JP2012224958A - Method for producing fine fiber and apparatus for producing fine fiber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrospinning method and apparatus capable of continuously and stably operating for a long period of time, and efficiently producing a high-quality fine fiber at a low cost.SOLUTION: This apparatus for producing the fine fiber comprises: a storage tank 2 in which a liquid polymer P is stored; vibration generation means 3 for applying vibration to the liquid polymer P in the storage tank 2; a counter electrode 4 that is arranged at an upper position of a liquid level 10 of the liquid polymer P in the storage tank 2 so as to face the liquid level 10; and voltage supply means 5 for applying high voltage between the liquid polymer P and the counter electrode 4. The apparatus applies the vibration to the liquid polymer by using the vibration generation means to form a surface wave in the liquid level of the liquid polymer, and also makes jets of a polymer fiber fly toward the electrode from each peak of the surface waves of the liquid polymer by applying high voltage.

Description

  The present invention relates to an electrostatic spinning method (electrospinning) in which a polymer fiber jet is made to fly from a polymer surface by a high voltage applied between a polymer solution or a molten polymer (hereinafter referred to as “liquid polymer”) and an electrode. In particular, the present invention relates to a fine fiber production method and production apparatus suitable for producing nanofibers.

  The conventional electrospinning method uses the fact that a single jet flies between a nozzle from which a liquid polymer flows and an electrode facing the nozzle, thereby obtaining a fine fiber assembly in which fine fibers are accumulated. It is. And in order to raise productivity, many injection needle-shaped nozzles, such as 0.1-0.2 mm, are arranged. However, in practice, the number of nozzles arranged is limited, and only limited productivity can be obtained. In addition, in such a needle-like nozzle, there still remains a problem that hinders improvement in productivity such as nozzle clogging due to foreign matter in the liquid polymer and solidification of the liquid polymer at the tip of the nozzle.

  On the other hand, an elongated rotating spinning electrode is provided in a partially immersed state in a liquid polymer storage tank, a fiber collecting electrode is installed opposite to the rotating spinning electrode, and the rotating spinning electrode is rotated so that the liquid polymer is on the surface. A method has been proposed in which a fine fiber assembly is obtained by forming and adhering fibers to the collecting electrode by applying a high voltage between both electrodes and applying a high voltage between the electrodes to the collection electrode. (For example, refer to Patent Document 1). Here, it has also been proposed to provide a large number of protrusions on the surface of the rotary spinning electrode in order to facilitate the flight of the fiber jet. In addition, the surface of the polymer is raised by embedding a device that generates bubbles in the polymer reservoir layer to which a high voltage is applied, and a ground electrode is provided facing the liquid surface of the reservoir layer, and a polymer fiber jet is formed from the polymer foam surface. There has also been proposed a method for producing a fine fiber assembly in which the fibers are allowed to fly and accumulate (see, for example, Patent Document 2).

  However, the method using the rotating electrode as in Patent Document 1 has a certain effect in terms of increasing the flying polymer fiber jet and improving the productivity, but the polymer fiber jet does not fly from the entire rotating electrode, The flight is from only the range closest to the counter electrode, and there is a limit to improving the productivity per set. Moreover, in the method as disclosed in Patent Document 2, when a bubble is generated on the polymer liquid surface and a jet is caused to fly from the apex of the bubble, there is a problem that fine flying powder due to bursting of the bubbles fly and adheres to the fiber surface. .

Special table 2009-538992 Japanese Patent No. 3918179

  Therefore, in view of the above-mentioned situation, the present invention intends to solve the problems of these known techniques and provide a highly productive electrospinning method and apparatus capable of stably forming fine fibers. There is in point to do.

  In order to solve the above-mentioned problems, the present invention provides a fine fiber production method in which a high voltage is applied between a liquid polymer and an electrode, and the liquid polymer is made to fly as a polymer fiber jet toward the electrode to form a fiber. A fine structure characterized by applying vibration to a liquid polymer, forming a surface wave due to the vibration on a liquid surface of the liquid polymer, and causing a polymer fiber jet to fly from the peak of the surface wave toward the electrode with a high voltage. A fiber manufacturing method is provided.

  Here, the surface wave formed on the liquid polymer liquid surface by the vibration is preferably a standing wave.

  The vibration is preferably ultrasonic vibration.

  Further, the present invention is arranged in a storage tank in which the liquid polymer is stored, vibration generating means for applying vibration to the liquid polymer in the storage tank, and an upper position facing the liquid surface of the liquid polymer in the storage tank. An electrode, and a voltage supply unit that applies a high voltage between the liquid polymer and the electrode, and the vibration generating unit vibrates the liquid polymer to form a surface wave on the liquid polymer liquid surface, and the voltage There is also provided a fine fiber manufacturing apparatus characterized in that a polymer fiber jet is caused to fly from a peak portion of a surface wave of the liquid polymer toward an electrode by the high voltage by a supply means, and fiberized.

  According to the fine fiber manufacturing method and the fine fiber manufacturing apparatus according to the present invention, the liquid polymer is vibrated, a surface wave is formed by the vibration on the liquid surface of the liquid polymer, and the surface wave is applied to the electrode from the peak. Since the polymer fiber jet is caused to fly at a high voltage, it can be operated without using a nozzle and can operate stably continuously for a long period of time without problems such as blocking of nozzle holes. Further, since the polymer fiber jets fly from the entire surface of the liquid without using nozzles or rotating electrodes that limit productivity, the polymer fiber jets can be generated very efficiently and at low cost. In addition, the problem of bubble bursting, which is a quality problem, can be avoided, and high-quality fine fibers can be produced efficiently and at low cost.

  In addition, since the surface wave formed on the liquid polymer liquid surface by vibration is a standing wave, the polymer fiber jet can stably fly from the standing wave on the liquid surface, producing higher quality fine fibers. it can.

  This electrostatic spinning is a phenomenon in which the polymer fiber jet is drawn when the electrostatic force overcomes the surface tension of the polymer liquid surface. Therefore, the lower the surface tension of the polymer, the easier the fibers are generated. When the vibration is an ultrasonic vibration, the ultrasonic wave has an action of reducing the surface tension, and can further increase the productivity of the fiber.

  A storage tank in which the liquid polymer is stored; vibration generating means for applying vibration to the liquid polymer in the storage tank; an electrode disposed at an upper position facing the liquid surface of the liquid polymer in the storage tank; Voltage supply means for applying a high voltage between the liquid polymer and the electrode, and the vibration generating means vibrates the liquid polymer to form a surface wave on the liquid polymer liquid surface, and the voltage supply means Since the high-voltage is used to form a fiber by jetting a polymer fiber jet from the peak of the surface wave of the liquid polymer toward the electrode, the liquid level of the liquid polymer is closed by the wall of the storage tank. The surface wave generated on the liquid surface by the vibration generating means can be freely controlled.

  Further, when the vibration generating means is composed of a vibration oscillator fixed to the side wall portion of the storage tank, a stable standing wave may be formed depending on the wavelength of vibration and the distance between the vibration oscillator and the opposite side wall. Easy.

Explanatory drawing which shows the fine fiber manufacturing apparatus which concerns on typical embodiment of this invention. AA sectional drawing of FIG. Explanatory drawing of the principal part which similarly shows the modification of a fine fiber manufacturing apparatus.

  Next, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

  As shown in FIG. 1, a fine fiber manufacturing apparatus 1 according to the present invention includes a storage tank 2 in which a liquid polymer P is stored, a vibration generating means 3 that vibrates the liquid polymer P in the storage tank 2, and a storage tank. 2 is provided with a counter electrode 4 disposed at an upper position facing the liquid surface 10 of the liquid polymer P in the line 2 and a voltage supply means 5 for applying a high voltage between the liquid polymer P and the counter electrode 4.

  In this example, as shown in FIG. 2, a conveyor net 6 that runs in the lateral direction is provided between the liquid polymer P liquid level 10 and the counter electrode 4, and polymer fiber jets J are sequentially accumulated on the lower surface of the conveyor net 6. Is configured to do. Although the counter electrode 4 is fixed, the stacking means itself such as the conveyor net 6 may also serve as the counter electrode. The counter electrode 4 is preferably a plate-like electrode parallel to the liquid surface 10 of the liquid polymer P, but is not limited thereto. Moreover, although it has the lower surface of substantially the same area as the liquid level 10 and each polymer fiber jet J is made to fly straight upwards, it is good also as an area mutually different.

  As shown in FIGS. 1 and 2, the vibration generating means 3 includes a vibration oscillator 31 fixed to the side wall 20 of the storage tank 2 and a vibration oscillator 30 that transmits an oscillation signal to the vibration oscillator 31. In addition, the vibration intensity of the vibration oscillator 31 can be continuously adjusted by the vibration oscillator 30. In addition to the side wall 20 of the storage tank 2, the vibration oscillator 31 can be installed at an appropriate location such as the bottom wall or the center. The vibration oscillator and the vibration oscillator are preferably an ultrasonic oscillator and an ultrasonic oscillator, respectively.

  When vibration is applied to the liquid polymer P by the vibration generating means 3, a surface wave 11 is formed on the liquid polymer liquid surface 10. As the amplitude of the vibration increases, the peaks and valleys of the surface wave 11 also increase. When this amplitude is increased and a critical point is reached, the surface wave 11 collapses from the top of the mountain, and fine liquid particles fly off the liquid surface. Preferably, the vibration is adjusted so as to approach a state immediately before reaching such a critical point. More preferably, the surface wave formed on the liquid polymer liquid surface 10 by vibration is preferably adjusted to be a standing wave. When the vibration oscillator is an ultrasonic vibration oscillator, frequency-specific capillary waves (capillary surface waves) and cavitation (cavity phenomenon) are generated on the polymer liquid surface and inside the liquid. Capillary surface waves are generated and the surface tension of the liquid is reduced, so that the polymer fiber jet is more likely to fly.

  Here, as shown in FIG. 3, by providing a vibration oscillator 31 on each of two adjacent side walls that form 90 degrees with each other in the rectangular storage tank 2 as viewed from above, more waves arranged in the vertical and horizontal directions can be obtained. In particular, a standing wave having a lattice shape as shown in the figure can be formed by using a standing wave.

  As the voltage supply means 5, as shown in FIG. 1, a ground electrode 50 is installed at the bottom of the storage tank 2, and a power supply device 51 for applying a high voltage is provided between the ground electrode 50 and the counter electrode 4. Yes. Here, the ground electrode 50 may be omitted, and the wall of the storage tank 2 may be configured to also serve as the ground electrode.

  When a high voltage is applied between the ground electrode 50 and the counter electrode 4 by the voltage supply means 5 in a state where the surface wave 11 is formed on the liquid polymer liquid surface 10 by the vibration generating means 3, FIG. As shown in FIG. 2, the polymer fiber jets J fly from the summits of the surface waves 11 toward the counter electrode 4, and the mist rises from the liquid polymer liquid surface as if the polymer fiber jets J were many. The polymer fiber jets J are sequentially accumulated on the lower surface of the conveyor net 6 in the middle in a fiberized state.

  The conveyor net 6 is a net-like annular belt suspended between the driving roller 60 and the driven roller 61. In this example, the conveyor net 6 circulates so as to sandwich the counter electrode 4 vertically, A fine fiber assembly F in which polymer fiber jets J are accumulated is formed on the lower surface of the net that runs in the horizontal direction between the counter electrodes 4, and the fine fiber assembly F is placed on the extension line of the drive roller 60 in the horizontal direction. A take-up device 7 is provided which is peeled off from the lower surface of the net 6 in the lateral direction on the extension and wound up.

  The conveyor net 6 travels at a constant speed, and a fine fiber aggregate F having a constant thickness is formed on the lower surface of the conveyor net 6 by the fiberized polymer fiber jet J. The conveyor net 6 is configured to move in the horizontal direction parallel to the liquid polymer liquid level 10 and the counter electrode 4, but is not limited thereto.

  Although the embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and can of course be implemented in various forms without departing from the gist of the present invention.

DESCRIPTION OF SYMBOLS 1 Fine fiber manufacturing apparatus 2 Storage tank 3 Vibration generating means 4 Counter electrode 5 Voltage supply means 6 Conveyor net 7 Winding device 10 Liquid surface 11 Surface wave 20 Side wall part 30 Vibration oscillator 31 Vibration oscillator 50 Ground electrode 51 Feeding device 60 Drive Roller 61 Followed roller F Fine fiber assembly J Polymer fiber jet P Liquid polymer

Claims (4)

In a fine fiber manufacturing method in which a high voltage is applied between a liquid polymer and an electrode, and the liquid polymer is made to fly as a polymer fiber jet toward the electrode to be fiberized,
Vibrating the liquid polymer, forming a surface wave due to the vibration on the liquid surface of the liquid polymer,
A method for producing fine fibers, characterized in that a polymer fiber jet is caused to fly at a high voltage from the top of the surface wave toward the electrode.   The method for producing fine fibers according to claim 1, wherein a surface wave formed on the liquid polymer liquid surface by the vibration is a standing wave.   The fine fiber manufacturing method according to claim 1, wherein the vibration is ultrasonic vibration. A storage tank in which the liquid polymer is stored;
Vibration generating means for applying vibration to the liquid polymer in the storage tank;
An electrode disposed at an upper position facing the liquid surface of the liquid polymer in the storage tank;
Voltage supply means for applying a high voltage between the liquid polymer and the electrode;
With
A vibration is applied to the liquid polymer by the vibration generating means to form a surface wave on the liquid polymer liquid surface, and the high voltage from the voltage supply means causes the polymer from the peak of the surface wave of the liquid polymer to the electrode. An apparatus for producing fine fibers, wherein a fiber jet is made to fly to form fibers.

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