JPH0411021A - Conjugate fiber and stockings - Google Patents

Abstract

PURPOSE:To obtain a conjugate fiber having excellent stretchability, post- processability, dyeability, etc., and giving stockings giving comfortable feeling to the skin and excellent transparent appearance by using a polyamide as a sheath component and a polyurethane as a core component and conjugating the sheath and core components in concentric state at a specific conjugation ratio. CONSTITUTION:The objective conjugate fiber is produced by using a polyamide (e.g. a nylon 6, etc., preferably having a relative viscosity of <=2.3 and a melting point of <=220 deg.C) as a sheath component and a polyurethane (preferably having a Shore A hardness of 60-95) as a core component and carrying out conjugate spinning of the components at a core/sheath conjugation ratio (cross-sectional ratio) of 3-90 in concentric state (in cross-section) in such a manner as to satisfy the formula [(crosslinking density of polyurethane of the core component) >=-8.7X(conjugation ratio) +52 (mumol/g). A conjugate fiber having further improved recoverability, heat-resistance, etc., can be produced by using a thermoplastic polyurethane or crosslinked polyurethane as the polyurethane component.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a novel composite yarn made of polyamide and polyurethane and stockings thereof.

(Prior Art) Polyurethane elastic threads have been used for various purposes because of their special functions. However, on the other hand, this yarn has extremely poor high-order processability due to its high coefficient of friction.
It is also known that the finished product has poor touch, dyeability and color fastness. Therefore, products using only polyurethane elastic threads are rarely seen because the manufacturing process is extremely difficult.

In order to compensate for these drawbacks, polyurethane elastic threads are covered with nylon threads, or threads with a core-sheath structure made of polyamide-based polymers such as polycapramide and polyurethane are crimped and the covering process is omitted (Tokuko Kouko 5).
5-27175), a polyurethane composite fiber with an eccentric structure and a crosslinked polyurethane elastic body in the core (
Japanese Patent Publication No. 118619 is also known.

In addition, for stockings, the elastic properties, especially the fit to the feet, are important, so 14
! Covering yarns are used, such as crimped yarns, latent crimped yarns created by the conjugate method, and polyurekne elastic yarns wrapped with nylon6. A polyurethane-based composite fiber (Japanese Patent Publication No. 1-118619) has been proposed that uses omitted thread (Japanese Patent Publication No. 55-2.7175), eccentric structure, and a polyurethane elastic body crosslinked in the core.

On the other hand, polyurethane elastic yarn has been considered to be knitted into stockings using the so-called bare system due to its excellent elastic properties, but it has not been put to practical use because of the fatal drawbacks described below.

(Problems to be solved by the invention) Polyurethane elastic yarn stretches with a small force and has a high coefficient of friction, making it difficult to handle the yarn in the subsequent process and even under strict control, the yarn breaks and two stitches occur. Problems such as ground spots are always present.

Therefore, in order to reinforce the polyurethane elastic thread and make the thread easier to handle, covering threads, in which nylon threads are wrapped around polyurethane threads, have been devised and are used for many purposes such as stockings.However, covering threads Compared to using urethane bare thread, the thread becomes thicker by the amount of thread that is wound, and when knitted into stockings, the product becomes thick and lacks transparency.Also, the covering method requires that process, The problem is that the production speed is extremely slow.

On the other hand, eccentric core-sheath yarns made of polycabramide and polyurethane have the disadvantage that they require a stretching-relaxation treatment step to generate crimp restoring force, and that this restoring force is weak because it is caused by crimp. Furthermore, careful attention must be paid to the uniformity of this crimp.

In addition, stockings made of this yarn lack transparency, and the knitted fabric has a poor grain surface, resulting in poor appearance when worn.

Therefore, if bare elastic polyurethane yarn can be knitted into stockings, stockings with excellent transparency and elasticity can be made without requiring many steps. However, although various yarns are currently used as stocking threads, they all utilize the elasticity of covering or crimped structures, and are made of yarns with a linear structure that can be dyed with stretchable elastic yarns. The reality is that there are still no stockings with beautiful stitches and excellent transparency.

An object of the present invention is to provide a novel composite yarn which has excellent stretchability and elasticity, and also has good post-fire processability and dyeability. The second purpose of the present invention is to obtain new properties that are completely different from those of stockings made using bare polyurethane yarns, and to create new stockings that have excellent elasticity, heat resistance (8), feel to the touch when worn, and (i3) brightness. It is on offer.

(Means for Solving the Problems) The present inventors have arrived at the present invention as a result of intensive studies to achieve the above object in view of the current situation.

That is, the composite yarn of the present invention is a composite yarn having a polyamide sheath and a polyurethane core, and has a core/sheath composite ratio (X
) is 3 to 9o in terms of cross-sectional area ratio, ・Crosslinking density Y of polyurethane in the core component (μmol/
g) and the composite ratio
・In the cross-sectional shape of the composite yarn, each center of the core and sheath is the same. In addition, the stockings of the present invention are composite yarns having a polyamide sheath and a thermoplastic polyurethane or crosslinked polyurethane core, wherein the core/sheath composite ratio is 3 to 9o in terms of cross-sectional area ratio, A special feature is that a composite yarn is used in which the center points of each core-sheath are essentially the same in the cross-sectional shape of the composite yarn.

The polyurethane that is the core component of the present invention is a polymer obtained by, for example, reacting a polymeric diol with an organic diisocyanate and a chain extender, and is a segmented polyurethane having urethane bonds and urea bonds in the molecule.

Examples of the polymeric diol include polytetramethylene glycol having a hydroxyl group at both ends and a molecular weight of 500 to 5,000;
These include glycols such as ether polyols such as polypropylene glycol, ester polyols such as polyhexamethylene glycol, polybutylene adipate, polycarbonate diol, and polycaprolactone diol, and mixtures thereof. Examples of the chain extender include 1,4-butanediol, ethylene glycol, propylene glycol, and bishydroxyethoxybenzene having a molecular weight of 500 or less. As the organic diisocyanate, tolylene diisocyanate (TDI), 4.4'
-diphenylmethane diisocyanate (MDI), or non-yellowing diisocyanates such as 1,6-hexane diisocyanate, and mixtures thereof.

The Situ A hardness of the polyurethane is preferably in the range of 60 to 95. If the hardness is less than 60, problems such as poor recovery power of the resulting yarn and poor spinning stability occur, so it is not preferable. On the other hand, if the hardness exceeds 95, the recovery performance of the polyurethane itself is poor, and the recovery power of the yarn cannot be expected unless it is based on a crimped structure, and there are also problems such as the range of optimal spinning conditions for polyurethane of this hardness is extremely narrow. 65-9, more preferably 65-9
It is also preferable to add titanium oxide, an ultraviolet stabilizer, an ultraviolet absorber, an antibacterial agent, etc. to such polyurethane, which is preferably in the range of 0.

In addition, if further heat resistance, recovery properties, etc. are required as a composite yarn, a cross-linked polyurethane obtained by reacting a polyisocyanate compound with the above-mentioned polyurethane may be placed as a core component. It is a compound consisting of a polyol component and an isocyanate component, and having two or more, preferably two to three, isocyanate groups in the molecule. As the polyol component, in addition to the above-mentioned diols with a molecular weight of 300 to 4,000 used in the synthesis of polyurethane, there may also be a mixture of diols and triols with an average functionality of 2 to 3, or a synthetic polyol with a functionality of 2 to 3. It can be suitably used. For example, in addition to the diols used in the synthesis of the thermoplastic polyurethane, trifunctional polyols such as polycaprolactone polyester triol, monopolycondensation polyester triol, polyether triol 1, and mixtures thereof can be used. Furthermore, polycondensation polyester polyols having a functionality in the range of 2 to 3 can also be suitably used.

On the other hand, as the isocyanate component, the above-mentioned diisocyanates used in polyurethane synthesis, trimers of organic diisocyanates, reaction products of trimethylolpropane and organic diisocyanates, or isocyanates with a functionality in the range of 2 to 3 (e.g. , MDI-modified products such as carbodiimide-modified isocyanate), and mixtures thereof can be used.

The above-mentioned two components can be reacted by known methods, but in the case of the present invention, in order to have an excessive content of isocyanate groups,
That is, the amount of isocyanate groups (NCO groups) in the reactant is 2
It is preferable to carry out the reaction so that the concentration is 22% to 22%. Of course, this amount varies depending on the desired physical properties such as heat resistance and recovery properties and the polyol used, and is selected as appropriate.

The amount of the polyisocyanate compound added varies depending on the NCO group content and type of the polyisocyanate compound used, but is 40% by weight based on the mixture of the polyurethane used as the core component and the polyisocyanate compound contained.
The following ranges are preferred. If the amount added is too large, the spinning becomes unstable due to uneven mixing, and the mechanical properties of the yarn are unsatisfactory, which is undesirable.
A crosslinked structure consisting mainly of allophanate crosslinks is formed in the polyurethane in the core component.

Examples of the polyamide used in the present invention include, for example,
Examples include nylon 6 and nylon 66. Nylon 6 uses 98% sulfuric acid at 100mj! 1g of nylon sample
It is particularly preferable to have a relative viscosity of 2.3 or less when measured at 25°C, and a melting point of 2.2 or less when measured by DSC.
Modified product of nylon 66 below 0°C, nylon 8. Nylon9. Nylon 10. Nylon 11. Nylon 12 grade,
Also nylon 6/66. In addition to binary copolymers such as nylon 6/12, ternary copolymers such as nylon 6/12/10, multicomponent copolymers, and mixtures thereof can also be suitably used. If the melting point exceeds 220°C, the melt stability and heat resistance of the core component polyurethane will be poor.
This is not desirable because the melt viscosity balance will shift during composite spinning and the recovery power of the obtained yarn will also be low.In the present invention, it is also possible to add a light stabilizer, a matting agent such as titanium oxide, an antibacterial agent, etc. to the polyamide. be.

The core-sheath components have been described above, and next, the composite ratio of the core-sheath components will be described.

The composite ratio (X) of the core/sheath component is preferably in the range of 3 to 90 in terms of cross-sectional area ratio.When the ratio of the sheath component is 3 or less, the resulting yarn has improved elastic recovery properties, recovery properties from high temperatures, Heat resistance is insufficient. On the other hand, if this ratio is 90 or more, the sheath component is likely to be torn or the core component is likely to be exposed on the yarn surface, which is not preferable since it will have an adverse effect on spinnability and light resistance.

In order to have a sufficient function as a composite yarn, not only the above composite ratio but also the crosslinking density of polyurethane in the core component is important for the present invention, and the core/sheath ratio X and this crosslinking density Y (μmol / g), Y≧-8,7
It must be constructed so that the inequality X X + 52 holds true. In other words, when the crosslinking density is low, it is necessary to increase the ratio of the core component according to the above formula;
When the density is high, the range of application of the composite ratio can be expanded. Yarns constructed so as not to satisfy this formula are undesirable because their function as composite yarns, such as their recovery properties, are poor.

The crosslinking density referred to in the present invention is the crosslinking density of polyurethane in the core component, and in this measurement method, first, the polyurethane after dissolving the sheath component with formic acid or the like is used as a sample. Then, the method of Detection et al. (Journal of Polymer Science: Polymer Letters Ediciron: No. 17)
Vol., p. 175 (1979)) and "Synthesis, compounding, functionalization, and application development of the latest polyurethanes," Technical Information Association Publishing, p. 94 (1989 edition), "Correlation between deterioration behavior of crosslinked polyurethane rubber and chemorheology." Measurements were made with reference to Murakami's method described in ``. That is, polyurethane Ig
was dissolved in a dimethyl sulfoxide solution containing 20 micromol/g of n-butylamine at 23°C for 24 hours, and then dissolved in a 1/25N hydrochloric acid-methanol solution using bromophenol blue as an indicator to dissolve n- Butylamine was back titrated and the density was determined using the following formula.

VO1-VOXW2/Wl Crosslinking density (micromol/g) Wl: Weight of decomposition liquid in sample digestion (g) W2: Weight of charged decomposition liquid in sample decomposition (g) vO: Titration amount required for blank test (ml) VIO: Blank test titer (#1) in sample digestion ■S
; Titration amount (ml) in sample digestion fHcTE titer (-
) NHCI: Standard concentration (standard) At this time, a core component with a crosslinking density that cannot be dissolved by such a method may be considered, but such a system can also be suitably used if it has good spinnability. Of course.

As for the composite form of the core-sheath, it is preferable that the centers of both the core-sheath components are substantially the same from the viewpoint of the quality of the spinning chamber and the uniformity of the obtained yarn, and the cross-sectional shape of the composite yarn is It doesn't matter if it's circular or irregularly shaped.

Among these, a composite form consisting of concentric circles is particularly preferred.

What is important in the present invention is that the sheath of the composite yarn completely covers the core and the center points of the sheath and the core are mainly the same, so even if the viscosity balance and composite ratio of the core and sheath components are slightly different, the yarn can still be spun. This is a very good thing.

This is a feature not found in yarns having an eccentric cross-sectional shape.

Next, a method for manufacturing a composite yarn of the present invention will be explained.

Carrying out the process using a melt composite spinning apparatus equipped with a part that melt-extrudes thermoplastic polyurethane, a part that adds and mixes the polyisocyanate compound, a part that melt-extrudes the sheath component, and a spinning head that has a known core-sheath type composite spinneret. is suitable. A known device can be used to add the polyisocyanate compound during spinning. Although it is possible to use a kneading device with a rotating part in the part where the polyisocyanate compound is added to and mixed with the molten polyurethane, it is more preferable to use a mixing device with a stationary kneading element. . A known mixing device having a stationary kneading element can be used. The shape and number of elements of the stationary kneading element vary depending on the conditions of use, but are selected so that sufficient mixing of the thermoplastic polyurethane elastomer and the polyisocyanate compound is completed before entering the composite spinneret. It is important to do so, and usually 2
0 to 90 elements are provided. The composite yarn of the present invention can be obtained by using polyurethane mixed with a polyisocyanate compound as a core component, melting polyamide as a sheath component using a separate extruder, and introducing both into a known core-sheath composite die for spinning. can get.

Immediately after spinning and winding, the composite yarn has poor physical properties such as strength and heat resistance, but when left at room temperature for 2 hours to 7 days, the physical properties improve significantly, and the core-sheath adhesion improves. It also improves. The yarn quality and thermal performance of composite yarns spun in this way change over time because the reaction of the polyisocyanate compound mixed with the thermoplastic polyurethane elastomer used as the spinning raw material is completed during spinning. This is presumed to be due to the fact that it progresses even after spinning. This reaction is the production of branched or crosslinked polymers due to allophanate bonds between polyurethane and polyisocyanate compounds, and the improvement in adhesion with the sheath component is due to amino groups, amide groups in polyamide,
This is thought to be a reaction between the carboxyl group and the polyisocyanate compound.

It is also possible to draw the composite yarn immediately after spinning, but in this case, the water conduction shrinkage rate becomes large.

Examples of embodiments of the method for manufacturing the composite yarn and stockings of the present invention will be described below.

A pellet of thermoplastic polyurethane elastomer is supplied from a hopper and heated and melted in an extruder. Melting temperature is 190-2
A range of 30°C is preferred.

On the other hand, the polyisocyanate compound is
It is melted at a temperature of 0°C or lower and defoamed beforehand. If the melting temperature is too high, the quality of the polyisocyanate compound will change, so it is desirable that it is as low as possible within the melting range, and a temperature between room temperature and 100°C is used as appropriate. The molten polyisocyanate compound is metered by a metering pump, filtered if necessary by a filter, and added to the molten polyurethane at a meeting point provided at the tip of the extruder.

The polyisocyanate compound and polyurethane are kneaded using a kneading device having a stationary kneading element. This mixture is metered by a metering pump and introduced into the spinning head. It is preferable that the spinning head is designed to have a shape that minimizes the retention area of the mixture as much as possible.If necessary, after removing foreign substances using a filtering layer such as a wire mesh or glass beads in a filtration layer provided in the spinning head, the mixture is removed from the sheath. It is bonded to a polyamide-based polymer as a component in a core-sheath type, then discharged from a die, cooled in air, coated with oil, and then rolled up. 1! The scraping speed is usually 400 to 1500 m/min.

The strength of the composite elastic yarn wound onto a spinning bobbin may be poor immediately after spinning, but if it is left at room temperature (for example, 2
(hours to 6 days), and the recovery properties from elongation at high temperatures are also improved.

Further, by applying heat treatment by an appropriate method after spinning, improvement of yarn quality and thermal properties is promoted.

The yarn quality and thermal performance of the spun composite elastic yarn change over time because the reaction of the polyisocyanate compound mixed with the thermoplastic polyurethane elastomer used as the spinning raw material is completed during spinning. It is presumed that this is because the process continues even after spinning without any process. This reaction is the production of branched or crosslinked polymers due to allophanate bonds between polyurethane and polyisocyanate compounds, and the improvement in adhesion with the sheath component is due to the amino groups in the polyamide polymer,
A reaction between an amide group or a carboxyl group and a polyisocyanate compound is also considered.

Using the obtained composite yarn, stockings can be easily manufactured using a conventional method, for example, using a four-pitch sewing machine. Further, the dye is preferably an acid dye, a basic dye, or a disperse dye.

In addition, the stockings referred to in the present invention include stockings knitted by not only using the composite yarn of the present invention alone but also knitting with ordinary nylon yarn false twisted yarn 5 polyurethane covering yarn, or by knitting these yarns together. This includes over-the-knee stockings that reach above the knee, full-length stockings that extend to the thighs, and pantyhose that combine the panty and stocking parts.

(Effects of the present invention) As described above, since the yarn of the present invention has a sheath component of polyamide and a core component of polyurethane, it has very good recovery properties as well as dyeability. In other words, the sheath component is polyamide, and conventionally it was impossible to expect elasticity, but by using polyurethane as the core component and compounding it into a specific shape as in the present invention, it surprisingly has elasticity. It can have excellent performance such as having elastic properties rather than a crimped structure, and having little permanent set and high recovery power when 100% elongated. Furthermore, in the case of a structure in which a polyisocyanate compound is blended on the core component side, not only the recovery property 7 and heat resistance but also the adhesion between the core and sheath components are improved because the reaction proceeds at these interfaces.

The yarn of the present invention is also characterized by its complete absence of stiction. Even in the subsequent process, since the core is completely covered with the sheath and the sheath is made of polyamide, it is extremely easy to take out the warp, which is impossible with polyurethane elastic yarn.

In addition, when spinning and winding, an inexpensive emulsion oil can be used1, and it is also possible to wind the fibers at high speeds such as 1000 m/min, and onto small-diameter bobbins or paper tubes. Productivity is also advantageous for industrial production since it is a melt spinning method.

Since the composite yarn of the present invention has excellent characteristics, it can be used for various purposes such as stockings, swimwear, and inner socks.

For example, the stockings of the present invention are characterized by being much more transparent than conventional stockings, having a superior appearance, and being soft to the touch.

Next, preferred embodiments of the present invention will be summarized and described.

(a) The polyamide has a relative viscosity of 2.3 or less and/or a polyamide melting point of 220'c or less (
1) Composite yarn as described.

(b) The composite yarn according to claim (1), wherein the polyurethane has a Situ A hardness of 60 to 95.

(c) The composite yarn according to claim (1), wherein the polyurethane is crosslinked by a polyisocyanate compound.

(d) Claim (1) wherein the adhesion between the core component and the sheath component is enhanced by the polyisocyanate compound in the core component.
Composite yarn as described.

(e) The composite yarn according to claim 1, wherein the polyisocyanate compound has a functionality of 2 to 3.

1) The composite yarn according to claim 1, which has a permanent set of 25% or less when 100% elongation is repeated twice at room temperature.

(G) When 100% elongation is repeated twice, the second 5
The composite yarn according to claim 1, wherein the return strength at 0% elongation is 0.41 times or more the previous strength at the second 50% elongation.

(h) The melting point of the polyamide polymer on DSC is 80°C
Stockings using the composite yarn according to claim 2, which has a temperature of ~220°C or a relative viscosity of 2.3 or less.

(2) Stockings using elastic yarn according to claim 2, wherein the thermoplastic polyurethane has a hardness of 60 to 95.

(2) A stock-knocking method using the composite yarn according to claim (2), wherein the polyisocyanate compound has a functionality of 2 to 3.

(2) Stockings using the composite yarn according to claim 2, wherein the weight amount of NCO groups in the polyisocyanate compound is 22% by weight.

(E) Claim (2) wherein the adhesion between the core component and the sheath component is enhanced by the polyisocyanate compound in the core component.
Stockings made of the composite yarn described.

(W) A claim in which the expansion and contraction behavior of the composite yarn is not due to the crimped structure but mainly due to the properties of the yarn itself (
2) Stockings using the composite yarn described above.

(Example) Hereinafter, the present invention will be specifically explained with reference to Examples.

Example Topolyurethane Polyhexamethylene adipate with a molecular weight of 2010 and p,
A thermoplastic polyurethane having a hardness of 85 was synthesized by a conventional method using p'-diphenylmethane diisocyanate and 1,4-butanediol as a chain extender.

- Polyisocyanate compound Polybutylene adipate polyol having a molecular weight of 1050 and a functionality of 2.0 was reacted with p,p'-diphenylmethane diisocyanate so that NC0% was 6.8% by weight to obtain a polyisocyanate compound.

- Polyamide A nylon 6/66 copolymer having a melting point of 205° C. (manufactured by Ube Industries, Ltd.: 5013B) was used.

The above thermoplastic polyurethane is melted using an extruder, and the above polyisocyanate compound is added during the flow of the melt, and then thoroughly kneaded using a 35-element static mixer (manufactured by K-EX). Melt them using an extruder, weigh them separately, and put them into a concentric 8-hole composite nozzle (nozzle diameter 0.5 mm).
led to.

The spinning speed was 600 m/min to obtain a monofilament with a fineness of 40 d. In addition, a yarn in which no polyisocyanate compound was added was also spun in the same manner.

In Table 1, which shows the composite ratio and the polyurethane content in the core component, 5R-II is the value calculated by the following formula when the yarn is stretched twice at 100% at room temperature. , the larger this value is, the better the recovery performance is.

5R-n (%) Former strength at the second 50% elongation x 100 Heat resistance means that when a load of 10 mg/d is applied to the yarn,
When measured at a heating rate of 70°C/min, the yarn
Represents the temperature when elongated by %.

From Table 1, it can be seen that as the crosslinking density of the core component and the composite ratio increase, the heat resistance 1 recovery property improves.

When pantyhose were manufactured using the yarn of the present invention (Examples 1-1 to 1-4) using a four-slit machine, the results showed that, unlike conventional pantyhose, they had excellent transparency, stitch surface, and elasticity. It was good. Furthermore, even when these stockings were worn for a long time, the core-sheath components did not peel off and the adhesion was good.

Example 2 The hardness of polyurethane in the core component was changed, and the core-sheath composite ratio was 10.
．． Spinning was carried out under the same conditions as in Example 1 except that the crosslink density in the core component was 14 micromol/g.

The results are shown in Table 2.

Table 2 From Table 2, the hardness of polyurethane becomes too high,
If it becomes too low, spinnability and elongation recovery will be poor, which is not preferable.

Example 3 The above thermoplastic polyurethane and polyamide were melted in an extruder, weighed separately, and introduced into a concentric composite nozzle configured such that the thermoplastic polyurethane was the core and the polyamide was the sheath, and the spinning speed was 1000 m. /min to obtain a monofilament (Yarn A) with a core/sheath composite ratio of 10 in terms of volume ratio and a fineness of 20 denier.

On the other hand, the above-mentioned polyisocyanate compound was added during the process of melting the thermoplastic polyurethane in an extruder and introducing it into the composite die, and after sufficiently kneading it with a 40-element static mixer (manufactured by Kenix Co., Ltd.), the same polyisocyanate compound was obtained. Depending on the method, composite monofilament with a fineness of 20 denier (Yarn B
) was obtained.

As a comparative example of the present invention, a 20-denier monofilament (Yarn C) made by melt-spinning only the thermoplastic polyurethane used to manufacture the tea master was given false twist in the S or Z direction as a bulky crimped yarn. Denier/6 filament woolly nylon yarn (Yarn D) Eccentrically wound 1II composite yarn with the thermoplastic polyurethane core and polycapramide sheath used to manufacture Yarn A (Yarn E
), 13 denier/3 filament false-twisted woolly yarn is wound around yarn C in S or 2 directions. Single covering yarn (yarn F) is used for 4-way seamless straight socking & Q! (Speed 60
Five types of stockings (tea master to F above) were manufactured under the conditions (0 rpm).

In addition, wire thread was used for all four threads of the four types of threads except for the covering thread (thread F), but thread F had a wire thread of 13 denier/
One 3-filament flat yarn was alternately knitted and used.

The five types of yarn thus obtained and the stockings using the yarn were subjected to a yarn physical property test, a stocking physical property test, and a wearing test by 30 people.

The results are shown in Table 3.

The items used in the yarn physical property test and stocking physical property test are as follows.

(1) The calf area of trench bank stockings is stretched and recovered at 100% in the direction perpendicular to the length of the stocking five times, and the stress resistance is determined by the ratio of the 80% stretching stress at the final stretch to the 80% recovery stress at the final recovery. The larger this value, the better the fit.

・In the case of peeling after 1000 to 3000 times of 1 kg... Grade 4: No peeling after 3000 times of 2 kg Light passing through a knitted stocking fabric stretched 100% in the warp and weft directions is detected 1Qcm behind the knitted stocking fabric, and the case where there is no knitted stocking fabric is set as 100, and the decrease rate is expressed.

(3) Core/sheath adhesion Evaluated using a Schaeffer abrasion tester according to the following criteria.

Core peeling occurs under load 1 kg x 1000 times...
- Grade 1: Peeling occurs at 1 kg x 1,000 to 3,000 times... Grade 2: Peeling occurs at 2 kf x 1,000 times or less... The stockings of the present invention using grade 3 yarns A and B are urethane yarns. It has the same stretch back properties (fitting properties, tightness) as (thread C), and improves the feel, which is a drawback of urethane thread, making the stockings extremely comfortable to wear.

Woolly nylon thread has an elastic fit5. i3 Each yarn has its own characteristics such as lack of brightness, eccentric composite yarn E has poor crimp uniformity, and covering yarn F has poor stitch surface due to uneven covering and lacks transparency. There are drawbacks, making it difficult to obtain high-quality stockings.

In contrast to the fact that the eccentric composite yarn E is crimped and the covering yarn F is bulky and obstructs the i3 passage of light, the yarns A and B of the present invention are extremely transparent because they are flat. Stockings with high quality can be obtained. Furthermore, when the stocking is stretched, the yarn of the present invention utilizes the stretching stress of the yarn itself, rather than relying on the spring stress of crimp, so that excellent power and fit can be obtained.

The S)7 King of the present invention is an extremely high-quality, unprecedented stocking that has received excellent scores in all items from the wear test results, retaining the characteristics of polyurethane yarn, and on top of that, has new performance. It can be said.

Claims (2)

[Claims] (1) A composite yarn with a polyamide sheath and a polyurethane core, ・The core/sheath composite ratio (X) is 3 to 90 in cross-sectional area ratio, ・The crosslinking density of the polyurethane in the core component Y ( μmol/g) and the composite ratio X satisfy the following formula Y≧-8.7×X+52, - Composite yarn characterized in that the center point of each core-sheath is the same in the cross-sectional shape of the composite yarn . (2) A composite yarn with a polyamide sheath and a thermoplastic polyurethane or crosslinked polyurethane core, wherein: - The core/sheath composite ratio is 3 to 90 in terms of cross-sectional area ratio; - The cross-section of the composite yarn Stockings made of composite yarn characterized in that the center points of each core and sheath are the same in shape.