JP7076734B2 - Nanofiber manufacturing equipment and nanofiber manufacturing method - Google Patents

Description

The present invention relates to a nanofiber manufacturing apparatus and a method for manufacturing nanofibers.

In recent years, attention has been focused on nanofibers, which are nanoscale ultrafine fibers. In general, a thread or cloth made of nanofibers has a large specific surface area, a high void ratio, and fine pores (pores) as compared with a thread or cloth made of microfibers (ordinary fibers). It has features such as being able to be formed thin and having a smooth feel.
For this reason, nanofibers can be applied to a very wide range of fields such as moisture permeable waterproof films, high-performance filters, secondary battery separators, electrodes, supercapsules, solar cells, clean room wipers, dustproof clothing, masks, and artificial muscles. Is expected, and research is being actively conducted.

The term "nanofiber" as used herein refers to a fiber having a fiber diameter of 3000 nm or less (preferably 1000 nm or less) and an average diameter of 1000 nm or less (preferably 500 nm or less). Further, the nanofiber may contain a substance (for example, carbon nanotube or metal nanoparticles) other than the substance (polymer) constituting the fiber body inside or outside the fiber.

Conventionally, as a method for producing nanofibers made of a polymer, a production method using a melt spinning method (melt blow method) or an electrospinning method (electrospinning method), and a production apparatus used for these production methods are known (for example). , Patent Documents 1 to 3).
In the melt spinning method, nanofibers are formed by discharging a polymer melted from a thin nozzle together with a high temperature air flow. Further, in the electric field spinning method, nanofibers are formed by discharging a raw material solution in which a polymer is dissolved in a solvent in a state where a high voltage is applied between a nozzle and a collector from the nozzle.

According to the conventional method for producing nanofibers, it becomes possible to produce nanofibers which are nanoscale fibers.

U.S. Pat. No. 6114017 U.S. Pat. No. 6,673,136 International Publication No. WO2009 / 034765

By the way, in the method for producing nanofibers using the melt spinning method or the electric field spinning method, the nanofibers are produced in the state of a non-woven fabric. When the nanofiber is used as a non-woven fabric (for example, when it is used as a filter), the above method can be preferably used. On the other hand, when it is desired to give the nanofibers orientation (the property that the directions of the fibers are aligned in a certain direction) (for example, when tensile strength in a certain direction is required or when the nanofibers are used as electrical wiring), There is a problem that the conventional manufacturing method and the nanofiber manufacturing apparatus used in the conventional manufacturing method are inconvenient.

Therefore, the present invention has been made to solve the above problems, and an object of the present invention is to provide a nanofiber manufacturing apparatus capable of manufacturing nanofibers in a state of having orientation. Another object of the present invention is to provide a method for producing nanofibers capable of producing nanofibers in a state of having orientation.

[1] The nanofiber manufacturing apparatus of the present invention comprises a solution arranging member capable of arranging a raw material solution which is a raw material of nanofibers, and when the raw material solution is arranged on the solution arranging member, the raw material solution comes into contact with the raw material solution. It is characterized by including a moving member that can move at least one-dimensionally so that the raw material solution can be stretched to form the nanofibers by moving in a direction away from the solution arranging member.

[2] In the nanofiber manufacturing apparatus of the present invention, the moving member is preferably a needle-shaped member having a sharp end on the side to be in contact with the raw material solution.

[3] In the nanofiber manufacturing apparatus of the present invention, it is preferable that the thickness of the portion of the moving member in contact with the raw material solution is 5 mm or less.

[4] In the nanofiber manufacturing apparatus of the present invention, it is preferable to further include a moving mechanism capable of repeatedly moving the moving member at a predetermined speed.

[5] In the method for producing nanofibers of the present invention, a contact step of preparing a raw material solution which is a raw material of nanofibers and bringing the raw material solution into contact with a moving member, and a direction in which the moving member moves away from the raw material solution. It is characterized by including a nanofiber forming step of moving and stretching the raw material solution to form the nanofibers.

[6] In the method for producing nanofibers of the present invention, it is preferable to use as the moving member a needle-shaped member having a sharp end on the side to be in contact with the raw material solution.

[7] In the method for producing nanofibers of the present invention, it is preferable to use a moving member having a thickness of a portion of the moving member in contact with the raw material solution of 5 mm or less.

[8] In the method for producing nanofibers of the present invention, it is preferable to repeat the contact step and the nanofiber forming step a plurality of times, and then recover the nanofibers.

Since the nanofiber manufacturing apparatus of the present invention includes a solution arranging member capable of arranging a raw material solution which is a raw material of nanofibers and a moving member which can move at least one-dimensionally, as shown in Examples described later. It is a nanofiber manufacturing apparatus capable of manufacturing nanofibers in a state of having orientation.

In the method for producing nanofibers of the present invention, a raw material solution as a raw material for nanofibers is prepared, and a contact step of bringing the raw material solution into contact with a moving member and a moving member to move the moving member away from the raw material solution to prepare the raw material solution. Since it includes a nanofiber forming step of stretching to form nanofibers, it is a method for producing nanofibers capable of producing nanofibers in a state of orientation, as shown in Examples described later.

It is a figure which shows for demonstrating the nanofiber manufacturing apparatus 1 which concerns on embodiment. It is a figure which shows for demonstrating the manufacturing method of the nanofiber which concerns on embodiment. It is a photograph shown for demonstrating the nanofiber manufacturing apparatus which concerns on Example. It is a photograph showing the state of collecting the manufactured nanofibers. It is a SEM (scanning electron microscope) image shown for demonstrating the orientation of the nanofibers manufactured by the nanofiber manufacturing apparatus which concerns on Example. 6 is an SEM image of nanofibers in an example when a needle-shaped member having a thickness of 0.12 mm is used. 6 is an SEM image of nanofibers in an example when a needle-shaped member having a thickness of 0.5 mm is used. 6 is an SEM image of nanofibers in an example when a needle-shaped member having a thickness of 1.02 mm is used. 6 is a graph showing the relationship between the concentration of polyethylene oxide in the raw material solution and the fiber diameter of the produced nanofibers in the embodiment for each thickness of the needle-shaped member. 6 is an SEM image shown to illustrate the effect of the stretching rate of the raw material solution in the examples. 6 is an SEM image shown to explain the effect of the stretching distance of the raw material solution in the examples. It is a graph which shows the Raman spectrum of the nanofiber in an Example. 6 is a TEM (transmission electron microscope) image showing the state of nanofibers containing carbon nanotubes in an example. It is a graph which shows the strain-stress curve of the nanofiber in an Example.

Hereinafter, the nanofiber manufacturing apparatus and the nanofiber manufacturing method according to the present invention will be described based on the embodiments. It should be noted that not all of the elements and combinations thereof described in the embodiments are indispensable for the means for solving the present invention.

1. 1. Nanofiber manufacturing apparatus 1 according to an embodiment
FIG. 1 is a diagram for explaining the nanofiber manufacturing apparatus 1 according to the embodiment. FIG. 1A is a front view of the nanofiber manufacturing apparatus 1, and FIG. 1B is a top view (plan view) of the nanofiber manufacturing apparatus 1. The "front view" and "top view (plan view)" are for convenience of explanation, and do not specify the installation direction of the nanofiber manufacturing apparatus 1.

As shown in FIG. 1, the nanofiber manufacturing apparatus 1 according to the embodiment includes a solution arrangement member 10, a moving member 20, a connecting member 30, a moving mechanism 40, a guide member 50, and a base 60. ..

The solution arranging member 10 is a member capable of arranging (holding) a raw material solution which is a raw material of nanofibers. In the embodiment, the solution arranging member 10 has a solution container 12, and when producing nanofibers, the raw material solution is arranged in the solution container 12.
The arrangement of the raw material solution may be carried out by, for example, a human being, or may be carried out by a dedicated device or instrument. The timing of arranging the raw material solution may be determined by a human being each time, or may be automatically performed by a mechanical mechanism or the like.

The moving member 20 is a member capable of forming nanofibers by stretching the raw material solution by moving in a direction away from the solution arranging member 10 after contacting with the raw material solution when the raw material solution is placed on the solution arranging member 10. .. The moving member 20 is movable at least one-dimensionally.
In the embodiment, the nanofiber manufacturing apparatus 1 includes four moving members arranged in a straight line.

The moving member 20 is a needle-shaped member having a sharp end on the side to be in contact with the raw material solution.
The thickness of the portion of the moving member 20 that comes into contact with the raw material solution is 5 mm or less. The thickness is more preferably 2 mm or less.
"The thickness of the portion in contact with the raw material solution is 5 mm or less" means that "when the portion of the moving member in contact with the raw material solution is viewed in a cross section perpendicular to the axial direction of the moving member, the cross section has a diameter of 5 mm. It fits within the circular range of. "

Although there is no lower limit to the thickness of the moving member 20 conceptually, it is preferable that the thickness is 0.05 mm or more in consideration of the strength of the moving member 20 when actually forming nanofibers. Be done.

As used herein, the term "needle-shaped member" refers to a rod-shaped member having at least one end sharpened. As the needle-shaped member, a widely commercially available needle such as a sewing needle or a needle for acupuncture treatment can be used, or a dedicated one designed for a nanofiber manufacturing apparatus can be used.
The inventors of the present invention refer to a nanofiber manufacturing apparatus using a needle-shaped member as in the nanofiber manufacturing apparatus 1 according to the embodiment as a "needle spinning apparatus (NS apparatus)".

The connecting member 30 is a member that connects the moving member 20 and the moving mechanism 40. In the embodiment, the moving member 20 is arranged on the connecting member 30.
The moving mechanism 40 is a mechanism capable of repeatedly moving the moving member 20 at a predetermined speed. The moving mechanism 40 in the embodiment indirectly moves the moving member 20 by directly moving the connecting member 30. In the moving mechanism 40, for example, an electric motor, an air cylinder, an elastic member (spring or the like) can be used as the power for moving the moving member 20.

The guide member 50 is a member arranged on the side of the connecting member 30 opposite to the moving mechanism 40 side. The guide member 50 is a rod-shaped member, and is connected to the side of the connecting member 30 opposite to the moving mechanism 40 side so that the connecting member 30 can slide and move according to the movement of the connecting member 30.
The base 60 is a member that supports each of the above-mentioned components.

2. 2. Method for manufacturing nanofibers according to an embodiment FIG. 2 is a diagram shown for explaining a method for manufacturing nanofibers according to an embodiment. 2 (a) to 2 (c) are process diagrams.

The method for producing nanofibers according to the embodiment includes a contact step S1 and a nanofiber forming step S2.
The nanofiber manufacturing method according to the embodiment is a manufacturing method carried out using the nanofiber manufacturing apparatus 1 according to the embodiment.
Therefore, the method for producing nanofibers according to the embodiment is a method in which a needle-shaped member having a sharp end on the side to be in contact with the raw material solution S (described later) is used as the moving member 20.
Further, the method for producing nanofibers according to the embodiment is a method in which a moving member 20 having a thickness of a portion of the moving member 20 in contact with the raw material solution S having a thickness of 5 mm or less is used.
The inventors of the present invention refer to a method for producing nanofibers using a needle-like member as in the method for producing nanofibers according to an embodiment as a "needle spinning method (NS method)".

In the contact step S1, a raw material solution S, which is a raw material for nanofibers, is prepared (see FIG. 2A), and the raw material solution S is brought into contact with the moving member 20 which can move at least one-dimensionally (FIG. 2 (FIG. 2). b) See.) Step.
The raw material solution is a solution obtained by adding a solvent to the polymer constituting the nanofiber. As the polymer, various polymers can be used as long as they are soluble in the solvent.
The raw material solution is preferably viscous to some extent for the convenience of directly stretching from the raw material solution to form nanofibers. The amount and type of the polymer and the solvent for preparing the raw material solution can be appropriately determined according to the physical properties of the nanofibers to be produced and the like.

In addition, the raw material solution contains substances for improving or adjusting the properties of the nanofibers to be produced (for example, carbon-based substances having a nanoscale structure, metal particles as catalysts and bactericides, etc.). You may. In particular, in the method for producing nanofibers according to the embodiment, since the nanofibers are formed by directly stretching from the raw material solution, it is easy to contain a large amount of substances contained in the nanofibers, and it is in the form of fibers such as carbon nanotubes. Especially suitable for producing nanofibers containing the above substances.
Further, the raw material solution may contain a substance (for example, a surfactant or a thickener) for adjusting the properties of the raw material solution such as viscosity and surface tension.

In the embodiment, after the raw material solution S is placed in the solution container 12 of the solution arranging member 10, the moving member 20 is brought closer to the solution arranging member 10 by the moving mechanism 40, and the raw material solution S and the moving member 20 are brought into contact with each other.

The nanofiber forming step S2 is a step of moving the moving member 20 in a direction away from the raw material solution S and stretching the raw material solution S to form the nanofiber F (see FIG. 2C).

The nanofiber F formed as described above can be recovered in a state of having orientation by pressing a frame-shaped or plate-shaped member from a direction orthogonal to the stretching direction of the fiber, for example.

In the method for producing nanofibers according to the embodiment, the contact step S1 and the nanofiber forming step S2 may be performed only once each, but from the viewpoint of obtaining a large amount of nanofibers, the contact step S1 It is preferable to repeat the nanofiber forming step S2 a plurality of times in this order.
When the contact step S1 and the nanofiber forming step S2 are repeated a plurality of times, the manufactured nanofiber F may be recovered every time the nanofiber forming step S2 is completed, or the contact step S1 and the nanofiber forming step S2 may be recovered. May be repeated a plurality of times (arbitrarily many times). When the purpose is to obtain a large amount of nanofiber F, it is preferable to recover the nanofiber F after repeating the contact step S1 and the nanofiber forming step S2 a plurality of times.

3. 3. Effects of the nanofiber manufacturing method and the nanofiber manufacturing method according to the embodiment The effects of the nanofiber manufacturing method and the nanofiber manufacturing method according to the embodiment will be described below.

The nanofiber manufacturing apparatus 1 according to the embodiment includes a solution arranging member 10 capable of arranging a raw material solution which is a raw material of nanofibers, and a moving member 20 which can move at least one-dimensionally. As shown, it is a nanofiber manufacturing apparatus capable of manufacturing nanofibers in a state of having orientation.

Further, according to the nanofiber manufacturing apparatus 1 according to the embodiment, since the nanofibers can be formed by stretching the raw material solution by the moving member 20, a mechanism for generating a high temperature airflow and a high voltage are applied. It is possible to manufacture nanofibers with a simple structure without using the mechanism of.

Further, according to the nanofiber manufacturing apparatus 1 according to the embodiment, since the nanofibers can be formed by directly stretching the raw material solution by the moving member 20, the nanofibers for carrying out the melt spinning method and the electric field spinning method. Compared to manufacturing equipment, nanofibers can contain a large amount of various substances.

Further, according to the nanofiber manufacturing apparatus 1 according to the embodiment, since the moving member 20 is a needle-shaped member having a sharp end on the side to be in contact with the raw material solution, the moving member 20 has a sharp and thin end. It is possible to stably produce nanofibers with a small fiber diameter.

Further, according to the nanofiber manufacturing apparatus 1 according to the embodiment, since the thickness of the portion of the moving member 20 in contact with the raw material solution is 5 mm or less, it is sufficient to make the moving member 20 (needle-shaped member) sufficiently thin. It is possible to manufacture fine nanofibers.

Further, according to the nanofiber manufacturing apparatus 1 according to the embodiment, since the moving mechanism 40 capable of repeatedly moving the moving member 20 at a predetermined speed is provided, as compared with the case where the moving member 20 is manually moved. , It becomes possible to repeatedly produce homogeneous nanofibers.

The method for producing nanofibers according to the embodiment is a contact step S1 in which a raw material solution S, which is a raw material for nanofiber F, is prepared and the raw material solution S and the moving member 20 are brought into contact with each other, and the moving member 20 is moved away from the raw material solution S. Since the nanofiber forming step S2 of moving in the direction and stretching the raw material solution S to form the nanofiber F is included, the nanofiber F is manufactured in a state of orientation as shown in Examples described later. This is a method for manufacturing nanofibers.

Further, according to the method for manufacturing nanofibers according to the embodiment, since the nanofiber F is formed by directly stretching the raw material solution by the moving member 20, a mechanism for generating a high temperature airflow and a high voltage are applied. It is possible to manufacture the nanofiber F by a simple method without using the mechanism of.

Further, according to the method for producing nanofibers according to the embodiment, since the nanofiber F is formed by directly stretching the raw material solution by the moving member 20, it is compared with the method for producing nanofibers by the melt spinning method or the electrospinning method. As a result, the nanofiber F can contain a large amount of various substances.

Further, according to the method for manufacturing nanofibers according to the embodiment, since the moving member 20 uses a needle-shaped member having a sharp end on the side to be in contact with the raw material solution S, the end portion is sharp and thin. This makes it possible to stably produce nanofiber F having a small fiber diameter.

Further, according to the method for manufacturing nanofibers according to the embodiment, since the moving member 20 has a thickness of 5 mm or less at the portion of the moving member 20 in contact with the raw material solution S, the moving member 20 (needle-shaped member) is used. ) Can be made sufficiently thin to produce a sufficiently thin nanofiber F.

Further, according to the nanofiber manufacturing method according to the embodiment, when the contact step S1 and the nanofiber forming step S2 are repeated a plurality of times and then the nanofiber F is recovered, the contact step S1 and the nanofiber forming step S2 are performed. It is possible to obtain a large amount of nanofibers F from a quantitative raw material solution S as compared with the case where each is carried out once.

[Example]
In the examples, the nanofiber manufacturing apparatus of the present invention was actually produced, and the method for producing nanofibers of the present invention was carried out using the nanofiber manufacturing apparatus. In addition, the structure, physical properties, etc. of the nanofibers produced by the method for producing nanofibers of the present invention were investigated using the nanofiber production apparatus of the present invention.

1. 1. Reagents, Equipment, etc. Used in Examples FIG. 3 is a photograph shown to explain the nanofiber manufacturing equipment according to the examples. FIG. 3A is a photograph showing the moving members 20a, 20b, 20c (needle-shaped members, more specifically, commercially available needles) used in the examples, and FIG. 3B is a moving member 20b used in the examples. , Is a photograph showing a connecting member 30a and a moving mechanism 40a. The fact that the moving member 20b is shown in FIG. 3B is merely an example, and in the embodiment, the moving members 20a and 20c are also used by being set on the connecting member in the same manner as the moving member 20b.
First, the substances, devices, and the like used in the examples will be described.

Polyethylene oxide (PEO. Average Mv: ~ 8,000,000 or 15,000. Powder) was purchased from Sigma-Aldrich.
Distilled water for the solvent used was distilled in the laboratory.
As the surface active agent, sodium dodecyl sulfate, which was purchased from Nacalai Tesque Co., Ltd., was used.
As the single-walled carbon nanotubes (CNTs), those having (7,6) chirality, ≧ 90% carbon basis (≧ 99% as carbon nanotubes), and 0.83 nm average diameter were used.

In order to manufacture the nanofibers in the examples, the nanofiber manufacturing apparatus according to the examples was used. Hereinafter, the components of the nanofiber manufacturing apparatus according to the embodiment will be described.
As the solution arranging member in the nanofiber manufacturing apparatus according to the embodiment, a resin member (bathtub-shaped member) having a recess for arranging the solution in the center was used.

As the moving member, a needle-shaped member, which is a commercially available needle, was used (see FIG. 3A). Specifically, the moving member has a diameter (thickness) of 1.02 mm (see reference numeral 20a in FIG. 3A) and a moving member having a diameter of 0.5 mm (see reference numeral 20b in FIG. 3A). And three types having a diameter of 0.12 mm (see reference numeral 20c in FIG. 3A) were used.
A needle manufactured by Clover Co., Ltd. was used as a needle-shaped member having a diameter of 0.5 mm and a needle-shaped member having a diameter of 1.02 mm. Further, a needle manufactured by Seirin Corporation was used as a needle-shaped member having a diameter of 0.12 mm.
As the connecting member, a commercially available prismatic acrylic rod having a hole for arranging the moving member and a hole for passing the guide member was used (see reference numeral 30a in FIG. 3B).

As the moving mechanism, RS-220-R-C1-N-5-500-S, which is a single-axis robot of Misumi Corporation, was used (see reference numeral 40a in FIG. 3B). The single-axis robot can finely adjust the moving speed of the moving target, and the maximum moving speed is 1000 mm / sec and the maximum moving distance is 500 mm. In the embodiment, the moving speed is the stretching speed of the nanofibers, and the moving distance is the stretching distance of the nanofibers.
As the guide member, a commercially available cylindrical stainless steel rod was used.

In order to manufacture the nanofibers in the comparative example, the nanofiber manufacturing apparatus according to the comparative example, which is a nanofiber manufacturing apparatus for carrying out the electrospinning method, was used. Hereinafter, the components of the nanofiber manufacturing apparatus according to the comparative example will be described.
As the high voltage supply device (power supply device), Har-100 * 12 manufactured by Matsusada Precision Co., Ltd. was used. The applied voltage during spinning was 12 kV.
As the collector, a rotary drum collector covered with aluminum foil was used.
As the syringe, a general-purpose 5 mL plastic syringe was used.
The inner diameter of the capillary tip attached to the syringe was 0.6 mm.
A copper wire connected to the anode of the high voltage supply device was used to charge the raw material solution.
The distance between the chip and the collector was 15 cm.

Hereinafter, the devices and instruments used for observations and experiments on the nanofibers in the examples and the nanofibers in the comparative examples will be described.
As a scanning electron microscope (SEM), JSM-6010LA of JEOL Ltd. was used.
JFC of JEOL Ltd. was used as a sputtering device for giving conductivity to the sample.
To calculate the fiber diameter of the sample. In the measurement of the fiber diameter using the image analysis software ImageJ, 50 random points were selected from SEM images showing a plurality of nanofibers, and the average value was obtained.

As a transmission electron microscope (TEM: Transmission Electron Microscope), JEM2100 manufactured by JEOL Ltd. was used.
As a Raman spectrophotometer, a Hololab 5000 from Kaiser Optical Systems was used.
As a tensile tester for measuring the tensile strength, a single thread tensile tester (ultrafine fiber mechanical strength tester) NFR-1000 (FITRON) manufactured by Reska Co., Ltd. was used.

2. 2. The nanofiber manufacturing apparatus according to the embodiment and the nanofiber manufacturing apparatus according to the comparative example The nanofiber manufacturing apparatus according to the embodiment basically has the same configuration as the nanofiber manufacturing apparatus 1 according to the embodiment, and has a solution arrangement. It is a combination of a member, a moving member, a connecting member, a moving mechanism, a guide member, and a base (see FIG. 1).

As the nanofiber manufacturing apparatus according to the comparative example, a combination of the above-mentioned high voltage supply apparatus, collector, capillary tip, syringe and copper wire was used. Since such a nanofiber manufacturing apparatus (nanofiber manufacturing apparatus for carrying out the electric field spinning method) is widely known, the illustration is omitted.

3. 3. Method for Producing Nanofibers According to Examples The method for producing nanofibers according to Examples is basically the same as the method for producing nanofibers according to the embodiment, and includes a contact step and a nanofiber forming step.

(1) Contact step In the contact step according to the example, a raw material solution was prepared by the following procedure. First, a powder of polyethylene oxide (molecular weight: ~ 8,000,000), which is a polymer constituting nanofibers, was put into distilled water and stirred with a magnetic stirrer for 2 hours or more. Then, the surfactant was added so that the concentration became 0.3 wt%, and the mixture was further stirred for 20 minutes or more. Finally, a predetermined amount of carbon nanotubes was added to the required sample, and the mixture was stirred for 1 hour or more to prepare a raw material solution.

In the examples, in order to investigate the influence of the concentration of polyethylene oxide, three kinds of raw material solutions having the concentration of polyethylene oxide of 2 wt%, 2.5 wt% and 3 wt% were used.
Further, in the examples, in order to investigate the influence of the addition amount of carbon nanotubes, three kinds of raw material solutions having carbon nanotube concentrations of 0.5 wt%, 1.0 wt% and 1.5 wt% were used.

The raw material solution prepared as described above was placed in contact with the moving member by arranging 2 mL of the raw material solution on the solution arranging member of the nanofiber manufacturing apparatus according to the example.

(2) Nanofiber forming process FIG. 4 is a photograph showing how the manufactured nanofibers are collected. In FIG. 4, reference numeral F is a nanofiber, and reference numeral W is a wire hanger.
The stretching speed and distance were set by a PC connected to the moving mechanism. The nanofibers were formed by repeating the contact step and the nanofiber forming step for 5 minutes per 2 mL of the raw material solution.
Then, the produced nanofibers were recovered by using a wire hanger deformed in an annular shape and pressing the wire hanger against the nanofibers from a side different from the stretching direction of the nanofibers (see FIG. 4). After recovery, the nanofibers were dried at room temperature for 24 hours.

4. Method for producing nanofibers according to a comparative example The method for producing nanofibers according to a comparative example is a method for producing nanofibers by an electrospinning method, which is a general method.
It is difficult to use polyethylene oxide having a large molecular weight in the electrospinning method mainly because of the viscosity of the raw material solution (spinning solution). Therefore, in the method for producing nanofibers according to the comparative example, the nanofibers were produced using polyethylene oxide having a molecular weight of 15,000, which has a smaller molecular weight than the method for producing nanofibers according to the examples. The concentration of polyethylene oxide in the raw material solution was set to 5.0 wt% after examining the optimum conditions in advance. When carbon nanotubes were added to the raw material solution, the concentration was set to 0.5 wt%.

The formation of nanofibers (electric field spinning) was performed in an environment of a temperature of 20 ± 3 ° C. and a humidity of 30 ± 5%. The non-woven fabric made of the formed nanofibers was peeled off from a collector, recovered, and then dried at room temperature for 24 hours in order to remove the residual solvent.

5. Structure and Physical Properties of Nanofibers in Examples The structure and physical properties of nanofibers in Examples will be described below with comparison with nanofibers in Comparative Examples.

FIG. 5 is an SEM (scanning electron microscope) image shown for explaining the orientation of nanofibers produced by the nanofiber manufacturing apparatus according to the embodiment. FIG. 5A is an SEM image of nanofibers (nanofibers formed by an electric field spinning method) in a comparative example, and FIG. 5B is an SEM image of nanofibers in an example. In addition, "ES" in FIG. 5A is a character indicating that it was manufactured by using an electrospinning method (electrospinning method), and "NS" in FIG. 5B is a method for manufacturing nanofibers of the present invention. It is a character indicating that it was manufactured using (needle spinning method).

FIG. 6 is an SEM image of nanofibers in an example when a needle-shaped member having a thickness of 0.12 mm is used. FIG. 6 (a) is an SEM image of nanofibers when the concentration of polyethylene oxide in the raw material solution is 2.0 wt%, and FIG. 6 (b) shows the concentration of polyethylene oxide in the raw material solution is 2.5 wt%. FIG. 6C is an SEM image of the nanofibers at the time, and FIG. 6C is an SEM image of the nanofibers when the concentration of polyethylene oxide in the raw material solution is 3.0 wt%. The numbers displayed in the upper left of each SEM image of FIGS. 6 (a) to 6 (c) are the concentrations (unit: wt%) of polyethylene oxide in the raw material solution of nanofibers shown in the SEM images. be. The same applies to the numbers displayed in the upper left of each SEM image of FIGS. 7 (a) to 7 (c) and FIGS. 8 (a) to 8 (c).

FIG. 7 is an SEM image of nanofibers in an example when a needle-shaped member having a thickness of 0.5 mm is used. FIG. 7 (a) is an SEM image of nanofibers when the concentration of polyethylene oxide in the raw material solution is 2.0 wt%, and FIG. 7 (b) shows the concentration of polyethylene oxide in the raw material solution is 2.5 wt%. It is an SEM image of the nanofiber at the time, and FIG. 7 (c) is an SEM image of the nanofiber when the concentration of polyethylene oxide in the raw material solution is 3.0 wt%.

FIG. 8 is an SEM image of nanofibers in an example when a needle-shaped member having a thickness of 1.02 mm is used. FIG. 8 (a) is an SEM image of nanofibers when the concentration of polyethylene oxide in the raw material solution is 2.0 wt%, and FIG. 8 (b) shows the concentration of polyethylene oxide in the raw material solution is 2.5 wt%. FIG. 8C is an SEM image of the nanofibers at the time, and FIG. 8C is an SEM image of the nanofibers when the concentration of polyethylene oxide in the raw material solution is 3.0 wt%.

FIG. 9 is a graph showing the relationship between the concentration of polyethylene oxide in the raw material solution and the fiber diameter of the produced nanofibers for each thickness of the needle-shaped member in the embodiment. The horizontal axis of the graph of FIG. 9 represents the concentration of polyethylene oxide, and the vertical axis represents the fiber diameter. In the graph of FIG. 9, the one shown by 20a (the symbol representing the value is marked with a circle) is the result for the moving member having a diameter of 1.02 mm, and the one shown by 20b (the symbol representing the value is marked with a square) is the diameter. The results are for a moving member of 0.5 mm, and the one shown by 20c (the symbol representing the value is a triangle mark) is the result for the moving member having a diameter of 0.12 mm.

First, the difference in orientation due to the difference in the manufacturing method was investigated using SEM. As a result, the nanofibers in the comparative example were not oriented (the orientation of the nanofibers was random), whereas the nanofibers in the examples were oriented (the orientation of the nanofibers). Was aligned in one direction).
The nanofibers in FIG. 5A are those when the concentration of polyethylene oxide is 5.0 wt%, the stretching speed is 1000 mm / sec, and the stretching distance is 500 mm, and the nanofibers in FIG. 5B are poly. This is when the concentration of polyethylene oxide is 2.0 wt%.

Next, the influence of the thickness of the moving member and the influence of the concentration of polyethylene oxide in the raw material solution were investigated using SEM. The nanofibers shown in FIGS. 6, 7 and 8 were manufactured with a stretching speed of 1000 mm / sec and a stretching distance of 500 mm.
As a result, as shown in FIGS. 6 (a) to 8 (c) and FIG. 9, it was confirmed that the fiber diameter tends to increase as the concentration of polyethylene oxide increases. It is considered that this is because the larger the amount of the solvent, the more easily the fiber diameter of the nanofibers shrinks as the solvent (distilled water) evaporates after the raw material solution is stretched.
It was also confirmed that the thicker the moving member, the larger the fiber diameter tends to be.

In the subsequent experiments, unless specific conditions were described, the experiments were carried out under the conditions of a polyethylene oxide concentration of 2.0 wt%, a moving member thickness of 0.12 mm, a stretching speed of 1000 mm / sec, and a stretching distance of 500 mm.

Next, the effects of stretching speed and stretching distance were investigated.
FIG. 10 is an SEM image shown for explaining the influence of the stretching speed of the raw material solution in the examples. FIG. 10 (a) is an SEM image of the nanofiber in the example when the stretching speed is 1000 mm / sec, and FIG. 10 (b) is an SEM of the nanofiber in the example when the stretching speed is 500 mm / sec. It is an image, and FIG. 10 (c) is an SEM image of nanofibers in an example when the stretching speed is 250 mm / sec.

FIG. 11 is an SEM image shown for explaining the influence of the stretching distance of the raw material solution in the examples. FIG. 11A is an SEM image of nanofibers in an example when the stretching distance is 500 mm, and FIG. 11B is an SEM image of nanofibers in an example when the stretching distance is 250 mm. FIG. 11 (c) is an SEM image of nanofibers in an example when the stretching distance is 100 mm / sec.

First, nanofibers were produced with stretching speeds of 1000 mm / sec, 500 mm / sec and 250 mm / sec. The stretching distances were all set to 500 mm.
As a result, as shown in FIGS. 10 (a) to 10 (c), it was confirmed that the slower the stretching speed, the lower the orientation of the nanofibers and the larger the fiber diameter tended to be.

Next, nanofibers were manufactured with stretching distances of 500 mm, 250 mm and 100 mm. The stretching speed was set to 1000 mm / sec.
As a result, as shown in FIGS. 11 (a) to 11 (c), the orientation of the nanofibers tends to increase as the stretching distance becomes shorter, but a bead-like structure is generated in the nanofibers, and the fibers are formed. It was confirmed that the diameter tends to increase.

Next, nanofibers containing carbon nanotubes were produced and analyzed by the Raman scattering method (molecular structure analysis).
FIG. 12 is a graph showing the Raman spectrum of nanofibers in the examples. In the graph of FIG. 12, those indicated by reference numerals e1 to e3 represent the results relating to the nanofibers in the examples, and those indicated by the reference numerals r represent the results relating to the nanofibers in the comparative example. The reference numeral e1 represents the result when the concentration of carbon nanotubes in the raw material solution is 0.5 wt%, and the reference numeral e2 shows the result when the concentration of carbon nanotubes in the raw material solution is 1.0 wt%. It is represented by reference numeral e3 and represents the result when the concentration of carbon nanotubes in the raw material solution is 1.5 wt%.
In the example, three measurements were made for one sample. The average value was used as the experimental result.

As a result, as shown in FIG. 12, a peak caused by a carbon atom having a D band dangling bond found near 1590 cm ^-1 and a D band dangling bond found near 1350 cm ^-1 was confirmed. It was also confirmed that the higher the content of carbon nanotubes, the larger the peak. Therefore, the nanofibers in the examples contain carbon nanotubes, and the amount of carbon nanotubes contained in the nanofibers produced can be increased by increasing the content (concentration) of the carbon nanotubes in the raw material solution. It could be confirmed.

Next, the inside of the fiber was observed using TEM.
FIG. 13 is a TEM (transmission electron microscope) image showing the state of nanofibers containing carbon nanotubes in the examples. FIG. 13 (a) is a TEM image of nanofibers in a comparative example, and FIG. 13 (b) is a TEM image of nanofibers in an example when the concentration of carbon nanotubes in the raw material solution is 0.5 wt%. FIG. 13 (c) is a TEM image of nanofibers in an example when the concentration of carbon nanotubes in the raw material solution is 1.0 wt%, and FIG. 13 (d) shows a concentration of carbon nanotubes in the raw material solution of 1.5 wt%. It is a TEM image of the nanofiber in the example when it is%.

As a result, the carbon nanotubes are aggregated in the nanofibers in the comparative example, that is, the nanofibers produced by the method for producing nanofibers for carrying out the electrospinning method (the hump shape of FIG. 13A). In contrast to the nanofibers in the examples, it was confirmed that the carbon nanotubes were dispersed (displayed in dark black in the nanofibers of FIGS. 13 (b) to 13 (d). See the part that is.).

Next, the tensile strength was measured.
FIG. 14 is a graph showing a strain-stress curve of nanofibers in an example. The horizontal axis of the graph of FIG. 14 represents strain (unit:%), and the vertical axis represents stress (unit: MPa). In the graph of FIG. 14, those represented by reference numerals e1 to e3 represent the results relating to nanofibers in Examples, and those represented by reference numerals r represent the results relating to nanofibers in Comparative Examples. The reference numeral e1 represents the result when the concentration of carbon nanotubes in the raw material solution is 0.5 wt%, and the reference numeral e2 shows the result when the concentration of carbon nanotubes in the raw material solution is 1.0 wt%. It is represented by reference numeral e3 and represents the result when the concentration of carbon nanotubes in the raw material solution is 1.5 wt%.
In the measurement of tensile strength, the stretching speed was set to 150 μm / sec. The measurement was performed 5 times for each sample, and the average value was used as the final value.

As a result, as shown in FIG. 14, the breaking strength of the nanofibers in the comparative example was 11.0865 MPa, whereas the nanofibers in the examples were 21.3485 MPa, 21 from the one with the lowest carbon nanotube content. The results were 0.7280 MPa and 23.0083 MPa, and it was confirmed that the nanofibers in the examples had nearly twice the strength as the nanofibers in the comparative examples. It is considered that this is because the polymer chains are arranged and the crystallinity is increased because the nanofibers are formed by stretching the raw material solution. It was also confirmed that the higher the content of carbon nanotubes, the lower the elongation rate and the higher the breaking strength.

From the above results, it can be confirmed that according to the nanofiber manufacturing apparatus and the nanofiber manufacturing method according to the present invention, it is possible to manufacture nanofibers in a state of orientation under various conditions. rice field. Further, it was confirmed that the nanofiber manufacturing apparatus and the nanofiber manufacturing method according to the present invention are suitable for manufacturing nanofibers containing a substance such as carbon nanotubes.

Although the present invention has been described above based on the above embodiments and examples, the present invention is not limited to the above embodiments and examples. It can be carried out in various modes within the range that does not deviate from the purpose.
For example, the configurations described in the above-described embodiment and each experimental example are examples or specific examples, and can be changed as long as the effects of the present invention are not impaired.

(1) In the above embodiment, the number of moving members is four, but the present invention is not limited thereto. The number of moving members may be 3 or less, or 5 or more. Further, the arrangement of the moving members is not limited to a linear shape, and can be appropriately determined according to the number of moving members and the like.

(2) In the above embodiment, the nanofiber manufacturing apparatus includes a guide member, but the present invention is not limited thereto. When the moving member and the connecting member can be supported only by the moving mechanism, the guide member is not always necessary.

(3) In the above embodiment, the nanofiber manufacturing apparatus includes a moving mechanism, but the present invention is not limited thereto. For example, instead of the moving mechanism, a mechanism for manually moving the moving member may be provided.

1 ... Nanofiber manufacturing equipment, 10 ... Solution placement member, 12 ... Solution container, 20, 20a, 20b, 20c ... Moving member, 30, 30a ... Connecting member, 40, 40a ... Moving mechanism, 50 ... Guide member, 60 ... Base, F ... Nanofiber, S ... Raw material solution, W ... Wire hanger

Claims (8)

A solution placement member on which the raw material solution, which is the raw material for nanofibers, can be placed,
When the raw material solution is placed on the solution arranging member, the raw material solution can be stretched to form the nanofibers by moving in a direction away from the solution arranging member after contacting with the raw material solution, at least 1. A nanofiber manufacturing apparatus characterized by including a moving member that can be moved dimensionally. The nanofiber manufacturing apparatus according to claim 1, wherein the moving member is a needle-shaped member having a sharp end on the side to be in contact with the raw material solution. The nanofiber manufacturing apparatus according to claim 2, wherein the moving member has a thickness of a portion in contact with the raw material solution of 5 mm or less. The nanofiber manufacturing apparatus according to any one of claims 1 to 3, further comprising a moving mechanism capable of repeatedly moving the moving member at a predetermined speed. A contact step of preparing a raw material solution that is a raw material for nanofibers and bringing the raw material solution into contact with a moving member that can move at least one-dimensionally.
A method for producing nanofibers, which comprises a nanofiber forming step of moving the moving member in a direction away from the raw material solution and stretching the raw material solution to form the nanofibers. The method for producing nanofibers according to claim 5, wherein as the moving member, a needle-shaped member having a sharp end on the side to be in contact with the raw material solution is used. The method for producing nanofibers according to claim 6, wherein as the moving member, a member having a thickness of a portion of the moving member in contact with the raw material solution of 5 mm or less is used. The method for producing nanofibers according to any one of claims 5 to 7, wherein the contacting step and the nanofiber forming step are repeated a plurality of times, and then the nanofibers are recovered.

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