JP3359755B2 - Polyester thick & thin yarn manufacturing method - Google Patents

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 polyester thick and thin yarn. More specifically, the present invention relates to a method for producing a raw polyester yarn which can provide a woven or knitted fabric having a natural feeling without a feeling of irritability.

[0002]

2. Description of the Related Art A method for expressing a so-called thick and thin difference in the direction of the fiber axis of a polyester filament has been known for a long time. For example, Japanese Patent Application Laid-Open No. 60-181316 discloses a method in which a polyester undrawn yarn having a birefringence of 12 to 50 × 10 ⁻³ is drawn at a maximum draw ratio of 0.40 to 0.55 times. Also, JP-A-63-21131
No. 8 discloses that a polyester multifilament is stretched in the first stage (stretching ratio D ₁ ) while squeezing at a temperature not higher than the glass transition point, and then naturally stretched in the second stage stretching (stretching ratio D ₂ ). A method is disclosed in which stretching is performed at a magnification (NDR) or less and each stretching magnification is set to 0.7 × NDR ≦ D ₁ × D ₂ <NDR.

[0003]

However, when dyeing a fabric using a yarn obtained by the method described in Japanese Patent Application Laid-Open No. 60-181316, the shading difference based on thick and thin is too large, resulting in a feeling of irritation. There is a disadvantage of doing so. Further, the method described in Japanese Patent Application Laid-Open No. 63-21318 disperses the thick and thin finely, so that the difference in shading becomes too small and there is no irritating feeling, but the appearance becomes plain. Therefore, it is far from the natural sensation, and also has a poor span-like feel.

[0004] The present invention is intended to improve the above-mentioned drawbacks, and an object of the present invention is to provide a raw yarn for obtaining a fabric which does not have a feeling of irritability but exhibits a natural spot feeling and has a spun-like feel and luster. Specifically, an object of the present invention is to randomly disperse the length and interval (expression frequency) of the large fineness portion in the fiber longitudinal direction and between the single yarns.

[0005]

SUMMARY OF THE INVENTION According to the present invention, when spinning a polyester flat multifilament having a long-axis / short-axis ratio of 1.5 to 3.5 in the cross section of a single yarn, a spinning hole of a die is made to have a long axis.
Equally arranged on the pitch circle diameter so that the directions are parallel,
Number of filaments spun from one die is equivalent to die diameter
On the other hand, with a diameter of 0.4 / mm or more, the spinning is performed such that the major axis is substantially perpendicular to the blowing direction of the spinning cooling air, and winding is performed.
After aging, the film is stretched at a stretching ratio (DR) in the range of 0.85 NDR ≦ DR ≦ 0.97 NDR of the average natural stretching ratio (NDR) and at a temperature equal to or lower than the glass transition point.

In the polyester of the present invention, polyethylene terephthalate constitutes at least 80% of its constituent units, and an aromatic dicarboxylic acid such as isophthalic acid and pentasodium sulfoisophthalic acid as an acid component, and diethylene glycol as a glycol component. Butanol and the like may be copolymerized.

The flat single yarns constituting the polyester flat multifilament yarn spun in the present invention must have a long-axis / short-axis ratio of single yarn cross section of 1.5 to 3.5. The axis is the longest axis length of a straight line connecting two points on the outer periphery of the single yarn section as shown in FIG. 1, and the short axis is the shortest axis length. When the ratio of the major axis / minor axis is smaller than 1.5,
The thick and thin expression effect obtained by the method of the present invention is poor. That is, the shielding area of the spinning cooling air that hits immediately after spinning becomes small, and the randomness of thick and thin becomes poor. On the other hand, if the ratio of the major axis to the minor axis is larger than 3.5, the randomness of the thick and thin is increased, but the gloss of the cloth becomes too metallic. Since the flat yarn may have the above-mentioned cross-sectional shape, it may have a projection or a depression in addition to a flake-shaped simple flat yarn.

In spinning such a flat yarn, the larger the number of filament single yarns spun from the spinneret per unit area is, the more effective it is. 0.4 / mm
The diameter is preferably equal to or more than the diameter. Therefore, for example, it is preferable to spin out 30 or more flat filaments from a 75 mmφ die, and the fineness of a single filament is 1.7 to
It is preferably 2.8 denier.

The spinning of the flat yarn is carried out by directly spinning a flat yarn having a flat spinning hole shape, or by spinning a flat yarn.
As described in Japanese Patent No. 9803, a single yarn spun from a plurality of circular spinning holes adjacent to each other may be fused to form a flat or irregular shaped cross section. Also, the number of spinning holes in the die is preferably as described above, but the arrangement of each spinning hole is preferably arranged on the pitch circle diameter, and each flat single yarn is formed from a single direction as described later. Same direction for all single yarns with cooling air (direction substantially perpendicular to long axis of single yarn)
In order to blow the cooling air from the nozzle, the spinning holes of the spinneret should be arranged so that the major axis directions thereof are parallel.

The multifilament spun from the die as described above blows spinning cooling air from a direction substantially perpendicular to the long axis of the single yarn as shown in FIG. Cooling air is 0.2 ~
It is preferable to perform spraying at a strength of about 0.4 m / sec, and it is preferable to perform spraying only from one direction.

The undrawn flat multifilament yarn wound and wound as described above is then subjected to aging.
It is preferable to perform aging in an atmosphere of 25 ° C. ± 2 ° C. × 70% ± 10 RH% corresponding to standing for 20 hours to 150 hours. When aging is performed in the atmosphere for more than 150 hours, a stretching operation is performed. The properties tend to decrease, which is not preferred. If the aging time is less than 20 hours, the undrawn yarn immediately after spinning is unlikely to develop thick and thin even at a low draw ratio.

Next, the aged unflattened multifilament yarn is subjected to an average natural stretching ratio (N
The film is stretched at a draw ratio in the range of 0.85 NDR to 0.97 NDR of DR) and at a temperature not higher than the glass transition point. The average natural stretching magnification in this case is St shown in FIG.
is a value derived from the less-Strain curve,
The asymptote from the point where the tensile stress when the undrawn yarn is drawn starts to rise and the fulcrum of the asymptote from the point where the tensile stress suddenly starts rising on a straight line are worthy of. Since the individual single yarns constituting the yarn have different degrees of orientation, the natural draw ratio also differs depending on the individual single yarns. Therefore, the natural stretching ratio is calculated as the average value of the whole.

FIG. 4 (a) shows the appearance of the thick fineness portion (thick portion) of the thick & thin yarn obtained by the method of the present invention, and FIG. 4 (b) and FIG. In contrast, the length and appearance position of each large fineness portion are more random than conventional ones.

[0014]

In the present invention, the filament closer to the spout cooling air blowing portion is cooled quickly, but the spun yarn has a flat shape, so that the filament farther from the blowing portion blocks part of the cooling air. Then, the filament is gradually cooled as compared with the filament closer to the blowing section. Therefore, when viewed as a whole multifilament, the individual undrawn yarns in the yarn have different cooling conditions and different degrees of orientation. As a result, the expression state of thick & thin between each single yarn is greatly different, and the multifilament composed of them is, as a whole,
It is composed of random thick fineness portions (thick portions).

[0015]

The present invention will be described in more detail with reference to the following examples. (Example 1) Polyethylene terephthalate containing 0.35% by weight of titanium dioxide (intrinsic viscosity 0.64 measured with a mixed solution of phenol / tetrachloroethane = 6/4)
0) is melted at 290 ° C.
Forty-eight slit holes having a length of 0.35 mm / mm were spun out from a die which was drilled at equal intervals and in parallel on a double circle.

Spinning is performed so that the long axis of the yarn spun from each slit hole and the blowing direction of the cooling air are at right angles, and the yarn is wound at a speed of 1500 m / min and 225d / 48.
When the undrawn yarn of f was wound up, the ratio of the long axis / short axis of the obtained undrawn yarn was 2.5.

Next, this was left to stand in an atmosphere of 25 ° C. × 70% RH and aged for 30 hours. The average natural draw ratio of the undrawn yarn is 2.5, and the draw ratio is 2.0.
(0.8NDR), 2.13 (0.85NDR), 2.
25 (0.9NDR), 2.43 (0.97NDR),
At 2.5 (NDR), the film was stretched at a roll heater temperature of 68 ° C., and heat-set at 115 ° C. of a plate heater. Table 1 shows the results.

[0018]

[Table 1]

(Example 2) Spinning and winding and aging were carried out in the same manner as in Example 1 except that the slit holes of the die were changed to the conditions shown in Table 2, and the film was stretched at 0.9 times the average natural magnification to obtain five types. Of 100d / 48f. Each was made into a plain woven fabric used for the course, scoured to dyed, and compared. Table 2 shows the results.

[0020]

[Table 2]

[0021]

The fabric using the polyester thick & thin yarn obtained by the method of the present invention has a natural spot feeling, a spun-like feeling and a moderate gloss. For this reason, such thick and thin yarns are suitable for use in women's thin materials such as blouses and dresses.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing a long axis and a short axis of a flat multifilament yarn.

FIG. 2 is an explanatory diagram showing a relationship between spun multifilaments and cooling air.

FIG. 3 is a graph showing a stress-strain curve.

FIG. 4 is an explanatory diagram showing a form of expression of a thick & thin yarn.

Claims (1)

(57) [Claims] 1. The long axis / short axis ratio of a single yarn cross section is 1.5 to 1.5.
Spinning of 3.5 polyester flat multifilament
When spinning , the spinning holes of the spinneret should be
Are arranged equally on the switch circle diameter and spun from one die.
0.4 filament / mm diameter or less with respect to the diameter of the base
Above, after spinning and aging so that the long axis is substantially perpendicular to the spinning cooling air blowing direction,
Average natural stretch ratio (NDR) 0.85 NDR ≦ DR ≦
A method for producing a polyester thick & thin yarn, comprising drawing at a draw ratio (DR) in the range of 0.97 NDR and a temperature not higher than the glass transition point.