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

Abstract

To provide a manufacturing method and an apparatus for obtaining, with a high manufacturing efficiency, a long fiber entangled body in which powder particles are coupled on surfaces of long fibers drawn by a melt blowing process.SOLUTION: There is provided a manufacturing method of a long fiber entangled body, which comprises: melting a thermoplastic resin by a screw of an extruder to continuously extrude the same from a resin nozzle of a nozzle head; forming an airflow that horizontally directs from a gas nozzle provided on the nozzle head adjacent to the resin nozzle; stretching the thermoplastic resin by the airflow; and releasing self-adhesive long fibers into the air to form a long fiber entangled body. Herein, the powder particles are provided at a predetermined position along the airflow from the nozzle head, and the thermoplastic resin is stretched while being brought into contact with and adhered to the surface of the thermoplastic resin.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method and an apparatus for producing an entangled long-fiber body made of a thermoplastic resin compounded with powder particles, and more particularly to a method and an apparatus for producing an entangled long-fiber body in which particles are compounded on the surface of long fibers stretched by a melt-blowing method. [Background technology]

[0002] A method for producing entangled long fibers by 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 obtain entangled long fibers with nanometer diameters ranging from several tens of microns to submicrons.

[0003] For example, Patent Document 1 discloses a method for producing an entangled long-fiber body by a melt-blowing method, in which a negative pressure is generated near the outlet of a resin discharge nozzle by an airflow directed horizontally from a gas nozzle provided on a nozzle head adjacent to the resin nozzle, and the resin is drawn out and strongly stretched.

[0004] It is expected 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 a desired function. One possible method is to prepare pellets containing the functional particles, which are then fed into an extruder for melt-blowing. However, the non-ductile particles can disrupt the long fibers, making it difficult to achieve good stretching. Furthermore, after stretching, the functional particles may be embedded almost entirely within the long fibers, preventing them from being 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.

[0005] Patent Document 2 discloses a method of contacting fibers constituting a nonwoven fabric made of a thermoplastic resin obtained by a melt-blowing method or the like with solid particles heated to a temperature higher than the melting point of the thermoplastic resin, thereby fusing and compounding the fibers. This method is said to be able to prevent the solid particles from being embedded in the fibers without melting and fluidizing the entire resin on the fiber surface. As a method of contacting the solid particles with the fibers, methods such as blowing an airflow containing the solid particles onto the fiber surface or allowing the solid particles to fall naturally onto the fibers have been proposed. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent No. 6171072 [Patent Document 2] Japanese Patent Application Laid-Open No. 2004-3070 Summary of the Invention [Problem to be solved by the invention]

[0007] It is desirable to composite the functional particles so that they are exposed on the surface of the long fibers stretched by the melt-blowing method without being embedded inside. However, the composite functional particles tend to fall off from the fiber surface and lose their function when the tangled long-fiber body is washed, etc. Furthermore, as described above, the process of bringing heated particles into contact with the fibers is complicated, which reduces production efficiency and undermines the advantage of the melt-blowing method, which produces tangled long-fiber bodies with high production efficiency.

[0008] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a method and an apparatus for producing, with high production efficiency, a long-fiber entanglement body in which powder particles are compounded on the surface of long fibers stretched by a melt-blowing method. [Means for solving the problem]

[0009] The method for producing a particle-composite long-fiber entangled body according to the present invention is a method for producing a long-fiber entangled body made of a thermoplastic resin composited with powder particles, and is characterized in that, in the process of melting the thermoplastic resin in an extruder screw and continuously discharging it from a resin nozzle of a nozzle head, and forming an airflow horizontally from a gas nozzle provided on the nozzle head adjacent to the resin nozzle, the thermoplastic resin is stretched by the airflow and long fibers having self-adhesive properties are released into the air to form a long-fiber entangled body, powder particles are supplied to a predetermined position along the airflow from the nozzle head, and the thermoplastic resin is stretched while the powder particles come into contact with and adhere to the surface of the thermoplastic resin while the thermoplastic resin is stretched.

[0010] 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 the screw of an extruder and continuously discharging it from a resin nozzle of a nozzle head, stretching the thermoplastic resin with an air flow formed horizontally from a gas nozzle provided on the nozzle head adjacent to the resin nozzle, and releasing self-adhesive long fibers into the air, and is characterized by including a powder particle supply mechanism for supplying powder particles at a predetermined position along the air flow from the nozzle head, stretching the thermoplastic resin and bringing the powder particles into contact with the surface of the thermoplastic resin while stretching it.

[0011] According to this feature, it is possible to obtain with high production efficiency an entangled long fiber body in which powder particles are compounded on the surface of long fibers stretched by the melt-blowing method. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 2 is a side view (partial cross section) of a particle-composite tangled long fiber body during production and a production apparatus therefor. [Figure 2] FIG. [Figure 3] FIG. 1 is a cross-sectional view (partially a block diagram) of an extruder. [Figure 4] FIG. 1 is a side view of a bundle of filaments being drawn. [Figure 5]1 is a photograph showing the appearance of the obtained tangled long-fiber body. [Figure 6] This is an enlarged photograph of a part of the entangled long fibers being loosened. DETAILED DESCRIPTION OF THE INVENTION

[0013] A method and apparatus for producing a particle-composite tangled long fiber body as a typical example according to the present invention will be described below with reference to FIGS. 1 to 6. FIG.

[0014] As shown in FIGS. 1 and 2, in the method for producing a particle-composite tangled long-fiber body in this example, a so-called melt-blowing method is used to produce the tangled long-fiber body, and powder particles 7 are attached to the surfaces of the long fibers to combine the powder particles 7 with the tangled long-fiber body.

[0015] Specifically, a thermoplastic resin is melted in the screw 2 of the extruder 1 and continuously discharged from a 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 body 6. In this embodiment, the nozzle head 3 is provided with multiple pairs of resin nozzles 3a and gas nozzles 3b (see FIG. 2 in particular). However, the nozzle head may be of any other known type. The thermoplastic resin used is a resin that exhibits self-adhesive properties in a molten state or in a semi-molten state after being stretched to form long fibers, allowing powder particles (described later) to adhere to it. Examples of suitable resins include polyolefin resins such as PP (polypropylene) and PE (polyethylene).

[0016] To provide particles to the surface of the tangled long-fiber body, the apparatus 10 for producing a tangled long-fiber body includes 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 so as 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 so that the powder particles are supplied by being scattered 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 reliable supply of the powder particles and makes it easy to adjust the supply amount. The powder particles 7 may also be supplied by being projected from below, sideways, or obliquely across the airflow 4.

[0017] As described below, the powder particles 7 adhere to the surface of a self-adhesive thermoplastic resin stretched into long fibers while maintaining their self-adhesiveness. While the self-adhesiveness is not necessarily synchronized with the stretching, the fact that a long-fiber entanglement body in which the long fibers are bonded and entangled after stretching can be obtained means that the self-adhesiveness is maintained at least during the stretching process. In other words, the supply location of the powder particles 7 is important, and it is preferable to adjust this location according to 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 along the central axis A of the airflow 4 and adjust the distance from the central axis A toward or away from the central axis A.

[0018] As shown in FIG. 3, the extruder 1 sends the 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 in the nozzle head 3, and therefore 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 introducing 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, and the like.

[0019] As shown in Figure 4, when molten resin 6a is discharged horizontally forward from the nozzle head 3, the molten resin 6a is branched and stretched to form long fibers 6b, continuously forming bundles 6c of long fibers 6b of a certain length. At this time, as described above, shear forces are generated in the molten resin 6a in a direction transverse to the extension direction of the resin nozzle 3a due to the rotation of the screw 2. This shear force acts on the molten resin 6a discharged from the nozzle head 3 in a direction corresponding to the rotation direction of the screw 2, causing it to break. Therefore, 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 aligned relatively parallel to the central axis A of the airflow 4, which is the stretching direction. However, once stretching is complete, the bundles 6c rotate and deviate from the central axis A due to turbulence in the airflow.

[0020] For example, during drawing, a bundle of long fibers 6b absorbs the force of being pulled forward by the airflow and extends downstream with one end supported by the nozzle head 3. As a result, a bundle 6c is arranged 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 affected by the force from the airflow and the shear force described above and is broken. When this happens, the support at the end is lost, and coupled with the turbulence of the airflow and the slowing of the airflow forward, the bundle 6c bends and moves away from the central axis A. In other words, the section where the bundle 6c of long fibers 6b is arranged approximately parallel to the central axis A serves as a guide for the section where the resin is being drawn.

[0021] Furthermore, the fact that the resin (molten resin 6a or continuous 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 adhering particles after stretching has progressed to a certain extent, rather than before or during stretching. Therefore, it is also preferable to adhere particles at a position a certain distance from the nozzle head 3, as long as the self-adhesive properties are not lost.

[0022] 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. That is, it is preferable to set the predetermined position in a section where the resin is stretched, i.e., a section where the resin has fluidity, so that the powder particles 7 can easily adhere to the surfaces of the long fibers 6b. Furthermore, as described 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 within a range where it does not lose its adhesiveness due to its fluidity.

[0023] The predetermined position for supplying the powder particles 7 can be easily adjusted by providing the position control mechanism 5c. In the melt-blowing method, the length of the section Z varies depending on the type and temperature of the resin, the speed of the airflow, etc. It is preferable to provide the position control mechanism 5c in order to accommodate changes in the section Z due to such manufacturing conditions.

[0024] This produces a tangled long-fiber body 6 in which the powder particles 7 are composited onto the surfaces of the long fibers 6b stretched by the melt-blowing method. In particular, since 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 produced with high production efficiency. According to this method, the powder particles 7 are adhered 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 because it can impart high functionality to the tangled long-fiber body 6.

[0025] In addition, a step may be added in which a portion of the powder particles 7 that have not adhered to the long fibers 6b is removed 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 collecting net 11, or the collected tangled long-fiber body 6 may be sieved.

[0026] As shown in FIG. 5, a tangled long fiber body 6 made of long fibers of PP with a diameter of 20 microns or less and having a cotton-like appearance was obtained by the above manufacturing method.

[0027] Furthermore, as shown in Figure 6, it can be seen that powder particles 7 (here, white ceramic particles) are attached to the surface of the long fibers 6b at relatively narrow intervals. In particular, the powder particles 7 are hardly buried inside the long fibers 6b, but are attached so as to partially contact the long fibers 6b while leaving most of their surfaces exposed. In other words, it is thought that the use of powder particles 7 that exert their function by being exposed can impart particularly high functionality to the entangled long-fiber body 6. This state of attachment 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.

[0028] Although the embodiments of the present invention and modifications based thereon have been described above, the present invention is not necessarily limited to these examples. Furthermore, those skilled in the art will be able to find various alternative embodiments and modifications without departing from the spirit of the present invention or the scope of the appended claims. [Explanation of symbols]

[0029] 1. Extruder 2 screws 3 nozzle head 4. Airflow 5 Powder particle supply mechanism 6. Long fiber entanglement 6a Molten resin 6b Long Fiber 6c bundle A center axis Z interval

Claims

1. 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.

2. 2. The method for producing a particle-composite long-fiber entangled body according to claim 1, wherein the predetermined position is in a section where the thermoplastic resin or the long fibers made of the thermoplastic resin advances substantially parallel to the central axis of the airflow.

3. 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. 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.

5. 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 air flow.

6. 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 it 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.

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