JP4965533B2 - Nanofiber manufacturing apparatus and nanofiber manufacturing method - Google Patents

Description

  The present invention relates to a nanofiber manufacturing apparatus, and more particularly, to a nanofiber manufacturing apparatus including a charging electrode at a position different from a position where nanofibers are collected, and a nanofiber manufacturing method using the nanofiber manufacturing measure.

  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 discharged (discharged) into the space by a nozzle, etc. This is a method for obtaining nanofibers by electrostatically exploding the raw material liquid therein.

  A more specific description of the electrospinning method is as follows. That is, the raw material liquid that has been charged and discharged into the space gradually evaporates the solvent while flying through the space. As a result, the volume of the raw material liquid in flight gradually decreases, but the charge imparted to the raw material liquid remains in the raw material liquid. As a result, the charge density of the raw material liquid in flight through the space gradually increases. Since the solvent continues to evaporate, the charge density of the raw material liquid further increases, and the polymer solution explodes when the repulsive Coulomb force generated in the raw material liquid exceeds the surface tension of the raw material liquid. Phenomenon (electrostatic explosion) occurs. The electrostatic explosions occur one after another in the space, and nanofibers made of a polymer having a diameter of submicron are manufactured (for example, see Patent Document 1).

  In order to improve the production efficiency of nanofibers manufactured by the electrospinning method as described above, it is sufficient to increase the raw material liquid that flows out into the space. However, because the raw material liquid is charged at the same potential, it is difficult to flow a large amount of the raw material liquid into a small space at the same time, and it is also difficult to produce nanofibers spatially and uniformly. Met.

Therefore, the inventors of the present invention do not generate an electric field by applying a voltage between the portion where the raw material liquid flows out and the portion where the manufactured nanofibers are collected, but the raw material liquid charged in a predetermined space. Propose a nanofiber manufacturing device that can improve the production efficiency of nanofibers by transporting the produced nanofibers with a gas flow and collecting them with a collecting means arranged away from the space is doing.
JP 2008-31624 A

  However, as the inventors of the present application use the nanofiber manufacturing apparatus, some nanofibers adhere to the electrode provided to charge the raw material liquid, and the production efficiency of the nanofibers decreases. I found out.

  Furthermore, as a result of diligent efforts and research, the inventors of the present application have made the charged state of the nanofibers that flow out into the space to be 0 or to have a reverse polarity before reaching the electrodes. It has been found that adhesion to can be avoided.

  The present invention has been made on the basis of the above findings, and an object of the present invention is to provide a nanofiber manufacturing apparatus that can change the charged state of the nanofiber before reaching the electrode.

  In order to solve the above-described problems, a nanofiber manufacturing apparatus according to the present invention is a nanofiber manufacturing apparatus for manufacturing a nanofiber by electrostatically exploding a raw material liquid in a space, and the raw material liquid flows out into the space. An outflow body having an outflow hole to be formed, a charging electrode arranged at a predetermined interval from the outflow body, to which a predetermined voltage is applied to the outflow body, and a surface of the charging electrode facing the outflow body An insulating layer provided, a charging power source for setting a predetermined voltage between the outflow body and the charging electrode, and a gas flow for transporting nanofibers manufactured from the raw material liquid flowing out from the outflow body are generated. And a gas flow generation means.

  Thereby, since nanofiber can be manufactured stably, it becomes possible to maintain the production efficiency of nanofiber in a high state.

  The insulator layer is preferably made of an insulator that is more easily charged positively than rayon or more negatively charged than polyester.

  As a result, the vicinity of the charging electrode can be maintained in a highly charged state where positive or negative charges exist in a high density state, and nanofibers can be transported more stably.

  According to the present invention, the manufactured nanofiber is transported in a stable state without adhering to the charging electrode. Therefore, high production efficiency of nanofibers can be maintained.

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

  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 discharge means 200, a guide body 206, a diffusion means 240, a collection means 110, and an attracting means 120.

  Here, the raw material liquid for producing the nanofiber is referred to as a raw material liquid 300, and the manufactured nanofiber is referred to as a nanofiber 301. Therefore, 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.

  As shown in these drawings, the discharge means 200 is a unit that can discharge the charged raw material liquid 300 and the manufactured nanofibers 301 on a gas flow. The discharge means 201, the charging means 202, A wind tunnel body 209 and gas flow generation means 203 are provided.

  Furthermore, the outflow means 201 is a device that causes the raw material liquid 300 to flow out into the space. In the present embodiment, the raw material liquid 300 is caused to flow out radially by centrifugal force, and the raw material liquid is discharged to the inside of the charging electrode 221. Device. The outflow means 201 includes an outflow body 211, a rotating shaft body 212, and a motor 213. The rotating shaft body 212 is rotatably supported by a support body (not shown) via a bearing (not shown).

  The outflow body 211 is a member for allowing the raw material liquid 300 to flow out into the space, and is a member provided with many outflow holes 216 through which the raw material liquid 300 passes. In the case of the present embodiment, the outflow body 211 is a container that can cause the raw material liquid 300 to flow out into the space by centrifugal force due to its rotation while the raw material liquid 300 is injected inward, and one end is closed. It has a cylindrical shape, and has a large number of outflow holes 216 on the peripheral wall. The outflow body 211 is formed of a conductor in order to give an electric charge to the raw material liquid 300 to be stored. The outflow body 211 is rotatably supported by a bearing 215 provided on a support (not shown).

  Specifically, it is preferable that the diameter of the outflow body 211 is adopted from a range of 10 mm or more and 300 mm or less. This is because if it is too large, it will be difficult to concentrate the raw material liquid 300 and the nanofiber 301 by the gas flow described later, and if the weight balance is slightly deviated, such as the rotational axis of the effluent 211 is deviated, a large vibration will occur. This is because a structure that firmly supports the outflow body 211 is required to suppress the vibration. On the other hand, if it is too small, the rotation for causing the raw material liquid 300 to flow out by centrifugal force must be increased, which causes problems such as load and vibration of the drive source. Furthermore, it is preferable to employ the diameter of the outflow body 211 from the range of 20 mm or more and 100 mm or less.

  In addition, the shape of the outflow hole 216 is preferably circular, and the diameter thereof is preferably from about 0.01 mm to 3 mm, although it depends on the thickness of the outflow body 211. This is because if the outflow hole 216 is too small, it is difficult to cause the raw material liquid 300 to flow out of the outflow body 211, and if it is too large, the unit of the raw material liquid 300 that flows out from one outflow hole 216. This is because the amount per hour becomes too large (that is, the thickness of the line formed by the flowing out raw material liquid 300 becomes too thick), making it difficult to manufacture the nanofiber 301 having a desired diameter.

  In addition, the outflow body 211 is not only a member that causes the raw material liquid 300 to flow out into the space by the centrifugal force of its own rotation, but is also stationary and the pressurized raw material liquid 300 flows out from the outflow hole 216. A member may be used. Moreover, the shape of the outflow body 211 that causes the raw material liquid 300 to flow out by centrifugal force is not limited to a cylindrical shape, and may be a polygonal cylindrical shape having a polygonal cross section or a conical shape. Any shape may be used as long as the raw material liquid 300 can flow out of the outflow hole 216 by centrifugal force when the outflow hole 216 rotates. Further, the shape of the outflow hole 216 is not limited to a circular shape, and may be a polygonal shape or a star shape.

  The rotating shaft body 212 is a shaft body for transmitting a driving force for rotating the outflow body 211 and causing the raw material liquid 300 to flow out by centrifugal force, and is inserted into the outflow body 211 from the other end of the outflow body 211. This is a rod-like body in which the closed portion and one end portion of the outflow body 211 are joined. The other end is joined to the rotating shaft of the motor 213.

  The motor 213 is a device that applies a rotational driving force to the outflow body 211 via the rotary shaft body 212 in order to cause the raw material liquid 300 to flow out from the outflow hole 216 by centrifugal force. The rotational speed of the outflow body 211 is selected from a range of several rpm or more and 10,000 rpm or less depending on the diameter of the outflow hole 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. Preferably, when the motor 213 and the efflux body 211 are in linear motion as in the present embodiment, the rotational speed of the motor 213 matches the rotational speed of the efflux body 211.

  The charging unit 202 is a device that charges the raw material liquid 300 by applying an electric charge. In the case of the present embodiment, the charging unit 202 includes a charging electrode 221 provided with an insulator layer 207 on the surface, a charging power source 222, and a grounding unit 223. In addition, the outflow body 211 also functions as a part of the charging means 202.

  The charging electrode 221 is a member for inducing charges to the efflux body 211 that is arranged in the vicinity and is grounded when the charging electrode 221 itself becomes a high voltage or a low voltage with respect to the ground, and surrounds the front end portion of the efflux body 211. It is an annular member arranged like this. When a positive voltage is applied to the charging electrode 221, a negative charge is induced in the outflow body 211, and when a negative charge is applied to the charging electrode 221, a positive charge is induced in the outflow body 211. . The charging electrode 221 also functions as a wind tunnel body 209 that guides the gas flow from the gas flow generation means 203 to the guide body 206.

  The size of the charging electrode 221 needs to be larger than the diameter of the outflow body 211, and the diameter is preferably employed in the range of 200 mm or more and 800 mm or less. The shape of the charging electrode 221 is not limited to an annular shape, and may be a polygonal annular member having a polygonal shape.

  The insulator layer 207 is a layer made of an insulator provided on the inner peripheral surface of the charging electrode 221 facing the outflow body 211. The insulator layer 207 is a member provided in order to change the charged state of the nanofiber 301 in the vicinity of the inner peripheral surface of the charging electrode 221. In this embodiment, the insulator layer 207 is a thin sheet-like member that covers the entire inner peripheral surface of the charging electrode 221. The material constituting the insulator layer 207 may be an insulator, but in particular, a material made of an insulator that is more easily charged positively than rayon or more negatively charged than polyester is preferable.

  Here, the insulator that is more easily charged positively than the rayon is an insulator when the rayon is negatively charged and the insulator is positively charged as a result of rubbing the rayon and the insulator. Specific examples of the insulator that is more positively charged than rayon include wool, mica, glass, human hair, asbestos and the like. Alternatively, an insulator that is more negatively charged than polyester refers to an insulator when the polyester is positively charged and the insulator is negatively charged as a result of rubbing the polyester and the insulator. Specifically, as an insulator that is more easily negatively charged than polyester, acrylic, vinyl chloride, fluorine-based resin (for example, polytetrafluoroethylene, tetrafluoroethylene-hexafluoropropylene copolymer, tetrafluoroethylene- Examples thereof include perfluoroalkoxyethylene copolymer, ethylene-tetrafluoroethylene copolymer, chlorotrifluoroethylene, polyvinylidene fluoride, polychlorotrifluoroethylene, etc.) and Teflon (registered trademark).

  In the present embodiment, Teflon (registered trademark) is used as the material of the insulator layer 207, and the thickness of the insulator layer 207 is 0.2 mm.

  As in this embodiment, when the insulator layer 207 is formed of an insulator that is easily negatively charged and a negative potential is applied to the charging electrode 221, the insulating layer 207 is near the inner peripheral surface of the charging electrode 221. The positively charged nanofiber 301 (raw material liquid 300) flying upward is converted into a negatively charged state and repels the charged electrode 221.

  In the present embodiment, the insulator layer 207 covers the entire inner peripheral surface of the charging electrode 221, but the insulator layer 207 may be a part of the inner peripheral surface of the charging electrode 221.

  The charging power source 222 is a power source that can apply a high voltage to the charging electrode 221. In general, the charging power source 222 is preferably a DC power source. In particular, a direct-current power supply is preferable when the charged polarity of the nanofiber 301 to be generated is not affected, or when the charged nanofiber 301 is collected and collected on the electrode. Further, when the charging power source 222 is a DC power source, the voltage applied to the charging electrode 221 by the charging power source 222 is preferably set from a value in the range of 10 KV or more and 200 KV or less. When a negative voltage is applied to the charging power source 222, the polarity of the applied voltage becomes negative. In particular, the electric field strength between the effluent 211 and the charging electrode is important, and it is preferable to arrange the applied voltage and the charging 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 outflow body 211 and can maintain the outflow body 211 at the ground potential. One end of the grounding means 223 functions as a brush so that the electrical connection state can be maintained even when the outflow body 211 is in a rotating state, and the other end is connected to the ground.

  If an induction method is employed for the charging means 202 as in the present embodiment, it is possible to apply a charge to the raw material liquid 300 while maintaining the effluent 211 at the ground potential. If the outflow body 211 is in a ground potential state, it is not necessary to electrically insulate members such as the rotating shaft body 212 and the motor 213 connected to the outflow body 211 from the outflow body 211, and the outflow unit 201 has a simple structure. Can be adopted, which is preferable.

  As the charging means 202, a charge may be applied to the raw material liquid 300 by connecting a power source to the effluent 211, maintaining the effluent 211 at a high voltage, and grounding the charging electrode 221. In addition, the outflow body 211 is formed of an insulator, and an electrode that is in direct contact with the raw material liquid 300 stored in the outflow body 211 is disposed inside the outflow body 211, and charges are applied to the raw material liquid 300 using the electrodes. It may be a thing. When an electrode is arranged directly on the effluent 211 or directly on the raw material liquid, the polarity of the charge charged in the raw material liquid is the same as the polarity of the applied voltage.

  The gas flow generation means 203 is a device that generates a gas flow for changing the flight direction of the raw material liquid 300 flowing out from the outflow body 211 to the direction guided by the guide body 206. The gas flow generation means 203 is provided on the back of the motor 213 and generates a gas flow from the motor 213 toward the tip of the effluent 211. The gas flow generating means 203 can generate wind power that can change the raw material liquid 300 in the axial direction until the raw material liquid 300 flowing out from the outlet body 211 reaches the charging electrode 221 in the radial direction. It has become. 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 gas flow generation unit 203.

  Note that the gas flow generating means 203 may be constituted by another blower such as a sirocco fan. Further, the direction of the raw material liquid 300 that has flowed out by introducing high-pressure gas may be changed. Further, a gas flow may be generated inside the guide body 206 by the suction means 102 or the like. In this case, the gas flow generating means 203 does not have a device that actively generates a gas flow. However, in the case of the present invention, the gas flow is generated when the gas flow is generated inside the guide body 206. It is assumed that the means 203 exists. In addition, there is a gas flow generating means in which a gas flow is generated inward of the wind tunnel body 209 and the guide body 206 by suction by the suction means 102 without the gas flow generating means 203. It shall be. Further, when a gas flow is generated inside the wind tunnel body 209 or the guide body 206 by suction by the suction means 102 without the gas flow generation means 203, the suction means 102 functions as the gas flow generation means. It is assumed that

  The wind tunnel body 209 is a conduit that guides the gas flow generated by the gas flow generation means 203 to the vicinity of the outflow body 211. The gas flow guided by the wind tunnel body 209 intersects the raw material liquid 300 that has flowed out of the outflow body 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 gas flow generation means 203 does not hit the outflow hole 216. In this embodiment, as the gas flow control means 204, An air passage body that guides the gas flow so as to flow in a predetermined region is employed. Since the gas flow does not directly hit the outflow hole 216 by the gas flow control means 204, the raw material liquid 300 flowing out from the outflow hole 216 is prevented from evaporating early and blocking the outflow hole 216 as much as possible. The liquid 300 can be kept flowing out stably. The gas flow control means 204 may be a wall-shaped windbreak wall that is arranged on the windward side of the outflow hole 216 and prevents the gas flow from reaching the vicinity of the outflow hole 216.

  The heating unit 205 is a heating source that heats the gas constituting the gas flow generated by the gas flow generation unit 203. In the case of the present embodiment, the heating means 205 is an annular heater arranged inside the guide body 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 flowing out into the space is accelerated in evaporation, and nanofibers can be efficiently manufactured.

  The guide body 206 is a wind tunnel that guides the nanofiber 301 emitted from the emission means 200 to a predetermined place. The guide body 206 in the present embodiment is a cylindrical body, has the same opening shape as that of the emitting means 200 on the side where the nanofibers 301 are emitted, and is arranged in series with the emitting means 200.

  In order to stabilize the charged state of the nanofiber 301, a sheet-like member made of the same material as the insulator layer 207 is also attached to the inner wall surface of the guide body 206.

  The material of the guide base 208 is not particularly limited, but in the case of the present embodiment, transparent vinyl chloride is used. This is because it is suitable for visually observing the state of the nanofiber 301 conveyed inside the guide body 206.

  Returning to FIG.

  The diffusing unit 240 is a conduit connected to the guide body 206 and diffusing the nanofibers 301 in a high density state widely and evenly into a low density state. The space in which the nanofibers 301 are guided is smoothly and continuously. By expanding, it is a hood-like member that gradually reduces the velocity of the gas flow conveying the nanofiber 301 and the velocity of the nanofiber 301.

  The collecting unit 110 is a device for collecting the nanofibers 301 emitted from the diffusing unit 240, and includes a member 101 to be deposited, a transfer unit 104, and a supply unit 111.

  The member to be deposited 101 is a member on which nanofibers 301 that are manufactured and flying by electrostatic explosion are deposited. In the case of the present embodiment, the member to be deposited 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 member 101 to be deposited, 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 member 101 to be deposited because the peelability when the deposited nanofiber 301 is peeled off from the member 101 to be deposited is improved. The member 101 to be deposited is supplied from the supply unit 111 in a state of being wound in a roll shape.

  The transfer means 104 is a device that can transfer the deposition target member 101. In the case of the present embodiment, the member to be deposited 101 is conveyed together with the nanofibers 301 to be pulled out from the supply means 111 while winding the long member to be deposited 101. The transfer means 104 is capable of winding the nanofibers 301 deposited in the form of a nonwoven fabric together with the member to be deposited 101.

  The attracting means 120 is a device for attracting the nanofiber 301 flying in the space to a predetermined place. Examples of a method for attracting the nanofiber 301 include a method for attracting the nanofiber 301 by sucking a gas flow and a method for attracting the charged nanofiber 301 by an electric field (electric field). In the case of the present embodiment, the attracting means 120 employs a device that can selectively and simultaneously implement a method of attracting a gas flow and a method of attracting with an electric field, An attraction electrode 121 and an attraction power source 122 are provided.

  The suction means 102 is a device that forcibly sucks the gas flow that passes through the deposition target member 101. In the present embodiment, the suction means 102 includes a funnel-shaped hood 103 and a blower 105. The blower 105 is a blower such as a sirocco fan or an axial fan, and is a device that can generate a gas flow from the deposition target member 101 toward the blower 105.

  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.

  The attracting electrode 121 is an electrode for generating an electric field for attracting the charged nanofiber 301. In the case of the present embodiment, a metal net capable of passing a gas flow is employed.

  The attraction power source 122 is a DC power source that can maintain the attraction electrode 121 at a predetermined voltage and polarity. In the case of the present embodiment, the attraction power source 122 is a DC power source that can freely change the voltage and polarity in the range of 0 V (grounded state) to 200 KV or less.

  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 body 206 and the wind tunnel body 209 by the gas flow generation means 203 (gas flow generation step). On the other hand, the gas flow generated in the guide body 206 is sucked by the suction means 102. In the above state, the air volume in the guide body 206 was adjusted to be 30 m ³ / min.

  Next, the raw material liquid 300 is supplied to the outflow body 211 of the outflow means 201 (raw material liquid supply step). 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 into the effluent 211 from the other end of the effluent 211. Specifically, PVA (polyvinyl alcohol) is selected as the material of the nanofiber 301, and the raw material liquid 300 is a solvent in which water is used as a solvent and PVA is dissolved in water at 10% by weight.

  Next, while supplying electric charge to the raw material liquid 300 stored in the effluent 211 by the charging power source 222 (charging process), the effluent 211 is rotated by the motor 213 and charged from the outflow hole 216 by centrifugal force. 300 flows out (outflow process). Specifically, an effluent 211 having a diameter of 60 mm was used. The number of outflow holes 216 provided in the outflow body 211 was 108, and the hole diameter was 0.3 mm. Moreover, the raw material liquid 300 was made to flow out by rotating the outflow body 211 at 2000 rpm. On the other hand, the charging electrode 221 having an inner diameter of Φ600 mm was used, and the charging electrode 221 was made negative 60 KV with respect to the ground potential by the charging power source 222. As a result, positive charge is induced in the effluent 211, and the positively charged raw material liquid 300 flows out.

  The raw material liquid 300 that has flowed radially in the radial direction of the outflow body 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 nanofiber 301 emitted from the emission means 200 as described above is introduced into the guide body 206. The nanofiber 301 is guided while being conveyed in the gas flow inside the guide body 206 (conveying step).

  Here, since a negative voltage is applied to the charging electrode 221, a positive charge is induced in the outflow body 211. Therefore, the raw material liquid 300 flowing out from the outflow body 211 is positively charged. Further, the nanofiber 301 manufactured by electrostatic explosion due to the repulsive force between positive charges is also positively charged. The flight direction of the nanofiber 301 is changed in a direction toward the deposition target member 101 by the gas flow by the gas flow generation unit 203, but a part of the nanofiber 301 is directed to the charging electrode 221 having a reverse polarity. In the vicinity of the insulator layer 207, the nanofiber 301 changes to zero or negative charge, and is transported to the gas flow without being attached to the charging electrode 221 and heading toward the deposition target member 101. .

  Although the detailed mechanism of this phenomenon is unknown, the atmosphere (air) in the vicinity of the inner peripheral surface of the charging electrode 221 is strongly negatively charged due to the presence of the insulator layer 207 made of a material that is easily negatively charged. In particular, a negative voltage is applied to the charging electrode 221, and negative charges are emitted from the insulator layer 207 through the voltage, and the air in the vicinity of the insulator layer 207 of the charging electrode 221 is radiated. It is considered that an air layer having a negative charge is maintained. Then, it is considered that the negatively charged atmosphere acts on the nanofiber 301 and changes the charging polarity.

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

  In this state, the suction means 102 disposed behind the deposition target member 101 sucks the gas flow together with the solvent that is the evaporated component, and attracts the nanofiber 301 onto the deposition target member 101 (attraction process). . In addition, an electric field is generated by the attracting electrode 121 to which a voltage is applied, and the nanofiber 301 is attracted by the electric field.

  As described above, the nanofibers 301 are deposited on the deposition target member 101. Since the member 101 to be deposited is slowly transferred by the transfer means 104, the nanofiber 301 is also collected as a long belt-like member extending in the transfer direction.

  As described above, when the insulator layer 207 is provided on the inner peripheral surface of the charging electrode 221, most of the nanofibers 301 reach the deposition target member 101 without the manufactured nanofibers 301 adhering to the charging electrode 221. To do. Accordingly, the nanofibers 301 can be collected with high efficiency, and high production efficiency of the nanofibers 301 can be obtained.

  Specifically, the collection rate, which is the ratio of the amount of resin collected as nanofibers to the amount of charged resin, is 30 to 40% in the case of the nanofiber manufacturing apparatus 100 in which the insulator layer 207 is not provided. In contrast, in the case of the nanofiber manufacturing apparatus 100 according to the present embodiment in which the insulator layer 207 is provided, the collection rate is a value exceeding 95%.

  Here, as a polymer substance constituting the nanofiber 301, polypropylene, polyethylene, polystyrene, polyethylene oxide, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, poly-m-phenylene terephthalate, poly-p-phenylene isophthalate, Polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, polyvinyl chloride, polyvinylidene chloride-acrylate copolymer, polyacrylonitrile, polyacrylonitrile-methacrylate copolymer, polycarbonate, polyarylate, polyester carbonate, polyamide, aramid , Polyimide, polycaprolactone, polylactic acid, polyglycolic acid, collagen, polyhydroxybutyric acid, polyvinyl acetate Le, polypeptides, and the like, and copolymers 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, N, N-dimethylacetamide, dimethylsulfo Examples thereof include oxide, pyridine, water and the like. Moreover, the kind selected from the above may be used, and a plurality of kinds may be mixed. In addition, the above is an illustration and this invention is not limited to the said solvent.

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. In addition, the above is an illustration and this invention is not limited to the said additive.

  The mixing ratio of the solvent and the polymer material varies depending on the solvent and the polymer material, but the amount of the solvent is preferably between about 60 wt% and 98 wt%.

  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% by weight or more of the solvent as described above, and generates an electrostatic explosion. It becomes 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 above embodiment, the raw material liquid 300 is caused to flow out using centrifugal force, but the present invention is not limited to this. For example, as shown in FIG. 4, a nozzle head 210 as an outflow body provided with a large number of outflow holes 216 is disposed on one wall surface of a wind tunnel body 209 having a rectangular cross section, and a charging electrode 221 is disposed on the opposite surface of the wind tunnel body 209. The charging means 202 is obtained by charging the raw material liquid by generating an electric field by providing a potential difference between the outflow hole 216 and the charging electrode 221. Further, a gas flow generating means 203 is provided at one of the open ends of the wind tunnel body 209. Further, a guide body 206 having the same cross-sectional shape as that of the wind tunnel body 209 may be disposed at a predetermined interval from the discharge means 200.

  Note that although the case where the nanofiber 301 is positively charged and the insulator layer 207 provided on the inner peripheral surface of the charging electrode 221 is negatively charged has been described in this embodiment mode, the present invention is not limited thereto. Is not to be done. For example, the effluent 211 may be negatively charged by applying a positive voltage to the charging electrode 221, and the raw material liquid 300 and the nanofiber 301 may be negatively charged. In this case, the material of the insulator layer 207 is made of rayon or a material that is more positively charged than rayon, so that the charged state is opposite to that in the above embodiment, and the nanofiber 301 is not attached to the charging electrode 221.

  That is, the material of the insulator layer 207 on the surface of the charging electrode 221 can be determined from the charging polarity of the nanofiber 301 that has flowed out of the outflow hole 216. When the nanofiber 301 has a positive charging polarity, an insulator that is more negatively charged than polyester is selected, and when the nanofiber 301 has a negative charging polarity, it is more positively charged than rayon. It is desirable to select an insulator.

  The present invention can be applied to the manufacture of nanofibers by electrostatic explosion (electrospinning method) and the manufacture of nonwoven fabrics on which the nanofibers are deposited.

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 sectional drawing which shows another aspect of the discharge | release means.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Nanofiber manufacturing apparatus 101 Deposited member 102 Suction means 103 Hood 104 Transfer means 105 Blower 106 Solvent recovery apparatus 110 Collecting means 111 Supply means 120 Attracting means 121 Attracting electrode 122 Attracting power source 200 Discharge means 201 Outflow means 202 Charging means 203 Generation means 204 Gas flow control means 205 Heating means 206 Guide body 207 Insulator layer 209 Wind tunnel body 210 Nozzle head 211 Outflow body 212 Rotating shaft body 213 Motor 215 Bearing 216 Outflow hole 217 Supply path 221 Charging electrode 222 Charging power supply 223 Grounding means 240 Diffusion means 300 Raw material liquid 301 Nanofiber

Claims (7)

A nanofiber manufacturing apparatus that electrostatically explodes a raw material liquid in a space to manufacture nanofibers,
An outflow body having an outflow hole for allowing the raw material liquid to flow out into the space;
A charging electrode that is disposed at a predetermined interval from the effluent, and to which a predetermined voltage is applied to the effluent;
An insulator layer provided on the surface of the charging electrode facing the outflow body;
A charging power source for setting a predetermined voltage between the outflow body and the charging electrode;
A nanofiber manufacturing apparatus comprising: a gas flow generating means for generating a gas flow for transporting a nanofiber manufactured from the raw material liquid flowing out from the outflow body.   2. The nanofiber manufacturing apparatus according to claim 1, wherein the insulator layer is made of an insulator that is more easily charged positively than rayon or more negatively charged than polyester.   The nanofiber manufacturing apparatus according to claim 2, wherein the insulator layer is made of a fluorine-based resin. further,
A collection means for collecting nanofibers produced in space;
The nanofiber manufacturing apparatus according to claim 1, further comprising an attracting unit that attracts the nanofiber to the collecting unit. A nanofiber manufacturing method for manufacturing nanofibers by electrostatically exploding a raw material liquid in a space,
An outflow step for allowing the raw material liquid to flow out into the space from an outflow body having an outflow hole;
A charging electrode disposed at a predetermined interval from the effluent body, wherein a predetermined voltage is applied to the effluent body on a charging electrode provided with an insulator layer on the surface of the charging electrode facing the effluent body. Charging process to be applied;
And a gas flow generating step of generating a gas flow for transporting the nanofiber manufactured by electrostatic explosion of the raw material liquid in the space. further,
A collecting step of collecting nanofibers guided by the guiding body by a collecting means;
The nanofiber manufacturing method according to claim 5, further comprising an attracting step of attracting the nanofibers to the collecting means. further,
When the raw material liquid contains rayon or a resin that is more easily charged positively than rayon, in the charging step, the raw material liquid is charged positively,
The nanofiber manufacturing method according to claim 5, wherein when the raw material liquid includes polyester or a resin that is more negatively charged than polyester, the raw material liquid is negatively charged in the charging step.

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