JPS61289110A - Spinneret for hollow fiber - Google Patents

Abstract

PURPOSE:To provide the titled spinneret having a plurality of specific arc slits directing the concave side toward the center of the nozzle and capable of surely bonding the polymer streams extruded through the slits and keeping the strength of the spinneret by the bridges between the slits. CONSTITUTION:The objective nozzle is composed of 2-6 arch slits satisfying the following relationships: 3<L/W<8, 4<R/W<10 and 0.07<A<0.15 [L is depth of the slit (mm); W is width of the slit (m); R is radius of inscribed circle of the slits (mm); A is gap between the slits (mm)]. A hollow fiber having an essentially annular cross-section and a filament fineness of 1-10d can be produced by the use of this spinneret.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a die for thermoplastic synthetic fiber hollow fibers. More specifically, the present invention relates to a die capable of stably producing hollow fibers of thermoplastic synthetic fibers having a large hollowness ratio, a substantially annular cross section, and a single fiber denier of 1 to 10 d.

[Prior art and its problems]

Conventionally, the shape of the spindle for spinning hollow fibers is as follows:
It has been known that a plurality of arcuate slits are arranged on the same circumference. In such a die, the poly 1 discharged from each slit adheres to each other immediately after sucking air between the slits to obtain a hollow fiber.

When attempting to stably spin hollow fibers using such a conventional spinneret, it was necessary to make the interval between each slit as narrow as possible in order to ensure that the polymer discharged from each slit adhered to each other. However, if the spacing between the slits is narrowed, the central part of the spinneret surrounded by each slit, the island between the slits, will be supported by the space between the slits, which will not be able to withstand the pressure of the polymer during spinning, resulting in frequent breakage of the spinneret. In addition, there was a drawback that air could not smoothly flow in from the spaced portions, making it difficult to obtain fibers with a large hollowness ratio. On the other hand, if the distance between each slit is increased to solve these drawbacks, it becomes difficult for the polymer flow discharged from each slit to adhere, resulting in the so-called puncture phenomenon (incomplete adhesion or no adhesion at all). It has been difficult to stably spin hollow fibers because of this.

As a method for improving this drawback, Japanese Patent Application Laid-open No. 57 (1982) discloses that it is effective to provide a protrusion at the center of the outside of each slit, as shown in FIG.
This is proposed in Publication No.-2151Q.

However, in the conventional technique shown in Fig. 5, it is extremely difficult to provide a protrusion with high precision at the center of the outside of each slit in terms of die machining accuracy, and the disadvantage is that it increases the variation in die machining accuracy. there were. If spinning is performed using a spindle with large variations in spindle machining accuracy, variations in the hollowness ratio and single yarn denier of the resulting hollow fibers will increase, resulting in a decrease in quality, as well as an increase in the thread breakage rate and a decline in operational performance. do. On the other hand, if the machining accuracy of the die is improved, the yield of the die product will be significantly reduced, and the unit price of the die will become extremely expensive.

[Purpose of the invention]

The purpose of the present invention is to improve the drawbacks of the prior art, to ensure that the polymer discharged from each slit can be bonded securely, to maintain sufficient strength of the cap due to the spacing between the slits,
The present invention relates to a spindle that can be manufactured with relative ease with high precision and that can stably spin hollow fibers having a substantially annular cross section with a single filament fineness of 1 to 10 d.

[Structure of the invention]

The object of the present invention described above is to provide a hollow fiber mouthpiece in which the mouthpiece hole is composed of two or more and six or less arc-shaped slits each having a concave portion toward the center of the mouthpiece hole. The relationship between the inscribed circles is as follows +11
, +21 and formula (3) at the same time.

! l<L/W<8 ・・・・・・・・・・・・・・・
・・・・・・・・・・・・・・・・・・・・・・・・
...(1) 4 (R/W < 10 ...
・・・・・・・・・・・・・・・・・・・・・・・・
・・・・・・・・・・・・・・・ (2) 0.07<A<
0.15 ・・・・・・・・・・・・・・・・・・
・・・・・・・・・・・・・・・・・・・・・ (31 However: L is the depth of the slit (2) W is the width of the slit (1g1) R is the width formed by each slit Radius of tangent circle (I
EII) A is the distance between each slit (wl) or less,
The present invention will be described in detail.

- Figures 1 and 2 are plan views showing examples of the shape of the mouthpiece hole of the present invention. Figure 1 shows the shape of the mouthpiece hole, which is composed of three arcuate slits, and Figure 2 shows the shape of the mouthpiece hole, which is composed of four arcuate slits. It is preferable that it is a congruent form.

In FIG. 1, A is the interval between each slit, R is the radius of the inscribed circle formed by each slit, and W is the width of each slit.

FIG. 3 is a longitudinal sectional view taken along line XX in FIG. 2, showing the depth L of the slit.

The relationship expressed by equation (1) in the present invention is the relationship between the depth L of each slit and the width W of each slit. L/W is an index that represents the magnitude of pressure loss during spinning, and if r and /W are small, the balance is low.
:9,,! (□11 Eh, o. A, -waka8 □□yo.
1) increases, and the adhesion of the amount of polymer discharged from each slit becomes easier, but on the other hand,
l↑ The dispersion of the discharge amount between the discharge holes will increase.
i, it becomes impossible to obtain uniform hollow fibers, and on the other hand,
(If L/W is large, the variation in the discharge amount between the discharge holes will be reduced, and hollow fibers with less variation in single fiber fineness can be obtained, but on the other hand, the balance effect will be reduced.
Poor adhesion of polymer discharged from each slit
1 (hollow fiber banking phenomenon) begins to occur.
;”, and even more so due to the increase in pressure loss during spinning.
] 11. Since total damage will increase, use high quality hollow fibers!・[: For stable spinning, L/W should be 3 to 8 or even more.
1), it should preferably be in the range of 4 to 7.
The relationship expressed by equation (2) in the present invention indicates the relationship between the width W of each slit and the radius R of the inscribed circle formed by each slit. R/W is an index that determines the hollowness ratio of the hollow fiber obtained. When R/W is small, the adhesiveness of the polymer discharged from each slit is good, and hollow fibers with little variation in single fiber fineness are produced. Although it is possible to stably spin the fibers, on the other hand, the hollowness ratio decreases, making it impossible to obtain a hollow fiber with a sufficient hollowness ratio.
If the R/W is large, hollow fibers with a high hollowness ratio can be obtained, but on the other hand, the number of deformed hollow fibers due to poor adhesion of the polymer discharged from each slit increases, so the R/W should be 4 to 4.
It should be in the range 10, more preferably in the range 5-9.

The relationship expressed by equation (3) in the present invention indicates the desired spacing between each slit in order to achieve the object of the present invention. If the distance A between each slit is small, the adhesion of the polymer discharged from each slit will be good, but on the other hand, the amount of air flowing into the discharged polymer stream through the distance A between each slit will be good. This decreases the hollowness ratio of the hollow fiber obtained, and furthermore, since the pressure of the polymer during spinning is supported by the distance A between each slit, damage to the spinneret hole increases, and on the other hand, As the distance A between each slit increases, the hollowness ratio of the hollow fiber obtained increases and damage to the die hole is eliminated, but on the other hand, poor adhesion of the polyester W discharged from each slit is likely to occur, resulting in puncture of the hollow fiber. In order for this phenomenon to occur, the interval A between each slit must be in the range of 0.07 to 0.15101, and O
, Oa to 0.12 is more desirable.

Although the cap of the present invention can be widely applied to thermoplastic synthetic fibers,
It is particularly effective when obtaining hollow fibers by melt spinning polyester, nylon, or polypropylene.

〔Effect of the invention〕

The present invention satisfies the above formulas (11, +21, and (3) at the same time, thereby ensuring the strength of the base, and making it possible to use hollow thermoplastic synthetic fibers with a substantially round cross section and a single yarn denier of 1 to 10 d and a high hollowness ratio. Yarn can be produced stably.

Here, the present invention will be further specifically explained with reference to Examples.

Example 1 A cap consisting of three concentric arc-shaped slits as shown in Fig. 1, the depth of the slit L1 the width of the slit W1 the radius of the inscribed circle formed by each slit R1 the distance between each slit A Polyester chips with an intrinsic viscosity of 0.65 (measured in orthochlorophenol at 25°C) were spun at a spinning temperature of 288°C, at a spinning speed of 1500 m/min, and with cooling air, using a spinneret with 24 holes with various modifications. The yarn was spun at a wind speed of 35 m/min and a discharge rate of 451 mm/min, and was drawn 5.0 times by a conventional method to obtain a drawn yarn of 100 denier 24 filaments, and a hollow fiber having the cross section shown in Fig. 4 was obtained. Ta. The results are shown in Table 1.

In Table 1, experiments A I, 5, 6, 9, 1
Examples 0 and 13 are comparative examples for clarifying the effects of the present invention.

In addition, the definition of hollowness ratio in Examples is as follows. (See Figure 4) However: 81 is the cross-sectional area of the hollow fiber S2 is the area of the hollow part of the cross-section of the hollow fiber Experiments A1 to A5 are those that confirmed the effect of the spacing A between each slit, and 42.3 and 4 was good, but in AI, the interval A between each slit was too narrow, so the air flow into the hollow part was insufficient, and a sufficient hollowness ratio could not be obtained, and furthermore, it did not work for a long time. Three discharge holes were damaged after use. On the other hand, in A5, since the interval A was too wide, the hollowness ratio increased, but punctures occurred sporadically due to poor adhesion of the polymer discharged from each slit.

In experiments A 6 , 7 , 8 and 9, the depth L of each slit was
The effect of the relative relationship between the width and the width W (L/W) was confirmed, and while Ya 7 and 8 were good, Ya 6 had a small L/W, so the spinning pressure decreased. As a result, single fiber denier abnormalities of hollow fibers occurred frequently. On the other hand, in Ya9, since the L/W was large, the spinning pressure increased and the balancing effect decreased, so that two single yarns were punctured.

Experiments A I 0 , 11 , 12 and 13 were conducted using the radius R of the inscribed circle formed by each slit and the width W of the slit.
This confirms the effect of the relative relationship (R/W) of
While the flats 11 and 12 were good, the R/W of the grave 10 was small, so a sufficient hollowness ratio could not be obtained.

On the other hand, since flat 13 has a large R/W, there are many yarns with abnormal cross-sectional areas due to poor adhesion.

[Brief explanation of the drawing]

1 and 2 are plan views illustrating the shape of the cap hole of the present invention, FIG. 3 is a vertical cross-sectional view taken along the line X-X in FIG. 2, and FIG. 4 is a hollow hole obtained using the cap of the present invention. It is a cross-sectional view showing an example of thread. FIG. 5 is a plan view showing an example of a conventional mouth hole shape. A: Distance between each slit W Width of the slit R: Radius of the inscribed circle formed by each slit

Claims (1)

[Scope of Claims] The relationship between the inscribed circle in which the cap hole is composed of two or more and six or less arcuate slits having a concave portion toward the center of the cap hole is as follows (2), (2), and ( 3) A hollow fiber spinneret characterized by simultaneously satisfying the following formulas. 3<L/W<8・・・・・・・・・・・・・・・・・・
・・・・・・・・・・・・・・・・・・・・・(1) 4＜R/W＜10・・・・・・・・・・・・・・・・・・
・・・・・・・・・・・・・・・・・・・・・・・・(2) 0.07＜A＜0.15・・・・・・・・・・・・・・・
・・・・・・・・・・・・・・・・・・・・・・・・(3) However: L is the depth of the slit (mm) W is the width of the slit (mm) R is the width of each slit radius of the inscribed circle (mm
) A is the distance between each slit (mm)