KR0162550B1 - The spinning nozzle for manufacturing hollow fiber - Google Patents

Abstract

The present invention relates to a spinneret for producing a hollow fiber having a high hollow ratio of 28% or more.

The present invention is characterized in that the outer peripheral portion of the discharge slits of the spinneret has a taper portion inclined 4 ° to 10 ° in the discharge direction from a point corresponding to 1/2 of the total length of the discharge slits.

In addition, the present invention is that the discharge slits satisfy the following conditions.

Description

Spinnerets for manufacturing hollow fibers

1 is a longitudinal sectional view of the spinneret for producing hollow fibers of the present invention.

2 is a cross-sectional view of the spinneret for producing hollow fibers of the present invention.

3 is a longitudinal sectional view of a spinneret for manufacturing a conventional hollow fiber.

* Explanation of symbols for the main parts of the drawings

a: spinneret b: discharge slit

c: thickness of discharge slit d: inner diameter of discharge slit

e: Spacing between discharge sullets f: Compression section

g: Taper portion θ: Taper angle

The present invention relates to a spinneret capable of producing a hollow fiber having a hollow ratio of 28% or more continuously in the longitudinal direction of the fiber in manufacturing the hollow fiber by using a thermoplastic polymer having excellent fiber forming ability.

As is well known, in the field of conventional polyester or polyamide fibers, researches for changing the cross-section of the fiber or incorporating additives with special functions into the fiber are very active in order to meet consumer demands for high quality and convenience of wearing. It has been going on.

In particular, by inducing the cross section of the fiber in a hollow shape and providing an air layer to the hollow, much attention has been focused on the manufacture of hollow fiber which can impart resilience and drape, as well as increasing the weight and insulation of the fiber. The characteristics of the hollow fiber are excellent because the apparent specific gravity of the fiber decreases as the ratio of the hollow part in the fiber center to the total area of the fiber (hereinafter referred to as hollow ratio) increases.

As a method of manufacturing hollow fibers by melt spinning, a method of improving the hollow ratio by adjusting the shape of the slit of the spinneret (Japanese Utility Model Publication No. Hei 2-43879) and forced air inside the fiber during the spinning process And a method of improving the hollow ratio by injecting a liquid or the like (Japanese Patent Publication No. 3-60928).

Among the above methods, the method of adjusting the shape of the slit is a method of using the detention in which the discharge slit b is connected from the compression part f of the spinneret as shown in FIG. It is a method of expanding the hollow ratio of the fiber while changing the inner diameter.

When the hollow fiber is manufactured using the above method, it is possible to produce a hollow fiber with stable radioactivity and a uniform hollow ratio. However, the hollow fiber manufactured by this method has a limitation in expanding the size of the slit due to the radioactivity. Hollow fiber is mainly 5 to 15% level of hollow fiber having a hollow rate of more than 15% has a disadvantage that is difficult to obtain.

However, considering the research report that at least 27.5% of the hollow ratio is required to have a buoyancy in water as the apparent specific gravity of the hollow fiber is less than 1, the hollow fiber having a hollow ratio of 15% is the characteristic of the hollow fiber. It is not up to expectations for improvement of phosphorus light weight and heat retention.

As described above, there is a limit to the method of improving the hollow ratio depending on the shape of the slit. As a method for overcoming its disadvantages and maximizing the hollow ratio, the air is forcedly injected into the fiber during the spinning process or liquid is applied. Although a method of increasing the hollow ratio by injecting has been proposed, the above method can be used to produce a fiber having a hollow ratio of 40% or more. It is inconvenient to maintain the extra cost and maintenance required. Also, if the tension applied to the whole fiber is not uniformly controlled during the spinning process, there is a difference in the hollow ratio of the whole fiber and in some cases the hollow is destroyed. It has a downside.

Therefore, the present inventors use the existing melt spinning apparatus without attaching a separate facility, but the hollow fiber of 28% or more is formed stably in the longitudinal direction of the fiber, so that the fabric or knitted fabric having excellent lightness, insulation, and resilience is excellent. As a result of intensive research to produce hollow fiber that can be developed, it is possible to improve the hollow ratio when melting the swelling phenomenon (hereinafter referred to as die swelling) that occurs when the molten polymer during the spinning process exits the discharge hole. With this in mind, the present invention was completed.

Hereinafter, the present invention will be described in detail.

In general, in the spinning process, the molten polymer increases its pressure as it passes through the compression section of the spinneret, which gradually decreases in volume while passing through the induction hole of the cap. do. However, the molten polymer having exited the discharge hole with a constant pressure is awelled immediately under the discharge hole having a zero state pressure when discharged into the atmosphere. This swelling phenomenon is called die swelling. Die swelling is a very important factor in the production of hollow fibers. That is, the molten polymer exiting the slit of the spinneret for hollow fiber manufacturing is inflated simultaneously in the inner and outer direction of the slit, and the degree of swelling in the inner direction is relatively small, and the gap between the slits shown in FIG. As the amount of air introduced increases, the hollow ratio may be improved.

Therefore, in the present invention, as shown in FIG. 1, the taper portion g having a constant angle extending from the portion corresponding to one half of the slit length to the discharge direction from the discharge slit b present in the outer circumferential portion is expanded. By imparting, the hollow swell can be improved by inducing the die swelling of the naturally discharged polymer during the spinning process to the outer periphery of the fiber and at the same time reducing the die swelling in the fiber inward direction.

Therefore, the detention (a) of the present invention is formed in the discharge direction from the portion corresponding to 1/2 of the total length of the slit in the outer peripheral portion of the discharge slit (b) as compared with the discharge slits for manufacturing hollow fiber The tapered portion g is formed at an angle of not less than 10 degrees. At this time, if the angle of the tapered portion (g) is less than 4 °, the die swelling of the discharge polymer cannot be sufficiently induced, and therefore, the effect of the present invention cannot be expected, and if it exceeds 10 °, it is sufficient to induce swelling. On the contrary, the function of increasing the thickness of the discharge slit b lowers the forming ability of the fibers.

At this time, the thickness (c) and spacing (e) of the slits present in the detention and the inner diameter (d) of the slit also act as a very important factor in improving the hollow ratio. When satisfying the content of the hollow fiber was confirmed to obtain a hollow fiber of 28% or more.

In other words, the thickness (c) of the used discharge slits (b) is preferably 0.06 mm or more and 0.5 mm or less. If the thickness of the slits exceeds 0.5 mm, the pressure in the discharge hole is low, and thus the fiber forming ability is low. If it is lowered and less than 0.06 mm, it is difficult to manufacture precise molds because the limit of the precision processing range is exceeded during the manufacturing of the molds.

In addition, the inner diameter (d) of the slit is suitably 0.8mm or more and 1.5mm or less, and if the inner diameter of the slit is less than 0.8mm, the hollow ratio of the manufactured hollow fiber is lowered and insufficient to achieve the object of the present invention, 1.5mm If it exceeds, the hollow tends to be broken. In addition, in the spinning process for manufacturing hollow fibers, the air present in the fiber is mainly introduced through the spacing (e) of the slits in the detention, the spacing (e) of the slits in the present invention is 0.05mm or more and 0.4mm The following is suitable. If the slit spacing e is less than 0.05 mm, the spacing is very close compared to the die swelling at the distal end of the slit during the spinning process. Not only does it cause a problem of having a shape or a very low hollow ratio, but also has a disadvantage in that it is difficult to maintain or maintain the detention due to wear of the detention, and when the slit interval exceeds 0.4 mm, the polymer discharged from each slit Since the mutual adhesion is poor, the phenomenon that the hollow is broken occurs.

In the present invention, the number n of slits is preferably 3 or more and 4 or less. In case of less than 3, the hollow fiber of manufactured fiber could not be improved because there is little inflow of external air which is important for the formation of hollow during spinning process. If the number of slits is 5 or more, the hollow ratio is improved compared to 4 On the other hand, the manufacturing cost of detention increases.

When the hollow fiber was manufactured using the spinneret satisfying the above conditions, the hollow fiber having a hollow ratio of 28% or more could be reproducibly produced.

[Examples and Comparative Examples]

A hollow fiber of 50 denier / 24 filaments was prepared by spinning a polyester resin having an intrinsic viscosity of 0.64 at a spinning temperature of 295 ° C. In this case, the tapered portion of the discharge slit, the thickness c of the discharge slit, the inner diameter d of the slit, and the slit spacing e and the number n of the slit, respectively, were used. Shown in

[Assessment Methods]

1. Spinning workability: Comparative evaluation was made through the trimming rate and the visual inspection of the yarn.

2. Cross section forming ability: excellent when no hollow is broken through cross-sectional observation of drawn yarn manufactured using a microscope, good when the hollow is broken within 1 ~ 2, good within 3 ~ 4, usually 5 or more It evaluated as bad.

3. Hollow Ratio: The cross-sectional area occupied by the hollow part of the total cross-sectional area based on the cross-sectional area of the manufactured yarn is shown by the following equation.

Claims (2)

A spinneret for manufacturing hollow fibers, characterized in that a tapered portion (g) is formed at the outer periphery of the discharge slit (b) extending from an angle of 4 ° to 10 ° in the discharge direction from the half length of the discharge slit. Spinnerets for producing hollow fibers. The spinneret for producing hollow fibers according to claim 1, wherein the discharge slit (b) satisfies all of the following conditions.