JPH0252020B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a method for producing a double-covered elastic yarn in which a thermoplastic synthetic fiber yarn such as polyamide is double-wound around an elastic yarn such as polyurethane yarn. 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, 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 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 the torque that increases as a result of improving the covering property, the present invention reduces the torque without reducing the number of covering twists and increases the The main objective is to provide a method for producing an excellent coated elastic yarn that has sufficient covering 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 a method for obtaining an excellent double-covering elastic yarn, which provides a knitted fabric with excellent elasticity and durability. 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 the method of manufacturing a double covering elastic yarn by double winding the outer wrapping yarn, a non-bulky torque type false twisted yarn having a torque in the same direction as the winding direction is used as the outer wrapping yarn. A method for producing double-covered elastic yarn, characterized by: Here, the torque in the same direction as the winding direction means that the torque of the false twisted yarn is reduced by 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 covering yarn for outer wrapping refers to a false twisted yarn that does not substantially exhibit bulkiness in the covered state, and is generally referred to 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 25000/√ to 30000/√, while the range is 3000/√≦T≦18000/√, preferably in the range of 5000/√≦T≦18000/√, and furthermore, the 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 outer wrapping covering yarn is the direction in which the torque of the false twisted yarn is reduced. This 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 a Z direction torque obtained by Z twisting and false twisting, it means that the winding direction (covering twisting direction) is the Z direction. As the covering thread for wrapping on the inside, 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 outer wrapping yarn to reduce torque without deteriorating the covering property or uniformity, and It is characterized in that the yarn is wound in a direction in which the torque of the false twisted yarn is reduced. In double covering elastic yarn (hereinafter simply referred to as covered elastic yarn), the winding directions are reversed for the inside and outside windings, so the torques due to the covering twists cancel each other out between the inside and outside windings. be. 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 outer winding diameter would be the same as the inner winding diameter. Since the torque is considerably larger than that of the outer winding, the torque due to the outer winding is considerably large, and it is difficult to completely cancel out both torques under conditions that provide sufficient 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, we investigated ways to reduce the torque of the covering elastic yarn without lowering the number of twists in the outer covering, and found that a torque-type false twisted yarn, which has a torque in the same direction as the outer covering twist direction, was used as the outer covering yarn. The present invention was developed based on the finding that by manufacturing a covered elastic yarn, the torque caused by the covering twist of the outer covering yarn can be reduced without impairing the covering properties or uniformity. That is, in the present invention, a torque type false twisted yarn having a torque in the same direction as the outer covering twisting direction is used as the covering yarn used on the outside where a large torque is generated, so that the torque of the torque type false twisted yarn is This reduces the torque caused by the covering twist, thereby making it possible to reduce the torque of the entire covered elastic yarn without reducing the number of outer covering twists. 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, if a 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/√ to 30000/√ is used as the outer covering yarn, , the torque due to the crimped type false twisted yarn is much larger than the torque due to the outer covering twist, so the torque due to the crimped type false twisted yarn appears in the obtained covered elastic yarn to a large extent, and it cannot be made into a low torque yarn. . In addition, since the crimped type false twisted yarn exhibits bulkiness in the covered state, the surface appearance of the obtained covered elastic yarn becomes uneven, resulting in a knitted fabric with excellent transparency and a flat, even appearance, which is the objective of the method of the present invention. is difficult to obtain. Furthermore, since the crimped type false twisted yarn has a deformed single yarn cross section as shown in Figure 1, the resulting coated elastic yarn becomes irritated, which also hinders the uniformity of the knitted fabric. Become. [Examples and Comparative Examples] - Example 1 A 20-denier, 3-filament spandex fiber yarn was stretched 3.2 times and double covered using a normal covering machine (lower twist in the Z direction, upper twist in the S direction).
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 an S-direction torque obtained by S-direction false-twisting, heat setting, and untwisting at the number of false twists and 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 a coated elastic yarn of m and letting it hang, and 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 the 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 〇: Almost none ×: Many

[Table] As can be seen from the results, in the coated elastic yarns No. 1 to 8 obtained by the method of the present invention, the torque was reduced without reducing the number of covering twists, and the covering property and
A coated elastic yarn with excellent low torque properties can be obtained, and there is no snarling during knitting.
A knitted fabric with excellent uniformity could be obtained. On the other hand, in the case of the conventional method using flat yarn as the inner and outer covering yarns (No. 21, 22)
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. 23, when a crimped type false twisted yarn is used as the outer covering yarn, a torque due to the large torque of the crimped type false twisted yarn appears, and the torque becomes high. Although the coverage was improved, the uniformity was 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 Z direction, upper twist 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
The yarn 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 S-direction torque obtained by S-direction false-twisting, heat setting, and untwisting.

[Table] As can be seen from this result, in the coated elastic yarns No. 9 to 15 obtained by the method of the present invention, even if the number of inner covering twists is lowered to the same level as the outer covering twist number, the torque is A coated elastic yarn with low coverage and excellent coverage could be obtained. Furthermore, by lowering the number of twists in the inner covering, it was possible to increase the productivity of the covering. On the other hand, in the case of the conventional method (No. 24) using flat yarn as the inner and outer covering yarns,
The torque is extremely high and there is a lot of chattering during knitting.
The symmetry was also reduced. In addition, as can be seen from the results of No. 25, when crimped type false twisted yarn is used as the outer covering yarn,
Both torque uniformity was significantly inferior. [Effects 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 outer wrapping yarn, and the winding direction of the outer covering yarn is the same as that of the false twisted yarn. Since the torque of the covered elastic yarn is reduced, the torque of the covered elastic yarn obtained can be reduced without reducing the number of covering twists. 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 drawings]

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. 6) used as the outer coating yarn in the method of the present invention, and FIG. FIG. 2 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 inner 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 outer covering yarn in No. 23 of Example 1 and No. 25 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 same direction as the winding direction is used as a covering yarn.