JP5656297B2 - Centrifugal spinning apparatus and centrifugal spinning method - Google Patents

Description

  The present invention relates to a centrifugal spinning apparatus and a centrifugal spinning method related to centrifugal spinning of a thermoplastic resin having a mass concentration of 100% substantially using no solvent.

  Since it has been announced that garment materials and filter materials using nanofibers will exhibit new and useful functions, various proposals have been made on methods for producing nanofibers or applied products using nanofibers. Yes. In these proposals, the development of a method capable of mass-producing uniform nanofibers has become an important issue.

  Among the nanofiber production methods, the electrospinning method is a widely used nanofiber production method. This electrospinning method is a manufacturing method that skillfully utilizes the phenomenon that when a solution in which a polymer material is dissolved in a solvent is charged and released into an electric field, the polymer material is explosively stretched due to volatilization of the solvent. Patent Document 1 proposes a fiber manufacturing apparatus having a spray head provided with an extrusion element that rotates around a long axis and ejects a fiber constituent material into an electric field. This fiber manufacturing apparatus can form highly oriented nanofibers by utilizing the centrifugal force accompanying the rotation of the spray head.

  Patent Document 2 proposes an electrospinning device in which a strong electrostatic field is formed between an inclined surface and a collector facing the inclined surface, and the spinning solution is supplied in a thin film form on the inclined surface. ing. Since this electrospinning apparatus does not have many tapered nozzles that form a strong electric field, it is possible to suppress mutual interference between the strong electric fields of the nozzles, and an assembly of nanofibers having a form such as a nonwoven web It is said that the production efficiency can be dramatically improved.

  On the other hand, a nanofiber manufacturing method that does not use electrostatic force has been proposed. For example, Patent Document 3 discloses a fiber manufacturing method in which a resin solution stored in a rotating body is ejected from its ejection nozzle to perform centrifugal spinning, and the rotational speed of the rotating body is 10,000 to 25,000 rpm, and the pressure of the ejection nozzle portion is 10 to 10 There has been proposed a fiber manufacturing method in which spinning is performed by ejecting a resin solution having a viscosity of 50 to 200 Pa.s at 80 bar from an ejection nozzle. The resin solution used in the fiber manufacturing method is generally present in the form of an aqueous solution.

  Patent Document 4 discloses that a spinning solution in which at least one polymer is dissolved in at least one solvent at a temperature between about 100 ° C. and the freezing point of the solvent is spin with a rotational speed of about 4,000 to 100,000 rpm. A method of forming nanofibers has been proposed in which the surface is wetted from the center of the disk and diffused into a film shape and released from the peripheral portion, whereby the solvent is evaporated and fiberized. Since this nanofiber forming method uses a high-speed rotating spin disk, nanofibers and a uniform web can be produced at a high throughput.

Special Table 2007-532790 Publication JP 2011-162636 A JP-A-6-322606 Special table 2011-506797 gazette

  As shown in Patent Documents 1 to 4, electrostatic force and centrifugal force are effectively used in the production of nanofibers. The manufacturing method using electrostatic force proposed in Patent Document 1 or 2 can use a wide range of materials as a spinning solution for nanofibers, but requires an apparatus for forming an electric field, and is inherently There is a problem that a solvent is required. In addition, there is a problem that spinning is difficult in the case of a resin that cannot sufficiently utilize an electrostatic force because it is difficult to be charged. In particular, there is a problem that it is difficult to spin polyethylene resin, which is in great demand, and a desired nonwoven web cannot be obtained unless it is a special grade polyethylene resin with extremely high fluidity.

  On the other hand, the production method proposed in Patent Document 3 or 4 using centrifugal force requires a solvent for ensuring the viscosity or fluidity of the resin solution or spinning solution as described in those documents, and spinning. There is a problem that the possible materials are limited. In addition, polypropylene and polyethylene, which are in high demand, have a problem that it is not easy to develop a solvent suitable for spinning because of high solvent resistance.

  In addition, the manufacturing method proposed in Patent Document 1 or 3 has a problem that there are certain restrictions and limits on the number and arrangement of nozzles for ejecting or extracting the spinning solution. The problem of the number of nozzles and the arrangement of the nozzles may not only affect the productivity of nanofibers, but in order to reduce the fiber diameter, the nozzle hole diameter must be reduced, and the spinning device is complicated and expensive. Therefore, there is a problem that the maintainability is inferior and industrialization is not easy.

  In view of such conventional problems, the present invention relates to a nanofiber manufacturing method using centrifugal force, and with high production efficiency using various thermoplastic resins having a mass concentration of substantially 100% without using a solvent. An object of the present invention is to provide a centrifugal spinning apparatus and a centrifugal spinning method capable of producing nanofibers.

  The centrifugal spinning device according to the present invention includes a rotating body and a resin supply nozzle that supplies a molten resin from the rotation axis direction to the center of the upper surface of the rotating body, and the supplied molten resin is supplied to the rotating body. A centrifugal spinning device that produces fibers of fine diameter by diffusing to the upper surface and separating, stretching and flying from the periphery, wherein the rotating body has a guide rod extending from the center of the upper surface to the inside of the resin supply nozzle. Do it.

  In the above invention, the guide rod may have a concave portion and / or a convex portion on the surface portion.

As the molten resin, a thermoplastic resin having a mass concentration of 100% can be used. In addition, a molten resin having a shear rate of 1,000 s ^{-1 to} 100,000 s ^-1 and a viscosity of ¹ Pa.s to 100 Pa.s at the spinning temperature can be used.

  The rotating body preferably has a heating means capable of adjusting the temperature of the upper surface thereof, and is preferably provided with air blowing means for blowing normal temperature or heated gas to the molten resin that extends and flies from the upper surface of the rotating body. .

The centrifugal spinning method according to the present invention supplies a molten resin to the center of the upper surface of the rotating body, and diffuses the supplied molten resin to the upper surface of the rotating body to separate, stretch and fly from the periphery to produce fine fibers. The centrifugal spinning method is carried out by spinning in a molten resin having a shear rate of 1,000 s ^{-1 to} 100,000 s ^-1 and a viscosity of ¹ Pa.s to 100 Pa.s.

  Further, the centrifugal spinning method according to the present invention supplies molten resin from the resin supply nozzle to the center of the upper surface of the rotating body, diffuses the supplied molten resin to the upper surface of the rotating body, and disengages, stretches and flies from the periphery. This is a centrifugal spinning method for producing fine fibers by spinning while rotating a guide rod extending from the center of the upper surface of the rotating body to the inside of the resin supply nozzle.

  Further, the centrifugal spinning method according to the present invention supplies molten resin from the resin supply nozzle to the center of the upper surface of the rotating body, diffuses the supplied molten resin to the upper surface of the rotating body, and disengages, stretches and flies from the periphery. And spinning the guide rod extending from the center of the upper surface of the rotating body to the inside of the resin supply nozzle so as to satisfy the following expression (1). Implemented by doing. Centrifugal force acting on the molten resin <guide rod adhesion force due to the Weisenberg effect acting on the molten resin (1)

  According to the present invention, nanofibers can be produced with high production efficiency by using various thermoplastic resins having a mass concentration of 100% substantially without using a solvent.

It is a schematic diagram which shows the Example of the centrifugal spinning apparatus which concerns on this invention. It is a schematic diagram which shows the rotary body part of the centrifugal spinning apparatus which concerns on the other Example of this invention. It is a schematic diagram which shows the other Example of a guide bar. It is a graph which shows the relationship between the shear rate loaded on molten resin, and a viscosity. It is a SEM figure which shows the result of a present Example.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. An example of a centrifugal spinning device according to the present invention is shown in FIG. The centrifugal spinning device according to the present invention supplies a molten resin to the upper surface of the rotating body, diffuses the molten resin to the upper surface of the rotating body by centrifugal force, and separates, stretches, and flies from the periphery of the rotating body to manufacture fine fibers. This is a centrifugal spinning device of the type to be performed. That is, as shown in FIG. 1, the centrifugal spinning device 10 is configured such that the molten resin 50 supplied from the extruder 11 is supplied to the upper surface of the rotating body 20 through the resin supply nozzle 15. The rotating body 20 has a guide bar 22 extending inside the resin supply nozzle 15 at the center of the upper surface thereof, and is rotated together with the guide bar 22 by the driving means 25. Fine-diameter fibers formed by flying from the rotating body 20 are collected by the collection device 40.

  The rotating body 20 can be a disc-shaped member as shown in FIG. 1, but may be any member that has a circular plane portion on the upper surface to which the molten resin 50 is supplied. The rotating body 20 can be provided with grooves, protrusions, protrusions, and the like on the upper surface portion thereof. Further, the side surface of the rotator 20 is not smooth and can be, for example, a gear shape. If the side surface of the rotator 20 is made into a gear shape, the largest centrifugal force acts on the tip of the gear teeth, so that the molten resin can be selectively detached from the tip, extended and flying, and the fine nanofibers Easy to manufacture.

  The rotating body 20 is preferably configured so that the rotation speed can be controlled. Further, the rotating body 20 may be configured to be rotatable through a rotating shaft 26 integrated with the guide rod 22 as shown in FIG. 1, and is driven as shown in FIG. The means 25 may be directly connected to the rotating body 20 so as to be rotatable.

  The guide rod 22 only needs to extend from the center of the upper surface of the rotating body 20 into the resin supply nozzle 15 as described above. For example, the guide rod 22 can be configured to penetrate through the resin supply nozzle 15 as shown in FIG. 1 or to protrude from the center of the upper surface of the rotating body 20 as shown in FIG. . Further, the guide bar 22 may be a round bar shape having a chamfer 22a as shown in FIG. 2, or may have a concave portion and / or a convex portion on the surface thereof.

  The guide rod 22 preferably has a shape that can effectively apply a shearing force to the molten resin 50. For example, the guide bar 22 can be in the shape of a dull image, mudock or pin used for a screw such as an extruder. Moreover, the guide rod 22 having the shape 22b in which the spools shown in FIG. 3 are stacked can be used. The guide rod 22 is provided with one or more weirs (four weirs in this example) having a gap δ (for example, 0.5 mm or less) with the inner diameter of the resin supply nozzle 15.

  The means for supplying the molten resin 50 to the upper surface portion of the rotating body 20 may be an extruder 11 as shown in FIG. 1 or may be a form of pushing out with a piston 13 as shown in FIG. Any material that can supply the molten resin 50 may be used. And what can supply molten resin 50 to fixed quantity is good. By supplying a certain amount of molten resin, it becomes easy to produce nanofibers having a uniform diameter. The fixed amount of molten resin can be supplied by, for example, an extruder 11 or a gear pump provided between the piston 13 and the resin supply nozzle 15. It is preferable to provide a filter for removing unmelted resin mixed in the molten resin, or a trace amount of metal powder generated from the screw of the extruder 11, the piston 13, the resin supply nozzle 15, or the like.

  Further, as shown in FIG. 1, the centrifugal spinning device according to the present invention causes the heated gas to be ejected to the molten resin that diffuses to the upper surface of the rotating body 20 and separates, stretches, and flies from the periphery of the rotating body 20. Air blow means 33 can be provided. The air blowing means 33 preferably has a temperature control means capable of adjusting the gas temperature. As the heated gas, air is usually used, but air mixed with nitrogen gas or an inert gas such as nitrogen gas can be used.

  Further, a heating means 36 for heating the molten resin that diffuses the upper surface portion of the rotating body 20 can be provided. In the heating means 36, a sheathed heater or the like that can heat the rotating body 20 itself can be provided, and when an infrared heater or an electromagnetic induction heating heater is provided, the upper surface of the rotating body 20 is effectively heated without contact. be able to. Furthermore, it is preferable to provide temperature detection means such as a thermopile or an infrared thermo viewer. By these temperature detection means, the temperature of the rotating body 20, preferably the molten resin temperature of the upper surface of the rotating body 20, is measured, and the energization amount to the sheathed heater, infrared heater or electromagnetic induction heater based on the temperature data By automatically controlling the temperature, the temperature of the molten resin can be controlled to a desired temperature.

  Further, the centrifugal spinning apparatus according to the present invention can use various thermoplastic resins, and the thermoplastic resin does not require a solvent and can be spun even if it is a thermoplastic resin having a mass concentration of 100%. It can be carried out. According to the present invention, for example, polypropylene (PP), polyethylene (PE), polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyamide (PA), polylactic acid (PLLA), polyglycolic acid (PGA), polyphenylene Spinning of resins such as sulfide (PPS), polymethyl methacrylate (PMMA), polycarbonate (PC), cycloolefin polymer (COP), cycloolefin copolymer (COC) and the like can be performed. As described below, the present invention is characterized in that spinning is performed by adjusting the viscosity of the molten resin by adjusting the shear rate and the resin temperature. For this reason, according to this invention, even if it is a low flow or high flow grade resin, it can spin various resin, without being restrict | limited to the kind and grade of resin. The mass concentration of the thermoplastic resin is substantially 100%, which corresponds to a so-called 100% concentration by weight, and includes a case where a commonly used additive or the like is contained.

The centrifugal spinning device according to the present invention performs spinning at a spinning temperature in a range of 1,000 s ^{-1 to} 100,000 s ^-1 and a viscosity of ¹ Pa.s to 100 Pa.s (region A shown in FIG. 4). Can do. That is, according to the present invention, by rotating the guide rod 22 inside the resin supply nozzle 15 to which the molten resin 50 is supplied, a shearing force is applied to the molten resin to exponentially decrease the viscosity of the molten resin. it can. Moreover, shear heat generation can be generated by the action of the shear force, and the viscosity of the molten resin can be further reduced by the shear heat generation. Shear heat generation is preferable because it is diffused into the molten resin by heat conduction and can reduce the viscosity of a wide range of molten resin. For this reason, it is possible to perform spinning even with a thermoplastic resin having a small MFR value and low fluidity, which has been difficult to produce a nanofiber nonwoven fabric by the conventional production method. FIG. 4 is obtained by processing a known figure (Plastics Vol. 52, No. 9, P99, FIG. 9). In FIG. 4, the horizontal axis indicates the shear rate of the molten resin, and the vertical axis indicates the viscosity of the molten resin.

  In the present invention, since a thermoplastic resin having a mass concentration of 100% is used substantially without using a solvent, the Weisenberg effect can be produced in the molten resin. That is, as shown in FIG. 2, the Weisenberg effect can be generated in the molten resin 50 existing inside the resin supply nozzle 15 by rotating the guide rod 22. Due to the Weisenberg effect, the molten resin 50 flowing inside the resin supply nozzle 15 is pushed down toward the rotating body 20 by the molten resin 50 flowing in from the upstream while being wound around the guide rod 22, so that the molten resin 50 becomes a resin. It will not adhere to the tip of the supply nozzle 15. Then, the molten resin 50 that has reached the upper surface of the rotating plate 20 diffuses so as to spread over the upper surface of the rotating body 20.

  The Weisenberg effect generates a force that causes the molten resin 50 to be wound around and adhered to the guide rod 22. It is preferable that the force for winding the molten resin 50 around the guide rod 22 is larger than the centrifugal force acting on the molten resin 50, that is, the force for pulling the molten resin 50 away from the guide rod 22. This is because the following problems arise when the guide rod adhesion force acting on the molten resin 50 is smaller than the centrifugal force acting on the molten resin 50. That is, the molten resin 50 discharged from the resin supply nozzle 15 adheres to the tip of the resin supply nozzle 15 by centrifugal force immediately after discharge. Then, since the centrifugal force by the rotating body 20 does not act on the adhered molten resin, a resin pool is formed at the adhered portion. This resin pool has a problem that the molten resin continues to adhere one after another and becomes gradually larger, and finally it becomes difficult to perform spinning.

  Using a centrifugal spinning device having the configuration shown in FIG. 2, a test was conducted to produce a nonwoven fabric by spinning polypropylene. This centrifugal spinning device has a resin supply nozzle with an inner diameter of 5 mm, a circular guide rod with an outer diameter of 4 mm and a length of 10 mm, a spur gear-shaped rotating body with an outer diameter of 28 mm, an air blowing means with a temperature of 380 ° C. and an air blowing rate of 20 l / min. And heating means comprising an infrared lamp. Polypropylene had a homopolymer (homopolymer) composition and a melt flow rate (JISK7210) MFR = 9 g / 10 min.

  The test conditions were a spinning temperature of 280 ° C., a guide rod speed of 20,000 rpm, an infrared lamp output of 150 W, and an air blowing means air temperature of 380 ° C. This test condition corresponded to the condition of point P in FIG. The SEM image of the produced nonwoven fabric is shown in FIG. As can be seen from FIG. 5, this nonwoven fabric is composed of relatively uniform fibers having an outer diameter of micron-submicron.

10 Centrifugal spinning device
11 Extruder
13 Piston
15 Resin supply nozzle
20 Rotating body
22 Guide bar
25 Drive means
26 Rotation axis
33 Air blow means
36 Heating means
40 Collector
50 Molten resin

Claims (8)

It has a rotating body and a resin supply nozzle that supplies molten resin to the center of the upper surface of the rotating body from the direction of the rotation axis. The supplied molten resin is diffused to the upper surface of the rotating body and detached from the periphery. And a centrifugal spinning device for producing fine fibers by flying,
The molten resin has a shear rate of 1,000 s ^{-1 to} 100,000 s ^-1 and a viscosity of ¹ Pa.s to 100 Pa.s at the spinning temperature ,
The rotary spinning device is a centrifugal spinning device having a guide rod extending from the center of the upper surface into the resin supply nozzle.   The centrifugal spinning device according to claim 1, wherein the guide rod has a concave portion and / or a convex portion on a surface portion.   The centrifugal spinning apparatus according to claim 1 or 2, wherein the molten resin is a thermoplastic resin having a mass concentration of 100%. The centrifugal spinning device according to any one of claims 1 to 3 , further comprising heating means capable of adjusting a temperature of an upper surface of the rotating body. The centrifugal spinning device according to any one of claims 1 to 4 , further comprising air blowing means for blowing a normal temperature or heated gas to a molten resin that extends and flies from the upper surface of the rotating body. A centrifugal spinning method for producing fine fibers by supplying a molten resin to the center of the upper surface of the rotating body, diffusing the supplied molten resin to the upper surface of the rotating body, separating from the peripheral edge, stretching and flying,
A centrifugal spinning method in which spinning is performed in a molten resin having a shear rate of 1,000 s ^{-1 to} 100,000 s ^-1 and a viscosity of ¹ Pa.s to 100 Pa.s. Centrifugal spinning method in which a molten resin is supplied from the resin supply nozzle to the center of the upper surface of the rotating body, and the supplied molten resin is diffused to the upper surface of the rotating body to be separated from the peripheral edge, stretched, and fly to produce fine fibers. Because
The molten resin has a shear rate of 1,000 s ^{-1 to} 100,000 s ^-1 and a viscosity of ¹ Pa.s to 100 Pa.s at the spinning temperature ,
A centrifugal spinning method in which spinning is performed while rotating a guide rod extending from the center of the upper surface of the rotating body into the resin supply nozzle. Centrifugal spinning method in which a molten resin is supplied from the resin supply nozzle to the center of the upper surface of the rotating body, and the supplied molten resin is diffused to the upper surface of the rotating body to be separated from the peripheral edge, stretched, and fly to produce fine fibers. Because
The molten resin has a shear rate of 1,000 s ^{-1 to} 100,000 s ^-1 and a viscosity of ¹ Pa.s to 100 Pa.s at the spinning temperature ,
A centrifugal spinning method in which spinning is performed by rotating a guide rod extending from the center of the upper surface of the rotating body into the resin supply nozzle so as to satisfy the following expression (1).
Centrifugal force acting on the molten resin <guide rod adhesion force due to the Weisenberg effect acting on the molten resin (1)

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