CN112746338A

CN112746338A - Nanofiber manufacturing device and manufacturing method thereof

Info

Publication number: CN112746338A
Application number: CN201911259773.0A
Authority: CN
Inventors: 金翼水; 李昊翼; 堀口卓也; 尾谷聖; 井上胜间; 长谷川洋平
Original assignee: N2cell Inc
Current assignee: N2cell Inc
Priority date: 2019-10-31
Filing date: 2019-12-10
Publication date: 2021-05-04
Also published as: KR102234787B1

Abstract

Provided are a nanofiber manufacturing apparatus and a method for manufacturing the same, the nanofiber manufacturing apparatus according to an embodiment includes: a solution preparation unit capable of preparing a raw material solution as a raw material of nanofibers; and a moving member configured to be movable at least one-dimensionally so as to be brought into contact with the raw material solution and then moved in a direction away from the solution disposing member when the solution disposing member disposes the raw material solution, thereby extending the raw material solution to form the nanofibers. The nanofibers produced by such an apparatus can be collected in a state of orientation, and thus there is an advantage in that nanofibers having high tensile strength can be produced.

Description

Nanofiber manufacturing device and manufacturing method thereof

Technical Field

The present invention relates to nanofiber production, and more particularly, to an apparatus and a method for producing nanofibers with orientation.

Background

Recently, nanofibers have been attracting attention as extremely fine fibers on the order of nanometers. Generally, a yarn or cloth made of nanofibers has a characteristic of soft touch because it has a larger specific surface area, has fine pores with a high porosity, and is formed thinner than a yarn or cloth made of general fibers.

Therefore, nanofibers are widely used in various fields such as moisture-permeable waterproof films, high-performance filters, secondary battery separation films, electrodes, supercapacitors, solar cells, dust-free wiping cloths (clean room wipers), dust-proof clothing, masks, and artificial muscles, and research and development thereof are actively being conducted.

In the present specification, "nanofibers" mean fibers having a fiber diameter of 3000nm or less (preferably 1000nm or less) and an average diameter of 1000nm or less (preferably 500nm or less). The nanofibers contain substances other than polymers, which are substances constituting the main body of the fiber, such as carbon nanotubes and metal nanoparticles, inside or outside the fiber.

As a method for producing nanofibers made of a known polymer, a method and an apparatus for producing nanofibers by using a melt spinning method and an electro-spinning (electro-spinning) method are known (see, for example, patent documents 1 to 2).

The melt spinning method is a method of forming nanofibers by discharging a molten polymer from a narrow nozzle together with a high-temperature gas flow. The electrospinning method is a method in which a raw material solution in which a polymer is dissolved in a solvent is discharged from a nozzle in a state where a high voltage is applied between the nozzle and a collector to form nanofibers.

Patent document 1: US6114017B

Patent document 2: US6673136B

When the nanofiber is manufactured by the melt spinning method and the electric field spinning method in the prior art, the nanofiber can be manufactured into a state of a nanofiber non-woven fabric. In the case of using such a nanofiber nonwoven fabric as it is, for example, as a filter, no major problem occurs even when the existing method is used.

However, when the nanofibers are intended to have orientation (a property that the directions of the fibers are aligned in a certain direction), for example, when the nanofibers are intended to have tensile strength in a certain direction or to be used as electric wiring, there is a problem that it is difficult to realize the nanofibers by the conventional production method and apparatus.

Disclosure of Invention

Accordingly, the present invention provides an apparatus and a method for producing nanofibers capable of producing nanofibers in an oriented state.

The nanofiber manufacturing apparatus according to the present embodiment is characterized by including: a solution preparation unit that can prepare a raw material solution that is a raw material of the nanofibers; and a moving member configured to be movable at least one-dimensionally so as to be brought into contact with the raw material solution and then moved in a direction away from the solution disposing member when the solution disposing member disposes the raw material solution, thereby extending the raw material solution to form the nanofibers.

In addition, the method for producing nanofibers according to the present embodiment is characterized by including: a contact step of preparing a raw material solution that is a raw material of nanofibers, and bringing the raw material solution into contact with a moving member that is movable at least one-dimensionally; and a nanofiber forming step of moving the moving member in a direction away from the raw material solution to extend the raw material solution, thereby forming the nanofibers.

(effect of the invention)

The nanofiber manufacturing apparatus and method according to the present embodiment have an advantage of manufacturing nanofibers having directionality.

Drawings

Fig. 1 is a diagram for explaining a nanofiber manufacturing apparatus according to the present embodiment.

Fig. 2 is a diagram for explaining the method for producing nanofibers according to the present example.

Fig. 3 is a photograph showing the nanofiber manufacturing apparatus according to the present example.

Fig. 4 is a photograph showing a case where nanofibers fabricated according to the present embodiment were collected.

Fig. 5 is an SEM photograph showing the orientation of the nanofibers produced by the nanofiber manufacturing apparatus according to the present example.

Fig. 6 is an SEM photograph of the nanofibers manufactured according to the present example using needle-shaped members having a thickness of 0.12 mm.

FIG. 7 is an SEM photograph of nanofibers fabricated according to this example having needle-shaped members with a thickness of 0.5 mm.

FIG. 8 is a SEM photograph of nanofibers fabricated from needle-shaped members having a thickness of 1.02 mm.

Fig. 9 is a graph showing the relationship between the concentration of polyethylene oxide (polyethylene oxide) in the raw material solution and the fiber diameter of the produced nanofiber in terms of the thickness of the needle-shaped member in this example.

Fig. 10 is an SEM photograph showing the effect of the extension rate of the raw material solution in this example.

Fig. 11 is an SEM photograph showing the effect of the extension distance of the raw material solution in this example.

Fig. 12 is a graph showing a raman spectrum of the nanofiber according to the present embodiment.

Fig. 13 is a TEM photograph showing the pattern of nanofibers containing the carbon nanotubes of this example.

Fig. 14 is a graph showing a deformation-stress curve of the nanofiber according to the present embodiment.

Detailed Description

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

1. Nanofiber manufacturing apparatus according to embodiments

Fig. 1 is a diagram for explaining a nanofiber manufacturing apparatus according to an embodiment.

Fig. 1 (a) is a front view of the nanofiber manufacturing apparatus 1, and fig. 1 (b) is a plan view of the nanofiber manufacturing apparatus 1.

As shown in fig. 1, a nanofiber manufacturing apparatus 1 according to an embodiment includes a solution disposing member 10, a moving member 20, a connecting member 30, a power device 40, a guide member 50, and a base portion 60.

The solution arrangement member 10 accommodates a raw material solution as a raw material of nanofibers. In the embodiment, the solution preparing part 10 includes a solution inlet 12, and the raw material solution is prepared at the solution inlet 12 when the nanofibers are manufactured. The preparation of the raw material solution can be carried out directly by the user or by means of special equipment, for example.

The moving member 20 is a member that moves in a direction away from the solution disposing member 10 after coming into contact with the raw material solution when the raw material solution is disposed in the solution disposing member 10, and forms nanofibers by stretching the raw material solution. The moving member 20 is movable at least in one dimension.

In an embodiment, the nanofiber manufacturing apparatus 1 may include four moving members arranged in a linear direction. The end of the moving member 20 that comes into contact with the raw material solution is formed as a sharp needle-like member. For example, the thickness of the portion of the moving member 20 that comes into contact with the raw material solution is 5mm or less, and particularly preferably 2mm or less.

"the thickness of the portion in contact with the raw material solution is 5mm or less" means "when the end portion of the moving member in contact with the raw material solution is viewed from a cross section perpendicular to the axial direction of the moving member, the cross section is circular with a diameter of 5mm or less". However, in consideration of the strength of the moving member 20 when actually forming the nanofibers, the thickness is preferably 0.05mm or more.

In the present specification, the "needle-like member" refers to a member having a rod-like shape with at least one sharp end. The needle-like member may be a needle widely commercially available as a needle or a needle for needling, or may be a member designed for a nanofiber manufacturing apparatus. The nanofiber manufacturing apparatus 1 including the needle-shaped member shown in the drawing can be referred to as "needle spinning equipment (NS apparatus)".

The connecting member 30 is a member for connecting the moving member 20 and the power unit 40, and the moving member 20 is disposed in the connecting member 30.

The power device 40 is a device that can repeatedly move the moving member 20 at a predetermined speed. The power unit 40 directly moves the connecting member 30 to indirectly move the moving member 20. The power unit 40 may use, for example, a motor, an air cylinder, or an elastic member (spring, etc.) as power for moving the moving member 20.

The guide member 50 is a member disposed on the opposite side of the power unit 40 with respect to the connection member 30. The guide member 50 is a rod-shaped member, and is configured to slidably move with respect to the movement of the connection member 30.

The base portion 60 performs a function of supporting the respective components described above at the lower side.

2. The embodiment relates to a method for manufacturing nano-fiber

Fig. 2 is a diagram for explaining a method for producing nanofibers according to an example, and fig. 2 (a) to 2 (c) are process diagrams.

The method for producing nanofibers according to the example includes a contact step S1 and a nanofiber forming step S2.

A method for producing nanofibers using the nanofiber producing apparatus 1 shown in fig. 1 will be described.

The method for producing nanofibers according to the example is a method using a needle-like member whose end portion is sharpened only when the raw material solution S comes into contact with the moving member 20.

In the contacting step S1, a raw material solution S is prepared as a raw material of nanofibers (see fig. 2 (a)), and the raw material solution S is brought into contact with the moving member 20 that can move at least one-dimensionally (see fig. 2 (b)).

The raw material solution is a solution obtained by adding a solvent to a polymer constituting the nanofibers, and various polymers soluble in the solvent can be used as the polymer.

In this embodiment, since the nanofibers are formed by directly extending from the raw material solution, the raw material solution preferably has a predetermined viscosity. The amount and type of the polymer and solvent used for producing the raw material solution may be appropriately determined depending on the physical properties of the nanofibers to be produced.

The raw material solution may contain a substance capable of improving or adjusting the properties of the nanofibers to be produced, for example, a carbon-based substance having a structure on the order of nanometers, and metal particles or the like as a catalyst or a bactericide. In particular, since the nanofibers are formed by directly extending the nanofibers from the raw material solution in the method of producing nanofibers according to the example, it is easy to contain a large amount of substances to be contained in the nanofibers and to produce nanofibers containing fibrous substances such as carbon nanotubes.

In addition, the raw material solution may contain a substance that can adjust the properties of the raw material solution such as viscosity and surface tension, for example, a surfactant and a thickener.

In the embodiment, after the raw material solution S is disposed at the solution inlet 12 of the solution disposing part 10, the moving part 20 is brought close to the solution disposing part 10 by the power device 40, thereby contacting the raw material solution S and the moving part 20.

The nanofiber forming step S2 is a step of forming nanofibers F by moving the moving member 20 in a direction away from the raw material solution S to elongate the raw material solution S (see fig. 2 (c)).

The nanofibers F formed by the above-described method can be directly collected in a state of orientation by, for example, pressing a frame-shaped or plate-shaped member in a direction orthogonal to the extending direction of the fibers.

In the method for producing nanofibers according to the example, the contacting step S1 and the nanofiber forming step S2 may be performed once, but the contacting step S1 and the subsequent nanofiber forming step S2 may be repeated a plurality of times in order to obtain a predetermined amount of nanofibers.

In the case where the contacting process S1 and the nanofiber forming process S2 are repeated several times, the collection of the manufactured nanofibers F may be performed every time the nanofiber forming process S2 is finished, or may be performed after the contacting process S1 and the nanofiber forming process S2 are repeated several times. In order to obtain the nanofibers F in a predetermined amount, it is preferable to collect the nanofibers F after repeating the contacting step S1 and the nanofiber forming step S2 several times.

3. Effects of the method for producing nanofiber and the method for producing nanofiber according to example

The following describes the effects of the method for producing nanofibers and the method for producing nanofibers according to the examples.

The nanofiber manufacturing apparatus 1 according to the embodiment is a nanofiber manufacturing apparatus capable of manufacturing nanofibers with orientation described later, because it includes the solution arranging member 10 in which the raw material solution that is the raw material of the nanofibers can be arranged, and the moving member 20 that can move at least one-dimensionally.

In addition, according to the nanofiber manufacturing apparatus 1 of the embodiment, since the raw material solution can be extended by the moving member 20 to form the nanofibers, it is not necessary to use a device for generating a high-temperature gas flow or a device for applying a high voltage, and the nanofibers can be manufactured by a simple configuration.

In addition, according to the nanofiber manufacturing apparatus 1 according to the embodiment, since the raw material solution can be directly drawn by the moving member 20 to form the nanofibers, the nanofibers can contain a large amount of various substances as compared with nanofiber manufacturing apparatuses that perform the melt spinning method and the electric field spinning method.

In addition, according to the nanofiber manufacturing apparatus 1 of the embodiment, since the portion (end portion) of the moving member 20 that contacts the raw material solution is formed of the sharp needle-like member, nanofibers having a small diameter can be stably manufactured by the sharp and short end portion.

In addition, according to the nanofiber manufacturing apparatus 1 of the embodiment, since the thickness of the portion of the moving member 20 that contacts the raw material solution is 5mm or less, the moving member 20 (needle-like member) can be made sufficiently fine, and thus thinner nanofibers can be manufactured.

Further, according to the nanofiber manufacturing apparatus 1 of the embodiment, since the power device 40 capable of repeatedly moving the moving member 20 at a predetermined speed is provided, uniform nanofibers can be repeatedly manufactured as compared with a case where the moving member 20 is moved by manpower.

[ examples ]

In the examples, the nanofiber manufacturing apparatus of the present invention was actually manufactured, and the nanofiber manufacturing method was carried out using the nanofiber manufacturing apparatus. Further, the structure, physical properties, and the like of nanofibers produced by the nanofiber production method of the present invention using the nanofiber production apparatus of the present invention were examined.

1. Reagents, kits, etc. used in the examples

Fig. 3 is a photograph for explaining a nanofiber manufacturing apparatus according to an example. Fig. 3 (a) is a photograph showing the moving

members

20a, 20b, and 20c (needle-like members, more specifically, common needles) used in the example, and fig. 3 (b) is a photograph showing the moving member 20b, the connecting member 30a, and the power unit 40a used in the example.

The imaging of the moving member 20b in fig. 3 (b) is merely an example, and in the embodiment, the moving

members

20a and 20c may be provided as a connecting member as in the case of the moving member 20 b. First, substances, devices, and the like used in the examples will be described.

Polyethylene oxide (PEO, average Mv:. about.8,000,000 or 15,000 powder) the material purchased from Sigma Aldrich (Sigma-Aldrich) was used.

Distilled water of solvent water distilled in a laboratory was used. Sodium dodecyl sulfate (sodium dodecyl sulfonate) as a surfactant was used a material purchased from nacalai tesque corporation. As single-walled Carbon Nanotubes (CNTs), a material having chirality of (7,6), 90% carbon group (carbon nanotubes of not less than 99%) and an average diameter of 0.83nm was used.

In the nanofiber manufacturing apparatus according to the embodiment, as the solution disposing member, a resin member (bathtub-shaped member) having a recess portion at the center for disposing the solution is used.

A needle-like member (see fig. 3 (a)) as a commercially available needle was used as the moving member. Specifically, three types of moving members having a diameter (thickness) of 1.02mm (see reference numeral 20a in fig. 3 a), a diameter of 0.5mm (see reference numeral 20b in fig. 3 a), and a diameter of 0.12mm (see reference numeral 20c in fig. 3 a) are used.

As the needle-like members having a diameter of 0.5mm and the needle-like members having a diameter of 1.02mm, needles of Crossbar corporation were used. Further, as a needle-like member having a diameter of 0.12mm, a needle manufactured by SEIREN K.K. was used.

As the connecting member, a member in which a hole for disposing the moving member on a commercially available cylindrical acrylic rod and a hole for passing the guide member are formed is used (see reference numeral 30a in fig. 3 (b)).

As the power plant, a short axis robot RS-220-R-C1-N-5-500-S (see symbol 40a in FIG. 3 (b)) available from Misumi corporation was used. In addition, the short axis robot can finely adjust the moving speed of the moving object, the maximum moving speed is 1000mm/sec, and the maximum moving distance is 500 mm. In an embodiment, the moving speed represents an extension speed of the nanofiber, and the moving distance represents an extension distance of the nanofiber. As the guide member, a cylindrical stainless steel rod was used.

In the comparative example, a nanofiber manufacturing apparatus using an electric field spinning method was used to manufacture nanofibers. The following describes the components of the nanofiber manufacturing apparatus according to the comparative example.

Har-100 x 12 from matsusada precision Inc. The applied voltage during spinning was set at 12 kV.

As the collector, a rotary drum collector covered with aluminum foil was used. As a syringe (syring), a general 5mL plastic syringe was used. The inner diameter of the capillary chip attached to the syringe was set to 0.6 mm. In order to supply electric charge to the raw material solution, a copper wire connected to the anode of a high voltage supply device is used. The distance between the chip and the collector was set to 15 cm.

Hereinafter, the equipment and equipment used for observation and experiment of the nanofibers of examples and the nanofibers of comparative examples will be described.

As a Scanning Electron Microscope (SEM: Scanning Electron Microscope), JSM-6010LA from JEOL was used. As a sputtering apparatus for imparting conductivity to a sample, JFC of japan electronics co.

In order to calculate the fiber diameter of the sample, 50 points were arbitrarily selected from SEM photographs of a plurality of nanofibers for the measurement of the fiber diameter using the image analysis software ImageJ, and the average value thereof was obtained.

As a Transmission Electron Microscope (TEM: Transmission Electron Microscope), JEM2100 available from Nippon electronic Co., Ltd. As a Raman spectrometer (Raman spectrometer), Hololab 5000, which is a casser optical system, was used. As a tensile tester for measuring tensile strength, a one-wire tensile tester (a machine for testing mechanical strength of ultra fine fibers) NFR-1000(FITRON) available from rhesca was used.

2. Nanofiber manufacturing apparatus of example and nanofiber manufacturing apparatus of comparative example

The nanofiber manufacturing apparatus according to the example includes the same knot hook as the nanofiber manufacturing apparatus 1, and includes a combination of a solution arrangement member, a moving member, a connection member, a power device, a guide member, and a base portion (see fig. 1).

As the nanofiber manufacturing apparatus according to the comparative example, a combination of the high voltage supply apparatus, the collector, the capillary chip, the syringe, and the copper wire was used. Since such a nanofiber manufacturing apparatus (an apparatus using an electrospinning method) is widely known, illustration thereof is omitted.

3. The embodiment relates to a method for manufacturing nano-fiber

The method for producing nanofibers according to the example is basically the same as the method for producing nanofibers according to the example, and includes a contact step and a nanofiber forming step.

(1) Contact procedure

The contacting step according to the example produces a raw material solution as follows. First, a powder of polyethylene oxide (molecular weight: 8,000,000) as a polymer constituting nanofibers was put into distilled water, and stirred for two hours or more with a magnetic stirrer. The surfactant was added to a concentration of 0.3 wt%, and stirring was again carried out for twenty minutes or more. Finally, a predetermined amount of carbon nanotubes was added to a desired sample, and the mixture was stirred for one hour or more to prepare a raw material solution.

In the examples, in order to examine the influence of the polyoxyethylene concentration, three raw material solutions having polyoxyethylene concentrations of 2 wt%, 2.5 wt%, and 3 wt% were used.

In the examples, three raw material solutions having carbon nanotube concentrations of 0.5 wt%, 1.0 wt%, and 1.5 wt% were used to examine the influence of the addition amount of the carbon nanotubes.

The raw material solution prepared as described above was placed in a solution placement member of the nanofiber manufacturing apparatus according to the example at 2mL, and was brought into contact with a moving member.

(2) Nanofiber Forming Process

Fig. 4 is a photograph showing a case where the manufactured nanofibers were collected. In fig. 4, symbol F denotes a nanofiber, and symbol W denotes a wire hook.

The extension speed and distance are set by a PC connected to the power plant. For the formation of nanofibers, the contact step and the nanofiber formation step were repeated for 2mL of the raw material solution for five minutes.

Then, the produced nanofibers were collected while being pushed and stuck to the nanofibers from a side surface different from the extending direction of the nanofibers by the wire hook which was deformed into a hook shape (see fig. 4). After collection, the nanofibers were dried at room temperature for 24 hours.

4. Method for producing nanofiber according to comparative example

The method for producing nanofibers according to comparative examples is a method for producing nanofibers by an electrospinning method, and is a general method.

It is difficult to use polyethylene oxide having a large molecular weight as an electric field spinning method mainly from the viewpoint 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 is smaller than the method for producing nanofibers according to the example. As for the concentration of polyoxyethylene in the raw material solution, optimum conditions were investigated in advance, and set to 5.0 wt%. The year of the raw material solution was set to 0.5 wt% in the case where carbon nanotubes were added.

The nanofiber formation (electrospinning) was carried out at a temperature of 20. + -. 3 ℃ and a humidity of 30. + -. 5%. With respect to the nonwoven fabric composed of the formed nanofibers, in order to remove the residual solvent, the nonwoven fabric was peeled from the collector, collected, and dried at room temperature for 24 hours.

5. Structure and physical Properties of nanofibers in examples

Next, the structure and physical properties of the nanofibers produced according to the examples were compared with those of the nanofibers produced in the comparative examples.

Fig. 5 is an SEM photograph for explaining the orientation of the nanofibers produced by the nanofiber manufacturing apparatus according to the example. Fig. 5 (a) is an SEM photograph of nanofibers (nanofibers formed by the electrospinning method) produced in the comparative example, and fig. 5 (b) is an SEM photograph of nanofibers produced in the example. In addition, "ES" in fig. 5 (a) means that the nanofiber is manufactured by Electro-spinning (Electro-spinning method), and "NS" in fig. 5 (b) means that the nanofiber is manufactured by the nanofiber manufacturing method (needle spinning method) of the present invention.

Fig. 6 is an SEM photograph of the nanofibers manufactured according to the present example using needle-shaped members having a thickness of 0.12 mm. Fig. 6 (a) is an SEM photograph of the nanofibers when the polyethylene oxide concentration of the raw material solution is 2.0 wt%, fig. 6 (b) is an SEM photograph of the nanofibers when the polyethylene oxide concentration of the raw material solution is 2.5 wt%, and fig. 6 (c) is an SEM photograph of the nanofibers when the polyethylene oxide concentration of the raw material solution is 3.0 wt%.

In addition, the numbers shown at the upper left end of each of the SEM photographs of (a) to (c) of FIG. 6 indicate the concentration (unit: wt%) of polyethylene oxide in the raw material solution of nanofibers photographed on the SEM photographs. The same numbers are indicated at the upper left end of each SEM photograph in fig. 7 (a) to 7 (c) and fig. 8 (a) to 8 (c).

Fig. 7 is an SEM photograph of the nanofibers fabricated according to the present example using needle-shaped members having a thickness of 0.5 mm. Fig. 7 (a) is an SEM photograph of the nanofibers when the polyethylene oxide concentration of the raw material solution is 2.0 wt%, fig. 7 (b) is an SEM photograph of the nanofibers when the polyethylene oxide concentration of the raw material solution is 2.5 wt%, and fig. 7 (c) is an SEM photograph of the nanofibers when the polyethylene oxide concentration of the raw material solution is 3.0 wt%.

Fig. 8 is an SEM photograph of the nanofibers manufactured according to the present example using needle-shaped members having a thickness of 1.02 mm. Fig. 8 (a) is an SEM photograph of the nanofibers when the polyethylene oxide concentration of the raw material solution is 2.0 wt%, fig. 8 (b) is an SEM photograph of the nanofibers when the polyethylene oxide concentration of the raw material solution is 2.5 wt%, and fig. 8 (c) is an SEM photograph of the nanofibers when the polyethylene oxide concentration of 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 by the thickness of the needle-like member in this example.

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, 20a shows the results for a moving part having a diameter of 1.02mm, 20b shows the results for a moving part having a diameter of 0.5mm, and 20c shows the results for a moving part having a diameter of 0.12 mm.

First, it was examined what difference in orientation of nanofibers is due to the difference in manufacturing method by SEM. As a result, the nanofibers of the comparative example were not oriented (the direction of the nanofibers was random), but the nanofibers of the examples were oriented (the direction of the nanofibers was in a certain direction).

In addition, it is the case that the nanofiber has a concentration of polyethylene oxide of 5.0 wt%, an extension speed of 1000mm/sec, and an extension distance of 500mm in (a) of fig. 5, and it is the case that the nanofiber has a concentration of polyethylene glycol of 2.0 wt% in (b) of fig. 5.

Next, the influence of the thickness of the moving member and the influence of the polyoxyethylene concentration of the raw material solution were examined by SEM. The nanofibers shown in FIGS. 6, 7 and 8 were manufactured at an elongation rate of 1000mm/sec and an elongation distance of 500 mm.

As a result, as shown in fig. 6 (a) to 8 (c) and 9, it was confirmed that the higher the polyoxyethylene concentration, the larger the fiber diameter tends to be. This is because, as the amount of the solvent is increased, the diameter of the nanofiber tends to be more reduced as the solvent (distilled water) is evaporated after the raw material solution is elongated.

Further, it was confirmed that the larger the moving member, the larger the fiber diameter tends to be.

In the subsequent experiments, the respective conditions are not described, but the experiments are performed under the conditions that the concentration of polyethylene oxide is 2.0 wt%, the thickness of the moving member is 0.12mm, the elongation rate is 1000mm/sec, and the elongation distance is 500 mm.

Further, the influence of the extension speed and the extension distance was examined.

Fig. 10 is an SEM photograph showing the influence of the extension rate of the raw material solution in the examples. FIG. 10 (a) is an SEM photograph of a nanofiber at an elongation rate of 1000mm/sec, FIG. 10 (b) is an SEM photograph of a nanofiber at an elongation rate of 500mm/sec, and FIG. 10 (c) is an SEM photograph of a nanofiber at an elongation rate of 250 mm/sec.

Fig. 11 is an SEM photograph showing the effect of the extension distance of the raw material solution in the examples. Fig. 11 (a) is an SEM photograph of nanofibers extending at a distance of 500mm, fig. 11 (b) is an SEM photograph of nanofibers extending at a distance of 250mm, and fig. 11 (c) is an SEM photograph of nanofibers extending at a distance of 100 mm.

First, nanofibers were produced at elongation speeds of 1000mm/sec, 500mm/sec, and 250 mm/sec. In this case, the extension distance is 500 mm. As a result, as shown in fig. 10 (a) to 10 (c), it was confirmed that the lower the extension speed, the lower the orientation of the nanofibers, and the larger the fiber diameter.

Second, nanofibers were produced with extension distances of 500mm, 250mm and 100 mm. At this time, the elongation rate was 1000 mm/sec.

As a result, as shown in fig. 11 (a) to 11 (c), it was confirmed that the orientation of the nanofibers tends to be higher as the extension distance is shorter, but the nanofibers tend to have a bead-like structure and a larger fiber diameter.

Further, nanofibers containing carbon nanotubes were produced, and analysis by raman scattering (molecular structure analysis) was performed.

Fig. 12 is a graph showing a raman spectrum of the nanofiber according to the example.

In the graph of fig. 12, symbols e1 to e3 represent the results for the nanofibers of the examples, and symbol r represents the results for the nanofibers of the comparative examples.

Symbol e1 represents the result when the concentration of carbon nanotubes in the raw material solution was 0.5 wt%, symbol e2 represents the result when the concentration of carbon nanotubes in the raw material solution was 1.0 wt%, and symbol e3 represents the result when the concentration of carbon nanotubes in the raw material solution was 1.5 wt%.

In the examples, three measurements were performed on one sample, and the average thereof was taken as the experimental result.

As a result, as shown in FIG. 12, it was confirmed that the cause was 1590cm^-1G band found nearby at 1350cm^-1The D band found nearby has a peak due to a carbon atom of a dangling bond (dangling bond). In addition, it can be confirmed that the higher the content of the carbon nanotube, the larger the peak value. Therefore, it was confirmed in the examples that the nanofibers contain carbon nanotubes, and the content (concentration) of the carbon nanotubes in the raw material solution was increased to increase the amount of the carbon nanotubes contained in the produced nanofibers.

Next, observation of the fibers was performed by TEM.

Fig. 13 is a TEM (transmission electron microscope) photograph showing the pattern of the nanofiber containing carbon nanotubes in the example.

Fig. 13 (a) is a TEM photograph of nanofibers of a comparative example, fig. 13 (b) is a TEM photograph of nanofibers of an example when the concentration of carbon nanotubes in the raw material solution is 0.5 wt%, fig. 13 (c) is a TEM photograph of nanofibers of an example when the concentration of carbon nanotubes in the raw material solution is 1.0 wt%, and fig. 13 (d) is a TEM photograph of nanofibers of an example when the concentration of carbon nanotubes in the raw material solution is 1.5 wt%.

As a result, it was confirmed that the carbon nanotubes were aggregated in the nanofibers of the comparative example, that is, in the nanofibers produced by the nanofiber production method using the electrospinning method (a portion aggregated like a nodule in fig. 13 (a)).

In contrast, in the nanofibers of the examples, it was confirmed that the carbon nanotubes were dispersed (see the portions of the nanofibers indicated by dark colors in fig. 13 (b) to 13 (d)).

Next, measurement of tensile strength was performed.

Fig. 14 is a graph showing a strain-stress curve of nanofibers according to an example.

The horizontal axis of the graph of FIG. 14 represents deformation (unit:%) and the vertical axis represents stress (unit: MPa).

In the graph of fig. 14, symbols e1 to e3 represent the results for the nanofibers of the examples, and symbol r represents the results for the nanofibers of the comparative example.

The speed was set to approximately 150 μm/sec in the measurement of the tensile strength. The measurement was performed five 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 of the comparative example was 11.0865MPa, but the nanofibers of the examples showed 21.3485MPa, 21.7280MPa, and 23.0083MPa in order from the start of the low content of carbon nanotubes, and it was confirmed that the nanofibers of the examples had almost twice as high strength as the nanofibers of the comparative example.

This is because the raw material solution is extended to form nanofibers, and the polymer chains are aligned to increase the crystallinity. In addition, it was confirmed that the higher the content of the carbon nanotubes, the lower the growth rate, and the higher the breaking strength.

From the above results, it was confirmed that nanofibers can be produced under various conditions in a state of orientation by the nanofiber production apparatus and the nanofiber production method according to the present invention. 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 substances such as carbon nanotubes.

Claims

1. A nanofiber manufacturing apparatus, comprising:

a solution preparation unit capable of preparing a raw material solution as a raw material of nanofibers; and

and a moving member configured to be movable at least one-dimensionally so as to move in a direction away from the solution disposing member after coming into contact with the raw material solution when the solution disposing member disposes the raw material solution, thereby extending the raw material solution to form the nanofibers.

2. The nanofiber manufacturing apparatus as recited in claim 1,

the end of the moving member that comes into contact with the raw material solution is formed of a needle-like member having a sharp shape.

3. The nanofiber manufacturing apparatus as recited in claim 2,

the needle-like member is formed so that the thickness of a portion in contact with the raw material solution is 5mm or less.

4. The nanofiber manufacturing apparatus according to any one of claims 1 to 3, further comprising:

a power plant: providing a power capable of repeatedly moving the moving member at a predetermined speed.

5. A method for producing nanofibers, comprising:

a contact step of preparing a raw material solution that is a raw material of nanofibers, and bringing the raw material solution into contact with a moving member that is movable at least one-dimensionally; and

and a nanofiber forming step of moving the moving member in a direction away from the raw material solution to extend the raw material solution, thereby forming the nanofibers.

6. The method for producing nanofibers according to claim 5,

the contacting process and the nanofiber forming process are sequentially performed a plurality of times, and then the nanofibers are collected.