JP2009030197A - Composite spinneret for hollow fiber - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a spinneret having a hollow cross-section having a relatively low hollowness and capable of keeping good spinning for a long time without causing the breakage of hollow structure. <P>SOLUTION: The composite spinneret for hollow fiber produces a multifilament composed of a conjugate single fiber group, wherein individual polymer segments containing at least two kinds of thermoplastic polymer components are alternately arranged in the circumferential direction to form a hollow circular shape as the total cross-section. A group of discharge holes for discharging the thermoplastic polymer in the form of a hollow single fiber are bored on the spinneret, each of the discharging holes is composed of a plurality of circular arc slit hole groups bored on the circumference of the same circle, the diameter of the circumscribing circle circumscribing the circular arc slit hole group is 0.4-1.0 mm, and the ratio of the slit length L to the slit width W (L/W) of the circular arc slit hole is ≥4. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a spinneret for melt spinning fibers made from thermoplastic synthetic resins such as polyester and polyamide, and more particularly to a spinneret for spinning hollow fibers having a hollow cross-sectional shape in the cross section. is there.

  In recent years, high-quality, fine and fine fabrics with excellent touch and drape properties have been put on the market, and ultrafine fibers are often used to obtain such fabrics. As a means for obtaining such ultrafine fibers, there is a method of spinning a single fiber group (filament group) having a fineness from the beginning as one method. However, there is a limit to the lower limit fineness of the ultrafine fibers obtained by this method.

  Therefore, as another method, a composite fiber composed of two polymers having different components is manufactured, and the composite fiber is divided at the bonding surface of different components, or one component is extracted and only the other component is extracted. There is a method of reducing the fineness by leaving. This method has the advantage that ultrafine fibers with a finer degree can be obtained as compared with the method described above. In addition, by producing a composite fiber with a fineness by this method and making it into a fabric, the composite fiber can be refined by the above-mentioned division and extraction, thereby streamlining the process and improving the process tone. There is an advantage.

  In addition, since polyester is excellent in mechanical characteristics, thermal stability, and the like, a composite fiber in which at least one component is composed of a polyester polymer has been conventionally used. For example, in Patent Document 1 (Japanese Patent Application Laid-Open No. 2004-270115) and the like, a composite fiber having such a polyester as its component is proposed.

  As described above, there are many techniques for dividing a composite fiber into ultrafine fibers, as proposed in, for example, Japanese Patent Application Laid-Open No. 2001-519488. For example, there is a method in which each polymer segment constituting the composite fiber is divided at the bonding surface by applying a mechanical force to the composite fiber by a method such as high-pressure water jet or beating. In addition, there is a method in which a specific component of a composite fiber formed of a plurality of polymer components is dissolved and removed with a solvent, and an ultrafine fiber is formed leaving only an undissolved component segment.

  Here, when the composite single fiber bonded with two different components is to be divided along the bonding surface only by mechanical force, the sectional shape of each component is important. The cross-sectional shape of a typical split-type composite single fiber is shown. However, in order to divide stably, it is desirable to set it as the hollow fiber which has a hollow cross-sectional shape illustrated in FIG.4 (b).

  Therefore, a spinneret for stably spinning such a hollow fiber without causing problems such as hollow cracking has been proposed in Patent Document 3 (Japanese Patent Laid-Open No. 11-152615). In such a spinneret, it is preferable to provide protruding flow passages at or near both ends of the arc-shaped slit hole group as shown in FIG. 5 in order to obtain a good hollow cross-sectional shape. Yes.

  Certainly, when spinning a hollow cross-section yarn from only one component polymer, it can be said that a good hollow fiber can be stably obtained by spinning the polymer from the discharge holes as illustrated in FIG. Although effective, in order to obtain a hollow composite fiber having a hollow cross-sectional shape as shown in FIG. 4 (b), providing projecting flow channels at both ends of the arc-shaped slit hole group or in the vicinity of both ends This will unbalance the polymer segments and is undesirable.

  In addition, such a problem appears remarkably in a spinneret in which discharge holes exceeding several thousand are arranged at a short pitch as used in a production facility for long fiber nonwoven fabrics. In order to prevent this yarn breakage, a so-called “surface cleaning operation” is performed in which foreign matter adhering to the surface of the spinneret is periodically removed using a spatula or the like. There is also a problem in that productivity is greatly reduced when it is necessary to carry out the process at short intervals.

JP 2004-270115 A Special table 2001-519488 gazette JP-A-11-152615

  The present invention has been made for the purpose of solving various problems of the prior art. That is, the object is to obtain a hollow section with a relatively low hollow ratio, to prevent the occurrence of hollow cracks, to maintain a good spinning condition for a long time, and to set the surface sweep cycle to 24 hours or more. It is to provide a spinneret that can be made.

Here, as the present invention according to claim 1 for solving the above-mentioned problem, “the polymer segments having at least two kinds of thermoplastic polymer components are alternately arranged in the circumferential direction and the entire cross section is hollow. In a composite spinneret for hollow fibers for spinning multifilaments composed of a group of composite single fibers exhibiting a circular shape,
Discharge hole groups for discharging the thermoplastic polymer as hollow single fibers are perforated, and each discharge hole is composed of a plurality of arc-shaped slit hole groups perforated on the circumference of the same circle. The diameter of the circumscribed circle circumscribing the arc-shaped slit hole group is 0.4 to 0.9 mm, and the ratio L / W of the slit width W to the slit length L of each arc-shaped slit hole is 4 or more. A featured composite spinneret for hollow fibers is provided.
Further, as in the present invention according to claim 2, "for the hollow fiber according to claim 1, wherein the sum of the outer peripheral lengths of the arc-shaped slit hole group formed in one discharge hole is 3.2 mm or less. A “composite spinneret” is provided.
Further, as in the present invention according to claim 3, “the number of slit holes forming discharge holes for spinning one single fiber is two, or claim 1 or claim 3. Item 2. A composite spinneret for hollow fibers according to Item 2.
And, as in the present invention according to claim 4, there is provided "a composite spinneret for hollow fibers according to any one of claims 1 to 3, wherein the hollow ratio of hollow fibers to be spun is 10% or less". The

  As described above, by using the composite spinneret for hollow fibers according to the present invention, the polymers discharged from the adjacent slit holes can be easily joined, and the occurrence of hollow cracks can be prevented. In addition, by using the spinneret, there is an extremely remarkable effect that a composite fiber composed of a polymer having two or more components that can be easily divided into fine fibers can be melt-spun.

  Furthermore, as another effect of using the composite spinneret for hollow fibers according to the present invention, the sum of the outer peripheral lengths of the arc-shaped slit holes formed in one discharge hole is 3.2 mm or less, Since the amount of foreign matter adhering to the polymer discharge surface can be suppressed and suppressed, and the surface cleaning cycle can be greatly extended, it is possible to maintain a good spinning condition for a long time.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 illustrates a hollow fiber composite spinneret according to the present invention. FIG. 1 (a) is a front sectional view, and FIGS. 1 (b) to 1 (e) are views of A in FIG. 1 (a). -A arrow cross section, BB arrow cross section, CC arrow cross section, and DD arrow cross section are shown, respectively. However, in FIGS. 1A to 1E, only one representative discharge hole formed in the composite spinneret for hollow fiber is taken out and described. However, in the actual spinneret, a multifilament is used. It goes without saying that a large number of discharge hole groups are formed in one hollow fiber composite spinneret for spinning the yarn.

  In the composite spinneret for hollow fibers of this example, the first base plate 1, the second base plate 2, and the third base plate 3 are incorporated into the spinneret pack in a state of being laminated in order from the bottom and are used for melt spinning. Provided. However, this example is an example in which two types of polymers (A) and (B) are used. Of course, two or more types of polymers may be used as in a known composite spinneret.

  In practice, a plurality of distribution plates are arranged on the third distribution plate 3 to provide a base for efficiently transferring a polymer having two or more components. However, in FIG. 1, the other base plates for transferring the two types of polymer (A) and polymer (B) to the third base plate 3 are items that can be easily designed. The illustration is omitted in order to avoid complicated and complicated explanation.

  Next, the manner in which the polymer flows through these base plate groups 1 to 3 will be described below. However, in the present invention, at least two types of thermoplastic polymers are used. In the following description, the case of two types of polymers (A) and polymers (B) will be described.

  In the composite spinneret for hollow fibers illustrated in FIG. 1, first, the polymer (A) and the polymer (B) flow into the third base plate 3. At this time, the polymer (A) and the polymer (B) are alternately distributed and flow into the introduction hole group 31.

  Subsequently, it flows into the 2nd nozzle | cap | die 2 and the polymer (A) and the polymer (B) merge in the merging hole 21, and a plurality of polymer segments having a fan-shaped wedge shape (16 in the figure) are alternately bonded. . As shown in FIG. 1B, the introduction hole group 31 is preferably formed in a circumferential row so that the hole centers of these hole groups are respectively located on one concentric circle C. They are alternately arranged at equal pitch intervals.

  Therefore, since each polymer (A) flow and each polymer (B) flow that flowed into the circular merge holes 21 from the distribution hole group 51 and maintained the same flow rate and pressure, the wedges are alternately fan-shaped. Circumferentially arranged with the center facing the center of the fiber cross section. In this way, the merged polymer flow continues as the merged polymer having the cross-sectional shape alternately bonded in the shape of a fan-shaped wedge flows down the polymer introduction hole 11 formed in the first base plate 1 and gradually contracts. Then, it flows into the polymer discharge hole 12 and is finally spun from the polymer discharge hole 12 as a hollow composite fiber.

  Here, it is important to arrange the introduction hole group 31 so that the same polymer (polymer (A) in this example) flows into the portion where the polymer is bonded, that is, both ends of the slit. This is because the same polymers are more likely to be joined to each other and are difficult to separate (hard to crack). As the polymer (A), a polymer that does not easily generate foreign matters such as carbide is selected.

FIG. 2 is an enlarged view of the discharge hole portion drilled in the hollow fiber composite spinneret according to the present invention, and is already illustrated in FIG.
Here, in the composite spinneret for hollow fibers of the present invention, as shown in FIG. 2, a plurality of arc-shaped slit hole groups for discharging the thermoplastic polymer are formed on the same circumference. The diameter of the circumscribed circle circumscribing the arc-shaped slit hole group is 0.4 to 1.0 mm, and the ratio L / W of the slit width W of the arc-shaped slit hole to the length L of the slit central arc is 4 or more. It is characterized by being. As illustrated in FIG. 2, the L value is a value calculated from the center width (W / 2) of the slit hole.

  In the embodiment shown in FIG. 2, each one discharge hole for spinning one hollow single fiber has a plurality of arc-shaped slit holes. The number of arc-shaped slit holes is not particularly limited, but in the present invention, it is more preferably 2 to 5 and particularly preferably 2 for the following reasons. .

  That is, since both ends of the slit hole are portions where foreign substances are easily deposited and adhered, the number of slits is preferably small, and for this reason, it is preferably 5 or less. On the other hand, when the number of slit holes is one, the slit hole has a C-shape due to design requirements. In this case, the sectional shape as shown in FIG. In order to obtain the hollow fiber having, it is difficult and unsuitable to stabilize the discharge balance of two different polymers.

  In the embodiment of the composite spinneret for hollow fibers according to the present invention illustrated in FIG. 2, it is particularly preferable that the discharge hole for discharging one hollow single fiber is composed of two arc-shaped slit holes. As already explained. The reason for this is that when a split type hollow composite yarn is assumed, it is not necessary to increase the hollow ratio in this type of hollow composite yarn (the same polymer constituting the hollow single fiber is bonded to each other at the center of the fiber). This is because it is only necessary to prevent it from being divided and becoming impossible to be divided). On the other hand, when it is not a split-type hollow composite fiber, it is necessary to increase the number of slit holes in order to increase the hollow ratio.

  Conversely, in order to spin a hollow fiber having a low hollow ratio, it is preferable that the number of slit holes is small. This is because, due to the presence of the non-perforated portion between the slit holes, the non-perforated portion is opened in the yarn immediately after discharge, and air flows into the hollow forming portion from here to affect the hollow ratio. In addition, shortening the gap | interval (distance of a non-perforated part) between adjacent slit holes acts effectively for the stable joining of the polymers after discharging from the adjacent slit hole.

  Therefore, it is preferable to shorten the gap between adjacent slit holes (the distance between the non-perforated portions). However, in the spinneret of the present invention, the distance between the slit holes is set to about 60 μm in consideration of the limitation of the processing technique. Because of this distance, the slit hole having L / W of 4 or more shown in the present invention can be drilled without difficulty, and the polymer can be stably joined without causing hollow cracks. This is because it can be realized.

  Next, in the present invention, when a circumscribed circle circumscribing the arc-shaped slit hole group of one discharge hole is considered, the diameter of the circumscribed circle (value of “D” in FIG. 2) is It is preferable that it is 0.4-1.0 mm, Most preferably, it is 0.5-0.8 mm.

  If the diameter D of the circumscribed circle is less than 0.4 mm, the processing accuracy of the arc-shaped slit hole becomes a problem, the cost of manufacturing the die increases, and the manufacturing conditions of the composite fiber become strict, so that stable manufacturing is possible. It becomes difficult. Further, when the circumscribed circle diameter D is larger than 1.0 mm, after the split hollow composite yarn is manufactured, the bonded polymer segments are divided to achieve the purpose of manufacturing a fine yarn. It becomes difficult and the spinning conditions become severe, and it is difficult to obtain a good hollow composite yarn.

  In the composite spinneret for hollow fibers according to the present invention described above, when the present inventor conducted a melt spinning experiment by changing the shape of the discharge hole of the base in various ways, surprisingly, it was drilled in one discharge hole. It was found that the sweeping period can be greatly improved by setting the total outer peripheral length of the arc-shaped slit hole group to 3.2 mm or less. Therefore, in terms of increasing the sweeping period, it is preferable to set the total outer peripheral length of the arcuate slit hole group formed in one discharge hole to be 3.2 mm or less.

  Hereinafter, the operation and effect of the present invention will be described more specifically by experimental examples performed on the composite spinneret for hollow fibers according to the present invention. In this series of experiments, the die evaluation of the present invention was carried out at the hollow crack generation rate and the face sweep cycle shown below.

(1) Hollow crack occurrence rate: Yarn spun at a predetermined speed was collected, and the ratio of occurrence of hollow cracks in the cross section of the raw yarn was investigated.
(2) Face sweeping cycle: The spinneret is subjected to continuous operation for one month, and the operator periodically checks the state of the polymer discharge surface of the nozzle, and changes occur so that the occurrence of yarn breakage is predicted. At that time, the surface is cleaned (cleaning of the polymer discharge surface of the spinneret). Then, the number of times of surface cleaning and the time interval until a new surface cleaning occurred were obtained, and the surface cleaning cycle was calculated.

  Experimental Example 1 has a base having a discharge hole of L / W = 4.1, Experimental Example 2 has a base having a discharge hole of L / W = 4.2, and Experimental Example 3 has an L / W value of Eight types of caps (shown by the symbol “●” in FIG. 3) having discharge holes of 4 or less were produced. In all of Experimental Examples 1 to 3, the same specification base plate is used except for the first base plate having the discharge holes. At that time, the d value and the D value defined in FIG. 2 were set to d = 60 μm and D = 0.5 mm, and these values were all fixed to constant values in Experimental Examples 1 to 3.

  In order to confirm the rate of occurrence of hollow cracks in the die as described above, the die of Examples 1 and 2 and the comparative example were mounted on a spinneret pack and a spinning test was performed. In this test, polyester and polyamide were melted by two melt extruders, respectively, and then each polymer was sent to a spin block (melt spinning apparatus) while continuously metering each polymer. The spin block is fitted with the composite spinneret for hollow fibers illustrated in FIG. 1, and about 0.5 g per discharge hole from a group of 3000 holes formed in the spinneret. A two-component polymer comprising / min is spun from the die. In this way, the multifilament yarn spun from the die was cooled according to the usual method of melt spinning and taken up at 3000 m / min.

  The hollow fiber occurrence rate was evaluated for the hollow fibers obtained as described above. The result is shown in FIG. As is apparent from FIG. 3, in the bases of the present invention (Experimental Example 1 and Experimental Example 2), the incidence of hollow cracks is almost 0%, whereas in the eight types of experimental bases of Experimental Example 3, L / It was confirmed that the smaller the W is, the higher the incidence of hollow cracks is, and there is a clear difference between L / W = 4.

Experimental Example 4 is a base having a discharge hole having a total outer peripheral length of 3.2 mm with two slit hole groups, and Experimental Example 5 has a total outer peripheral length of 4.1 mm. A base having a discharge hole was used. The other conditions were the same as those of the base of Experimental Example 2.
In the evaluation result of the surface cleaning cycle obtained at this time, the base of the experimental example 4 has a surface cleaning cycle of 24 to 30 hours and exceeds 24 hours, whereas the base of the experimental example 5 has 7 to 7 hours. It was confirmed that 8 hours and the sweeping period were at a level of 1/3 or less, and that the outer peripheral length of the slit was 3.2 mm or less, which was necessary for the practical sweeping period to be 24 hours or more. .

Fig. 1 illustrates a hollow fiber composite spinneret according to the present invention, in which Fig. 1 (a) is a front sectional view, and Figs. 1 (b) to 1 (e) are views taken along arrows AA in Fig. 1 (a). A cross section, a BB arrow cross section, a CC arrow cross section, and a DD arrow cross section are shown. It is the figure which expanded and illustrated the discharge hole part drilled in the composite spinneret for hollow fibers which concerns on this invention, Comprising: It is the figure illustrated in FIG.1 (b). It is an evaluation result of an Example. It is sectional drawing which illustrated the fiber cross-sectional shape of typical split type composite fiber. It is the top view which illustrated the discharge hole shape of the typical compound spinneret for hollow fibers.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 1st nozzle | cap | die 2nd 2nd nozzle | cap | die 3 3rd nozzle | cap | die 11 Polymer discharge hole 12 Introduction hole 21 of merged polymer Merge hole 31 Introduction hole of polymer (A), (B)

Claims (4)

For hollow fibers for spinning multifilaments consisting of a composite single fiber group in which each polymer segment having at least two kinds of thermoplastic polymer components is alternately arranged in the circumferential direction and the entire cross section has a hollow circle In composite spinneret,
Discharge hole groups for discharging the thermoplastic polymer as hollow single fibers are perforated, and each discharge hole is composed of a plurality of arc-shaped slit hole groups formed on the circumference of the same circle. The diameter of the circumscribed circle circumscribing the arc-shaped slit hole group is 0.4 to 1.0 mm, and the ratio L / W of the slit width W to the slit length L of each arc-shaped slit hole is 4 or more. Characteristic composite spinneret for hollow fibers.   2. The composite spinneret for hollow fibers according to claim 1, wherein the sum total of the outer peripheral lengths of the arc-shaped slit hole groups formed in one discharge hole is 3.2 mm or less.   The composite spinneret for hollow fibers according to claim 1 or 2, wherein the number of slit holes forming discharge holes for spinning one single fiber is two.   The composite spinneret for hollow fibers according to any one of claims 1 to 3, wherein the hollow ratio of the hollow fibers to be spun is 10% or less.

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