Polyamide core-sheath composite fibers and fabrics

Abstract

The present invention provides a polyamide core-sheath composite fiber that has hygroscopicity, antistatic properties, and strength retention, suppresses the generation of fuzz, and has excellent high-order permeability. The polyamide core-sheath composite fiber is a core-sheath type composite fiber in which the sheath polymer is composed of polyamide and the core polymer is composed of a polyetheresteramide copolymer, has a strength of 3.6 cN / dtex or more, a cross-sectional uniformity ratio d / R of the core-sheath component of the entire monofilament of less than 0.072, and a resistivity of 10 7 ~10 10 Ω·cm.

Description

Technical Field

[0001] The present invention relates to a polyamide core-sheath composite fiber and a fabric, and more particularly to a polyamide core-sheath composite fiber and a fabric having excellent hygroscopicity and antistatic properties. Background Art

[0002] Synthetic fibers made from thermoplastic resins such as polyamide and polyester are widely used in clothing and industrial applications due to their excellent strength, chemical resistance, and heat resistance. Polyamide fibers, in particular, are widely used in general clothing applications such as underwear, outerwear, and sportswear due to their unique softness, high tensile strength, excellent color development when dyed, and high heat resistance.

[0003] With the recent rise in outdoor sports, demand for sportswear and leisurewear has been increasing year by year. Fabrics used in down jacket bases and windbreakers, in particular, require thinness, lightness, softness, and low air permeability. Polyamide fibers are trending towards finer deniers, including finer single-filament deniers. Polyamide fibers are prone to static electricity in the low-temperature, low-humidity winter environment. As they become thinner, they are more susceptible to static electricity generation, leading to a demand for polyamide fibers with excellent antistatic properties.

[0004] Many proposals have been made for polyamide fibers, which have excellent antistatic properties, such as adding antistatic agents to fibers and fabrics through post-processing, and forming composite fibers with antistatic polymers. Among these, core-sheath composite polyamide fibers, which use a hygroscopic component in the core, exhibit excellent antistatic properties. This eliminates the drawbacks of polyamide fibers, such as their significant electrical resistance and susceptibility to static electricity, and is in high demand, particularly for outerwear used in winter, where temperatures are low and humidity is low. Research and development efforts are underway.

[0005] For example, Patent Document 1 discloses a core-sheath composite fiber with a polyamide resin sheath and a polyetheresteramide copolymer core, with a single-filament fineness of 3.5 dtex. Patent Document 2 discloses a composite fiber with a polyamide resin sheath and a polyetheresteramide copolymer core, with a core-to-sheath area ratio of 3 / 1 to 1 / 5 and a single-filament fineness of 3.25 dtex. Patent Document 3 discloses a composite fiber with a polyamide core and a polyetheresteramide copolymer core, which exhibits excellent antistatic properties.

[0006] Prior art literature

[0007] Patent Literature

[0008] Patent Document 1: Japanese Patent Application Laid-Open No. 6-136618

[0009] Patent Document 2: International Publication No. 2014 / 10709

[0010] Patent Document 3: Japanese Patent Application Laid-Open No. 2017-57513 Summary of the Invention

[0011] Problems to be solved by the invention

[0012] However, the core-sheath composite fibers disclosed in Patent Documents 1 and 2 have excellent hygroscopic and antistatic properties, but as the fineness and fineness of the single filaments increase, the strength of the raw yarn decreases. If stretching is performed to ensure the strength of the raw yarn, there are problems such as the frequent occurrence of raw yarn fuzz, deterioration of the process passability in higher-order processing steps, and deterioration of the product quality. The core-sheath composite yarn disclosed in Patent Document 3 has excellent antistatic properties, but the core ratio of the polyetheresteramide copolymer that ensures hygroscopic performance is low. If the core ratio is increased to ensure hygroscopic performance, the same problems as in Patent Documents 1 and 2 arise, such as the decrease in raw yarn strength, the frequent occurrence of raw yarn fuzz, deterioration of high-order passability, and deterioration of product quality.

[0013] With the demand for thin, lightweight, soft, and low-permeability fabrics, fibers are trending towards finer deniers, and monofilaments are becoming finer. Therefore, the challenge is to provide polyamide core-sheath composite fibers that have hygroscopicity, antistatic properties, and suppress the formation of fuzz while maintaining strength, and have excellent high-order permeability.

[0014] Means of solving the problem

[0015] In order to solve the above-mentioned problems, the present invention includes the following.

[0016] (1) A polyamide core-sheath composite fiber, which is a core-sheath type composite multifilament in which the sheath polymer is composed of polyamide and the core polymer is composed of a polyetheresteramide copolymer, has a strength of 3.6 cN / dtex or more, a cross-sectional uniformity ratio d / R of the core-sheath component in the fiber cross section of not more than 0.072, and a resistivity of 10 7 ~10 10 Ω·cm.

[0017] d: The distance between the center of the inscribed circle of the core component and the center of the inscribed circle of the sheath component

[0018] R: Diameter of the inscribed circle of the sheath component

[0019] (2) The polyamide core-sheath composite fiber according to (1), wherein the single yarn fineness is 0.8 to 2.0 dtex and the area ratio of the core portion in the fiber cross section is 20 to 40%.

[0020] (3) A fabric comprising at least a portion of the polyamide core-sheath composite fiber according to (1) or (2).

[0021] Effects of the Invention

[0022] According to the present invention, a polyamide core-sheath composite fiber can be provided which has hygroscopicity, antistatic properties, suppresses the generation of fuzz while maintaining strength, and is excellent in high-order permeability. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic diagram showing the cross-sectional shape of the fiber of the present invention.

[0024] Figure 2 This is a longitudinal sectional view showing an example of the discharge hole of the conjugate spinning nozzle used in the present invention.

[0025] Figure 3 This is a schematic diagram partially showing the arrangement of the core component introduction holes and the sheath component introduction holes of the lower introduction plate of the spinneret for composite spinning used in the present invention.

[0026] Figure 4 This is a diagram showing one embodiment of a production apparatus based on a direct spinning and drawing method preferably used in the method for producing the polyamide core-sheath composite fiber of the present invention. DETAILED DESCRIPTION

[0027] The polyamide core-sheath composite fiber of the present invention comprises a polyamide sheath portion and a polyetheresteramide copolymer as the core portion.

[0028] The polyamide core-sheath composite fiber of the present invention is Figure 1 As shown in the example, the cross-sectional uniformity ratio (d / R) of the cross section is less than 0.072. The cross-sectional uniformity ratio mentioned here refers to the value calculated by measuring the distance (d) between the center point of the inscribed circle of the core component (point C) and the center point of the inscribed circle of the sheath component (point S), and the diameter of the inscribed circle of the sheath component (R), and is the average value obtained by measuring all the monofilaments. The closer the value is to 0, the more concentric it is, and the larger the value, the more eccentric it is. By making the cross-sectional uniformity ratio (d / R) within this range, the generation of monofilament fluff is suppressed, and high-order passability is excellent. More preferably, it is 0.050 or less. When the cross-sectional uniformity ratio (d / R) exceeds 0.072, the core polyetheresteramide copolymer is eccentric, and the sheath thickness deviates in the sheath polyamide. Therefore, if external force is applied to the thin part of the sheath, the monofilament is likely to break from there, and the monofilament fluff is frequent. Not only does the high-order passability deteriorate, but the quality of the product also tends to deteriorate.

[0029] The strength of the polyamide core-sheath composite fiber of the present invention is 3.6 cN / dtex or greater. By setting it within this range, breakage during high-order processing is reduced, and high-order passability is improved. In addition, the product has excellent durability. When it is less than 3.6 cN / dtex, there is a tendency for breakage during high-order processing to increase and high-order passability to deteriorate. In addition, in clothing applications such as outerwear and sportswear, it is sometimes easy to reach a level that cannot withstand actual use, and the product durability is poor. A more preferred range is 4.0 cN / dtex or greater.

[0030] The polyamide core-sheath composite fiber of the present invention preferably has a core area ratio of 20% to 40% in the fiber cross section. It is more preferably 20% to 30%, and even more preferably 25% to 30%. Within this range, the sheath readily absorbs a large amount of limited moisture in the air, increasing the rate of transfer of this absorbed moisture to the core. Furthermore, a small core area ratio allows any static electricity to be rapidly transferred to the water-absorbing core, resulting in excellent hygroscopicity and antistatic properties.

[0031] The polyamide core-sheath composite fiber of the present invention has a resistivity of 10 at a temperature of 20°C and a humidity of 40% RH. 7 ~10 10 Ω·cm. By setting it within this range, antistatic properties can be obtained. The resistivity of general polyamide fibers is 10 14 Ω·cm level. Moreover, static electricity is affected by the amount of moisture in the air. It is not easy to generate static electricity in a high humidity environment, but it is easy to generate static electricity in a dry environment. In order to fully exert the antistatic property, if the temperature is 20℃ and the humidity is 40%RH, it has 10 10 The resistivity value below Ω·cm can fully exert antistatic performance. It should be noted that the lower limit of the resistivity value that can be achieved in the present invention is 10 7 About Ω·cm.

[0032] In the polyamide core-sheath composite fiber of the present invention, ΔMR is preferably 5.0% or more. By setting it within this range, hygroscopicity can be obtained. In order to obtain good comfort when wearing, it is required to have the function of regulating the humidity inside the clothes. As an indicator of this humidity regulation, ΔMR is used, which is represented by the difference between the temperature and humidity inside the clothes represented by 30°C×90%RH during light to medium work or light to medium exercise and the moisture absorption rate at the external atmospheric temperature and humidity represented by 20°C×65%RH. The larger the ΔMR, the higher the hygroscopic performance and the better the comfort when wearing. If ΔMR is 5.0% or more, it is possible to suppress stuffiness and stickiness during wearing, and it is possible to provide clothing with excellent comfort. The upper limit value of ΔMR is about 17.0%.

[0033] The polyamide core-sheath composite fiber of the present invention can have any total fineness suitable for clothing, preferably 8 to 155 dtex. The single filament fineness can also be arbitrarily set according to product requirements. However, with the trend toward thin, lightweight, soft, and low-air-permeability fabrics, both fiber fineness and single filament fineness are becoming increasingly desirable. Therefore, a fineness of 0.8 to 2.0 dtex is preferred.

[0034] The polyamide core-sheath composite fiber of the present invention preferably has an elongation of 40% or more, more preferably 42 to 65%. By setting it within this range, breakage in high-order processing steps is reduced, and high-order passability is improved.

[0035] The polyamide core-sheath composite fiber of the present invention uses polyamide in the sheath portion and a polyetheresteramide copolymer in the core portion.

[0036] The polyetheresteramide copolymer used in the core of the present invention is a block copolymer having ether, ester, and amide bonds within the same molecular chain. More specifically, it is a block copolymer obtained by polycondensing one or more polyamide components (A) selected from lactams, aminocarboxylic acids, diamines, and salts of dicarboxylic acids, and a polyetherester component (B) composed of a dicarboxylic acid and a poly(alkylene oxide) glycol.

[0037] The polyamide component (A) includes lactams such as ε-caprolactam, lauryl lactam, and undecanoic acid, ω-aminocarboxylic acids such as aminocaproic acid, 11-aminoundecanoic acid, and 12-aminododecanoic acid, and nylon salts of diamine-dicarboxylic acids that are precursors of nylon 66, nylon 610, nylon 612, etc. The preferred polyamide-forming component is ε-caprolactam.

[0038] The polyetherester component (B) is formed from a dicarboxylic acid having 4 to 20 carbon atoms and a poly(alkylene oxide) glycol. Examples of 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 dodecanedioic 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. One or more of these can be used alone or in combination. Preferred dicarboxylic acids are adipic acid, sebacic acid, dodecanedioic acid, terephthalic acid, and isophthalic acid. In addition, examples of the poly(alkylene oxide) glycol include polyethylene glycol, poly(1,2- and 1,3-propylene oxide) glycol, poly(tetramethylene ether) glycol, and poly(hexamethylene ether) glycol. Polyethylene glycol having good hygroscopic properties is particularly preferred.

[0039] The number average molecular weight of the poly(alkylene oxide) glycol is preferably 300 to 5000, more preferably 500 to 4000. A molecular weight of 300 or greater is preferred because it is less likely to scatter outside the system during the polycondensation reaction, resulting in fibers with stable hygroscopicity and antistatic properties. A molecular weight of 5000 or less is also preferred because the poly(alkylene oxide) glycol is uniformly dispersed in the polymer, resulting in excellent hygroscopicity and antistatic properties.

[0040] The molar ratio of the polyetherester component (B) in the overall polyetheresteramide copolymer is preferably 20 to 80%. A molar ratio of 20% or more is preferred because good hygroscopicity and antistatic properties are achieved. A molar ratio of 80% or less is also preferred because good color fastness, hygroscopicity, and antistatic properties can be achieved with washing durability.

[0041] The molar ratio of polyamide to poly(alkylene oxide) glycol is preferably 20% / 80% to 80% / 20%. A poly(alkylene oxide) glycol content of 20% or more is preferred because it provides excellent hygroscopicity and antistatic properties. A poly(alkylene oxide) glycol content of 80% or less is also preferred because it provides excellent color fastness, hygroscopicity, and antistatic properties, as well as washing durability.

[0042] As such a polyetheresteramide copolymer, "MH1657" and "MV1074" manufactured by Arkema are commercially available.

[0043] The o-chlorophenol relative viscosity of the polyetheresteramide copolymer chips used in the core of the present invention is preferably 1.2 or higher and 2.0 or lower. When the o-chlorophenol relative viscosity is 1.2 or higher, optimal stress is applied to the sheath during spinning, promoting crystallization of the polyamide in the sheath and achieving increased strength.

[0044] Poly(alkylene oxide) glycol undergoes a chain reaction in which free radicals are generated within the molecule when heat is applied. These free radicals then attack adjacent atoms, generating further free radicals. The heat of the reaction causes temperatures exceeding 200°C. Furthermore, the smaller the molecular weight of the poly(alkylene oxide) glycol, the more easily heat is applied to the molecular chain, resulting in a tendency for free radicals to be generated, leading to a higher generation of reaction heat.

[0045] The number average molecular weight of the poly(alkylene oxide) glycol contained in the polyetheresteramide copolymer used in the present invention is 300 to 5000, which is relatively small. Therefore, based on the above-mentioned mechanism, the thermal degradation of the polyetheresteramide copolymer is easy to proceed, which is very likely to cause the solidification, embrittlement, hygroscopicity and antistatic properties of the raw yarn to decrease.

[0046] Therefore, it is preferred to add a free radical-scavenging hindered phenolic antioxidant to the core polyetheresteramide copolymer. A semi-hindered phenolic antioxidant is more preferred. The amount of hindered phenolic antioxidant added is preferably 1.0% by weight or more and 5.0% by weight or less relative to the weight of the core polyetheresteramide copolymer. More preferably, it is 2.0% by weight or more.

[0047] Examples of the bis-hindered phenol antioxidant include pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] (IR1010), tris(4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl)isocyanuric acid (IR1790), (1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxyphenyl)benzene (AO-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 (IR3114), and N,N'-hexamethylenebis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionamide] (IR1098).

[0048] In the case of bis-hindered phenol antioxidants, thermal degradation of polyetheresteramide copolymers is accelerated by the thermal history during the spinning process (high temperatures applied during polymer melting, heat setting after stretching) and the thermal history during high-level processing steps (dying and heat setting of the fabric, etc.), significantly reducing the effective amount of antioxidants that capture free radicals remaining in the fabric and clothing products. Therefore, in order to prevent the reduction in the effective amount of antioxidants that capture free radicals remaining in the fabric and clothing products, the combined use of hindered amine (HALS (Hindered Amine Light Stabilizer)) stabilizers can suppress thermal degradation of hindered phenol antioxidants, thereby suppressing reaction heat and thermal degradation, and preventing solidification, embrittlement, and reduction in hygroscopicity and antistatic properties of the raw yarn. Examples of HALS stabilizers include dibutylamine 1,3,5-triazine, N,N-bis(2,2,6,6-tetramethyl-4-piperidinyl)-1,6-hexamethylenediamine, and N-(2,2,6,6-tetramethyl-4-piperidinyl)butylamine condensation product (CHIMASSORB2020FDL), 4,7,N,N'-tetrakis[4,6-bis[butyl(1,2,2,6,6-pentamethyl-4-piperidinyl) )amino]-1,3,5-triazine-2-yl]-4,7-diazadecane-1,10-diamine (CHIMASSORB 119), poly[{6-(1,1,3,3-tetramethylbutyl)amino-1,3,5-triazine-2,4-diyl)(2,2,6,6-tetramethyl-4-piperidinyl)imino)hexamethylene((2,2,6,6-tetramethyl-4-piperidinyl)imino](CHIMASSORB 944).

[0049] Examples of semi-hindered phenol antioxidants include 2,2'-dimethyl-2,2'-(2,4,8,10-tetraoxaspiro[5.5]undecane-3,9-diyl)dipropane-1,1'-diylbis[3-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionate] (Sumilyzer (registered trademark) AG80 manufactured by Sumitomo Chemical Co., Ltd., and Adeka Stab (registered trademark) AO-80 manufactured by Adeka Co., Ltd.), and 1,3,5-tris[[4-(1,1-dimethylethyl)-3-hydroxy-2,6-dimethylphenyl]methyl]-1,3,4-triazine-2,4,6(1H,3H,5H)-trione (Cyanox 1790 manufactured by Solbe).

[0050] Compared to bis-hindered phenol antioxidants, semi-hindered phenol antioxidants exhibit significantly less reduction in the amount of the antioxidant's active ingredient during the thermal history of the spinning process and the thermal history of high-level processing steps. Therefore, unlike bis-hindered phenol antioxidants, which require the use of HALS stabilizers, the use of semi-hindered phenol antioxidants alone can suppress reaction heat and thermal degradation, thereby preventing the solidification, embrittlement, and reduction in hygroscopicity and antistatic properties of the raw yarn. Furthermore, the decomposition products of semi-hindered phenols exhibit minimal coloration, thus also preventing yellowing.

[0051] The core polyetheresteramide copolymer may also contain other phosphorus stabilizers. Furthermore, various other additives, such as matting agents, flame retardants, ultraviolet absorbers, infrared absorbers, crystal nucleating agents, fluorescent brighteners, antistatic agents, hygroscopic polymers, and carbon, may be copolymerized or mixed as needed so that the total additive content is 5% by weight or less relative to the polyetheresteramide copolymer.

[0052] The ratio of the core portion is preferably 20% to 40% by weight relative to the entire composite fiber. It is further preferably 20% to 30% by weight, and more preferably 25% to 30% by weight. The higher the ratio of the core portion, the higher the hygroscopicity and antistatic properties, but the strength decreases. On the other hand, the lower the ratio of the core portion, the higher the strength, but the hygroscopicity and antistatic properties decrease. By setting it to this range, hygroscopicity and antistatic properties are shown, and appropriate stretching can be applied to the polyamide of the sheath portion to reach high strength.

[0053] Examples of polyamides used in the sheath of the present invention include nylon 6, nylon 66, nylon 46, nylon 9, nylon 610, nylon 11, nylon 12, and nylon 612, or copolymerized polyamides containing these and compounds having amide-forming functional groups, such as laurolactam, sebacic acid, terephthalic acid, isophthalic acid, and 5-sodium sulfoisophthalate. Among these, nylon 6, nylon 11, nylon 12, nylon 610, and nylon 612 have a small difference in melting point from the polyetheresteramide copolymer, which can suppress thermal degradation of the polyetheresteramide copolymer during melt spinning and is therefore preferred from the perspective of yarn-forming properties. Nylon 6, which has excellent dyeability, is particularly preferred.

[0054] In the polyamide of the sheath portion, various additives such as matting agents, flame retardants, antioxidants, ultraviolet absorbers, infrared absorbers, crystallization nucleating agents, fluorescent brighteners, antistatic agents, hygroscopic polymers, carbon, etc. can be copolymerized or mixed as needed in a manner such that the total additive content is less than 5 weight % relative to the polyetheresteramide copolymer.

[0055] The polyamide chips used in the sheath of the present invention preferably have a sulfuric acid relative viscosity of 2.3 or more and 3.3 or less. By setting the viscosity within this range, appropriate stretching can be applied to the polyamide in the sheath to achieve high strength.

[0056] The melt viscosity of the polyetheresteramide copolymer used in the present invention is 400 to 600 poise, which is lower than the melt viscosity of the polyamide used in the present invention, which is 900 to 1500 poise, and the difference in melt viscosity is also large. Therefore, it is preferred to select a combination of a polyetheresteramide copolymer and a polyamide having a melt viscosity ratio of 3.0 or less at the spinning temperature. By setting it within the above range, the stress applied along the length direction of the filament during thinning and stretching after being discharged from the die during spinning is not biased towards the sheath component, and there is a tendency to reduce the cross-sectional uniformity ratio (d / R). If it exceeds 3.0, the stress applied along the length direction of the filament during thinning and stretching is biased towards the sheath component, and the cross-sectional uniformity ratio becomes larger. The melt viscosity mentioned here refers to the melt viscosity that can be measured by a capillary rheometer using a vacuum dryer to reduce the moisture content of the sliced ​​polymer to less than 200 ppm, and refers to the melt viscosity at the same shear rate at the spinning temperature.

[0057] Since the melting point of the polyetheresteramide copolymer is lower than that of the polyamide, it is preferable to select a polyetheresteramide copolymer and a polyamide with a melting point difference of 30°C or less from the perspective of suppressing thermal degradation of the polyetheresteramide copolymer during melt spinning and improving spinning properties.

[0058] In the spinning process, the core polymer melt temperature is preferably set to 235° C. or higher and 260° C. or lower. A core polymer melt temperature of 235° C. or higher is preferred because the core polyetheresteramide copolymer has a melt viscosity suitable for melt spinning. A core polymer melt temperature of 260° C. or lower is preferred because thermal decomposition of the core polyetheresteramide copolymer due to a temperature increase can be suppressed.

[0059] The melting point temperature of the sheath polymer is preferably 240°C or higher and 285°C or lower. A melting point temperature of 240°C or higher is preferred because the polyamide in the sheath has a melt viscosity suitable for melt spinning. A melting point temperature of 285°C or lower is preferred because thermal decomposition of the polyetheresteramide copolymer in the core due to temperature increases can be suppressed.

[0060] The melting zone temperature at the confluence is preferably set to 235°C or higher and 270°C or lower. A temperature of 235°C or higher is preferred because the polyamide and polyetheresteramide copolymer have a melt viscosity suitable for melt spinning. A temperature of 270°C or lower is preferred because thermal decomposition of the polyetheresteramide copolymer can be suppressed.

[0061] In order to control the cross-sectional uniformity ratio (d / R) of the core-sheath composite fiber of the present invention within such a range, it is necessary to optimize the die design until the core-sheath components merge, based on the melt viscosities of the core and sheath polymers.

[0062] Figure 2 This is a longitudinal sectional view showing an example of the discharge hole of the spinneret for composite spinning used in the core-sheath composite fiber of the present invention. Figure 2 In the composite spinneret, the components are stacked in the order of upper introduction plate 1, lower introduction plate 2, and die plate 3 from the top. Figure 2 、 Figure 3 In the composite spinning spinneret exemplified in FIG, the description will be made along the flow of the polymer from the upstream to the downstream of the composite spinning spinneret.

[0063] The core component polymer flows into the core component inlet hole 1-1 of the upper inlet plate, is measured by the core component throttling section 1-2 provided through the lower end, and is then discharged into the core component inlet hole 2-1 of the lower inlet plate. Similarly, the core component polymer flowing into the core component inlet hole 2-1 of the lower inlet plate is measured by the core component throttling section 2-2 provided through the lower end, and then flows into the confluence pool 3-1 of the inlet template 3.

[0064] The sheath component polymer flows into the sheath component inlet holes 1-3 of the upper inlet plate and is discharged into the sheath component reservoir 2-3 of the lower inlet plate. Below the sheath component reservoir 2-3 of the lower inlet plate, which accumulates the polymer flowing in from the sheath component inlet holes of the upper inlet plate, a sheath component inlet hole 2-4 is provided to allow the polymer to flow downstream. The sheath component polymer flowing into the sheath component reservoir 2-3 is metered by a sheath component restriction 2-5 provided through the lower end before flowing into the confluence pool 3-1 of the inlet template 3.

[0065] The core polymer and the sheath polymer flow into the confluence pool 3-1 of the inlet template 3 respectively, form a core-sheath composite form and flow into the discharge hole 3-3, pass through the discharge hole throttle part 3-2 set at the lower end for metering, and then are discharged.

[0066] To maintain accurate metering of the core polymer, metering is performed once using upper inlet plate 1 and then again using lower inlet plate 2, for a total of two metering steps. Because the core polymer has low viscosity, these two metering steps control polymer flow, ensuring that the core polymer truly forms the center. Furthermore, metering using upper inlet plate 1 increases the pressure of the core polymer, improving the seal between upper and lower inlet plates 1 and 2 and preventing polymer leakage.

[0067] In order to maintain the metering performance of the sheath component polymer, the relationship L / D between the hole length (L) and the pore diameter (D) of the sheath component throttling part 2-5 of the lower inlet plate 2 needs to be set to 1.0 to 2.5. By making L / D above 1.0, the metering performance is stable and the cross-sectional uniformity ratio can be within the relevant range. If the pore diameter is large and the hole length is small, the metering performance is reduced and eccentricity is easy. When L / D is less than 1.0, the cross-sectional uniformity ratio (d / R) sometimes exceeds 7.2. If the pore diameter (D) is too small to improve the metering performance, the polymer foreign matter is easy to clog and the cross-sectional defect is easy to occur. In addition, if the hole length (L) is too large, the back pressure of the die becomes large, the deformation of the die becomes large, and the pump cannot withstand the polymer pressure, and polymer leakage is easy to occur. By making L / D below 2.5, a uniform cross-section can be obtained and stable silk making can be carried out. More preferably, it is 1.5 to 2.5.

[0068] like Figure 3As shown, in the lower inlet plate 2, three sheath component inlet holes 2-4 need to be set through the core component inlet hole 2-1 and its surroundings. By setting the number of through-holes to 3, the sheath polymer can be evenly filled in the confluence pool 3-1 of the mouth template 3, and the cross-sectional uniformity ratio can be within the relevant range. When the number of through-holes is 2 or less, the filling of the polymer in the confluence pool 3-1 is prone to deviation, and the cross-sectional uniformity ratio (d / R) sometimes exceeds 7.2. When the number of through-holes is 4 or more, in order to maintain metering, it is necessary to design the pore size (D) to be small or the pore length (L) to be large, which makes it easy for blockage and leakage to occur, reduces the silk-making stability, and also makes it easy for cross-sectional defects to occur.

[0069] Furthermore, for the three sheath component introduction holes 2-4 provided through the holes, in order to further reduce the cross-sectional uniformity ratio (d / R), it is preferred that the discharge amount of each hole be the same. Therefore, it is preferred that the holes be provided through the holes at point-symmetrical points, that is, on the same track.

[0070] Figure 4 This is a diagram showing one embodiment of a production apparatus based on a direct spinning and drawing method preferably used in the method for producing the polyamide core-sheath composite fiber of the present invention.

[0071] The polyamide (sheath) and polyetheresteramide copolymer (core) are melted separately, metered and transported using a gear pump, and ejected from the composite spinneret 4 to form individual filaments. Each filament ejected from the composite spinneret 4 is subjected to cooling air blown by a filament cooling device 5, such as an air duct, to cool and solidify the filaments to room temperature. An oiling agent is then applied using an oiling device 6, and the filaments are bundled to form a multifilament yarn. This is interwoven using a fluid interweaving nozzle device 7, and passed through a drawing roller 8 and a stretching roller 9, where they are stretched according to the ratio of the circumferential speeds of the drawing roller 8 to the stretching roller 9. Furthermore, the filaments are heat-treated by heating the stretching roller 9 and are wound up using a winding device.

[0072] In the production of the polyamide core-sheath composite fiber of the present invention, the cooling device 5 can be manufactured by any of the following methods: a cooling device that blows out cooling and rectifying air from a certain direction, an annular cooling device that blows out cooling and rectifying air from the outer periphery to the center, or an annular cooling device that blows out cooling and rectifying air from the center to the outer periphery. When the vertical distance Ls (hereinafter referred to as the cooling start distance) from the lower surface of the spinneret to the upper end of the cooling air blowing portion of the cooling device 5 is in the range of 159 to 219 mm, it is preferred from the perspective of suppressing yarn swing and fiber unevenness, and more preferably 169 to 189 mm. Regarding the cooling air speed blown out from the cooling air blowing surface, from the perspective of fineness unevenness and strength, it is preferably in the range of 20.0 to 40.0 (m / min) as the average of the interval from the upper end surface to the lower end surface of the cooling air blowing portion.

[0073] In the manufacture of the polyamide core-sheath composite fiber of the present invention, the polymer discharged from the spinneret is solidified by blowing cooling air through a cooling device, and is stretched by the spinning tension accompanied by the accompanying flow between the solidification position and the oil supply position, and then mechanically stretched between the traction roller and the stretching roller. For the core-sheath composite fiber of the present invention, mechanical stretching is performed to promote the oriented crystallization of the sheath polymer and improve the strength, and reducing the spinning tension is the key point to suppress the oriented crystallization of the core polymer and improve the moisture absorption performance. Therefore, the position of the oil supply device 6, that is, Figure 4 The vertical distance Lg from the lower surface of the spinneret to the oil supply nozzle position of the oil supply device 6 (hereinafter referred to as the oil supply position Lg) also depends on the single fiber fineness and the cooling efficiency of the filaments from the cooling device, but is preferably 800 to 1500 mm, and more preferably 1000 to 1300 mm. When the oil supply position is less than 800 mm, the filaments will not be fully cooled, and they will be damaged by contact with the oil supply guide in a structurally unstable state. Therefore, not only will the single fiber strength of the filaments be reduced, but the fluff will also tend to increase. In particular, when the single fiber fineness is fine, the core ratio is high, and the cross-sectional uniformity ratio is high, the thinner the sheath thickness, the more likely it is to be damaged, and sometimes the above phenomenon will occur significantly. In addition, when the oil supply position exceeds 1500 mm, the spinning tension becomes high, so not only will the orientation crystallization of the core polymer proceed and the hygroscopicity be reduced, but the mechanical stretching ratio will also be reduced, so the strength will also be reduced, and sometimes fuzzing will occur.

[0074] In the stretching process of manufacturing the polyamide core-sheath composite fiber of the present invention, it is preferred to set the spinning conditions in a manner such that the product of the speed of the filaments to be towed by the traction roller (spinning speed) and the value of the circumferential speed ratio of the traction roller and the stretching roller, i.e., the stretching ratio, is 3300 or more and 4500 or less. It is further preferred to be 4000 or less. This numerical value represents the total stretching amount of the polymer discharged from the die from the die discharge linear speed to the circumferential speed of the traction roller, and then from the circumferential speed of the traction roller to the circumferential speed of the stretching roller. By setting it to this range, appropriate stretching can be applied to the polyamide of the sheath portion. If it is more than 3300, the polyamide of the sheath portion is crystallized, so the raw yarn strength is improved, and therefore it is preferred. If it is less than 4500, the crystallization of the polyamide of the sheath portion is appropriately carried out, and the generation of broken yarns and fuzzing during silk making is less, which is preferred.

[0075] With the demand for thin, lightweight, soft, and low-permeability fabrics, there is a trend toward finer fiber deniers and finer single-filament deniers. This has led to a decrease in the single-filament strength of polyamide core-sheath composite fibers, where the sheath comprises polyamide and the core comprises a polyetheresteramide copolymer. Furthermore, as the core area ratio increases, the finer the single-filament denier becomes, and the thickness of the polyamide sheath, which provides the single-filament strength, decreases, reducing the single-filament strength.

[0076] On the other hand, in polyamide monocomponent fibers, to ensure single-filament strength, the draw ratio is typically adjusted appropriately within a range that maintains the elongation required for high-order processing. However, in the polyamide core-sheath composite fibers of the present invention, the thinner the sheath thickness, the higher the draw ratio. This, in turn, increases the sheath's susceptibility to breakage, increasing the occurrence of single-filament fuzz, which not only deteriorates high-order passability but also worsens product quality. Therefore, the polyamide core-sheath composite fibers of the present invention require that the strength and cross-sectional area ratio be within relevant ranges. Therefore, it is necessary to set manufacturing conditions that ensure uniform sheath thickness while ensuring the strength of the polyamide in the sheath.

[0077] Although it also depends on the core-sheath composite ratio, the single yarn fineness and the cooling efficiency of the filament from the cooling device, by setting the oil supply position to 800 to 1500 mm from the spinneret surface and the product of the spinning speed and the stretching ratio to be greater than 3300 and less than 4500, optimal stress is applied to the sheath polyamide during spinning, appropriate stretching can be applied, the crystallization of the sheath polyamide is promoted, and the strength can be controlled within the relevant range.

[0078] By using polyamide suitable for melt viscosity of 900-1500 poise, polyetheresteramide copolymer with melt viscosity of 400-600 poise, and flow balance (melt viscosity ratio), and a composite spinneret suitable for flow balance, discharge stability can be ensured and the cross-sectional uniformity ratio can be controlled within the relevant range.

[0079] By employing these conjugate spinnerets and spinning conditions, core-sheath conjugate fibers with excellent hygroscopicity and antistatic properties can be obtained, with a strength of 3.6 cN / dtex or greater, a cross-sectional uniformity ratio d / R of 0.072 or less for the core-sheath components of all filaments, and excellent antistatic properties. This effect is particularly pronounced when the sheath thickness is relatively thin, the single-filament fineness is 2.0 dtex or less, and the core area ratio is 20% or greater.

[0080] The core-sheath composite fibers of the present invention have excellent hygroscopicity and antistatic properties and are therefore preferably used in clothing products. The fabric form can be woven or knitted, depending on the intended purpose. Furthermore, various clothing products such as underwear and sportswear can be made into clothing products.

[0081] Example

[0082] The present invention will be described in more detail below with reference to Examples. The methods for measuring the characteristic values ​​in the Examples are as follows.

[0083] (1) Relative viscosity of sulfuric acid

[0084] Dissolve 0.25 g of the sliced ​​sample in 100 ml of 98 wt% sulfuric acid to make 1 g. Use an Ostwald viscometer to measure the elution time (T1) at 25°C. Next, measure the elution time (T2) of the 98 wt% sulfuric acid. The ratio of T1 to T2, T1 / T2, is used as the relative viscosity of the sulfuric acid.

[0085] (2) Orthochlorophenol relative viscosity (OCP relative viscosity)

[0086] Dissolve 0.5 g of the sliced ​​sample in 100 ml of o-chlorophenol to obtain 1 g. The elution time (T1) at 25°C was measured using an Ostwald viscometer. Next, the elution time (T2) of the o-chlorophenol was measured. The ratio of T1 to T2, i.e., T1 / T2, was used as the relative viscosity of sulfuric acid.

[0087] (3) Melt viscosity

[0088] The sliced ​​sample was kept at a moisture content of 200 ppm or less using a vacuum dryer. The melt viscosity was measured using a Toyo Seiki Cabigraph 1B while gradually changing the strain rate. The measurement temperature was set to the spinning temperature, and the time from sample placement in the heating furnace to the start of measurement was set to 5 minutes. Measurements were performed under a nitrogen atmosphere.

[0089] (4) Fineness, single yarn fineness

[0090] A fiber sample was placed on a ruler at 1.125 m / circle and rotated 200 times to form a circular hank. The hank was then dried in a hot air dryer (105 ± 2°C for 60 minutes). The hank mass was weighed on a balance, and the fineness was calculated by multiplying the value by the official moisture content. The official moisture content of the core-sheath composite fiber is 4.5%.

[0091] (5) Strength and elongation

[0092] Fiber samples were measured using the "TENSILON" (registered trademark) UCT-100 manufactured by ORIENTEC Co., Ltd. under the constant-rate elongation conditions specified in JIS L1013 (Test Methods for Chemical Filament Yarns, 2010). Elongation was calculated as the elongation at the point showing maximum strength on the tensile strength-elongation curve. Strength was determined by dividing the maximum strength by the fineness. Ten measurements were performed, and the average values ​​were used as strength and elongation.

[0093] (6) Cross-sectional uniformity and cross-sectional uniformity

[0094] A. Taking cross-sectional photos

[0095] The coating agent composed of paraffin, stearic acid, and ethyl cellulose was dissolved and introduced into the fiber, and then solidified by leaving it at room temperature. The raw fibers in the coating agent were cut along the cross-sectional direction, and the fiber cross-section was photographed using a CCD camera (CS5270) manufactured by Tokyo Electron Co., Ltd., and printed out at 1500 times using a color video processor (SCT-CP710) manufactured by Mitsubishi Electric.

[0096] B. Determination of cross-sectional uniformity ratio

[0097] like Figure 1 As shown in the example, the distance (d) between the center point of the inscribed circle of the core component (point C) and the center point of the inscribed circle of the sheath component (point S) and the diameter (R) of the inscribed circle of the sheath component are measured and calculated. The cross-section of all filaments of the core-sheath composite yarn is measured, and the average value is used as the cross-sectional uniformity ratio.

[0098] C. Cross-sectional uniformity

[0099] Cross sections of all filaments of the core-sheath composite yarn were visually observed and evaluated according to the following criteria.

[0100] A: The sheath and core components are circular and have a uniform cross-section with no deviation in size.

[0101] C: There are variations in the roundness and size of the sheath component and the core component, and the cross section is defective.

[0102] (7) Number of villi

[0103] The fiber sample is rewound at a speed of 500 m / min. A laser fuzz detector is placed 2 mm away from the rewound yarn. The total number of defects detected is converted to the number per 100,000 m. A count of 2 or fewer per 100,000 m is considered acceptable.

[0104] (8) Resistivity value

[0105] The fiber sample was thoroughly scoured in a 0.2% by weight aqueous solution of a weakly alkaline anionic surfactant to remove oils and other agents, then thoroughly rinsed and dried. The sample was then stretched into a fiber bundle with a length (L) of 5 cm and a total fineness (D) of 2200 dtex (2000 denier). After conditioning for two days at 20°C and 40% RH, the resistance of the sample was measured using a vibrating capacitance-type micropotential measuring instrument at an applied voltage of 500 V. The resistance was calculated using the following formula.

[0106] ρ=(R×0.9D) / (9×10 5 ×L×d×10 4 )

[0107] ρ: volume resistivity (Ω·cm), R: electrical resistance (Ω), D: fineness (dtex), L: sample length (cm), d: sample density (g / m 2 ).

[0108] (9)ΔMR

[0109] Weigh approximately 1-2 g of a fiber sample (or fabric) in a weighing bottle, dry it at 110°C for 2 hours, and measure its weight (W0). Next, maintain the sample at 20°C and 65% relative humidity for 24 hours, and measure its weight (W65). Next, maintain the sample at 30°C and 90% relative humidity for 24 hours, and measure its weight (W90). The following formula is then used to calculate the weight.

[0110] MR65=[(W65-W0) / W0]×100%······(1)

[0111] MR90=[(W90-W0) / W0]×100%······(2)

[0112] ΔMR=MR90-MR65·············(3).

[0113] (10) High-level passability

[0114] Ten pieces (1000 m / piece) of plain weave fabric were woven using a water jet loom at a loom speed of 750 rpm and a weft length of 1620 mm. The number of loom stops due to yarn breakage was evaluated according to the following criteria.

[0115] S: less than 2 times, A: 2 times or more and less than 4 times, B: 4 times or more and less than 6 times, C: 6 times or more. S, A, and B are considered to be acceptable for process passability.

[0116] [Example 1]

[0117] (Manufacturing of polyamide core-sheath composite fibers)

[0118] As a polyetheresteramide copolymer, a polyetheresteramide copolymer (made by Arkema, MH1657, relative viscosity of o-chlorophenol 1.69, melting point 200°C, melt viscosity 450 poise (260°C)) in which the polyamide component is nylon 6, the polyether component is polyethylene glycol with a molecular weight of 1500, and the molar ratio of nylon 6 to polyethylene glycol is 24%:76% is sliced ​​and used for the core. In addition, masterbatch chips containing a semi-hindered phenolic antioxidant 2,2'-dimethyl-2,2'-(2,4,8,10-tetraoxaspiro[5.5]undecane-3,9-diyl)dipropane-1,1'-diyl=bis[3-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionate] (Adekastab AO-80 manufactured by ADEKA Corporation) at a high concentration in a polyetheresteramide copolymer were previously blended with polyetheresteramide copolymer chips using a twin-screw extruder to adjust the content to 3.0% by weight based on the weight of the core.

[0119] As the polyamide, titanium oxide-free nylon 6 chips having a sulfuric acid relative viscosity of 2.73, a melting point of 215° C., and a melt viscosity of 1250 poise were used for the sheath portion.

[0120] The polyether ester amide copolymer was used as the core and nylon 6 was used as the sheath. The core melting temperature was 240°C, the sheath melting temperature was 270°C, and the spinning temperature was 265°C. Figure 2 、 Figure 3 In the three-piece structure shown in the example, the core is metered twice, the number of through-holes 2-4 for the sheath component is 3, the hole length (L) of the sheath component throttling part 2-5 of the lower inlet plate 2 for measuring the sheath component is 0.3 mm, the hole diameter (D) is 0.2 mm, the number of discharge holes of the mouth template 3 is 24, and the core / sheath ratio (weight %) is 30 / 70 when discharged from the concentric core-sheath composite spinneret.

[0121] use Figure 4 The composite spinning machine illustrated in the figure uses cold air at a cooling start distance Ls of 100 mm, a wind temperature of 18°C, and a wind speed of 30 m / min to pass through a yarn cooling device, cooling and solidifying the yarn to room temperature. A non-aqueous oil is then applied at an oiling position Lg 1300 mm from the spinneret surface, while the filaments are bundled to form a multifilament yarn. After the non-aqueous oil is supplied by the oiling device, interlacing is applied using a first fluid interlacing nozzle device. Drawing is performed at a circumferential speed of 3255 m / min for the first take-up roll and 4167 m / min for the second draw roll. Heat setting is performed at a draw ratio of 1.28 and a draw roll speed of 150°C. The yarn is then wound at a relaxation rate of 4.0% and a winding speed of 4000 m / min to produce a 22 dtex, 12-filament core-sheath composite yarn, consisting of two yarns. The raw yarn properties are shown in Table 1.

[0122] (Fabric Manufacturing)

[0123] The core-sheath composite fiber was used for warp and weft yarns, with a warp density of 188 yarns / 2.54 cm and a weft density of 155 yarns / 2.54 cm, and was woven in a plain weave.

[0124] The resulting fabric was scoured in a conventional solution containing 2 g of caustic soda (NaOH) per liter using an open mill, dried using a drum dryer at 120°C, and preformed at 170°C. The fabric was then dyed using a 1.0% owf acid dye (Nylosan Blue-GFL 167% (Sandos)) at 98°C for 60 minutes using a jet dyeing machine. The fabric was then fixed using 3 g / l of synthetic tannin (Nylonfix 501, Senka) at 80°C for 20 minutes, dried at 120°C, and finished at 175°C. The fabric was then calendered once on both sides (processing conditions: drum processing, heated roll surface temperature 180°C, heated roll load 147 kN, fabric travel speed 20 m / min) to produce a fabric with a warp density of 210 strands / 2.54 cm and a pick density of 160 strands / 2.54 cm. Table 1 shows the results of evaluation of the obtained woven fabric.

[0125] [Examples 2-3, Comparative Examples 1-2]

[0126] Spinning was performed in the same manner as in Example 1, except that a spinneret having a different L / D ratio as shown in Table 1 was formed in the sheath component throttling portion 2-5 of the lower inlet plate 2 for measuring the sheath component, to obtain a core-sheath composite yarn and form a woven fabric. The obtained results are shown in Table 1.

[0127] [Comparative Examples 3-4]

[0128] A spinneret having a core component introduction hole 2-1 and a sheath component introduction hole 2-4 formed around the lower introduction plate 2 was formed, with the number of the core component introduction holes 2-1 and the sheath component introduction holes 2-4 being changed as shown in Table 1. Spinning was performed in the same manner as in Example 1 to obtain a core-sheath composite yarn and form a fabric. The obtained results are shown in Table 1.

[0129] [Comparative Example 5]

[0130] The spinning was carried out in the same manner as in Example 1 except that a two-piece structure was formed, the core was measured once, the number of penetrations was set to 3, and the L / D of the sheath component restriction portion for measuring the sheath component was changed as shown in Table 1. The core-sheath composite yarn was obtained and a fabric was made. The obtained results are shown in FIG.

[0131] Table 1.

[0132]

[0133] In Examples 1 to 3 of the present invention, the occurrence of fuzz was suppressed and the high-order passing property was excellent.

[0134] Comparative Example 1, in which the L / D ratio of the sheath component throttle portion of the lower inlet plate for metering the sheath component was small, Comparative Example 3, in which the number of penetrations was small, and Comparative Example 5, in which the core was metered once, showed low metering performance of the polyetheresteramide copolymer, high cross-sectional uniformity, observed unevenness, and poor fuzz and high-order passability. Furthermore, Comparative Example 2, in which the L / D ratio was large, and Comparative Example 4, in which the number of penetrations was large, showed a lack of cross-sectional uniformity and poor spinning stability.

[0135] [Examples 4-5, Comparative Examples 6-7]

[0136] Spinning was carried out in the same manner as in Example 1 except that the oil supply position Lg was changed as shown in Table 2 and the spinning speed and draw ratio were adjusted as shown in Table 2 to obtain a core-sheath composite yarn and a woven fabric.

[0137] [Examples 6 to 8]

[0138] Spinning was carried out in the same manner as in Example 1 except that the core ratio (wt%) was changed as shown in Table 2 and the spinning speed and draw ratio were adjusted as shown in Table 2 to obtain core-sheath composite yarns and fabrics.

[0139]

[0140] Examples 4 to 8 of the present invention have hygroscopicity and antistatic properties, suppress the occurrence of fuzzing while maintaining strength, and are excellent in high-order passability.

[0141] In Comparative Example 6, where the oil supply point Lg was located relatively far below the spinneret, the sheath polyamide was not properly stretched, resulting in reduced strength and increased fuzz, leading to poor high-order passability. Furthermore, in Comparative Example 7, where the oil supply point Lg was located relatively short below the spinneret, insufficient cooling of the filaments occurred, leading to structural instability and damage from contact with the oil supply guide. This resulted in a slight decrease in strength and increased fuzz, resulting in poor high-order passability. Example 8, with a high core ratio, had a thinner sheath than Example 1, slightly reduced strength, and slightly more fuzz, but the high-order passability was acceptable.

[0142] [Examples 9-10]

[0143] Spinning was performed 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 speed, draw ratio, and oil supply position were adjusted as shown in Table 3 to obtain a core-sheath composite yarn and a woven fabric. The obtained results are shown in Table 3.

[0144] [Example 11]

[0145] Nylon 6 chips containing 1.8% titanium oxide, having a sulfuric acid relative viscosity of 2.63, a melting point of 215°C, and a melt viscosity of 1000 poise, were used as the sheath portion of the polyamide. Spinning was performed in the same manner as in Example 1, except that the spinning speed and draw ratio were adjusted as shown in Table 3, to obtain a core-sheath composite yarn and fabric. The obtained results are shown in Table 3.

[0146] Table 3

[0147]

[0148] Explanation of symbols

[0149] 1: Upper guide plate

[0150] 1-1: Core component introduction hole

[0151] 1-2: Core component throttling part

[0152] 1-3: Sheath component introduction hole

[0153] 2: Lower inlet plate

[0154] 2-1: Core component introduction hole

[0155] 2-2: Core component throttling part

[0156] 2-3: Sheath component pool

[0157] 2-4: Sheath component introduction hole

[0158] 2-5: Sheath component throttling part

[0159] 3: Mouth template

[0160] 3-1: Merging pool

[0161] 3-2: Discharge hole throttling part

[0162] 3-3: Discharge hole

[0163] 4: Spinneret

[0164] 5: Cooling device

[0165] 6: Oil supply device

[0166] 7: Fluid interweaving nozzle device

[0167] 8: Traction roller

[0168] 9: stretching roller

[0169] 10: Winding device

[0170] Lg: Oil supply position

[0171] Ls: Cooling start distance

Claims

1. A polyamide core-sheath composite fiber, wherein the sheath polymer is composed of polyamide and the core polymer is composed of a polyetheresteramide copolymer, the single yarn fineness is 0.8 to 2.0 dtex, the strength is 3.6 cN / dtex or more, the cross-sectional uniformity ratio d / R of the core-sheath component in the fiber cross section is less than 0.072, and the resistivity is 10 7 ~10 10 Ω·cm; d: The distance between the center of the inscribed circle of the core component and the center of the inscribed circle of the sheath component R: Diameter of the inscribed circle of the sheath component. 2 . The polyamide core-sheath composite fiber according to claim 1 , wherein the area ratio of the core portion in the fiber cross section is 20 to 40%.

3. A fabric comprising at least a portion thereof the polyamide core-sheath composite fiber according to claim 1 or 2.

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