Nozzle head and electrospinning apparatus

Abstract

To suppress filming of ultra fine fibers in a collection member.SOLUTION: A nozzle head 10 includes a spinning hole 21 open to an outer peripheral surface, a cylindrical head main body 11 having feeding passages 14, 15 for feeding spinning liquid L including a solvent to the spinning hole 21, and a spinning electrode 22 for charging the spinning liquid L. By an electric potential difference between the spinning electrode 22 and a collector electrode 33 disposed on the outside of the nozzle head 10, the spinning liquid L is ejected from the spinning hole 21 and collected in a collection member 35 in a form of an ultra fine fiber. The nozzle head 10 is assembled with an air discharge port 29 that discharges air A so as to be in contact with a jet flow J of the spinning liquid L from the spinning hole 21 to the collection member 35.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present invention relates to a nozzle head and an electrospinning apparatus.

Background Art

[0002] Patent Document 1 discloses an electrospinning apparatus that produces a fiber aggregate by ejecting a spinning solution from a spinning hole of a nozzle head by means of a potential difference. The spinning solution is a resin material dissolved in a solvent. In the process of the spinning solution moving toward the collecting member, the electric field density of the spinning solution increases as the solvent evaporates, and electrorepulsion causes ultrafine fibrillation. When the ultrafine fibers are collected on the sheet-like collecting member, a fiber aggregate composed of the ultrafine fibers is produced. Examples of the fiber aggregate include nonwoven fabrics used as separators for secondary batteries. This electrospinning apparatus has the advantage of easily generating ultrafine fibers.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] When the spinning solution is collected on the collecting member and the solvent remains attached to the ultrafine fibers, the ultrafine fibers adhere to each other on the surface of the collecting member and form a film. When the fiber aggregate formed into a film is used as a separator, the ion passage resistance in the secondary battery increases, causing a decrease in the output of the secondary battery.

[0005] The present disclosure has been completed based on the above circumstances, and an object thereof is to suppress the film formation of ultrafine fibers on the collecting member.

Means for Solving the Problems

[0006] The nozzle head of the first disclosure is a cylindrical head body having a spinning hole opening on the outer peripheral surface and a supply path for supplying a spinning solution containing a solvent to the spinning hole, and a spinning electrode for charging the spinning solution, and the spinning solution is ejected from the spinning hole and collected by a collecting member in a state of being nanofibered by a potential difference between the spinning electrode and a collector electrode disposed outside the head body. The nozzle head is equipped with an air discharge port for discharging air so as to contact the jet of the spinning solution from the spinning hole to the collecting member.

[0007] The electrospinning apparatus of the second disclosure is a nozzle head, and a collector electrode disposed outside the nozzle head, wherein the nozzle head has a cylindrical head body having a spinning hole opening on the outer peripheral surface and a supply path for supplying a spinning solution containing a solvent to the spinning hole, and a spinning electrode for charging the spinning solution, and the spinning solution is ejected from the spinning hole and collected by a collecting member in a state of being nanofibered by a potential difference between the spinning electrode and the collector electrode, and the nozzle head is provided with an air discharge port for discharging air so as to contact the jet of the spinning solution from the spinning hole to the collecting member.

Advantages of the Invention

[0008] According to the first disclosure and the second disclosure, it is possible to suppress the formation of a film of nanofibers on the collecting member.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

[0010] Here, desirable exemplary embodiments of the present disclosure are shown. Combinations of the following multiple exemplary embodiments arbitrarily within a range that does not cause contradictions are also included in the embodiments for carrying out the invention.

[0011] The nozzle head of the first disclosure has: (1) a cylindrical head body having a spinning hole opening on an outer peripheral surface and a supply path for supplying a spinning solution containing a solvent to the spinning hole, and a spinning electrode for charging the spinning solution. Due to the potential difference between the spinning electrode and a collector electrode disposed outside the head body, the spinning solution is ejected from the spinning hole and collected by a collecting member in a state of being nanofibered. The nozzle head is provided with an air discharge port for discharging air so as to contact the jet of the spinning solution from the spinning hole to the collecting member. According to the first disclosure, since the air discharged from the air discharge port contacts the jet of the spinning solution, evaporation of the solvent in the spinning solution is promoted, so that it is possible to suppress the nanofibers collected by the collecting member from being formed into a film by the solvent.

[0012] (2) In (1), it is preferable that the air discharge port opens so as to surround the ejection path of the spinning solution ejected from the spinning hole. According to this configuration, the air discharged from the air discharge port can be made to follow the jet of the spinning solution.

[0013] (3)(2) In this case, it is preferable to provide an air tube that surrounds the head body, and the space between the head body and the air tube functions as an air flow path for supplying the air to the air discharge port. According to this configuration, since the air and the spinning solution do not mix until the spinning solution is ejected from the spinning holes, the spinning solution can be stably ejected from the spinning holes.

[0014] (4)(3) In this case, it is preferable that the inner diameter of the air discharge port is larger than the inner diameter of the spinning holes. According to this configuration, there is no risk that the shape of the jet of the spinning solution is disrupted by the air.

[0015] (5)(4) In this case, it is preferable that the opening shapes of the spinning holes and the air discharge port are concentric circles. According to this configuration, since the air can surround the jet of the spinning solution over the entire circumference, the effect of promoting the evaporation of the solvent is excellent.

[0016] The electrospinning apparatus of the second disclosure is (6) It includes a nozzle head and a collector electrode disposed outside the nozzle head. The nozzle head has a cylindrical head body having a spinning hole that opens on the outer peripheral surface and a supply path for supplying a spinning solution containing a solvent to the spinning hole, and a spinning electrode for charging the spinning solution. Due to the potential difference between the spinning electrode and the collector electrode, the spinning solution is ejected from the spinning holes and collected by a collecting member in a state of being nanofibrized. The nozzle head is provided with an air discharge port for discharging air so as to contact the jet of the spinning solution from the spinning holes to the collecting member. According to the second disclosure, since the air discharged from the air discharge port contacts the jet of the spinning solution, the evaporation of the solvent in the spinning solution is promoted, so that it is possible to suppress the formation of a film by the solvent on the nanofibers collected by the collecting member.

[0017] <Embodiment 1> Embodiment 1 embodying the present disclosure will be described with reference to FIGS. 1 to 5. Note that the present invention is not limited to these examples, but is indicated by the claims, and is intended to include all modifications within the meaning and scope equivalent to the claims. In the present Embodiment 1, regarding the front-rear direction, the F direction in FIGS. 2 to 4 is defined as the front. Regarding the up-down direction, the H direction in FIGS. 1, 2, 4, and 5 is defined as the up. Regarding the left-right direction, the R direction in FIGS. 1, 3, and 5 is defined as the right.

[0018] The electrospinning apparatus shown in FIGS. 1 and 2 is an apparatus for producing a fiber aggregate F by electrospinning ultrafine fibers (not shown) from a spinning solution L and collecting the ultrafine fibers on a collecting member 35. Examples of the fiber aggregate F include nonwoven fabrics used as separators for secondary batteries (not shown).

[0019] The spinning solution L has a resin material (not shown) that forms ultrafine fibers as a solute, and this solute is dissolved or dispersed in a volatile solvent (not shown). As the solute, for example, synthetic resins such as polyacrylonitrile (PAN), polypropylene (PP), and polyethylene (PE) are used. As the solvent, for example, compounds such as N,N-dimethylacetamide (DMA), N,N-dimethylformamide (DMF), and tetrahydrofuran (THF) are used.

[0020] The electrospinning apparatus includes a nozzle head 10, a tank 19, a pump 20, a DC power supply 24, a transport device 30 for transporting the collecting member 35, and a collector electrode 33. As shown in FIGS. 3 to 5, the nozzle head 10 includes a head body 11, a spinning electrode 22, and an air tube 25. The head body 11 stores an amount of spinning solution L necessary for electrospinning and supplies the spinning solution L to a spinning hole 21 described later. The head body 11 as a whole has a cylindrical shape with its axis S in the horizontal direction (front-rear direction). The axis S of the head body 11 is parallel to the width direction of the collecting member 35 described later.

[0021] The head body 11 has a double-tube structure composed of a cylindrical inner tube 12 and a concentric cylindrical outer tube 13 that surrounds the inner tube 12 concentrically. The inner tube 12 and the outer tube 13 are formed of, for example, a solvent-resistant resin. The solvent-resistant resin is, for example, a synthetic resin such as a fluororesin (PTFE).

[0022] The internal space of the inner tube 12 functions as a first supply path 14 for storing and flowing the spinning solution L. The space between the outer peripheral surface of the inner tube 12 and the inner peripheral surface of the outer tube 13 functions as a second supply path 15 for storing and flowing the spinning solution L. A plurality of inner holes 16 spaced apart in the axial direction of the axis S are formed at the lower end of the inner tube 12. The inner holes 16 penetrate the inner tube 12 in the vertical direction and communicate the first supply path 14 and the second supply path 15.

[0023] The downstream ends of two pipes 18 are individually connected to the supply ports 17 at both ends of the inner tube 12. In FIG. 1, for the sake of convenience, only one of the two pipes 18 is shown. The upstream end of the pipe 18 is connected to a tank 19 in which the spinning solution L is stored. A pump 20 for pumping the spinning solution L in the tank 19 to the nozzle head 10 is provided in the pipe 18.

[0024] A plurality of spinning holes 21 spaced apart in the axial direction of the axis S are formed at the upper end of the outer tube 13. The spinning holes 21 penetrate the outer tube 13 in the vertical direction and communicate the second supply path 15 and the outside of the head body 11 (outer tube 13). In a plan view of the nozzle head 10 seen from above, the spinning holes 21 are circular. The inner diameter of the spinning holes 21 is preferably 0.5 mm to 2.0 mm, for example, 1.0 mm.

[0025] The spinning electrode 22 has a smaller diameter than the inner diameter of the inner tube 12 and is made of a conductive wire rod (wire-shaped member) made of a metal such as stainless steel. The wire diameter of the spinning electrode 22 is, for example, 0.9 mm. The spinning electrode 22 is housed in the head body 11 and is formed in a spiral shape (coil shape) centered on the axis S of the head body 11. The spinning electrode 22 is entirely immersed in the spinning solution L within the head body 11. That is, the entire outer surface of the spinning electrode 22 is in contact with the spinning solution L within the head body 11. The spinning electrode 22 is housed within the second supply passage 15 and is arranged along the inner peripheral surface of the outer tube 13. The pitch of the spiral of the spinning electrode 22 is the same as the pitch in the front line direction of the spinning holes 21. The spinning electrode 22 is shaped such that it passes through all of the spinning holes 21 in a plan view. The spinning electrode 22 is connected to a DC power supply 24 via a wiring 23 at the end of the outer tube 13.

[0026] The air tube 25 is a cylindrical member made of synthetic resin. The inner diameter of the air tube 25 is larger than the outer diameter of the outer tube 13, and the air tube 25 is arranged to concentrically surround the outer tube 13. The cylindrical space between the outer peripheral surface of the outer tube 13 and the inner peripheral surface of the air tube 25 functions as an air flow path 26 for flowing air A. Both ends of the air flow path 26 are airtightly closed. Air A is supplied to the air flow path 26 from an air supply source 28 connected via an air supply passage 27. The humidity of the air A supplied to the air flow path 26 is set lower than that within the booth or housing (not shown) where the electrospinning device is installed.

[0027] At the upper end of the air tube 25, the same number of air discharge ports 29 as the spinning holes 21 are formed. In a plan view, the opening shape of the air discharge port 29 is circular. In a plan view, each air discharge port 29 opens concentrically with the spinning hole 21. The inner diameter of the air discharge port 29 is larger than the inner diameter of the spinning hole 21. The air discharge port 29 is an opening that communicates the air flow path 26 with the outside of the air tube 25 (the outside of the nozzle head 10). The air discharge port 29 and the air flow path 26 communicate with the second supply passage 15 via the spinning hole 21.

[0028] The conveying device 30 is a device for horizontally (left - right direction) conveying the collecting member 35 above the nozzle head 10. The collecting member 35 is a long sheet - shaped member. The conveying device 30 is configured to include a delivery roller 31 and a take - up roller 32 that are arranged at the same height and spaced apart in the left - right direction. The collecting member 35 is wound around the delivery roller 31. The leading end of the collecting member 35 in the conveying direction is wound around the take - up roller 32. In the spinning process, the collecting member 35 wound around the delivery roller 31 is wound around the take - up roller 32 while moving horizontally (right direction) between the two rollers 31 and 32.

[0029] The collector electrode 33 is arranged between the delivery roller 31 and the take - up roller 32. The collector electrode 33 is arranged along the upper surface of the collection region 36 that is horizontally stretched between the two rollers 31 and 32 in the collecting member 35. The positive electrode of the DC power supply 24 is connected to the spinning electrode 22, and the negative electrode is connected to the collector electrode 33.

[0030] Next, a method for manufacturing the fiber aggregate F will be described. The first supply path 14 and the second supply path 15 in the nozzle head 10 are filled with the spinning solution L. When the electrospinning device operates, the collecting member 35 is horizontally fed at a constant speed from the delivery roller 31 toward the take - up roller 32 in a state of being in contact with or approaching the lower surface of the collector electrode 33. By driving the pump 20, the spinning solution L in the tank 19 is supplied to the first supply path 14 of the inner tube 12, passes through the inner hole 16, and is supplied to the second supply path 15. The second supply path 15 functions as a buffer space for the spinning solution L discharged from the inner hole 16.

[0031] The spinning solution L in the second supply path 15 is charged by contacting the spinning electrode 22, and is attracted to the collector electrode by the electrostatic force (Coulomb force) caused by the potential difference between the spinning electrode 22 and the collector electrode 33, and is ejected upward from the spinning holes 21. The spinning solution L ejected from the spinning holes 21 passes through the air discharge port 29 and becomes a jet J that rises toward the collecting member 35.

[0032] Since the jet J of the spinning solution L ejected from the spinning holes 21 is charged by contact with the spinning electrode 22, inside the jet J, the spinning solution L becomes ultrafine fibers (nanofibers) due to the repulsive force of the electric charges accumulated in the spinning solution L. Since the surface area of the ultrafine fibers is large compared to their volume, the solvent in the ultrafine fibers evaporates efficiently. Also, due to this evaporation, the volume of the ultrafine fibers decreases and the charge density becomes higher. Therefore, the repulsive force between the charged ultrafine fibers increases, and each ultrafine fiber splits into even finer ultrafine fibers.

[0033] While going through such a process, ultrafine fibers are spun, and the spun ultrafine fibers are collected on the lower surface of the collection member 35, thereby forming the fiber aggregate F. The collection member 35 on which the fiber aggregate F is laminated is wound by the winding roller 32. When using the fiber aggregate F, the fiber aggregate F is peeled off from the collection member 35 while pulling out the collection member 35 from the winding roll.

[0034] In the above electrospinning process, the air A supplied to the air flow path 26 is ejected from the air discharge port 29 above the outside of the nozzle head 10 (air tube 25). The air discharge port 29 is arranged concentrically with the spinning solution L, and since the inner diameter of the air discharge port 29 is larger than the inner diameter of the spinning holes 21, the air A discharged from the air discharge port 29 surrounds the jet J of the spinning solution L over the entire circumference, and while being in contact with the outer peripheral surface of the jet J, rises along with the jet J. Since this air A is a low-humidity gas that is drier than the atmosphere of the rising path of the jet J from the nozzle head 10 to the collection member 35, it promotes the evaporation of the solvent by coming into contact with the ultrafine fibers in the jet J.

[0035] When the jet J is collected by the collecting member 35 to form the fiber aggregate F, if a large amount of solvent remains attached to the ultrafine fibers, the ultrafine fibers adhere to each other and form a film. On the other hand, in the electrospinning apparatus of the present embodiment, the ultrafine fibers in the jet J are in a state where the amount of attached solvent is small due to contact with the low-humidity air A. Therefore, when they are collected by the collecting member 35 to form the fiber aggregate F, it is difficult to adhere to other ultrafine fibers. Accordingly, the fiber aggregate F on the surface of the collecting member 35 is unlikely to be in a state of being formed into a film due to the adhesion of the ultrafine fibers to each other. Thus, a good nonwoven fabric can be obtained.

[0036] The electrospinning apparatus of the first embodiment includes a nozzle head 10 and a collector electrode 33 disposed outside (above) the nozzle head 10. The nozzle head 10 has a head body 11 and a spinning electrode 22. The head body 11 is a cylindrical member having a spinning hole 21 that opens on the outer peripheral surface and supply paths (a first supply path 14 and a second supply path 15) for supplying the spinning solution L containing the solvent to the spinning hole 21. The spinning electrode 22 is a member that charges the spinning solution L. The nozzle head 10 is configured to collect the spinning solution L from the spinning hole 21 and eject it in a state of being formed into ultrafine fibers and collect it on the collecting member 35 due to the potential difference between the spinning electrode 22 and the collector electrode 33. The nozzle head 10 is provided with an air discharge port 29 for discharging air A so as to come into contact with the jet J of the spinning solution L from the spinning hole 21 to the collecting member 35. According to this configuration, the air A discharged from the air discharge port 29 comes into contact with the jet J of the spinning solution L, thereby promoting the evaporation of the solvent in the spinning solution L. Therefore, it is possible to suppress the formation of a film by the solvent on the ultrafine fibers collected on the collecting member 35.

[0037] Since the air outlet 29 is open so as to surround the ejection path (jet J) of the spinning solution L ejected from the spinning holes 21, the air A ejected from the air outlet 29 can be made to follow along the jet J of the spinning solution L. The nozzle head 10 is provided with an air tube 25 that surrounds the head body 11. The space between the head body 11 and the air tube 25 functions as an air flow path 26 for supplying the air A to the air outlet 29. According to this configuration, since the air A and the spinning solution L do not mix before the spinning solution L is ejected from the spinning holes 21, the spinning solution L can be stably ejected from the spinning holes 21.

[0038] Since the inner diameter of the air outlet 29 is larger than the inner diameter of the spinning holes 21, there is no risk that the shape of the jet J of the spinning solution L will be disrupted by the air A. Since the opening shape of the spinning holes 21 and the opening shape of the air outlet 29 are concentric circles, the air A can surround the jet J of the spinning solution L over the entire circumference. As a result, the electrospinning apparatus and the nozzle head 10 of the first embodiment are excellent in the effect of promoting the evaporation of the solvent.

[0039] <Other Embodiments> The present invention is not limited to the embodiments described above with reference to the description and the drawings. For example, the following embodiments are also included in the technical scope of the present invention. · The air outlet may be open to the outside of the nozzle head. · The region where the air contacts the jet of the spinning solution may be only a part of the ejection path of the spinning solution from the spinning holes to the collecting member. Specifically, it may be only the region near the spinning holes, or only the region near the collecting member. · The opening shape of the spinning holes may be non-circular. · The opening shape of the air outlet may be non-circular. · When viewed in the radial direction of the nozzle head, the spinning holes and the air outlet may have an eccentric positional relationship. · The air may be brought into contact with the spinning solution before the spinning solution reaches the spinning holes. · The inner diameter of the spinning holes and the inner diameter of the air outlet may be the same size.

Explanation of Reference Numerals

[0040] 10…Nozzle head 11…Head body 14…First supply path (supply path) 15…Second supply path (supply path) 21…Spinning hole 22…Spinning electrode 25…Air tube 26…Air flow path 29…Air discharge port 33…Collector electrode 35…Collection member A…Air L…Spinning solution J…Jet of spinning solution

Claims

1. A cylindrical head body having a spinning hole that opens to the outer peripheral surface and a supply path for supplying a spinning solution containing a solvent to the spinning hole, and a spinning electrode for charging the spinning solution, wherein, due to the potential difference between the spinning electrode and a collector electrode disposed outside the head body, the spinning solution is ejected from the spinning hole and collected by a collection member in a state of being nanofibered, and it is a nozzle head configured as such, the nozzle head being provided with an air discharge port for discharging air so as to bring the air into contact with the jet of the spinning solution from the spinning hole to the collection member.

2. The nozzle head according to claim 1, wherein the air discharge port opens so as to surround the ejection path of the spinning solution ejected from the spinning hole.

3. The nozzle head according to claim 2, further comprising an air tube surrounding the head body, wherein the space between the head body and the air tube functions as an air flow path for supplying the air to the air discharge port.

4. The nozzle head according to claim 3, wherein the inner diameter of the air discharge port is larger than the inner diameter of the spinning hole.

5. The nozzle head according to claim 4, wherein the opening shapes of the spinning hole and the air discharge port are concentric circles.

6. An electrospinning device comprising a nozzle head and a collector electrode disposed outside the nozzle head, wherein the nozzle head has a cylindrical head body having a spinning hole that opens to the outer peripheral surface and a supply path for supplying a spinning solution containing a solvent to the spinning hole, and a spinning electrode for charging the spinning solution, and due to the potential difference between the spinning electrode and the collector electrode, the spinning solution is ejected from the spinning hole and collected by a collection member in a state of being nanofibered, and the nozzle head is provided with an air discharge port for discharging air so as to bring the air into contact with the jet of the spinning solution from the spinning hole to the collection member.

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