΔMR is the difference between the moisture absorption rate at a temperature of 30 ° C. and a humidity of 90% RH assuming the temperature and humidity in the clothes after light exercise, and the moisture absorption rate at a temperature of 20 ° C. and a humidity of 65% RH as the outside air temperature humidity. That is, ΔMR is a hygroscopic index, and the higher the value of ΔMR, the better the wearing comfort. The difference in moisture absorption rate (ΔMR) of the present invention is a value after hydrothermal treatment, and is very important in that it expresses hygroscopicity even after hydrothermal treatment such as dyeing. If ΔMR after the hot-water treatment of the core-sheath type composite fiber is 2.0% or more, there is little feeling of stuffiness in the clothes and wear comfort is expressed. The ΔMR after hydrothermal treatment of the core-sheath type composite fiber is more preferably 3.0% or more, further preferably 3.5% or more, and particularly preferably 4.0% or more. On the other hand, if the ΔMR after the hydrothermal treatment of the core-sheath type composite fiber is 10.0% or less, the process passability and handleability are good, and the durability during use is also excellent.

  The core-sheath type composite fiber of the present invention has one portion where the core component is exposed on the surface in the fiber cross section, and the length R of the outer periphery of the fiber cross section and the surface exposed portion of the core component If ratio (r / R) of length r satisfies 0.005 or more and less than 0.050, there is no restriction | limiting in particular regarding the cross-sectional shape of a fiber, It can select suitably according to a use or a required characteristic. The core-sheath type composite fiber of the present invention is not particularly limited with respect to the form of the fiber, and may be any form such as monofilament, multifilament, and staple.

The core-sheath type composite fiber of the present invention can be processed into false twists and twisted yarns in the same manner as general fibers, and weaving and knitting can be handled in the same manner as general fibers.
The form of the fiber structure composed of the core-sheath composite fiber and / or false twisted yarn of the present invention is not particularly limited, and is made into a woven fabric, a knitted fabric, a pile fabric, a nonwoven fabric, a spun yarn, a stuffed cotton or the like according to a known method. Can do. Further, the fiber structure composed of the core-sheath type composite fiber and / or false twisted yarn of the present invention may be any woven structure or knitted structure, such as plain weave, twill weave, satin weave, or these changed weaving, warp knitting, A weft knitting, a round knitting, a lace knitting, or a change knitting thereof can be suitably employed.

  The core-sheath type composite fiber of the present invention may be combined with other fibers by knitting or knitting when making a fiber structure, or may be made into a fiber structure after being mixed with other fibers. .

Next, the manufacturing method of the core-sheath type composite fiber of this invention is shown below.
As a method for producing the core-sheath composite fiber of the present invention, a known melt spinning method, stretching method, false twisting method can be used.

  In the present invention, it is preferable that the core component and the sheath component are dried and the water content is 300 ppm or less before melt spinning. A water content of 300 ppm or less is preferable because molecular weight reduction due to hydrolysis and foaming due to moisture are suppressed during melt spinning, and spinning can be performed stably. The water content is more preferably 100 ppm or less, and further preferably 50 ppm or less.

  In the present invention, the pre-dried chips are supplied to a melt spinning machine such as an extruder type or a pressure melter type, and the core component and the sheath component are separately melted and measured with a metering pump. After that, after introducing into the spinning pack heated in the spinning block and filtering the molten polymer in the spinning pack, the core component and the sheath component are merged with the core-sheath type composite spinneret to form a core-sheath structure, from the spinneret. Discharge into fiber yarn. The fiber yarn discharged from the spinneret is cooled and solidified by a cooling device, taken up by a first godet roller, wound up by a winder through a second godet roller, and taken up as a wound yarn. In addition, in order to improve the spinning maneuverability, productivity, and mechanical properties of the fiber, a heating cylinder or a thermal insulation cylinder having a length of 2 to 20 cm may be installed below the spinneret as necessary. Moreover, you may supply oil to a fiber yarn using an oil supply apparatus, and you may give an entanglement to a fiber yarn using an entanglement apparatus.

  The spinning temperature in melt spinning can be appropriately selected according to the melting point and heat resistance of the core component and the sheath component, but is preferably 240 to 320 ° C. If the spinning temperature is 240 ° C. or higher, the elongation viscosity of the fiber yarn discharged from the spinneret is sufficiently lowered, so that the discharge is stable, and further, the spinning tension is not excessively high and the yarn breakage is suppressed. This is preferable. The spinning temperature is more preferably 250 ° C. or higher, and further preferably 260 ° C. or higher. On the other hand, a spinning temperature of 320 ° C. or lower is preferable because thermal decomposition during spinning can be suppressed, and deterioration of mechanical properties and coloring of fibers can be suppressed. The spinning temperature is more preferably 310 ° C. or lower, and further preferably 300 ° C. or lower.

  The base used for melt spinning is one part of the core component in the insert type, pipe type or distribution type composite base in order to make the fiber cross section (FIG. 1) having one part where the core component is exposed on the surface. A core-sheath cross-section die that was processed so as to be exposed on the surface was used.

  The spinning speed in melt spinning can be appropriately selected according to the composition of the core component, sheath component, spinning temperature, and the like. It is preferable that the spinning speed is 500 to 6000 m / min in the case of the two-step method in which the melt spinning is once performed and the winding is performed, and then drawing or false twisting is performed separately. A spinning speed of 500 m / min or more is preferable because the running yarn is stable and yarn breakage can be suppressed. The spinning speed in the two-step method is more preferably 1000 m / min or more, and further preferably 1500 m / min or more. On the other hand, a spinning speed of 6000 m / min or less is preferable because stable spinning can be performed without yarn breakage by suppressing spinning tension. The spinning speed in the two-step method is more preferably 4500 m / min or less, and further preferably 4000 m / min or less. Moreover, it is preferable that the spinning speed in the case of the one-step method in which spinning and stretching are simultaneously performed without winding once is 500 to 5000 m / min for the low speed roller and 2500 to 6000 m / min for the high speed roller. It is preferable that the low-speed roller and the high-speed roller are within the above ranges because the running yarn is stabilized, yarn breakage can be suppressed, and stable spinning can be performed. The spinning speed in the one-step method is more preferably 1000 to 4500 m / min for the low speed roller, 3500 to 5500 m / min for the high speed roller, 1500 to 4000 m / min for the low speed roller, and 4000 to 5000 m / min for the high speed roller. More preferably.

  When stretching is performed by a one-step method or a two-step method, any one of a one-step stretching method or a two-step or more multi-stage stretching method may be used. The heating method in stretching is not particularly limited as long as it is a device that can directly or indirectly heat the traveling yarn. Specific examples of the heating method include, but are not limited to, a heating roller, a hot pin, a hot plate, a liquid bath such as hot water and hot water, a gas bath such as hot air and steam, and a laser. These heating methods may be used alone or in combination. Heating methods include control of the heating temperature, uniform heating of the running yarn, and contact with the heating roller, contact with the hot pin, contact with the hot plate, and immersion in a liquid bath from the viewpoint of not complicating the device. It can be suitably employed.

  The stretching temperature in the case of stretching can be appropriately selected depending on the extrapolation melting start temperature of the polymer of the core component and the sheath component, the strength of the fiber after stretching, the elongation, etc. Preferably there is. A drawing temperature of 50 ° C. or higher is preferable because the yarn supplied to the drawing is sufficiently preheated, the thermal deformation during drawing becomes uniform, and the occurrence of fineness spots can be suppressed. The stretching temperature is more preferably 60 ° C. or higher, and further preferably 70 ° C. or higher. On the other hand, if the stretching temperature is 150 ° C. or lower, it is preferable because fusion and thermal decomposition of fibers due to contact with the heating roller can be suppressed, and process passability and quality are good. Moreover, since the slipperiness of the fiber with respect to a drawing roller becomes favorable, yarn breakage is suppressed and stable drawing can be performed, which is preferable. The stretching temperature is more preferably 145 ° C. or less, and further preferably 140 ° C. or less. Moreover, you may perform the heat setting of 60-150 degreeC as needed.

  The stretching ratio in the case of stretching can be appropriately selected according to the elongation of the fiber before stretching, the strength and elongation of the fiber after stretching, and the like, and is 1.02 to 7.0 times. Is preferred. A draw ratio of 1.02 or more is preferable because mechanical properties such as fiber strength and elongation can be improved by drawing. The draw ratio is more preferably 1.2 times or more, and further preferably 1.5 times or more. On the other hand, if the draw ratio is 7.0 times or less, yarn breakage during drawing is suppressed, and stable drawing can be performed. The draw ratio is more preferably 6.0 times or less, and still more preferably 5.0 times or less.

  The stretching speed for 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 corresponding to the spinning speed corresponds to the stretching speed. The stretching speed when stretching by the two-step method is preferably 30 to 1000 m / min. A stretching speed of 30 m / min or more is preferable because the running yarn is stable and yarn breakage can be suppressed. In the case of stretching by a two-step method, the stretching speed is more preferably 50 m / min or more, and further preferably 100 m / min or more. On the other hand, a stretching speed of 1000 m / min or less is preferable because yarn breakage during stretching can be suppressed and stable stretching can be performed. The stretching speed when stretching by the two-step method is more preferably 900 m / min or less, and still more preferably 800 m / min or less.

  When false twisting is performed, so-called bulerial processing using both a single-stage heater and a two-stage heater can be appropriately selected in addition to the so-called Woolley process using only a single-stage heater. 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 disk type, a belt nip type, and a pin type.

  The heater temperature when performing false twisting can be appropriately selected according to the extrapolated melting start temperature of the core component and the sheath component polymer, but is preferably 120 to 210 ° C. If the heater temperature is 120 ° C. or higher, the yarn supplied to the false twisting process is sufficiently preheated, the thermal deformation accompanying stretching becomes uniform, and the occurrence of fineness unevenness can be suppressed. The heater temperature is more preferably 140 ° C. or higher, and further preferably 160 ° C. or higher. On the other hand, if the heater temperature is 210 ° C. or lower, the fusion between fibers and thermal decomposition due to contact with the heater are suppressed, so there is little dirt such as yarn breakage and heater, and the process passability and quality are low. It is preferable because it is good. The heater temperature is more preferably 200 ° C. or less, and further preferably 190 ° C. or less.

  Although the draw ratio in the case of false twisting can be appropriately selected according to the elongation of the fiber before false twisting, the strength and elongation of the fiber after false twisting, etc., 1.01 to 2 .5 times is preferable. A draw ratio of 1.01 or more is preferable because mechanical properties such as fiber strength and elongation can be improved by drawing. The draw ratio is more preferably 1.2 times or more, and further preferably 1.5 times or more. On the other hand, a draw ratio of 2.5 times or less is preferable because yarn breakage during false twisting can be suppressed and stable false twisting can be performed. The draw ratio is more preferably 2.2 times or less, and further preferably 2.0 times or less.

  Although the processing speed in the case of false twisting can be selected as appropriate, it is preferably 200 to 1000 m / min. A processing speed of 200 m / min or more is preferable because the running yarn is stable and yarn breakage can be suppressed. The processing speed is more preferably 300 m / min or more, and still more preferably 400 m / min or more. On the other hand, if 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 processing speed is more preferably 900 m / min or less, and still more preferably 800 m / min or less.

In this invention, you may dye | stain in any state of a fiber or a fiber structure as needed. In the present invention, a disperse dye can be suitably employed as the dye.
There is no restriction | limiting in particular in the dyeing | staining method in this invention, A cheese dyeing machine, a liquid dyeing machine, a drum dyeing machine, a beam dyeing machine, a jigger, a high-pressure jigger etc. can be employ | adopted suitably according to a well-known method.
In this invention, there is no restriction | limiting in particular regarding dye density | concentration and dyeing | staining temperature, A well-known method can be employ | adopted suitably. If necessary, scouring may be performed before the dyeing process, or reduction cleaning may be performed after the dyeing process.

  The core-sheath type composite fiber of the present invention and the false twisted yarn and fiber structure comprising the same are excellent in hygroscopicity. Therefore, it can be suitably used in applications that require comfort and quality. Examples include, but are not limited to, general clothing uses, sports clothing uses, bedding uses, interior uses, and material uses.

  Hereinafter, the present invention will be described in more detail with reference to examples. In addition, each characteristic value in an Example is calculated | required with the following method.

A. Difference in moisture absorption between core and sheath components (△ MR)
A core or sheath polymer was used as a sample, first dried with hot air at 60 ° C. for 30 minutes, and then allowed to stand in an Espec constant temperature and humidity chamber LHU-123 conditioned at 20 ° C. and humidity 65% RH for 24 hours. Then, after measuring the weight (W1) of the polymer, the polymer was allowed to stand for 24 hours in a thermo-hygrostat adjusted to a temperature of 30 ° C. and a humidity of 90% RH, and the weight (W2) of the polymer was measured. Then, it dried with hot air at 105 degreeC for 2 hours, and measured the weight (W3) of the polymer after absolute drying. Using the weights W1 and W3 of the polymer, the moisture absorption rate MR1 (%) when left standing in an atmosphere of 20 ° C. and 65% humidity for 24 hours from the absolutely dry state is calculated according to the following formula. Is used to calculate the moisture absorption rate MR2 (%) when left in an atmosphere of 30 ° C. and 90% humidity for 24 hours from the absolutely dry state, and then the moisture absorption rate difference (ΔMR) is calculated using the following equation. Calculated. The measurement was performed five times for each sample, and the average value was defined as the difference in moisture absorption rate (ΔMR).
MR1 (%) = {(W1-W3) / W3} × 100
MR2 (%) = {(W2-W3) / W3} × 100
Moisture absorption difference (ΔMR) (%) = MR2−MR1.

B. Extrapolation melting start temperature Using the TA instrument differential scanning calorimeter (DSC) Q2000 model, the extrapolation melting start temperature was measured using the core component and the sheath component polymer and the fibers obtained in the examples as samples. . First, about 5 mg of a sample was heated from 0 ° C. to 280 ° C. at a temperature rising rate of 50 ° C./min under a nitrogen atmosphere, and held at 280 ° C. for 5 minutes to remove the thermal history of the sample. Then, after rapidly cooling from 280 ° C. to 0 ° C., the temperature was increased again from 0 ° C. to 280 ° C. at a rate of temperature increase of 3 ° C./min, temperature modulation amplitude ± 1 ° C., temperature modulation period 60 seconds, and TDSC measurement was performed. In accordance with JIS K7121: 1987 (Plastic transition temperature measurement method) 9.1, the extrapolated melting start temperature was calculated from the melting peak observed during the second temperature raising process. The measurement was performed 3 times per sample, and the average value was used as the extrapolated melting start temperature. When a plurality of melting peaks were observed, the extrapolated melting start temperature was calculated from the melting peak on the lowest temperature side.

C. Core / sheath composite ratio The core / sheath composite ratio (weight ratio) was calculated from the weight of the core component used as the raw material of the core-sheath composite fiber and the weight of the sheath component.

D. Thread breakage Under the false twist conditions described in each example, the number of yarn breaks when processed for 10 hours was counted to obtain thread breakage (times).

E. Deposits Observe the heater, cooling plate, friction disk, and guide of the drawing false twisting machine after processing for 10 hours under the false twisting conditions described in each example. “Slightly” is indicated by ○, “Many deposits” is indicated by Δ, “Much deposits” are indicated by ×, and ○ and ◎ are indicated as acceptable.

F. In an environment with a fineness of 20 ° C. and a humidity of 65% RH, 100 m of the fiber obtained in the example was scraped using an electric measuring machine manufactured by INTEC. The weight of the obtained skein was measured, and the fineness (dtex) was calculated using the following formula. In addition, the measurement was performed 5 times per sample, and the average value was defined as the fineness.

  Fineness (dtex) = weight of fiber 100 m (g) × 100

G. Strength and elongation The strength and elongation were calculated according to JIS L1013: 2010 (chemical fiber filament yarn test method) 8.5.1 using the fiber obtained in the example as a sample. In an environment of a temperature of 20 ° C. and a humidity of 65% RH, a tensile test was performed using a Tensilon UTM-III-100 model manufactured by Orientec 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 fineness (dtex), and using the elongation (L1) and the initial sample length (L0) at the point indicating the maximum load, The elongation (%) was calculated by the formula. The measurement was carried out 10 times per sample, and the average values were taken as the strength and elongation.
Elongation (%) = {(L1-L0) / L0} × 100.

H. The length R of the outer periphery of the fiber cross section, the length r of the surface exposed portion of the core component, r / R
The fibers obtained according to the examples were embedded with epoxy resin, frozen with a Reichert FC 4E cryosectioning system, and cut with a Reichert-Nissei ultracut N (ultramicrotome) equipped with a diamond knife. Thereafter, the cut surface, that is, the fiber cross section was vapor-deposited with a platinum-palladium alloy, and observed at 1000 times using a Hitachi scanning electron microscope (SEM) S-4000 type, and a micrograph of the fiber cross section was taken. Thirty samples were randomly extracted from the obtained photographs, and using image processing software (WINROOF manufactured by Mitani Corp.), the length of the outer periphery of all fiber cross sections and the length of the exposed surface of all core components After the measurement, the average value of 30 fibers was calculated and used as the length R of the outer circumference of the fiber cross section and the length r of the surface exposed portion of the core component.

  r / R was calculated by the following formula using the length R of the outer circumference of the fiber cross section calculated above and the length r of the surface exposed portion of the core component.

Ratio of the length R of the outer periphery of the fiber cross section to the length r of the surface exposed portion of the core component (r / R) = r / R
Since only the surface exposure of the core component has a plurality of locations only in Comparative Example 8, regarding the length r and r / R of the surface exposure portion of the core component, the sum of the lengths of the surface exposure portions of the core component is r, and r / R was calculated.

I. Moisture absorption difference after scouring and hot water treatment (△ MR)
Using the fiber obtained in the example as a sample, about 2 g of cylindrical knitting was produced using a Yoko Sangyo circular knitting machine NCR-BL (3-inch and half (8.9 cm), 27 gauge), then 1 g of sodium carbonate / L, scouring at 80 ° C. for 20 minutes in an aqueous solution containing the surfactant Sunmol BK-80 manufactured by Nikka Chemical, and then drying in a hot air dryer at 60 ° C. for 60 minutes to obtain a scoured tubular knitting. Further, after the scoured tube knitting is subjected to hot water treatment under conditions of a bath ratio of 1: 100, a treatment temperature of 130 ° C., and a treatment time of 60 minutes, the tube is dried in a hot air dryer at 60 ° C. for 60 minutes, and the tube after the hot water treatment. Knitted.

  The moisture absorption rate (%) was calculated according to the moisture content of JIS L1096: 2010 (fabric and knitted fabric test method) 8.10 using a sample after scouring and hot water treatment as a sample. First, after drying the tubular knitting at 60 ° C. for 30 minutes with hot air, the tubular knitting was left in an Espec constant temperature and humidity chamber LHU-123 conditioned at a temperature of 20 ° C. and a humidity of 65% RH for 24 hours. After measuring the weight (W1) of the knitting, the tubular knitting was allowed to stand for 24 hours in a thermo-hygrostat adjusted to a temperature of 30 ° C. and a humidity of 90% RH, and the weight of the tubular knitting (W2) was measured. Thereafter, the tubular knitting was dried with hot air at 105 ° C. for 2 hours, and the weight (W3) of the tubular knitting after absolutely dried was measured. By using the weights W1 and W3 of the tubular knitting, the moisture absorption rate MR1 (%) when left standing in an atmosphere of a temperature of 20 ° C. and a humidity of 65% RH from the absolutely dry state for 24 hours is calculated according to the following formula. , After calculating the moisture absorption rate MR2 (%) when left in an atmosphere of 30 ° C. and 90% humidity for 24 hours from the absolutely dry state using W3, the difference in moisture absorption rate (ΔMR ) Was calculated. The measurement was performed five times for each sample, and the average value was defined as the difference in moisture absorption rate (ΔMR).

MR1 (%) = {(W1-W3) / W3} × 100
MR2 (%) = {(W2-W3) / W3} × 100
Moisture absorption difference (ΔMR) (%) = MR2−MR1.

J. et al. Fusion Welded tubular braids prepared in I above were vapor-deposited with platinum-palladium alloy, and observed at 1000 times using Hitachi scanning electron microscope (SEM) S-4000 type. Micrographs were taken. In the obtained five photographs, the total number of the fused portions was defined as fusion (location).

K. Cylindrical cracking After the hydrothermal treatment produced in I above, the tubular braid was vapor-deposited with a platinum-palladium alloy and observed at 1000 times using a Hitachi scanning electron microscope (SEM) S-4000 type. Micrographs were taken. In the obtained five photographs, the total of the portions where the sheath was broken was defined as the sheath crack (location).

L. Leveling property After scouring the cylindrical knitting produced in the same manner as in I above, heat-heat set at 160 ° C. for 2 minutes, and as a disperse dye, Kayalon Polyester Blue UT-YA manufactured by Nippon Kayaku as a disperse dye Was dyed in a dyeing solution adjusted to pH 5.0 with a bath ratio of 1: 100, a dyeing temperature of 130 ° C., and a dyeing time of 60 minutes. When a cationic dyeable polyester is used as the sheath component, 1.0% by weight of Kayacryl Blue 2RL-ED manufactured by Nippon Kayaku is added as a cationic dye, and the dyeing solution is adjusted to pH 4.0 in a bath. Dyeing was performed at a ratio of 1: 100, a dyeing temperature of 130 ° C., and a dyeing time of 60 minutes.

  Regarding tube knitting after dyeing, according to the consensus of five inspectors who have experience of quality judgment for more than 5 years, “It is dyed very uniformly and no dyed spots are observed” `` Stained and almost no dyed spots are found '' ○, `` Almost not evenly dyed and slightly dyed spots are seen '' △, `` Uniformly dyed and spotted spots are not clearly seen '' Is accepted ", and ○ and ◎ are accepted.

M.M. Grade (fluff, grade)
Regarding the tube knitting after dyeing produced in the above L, according to the consensus of five inspectors having experience of quality judgment for 5 years or more, “No fluff and excellent quality” ◎, “There is almost no fluff, “Excellent quality” was rated as “◯”, “Fuzzy and inferior in quality” as “△”, “Many fluffs and inferior in quality” as “x”, and “Good” and “◎” as acceptable.

Example 1
Polybutylene terephthalate copolymerized with 30% by weight of polyethylene glycol having a number average molecular weight of 3400 g / mol (PEG 4000S manufactured by Sanyo Chemical Industries) as a core component and polyethylene terephthalate (IV = 0.66) as a sheath component, each at 150 ° C. After vacuum drying for 12 hours, the core component is fed to the extruder type composite spinning machine at a compounding ratio of 40% by weight and the sheath component is 60% by weight, and melted separately. A spun yarn (single yarn cross-sectional shape: FIG. 1) was obtained by discharging from a core-sheath-type dispensing spinneret (number of holes: 72). The spun yarn is cooled by cooling air with an air temperature of 20 ° C. and an air speed of 20 m / min, applied with an oil agent by an oil supply device, converged, and taken up by a first godet roller rotating at 2500 m / min. An undrawn yarn of 144 dtex-72f was obtained by winding with a winder via a second godet roller rotating at the same speed as the dead roller. Then, using a drawing false twisting machine (twisted part: friction disk type, heater part: contact type), the obtained undrawn yarn was drawn and twisted under the conditions of a heater temperature of 170 ° C. and a magnification of 1.7 times, An 84 dtex-72f false twisted yarn was obtained.

  Table 1 shows the evaluation results of the fiber characteristics, fabric characteristics and process passability of the obtained fibers. The yarn breakage at the time of false twisting was 0, and no deposits were seen on the heater, guide, etc. after false twisting, and the process passability was very good. Further, there was almost no decrease in hygroscopicity due to the hot water treatment, and the hygroscopicity was good even after the hot water treatment. Furthermore, the fusion between fibers and sheath cracking were not observed, and the leveling and quality were acceptable.

Examples 2-9, Comparative Example 1
A false twisted yarn was prepared in the same manner as in Example 1 except that the copolymerization ratio and core / sheath composite ratio of polyethylene glycol, which is the copolymer component of the core component, were changed as shown in Table 1.
Table 1 shows the evaluation results of the fiber characteristics, fabric characteristics and process passability of the obtained fibers. Even when the copolymerization ratio of polyethylene glycol or the composite ratio of the core component and the sheath component was changed, both the process passability and the fabric characteristics were good. In Comparative Example 1, the hygroscopicity after scouring was low, and as a result, the hygroscopicity after the hot water treatment was extremely poor.

Examples 10-15, Comparative Examples 2, 3
A false twisted yarn was prepared in the same manner as in Example 1 except that the number average molecular weight, copolymerization rate, and core / sheath composite ratio of polyethylene glycol, which is a copolymer component of the core component, were changed as shown in Table 2.

  Table 2 shows the evaluation results of the fiber characteristics, fabric characteristics and process passability of the obtained fibers. When the number average molecular weight of polyethylene glycol, the copolymerization rate, or the composite ratio of the core component and the sheath component were changed, both the process passability and the fabric characteristics were good. In Comparative Example 2, the hygroscopicity after scouring was low, and as a result, the hygroscopicity after the hot water treatment was extremely poor. Further, in Comparative Example 3, the extrapolated melting start temperature of the core component was not detected, and the core component did not have crystallinity. Therefore, yarn breakage and deposits were extremely large, and the process passability was extremely poor. In addition, many fusions and sheath cracks were observed, and leveling and quality did not reach acceptable levels. Furthermore, in the micrographs in which fusion and sheath cracks were observed, the elution of the hygroscopic polymer of the core component was observed. As a result of the elution of the hygroscopic polymer of the core component by hot water treatment, Hygroscopicity was greatly reduced by the water treatment, and the hygroscopicity after the hot water treatment was extremely low.

Examples 16-22, Comparative Examples 4-6
The number average molecular weight of polyethylene glycol, the copolymerization rate as shown in Table 3, polybutylene terephthalate copolymerized as a core component, polybutylene terephthalate (IV = 0.66) as a sheath component, the spinning temperature is 255 ℃, The core / sheath composite ratio was as shown in Table 3, and in Example 18 and Comparative Examples 4 and 5, false twisted yarn was prepared in the same manner as in Example 1 except that the heater temperature of the drawing false twister was changed to 150 ° C. .

  Table 3 shows the evaluation results of the fiber characteristics, fabric characteristics and process passability of the obtained fibers. In Examples 18 to 24, even when the number average molecular weight, the copolymerization rate, and the core / sheath composite ratio of polyethylene glycol were changed, both process passability and fabric characteristics were good. In Comparative Example 4, the hygroscopicity after scouring was low, and as a result, the hygroscopicity after the hot water treatment was extremely poor. In Comparative Example 5, the hygroscopicity after scouring was high, but the hygroscopicity was greatly reduced after the hot water treatment, and the process passability was poor, and the leveling and quality did not reach acceptable levels. In Comparative Example 6, since the extrapolated melting start temperature of the core component was low, thread breakage and deposits were extremely large, and the process passability was extremely poor. Moreover, the hygroscopicity after scouring was low, and as a result, the hygroscopicity after the hot water treatment was extremely poor.

Examples 23-25
In Examples 23 and 24, the core component was nylon 6 obtained by copolymerizing polyethylene glycol having a number average molecular weight of 3400 g / mol (PEG 4000S manufactured by Sanyo Chemical Industries) at a copolymerization ratio shown in Table 4, and in Example 25, “PEBAX MH1657” manufactured by Arkema. A false twisted yarn was produced in the same manner as in Example 1 except that the above was changed.
Table 4 shows the evaluation results of the fiber characteristics, fabric characteristics and process passability of the obtained fibers. Even when the core component was changed to polyether amide, both process passability and fabric characteristics were good.

Example 26
A false twisted yarn was produced in the same manner as in Example 1 except that the core component was “PAS-40N” manufactured by Toray and the heater temperature of the drawing false twister was changed to 150 ° C.

  Table 4 shows the evaluation results of the fiber characteristics, fabric characteristics and process passability of the obtained fibers. Even when the core component was changed to polyether ester amide, both process passability and fabric characteristics were good.

Example 27
The sheath component is polyethylene terephthalate (IV = 0.66) copolymerized with 1.5 mol% of 5-sulfoisophthalic acid sodium salt and 1.0 wt% of polyethylene glycol (PEG 1000 manufactured by Sanyo Chemical Industries) having a number average molecular weight of 1000 g / mol. A false twisted yarn was produced in the same manner as in Example 10 except that it was changed to.

  Table 4 shows the evaluation results of the fiber characteristics, fabric characteristics and process passability of the obtained fibers. Even when cationic dyeable polyester was used as the sheath component, both process passability and fabric characteristics were good.

Comparative Example 7
A false twisted yarn was produced in the same manner as in Example 10 except that the cross-sectional shape was changed to FIG.

  Table 4 shows the evaluation results of the fiber characteristics, fabric characteristics and process passability of the obtained fibers. There was no yarn breakage, almost no deposit was seen, and the process passage was good. However, although there is no fusion, since the core component hygroscopic polymer is completely covered with the sheath component, many sheath cracks are observed due to the volume swelling of the hygroscopic polymer during hydrothermal treatment. It was. As a result, leveling and quality did not reach acceptable levels.

Comparative Example 8
A false twisted yarn was produced in the same manner as in Example 10 except that the cross-sectional shape was changed to FIG.
Table 4 shows the evaluation results of the fiber characteristics, fabric characteristics and process passability of the obtained fibers. The yarn breakage and deposits were very large, and the process passability was extremely poor. Moreover, since the core component was exposed at a plurality of locations on the surface, peeling and falling off of the sheath were confirmed (counted collectively as sheath cracks in Table 4). As a result, leveling and quality did not reach acceptable levels.

Since the core-sheath type composite fiber of the present invention is suppressed from fusing in the drawing and false twisting processes, the occurrence of yarn breakage and fluff is less and the process passability is good. In addition, when a fiber structure such as a woven fabric or a knitted fabric is used, there is little generation of dyed spots and fluff, and the quality is excellent. Furthermore, peeling is suppressed by providing one opening in advance, and sheath cracking associated with swelling of the hygroscopic polymer of the core component during hot water treatment such as dyeing is suppressed. Moreover, elution of the hygroscopic polymer is suppressed, and the hygroscopic property is excellent even after the hot water treatment. Therefore, it can be suitably used as a fiber structure such as a woven or knitted fabric or a non-woven fabric for clothing.

1. Core component Sheath component

Claims (12)

  Both the core component and the sheath component are polymers having crystallinity, the core component is a hygroscopic polymer, and has one portion where the core component is exposed on the surface in the cross section of the fiber. A sheath-core conjugate fiber in which the ratio (r / R) of the length R of the outer periphery of the surface to the length r of the exposed surface portion of the core component is 0.005 or more and less than 0.050, and the sheath-core conjugate fiber A core-sheath-type composite fiber having an extrapolated melting start temperature of 150 ° C. or more and a moisture absorption difference (ΔMR) after hot water treatment of 2.0 to 10.0%.   The core-sheath composite fiber according to claim 1, wherein a composite ratio (weight ratio) of the core component / sheath component is 10/90 to 70/30.   The hygroscopic polymer of the core component contains at least one selected from the group consisting of polyether ester, polyether amide, and polyether ester amide containing polyether as a copolymer component. 2. The core-sheath type composite fiber according to 2.   The core-sheath composite fiber according to claim 3, wherein the polyether is at least one polyether selected from the group consisting of polyethylene glycol, polypropylene glycol, and polybutylene glycol.   The core-sheath type composite fiber according to claim 3 or 4, wherein the polyether ester comprises an aromatic dicarboxylic acid and an aliphatic diol as main constituent components and a polyether as a copolymer component.   The core-sheath composite fiber according to claim 5, wherein the aliphatic diol is ethylene glycol, and the polyether has a number average molecular weight of 8000 to 30000 g / mol.   The core-sheath composite fiber according to claim 6, wherein the polyether has a copolymerization ratio of 10 to 35% by weight.   The core-sheath conjugate fiber according to claim 5, wherein the aliphatic diol is 1,4-butanediol, and the polyether has a number average molecular weight of 2000 to 30000.   The core-sheath type composite fiber according to claim 8, wherein the polyether has a copolymerization ratio of 25 to 60% by weight.   The sheath-core composite fiber according to any one of claims 1 to 9, wherein the sheath component is a cationic dyeable polyester.   A false twisted yarn obtained by twisting two or more core-sheath composite fibers according to any one of claims 1 to 10.   A fiber structure using at least a part of the core-sheath composite fiber according to any one of claims 1 to 10 and / or the false twisted yarn according to claim 11.