JPH0316408B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a method for producing a double covering elastic yarn, which is 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 method for producing a coated elastic yarn with fine fineness that is useful as a material for socks and stockings. [Prior art] By double wrapping thermoplastic synthetic fibers such as polyamide long fibers around elastic threads such as polyurethane threads (double covering), the dyeing properties and mechanical strength, which are disadvantages of elastic threads, can be improved. It is widely used to cover friction resistance and other properties.
This double covered coated elastic yarn has 20 to 70
It is generally manufactured by wrapping a covering thread of 70 to 20 deniers twice around a denier elastic yarn.
Wrapping was carried out at a rate of about 1800t/m (Japanese Patent Laid-Open No. 1973)
-19146), socks, stockings, etc.). As the covering yarn, the same flat yarn (drawn yarn that has not been subjected to any kind of processing) has been used for both inner and outer wrapping. 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,
In addition, the number of windings of the covering thread (covering twist number)
It can be improved by increasing. 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 and uniformity of the resulting product are strongly required and it is not possible to increase the thickness of the coated elastic yarn itself, it is necessary to The fineness of the yarn must be reduced to 18 denier or less, and the number of windings must be increased to about 3000 to 4000 t/m. However, when the number of windings of the covering yarn is increased in this way, the torque of the resulting covered elastic yarn increases, which causes problems such as snarls that occur during knitting, and increased number of stitch irregularities in the resulting knitted fabric. Therefore, it was not preferable when industrially producing double-covered elastic yarns. [Problems to be Solved by the Invention] Therefore, in order to solve the problem of increased torque accompanying improved coverage, the present invention reduces torque without reducing the number of governing twists and increases the The main objective is to provide a method for producing an excellent coated elastic yarn that has sufficient governing twist to exhibit coverage and a uniform appearance, yet exhibits sufficiently low torque properties. That is, the main object of the present invention is to provide a fabric with excellent coverage and uniformity, easy knitting without snarling and frizz during knitting, and high transparency and a well-balanced knitted surface. It is an object of the present invention to provide an excellent double-covering elastic yarn that can yield a knitted fabric with excellent elasticity and durability, and a manufacturing method that can obtain it. Another object of the present invention is to obtain a double-covered elastic yarn that can be made into a knitted fabric with excellent transparency and a flat and uniform appearance. [Means for solving the problem] In order to achieve this object, the present invention wraps two covering yarns made of long fibers of a thermoplastic polymer around a core yarn made of elastic fibers in different directions. In a method for producing a double covered elastic yarn by double winding, a non-bulky torque type false twisted yarn having a torque in the opposite direction to the winding direction is used as the inner wrapping covering yarn. A method for producing double-covered elastic yarn characterized by: The torque in the direction opposite to the winding direction as used herein means that the torque of the false twisted yarn increases due to winding and twisting. The elastic fibers used in the method of the present invention are preferably polyurethane elastic fibers commonly referred to as spandex fibers, but other types of elastic fibers may also be used. 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 strength, abrasion resistance, etc. are preferred, and among polyamides, nylon 6 and nylon 66 fibers are particularly preferred as they have particularly excellent properties. The non-bulky torque type false twisted yarn used as the inner wrapping covering yarn refers to a false twisted yarn that does not substantially exhibit bulkiness in the covered state, and is generally not the same as the torque type false twisted yarn. That is what is said. For this torque type false twisted yarn, the normal woolly false twisting processing method changes the number of false twists (Tt/m) to its yarn fineness (D denier).
False twisting is carried out in the range of 25,000 to √ to 30,000/√, but it is in the range of 3,000/√≦T≦18,000/√, preferably in the range of 5,000/√≦T≦18,000/√, and furthermore, The heat setting temperature is 40 to 110 degrees Celsius lower than the melting point of the yarn,
Preferably, it can be obtained by false twisting at a lower temperature of 50 to 90°C. The torque-type false-twisted yarn obtained under these false-twisting conditions has almost no deformation of the single yarn cross section due to the false-twisting process (see Figure 1), so it prevents irritation caused by the covered elastic yarn and has excellent symmetry. preferred for retaining The winding direction of the inner wrapping covering yarn is the direction in which the torque of the false twisted yarn increases, which means that when using false twisted yarn with S direction torque obtained by S twist false twisting, the winding direction (covering On the other hand, when using a false twisted yarn with Z direction torque obtained by Z twisting and false twisting, it means that the winding direction (covering twisting direction) is the S direction. As the outer covering thread, a flat yarn which is commonly used as a covering thread may be used. In addition, double covering yarn production in which a covering yarn is wound around a core yarn is performed using a normal double covering yarn manufacturing method, that is, two covering yarns are each wrapped around a core yarn, and the twisting direction is changed outward. This can be done using double covering, which is wrapped twice. [Function] The present invention uses a non-bulky torque type false twisted yarn as the inner wrapping yarn to reduce torque without deteriorating the covering property or uniformity, and It is characterized in that the direction in which the yarn is wound is the direction in which the torque of the false twisted yarn increases. In double covering elastic yarns (hereinafter simply referred to as covered elastic yarns), the twisting directions are reversed between the inside and outside windings, so the torques due to the covering twists cancel each other out between the inside and outside windings. . However, in the past, the same flat yarn was used for both the inner and outer covering yarns, so even if the number of covering twists of the outer covering yarn was lowered, the resulting torque would be considerably large, making it necessary to It was difficult to completely offset both torques under conditions that provided good coverage. As a result, in the conventional covered elastic yarn, the torque due to the outer covering twist appears as the torque of the covered elastic yarn. This torque can be reduced by significantly reducing the number of twists in the outer covering, but
At the same time, there is a drawback that the coverage is reduced and the appearance is impaired. Therefore, as a result of considering ways to reduce the torque of the covered elastic yarn without lowering the number of twists in the outer covering, we decided to use a torque-type false twisted yarn, which has a torque in the opposite direction to the twist direction of the inner covering yarn, as the inner covering yarn. The present invention was developed based on the finding that the torque caused by the covering twist of the outer covering yarn can be reduced without impairing the covering properties or uniformity by producing a covered elastic yarn using the above method. be. That is, in the present invention, since a torque type false twisted yarn having a torque in the direction opposite to the twisting direction of the inner covering is used as the covering yarn used for the inner side, the torque of the torque type false twisted yarn and the inner covering yarn are The torque due to twisting is synergistic with the torque due to the inner winding, which becomes balanced with the torque due to the outer winding, thereby increasing the torque of the entire covered elastic yarn without reducing the number of outer covering twists. It can be reduced. As a result, even if a sufficient number of covering twists is applied to give the resulting covered elastic yarn good coverage and uniformity, the torque can still be reduced. In addition, the production speed of covered elastic yarn is generally determined by the number of twists in the inner covering, which has a higher number of twists, but according to the method of the present invention, it is possible to reduce the number of twists in the inner covering without increasing torque. As a result, the production speed of double covering can be increased without compromising coverage, uniformity and low torque. On the other hand, crimped type false twisted yarn (Woolly type false twisted yarn) obtained by false twisting with a high false twist number (Tt/m) of about 25000/√~30000/√ was used as the inner covering yarn. However, since the torque of the crimped type false twisted yarn is considerably larger than that of the torque type false twisted yarn used in the present invention, the torque due to the inner winding tends to be excessive. Therefore, it is not easy to balance the torque. In addition, since crimped type false twisted yarn exhibits bulkiness in the covered state, it has excellent covering properties, but the surface appearance of the obtained covered elastic yarn is not sufficiently uniform and tends to become uneven, which is not the objective of the method of the present invention. It is difficult to obtain a knitted fabric with extremely high transparency and a flat, uniform appearance required for high-class women's stockings. Furthermore, since the crimped type false twisted yarn has a deformed single yarn cross section as shown in Figure 1, it is easy to cause irritation in the resulting covered elastic yarn, and from this point of view it is important to create a knitted fabric with a uniform appearance. It is difficult. [Examples and Comparative Examples] - Example 1 A 20-denier, 3-filament spandex fiber yarn was stretched 3.2 times and double covered (lower twist Z direction, upper twist S direction) using a normal covering machine.
direction), twisting speed 16000 rpm, yarn speed 5.3 m/
I did it at min. The covering yarn used in this case was a nylon 6-filament yarn of 15 denier and 5 filaments, and the yarn form was a flat yarn, a torque type false twisted yarn, or a crimp type false twisted yarn, as shown in Table 1. The false twisted yarn used here was a false twisted yarn having a torque in the S direction obtained by performing S direction false twisting, heat setting, and untwisting at the number of false twists and the temperature shown in Table 1. The torque of the obtained covered elastic yarn is
Torque is developed by applying a load of 1 g to the center of 1 m of covered elastic yarn and letting it hang down.The number of twists produced (number of twists per 50 cm) is measured, and the value converted to the number of twists per 1 m (torque index) ). Further, the coverage of the obtained covered elastic yarn was evaluated visually using a magnifying glass according to the following criteria. ◎: Excellent △: Slightly poor ○: Good ×: Poor Next, the obtained covered elastic yarn was made into a knitted fabric by a usual method, and its evenness was evaluated using the same criteria as in the case of covering property. In addition, the degree of snarling that occurs during knitting was evaluated using the following criteria. ◎: None ○: Almost none ×: Many

[Table] As can be seen from the results, in the coated elastic yarns No. 1 to 6 obtained by the method of the present invention, the torque of the coated elastic yarns was reduced without reducing the number of outer covering twists, and the covering properties and A coated elastic yarn with excellent torque properties could be obtained, and a knitted fabric with excellent uniformity could be obtained without any snarling during knitting. In contrast, when using the conventional method using flat yarn as the inner and outer covering yarns (No. 11, 12)
When the number of outer covering twists is high, coverage and uniformity are good, but on the other hand, there is a problem that torque is high and there is a lot of chattering during knitting. In addition, as can be seen from the results of No. 13, when a crimped type false twisted yarn is used as the inner covering yarn, the inner wrapping torque increases due to the large torque of the crimped type false twisted yarn, resulting in a coating that can be obtained. On the contrary, the torque of the elastic yarn tends to be high, and the symmetry is poor.・Example 2 A 20-denier, 3-filament spandex fiber yarn was stretched 3.2 times and double covered using a normal covering machine (lower twist in Z direction, upper twist in S direction).
The direction and number of covering twists are both inside and outside.
2600t/m), twisting speed 16000rpm, yarn speed
The speed was 6.2m/min. The covering thread used at this time was
It was a 15 denier 5 filament nylon 6 filament yarn, and the yarn form was a flat yarn, a torque type false twisted yarn, or a crimp type false twisted yarn as shown in Table 1. The false twisted yarn used here had the number of false twists and temperature shown in Table 2.
The false twisted yarn had a torque in the S direction and was obtained by false twisting in the S direction, heat setting, and untwisting.

〔Effect of the invention〕

The covered elastic yarn obtained by the method of the present invention uses a non-bulky torque type false twisted yarn as the covering yarn wrapped inside, and the winding direction of the inner covering yarn is adjusted so that the torque of the false twisted yarn is Since the direction of increase is set, it is possible to reduce the torque of the covered elastic yarn obtained without lowering the number of twists of the outer covering. Therefore, it is possible to obtain an excellent coated elastic yarn that has high coverage, a uniform appearance, and exhibits low torque characteristics. This coated elastic yarn is easy to knit, has good covering properties, and is useful for obtaining high-quality knitted fabrics with excellent transparency and a flat, uniform appearance. Further, according to the method of the present invention, the number of twists of the inner covering can be lowered without increasing the torque of the obtained covered elastic yarn, so the production speed of the covering can be increased.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing a single yarn cross-sectional form of the torque type false twisted yarn (torque type false twisted yarn in Example 1 No. 4) used as the inner covering yarn in the method of the present invention, and FIG. FIG. 3 is a sectional view showing a single yarn cross-sectional form of a flat yarn (flat yarn in Examples 1 and 2) used as an outer covering yarn. Further, FIG. 3 is a sectional view showing the single yarn cross-sectional form of the crimp type false twisted yarn used as the inner covering yarn in No. 13 of Example 1 and No. 15 of Example 2.

Claims (1)

[Claims] 1 In a method for producing a double covering elastic yarn by wrapping two covering yarns made of long fibers of a thermoplastic polymer around a core yarn made of elastic fibers in different winding directions, A method for producing a double covering elastic yarn, characterized in that a non-bulky torque type false twisted yarn having a torque in the opposite direction to the winding direction is used as a covering yarn.