JP2842243B2 - Melt spinning equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a melt spinning apparatus suitable for ultrafine fibers, and more particularly to a melt spinning apparatus capable of melt spinning high-quality ultrafine fibers with good spinning operability.

[0002]

2. Description of the Related Art Ultrafine fibers having a single-fiber fineness of 0.1 to 1.0 denier after stretching are widely used for applications such as synthetic leather, high-density woven fabric, and high-grade raised fabric. There are many methods for obtaining such ultrafine fibers by melt spinning. Among them, the simplest first method is a method of spinning with a small discharge amount per one hole of a spinneret (Japanese Patent Laid-Open No. 55
-62209). The second method uses an elution-type composite spun fiber, in which the so-called sea-island type composite fiber is eluted with a solvent to obtain only the island component as an ultrafine fiber (Japanese Patent Publication No. 48-25362). Such). A third method uses splittable conjugate fibers,
This is a method in which components composed of mutually incompatible polymers are divided into pieces by the action of a chemical solution, impact or the like to obtain ultrafine fibers (Japanese Patent Laid-Open No. Sho 51-130317).

[0003] Of these methods, the second and third methods require a plurality of components at the melt spinning stage, require a special spinneret having a complicated structure, and dissolve or split the material. Due to the necessity of a special process, there is a drawback that the production cost becomes extremely high. On the other hand, the first method has an advantage that the cost is low because a single thermoplastic polymer may be spun from a spinneret, but the discharge amount per one pore is small, so that as described below. There is a technical problem that stable spinning becomes difficult and it is very difficult to obtain high quality ultrafine fibers.

Meanwhile, the melt spinning method is a method in which a thermoplastic polymer is melted into a spinning dope, which is weighed, discharged from a spinneret, cooled, solidified, and taken off. Here, the cooling is to suppress unevenness in the thickness of the yarn in the longitudinal direction, thereby reducing unevenness in physical properties of the fiber. For such cooling, it is necessary to actively send cooling air so that the melted or semi-molten yarn discharged from the pores does not fuse or break due to yarn sway. It is.

[0005] In the case where the discharge amount per pore is extremely small as in the case of melt spinning of ultrafine fibers, the discharge yarn is cooled near the spinneret and solidified due to its small heat capacity. Unless the spraying position is set close to the spinneret, it becomes difficult to reduce the unevenness of the thickness, and frequent fusion or breakage of the yarn occurs. However, simply
Attempting to enhance cooling by sending cooling air directly below the spinneret causes the temperature of the spinneret to drop, so the thermoplastic polymer, which was kept at a constant high temperature just above the spinneret, The liquid is rapidly cooled and discharged. For this reason, the thinning of the discharged yarn becomes unstable and spinning becomes difficult.

In order to avoid this, the temperature of the thermoplastic polymer reaching the spinneret portion is raised to a temperature inappropriate for spinning in advance, but this causes quality degradation due to thermal decomposition of the thermoplastic polymer. Would.

For this reason, there have been proposed several methods for locally increasing the temperature around the spinneret. For example, Japanese Utility Model Publication No. 47-34247 discloses a double-cylinder gap-shaped passage provided between a filtration unit of a spinneret pack and a spinneret, and the passage is heated by a heat medium. However, in this technique, since the flow velocity differs according to the distance from the pipe wall of the double circular pipe, it is supplied to a spinneret having a greatly different heat history. For this reason, the melt viscosity of the spinning dope varies, causing a variation in the discharge amount between the discharge holes. In addition, some of the spinning dope undergoes severe thermal decomposition, thereby causing a "bending" phenomenon and yarn breakage of the spinning dope at the exit of the pore.

Japanese Patent Publication No. 46-37777 discloses that a heater is provided on the outer periphery of a spinneret pack in order to obtain a high-quality undrawn yarn with small fineness unevenness and no fusion, and heat from the heater is provided. The spinneret is directly heated by conduction. However, when this technology is applied to the production of microfibers, it is difficult to balance the heat by heat conduction and the heat radiation to the cooling atmosphere uniformly within the spinneret surface, and the temperature decreases at the center of the spinneret. Happens.
For this reason, this temperature difference causes a variation in the viscosity of the spinning dope immediately before ejection, causing the same problem as described above. Further, Japanese Patent Application Laid-Open No. 6-17304 proposes an ultrafine melt spinning apparatus provided with a heater, a heat retaining section, and a shutter immediately below a die pack. In this spinning apparatus, although the mottling and spinnability are improved by suppressing the turbulence in the atmosphere below the spinneret and improving the heat insulation, the effect of the heating and heat insulation on the spinneret is small, and the improvement effect is not sufficient.

[0009]

The inventors of the present invention have conducted intensive studies on a method for producing high-quality ultrafine fibers without the above-mentioned problems, and have found that the spinneret is indirectly heated through an appropriate clearance. As a result, it has been found that a high-quality ultrafine fiber which cannot be achieved by the prior art can be obtained with good spinning operability, and the present invention has been completed by further various studies.

[0010]

SUMMARY OF THE INVENTION An object of the present invention is to provide a puck heater for heating a molten thermoplastic polymer in a flow path from a heating / melting apparatus to a spinneret, and a separate and independent puck heater. A heater for heating the spinneret through a clearance of 0.5 to 5.0 mm with the spin pack, the upper surface of the heater being 0 to 10 mm above the upper surface of the spinneret, and The lower surface of the heater is 5 to 50 mm below the lower surface of the spinneret, and the uppermost blower of the blower for cooling the discharged yarn is provided below the lower surface of the spinneret within 100 mm. This is achieved by a melt spinning device.

In the present invention, the ultrafine fibers are multifilaments having a single yarn fineness of 0.1 to 1.0 denier after drawing. The drawn yarn may be drawn,
The drawn yarn may be drawn during the spinning step by a method such as taking out the discharged yarn at a high speed.

Hereinafter, the structure of the present invention will be specifically described with reference to the drawings. FIG. 1 is a sectional view showing an example of the melt spinning apparatus of the present invention. The heated and melted thermoplastic polymer is discharged from the spinneret 4 through the spinning pack 3 from the flow path 5,
The discharged yarn 6 is cooled and solidified by the cooling air blown from the blower 7.

The melt-spinning apparatus of the present invention comprises a pack heater 1
The spinneret 4 is attached to the spinneret 4 and the spinneret 4 is
Is heated by the heater 2 independent of the above.

The first feature of the present invention is that the heater 2 indirectly heats the spinneret 4 mainly by radiation through the clearance 0.5-5.0 mm with the spinning pack 3 so that the surface of the spinneret can be heated. Is small. If the clearance is less than 0.5 mm, the temperature difference between the inside and outside of the spinneret surface becomes large, causing a bending phenomenon or breakage of the yarn discharged from the discharge hole, resulting in a large difference in fineness between single yarns of the obtained fiber. As a result, the quality of the fiber decreases. On the other hand, when the clearance exceeds 5.0 mm, the heating effect on the spinneret 4 becomes small, so that the thinning of the yarn after ejection becomes unstable, the thickness unevenness of the obtained fiber becomes large, Frequent thread breaks.

Further, a second feature of the present invention is that the upper surface of the heater 2 is 0 to 10 mm above the upper surface of the spinneret 4 and the lower surface of the heater 2 is 5 to 10 mm below the lower surface of the spinneret 4.
By setting it to be 50 mm lower, the heating effect on the spinneret 4 is high without expanding the temperature distribution on the spinneret surface. When the upper surface of the heater 2 is below the upper surface of the spinneret 4, the heating effect of the heater 2 on the spinneret 4 is small. The fineness difference between the single yarns of the fiber increases, and the quality of the fiber decreases. Further, when the upper surface of the heater 2 is located above the upper surface of the spinneret 4 by more than 10 mm, thermal decomposition of the thermoplastic polymer is promoted.
The resulting fibers are colored and cause thread breakage. If the distance between the lower surface of the heater 2 and the lower surface of the spinneret 4 is less than 5 mm, the heat radiation area of the heater 2 with respect to the spinneret 4 becomes small, so that the temperature distribution on the spinneret surface becomes large and the yarn discharged from the discharge hole is discharged. This causes a bending phenomenon or yarn breakage, resulting in a large difference in fineness between single yarns of the obtained fiber, and the quality of the fiber is reduced. If the distance between the lower surface of the heater 2 and the lower surface of the spinneret 4 exceeds 50 mm, the heating effect on the discharged yarn becomes large, so that the temperature distribution between the discharged single yarns becomes large, and the unevenness of the thickness of the fiber becomes large. Frequent increase, fusion and yarn breakage.

The temperature of the heater 2 can be appropriately set, but it is preferable that the temperature of the heater 2 be equal to or higher than the temperature of the pack heater 1 + 5 ° C. and equal to or lower than the temperature of the pack heater 1 + 50 ° C. . The temperature of heater 2 is changed to the temperature of pack heater 1.
When the temperature is + 5 ° C. or higher , the molten thermoplastic polymer is gradually cooled at the spinneret and discharged, so that the thinned yarn after discharging becomes stable, and the thickness of the obtained fiber becomes uneven, and <br/> Fusing and thread breakage are reduced. Further, when the temperature of the heater 2 is set to be equal to or lower than the temperature of the pack heater + 50 ° C., the temperature difference between the inside and outside of the spinneret surface becomes small, and the bending phenomenon and the yarn breakage of the yarn discharged from the discharge hole are suppressed. The difference in fineness between the single yarns of the obtained fibers is reduced, and a high-quality product can be obtained.

In the melt-spinning apparatus of the present invention, the uppermost blowing section A of the blower 7 for cooling the yarn 6 must be provided below the lower surface of the spinneret 4 within 100 mm. If the distance between the uppermost blowing section A of the blower 7 and the lower surface of the spinneret 4 exceeds 100 mm, the atmosphere immediately below the spinneret becomes turbulent, so that the thinning of the discharge yarn becomes unstable and the resulting fiber The thickness irregularity increases, and fusion and thread breakage occur frequently. Further, the direction of the cooling air blown from the blower 7 is preferably blown in the horizontal direction. When spun out, the spinneret surface is cooled,
There is a tendency for yarn breakage to occur frequently, and when blown downward, turbulence occurs in the atmosphere below the spinneret, so that yarn spots tend to worsen.

As the thermoplastic polymer in the present invention, a polymer having melt-spinnable thermoplastic properties such as polyester, polyamide and polyolefin can be used, and in particular, polyethylene terephthalate is used because the effect of the present invention is remarkable. Is preferred. Further, the melt spinning apparatus of the present invention is not only for the production of ultrafine fibers, but also for the modified spinning of irregularly shaped cross-section yarns, hollow fibers, etc.
An advantageous effect can also be obtained for reducing fineness unevenness.

[0019]

The present invention will be specifically described below with reference to examples. In addition, each characteristic value in the examples was obtained by the following method.

(A) Intrinsic Viscosity An orthochlorophenol solution was used and measured at 30 ° C.

(B) Strength and Elongation Using a Tensilon tensile tester manufactured by Toyo Baldwin Co., a load elongation curve of the drawn yarn was determined at a sample length of 200 mm, a pulling speed of 200 mm / min, and a chart speed of 300 mm / min. The strength obtained by dividing the force at the time of
The value obtained by multiplying the value obtained by dividing the elongation at break of the yarn by the sample length by 100 was defined as the elongation.

(C) Yarn spot A yarn speed of 2 was measured using a Worster spot tester manufactured by Zellberger.
5m / min, range ± 12.5%, chart speed 50mm
/ Min, and the U% value obtained by measuring the thickness unevenness of the drawn yarn in the fiber axis direction for 3 minutes was defined as the yarn unevenness. The uniformity of the yarn was determined as follows. U% value 0 to 0.30: very good 0.31 to 0.50: good 0.51 to 0.80: slightly good 0.81 or more: bad (E) unevenness of fineness between single yarns The cross section of the drawn yarn was determined by microscopic observation.

(F) Spinnability The number of yarn breaks during spinning that occurred until 5000 undrawn yarn packages of 6 kg winding were obtained. The spinnability was determined as follows. Number of times of spun yarn breakage 0 to 10 times: very good 11 to 20 times: good 21 to 30 times: somewhat good 31 times or more: bad (G) stretchability The stretching that occurs until 3,000 drawn yarn packages of 2 kg winding are obtained. The number of yarn breaks at that time. The determination of the stretchability was as follows. Number of times of drawing yarn breakage 0 to 10 times: very good 11 to 20 times: good 21 to 30 times: somewhat good 31 times or more: bad Example 1 Polyethylene having an intrinsic viscosity of 0.62 using the melt spinning apparatus of FIG. Terephthalate was melt spun. The obtained unstretched yarn was stretched by a conventional method at a magnification at which the elongation of the obtained stretched yarn was about 35%. The spinning conditions and stretching conditions were as follows. Spinning conditions Pack heater 1 temperature: 290 ° C. Heater 2 temperature: 310 ° C. Clearance between heater 2 and spin pack 3: 2.0 mm Position of upper surface of heater 2: 5 mm above upper surface of spinneret 4 Position of the lower surface of the vessel 2: 30 mm below the lower surface of the spinneret 4 Position of the uppermost blowing part of the blower 7 A: 50 mm below the lower surface of the spinneret 4 Cooling air blowing direction: horizontal Hole diameter: 0.20 mm Discharge rate: 12.0 g / min Spinning speed: 1500 m / min Drawing conditions Supply roll temperature: 86 ° C. Hot plate temperature: 140 ° C. 5 times, and the spinnability and stretchability were very good.

The physical properties of the obtained drawn yarn were as follows: fineness: 72 denier, single yarn fineness: 0.50 denier, strength: 4.6 g / denier, and elongation: 35%. The U% value was 0.25, and the uniformity of the yarn was very good. In addition, there was no unevenness in fineness between the single yarns.

Example 2 Spinning and stretching were performed in the same manner as in Example 1 except that the clearance between the heater 2 and the spin pack 3 was changed as shown in Table 1. The results are as shown in Table 2, and the results of No. 2 within the scope of the present invention. At a level of 3 to 6, spinnability, stretchability and uniformity of the yarn were slightly good or higher, and unevenness in fineness between single yarns was hardly observed.

N with a clearance smaller than 0.5 mm
o. At the levels of 1 and 2, spinnability and stretchability were poor, and the fineness unevenness between single yarns was large. No. whose clearance is larger than 5.0 mm. At a level of 7, spinnability and stretchability were poor and yarn spots were large.

[0027]

[Table 1]

[Table 2] Example 3 Spinning and stretching were performed in the same manner as in Example 1 except that the positions of the upper surface and the lower surface of the heater 2 were changed as shown in Table 3. The results are as shown in Table 4, and are within the scope of the present invention.
o. At the levels of 9, 10, 13 and 14, spinnability, drawability and yarn uniformity were slightly better.
Further, unevenness of fineness between single yarns was hardly observed.

[0028]

[Table 3]

[Table 4] The upper surface of the heater 2 is located below the upper surface of the spinneret 4.
o. At a level of 8, spinnability and stretchability are poor,
The fineness unevenness between single yarns was large. In addition, the upper surface of the heater 2 is located above the upper surface of the spinneret 4 by more than 10 mm.
o. At a level of 11, yarn breakage occurred frequently during spinning and drawing. Further, the obtained fiber was colored yellow.

Further, No. 3 in which the lower surface of the heater 2 is less than 5 mm below the lower surface of the spinneret 4. At a level of 12,
The spinnability and stretchability were poor, and the unevenness of fineness between single yarns was large. In addition, No. 2 in which the lower surface of the heater 2 is lower than the lower surface of the spinneret 4 by more than 50 mm. At a level of 15, yarn breakage occurred frequently during spinning and drawing, and yarn spots were large.

Example 4 Spinning and drawing were carried out in the same manner as in Example 1 except that the position A of the uppermost blow-out portion of the blower 7 was changed as shown in Table 5. The results are as shown in Table 6 and are within the scope of the present invention.
o. At a level of 16 to 18, spinnability, stretchability and uniformity of the yarn were slightly better. The position A of the uppermost blow-off portion of the blower 7 is below No. 100 mm below the spinneret. At a level of 19, spinnability, stretchability and yarn uniformity were all poor.

[0031]

[Table 5]

[Table 6] Example 5 Spinning and stretching were performed in the same manner as in Example 1 except that the temperature of the heater 2 was changed as shown in Table 7. The results are shown in Table 8, and at any level within the scope of the present invention, spinnability, stretchability, and yarn uniformity were slightly better or better. The temperature of the heater 2 was 5 to 50 ° C. higher than the temperature of the pack heater 1. Spinnability at a level of 22-24,
The drawability and yarn uniformity were very good.

[0032]

[Table 7]

[Table 8] Example 6 Spinning and stretching were performed in the same manner as in Example 1 except that the discharge amount was changed as shown in Table 9. The results are as shown in Table 10, and the spinnability, stretchability and yarn uniformity were at levels of good or better. In addition, there was almost no fineness unevenness between the single yarns.

[0033]

[Table 9]

[Table 10]

[0034]

According to the present invention, it is possible to produce ultrafine fibers having a single fiber fineness of 0.1 to 1.0 denier after stretching with good spinning operability by a melt spinning method, and to reduce unevenness in quality. It is possible to obtain small and high-quality ultrafine fibers.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing one example of a melt spinning apparatus of the present invention.

[Explanation of Signs] 1 ... Pack heater 2 ... Heating device 3 ... Spin pack 4 ... Spinneret 5 ... Flow path 6 ... ··· Thread 7 ···························································· 位置

Claims (2)

(57) [Claims] 1. A pack heater for heating a molten thermoplastic polymer in a flow path from a heating / melting device to a spinneret, and a separate heater independent of the pack heater are provided. 0.5 to clearance with spinning pack
Heating the spinneret via 5.0 mm, the upper surface of the heater is 0-10 mm above the upper surface of the spinneret, and the lower surface of the heater is 5-50 mm below the lower surface of the spinneret; A melt spinning apparatus, wherein an uppermost blowing portion of a blower for cooling a discharge yarn is provided below the lower surface of the spinneret within 100 mm. 2. The temperature of the heater is equal to the temperature of the pack heater plus the temperature of the pack heater.
The melt spinning apparatus according to claim 1, wherein the temperature is 5 ° C or more and the temperature of the pack heater is + 50 ° C or less.