JP5754703B2 - Method and apparatus for producing nanofiber nonwoven fabric - Google Patents

Description

  The present invention relates to a method and apparatus for producing a nanofiber nonwoven fabric on which nanofibers made of a polymer are deposited.

  An electrospinning method is known as a method for producing a nanofiber having a submicron-scale diameter made of a polymer. In this electrospinning method, a polymer solution is supplied to a needle-like nozzle to which a high voltage is applied, and the polymer solution is ejected linearly from the needle-like nozzle toward a collecting portion. The linear polymer solution is charged, and the diameter of the linear polymer solution is reduced with the evaporation of the solvent of the polymer solution, the charged charge is concentrated, and the Coulomb force acting on the linear polymer solution is increased. When this Coulomb force becomes larger than the surface tension of the linear polymer solution, a phenomenon occurs that the linear polymer solution is stretched explosively (electrostatic explosion phenomenon). By repeating this electrostatic explosion phenomenon, submicron Nanofibers with a diameter (eg 50-1000 nm) are produced.

  By depositing the nanofibers on the collection part, a three-dimensional thin film having a three-dimensional network can be obtained. Also, by forming the nanofiber thick, a highly porous web having a submicron network can be produced. The highly porous web thus produced can be suitably applied to filters, battery separators, polymer electrolyte membranes and electrodes of fuel cells.

  A nanofiber nonwoven fabric is produced by depositing nanofibers produced by electrospinning by flowing a polymer solution from a nozzle on a movable sheet that can be ventilated as a collection part, and sucking the lower side of this sheet. A method is known (Patent Document 1).

JP 2008-223179 A

  In the configuration shown in Patent Document 1, since suction is only performed from the lower side of the sheet, a part of the nanofibers flying from the discharge unit toward the collection unit is scattered, or the deposition thickness on the collection unit There is a risk that the unevenness of the thickness becomes large.

  In addition, the charged polymer or the conductive polymer needs to have a very high applied voltage between the nozzle and the collecting portion during electrospinning. However, if the applied voltage is increased in this way, there is a possibility of discharging. high.

  An object of the present invention is to solve the above-described conventional problems and to provide a method and apparatus for producing a nanofiber nonwoven fabric that can efficiently produce a uniform nanofiber nonwoven fabric without causing discharge.

In the method for producing a nanofiber nonwoven fabric of the present invention (Claim 1), a polymer solution obtained by dissolving a nanofiber raw polymer in a solvent is discharged from a discharge portion, and a voltage is applied between the discharge matter and the discharge portion. In the method for producing a nanofiber nonwoven fabric, a nanofiber is produced by flying toward one side of the collection portion, and the produced nanofiber is collected by the collection portion to form a nanofiber nonwoven fabric. A method of producing a nanofiber nonwoven fabric having a structure capable of ventilating, sucking the other side of the collection unit by a gas suction unit, and blowing air by a blowing unit in a direction from the discharge unit toward the collection unit, A cylindrical auxiliary electrode coaxial with the discharge unit is disposed around the discharge flying zone between the discharge unit and the collection unit, and the distance between the tip of the discharge unit and the collection unit is a. Tip and auxiliary When the distance between the poles is b, provided at a position where b / a is 0.3 to 1.5, with voltages _{V 1} between the collecting unit said discharge out portion 1～100KV, said discharge detecting section those voltage V ₂ between the auxiliary electrodes so that 30 to 100% of the voltage V _1, characterized in that said auxiliary electrode to apply a voltage such that the opposite potential and discharge portion and It is.

Method for producing a nanofiber nonwoven according to claim 2, characterized in that Oite to claim 1, the air volume air blowing means generating, 30 to 100% of the air volume that the gas suction means for generating is there.

According to a third aspect of the present invention, there is provided a method for producing a nanofiber nonwoven fabric according to the first or second aspect , wherein the outer periphery of the ejected matter flying zone is surrounded by a surrounding body.

The method for producing a nanofiber nonwoven fabric according to claim 4 is characterized in that, in any one of claims 1 to 3 , the raw material polymer is a charged or conductive polymer.

The apparatus for producing a nanofiber nonwoven fabric according to claim 5 is a discharge unit that discharges a solution obtained by dissolving a raw polymer of nanofibers in a solvent, a collection unit that collects nanofibers from the discharge unit on one side, and A device for applying a voltage between the discharge unit and the collection unit, and a gas for sucking the other side of the collection unit in the nanofiber nonwoven fabric manufacturing apparatus, wherein the collection unit can be ventilated and suction means, Oite around the discharged product flying zone between the collecting unit blowing means and the discharge unit for blowing air in the direction toward the collecting unit from said discharge output unit, said discharge out of the tip and the collecting the distance between the parts is a, and the distance between said discharge out of the tip and the auxiliary electrode was b, b / a is provided at positions which are 0.3 to 1.5, said discharge detecting portion coaxially The voltage V1 between the cylindrical auxiliary electrode and the discharge part and the collection part is ₁ to 100 kV, So that the voltage V ₂ between the said discharge exit portion and the auxiliary electrode is 30% to 100% of the voltage V _1, means for applying a voltage to the opposite potential and the discharge unit with respect to the auxiliary electrode And is further provided.

An apparatus for producing a nanofiber nonwoven fabric according to a sixth aspect of the present invention is the apparatus for manufacturing a nanofiber nonwoven fabric according to the fifth aspect , further comprising an enclosure that surrounds the outer periphery of the discharge product flying zone.

Apparatus for producing nanofiber nonwoven according to claim 7, in claim 5 or 6, in which the raw material polymer is characterized by a charged or conductive polymers.

  In the present invention, not only the collection part is sucked from the opposite side (other side) to the discharge part, but also the air is blown in the direction from the discharge part toward the collection part, so that the nano flying from the discharge part toward the collection part Since the fiber (electrospun fiber) maintains a uniform distribution state and does not protrude from the collection part, it will surely deposit on the collection part. Can do.

  In the present invention, not only the collecting part but also an auxiliary electrode is provided, and by applying a voltage to the auxiliary electrode so as to have a potential opposite to that of the discharge part, the voltage applied to the collecting part can be reduced, Less likely.

  The chargeable polymer is converted into nanofibers by applying a voltage to the collection part, and is collected in the collection part. However, at that time, the nanofiber is charged by the potential of the collection part, and tries to fluff toward the discharge part having the opposite potential. By using the auxiliary electrode, not only can the voltage applied to the collection unit be reduced, but also the applied nanofiber was collected by the collection unit by applying a voltage at a potential opposite to the discharge unit to the auxiliary electrode. Later, fluffing toward the discharge part can be suppressed. By using an auxiliary electrode in addition to air blowing and exhausting air, fuzzing can be further suppressed and a uniform film can be produced.

  In addition, since the deposit of nanofiber is pressed against the collection part by the gas flow which passes a collection part, it becomes a sheet form in normal cases. By setting the air volume of the air blowing means to 30% or more of the air volume of the gas suction means, it is possible to suppress the fuzz of the nanofibers deposited on the collecting part, and thereby unevenness in the deposited thickness of the nanofibers on the collecting part. Can be reduced. If the air volume of the air blowing means is increased too much, the air volume on the discharge part side (one side) of the collecting part becomes excessive, and the air circulates around the air blowing means, from the discharge part to the collecting part. Although some of the nanofibers flying in the direction may be scattered without being collected by the collecting part, the air volume of the air blowing means is 100% or less of the air volume of the gas suction means, It is possible to prevent the air volume on the discharge unit side from becoming excessive, and to prevent nanofibers from being scattered.

  When the nanofibers are collected in the collection part, the collection part is gradually closed. Therefore, if the air volume of the blowing means and the air volume of the gas suction means are equivalent, the collection part is blocked. Along with this, there is a risk that the air volume of the air blowing means becomes excessive and a part of the nanofibers flying from the discharge part toward the collecting part may be scattered, but the air volume of the air blowing means is, for example, 80% or less of the air volume of the gas suction means. By reducing the amount, the air volume of the air blowing means is unlikely to be excessive even when the collection of the nanofibers in the collection part proceeds, and the nanofibers can be more reliably prevented from being scattered for a long period of time.

  A more uniform nanofiber nonwoven fabric can be efficiently produced by surrounding the outer periphery of the discharged product flying zone between the discharge unit and the collection unit with an enclosure.

  In addition, by adjusting the humidity and temperature of the gas flow from the discharge part to the collection part, the evaporation rate of the solvent from the nanofibers in flight and the nanofiber nonwoven fabric on the collection part can be controlled. A good nanofiber nonwoven fabric can be produced, which is preferable.

  By heating the discharge part and the polymer solution supplied to the discharge part, gelation and solidification of the polymer solution can be prevented, and the nanofiber nonwoven fabric can be efficiently produced.

It is sectional drawing of the nonwoven fabric manufacturing apparatus which concerns on embodiment. It is a perspective view of the state which removed the housing of the nonwoven fabric manufacturing apparatus of FIG. It is a perspective view of the state where the housing of the nonwoven fabric manufacturing apparatus concerning an embodiment was removed. It is a perspective view of the state where the housing of the nonwoven fabric manufacturing apparatus concerning an embodiment was removed. It is a perspective view of the state where the housing of the nonwoven fabric manufacturing apparatus concerning an embodiment was removed. It is a perspective view of the state where the housing of the nonwoven fabric manufacturing apparatus concerning an embodiment was removed. It is a microscope picture of a nanofiber nonwoven fabric. It is a microscope picture of a nanofiber nonwoven fabric. It is a microscope picture of a nanofiber nonwoven fabric.

  Hereinafter, embodiments will be described with reference to the drawings. FIG. 1 is a cross-sectional view of the nanofiber nonwoven fabric manufacturing apparatus according to the embodiment, and FIG. 2 is a perspective view of the nonwoven fabric manufacturing apparatus with the housing removed.

[Nanofiber non-woven fabric manufacturing apparatus of FIGS. 1 and 2]
In FIGS. 1 and 2, a nozzle 1 as a discharge unit for discharging a polymer solution into a thin line shape, and a collection material 2 as a collection unit for collecting nanofibers generated by discharging from the nozzle 1, Is disposed in the housing 3 as an enclosure. In this embodiment, the housing 3 has a cylindrical shape such as a cylindrical shape or a rectangular tube shape, a blower 4 as a blower means is disposed on one end side, and a blower 5 as a gas suction means is provided on the other end side. ing.

  The exhaust fan 5 is disposed on the opposite side of the nozzle 1 with the trapping material 2 interposed therebetween. A polymer solution is supplied to the nozzle 1 via a pipe 6.

  An auxiliary electrode 7 is provided around the nozzle 1. In this embodiment, the auxiliary electrode 7 has a short cylindrical shape coaxial with the nozzle 1. When the distance between the tip of the nozzle 1 and the collecting material 2 is a and the distance between the tip of the nozzle 1 and the auxiliary electrode 7 is b, b / a is 0.3 to 1.5, particularly 0.5 to 1. About 0.0 is preferable.

A high voltage is applied between the nozzle 1 and the collector 2 and the auxiliary electrode 7 by a voltage source 8. In FIGS. 1 and 2, a high voltage is applied so that the collector 2 and the auxiliary electrode 7 are positive and the nozzle 1 is negative. This polarity may be reversed. The voltage V ₁ between the nozzle 1 and the collecting material 2 is preferably about ₁ kV to 100 kV, particularly about 5 kV to 100 kV, but is not limited thereto. Voltage _{V 2} between the nozzle 1 and the auxiliary electrode 7, _{V 1} or less, is preferably 30% to 100%, especially 50-90%, for example _{V 1.}

  The collection material 2 is made of a material that allows ventilation, such as a perforated plate, a mesh, a woven fabric, and a non-woven fabric. It may be a perforated plate or a mesh having a woven fabric or non-woven fabric arranged on the plate surface on the nozzle 1 side.

  In the nanofiber nonwoven fabric manufacturing apparatus configured as described above, the blower 4 and the exhaust fan 5 are operated, a voltage is applied between the nozzle 1, the collector 2 and the auxiliary electrode 7, and the polymer solution is discharged from the nozzle 1. Then, the polymer solution is discharged from the nozzle 1 as a thin linear body. As the solvent of the polymer solution evaporates from the linear body, the diameter of the linear body is reduced, and the charged charge is concentrated accordingly, and the Coulomb force exceeds the surface tension of the linear polymer solution. At that point, a primary electrostatic explosion occurred and the film was stretched explosively, and then the solvent further evaporated, similarly a secondary electrostatic explosion occurred and the film was stretched explosively, and in some cases, a third electrostatic explosion occurred. By being drawn, nanofibers F made of a polymer having a submicron diameter are efficiently produced.

  In this embodiment, since the auxiliary electrode 7 is provided, even if the voltage between the nozzle 1 and the collecting material 2 is lower than that without the auxiliary electrode 7, a sufficiently high quality nanofiber is obtained. Can be manufactured.

  In the present invention, at the time of manufacturing the nonwoven fabric, the blower 4 and the exhaust fan 5 are operated so that the air volume of the blower 4 is 30 to 100%, preferably 30 to 80% of the air volume of the exhaust fan 5.

  This nanofiber F is collected and deposited on the collection material 2, and a nonwoven fabric produces | generates. After a predetermined amount of non-woven fabric is generated, the above manufacturing operation is stopped and the non-woven fabric is taken out from the collecting material 2.

  By operating the blower 4 and the exhaust fan 5 so that the air volume of the blower 4 becomes 30% or more of the air volume of the exhaust fan 5 at the time of manufacturing the nonwoven fabric, the fuzz of the nanofibers F accumulated on the collecting material 2 is suppressed. Thereby, the unevenness of the deposited thickness of the nanofiber F on the collecting material 2 can be reduced. If the air volume of the blower 4 is increased too much, the air volume on the nozzle 1 side of the trapping material 2 becomes excessive, and the wind circulates around the blower 4, from the nozzle 1 toward the trapping material 2. Although some of the flying nanofibers F may be scattered without being collected by the collecting material 2, the air volume of the blower 4 is set to 100% or less of the air volume of the exhaust fan 5. The air volume on the nozzle 1 side is prevented from becoming excessive, and scattering of the nanofibers F can be prevented.

  Note that when the nanofibers F are collected on the collection material 2, the collection material 2 is gradually blocked. Therefore, when the air volume of the blower 4 is equal to the air volume of the exhaust fan 5, this collection is performed. There is a possibility that the air volume of the blower 4 becomes excessive as the collecting material 2 is blocked. By making the air volume of the blower 4 80% or less of the air volume of the exhaust fan 5, the nanofiber F to the collecting material 2 can be obtained. However, the air volume of the blower 4 is unlikely to be excessive even if the collection of the air proceeds, and the scattering of the nanofibers F can be more reliably prevented over a long period of time.

  In this embodiment, the housing 3 is provided so as to surround the discharge flying zone between the nozzle 1 and the collection material 2, the blower 4 is provided in the upstream portion of the housing 3, and the exhaust fan 5 is provided as the collection material. 2, the nanofibers F flying from the nozzle 1 toward the collecting material 2 are collected in the collecting material 2 without being scattered around and in a uniformly distributed state. . Therefore, the non-woven fabric on the collection material 2 has less unevenness in quality, characteristics, and thickness.

[Nanofiber non-woven fabric manufacturing equipment in Fig. 3]
In FIG. 3, in the manufacturing apparatus of FIGS. 1 and 2, the auxiliary electrode 7 is arranged in the discharge flying zone between the nozzle 1 and the collecting material 2 so as to surround the flying zone. The shape of the auxiliary electrode 7 is the same as in FIGS. 1 and 2, and the auxiliary electrode 7 is arranged coaxially with the nozzle 1. The ratio b / a between the distance b between the tip of the nozzle 1 and the auxiliary electrode 7 and the distance a is preferably about 0.3 to 1.5, particularly about 0.5 to 1.0.
[Nanofiber manufacturing equipment in Fig. 4]
In FIG. 4, a plurality of flat auxiliary electrodes 10 are arranged around the nozzle 1 so as to surround the nozzle 1. In this embodiment, four auxiliary electrodes 10 are arranged every 90 ° in the circumferential direction of the nozzle 1. The plate surface of each auxiliary electrode 10 is parallel to the axial direction of the nozzle 1. Other configurations are the same as those in FIGS. 1 and 2, and the same reference numerals denote the same parts.
[Nanofiber manufacturing equipment in FIG. 5]
In FIG. 5, a polygonal cylindrical auxiliary electrode 11 is installed around the nozzle 1 coaxially with the nozzle 1. The auxiliary electrode 11 has a hexagonal cylindrical shape, but may be a quadrangle or more. Other configurations are the same as those in FIGS. 1 and 2, and the same reference numerals denote the same parts.
[Nanofiber manufacturing equipment in FIG. 6]
In FIG. 6, a ring-shaped auxiliary electrode 12 is installed coaxially with the nozzle 1. The plate surface of the auxiliary electrode 12 is perpendicular to the axis of the nozzle 1. Other configurations are the same as those in FIGS. 1 and 2, and the same reference numerals denote the same parts.

  In addition, although illustration is abbreviate | omitted, you may install the air heater for humidifying the air ventilated with the air blower 4, and the water vapor | steam supply device for humidifying this air. Air is heated with an air heater to promote evaporation of the solvent from the fine linear polymer solution during flight, or to adjust the humidity (water vapor concentration) in the atmosphere in the housing 3 to evaporate the solvent from the fine linear polymer solution. The speed can be controlled, and the length and diameter of the nanofiber can be adjusted accordingly.

  The above manufacturing apparatus manufactures a nanofiber nonwoven fabric batchwise, and moves the collection material continuously, and deposits nanofibers on the collection material to produce the nonwoven fabric continuously. It may be.

  In this case, the trapping material is an endless belt made of a material that can be ventilated and bent, such as mesh, woven fabric, non-woven fabric, etc., spanned endlessly between the drive rollers, and the upper traveling part moves horizontally. Configured to do.

[Raw material of nanofiber]
The raw material polymer for nanofibers includes polyolefins such as polyethylene and polypropylene, polyethers such as polyethylene oxide and polypropylene oxide, fluororesins such as PTFE, CTFE, PFA, polyvinylidene fluoride (PVDF), and halogenated polyolefins such as polyvinyl chloride. , Polyamide such as nylon-6, nylon-66, urea resin, phenolic resin, melamine resin, polystyrene, cellulose, cellulose acetate, cellulose nitrate, polyetherketone, polyetherketoneketone, polyetheretherketone, polysulfone, polyethersulfone , Polyimide, polyetherimide, polyamideimide, polybenzimidazole, polycarbonate, polyethylene terephthalate, polybutylene Terephthalate, polyphenylene sulfide, polyacrylonitrile, polyether nitrile, but polyvinyl alcohol and materials including these copolymers can be used, not limited thereto. In particular, it is not limited to one kind of material, and various materials can be selected as necessary. However, a chargeable or conductive polymer is preferable because the effect of the present invention is remarkable because fuzzing is likely to occur in the collecting portion by electrospinning. In addition, you may mix other polymers, such as polyolefin and polyether, with a chargeable or electroconductive polymer.

  Examples of the conductive polymer include polyacetylene and polythiophenes.

  As the chargeable polymer, a perfluorocarbon sulfonic acid polymer (NAFION (registered trademark), Fumion (trade name)), a sulfonate group, a carboxyl group, and a primary to quaternary amino group were added to the skeleton uncharged polymer. Mention may be made of polymers. Examples of the non-chargeable polymer serving as the skeleton include polyolefin, polystyrene, polysulfone, polyester, and polyvinylidene fluoride.

  As the solvent, alcohols such as methanol, ethanol, propanol and isopropanol, N-methylpyrrolidone, dimethylacetamide, dimethylformamide, fluorinated solvents and the like are preferable, but water is added in an amount of 10 to 1000 volumes with respect to 100 parts by volume of the solvent. Partially mixed solvents are also suitable.

  The nanofiber may be provided with at least one of a cation exchange group, an anion exchange group, and a chelate group.

  Examples of ion exchange groups include sulfonic acid groups, phosphoric acid groups, phosphonic acid groups, phosphinic acid groups, carboxylic acid groups, hydroxyl groups, phenol groups, quaternary ammonium groups, primary to tertiary amine groups, pyridine groups, and amide groups. There is not this limit. These functional groups may be not only H-type and OH-type but also salt-type such as Na.

  The method for introducing the functional group is not particularly limited, and various methods can be employed. For example, in the case of polystyrene, a sulfonic acid group can be introduced by adding an appropriate amount of paraformaldehyde to a sulfuric acid solution and crosslinking by heating. In the case of polyvinyl alcohol, a functional group can be introduced by allowing a trialkoxysilane group, a trichlororosilane group, or an epoxy group to act on the hydroxyl group. If the functional group cannot be introduced directly depending on the material, first introduce a highly reactive monomer such as styrene (referred to as a reactive monomer) and then introduce the functional group in two or more stages. Then, a target functional group may be introduced. These reactive monomers include, but are not limited to, glycidyl methacrylate, styrene, chloromethyl styrene, acrolein, vinyl pyridine, acrylonitrile and the like.

[Other embodiments]
In the present invention, a heater for heating the nozzle or a heater (such as a heater or a heat exchanger) for heating the polymer solution supplied to the nozzle to 30 to 90 ° C., particularly about 30 to 60 ° C. may be provided. Good. By heating the nozzle or the polymer solution to be supplied to the nozzle in this way, gelation and solidification of the polymer solution can be prevented, and the nanofiber nonwoven fabric can be efficiently produced.

  In the present invention, the exhaust air from the exhaust fan may be sent to the suction side of the blower.

<Examples 1 to 5 and Comparative Example 1>
[Example 1]
A polymer solution for producing nanofibers was prepared by dissolving 10 parts by weight of commercially available NAFION and 10 parts by weight of polyvinylidene fluoride in 80 parts by weight of dimethylacetamide.

  This polymer solution was supplied to the nozzle 1 in FIGS. 1 and 2 over 480 minutes to produce nanofibers having an average fiber diameter of 300 nm. Other conditions are as follows.

Nozzle diameter: 320 μm
Amount ejected from nozzle: 0.2 mL / min
Distance a between the tip of the nozzle 1 and the collection material 2: 135 mm
Distance b between tip of nozzle 1 and auxiliary electrode 7: 140 mm
Housing cross section: 1300cm ²
Air flow: 30000L / min
Exhaust air volume: 50000L / min
Humidity: 50%
Temperature: Room temperature Applied voltage V ₁ between the nozzle 1 and the collecting material 2: 30 kV
Applied voltage V ₂ between nozzle 1 and auxiliary electrode 7: 20 kV

  Thereby, the nonwoven fabric shown in FIG. 7 was manufactured. In Example 1, the presence or absence of discharge, the SEM observation of the state of the product, the fluffing of the nanofiber being produced, and the thickness of the produced film, variation in film thickness, and the recovery rate of the produced nanofiber were determined. .

  The variation in film thickness is obtained by cutting the prepared film into a square with a side of 100 mm, measuring the film thickness at 16 points at equal intervals, and obtaining the average value, the thickest value, and the thinnest value, and calculating the difference from the average value. Calculated and determined. Further, the recovery rate of the nanofibers was obtained by the estimated amount of nanofiber production × 100 calculated from the amount of nanofiber film produced / the amount of solution used.

  The results are shown in Table 1. As shown in Table 1, according to Example 1, it was possible to stably form fibers without discharging and to produce a nonwoven fabric with a sufficient film thickness without unevenness.

[Example 2]
40kV a collecting unit applying voltages _{V 1} in Example 1, except that the auxiliary electrode application voltage _{V 2} was 25kV was prepared a nonwoven fabric under the same conditions. The results are shown in Table 1. As shown in Table 1, it was possible to produce a nonwoven fabric having a sufficient film thickness without unevenness by forming fibers stably without discharging.

[Comparative Example 1]
And removing the auxiliary electrode in Example 1, but except that the collecting unit applying voltages V ₁ was 30kV tried manufacturing a nonwoven in the same conditions, where the construct was observed by SEM, Table 1 and 8 As shown in the figure, it was a mixture of fibers and droplets. Since there is no auxiliary electrode and the collector application voltage is as low as 30 kV, it is considered that the fibers were not sufficiently formed.

[Comparative Example 2]
And removing the auxiliary electrode in Example 1, but except that the collecting unit applying voltages V ₁ was 50kV tried nonwoven production under the same conditions, where the construct was observed by SEM, as shown in Table 1, the fibers And a mixture of droplets. Although the fibers could be stably formed without discharge, the variation in the film thickness with respect to the film thickness of the nonwoven fabric was slightly increased to ± 17 μm. It is considered that some fluffing was suppressed by the air blowing, but partly fuzzing occurred because there was no auxiliary electrode.

[Comparative Example 3]
And removing the auxiliary electrode in Example 1, except that the collecting unit applying voltages V ₁ was 60kV tried nonwoven production in the same conditions. As shown in Table 1, spinning was possible, but discharge occurred during production, and continuous production was difficult. No auxiliary electrode, also, presumably because of increased applied voltages V ₁ to the collecting portion 60 kV.

[Comparative Example 4]
In Example 1, the production of the nonwoven fabric was attempted under the same conditions except that the exhaust and blowing were stopped. However, as shown in Table 1, the produced film fluttered up and was difficult to produce. It is thought that fluffing occurred because there was no hold-down by air blowing, and that the fiber soared because there was no exhaust.

[Comparative Example 5]
In Example 1, an attempt was made to produce a non-woven fabric under the same conditions except that the air flow was set to 50000 L / min and the exhaust air was stopped. However, as shown in Table 1, the produced film was swollen and difficult to produce. Although fluffing did not occur due to the suppression by blowing air, it was thought that the fiber soared because there was no exhaust.

[Comparative Example 6]
In Example 1, production of the nonwoven fabric was tried under the same conditions except that the blowing was stopped and the exhausted air amount was 50000 L / min. However, as shown in Table 1, the produced fibers were fluffy and difficult to produce. It was thought that fluffing occurred because there was no hold-down by blowing air, but it was thought that it was possible to prevent soaring because of the exhaust air.

[Comparative Example 7 (change of applied voltage of auxiliary electrode)]
Example 1 0.5 kV auxiliary electrode applied voltage V ₂ at, but except that the collecting unit applying voltages V ₁ was 30kV tried nonwoven production under the same conditions, where the construct was observed by SEM, the As shown in FIG. 9 and Table 1, it was a mixture of fibers and droplets. It is considered that sufficient fibers were not formed because the applied voltage of the auxiliary electrode was extremely low.

[Comparative example 8 (change of applied voltage of auxiliary electrode)]
Example 1 60 kV auxiliary electrode applied voltage V ₂ in, except that the collecting unit applying voltages V ₁ was 30kV tried nonwoven production under the same conditions. As shown in Table 1, spinning was possible, but discharge occurred during production, making continuous production difficult. Application of the auxiliary electrode voltage V ₂ is considered to have discharged because higher than V _1.

[Example 3 (change in the ratio of air intake and intake)]
A nonwoven fabric was manufactured under the same conditions except that the air flow rate was set to 15000 L / min and the exhaust air flow rate was set to 50000 L / min in Example 1. The results are shown in Table 1. As shown in Table 1, the ratio of airflow and exhaust air was balanced, and soaring and fluffing were suppressed.

[Example 4 (change in the ratio of air intake and intake)]
A nonwoven fabric was manufactured under the same conditions except that the air flow rate was 50000 L / min and the exhaust air volume was 50000 L / min in Example 1. The results are shown in Table 1. As shown in Table 1, the ratio of airflow and exhaust air was balanced, and soaring and fluffing were suppressed.

[Comparative example 9 (change in the ratio of air intake and intake)]
In Example 1, an attempt was made to fabricate the nonwoven fabric under the same conditions except that the air flow rate was 10,000 L / min and the exhaust air amount was 50000 L / min. However, as shown in Table 1, the produced fibers were fluffy and difficult to produce. . This is probably because the amount of exhausted air was low and the effect of suppressing fuzz was insufficient.

[Comparative Example 10 (change in the ratio of air intake and intake)]
In Example 1, the production of the nonwoven fabric was tried under the same conditions except that the air flow rate was 60000 L / min and the exhaust air amount was 50000 L / min, but as shown in Table 1, the fibers produced in the collection part were collected. As it gradually rose, it was difficult to manufacture. Since the amount of exhausted air is small relative to the amount of air blown, the balance of air blowing / exhaust is poor, and it is considered that the fiber soars.

[Example 5 (change of auxiliary electrode position)]
In Example 1, a non-woven fabric was produced under the same conditions except that the position of the electrode was around the flying zone as shown in FIG. As a result, as shown in Table 1, it was possible to produce a nonwoven fabric having a sufficient thickness without unevenness by forming fibers stably without discharging.

  As is clear from these examples and comparative examples, according to the present invention, the use of the auxiliary electrode in addition to air blowing / intake leads to more fuzzing and film thickness variation (unevenness) than in the case of air blowing / intake alone. ) Can be prevented.

DESCRIPTION OF SYMBOLS 1 Nozzle 2 Collection material 3 Housing 4 Blower 5 Fan exhaust 6 Pipe for polymer solution supply 7 Auxiliary electrode 8 Voltage source

Claims (7)

A polymer solution obtained by dissolving a nanofiber raw material polymer in a solvent is discharged from a discharge portion, and the discharge is made to fly toward one side of a collection portion to which a voltage is applied between the discharge portion and the nanofiber. In the method for producing a nanofiber nonwoven fabric, the produced nanofibers are collected at the collection section to form a nanofiber nonwoven fabric.
In the manufacturing method of the nanofiber nonwoven fabric which is structured so as to allow ventilation of the collection part and sucks the other side of the collection part by the gas suction means and blows by the blowing means in the direction from the discharge part toward the collection part. There,
Around the discharged product flying zone between the collecting unit said discharge out section, the said discharge detecting portion coaxial with the cylindrical auxiliary electrodes, and the distance between the tip and the collecting portion of said discharge detection section and a, the When the distance between the tip of the discharge part and the auxiliary electrode is b, the voltage V ₁ between the discharge part and the collection part is 1 at a position where b / a is 0.3 to 1.5. The voltage is applied so that the auxiliary electrode is at a potential opposite to that of the discharge unit so that the voltage V ₂ between the discharge unit and the auxiliary electrode is 30 to 100% of the voltage V ₁ at ˜100 kV A method for producing a nanofiber nonwoven fabric, comprising: Oite to claim 1, the air volume air blowing means generating method of the nanofiber nonwoven fabric, characterized in that the gas suction means is 30 to 100% of the air volume to be generated. 3. The method for producing a nanofiber nonwoven fabric according to claim 1, wherein an outer periphery of the ejected product flying zone is surrounded by an enclosure. The method for producing a nanofiber nonwoven fabric according to any one of claims 1 to 3 , wherein the raw material polymer is a charged or conductive polymer. A discharge unit for discharging a solution obtained by dissolving a raw material polymer of nanofibers in a solvent;
A collection unit that collects nanofibers from the discharge unit on one side;
Means for applying a voltage between the discharge section and the collection section;
In the nanofiber nonwoven fabric manufacturing apparatus equipped with
It is configured so that the collection part can be ventilated,
Gas suction means for sucking the other side of the collection part;
Air blowing means for blowing air in a direction from the discharge part toward the collecting part;
The distance between the discharged product Oite around the flying zone, the distance between the tip and the collecting portion of said discharge detection section is a, said discharge out of the tip and the auxiliary electrode between the collecting portion the discharge portion Is a cylindrical auxiliary electrode coaxial with the discharge part, provided at a position where b / a is 0.3 to 1.5 ,
The voltage V ₁ between the discharge part and the collection part is ₁ to 100 kV, and the voltage V ₂ between the discharge part and the auxiliary electrode is 30 to 100% of the voltage V _1. Means for applying a voltage to the auxiliary electrode at a potential opposite to that of the discharge unit;
An apparatus for producing a nanofiber nonwoven fabric, further comprising: 6. The apparatus for producing a nanofiber nonwoven fabric according to claim 5 , further comprising an enclosure that surrounds an outer periphery of the discharge product flying zone. According to claim 5 or 6, nanofiber nonwoven fabric manufacturing apparatus characterized by the raw material polymer is charged or conductive polymers.

Images