Nanofiber manufacturing device and nanofiber manufacturing method

Abstract

To provide a nanofiber manufacturing device capable of easily changing a diameter of nanofibers.SOLUTION: There is provided a nanofiber manufacturing device 1, comprising; a raw material heating unit 10 that heats and delivers a raw material, and discharges a liquid-state raw material from a raw material discharge unit 14; and a gas heating unit 20 that blows heated gas onto the liquid-state raw material discharged from the raw material discharge unit 14 to convert a raw material into nanofibers. The nanofiber manufacturing device includes a gas heating unit control unit 3c having temperature setting means, which can set and change a gas blowing temperature in the gas heating unit 20.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a nanofiber production apparatus and a nanofiber production method. [Background technology]

[0002] Recently, fiber aggregates containing extremely fine fibers on the nanometer scale (hereinafter referred to as nanofibers) have been used in a variety of applications, such as thermal insulation, sound absorption, and oil absorption. To improve their performance, these nanofibers are required to have an average fiber diameter and a characteristic fiber diameter distribution suited to their applications.

[0003] As one of the methods for producing these nanofibers, a melt-blowing method is known (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-185153 Summary of the Invention [Problem to be solved by the invention]

[0005] As described above, nanofibers are required to have an average fiber diameter and fiber diameter distribution that suit their applications. In nanofiber production devices using the melt-blowing method, the average fiber diameter and fiber diameter distribution can be changed by replacing the head, which is equipped with a raw material discharge section that discharges molten raw material (liquid raw material) and a gas discharge section that discharges gas. In other words, it has been common to adjust and change the average fiber diameter and fiber diameter distribution of nanofibers by replacing or changing the head with one that has a different shape, position, size, etc. of the raw material discharge section and the gas discharge section.

[0006] However, replacing the head of a nanofiber manufacturing device requires stopping the device, removing the head, attaching a new head, and starting up the device, which requires a significant amount of downtime for replacement.

[0007] The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a nanofiber production device that can easily change the nanofiber fiber diameter.

[0008] The main invention for achieving the above-mentioned object is a nanofiber production apparatus comprising a raw material heating section that heats and sends out raw material, and discharges the raw material in a liquid state from a raw material discharge section, and a gas heating section that sprays heated gas onto the liquid raw material discharged from the raw material discharge section to convert the raw material into nanofibers, characterized in that the nanofiber production apparatus comprises a gas heating section control section that has a temperature setting means that can set and change the gas spray temperature (hereinafter also referred to as gas temperature) in the gas heating section.

[0009] Other features of the present invention will become apparent from the description of this specification and the accompanying drawings. [Effects of the Invention]

[0010] According to the present invention, there can be provided a nanofiber production apparatus comprising a raw material heating section that heats and sends out raw material, and discharges the raw material in a liquid state from a raw material discharge section, and a gas heating section that sprays heated gas onto the liquid raw material discharged from the raw material discharge section to convert the raw material into nanofibers, wherein the nanofiber production apparatus is characterized by comprising a gas heating section control section that has a temperature setting means that can set and change the spraying temperature of the gas in the gas heating section. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a diagram showing a nanofiber production apparatus 1 of a first embodiment. [Figure 2] 1 is a diagram showing a raw material heating section 10 and a gas heating section 20 of a nanofiber production apparatus 1. FIG. [Figure 3] FIG. 2 is a view showing the arrow A in FIG. [Figure 4] FIG. 4 is a view showing the arrow BB in FIG. 3. [Figure 5] 1 is a flowchart showing a method for producing a nanofiber according to a first embodiment. [Figure 6] The graph shows the fiber diameter distribution and an electron microscope photograph at a gas temperature of 300°C. [Figure 7] The graph shows the fiber diameter distribution and an electron microscope photograph at a gas temperature of 400°C. [Figure 8] The graph shows the fiber diameter distribution and an electron microscope photograph at a gas temperature of 500°C. [Figure 9] The fiber diameter distribution and electron microscope photographs are shown at a gas temperature of 600°C. [Figure 10] FIG. 1 is a diagram showing a nanofiber production apparatus 100 according to a second embodiment. [Figure 11] 11 is a view corresponding to FIG. 3 in the first embodiment, showing the view of an arrow C in FIG. 10. FIG. [Figure 12] 10 is a flowchart showing a method for producing nanofibers according to a second embodiment.

[0012] At least the following matters will become clear from the description of this specification and the accompanying drawings.

[0013] A nanofiber production apparatus comprising: a raw material heating section that heats and sends out raw material, and discharges the raw material in a liquid state from a raw material discharge section; and a gas heating section that blows heated gas onto the liquid raw material discharged from the raw material discharge section to convert the raw material into nanofibers, wherein the nanofiber production apparatus further comprises a gas heating section control section having a temperature setting means that can set and change the blowing temperature of the gas in the gas heating section.

[0014] Such a nanofiber production device is provided with a gas heating unit control unit that can change the setting of the temperature of the gas being sprayed, making it possible to easily change the fiber diameter of the nanofibers produced.

[0015] In such a nanofiber manufacturing apparatus, it is desirable that the gas heating section includes a first gas heating section and a second gas heating section, the gas heating section control section includes a first gas heating section control section and a second gas heating section control section, the temperature of the first gas heating section is controlled by the first gas heating section control section, the temperature of the second gas heating section is controlled by the second gas heating section control section, and the first gas discharge section of the first gas heating section and the second gas discharge section of the second gas heating section are provided separately.

[0016] According to such a nanofiber manufacturing apparatus, by providing multiple gas heating units, gas heating unit control units, and gas discharge units and individually setting the gas discharge temperatures of each, the fiber diameter distribution of the nanofibers can be easily changed.

[0017] In such a nanofiber production apparatus, it is desirable that the gas blowing temperature that can be set in the gas heating unit control unit is 300°C or higher and 600°C or lower.

[0018] With this type of nanofiber manufacturing apparatus, if the gas spraying temperature is less than 300°C, the nanofibers produced will have many lumps, and if it exceeds 600°C, the nanofibers produced will have difficulty maintaining their fiber shape. Therefore, by setting the temperature at 300°C or higher and 600°C or lower, the quality of the fibers can be stabilized.

[0019] In such a nanofiber manufacturing apparatus, it is desirable that the amount of gas blown is 160 l / min or more and 400 l / min or less.

[0020] With such a nanofiber manufacturing apparatus, it becomes difficult to produce nanofiber fiber shapes when the gas spray rate is less than 160 l / min or more than 400 l / min, so by setting the rate to 160 l / min or more and 400 l / min or less, the quality of the fiber can be stabilized.

[0021] In such a nanofiber manufacturing apparatus, it is desirable that the amount of gas blown is 200 l / min or more and 320 l / min or less.

[0022] According to such a nanofiber production apparatus, by setting the gas blowing rate to 200 l / min or more and 320 l / min or less, it becomes possible to produce nanofiber fibers with even more stable quality.

[0023] A nanofiber production method comprising: a raw material heating step of heating and sending out raw material, and discharging the raw material in a liquid state from a raw material discharge portion; and a gas heating step of blowing heated gas onto the liquid raw material discharged from the raw material discharge portion to convert the raw material into nanofibers, wherein the method further comprises a temperature setting step of setting and changing the blowing temperature of the gas in the gas heating step.

[0024] According to such a nanofiber production method, the fiber diameter of the produced nanofibers can be easily changed by having a temperature setting step that can adjust and change the temperature of the gas to be sprayed. ===First Embodiment===

[0025] As one aspect of the present invention, a first embodiment of a nanofiber production apparatus will be described with reference to Figures 1 to 4. Figure 1 is a diagram showing a nanofiber production apparatus 1 of the first embodiment, Figure 2 is a diagram showing a raw material heating section 10 and a gas heating section 20 of the nanofiber production apparatus 1, Figure 3 is a diagram showing a view A in Figure 1, and Figure 4 is a diagram showing a view B-B in Figure 3.

[0026] Referring to FIG. 1, the nanofiber production apparatus 1 in the first embodiment includes a hopper 2 , a control unit 3 , a drive unit 4 , a raw material heating unit 10 , and a gas heating unit 20 .

[0027] The hopper 2 shown in Figure 1 is a part for supplying raw materials to the raw material heating section 10, and is shaped like a funnel, opening wide at the top and narrowing toward the bottom. The bottom opening 2a of the hopper 2 is connected to the top of the raw material heating section 10. In other words, when raw materials are introduced into the top opening of the hopper 2, the raw materials move from the top to the bottom and are supplied to the raw material heating section 10 from the bottom opening 2a.

[0028] In this embodiment, polypropylene (PP) pellets are used as the raw material, but this is not limited to this, and pellets of other resins such as polyethylene (PE) or polyethylene terephthalate (PET), or pellets of metal, etc. may also be used.

[0029] Furthermore, the raw material is not limited to pellets, and may be another solid material, a liquid material (for example, a solution of resin dissolved in a solvent), a mixture of multiple materials (for example, PP and PET), or a material mixed with additives, etc.

[0030] 1 includes a drive unit control unit 3a, a raw material heating unit control unit 3b, and a gas heating unit control unit 3c. The drive unit control unit 3a is a unit that controls the drive unit 4 shown in FIG.

[0031] In this embodiment, the drive unit 4 is a motor, and the drive unit control unit 3a rotates the motor at a set rotation speed. The motor is connected to the drive unit connection unit 4a at the right end of the rod 12a of the raw material heating unit 10 shown in Figure 4, and the rotation of the motor rotates the rod 12a.

[0032] Raw material heating unit control unit 3b controls the heating temperature of the raw material in raw material heating unit 10, heating raw material heater 11 to a set temperature. As shown in Figure 2, raw material heating unit 10 is provided with multiple raw material heaters 11. Each raw material heater 11 is provided with a raw material heater sensor 11a, and each raw material heater sensor 11a is provided with raw material heating unit control unit 3b.

[0033] That is, the temperature of each raw material heater 11 is detected by its own raw material heater sensor 11a, and the detected temperature is transmitted to the respective raw material heating controller 3b. If the transmitted detected temperature is equal to or higher than the set temperature, the raw material heating controller 3b stops heating the corresponding raw material heater 11; if the transmitted detected temperature is lower than the set temperature, the raw material heater 11 starts (continues) heating. In this way, the heating temperature of the raw material heater 11 is controlled.

[0034] In this embodiment, multiple (four) raw material heaters 11 are used, but this is not a limitation. Raw material heater 11 may be a single heater or five or more heaters, and there is no limitation as long as it can sufficiently heat and melt the raw material.

[0035] The set temperatures of raw material heaters 11 are determined in consideration of the melting points of the raw materials. In this embodiment, PP pellets are used as the raw material, so at least one of raw material heaters 11 is set to a temperature above the melting point of PP, approximately 160°C. The temperature is set so that the molten PP has an appropriate viscosity and does not burn.

[0036] The gas heating unit control unit 3c is a unit that controls the heating temperature of the gas (air in this embodiment) in the gas heating unit 20, and heats and adjusts the gas heater 21 to a set temperature. In the production of fibrous bodies by a general melt-blowing method, the temperature of the gas to be blown is not changed, but in this embodiment, the temperature of the gas to be blown is adjusted and changed to produce fibrous bodies.

[0037] As a means for adjusting and changing the temperature of the gas to be blown, a gas heater sensor 21a is provided in the gas heater 21 of the gas heating unit 20, as shown in Figure 2. The gas heater sensor 21a detects the temperature of the gas heater 21 and transmits the detected temperature to the gas heating unit control unit 3c.

[0038] If the transmitted detected temperature is equal to or higher than the set temperature, the gas heating unit control unit 3c stops heating of the gas heater 21, and if the detected temperature is lower than the set temperature, starts (continues) heating of the gas heater 21. In this way, the gas temperature of the gas heating unit 20 is controlled.

[0039] As shown in FIGS. 2 to 4, raw material heating section 10 includes raw material heater 11, raw material heater sensor 11a, cylinder 12, rod 12a, head 13, raw material discharge section 14, and raw material flow path 15.

[0040] As described above, raw material heater 11 is a component that heats the raw material, and raw material heater sensor 11a is a component that detects the temperature of raw material heater 11. Raw material heater 11 is attached to the outer periphery of cylinder 12 and heats the raw material via cylinder 12. Cylinder 12 is elongated in the left-right direction and has a hole that penetrates it from left to right.

[0041] A rod 12a is rotatably mounted in a hole inside the cylinder 12. The right end of the rod 12a is connected to the left end of the motor shaft, and the rod 12a rotates as the motor rotates. A spiral groove is formed on the outer periphery of the rod 12a, and the lower end opening 2a of the hopper 2 described above is provided at the top of the rod 12a.

[0042] That is, when raw material is supplied into the interior of the cylinder 12 from the top of the rod 12a, the raw material moves along the spiral groove of the rod 12a. Then, when the motor rotates the rod 12a, the raw material moves along the spiral groove from right to left inside the cylinder 12. Then, the raw material passes through the interior of the cylinder 12, which is heated by the raw material heater 11, and is heated and melted (liquefied). That is, the raw material moves from right to left inside the cylinder 12 while being heated and melted inside the cylinder 12.

[0043] A head 13 is provided at the left end of cylinder 12, and as shown in Fig. 4, head 13 is provided with a raw material discharge section 14 and a raw material flow path 15. In other words, the raw material that moves while being heated and melted inside cylinder 12 flows into raw material flow path 15 when it reaches the left end inside cylinder 12, and is finally discharged in a molten state from raw material discharge section 14 to the outside of raw material heating section 10.

[0044] As shown in FIGS. 2 to 4, the gas heating unit 20 includes a gas heater 21, a gas heater sensor 21a, a gas pipe 22, a gas discharge unit 23, and a gas flow path 24.

[0045] As described above, the gas heater 21 is a component that heats the gas, and the gas heater sensor 21a is a component that detects the temperature of the gas heater 21. The gas heater 21 is provided on the outer periphery of the gas pipe 22, and heats the gas through the gas pipe 22.

[0046] The right end of the gas pipe 22 is connected to a compressor (not shown) via a gas flow regulator (not shown). That is, the gas compressed by the compressor and whose flow rate is adjusted by the gas flow regulator is supplied from the right side to the left side inside the gas pipe 22 and heated to a set temperature by the gas heater 21.

[0047] The left end of the gas pipe 22 is connected to a gas flow path 24 provided in the head 13. In other words, when the gas supplied while being heated by the gas pipe 22 reaches the left end of the gas pipe 22, it is supplied to the gas flow path 24 and is finally discharged as compressed heated gas from the gas discharge portion 23. In other words, the heated gas is blown out from the gas discharge portion 23 as a blown gas, and is blown onto the molten raw material discharged from the raw material discharge portion 14. <<<Nanofiber Production Method in First Embodiment>>>

[0048] Next, the nanofiber manufacturing method in the first embodiment (nanofiber manufacturing apparatus 1) will be described with reference to Fig. 5. Fig. 5 is a flowchart showing the nanofiber manufacturing method in the first embodiment.

[0049] First, the nanofiber production apparatus 1 is started up to a state where it can produce nanofibers. Specifically, the main power of the nanofiber production apparatus 1 is turned on to make it operable, and the temperatures of the raw material heating unit control unit 3b and the gas heating unit control unit 3c are set (step S1).

[0050] As described above, the heating temperature of raw material heating unit control unit 3b is set so that the raw material to be used is melted in an optimal state and discharged from raw material discharge unit 14. Furthermore, gas heating unit control unit 3c is generally fixed, but in this embodiment, the setting is changed depending on the desired average fiber diameter, as will be described in detail later (corresponding to a temperature setting step).

[0051] Next, the gas flow rate is adjusted by the gas flow regulator and the gas is supplied to the gas heating unit 20 (step S2). By raising the temperature while supplying the gas, the gas temperature can be stabilized regardless of the magnitude of the gas flow rate.

[0052] The gas flow rate is set to a gas spray rate of 160 L / min or more and 400 L / min or less. This is because if the gas spray rate is less than 160 L / min or more than 400 L / min, it becomes difficult to form the shape of the nanofiber fiber, and by setting the gas spray rate to 160 L / min or more and 400 L / min or less, the quality of the nanofiber fiber can be stabilized.

[0053] Furthermore, the gas flow rate is set to 200 L / min or more and 320 L / min or less, because by setting the gas blowing rate to 200 L / min or more and 320 L / min or less, it becomes possible to produce nanofiber fibers with even more stable quality.

[0054] Next, it is confirmed that the temperatures of the raw material heating unit 10 and the gas heating unit 20 have been changed to the set temperatures (step S3). This is to ensure that each heating unit is sufficiently heated before starting to produce nanofibers.

[0055] Next, the raw material is charged into the hopper 2 (step S4). The raw material may be charged at this time, or may be charged at the beginning. Furthermore, if the raw material becomes insufficient due to nanofiber production, additional raw material can be charged even during nanofiber production.

[0056] Next, the drive unit control unit 3a drives the drive unit 4 to send the raw material toward the raw material discharge unit 14 (step S5). As described above, the raw material is melted and sent from the right side to the left side along the spiral groove of the rod 12a in the cylinder 12, and is finally discharged as molten raw material from the raw material discharge unit 14 (steps S1, S3, and S5 correspond to the raw material heating step).

[0057] Then, nanofibers are produced by blowing the raw material discharged from the raw material discharge port 14 with gas discharged from the gas discharge port 23 (step S6). As described above, the melted state of the raw material, the gas flow rate, the gas temperature, and other conditions are controlled to produce nanofibers by the so-called melt-blowing method (steps S1, S2, S3, and S6 correspond to the gas heating process).

[0058] Finally, the generated nanofibers are collected (step S7). There are various collection methods, but since the nanofibers and the sprayed gas are blown into the collection section together, it is common to use a mesh-like object that allows the gas to pass through while capturing the nanofibers. <<<The effect of gas temperature on nanofibers>>>

[0059] In this embodiment, the state of the nanofibers produced is changed by changing the gas temperature, which is generally fixed.Specific gas temperatures of 300°C, 400°C, 500°C, and 600°C were evaluated.

[0060] This is because if the gas blowing temperature is below 300°C, the nanofibers produced will have many lumps, and if it exceeds 600°C, it will be difficult for the nanofibers produced to maintain their fiber shape. In other words, if the gas blowing temperature that can be set in the gas heating unit control unit 3c is between 300°C and 600°C, the quality of the nanofiber fibers can be stabilized.

[0061] Fig. 6 shows the fiber diameter distribution and electron microscope photographs at a gas temperature of 300°C, Fig. 7 shows the fiber diameter distribution and electron microscope photographs at a gas temperature of 400°C, Fig. 8 shows the fiber diameter distribution and electron microscope photographs at a gas temperature of 500°C, and Fig. 9 shows the fiber diameter distribution and electron microscope photographs at a gas temperature of 600°C.

[0062] 6 to 9, it can be seen that the average fiber diameter of the nanofibers decreases as the gas temperature increases. The specific relationship between the gas temperature and the average fiber diameter of the nanofibers is as follows: Gas temperature Average fiber diameter 300℃ 4859nm 400℃ 3832nm 500℃ 3296nm 600℃ 2589nm

[0063] In other words, it can be said that the average fiber diameter of the nanofibers can be easily adjusted by simply changing the gas temperature setting, without incurring work downtime (dead time) for head replacement or the like.

[0064] Here, the features of the nanofiber manufacturing apparatus 1 described above can be summarized as follows: the nanofiber manufacturing apparatus 1 comprises a raw material heating unit 10 that heats and sends out the raw material, causing the liquid raw material to be discharged from the raw material discharge unit 14, and a gas heating unit 20 that sprays heated gas onto the liquid raw material discharged from the raw material discharge unit 14 to convert the raw material into nanofibers; and the apparatus 1 is equipped with a gas heating unit control unit 3c having a temperature setting means that can set and change the gas spray temperature in the gas heating unit 20.

[0065] Furthermore, the nanofiber production apparatus 1 is equipped with a gas heater control unit 3c that can change the setting of the temperature of the gas being sprayed, making it possible to easily change the fiber diameter of the nanofibers produced. === Second Embodiment ===

[0066] Next, a second embodiment will be described with reference to Figures 10 and 11. Figure 10 is a diagram showing a nanofiber production apparatus 100 in a second example, and Figure 11 is a diagram corresponding to Figure 3 in the first embodiment, showing view C in Figure 10. In the following, explanations of parts that are the same as those in the first embodiment will be omitted, and figures, symbols, etc. that are not necessary for the explanation may also be omitted.

[0067] 10 and 11, the differences between the second embodiment and the first embodiment are mainly the gas heating unit 120 and the control unit 103. Specifically, in the first embodiment, the gas heating unit 20 heats one gas and sprays it onto the raw material, whereas in the second embodiment, the gas heating unit 120 heats and sprays two gases.

[0068] As shown in the diagram, one gas heating section 20 is provided in the center of the nanofiber manufacturing apparatus 1 in the front-rear direction, as shown in Figure 3, whereas the gas heating section 120 is provided with a first gas heating section 120a at the front side of the nanofiber manufacturing apparatus 100 and a second gas heating section 120b at the back side, as shown in Figure 11.

[0069] The first gas heating unit 120a and the second gas heating unit 120b can set the gas heating temperature independently. That is, the first gas heating unit 120a heats the first gas at the heating temperature set by the first gas heating unit control unit 3ca, and the second gas heating unit 120b heats the second gas at the heating temperature set by the second gas heating unit control unit 3cb.

[0070] As shown in FIG. 11, the first gas heating section 120a includes a first gas heater 121a, a first gas heater sensor (not shown), a first gas pipe 122a, a first gas discharge section 123a, and a first gas flow path 124a.

[0071] The first gas heater 121a is a component that heats the first gas, and the first gas heater sensor is a component that detects the temperature of the first gas heater 121a. The first gas heater 121a is provided on the outer periphery of the first gas pipe 122a, and heats the first gas through the first gas pipe 122a.

[0072] The right end of the first gas pipe 122a is connected to a compressor (not shown) via a first gas flow regulator (not shown). That is, the first gas compressed by the compressor and having its flow rate adjusted by the first gas flow regulator is supplied from the right side to the left side inside the first gas pipe 122a and heated by the first gas heater 121a to a temperature set by the first gas heating unit control unit 3ca.

[0073] The left end of the first gas pipe 122a is connected to a first gas flow path 124a provided in the head 113. In other words, the first gas supplied while being heated in the first gas pipe 122a is supplied to the first gas flow path 124a when it reaches the left end of the first gas pipe 122a, and is finally discharged as a compressed heated gas from the first gas discharge part 123a. In other words, a blowing gas is blown out from the first gas discharge part 123a and sprayed onto the molten raw material.

[0074] As shown in FIG. 11, the second gas heating section 120b includes a second gas heater 121b, a second gas heater sensor (not shown), a second gas pipe 122b, a second gas discharge section 123b, and a second gas flow path 124b.

[0075] The second gas heater 121b is a component that heats the second gas, and the second gas heater sensor is a component that detects the temperature of the second gas heater 121b. The second gas heater 121b is provided on the outer periphery of the second gas pipe 122b, and heats the second gas through the second gas pipe 122b.

[0076] The right end of the second gas pipe 122b is connected to a compressor (not shown) via a second gas flow regulator (not shown). That is, the second gas compressed in the compressor and having its flow rate adjusted by the second gas flow regulator is supplied from the right side to the left side inside the second gas pipe 122b and heated by the second gas heater 121b to a temperature set by the second gas heating unit control unit 3cb.

[0077] The left end of the second gas pipe 122b is connected to a second gas flow path 124b provided in the head 113. In other words, the second gas supplied while being heated in the second gas pipe 122b is supplied to the second gas flow path 124b when it reaches the left end of the second gas pipe 122b, and is finally discharged as a compressed heated gas from the second gas discharge portion 123b. In other words, a blowing gas is blown out from the second gas discharge portion 123b and sprayed onto the molten raw material.

[0078] In other words, the gas heating section 120 comprises a first gas heating section 120a and a second gas heating section 120b, the gas heating section control section comprises a first gas heating section control section 3ca and a second gas heating section control section 3cb, the temperature of the first gas heating section 120a is controlled by the first gas heating section control section 3ca, the temperature of the second gas heating section 120b is controlled by the second gas heating section control section 3cb, and the first gas discharge section 123a of the first gas heating section 120a and the second gas discharge section of the second gas heating section are provided separately.

[0079] In this way, nanofibers with different average fiber diameters can be simultaneously obtained by, for example, setting the temperature of first gas heating unit control unit 3ca to 300° C. and setting the temperature of second gas heating unit control unit 3cb to 600° C. In other words, nanofibers produced at the above-mentioned gas temperatures of 300° C. and 600° C. can be mixed to obtain nanofibers with a wide fiber diameter distribution.

[0080] To maximize the performance of nanofibers, an average fiber diameter and fiber diameter distribution appropriate for the intended application are required. In other words, by using the nanofiber production apparatus 100 according to the second embodiment, it is possible to easily produce the average fiber diameter and fiber diameter distribution of nanofibers required for the intended application. <<<Nanofiber Production Method in Second Embodiment>>>

[0081] Next, a nanofiber manufacturing method in the second embodiment (nanofiber manufacturing apparatus 100) will be described with reference to Fig. 12. Fig. 12 is a flowchart showing the nanofiber manufacturing method in the second embodiment.

[0082] First, the raw material is charged into the hopper 2 (step S10). As in the first embodiment, the raw material may be charged at this timing, or it may be charged just before the nanofiber production apparatus 100 starts up and sends the raw material to the raw material heating section 110. Furthermore, as in the first embodiment, if the raw material runs short due to nanofiber production, additional raw material can be charged even during nanofiber production.

[0083] Next, the nanofiber production apparatus 1 is started up to a state where it can produce nanofibers. Specifically, the main power of the nanofiber production apparatus 100 is turned on to make it operable, and the temperatures of the raw material heating unit control unit 3b, first gas heating unit control unit 3ca, and second gas heating unit control unit 3cb are set (step S11).

[0084] The heating temperature of raw material heating unit control unit 3b is set so that the raw material to be used is melted in an optimal state and discharged from raw material discharge unit 14. In addition, first gas heating unit control unit 3ca and second gas heating unit control unit 3cb are set so that the average fiber diameter and fiber diameter distribution required for the application are obtained.

[0085] Next, the first gas flow rate is adjusted by the first gas flow rate regulator, and the second gas flow rate is adjusted by the second gas flow rate regulator, and the gases are supplied to the gas heating unit 120 (step S12). By raising the temperature while supplying the first gas and the second gas, the respective gas temperatures can be stabilized regardless of the magnitude of the flow rates of the first gas and the second gas.

[0086] The gas flow rate is set to 160 L / min or more and 400 L / min or less for each gas blowing rate. This is because, as in the first embodiment, it becomes difficult to generate the shape of the nanofiber fiber when the gas blowing rate is less than 160 L / min or more than 400 L / min, and by setting the gas blowing rate to 160 L / min or more and 400 L / min or less, the quality of the nanofiber fiber can be stabilized.

[0087] Furthermore, the gas flow rate is set to 200 L / min or more and 320 L / min or less for each gas spray amount, because, as in the first embodiment, by setting the gas spray amount to 200 L / min or more and 320 L / min or less, it becomes possible to produce nanofiber fibers with even more stable quality.

[0088] Next, it is confirmed that the temperatures of the raw material heating section 10 and the gas heating section 20 have been changed to the set temperatures (step S13). As in the first embodiment, this is because nanofiber production is started after it is confirmed that each heating section has been sufficiently heated.

[0089] Next, the drive unit control unit 3a drives the drive unit 4 to send the raw material toward the raw material discharge unit 14 (step S15). As in the first embodiment, the raw material is melted and sent from the right side to the left side along the spiral groove of the rod 12a in the cylinder 12, and is finally discharged as molten raw material from the raw material discharge unit 14.

[0090] Then, the raw material discharged from the raw material discharge part 14 is blown by gases discharged from the first gas discharge part 123a and the second gas discharge part 123b to produce nanofibers (step S16). The nanofibers are produced by the melt-blowing method by controlling the conditions such as the molten state of the raw material, the flow rates of the first and second gases, and the temperatures of the first and second gases.

[0091] Finally, the generated nanofibers are collected (step S7). There are various collection methods, but as in the first embodiment, since the nanofibers and the sprayed gas are blown into the collection section together, it is common to use a mesh-like object that allows the gas to pass through while collecting the nanofibers. ===Other embodiments===

[0092] The above-described embodiments are intended to facilitate understanding of the present invention and are not intended to limit the present invention. The present invention may be modified or improved without departing from the spirit thereof, and it goes without saying that the present invention includes equivalents thereof.

[0093] In the above embodiment, head 113 is provided with a plurality of rectangular raw material discharge portions 14 and rectangular first gas discharge portion 123a and second gas discharge portion 123b below them, but this is not limited to this. For example, the raw material and gas discharge portions may have another shape, such as a round shape, or first gas discharge portion 123a may be located above raw material discharge portion 14. In addition, while there are multiple raw material discharge portions 14 and only one first gas discharge portion 123a and one second gas discharge portion 123b, this is not limited to this. There may also be a single raw material discharge portion 14 and multiple first gas discharge portions 123a and multiple second gas discharge portions 123b.

Claims

1. a raw material heating unit that heats and delivers the raw material, and discharges the raw material in a liquid state from a raw material discharge unit; a gas heating unit that blows heated gas onto the liquid raw material discharged from the raw material discharge unit to convert the raw material into nanofibers; A nanofiber manufacturing apparatus comprising: A nanofiber production apparatus comprising a gas heating unit control unit having a temperature setting means that can set and change the gas spraying temperature in the gas heating unit.

2. The nanofiber production apparatus according to claim 1, the gas heating unit includes a first gas heating unit and a second gas heating unit; The gas heating unit control unit includes a first gas heating unit control unit and a second gas heating unit control unit, The temperature of the first gas heating unit is controlled by the first gas heating unit control unit, The second gas heating unit control unit controls the temperature of the second gas heating unit, A nanofiber production apparatus, characterized in that the first gas discharge port of the first gas heating section and the second gas discharge port of the second gas heating section are provided separately.

3. The nanofiber production apparatus according to claim 1, A nanofiber production apparatus characterized in that the gas blowing temperature that can be set in the gas heating unit control unit is 300°C or higher and 600°C or lower.

4. The nanofiber production apparatus according to claim 1, A nanofiber manufacturing apparatus characterized in that the amount of gas sprayed is 160 L / min or more and 400 L / min or less.

5. The nanofiber production apparatus according to claim 4, A nanofiber production apparatus characterized in that the amount of gas sprayed is 200 L / min or more and 320 L / min or less.

6. a raw material heating step of heating and feeding the raw material, and discharging the raw material in a liquid state from a raw material discharging portion; a gas heating step of blowing heated gas onto the liquid raw material discharged from the raw material discharge portion to convert the raw material into nanofibers; A method for producing nanofibers, comprising: A nanofiber production method characterized by including a temperature setting step in which the gas blowing temperature in the gas heating step can be set and changed.

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