US20230323568A1 - Polyamide core-sheath composite fiber and fabric - Google Patents

Polyamide core-sheath composite fiber and fabric Download PDF

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US20230323568A1
US20230323568A1 US18/025,298 US202118025298A US2023323568A1 US 20230323568 A1 US20230323568 A1 US 20230323568A1 US 202118025298 A US202118025298 A US 202118025298A US 2023323568 A1 US2023323568 A1 US 2023323568A1
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core
sheath
polyamide
component
composite fiber
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Taisuke Kishida
Daisuke Yoshioka
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Toray Industries Inc
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Toray Industries Inc
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Assigned to TORAY INDUSTRIES, INC. reassignment TORAY INDUSTRIES, INC. ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: KISHIDA, TAISUKE, YOSHIOKA, DAISUKE
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    • D—TEXTILES; PAPER
    • D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
    • D01D—MECHANICAL METHODS OR APPARATUS IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS
    • D01D5/00—Formation of filaments, threads, or the like
    • D01D5/28—Formation of filaments, threads, or the like while mixing different spinning solutions or melts during the spinning operation; Spinnerette packs therefor
    • D01D5/30—Conjugate filaments; Spinnerette packs therefor
    • D01D5/34—Core-skin structure; Spinnerette packs therefor
    • D—TEXTILES; PAPER
    • D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
    • D01F—CHEMICAL FEATURES IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS; APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OF CARBON FILAMENTS
    • D01F8/00—Conjugated, i.e. bi- or multicomponent, artificial filaments or the like; Manufacture thereof
    • D01F8/04—Conjugated, i.e. bi- or multicomponent, artificial filaments or the like; Manufacture thereof from synthetic polymers
    • D01F8/12—Conjugated, i.e. bi- or multicomponent, artificial filaments or the like; Manufacture thereof from synthetic polymers with at least one polyamide as constituent
    • D—TEXTILES; PAPER
    • D10—INDEXING SCHEME ASSOCIATED WITH SUBLASSES OF SECTION D, RELATING TO TEXTILES
    • D10B—INDEXING SCHEME ASSOCIATED WITH SUBLASSES OF SECTION D, RELATING TO TEXTILES
    • D10B2331/00—Fibres made from polymers obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds, e.g. polycondensation products
    • D10B2331/02—Fibres made from polymers obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds, e.g. polycondensation products polyamides

Definitions

  • This disclosure relates to a polyamide core-sheath composite fiber and a fabric, more specifically, a polyamide core-sheath composite fiber and a fabric excellent in a humidity-absorbing property and an antistatic property.
  • Synthetic fibers made from thermoplastic resins such as polyamides and polyesters are widely used in clothing applications, industrial applications and the like because they are excellent in strength, chemical resistance, heat resistance and the like.
  • polyamide fibers are excellent in characteristics such as distinctive softness, high tensile strength, the coloring property at dyeing, and high heat resistance and are widely used in general clothing applications such as underwear, outerwear, and sportswear.
  • polyamide fibers excellent in an antistatic property have been proposed such as a method of applying an antistatic agent to a fiber or fabric by post-processing, a method of forming a composite fiber with a polymer having an antistatic property and the like.
  • core-sheath composite polyamide fibers using a humidity-absorbing component in a core have an excellent antistatic property and remove the drawback of polyamide fibers of having remarkable electrical resistance and being easily charged with static electricity.
  • the core-sheath composite polyamide fibers are highly desired for applications such as outerwear used under low temperature and low humidity in winter, and research and proposals have been advanced.
  • Japanese Patent Laid-open Publication No. H6-136618 discloses a core-sheath composite fiber including a polyamide resin as a sheath and a polyether ester amide copolymer as a core and having a single yarn fineness of 3.5 dtex.
  • International Publication No. 2014-10709 discloses a composite fiber including a polyamide resin as a sheath and a polyether ester amide copolymer as a core and having an area ratio between the core and the sheath of 3/1 to 1/5 and a single yarn fineness of 3.25 dtex.
  • Japanese Patent Laid-open Publication No. 2017-57513 discloses that a composite fiber including a polyamide as a core and a polyether ester amide copolymer as a core is excellent in an antistatic property.
  • the core-sheath composite fibers disclosed in JP '618 and WO '709 are excellent in moisture-absorbing capability and antistatic capability, but the raw yarn strength decreases as the fibers become finer in terms of the fineness and single yarn fineness.
  • the core-sheath composite yarn disclosed in JP '513 is excellent in antistatic capability but has a low core ratio of a polyether ester amide copolymer that ensures moisture-absorbing capability.
  • the core ratio is increased to ensure the moisture-absorbing capability, the raw yarn strength is reduced, much raw yarn fluff is generated, and high-order passability and product quality are deteriorated as in JP '618 and WO '709.
  • FIG. 1 schematically shows the shapes of transverse cross-sections of our fiber.
  • FIG. 2 is a longitudinal sectional view of an example of a discharge hole of a spinneret for composite spinning.
  • FIG. 3 schematically shows a part of the arrangement of a core component introduction hole and a sheath component introduction holes of a lower introduction plate of the spinneret for composite spinning.
  • FIG. 4 shows an example of a production device employing a direct spinning-drawing method preferably used in a method of producing our polyamide core-sheath composite fiber.
  • Our polyamide core-sheath composite fiber is a core-sheath composite fiber using a polyamide for the sheath and a polyether ester amide copolymer for the core.
  • the polyamide core-sheath composite fiber has a cross-sectional uniformity ratio (d/R) of 0.072 or less in a transverse cross-section.
  • the cross-sectional uniformity ratio is a value calculated by measuring the distance (d) between the center point (point C) of the inscribed circle of the core component and the center point (point S) of the inscribed circle of the sheath component, and the diameter (R) of the inscribed circle of the sheath component, and is an average value obtained by measuring the entire yarn. The closer the numerical value is to 0, the more concentric it is, and the larger the numerical value is, the more eccentric it is.
  • the cross-sectional uniformity ratio (d/R) By setting the cross-sectional uniformity ratio (d/R) within such a range, generation of single yarn fluff is suppressed, and high-order passability is excellent.
  • the ratio is more preferably 0.050 or less.
  • the cross-sectional uniformity ratio (d/R) exceeds 0.072, the core polyether ester amide copolymer is eccentric, and the sheath thickness of the sheath polyamide is uneven. Therefore, when an external force is applied to a thin portion of the sheath, the single yarn is easily broken from the thin portion, and much single yarn fluff is generated so that not only high-order passability is deteriorated but also product quality tends to deteriorate.
  • the polyamide core-sheath composite fiber has a strength of 3.6 cN/dtex or more. Within such a range, yarn breakage in the high-order processing steps is reduced, and the high-order passability is improved. In addition, product durability is excellent. If the strength is less than 3.6 cN/dtex, yarn breakage in high-order processing steps tends to increase, leading to deterioration of high-order passability. In addition, in clothing applications mainly including outerwear clothing applications and sportswear clothing applications, product durability may be deteriorated due to a tendency that the product becomes undurable for actual use.
  • the range is more preferably 4.0 cN/dtex or more.
  • the polyamide core-sheath composite fiber preferably has an area ratio of the core in a transverse cross-section of the fiber of 20% or more and 40% or less.
  • the ratio is more preferably 20% or more and 30% or less, still more preferably 25% or more and 30% or less.
  • the sheath easily absorbs more moisture present in the air in a limited amount, and the ratio of transmission of the absorbed moisture to the core increases.
  • the area ratio of the core is small, the charged static electricity is quickly transmitted through the core that has absorbed moisture so that an excellent humidity-absorbing property and antistatic property are exhibited.
  • the polyamide core-sheath composite fiber has an electrical specific resistance of 10 7 to 10 10 ⁇ cm under conditions of a temperature of 20° C. and a humidity of 40% RH. With such a range, an antistatic property is provided.
  • a general polyamide fiber has an electrical specific resistance of the order of 10 14 ⁇ cm. Then, static electricity depends on the amount of moisture in the air, and static electricity is less likely to be generated in a humid environment and is likely to be generated in a dry environment. To exhibit a sufficient antistatic property, sufficient antistatic capability can be exhibited when the specific resistance is 10 10 ⁇ cm or less under the conditions of a temperature of 20° C. and a humidity of 40% RH.
  • the lower limit of the electrical specific resistance that can be achieved is of the order of about 10 7 ⁇ cm.
  • ⁇ MR is preferably 5.0% or more. With such a range, a humidity-absorbing property is provided. To provide high wearing comfort, a function of adjusting the humidity inside the clothes is required. As an indicator of this humidity adjustment, ⁇ MR is used.
  • the ⁇ MR is represented by the difference in moisture absorptivity between that at the temperature and humidity inside the clothes typified by 30° C. ⁇ 90% RH in work on light to medium duty or light to medium exercise, and that at the outside temperature and humidity typified by 20° C. ⁇ 65% RH.
  • a ⁇ MR of 5.0% or more makes it possible to suppress stuffy and sticky feeling during wearing and to provide clothing excellent in comfort.
  • the upper limit value of the ⁇ MR is about 17.0%.
  • the polyamide core-sheath composite fiber can be arbitrarily set as long as it has a total fineness suitable for clothing, preferably 8 to 155 dtex.
  • the single yarn fineness can also be arbitrarily set according to product requirements but is preferably 0.8 to 2.0 dtex because fibers are becoming finer in terms of the fineness and the single yarn fineness with the demand for thin and lightweight, soft, and low-air-permeability woven fabrics.
  • the polyamide core-sheath composite fiber preferably has an elongation of 40% or more.
  • the elongation is more preferably 42 to 65%. Within such a range, yarn breakage in the high-order processing steps is reduced, and the high-order passability is improved.
  • the polyamide core-sheath composite fiber employs a polyamide for the sheath and a polyether ester amide copolymer for the core.
  • the polyether ester amide copolymer used for the core is a block copolymer having an ether bond, an ester bond, and an amide bond in one molecular chain. More specifically, the polyether ester amide copolymer is a block copolymer obtained by the polycondensation reaction of at least one polyamide component (A) selected from lactams, aminocarboxylic acids, and salts of diamines and dicarboxylic acids, with a polyether ester component (B) formed of a dicarboxylic acid and a poly(alkylene oxide) glycol.
  • A polyamide component selected from lactams, aminocarboxylic acids, and salts of diamines and dicarboxylic acids
  • polyamide component (A) examples include lactams such as ⁇ -caprolactam, dodecanolactam, and undecanolactam, ⁇ -aminocarboxylic acids such as aminocaproic acid, 11-aminoundecanoic acid, and 12-aminododecanoic acid, and nylon salts of diamines and dicarboxylic acids, which are precursors of nylon 66, nylon 610, nylon 612, and the like.
  • a preferable polyamide-forming component is ⁇ -caprolactam.
  • the polyether ester component (B) is formed of a dicarboxylic acid having 4 to 20 carbon atoms and a poly(alkylene oxide) glycol.
  • the dicarboxylic acid having 4 to 20 carbon atoms include aliphatic dicarboxylic acids such as succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, sebacic acid, and dodecadi acid, aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, and 2,6-naphthalenedicarboxylic acid, and alicyclic dicarboxylic acids such as 1,4-cyclohexanedicarboxylic acid.
  • Preferable dicarboxylic acids are adipic acid, sebacic acid, dodecadi acid, terephthalic acid, and isophthalic acid.
  • Preferable dicarboxylic acids are adipic acid, sebacic acid, dodecadi acid, terephthalic acid, and isophthalic acid.
  • Examples of the poly(alkylene oxide) glycol include polyethylene glycol, poly(1,2- and 1,3-propylene oxide) glycol, poly(tetramethylene oxide) glycol, and poly(hexamethylene oxide) glycol. Polyethylene glycol having particularly high moisture-absorbing capability is preferable.
  • the number average molecular weight of the poly(alkylene oxide) glycol is preferably 300 to 5,000, more preferably 500 to 4,000.
  • a molecular weight of 300 or more is preferable because the poly(alkylene oxide) glycol hardly scatters to the outside of the system during the polycondensation reaction, and a fiber having stable humidity-absorbing and antistatic properties is obtained.
  • a molecular weight of 5,000 or less is preferable because the poly(alkylene oxide) glycol is uniformly dispersed in the polymer, and good humidity-absorbing and antistatic properties can be obtained.
  • the constituent ratio of the polyether ester component (B) in the entire polyether ester amide copolymer is preferably 20 to 80% in terms of molar ratio.
  • a constituent ratio of 20% or more is preferable because high humidity-absorbing and antistatic properties can be obtained.
  • a constituent ratio of 80% or less is preferable because high color fastness and washing durability of humidity-absorbing and antistatic properties can be obtained.
  • the constituent ratio between the polyamide and the poly(alkylene oxide) glycol is preferably 20%/80% to 80%/20% in terms of molar ratio.
  • a constituent ratio of the poly(alkylene oxide) glycol of 20% or more is preferable because good humidity-absorbing and antistatic properties can be obtained.
  • a constituent ratio of the poly(alkylene oxide) glycol of 80% or less is preferable because high color fastness and washing durability of humidity-absorbing and antistatic properties can be obtained.
  • the chips of the polyether ester amide copolymer used for the core preferably has an ortho-chlorophenol relative viscosity of 1.2 or more and 2.0 or less.
  • the ortho-chlorophenol relative viscosity is 1.2 or more, the desired stress is applied to the sheath during spinning, crystallization of the polyamide in the sheath proceeds, and the strength is increased.
  • the poly(alkylene oxide) glycol As for the poly(alkylene oxide) glycol, a chain reaction in which radicals are generated from the inside of the molecule by heat application and attack adjacent atoms to generate radicals proceeds, and a high temperature exceeding 200° C. is caused by heat of reaction.
  • the molecular weight of the poly(alkylene oxide) glycol is smaller, heat is easily applied to the molecular chain so that radicals tend to be generated more easily, and heat of reaction tends to be generated more easily.
  • the number average molecular weight of the poly(alkylene oxide) glycol contained in the polyether ester amide copolymer is as relatively small as 300 to 5,000, from the above mechanism, thermal degradation of the polyether ester amide copolymer is likely to proceed, and hardening or embrittlement of a raw yarn, deterioration of the humidity-absorbing property and the antistatic property and the like are very likely to occur.
  • a hindered phenolic antioxidant that supplements radicals to the polyether ester amide copolymer in the core.
  • a half-hindered phenolic antioxidant is more preferable.
  • the amount of the hindered phenolic antioxidant to be added is preferably 1.0 wt % or more and 5.0 wt % or less with respect to the weight of the polyether ester amide copolymer in the core. The amount is more preferably 2.0 wt % or more.
  • Examples of a both-hindered phenolic antioxidant include pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] (IR 1010), tris(4-tert-butyl-3-hydroxy-2,6-di-methylbenzyl)isocyanuric acid (IR 1790), (1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxy-phenyl)benzene (A0-330), 1,3,5-tris[[3,5-bis(1,1-dimethylethyl)-4-hydroxyphenyl]methyl]-1,3,5-triazine-2,4,6(1H,3H, 5H)-trione (IR 3114), and N,N′-hexamethylenebis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propanamide] (IR 1098).
  • thermal degradation of the polyether ester amide copolymer proceeds due to thermal hysteresis during a spinning step (a high temperature applied during polymer melting or heat setting after drawing) and thermal hysteresis during a high-order processing step (dyeing or heat setting of the fabric or the like), and the amount of active ingredient of the antioxidants that supplement radicals remaining at the stage of the fabric and the article of clothing is significantly reduced.
  • HALS hindered amine light stabilizer
  • HALS examples include a polycondensate of dibutylamine-1,3,5-triazine N,N-bis(2,2,6,6-tetramethyl-4-piperidyl-1,6-hexamethylenediamine N-(2,2,6,6-tetramethyl-4-piperid-yl)butylamine (CHIMASSORB 2020 FDL), 4,7,N,N′-tetrakis[4,6-bis[butyl(1,2,2,6,6-pentameth-yl-4-piperidinyl)amino]-1,3,5-triazin-2-yl]-4,7-diazadecane-1,10-diamine (CHIMAS SORB 119), poly[ ⁇ 6-(1,1,3.3-tetramethylbutyl)amino-1,3,5-triazine-2,4-diyl)((2,2,6,6-tetramethyl-4-piperid-yl)imino)hexamethylene((2,2,6,6-te
  • the half-hindered phenolic antioxidant As for the half-hindered phenolic antioxidant, the decrease in the amount of the active ingredient of the antioxidant in the thermal hysteresis during the spinning step and the thermal hysteresis during the high-order processing step is very small compared to the both-hindered phenolic antioxidant. Therefore, the heat of reaction/thermal degradation can be suppressed by using the half-hindered phenolic antioxidant alone without using the HALS in combination unlike the both-hindered phenolic antioxidant, and hardening or embrittlement of the raw yarn and deterioration of humidity-absorbing and antistatic properties can be suppressed. In addition, since the decomposition product of the half-hindered phenol is less colored, yellowing can also be suppressed.
  • phosphorus stabilizers in combination with the polyether ester amide copolymer in the core.
  • Various other additives such as a matting agent, a flame retardant, an ultraviolet absorber, an infrared absorber, a crystal nucleating agent, a fluorescent whitening agent, an antistatic agent, a hygroscopic polymer, and carbon may be contained in the form of a copolymer or a mixture as needed at a total additive content of 5 wt % or less with respect to the polyether ester amide copolymer.
  • the ratio of the core is preferably 20 wt % to 40 wt % with respect to the entire composite fiber.
  • the ratio is more preferably 20 wt % to 30 wt %, more preferably 25 wt % to 30 wt %.
  • the ratio of the core increases, the humidity-absorbing and antistatic properties are improved, but the strength decreases.
  • the humidity-absorbing and antistatic properties are deteriorated. Within such a range, the humidity-absorbing property and the antistatic property are exhibited, and it becomes possible to appropriately draw the polyamide in the sheath so that the strength is enhanced.
  • polyamide used in the sheath examples include nylon 6, nylon 66, nylon 46, nylon 9, nylon 610, nylon 11, nylon 12, and nylon 612, or copolymerized polyamides containing these nylons and a copolymerization component such as a compound having an amide-forming functional group such as laurolactam, sebacic acid, terephthalic acid, isophthalic acid, and sodium 5-sulfoisophthalate.
  • nylon 6, nylon 11, nylon 12, nylon 610, and nylon 612 have a small difference in melting point from the polyether ester amide copolymer and can suppress thermal degradation of the polyether ester amide copolymer during melt spinning, which is preferable from the viewpoint of the yarn-making property.
  • Nylon 6 having excellent dyeability is particularly preferable.
  • the polyamide in the sheath may contain various other additives such as a matting agent, a flame retardant, an antioxidant, an ultraviolet absorber, an infrared absorber, a crystal nucleating agent, a fluorescent whitening agent, an antistatic agent, a hygroscopic polymer, and carbon in the form of a copolymer or a mixture as needed at a total additive content of 5 wt % or less with respect to the polyether ester amide copolymer.
  • additives such as a matting agent, a flame retardant, an antioxidant, an ultraviolet absorber, an infrared absorber, a crystal nucleating agent, a fluorescent whitening agent, an antistatic agent, a hygroscopic polymer, and carbon in the form of a copolymer or a mixture as needed at a total additive content of 5 wt % or less with respect to the polyether ester amide copolymer.
  • the polyamide chips used in the sheath preferably has a sulfuric acid relative viscosity of 2.3 or more and 3.3 or less. Within such a range, it becomes possible to appropriately draw the polyamide in the sheath so that the strength is enhanced.
  • the polyether ester amide copolymer has a melt viscosity of 400 to 600 poise, which is lower than the melt viscosity of 900 to 1,500 poise of the polyamide, and has a large difference in melt viscosity. Therefore, it is preferable to select a combination of a polyether ester amide copolymer and a polyamide having a melt viscosity ratio at a spinning temperature of 3.0 or less. Within such a range, the stress applied in the longitudinal direction of the yarn at the time of thinning and drawing after the yarn is discharged from the spinneret at the time of spinning is not biased to the sheath component, and there is a tendency that the cross-sectional uniformity ratio (d/R) can be reduced.
  • d/R cross-sectional uniformity ratio
  • melt viscosity refers to a melt viscosity that can be measured with a capillary rheometer using a chip-shaped polymer caused to have a moisture content of 200 ppm or less by a vacuum dryer, and means a melt viscosity at the same shear rate at a spinning temperature.
  • the melting point of the polyether ester amide copolymer is lower than the melting point of the polyamide, it is preferable to select a polyether ester amide copolymer and a polyamide having a melting point difference of 30° C. or less from the viewpoint of suppressing thermal degradation of the polyether ester amide copolymer during melt spinning and yarn-making properties.
  • the temperature of the melted portion of the core polymer is preferably 235° C. or higher and 260° C. or lower.
  • the polyether ester amide copolymer in the core has a melt viscosity suitable for melt spinning, which is preferable.
  • the temperature of the melted portion is 260° C. or lower, thermal decomposition of the polyther ester amide copolymer in the core due to temperature rise can be suppressed, which is preferable.
  • the temperature of the melted portion of the sheath polymer is preferably 240° C. or higher and 285° C. or lower.
  • the temperature of the melted portion of the sheath polymer is 240° C. or higher, the polyamide in the sheath has a melt viscosity suitable for melt spinning, which is preferable.
  • the temperature is 285° C. or lower, thermal decomposition of the polyther ester amide copolymer in the core due to temperature rise can be suppressed, which is preferable.
  • the temperature of the melted portion of the joining portion is preferably 235° C. or higher and 270° C. or lower.
  • the temperature is 235° C. or higher, the polyamide and the polyether ester amide copolymer have melt viscosities suitable for melt spinning, which is preferable.
  • the temperature is 270° C. or lower, decomposition by thermal decomposition of the polyther ester amide copolymer can be suppressed, which is preferable.
  • FIG. 2 is a longitudinal sectional view of an example of a discharge hole of a spinneret for composite spinning used for the core-sheath composite fiber.
  • members are laminated in the order of an upper introduction plate 1, a lower introduction plate 2, and a spinneret plate 3 from the top to form a composite spinneret.
  • a description will be given along a flow of the polymer from upstream to downstream of the composite spinneret.
  • the core component polymer flows into a core component introduction hole 1-1 of the upper introduction plate, is metered by a core component narrowing part 1-2 drilled at the lower end, and is then discharged into a core component introduction hole 2-1 of the lower introduction plate.
  • the core component polymer that has flowed into the core component introduction hole 2-1 of the lower introduction plate is metered by a core component narrowing part 2-2 drilled at the lower end and then flows into a joining pool 3-1 of the spinneret plate 3.
  • the sheath component polymer flows into a sheath component introduction hole 1-3 of the upper introduction plate and is discharged into a sheath component pool 2-3 of the lower introduction plate.
  • a sheath component introduction hole 2-4 for allowing the polymer to flow downstream is drilled.
  • the sheath component polymer that has flowed into the sheath component pool 2-3 is metered by a sheath component narrowing part 2-5 drilled at the lower end and then flows into the joining pool 3-1 of the spinneret plate 3.
  • the core polymer and the sheath polymer each flow into the joining pool 3-1 of the spinneret plate 3, flow into a discharge hole 3-3 in a core-sheath composite form, are metered by a discharge hole narrowing part 3-2 drilled at the lower end, and are then discharged.
  • the core component polymer has a low viscosity, by metering the polymer amount twice, the polymer flow can be controlled, and the core component can be located at the true center.
  • the upper introduction plate 1 it is also intended to increase the pressure of the core component polymer, improve the sealing property between the upper introduction plate 1 and the lower introduction plate 2, and prevent polymer leakage.
  • L/D is more preferably 1.5 to 2.5.
  • the lower introduction plate 2 it is necessary to drill the core component introduction hole 2-1 and three sheath component introduction holes 2-4 around the core component introduction hole 2-1.
  • the number of drilled holes By setting the number of drilled holes to three, it becomes possible to uniformly fill the joining pool 3-1 of the spinneret plate 3 with the sheath polymer, and the cross-sectional uniformity ratio can be set to such a range.
  • the number of drilled holes is two or less, the filling of the joining pool 3-1 with the polymer tends to be biased, and the cross-sectional uniformity ratio (d/R) may exceed 7.2.
  • the hole diameter (D) is small or the hole length (L) to be large to maintain the metering property, clogging and leakage are likely to occur, the yarn-making stability is likely to decrease, and the cross section tends to be poor.
  • the discharge rate per hole of the three drilled sheath component introduction holes 2-4 is set to be the same to further reduce the cross-sectional uniformity ratio (d/R), and for this reason, it is preferable that the holes are drilled at point-symmetric points, that is, on the same orbit.
  • FIG. 4 shows an example of a production device employing a direct spinning-drawing method preferably used in a method of producing the polyamide core-sheath composite fiber.
  • the polyamide (sheath) and the polyether ester amide copolymer (core) are separately melted, metered and transported by a gear pump, and discharged from a composite spinneret 4 to form each filament.
  • Each filament discharged from the composite spinneret 4 in this manner is cooled and solidified to room temperature by blowing cooling air to the filament with a yarn cooling device 5 such as a chimney.
  • an oil is applied with an oiling device 6, and the filaments are converged to form multifilaments, the multifilaments are entangled with a fluid entangling nozzle device 7 and pass through a take-up roller 8 and a drawing roller 9, and at that time, the multifilaments are drawn according to the ratio of the circumferential velocities of the take-up roller 8 and the drawing roller 9. Furthermore, the yarn is heat-treated by heating the drawing roller 9 and wound with a winding device.
  • the production of the polyamide core-sheath composite fiber can be achieved by any method using a cooling device that blows cooling/rectifying air from a certain direction, an annular cooling device that blows cooling/rectifying air from the outer peripheral side toward the central side, or an annular cooling device that blows cooling/rectifying air from the central side toward the outer periphery as the cooling device 5.
  • a vertical distance Ls (hereinafter referred to as a cooling start distance) from the lower surface of the spinneret to the upper end of the cooling air blowing part of the cooling device 5 is preferably 159 to 219 mm from the viewpoint of suppressing yarn swinging and fiber unevenness, more preferably 169 to 189 mm.
  • the cooling air velocity blown out from the cooling air blowing surface is preferably 20.0 to 40.0 (m/min) on average in the section from the upper end surface to the lower end surface of the cooling air blowing part from the viewpoint of fineness unevenness and strength.
  • the polymer discharged from the spinneret is blown with cooling air from the cooling device to be solidified into yarns, and the yarns are drawn in the section from the solidification position to the oiling position by spinning tension with accompanying flow and then mechanically drawn between the take-up roller and the drawing roller.
  • the core-sheath composite fiber it is important to perform mechanical drawing to promote the orientation crystallization of the sheath polymer to increase the strength, and decrease the spinning tension to suppress the orientation crystallization of the core polymer to improve the moisture-absorbing capability.
  • the position of the oiling device 6, that is, a vertical distance Lg (hereinafter referred to as an oiling position Lg) from the lower surface of the spinneret to the oiling nozzle position of the oiling device 6 in FIG. 4 is preferably 800 to 1,500 mm, more preferably 1,000 to 1,300 mm, although it depends on the single yarn fineness and the cooling efficiency of the filament from the cooling device.
  • the oiling position is less than 800 mm, the filament is not sufficiently cooled and damaged due to contact with an oiling guide while having an unstable structure so that not only the single yarn strength of the filament decreases, but also fluff tends to increase.
  • the sheath thickness is thinner, which means a smaller single yarn fineness, a higher core ratio, a higher cross-sectional uniformity ratio and the like, damage is more likely to occur, and the above phenomenon may be remarkably produced.
  • the oiling position is more than 1500 mm, not only the orientation crystallization of the core polymer proceeds due to the high spinning tension to decrease the moisture-absorbing capability, but also the mechanical draw ratio is reduced, which may cause decrease in the strength and generation of fluff.
  • the spinning conditions are preferably set so that the product of the velocity (spinning velocity) of the yarn taken up by the take-up roller and the draw ratio, which is the value of the circumferential velocity ratio between the take-up roller and the drawing roller, is 3,300 or more and 4,500 or less.
  • the product is more preferably 4,000 or less.
  • This numerical value represents the total amount of drawing of the polymer discharged from the spinneret from the spinneret discharge linear velocity to the circumferential velocity of the take-up roller, and further from the circumferential velocity of the take-up roller to the circumferential velocity of the drawing roller. Setting the value within this range makes it possible to appropriately draw the polyamide in the sheath.
  • the desired stress is applied to the polyamide in the sheath during spinning, and appropriate drawing can be applied so that crystallization of the polyamide in the sheath proceeds, and the strength can be controlled within the above range.
  • the flow balance (melt viscosity ratio) of a polyamide having a melt viscosity of 900 to 1,500 poise and a polyether ester amide copolymer having a melt viscosity of 400 to 600 poise, discharge stability can be secured, and the cross-sectional uniformity ratio can be controlled within the above range.
  • a core-sheath composite fiber excellent in the humidity-absorbing property and the antistatic property having a strength of 3.6 cN/dtex or more and a cross-sectional uniformity ratio d/R of the core and sheath components of the entire filament of 0.072 or less can be obtained.
  • this effect is remarkably exhibited when the sheath thickness is relatively small, the single yarn fineness is 2.0 dtex or less, and the area ratio of the core is 20% or more.
  • the core-sheath composite fiber is excellent in the humidity-absorbing property and the antistatic property and thus can be preferably used for clothing.
  • the fabric form can be selected according to a purpose such as a woven fabric and a knitted fabric.
  • the clothing items may be various clothing products such as underwear and sportswear.
  • T1 a flow time at 25° C. was measured using an Ostwald viscometer.
  • T2 a flow time of 98 wt % sulfuric acid was measured.
  • the ratio of T1 to T2, that is, T1/T2 was defined as the sulfuric acid relative viscosity.
  • the flow time (T1) at 25° C. was measured using an Ostwald viscometer. Then, the flow time (T2) of ortho-chlorophenol was measured.
  • the ratio of T1 to T2, that is, T1/T2 was defined as the sulfuric acid relative viscosity.
  • a chip sample was caused to have a moisture content of 200 ppm or less with a vacuum dryer, and the melt viscosity was measured with Capilograph 1B manufactured by Toyo Seiki Seisaku-sho, Ltd. while changing the strain rate stepwise.
  • the measurement temperature was set to a spinning temperature, and the measurement was performed in a nitrogen atmosphere with the period of time from when the sample was put into a heating furnace to the start of the measurement being set to 5 minutes.
  • a fiber sample was set on a sizing reel having a perimeter of 1.125 m and rotated 200 times to make a looped skein.
  • the skein was dried (105 ⁇ 2° C. ⁇ 60 minutes) with a hot air dryer, and the skein mass was measured with a balance. The fineness was calculated from the value obtained by multiplying the skein mass by the official regain. The official regain of the core-sheath composite fiber was set to 4.5%.
  • a fiber sample was measured with “TENSILON” (registered trademark) UCT-100 manufactured by Orientec Co., Ltd. under the constant rate extension conditions shown in JIS L 1013 (Testing methods for man-made filament yarns, 2010).
  • the elongation was calculated from the elongation at the point showing maximum strength in the tensile strength-elongation curve.
  • the value obtained by dividing the maximum strength by the fineness was defined as strength.
  • the measurement was performed 10 times, and the average values therefor were defined as the strength and the elongation.
  • An embedding agent composed of paraffin, stearic acid, and ethyl cellulose was dissolved, fibers were introduced and then solidified by being left standing at room temperature, and a raw yarn in the embedding agent was cut in a transverse cross-sectional direction.
  • the transverse cross section of the fiber was photographed with a CCD camera (CS 5270) manufactured by Tokyo Electronics Co., Ltd., and the image was printed out at a magnification of 1,500 times with a color video processor (SCT-CP 710) manufactured by Mitsubishi Electric Corporation.
  • the distance (d) between the center point (point C) of the inscribed circle of the core component and the center point (point S) of the inscribed circle of the sheath component and the diameter (R) of the inscribed circle of the sheath component are measured, and calculation is performed.
  • the cross sections of all the filaments of the core-sheath composite yarn were each measured, and the average value therefor was taken as the cross-sectional uniformity ratio.
  • A A uniform cross section without variations in circular shape and size of the sheath component and the core component is observed.
  • a fiber sample was rewound at a velocity of 500 m/min, a laser-type fluff detector was installed at a position 2 mm away from the yarn during rewinding, and the total number of detected defects was converted into the number per 100,000 m and displayed. A value of 2 pieces/100,000 m or less was regarded as acceptable.
  • a fiber sample is sufficiently scoured in a 0.2-wt % weak alkaline aqueous solution of an anionic surfactant to remove oil and the like and then sufficiently rinsed and dried.
  • the sample is aligned to form a fiber bundle having a length (L) of 5 cm and a total fineness (D) of 2,200 dtex (2,000 denier), subjected to humidity conditioning by being left standing for 2 days under the conditions of a temperature of 20° C. and a humidity of 40% RH, and then measured for the resistance of the sample at an applied voltage of 500 V with a vibrating reed minute-potential electrometer, and calculation is performed by the following formula:
  • ⁇ Volume resistivity ( ⁇ cm), R: resistance ( ⁇ ), D: fineness (dtex), L: sample length (cm), d: sample density (g/m 2 ).
  • MR 65 [( W 65 ⁇ W 0)/ W 0] ⁇ 100% (1)
  • polyether ester amide copolymer As the polyether ester amide copolymer, polyether ester amide copolymer (MH 1657 manufactured by ARKEMA K.K., ortho-chlorophenol relative viscosity: 1.69, melting point: 200° C., melt viscosity: 450 poise (260° C.)) chips containing nylon 6 as the polyamide component and polyethylene glycol having a molecular weight of 1,500 as the polyether component and having a molar ratio between nylon 6 and polyethylene glycol of 24%:76% was used for the core.
  • MH 1657 manufactured by ARKEMA K.K., ortho-chlorophenol relative viscosity: 1.69, melting point: 200° C., melt viscosity: 450 poise (260° C.)
  • nylon 6 chips that did not contain titanium oxide and had a sulfuric acid relative viscosity of 2.73, a melting point of 215° C., and a melt viscosity of 1,250 poise were used for the sheath.
  • the polyether ester amide copolymer as the core and nylon 6 as the sheath were melted at 240° C. as the temperature of the melted portion of the core and 270° C. as the temperature of the melted portion of the sheath and discharged from a concentric core-sheath composite spinneret of a 3-plate structure illustrated in FIGS.
  • the yarn is passed through a yarn cooling device with a cooling start distance Ls of 100 mm with cold air having an air temperature of 18° C. and an air velocity of 30 m/min to cool and solidify the yarn to room temperature.
  • a non-hydrous oil was applied at an oiling position Lg from the spinneret surface of 1,300 mm, and the filaments were bundled to form multifilaments.
  • entanglement was applied with a first fluid entangling nozzle device.
  • the multifilaments were drawn at a circumferential velocity of a take-up roller as a first roll of 3,255 m/min and a circumferential velocity of a drawing roller as a second roll of 4,167 m/min, heat-set at a draw ratio of 1.28 times with the drawing roller at 150° C., and wound at a relaxation rate of 4.0% and a winding velocity of 4,000 m/min to provide two core-sheath composite yarns of 22 dtex and 12 filaments.
  • the physical properties of the raw yarns are as shown in Table 1.
  • the core-sheath composite fibers were used as a warp and a weft, and a plain weave structure was woven at a warp density of 188 yarns/2.54 cm and a weft density of 155 yarns/2.54 cm.
  • the obtained gray fabric was scoured with an open soaper in a solution containing 2 g of caustic soda (NaOH) per liter by a conventional method, dried at 120° C. with a cylinder dryer, then pre-set at 170° C., subjected to a dyeing treatment at 98° C. for 60 minutes using an acidic dye (Nylosan Blue-GFL 167% (manufactured by Sandoz Ltd.) 1.0% owf and a fixing treatment at 80° C. for 20 minutes using 3 g/l of synthetic tannin (NYLONFIX 501 manufactured by Senka Corporation) with a jet dyeing machine, then dried (120° C.), and finish-set (175° C.).
  • an acidic dye Neylosan Blue-GFL 167% (manufactured by Sandoz Ltd.) 1.0% owf
  • a fixing treatment at 80° C. for 20 minutes using 3 g/l of synthetic tannin (NYLONFIX 501 manufactured by Senka Corporation) with a
  • Core-sheath composite yarns were provided by spinning in the same manner as in Example 1 except that a spinneret having L/D changed as shown in Table 1 in the sheath component narrowing part 2-5 of the lower introduction plate 2 for metering the sheath component was used, and woven fabrics were produced. The results are shown in Table 1.
  • Core-sheath composite yarns were provided by spinning in the same manner as in Example 1 except that a spinneret having the core component introduction hole 2-1 and the number of drilled sheath component introduction holes 2-4 around the core component introduction hole 2-1 changed as shown in Table 1 in the lower introduction plate 2 was used, and woven fabrics were produced. The results are shown in Table 1.
  • Core-sheath composite yarns were provided by spinning in the same manner as in Example 1 except that a spinneret (not shown) employing a two-plate structure, a number of times of core metering of one, a number of drilled holes of three, and L/D of the sheath component narrowing part for metering the sheath component changed as shown in Table 1 was used, and a woven fabric was produced. The results are shown in Table 1.
  • Example 3 Example 1 Core Polymer Polyether Polyether Polyether Polyether component ester amide ester amide ester amide ester amide copolymer copolymer copolymer copolymer OCP relative viscosity 1.69 1.69 1.69 1.69 Sheath Polymer Nylon 6 Nylon 6 Nylon 6 Nylon 6 Nylon 6 component Sulfuric acid relative 2.73 2.73 2.73 2.73 viscosity Spinneret Drawing FIGS. 2 FIGS. 2 FIGS. 2 FIGS. 2 FIGS.
  • FIG. 2 Not and 3 shown Configuration Three-plate Three-plate Three-plate Three-plate Two-plate structure, structure, structure, structure, core core core core metered metered metered metered twice twice twice once Sheath component 3 2 4 3 introduction hole: number of drilled holes Sheath component 3.0 1.5 1.5 1.5 narrowing part: L/D Yarn Spinning velocity 3255 3255 3255 making (m/min) conditions Draw ratio 1.28 1.28 1.28 1.28 Product 4166 4166 4166 4166 4166 Oiling position (mm) 1300 1300 1300 1300 Yarn Fineness (dtex) 22 22 22 22 characteristics Number of filaments 12 12 12 12 12 Single yarn fineness 1.8 1.8 1.8 1.8 Core ratio (%) 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 Cross
  • Comparative Example 1 in which L/D of the sheath component narrowing part of the lower introduction plate for measuring the sheath component was small, Comparative Example 3 in which the number of drilled holes was small, and Comparative Example 5 in which the core metering was performed once, the metering property of the polyether ester amide copolymer polymer was poor, the cross-sectional uniformity ratio was high, which indicated that bias was observed, and fluff and high-order passability were poor.
  • Comparative Example 2 having a large L/D and Comparative Example 4 having a large number of drilled holes the cross-section was not uniform, and the yarn-making stability was poor.
  • Core-sheath composite yarns were provided by spinning in the same manner as in Example 1 except that the oiling position Lg was changed as shown in Table 2 and the spinning velocity and the draw ratio were adjusted as shown in Table 2, and woven fabrics were produced. The results are shown in Table 2.
  • Core-sheath composite yarns were provided by spinning in the same manner as in Example 1 except that the core ratio (wt %) was changed as shown in Table 2 and the spinning velocity and the draw ratio were adjusted as shown in Table 2, and woven fabrics were produced. The results are shown in Table 2.
  • Example 6 Example 7 Core Polymer Polyether Polyether Polyether Polyether component ester amide ester amide ester amide ester amide copolymer copolymer copolymer copolymer copolymer OCP relative viscosity 1.69 1.69 1.69 1.69 Sheath Polymer Nylon 6 Nylon 6 Nylon 6 Nylon 6 component Sulfuric acid relative 2.73 2.73 2.73 2.73 viscosity Spinneret Drawing FIGS. 2 FIGS. 2 FIGS. 2 FIGS. 2 FIGS.
  • FIGS. 2 FIGS. 2 and 3 and 3 and 3 and 3 Configuration Three-plate Three-plate Three-plate structure, structure, structure, core core core metered metered metered twice twice twice Sheath component 3 3 3 introduction hole: number of drilled holes Sheath component 1.5 1.5 1.5 narrowing part: L/D Yarn Spinning velocity 2750 3000 3700 making (m/min) conditions Draw ratio 1.5 1.4 1.15 Product 4125 4200 4255 Oiling position (mm) 1300 1300 1300 Yarn Fineness (dtex) 22 22 22 characteristics Number of filaments 12 12 12 Single yarn fineness 1.8 1.8 1.8 Core ratio (%) 20 25 40 Cross-sectional A A A uniformity Cross-sectional 0.045 0.045 0.055 uniformity ratio d/R Strength (cN/dtex) 4.9 4.5 3.7 Elongation (%) 44 44 44 ⁇ MR (%) 6.7 8.3 13.3 Specific resistance 9.8 9.3 8.3 (log ⁇ ⁇ cm) Amount of fluff 1.0 1.0 1.5 (pieces/100,000 m
  • Example 6 In Comparative Example 6 in which the oiling position Lg was long from the bottom of the spinneret, appropriate drawing could not be applied to the polyamide in the sheath, the strength was reduced, the fluff was increased, and the high-order passability was poor.
  • Comparative Example 7 In which the oiling position Lg was short from the bottom of the spinneret, the filament was not sufficiently cooled and was damaged due to contact with the oiling guide while having an unstable structure so that the strength slightly decreased, the fluff increased, and the high-order passability was poor.
  • Example 8 having a high core ratio, the sheath was thinner, the strength was slightly lower, and the amount of fluff was slightly greater than in Example 1, but the high-order passability was at an acceptable level.
  • Core-sheath composite yarns were provided by spinning in the same manner as in Example 1 except that the number of discharge holes was changed, the number of filaments was changed as shown in Table 3, and the spinning velocity, the draw ratio, and the oiling position were adjusted as shown in Table 3, and woven fabrics were produced. The results are shown in Table 3.
  • Core-sheath composite yarns were provided by spinning in the same manner as in Example 1 except that nylon 6 chips having a sulfuric acid relative viscosity of 2.63, a melting point of 215° C., and a melt viscosity of 1,000 poise and containing 1.8% of titanium oxide were used as the polyamide in the sheath, and the spinning velocity and the draw ratio were adjusted as shown in Table 3, and a woven fabric was produced. The results are shown in Table 3.
  • Example 10 Example 11 Core Polymer Polyether Polyether Polyether component ester amide ester amide ester amide copolymer copolymer copolymer OCP relative viscosity 1.69 1.69 1.69 Sheath Polymer Nylon 6 Nylon 6 Nylon 6 component Sulfuric acid relative 2.73 2.73 2.63 viscosity Spinneret Drawing FIGS. 2 FIGS. 2 FIGS.

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