JP7765804B2 - Method and apparatus for producing particle-composite long fiber entangled body - Google Patents

Description

The present invention relates to a method and apparatus for producing a tangled long-fiber body made of a thermoplastic resin compounded with powder particles, and in particular to a method and apparatus for producing a tangled long-fiber body in which particles are compounded on the surface of long fibers stretched by the melt-blowing method.

A method for producing an entangled long-fiber body using the melt-blowing method has been proposed, in which thermoplastic resins such as polyethylene (PE) and polypropylene (PP) are melted and extruded from an extruder, stretched by a high-speed airflow, and released into the air to produce an entangled long-fiber body made of long fibers with nanometer diameters ranging from several tens of microns to submicrons.

For example, Patent Document 1 discloses a method for producing tangled long fibers using the melt-blowing method. This method involves horizontally directing airflow from a gas nozzle attached to a nozzle head adjacent to the resin nozzle, creating negative pressure near the outlet of the resin discharge nozzle, drawing the resin out and subjecting it to strong stretching.

It is hoped that functional particles can be compounded with the long fibers of the entangled long-fiber structure obtained by the melt-blowing method, as described above, to achieve desired functionality. One possible method involves creating pellets containing the functional particles, feeding them into an extruder, and melt-blowing them. However, the non-ductile particles can disrupt the long fibers, making it difficult to achieve good stretching. Furthermore, after stretching, the functional particles may become largely embedded within the long fibers and not be exposed, preventing them from fully demonstrating their function. On the other hand, increasing the ratio of functional particles to resin to achieve sufficient functionality makes it even more difficult to achieve good stretching.

Patent Document 2 discloses a method in which solid particles heated to a temperature higher than the melting point of a thermoplastic resin, obtained by a melt-blowing method or the like, are brought into contact with fibers constituting a nonwoven fabric made of the thermoplastic resin, fusing the particles to the fiber surface and forming a composite. This method is said to prevent the solid particles from becoming embedded in the fibers without melting and fluidizing the entire resin on the fiber surface. Proposed methods for contacting the solid particles with the fibers include blowing an airflow containing the solid particles onto the fiber surface, or allowing the solid particles to fall naturally onto the fibers.

Patent No. 6171072 Japanese Patent Application Laid-Open No. 2004-3070

It is desirable to composite functional particles so that they are exposed on the surface of the long fibers stretched by the melt-blowing method, rather than being embedded inside. However, the composite functional particles tend to fall off the fiber surface and lose their function when the tangled long-fiber body is washed, for example. Furthermore, as mentioned above, the process of bringing heated particles into contact with the fibers is complicated, reducing production efficiency and undermining the advantage of the melt-blowing method, which produces tangled long-fiber bodies with high production efficiency.

The present invention was made in light of the above circumstances, and its purpose is to provide a manufacturing method and apparatus for producing, with high production efficiency, an entangled long-fiber body in which powder particles are composited onto the surface of long fibers stretched by the melt-blowing method.

The method for producing a particle-composite tangled long fiber body according to the present invention is a method for producing a tangled long fiber body made of a thermoplastic resin compounded with powder particles, in which the thermoplastic resin is melted in an extruder screw and continuously discharged from a resin nozzle of a nozzle head, and an airflow is formed horizontally from a gas nozzle attached to the nozzle head adjacent to the resin nozzle, and the thermoplastic resin is stretched by the airflow, releasing self-adhesive long fibers into the air to form a tangled long fiber body. In this process, powder particles are supplied to a predetermined position along the airflow from the nozzle head, stretching the thermoplastic resin and causing the powder particles to contact and adhere to the surface of the thermoplastic resin as it is stretched.

The apparatus for producing a particle-composite tangled long fiber body according to the present invention is an apparatus for producing a tangled long fiber body by melting a thermoplastic resin in an extruder screw, continuously discharging it from a resin nozzle of a nozzle head, and stretching the thermoplastic resin with an airflow directed horizontally from a gas nozzle attached to the nozzle head adjacent to the resin nozzle, thereby releasing self-adhesive long fibers into the air, and is characterized by including a powder particle supply mechanism that supplies powder particles at a predetermined position along the airflow from the nozzle head, stretching the thermoplastic resin while bringing the powder particles into contact with the surface of the thermoplastic resin.

This feature makes it possible to produce with high production efficiency a long-fiber entanglement body in which powder particles are composited onto the surface of long fibers stretched by the melt-blowing method.

1 is a side view (partial cross section) of a particle-composite tangled long fiber body during production and a production apparatus therefor. FIG. FIG. FIG. 1 is a cross-sectional view (partially a block diagram) of an extruder. FIG. 1 is a side view of a bundle of filaments being drawn. 1 is a photograph showing the appearance of the obtained tangled long-fiber body. This is an enlarged photograph of a part of the entangled long fibers being loosened.

The following describes a method and apparatus for producing a particle-composite entangled long fiber body as a representative example of the present invention, using Figures 1 to 6.

As shown in Figures 1 and 2, in this embodiment, the method for producing a particle-composite tangled long fiber body involves producing the tangled long fiber body by the so-called melt-blowing method, while adhering powder particles 7 to the surfaces of the long fibers, thereby combining the powder particles 7 with the tangled long fiber body.

Specifically, a thermoplastic resin is melted in the screw 2 of the extruder 1 and continuously discharged from the resin nozzle 3a of the nozzle head 3. A gas nozzle 3b attached to the nozzle head 3, adjacent to the resin nozzle 3a, forms an airflow 4 directed horizontally. As a result, the molten thermoplastic resin 6a is stretched by the airflow 4 and released into the air, forming long fibers 6b. The released long fibers 6b are collected by a collection net 11 attached ahead of the airflow 4, forming a tangled long fiber mass 6. While multiple pairs of resin nozzles 3a and gas nozzles 3b are arranged on the nozzle head 3 in this embodiment (see Figure 2 in particular), other known nozzle head configurations may also be used. The thermoplastic resin is a self-adhesive resin in a molten state or a semi-molten state that has been stretched to form long fibers, allowing the powder particles described below to adhere to it. Examples of suitable resins include polyolefin resins such as polypropylene (PP) and polyethylene (PE).

To apply particles to the surface of the tangled long fibers, the tangled long fiber manufacturing apparatus 10 is equipped with a powder particle supply mechanism 5 that supplies powder particles 7 to the surface of long fibers made of a self-adhesive resin. The powder particle supply mechanism 5 includes, for example, a supply pipe 5a that discharges the powder particles 7 downward. The tip opening 5b of the supply pipe 5a is positioned to supply the powder particles 7 to a predetermined position along the airflow 4 from the nozzle head 3. The tip opening 5b may be positioned above the airflow 4 to supply the powder particles by scattering them downward. However, it is preferable to supply the powder particles by positioning the tip opening 5b so that it is inserted into the airflow 4, as this ensures a reliable supply of powder particles and makes it easy to adjust the supply amount. The powder particles 7 may also be supplied by being projected from below, to the side, or obliquely across the airflow 4.

As described below, the powder particles 7 are formed by drawing self-adhesive thermoplastic resin into long fibers, and are applied to the surface while maintaining their self-adhesive properties, thereby adhering to the surface. While drawing and self-adhesive properties are not necessarily strictly synchronized, the fact that a long-fiber entanglement body in which the long fibers are bonded and entangled after drawing can be obtained means that self-adhesive properties are maintained at least during the drawing process. In other words, the supply location of the powder particles 7 is important, and it is preferable to adjust this location in accordance with the manufacturing conditions. Therefore, the powder particle supply mechanism 5 preferably further includes a position control mechanism 5c that can adjust the position of the tip opening 5b in a direction along the central axis A of the airflow 4 and adjust the distance from the central axis A toward or away from it.

As shown in FIG. 3, the extruder 1 sends molten resin in the barrel 22 toward the nozzle head 3 by rotating the screw 2 to extrude the molten resin from the nozzle head 3. That is, the molten resin is extruded toward the nozzle head 3 while rotating due to the rotation of the screw 2. Meanwhile, the resin passing through the nozzle head 3 passes through the resin nozzle 3a (see FIG. 2) provided on the nozzle head 3 and travels straight in the direction of extension of the resin nozzle 3a. Therefore, in the vicinity of the nozzle head 3, a shear force transverse to the direction of extension of the resin nozzle 3a is applied to the molten resin. The extruder 1 also includes a hopper 24 for feeding pellets, which are the material for the molten resin, a heater 25 for heating the barrel 22 to melt the pellets, a gas supply unit 26 and a gas heating unit 27 for supplying heated gas to the nozzle head 3, etc.

As shown in Figure 4, when molten resin 6a is discharged horizontally forward from the nozzle head 3, it branches and stretches to form long fibers 6b, continuously forming bundles 6c of long fibers 6b of a certain length. At this time, as described above, the rotation of the screw 2 generates shear forces in the molten resin 6a that transverse the direction of extension of the resin nozzle 3a. This shear force acts on the molten resin 6a discharged from the nozzle head 3 in a direction corresponding to the rotation of the screw 2, causing it to break. It is believed that the bundles 6c of long fibers 6b are not continuous but of a certain length. Furthermore, while the molten resin 6a is being stretched, the bundles 6c are positioned relatively parallel to the central axis A of the airflow 4, which is the stretching direction. However, once stretching is complete, the turbulence of the airflow causes the bundles 6c to rotate and deviate from the central axis A.

For example, during drawing, a bundle of long fibers 6b absorbs the force of being pulled forward by the airflow as it is drawn, and extends downstream with one end supported by the nozzle head 3. As a result, bundles 6c are positioned relatively parallel to the central axis A. On the other hand, resin that can no longer be drawn or has been drawn thin enough is subjected to the force from the airflow and the shear force described above, causing it to break. This causes the end support to disappear, and coupled with the turbulence of the airflow and a slower forward airflow, bundles 6c bend as they move away from the central axis A. In other words, the section where bundles 6c of long fibers 6b are positioned approximately parallel to the central axis A serves as an indication of the section where the resin is being drawn.

Furthermore, the fact that the resin (molten resin 6a or long fibers 6b) is being stretched means that the resin still has fluidity, and at least the self-adhesive properties of the resin allow particles to adhere to the surface. Note that particle density can be increased by attaching particles after stretching has progressed to a certain extent, rather than before or during stretching. Therefore, it is also preferable to attach the particles at a position a certain distance from the nozzle head 3, as long as the self-adhesive properties are not lost.

In light of the above, the predetermined position for supplying the powder particles 7 can be set in section Z, where the molten resin 6a or the resulting long fibers 6b travel substantially parallel to the central axis A of the airflow 4. In other words, to facilitate adhesion of the powder particles 7 to the surfaces of the long fibers 6b, it is preferable to set the predetermined position in a section where the resin is stretched, i.e., where the resin has fluidity. Furthermore, as mentioned above, it is also preferable to set the predetermined position downstream of section Z, so that the resin is separated from the nozzle head 3 to a degree that does not cause it to lose its adhesiveness due to its fluidity.

The predetermined position for supplying these powder particles 7 can be easily adjusted by providing the position control mechanism 5c described above. Note that in the melt-blowing method, the length of the aforementioned section Z changes depending on the type of resin, temperature, airflow speed, etc. It is preferable to provide a position control mechanism 5c in order to accommodate changes in section Z due to such manufacturing conditions.

This results in a tangled long-fiber body 6 in which powder particles 7 are composited onto the surfaces of the long fibers 6b stretched by the melt-blowing method. In particular, because the step of adhering the powder particles 7 is carried out simultaneously with stretching by the melt-blowing method, the tangled long-fiber body 6 can be obtained with high production efficiency. This method allows the powder particles 7 to adhere to the surfaces of the long fibers 6b. Therefore, for example, when using powder particles 7 made of a functional material that exhibits its function when exposed on the surfaces of the long fibers 6b, this is preferable as it can impart high functionality to the tangled long-fiber body 6.

A process may also be added to remove some of the powder particles 7 that have not adhered to the long fibers 6b from the tangled long-fiber body 6. For example, air may be blown in a direction intersecting the central axis A on the upstream side of the collection net 11, or the tangled long-fiber body 6 after collection may be sieved.

As shown in Figure 5, the above manufacturing method produced a tangled long fiber body 6 made of PP long fibers with a diameter of 20 microns or less, which had a cotton-like appearance.

As shown in Figure 6, powder particles 7 (here, white ceramic particles) are attached to the surface of the long fibers 6b at relatively close intervals. In particular, the powder particles 7 are hardly buried inside the long fibers 6b, but rather are attached so that most of their surface is exposed and they are in partial contact with the long fibers 6b. In other words, when powder particles 7 that perform their function by being exposed are used, it is thought that particularly high functionality can be imparted to the tangled long-fiber body 6. This type of attachment state is thought to be a characteristic of the fact that the powder particles 7 are supplied from the outside while the long fibers 6b are being stretched, and are attached by the self-adhesive properties of the long fibers 6b.

Although the present invention has been described above with reference to examples and variations thereof, the present invention is not necessarily limited to these examples. Furthermore, those skilled in the art will be able to identify various alternative embodiments and modifications without departing from the spirit of the present invention or the scope of the appended claims.

REFERENCE SIGNS LIST 1 Extruder 2 Screw 3 Nozzle head 4 Air flow 5 Powder particle supply mechanism 6 Tangled long fibers 6a Molten resin 6b Long fibers 6c Bundle A Central axis Z Section

Claims (6)

A method for producing a long-fiber entangled body made of a thermoplastic resin compounded with powder particles, comprising:
In a process of melting the thermoplastic resin with a screw of an extruder and continuously discharging it from a resin nozzle of a nozzle head, forming an airflow in a horizontal direction from a gas nozzle provided on the nozzle head adjacent to the resin nozzle, stretching the thermoplastic resin with the airflow to release self-adhesive long fibers into the air and forming an entangled long-fiber body, a process of providing powder particles at a predetermined position along the airflow from the nozzle head and stretching the thermoplastic resin while bringing the powder particles into contact with and adhering to the surface of the thermoplastic resin ,
The method for producing a particle-composite entangled long fiber body is characterized in that the powder particles are discharged from a tip opening of a supply pipe, and the tip opening is positioned inside the air flow . The method for producing a particle-composite long-fiber entangled body according to claim 1, characterized in that the predetermined position is in a section where the thermoplastic resin or the long fibers made thereof travels approximately parallel to the central axis of the airflow. 3. The method for producing a particle-composite entangled long fiber body according to claim 2, wherein the thermoplastic resin is a polyolefin resin. 4. The method for producing a particle-composite tangled long fiber body according to claim 1, further comprising a step of removing a portion of the powder particles. An apparatus for producing a tangled long fiber body made of a thermoplastic resin compounded with powder particles, comprising:
a melt-blowing device in which a thermoplastic resin is melted by a screw of an extruder and continuously discharged from a resin nozzle of a nozzle head, and an airflow is formed in a horizontal direction from a gas nozzle provided on the nozzle head adjacent to the resin nozzle, and the thermoplastic resin is stretched by the airflow, causing self-adhesive long fibers to be released into the air, thereby forming an entangled long-fiber body;
a powder particle supply mechanism that supplies powder particles to a predetermined position along the airflow from the nozzle head, stretches the thermoplastic resin, and causes the powder particles to contact and adhere to the surface of the thermoplastic resin ,
The powder particle supply mechanism includes a supply pipe for discharging the powder particles from a tip opening, and the tip opening is disposed within the airflow . 6. The apparatus for producing a particle-composite long-fiber entangled body according to claim 5 , further comprising a control mechanism for adjusting the predetermined position so that the predetermined position is in a section in which the thermoplastic resin or the long fibers made therefrom travel approximately parallel to the central axis of the airflow.