JP2003342825A - Spinneret for highly hollow yarn - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a spinneret which can stably produce a highly hollow yarn comprising 36 or more filaments. <P>SOLUTION: This spinneret is the one in which spinning nozzle (2) groups for spinning a multifilament yarn comprising hollow single filaments are formed and which simultaneously satisfies the following requirements (A) to (D). (A) Each spinning nozzle has at least a polymer-introducing hole formed on the upstream side and a discontinuous polymer flow pass formed on the downstream side. (B) In the spinning nozzle, three or more circular slit flow passes are arranged on the circumference in a row to form a wholly discontinuous circular polymer flow pass. (C) (a) and (b) have a relation: (b)≥3.1(a), wherein (a) is the diameter of a virtual inscribed circle inscribing in the peripheral edge of the circular polymer flow pass, and (b) is a distance between the centers of the mutually adjacent spinning nozzles. (D) When the spinning nozzle groups are arranged on lattice points, a distance between the lattice points has at least the relation of (C). <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a melt spinneret for melt spinning a thermoplastic synthetic fiber, and more particularly to a melt spinneret for melt spinning a hollow fiber having a high hollowness.

[0002]

2. Description of the Related Art Conventionally, when melt-spinning a hollow fiber, for example, a polymer is spun on a polymer discharge surface of a die from a discharge hole having a shape shown in FIGS. 6 (a) and 6 (b). It is being appreciated. That is, as shown in the figure, a discharge hole is used in which at least one discontinuous annular slit channel is formed on the same circumference.

However, hollow fibers obtained by spinning from a die having such discharge holes are shown in FIGS. 7 (a) to 7 (c).
As shown in Fig. 6, when the polymers immediately after spinning are bonded to each other in the discontinuous portion formed in the annular slit channel, a dent may occur at the bonding portion or the symmetry of the fiber cross section may be broken. Or, it may cause a defective joint.

Therefore, for the purpose of solving such a problem and obtaining a hollow fiber having a high hollow ratio and a good symmetry of the fiber cross section, for example, Japanese Patent Laid-Open No. Sho 58-58.
In JP-A-169507 and the like, a spinneret in which a channel end shape in a discontinuous portion of an annular slit channel is devised is proposed. According to this spinneret,
A yarn having a hollowness of about 20 to 30% can be obtained, but it is difficult to obtain a stable yarn because the fiber cross-section is distorted as shown in FIGS. 9 (a) to 9 (c).

In order to solve the above-mentioned problems, for example, Japanese Utility Model Publication No. 2-43879 proposes a spinneret having a discharge hole shape as shown in FIG. By using such a spinneret, as shown in FIGS. 4 (a) to 4 (c), it has become possible to obtain a hollow fiber having excellent symmetry and a hollow ratio of more than 30%. .

However, these spinnerets can be practically used if melt spinning of multifilaments composed of a small number of single fibers (the number of filaments) can be obtained, for example, 36 or more. In the case of melt-spinning a multifilament having a single fiber (filament), there is a problem that a stable hollow fiber cannot be obtained for a long period of time.

[0007] Also, it seems that a good hollow fiber can be obtained at first glance even with multi-filament melt-spinning having a number of filaments less than 36, but to a different degree, in reality, it is shown in Fig. 9 (a). It was found that there is an inherent problem of fiber cross-section distortion as shown in (c) to (c), and a fundamental solution has not been reached.

[0008]

DISCLOSURE OF THE INVENTION In view of the above-mentioned problems of the spinneret for hollow fibers, the present inventors have made earnest studies, and as a result, have made the present invention. However, a high hollow multifilament yarn having 36 or more filaments has excellent symmetry and 25%
An object of the present invention is to provide a spinneret capable of stably producing a hollow fiber having a high hollow ratio as described above over a long period of time.

[0009]

As a spinneret of the present invention for achieving the above object, a group of spinning holes for spinning out a multifilament yarn composed of 36 or more hollow single fibers is provided here. And a spinneret for high hollow fibers, which simultaneously satisfies the following requirements (A) to (D).

Here, the requirements (A) to (D) are as follows:
"(A) At least a polymer introduction hole in which each spinning hole is formed on the upstream side, and a discharge hole having a discontinuous annular polymer flow path formed subsequently to the introduction hole and on the downstream side thereof" (B) The discharge hole has three or more arc-shaped slit channels arranged in a line on the circumference to form a discontinuous annular polymer channel, and (C) the circle. An inscribed circle inscribed in the outer peripheral edge of the annular polymer channel is hypothesized, the diameter of the virtual inscribed circle is a (unit: mm), and the center-to-center distance between adjacent spinning holes is b (unit: mm). ), These a and b have a relationship of b ≧ 3.1a, and (D) the spinning hole groups are arranged on a square lattice point, and the distance between the square lattice points at this time is at least Having the relationship of (C) ”.

In the spinneret of the present invention, it is preferable that no discharge hole is formed at the center of the spinneret. Therefore, no spin hole is drilled in a region within a radius of 5.0 mm from the center of the spinneret. That is the preferred embodiment. Also, the condition a satisfies the condition 0.5 ≦ a ≦ 1.8, and (a−b) ≧ 3.1 with respect to the condition b.
It is also a preferable embodiment to have the relationship.

At that time, in the spinneret of the present invention, when the molten polymer is discharged from the discharge hole, the polymer discharge linear velocity is set to 5 to 12 cm / sec to obtain a hollow fiber excellent in spinning tone and quality. It is preferable above.

The spinneret of the present invention described above is particularly preferably used for obtaining a hollow fiber having a hollow ratio of 25% or more stably over a long period of time.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below.

First, to exemplify a preferable polymer as the molten polymer used in the spinneret of the present invention, a polyester in which ethylene terephthalate accounts for 85 mol% or more, preferably 95 mol% or more as a repeating unit.

The polyester may be obtained by copolymerizing a small amount of a component other than the terephthalic acid component and / or the ethylene glycol component (usually 15 mol% or less with respect to the terephthalic acid component). In addition, the intrinsic viscosity of such a polyester (as known, obtained by measurement using an ortho-chlorophenol solution at 35 ° C. as a solvent) is the same as that of a polyester usually used as a cloth material for clothing. Intrinsic viscosity of 0.45
0.70 is preferable. Further, these polyesters may contain known additives such as pigments, dyes, matting agents, antifouling agents, optical brighteners, flame retardants, stabilizers, UV absorbers and lubricants.

The spinneret for high hollow fibers according to the present invention for performing melt spinning using the above-mentioned polymers will be described in detail below with reference to the drawings.

FIG. 1 is an explanatory view schematically showing a spinning hole formed in a spinneret for a high hollow fiber used in the present invention, and FIG. 1 (a) is a spinning hole in which an essential part is enlarged. And a schematic plan view of the spinning hole seen from the polymer discharge surface side.

In FIG. 1, reference numeral 1 indicates a spinneret, and reference numeral 2 indicates a spinning hole. Here, as shown in the drawing, the spinning hole 1 has a polymer introduction hole 2a formed on the upstream side into which the polymer flows, and the introduction hole 2a is formed.
And a discharge hole 2b having a discontinuous ring-shaped polymer flow path that is bored downstream thereof. At this time, the discharge holes 2b are formed by arranging three or more arc-shaped slit channels (four in this example) in a line on the circumference, and forming a discontinuous portion at the end of the arc-shaped slit channels. , Forming an annular polymer channel that is discontinuous as a whole.

Therefore, the term "discontinuous toroidal polymer channel" used in the present invention means that a discontinuous portion is formed at the end of such an arcuate slit channel, and the polymer discharge surface is simply connected. The term "separated flow path" that is not performed. In the present invention, a virtual inscribed circle (indicated by a dotted line in the figure) inscribed in the outer peripheral edge of the annular polymer channel is further considered, and the diameter of the virtual inscribed circle is a
(Unit: mm). Further, at both ends of the discontinuous portion of the annular polymer channel, a projecting channel is formed on the inner peripheral edge side toward the center of the spinning hole 2, and by forming such projecting channel. The bonding of the polymers discharged from the discharge holes 2b is made good, the defective bonding and the hollow cracks at the bonded portions are prevented, and the bondability between the polymers is improved.

Next, in the spinneret 1 of the present invention, the spinning hole 2
It is a necessary condition that at least 36 holes be drilled,
At that time, when the center-to-center distance between the adjacent spinning holes 2 is b (unit: mm), these a and b are b
It is important to have a relationship of ≧ 3.1a. At this time, a is preferably 0.5 mm or more and 1.8
It is important that (mm) or less and (ab) be 3.1 mm or more.

In the spinneret 1 of the present invention, in addition to the above conditions, the arrangement of the spinning holes 2 is also an important requirement. As shown by the one-dot chain line in FIG. 2, the spinning holes are formed on the square lattice points. It is important to arrange 2 pieces. By arranging the spinning holes 2 in this way, in the cooling process of the multifilament after spinning, there are no filaments that obstruct the distribution of the filaments other than the square lattice points, so that the cooling air is spun into a square lattice shape. It is possible to smoothly flow while moving straight between the filament groups.

Therefore, even if the spinning is performed through 36 or more spinning holes 2, that is, even if the number of filaments becomes extremely large, the cooling air can easily enter while crossing the filament group. It is possible to stably form a high hollow fiber having a good cross-sectional shape. However, when the above b is not spun without maintaining the interval of b ≧ 3.1a, or when the spinning hole arrangement is not a square lattice arrangement, the cooling air sufficiently enters between the filament groups. Therefore, a filament that is insufficiently cooled is produced, and a filament having a non-cross-sectional shape as shown in FIGS. 7 and 9 is obtained.

In the spinneret 1 of the present invention, the spinning holes 2 are arranged in a square lattice shape including a rectangular lattice and a square lattice, but the spinning holes 2 precede the spinneret 1 with higher density. For this reason, it is preferable to use a square lattice-like arrangement because the minimum necessary length can be secured without making one side of the lattice longer than necessary.

As described above, in the spinneret of the present invention, as shown in FIG. 3 exemplifying the overall arrangement of the spinning holes, the overall arrangement of the spinning holes 2 is as shown in FIG.
The spinning hole 2 can be drilled up to the center of the spinneret. However, considering the easiness of the cooling air to enter the center of the spun filament group, as shown in FIG. (B), the spinneret 2 is formed in the center of the spinneret corresponding to the area of the circle indicated by the alternate long and short dash line. Is preferably not provided.

Next, a feature of the spinneret of the present invention is that the discharge linear velocity of the polymer discharged from three or more arc-shaped slit channels is 5 to 12 cm / sec, preferably 8 to 10 cm / sec. The range is. The discharge linear velocity of the polymer can be arbitrarily set by adjusting the total opening area of the arc-shaped slit flow channel according to the amount of polymer supplied to the spinning hole.

At that time, the discharge linear velocity of the polymer is 5 cm /
If it is set to a low speed less than sec, as the spinning time elapses,
Foreign matter grows around the edges of the discharge holes, which hinders stable polymer discharge. If this happens, hollow breakage will occur. And as time goes on,
Single fiber breakage occurs, making spinning winding difficult. Further, when the discharge linear velocity of the polymer exceeds 12 cm / sec, it is difficult to bond (join) between the melted polymers discharged from three or more arc-shaped slit channels, and it becomes difficult to form a hollow.

[0028]

EXAMPLES The present invention will be described in more detail below with reference to examples. Each evaluation item in the examples was measured by the following method.

(1) Variation in hollowness (%) and hollowness A cross-sectional photograph (560 times) of the polyester multifilament taken up by spinning was taken, and the hollow portion of each single yarn cross-section was removed except for the cross-section where hollow breakage was observed. The area (A) and the area (B) surrounding the cross section were measured, and "hollow ratio (%) = A / B × 1"
"00" was calculated, and the average value of all measured values was defined as the hollow ratio (%). Further, the variation rate of the measured value (standard deviation / average value × 100) was defined as the variation of hollow rate.

(2) Hollow breakage occurrence rate (%) In the cross-section photograph obtained in (1) above, the number of single yarn cross-sections with hollow breakage was counted, and the ratio (%) to the total single yarn cross section was defined as the hollow breakage occurrence rate. did.

(3) Spinning Breakage Rate (%) The number of times of thread breakage generated at the end of each package of the specified weight is recorded, excluding the thread breakage caused by artificial or mechanical factors, and the "spinning breakage rate" is recorded. (%) = Number of yarn breaks / number of spinning spindles ×
The spinning breakage rate was calculated by the formula "100".

[Examples 1 and 2, Comparative Examples 1 and 2] A spinneret having 48 spinning holes having the same shape as that shown in FIG. 1 was applied to the spinning step shown in FIG. In FIG. 5, 1 is a spinneret of the present invention, 3 is a cooling air shielding member, 4 is a cross-flow type spinning cylinder, 5 is a guide type oil supply device, 6 is a confounding imparting device, and 7a and 7b are first. And the second
The words dead row, 8 indicate hollow fiber packages wound by a winder, respectively.

In the spinning process described above, polyethylene terephthalate having an intrinsic viscosity of 0.64 was dried at 160 ° C., and then melted in a conventional melt spinning facility equipped with a screw type extruder according to a conventional method, as shown in FIG. Using a spinneret 1 in which 48 spinning holes having the same shape as those described above are formed,
Spinning temperature 290 ° C, discharge rate 25g / min, discharge linear velocity 8
It was discharged at cm / sec. At this time, the arrangement of the spinning holes 2 was as shown in Table 1.

The discharged polymer is cooled and solidified by blowing cooling air of 25 ° C. across the spun filament group from the cross-flow type spinning cylinder 3 to solidify by cooling, and 70 cm below the polymer discharge surface of the spinneret 1. After applying the oil agent while concentrating the traveling yarns with the installed guide type oil supply device, the spinning tension is set to 0.15 cN / dtex while the multifilaments are entangled by the entanglement application device 6. It was taken up through a godet roller at a speed of 3000 m / min and wound as a 10 kg polyester multifilament package. At this time, the total fineness of the obtained hollow fiber was 84 dtex, and the number of filaments was 48.

At this time, in Examples 1 and 2 in which the relation between the diameter a (mm) of the virtual inscribed circle and the interval b (mm) of the square lattice was b ≧ 3.1a, as is clear from Table 1. Good results were also obtained for variations in hollow ratio.

In Comparative Examples 1 and 2, it was not possible to produce a stable polyester multifilament having a high hollow ratio because the hollow ratio varied and the hollow breakage ratio with time was high.

[0037]

[Table 1]

[Examples 3 to 4 and Comparative Examples 3 to 4] Example 1 except that the discharge linear velocities of the polymers were set as shown in Table 2.
The spinning operation was performed under the same method and conditions.

As is clear from Table 2, the discharge linear velocity is 1
In Comparative Example 4 exceeding 2 cm / sec, there were many bonding failures between the molten polymers discharged from the plurality of slits, and the hollow breakage rate was extremely high from the start of spinning.

The above operation was continuously performed for 32 spinning spindles for 7 days, and the hollow breakage rate and the spinning breakage rate were observed. As is clear from Table 2, the discharge linear velocity is 5 to 12c.
In Examples 3 to 4 in the range of m / sec, the polyester multifilament having a high hollow ratio could be stably produced over 4 days. On the other hand, in Comparative Example 4 in which the discharge linear velocity is less than 5 cm / sec, the growth of foreign matter was observed around the slits with the elapse of the spinning time, the hollow breakage rate increased, and the spinning breakage occurred after the third spinning day. It happened a lot.

[0041]

[Table 2]

[0042]

EFFECTS OF THE INVENTION According to the present invention, a highly hollow multifilament yarn having 36 or more filaments can be stably used for a long period of time with a hollow fiber having excellent symmetry and a high hollowness of 25% or more. It is possible to provide a spinneret which can be manufactured by the following method.

[Brief description of drawings]

FIG. 1 is an explanatory view schematically illustrating a spinning hole formed in a spinneret for high hollow fibers according to the present invention, and FIG. 1 (a) is a schematic front sectional view of a spinning hole in which an essential part is enlarged. (B) is a schematic plan view of the spinning hole as seen from the polymer discharge surface side.

FIG. 2 is a schematic explanatory view for explaining the arrangement of spinning holes formed in the spinneret of the present invention.

FIG. 3 is a plan view exemplifying the overall arrangement of the spinning holes formed in the spinneret of the present invention, where (a) shows the case where the spinning holes are drilled to the center of the spinneret, and (b) shows the center part of the spinneret. In each case, no spinning hole is formed.

FIG. 4 is a cross-sectional view of a hollow fiber obtained by the spinneret of the present invention.

FIG. 5 is a process drawing that illustrates a schematic spinning process in which the spinneret of the present invention is applied.

FIG. 6 is a plan view showing a conventional discharge hole.

FIG. 7 is a cross-sectional view of a hollow fiber obtained by the conventional discharge hole illustrated in FIG.

FIG. 8 is a plan view showing another conventional discharge hole.

9 is a cross-sectional view of the hollow fiber obtained in the discharge hole of FIG.

[Explanation of symbols]

2: Discharge hole a: Diameter of virtual inscribed circle b: Distance between discharge holes (distance between grid points)

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Hiroyuki Osaka             77, Kitayoshida-cho, Matsuyama-shi, Ehime Teijin Stock Association             Company Matsuyama Office F-term (reference) 4L045 AA05 BA03 BA24 CB02 CB10

Claims (5)

[Claims] 1. A spinning hole group for spinning a multifilament yarn composed of 36 or more hollow monofilaments is provided.
A spinneret for a high hollow fiber that simultaneously satisfies the following requirements (A) to (D). (A) At least a polymer introducing hole in which each of the spinning holes is formed on the upstream side, and a discharge hole having a discontinuous annular polymer flow channel formed on the downstream side of the introducing hole and subsequently formed (B) In the discharge hole, three or more arc-shaped slit channels are arranged in a line on the circumference to form a discontinuous annular polymer channel, and (C) the annular shape. An inscribed circle inscribed in the outer peripheral edge of the polymer channel is assumed to be virtual, the diameter of this virtual inscribed circle is set to a (unit: mm), and the center-to-center distance between the spinning holes adjacent to each other is set to b (unit: mm). In this case, a and b have a relationship of b ≧ 3.1a, and (D) the spinning hole groups are arranged on lattice points, and the distance between lattice points at this time is at least (C).
Have a relationship with. 2. The spinneret for high hollow fibers according to claim 1, wherein no spinning hole is formed in a region within a radius of 5.0 mm from the center of the spinneret. 3. A satisfies the condition of 0.5 ≦ a ≦ 1.8, and (a−b) between b and
The spinneret for a high hollow fiber according to claim 1 or 2, which has a relationship of ≧ 3.1. 4. When the molten polymer is discharged from the discharge hole, the discharge linear velocity of the polymer is 5 to 12 cm / sec.
The spinneret for high hollow fibers according to any one of claims 1 to 3. 5. The hollow ratio is 25% or more, 1 to 4.
The spinneret for a high hollow fiber according to any one of 1.