JPH04370236A - Production of cored yarn machine sewing thread - Google Patents

Abstract

PURPOSE:To stably produce cored yarn machine sewing thread excellent in sewability, good in seam strength and improved in seam appearance at a low cost. CONSTITUTION:A molten polymer is spun to produce two kinds of raw yarns of low-elongation filaments having >=35% elongation and highelongation filaments having >=20% difference in elongation from the low-elongation filaments. The resultant raw yarns 11 and 12 are then doubled and stretch- broken between feed rollers 13 and stretch-breaking rollers 14, then combined with air nozzles 15 and subsequently wound with a winder 16.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a core yarn sewing thread having excellent high-speed sewing properties.

0002

[Prior Art] The main sewing thread currently used is polyester sewing thread, and depending on the form of the raw thread, there are two types: polyester filament sewing thread made of polyester filament thread and polyester spun sewing thread made of polyester spun thread (spun yarn). It is broadly divided into

Polyester filament sewing thread has high tenacity and excellent seam appearance, but because of its low porosity with the needle hole, it is easily affected by heat and has the problem of poor strength retention after sewing. have.

On the other hand, polyester spun sewing thread has fluff and high porosity, so it has excellent strength retention after sewing, and is also excellent in sewability, but it has poor seam appearance compared to polyester filament sewing thread. It has some disadvantages.

As described above, if a low-cost polyester sewing thread that combines the advantages of both filament sewing thread and spun sewing thread could be developed, it would have revolutionary technical significance in the sewing field. Various proposals have been made to develop yarns that combine the advantages of filament yarns and spun yarns. A typical example is a composite core yarn yarn in which a filament is used as a core yarn and spun fibers are wrapped around it. In the field of sewing threads, core yarns have high sewability and excellent seam appearance, and are known to have performance that combines the excellent features of both filament sewing threads and spun sewing threads.

[0006]

[Problems to be Solved by the Invention] However, in the conventional production of core yarns, it is necessary to wrap spun fibers in filament yarns, and the method for this is to open multifilaments and overlap and twist them with drafted spun fiber bundles. A method for producing the fiber, or a method for forming the multifilament into a core and the spun fiber into a sheath by combining and twisting the multifilament and a drafted spun fiber bundle. However, due to the increased production cost and difficulty in production control in manufacturing these threads, they have not yet been able to become a general-purpose product on the market.

[0007] Core spun sewing threads are generally obtained by twisting together spun fibers drafted into multifilaments. In this method, the multifilament is not necessarily at the center of the core spun yarn, and as a result, there is a risk of a decrease in strength after sewing due to friction between the multifilament part exposed to the surface and the needle hole. Therefore, there is a problem that production costs are high.

The present invention eliminates the drawbacks of the prior art as described above, and provides a manufacturing method for stably supplying core yarn sewing thread with good sewability, strong seam strength, and excellent seam appearance at a low cost. This is what we are trying to provide.

[0009]

[Means for Solving the Problems] As a result of intensive studies to achieve the above object, the inventors of the present invention have made a multifilament core by performing tension cutting on multifilaments having two different elongations. It is possible to stably produce core yarn sewing thread with a sheath of stretched spun fibers at low cost, and the multifilament on the high elongation side has an intrinsic viscosity of 0.
．． 7 or more, and when the low elongation side multifilament is made by spinning and drawing polyester with an intrinsic viscosity of 0.7 or more at a spinning speed of 2000 m/min or more, the sewability and seam strength are particularly high. The inventors have discovered that a core yarn with improved properties can be obtained, leading to the present invention.

That is, the present invention provides a method for producing a core yarn sewing thread composed of a composite yarn formed by mixing long filament synthetic fibers with short fibers as the core yarn, and in which the average elongation of the filaments on the low elongation side is 35. % or less, and the difference in elongation from the high elongation filament is 20% or more.The method is characterized in that a long and short composite yarn is obtained by doubling two types of filaments with different elongations and performing a tension cutting process. This is a method for producing core yarn sewing thread.

The multifilament used in the present invention is not particularly limited, but polyester is preferred from the viewpoint of cost and versatility. Here, polyester has terephthalic acid as the main acid component and at least 1
The type of glycol preferably refers to one whose main glycol component is an alkylene glycol selected from ethylene glycol, triethylene glycol, and tetramethylene glycol, and polyethylene terephthalate polyester is particularly preferred.

[0012] The composite yarn that is effective as a core yarn sewing thread for the purpose of the present invention has high elongation and low elongation when considering cutting only the filaments forming the sheath without cutting the multifilaments in the core. The difference in elongation of the filaments must be at least 20%; if it is less than this, the stretchability will be poor and neps will occur, and the appearance after sewing will also be poor. Also, the elongation of the multifilament on the low elongation side is 35
It is necessary to set it so that it is less than 35%.
If this is the case, the core-sheath structure of the composite yarn obtained by stretch-cutting will not be good, the core will come out on the surface, resulting in poor dyeing spots, and it will easily melt and cut during sewing, resulting in poor sewability.

[0013] Furthermore, the high elongation filament serving as the core yarn is made of polyester having an intrinsic viscosity of 0.7 or more.
In particular, it is preferable to improve the strength of the seam after sewing, while the low elongation filament that becomes the sheath thread has an intrinsic viscosity of 0 to improve fatigue resistance, abrasion resistance, and heat resistance during sewing.
．． Preferably, polyester having a molecular weight of 7 or more is melt-spun at a spinning speed of 2000 m/min or more and then further stretched if necessary. However, if the intrinsic viscosity is too high,
If the spinning speed is too high, stable spinning tends to become difficult, so it is desirable that the intrinsic viscosity is 1.0 or less and the spinning speed is 5000 m/min or less.

The present invention will be explained below based on the drawings. FIG. 1 is a schematic diagram of a spinning apparatus suitable for carrying out the present invention. In the figure, filaments 2 discharged from a spinneret 1 are cooled by a cooling air device 3. Next, the filament passing through the oil application device 4 below is stretched between codet rollers 5 and 6, further heat-treated by the godet roller 6, and wound up by a winder 7.

[0015] The raw yarn obtained by the above-mentioned apparatus is subjected to drawing of the filament on the low elongation side and random stretch cutting in an ordinary drawing apparatus or stretch cutting apparatus. After cutting, the fluff of the low elongation filament may remain protruding from the processed yarn, or may be wrapped around the outer layer of the filament using an interlace or a combination nozzle such as a swirl nozzle.

FIG. 2 shows a schematic diagram of a tension cutting apparatus suitable for carrying out the present invention. Here, the raw yarns 11 and 12 obtained by the apparatus shown in FIG. .

When the processed yarn thus obtained was used as a core yarn sewing thread, a sewing thread with high sewability and excellent seam appearance was obtained.

[0018]

[Examples] The present invention will be explained in more detail below with reference to Examples.

[0019]

[Examples 1 to 3, Comparative Examples 1 to 5] Polyethylene terephthalate (containing 0.3 wt% TiO2 as a matting agent) having an intrinsic viscosity of 0.64 was spun at a spinning speed of 1800 m/min using a known melt-spinning direct drawing machine. Except for melt spinning in minutes, other conditions were set so that 36 filaments with low elongation and 100 denier with high elongation were obtained. The low elongation side yarn and the high elongation side yarn are combined to make a 200 denier 72 filament, and the elongation of the low elongation side yarn and the high elongation side yarn are separated using a tension cutting machine. Stretch cutting was performed at an intermediate magnification. The long and short composite yarns obtained by tension-cutting were subjected to preliminary twisting. Three pre-twisted long and short composite yarns were aligned, pre-twisted, dyed with a disperse dye and coated with a silicone oil, and then subjected to a sewability test. The results are shown in Table 1.

[0020]

[Table 1]

From the results in Table 1, it can be seen that the long and short composite yarn obtained according to the present invention has excellent sewability as a core yarn sewing thread and has a good seam appearance. In addition, if the elongation of the low elongation raw yarn is 35% or more, the composite yarn obtained by stretch cutting will not have a good core-sheath structure, and the core will be exposed to the surface, resulting in poor dyeing. In addition, it was found that the filaments exposed to the surface were fused and cut during sewing, resulting in poor sewability. Furthermore, if the difference in elongation is less than 20%, the tension cutting properties are poor and the occurrence of neps is observed. Therefore, defects tend to occur in the appearance after sewing.

[0022] Regarding the evaluation of sewability, using two layers of polyester/cotton blend (65/35) work clothes fabric (using 34/2's), 100 m of the fabric was sewn using a lockstitch single needle sewing machine. A comprehensive evaluation was made regarding the number of rotations at which the thread melted, the sewing length until the thread broke, and the thread breakage. Excellent was evaluated as ◎, good as ○, fair as △, and poor as ×. Regarding the sewing appearance, the color tone, gloss, and uniformity of the thread were visually judged, and excellent was rated as ◎, good as ○, fair as △, and poor as ×. In addition, good tension cutting property is ○, occurrence of neps is △, and simultaneous filament breaking is ×.
Dyeing spots are determined visually by dyeing the yarn with a disperse dye on a stockinette knit, and ○ is good with no spots, △ is where some dark and light spots are observed, and smudge-like dark and light spots are judged. If this was observed throughout, it was marked as ×.

[0023]

[Examples 4 to 6] Long and short composite yarns were obtained in the same manner as in Example 1, except that polyethylene terephthalate fibers having an intrinsic viscosity listed in Table 2 (set to a difference in elongation of 46%) were used as the high elongation filaments. . This was twisted in the same way as in Example 1,
Table 2 shows the results of a sewability test after ply-twisting, dyeing, etc.

[0024]

[Table 2] From the results in Table 2, the high elongation filament has an intrinsic viscosity of 0.7.
It can be seen that when the polyester is made of the above polyester, the seam strength is particularly improved.

[0025]The seam strength was measured by untying the upper thread after sewing and using a low-speed extension type tensile tester. ◎: Excellent, ○: Good,
Evaluation was made in four stages: △: good, ×: bad.

[0026]

[Examples 7 to 10] Polyethylene terephthalate (containing 0.3% TiO2 as a matting agent) with an intrinsic viscosity of 0.64 was used for the core yarn (high elongation side yarn), and polyethylene terephthalate (containing 0.3% TiO2 as a matting agent) was used for the sheath yarn (low elongation side yarn). Intrinsic viscosity 0.64, 0.72, 0.8 for side yarn)
0.0.0.95 polyethylene terephthalate (containing 0.3% TiO2 as a matting agent) was melt-spun using a known melt-spinning direct drawing machine at a spinning speed of 2500 m/min and then stretched to obtain a low elongation side. Elongation 25%, high elongation side elongation 62
% and 36 filaments of 100 denier.

[0027] The low elongation side raw yarn and the high elongation side raw yarn are combined and 2
00 denier 72 filament, and tension cutting was performed using a tension cutting machine at a magnification between the elongation of the low elongation side raw yarn and the elongation of the high elongation side raw yarn.

The obtained long and short composite yarn was evaluated in the same manner as in Example 1, and the results are shown in Table 3.

[0029]

[Table 3] As is clear from the results, the long and short composite yarn obtained according to the present invention has excellent sewability as a core yarn sewing thread and has a good seam appearance.

[0030]

[Examples 11 to 14] Low elongation side yarns were spun at the spinning speed shown in Table 4 and then directly drawn, and the intrinsic viscosity was 0.85.
Table 4 shows the evaluation results of a long and short composite yarn obtained in the same manner as in Example 7 except that a 100 denier/36 filament multifilament with an elongation of 62% was used.

[0031]

[Table 4] From these results, it can be seen that the spinning speed of the low elongation side raw yarn, which becomes the sheath yarn of the long and short composite yarn, is in the range of 2000 m/min or more, which is particularly excellent in sewability and seam appearance. I understand.

[0032]

[Effects of the Invention] As explained above, according to the present invention, it is possible to stably supply core yarn sewing thread with good sewability, strong seam strength, and excellent seam appearance at low cost. It has a remarkable effect.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of a spinning device suitable for carrying out the present invention.

FIG. 2 is a schematic diagram of a tension cutting device suitable for carrying out the present invention.

[Explanation of symbols]

1 Spinneret 5 Godet roller 6 Godet roller 7 Winding machine 14 Cut-off roller 15 Air nozzle 16 Winder

Claims (3)

[Claims] Claim 1. A method for producing a core yarn sewing thread consisting of a composite yarn made by using a long fiber filament synthetic fiber as a core yarn and mixing it with short fibers, wherein the average elongation of the filament on the low elongation side is 35% or less. A core yarn sewing thread characterized by obtaining a long and short composite yarn by combining two types of filaments with different elongations and carrying out a tension cutting process, in which the elongation difference with the high elongation filament is 20% or more. manufacturing method. Claim 2: The filament on the high elongation side has an intrinsic viscosity of 0.
．． The method for producing a core yarn sewing thread according to claim 1, comprising polyester having a molecular weight of 70 or more and 1.00 or less. [Claim 3] The filament on the low elongation side has an intrinsic viscosity of 0.
．． 2000m/2000m of polyester of 70 or more and 1.00 or less
The method for producing a core yarn sewing thread according to claim 1 or 2, wherein the filament is melt-spun and drawn at a spinning speed of 5000 m/min or more.