JPS643966B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to an improvement in a double-covered elastic yarn formed by doubly wrapping a thermoplastic synthetic fiber yarn such as polyamide around an elastic yarn such as polyurethane. In particular, the present invention relates to a double coated elastic yarn useful as a material for hosiery such as socks and stockings. [Prior art] By double wrapping thermoplastic synthetic fibers such as polyamide long fibers around elastic threads such as polyurethane threads, it is possible to improve the dyeing properties, mechanical strength, and abrasion resistance properties that are disadvantageous to elastic threads. It is widely used to cover such things as This double coated elastic yarn is generally manufactured by double wrapping a 70 to 20 denier covering yarn around a 20 to 70 denier elastic yarn.
Winding is carried out at a rate of 2,600 t/m and a number of twists of the needle thread of 1,800 t/m (Japanese Patent Application Laid-Open No. 19146/1983, etc.), and it is widely used for socks, stockings, etc. As the covering yarn, the same type of yarn was used for both inner and outer wrapping, and a normal circular cross-section fiber having a circular single yarn cross section was 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 be improved. 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. fineness
Make it as thin as 18 denier or less and reduce the number of wraps.
Increase it to around 3000-4000t/m, and
It is necessary to increase the number of single threads of the covering thread. 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, and the resulting knitted fabric will have more irregular stitches. There is also. Furthermore, increasing the number of single yarns in the covering yarn requires the use of ultra-fine yarn, but this ultra-fine yarn is not easy to spin, is expensive, and difficult to use practically. Moreover, there is a problem in that fuzz is likely to occur during winding. As described above, each method has its advantages and disadvantages, and is not preferable for industrially obtaining fine-grained double-coated elastic yarns. [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 double-covered elastic yarn that can provide sufficiently high coverage. That is, one object of the present invention is to provide a double-covered elastic yarn that can sufficiently improve the covering properties without impeding the yarn fineness of the covered elastic yarn and has good productivity. be. Furthermore, another object of the present invention is to reduce the torque of the covered elastic yarn even in a state of excellent covering properties, to obtain a knitted fabric that is easy to knit and has a beautiful knitted surface. The object of the present invention is to provide a double-coated elastic yarn with excellent mechanical strength. [Means for Solving the Problems] In order to achieve this object, the present invention is formed by doubly wrapping a covering thread made of long fibers of a thermoplastic polymer around a core thread made of elastic fibers. In the double-covered elastic yarn, the covering yarn wound on the inside is made of long fibers with a round cross section, and the covering yarn wound on the outside has a cross-sectional shape coefficient K of 1.20 to 1.60. A double-coated elastic yarn characterized in that it consists of long fibers with a non-circular cross section (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 the single yarns forming the covering yarn wound on the outside. 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 thermoplastic polymers that make up the covering yarn.
Polyamide fibers with excellent dyeing properties, mechanical properties, abrasion resistance properties, etc. are preferred, and among polyamides, nylon 6 and nylon 66 fibers are particularly preferred as they have particularly excellent properties. [Function] In order to improve coverage, reduce torque, and improve mechanical strength, the present invention has a cross-sectional shape factor K of 1.20.
Using two different types of covering yarn, one consisting of long fibers with a specific non-circular cross section of 1.60 and the other covering yarn consisting of long fibers with a round cross section, and
It is characterized by winding a thread of round cross-section fibers on the inside and a thread of non-circular cross-section fibers on the outside. On the other hand, conventional covered elastic yarns made of fine-grained thermoplastic synthetic fibers for stockings and the like have used the same thread for both the inner and outer covering yarns. However, there is a difference in the covering efficiency of the core yarn between the inner covering thread and the outer covering thread, and the covering efficiency of the outer covering thread is considerably higher than that of the inner covering thread. The torque of the elastic yarn is generated by the covering twist of the outer covering yarn. Furthermore, the present inventors have discovered that the mechanical strength of the coated elastic yarn can be improved by coating it with non-circular cross-sectional fibers having a specific cross-sectional shape coefficient. Therefore, when covering elastic yarns such as spandex fibers with synthetic fiber filament yarns, they are used as covering yarns for the inner side, where the covering efficiency is poor, because they are particularly small in bulk, have high productivity, and are extremely good in terms of quality such as fluff. By using a non-circular cross-section fiber yarn with a cross-sectional shape coefficient K of 1.20 to 1.60, which has particularly excellent covering properties, as a covering yarn used on the outside with good covering efficiency, it is possible to improve coverage. This invention has led to the achievement of the excellent effects of reducing torque and improving mechanical strength. In the present invention, since the round cross-section fiber yarn is wound on the inside, even if a non-circular cross-section fiber having a high degree of deformation with a cross-sectional shape coefficient K of 1.20 or more is wound on the outside, it is possible to use a general material. Rather than exhibiting an increase in mechanical torsional or bending stiffness, the non-circular cross-section fibers of the outer covering yarn become highly buckled and exhibit a decrease in stiffness, resulting in helical bending stress due to the covering twist. As a result, the torque of the covered elastic yarn is reduced, and troubles during knitting and defects in the knitted surface are improved. On the other hand, if non-circular cross-section fibers are used both inside and outside, the resulting covered elastic yarn will have a large diameter, making it difficult to reduce the torque. Furthermore, this non-circular cross-section fiber needs to have a cross-sectional shape factor K of 1.20 or more in order to obtain a sufficient covering effect and improvement in mechanical strength.
It is preferable to set it to 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 furthermore, the color fastness and texture will decrease, making it unsuitable for practical use. 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. In this way, these characteristics are comprehensively satisfied,
In order to obtain a coated elastic yarn with excellent coating effect, mechanical strength, and low torque, the outer coating yarn should be coated with
It is necessary to use specific non-circular cross-section fibers with a cross-sectional shape factor K of 1.20 to 1.60. 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. On the other hand, the inner covering yarn needs to be a long fiber yarn with a round cross section in order to reduce the diameter of the resulting covered elastic yarn. As this round cross-section fiber yarn,
It is sufficient to use a round cross-section fiber thread that has been generally used as a covering thread. The production of covered yarn, in which the covering yarn is wound around the core yarn, is carried out by the usual method of producing covered yarn, that is, the two covering yarns are wound twice around the core yarn by sequentially changing the twist direction outward. This can be done by attaching a double covering. Note that the single yarns of the outer covering yarn may have different finenesses and cross-sectional shapes as long as they fall within the conditions of the present invention. [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 yarns and covering conditions used in this case are as shown in Table 1. The covering yarns include a yarn consisting of nylon 6 filaments with a round cross section, and a yarn consisting of nylon 6 filaments with a trilobal cross section. The yarn fineness, number of single yarns, and cross-sectional shape factor K were varied. The coverage of the obtained covered elastic yarn was evaluated visually using a magnifying glass according to the following criteria. ◎: Excellent 〇: Good △: Slightly poor ×: 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 outer covering yarn shown in FIG. shows the case of Comparative Example 1. In addition, the torque value of the obtained covered elastic yarn is determined by applying a load of 1 g to the center of a 1 m long covered elastic yarn and letting it hang down to develop torque.
Measure the number of twists that occurred (number of twists per 50 cm), and
It is converted into the number of twists per m. The quality of the torque value was evaluated using the same criteria as in the case of coverage.

【table】

[Table] As can be seen from this result, when the cross-sectional shape coefficient K of the fibers forming the outer wrapping covering yarn was changed for each of different yarn fineness levels of 15 denier, 12 denier, and 10 denier (comparison Example 1 and Invention Example 1, Comparative Example 2 and Examples 2 to 4, Comparative Example 3 and Example 5), the products according to the present invention were superior to the comparative examples in both yarn evaluation and knitted fabric evaluation. Moreover, even though a non-circular cross-section yarn was used, which was 80 to 90% stronger than a round cross-section yarn, the strength of the yarn was improved and the torque was reduced. Also, Comparative Example 3 and Example 5 (for 10 denier)
As can be seen from the comparison, the covered elastic yarn according to the present invention exhibited a covering effect superior to that of the comparative example, even though the number of twists in the covering was 400 t/m or more less. Furthermore, the cross-sectional shape coefficient K of the outer covering yarn shown in Comparative Example 2, Example 2, Example 3, and Example 4
As can be seen from the results obtained when the coefficients were varied, good covering effects, torque reduction effects, etc. were obtained by using highly deformed non-circular cross-sectional fibers with a cross-sectional shape coefficient K of 1.20 or more. As can be seen from the comparison results between Comparative Example 4 and Example 6, even if the number of filaments was reduced to 3, the coverage could be significantly improved by increasing the cross-sectional shape factor K. In addition, as Comparative Example 5, coating was carried out using the filament yarns used for the inner and outer covering yarns in the opposite manner to those in Example 1, without changing the number of twists on the inner and outer sides. The coverage of the coated elastic yarn was slightly better than Comparative Example 1 (△ to 〇),
The torque was 22 t/m, which was worse than Comparative Example 1. [Effects of the Invention] The double-coated elastic yarn according to the present invention uses a coating yarn with a sufficiently high coating effect for outer winding with high coating efficiency, so the number of windings and the number of single yarns can be increased. It is possible to improve the coverage without any problems. Therefore, it is possible to obtain a double-coated elastic yarn with good productivity and excellent coating effect. In addition, 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 performance can be obtained without increasing the number of windings. Round cross-section yarn is used for the covering yarn to prevent the yarn diameter from increasing.
The present invention is also effective in obtaining double-coated elastic yarns with extremely small diameters. Furthermore, since a round cross-section fiber yarn is used as the inner covering thread, and a non-circular cross-section fiber with a specific cross-sectional shape and excellent covering properties is used as the outer covering thread, the resulting double The coated elastic yarn has a low torque and can be knitted with good knitting properties and a beautiful knitted surface. The coated elastic yarn according to the invention also has superior mechanical strength to conventional coated elastic yarns coated with round cross-section fibers.

[Brief explanation of the drawing]

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

Claims (1)

[Claims] 1. In a double-covered elastic yarn formed by doubly wrapping a covering yarn made of long fibers of a thermoplastic polymer around a core yarn made of elastic fiber, the covering yarn wound on the inside has a round cross section. The double-covered elastic yarn is characterized in that the covering yarn is made of long fibers and the covering yarn wound on the outside is made of long fibers with a non-circular cross section having a cross-sectional shape coefficient K of 1.20 to 1.60. (The cross-sectional shape factor K is the value of K=L/Lc, where:
L means the outer circumferential length of the fiber cross section, and Lc means the outer circumferential length of a circle having the same cross-sectional area as the fiber. )