JP3866843B2 - Spinneret for hollow fiber - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention, when viewed in a cross section perpendicular to the fiber axis (hereinafter simply referred to as “fiber cross section”), the ratio of the occupied area of the hollow portion in the entire fiber cross section (hereinafter referred to as “hollow ratio”) Is related to a spinneret capable of melt-spinning ultra-high hollow fiber having a hollow ratio of 50% or more, and produces a lightweight, highly heat-retaining fiber with tightness and sharpness. It relates to a spinneret.
[0002]
[Prior art]
Conventionally, when melt spinning a hollow fiber, as shown in FIGS. 3 (a) and 3 (b), a hollow in which a plurality of discharge holes having arc-shaped slit channel holes are formed on the same circumference. A spinneret for yarn was generally used. However, the hollow ratio of the hollow fiber spun from such a spinneret was only 30 to 35%. Moreover, using such a spinneret, when trying to obtain a hollow fiber having a higher hollow ratio, as shown in FIGS. 4 (a) to (c), from the slit channel holes adjacent to each other, There has been a problem in that a recess is formed in a bonded portion to which the discharged polymer is bonded, or a defect occurs in bonding.
[0003]
A spinneret for solving such a problem and obtaining a hollow fiber having an improved roundness of a fiber cross section has been proposed in Japanese Patent Laid-Open No. 58-169507. Certainly, according to this spinneret, a hollow fiber having a substantially round fiber cross-section can be stably obtained without causing a hollow crack in a relatively small hollow ratio of 20% or less. Can do. However, when a yarn having a high hollow ratio exceeding 30% is to be produced, it is difficult to obtain such a yarn because the shape of the fiber cross section is inevitably distorted. That is, even when trying to obtain a shape in which the fiber cross section is close to a perfect circle, it has a big problem that it is difficult to become a perfect circle.
[0004]
[Problems to be solved by the invention]
The present invention seeks to provide a spinneret for solving such drawbacks in the prior art and stably producing a hollow fiber having a substantially perfect circle and a hollow ratio of 50% or more. If such a spinneret is to be provided, it becomes possible to stably and surely produce a hollow fiber having a substantially circular fiber cross-sectional shape and having a high hollow ratio, which is more than conventional. A hollow fiber excellent in lightness and heat retention can be obtained.
[0005]
[Means for Solving the Problems]
Here, according to the present invention, there is provided a spinneret having the following configuration which has solved the above-mentioned problem very skillfully.
[0006]
That is, the present invention provides a spinneret for hollow fibers having a plurality of discharge holes simultaneously satisfying the following requirements a to e for melt spinning a hollow multifilament yarn composed of a hollow single fiber having one hollow portion. It is.
a. Four or more and eight or less arc-shaped slit channel holes (H) are circumscribed around the circumference of the same circle (C), and the slit channel holes (H) have inner edges (Ei). ) In the vicinity of the ends of the part has a projecting flow path hole (h) projecting in a semicircular shape toward the approximate center of the circle (C),
b. On the polymer discharge surface of the die, when the opening channel area formed by the polymer wetting edge of the slit channel hole (H) group is S2, and the area surrounded by the circle (C) is S1 In the relational expression (R) = (S2 / S1) × 100, which is established between S1 and S2, the flow path occupancy (%) is 7% ≦ R ≦ 10%. There,
c. The diameter (D) of the circle (C) is 1.6 mm or more and 1.8 mm or less,
d. The interval (t) between the slit channel holes (H) adjacent to each other is 0.08 mm or more and 0.1 mm or less,
e. The ratio (S3 / S2 × 100) of the total opening channel area (S3) on the die discharge surface, which is composed only of the protruding channel hole (h) group, to the opening channel area (S2) is 2. 0% or more and 10.0% or less.
[0007]
In the following description of the present invention, “channel occupation ratio (R)” refers to a value (%) defined by the above formula, R = (S2 / S1) × 100.
[0008]
【Example】
Next, an embodiment of a spinneret for obtaining a hollow fiber having a substantially perfect fiber cross section with the above-described configuration and having a high hollow ratio will be described in detail below along with its function.
In the case of melt spinning a fiber made of a thermoplastic resin from a polymer including a hollow fiber, the polymer discharged from the spinneret is swelled immediately after discharge (so-called “ballus effect”), and then thinning occurs. Begins. This ballast effect plays a very important role in the hollowness of the hollow fiber obtained. That is, generally, when the melting temperature of the polymer is lowered, the ballast effect of the polymer discharged from the discharge hole is increased, and the hollow ratio of the obtained hollow fiber is increased. However, on the other hand, the higher the hollow ratio is, the harder the arcuate shape at the time of discharging the polymer discharged from the discharge hole is to be maintained as it is. Various modifications are made depending on the situation. Such deformation of the fiber cross-sectional shape depends on various factors as described above. Here, if these factors are enumerated taking the spinneret for hollow fibers of the present invention shown in FIG. 1 as an example, the number of arc-shaped slit channel holes (H), the diameter (D) of the slit channel holes , spacing width between the slits passage holes adjacent to each other (t), the flow path occupancy of the (R), occupancy of the protruding flow path hole area during the area of a circle (C), 1 polymer discharge hole per hole There is. FIG. 1 is a plan view of one discharge hole, which is a basic unit for spinning one single fiber, which is formed in the spinneret .
[0009]
It will be described in detail with reference to FIG surface discharge hole provided in the spinneret of the present invention to the specific parameters and co.
FIG. 1 exemplifies a discharge hole for spinning a hollow single fiber (single filament) constituting a multifilament . In order to spin a multifilament, a discharge composed of such basic units is shown. Needless to say, a spinneret having holes corresponding to the number of filaments is used. 2 shows a fiber cross section of a hollow fiber obtained by melt spinning with the spinneret of FIG. 1, and a fiber cross section showing an example in which the hollow portion is formed with a high hollow ratio. It is.
[0010]
In FIG. 1 , the discharge hole formed in the spinneret of the present invention has six arc-shaped slit channel holes (H), and each of the slit channel holes (H) The outer edge (Eo) is inscribed in the circle (C). In addition, the slit channel holes (H) adjacent to each other are equally arranged on the circle (C) with a slight interval (t).
[0011]
Next, in order not to form the yarn (Fig. (A)) and the yarn (Fig. (B) and (c)) in which the fiber cross-sectional shape is deformed as shown in FIG. It is important to provide a projecting channel hole (h) projecting in a substantially inward normal direction of the circle (C) at the inner edge (Ei) in the vicinity of both ends of each slit channel hole (H). It is important that the protruding flow path holes (h) are provided in pairs symmetrically opposite to each other and adjacent to the slit flow path holes (H) adjacent to each other with an interval (t). The number of slit channel holes (H) is preferably large in order to form a substantially circular fiber cross-sectional shape. ~ 8 are preferred.
[0012]
Furthermore, the area of the inner region of the circle (C) surrounded by the inscribed circle (C) inscribed in the outer edge (Eo) of the slit flow path hole (H) is S1, and is surrounded by the polymer wetting edge of the discharge hole. When the formed total opening channel area is defined as S2, it is necessary that these S1 and S2 satisfy the relational expression of 7% ≦ R = (S2 / S1) × 100 ≦ 10%. In this relational expression, in the present invention, R is referred to as “channel occupation ratio” as described above. If this channel occupation ratio (R) is less than 7%, the polymer bonded portion as shown in FIG. 4 (a) becomes a defective hollow fiber, and if it exceeds 10%, the hollow ratio is 50% or more. It becomes difficult to obtain a hollow fiber having a high hollow ratio.
[0013]
However, the channel occupation ratio (R) is greatly influenced by the gap width (t) separating the arc-shaped slit channel holes (H) adjacent to each other. In further remarks regarding the relationship between the interval width (t) and the channel occupation ratio (R), generally, when t is small, R is selected to be a small value, and conversely, when t is large, R is selected. It is preferable to select a large value. However, in order to obtain a yarn having an ultrahigh hollow ratio of 50% or more, it is important to have a relationship of 7% ≦ R ≦ 10% as described above. Experiments have shown that t) is preferably 0.08 mm or more and 0.1 mm or less. If t is too small, the discharged polymer is joined quickly, and it becomes easy to form a flat hollow fiber. Further, the spinneret is easily deformed by the discharge pressure of the polymer, which is not preferable in terms of the strength design of the die. . Moreover, when t becomes too large, joining is delayed, and therefore, the polymer is not sufficiently bonded to cause hollow cracking.
[0014]
Further, the diameter (D) of the inscribed circle (C) is more likely to be a super hollow fiber. However, due to constraints such as yarn denier, cap surface space, and spinning stability, 1.6 mm or more. It is preferable to be 8 mm or less.
[0015]
Next, in order not to form a yarn with poor polymer bonding as shown in FIG. 4, the center of the circle (C) is formed on the inner edge (Ei) in the vicinity of both ends of each slit channel hole (H). Protruding channel hole pairs (h) projecting in a semicircular shape toward the direction are provided, and discharge holes (in the case of FIG. 1, six slit channel holes (H) and twelve projecting channel holes (h The ratio of the open channel area on the nozzle discharge surface occupied by the projecting channel hole (h) is 2.0% or more and 4.0% or less. Is preferred. In this case, when the ratio is less than 2.0%, polymer bonding tends to be poor, and when it exceeds 4.0%, it is difficult to obtain a yarn having a high hollow ratio of 50% or more.
[0016]
Furthermore, in order to stably produce a high hollow fiber of 50% or more, it is preferable that the polymer discharge amount per hole from the discharge hole is 2.0 g / min or more and 2.6 g / min or less. This is because when the discharge rate is less than 2.0 g / min, the discharge linear velocity of the polymer is lowered, causing discharge spots and cooling spots, the polymer is likely to be stuck poorly, and yarn breakage is likely to occur. is there. Moreover, if the discharge amount exceeds 2.6 g / min, the discharge linear velocity of the polymer is increased too much, and it becomes difficult to obtain a high hollow fiber of 50% or more due to delayed cooling.
[0017]
Finally, an experimental example using the spinneret having the discharge holes of the present invention described above will be described below.
Six arc-shaped slit channel holes (H) with an interval width (t) of 0.09 mm and the outer edge (Eo) inscribed in an inscribed circle (C) with a diameter (D) of 1.7 mm And arranged equally on the circle (C). At this time, the flow rate occupation ratio (R) is 8%, and the ratio of the area occupied by the protruding flow passage holes (h) to the total opening flow passage area of the discharge holes is 3%. The yarn was spun. When the fiber cross section of the obtained hollow fiber was observed, the fiber cross sectional shape was almost perfect circle, the hollow ratio was 55%, and there was no hollow crack.
[0018]
Moreover, the hollow ratio of the obtained hollow fiber is 53% and 51%, respectively, except that the channel occupation ratio (R) is 7% and 10%. No cracks occurred, and the fiber cross section was almost a perfect circle.
[0019]
【The invention's effect】
As described above, according to the present invention, it is possible to stably and reliably spin a high-hollow-ratio yarn having a substantially perfect circle and 50% or more. A material with a sense of waist and sharpness can be obtained. Further, since there is no viscosity unevenness or poor lamination of the polymer to be spun, stable spinning can be performed without causing yarn breakage. For this reason, there is an extremely remarkable effect that it is possible to obtain a high-quality yarn that is excellent in yarn production performance and that is ultralight.
[Brief description of the drawings]
FIG. 1 is a plan view illustrating a discharge hole formed in a spinneret for hollow fibers of the present invention.
FIG. 2 is a view illustrating a fiber cross section of a hollow fiber obtained at the discharge hole of FIG. 1;
FIGS. 3A and 3B are plan views showing conventional ejection holes. FIGS.
4A is a fiber cross-sectional view of a hollow fiber obtained by the discharge hole illustrated in FIG.
(B) And (c) It is a fiber sectional view of the hollow fiber obtained with the discharge hole of Drawing 3 (b).
[Explanation of symbols]
1 Spinneret Main Body C Inscribed Circle Ei Inner Edge Eo Outer Edge H Slit Channel Hole h Projected Channel Hole D Diameter of Inscribed Circle t Distance between Discharge Holes Adjacent to each other

Claims (1)

A spinneret for hollow fibers having a plurality of discharge holes simultaneously satisfying the following requirements a to e for melt spinning a hollow multifilament yarn composed of a hollow single fiber having one hollow portion .
a. Four or more and eight or less arc-shaped slit channel holes (H) are circumscribed around the circumference of the same circle (C), and the slit channel holes (H) have inner edges (Ei). ) In the vicinity of the ends of the part has a projecting flow path hole (h) projecting in a semicircular shape toward the approximate center of the circle (C),
b. On the polymer discharge surface of the die, when the opening channel area formed by the polymer wetting edge of the slit channel hole (H) group is S2, and the area surrounded by the circle (C) is S1 In the relational expression (R) = (S2 / S1) × 100, which is established between S1 and S2, the flow path occupancy (%) is 7% ≦ R ≦ 10%. There,
c. The diameter (D) of the circle (C) is 1.6 mm or more and 1.8 mm or less,
d. The interval (t) between the slit channel holes (H) adjacent to each other is 0.08 mm or more and 0.1 mm or less,
e. The ratio (S3 / S2 × 100) of the total opening channel area (S3) on the die discharge surface, which is composed only of the protruding channel hole (h) group, to the opening channel area (S2) is 2. 0% or more and 10.0% or less.

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