JPS643965B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to an improvement in a covered elastic yarn formed by winding a thermoplastic synthetic fiber yarn such as polyamide around an elastic yarn such as polyurethane yarn. In particular, the present invention relates to a coated elastic yarn useful as a material for socks, stockings, and the like. [Prior art] By wrapping thermoplastic synthetic fibers such as polyamide long fibers around elastic threads such as polyurethane threads, the disadvantages of elastic threads such as dyeing properties, mechanical strength, and abrasion resistance can be overcome. It is widely used as a This coated elastic yarn is generally manufactured by wrapping a 70-20 denier covering yarn around a 20-70 denier elastic yarn in a single or double manner. In the case of , the number of twists of the lower thread is 2600t/m, and the number of twists of the upper thread is 1800t/m.
Wrapping is carried out at a length of 1.5 m
It is widely used in socks, stockings, etc.). As the covering yarn, a normal circular cross-section fiber having a circular cross-section has been used. The covering properties of this covered elastic yarn can be improved by increasing the yarn fineness of the covering yarn, increasing the number of single yarns, and increasing the number of windings (number of covering twists) of the covering yarn. can do. However, when the yarn fineness of the covering yarn is increased, there is a problem that the covering elastic yarn itself becomes thicker. Therefore, in fashion-oriented application fields such as stockings, where transparency of the resulting product is strongly required and the thickness of the covered elastic yarn itself cannot be increased, it is necessary to increase the coverage of the covering yarn. Reduce the fineness to 18 denier or less and increase the number of windings to 3000~
It is necessary to increase the amount to about 4000t/m, and also to increase the number of single yarns for coating. However, if the number of wrappings of the covering thread is increased,
This will significantly reduce the production speed, and furthermore, the torque of the resulting covered elastic yarn will increase, making it more likely that snarls will occur during knitting. moreover,
Increasing the number of single yarns in the covering yarn requires the use of ultra-fine yarns, but these ultra-fine yarns are not easy to spin, are expensive, and difficult to use practically. There is a problem in that fluff tends to occur during winding. As described above, each method has its advantages and disadvantages, and is not preferred for industrially obtaining coated elastic yarns with a fineness. [Problems to be Solved by the Invention] Therefore, the present invention solves the above-mentioned problems and solves the above problems without increasing the yarn fineness of the covering yarn or increasing the number of windings or the number of single yarns. One object of the present invention is to provide a coated elastic yarn that can provide sufficiently high coverage. That is, one object of the present invention is to provide a covered elastic yarn that can sufficiently improve the covering properties without impeding the yarn fineness of the covered elastic yarn and has good productivity. Furthermore, another object of the present invention is to provide a coated elastic yarn with excellent mechanical strength. [Means for Solving the Problems] In order to achieve this object, the present invention provides a coated elastic yarn formed by winding a covering yarn made of long fibers of a thermoplastic polymer around a core yarn made of elastic fibers. In the yarn, the long fibers forming the covering yarn have a diameter of 1.20 to 1.60.
A coated elastic yarn characterized in that it is a non-circular fiber having a cross-sectional shape coefficient K of (the cross-sectional shape coefficient K
is the value of K=L/Lc, where L means the outer circumference length of the fiber cross section, and Lc means the outer circumference length of a circle having the same cross-sectional area as the fiber. ). Note that the cross-sectional shape coefficient K is expressed as an average value of all single yarns of the covering yarn. The elastic fibers used in the present invention are preferably polyurethane elastic fibers commonly referred to as spandex fibers, but may be other types of elastic fibers. On the other hand, polyamide, polyester, polyolefin, polyacrylic fibers, etc. are used as the long fibers of the thermoplastic polymer constituting the coating thread, but polyamide fibers are preferable because of their excellent dyeing properties, mechanical strength, friction resistance properties, etc. Furthermore, among polyamide fibers, nylon 6 and nylon 66 fibers are preferred because they have particularly excellent properties. [Function] The present invention is characterized by using specific non-circular cross-sectional fibers having a cross-sectional shape factor K of 1.20 to 1.60 as the covering thread in order to improve the covering properties and mechanical strength. In other words, in general, fibers with a non-circular cross-section have lower mechanical strength than fibers with a round cross-section. Although the mechanical strength of the yarn is low, the mechanical strength is greatly improved compared to when it is coated with round cross-section fibers, and it is possible to create a coated elastic yarn that has excellent not only covering properties but also mechanical strength. be. Even if non-circular cross-section fibers are used as the covering yarn, if the cross-sectional shape factor K is less than 1.20, sufficient covering effect and improvement in mechanical strength cannot be obtained. In order to obtain even better effects, it is preferable that the cross-sectional shape factor K is 1.30 or more. on the other hand,
If the cross-sectional shape coefficient K exceeds 1.60, the abrasion resistance of the resulting coated elastic yarn will decrease, and the color fastness and texture will also decrease, making it unsuitable for practical use. That is, in order to obtain a coated elastic yarn that comprehensively satisfies these characteristics and has excellent coating effect and mechanical strength, the coating yarn must have a specific non-circular cross section with a cross-sectional shape coefficient K of 1.20 to 1.60. It is necessary to use fiber. The cross-sectional shape of this non-circular cross-section fiber is Y-shaped, T-shaped,
The shape may be any shape such as a letter, an X-shape, a U-shape, an H-shape, an L-shape, or an E-shape. To further improve strength,
It is preferable to have a Y-shaped (trefoil) cross-sectional shape. The production of covered yarn, in which a covering yarn is wound around a core yarn, may be carried out by a normal covering yarn manufacturing method, and even single covering, in which one covering yarn is wound around a core yarn, may be used. Alternatively, it may be a double covering in which two covering threads are sequentially wound outward in different twisting directions. Furthermore, when performing double covering, the cross-sectional shapes of the respective non-circular cross-section fibers forming the two covering threads may be different within the condition range of the present invention. Furthermore, the single yarns of the covering yarn may have different finenesses and cross-sectional shapes. [Example and Comparative Example] A 20 denier, 3 filament spandex fiber yarn was stretched 3.2 times and double covered using a normal covering machine (lower twist Z direction, upper twist S direction).
direction). The covering yarn used and its covering conditions are shown in Table 1. The covering yarn used was the same type of nylon 6 filament yarn for both the inside and outside windings, and its yarn fineness and The number of threads and the cross-sectional shape factor K were varied. Note that the cross-sectional shape of the non-circular cross-sectional fiber was trilobal. The coverage of the obtained covered elastic yarn and the coverage of the knitted stocking fabric knitted using this covered elastic yarn were visually observed using a magnifying glass and evaluated according to the following criteria. ◎: Excellent △: Slightly poor 〇: Good ×: Poor In addition, an enlarged photograph (12x) of the covered elastic yarn in Figure 1
The enlarged cross-sectional view of the non-circular cross-section fiber used for the covering yarn shown in FIG. 2 shows the case of Example 1, and the enlarged photograph (12
times) indicates the case of Comparative Example 1.

[Table] As can be seen from the results shown in Table 1 and Figures 1 and 3, the yarn fineness is 15 denier, 12 denier, and 10 denier.
When the cross-sectional shape coefficient K of the fiber of the covering yarn was changed for each level of denier (Comparative Example 1)
and Example 1, Comparative Example 2 and Example 4, and Comparative Example 4 and Example 6), the product according to the present invention had a superior covering effect compared to the comparative example in both yarn evaluation and knitted fabric evaluation. had. Furthermore, as can be seen from the comparison between Comparative Example 1 and Example 2 (in the case of 15 denier) and Comparative Example 5 and Example 6 (in the case of 10 denier), the covered elastic yarn according to the present invention has a covering twist number of 500 t/m. Although the amount was less than that, it had an excellent coating effect equivalent to or better than that of the comparative example. Furthermore, as can be seen from the results when the cross-sectional shape coefficient K was varied as shown in Comparative Example 2, Comparative Example 3, Example 3, Example 4, and Example 5, a good coating effect is obtained when the cross-sectional shape coefficient K is This was obtained by using a coating thread having a coefficient of 1.20 or higher. As can be seen from the comparison results between Comparative Example 6 and Example 7, even if the number of filaments was reduced to 3, coverage could be significantly improved by increasing the cross-sectional shape factor K. In addition, for representative covered elastic yarns obtained by the above method, the yarn strength of the obtained covered elastic yarn and the yarn strength of the nylon 6 filament yarn used as the covering yarn were measured. , as shown in Table 2. As can be seen from the results in Table 2, when non-circular cross-section fibers with a cross-sectional shape factor K of 1.20 to 1.60 are used as coating yarns (Examples 1, 4, 6, and 7), round-section fibers are coated with round-section fibers. When used for yarn (Comparative Examples 1, 2,
Compared to 4 and 6), although the filament yarns used for coating had lower tenacity, the strength of the resulting coated elastic yarns was greatly improved.

[Table] [Effects of the Invention] Since the covered elastic yarn according to the present invention has a sufficiently enhanced covering effect with the covering yarn, it is possible to improve the covering property without increasing the number of windings or the number of single yarns. can. Therefore, it is possible to obtain a coated elastic yarn with good productivity and excellent coating effect. Furthermore, even if the fineness of the long fiber yarn constituting the covering yarn is reduced or the number of single yarns is decreased, good covering properties can be obtained without increasing the number of windings. Furthermore, the coated elastic yarn according to the present invention has a mechanical strength superior to that of a conventional coated elastic yarn coated with round cross-section fibers.

[Brief explanation of drawings]

FIG. 1 is an enlarged side photograph showing an example of a covered elastic yarn (double covering yarn) according to the present invention. FIG. 2 is an enlarged sectional view showing the cross-sectional shape of the covering yarn used in manufacturing the covered elastic yarn of FIG. Moreover, FIG. 3 is an enlarged side photograph showing a conventional covered elastic yarn (double covering yarn).

Claims (1)

[Claims] 1. In a covered elastic yarn formed by winding a covering yarn made of long fibers of a thermoplastic polymer around a core yarn made of elastic fiber, the long fibers forming the covering yarn have a cross-sectional shape coefficient of 1.20 to 1.60. A coated elastic yarn characterized in that it is a non-circular fiber having K. (The cross-sectional shape factor K is the value of K=L/Lc, where L is the outer circumference length of the fiber cross section, and Lc is
Each refers to the outer circumference of a circle having the same cross-sectional area as the fiber. )