WO2022065121A1

WO2022065121A1 - Polyamide core-sheath composite fiber and fabric

Info

Publication number: WO2022065121A1
Application number: PCT/JP2021/033633
Authority: WO
Inventors: 岸田泰輔; 吉岡大輔
Original assignee: 東レ株式会社
Priority date: 2020-09-24
Filing date: 2021-09-14
Publication date: 2022-03-31
Also published as: TW202231949A; KR20230073146A; EP4219810A1; CN115989344A; JPWO2022065121A1; US20230323568A1

Abstract

Provided is a polyamide core-sheath composite fiber comprising a sheath polymer formed from polyamide and a core polymer formed from polyether ester amide copolymer, wherein the core-sheath composite fiber has a strength of 3.6 cN/dtex or greater, a cross-sectional uniformity ratio d/R of the core-sheath component in the entire yarn of 0.072 or less, and an electrical specific resistance of 10⁷ to 10¹⁰ Ω･cm.　The provided polyamide core-sheath composite fiber has a humidity-absorbing property and an antistatic property, and while retaining strength, suppresses generation of fluff and has excellent high-order passability .

Description

Polyamide core-sheath composite fiber and fabric

The present invention relates to a polyamide core-sheath composite fiber and a fabric. More specifically, the present invention relates to a polyamide core-sheath composite fiber and a fabric having excellent hygroscopicity and antistatic properties.

Synthetic fibers made of thermoplastic resins such as polyamide and polyester are widely used in clothing and industrial applications because of their excellent strength, chemical resistance, and heat resistance. In particular, polyamide fiber is excellent in its unique softness, high tensile strength, color development during dyeing, high heat resistance, etc., and is widely used for general clothing applications such as innerwear, outerwear, and sportswear. ..

In recent years, with the spread of outdoor sports, the demand for sports and casual clothing is increasing year by year. In particular, woven fabrics used for down jacket base fabrics and windbreakers are required to be thin, lightweight, soft, and have low air permeability, and polyamide fibers are becoming finer and finer than single yarn. Polyamide fibers have the property of being easily charged, and are easily charged with static electricity in a low temperature and low humidity winter environment. With the progress of thinning, static electricity is more likely to be generated, and polyamide fibers having excellent antistatic properties are desired.

Polyamide fibers having excellent antistatic properties have been proposed in many ways, such as a method of applying an antistatic agent to fibers and fabrics by post-processing, and a method of forming composite fibers with a polymer having antistatic properties. Among them, the core-sheath composite polyamide fiber that uses a moisture-absorbing component in the core has excellent antistatic properties, and the polyamide fiber has a remarkable electrical resistance and eliminates the drawback of being easily charged with static electricity, especially in winter. There are high demands for applications such as outer wear used under low temperature and low humidity, and research and proposals are progressing.

For example, Patent Document 1 describes a core-sheath composite fiber having a polyamide resin as a sheath and a polyether ester amide copolymer as a core, and a composite fiber having a single yarn fineness of 3.5 dtex. .. Patent Document 2 describes a composite fiber having a polyamide resin as a sheath and a polyether ester amide copolymer as a core, and the area ratio between the core and the sheath is 3/1 to 1/5, and the single yarn fineness. A composite fiber having a value of 3.25 dtex is described. Patent Document 3 describes that it is a composite fiber having a polyamide as a core and a polyether ester amide copolymer as a core, and has excellent antistatic properties.

Japanese Unexamined Patent Publication No. 6-136618 International Publication No. 2014/10709 Japanese Unexamined Patent Publication No. 2017-57513

However, although the core-sheath composite fibers described in

Patent Documents

1 and 2 are excellent in hygroscopicity and antistatic performance, the raw yarn strength decreases as the fineness and single yarn fineness increase. When stretching is performed to ensure the strength of the raw yarn, fluffing of the raw yarn occurs frequently, and not only the process passability in the higher-order processing process is deteriorated, but also the product quality is deteriorated. The core-sheath composite yarn described in Patent Document 3 is excellent in antistatic performance, but has a low core ratio of a polyether ester amide copolymer that guarantees moisture absorption performance. If the core ratio is increased to ensure the moisture absorption performance, the problems are that the strength of the raw yarn is lowered, the fluff of the raw yarn is frequently generated, and the high-order passability and the product quality are deteriorated, as in Patent Document 1 and Patent Document 2.

Thin fabrics Lightweight, soft, and low air permeability are required, and the fineness of fibers and single yarns are becoming finer. It is an issue to provide a polyamide core-sheath composite fiber that suppresses the generation and has excellent high-order passability.

The present invention has the following configuration in order to solve the above problems.
(1) In a core-sheath type composite multifilament in which the sheath polymer is a polyamide and the core polymer is a polyether ester amide copolymer, the strength is 3.6 cN / dtex or more, and the cross-sectional uniform ratio of the core-sheath component in the fiber cross section. Polyamide core-sheath composite fiber having a d / R of 0.072 or less and an electric specific resistance value of 10 ⁷ to 10 ¹⁰ Ω · cm.
d: 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) Single thread fineness 0.8 to 2.0 dtex, core portion in the fiber cross section The polyamide core-sheath composite fiber according to (1), wherein the area ratio of the fibers is 20 to 40%.
(3) A fabric having at least a part of the polyamide core-sheath composite fiber according to (1) or (2).

According to the present invention, it is possible to provide a polyamide core-sheath composite fiber having hygroscopicity and antistatic properties, maintaining strength, suppressing the generation of fluff, and having excellent high-order passage.

The schematic diagram which shows the fiber cross-sectional shape of this invention. The vertical sectional view which shows an example of the discharge hole of the base for composite spinning used in this invention. The schematic diagram which shows a part of the arrangement of the lower introduction plate core component introduction hole and the sheath component introduction hole of the base for composite spinning used in this invention. The figure which shows one Embodiment of the manufacturing apparatus by the direct spinning and drawing method preferably used for the manufacturing method of the polyamide core-sheath composite fiber of this invention.

The polyamide core-sheath composite fiber of the present invention is a core-sheath composite fiber using a polyamide in the sheath portion and a polyether ester amide copolymer in the core portion.

As illustrated in FIG. 1, the polyamide core-sheath composite fiber of the present invention has a cross-sectional uniformity ratio (d / R) of 0.072 or less. The cross-sectional uniformity ratio referred to here is 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). ) Is measured and calculated, and is the average value obtained by measuring all single yarns. The closer the value is to 0, the more concentric it is, and the larger the value, the more eccentric it is. By setting the cross-sectional uniformity ratio (d / R) to such a range, the generation of single yarn fluff is suppressed and the 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 polyether ester amide copolymer is eccentric, and the sheath thickness can be biased in the sheath polyamide. Therefore, when an external force is applied to a portion where the sheath is thin, the single yarn is easily broken from there, and single yarn fluff occurs frequently, which not only deteriorates the higher-order passability but also tends to deteriorate the product quality.

The polyamide core-sheath composite fiber of the present invention has a strength of 3.6 cN / dtex or more. Within such a range, yarn breakage in the higher-order processing step is reduced and higher-order passability is improved. In addition, it has excellent product durability. When it is less than 3.6 cN / dtex, the yarn breakage in the higher-order processing step tends to increase and the higher-order passability tends to deteriorate. In addition, in clothing applications such as outer clothing applications and sports clothing applications, the level tends to be unbearable for actual use, and the product durability may be inferior. A more preferable range is 4.0 cN / dtex or more.

The polyamide core-sheath composite fiber of the present invention preferably has a core area ratio of 20% or more and 40% or less in the cross section of the fiber. It is more preferably 20% or more and 30% or less, and further preferably 25% or more and 30% or less. Within this range, the sheath portion easily absorbs a large amount of the limited moisture in the air, and the ratio of transmitting the absorbed moisture to the core portion increases. Further, since the area ratio of the core portion is small, the charged static electricity quickly transmits the absorbed core portion, so that excellent hygroscopicity and antistatic property are exhibited.

The polyamide core-sheath composite fiber of the present invention has an electrical resistivity value of ¹⁰⁷ to 10 ¹⁰ Ω · cm under the conditions of a temperature of 20 ° C. and a humidity of 40% RH. Antistatic property can be obtained by setting it within such a range. The electrical resistivity value of a general polyamide fiber is 10 ¹⁴ Ω · cm level. The static electricity depends on the amount of water in the air, and static electricity is unlikely to occur in a humid environment, and static electricity is likely to occur in a dry environment. In order to exhibit sufficient antistatic performance, sufficient antistatic performance can be exhibited if the specific resistance value is 10 ¹⁰ Ω · cm or less under the conditions of temperature 20 ° C. and humidity 40% RH. The level of the lower limit of the electrical resistivity that can be achieved by the present invention is about ¹⁰⁷ Ω · cm.

In the polyamide core-sheath composite fiber of the present invention, ΔMR is preferably 5.0% or more. Hygroscopicity can be obtained by setting it within such a range. In order to obtain good comfort when worn, it is required to have a function of controlling the humidity inside the garment. As an index of this humidity adjustment, the temperature and humidity inside clothes represented by 30 ° C x 90% RH and the outside air temperature humidity represented by 20 ° C x 65% RH when performing light to medium work or light to medium exercise. ΔMR, which is represented by the difference in moisture absorption rate in, is used. The larger the ΔMR, the higher the hygroscopic performance, indicating that the comfort when worn is good. If ΔMR is 5.0% or more, stuffiness and stickiness at the time of wearing can be suppressed, and it becomes possible to provide clothing having excellent comfort. The upper limit of ΔMR is about 17.0%.

The polyamide core-sheath composite fiber of the present invention can be arbitrarily set as long as it has a total fineness suitable for clothing, but it is preferably 8 to 155 dtex. In addition, the single yarn fineness can be arbitrarily set according to the product requirements, but the fineness of the fibers and the fineness of the single yarn are increasing in line with the demands for thin, lightweight, soft, and low air permeability of the woven fabric. It is preferably 0.8 to 2.0 dtex.

The polyamide core-sheath composite fiber of the present invention preferably has an elongation of 40% or more. More preferably, it is 42 to 65%. Within such a range, yarn breakage in the higher-order processing step is reduced and higher-order passability is improved.

The polyamide core-sheath composite fiber of the present invention uses polyamide for the sheath and a polyether ester amide copolymer for the core.

The polyether ester amide copolymer used for the core of the present invention is a block copolymer having an ether bond, an ester bond and an amide bond in the same molecular chain. More specifically, one or more polyamide components (A) selected from lactam, aminocarboxylic acid, diamine and dicarboxylic acid salts, and a polyether ester component consisting of dicarboxylic acid and poly (alkylene oxide) glycol (. It is a block copolymer polymer obtained by subjecting B) to a polycondensation reaction.

The polyamide component (A) includes lactams such as ε-caprolactam, dodecanolactam, and undecanolactam, ω-aminocarboxylic acids such as aminocaproic acid, 11-aminoundecanoic acid, and 12-aminododecanoic acid, nylon 66, and nylon. There are nylon salts of diamine-dicarboxylic acid which are precursors such as 610 and nylon 612, and a preferable polyamide-forming component is ε-caprolactam.

The polyether ester component (B) is composed of 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 dodecadic acid, terephthalic acid, isophthalic acid and 2,6-naphthalenedicarboxylic acid. Examples thereof include aromatic dicarboxylic acids such as, and alicyclic dicarboxylic acids such as 1,4-cyclohexanedicarboxylic acid, which can be used alone or in admixture of two or more. Preferred dicarboxylic acids are adipic acid, sebacic acid, dodecadic 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, poly (hexamethylene oxide) glycol and the like. Polyethylene glycol having good moisture absorption performance is preferable.

The number average molecular weight of the poly (alkylene oxide) glycol is preferably 300 to 5000, more preferably 500 to 4000. When the molecular weight is 300 or more, the fiber is less likely to be scattered outside the system during the polycondensation reaction, and the fiber has stable hygroscopicity and antistatic properties, which is preferable. Further, when it is 5000 or less, poly (alkylene oxide) glycol is uniformly dispersed in the polymer, and good hygroscopicity and antistatic property can be obtained, which is preferable.

The composition ratio of the polyether ester component (B) in the entire polyether ester amide copolymer is preferably 20 to 80% in terms of molar ratio. When it is 20% or more, good hygroscopicity and antistatic property can be obtained, which is preferable. Further, when it is 80% or less, good dyeing fastness, hygroscopicity and antistatic washing durability can be obtained, which is preferable.

The composition ratio of polyamide and poly (alkylene oxide) glycol is preferably 20% / 80% to 80% / 20% in terms of molar ratio. When the poly (alkylene oxide) glycol is 20% or more, good hygroscopicity and antistatic property can be obtained, which is preferable. Further, when the poly (alkylene oxide) glycol is 80% or less, good dyeing fastness, hygroscopicity and antistatic washing durability can be obtained, which is preferable.

As such a polyether ester amide copolymer, "MH1657" and "MV1074" manufactured by Arkema Co., Ltd. are commercially available.

The chip of the polyether ester amide copolymer polymer used for the core portion of the present invention preferably has an orthochlorophenol relative viscosity of 1.2 or more and 2.0 or less. When the relative viscosity of orthochlorophenol is 1.2 or more, an optimum stress is applied to the sheath portion at the time of spinning, crystallization of the polyamide in the sheath portion proceeds, and the strength is increased.

Poly (alkylene oxide) glycol undergoes a chain reaction in which radicals are generated from inside the molecule by heat application and radicals are generated by attacking adjacent atoms, and the temperature rises to over 200 degrees due to the heat of reaction. Further, the smaller the molecular weight of the poly (alkylene oxide) glycol is, the easier it is to apply heat to the molecular chain, so that radicals are likely to be generated and reaction heat tends to be generated easily.

Since the number average molecular weight of the poly (alkylene oxide) glycol contained in the polyether ester amide copolymer used in the present invention is relatively small, 300 to 5000, the heat deterioration of the polyether ester amide copolymer is caused by the above mechanism. Is easy to proceed, and it is very easy to cause hardening and brittleness of the raw yarn, deterioration of moisture absorption and antistatic properties, and the like.

Therefore, it is preferable to add a hindered phenolic antioxidant that captures radicals to the core polyether ester amide copolymer. More preferably, it is a half-hindered phenolic antioxidant. The amount of the hindered phenolic antioxidant to be added is preferably 1.0% by weight or more and 5.0% by weight or less with respect to the weight of the polyether ester amide copolymer in the core portion. More preferably, it is 2.0% by weight or more.

Both hindered phenolic antioxidants include, for example, pentaerythritol tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate] (IR1010), tris (4-tert-butyl-3-3). 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), N, N'-hexamethylenebis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propanamide] (IR1098).

In the case of both hindered phenolic antioxidants, the heat history during the spinning process (high temperature applied during polymer melting and heat set after stretching) and the heat history during the higher processing process (fabric dyeing, heat set, etc.) The thermal deterioration of the polyether ester amide copolymer progresses, and the amount of the active component of the antioxidant that captures the radicals remaining at the stage of the fabric and clothing is significantly reduced. Therefore, in order not to reduce the amount of the active ingredient of the antioxidant that captures the radicals remaining in the fabric and clothing, a hindered amine (HALS (Hindered Amine Embrittle Stabilizer)) stabilizer is used in combination to oxidize the hindered phenol. Thermal deterioration of the inhibitor can be suppressed, reaction heat and thermal deterioration can be suppressed, and hardening and embrittlement of the raw yarn, and deterioration of hygroscopicity and antistatic properties can be suppressed. HALS-based stabilizers include, for example,

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-piperidyl-1,6-hexamethylenediamine N-). 2,2,6,6-Tetramethyl-4-piperidyl) Polycondensate of butylamine (CHIMASTORB2020FDL), 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-diazadecan-1,10-diamine (CHIMASTORB119), poly [{6- (1,1,1) 3.3-Tetramethylbutyl) Amino-1,3,5-triazin-2,4diyl) ((2,2,6,6-tetramethyl-4-piperidyl) imino) Hexamethylene ((2,2,2) 6,6 Tetramethyl-4-piperidyl) imino] (CHIMASSORB944).

The half-hindered phenolic antioxidant is, for example, 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) propanoart] (Sumitomo Chemical Co., Ltd. "Sumilyzer" (registered trademark) AG80, ADEKA Co., Ltd. "ADEKA STAB" (Registered Trademark) AO-80), 1,3,5-Tris [[4- (1,1-dimethylethyl) -3-hydroxy-2,6-dimethylphenyl] methyl] -1,3,4-triazine -2,4,6 (1H, 3H, 5H) -trion (Cyanox1790 manufactured by Solvay) can be mentioned.

Compared with both hindard phenolic antioxidants, the half-hindered phenolic antioxidant has the amount of the active component of the antioxidant in the heat history during the spinning process and the thermal history during the higher processing process. The drop is very small. Therefore, the reaction heat and thermal deterioration can be suppressed by using the half-hindered phenol-based antioxidant alone without using the HALS-based stabilizer in combination as in the case of both hindered phenol-based antioxidants. It is possible to suppress hardening, embrittlement, deterioration of hygroscopicity and antistatic property. In addition, since the decomposition product of half-hindered phenol has little coloring, yellowing can be suppressed.

It is also possible to use other phosphorus-based stabilizers in combination with the polyether ester amide copolymer in the core. In addition, various other additives such as matting agents, flame retardants, ultraviolet absorbers, infrared absorbers, crystal nucleating agents, bright whitening agents, antistatic agents, hygroscopic polymers, carbon, etc. are all added. The content may be 5% by weight or less with respect to the polyether ester amide copolymer, and may be copolymerized or mixed as required.

The ratio of the core portion is preferably 20% by weight to 40% by weight with respect to the entire composite fiber. More preferably, it is 20% by weight to 30% by weight, and more preferably 25% by weight to 30% by weight. The higher the ratio of the core portion, the higher the hygroscopicity and antistatic property, but the lower the strength. On the other hand, the lower the ratio of the core portion, the higher the strength, but the lower the hygroscopicity and the antistatic property. Within such a range, hygroscopicity and antistatic property are exhibited, and appropriate stretching can be applied to the polyamide of the sheath portion, so that the strength can be increased.

The polyamide used for the sheath portion of the present invention includes nylon 6, nylon 66, nylon 46, nylon 9, nylon 610, nylon 11, nylon 12, nylon 612 and the like, or compounds having amide-forming functional groups thereof, for example, lauro. Examples thereof include copolymerized polyamides containing copolymerizing components such as lactam, sebacic acid, terephthalic acid, isophthalic acid, and 5-sodium sulfoisophthalic acid. Among them, nylon 6 and 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 deterioration of the polyether ester amide copolymer during melt spinning. , Preferable from the viewpoint of yarn-making property. Particularly preferred is nylon 6, which is highly dyeable.

Various additives such as matting agents, flame retardants, antioxidants, ultraviolet absorbers, infrared absorbers, crystal nucleating agents, bright whitening agents, antistatic agents, and hygroscopic polymers are used in the polyamide of the sheath. , Carbon and the like may be copolymerized or mixed as necessary with a total additive content of 5% by weight or less with respect to the polyether ester amide copolymer.

The polyamide chip used for the sheath portion of the present invention preferably has a sulfuric acid relative viscosity of 2.3 or more and 3.3 or less. Within such a range, appropriate stretching can be applied to the polyamide of the sheath portion, and the strength can be increased.

The melt viscosity of the polyether ester amide 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 of 900 to 1500 poise, and the difference in melt viscosity is also large. Therefore, it is preferable to select a combination of a polyether ester amide copolymer and a polyamide having a melt viscosity ratio of 3.0 or less at the spinning temperature. Within such a range, the stress applied in the longitudinal direction of the yarn during thinning / stretching after being discharged from the mouthpiece at the time of spinning is not biased to the sheath component, and the cross-sectional uniform ratio (d / R) can be reduced. There is a tendency. If it exceeds 3.0, the stress applied in the longitudinal direction of the yarn during thinning / stretching is biased toward the sheath component, and the cross-sectional uniformity ratio becomes large. The melt viscosity referred to here refers to the melt viscosity of a chip-shaped polymer that can be measured by a capillary leometer with a moisture content of 200 ppm or less by a vacuum dryer, and means the melt viscosity at the same shear rate at the spinning temperature. do.

Further, since the melting point of the polyether ester amide copolymer is lower than the melting point of the polyamide, the difference in melting point is 30 ° C. or less from the viewpoint of suppressing the thermal deterioration of the polyether ester amide copolymer during melt spinning and the yarn-making property. It is preferable to select a polyether ester amide copolymer and a polyamide, respectively.

In the spinning step, the temperature of the molten part of the core polymer is preferably 235 ° C. or higher and 260 ° C. or lower. When the temperature of the melted portion of the core polymer is 235 ° C. or higher, the melt viscosity of the polyether ester amide copolymer in the core portion is suitable for melt spinning, which is preferable. It is preferable because it can suppress thermal decomposition due to an increase in temperature of the amide copolymer.

The temperature of the molten part of the sheath polymer is preferably 240 ° C. or higher and 285 ° C. or lower. When the temperature of the melted portion of the sheathed polymer is 240 ° C. or higher, the polyamide in the sheath portion has a melt viscosity suitable for melt spinning, which is preferable. When the temperature is 285 ° C. or lower, thermal decomposition due to an increase in the temperature of the polyether ester amide copolymer in the core can be suppressed, which is preferable.

The temperature of the molten part at the confluence is preferably 235 ° C or higher and 270 ° C or lower. When the temperature is 235 ° C. or higher, the polyamide and the polyether ester amide copolymer have a melt viscosity suitable for melt spinning, which is preferable. When the temperature is 270 ° C. or lower, decomposition of the polyether ester amide copolymer due to thermal decomposition can be suppressed, which is preferable.

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 design a base until the core-sheath components merge according to the melt viscosities of the core component and the sheath component polymer. It needs to be optimized.

FIG. 2 is a vertical sectional view showing an example of a discharge hole of a base for composite spinning used for the core-sheath composite fiber of the present invention. In FIG. 2, the members are laminated in the order of the upper introduction plate 1, the lower introduction plate 2, and the base plate 3 from the top to form a composite spinning base. Hereinafter, in the composite spinneret illustrated in FIGS. 2 and 3, the flow of the polymer from the upstream to the downstream of the composite spinneret will be described.

The core component polymer flows into the core component introduction hole 1-1 of the upper introduction plate, is weighed by the core component throttle portion 1-2 drilled at the lower end, and then the core component introduction hole 2-1 of the lower introduction plate. Is discharged to. Similarly, the core component polymer that has flowed into the core component introduction hole 2-1 of the lower introduction plate is weighed by the core component throttle portion 2-2 bored at the lower end, and then the merging pool 3-1 of the base plate 3 is used. Inflow to.

The sheath component polymer flows into the sheath component introduction holes 1-3 of the upper introduction plate and is discharged to the sheath component pool 2-3 of the lower introduction plate. On the lower surface of the sheath component pool 2-3 of the lower introduction plate for storing the polymer flowing in from each sheath component introduction hole of the upper introduction plate, a sheath component introduction hole 2-4 for flowing the polymer downstream is bored. .. The sheath component polymer that has flowed into the sheath component pool 2-3 is weighed by the sheath component squeezing portion 2-5 formed at the lower end, and then flows into the confluence pool 3-1 of the base plate 3.

Each of the core polymer and the sheath polymer flows into the confluence pool 3-1 of the base plate 3, forms a core-sheath composite form, and flows into the discharge hole 3-3, and the discharge hole throttle portion 3 drilled at the lower end. After being weighed by -2, it is discharged.

In order to maintain the measurable property of the core component polymer, it is necessary to weigh once with the upper introduction plate 1 and then with the lower introduction plate 2 for a total of two times. Since the core component polymer has a low viscosity, the polymer flow can be controlled and the core component can be centered by measuring the amount of the polymer twice. Further, by weighing with the upper introduction plate 1, the pressure of the core component polymer is increased, the sealing property between the upper introduction plate 1 and the lower introduction plate 2 is improved, and the polymer leakage is prevented.

In order to maintain the meterability of the sheath component polymer, it is necessary to set the relationship between the pore length (L) and the pore diameter (D) of the sheath component throttle portion 2-5 of the lower introduction plate 2 and the L / D to 1.0 to 2.5. There is. By setting the L / D to 1.0 or more, the measurable property can be stabilized and the cross-sectional uniformity ratio can be set within such a range. If the hole diameter is large and the hole length is small, the measurable property is lowered and eccentricity is likely to occur. If the L / D is less than 1.0, the cross-sectional uniformity ratio (d / R) may exceed 7.2. If the pore diameter (D) is made too small in order to improve the measurable property, the polymer foreign matter is likely to be clogged, and a cross-sectional defect is likely to occur. Further, if the hole length (L) is made too large, the back pressure of the base becomes large, the distortion of the base becomes large, and the pump cannot withstand the polymer pressure, so that polymer leakage is likely to occur. By setting the L / D to 2.5 or less, a uniform cross section can be obtained and stable silk reeling becomes possible. More preferably, it is 1.5 to 2.5.

As shown in FIG. 3, in the lower introduction plate 2, it is necessary to drill three core component introduction holes 2-1 and three sheath component introduction holes 2-4 around them. By setting the number of holes to three, it is possible to uniformly fill the merging pool 3-1 of the base plate 3 with the sheath polymer, and the cross-sectional uniformity ratio can be set within such a range. When the number of holes is 2 or less, the packing of the polymer in the confluence pool 3-1 tends to be biased, and the cross-sectional uniformity ratio (d / R) may exceed 7.2. When the number of holes is 4 or more, it is necessary to design the hole diameter (D) to be small or the hole length (L) to be large in order to maintain the measurable property, and clogging or leakage is likely to occur and the silk reeling stability is improved. It is lowered and a cross-sectional defect is likely to occur.

Further, it is preferable that the three sheath component introduction holes 2-4 formed have the same discharge amount per hole in order to make the cross-sectional uniformity ratio (d / R) smaller, and therefore the holes are point-symmetrical. It is preferable to drill at points, that is, on the same orbit.

FIG. 4 shows one embodiment of a manufacturing apparatus by a direct spinning and drawing method preferably used in the method for manufacturing a polyamide core-sheath composite fiber of the present invention.

Polyamide (sheath part) and polyether ester amide copolymer (core part) are melted separately, weighed and transported by a gear pump, and discharged from the above-mentioned composite spinneret 4 to form each filament. Each filament discharged from the composite spinneret 4 in this way is cooled and solidified to room temperature by blowing cooling air with a yarn cooling device 5 such as a chimney. After that, the oil is applied by the lubrication device 6, and each filament is focused to form a multifilament, entangled by the fluid entanglement nozzle device 7, passes through the take-up roller 8 and the draw roller 9, and at that time, the take-up roller 8 and the draw roller 9 are used. Stretching according to the ratio of peripheral speeds of. Further, the yarn is heat-treated by heating the drawing roller 9 and wound by a winding device.

In the production of the polyamide core-sheath composite fiber of the present invention, the cooling device 5 is 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 center side, or an annular cooling device that blows cooling rectifying air from the center side. It can be manufactured by any method such as an annular cooling device that blows cooling rectified air toward the outer periphery. 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 to suppress yarn sway and fiber spots. It is preferable in terms of points, and 169 to 189 mm is more preferable. Regarding the cooling air velocity blown from the cooling air blowing surface, the fineness spot and strength should be in the range of 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 blowing portion. It is preferable from the viewpoint of.

In the production of the polyamide core-sheath composite fiber of the present invention, the polymer discharged from the spinneret is blown with cooling air by a cooling device to solidify the yarn, and spinning with an accompanying flow from the solidification position to the refueling position. It is stretched by tension and then mechanically stretched between the take-up roller and the stretching roller. The core-sheath composite fiber of the present invention is mechanically stretched to promote the orientation crystallization of the sheath polymer and increase the strength, and the spinning tension is applied to suppress the orientation crystallization of the core polymer and enhance the moisture absorption performance. The point is to make it smaller. Therefore, the position of the refueling device 6, that is, the vertical distance Lg (hereinafter referred to as the refueling position Lg) from the lower surface of the spinneret in FIG. 4 to the refueling nozzle position of the refueling device 6 is the single yarn fineness and the filament from the cooling device. Although it depends on the cooling efficiency, it is preferably 800 to 1500 mm, more preferably 1000 to 1300 mm. When the refueling position is less than 800 mm, the filament does not cool sufficiently and the structure is unstable, and the filament comes into contact with the refueling guide and is damaged. Therefore, not only the single yarn strength of the filament is lowered but also the fluff tends to increase. .. In particular, the thinner the sheath thickness, the more easily the sheath is damaged, such as the fineness of the single yarn being thin, the core ratio being high, and the cross-sectional uniformity ratio being high, and the above phenomenon may appear remarkably. If the refueling position exceeds 1500 mm, the spinning tension becomes high, so that the orientation and crystallization of the core polymer progresses and the hygroscopic performance deteriorates. be.

In the drawing step of manufacturing the polyamide core-sheath composite fiber of the present invention, the product of the speed of the yarn taken up by the take-up roller (spinning speed) and the draw ratio, which is the value of the peripheral speed ratio between the take-up roller and the draw roller, is It is preferable to set the spinning conditions so as to be 3300 or more and 4500 or less. More preferably, it is 4000 or less. This numerical value represents the total stretching amount of the polymer discharged from the mouthpiece, which is stretched from the mouthpiece discharge line speed to the peripheral speed of the take-up roller, and further from the peripheral speed of the take-up roller to the peripheral speed of the drawing roller. Within such a range, it is possible to add appropriate stretching to the polyamide of the sheath portion. When it is 3300 or more, crystallization of the polyamide in the sheath portion proceeds, and the strength of the yarn is improved, which is preferable. When it is 4500 or less, crystallization of the polyamide in the sheath portion proceeds moderately, and yarn breakage and fluffing are less likely to occur during silk reeling, which is preferable.

With the demand for light weight, softness, and low air permeability of woven fabrics, the fineness of fibers and the fineness of single yarns are increasing. The single yarn strength of the fiber is reduced. Further, the higher the area ratio of the core portion and the finer the fineness of the single yarn, the thinner the sheath thickness of the sheathed polyamide, which is responsible for the strength of the single yarn, and the lower the strength of the single yarn.

On the other hand, in the case of a polyamide single component fiber, in order to secure the single yarn strength, it is generally practiced to appropriately adjust the draw ratio within a range in which the elongation required for higher-order processing can be maintained. In the polyamide core-sheath composite fiber, the thinner the sheath, the higher the draw ratio, the easier it is for the sheath to burst, the more single yarn fluff occurs, and the higher the passability deteriorates. , Product quality also deteriorates. Therefore, the polyamide core-sheath composite fiber of the present invention needs to have strength and a cross-sectional uniformity ratio within such a range. For that purpose, it is necessary to set the manufacturing conditions for making the sheath thickness uniform while ensuring the strength of the sheathed polyamide.

Although it depends on the core-sheath composite ratio, single yarn fineness, and the cooling efficiency of the filament from the cooling device, the lubrication position is 800 to 1500 mm from the base surface, and the product of the spinning speed and the draw ratio is 3300 or more and 4500 or less. Optimal stress is applied to the sheathed polyamide during spinning, and appropriate stretching can be applied, crystallization of the sheathed polyamide progresses, and the strength can be controlled within such a range.

Discharge stability is ensured by adopting a polyamide with a melt viscosity of 900 to 1500 poise, a flow balance (melt viscosity ratio) of a polyether ester amide copolymer having a melt viscosity of 400 to 600 poise, and a composite spinneret suitable for the flow balance. , The cross-sectional uniformity ratio can be controlled within such a range.

By adopting such a composite spinneret and silk reeling conditions, the strength is 3.6 cN / dtex or more, and the uniform cross-sectional ratio d / R of the core-sheath component of all filaments is 0.072 or less. An excellent core-sheath composite fiber can be obtained. In particular, when the sheath thickness is relatively thin, the single yarn fineness is 2.0 dtex or less, and the area ratio of the core portion is 20% or more, the effect is remarkably exhibited.

The core-sheath composite fiber of the present invention has excellent hygroscopicity and antistatic properties, and can be preferably used for clothing. As the cloth form, a woven fabric, a knitted fabric, or the like can be selected according to the purpose. Further, as clothing, various clothing products such as innerwear and sportswear can be used.

Hereinafter, the present invention will be described in more detail with reference to examples. The method for measuring the characteristic value in the examples is as follows.

(1) Relative Sulfuric Acid Viscosity 0.25 g of a chip sample was dissolved in 100 ml of sulfuric acid having a concentration of 98 wt% so as to be 1 g, and the flow time (T1) at 25 ° C. was measured using an Ostwald viscometer. Subsequently, the flow time (T2) of sulfuric acid having a concentration of 98 wt% was measured. The ratio of T1 to T2, that is, T1 / T2, was defined as the relative viscosity of sulfuric acid.

(2) Orthochlorophenol relative viscosity (OCP relative viscosity)
0.5 g of the chip sample was dissolved in 100 ml of orthochlorophenol so as to be 1 g, and the flow time (T1) at 25 ° C. was measured using an Ostwald type viscometer. Subsequently, the flow time (T2) of orthochlorophenol was measured. The ratio of T1 to T2, that is, T1 / T2, was defined as the relative viscosity of sulfuric acid.

(3) Melt Viscosity The chip sample was measured with a water content of 200 ppm or less by a vacuum dryer, and the strain rate was changed stepwise by Capillograph 1B manufactured by Toyo Seiki Co., Ltd. to measure the melt viscosity. The measurement temperature was the spinning temperature, and the measurement was performed in a nitrogen atmosphere with 5 minutes from the time the sample was put into the heating furnace to the start of the measurement.

(4) Fineness, single yarn fineness Set the fiber sample in a 1.125 m / circumference measuring instrument, rotate it 200 times to make a loop-shaped skein, and dry it with a hot air dryer (105 ± 2 ° C × 60). After minutes), the skein mass was weighed with a balance, and the fineness was calculated from the value multiplied by the official moisture content. The official moisture content of the core-sheath composite fiber was 4.5%.

(5) Strength / elongation The fiber sample is subjected to "TENSILON" (registered trademark) manufactured by Orientec Co., Ltd. under the constant speed elongation conditions shown in JIS L1013 (chemical fiber filament yarn test method, 2010) with UCT-100. It was measured. Elongation was determined from the elongation of the point showing the maximum strength in the tensile strength-elongation curve. The strength was defined as the value obtained by dividing the maximum strength by the fineness. The measurement was performed 10 times, and the average value was taken as strength and elongation.

(6) Cross-section uniformity ratio, cross-section uniformity A. Taking a cross-sectional photograph A packaging agent consisting of paraffin, stearic acid, and ethyl cellulose was dissolved, the fibers were introduced and then solidified by leaving at room temperature, and the raw yarn in the packaging agent was cut in the cross-sectional direction. The cross section of the fiber was photographed with a CCD camera (CS5270) manufactured by Mitsubishi Electric, and printed out at 1500 times with a color video processor (SCT-CP710) manufactured by Mitsubishi Electric.

B. Measurement of cross-sectional uniformity ratio As shown in FIG. 1, 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 inscribed circle of the sheath component. The diameter (R) is measured and calculated. The cross sections of all the filaments of the core-sheath composite yarn were measured, and the average value was taken as the cross-section uniform ratio.

C. Cross-sectional uniformity The cross-sections of all filaments of the core-sheath composite yarn were visually observed and evaluated according to the following criteria.
A: Circular shape of sheath component and core component, uniform cross-section without variation in size C: Circular shape and size of sheath component and core component are uneven and cross-sectional defect is poor.

(7) Number of fluffs The fiber sample is rewound at a speed of 500 m / min, and a laser fluff detector is installed at a location 2 mm away from the rewound yarn to reduce the total number of detected defects to 100,000 m. Converted and displayed. 2 pieces / 100,000 m or less were accepted.

(8) Specific resistance value The fiber sample is sufficiently scoured in a weak alkaline aqueous solution of 0.2% by weight of an anionic surfactant to remove oils and the like, then rinsed thoroughly and dried. Then, the sample was aligned with a fiber bundle having a length (L) of 5 cm and a total fineness (D) of 2200 dtex (2000 denier), and left for 2 days under the conditions of a temperature of 20 ° C. and a humidity of 40% RH. After that, the resistance of the sample is measured at an applied voltage of 500 V by a vibration capacitance type micropotential measuring device, and calculated by the following equation.
ρ = (R × 0.9D) / (9 × 10 ⁵ × L × d × 10 ⁴ )
ρ: Volume resistivity (Ω · cm), R: Resistance (Ω), D: Fineness (dtex), L: Sample length (cm), d: Sample density (g / m ² ).

(9) ΔMR
Weigh 1 to 2 g of the fiber sample (or textile) in a weighing bottle, keep it at 110 ° C for 2 hours, dry it and measure the weight (W0), then keep the target substance at 20 ° C and 65% relative humidity for 24 hours. Then weigh (W65). Then, this is held at 30 ° C. and a relative humidity of 90% for 24 hours, and then the weight is measured (W90). Then, it was calculated according to the following formula.
MR65 = [(W65-W0) / W0] x 100% ... (1)
MR90 = [(W90-W0) / W0] x 100% ... (2)
ΔMR = MR90-MR65 ・・・・・・・・・・・・ (3).

(10) High-order passability The following criteria are used to determine the number of stops due to thread breakage of the loom when weaving a plain woven fabric with 10 loom (1000 m / loom) at a loom rotation speed of 750 rpm and a warp length of 1620 mm on a water jet room loom. Evaluated in.
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, B were regarded as passing the process.

[Example 1]
(Manufacturing of polyamide core sheath composite fiber)
As a polyether ester amide copolymer, a polyether ester amide copolymer (alchema) having a polyamide component of nylon 6, a polyethylene glycol having a molecular weight of 1500, and a molar ratio of nylon 6 to polyethylene glycol of 24%: 76%. A chip manufactured by MH1657, orthochlorophenol relative viscosity: 1.69, melting point 200 ° C., melt viscosity 450 pose (260 ° C.)) was used for the core. In addition, a half-hindered phenol-based antioxidant: 2,2'-dimethyl-2,2'-(2,4,8,10) was added to the polyether ester amide copolymer at a high concentration in advance using a twin-screw extruder. -Tetraoxaspiro [5.5] undecane-3,9-diyl) dipropane-1,1'-diyl-bis [3- (3-tert-butyl-4-hydroxy-5-methylphenyl) propanoate] (ADEKA) A master chip containing Adecastab AO-80) manufactured by Adecaster Co., Ltd. and a polyether ester amide copolymer chip were blended and adjusted so as to be 3.0% by weight based on the weight of the core portion.

As the polyamide, nylon 6 chips containing no titanium oxide having a relative sulfuric acid viscosity of 2.73, a melting point of 215 ° C., and a melt viscosity of 1250 pose were used for the sheath.

The above-mentioned polyether ester amide copolymer is used as a core, nylon 6 is used as a sheath, and the core melts at a temperature of 240 ° C. and a sheath melts at a temperature of 270 ° C. The hole length (L) of the sheath component squeezing portion 2-5 of the lower introduction plate 2 for measuring the sheath component, the number of holes 2-4 for the sheath component introduction holes 2-4 is three, and the core is measured twice. The core / sheath ratio (% by weight) was 30/70 from the concentric core-sheath composite base having a hole diameter (D) of 0.2 mm and a number of discharge holes of 24 in the base plate 3.

Using the composite spinning machine illustrated in FIG. 4, the yarn is cooled and solidified to room temperature by passing it through a yarn cooling device with a cooling start distance Ls 100 mm, an air temperature of 18 ° C., and a wind speed of 30 m / min. After that, the non-hydrous oil agent is applied at the oil supply position Lg from the base surface at a position of 1300 mm, and each filament is focused to form a multifilament. Entanglement is applied, the peripheral speed of the take-up roller, which is the first roll, is 3255 m / min, the peripheral speed of the stretching roller, which is the second roll, is 4167 m / min, the stretching ratio is 1.28 times, and the stretching roller is heated by 150 ° C. The set was performed, and the relaxation rate was 4.0% and the winding speed was 4000 m / min to obtain a core-sheath composite yarn of 22dtex12 filament and two threads. The physical characteristics of the raw yarn are as shown in Table 1.

(Manufacturing of textiles)
The core-sheath composite fiber was used for the warp and weft, and the warp density was set to 188 lines / 2.54 cm and the weft density was set to 155 lines / 2.54 cm, and weaving was performed with a plain weave.

The obtained raw material is scoured by an open soaper with a solution containing 2 g of caustic soda (NaOH) per liter according to a conventional method, dried at 120 ° C. in a cylinder dryer, and then preset at 170 ° C., liquid flow. Dyeing treatment with acid dye (Nylosan Blue-GFL 167% (manufactured by Sandos) 1.0% owf at 98 ° C for 60 minutes by dyeing machine, synthetic tannin (nylon fix 501 manufactured by Senka) 3 g / l 80 It was fixed at ° C for 20 minutes, dried (120 ° C), and finished set (175 ° C). After that, calendar processing (processing conditions: cylinder processing, heating roll surface temperature 180 ° C, heating roll load 147 kN, cloth running speed 20 m). / Minute) was applied once on both sides of the woven fabric to obtain a woven fabric having a warp density of 210 lines / 2.54 cm and a weft density of 160 lines / 2.54 cm. The results of evaluation of the obtained woven fabric are shown in Table 1.

[Examples 2 to 3, Comparative Examples 1 to 2]
In the sheath component squeezing portion 2-5 of the lower introduction plate 2 for measuring the sheath component, the core-sheath composite yarn was spun in the same manner as in Example 1 except that the L / D was changed as shown in Table 1. Obtained and made a woven fabric. The results obtained are shown in Table 1.

[Comparative Examples 3 to 4]
In the lower introduction plate 2, spinning is performed in the same manner as in Example 1 except that the core component introduction hole 2-1 and the sheath component introduction hole 2-4 are formed around the spinneret with the number of holes 2-4 changed as shown in Table 1. , A core-sheath composite yarn was obtained, and a woven fabric was prepared. The results obtained are shown in Table 1.

[Comparative Example 5]
Examples except for a spinneret (not shown) in which the L / D of the sheath component squeezing portion for measuring the sheath component is changed as shown in Table 1, with a two-sheet configuration, one core weighing, and three holes. The yarn was spun in the same manner as in No. 1 to obtain a core-sheath composite yarn, and a woven fabric was prepared. The results obtained are shown in Table 1.

In Examples 1 to 3 of the present invention, the generation of fluff was suppressed and the high-order passage was excellent.
Comparative Example 1 in which the L / D of the sheath component squeezed portion of the lower introduction plate for measuring the sheath component is small, Comparative Example 3 in which the number of holes is small, and Comparative Example 5 in which the core is measured once are polyether ester amide copolymers. The weighability of the polymer was low, the cross-sectional uniformity ratio was high, and bias was observed, and the fluff and higher passability were inferior. Further, Comparative Example 2 having a large L / D and Comparative Example 4 having a large number of holes were lacking in cross-sectional uniformity, and the yarn-making stability was poor.

[Examples 4 to 5, Comparative Examples 6 to 7]
The refueling position Lg was changed as shown in Table 2, and the spinning speed and the draw ratio were adjusted as shown in Table 2. The spinning was performed in the same manner as in Example 1 to obtain a core-sheath composite yarn, and a woven fabric was prepared. The results obtained are shown in Table 2.

[Examples 6 to 8]
A woven fabric was prepared by spinning in the same manner as in Example 1 except that the core ratio (% by weight) was changed as shown in Table 2 and the spinning speed and the draw ratio were adjusted as shown in Table 2. The results obtained are shown in Table 2.

Examples 4 to 8 of the present invention had hygroscopicity and antistatic properties, maintained strength, suppressed the generation of fluff, and were excellent in high-order passage.

In Comparative Example 6 in which the lubrication position Lg was long from the bottom of the mouthpiece, appropriate stretching could not be applied to the sheathed polyamide, the strength decreased, the fluff increased, and the high-order passage was inferior. Further, in Comparative Example 7 in which the lubrication position Lg is short from the bottom of the mouthpiece, the filament is not sufficiently cooled and the structure is unstable, and the filament is in contact with the lubrication guide and is damaged. Therefore, the strength is slightly reduced and the fluff is increased. The result was inferior in high-order passage. In Example 8 having a high core ratio, the sheath was thinner, the strength was slightly reduced, and the fluff was slightly increased as compared with Example 1, but the higher passability was at the acceptable level.

[Examples 9 to 10]
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 lubrication position were adjusted as shown in Table 3, to obtain a core-sheath composite yarn. , Created a woven fabric. The results obtained are shown in Table 3.

[Example 11]
As the polyamide, nylon 6 chips containing 1.8% of titanium oxide having a relative sulfuric acid viscosity of 2.63, a melting point of 215 ° C. and a melt viscosity of 1000 poise were used for the sheath, and the spinning speed and the draw ratio were adjusted as shown in Table 3. Except for the above, the yarn was spun in the same manner as in Example 1 to obtain a core-sheath composite yarn, and a woven fabric was prepared. The results obtained are shown in Table 3.

1: Upper introduction plate 1-1: Core component introduction hole 1-2: Core component drawing part 1-3: Sheath component introduction hole 2: Lower introduction plate 2-1: Core component introduction hole 2-2: Core component drawing part 2-3: Sheath component pool 2-4: Sheath component introduction hole 2-5: Sheath component throttle part 3: Base plate 3-1: Confluence pool 3-2: Discharge hole throttle part 3-3: Discharge hole 4: Spinning Base 5: Cooling device 6: Refueling device 7: Fluid entanglement nozzle device 8: Take-up roller 9: Stretching roller 10: Winding device Lg: Refueling position Ls: Cooling start distance

Claims

In a core-sheath type composite multifilament in which the sheath polymer is polyamide and the core polymer is a polyether ester amide copolymer, the strength is 3.6 cN / dtex or more, and the cross-sectional uniform ratio d / R of the core-sheath component in the fiber cross section. Polyamide core-sheath composite fiber having an electric ratio of 0.072 or less and an electric specific resistance value of 10 7 to 10 10 Ω · cm.
d: Distance between the center of the inscribed circle of the core component and the center of the inscribed circle of the sheath component R: The diameter of the inscribed circle of the sheath component
The polyamide core-sheath composite fiber according to claim 1, wherein the single yarn fineness is 0.8 to 2.0 dtex, and the area ratio of the core portion in the cross section of the fiber is 20 to 40%.
A fabric having at least a part of the polyamide core-sheath composite fiber according to claim 1 or 2.