TW201907061A - Polyurethane. Nylon 6 eccentric core sheath composite fiber - Google Patents

Abstract

The purpose of the present invention is to provide a polyurethane-nylon 6 eccentric sheath-core conjugate fiber which can obtain an excellent soft stretchable woven/knitted fabric and ensure the quality of stockings. The present invention relates to an eccentric sheath-core conjugate fiber being characterized by having: (1) a core component of a thermoplastic polyurethane; and (2) a sheath component of nylon 6, wherein the curvature of a cross section is 15% or less and the CV value of the curvature of a cross section is 0.40 or less.

Description

   Polyurethane‧Nylon 6 Eccentric Core-Sheath Composite Fiber   

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

The self-crimping composite fiber obtained by eccentrically compounding polyurethane and polyamide is a knit fabric with excellent crimping properties, soft stretchability and transparency, and is highly suitable as a material for high-end socks. Evaluation.

On the other hand, the variation in the crimping characteristics of the sock-based fiber using the self-crimping composite fiber exists as it is, and there is a problem that streaks or uneven knitted fabric defects easily occur. In order not to cause streaks or uneven knitted fabric defects, self-crimping composite fibers are all subjected to crimping characteristics inspection and knitting inspection, and are selected for use. Therefore, there is an urgent need 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 making socks.

Since the past, a large number of reviews have been conducted on self-crimping composite fibers obtained by eccentrically compounding polyurethane and polyamide. For example, Patent Document 1 describes a self-crimping composite fiber using a polycarbonate-based polyurethane containing at least 10% by weight as a copolymerization component or a mixed component, and the relative viscosity of dimethylacetamide is 1.80 Polyurethane composition of ~ 3.00 can improve the stability of composite spinning and spinning, and suppress the deviation between polymers of polyurethane elastomer.

In addition, Patent Document 2 describes a self-crimping composite filament which is obtained by adding and mixing a polyamide with a thermoplastic polyurethane in a molten state, and mixing 5 to 20% by weight of a molecular weight of 400 or more. Polyurethane elastomer of a polyisocyanate compound is bonded at a core weight ratio of 80/20 to 20/80 in the cross section of a single filament, and the core is eccentrically bonded to perform composite melt spinning, followed by stretching. The filament obtained by relaxation heat treatment is characterized in that the reduction rate of the polyurethane elastomer in dimethylformamide is 80% by weight or less, and the linear shrinkage of the filament is 10 %, The curl display rate is above 68%; polyamine and polyurethane elastomers have excellent peel resistance, and have sufficient curl display force and curl stretch recovery even after relaxation heat treatment.

Prior art literature Patent literature

Patent Document 1 Japanese Unexamined Patent Publication No. 2-80616

Patent Document 2 Japanese Patent Publication No. 7-91693

However, although the composite fiber described in Patent Document 1 is excellent in melt spinning stability and silk-making property and can be used for industrially manufacturing a composite fiber having stable physical properties, there is no teaching about deviations in crimp characteristics. There is still the problem that the curl deviation remains as it is, and streaks or uneven knitted fabric defects are liable to occur.

Moreover, although the composite fiber described in Patent Document 2 has excellent peel resistance and a curling force and a curling stretch recovery property, there is no teaching about deviations in curling characteristics. There is still the problem that the curl deviation remains as it is, and streaks or uneven knitted fabric defects are liable to occur.

Therefore, in the present invention, an object is to provide a polyurethane · nylon 6 eccentric core-sheath composite fiber, which overcomes the problems of the conventional techniques and obtains excellent soft stretch knit fabrics and socks.

In order to solve the above problems, the present invention includes the following configurations.

(1) An eccentric core-sheath composite fiber having an eccentric core-sheath composite fiber with a core component of thermoplastic polyurethane and a sheath component of nylon 6, characterized in that the cross-section bending rate is 15% or less and the cross-section is curved The rate CV value is 0.40 or less.

(2) The eccentric core-sheath composite fiber according to (1), which has an expansion and contraction elongation of 90% or more.

(3) A knitted fabric comprising the core-sheath composite fiber according to (1) or (2) in at least a portion.

(4) A sock comprising a core-sheath composite fiber according to (1) or (2) on at least a part of a leg.

According to the present invention, a polyurethane ‧ nylon 6 eccentric core-sheath composite fiber can be provided, which can obtain excellent soft stretch knit fabric and socks quality.

1‧‧‧ thermoplastic polyurethane

2‧‧‧ nylon 6

1 (a) and 1 (b) of FIG. 1 are model diagrams illustrating the cross section of the eccentric core-sheath composite fiber of the present invention.

FIG. 2 is a model diagram for measuring the cross-section bending rate of the eccentric core-sheath composite fiber of the present invention.

Implementation of the invention

The eccentric core-sheath composite fiber of the present invention is a latent crimp yarn that exhibits a coil-like crimp in a knitted fabric and socks manufacturing process (hereinafter, referred to as a high-order step). In particular, knitted fabrics such as socks are knitted by supplying a plurality of yarns to a knitting machine. Therefore, when yarns having different latent crimp properties are supplied and knitted, the shortcomings such as streaks or unevenness are not seen even after being knitted. Also, curl deviations, streaks or unevenness may occur in higher-order steps.

The present inventors have found that by controlling the interface in the cross section of the eccentric core-sheath fiber before crimp development, stable crimp can be exhibited, crimp deviations can be suppressed, and soft stretch knits or socks with excellent quality without streaks or unevenness can be obtained. .

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

The so-called eccentric core sheath in the present invention means that in the cross section of the composite fiber, the position of the center of gravity of the thermoplastic polyurethane in the core portion is different from the center of the cross section of the composite fiber. Specifically, it means the form as shown in FIG.1 (a) and FIG.1 (b). By forming an eccentric core-sheath structure, it exhibits a uniform coiled curl. In addition, due to the poor viscosity of the core component thermoplastic polyurethane and the sheath component nylon 6 and the like, the thermoplastic polyurethane at the interface becomes slightly convex and bends. The core component may be partially exposed as shown in FIG. 1 (b), and more preferably, as shown in FIG. 1 (a), the sheath component nylon 6 contains a thermoplastic polyurethane having a core component.

The minimum thickness of the nylon 6 covering the sheath component of the core component is preferably 0.01 to 0.1 times the diameter of the composite fiber, and more preferably 0.02 to 0.08 times. If it is this range, sufficient curling force and stretchability 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 greater than the composite ratio of 80/20 and the nylon ratio becomes smaller, the dyeability or durability becomes worse, and the practicality becomes worse. In addition, when the polyurethane ratio is less than the composite ratio of 20/80 and the nylon ratio becomes large, the development of curl becomes insufficient. From the viewpoint of exhibiting uniform coiled curl and excellent soft stretchability, it is more preferably 40/60 to 60/40.

The eccentric core-sheath composite fiber of the present invention must have a cross-section bending rate of 15% or less. The bending rate of the profile mentioned here means the degree of bending at the interface between the core component thermoplastic polyurethane and the sheath component nylon 6, the larger the value, the greater the degree of bending at the interface, showing a fine curl, and the smaller the value , The smaller the degree of curvature of the interface, showing a larger curl.

By setting the bending rate from the cross section to 15% or less, a soft stretch knit fabric and socks that can exhibit uniform and dense curls and obtain excellent soft stretchability or quality can be obtained. It is preferably 0 to 10%, and more preferably 0 to 5%.

In addition, the eccentric core-sheath composite fiber of the present invention must have a cross-section bending ratio CV value of 0.40 or less. In particular, in socks, since the four-knitting sock knitting machine is the mainstream, it is necessary to evaluate four socks constituting the socks. Therefore, the cross-section bending ratio CV value referred to here is a value obtained by measuring the cross-section of all filaments of four eccentric core-sheath composite fibers and dividing the standard deviation by the average value. By setting it as such a range, it is possible to obtain a soft stretch knit fabric and socks which are excellent in quality with few curl deviations and no streaks or unevenness. It is more preferably 0.20 or less.

The expansion and contraction elongation of the eccentric core-sheath composite fiber system of the present invention is preferably 90% or more. By setting it as such a range, the soft stretchable knitted fabric and socks which can exhibit a uniform and dense coil curl, and can obtain excellent soft stretchability or 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, and more preferably 3.0 cN / dtex or more in terms of productivity in high-order steps or durability of clothing products.

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

The total fineness or the number of filaments of the eccentric core-sheath composite fiber of the present invention can be arbitrarily designed in terms of stretchability or feel required for clothing applications. Considering the use of clothing, the total fineness is preferably 5 to 235 dtex and the number of filaments is 1 to 144. For example, for socks, the total fineness is preferably 5 to 33 dtex and the number of filaments is 1 to 3.

In the eccentric core-sheath composite fiber of the present invention, in order to control the cross-section bending rate and the cross-section bending rate CV value in such a range, in addition to the polymer selection of thermoplastic polyurethane, nylon 6, and antioxidants, The melting conditions (polymer temperature, polymer temperature difference, spinning temperature, etc.) at the previous stage that can form the eccentric core-sheath composite profile by combination can be better controlled.

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

Specific examples of the diisocyanate include trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, and 1,3-bis (isocyanatemethyl) cyclohexyl. Alkane, 1,4-bis (isocyanatemethyl) cyclohexane, 1,3-cyclohexane diisocyanate, 1,4-cyclohexane diisocyanate, 2,2'-diphenylmethane diisocyanate, 2, 4'-diphenylmethane diisocyanate, 4,4'-diphenylmethane diisocyanate, 1,5-naphthalene diisocyanate, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, diphenylmethane Diisocyanate, etc. From the viewpoint of reactivity, diphenylmethane diisocyanate is preferred.

Specific examples of the polyol include, for example, polyether polyol, polyester polyol, polycaprolactone polyol, polycarbonate polyol, and the like, which are not particularly limited, and may be used alone or in combination of two or more. From the viewpoint of heat resistance, a polycarbonate polyol is preferred.

Specific examples of the chain extender include ethylene glycol, 1,2-propylene glycol, 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, diethylene glycol, and diethylene glycol. Propylene glycol, etc. From the viewpoint of reactivity, 1,4-butanediol is preferred.

In the eccentric core-sheath composite fiber of the present invention, the weight average molecular weight (Mw) of the thermoplastic polyurethane used for the core is preferably 80,000 or more and 180,000 or less. By setting Mw to 80,000 or more, thermal degradation in a preferable polymer temperature range described later can be prevented, and silk-forming properties become good. Since it is 180,000 or less, the difference in melt viscosity with nylon 6 can be reduced, and the cross-section bending rate can be 15% or less. It is more preferably 80,000 to 140,000.

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 indicating the expansion to the high side. Since it is set in this range, the deviation of the melt viscosity is reduced, and the cross-section bending ratio CV value can be made 0.40 or less.

In addition, since the thermoplastic polyurethane is a polymer that is easily thermally degraded, thermal decomposition easily occurs in a preferable polymer temperature range described later, and affects the silk-making property. In addition, the molecular weight decreases due to thermal decomposition, and the difference in melt viscosity with nylon becomes larger. Not only does the bending rate increase, but the melt viscosity becomes uneven, and the bending rate of the cross section becomes worse. Therefore, it is preferable that a hindered phenol-based stabilizer containing an antioxidant capable of trapping free radicals is added to the thermoplastic polyurethane of the core.

The amount of the hindered phenol-based stabilizer with respect to the weight of the thermoplastic polyurethane is preferably 0.1% by weight or more and 1.0% by weight or less. Since it is set to 0.1% by weight or more, thermal degradation of the thermoplastic polyurethane polymer in a preferable polymer temperature range described later can be prevented, and variation in viscosity or disconnection can be prevented. Since it is 1.0 weight% or less, it is preferable that an antioxidant does not precipitate on a fiber surface. If necessary, HALS, phosphorus-based, sulfur-based, or other antioxidants may be used in combination.

Examples of hindered phenol-based stabilizers include pentaerythritol [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate] (IR1010), 2,4,6-ginseng (3 ', 5'-di-tert-butyl-4'-hydroxybenzyl) mesitylene (IR1330), (1,3,5-trimethyl-2,4,6-ginseng (3,5-di-tert-butyl) 4-hydroxyphenyl) benzene (AO-330), 1,3,5-ginseng [[3,5-bis (1,1-dimethylethyl) -4-hydroxyphenyl] methyl] -1,3,5-three -2,4,6 (1H, 3H, 5H) -trione (IR3114), N, N'-hexamethylenebis [3- (3,5-di-third-butyl-4-hydroxyphenyl) Promethazine] (IR1098).

Various additives can be added to the thermoplastic polyurethane of the core of the present invention, such as matting agent, flame retardant, ultraviolet absorber, infrared absorber, crystal nucleating agent, fluorescent whitening agent, anti- Electrostatic agents, hygroscopic polymers, carbon, etc. When added, the total content of the additive is between 0.001 and 10% by weight, and can be copolymerized or mixed as required.

Various additives can be added to the nylon 6 of the sheath portion of the present invention, such as matting agents, flame retardants, antioxidants, ultraviolet absorbers, infrared absorbers, crystal nucleating agents, fluorescent whitening agents, and antistatic agents. , Hygroscopic polymer, carbon, etc. In addition, when added, the total additive content is between 0.001 and 10% by weight, and it may be copolymerized or mixed as necessary.

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

The eccentric core-sheath composite fiber of the present invention can be produced by a well-known melt spinning and composite spinning method. For example, a thermoplastic polyurethane (core) and a nylon 6 (sheath) are melted separately, supplied to a spinning module, and discharged from an eccentric core-sheath type composite spinning spinneret to form a sliver. The method for forming the eccentric core sheath structure is not particularly limited. For example, a thin sheath of nylon 6 is concentrically covered on polyurethane, and the method is compounded in parallel with the flow of the second nylon 6, or A method of coating polyurethane 6 and nylon 6 side by side, and then coating a thin sheath of nylon 6 and the like. The sliver is uniformly cooled to room temperature by a cooling device provided on the downstream side of the composite spinning spinneret, and an oil agent is applied to the yarn to take it up at a low speed. Then, it is preferable to extend by 3 to 5 times.

The melt viscosity of the thermoplastic polyurethane at 210 ° C is preferably 5,000 to 18,000 poises. Due to such a range, at the temperature of the nylon 6 spinning with the above-mentioned relative viscosity range, since the difference in melt viscosity becomes small, and the stable cross-sectional formability is achieved, the cross-sectional bending rate can be 15% or less. More preferably 8,000 to 15,000 poises.

The melt viscosity of nylon at 240 ° C is preferably 200 to 2,000 poises. By setting it as such a range, when spinning with the thermoplastic polyurethane described above, since the difference in melt viscosity becomes small, and the stable cross-sectional formability is achieved, the cross-sectional bending rate can be 15% or less. More preferably, it is 300 to 1,500 poises.

At the time of profile formation, by reducing the difference in melt viscosity between thermoplastic polyurethane and nylon 6, the curvature of the profile can be reduced, but because the actual melt viscosity in the spinning assembly cannot be measured, thermoplastic polyurethane The acid ester is based on 210 ° C and the nylon is based on 240 ° C melt viscosity. By using such a range of thermoplastic polyurethane and nylon 6, it is possible to sufficiently reduce the difference in melt viscosity 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 poises or less, and more preferably 100 poises or less.

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

By setting it as such a range, the difference in melt viscosity with nylon 6 can be reduced, and stable cross-section formation properties can be used to make the cross-section bending rate 15% or less. More preferably, it is 240 ° C or more and 245 ° C or less.

The temperature difference between the polymer of the thermoplastic polyurethane and nylon 6 is preferably set to within 10 ° C. The spinning temperature should be equal to the polymer temperature. However, if the polymer piping length and the temperature of the polymer are different after the polymer melts and before entering the spinning unit, the temperature can be reduced. The spinning temperature is set appropriately so that the polymer temperature falls within this range. By controlling the polymer temperature and the polymer temperature difference within this range, the heat transfer between the thermoplastic polyurethane and nylon 6 can be reduced inside the spinning module, and The temperature difference in the filament discharge hole portion is small, and the cross-sectional formability is stabilized, so that the cross-sectional bending ratio can be 15% or less, and the cross-sectional bending ratio CV value can be 0.40 or less.

The polymer temperature difference is preferably within 7 ° C. If the temperature difference of the polymer exceeds 10 ° C, the heat transfer will increase when forming the composite section, the bending of the interface at the core side will increase, the bending will be unstable, and the section formation will deteriorate, and the bending rate of the section will easily exceed 15%. The cross-section bending rate CV value easily exceeds 0.40.

For example, under the melting conditions described in Patent Document 1 or Patent Document 2, the spinning temperature difference between thermoplastic polyurethane and nylon 6 is 20 ° C, and the polymer temperature difference exceeds 10 ° C, so the profile cannot be made. The bending rate and the cross-section bending rate CV value fall within this range.

The temperature difference between the spinneret surfaces is preferably within 5 ° C. The surface temperature of the spinneret mentioned here is measured by measuring the center point and the outer three points of the spinneret, and calculating the difference between the maximum value and the minimum value. By setting it as this range, the cross-section curvature ratio CV value can be made into 0.40 or less.

The eccentric core-sheath composite fiber of the present invention can be preferably used for fabrics and clothing products. As the form of the fabric, woven fabrics, knitted fabrics, etc. can be selected according to the purpose, and clothing is also included. In addition, as clothing products, various clothing products such as socks, underwear, and sportswear can be used.

The eccentric core-sheath composite fiber of the present invention is preferably used for socks used in at least a part of a leg. The socks referred to here include socks products typified by tights, stockings, and socks. The so-called leg part refers to a range from a garter part to a toe in the case of pantyhose.

In addition, the knitting machine for the socks is not particularly limited, and ordinary socks knitting machines can be used. For example, a knitting machine with two or four yarn supply can be used to supply the eccentric core-sheath composite yarn of the present invention for weaving. Woven by the usual method. For example, socks-type socks knitted by supplying only the eccentric core-sheath composite yarn of the present invention, or elastic yarn as the core yarn, and a covering yarn wound with one or two layers of clothes yarn and the present invention may be mentioned. The eccentric core-sheath composite fibers are alternately supplied and woven into interwoven socks.

Examples

Hereinafter, the present invention will be described more specifically with reference to examples. The measurement methods and the like of the characteristic values in the examples are as follows.

    (1) Sulfuric acid relative viscosity of nylon 6    

0.25 g of a nylon 6 chip sample was dissolved so that 100 ml of sulfuric acid having a concentration of 98% by weight became 1 g, and an Oshwa type viscometer was used to measure the flow-down time (T1) at 25 ° C. Next, the flowing time (T2) of sulfuric acid having a concentration of only 98% by weight was measured, and the ratio of T1 to T2, that is, T1 / T2 was taken as the sulfuric acid relative viscosity.

    (2) determination of molecular weight (Mw, Mz / Mw) of thermoplastic polyurethane    

5 ml of a measurement solvent (0.05 M lithium bromide-containing dimethylformamide) was added to a 10 mg sample of a thermoplastic polyurethane chip, and the mixture was stirred at room temperature for about 60 minutes. Then, it filtered using a 0.45 micrometer membrane filter. The purified sample was measured for each molecular weight under the following conditions.

Device: GPC

Detector: Differential refractive index detector RI (Tosoh-made RI-8020, sensitivity 32)

Column: TSKgel α-M, α-3000 each (1 (7.8mm × 30cm, made by Tosoh)

Solvent: Dimethylformamide with 0.05M lithium bromide

Flow rate: 0.8mL / min

Column temperature: 0.2mL

Injection volume: 0.2mL

Standard sample: Tosoh Monodisperse Polystyrene

Data processing: TRC GPC data processing system

    (3) Melt viscosity    

Using "Flow Tester" CFT-500 made by Shimadzu Corporation, die: 1.0mm × 1.0 mm, plunger area: 1 cm ² , temperature: 210 ° C. (thermoplastic polyurethane), 240 ° C. (nylon 6), time: 4 minutes, load: 200 N, sample amount: 1 g.

    (4) Fineness    

Set the fiber sample at a length measuring device of 1.125m / week, make it 200 turns to make a loop-shaped skein, and dry it in a hot air dryer (105 ± 2 ℃ × 60 minutes). Then measure the quality of the skein with a balance. The fineness is calculated from the value multiplied by the constant moisture content. Furthermore, the core-sheath composite yarn has a nominal moisture content of 4.5%.

    (5) Strength, elongation    

The fiber sample was measured using "TENSILON" (registered trademark) UCT-100 manufactured by ORIENTEC, under constant speed elongation conditions shown in JIS L1013 (Chemical Fiber Silk Yarn Test Method, 2010). The elongation is calculated from the elongation at the point showing the maximum strength in the tensile strength-elongation curve. The intensity is 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) Section bending rate         A. Shooting of section photos    

An embedding agent consisting of paraffin, stearic acid, and ethylcellulose is dissolved. After the fiber is introduced, it is allowed to stand at room temperature to cure. The yarnmaker took a cross section of the fiber with a CCD camera (CS5270) made by Tokyo Electron Co., Ltd. and printed it at 1500 times with a color video processor (SCT-CP710) made by Mitsubishi Electric.

    B. Measurement of section curvature    

Using the following procedures (a) to (e), the cross sections of all the filaments of the four eccentric core-sheath composite fibers were measured, and the average value was used as the cross-section bending rate. Hereinafter, it will be described using FIG. 2.

(a) In the cross section of the fiber, the tangent line A is drawn at the most convex point (point a) at the composite interface between the thermoplastic polyurethane and the polyamide.

(b) Draw a line B parallel to the line A and connecting the two points (points b-1 and b-2) at which the inner diameter of the core becomes the largest.

(c) Draw a line C (point B-3) between the connection point a and the middle point (point b-3) of the two points (point b-1, point b-2) where the inner diameter of the core becomes the largest.

(d) Let the intersection point of the line C and the fiber surface which is close to the point a be the point c, and the intersection point with the other fiber surface be the point d.

(e) Section curvature = (length of point a-point b-3 / point c-point d length) / 100

    (7) CV value of section curvature    

The cross-section bending rate 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-section bending rate CV value.

Section bending rate CV value = standard deviation of section bending rate σ / average of section bending rate

    (8) Stretch elongation    

The stretch elongation is based on 5.7 method C (simple method) of JIS L1090 (Test Method for Synthetic Filament Bulk Processing Yarn), and is the stretch elongation by the formula shown below.

Stretch elongation (%) = [(L1-L0) / L0] × 100%

L0: Hanging on the fiber skein with 0.0018 cN / dtex load, hot water treatment at 90 ° C for 20 minutes, air-spinning length after day and night

L1: After the measurement of L0, remove the measurement load of L0, hang the load of 0.09cN / dtex, and the skein length after 30 seconds

    (9) Sock making method    

Four eccentric core-sheath composite fibers were used for the leg yarns, and they were woven into a flat-knit structure with a Super 4 knitting machine (400 needles) made by Nagada Seiki Co., Ltd. to obtain a grey fabric for socks.

Next, the grey fabric was pre-shaped in the order of 90 ° C. steam and 100 ° C. pressurized steam in a suspended state, and then the lower part of the crotch and the toe part were sewn.

After thoroughly washing and removing the oil from the fiber, apply brown coloring and softening treatment to the general color of the pantyhose at 95 ° C for 40 minutes, and then cover the general foot model, and final shape at 110 ° C for 15 seconds. Get socks.

    (10) Quality evaluation of socks    

The socks produced in the above (9) were evaluated on a 4-level scale using the following criteria, and Δ or higher was considered acceptable.

◎: No streaks, high quality

○: almost no streaks, good quality

△: There are some streaks, but there is no problem in quality

×: Streaks are clearly visible, low quality

    (11) Evaluation of soft stretch of socks    

The socks produced in the above (9) were evaluated on a 4-level scale using the following criteria, and Δ or higher was considered acceptable.

◎: Very good

○: Good

△: Slightly good

×: poor

    [Example 1]    

Thermoplastic polyurethane with diisocyanate as diphenylmethane diisocyanate, polyol as two components of polyester polyol and polycarbonate polyol, and chain extender as 1,4-butanediol (weight The average molecular weight (Mw) = 114,000, Mz / Mw = 2.0, and melt viscosity = 8,000 poise) were used as cores. In addition, at the time of polymerization, 0.25% by weight of a hindered phenol-based stabilizer Irganox1010 (manufactured by BASF Japan) and 0.25% by weight of Irganox1330 (manufactured by BASF Japan) were added as heat-resistant agents.

Here, a sheath portion was made of nylon 6 having a sulfuric acid relative viscosity of 2.20.

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 assembly was thermoplastic polyurethane: 238 ° C, nylon 6: 246 ° C. An eccentric core-sheath composite spinning spinneret (round hole, 8 hole) was used to perform melt discharge at a core thermoplastic polyurethane / sheath nylon 6 weight ratio of 50/50. The temperature of the spinneret surface was an average of 226 ° C and a difference of 1.7 ° C.

The sliver discharged from the spinneret was cooled and solidified by a sliver cooling device, and the oil solution was applied (oiled), and the sliver was wound at 600 m / min. Then, it was stretched to 4.29 times by an elongator, and an eccentric core-sheath composite monofilament (18 monofilament) of 18 dtex and 1 filament was wound on a bobbin to obtain 8 pieces. The yarn had a strength of 3.8 cN / dtex and a elongation of 44%. The obtained eccentric core-sheath composite monofilament had a cross-section bending rate of 8.0%, a cross-section bending rate CV value of 0.20, and a stretching elongation rate of 115%.

Using the obtained eccentric core-sheath composite monofilament, the sock was produced with almost no streaks and good quality (○). In addition, the soft stretchability was also good (○).

    [Example 2]    

Except that the weight average molecular weight (Mw) of the thermoplastic polyurethane was set to 130,000 (Mz / Mw = 2.0, melt viscosity = 9,500 poise), spinning was performed in the same manner as in Example 1 to obtain 18 dtex, 1 Filament eccentric core sheath composite monofilament.

The obtained eccentric core-sheath composite monofilament had a cross-section bending rate of 10.0%, a CV value of 0.20, and a stretching elongation of 105%.

Using the obtained eccentric core-sheath composite monofilament, the sock produced had almost no streaks and was of good quality (○). In addition, the soft stretchability was also good (○).

    [Example 3]    

Spin spinning was performed in the same manner as in Example 1 except that the weight average molecular weight (Mw) of the thermoplastic polyurethane was 150,000 (Mz / Mw = 2.5, melt viscosity = 11,500 poise), and 18 dtex, 1 Filament eccentric core sheath composite monofilament.

The obtained eccentric core-sheath composite monofilament had a cross-section bending rate of 12.5%, a CV value of 0.30, and a stretching elongation of 100%.

Using the obtained eccentric core-sheath composite monofilament, although the sock produced had some stripes, the quality was not a problem (Δ). The soft stretchability was also slightly good (Δ).

    [Example 4]    

Except that the weight average molecular weight (Mw) of the thermoplastic polyurethane was 180,000 (Mz / Mw = 2.8, melt viscosity = 14,000 poise), spinning was performed in the same manner as in Example 1 to obtain 18 dtex, 1 Filament eccentric core sheath composite monofilament.

The obtained eccentric core-sheath composite monofilament had a cross-section bending rate of 14.5%, a CV value of 0.35, and a telescopic elongation rate of 93%.

Using the obtained eccentric core-sheath composite monofilament, although the sock produced had some stripes, the quality was not a problem (Δ). The soft stretchability was also slightly good (Δ).

    [Example 5]    

Except that the weight average molecular weight (Mw) of the thermoplastic polyurethane was set to 80,000 (Mz / Mw = 1.9, melt viscosity = 5,000 poise), spinning was performed in the same manner as in Example 1 to obtain 18 dtex, 1 Filament eccentric core sheath composite monofilament.

The obtained eccentric core-sheath composite monofilament had a cross-section bending rate of 5.0%, a CV value of 0.18, and an expansion and contraction elongation of 120%.

Using the obtained eccentric core-sheath composite monofilament, the sock produced was high-quality (◎) without streaks. In addition, soft stretchability was also very good (◎).

    [Example 6]    

Melt thermoplastic polyurethane chips at a spinning temperature (set value) of 247 ° C, melt nylon 6 chips at a spinning temperature (set value) of 255 ° C, and polymer temperature (measured value) before entering the spinning assembly It is a thermoplastic polyurethane: 240 ° C, nylon 6: 246 ° C. The temperature of the spinneret surface was an average of 227 ° C and a difference of 1.8 ° C. Except that the melting conditions of the thermoplastic polyurethane were changed, spinning was performed in the same manner as in Example 1 to obtain an eccentric core-sheath composite monofilament of 18 dtex and 1 filament.

The obtained eccentric core-sheath composite monofilament had a cross-section bending rate of 5.0%, a CV value of 0.18, and an expansion and contraction elongation of 120%.

Using the obtained eccentric core-sheath composite monofilament, the sock produced was high-quality (◎) without streaks. In addition, soft stretchability was also very good (◎).

    [Example 7]    

The thermoplastic polyurethane chip was melted at a spinning temperature (set value) of 252 ° 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 assembly was thermoplastic polyurethane: 244 ° C, nylon 6: 246 ° C. The spinneret temperature was an average of 229 ° C and a difference of 0.8 ° C. Except that the melting conditions of the thermoplastic polyurethane were changed, spinning was performed in the same manner as in Example 1 to obtain an eccentric core-sheath composite monofilament of 18 dtex and 1 filament.

The obtained eccentric core-sheath composite monofilament raw yarn had a cross-section bending rate of 3.0%, a CV value of 0.15, and a stretching elongation of 125%.

Using the obtained eccentric core-sheath composite monofilament, the sock produced was high-quality (◎) without streaks. In addition, soft stretchability was also very good (◎).

    [Example 8]    

Except that the weight average molecular weight (Mw) of the thermoplastic polyurethane was set to 80,000 (Mz / Mw = 1.9, melt viscosity = 5,000 poise), spinning was performed in the same manner as in Example 7 to obtain 18 dtex, 1 Silk eccentric core sheath composite monofilament.

The obtained eccentric core-sheath composite monofilament had a cross-section bending rate of 1.0%, a CV value of 0.10, and a telescopic elongation rate of 130%.

Using the obtained eccentric core-sheath composite monofilament, the sock produced was high-quality (◎) without streaks. In addition, soft stretchability was also very good (◎).

    [Example 9]    

Except that nylon 6 had a sulfuric acid relative viscosity of 2.00 (melt viscosity = 300 poise), spinning was performed in the same manner as in Example 8 to obtain an eccentric core-sheath composite monofilament of 18 dtex and 1 filament.

The obtained eccentric core-sheath composite monofilament had a cross-section bending rate of 1.0%, a CV value of 0.10, and a stretching elongation of 120%.

Using the obtained eccentric core-sheath composite monofilament, the sock produced was high-quality (◎) without streaks. In addition, soft stretchability was also very good (◎).

    [Example 10]    

Except that nylon 6 had a sulfuric acid relative viscosity of 2.30 (melt viscosity = 1500 poise), spinning was performed in the same manner as in Example 7 to obtain an eccentric core-sheath composite monofilament of 18 dtex and 1 filament.

The obtained eccentric core-sheath composite monofilament had a cross-section bending rate of 10.0%, a CV value of 0.30, and a telescopic elongation rate of 103%.

Using the obtained eccentric core-sheath composite monofilament, the sock was produced with almost no streaks and good quality (○). In addition, the soft stretchability was also good (○).

    [Comparative Example 1]    

Except that the weight average molecular weight (Mw) of the thermoplastic polyurethane was set to 250,000 (Mz / Mw = 3.1, melt viscosity = 21,000 poise), spinning was performed in the same manner as in Example 1 to obtain 18 dtex, 1 Filament eccentric core sheath composite monofilament.

The obtained raw yarn had a cross-section bending rate of 19.0%, a CV value of 0.45, and an elongation of 80%. That is, it can be seen that the interface at the core side has a large curvature, the coil-shaped curl is thin and uneven, and the curl characteristics are low.

Using the obtained eccentric core-sheath composite monofilament, the sock system produced can clearly see the stripes, and has low quality (×). In addition, soft stretchability is also poor (×).

    [Comparative Example 2]    

The thermoplastic polyurethane chip was melted at a spinning temperature (set value) of 236 ° 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 assembly was thermoplastic polyurethane: 230 ° C, nylon 6: 246 ° C. The temperature of the spinneret surface was an average of 225 ° C and a difference of 6.2 ° C. Except that the melting conditions of the thermoplastic polyurethane were changed, spinning was performed in the same manner as in Example 1 to obtain an eccentric core-sheath composite monofilament of 18 dtex and 1 filament.

The obtained eccentric core-sheath composite monofilament had a cross-section bending rate of 23.0%, a CV value of 0.55, and an expansion and contraction elongation of 80%. That is, it can be seen that the interface at the core side has a large curvature, the coil-shaped curl is thin and uneven, and the curl characteristics are low.

Using the obtained eccentric core-sheath composite monofilament, the sock system produced can clearly see the stripes, and has low quality (×). In addition, soft stretchability is also poor (×).

    [Comparative Example 3]    

The thermoplastic polyurethane chip was melted at a spinning temperature (set value) of 230 ° C, and the nylon 6 chip was melted at a spinning temperature (set value) of 250 ° C. The polymer temperature (measured value) before entering the spinning assembly was thermoplastic polyurethane: 225 ° C, nylon 6: 242 ° C. The temperature of the spinneret surface was an average of 224 ° C and a difference of 7.5 ° C. Except that the melting conditions of the thermoplastic polyurethane were changed, spinning was performed in the same manner as in Example 1 to obtain an eccentric core-sheath composite monofilament of 18 dtex and 1 filament.

The obtained eccentric core-sheath composite monofilament had a cross-section bending rate of 24.5%, a CV value of 0.55, and an expansion and contraction elongation of 80%. That is, it can be seen that the interface at the core side has a large curvature, the coil-shaped curl is thin and uneven, and the curl characteristics are low.

Using the obtained eccentric core-sheath composite monofilament, the sock system produced can clearly see the stripes, and has low quality (×). In addition, soft stretchability is also poor (×).

Specific aspects have been used to describe the present invention in detail, but various changes and modifications are possible without departing from the intention and scope of the present invention, which is clearly known to those skilled in the art. In addition, this application is based on the Japanese invention patent application (Japanese Patent Application No. 2017-123316) filed on June 23, 2017, and the entire system is cited by reference.

Claims (4)

    An eccentric core-sheath composite fiber, the core component of which is a thermoplastic polyurethane, and the sheath component is nylon 6. The eccentric core-sheath composite fiber is characterized in that the section bending rate is 15% or less, and the section bending rate is CV value. It is 0.40 or less.         For example, the eccentric core-sheath composite fiber of claim 1 has a stretching elongation of 90% or more.         A knitted fabric having an eccentric core-sheath composite fiber as claimed in claim 1 or 2 in at least a portion.         A sock (stocking) having at least a part of a leg having an eccentric core-sheath composite fiber as claimed in claim 1 or 2.