JPH06306755A - Production of melt-blow nonwoven fabric - Google Patents

Abstract

PURPOSE:To enable the production of a uniform nonwoven fabric without deteriorating the working environment even by using an ultrafine fiber having a diameter smaller than several microns. CONSTITUTION:Fibers F produced by ejecting a molten polymer from a nozzle are blown against a moving collection face 4 together with a compressed gas flow to form a melt-blow nonwoven fabric S. In the above process, an assistant moving collection member 6 is oppositely placed at the downstream position adjacent to the fiber blowing part A on the moving collection face 4 and the fiber collected by the assistant moving collection member 6 is transferred to the surface of the melt-blow nonwoven fabric S.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the production of a non-woven fabric by the melt-blowing method, and more particularly to a method of producing a non-woven fabric which is uniform and has a fine workability while maintaining a good working environment. .

[0002]

2. Description of the Related Art A method for producing a non-woven fabric by this melt blowing is usually a method in which a molten thermoplastic polymer is extruded in a fibrous form from a large number of orifices, and this is extruded together with a heating gas on a moving collection surface of a porous belt or drum. It is carried out by collecting in sheet form. However, in such a method for producing a melt-blown nonwoven fabric, a part of the fiber flow blown onto the moving collecting surface is scattered with gas, or the thickness and the basis weight of the nonwoven fabric collected on the moving collecting surface. However, there was a drawback that it became uneven. The reason for this is that once the meltblown fibers have been collected on the moving collection surface, the sprayed gas must penetrate through the already formed nonwoven fabric in order for the fiber stream that is subsequently sprayed to form into the nonwoven fabric. However, if the fabric weight of the formed non-woven fabric increases and the ventilation resistance of the non-woven fabric increases, the gas of the fiber jet does not sufficiently penetrate into the non-woven fabric and the fiber jet is reflected on the non-woven fabric surface. Part of the fiber flow is scattered or disturbed with the gas.

In order to prevent such a phenomenon, a method is generally used in which a suction device is installed on the back side of the moving collecting surface to forcibly discharge the gas blown onto the collecting surface. However, as the fibers to be collected become finer and finer, the suction force becomes limited, and when the diameter of the fibers is several microns or less, the ventilation resistance of the formed non-woven fabric increases, so suction with a suction device Even if it does not suck sufficiently, the scattering of fibers cannot be suppressed. As a result, not only the working environment is deteriorated, but also the product nonwoven fabric becomes non-uniform.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for producing a melt blown non-woven fabric, which makes it possible to produce a uniform non-woven fabric without deteriorating the working environment even with ultrafine fibers having a diameter of several microns or less. Especially.

[0005]

Means for Solving the Problems The present invention, which achieves the above object, provides a method for forming a melt-blown nonwoven fabric by spraying fibers discharged from a molten polymer from a nozzle together with a pressurized gas onto a moving collection surface to form a melt-blown nonwoven fabric. It is characterized in that an auxiliary moving collector is provided at a downstream position adjacent to the fiber spraying portion on the collecting surface, and the fibers collected by the auxiliary moving collector are transferred to the surface of the meltblown nonwoven fabric. is there.

With such a structure, even when the fibers blown onto the moving and collecting surface by melt-blowing are extremely fine, the fibers reflected by the moving and collecting surface are collected by the auxiliary moving collecting body without being scattered. In addition, a uniform nonwoven fabric can be obtained. In the present invention, the thickness of the fibers forming the meltblown nonwoven fabric is not particularly limited, but it is preferable that the average fiber diameter is in the range of 0.1 μm to 10 μm. The polymer forming the fiber is not particularly limited as long as it is a melt-spinnable polymer, and various thermoplastic polymers can be used. For example, polyolefins such as polypropylene and polyethylene, polyesters such as polyethylene terephthalate and polybutylene terephthalate, polyamides such as nylon 6 and nylon 66,
Further, copolymers thereof, ethylene / vinyl compound copolymers such as ethylene / vinyl chloride copolymer, and styrene resins can be used. These may be used alone or in combination.

FIG. 1 illustrates an apparatus used in the method for manufacturing a meltblown nonwoven fabric of the present invention. In the figure, 1 is an extruder, 2 is a hopper for supplying raw materials, and 3 is a melt blow spinning section. The melt blow spinning section 3 is configured by arranging nozzles (not shown) arranged in rows inside and gas injection nozzles (not shown) of pressurized air on both sides thereof. Below the melt blow spinning section 3, a breathable moving collecting surface 5 made of a wire mesh conveyor is installed, and a suction device 5 is provided inside thereof.

The fibers F sprayed together with the pressurized gas from the melt blow spinning section 3 are sprayed on the moving collecting surface 5, and the auxiliary moving collecting body 6 is installed at the position downstream of the spraying section A. . The auxiliary moving collector 6 is composed of a roller made of a porous material having a mesh of 5 to 200 mesh, such as a metal net or a synthetic resin net such as polyester, polyamide or fluororesin. S is the formed non-woven fabric.

FIG. 2 illustrates an apparatus according to another aspect of practicing the present invention. In this embodiment, the moving collection surface 5 is composed of a wire mesh drum, and the fiber spraying section A is used.
The auxiliary movement collector 6 on the downstream side of is composed of a mesh belt corresponding to 5 to 200 mesh. The mesh belt is made of metal such as stainless steel or polyester, polyamide,
A plate-like air flow control body made of synthetic resin such as fluororesin, and slightly upstream thereof, which guides the reflected airflow to the auxiliary moving trap 6 or synthetic resin such as polyester, polyamide, or fluororesin 7 is installed.

FIG. 3 shows still another embodiment for carrying out the present invention. In this embodiment, in a device similar to that shown in FIG. 1, a wire shape is provided below the melt blow spinning section 3.
An electrode 8 having a shape such as a knife shape or a needle shape is installed and connected to a high voltage generator (not shown) so that an electric field E is formed between the electrode 8 and the moving collection surface 5. Has become. This electric field E (electric appliance) acts to electretize the fibers to be collected.

In the melt blown nonwoven fabric manufacturing apparatus according to each of the above-described embodiments, the polymer heated and melted by the extruder 1 is injected from the melt blow spinning section 3 together with the heated gas into the fiber F, and the moving collection surface 5 is sprayed. The sheet-shaped nonwoven fabric S is sprayed onto the part A. The fibers F jetted from the melt blow spinning section 3 become ultrafine fibers having a diameter of 10 microns or less and are laminated on the moving collection surface 5, and when the basis weight is increased, the gas of the fiber jet flows the nonwoven fabric S sufficiently. Instead of penetrating, a part of the fiber jet is reflected as shown in FIG.
Although the fibers start to scatter with the gas, they are captured by the auxiliary movement collector 6 and transferred onto the nonwoven fabric S.

In the present invention, the installation position of the auxiliary moving collector 6 is important for maintaining the working environment and obtaining a uniform nonwoven fabric. The position is preferably close to the fiber spraying part A within a range in which the fiber jet flow sprayed from the melt blow spinning part 3 does not hinder the formation of the nonwoven fabric S on the moving and collecting surface 4. That is, when the auxiliary moving collector is brought close to a position where a part of the fiber jet ejected from the melt blow spinning section 3 directly comes into contact, the fibers spread over both the moving collecting surface and the auxiliary moving collector, and the nonwoven fabric S Becomes uneven.

On the other hand, in the fiber flow reflected and scattered from the moving and collecting surface, the turbulence of the fibers becomes larger as the flight distance increases, so if the installation position of the auxiliary moving and collecting body is too far from the fiber spraying section A, the non-woven fabric is formed. Is less uniform. Therefore, in the case where the flight direction of the reflected and scattered fiber flow deviates from the auxiliary moving collector due to the shape of the moving collecting surface, FIG.
It is advisable to install the air flow control body 7 as in the above embodiment to forcibly guide the reflected fiber flow to the auxiliary movement collector 6.

The transfer of fibers from the auxiliary transfer collector 6 to the meltblown nonwoven fabric S can be easily achieved by pressing the auxiliary transfer collector 6 against the meltblown nonwoven fabric S. The moving direction of the auxiliary moving / collecting body is preferably in the same direction (forward direction) as the traveling direction of the meltblown nonwoven fabric, but is not particularly limited. In short, it is preferable to move in a direction that does not disturb the arrangement of the meltblown fibers. The moving speed is preferably substantially the same as the moving speed of the meltblown nonwoven fabric.

When producing a meltblown nonwoven fabric according to the method of the present invention, the temperature of the heating gas (air) used for meltblowing is in the range of 300 to 230 ° C., and the flow rate of the heating gas (air) is the orifice row of the meltblowing spinning section. It is preferably 0.5 to ³ Nm ³ / min per 10 cm of length. The discharge rate of the meltblown fiber is 0.1 to
It is preferably within the range of 0.8 g / min / orifice.

In particular, the method of the present invention is effective in obtaining a uniform meltblown nonwoven fabric composed of ultrafine fibers, and is advantageous in improving productivity. The method of the present invention has a basis weight of 30.
It is suitable for producing a melt-blown nonwoven fabric having a high basis weight within the range of up to 200 g / m ² . That is, it is difficult to make the nonwoven fabric having a high basis weight to have a uniform thickness, but the present invention can be easily carried out. Of course, the present invention has a basis weight of 3 to
It is also effective for a non-woven fabric with a low basis weight of 30 g / m ² .

As shown in FIG. 3, the strength of the electric field E when the fibers are electretized is the electric field strength (a value obtained by dividing the applied voltage by the shortest distance between the electrode and the fiber collecting surface). Is preferably 1 KV / cm or more. In order to produce an electret fiber sheet with further excellent uniformity, a thermoplastic polymer having a volume density of 10 ¹⁴ Ω · cm or more is selected from among the various melt-blown thermoplastic polymers described above, and the electric field strength is selected. It is better to collect the meltblown fiber jet in an electric field of 1 KV / cm or more.

The meltblown nonwoven fabric obtained by the method of the present invention may be subjected to shaping, fluid processing, pressing, electrostatic processing, etc., if necessary, or may be compounded with other materials.

[0019]

EXAMPLES Examples and comparative examples of the present invention will be shown below.
The basis weight variation measured in these is obtained as follows. That is, 100 pieces of 10 cm square samples were cut out in the width direction of the non-woven fabric and 10 pieces in the length direction, and the weight of each sample was measured. I asked. Example A polypropylene resin was used to manufacture a meltblown nonwoven fabric under the following conditions using the apparatus shown in FIG.

Discharge rate: 0.2 g / min / orifice Temperature of pressurized gas (air): 280 ° C. Flow rate of pressurized gas (air): Approximately 2 per 10 cm width of discharge die
Nm ³ / min Moving collection surface: Wire mesh conveyor of 150 mesh Suction static pressure: 100 mmAq Auxiliary moving collection body: Wire mesh roller of 30 mesh (Rotation direction is the same direction as the direction of the nonwoven fabric) In this melt blowing method, moving collection surface All the fibers scattered from were trapped by the auxiliary moving collector and transferred to the nonwoven fabric on the moving collecting surface. The non-woven fabric obtained in this way has a basis weight of 8 microfibers having an average diameter of about 1 μm.
The nonwoven fabric was 0 g / m ² and had a variation in unit weight of about 3%. Comparative Example A melt-blown nonwoven fabric was produced under the same conditions as in the above-mentioned example except that the auxiliary transfer collector was not used. The non-woven fabric thus obtained was a non-woven fabric having a basis weight of 80 g / m ² made of ultrafine fibers having an average diameter of about 1 μm and a variation in basis weight of about 5%. Further, during the production, the fibers were scattered from the moving and collecting surface to deteriorate the working environment, and it was difficult to endure long-time operation.

[0021]

As described above, according to the present invention, even when a melt blown nonwoven fabric of ultrafine fibers is manufactured, the auxiliary moving collector collects the fiber jet reflected from the moving collecting surface to the nonwoven fabric surface. Since it is transferred, it is possible to obtain a uniform nonwoven fabric without scattering fibers.

[Brief description of drawings]

FIG. 1 is a schematic view showing an example of an apparatus used in the method for producing a meltblown nonwoven fabric of the present invention.

FIG. 2 is a schematic view showing another example of the apparatus used in the present invention.

FIG. 3 is a schematic view showing still another example of the apparatus used in the present invention.

FIG. 4 is a schematic view for explaining the action of the auxiliary movement collector used in the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Extruder 3 Melt blow spinning section 4 Moving collecting surface 5 Suction device 6 Auxiliary moving collecting body 7 Air flow control body 8 Electrode

Claims (7)

[Claims] 1. A method for forming a melt-blown nonwoven fabric by spraying a molten polymer discharged from a nozzle with a pressurized gas onto a moving and collecting surface, in the downstream of the moving and collecting surface adjacent to a fiber spraying portion. A method for producing a meltblown nonwoven fabric, wherein an auxiliary movement collector is provided at a side position, and the fibers collected by the auxiliary movement collector are transferred to the surface of the meltblown nonwoven fabric. 2. The method for producing a meltblown nonwoven fabric according to claim 1, wherein the fibers sprayed onto the fiber spraying portion are ultrafine fibers having an average diameter of 0.1 to 10 μm. 3. The method for producing a melt-blown nonwoven fabric according to claim 1, wherein the fiber collection surface of the auxiliary movement collector is made of a porous material. 4. The method for producing a meltblown nonwoven fabric according to claim 3, wherein the fiber collecting surface is a porous material having voids corresponding to 5 to 200 mesh. 5. The method for producing a meltblown nonwoven fabric according to claim 1, wherein an air flow control body is provided between the fiber spraying portion of the moving and collecting surface and the auxiliary moving and collecting body. 6. The method for producing a meltblown nonwoven fabric according to claim 5, wherein the airflow control body is a plate-like material having a flat surface or a curved surface. 7. The method for producing a meltblown nonwoven fabric according to claim 1, wherein an electric field is applied to a region of the fiber spraying portion.