The present disclosure relates to a method for producing ultrafine fiber (or filament) nonwoven fabric and an apparatus therefor, in particular to the method which has excellent productivity and the apparatus therefor with a reduced size.
Hitherto, ultrafine fiber nonwoven fabric has been produced with using a spinning die of a substantial cuboid shape, which has nozzle holes for melt blowing thermoplastic polymer and slits for jetting hot air in both sides of the nozzle holes. The nozzle holes are linearly arranged in a longitudinal direction of the substantial cuboid spinning die. The spinning die is set to adjust the longitudinal direction of the spinning die to a width direction of the ultrafine fiber nonwoven fabric. A lot of ultrafine fibers are blown from the nozzle holes and accumulated to form ultrafine fiber nonwoven fabric.
A schematic cross sectional view of the spinning die is shown in
However, the spinning die 1 needs to have the pipes 6, 6, the hot air passages 5, 5 and the slits 4, 4 in both sides of the nozzle hole, to result in a drawback of a large-sized apparatus. The object of the present disclosure is to overcome the drawback and to make a small-sized apparatus. In addition, the spinning die is small-sized and a plurality of the spinning dies may be arranged in parallel, thus a productivity of ultrafine fiber nonwoven fabric may be enhanced.
In order to solve the above problems, according to the present disclosure, it is not always necessary to include the slits in both sides of the nozzle hole. Accordingly, the reason why the conventional spinning die includes the slits in both sides of the nozzle hole is considered that the thermoplastic polymer is melt blown from the nozzle hole 2 by jetting hot air to the axis direction of the nozzle and the melt blown ultrafine fiber is extended to the direction of the axis to enhance the strength of the ultrafine fiber. However, it has been found that, even if hot air is jetted to the direction of axis of the ultrafine fiber in the condition, because the ultrafine fiber is floating in the air, almost no extension effects of the fiber are obtained.
Accordingly, in the present disclosure, hot air has been jetted from only one side of the nozzle hole to produce ultrafine fiber nonwoven fabric, and it was found that the resultant ultrafine fiber nonwoven fabric has almost the same properties as the conventional ultrafine fiber nonwoven fabric. Thus, the present disclosure provides a method for producing ultrafine fiber nonwoven fabric, which comprises: a step of melt blowing thermoplastic polymer from a plurality of nozzle holes which are disposed in a longitudinal direction at a longitudinal lower end of a spinning die having a substantial cuboid shape to obtain ultrafine fibers, a step of jetting out hot air from a slit disposed in only one side of the nozzle holes to blow the ultrafine fibers at an angle inclining with respect to the direction of an axial line of the nozzles, and a step of accumulating the blown ultrafine fibers which are sucked downward from the spinning die to form the ultrafine fiber nonwoven fabric.
The production method of the present disclosure is conducted with using a specific spinning die. The specific spinning die may include an embodiment shown in
A slit is provided in only a right side of the nozzle hole 2. Hot air is flowed in pipes 6 in a pressurized condition and passed through hot air passage 5, thus jetting from slit 4. Accordingly, the ultrafine fibers from the nozzle 2 are blown to a left side to the axis line direction of the nozzle by jetting hot air.
Hot air is jetted to the ultrafine fibers at an angle of θ inclining with respect to the direction of the axis line of the nozzle. In this air jetting, it is necessary that the ultrafine fibers are sucked downward of the spinning die 1. Without sucking, it is not so easy that the ultrafine fibers are uniformly accumulated on a conveyer provided under the spinning die 1, thus deteriorating qualities of the resultant ultrafine fiber nonwoven fabric. The sucking can generally be conducted by a reduced pressure using a suction box from a lower portion of a breathable conveyer, such as a wire mesh chain conveyer and the like.
In
The apparatus for the production method of the present disclosure is comprised of the spinning die 1 shown in
Actually, the production of the ultrafine fiber nonwoven fabric may be conducted by an apparatus of only one of the spinning die 1 as shown in
The term “ultrafine fiber” as used herein means fiber having a fiber diameter of about 1 to about 15 μm. The thermoplastic polymer employed herein can be polyolefin, polyamide, polyester or the like. The nozzle hole 2 can generally have a diameter of about 0.1 to about 0.5 mm. Number of the nozzle holes can be 30 to 100 dies/inch and the nozzle holes are arranged in a longitudinal direction at a longitudinal lower end of a spinning die 1. The nozzle generally has a length of about 1 to about 5 mm.
In the combined apparatus of the present disclosure, a mixed ultrafine fiber nonwoven fabric can be obtained by changing the sorts of the thermoplastic polymer melt blown from each of the apparatuses. For example, polyester fiber is melt blown from one of the combined apparatus and polypropylene is melt blown from the other of the combined apparatus, thus obtaining a polyester/polypropylene ultrafine fiber nonwoven fabric. In the combined apparatus of the present disclosure, another mixed ultrafine fiber nonwoven fabric can be obtained by changing each diameter of the nozzle hole 2, thus obtaining a ultrafine fiber nonwoven fabric having different fiber diameter. For example, a thermoplastic polymer is melt blown from one of the combined apparatus which provides nozzle holes having a diameter of 0.1 mm and a thermoplastic polymer is melt blown from the other of the combined apparatus which provides nozzle holes having a diameter of 0.5 mm, thus obtaining a ultrafine fiber nonwoven fabric having a mixed fiber diameter.
The ultrafine fiber nonwoven fabric obtained by the production method of the present disclosure can be used for applications, such as filter material, cleaning cloth or the like.
The apparatus of the present disclosure has technical effects of making it miniaturized because it has the pipe flowing hot air, the passage for hot air and the slit only in one side of the nozzle holes, as it is clear when comparing with the conventional apparatus of
Number | Date | Country | Kind |
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2015-144966 | Jul 2015 | JP | national |
This application is a National Phase application filed under 35 USC 371 of PCT International Application No. PCT/JP2016/070580 with an International Filing Date of Jul. 12, 2016, which claims under 35 U.S.C. § 119(a) the benefit of Japanese Application No. 2015-144966 filed on Jul. 22, 2015, the entire contents of which are incorporated herein by reference.
Filing Document | Filing Date | Country | Kind |
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PCT/JP2016/070580 | 7/12/2016 | WO | 00 |