JP7074062B2 - Polyurethane / nylon 6 eccentric core sheath composite fiber - Google Patents

Description

The present invention relates to an eccentric core sheath composite fiber composed of polyurethane and nylon 6.

The self-crimping composite fiber, which is an eccentric composite of polyurethane and polyamide, has excellent crimping properties and can be a knitted fabric with soft stretchability and transparency, so it is highly suitable as a material for high-class stockings. It has been evaluated.

On the other hand, stockings using self-crimpable composite fibers have a problem that knitted fabric defects such as streaks and unevenness are likely to occur as the crimping characteristics of the fibers vary. In order not to cause knitted fabric defects such as streaks and unevenness, all self-crimping composite fibers are subjected to crimping characteristic inspection and knitting inspection and sorted and used. Therefore, there is a demand for a self-crimping composite fiber that has a small variation in the crimping characteristics of the fiber and is less likely to cause streaks or unevenness when the stocking is manufactured.

From the past, self-crimping composite fibers made by eccentrically composited polyurethane and polyamide have been actively studied. For example, Patent Document 1 uses a polyurethane composition containing at least 10% by weight of a polycarbonate ester-based polyurethane as a copolymerization component or a mixed component and having a dimethylacetamide relative viscosity of 1.80 to 3.00, and is composited. Self-crimping composite fibers have been described that improve stability during spinning and spinning and reduce variations between polymers of polyurethane elastics.

Further, in Patent Document 2, a polyurethane elastic body obtained by adding and mixing 5 to 20% by weight of a polyisocyanate compound having a molecular weight of 400 or more to polyamide and a molten thermoplastic polyurethane is bonded to each other with a bonding weight ratio of 80/20 to 20/80. It is a filament obtained by composite melt spinning so that it is eccentrically arranged and bonded in the cross section of a single filament at a ratio, then stretched and then relaxed and heat-treated. Is 80% by weight or less, the linear shrinkage rate of the filament is about 10%, the crimp development rate is 68% or more, the peel resistance of the polyamide and polyurethane elastic body is excellent, and after relaxation heat treatment. However, a self-crimping composite filament having sufficient crimping ability and stretch recovery property of crimping has been described.

Japanese Patent Application Laid-Open No. 2-80616 Japan Special Fairness 7-91693 Gazette

However, although the composite fiber described in Patent Document 1 is excellent in melt-spinning stability and silk-reeling property and can industrially produce a composite fiber having stable physical properties, there is no suggestion regarding variation in crimping characteristics. Still, there remains the problem that knitted fabric defects such as streaks and unevenness are likely to occur as the crimping variation remains.

Further, although the composite fiber described in Patent Document 2 has excellent peeling resistance between polyamide and polyurethane elastic body, has crimp-developing power and crimp stretch recovery property, there is no suggestion about variation in crimp characteristics. Still, there remains the problem that knitted fabric defects such as streaks and unevenness are likely to occur as the crimping variation remains.

Therefore, an object of the present invention is to provide a polyurethane / nylon 6 eccentric core-sheath composite fiber that overcomes the problems of the prior art and can obtain excellent soft stretch woven knitted fabric and stocking quality.

The present invention has the following configuration in order to solve the above problems.
(1) An eccentric core-sheath composite fiber having a core component of thermoplastic polyurethane and a sheath component of nylon 6 is characterized in that the cross-sectional curvature rate is 15% or less and the cross-sectional curvature rate CV value is 0.40 or less. Core-sheath composite fiber.
(2) The eccentric core sheath composite fiber according to (1), which has an expansion / contraction rate of 90% or more.
(3) A woven or knitted fabric having at least a part of the core-sheath composite fiber according to (1) or (2).
(4) Stockings having the core-sheath composite fiber according to (1) or (2) in at least a part of the leg portion.

According to the present invention, it is possible to provide a polyurethane / nylon 6 eccentric core sheath composite fiber capable of obtaining excellent soft stretch woven knitted fabric or stocking quality.

1 (a) and 1 (b) are model views illustrating a cross section of the eccentric core sheath composite fiber of the present invention. FIG. 2 is a model diagram for measuring the cross-sectional curvature of the eccentric core sheath composite fiber of the present invention.

The eccentric core-sheath composite fiber of the present invention is a latent crimped yarn in which coiled crimp is developed in a woven or knitted fabric or stocking manufacturing process (hereinafter referred to as a higher-order process). In particular, knitted fabrics such as stockings are knitted by supplying a plurality of yarns to a knitting machine, so if yarns having different latent crimping properties are supplied and knitted, there are drawbacks such as streaks and unevenness immediately after knitting. Even if it is not found, shrinkage variation occurs in the higher-order process, and defects such as streaks and unevenness occur.

The present inventors develop stable crimping by controlling the interface in the cross section of the eccentric core sheath fiber before the onset of crimping, suppress the crimping variation, and have excellent quality soft without streaks or unevenness. We have found that stretch woven knits and stockings are available.

The eccentric core-sheath composite fiber of the present invention has a core component of thermoplastic polyurethane and a sheath component of nylon 6.

In the present invention, the eccentric core sheath means that the position of the center of gravity of the thermoplastic polyurethane in the core portion is different from the center of the composite fiber cross section in the composite fiber cross section. Specifically, it refers to a form as shown in FIGS. 1 (a) and 1 (b). By adopting an eccentric core sheath structure, uniform coil-like crimping is developed. Further, due to the difference in viscosity between the core component thermoplastic polyurethane and the sheath component nylon 6, the interface thereof is curved with the thermoplastic polyurethane slightly convex. The core component may be partially exposed as shown in FIG. 1 (b), but it is more preferable that the sheath component nylon 6 includes the thermoplastic polyurethane which is the core component as shown in FIG. 1 (a).

Further, the minimum thickness of nylon 6 as a sheath component covering the core component is preferably 0.01 to 0.1 times the diameter of the composite fiber. More preferably, it is 0.02 to 0.08 times. Within this range, sufficient crimp-developing power and stretching performance can be obtained. The composite ratio of the eccentric core sheath composite fiber is preferably 80/20 to 20/80. When the polyurethane ratio is larger than the composite ratio of 80/20 and the nylon ratio is small, the dyeability and durability are deteriorated, and the practicality is inferior. Further, when the polyurethane ratio is smaller than the composite ratio of 20/80 and the nylon ratio is large, the occurrence of crimping becomes insufficient. It is more preferably 40/60 to 60/40 in terms of uniform coil-like crimping and excellent soft stretchability.

The eccentric core sheath composite fiber of the present invention needs to have a cross-sectional curvature of 15% or less. The cross-sectional curvature rate referred to here indicates the degree of curvature of the interface between the core component thermoplastic polyurethane and the sheath component nylon 6, and the larger the value, the greater the degree of interface curvature, the finer the crimps appear, and the smaller the value. It is shown that the degree of curvature of the interface is small and a large crimp is developed.

By setting the cross-sectional curvature ratio to 15% or less, a soft stretch woven knit or stocking can be obtained in which uniform and dense crimping is developed and excellent soft stretchability and quality can be obtained. It is preferably 0 to 10%. More preferably, it is 0 to 5%.

Further, the eccentric core sheath composite fiber of the present invention needs to have a cross-sectional curvature rate CV value of 0.40 or less. In particular, in stockings, a sock knitting machine with four yarns is the mainstream, so it is necessary to evaluate with four stockings. Therefore, the cross-sectional curvature CV value referred to here is a value obtained by measuring the cross-sections of all the filaments of the four eccentric core-sheath composite fibers and dividing the standard deviation by the average value. Within this range, it is possible to obtain a soft stretch woven knitted fabric and stockings of excellent quality with little variation in crimping and no streaks or unevenness. More preferably, it is 0.20 or less.

The eccentric core-sheath composite fiber of the present invention preferably has an expansion / contraction rate of 90% or more. Within such a range, uniform and dense coil crimping is developed, and soft stretch woven knitted fabrics and stockings with excellent soft stretchability and quality can be obtained. More preferably, it is 100% or more.

The strength of the eccentric core-sheath composite fiber of the present invention is preferably 2.5 cN / dtex or more in terms of productivity in higher-order processes and durability of clothing. More preferably, it is 3.0 cN / dtex or more.

The elongation of the eccentric core-sheath composite fiber of the present invention is preferably 35% or more in terms of productivity in higher-order steps. More preferably, it is 40 to 65%.

The total fineness and the number of filaments of the eccentric core sheath composite fiber of the present invention can be arbitrarily designed in terms of stretchability and texture required for clothing applications. Considering the use for clothing, the total fineness of 5 to 235 dtex and the number of filaments of 1 to 144 are preferable. For example, in the case of stocking applications, a total fineness of 5 to 33 dtex and a filament number of 1 to 3 are preferable.

In the eccentric core-sheath composite fiber of the present invention, in order to control the cross-sectional curvature and the cross-sectional curvature CV value within such a range, in addition to the thermoplastic polyurethane, the polymer selection of nylon 6, and the antioxidant, the eccentric core-sheath composite It can be preferably controlled by combining the melting conditions (polymer temperature, polymer temperature difference, spinning temperature, etc.) in the stage before forming the cross section.

The thermoplastic polyurethane used in the present invention is a polymer compound obtained by the reaction of three components, diisocyanate, polyol, and chain extender.

Specific examples of diisocyanates include, for example, trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, 1,3-bis (isocyanetmethyl) cyclohexane, 1,4-bis (isocyanismethyl) cyclohexane, and 1,3-cyclohexanediisocyanate. , 1,4-Cyclohexane diisocyanate, 2,2'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate, 4,4'-diphenylmethane diisocyanate, 1,5-naphthalenediocyanide, 2,4-toluene diisocyanate, 2,6- Examples thereof include toluene diisocyanate and diphenylmethane diisocyanate. Diphenylmethane diisocyanate is preferable from the viewpoint of reactivity.

Specific examples of the polyol include, for example, a polyether polyol, a polyester polyol, a polycaprolactone polyol, a polycarbonate polyol, and the like, and the present invention is not particularly limited, and the polyol may be used alone or in combination of two or more. Polycarbonate polyol is preferable from the viewpoint of heat resistance.

Specific examples of the chain extender include ethanediol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, diethylene glycol, dipropylene glycol and the like. From the viewpoint of reactivity, 1,4-butanediol is preferable.

The weight average molecular weight (Mw) of the thermoplastic polyurethane used for the core portion of the eccentric core-sheath composite fiber of the present invention is preferably 80,000 or more and 180,000 or less. By setting Mw to 80,000 or more, it is possible to prevent thermal deterioration within a preferable polymer temperature range described later, and the silk-reeling property is improved. By setting it to 180,000 or less, it is possible to reduce the difference in melt viscosity with nylon 6, and it is possible to set the cross-sectional curvature rate to 15% or less. More preferably, it is 80,000 or more and 140,000 or less.

Further, the relationship Mz / Mw between the average molecular weight (Mz) and the weight average molecular weight (Mw) of the thermoplastic polyurethane is preferably 3.0 or less. Mz / Mw is an index showing the spread to the higher side, and by setting it in this range, the variation in melt viscosity is reduced, and the cross-sectional curvature CV value can be set to 0.40 or less.

Further, since the thermoplastic polyurethane is a polymer in which thermal deterioration is liable to proceed, thermal decomposition is liable to occur within a preferable polymer temperature range described later, which affects the silk-reeling property. Further, due to thermal decomposition, the molecular weight is lowered, the difference in melt viscosity with nylon becomes large, the bending rate becomes large, and melt viscosity unevenness occurs, which leads to deterioration of the cross-sectional bending rate. Therefore, it is preferable to add a hindered phenol-based stabilizer, which is an antioxidant that captures radicals, to the thermoplastic polyurethane at the core.

The amount of the hindered phenol-based stabilizer is preferably 0.1% by weight or more and 1.0% by weight or less with respect to the weight of the thermoplastic polyurethane. When the content is 0.1% by weight or more, it is possible to prevent thermal deterioration of the thermoplastic polyurethane polymer within a preferable polymer temperature range described later, and it is possible to prevent variations in viscosity and yarn breakage. When the content is 1.0% by weight or less, the antioxidant does not precipitate on the fiber surface, which is preferable. Further, if necessary, another antioxidant such as HALS, phosphorus-based, sulfur-based, etc. may be used in combination.

Hindered phenolic stabilizers include, for example, pentaerythritol tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate] (IR1010), 2,4,6-tris (3', 5). '-Di-tert-butyl-4'-hydroxybenzyl) Mesitylene (IR1330), (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). Be done.

The thermoplastic polyurethane of the core in the present invention has various additives such as a matting agent, a flame retardant, an ultraviolet absorber, an infrared absorber, a crystal nucleating agent, a fluorescent whitening agent, an antistatic agent, and a hygroscopic agent. Polymers, carbon and the like may be added. When added, the total additive content may be between 0.001 and 10% by weight, if necessary, copolymerized or mixed.

Nylon 6 in the sheath portion of the present invention has various additives such as a matting agent, a flame retardant, an antioxidant, an ultraviolet absorber, an infrared absorber, a crystal nucleating agent, a fluorescent whitening agent, and an antioxidant. , Hygroscopic polymer, carbon and the like may be added. When added, the total additive content may be between 0.001 and 10% by weight, if necessary, copolymerized or mixed.

The relative sulfuric acid viscosity of the sheath nylon 6 of the present invention is preferably 2.0 or more and 2.3 or less. Within such a range, the difference in melt viscosity with the thermoplastic polyurethane can be reduced, the cross-sectional formability can be stabilized, and the cross-sectional curvature can be set to 15% or less.

The eccentric core sheath composite fiber of the present invention can be produced by a known melt spinning or composite spinning method. For example, thermoplastic polyurethane (core portion) and nylon 6 (sheath portion) are separately melted, subjected to a spinning pack, and discharged from an eccentric core-sheath type composite spinneret to form a yarn. The method for forming the eccentric core sheath structure is not particularly limited, but for example, a method in which a thin sheath of nylon 6 is concentrically covered with polyurethane and this and the flow of the second nylon 6 are combined side by side, or polyurethane and nylon 6 are used. There is a method of covering with a thin sheath of nylon 6 after compounding in a side-by-side manner. After the yarn is uniformly cooled to room temperature by a cooling device provided on the downstream side of the composite spinneret, an oil agent is applied and the yarn is wound at a low speed. After that, it is preferable to stretch it 3 to 5 times.

The melt viscosity of the thermoplastic polyurethane at 210 ° C. is preferably 5,000 to 18,000 poise. By setting this range, the difference in melt viscosity becomes smaller when the temperature is set to spin with nylon 6 in the relative viscosity range, so that the cross-sectional formability can be stabilized and the cross-sectional curvature can be set to 15% or less. Will be. More preferably, it is 8,000 to 15,000 poise.

The melt viscosity of nylon at 240 ° C. is preferably 200 to 2,000 poise. Within such a range, when spinning with the above-mentioned thermoplastic polyurethane, the difference in melt viscosity becomes small, so that the cross-sectional formability can be stabilized and the cross-sectional curvature can be set to 15% or less. More preferably, it is 300 to 1,500 poise.

By reducing the difference in melt viscosity between the thermoplastic polyurethane and nylon 6 during cross-section formation, it is possible to reduce the cross-sectional curvature rate, but it is not possible to measure the actual melt viscosity in the spinning pack. Therefore, the melt viscosity of thermoplastic polyurethane at 210 ° C and nylon at 240 ° C was used as a reference. By using the thermoplastic polyurethane and nylon 6 in such a range, the difference in melt viscosity can be sufficiently reduced at a preferable polymer temperature described later.

The difference in melt viscosity between the thermoplastic polyurethane and nylon 6 at each polymer temperature is preferably 300 poise or less, and more preferably 100 poise or less.

The polymer temperature of the thermoplastic polyurethane is preferably 235 ° C. or higher and 245 ° C. or lower. The polymer temperature referred to here is the temperature before entering the spinning pack.

Within such a range, the difference in melt viscosity with nylon 6 can be reduced, the cross-sectional formability can be stabilized, and the cross-sectional curvature can be set to 15% or less. More preferably, it is 240 ° C. or higher and 245 ° C. or lower.

Further, it is preferable that the polymer temperature difference between the thermoplastic polyurethane and nylon 6 is within 10 ° C. It is desirable that the spinning temperature and the polymer temperature be the same, but considering that the temperature varies depending on the spinning machine such as the length of the polymer pipe, even inside the spinning pack after the polymer is melted, the polymer temperature is within the range. The appropriate spinning temperature may be set. By controlling the polymer temperature and the polymer temperature difference within such a range, it is possible to reduce the heat transfer between the thermoplastic polyurethane and the nylon 6 inside the spinning pack, and the base discharge hole forming the composite cross section can be reduced. The temperature difference between the parts is reduced, the cross-sectional shapeability is stabilized, the cross-sectional curvature rate is 15% or less, and the cross-sectional curvature rate CV value is 0.40 or less.

Preferably, the polymer temperature difference is within 7 ° C. If the polymer temperature difference exceeds 10 ° C, the transfer of heat becomes large when forming a composite cross section, the curvature of the interface on the core side becomes large, the curvature becomes unstable, and the cross-section formability deteriorates, resulting in a cross-section curvature rate. It tends to exceed 15%, and the cross-sectional curvature CV value tends to exceed 0.40.

For example, under the melting conditions described in Patent Document 1 and Patent Document 2, since the spinning temperature difference between the thermoplastic polyurethane and nylon 6 is 20 ° C., the polymer temperature difference exceeds 10 ° C., and therefore the cross-sectional curvature rate and cross-section. The curvature rate CV value cannot be within such a range.

It is preferable that the temperature difference on the base surface is within 5 ° C. The base surface temperature referred to here is a value obtained by measuring the center point of the base and three outer points and calculating the difference between the maximum value and the minimum value. Within such a range, the cross-sectional curvature CV value can be set to 0.40 or less.

The eccentric core sheath composite fiber of the present invention is preferably used for fabrics and clothing. The fabric form can be selected according to the purpose such as woven fabric and knitted fabric, and clothing is also included. Further, as clothing, various clothing products such as stockings, innerwear, and sportswear can be used.

The eccentric core sheath composite fiber of the present invention is preferably used for stockings used for at least a part of the leg portion. Here, the stocking includes stocking products typified by pantyhose, long stocking, and short stocking. The leg portion refers to the range from the garter portion to the toes in the case of pantyhose, for example.

Further, the knitting machine for stockings is not particularly limited, and a normal sock knitting machine can be used. For example, a sock knitting machine with two or four yarns is used to supply the eccentric core sheath composite yarn of the present invention. It can be organized by the usual method of knitting. For example, a Zokki type stocking that is knitted by supplying only the eccentric core sheath composite yarn of the present invention, a covering yarn that uses an elastic yarn as a core yarn and winds a clothing yarn single or double, and an eccentric core sheath composite fiber of the present invention. Examples include cross-knit type stockings that are knitted by alternately supplying.

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 viscosity of nylon 6 with sulfuric acid Dissolve 0.25 g of nylon 6 chip sample in 100 ml of sulfuric acid with a concentration of 98% by weight so as to be 1 g, and use an Ostwald viscometer to flow down at 25 ° C. (T1). ) Was measured. Subsequently, the flow time (T2) of sulfuric acid having a concentration of 98% by weight was measured. The ratio of T1 to T2, that is, T1 / T2, was defined as the relative viscosity of sulfuric acid.

(2) Measurement of molecular weight (Mw, Mz / Mw) of thermoplastic polyurethane 5 ml of a measurement solvent (0.05 M lithium bromide-added dimethylformamide) was added to 10 mg of a thermoplastic polyurethane chip sample, and the mixture was stirred at room temperature for about 60 minutes. Then, it was filtered using a 0.45 μm membrane filter. The purified sample was measured for each molecular weight under the following conditions.
Equipment: Gel Permeation Chromatograph GPC
Detector: Differential refractometer detector RI (Tosoh RI-8020 type, sensitivity 32)
Column: TSKgel α-M, α-3000 1 each (φ7.8 mm x 30 cm, manufactured by Tosoh)
Solvent: 0.05 M Lithium bromide added Dimethylformamide Flow rate: 0.8 mL / min
Column temperature: 0.2 mL
Injection volume: 0.2 mL
Standard sample: Tosoh monodisperse polystyrene Data processing: TRC GPC data processing system

(3) Melt viscosity Using "Float Tester" CFT-500 manufactured by Shimadzu Corporation, die: 1.0 mmφ x 1.0 mm, plunger area: 1 cm ² , temperature: 210 ° C (thermoplastic polyurethane), 240 ° C ( Nylon 6), time: 4 minutes, load: 200N, sample volume: 1g.

(4) Fineness 1. Set the fiber sample on a measuring instrument with a circumference of 125 m / circumference, rotate it 200 times to make a loop-shaped skein, dry it with a hot air dryer (105 ± 2 ° C x 60 minutes), and then balance. The fineness was calculated from the value obtained by measuring the skein mass and multiplying by the official moisture content. The official moisture content of the core-sheath composite yarn was 4.5%.

(5) Strength / Elongation Fiber samples are 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-sectional curvature A. Taking a cross-sectional photograph Tokyo Denshi Co., Ltd. Co., Ltd., which melts a packaging agent consisting of paraffin, stearic acid, and ethyl cellulose, introduces fibers, solidifies them by leaving them at room temperature, and cuts the raw yarn in the packaging agent 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 curvature The cross-sections of all the filaments of the four eccentric core-sheath composite fibers were measured by the following procedures (a) to (e), and the average value was taken as the cross-sectional curvature. Hereinafter, it will be described with reference to FIG.
a) In the cross section of the fiber, a tangent line A is drawn at the point (point a) where the composite interface between the thermoplastic polyurethane and the polyamide is most convex.
b) Draw a line B that is parallel to the line A and connects two points (points b-1 and b-2) that have the maximum inner diameter of the core.
c) Draw a line C (extending to the fiber surface) connecting the point a and the intermediate point (point b-3) of the two points (points b-1 and b-2) where the inner diameter of the core portion is maximum.
d) Let the point c be the intersection of the line C having a short distance from the point a and the fiber surface, and the point d be the intersection with another fiber surface.
e) Cross-sectional curvature = (length of point a-point b-3 / length of point c-point d) / 100

(7) Cross-sectional curvature CV value The cross-sectional curvature of all the filaments of the four eccentric core-sheath composite fibers was measured, and the value obtained by dividing the standard deviation by the average value was taken as the cross-sectional curvature CV value.
Cross-section curvature CV value = standard deviation of cross-section curvature σ / average value of cross-section curvature

(8) Stretching / stretching ratio The stretching / stretching ratio was determined by the following formula according to JIS L1090 (synthetic fiber filament bulk processed yarn test method) and Section 5.7 C method (simple method).
Expansion and contraction rate (%) = [(L1-L0) / L0] × 100%
L0: 90 ° C. hot water treatment is performed for 20 minutes with a 0.0018 cN / dtex load suspended on the fiber skein, and the skein length after air-drying for one day and night L1: After measuring L0, the L0 measured load is removed and 0.09 cN / The length of the skein 30 seconds after suspending the dtex load

(9) Stocking manufacturing method Using four eccentric core sheath composite fibers for the thread for the leg part, a super 4 sock knitting machine (400 needles) manufactured by Nagata Seiki Co., Ltd. is used to knit into a stocking tissue. I got the dough.
Next, with the fabric suspended, presetting was sequentially performed with 90 ° C. steam and 100 ° C. pressurized steam, and then the crotch portion and the toe portion were sewn.
After thoroughly cleaning and removing the fiber oil, dye it in beige, which is the general color of pantyhose, at 95 ° C for 40 minutes, apply a fabric softener treatment, and then cover it with a normal foot mold and set it at 110 ° C for 15 seconds. And got stockings.

(10) Evaluation of stocking quality The stockings produced in (9) above were evaluated on a four-point scale according to the following criteria, and a score of Δ or higher was judged as acceptable.
◎: High quality with no streaks ○: Good quality with almost no streaks △: No problem with quality although there are some streaks ×: Low quality with clear streaks

(11) Evaluation of soft stretch of stockings The stockings produced in (9) above were evaluated on a four-point scale according to the following criteria, and a score of Δ or higher was judged as acceptable.
◎: Very good ○: Good △: Slightly good ×: Inferior

[Example 1]
Thermoplastic polyurethane (weight average molecular weight (Mw) = 114,000, Mz / Mw = 2.0) in which diisocyanate is diphenylmethane diisocyanate, polyol is polyester polyol and polycarbonate polyol, and chain extender is 1,4-butanediol. , Melt viscosity = 8,000 polyester) was used as the core. As heat-resistant agents, 0.25% by weight of hindered phenol-based stabilizer Irganox1010 (manufactured by BASF Japan) and 0.25% by weight of Irganox1330 (manufactured by BASF Japan) were added at the time of polymerization.
Here, nylon 6 having a relative sulfuric acid viscosity of 2.20 was used as the sheath portion.
The thermoplastic polyurethane chip was melted at a spinning temperature (set value) of 242 ° C, and the nylon 6 chip was melted at a spinning temperature (set value) of 255 ° C. The polymer temperature (measured value) before entering the spinning pack was thermoplastic polyurethane: 238 ° C. and nylon 6: 246 ° C. Using an eccentric core-sheath composite spinneret (round hole, 8 holes), melt-discharging was performed at a core thermoplastic polyurethane / sheath nylon 6 weight ratio of 50/50. The base surface temperature had an average value of 226 ° C and a difference of 1.7 ° C.
The yarn discharged from the mouthpiece was cooled and solidified by a yarn cooling device, oiled (lubricated), and wound at 600 m / min. Then, it was stretched 4.29 times with a stretching machine, and 18 dtex, 1 filament eccentric core sheath composite monofilament was wound around a bobbin to obtain 8 pieces. The strength of the yarn was 3.8 cN / dtex, and the elongation was 44%. The obtained eccentric core-sheath composite monofilament had a cross-sectional curvature rate of 8.0%, a cross-sectional curvature rate CV value of 0.20, and an expansion / contraction rate of 115%.
The stockings produced using the obtained eccentric core-sheath composite monofilament had almost no streaks and were of good quality (◯). The soft stretchability was also good (◯).

[Example 2]
The thermoplastic polyurethane was spun in the same manner as in Example 1 except that the weight average molecular weight (Mw) was 130,000 (Mz / Mw = 2.0, melt viscosity = 9,500 pose), and 18dtex and 1 filament were used. Eccentric core sheath composite monofilament was obtained.
The obtained eccentric core-sheath composite monofilament had a cross-sectional curvature rate of 10.0%, a CV value of 0.20, and an expansion / contraction rate of 105%.
The stockings produced using the obtained eccentric core-sheath composite monofilament had almost no streaks and were of good quality (◯). The soft stretchability was also good (◯).

[Example 3]
The thermoplastic polyurethane was spun in the same manner as in Example 1 except that the weight average molecular weight (Mw) was 150,000 (Mz / Mw = 2.5, melt viscosity = 11,500 pose), and 18dtex and 1 filament were used. Eccentric core sheath composite monofilament was obtained.
The obtained eccentric core-sheath composite monofilament had a cross-sectional curvature rate of 12.5%, a CV value of 0.30, and an expansion / contraction rate of 100%.
The stockings produced using the obtained eccentric core-sheath composite monofilament had no quality problem (Δ), although there were some streaks. The soft stretchability was also slightly good (Δ).

[Example 4]
The thermoplastic polyurethane was spun by the same method as in Example 1 except that the weight average molecular weight (Mw) was 180,000 (Mz / Mw = 2.8, melt viscosity = 14,000 poise), and 18dtex and 1 filament were used. Eccentric core sheath composite monofilament was obtained.
The obtained eccentric core-sheath composite monofilament had a cross-sectional curvature rate of 14.5%, a CV value of 0.35, and an expansion / contraction rate of 93%.
The stockings produced using the obtained eccentric core-sheath composite monofilament had no quality problem (Δ), although there were some streaks. The soft stretchability was also slightly good (Δ).

[Example 5]
The thermoplastic polyurethane was spun by the same method as in Example 1 except that the weight average molecular weight (Mw) was 80,000 (Mz / Mw = 1.9, melt viscosity = 5,000 pose), and 18dtex and 1 filament were used. Eccentric core sheath composite monofilament was obtained.
The obtained eccentric core-sheath composite monofilament had a cross-sectional curvature rate of 5.0%, a CV value of 0.18, and an expansion / contraction rate of 120%.
The stockings produced using the obtained eccentric core-sheath composite monofilament had no streaks and were of high quality (⊚). The soft stretchability was also very good (◎).

[Example 6]
The thermoplastic polyurethane chip is melted at a spinning temperature (set value) of 247 ° C, and the nylon 6 chip is melted at a spinning temperature (set value) of 255 ° C. , Nylon 6: 246 ° C. The base surface temperature had an average value of 227 ° C and a difference of 1.8 ° C. Spinning was performed in the same manner as in Example 1 except that the melting conditions of the thermoplastic polyurethane were changed to obtain an eccentric core-sheath composite monofilament of 18 dtex and 1 filament.
The obtained eccentric core-sheath composite monofilament had a cross-sectional curvature rate of 5.0%, a CV value of 0.18, and an expansion / contraction rate of 120%.
The stockings produced using the obtained eccentric core-sheath composite monofilament had no streaks and were of high quality (⊚). The soft stretchability was also very good (◎).

[Example 7]
The thermoplastic polyurethane chips were melted at a spinning temperature (set value) of 252 ° C, and the nylon 6 chips were melted at a spinning temperature (set value) of 255 ° C. The polymer temperature (measured value) before entering the spinning pack was thermoplastic polyurethane: 244 ° C. and nylon 6: 246 ° C. The base surface temperature had an average value of 229 ° C and a difference of 0.8 ° C. Spinning was performed in the same manner as in Example 1 except that the melting conditions of the thermoplastic polyurethane were changed to obtain an eccentric core-sheath composite monofilament of 18 dtex and 1 filament.
The obtained eccentric core-sheath composite monofilament yarn had a cross-sectional curvature rate of 3.0%, a CV value of 0.15, and an expansion / contraction rate of 125%.
The stockings produced using the obtained eccentric core-sheath composite monofilament had no streaks and were of high quality (⊚). The soft stretchability was also very good (◎).

[Example 8]
The thermoplastic polyurethane was spun by the same method as in Example 7 except that the weight average molecular weight (Mw) was 80,000 (Mz / Mw = 1.9, melt viscosity = 5,000 pose), and 18dtex and 1 filament were used. Eccentric core sheath composite monofilament was obtained.
The obtained eccentric core-sheath composite monofilament had a cross-sectional curvature rate of 1.0%, a CV value of 0.10, and an expansion / contraction rate of 130%.
The stockings produced using the obtained eccentric core-sheath composite monofilament had no streaks and were of high quality (⊚). The soft stretchability was also very good (◎).

[Example 9]
Nylon 6 was spun in the same manner as in Example 8 except that the relative viscosity of sulfuric acid of nylon 6 was set to 2.00 (melt viscosity = 300 poise) to obtain 18 dtex, 1 filament eccentric core-sheath composite monofilament.
The obtained eccentric core-sheath composite monofilament had a cross-sectional curvature rate of 1.0%, a CV value of 0.10, and an expansion / contraction rate of 120%.
The stockings produced using the obtained eccentric core-sheath composite monofilament had no streaks and were of high quality (⊚). The soft stretchability was also very good (◎).

[Example 10]
Spinning was performed in the same manner as in Example 7 except that the relative sulfuric acid viscosity of nylon 6 was set to 2.30 (melt viscosity = 1500 poise) to obtain an eccentric core-sheath composite monofilament of 18 dtex and 1 filament.
The obtained eccentric core-sheath composite monofilament had a cross-sectional curvature rate of 10.0%, a CV value of 0.30, and an expansion / contraction rate of 103%.
The stockings produced using the obtained eccentric core-sheath composite monofilament had almost no streaks and were of good quality (◯). The soft stretchability was also good (◯).

[Comparative Example 1]
The thermoplastic polyurethane was spun in the same manner as in Example 1 except that the weight average molecular weight (Mw) was 250,000 (Mz / Mw = 3.1, melt viscosity = 21,000 podise), and 18dtex and 1 filament were used. Eccentric core sheath composite monofilament was obtained.
The cross-sectional curvature of the obtained raw yarn was 19.0%, the CV value was 0.45, and the expansion / contraction elongation was 80%. That is, it can be seen that the interface on the core side has a large curvature, the coil-shaped crimping is fine and non-uniform, and the crimping characteristics are low.
The stockings produced using the obtained eccentric core-sheath composite monofilament were of low grade (x) with clearly visible streaks. The soft stretchability was also inferior (x).

[Comparative Example 2]
The thermoplastic polyurethane chips were melted at a spinning temperature (set value) of 236 ° C, and the nylon 6 chips were melted at a spinning temperature (set value) of 255 ° C. The polymer temperature (measured value) before entering the spinning pack was thermoplastic polyurethane: 230 ° C. and nylon 6: 246 ° C. The base surface temperature had an average value of 225 ° C and a difference of 6.2 ° C. Spinning was performed in the same manner as in Example 1 except that the melting conditions of the thermoplastic polyurethane were changed to obtain an eccentric core-sheath composite monofilament of 18 dtex and 1 filament.
The obtained eccentric core-sheath composite monofilament had a cross-sectional curvature rate of 23.0%, a CV value of 0.55, and an expansion / contraction rate of 80%. That is, it can be seen that the interface on the core side has a large curvature, the coil-shaped crimping is fine and non-uniform, and the crimping characteristics are low.
The stockings produced using the obtained eccentric core-sheath composite monofilament were of low grade (x) with clearly visible streaks. The soft stretchability was also inferior (x).

[Comparative Example 3]
The thermoplastic polyurethane chips were melted at a spinning temperature (set value) of 230 ° C., and the nylon 6 chips were melted at a spinning temperature (set value) of 250 ° C. The polymer temperature (measured value) before entering the spinning pack was thermoplastic polyurethane: 225 ° C. and nylon 6: 242 ° C. The base surface temperature had an average value of 224 ° C and a difference of 7.5 ° C. Spinning was performed in the same manner as in Example 1 except that the melting conditions of the thermoplastic polyurethane were changed to obtain an eccentric core-sheath composite monofilament of 18 dtex and 1 filament.
The obtained eccentric core-sheath composite monofilament had a cross-sectional curvature rate of 24.5%, a CV value of 0.55, and an expansion / contraction rate of 80%. That is, it can be seen that the interface on the core side has a large curvature, the coil-shaped crimping is fine and non-uniform, and the crimping characteristics are low.
The stockings produced using the obtained eccentric core-sheath composite monofilament were of low grade (x) with clearly visible streaks. The soft stretchability was also inferior (x).

Although the present invention has been described in detail using specific embodiments, it will be apparent to those skilled in the art that various modifications and variations are possible without departing from the intent and scope of the invention. This application is based on a Japanese patent application filed on June 23, 2017 (Japanese Patent Application No. 2017-123316), which is incorporated by reference in its entirety.

1: Thermoplastic polyurethane 2: Nylon 6

Claims (4)

An eccentric core-sheath composite fiber in which the core component is thermoplastic polyurethane and the sheath component is nylon 6 has an eccentric core-sheath composite having a cross-sectional curvature rate of 15% or less and a cross-sectional curvature rate CV value of 0.40 or less. fiber. The eccentric core sheath composite fiber according to claim 1, wherein the expansion / contraction rate is 90% or more. A woven or knitted fabric having at least a part of the eccentric core sheath composite fiber according to claim 1 or 2. A stocking having the eccentric core sheath composite fiber according to claim 1 or 2 in at least a part of a leg portion.

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