JP2003003320A - Spinning die for melt-blown nonwoven fabric - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a spinning die for a melt-blown nonwoven fabric enabling the spinning of ultrafine fibers in high efficiency and capable of reducing the energy cost. SOLUTION: A pair of hot-air blowing slits 23a, 23b are opened near the tip end 21a of a nozzle 21 to extrude a molten polymer and a pair of cold-air blowing slits 26a, 26b are placed downstream of the hot-air slits. Water-spraying slits 31a, 31b are opened in the cold-air blowing slits to supply a large volume of water-containing cold air. The molten polymer extruded from the nozzle 21 is drawn by the negative pressure generated by the flow of the cold air. Fibers having fine diameter can be produced in high efficiency by using the spinning die.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD OF THE INVENTION The present invention relates to a spinning die used when a nonwoven fabric is manufactured by a melt blow method.

[0002]

2. Description of the Related Art In the melt-blowing method, as shown in FIG. 6, raw material chips charged in a hopper 1 are heated and melted by an extruder 2, supplied to a die 3 and spun, and spun short fibers are collected. This is a method of producing a non-woven fabric by depositing it in a sheet form on a conveyor 4 composed of a collecting net, passing it through a calendar roll 5 while peeling it off from the conveyor 4, and then winding it up by a winder 6.

[0003]

The die 3 is adapted to spin the molten polymer discharged from the spinning port 3a with a high temperature air jetted from the hot air outlet 3b. The amount of the molten polymer discharged from the spinning port 3a. And a fine balance is required in the discharge amount of high temperature air, and spinning fibers of any diameter,
In particular, it was difficult to spin fibers having a small diameter, and it was not possible to obtain a non-woven fabric having high bulkiness and good texture. Further, since it is necessary to send a large amount of hot air, there is a problem that the energy cost is high.

Therefore, the present inventor has arranged a hot air discharge slit near the tip of a nozzle for extruding the molten polymer, and a slit for discharging a large amount of cold air downstream thereof to stretch the molten polymer. Has been proposed (Japanese Patent Laid-Open No. 2000-336517). It has been confirmed that a non-woven fabric having a high bulkiness composed of fine fibers can be obtained by using such a spinning die, but the drawing force is limited only by discharging cold air, and it is possible to efficiently produce fine fibers with a smaller diameter. Difficult to spin.

An object of the present invention is to provide a spinning die capable of enhancing the drawing force and efficiently spinning fine fibers.

[0006]

In order to solve the above-mentioned problems, the present invention provides, near the tip of a nozzle for extruding a molten polymer,
In a spinning die in which a pair of hot air discharge slits are arranged facing each other around the nozzle, and a pair of cold air discharge slits are arranged facing each other around the nozzle in the downstream of the hot air discharge slit, water spraying means in the cold air discharge slits. Is provided. It is preferable that the cold air discharge slit has a larger discharge air volume than the hot air discharge slit. Further, it is preferable that a pair of slits communicating with the outside air be arranged between the hot air discharge slit and the cold air discharge slit so as to face each other with the nozzle as the center.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be described below with reference to FIGS. As shown in FIG. 1, a spinning die 20 is attached to the lower end of the spinning pack 10. The spinning pack 10 is formed by joining two divided main bodies 11a and 11b with bolts 12, and a melted polymer such as polypropylene resin, polyester resin, nylon (registered trademark) resin is provided on the upper portions of the main bodies 11a and 11b. Inlet 13
Is provided, and hot air inlets 14a and 14b are provided in the lower part. In addition, the side plates are provided with the holding plates 16a and 16b.
The panel heaters 15a and 15b are in contact with each other.

As shown in FIGS. 2 and 3, the spinning die 20 is provided with a plurality of nozzles 21 in a line at the tip of the polymer passage 17 continuing from the polymer injection port 13, and the tip 21a of the nozzle 21 is provided. , A pair of discharge slits 2 arranged to face each other for discharging hot air from the hot air chambers 22a and 22b
It faces the center of 3a and 23b. Also, the hot air chamber 2
2a and 22b are passages 2 in the hot air inlets 14a and 14b.
It communicates via 4a and 24b.

The cool air chambers 25a and 25b and the pair of cold air discharge slits 26a and 26b are arranged facing each other with the nozzle 21 at the center, with a constant space S from the hot air discharge slits 23a and 23b. Communicates with the cold air inlet passages 27a and 27b. The spinning outlet 29 is located in front of the cold air discharge slits 26a and 26b. The space S forms suction slits 28a and 28b for the outside air (entrained flow) near the tip of the nozzle 21. The distance S ₁ is preferably about 2 to 10 mm.

As clearly shown in FIGS. 3 and 4, the outer wall forming the cold air discharge slits 26a and 26b has a supply passage 30 for normal temperature water (about 10 ° to 30 ° C.).
Spray slits 31a, 31b are provided a and 30b over substantially the entire length of the spinning die 20 and open to slits 26a, 26b from the supply passages 30a, 30b.
Are provided respectively, and cold air discharge slits 26a and 26b are provided.
As shown in FIG. 5, water is sprayed M by the cold air passing through the water rapidly.
Are to be released.

Now, when the molten polymer is extruded from the nozzle 21, it is drawn out from both sides of the molten polymer so as to be sandwiched by the hot air blown out through a pair of hot air jet slits 23a and 23b inclined in the pushing direction, and further the cold air jet slits. 26a, 26b and spray slit 31
Since a large amount of cold air containing fine water droplets is discharged from a and 31b, the molten polymer extruded from the nozzle 21 is rapidly sucked with a strong negative pressure and pressure-stretched with a large amount of water-containing cold air. At this time, the temperature of the hot air is 200 to 300.
C., the temperature of cold air is preferably about 10 to 30.degree. C., and the amount of hot air is preferably about 5 to 20% with respect to that of cold air. For example, when the cold air is 100 to 250 m / sec, the hot air is 5 to 50 m.
It is about m / sec. That is, here, the hot air is the nozzle 21.
It suffices to heat the molten polymer extruded from the polymer to such an extent that it does not cool rapidly, and it is rapidly sucked and drawn by the negative pressure generated by the water-containing cold air to form a fine fiber. The cold air discharge slits 26a and 26b are also the hot air discharge slits 2.
Similar to 3a and 23b, it is provided with an inclination that descends toward the spinning port 29. In addition, the slit 28 that creates a wake
By forming a and 28b, it is possible to reduce the amount of air flow. Further, if the surface 32a on which the spray slits 31a and 31b are formed is tapered so as to open outward from the discharge ports of the cold air discharge slits 31a and 31b, swirling can be prevented.

[0012]

According to the present invention, as described above, a molten polymer extruded by a nozzle, which is heated with a small amount of hot air that does not cool, is stretched by negative pressure with a large amount of water-containing cold air to obtain a small diameter. A fiber having a smooth surface is obtained, which gives a non-woven fabric having high bulkiness and good texture.

Further, since the fibers are not caught at the spinning outlet, the amount of discharged polymer can be increased and the productivity can be improved.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a spinning pack incorporating a spinning die of the present invention.

FIG. 2 is a perspective view of a spinning die.

FIG. 3 is an enlarged sectional view of a spinning die.

FIG. 4 is a partially enlarged sectional view of a spinning die.

FIG. 5 is an enlarged sectional view showing a spraying means.

FIG. 6 is a partial cross-sectional schematic diagram showing a method for manufacturing a non-woven fabric by a conventional melt blow method.

[Explanation of symbols]

1 hopper 2 extruder 3 dies 3a Spinneret 3b Hot air outlet 4 conveyor 5 calendar rolls 6 winder 10 Spinning pack 11a, 11b main body 12 volt 13 inlet 14a, 14b entrance 15a, 15b Panel heater 16a, 16b Presser plate 17 passage 20 Spinning die 21 nozzles 21a Nozzle tip 22a, 22b Hot air chamber 23a, 23b Hot air discharge slit 24a, 24b passage 25a, 25b cold air chamber 26a, 26b Cold air discharge slit 27a, 27b Cold air inlet passage 28a, 28b Suction slit 29 Spinneret 30a, 30b Water supply channel 31a, 31b Spray slit 32a Surface where spray slit is formed M spray S interval

Claims (3)

[Claims] 1. A spinning die in which a pair of hot air discharge slits are arranged to face each other around the nozzle in the vicinity of the tip of a nozzle for extruding a molten polymer, and a pair of cool air discharge slits are arranged downstream to face the pair of cool air discharge slits to face each other. A melt-blowing nonwoven fabric spinning die, characterized in that water spray means is provided in the cold air discharge slit. 2. The melt-blowing nonwoven fabric spinning die according to claim 1, wherein the amount of air discharged from the cold air discharge slit is larger than the amount of air discharged from the hot air discharge slit. 3. The melt-blowing non-woven fabric spinning die according to claim 1, wherein a pair of slits communicating with the outside air are arranged opposite to each other between the hot air discharge slits and the cold air discharge slits with the nozzles as a center.