JP2009249795A - Apparatus for producing nanofiber and method for producing nanofiber - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To thickly deposit a nanofiber produced by an electrospinning method and recover the nanofiber. <P>SOLUTION: An apparatus for producing a nanofiber includes raw material liquid-jetting means 201 of jetting a raw material liquid 300 into a space, raw material liquid-charging means 202 of electrically charging the raw material liquid 300, attracting means 110 of attracting a nanofiber 301 produced to a prescribed place, a depositing member 101 of receiving the attracted nanofiber 301 and depositing the nanofiber 301, surface potential-measuring means 114 of measuring a surface potential of the deposited nanofiber 301 and polarity-changing means 115 of changing a charge polarity of the nanofiber 301 deposited, based on measured result of the surface potential-measuring means 114 to a polarity which is reverse to the surface potential. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  TECHNICAL FIELD The present invention relates to a nanofiber manufacturing apparatus and a nanofiber manufacturing method for manufacturing nanofibers using an electrospinning method (electrostatic explosion), and more particularly, a nanofiber that can be deposited and collected thickly. The present invention relates to a fiber manufacturing apparatus and a nanofiber manufacturing method.

  An electrospinning (charge-induced spinning) method is known as a method for producing a filamentous (fibrous) material (nanofiber) made of a polymer material or the like and having a submicron-scale diameter.

  In this electrospinning method, a raw material liquid in which a polymer substance or the like is dispersed or dissolved in a solvent is ejected (discharged) into the space by a nozzle or the like, and the raw material liquid is charged and charged to fly through the space. This is a method for obtaining nanofibers by electrostatically exploding the raw material liquid therein.

  More specifically, the volume of the raw material liquid is reduced as the solvent evaporates from the particles of the raw material liquid in flight through the space. On the other hand, the charge imparted to the raw material liquid remains in the raw material liquid. As a result, the charge density of the particles of the raw material liquid flying in the space increases. Since the solvent in the raw material liquid continues to evaporate, the charge density of the raw material liquid grains further increases, and the coulomb force in the repulsive direction generated in the raw material liquid grains exceeds the surface tension of the raw material liquid. When this occurs, a phenomenon (electrostatic explosion) occurs in which the polymer solution is stretched linearly explosively. The electrostatic explosions occur one after another in the space, and nanofibers made of a polymer having a submicron diameter are manufactured.

For example, in order to collect the nanofibers manufactured as described above in a nonwoven fabric state, the manufactured nanofibers may be deposited on a belt conveyor or the like as described in Patent Document 1.
JP 2002-201559 A

  However, as described above, since the nanofiber is manufactured by electrostatic explosion, the manufactured nanofiber is charged either positively or negatively. Therefore, when such charged nanofibers are deposited, electric charges accumulate in the portion where the nanofibers are deposited, and a high potential is obtained with the same polarity as the nanofibers are charged.

  In such a state, the deposited nanofibers and the nanofibers coming to be deposited repel each other due to the Coulomb force, and it is difficult to deposit and collect the nanofibers more than a certain thickness. Become.

  This invention is made | formed in view of the said problem, and it aims at provision of the nanofiber manufacturing apparatus and nanofiber manufacturing method which can collect | recover in the state which deposited nanofiber thickly.

  In order to solve the above problems, a nanofiber manufacturing apparatus according to the present invention comprises a raw material liquid injection means for injecting a raw material liquid as a raw material for nanofibers into a space, a raw material liquid charging means for charging the raw material liquid, An attracting means for attracting nanofibers produced by electrostatic explosion of the raw material liquid to a predetermined place, a deposition member for receiving and depositing nanofibers attracted by the attraction means, and deposited on the deposition member Surface potential measuring means for measuring the surface potential of the nanofiber, and polarity changing means for changing the charging polarity of the nanofiber deposited based on the measurement result of the surface potential measuring means to a polarity opposite to the surface potential. It is characterized by.

  According to this, since the surface potential that increases as nanofibers are deposited can be monitored and the charging polarity of the nanofibers can be changed at an optimal timing, it is possible to increase the efficiency of depositing the nanofibers thickly.

  Furthermore, it is preferable to include a blowing unit that generates a gas flow for transporting the nanofibers and a guide unit for guiding the transported nanofibers to a predetermined place.

  According to this, since a large amount of nanofibers can be transported to a predetermined place by a gas flow, the nanofiber can be deposited thickly in a short time by combining with the change of the charging polarity of the nanofiber. It becomes possible. Furthermore, it is preferable to provide additional charging means for further charging the nanofibers conveyed in the gas flow.

  According to this, since it becomes possible to arbitrarily charge the nanofiber, the nanofiber which has been transported for a long time by the gas flow and has a reduced charge amount is recharged, and the nanofiber is It is possible to create an attracted state.

  The attraction means is based on an attraction electrode for attracting the nanofiber by an electric field generated by applying a predetermined potential, an attraction power source for applying a predetermined potential to the attraction electrode, and a measurement result of the surface potential measurement means. In addition, there may be provided attraction polarity changing means for changing the setting of the attraction power source so that the attraction electrode has a polarity opposite to the charged polarity of the nanofiber to be deposited.

  According to this, the charged nanofiber can be attracted by the electric field that is generated positively. Furthermore, since the polarity of the potential applied to the attracting electrode can be changed when the charging polarity of the nanofiber is changed, it is possible to attract the flying nanofiber even after the nanofiber is deposited thick. It becomes.

  On the other hand, in order to solve the above problems, a nanofiber manufacturing method according to the present invention includes a raw material liquid injection step of injecting a raw material liquid as a raw material of nanofibers into a space, and a raw material liquid charging step of charging the raw material liquid And an attracting step for attracting nanofibers produced by electrostatic explosion of the raw material liquid to a predetermined place, a deposition step for receiving nanofibers attracted by the attracting step and depositing them on a deposition member, A surface potential measurement step for measuring the surface potential of the nanofiber deposited on the deposition member, and a polarity change for changing the charging polarity of the nanofiber deposited based on the measurement result of the surface potential measurement step to a polarity opposite to the surface potential And a process.

  The operational effects of adopting the method are the same as the operational effects of the nanofiber manufacturing apparatus.

  The attracting step attracts the nanofiber by an electric field generated by applying a potential to the attracting electrode, and further, after the polarity changing step, the attracting polarity is opposite to the charged polarity of the nanofiber to be deposited. It is preferable to include an attracting polarity changing step of changing the electrode at a predetermined time.

  According to this, it is possible to effectively attract the nanofiber before the change remaining in the space immediately after changing the charging polarity of the nanofiber.

  According to the present invention, the potential state of the nanofiber deposited on the deposition member can be acquired, and the charging polarity of the nanofiber to be manufactured can be switched at an appropriate place, so that the nanofiber is collected in a thickly deposited state. It becomes possible to do.

  Next, an embodiment of a nanofiber manufacturing apparatus according to the present invention will be described with reference to the drawings.

(Embodiment 1)
FIG. 1 is a cross-sectional view schematically showing a nanofiber manufacturing apparatus according to an embodiment of the present invention.

  As shown in the figure, the nanofiber manufacturing apparatus 100 includes a raw material liquid injection unit 201, a raw material liquid charging unit 202, an attracting unit 110, a deposition member 101, a surface potential measuring unit 114, and a charging polarity changing unit 115. And attraction polarity changing means 116, blowing means 203, guiding means 206, and additional charging means 207.

  Further, the raw material liquid injection means 201, the raw material liquid charging means 202, the wind tunnel body 209, and the air blowing means 203 constitute a discharge means 200. The discharge means 200 is unitized and can be attached to and detached from the guide means 206.

  Here, the raw material liquid for manufacturing the nanofiber is referred to as a raw material liquid 300, and the manufactured nanofiber is referred to as a nanofiber 301. Since it changes, the boundary between the raw material liquid 300 and the nanofiber 301 is ambiguous and cannot be clearly distinguished.

FIG. 2 is a cross-sectional view showing the discharging means.
FIG. 3 is a perspective view showing the discharging means.

  The raw material liquid injection means 201 is an apparatus that injects the raw material liquid 300 into the space. In this embodiment, an apparatus that radially injects the raw material liquid 300 by centrifugal force is adopted as the raw material liquid injection means 201. As shown in these drawings, the raw material liquid injection unit 201 includes an injection container 211, a rotating shaft 212, and a motor 213.

  The injection container 211 is a container that is capable of injecting the raw material liquid 300 into the space by centrifugal force due to its rotation while the raw material liquid 300 is injected inward, and has a cylindrical shape with one end closed, Has a number of injection ports 216. The injection container 211 is formed of a conductor in order to give a charge to the stored raw material liquid 300, and also functions as a component of the raw material liquid charging unit 202. The injection container 211 is rotatably supported by a bearing (not shown) provided on a support body (not shown), and does not shake even if it rotates at a high speed.

  Specifically, it is preferable that the diameter of the ejection container 211 is adopted from a range of 10 mm to 300 mm. If it is too large, it becomes difficult to concentrate the raw material liquid 300 and the nanofibers 301 by the gas flow, and the structure supporting the injection container needs to be strengthened in order to stably rotate the injection container. Because there is. On the other hand, if it is too small, the rotation for injecting the raw material liquid 300 by centrifugal force must be increased, and problems such as motor load and vibration occur. Furthermore, it is preferable to employ the diameter of the injection container 211 from the range of 20 mm or more and 100 mm or less. Moreover, the shape of the injection port 216 is preferably circular, and the diameter is preferably employed from a range of 0.01 mm to 2 mm. However, the shape of the injection port 216 is not limited to a circular shape, and may be a polygonal shape, a star shape, or the like.

  Note that the shape of the ejection container 211 is not limited to a cylindrical shape, and may be a polygonal column shape having a polygonal side surface or a conical shape. It is only necessary that the raw material liquid 300 flows out of the injection port 216 by centrifugal force by the rotation of the injection port 216.

  The rotation shaft body 212 is a shaft body for transmitting a driving force for rotating the injection container 211 and injecting the raw material liquid 300 by centrifugal force, and is inserted into the injection container 211 from the other end of the injection container 211. This is a rod-like body in which the closing portion and one end portion of the injection container 211 are joined. The other end is joined to the rotating shaft of the motor 213. The rotating shaft body 212 includes an insulating portion (not shown) that is an insulating portion so that the ejection container 211 and a motor 213 described later are not electrically connected.

  The motor 213 is a device that applies a rotational driving force to the injection container 211 via the rotary shaft body 212 in order to inject the raw material liquid 300 from the injection port 216 by centrifugal force. The number of revolutions of the injection container 211 is selected from a range of several rpm or more and 10,000 rpm or less depending on the diameter of the injection port 216, the viscosity of the raw material liquid 300 to be used, the type of polymer substance in the raw material liquid, and the like. It is preferable that when the motor 213 and the ejection container 211 are linearly moved as in the present embodiment, the rotational speed of the motor 213 matches the rotational speed of the ejection container 211.

  The raw material liquid charging unit 202 is a device that charges the raw material liquid 300 by charging it. In the case of the present embodiment, the raw material liquid charging means 202 is a device that generates an induced charge and applies the charge to the raw material liquid 300, and includes an induction electrode 221, an induction power supply 222, and a grounding means 223. . The injection container 211 also functions as a part of the raw material liquid charging unit 202.

  The induction electrode 221 is a member for inducing electric charge to the injection container 211 that is arranged in the vicinity and grounded when the induction electrode 221 has a high voltage with respect to the ground, and is arranged so as to surround the distal end portion of the injection container 211. It is an annular member. The induction electrode 221 also functions as a wind tunnel body 209 that guides the gas flow from the air blowing means 203 to the guiding means 206.

  Therefore, when the induction electrode 221 is set to a positive potential, a negative charge is induced in the injection container 211, and a negative charge is applied to the raw material liquid 300. Conversely, when the induction electrode 221 is set to a negative potential, a positive charge is induced in the injection container 211 and a positive charge is imparted to the raw material liquid 300.

  The size of the induction electrode 221 needs to be larger than the diameter of the ejection container 211, and the diameter is preferably adopted from a range of 200 mm or more and 800 mm or less. The shape of the induction electrode 221 is not limited to an annular shape, and may be a polygonal annular member having a polygonal shape. The induction electrode 221 only needs to be arranged so as to surround the injection container 211 with a predetermined distance from the injection container 211, and may be an annular metal wire that surrounds the injection container 211.

  The induction power supply 222 is a power supply that can apply a high voltage to the induction electrode 221. The induction power supply 222 is a direct current power supply, and is a device that can set the voltage applied to the induction electrode 221 (based on the ground potential) and the polarity based on a command from the charging polarity changing unit 115. is there.

  The voltage applied by the induction power source 222 to the induction electrode 221 is preferably set from a value in the range of 10 KV to 200 KV. In particular, the electric field strength between the ejection container 211 and the induction electrode is important, and it is preferable to arrange the applied voltage and the induction electrode 221 so that the electric field strength is 1 KV / cm or more.

  The grounding means 223 is a member that is electrically connected to the ejection container 211 and can maintain the ejection container 211 at a ground potential. One end of the grounding means 223 functions as a brush so that an electrical connection state can be maintained even when the injection container 211 is in a rotating state, and the other end is connected to the ground.

  If the induction method is adopted for the raw material liquid charging means 202 as in the present embodiment, it is possible to apply a charge to the raw material liquid 300 while maintaining the injection container 211 at the ground potential. If the injection container 211 is in the ground potential state, members such as the rotary shaft 212 and the motor 213 connected to the injection container 211 do not need to take measures against high voltage with the injection container 211, and the raw material liquid A simple structure can be adopted as the ejection unit 201, which is preferable.

  As the raw material liquid charging means 202, a charge may be applied to the raw material liquid 300 by connecting a power source directly to the injection container 211, maintaining the injection container 211 at a high voltage, and grounding the induction electrode 221. In addition, the injection container 211 is formed of an insulator, and an electrode that is in direct contact with the raw material liquid 300 stored in the injection container 211 is disposed inside the injection container 211, and an electric charge is applied to the raw material liquid 300 using the electrode. It may be a thing.

  The air blowing unit 203 is a device that generates a gas flow for changing the flight direction of the raw material liquid 300 injected from the injection container 211 to the direction guided by the guide unit 206. The air blowing unit 203 is provided on the back of the motor 213 and generates a gas flow from the motor 213 toward the tip of the injection container 211. The air blowing means 203 can generate wind power that can change the raw material liquid 300 in the axial direction until the raw material liquid 300 injected in the radial direction from the injection container 211 reaches the induction electrode 221. ing. In FIG. 2, the gas flow is indicated by arrows. In the case of the present embodiment, a blower including an axial fan that forcibly blows the atmosphere around the discharge unit 200 is employed as the blower unit 203.

  In addition, you may comprise the ventilation means 203 by other air blowers, such as a sirocco fan. Moreover, the direction of the injected raw material liquid 300 may be changed by introducing high-pressure gas. Further, a gas flow may be generated inside the guide unit 206 by the suction unit 102, the second air blowing unit 232, or the like. In this case, the air blowing means 203 does not have a device that actively generates a gas flow. However, in the case of the present invention, the air blowing means 203 is present because the gas flow is generated inside the guide means 206. Suppose you are. In addition, it is assumed that the air blowing means is also present so that a gas flow is generated inside the guiding means 206 by being sucked by the suction means 102 without the air blowing means 203. In addition, it is assumed that the air blowing means is also present so that a gas flow is generated inside the guiding means 206 by being sucked by the suction means 102 without the air blowing means 203.

  The wind tunnel body 209 is a conduit that guides the gas flow generated by the air blowing means 203 to the vicinity of the injection container 211. The gas flow guided by the wind tunnel body 209 intersects the raw material liquid 300 injected from the injection container 211, and changes the flight direction of the raw material liquid 300.

  Furthermore, the discharge unit 200 includes a gas flow control unit 204 and a heating unit 205.

  The gas flow control means 204 has a function of controlling the gas flow so that the gas flow generated by the blowing means 203 does not hit the injection port 216. In the case of the present embodiment, the gas flow control means 204 is a gas An air passage body that guides the flow so as to flow to a predetermined region is employed. Since the gas flow does not directly hit the injection port 216 by the gas flow control means 204, the raw material liquid 300 injected from the injection port 216 is prevented from evaporating at an early stage and blocking the injection port 216 as much as possible. The liquid 300 can be stably sprayed continuously. The gas flow control means 204 may be a wall-shaped windbreak wall that is arranged on the windward side of the injection port 216 and prevents the gas flow from reaching the vicinity of the injection port 216.

  The heating unit 205 is a heating source that heats the gas constituting the gas flow generated by the blowing unit 203. In the case of the present embodiment, the heating means 205 is an annular heater arranged inside the guide means 206 and can heat the gas passing through the heating means 205. By heating the gas flow by the heating means 205, the raw material liquid 300 injected into the space is promoted to evaporate, and nanofibers can be manufactured efficiently.

Again, a description will be given with reference to FIG.
The attracting means 110 is a device that attracts the nanofiber 301 produced by electrostatic explosion of the raw material liquid 300 to a predetermined place. The attracting means 110 shown in FIG. 1 is a device that attracts nanofibers using an electric field, and includes an attracting electrode 112 and an attracting power source 113.

  The attracting electrode 112 is a conductor member that is maintained at a predetermined potential with respect to the ground by the attracting power source 113. When a potential is applied to the attracting electrode 112, an electric field is generated in the space. The attracting electrode 112 is a rectangular plate-shaped member, has no protruding portion for preventing discharge, and all corners are rounded.

  The attraction power source 113 is a DC power source capable of maintaining the attraction electrode 112 at a predetermined potential with respect to the ground. Further, the attracting power source 113 can change the positive / negative (including the ground potential) of the potential applied to the attracting electrode 112 based on the signal from the attracting polarity changing means 116.

  The attracting means 110 may be not only a device that attracts using an electric field, but also a device that attracts using a gas flow, such as a vacuum suction device.

  The deposition member 101 is a member on which nanofibers 301 that are manufactured by electrostatic explosion and fly are deposited. The deposition member 101 is a thin and flexible long sheet-like member made of a material that can be easily separated from the deposited nanofibers 301. Specifically, as the deposition member 101, a long cloth made of aramid fibers can be exemplified. Furthermore, it is preferable to perform a Teflon (registered trademark) coating on the surface of the deposition member 101 because the peelability when the deposited nanofibers 301 are peeled off from the deposition member 101 is improved. Moreover, the deposition member 101 is supplied from the supply roll 111 in a state of being wound in a roll shape.

  The transfer means 104 is a device that pulls out the long deposition member 101 from the supply roll 111 while winding it, and transports the deposition member 101 together with the nanofibers 301 to be deposited. The transfer means 104 is capable of winding the nanofibers 301 deposited in a nonwoven fabric shape together with the deposition member 101.

  The surface potential measuring unit 114 is a device that measures the surface potential of the nanofiber 301 deposited on the deposition member 101, and is a device that transmits a measurement result to the charging polarity changing unit 115 and the attracting polarity changing unit 116. The surface potential measuring means 114 is a device that can measure the so-called static state (potential) in a non-contact manner including the polarity, and has the least influence on the surface potential of the nanofiber 301 by measuring the potential. It has become.

  The guide means 206 is a conduit that forms a wind tunnel that guides the manufactured nanofiber 301 to the surface of the deposition member 101. The end of the guide unit 206 is a tubular member that is connected to the end of the discharge unit 200 and can guide all of the nanofibers 301 and the gas flow discharged from the discharge unit 200. In the case of this embodiment, the compressing means 230 and the diffusing means 240 described later are also included in the guiding means 206 in the sense that the nanofiber 301 is guided.

  The compression unit 230 is a device having a function of compressing a space (inner portion of the guide unit 206) where the nanofibers 301 conveyed by the gas flow are present and increasing the density of the nanofibers 301 in the space. The second air blowing means 232 and the compression conduit 234 are provided.

  The compression conduit 234 is a cylindrical member that gradually narrows the space in which the nanofibers 301 conveyed inside the guide means 206 are present, and the gas flow generated by the second air blowing means 232 is transferred into the compression conduit 234. The peripheral wall is provided with a gas flow inlet 233 that can be introduced toward the side. The portion of the compression conduit 234 connected to the guide means 206 has an area corresponding to the area of the lead-out end of the guide means 206, and the lead-out end of the compression conduit 234 corresponds to the lead-out end. It is smaller than the area. Therefore, the compression conduit 234 has a funnel shape as a whole, and the nanofiber 301 introduced into the compression conduit 234 can be compressed together with the gas flow.

  In addition, the end shape on the upstream side (introduction side) of the compression unit 230 is an annular shape that matches the end shape of the guide unit 206. On the other hand, the end shape on the downstream side (discharge side) of the compression unit 230 is a rectangle. Further, the shape of the end portion on the downstream side (discharge side) of the compression means 230 extends over the entire width direction of the stacking member 101 (perpendicular to the drawing sheet), and the length corresponding to the moving direction of the stacking member 101 is , Narrow in the width direction. The shape of the compression means 230 gradually changes from the annular upstream end toward the rectangular downstream end.

  The second blowing means 232 is a device that generates a gas flow by introducing high-pressure gas into the compression conduit 234. In the present embodiment, the second air blowing means 232 employs a device including a tank (cylinder) capable of storing high-pressure gas and a gas outlet means having a valve 235 for adjusting the pressure of the high-pressure gas in the tank. .

  The diffusing unit 240 is a conduit that is connected to the compressing unit 230 and diffuses and disperses the nanofibers 301 that have been compressed at one end and are in a high density state. The hood that decelerates the speed of the nanofibers 301 accelerated by the compressing unit 230. Shaped member. The diffusion means 240 includes a rectangular opening on the upstream end side into which the gas flow is introduced and a rectangular opening on the downstream end side from which the gas flow is discharged, and the opening area of the opening on the downstream end side is upstream. It is set to be larger than the opening area of the opening on the end side. The diffusing means 240 has a shape that gradually increases in area from the opening on the upstream end side toward the opening on the downstream end side. The opening on the downstream end side has a larger width than the width of the deposition member 101 and is longer than an attracting electrode 112 described later.

  When the gas flow flows from the small area introduction end side of the diffusing means 240 toward the large area lead-out end side, the nanofibers 301 in a high density state are dispersed in a low density state at once, and the flow velocity of the gas flow is It falls in proportion to the cross-sectional area of the diffusing means 240. Therefore, the speed of the nanofiber 301 carried on the gas flow is reduced along with the gas flow. At this time, the nanofiber 301 gradually and uniformly diffuses as the cross-sectional area of the diffusing means 240 increases. Therefore, the nanofibers 301 can be evenly deposited on the deposition member 101. In addition, since the nanofiber 301 is not transported by the gas flow, that is, the gas flow and the nanofiber 301 are separated, the charged nanofiber 301 has a reverse polarity without being affected by the gas flow. Is attracted to the attracting electrode 112 in the state of

  The additional charging means 207 is a device having a function of enhancing the charging of the charged nanofiber 301 or charging the neutralized nanofiber 301. In the case of the present embodiment, the additional charging means 207 is attached to the inner wall of the compression means 230. As the additional charging means 207, an apparatus capable of emitting ions or particles having the same polarity as the charged nanofiber 301 into the space can be listed. Specifically, the additional charging means 207 may be an arbitrary method such as a corona discharge method, a voltage application method, an AC method, a steady DC method, a pulsed DC method, a self-discharge method, a soft X-ray method, an ultraviolet ray method, or a radiation method. it can.

  The suction means 102 is disposed in the gap between the diffusing means 240 and the attracting electrode 112. The suction means 102 is a device that forcibly sucks the gas flow that is separated from the nanofiber 301 and flows out from the gap together with the solvent evaporated from the raw material liquid 300. In the present embodiment, a blower such as a sirocco fan or an axial fan is employed as the suction unit 102. Further, the suction unit 102 can suck most of the gas stream mixed with the solvent evaporated from the raw material liquid 300 and can transport the gas stream to the solvent recovery device 106 connected to the suction unit 102. Yes.

  Furthermore, the nanofiber manufacturing apparatus 100 includes a charging polarity changing unit 115 and an attracting polarity changing unit 116 as control devices.

  The charging polarity changing unit 115 is a device that acquires information including the measurement result of the surface potential measuring unit 114 and acquires the surface potential and polarity of the nanofiber 301 deposited on the deposition member 101 from the information. When the surface potential exceeds a predetermined threshold, the device can change the charged polarity of the nanofiber 301 flying toward the deposition member 101 to a polarity opposite to the acquired polarity. In the case of the present embodiment, in order to change the charging polarity of the nanofiber 301, the induction power source 222 is controlled so as to change the polarity of the charge applied to the raw material liquid 300.

  The attraction polarity changing unit 116 is a device that acquires information including the measurement result of the surface potential measuring unit 114 and acquires the surface potential and polarity of the nanofiber 301 deposited on the deposition member 101 from the information. When the surface potential exceeds a predetermined threshold, the induced power supply 113 can be changed to a polarity opposite to the charged polarity of the nanofiber 301 flying toward the deposition member 101 based on this information.

  Next, the manufacturing method of the nanofiber 301 using the nanofiber manufacturing apparatus 100 of the said structure is demonstrated.

  First, a gas flow is generated inside the guide unit 206 and the wind tunnel body 209 by the blowing unit 203 and the second blowing unit 232. On the other hand, the gas flow generated in the guide means 206 is sucked by the suction means 102.

  Next, the raw material liquid 300 is supplied to the injection container 211 of the raw material liquid injection means 201. The raw material liquid 300 is separately stored in a tank (not shown), passes through a supply path 217 (see FIG. 2), and is supplied from the other end of the injection container 211 into the injection container 211.

  Next, while supplying electric charge to the raw material liquid 300 stored in the injection container 211 by the induction power source 222 (raw material liquid charging step), the injection container 211 is rotated by the motor 213 and charged from the injection port 216 by centrifugal force. The raw material liquid 300 is injected (raw material liquid injection step).

  Here, it is assumed that a potential is applied to the induction electrode 221 by the induction power source 222 so as to be a negative potential. In this case, a positive induced charge is induced in the ejection container 211 via the grounding means 223. Therefore, the charge supplied to the raw material liquid 300 is a positive charge.

  The raw material liquid 300 injected radially in the radial direction of the injection container 211 is changed in flight direction by the gas flow and is guided by the wind tunnel body 209 in the gas flow. The raw material liquid 300 is discharged from the discharge means 200 while manufacturing the nanofiber 301 by the electrostatic explosion (nanofiber manufacturing process). The gas flow is heated by the heating means 205, and heats the raw material liquid 300 to promote the evaporation of the solvent while guiding the flight of the raw material liquid 300. The nanofibers 301 emitted from the emission means 200 as described above are conveyed by the gas flow inside the guide means 206 (conveying process).

  Next, the nanofiber 301 passing through the inside of the compression unit 230 is accelerated by the jet of high-pressure gas, and is gradually compressed as the inside of the compression unit 230 becomes narrower and reaches a diffusion unit 240 in a high density state. (Compression process).

  Here, since there is a possibility that the nanofiber 301 transported by the gas flow until now is weakly charged, the nanofiber 301 is forcibly charged with the same polarity by the additional charging means 207 (additional charging step). .

  The nanofibers 301 transported to the diffusion means 240 are rapidly reduced in speed and uniformly dispersed (diffusion process).

  In this state, the attracting electrode 112 disposed in the opening of the diffusing unit 240 is charged with a polarity opposite to the charged polarity of the nanofiber 301 (here, “negative”), and therefore attracts the nanofiber 301 ( Attraction process). Since the deposition member 101 exists between the nanofiber 301 and the attracting electrode 112, the nanofiber 301 attracted to the attracting electrode 112 is deposited on the deposition member 101 (deposition step) (FIG. 5 ( a)).

  When nanofibers are deposited on the deposition member 101 to some extent, positive charges are gradually accumulated on the deposition member 101. The change in surface potential due to this electric charge is measured by the surface potential measuring means 114 one by one (surface potential measuring step).

  Then, as shown in FIG. 4A <1>, when the surface potential exceeds the threshold Va, the charging polarity changing means 115 controls the induction power supply 222 as shown in FIG. 4B <1>. Then, the potential applied to the induction electrode 221 is changed from negative V1 to positive V2 (polarity changing step).

  On the other hand, at the same timing as the polarity change or slightly delayed, the attracting polarity changing means 116 controls the attracting power source 113 and applies it to the attracting electrode 112 as shown in <1> of FIG. The potential is changed from negative V3 to positive V4 (polarity changing step) (see FIG. 5A).

  By doing so, the charged polarity of the deposited nanofiber 301 and the charged polarity of the flying nanofiber 301 are reversed, so that the nanofibers 301 are attracted to each other and the nanofiber 301 is further deposited.

  This time, since nanofibers with negative charging polarity are piled up, the surface potential becomes 0 as shown in FIG. And as shown in FIG.5 (c), the surface potential of the deposited nanofiber 301 becomes negative.

  When the surface potential exceeds a negative threshold value −Vb, the polarities of the induction electrode 221 and the attraction electrode 112 are reversed as shown in <2> of FIG.

  By repeating the above cycle, it is possible to deposit on the deposition member 101 in a thick state while suppressing the influence from the surface potential of the deposited nanofiber 301 low.

(Example)
Under the above configuration, it was confirmed whether there is a difference in the deposition state of the nanofiber 301 between the case where the charging polarity is not changed (conventional) and the case where the charging polarity is changed.

  Specifically, in the nanofiber manufacturing apparatus 100, the injection container 211 is a cylindrical container having a diameter of 80 mm. The injection port 216 has a diameter of 0.3 mm. Further, 108 injection ports 216 were opened around the injection container 211. The rotation speed of the injection container 211 when the raw material liquid 300 was allowed to flow out was set to 1500 rpm. The voltage of the attracting power source 113 can be switched, but was set to 20 KV.

  Moreover, as the raw material liquid 300, what was produced | generated by mixing polyvinyl alcohol and water as a solvent with 90 vol% of solvents as a polymer resin was prepared.

  Under the above configuration and conditions, the charging polarity was changed when the surface potential reached a predetermined voltage (the set value was set at 20 KV). At this time, voltages applied to the induction electrode 221 by the induction power source 222 were 60 KV and −60 KV.

  As a result, it was confirmed that the nanofiber was stably deposited without being affected by the nanofiber deposited earlier.

  On the other hand, as a comparative example, the voltage applied to the induction electrode 221 by the induction power source 222 was fixed at 60 KV.

  In this case, the thickness at which the nanofiber 301 was stably deposited on the deposition member 101 was about 20 μm. When it tried to deposit 20 micrometers or more, it became difficult for nanofiber to disperse | distribute and to deposit more. The surface potential of the deposited nanofibers at the stage of deposition of 20 μm was about 40 KV.

(Embodiment 2)
Next, another embodiment according to the present invention will be described.

  FIG. 6 is a cross-sectional view schematically showing a nanofiber manufacturing apparatus according to an embodiment of the present invention.

  The nanofiber manufacturing apparatus 100 shown in the figure is substantially the same as the nanofiber manufacturing apparatus 100 shown in the first embodiment. The differences from the first embodiment are the point that there are two discharging means 200, the point that the guiding means 206 is divided into two, and the attracting means 110. Therefore, only differences will be described in the second embodiment.

  The nanofiber manufacturing apparatus 100 includes a first emission unit 200 a and a second emission unit 200 b as the emission unit 200. The first discharge means 200a and the second discharge means 200b have the same configuration as the discharge means 200 in the first embodiment. The first discharge means 200a charges the raw material liquid 300 only positive, and the second discharge means 200b charges the raw material liquid 300 only negative.

  The guiding means 206 can be connected to both the first emitting means 200a and the second emitting means 200b, and guides the nanofiber 301 manufactured by each of them to the same flow path. Therefore, the guide means 206 in the present embodiment is Y-shaped.

  In the present embodiment, the attracting means 110 attracts the nanofiber 301 onto the deposition member 101 together with the gas flow by vacuum suction of the gas flow. In addition, the attracting unit 110 includes an area regulating unit 103 between the deposition member 101 and the suction unit 102.

  The region regulating unit 103 includes an opening having the same shape and the same area as the lead-out opening end of the diffusion unit 240 on the deposition member 101 side, and the opening on the side connected to the suction unit 102 corresponds to the suction unit 102. It is circular. Thereby, the whole nanofiber 301 diffused by the diffusing means 240 is attracted onto the deposition member 101.

Next, a method for manufacturing the nanofiber 301 in the present embodiment will be described.
First, the nanofiber 301 is manufactured by the first emitting unit 200 a and is deposited on the deposition member 101. As the nanofibers 301 are deposited, the attracting effect of the attracting means 110 decreases. On the other hand, the deposited nanofiber 301 and the flying nanofiber 301 repel each other.

  When the surface potential exceeds the threshold value Va, the charging polarity changing unit 115 stops the first induction power source 222a and stops the first discharge unit 200a. On the other hand, the charging polarity changing unit 115 operates the second induction power source 222b and also operates the second discharging unit 200b (polarity changing step).

  Thereafter, the same control as in the first embodiment is performed, and the nanofibers 301 are deposited on the deposition member 101.

  In this way, in addition to the same effects as in the first embodiment, it is not necessary to change the induction power supply 222 from a positive high voltage to a negative high voltage, and the burden on the induction power supply 222 is reduced. can do.

  In addition, the nanofibers 301 can be stacked in a multilayer structure by supplying different types of raw material liquids 300 to the first discharge means 200a and the second discharge means 200b.

  In addition, although the compression conduit | pipe 234 and the spreading | diffusion means 240 were used, in this invention, these are not essential components.

  Moreover, although the case where it attracted with an electric field and the case where it attracted with a gas flow was illustrated as an attraction means, combining these, you may attract with a gas flow, attracting with an electric field.

  In addition, examples of the polymer material constituting the nanofiber 301 include polypropylene, polyethylene, polystyrene, polyethylene oxide, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, poly-m-phenylene terephthalate, poly-p-phenylene isophthalate, and polyfluoride. Vinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, polyvinyl chloride, polyvinylidene chloride-acrylate copolymer, polyacrylonitrile, polyacrylonitrile-methacrylate copolymer, polycarbonate, polyarylate, polyester carbonate, nylon, aramid, Polycaprolactone, polylactic acid, polyglycolic acid, collagen, polyhydroxybutyric acid, polyvinyl acetate, polyethylene Etc. can be exemplified. Moreover, the kind selected from the above may be used, and a plurality of kinds may be mixed. Note that the above is an example, and the present invention is not limited to the above polymer substance.

  Solvents used for the raw material liquid 300 include methanol, ethanol, 1-propanol, 2-propanol, hexafluoroisopropanol, tetraethylene glycol, triethylene glycol, dibenzyl alcohol, 1,3-dioxolane, 1,4-dioxane. , Methyl ethyl ketone, methyl isobutyl ketone, methyl n-hexyl ketone, methyl n-propyl ketone, diisopropyl ketone, diisobutyl ketone, acetone, hexafluoroacetone, phenol, formic acid, methyl formate, ethyl formate, propyl formate, methyl benzoate, Ethyl benzoate, propyl benzoate, methyl acetate, ethyl acetate, propyl acetate, dimethyl phthalate, diethyl phthalate, dipropyl phthalate, methyl chloride, ethyl chloride, methylene chloride, chloroform , O-chlorotoluene, p-chlorotoluene, chloroform, carbon tetrachloride, 1,1-dichloroethane, 1,2-dichloroethane, trichloroethane, dichloropropane, dibromoethane, dibromopropane, methyl bromide, ethyl bromide, odor Propyl chloride, acetic acid, benzene, toluene, hexane, cyclohexane, cyclohexanone, cyclopentane, o-xylene, p-xylene, m-xylene, acetonitrile, tetrahydrofuran, N, N-dimethylformamide, pyridine, water, etc. it can. Moreover, the kind selected from the above may be used, and a plurality of kinds may be mixed. Note that the above is an example, and the present invention is not limited to the above polymer substance.

Furthermore, an additive such as an aggregate or a plasticizer may be added to the raw material liquid 300. Examples of the additive include oxides, carbides, nitrides, borides, silicides, fluorides, sulfides, and the like. From the viewpoints of heat resistance and workability, oxides are preferably used. Examples of the oxide include Al ₂ O ₃ , SiO ₂ , TiO ₂ , Li ₂ O, Na ₂ O, MgO, CaO, SrO, BaO, B ₂ O ₃ , P ₂ O ₅ , SnO ₂ , ZrO ₂ , K. ₂ O, Cs ₂ O, ZnO, Sb ₂ O ₃ , As ₂ O ₃ , CeO ₂ , V ₂ O ₅ , Cr ₂ O ₃ , MnO, Fe ₂ O ₃ , CoO, NiO, Y ₂ O ₃ , Lu ₂ Examples thereof include O ₃ , Yb ₂ O ₃ , HfO ₂ , Nb ₂ O _{5 and the} like. Moreover, the kind selected from the above may be used, and a plurality of kinds may be mixed. Note that the above is an example, and the present invention is not limited to the above polymer substance.

  The mixing ratio of the solvent and the polymer is selected from the range of 1 vol% or more and less than 50 vol% of the polymer resin constituting the nanofiber, and correspondingly, the organic solvent that is an evaporating solvent is 50 vol% or more, It is desirable to select from a range of less than 99 vol%.

  As described above, since the solvent vapor is processed without being retained by the gas flow, the raw material liquid 300 is sufficiently evaporated even if it contains 50 vol% or more of the solvent as described above, and generates an electrostatic explosion. Is possible. Therefore, since the nanofiber 301 is manufactured from a state in which the solute polymer is thin, it is possible to manufacture a thinner nanofiber 301. Moreover, since the adjustable range of the raw material liquid 300 is widened, the performance range of the manufactured nanofiber 301 can be widened.

  In the first embodiment, the nanofiber 301 generated in the attracting means 110 is deposited from the guide means 206 through the compression conduit 234 and the diffusion means 240. However, the direct diffusion from the guide means 206 removes the compression conduit 234. The guide means 206 may be connected to the attracting means 110 by gradually expanding the guide means 206 into the shape of the diffusing means 240. In such a case, the additional charging unit 207 may be disposed inside the guide unit 206.

In the second embodiment, the same contents may be used.
In the embodiment of the present invention, the surface potential of the deposited nanofiber is measured by the surface potential measuring means, and the polarities of the induction power source 222 and the attraction power source 113 are switched. If it is known that the nanofiber 301 is difficult to deposit when the nanofiber 301 is deposited on 101, the polarity of the induction power supply 222 and the induction power supply 113 may be switched every set time.

  The present invention can be used for the production of nanofibers.

It is sectional drawing which shows typically the nanofiber manufacturing apparatus which is embodiment of this invention. It is sectional drawing which shows a discharge | release means. It is a perspective view which shows discharge | release means. It is a figure which matches and shows the graph which shows transition of surface potential, and the timing chart which shows the timing of polarity change. It is a figure which shows typically the deposition state of a nanofiber. It is sectional drawing which shows typically the nanofiber manufacturing apparatus which is other embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Manufacturing apparatus 101 Deposition member 102 Suction means 103 Area | region control means 104 Transfer means 106 Solvent recovery apparatus 110 Attracting means 111 Roll 112 Attracting electrode 113 Attracting power supply 114 Surface potential measuring means 115 Charging polarity changing means 116 Attracting polarity changing means 200 Ejecting means 200a First discharge means 200b Second discharge means 201 Raw material liquid injection means 202 Raw material liquid charging means 203 Blowing means 204 Gas flow control means 205 Heating means 206 Guide means 207 Additional charging means 209 Wind tunnel body 211 Injection container 212 Rotating shaft body 213 Motor 216 Injection port 217 Supply path 221 Induction electrode 222 Induction power source 222a First induction power source 222b Second induction power source 223 Grounding means 230 Compression means 232 Second air blowing means 233 Gas flow introduction port 234 Compression conduit 235 Valve 240 Diffusion means 300 Raw material liquid 301 Nanofiber

Claims (6)

A raw material liquid injection means for injecting a raw material liquid as a raw material of the nanofiber into the space;
Raw material liquid charging means for charging the raw material liquid;
An attracting means for attracting nanofibers produced by electrostatic explosion of the raw material liquid to a predetermined place;
A deposition member that receives and deposits the nanofibers attracted by the attraction means;
Surface potential measuring means for measuring the surface potential of the nanofiber deposited on the deposition member;
A nanofiber manufacturing apparatus comprising: a polarity changing unit that changes a charging polarity of a nanofiber deposited based on a measurement result of the surface potential measuring unit to a polarity opposite to the surface potential. further,
A blowing means for generating a gas flow for conveying the nanofibers;
The nanofiber manufacturing apparatus according to claim 1, further comprising guide means for guiding the transported nanofiber to a predetermined place. further,
The nanofiber manufacturing apparatus according to claim 2, further comprising additional charging means for further charging the nanofiber conveyed in the gas flow. The attraction means is
An attracting electrode for attracting the nanofiber by an electric field generated by applying a predetermined potential;
An attraction power source for applying a predetermined potential to the attraction electrode;
2. An attraction polarity changing unit that changes a setting of the attraction power source so that the attraction electrode has a polarity opposite to a charging polarity of the nanofiber to be deposited based on a measurement result of the surface potential measurement unit. The nanofiber manufacturing apparatus described in 1. A raw material liquid injection step of injecting a raw material liquid as a raw material of the nanofiber into the space;
A raw material liquid charging step for charging the raw material liquid;
An attracting step for attracting nanofibers produced by electrostatic explosion of the raw material liquid to a predetermined place;
A deposition step of receiving the nanofibers attracted by the attraction step and depositing the nanofibers on the deposition member;
A surface potential measurement step for measuring the surface potential of the nanofiber deposited on the deposition member;
A nanofiber manufacturing method including a polarity changing step of changing a charging polarity of the nanofiber deposited based on a measurement result of the surface potential measuring step to a polarity opposite to the surface potential. The attracting step attracts the nanofiber with an electric field generated by applying a potential to the attracting electrode,
further,
6. The nanofiber manufacturing method according to claim 5, further comprising an attracting polarity changing step of changing the attracting electrode to a polarity opposite to a charging polarity of the deposited nanofiber after a predetermined time after the polarity changing step.

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