JPH05230709A - Spinneret for hollow product - Google Patents

Abstract

PURPOSE:To provide a spinneret suitable for producing hollow products such as heavy denier hollow yarns of high centricity, tubes, or hollow pellets using a high-viscosity resin such as vinylidene chloride or vinyl chloride resin. CONSTITUTION:The objective spinneret is so designed that the central part thereof is supported by plural supporting arms, and a resin stock liquor divided by the supporting arms is refused outside the spinneret using one supporting arm along, while the resin stock is refused inside the spinneret for the other supporting arms.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improved die for hollow products such as hollow fibers, tubes and hollow pellets having a large denier and a high hollow ratio.

[0002]

2. Description of the Related Art As a die for producing hollow synthetic fibers,
There is known a die having a circular slit shape as shown in FIG. 2 in which a resin inlet and a resin outlet have the same shape of a spinning hole. Such a base is also described in JP-A-58-169507. The undiluted resin solution spun out from the missing circular slit a in FIG. 2 is divided by the support arm c and progresses into a cylindrical shape having cracks, but the cracks approach and re-melt at an early stage after spinning, It becomes cylindrical, stretched, stretched and wound into a hollow product. When a hollow product is manufactured using a circular slit slit-shaped die, the air that fills the hollow portion of the hollow product flows from the cracks divided by the support arm c. Further, there is also known a die having a divided arc-shaped slit as shown in FIG. 3 in which the inlet and outlet of the resin stock solution have the same shaped outlet. A die having a divided arc-shaped slit as shown in FIG.
It is described in Japanese Patent No. 5078. Since the base of FIG. 3 has two or more supporting arms, the strength of the base with respect to the internal pressure of the resin stock solution should be made larger than that of the truncated slit-shaped base having one supporting arm of FIG. Because of this, large hollow products can be made. The undiluted resin solution spun from the die of FIG. 3 becomes a cylindrical shape having four cracks divided by the support arm f, and the four cracks approach each other and are re-fused to form a cylindrical shape. Become.

[0003]

However, when a hollow product is manufactured by using the die having the circular slit shape shown in FIG. 2 or the divided arc shape shown in FIG. 3, there are the following problems. That is, for vinylidene chloride-based or vinyl chloride-based fibers, thick denier, that is, 30 to 100
Although there are many yarns of about 00 denier, when making hollow products such as hollow fibers, tubes, and hollow pellets having a large hollow ratio of such thick denier, these resins are likely to be thermally decomposed at high temperature, and therefore the spinneret It is easily contaminated with decomposed products, and it was necessary to wash the die in a short time at high temperature. Therefore, it is necessary to keep the temperature of the die as low as possible, but when the temperature of the die is set to a low temperature, the viscosity of the molten resin becomes high, the pressure loss of the die becomes large, and a large pressure is applied to the die. Became.

In order to increase the hollow ratio, it is necessary to narrow the width of the open circular slit a and increase the area of the central portion b in the open circular slit type die as shown in FIG. As the width of the slit is narrowed and the area of the central portion is increased, the pressure applied to the mouthpiece is increased, the force applied to the central portion is increased, and the load on the support arm c is increased.

As another problem, the higher the viscosity of the resin, the less likely it is that the divided spun product will be re-fused, and the width of the support arm c must be reduced. But,
The smaller the width of the supporting arm, the lower the strength of the supporting arm. Due to the various causes described above, the die having the slit slit shape shown in FIG. 2 is easily deformed or damaged. On the other hand,
Attempts to make a stable hollow product using the split arc-shaped die shown in FIG. 3 have not been successful. That is, with this type of die, even if the width of the support arm f is narrowed, re-fusion of cracks after spinning is unlikely to occur, resulting in a divided odd-shaped product, and a hollow product cannot be obtained. The reason for this is not clear, but a cylindrical resin that is divided by multiple support arms and has two or more cracks seems to cause deformation in a direction in which the cracks do not easily contact each other. When the resin has a large viscosity and a small die swell, it seems that fusion is difficult.

By solving the above-mentioned problems of the prior art and by melt spinning using a high-viscosity resin material such as vinylidene chloride-based or vinyl chloride-based resin, which is required to keep the temperature of the die low, It is an object of the present invention to provide a die for hollow products, which can obtain hollow products such as hollow fibers, tubes, and hollow pellets having a large hollow ratio of thick denier without causing deformation or damage of the die.

[0007]

The present invention has a spinning hole having a structure in which a central portion surrounded by a slit serving as a discharge port of a resin stock solution is supported by a plurality of supporting arms supported by an outer wall of the slit. In the die, the die for hollow products is characterized in that not only one supporting arm but all the other supporting arms are provided with cutout portions on the outlet side.

A die which can be used for the purpose of the present invention is illustrated in FIG. 1 and will be described in more detail with reference to FIG. The spinneret of the present invention is a thick denier hollow fiber having a large hollow ratio by melt-spinning a material such as vinylidene chloride-based or vinyl chloride-based, which is likely to undergo thermal decomposition at high temperatures, and the temperature of the spinneret needs to be kept low. It is particularly suitable for making hollow products such as tubes, hollow pellets, and the like, and can be applied when other high-viscosity materials are used or high-viscosity melt spinning is used. In the case of vinylidene chloride-based or vinyl chloride-based material, it is desirable to use an acid resistant material for the die.

FIG. 1- (1) exemplifies the shape of the outlet (outlet surface) of one spinning hole machined into the metal plate of the present invention. Normally, a large number of spinning holes are formed on the metal plate. Is provided to spin a large number of hollow products at the same time. FIG. 1- (2) shows the shape (inlet surface) of the inlet of the spinning hole of the present invention,
One support arm i, three support arms m having a cutout on the outlet side, and four arc-shaped slits j divided by a total of four support arms are shown. Although the slit j has a simple arc shape here, it is also possible to use a deformed slit having various protrusions if desired.

The total number of support arms i and m is four here, but the number of m is 1 or more and any number can be arbitrarily used. Therefore, the total number of i and m is 2 or more. I can decide. By increasing the number of the support arms m having the cutout portions, it is possible to obtain a mouthpiece that does not deform or break and can withstand high pressure. FIG. 1- (3) is a side view of the spinning hole in FIG. 1- (2) viewed from the xy plane, and the upper surface is the inlet and the lower surface is the outlet. In this figure, the support arm p in which the support arm i in FIG. 1- (2) is viewed from the side and the support arm q in which the support arm m having a notch on the outlet side in FIG. 1- (2) is viewed from the side can be seen. There is.

The most important point of the present invention is that only one support arm p
The support arm other than the above, that is, the support arm q, limits the length in the streamline direction so as not to reach the outflow surface n, and forms a slit s, that is, a notch portion between the end r of the support arm q and the outflow surface n. It is to be provided. By doing so, even if the resin stock solution is once divided by the support arm q on the inlet side, it is surely spread inside the mouthpiece by the slit s, that is, the notch, provided on the outlet side of the support arm q. The undiluted liquids are re-fused to reach the outflow surface n. FIG. 1- (1) shows the shape of the outlet, but at the outlet, it is only a slit with a broken circle divided by a single support arm i. Incidentally, the support arm i of FIG. 1- (1) is the same support arm i of FIG. 1- (2) and the support arm p of FIG. 1- (3).

The slit g shown in FIG. 1- (1) shows a simple oval shape, but if desired, it may have a different shape having various protrusions on the outside and inside, or a portion close to the support arm i. It is also possible that the slit has an enlarged shape at both ends thereof. The flow of the resin undiluted solution spun out from the outflow port becomes a cylindrical portion having a split portion i of the slit g in FIG. 1- (1), that is, a split with the support arm i,
The cracks come into contact with each other due to die swell and drawdown, and are re-fused outside the die to form a hollow cylindrical product. In the case of a hollow fiber, it is drawn and wound into a hollow fiber, and in the case of a hollow pellet, it is cooled and cut into a hollow pellet.

If the width of the lacking portion i in FIG. 1- (1), that is, the supporting arm i is too large, re-fusion does not easily occur, but this width is shown in FIG. 2 in which only one supporting arm is provided. With such a circular slit-shaped mouthpiece, it was not possible to make it too small in order to maintain the strength of the supporting arm, but with the mouthpiece of FIG. 1, since the other supporting arms share the load, it can be made smaller freely. It is possible to obtain a hollow product which is possible and completely fused. However, if the chipped portion i, that is, the width of the support arm i is too small and the spun resin flow does not have a complete split, the air filling the hollow portion of the hollow fiber cannot be supplied from the split and the hollow ratio is high. It should be noted that it may decrease.

When using a conventional base as shown in FIG. 2,
The reason why the re-fusion is difficult and the hollow fiber cannot be obtained is not completely understood, but it seems that the deformation of the spun resin is probably involved. That is, when the spinneret of the present invention is used, the spun resin deforms in a direction advantageous for re-fusion, and when the conventional spinneret as shown in FIG. 2 is used, the spun resin is re-fused. It seems that deformation is occurring in a disadvantageous direction.

[0015]

EFFECTS OF THE INVENTION According to the die of the present invention, a hollow product such as a hollow fiber or tube or hollow pellet having a large hollow ratio of thick denier can be formed by using a highly viscous resin such as vinylidene chloride or vinyl chloride. It can be manufactured without causing any damage.

[Brief description of drawings]

FIG. 1 is a view showing an example of a spinneret of a die used in the present invention. (1) shows the shape of the outlet.
(2) shows the shape of the inflow port. (3)
FIG. 3B is a view of a cut section taken along the xy plane in FIG. 1- (2) viewed from the z direction in FIG. 1- (2) to show the state of the flow path and the support arm.

FIG. 2 is a view showing the shape of a conventional circular slit slit-shaped outlet.

FIG. 3 is a view showing a shape of a conventional circular arc slit-shaped die outlet.

[Explanation of symbols]

g: Missing circular slit h: Central part (outlet surface) i: Missing part of missing slit g (support arm reaching inflow port) j: Divided arcuate slit k: Central part (inlet surface) m : Support arm having a cutout portion that does not reach the outlet xy: Plane to be cut z: Direction looking at the cut surface n: Outflow surface o: Inflow surface p: Support arm reaching the outlet q: Cut not reaching the outlet Support arm having a notch r: End of the support arm q s: Slit (notch) between the end of the support arm q and the outflow surface n a: Missing circular slit b: Center part c: Support arm d: Divided arc-shaped slit e: Central part f: Support arm

Claims (1)

[Claims] 1. A spinneret having a structure in which a central portion surrounded by a slit serving as a discharge port of a resin stock solution is supported by a plurality of supporting arms supported by an outer wall of the slit.
A hollow product mouthpiece, characterized in that a cutout portion is provided on the outlet side of all other support arms except one support arm.