JPH066460U - Spinneret for hollow fibers - Google Patents

Abstract

(57) [Summary] [Configuration] A plurality of arc-shaped slit holes are provided, and the center of each arc is different from the center of the circumscribed circle of the arc-shaped slit hole group. A spinneret for hollow fibers, wherein a protrusion is provided at a position on the inner edge of the slit hole that is close to both ends of the slit hole and away from the ends of the slit hole. [Effect] It becomes possible to melt-spin a hollow fiber having a high hollow ratio and a uniform wall thickness and excellent circularity.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a spinneret for hollow fibers for melt-spinning hollow fibers having a high hollow ratio and a uniform wall thickness and excellent circularity.

[0002]

[Prior art]

 For melt-spinning hollow fibers, a spinneret for hollow fibers is generally used, in which arc-shaped slit holes, which are discontinuous in at least one place as shown in FIGS. 3 (a) and 3 (b), are arranged on the same circumference. Is used. However, when a hollow fiber having a large hollow ratio is spun out from such a spinneret, the resulting hollow fiber has a hollow at the joint as shown in FIGS. It has the disadvantage of becoming poor.

As a solution to this drawback, for example, Japanese Patent Application Laid-Open No. 58-169507 proposes a spinneret in which both ends of a slit hole are enlarged as shown in FIGS. 5 (a) and 5 (b). . However, in such a slit hole, as the flow behavior of the melt-spun polymer, a stress that opens outward and a stress that gathers in the direction of the center of gravity act, so that the ends of the slit holes facing each other are not enough during spinning. There was a problem that they were not joined or the roundness was inferior.

Further, Japanese Utility Model Publication No. 2-43879 discloses a spinneret having slit holes in which arcuate slits are arranged on the same circumference as shown in FIG. A spinneret has been proposed in which a semicircular protrusion is provided at a position distant from the slit hole end at the inner edge of the hole. According to this spinneret, a hollow fiber having a high hollow ratio and a uniform wall thickness can be obtained, but as shown in FIG. 7, the joint portion was projected to the outside and the circularity was poor.

[0005]

[Problems to be solved by the device]

 The present invention solves the above problems and provides a spinneret for hollow fibers, which is capable of melt-spinning hollow fibers having a high hollow ratio and a uniform wall thickness and excellent circularity. It is a subject.

[0006]

[Means for Solving the Problems]

 The present invention relates to a hollow-fiber spinneret having a plurality of arc-shaped slit holes. A gist of a spinneret for hollow fibers is that a protrusion is provided at a position distant from the end of the slit hole at the inner edge of the hole.

Hereinafter, the present invention will be described in detail with reference to the drawings. 1 (a) to 1 (c) are schematic views showing an embodiment of the present invention, and FIG. 2 is a cross-sectional view of a hollow fiber obtained by melt spinning from the spinneret of FIGS. 1 (a) to 1 (c). .

A semi-circular protrusion 2 is provided at the inner edge of the slit hole near the end of the slit hole 1, that is, at a position apart from the end of the slit hole in the arc-shaped slit hole.

Although each slit hole has a center of an arc different from the center of the circumscribed circle of the arcuate slit hole group, the center of each of the slit holes 1 is the midpoint of the arc and the circumscribed circle of the arcuate slit hole group. It is preferable to set a point on the straight line connecting the centers to the slit hole side by a distance A defined by the following equation from the center of the circumscribed circle. (N-1) R / 8 ≥ A ≥ (n-1) R / 12 n: number of slits, R: radius of circumscribed circle In a spinneret having a slit hole 1 having a center point outside the above range, a polymer is bonded during spinning. It is not preferable because it is difficult to do so and hollow fibers with poor roundness are easily spun.

When the polymer is spun out from the slit hole 1, the discharge linear velocity of the protrusion 2 is slow and the stress that opens to the outside of the polymer is moderated because the centers of the slit holes 1 are different. Combined, the bonding by the ballast effect is performed under the spinner in a state close to a perfect circle, and a hollow fiber with a high hollow ratio, a uniform wall thickness and excellent roundness is obtained with a cross section as shown in Fig. 2. To be

In order to perform the bonding due to the polymer ballast effect in a state close to a perfect circle just below the mouthpiece, it is preferable that the size of the protrusion 2 be the maximum and the width of the slit hole 1. The position of the portion 2 is preferably such that the end of the protrusion 2 is half the width of the slit hole 1 or separated from the end of the slit hole by a distance similar to the width of the slit hole 1.

The hollow fiber formed by this joining is thinned by the spinning draft, but in the process, the excessive amount of polymer discharged from the protrusion first moves mainly to the joining portion to replenish the joining portion. To do. After that, even if more polymer than the amount replenished from the protrusion to the joint is discharged, the polymer on the inner circumference is harder to cool and solidify than the polymer on the outer circumference, so the polymer migration time becomes longer and the polymer solidifies by cooling. By the time the process is completed, the hollow fiber is subjected to stress that tends to be rounded in the direction of the center of gravity, so that a hollow fiber with a uniform wall thickness is formed throughout.

The hollowness of the hollow fiber depends on the conditions of the melt spinning, but the size of the slit hole is designed so that the hollow fiber with the hollowness of about 60% can be obtained under the standard melt spinning conditions. Thus, by adjusting the melt viscosity of the polymer and the cooling conditions of the spun yarn, it is possible to spin a hollow fiber having a high hollow ratio and excellent roundness.

[0014]

【Example】

 Next, the present invention will be specifically described with reference to examples. Example 1 Using Fig. 1 (b), nylon 6 having R = 1 mm and A = 0.2 mm and a sulfuric acid relative viscosity (dissolved in 1 g of 96% sulfuric acid 100 ml and measured at 25 ° C) of 2.6 was used. The fibers were spun at various melting temperatures, cooled with 15 ° C. cooling air, and wound at 4000 m / min to obtain 70 denier / 24 filament yarns.

Comparative Example 1 Example 1 was repeated except that the spinneret shown in FIG. 3B was used.

Comparative Example 2 The procedure of Example 1 was repeated, except that the spinneret shown in FIG. 6 was used.

Table 1 shows the results of examining the hollow ratio, the cross-sectional shape, and the number of unbonded single fibers of the hollow fibers obtained from the above Examples and Comparative Examples.

[0018]

[Table 1]

As is clear from Table 1, the yarn obtained in Example 1 was a good yarn having a high hollow ratio, a cross-sectional shape of a perfect circle, and an extremely small number of single-bonding single yarns. On the other hand, in Comparative Example 1, the obtained yarn had a substantially triangular cross-sectional shape and had a large number of unbonded single yarns. Further, the yarn obtained in Comparative Example 2 had a substantially rectangular cross-sectional shape and poor circularity.

Example 2 A 70-denier / 24-filament yarn was obtained by spinning in the same manner as in Example 1 except that the melting temperature was 260 ° C. and the cooling air temperature was variously changed.

Comparative Example 3 The procedure of Example 2 was repeated, except that the spinneret shown in FIG. 3B was used.

Comparative Example 4 The procedure of Example 2 was repeated, except that the spinneret shown in FIG. 6 was used.

Table 2 shows the results of examining the hollow ratio, the cross-sectional shape, and the number of unbonded single fibers of the hollow fibers obtained from the above Examples and Comparative Examples.

[0024]

[Table 2]

As is clear from Table 2, the yarn obtained in Example 2 was a good product having a high hollow ratio, a cross-sectional shape of a perfect circle, and an extremely small number of unbonded single yarns. On the other hand, in Comparative Example 3, the obtained yarn had a substantially triangular cross-sectional shape and had a large number of unbonded single yarns. In addition, the yarn obtained in Comparative Example 4 had a substantially rectangular cross-sectional shape and poor circularity.

[0026]

[Effect of device]

 According to the present invention, it is possible to melt-spin a hollow fiber having a high hollow ratio and a uniform wall thickness and excellent circularity, and by adjusting the melt viscosity and spinning conditions of the polymer to be spun, the hollow ratio can be improved. Can be adjusted.

[Brief description of drawings]

FIG. 1 is a view showing slit holes in a spinneret of the present invention.

FIG. 2 is a cross-sectional view of a hollow fiber obtained by melt spinning from the spinneret shown in FIG.

FIG. 3 is a view showing an example of slit holes of a conventional spinneret.

4 is a cross-sectional view of a hollow fiber obtained by melt spinning from the spinneret of FIG.

FIG. 5 is a diagram showing an example of another slit hole of a conventional spinneret.

FIG. 6 is a view showing an example of another slit hole of a conventional spinneret.

7 is a cross-sectional view of a hollow fiber obtained by melt spinning from the spinneret of FIG.

[Explanation of symbols]

 1 slit hole 2 protrusion

Claims (1)

[Scope of utility model registration request] 1. A hollow fiber spinneret having a plurality of arc-shaped slit holes, wherein each slit hole has a center of an arc different from a center of a circumscribed circle of a group of arc-shaped slit holes, and the slits are close to both ends of the slit hole. A spinneret for hollow fibers, characterized in that a protrusion is provided at a position distant from the end of the slit hole at the inner edge of the hole.