JP2011174206A - Covered elastic yarn and production method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide covered elastic yarns little in shrinkage by heating, excellent in morphological stability, little in slip between core fiber and sheath fiber and giving stockings having high transparency and excellent in dimensional stability between before and after wearing, and to provide a production method therefor. <P>SOLUTION: There is provided the hot-drawn covered elastic yarn Y having ≤15% boiling water shrinkage, wherein the hot-drawn covered elastic yarn Y comprises a core fiber (a) which is a polyurethane elastic fiber having a urethane bond and represented by formula (I) (wherein, P is a polyol residue, R<SP>1</SP>and R<SP>3</SP>are mutually the same or different diisocyanate residue, R<SP>2</SP>is a diol residue, U is a urethane bond, n1 is 1-10 recurring unit number, and n2 is 1-10 recurring unit number) and a sheath fiber (b) which is a polyamide fiber having <30% elongation. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a coated elastic yarn that is excellent in shape stability and can provide a highly transparent stocking and a method for producing the same.

  In general, stockings are preferably highly transparent in order to achieve a feeling of bare skin, which is a great need from women, and many methods and devices for obtaining stockings with excellent transparency have been proposed. For example, as a stocking excellent in transparency, at least the leg portion is provided with a rubber elastic fiber of 10 to 30 dtex as a core yarn, and a single yarn dtex as a covering yarn is 0.5 to 3.0, and a total dtex is 5 A covered yarn formed by arranging at least one polyamide filament yarn of ˜20 dtex and a polyamide filament yarn having a single yarn dtex of 1.0 to 7.0 dtex and a total dtex of 5 to 22 dtex; or A stocking in which the processed yarn is alternately knitted for each course is disclosed (see Patent Document 1). In addition, as a method for improving the transparency of the stockings, from a long fiber having a flat fiber cross-sectional shape with a yarn fineness of 5 to 15 dtex, a filament number of 2 to 7 filaments, and a flatness of 2.0 to 6.0. A stocking using a composite elastic yarn formed by winding a covering yarn is proposed, and an improvement in transparency is recognized as compared with a round cross section (see Patent Document 2).

  However, there is a strong demand for further transparency, and no one that fully satisfies this requirement has been proposed.

In addition, in thin stockings that are highly transparent, the fabric shrinks during attachment and detachment, and the aesthetics of the stockings are impaired. Therefore, for example, by unwinding the polyamide flat yarn from a package of polyamide flat yarn having a dynamic friction coefficient and unwinding tension within a specific range and knitting it with elastic yarn to produce a stocking knitted fabric, A method for improving the uniformity of the ground has also been proposed (see Patent Document 3). However, this proposal does not directly solve the dimensional change before and after wearing. Further, after winding high-strength polyamide POY (highly oriented undrawn yarn) around the elastic yarn A method for producing a coated elastic yarn that is stretched by 1.1 to 1.5 times has been proposed (see Patent Document 4). However, when the polyamide POY is covered with a polyurethane elastic yarn and then stretched, twisting is likely to occur, and the stretched polyamide fiber tends to float from the polyurethane elastic yarn, inducing yarn breakage during knitting, It is easy to cause twisting and it is difficult to obtain a plain knitted fabric. Furthermore, stockings also become bulky, and it is difficult to obtain a desired highly transparent product after all.

JP 61-89301 A JP 7-157902 A Japanese Patent Laid-Open No. 8-081129 JP-A-5-272019

  An object of the present invention is to provide a coated elastic yarn capable of providing a stocking having high transparency and high form stability before and after wearing, and a method for producing the same.

The coated elastic yarn of the present invention has one of the following configurations in order to solve the above problems.
(1) A heat-stretched coated elastic yarn having a boiling water shrinkage of 15% or less, a polyurethane elastic fiber represented by the following formula (I) as a core yarn, and a polyamide fiber having a sheath yarn having an elongation of less than 30% A coated elastic yarn comprising:

(2) The covered elastic yarn according to (1) above, wherein the number of slacks protruding from the yarn surface by 0.35 mm or more is less than 5 / m.
(3) The coated elastic yarn according to (1) or (2), wherein the fineness of the core yarn is 3 to 44 dtex.
(4) Polyurethane elastic fiber represented by the following formula (I), which is a core yarn, is coated with a polyamide fiber having an elongation of less than 30% as a sheath yarn, and the core yarn is stretched 2 to 5 times. A method for producing a coated elastic yarn, wherein a dry heat treatment at 140 ° C. to 185 ° C. is performed.

  According to the present invention, since it is a coated elastic yarn that has little shrinkage due to heating and excellent shape stability and little slip between the core yarn and sheath yarn, a stocking that is highly transparent and excellent in dimensional stability before and after wearing is provided. Obtainable.

It is a schematic diagram which shows one Embodiment of the covering elastic yarn of this invention. It is a schematic diagram which shows an example of the manufacturing process of the covering elastic yarn of this invention. It is a schematic diagram which shows the pantyhose created by the Example and the comparative example.

FIG. 1 schematically shows an embodiment of the coated elastic yarn of the present invention. The coated elastic yarn Y of the present invention has a structure in which a sheath yarn (B) is coated on the outer periphery of the polyurethane elastic fiber (A).
The coated elastic yarn of the present invention is a coated elastic yarn having a boiling water shrinkage of 15% or less due to hot drawing. If the boiling water shrinkage rate is greater than 15%, after knitting the stockings, in the process of applying heat such as presetting and dyeing, the coated elastic yarn constituting the stockings shrinks, the stockings become thicker, and its transparency is It will be greatly reduced. Furthermore, if the product that has been shrunk by dyeing is greatly stretched and heat-set with a finished mold set, even if the product is once made in large dimensions, the stockings will shrink when the consumer removes it. It detracts from aesthetics. By making the boiling water shrinkage rate 15% or less by hot stretching, it is possible to maintain high form stability before and after wearing such as stockings knitted with the coated elastic yarn as well as transparency.

  The coated elastic yarn of the present invention preferably has a number of slacks protruding from the yarn surface of 0.35 mm or more and less than 5 / m. That is, it is preferable that the sheath yarn (b) is covered with the outer circumference of the polyurethane elastic fiber (b) with almost no gap and with little twist (c). Such a configuration is effective in suppressing reflected light caused by a difference in refractive index between air and a polymer constituting a multifilament of sheath yarns on the fiber surface when forming a stocking, and improving transparency. If the number of slacks is 5 pieces / m or more, the coated elastic yarn itself becomes bulky, so that the transparency is reduced, and it also affects the reproduction of the bare skin feeling, which is the maximum required characteristic of stockings. .

  The number of twisted slacks protruding 0.35 mm or more from the surface of the yarn is projected from the side surface to the covered coated elastic yarn and at a position 0.35 mm from the surface of the yarn. Count the number of times. The measurement method will be described in more detail. First, set the light so that it strikes one side of the running yarn. From that state, while shifting the position of the light by 0.01 mm toward the other side of the running yarn, the number of yarns that intersect the light is counted, and the position of the light at which the count number reaches the maximum value is defined as the yarn surface. To do. The light is further shifted by 0.35 mm in the same direction from the yarn surface, and the number of slacks protruding beyond the light is measured.

  Next, the polyurethane elastic fiber that is the core yarn of the coated elastic yarn of the present invention will be described. The polyurethane elastic fiber is an elastic fiber containing polyurethane represented by the following formula (I). Moreover, it is an elastic fiber containing polyurethane represented by the following formula (I), and in its small-angle X-ray scattering image, it shows an eyebrow-like four-point scattering image, the long period in the meridian direction is 7 to 16 nm, and the equator line A polyurethane fiber having a long period in the direction of 13 to 30 nm is preferable.

Said polyurethane fiber can be manufactured with the following method, for example. That is, in producing a polyurethane fiber by dry spinning a polyurethane solution in which polyurethane is dissolved in a solvent, the addition ratio represented by the following formula (II) has the structural formula represented by the following formula (I): A polyurethane having 1.7 to 3, a hard ratio (n ₂ / n ₁ ) of 0.65 to 3, a number average molecular weight of 30,000 to 200,000 and a softening point of 130 to 250 ° C. is used.

  The above-mentioned polyurethane is a diol-extended polyurethane, and the diol-extended polyurethane can make a fiber have an appropriate heat setting property. In addition, it does not matter at all if a urea bond is partially present in the polyurethane molecule as long as the effect of the present invention is not hindered.

The raw material diol chain extender which is arranged in the polyurethane molecule as the diol residue R ² in the formula (I) and gives a urethane bond is not particularly limited, and conventionally known ones can be widely applied. . Needless to say, a compound having three or more hydroxyl groups, such as glycerin, may be used in combination as a chain extender within a range not impeding the effects of the present invention.

  Among the diol chain extenders, preferred for obtaining a superior polyurethane fiber is not particularly limited, but includes ethylene glycol (hereinafter abbreviated as “EG”), 1,3-propanediol. (Hereinafter abbreviated as “PDO”), 1,4-butanediol (hereinafter abbreviated as “BDO”), neopentyl glycol, 1,2-propylene glycol, 1,4-cyclohexanedimethanol, 1,4 -Cyclohexanediol, 1,4-bis (β-hydroxyethoxy) benzene (hereinafter abbreviated as “BHEB”), bis (β-hydroxyethyl) terephthalate, paraxylylene diol, and the like. Among these diol chain extenders, preferred are EG, PDO, BDO and BHEB. In particular, polyurethane fibers using EG as an extender are particularly preferred because they have particularly high strength, high heat resistance, moderate heat setability and elastic recovery, and high light resistance. The diol chain extender is not limited to one consisting of only one type of diol, but may be one consisting of a plurality of types of diols.

There are no particular limitations on the diisocyanate used as a raw material which is disposed in the polyurethane molecule as the diisocyanate residues R ¹ and R ³ in the formula (I) and gives a urethane bond, and conventionally known ones can be widely applied. In addition, you may use together the compound which has 3 or more isocyanate groups in the range which does not prevent the effect of this invention.

  Among diisocyanates, preferred for obtaining superior polyurethane fibers are not particularly limited, but include diphenylmethane diisocyanate (hereinafter abbreviated as “MDI”), dicyclohexylmethane diisocyanate (hereinafter “HMDI”). ), Hexamethylene diisocyanate, xylylene diisocyanate, tolylene diisocyanate, phenylene diisocyanate, naphthalene diisocyanate, isophorone diisocyanate and the like. Particularly preferred among these diisocyanates are MDI and HMDI. This is because polyurethane fibers using MDI have higher strength, higher heat resistance, and better solvent resistance. In addition, polyurethane fibers using HMDI have great advantages such as high light resistance when a polyol and a chain extender are appropriately selected. Furthermore, MDI is more preferable among these two. A diisocyanate is not limited to use of only 1 type, You may use multiple types together.

  Although the raw material polyol which becomes the polyol residue P in the formula (I) and is arranged in the polyurethane molecule and gives a urethane bond is not particularly limited, typical examples thereof include polytetramethylene ether glycol (hereinafter referred to as “polytetramethylene ether glycol”). Abbreviated as “PTMG”) and copolymers thereof, polypropylene glycol and ether-based polyols such as copolymers thereof, as well as polybutylene adipate glycol and copolymers thereof, neopentyl adipate glycol and copolymers thereof Polyester polyols disclosed in JP-A-4-41714, page 3, column 1, line 13 to column 4, column 4, line 4, etc., polycarbonate polyols, which are one kind of polyester polyols, poly List known polyols such as siloxane polyols It can be. Among these polyols, PTMG and copolymers thereof are preferable as ether-based polyols. Typical PTMG copolymers include those obtained by adding ethylene oxide to the end of PTMG, and PTMG copolymerized with tetrahydrofuran (hereinafter referred to as “THF”) and 3-methyl THF. Polyurethane fibers using PTMG and / or a copolymer thereof as a polyol have excellent low-temperature characteristics, higher mold resistance, better elastic recovery, and higher hydrolysis resistance.

  The molecular weight of the polyol is preferably 800 to 3500 in consideration of fiber strength and elastic recovery. In particular, for a polyol having no side chain, the preferred molecular weight is 800-2500. This is because the use of a polymer having a molecular weight within these ranges makes the low-temperature characteristics of the polyurethane fiber particularly excellent. Further, it is particularly preferable that the polyol is not a single component but has a plurality of components having a number average molecular weight of 800 to 2500 and a number average molecular weight of 1600 to 4000, and the polyol has a number average molecular weight of 1200 to 2600 as a whole. It is.

  The polyol residue P constituting the polyurethane is not limited to one type of use within one molecule of the polyurethane, but a plurality of types of polyol residues, for example, an ether polyol residue and an ester polyol residue. May be used in combination.

  Moreover, it is preferable that the said addition ratio shall be 1.7 or more from a viewpoint of preventing the fall of melting | fusing point of a fiber, and the increase in adhesiveness. On the other hand, it is preferably 3 or less from the viewpoint of preventing the fiber elongation from decreasing. In particular, the addition ratio is preferably 1.8 to 2 from the viewpoint of obtaining fibers having high heat resistance and appropriate setting properties.

  The polyurethane hard ratio is preferably 0.65 to 3. Here, the hard ratio refers to the ratio (n2 / n1) between the number of repeating units n2 and n1 in the formula (I). This is because when the hard ratio is in the above range, the strength of the polyurethane becomes higher and the heat resistance becomes higher. In order to make such an effect higher, a particularly preferable hard ratio is 0.9 to 1.8.

  The number average molecular weight of the polyurethane is preferably 30,000 to 200,000. This is because when the number average molecular weight is within this range, the durability is remarkably improved not only in strength but also in practical use. In order to make this improvement effect higher, it is particularly preferably 60,000 to 120,000. The number average molecular weight of polyurethane can be measured, for example, by preparing a calibration curve with standard polystyrene by a gel permeation chromatography method (hereinafter abbreviated as “GPC method”).

In the formula (I), the number of repeating units n1 and n2 are both in the range of 1-10.
If at least one of n1 and n2 is less than 1, the strength of the polyurethane is insufficient, the softening point is too low, or the elongation is insufficient, so that a desired fiber cannot be obtained. When n1 exceeds 10, the softening point of polyurethane becomes too low, so that a desired fiber cannot be obtained. On the other hand, when n2 exceeds 10, the softening point of polyurethane becomes too high and the elongation becomes low, so that a desired fiber cannot be obtained. Although it depends on the molecular weight of the polyol residue, the preferred n1 range is 1-5. Moreover, the preferable range of n2 is 1-5. This is because such a value makes a particularly good polyurethane fiber.

  Since polyurethane is a polymer, both n1 and n2 are average values. Therefore, it is not necessarily an integer. Specifically, n1 and n2 can be obtained by NMR method or hydrolysis method.

  The softening point of the polyurethane is preferably 130 to 250 ° C. This is because when the softening point is 130 ° C. or higher, the combined use with the polyamide fiber becomes easy. Further, if the softening point is 250 ° C. or less, there is an advantage that the form can be easily fixed by heat. From these viewpoints, a particularly preferred softening point is 150 to 230 ° C. The softening point of the polyurethane fiber can be measured by, for example, a thermomechanical analyzer method.

  In this invention, it is preferable that the fineness of the polyurethane elastic fiber used as a core yarn is 3-44 dtex. If it is less than 3 dtex, the durability of the coated elastic yarn is not sufficient, and if it is greater than 44 dtex, it is difficult to express its transparency when forming stockings.

  In the present invention, polyamide fibers having an elongation of less than 30% are used as the sheath yarn. In particular, a highly oriented undrawn yarn or the like having an elongation of 30% or more tends to increase the shrinkage because its molecular structure becomes loose. As a result, the shrinkage of the coated elastic yarn itself increases, resulting in a decrease in product transparency. The form of the sheath yarn may be raw yarn or temporary twisted yarn, but raw yarn is preferred from the viewpoint of the transparency of the stockings.

  Next, a method for producing the coated elastic yarn of the present invention will be described with reference to the drawings.

  FIG. 2 is a schematic diagram showing an example of a method for producing a coated elastic yarn of the present invention. In the method for producing a coated elastic yarn of the present invention, the above-mentioned polyurethane fiber 1 as a core yarn is coated with the polyamide fiber 2 as a sheath yarn, and the core yarn is stretched 2 to 5 times. In the state, a dry heat treatment at 140 ° C. to 185 ° C. is performed by the heater 7, that is, the coated elastic yarn is hot-drawn under specific conditions.

  In FIG. 2, the polyurethane elastic fiber 1 is pre-drafted between the feed roller 3 and the drive roller 4, and further drafted between the drive roller 4 and the drive roller 5. Accordingly, the total draft of the polyurethane elastic fiber 1 is represented by the ratio of the roller surface speed between the feed roller 3 and the drive roller 5, and in the present invention, this value is set to be in the range of 2 to 5 times. To do. The polyurethane elastic fiber 1 stretched 2 to 5 times between the feed roller 3 and the drive roller 5 is covered with a polyamide fiber 2 having an elongation of less than 30% wound around the H bobbin 6. The coating with the polyamide fiber 2 may be a single cover or a double cover. After forming the coated elastic yarn in this way, the coated elastic yarn is subjected to a dry heat treatment at 140 ° C. to 185 ° C. by the heater 8 while maintaining the state in which the polyurethane elastic yarn is stretched 2 to 5 times. If the temperature of the dry heat treatment is less than 140 ° C., the coated elastic yarn is not sufficiently set and becomes bulky. On the other hand, if the temperature of the dry heat treatment is higher than 185 ° C., yarn breakage tends to occur, which is a problem. The coated elastic yarn subjected to the heat treatment is wound up as a package 10 by a winder 9. Here, the heat treatment is performed on the covering step, but the yarn covered and wound as usual may be subjected to a drawing heat treatment in a separate step.

  Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to these examples.

<Boiling water shrinkage>
The coated elastic yarn was made into a 10-turn casserole with a hand-held measuring scale with a circumference of 1 m under a tension of 30 × 10 ⁻³ cN / dtex. After the casserole was turned around and taken out from the measuring instrument, a tension of 30 × 10 ⁻³ cN / decitex was applied to the casserole to measure the length (L0). Next, after removing the load and immersing it in hot water at 98 ° C. for 30 minutes in an unloaded state, the water is drained with blotting paper and air-dried in an environment of 20 ° C. × 50% humidity for 12 hours. Thereafter, a load of 30 × 10 ⁻³ cN / dtex was applied, and the length of the sample was measured 2 minutes after maintaining that state (L1).

  Using the obtained L0 and L1, the boiling water shrinkage was calculated by the following formula.

  The number of tests was 10 and the average value was obtained.

<Elongation>
JIS-L-1013 (1999) "Chemical fiber filament yarn test method", the elongation rate was determined by the test method described in "8.5.1 standard time test", this measurement was repeated 10 times, and the average value was determined .

<Number of slack>
Using a photoelectric fluff measuring machine (hairness counter DT-104 type, manufactured by Toray Engineering Co., Ltd.), the number of twisted slacks protruding from the surface of the coated elastic yarn by 0.35 mm or more, yarn speed 50 m / min, running tension 0.88 cN Measurement was performed for 20 minutes under the condition of / dtex, and the total number of twists per meter was determined.

<Dimensions before and after wearing stockings>
Regarding the leg length (M) of the stocking having the shape shown in FIG. 3, the width (T) of the thigh switching part, and the width (B) of the toe switching part, dimensions before wearing (M ₀ , T ₀ , B ₀ ) and The dimensions (M ₁ , T ₁ , B ₁ ) when the stockings were put on the foot mold for 10 minutes and removed were measured. Using the obtained dimensions, the dimensional change rate of each part was calculated as follows.

<Transparency of stockings>
The stocking products were viewed by 10 female monitors in their 20s to 50s, and a sensory evaluation was conducted on transparency. The average score of the evaluation score results is shown with a perfect score of 5 points.

[Example 1]
The covered elastic yarn shown in FIG. 2 and the following yarn configuration and yarn processing conditions were subjected to dry heat treatment while being covered to obtain a single cover covered elastic yarn.

[Thread configuration]
Core yarn: polyurethane elastic yarn “Lycra (registered trademark)” T-178C (manufactured by Toray Operontex)
Fineness 20 dtex Sheath yarn: 11 dtex 5 filament drawn polyamide yarn [yarn processing conditions on the covering machine]
Rotational speed: 20000 rpm
Draft (ratio of roller surface speed between roller 3 and roller 5): 3.0
Twist number: 2000T / m
Heater 8 temperature: 173 ° C
Table 1 shows the boiling water shrinkage of the obtained coated elastic yarn and the number of twist slacks protruding from the yarn surface by 0.35 mm or more.

  Using the obtained coated elastic yarn, the S 4 and Y twist yarns are alternately supplied to the yarn feeder of the knitting machine with the Super 4 knitting machine (400 stitches) manufactured by Nagata Seiki Co., Ltd. The ground was knitted only with covered elastic yarn. The toe portion was knitted with false twisted yarn (56 dtex 26 filaments) for reinforcement, as is usually done as pantyhose. Then, the leg part knitted fabric was scoured and dyed (98 ° C. × 20 min), finished, and a template set (steam set, 105 ° C. × 60 sec) to obtain a pantyhose product.

  The obtained pantyhose was very transparent, and the dimensional change before and after attachment / detachment was small. Table 1 shows the dimensions of the stockings before and after attachment / detachment.

[Example 2]
A single cover covered elastic yarn was obtained and evaluated in the same manner as in Example 1 except that the following yarn processing conditions were changed.

[Thread processing conditions on the covering machine]
Rotational speed: 20000 rpm
Draft: 3.0
Twist number: 2000T / m
Heater temperature: 155 ° C
Table 1 shows the boiling water shrinkage of the obtained coated elastic yarn, the number of slacks protruding from the yarn surface by 0.35 mm or more, and the evaluation results of pantyhose. Although the obtained pantyhose was inferior to Example 1, it was highly transparent and the dimensional change before and after attachment / detachment was small.

[Example 3]
A single-covered covered elastic yarn was obtained and evaluated in the same manner as in Example 1 except that the following yarn configuration was changed.

[Thread configuration]
Core yarn: polyurethane elastic yarn “Lycra (registered trademark)” T-178C (manufactured by Toray Operontex)
Fineness 20 decitex Sheath yarn: 11 decitex 2-filament stretched polyamide yarn Table 1 shows the boiling water shrinkage of the obtained coated elastic yarn, the number of slacks protruding more than 0.35 mm from the yarn surface, and the evaluation results of pantyhose Show. The obtained pantyhose was more transparent than Example 1, and the dimensional change before and after attachment / detachment was small.

[Example 4]
A single-covered covered elastic yarn was obtained and evaluated in the same manner as in Example 1 except that the following yarn configuration was changed.

[Thread configuration]
Core yarn: polyurethane elastic yarn “Lycra (registered trademark)” T-178C (manufactured by Toray Operontex)
Table 1 shows the results of the evaluation of the pantyhose, the shrinkage rate of boiling water of the coated elastic yarn obtained, the number of slacks protruding from the yarn surface by 0.35 mm or more, and the pantyhose yarn. Shown in Although the obtained pantyhose was inferior to Examples 1-3, it was highly transparent and the dimensional change before and after attachment / detachment was also small. Table 1 shows the dimensions of the stockings before and after attachment / detachment.

[Comparative Example 1]
A single cover covered elastic yarn was obtained and evaluated in the same manner as in Example 1 except that heat treatment was not performed during yarn processing.

  Table 1 shows the boiling water shrinkage of the obtained coated elastic yarn, the number of slacks protruding from the yarn surface by 0.35 mm or more, and the evaluation results of pantyhose. The obtained pantyhose was bulky and low in transparency, and the dimensional change before and after attachment / detachment was also large.

[Comparative Example 2]
A single-covered covered elastic yarn was obtained and evaluated in the same manner as in Example 2 except that the following yarn configuration was used.

[Thread configuration]
Core yarn: polyurethane elastic yarn “Lycra (registered trademark)” T-127C (manufactured by Toray Operontex)
Fineness 22 decitex Sheath yarn: 11 decitex 2-filament stretched polyamide yarn Table 1 shows the boiling water shrinkage of the obtained coated elastic yarn, the number of slacks protruding from the yarn surface by 0.35 mm or more, and the evaluation results of pantyhose Show. The obtained pantyhose was bulky and low in transparency, and the dimensional change before and after attachment / detachment was also large.

[Comparative Example 3]
A single cover covered elastic yarn was obtained and evaluated in the same manner as in Example 1 except that the following yarn processing conditions were changed.

[Thread processing conditions on the covering machine]
Rotational speed: 20000 rpm
Draft: 3.0
Twist number: 2000T / m
Heater temperature: 130 ° C
Table 1 shows the boiling water shrinkage of the obtained coated elastic yarn, the number of slacks protruding from the yarn surface by 0.35 mm or more, and the evaluation results of pantyhose. The obtained pantyhose was bulky and low in transparency, and the dimensional change before and after attachment / detachment was also large.

[Comparative Example 4]
A single-covered covered elastic yarn was obtained and evaluated in the same manner as in Example 1 except that the following yarn configuration was changed.

[Thread configuration]
Core yarn: polyurethane elastic yarn “Lycra (registered trademark)” T-178C (manufactured by Toray Operontex)
Fineness 20 dtex Sheath yarn: 17 dtex 5-filament polyamide highly oriented undrawn yarn The boiling elastic shrinkage of the coated elastic yarn obtained, the number of slacks protruding from the yarn surface by 0.35 mm or more, and the evaluation results of pantyhose Table 1 shows. The obtained pantyhose was low in transparency and had a large dimensional change before and after the attachment / detachment.

Y Covered elastic yarn (a) Polyurethane elastic fiber (b) Sheath yarn (c) Loosening 1 Polyurethane elastic fiber 2 Polyamide fiber 3 Feed roller 4 Driving roller 5 Driving roller 6 Spindle 7 H bobbin 8 Heater 9 Winder 10 Package M ₀ was Nugashi width B ₁ of the leg length T ₀ wearer before the thigh switching section width B ₀ wear before toe switching unit of width M ₁ Nugashi was thigh switching unit when the leg length is T ₁ Nugashi time before wearing Width of toe switching part

Claims (4)

It is a heat-stretched coated elastic yarn having a boiling water shrinkage of 15% or less, a core elastic yarn comprising a polyurethane elastic fiber represented by the following formula (I), and a sheath yarn comprising a polyamide fiber having an elongation of less than 30%. Coated elastic yarn characterized by

The coated elastic yarn according to claim 1, wherein the number of twist slacks protruding from the yarn surface by 0.35 mm or more is less than 5 / m. The coated elastic yarn according to claim 1 or 2, wherein the fineness of the core yarn is 3 to 44 dtex. The polyurethane elastic fiber represented by the following formula (I), which is a core yarn, is coated with a polyamide fiber having an elongation of less than 30% as a sheath yarn, and the core yarn is stretched 2 to 5 times. A method for producing a coated elastic yarn, characterized by performing a dry heat treatment at 185 ° C.

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