JPWO2007069381A1 - Electrostatic spraying apparatus and electrostatic spraying method - Google Patents

Abstract

The electrostatic spraying apparatus includes a plurality of nozzles arranged two-dimensionally for electrostatically spraying the polymer solution, and a plurality of first collectors arranged via an insulating sheet so as to face the nozzles. The spinning unit is attached to a collecting unit that holds the moving collecting sheet. Inside the spinning unit, the air flow in the direction of the collecting sheet is perpendicular to the spraying direction from the nozzle to the first collector. Configured to form.

Description

  The present invention relates to an electrostatic spraying apparatus and electrostatic spraying method for electrostatic spraying of a solution containing a polymer substance.

  Electrospraying is a solution in which a polymer substance, which is the material to be applied, is mixed with a solvent to form a solution, and the solution is stored in a container with a sharp tip, such as a needle tip of a syringe or a thin glass tube. This is done by applying a high voltage between the container and the spray object. In electrostatic spraying, a charge is given to the polymer substance in the container, and the charged polymer substance becomes a mist due to the repulsive force of the charge, from the tip of the container, using the Coulomb force to the spray side ( The light is emitted to the side called the collector having a different polarity from the container tip side) or to the ground side (ground side), and collected and stacked on the collector side. Electrostatic spraying is one that uses electrostatic spraying, and electrostatic coating for automobile bodies such as automobiles is generally known as an electrostatic coating application. Electrostatic coating is applicable not only to vehicle body coating but also to various other things. In particular, the present invention relates to an apparatus for electrostatic spraying using an artificial polymer substance as a material, and relates to an apparatus that can easily manufacture a nonwoven fabric having a fiber size smaller than 100 nanometers [nm], that is, a fiber size called a nanofiber. It is. The nonwoven fabric thus manufactured can be used in a wide range of filters and the like.

  The filter can also be manufactured using a “melting method” which is one of the conventional methods for manufacturing nonwoven fabrics. However, in such a conventional manufacturing method, a filter manufactured using a fiber having a diameter of several tens of micrometers is the mainstream, and it is limited to make a filter using a fiber having a size of several hundred nanometers. As described above, in the manufacturing method using electrostatic spraying, it is possible to manufacture a non-woven fabric having a fiber diameter that is one or two orders of magnitude thinner than a manufacturing method using a conventional “melting method” or the like. In electrostatic spraying, if only one nozzle has a spray port, only a few centimeter square filter can be manufactured. From the viewpoint of mass productivity and productivity, the nozzle that serves as the spray port A single configuration is not realistic. In the case of textile manufacturers and raw film manufacturers, it is necessary to use a plurality of nozzles when manufacturing a product with a width of 100 centimeters or a size similar to that of nonwoven fabrics and films manufactured by conventional manufacturing methods. was there.

  However, when using a plurality of nozzles, there is a problem that the operation state of electrostatic spraying is not stable due to the influence of charge interference or repulsion, and electrostatic spraying from some or most of the plurality of arranged nozzles. There was a case that could not be done. Therefore, in order to put the electrostatic spraying apparatus having a plurality of nozzles into practical use and mass production, it has been a problem to perform stable electrostatic spraying using the plurality of nozzles.

  In order to achieve the above object, Japanese Patent Laid-Open No. 2002-201559 proposes a mechanism called charge distribution plate for suppressing charge interference and repulsion. However, the position of the charge distribution plate has to be changed depending on the magnitude of the voltage applied for electrostatic spraying, which is not easy to handle. In addition, when a plurality of nozzles are arranged in a plurality of states in a plurality of vertical and horizontal directions, the use of the charge distribution plate deteriorates the ratio of the coating amount (lamination amount) to the spray amount, so-called collection efficiency. There was a problem.

Japanese Patent Application Laid-Open No. 8-153669 discloses a method of applying a high voltage by providing electrodes on the mounting surface of the nozzle and the spray object. In this manner, in the method of providing the electrodes on the nozzle and the mounting surface and electrostatically spraying the spray object, the electrostatically sprayed material is laminated so as to cover the surface of the counter electrode which is the mounting surface. Therefore, the ability of electrostatic spraying gradually weakens. Therefore, in the manufacturing method disclosed in Japanese Patent Laid-Open No. 8-153669, it is difficult to perform electrostatic spraying with high accuracy over a long period of time, and the manufacturing method is not suitable for mass production.
JP 2002-201559 A JP-A-8-153669

  The material sprayed with electrostatic charge is attracted to a collector, which is a collecting surface (stacked surface) having a charge of a different polarity, and collected (stacked) on the collector. Since the sprayed materials have the same polarity, they repel each other due to the Coulomb force, diffuse and reach the collector in a uniform state. At the same time as the material is collected (laminated) by the collector, a charge is released to the collector. The collector must always hold an equivalent amount of pole charge different from the charge of the material even after the charge has been released, or be grounded. This is because when the material sprayed one after another is sucked and collected by the collector, if the collector holds an equivalent amount of charge of a different polarity or is grounded, the charge is charged between the nozzle spray port and the collector. The material is smoothly sucked from the spray port toward the collection surface (lamination surface) without electrostatic accumulation, and electrostatic spraying is performed. However, when the amount of charge carried by the sprayed material increases, a state occurs in which charge accumulates between the spray port and the collector. Since the accumulated charge and the charge of the material to be sprayed are of the same polarity, they are repelled by Coulomb's law, and the spray operation from the spray port is suppressed, and electrostatic spray from the nozzle spray port The phenomenon that cannot be performed occurs. Such a phenomenon occurs similarly in a configuration in which one nozzle is provided or a configuration in which a plurality of nozzles are provided. The inventors conducted an experiment using an electrostatic spraying device having both a configuration in which one nozzle is provided and a configuration in which a plurality of nozzles are provided, and gradually increases the applied voltage to increase the polymer material. It has been confirmed that the electrostatic spraying is stopped by increasing the amount of electric charge. However, in the case of an electrostatic spraying device provided with a single nozzle, the amount of charge charged by the polymer material to be sprayed is smaller than in the case of an electrostatic spraying device provided with a plurality of nozzles. This configuration facilitates electrostatic spraying.

  If a plurality of nozzles are used in order to increase productivity, the amount of charge inevitably increases, and repulsion between charges increases, so electrostatic spraying often cannot be performed. For this reason, it is necessary to reduce the amount of charge, specifically, to reduce the applied voltage. However, when the applied voltage is reduced in this way, a problem arises that the spraying speed is lowered and the productivity is deteriorated. In addition, repulsive force of charge is necessary for spraying from the spray nozzle at the tip of the nozzle. However, when the applied voltage is lowered to reduce the charge, the repulsive force necessary for spraying is insufficient and spraying may not be possible.

  Therefore, even when the electrostatic spraying is performed efficiently in the configuration in which one nozzle is provided, for example, in a configuration in which a plurality of nozzles are provided even when the voltage and the spraying distance are set to be the same, There are many cases in which electrostatic spraying from a part or most cannot be performed. For this reason, when electrostatic spraying is performed even in a configuration in which a plurality of nozzles are provided under conditions where electrostatic spraying can be efficiently performed in a configuration in which one nozzle is provided, a special configuration is required.

  For example, in a conventional electrostatic spraying device, the collector is arranged parallel to the spray ports of a plurality of nozzles, and the collector is made of aluminum foil so that no electric charge is accumulated between the spray ports and the collector. For this, a material having good conductivity is used and / or the area of the collector is made as large as possible. However, even with such a configuration, a certain degree of effect can be expected, but it is not improved drastically and is not a fundamental solution.

  Moreover, in the conventional electrostatic spraying apparatus, even when electrostatic spraying is performed, the collection efficiency is low, and collection (stacking) only at the intended location is not possible, and things that are not collected around the apparatus are scattered. Have the problem. The problem of such scattering was confirmed by the present inventors performing electrostatic spraying by covering the apparatus with a cover such as acrylic. The problem of not being able to collect (laminate) the sprayed material in this way naturally leads to loss of the material, but not only that of fibers with a fiber diameter of several nanometers to tens of nanometers. It is necessary to pay attention to the health damage of workers due to the large amount of scattering.

  The present invention can stably perform electrostatic spraying using a plurality of spraying means, and can mass-produce products with high collection efficiency, excellent productivity, and high accuracy. An object is to provide a high electrostatic spraying device and an electrostatic spraying method.

  The electrostatic spraying apparatus and the electrostatic spraying method according to the present invention are configured as follows in order to solve various problems in the above-described conventional electrostatic spraying apparatus.

The electrostatic spraying device of the present invention is a plurality of nozzles arranged two-dimensionally to electrostatically spray a polymer solution containing a polymer substance and formed into a liquid state using a solvent, and opposed to the plurality of nozzles A plurality of spinning units having a first collector that is arranged via an insulating sheet and is grounded to a voltage of a polarity different from the voltage applied to the nozzle or a ground potential,
A first power source for applying a predetermined high voltage to the nozzle; and a collection unit to which the spinning unit is attached and movably holds a collection sheet,
The spinning unit includes air flow forming means that forms an air flow in a direction perpendicular to a spraying direction from the nozzle to the first collector and toward the collection sheet. The electrostatic spraying device of the present invention configured as described above can continuously perform electrostatic spraying stably and with high collection efficiency.

The electrostatic spraying method of the present invention includes a step of supplying a polymer solution containing a polymer substance and formed into a liquid state using a solvent to a plurality of nozzles arranged two-dimensionally,
Applying a high voltage to the nozzle to electrostatically spray the polymer solution from the nozzle;
Generating a flow of air that flows in a direction substantially perpendicular to the direction of electrostatic spraying in the spinning unit having the nozzle, and applying the air flow to the electrostatically sprayed and charged polymer material, A step of laminating the polymer substance on a collection sheet disposed in a direction substantially orthogonal to the flow direction of The above-described electrostatic spraying method of the present invention can reliably perform electrostatic spraying stably and with high collection efficiency.

According to the present invention, an electrostatic spraying apparatus capable of mass-producing a product with high collection efficiency, excellent productivity, and high accuracy using nozzles arranged two-dimensionally as a plurality of spraying means, and An electrostatic spraying method can be provided.
Moreover, according to this invention, since the organic solvent generate | occur | produced in an electrostatic spray process can be collect | recovered reliably, an electrostatic spray apparatus and an electrostatic spray method with high safety | security can be provided.

The figure which shows schematic structure of the electrostatic spraying apparatus of Example 1 which concerns on this invention. Sectional drawing which shows typically the state with which the several spinning unit in the electrostatic spraying apparatus of Example 1 was mounted | worn with the duct. The perspective view which shows the spinning unit of the electrostatic spraying apparatus of Example 1. FIG. The figure which shows the mounting surface of the spinning unit of the electrostatic spraying apparatus of Example 1. The figure which shows the back side of the spinning unit of the electrostatic spraying apparatus of Example 1. Sectional drawing of the spray block vicinity in the spinning unit of the electrostatic spraying apparatus of Example 1. The disassembled perspective view of the vicinity of the spray block in the spinning unit of the electrostatic spraying apparatus of Embodiment 1.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Nozzle 2 Conductive plate 3 Charged particle 4 1st collector 5 Insulation sheet 6 Air inlet 7 2nd collector 8 Collection sheet 9 Insulation cover 10 Housing | casing 11 Flange 12 Mounting hole 13 Collection part 14 Material supply pipe 15 Material Holding tank 16 Metal mesh 17 Air flow 18 Intermediate roller 19 Recovery unit 20 Supply roller 21 Winding roller 22 Spinning unit 30 Spray block 40 First power supply 50 Second power supply

  Hereinafter, preferred embodiments of an electrostatic spraying apparatus and an electrostatic spraying method of the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a side view showing a schematic configuration of an electrostatic spraying apparatus according to a first preferred embodiment of the present invention. In the electrostatic spraying apparatus of Example 1, a solution containing a polymer substance is ejected from a nozzle by electrostatic spraying to produce fibers thinner than 100 nanometers [nm], that is, fibers called nanofibers. Is to be manufactured.

  First, the outline | summary of preparation of the nanofiber nonwoven fabric by electrostatic spraying of the electrostatic spraying apparatus of Example 1 which concerns on this invention using FIG. 1 is demonstrated. In order to produce nanofiber nonwoven fabric by collecting and laminating nanofiber fibers, a base substrate is required. As the substrate, for example, a collection sheet 8 that is an insulating resin sheet such as polyethylene is used. The collection sheet 8 is sent out from the supply roller 20 and taken up by the take-up roller 21 via a plurality of intermediate rollers 18 capable of controlling the conveyance speed. In the electrostatic spraying apparatus of Example 1, the conveying speed of the collection sheet 8 is determined by the thickness of the nonwoven fabric, the fiber diameter of the nanofiber, the material, and the like, and is configured to be able to handle a wide range of several meters to several hundred meters per minute. Has been.

  The collection sheet 8 as a substrate is conveyed through a section from the supply roller 20 to the winding roll 21 via the plurality of intermediate rollers 18. The plurality of spinning units 22 are provided along the conveyance path of the collection sheet 8. The spinning unit 22 is attached to a duct of a collection unit 13 having a collection sheet 8 in which nanofiber fibers are collected and stacked. When the collection sheet 8 passes through the inside of the collection unit 13, the nanofiber fibers from the spinning unit 22 are stacked on the collection sheet 8 with a thickness of several hundred nanometers to several hundred micrometers.

  As shown in FIG. 1, the spinning unit 22 is mounted substantially horizontally so as to be orthogonal to the side surface of the duct of the collecting portion 13 extending in the vertical direction or the horizontal direction, and each has an independent configuration. is doing. The number of the spinning units 22 attached is arbitrarily set according to the production speed and specifications of the nanofiber nonwoven fabric to be manufactured. In the electrostatic spraying apparatus of the first embodiment, the number of the spinning units 22 that can be mounted can be freely selected from the maximum number that can be mounted on the collection unit 13 when the number of the spinning units 22 is one. Further, since each spinning unit 22 is configured to operate independently, it is possible to operate only an arbitrary selected spinning unit 22 with the spinning unit 22 mounted. Therefore, in the electrostatic spraying apparatus according to the first embodiment, it is possible to remove a specific spinning unit 22 without stopping production and cope with a failure or maintenance of the spinning unit 22. In addition, if an accident occurs suddenly in some of the spinning units 22 during production, it is possible to continue production without stopping the entire device by simply stopping the relevant spinning unit 22. It is.

  Moreover, in the electrostatic spraying apparatus of Example 1, the material supplied to each spinning unit 22 does not need to be the same. Each spinning unit 22 is provided with a material holding tank 15 (see FIG. 2), which will be described later, for supplying material to the nozzles. Therefore, different materials are supplied to each spinning unit 22 and different materials are stacked. It is possible to produce a non-woven fabric. Of course, it is also possible to supply the same material to each spinning unit 22 to hold the same material in each material holding tank 15, and to connect the same supply pipe to each spinning unit 22 to the same material. It is also possible to have a configuration that always supplies.

  Next, the configuration and operation of the spinning unit 22 in the electrostatic spraying apparatus of Example 1 will be described.

  FIG. 2 is a side cross-sectional view showing the configuration of the plurality of spinning units 22 attached to the collection unit 13. 3 to 5 are diagrams showing the configuration of the spinning unit 22, FIG. 3 is a perspective view showing the spinning unit 22, FIG. 4 is a front view showing the mounting surface of the spinning unit 22, and FIG. FIG.

  As shown in FIG. 2, each spinning unit 22 is provided with a material holding tank 15 for storing a solution containing a polymer substance, and the solution is fed from the material holding tank 15 through a material supply pipe 14 to the spinning unit 22. Are supplied to a plurality of nozzles 1 provided in the interior of the nozzle. The plurality of nozzles 1 are integrally formed with a conductive plate 2 that is a metal block of a conductive material, and are two-dimensionally arranged vertically and horizontally on a straight line (lattice shape). In the electrostatic spraying apparatus of the first embodiment, the conductive plate 2 has a function of a solution reservoir for temporarily storing a solution containing a polymer substance as a material, and a plurality of nozzles 1 are provided below the solution reservoir. Yes. The plurality of nozzles 1 and the conductive plate 2 constitute a spray block 30 serving as a spray portion.

  On the conductive plate 2 of the spray block 30 configured as described above, a solution prepared by mixing a polymer substance such as polyurethane as a nanofiber material with a solvent such as toluene is independent for each spinning unit 22. The material is supplied from the material holding tank 15 disposed through the material supply pipe 14.

In the electrostatic spraying apparatus of the first embodiment, the spray block 30 having the plurality of nozzles 1 and the conductive plate 2 is integrally formed by pressing a metal block, for example, an aluminum material or a stainless material, but is manufactured by cutting. You may do it. The nozzle 1 has a spray port of a predetermined diameter and is formed in a conical shape with a sharp tip, and is configured so that the solution reservoir of the conductive plate 2 and the spray port communicate with each other.

  The conductive plate 2 has a configuration in which a high voltage (for example, a high voltage of several kilovolts to several tens of kilovolts) is applied from the first power source 40, and the upper portion of the conductive plate 2 where the nozzle 1 is not disposed is an insulating resin. The insulating cover 9 is covered. The insulating cover 9 holds the solution in the solution reservoir of the conductive plate 2 in a state in which dust and the like are prevented from being mixed. Further, in the spinning unit 22, the spray block 30 is fixed while being insulated from the housing 10 by the insulating cover 9.

  In addition, an insulating sheet 5 and a first collector 4 made of a thin metal plate are stacked in order from the top so as to face the nozzle 1 on the entire lower surface inside the spinning unit 22. In the electrostatic spraying apparatus according to the first embodiment, the first collector 4 is grounded. However, a voltage of an electrode different from the spray block 30 may be applied.

  FIG. 6 is a cross-sectional view of a spray portion having the spray block 30 and the insulating cover 9 and the like covering the spray block 30 in the spinning unit 22 of the electrostatic spraying apparatus of the first embodiment. In addition to the spray block 30 and the insulating cover 9, a material supply pipe 14 and a material holding tank 15 are provided in the spray portion. FIG. 7 is an exploded perspective view of the spray portion of FIG.

  The conductive plate 2 formed integrally with the plurality of nozzles 1 is formed in a saucer shape, and the plurality of nozzles 1 having a conical and sharply sprayed nozzle at the bottom portion thereof are two-dimensionally on a vertical and horizontal straight line. That is, they are arranged at equal intervals from each other at positions that are lattice-like intersections. As described above, the spray block 30 having the conductive plate 2 and the plurality of nozzles 1 is integrally formed by pressing a metal block. A solution containing a polymer is accommodated in the space of the tray portion which is a recessed space of the conductive plate 2, and the amount of the solution is always constant from the material holding tank 15 through the material supply pipe 14. Supplied as The plurality of nozzles 1 arranged on the bottom surface of the conductive plate 2 are arranged so that the intervals in the vertical and horizontal rows are the same. In Example 1, 48 nozzles 1 of 4 rows × 12 columns were formed on the conductive plate 2 having a size of 250 mm (width) × 500 mm (length) × 180 mm (height). The size of the conductive plate 2 and the number of nozzles 1 are examples, and the specifications and the production speed of the nonwoven fabric to be produced, the voltage applied to the nozzle 1 and the spray direction of the nozzle 1 flow substantially orthogonally. It is appropriately set according to the strength of the air flow 17.

  The material used for the spray block 30 is preferably a conductive material that is generally easy to process, such as stainless steel. If the inner diameter of the spray port of the nozzle 1 is too thin, liquid clogging may occur. Conversely, if it is too thick, liquid dripping will occur. Therefore, it is preferably within a range of 0.1 mm to 1.0 mm. The through hole that becomes the spray port of the nozzle 1 is processed with high accuracy by drilling. Further, the height of the nozzle 1 (distance from the tip serving as the spray port of the conical nozzle 1 to the root) during press working is at least 5 mm or more in order to use the property that charges are concentrated on a pointed portion. Is formed. The spray block 30 having the conductive plate 2 and the nozzle 1 formed as described above is covered with an insulating cover 9 made of an insulating resin and fixed to each other.

  The insulating cover 9 serves as a lid for the saucer-shaped recessed space formed on the conductive plate 2, and the polymer substance injected into the recessed space of the conductive plate 2 from the material holding tank 15 via the material supply pipe 14. This prevents the contamination of contaminants and other solutions. The solution stored in the recessed space of the conductive plate 2 flows into each nozzle 1 integrally provided at the bottom of the conductive plate 2 and is sprayed.

  In the electrostatic spraying apparatus of the first embodiment, an organic solvent such as toluene is used as a solvent in order to make a polymer material or the like into a solution, so that the insulating cover 9, the material supply pipe 14, the material holding tank 15, etc. As the material of the portion in contact with the solution, a resin material such as a fluororesin having corrosion resistance, PE (polyethylene resin) or PP (polypropylene resin) is preferable.

  The solution containing the polymer supplied from the material holding tank 15 to the conductive plate 2 through the material supply pipe 14 is uniformly supplied to each nozzle 1 provided on the bottom surface of the concave space of the conductive plate 2. The level of the solution is constantly detected by using a general level detector so that all the nozzles 1 are sufficiently filled with the solution and the solution is held at a predetermined level in the recessed space of the conductive plate 2. Then, it is comprised so that a solution may be supplied.

  As shown in FIG. 7, the insulating cover 9 is formed with a mounting hole 12 for mounting the material supply pipe 14 and a recess for fitting the solution reservoir of the spray block 30 to be sealed. Yes. The material supply pipe 14 and the spray block 30 are configured to be easily removable from the insulating cover 9 and have a structure excellent in maintenance properties such as cleaning.

  The casing that forms the outer surface of the spinning unit 22 is a resin that is an insulator, is formed of a resin that has rigidity to support its own load, and a flange 11 that is attached to the duct of the collection unit 13. Is provided. Each spinning unit 22 is configured such that the flange 11 of the housing 10 is screwed to the duct with a bolt and is easily detached. An opening which is an air inlet 6 serving as an air flow forming means is formed on the back side of the housing 10, that is, on the side surface opposite to the flange 11. The air inlet 6 is provided with a metal net 16 that is electrically insulated from the housing 10. The metal net 16 is connected to the second power source 50. The second power supply 50 is supplied with a voltage that is lower than the voltage supplied from the first power supply 40 and has the same polarity. The reference potential is the wall surface of the duct that constitutes the collection unit 13, and the reference potentials of the first power source 40 and the second power source 50 are also the wall surfaces of the duct. The reference potential is usually connected to earth ground.

  When a high voltage from the first power supply 40 is applied to the conductive plate 2, an electric charge is generated by an electrostatic electric field. The charge has a property of concentrating on the pointed portion, and the charge is concentrated on the tip portion of the nozzle 1. The high voltage applied to the conductive plate 2 is determined by the material and viscosity of the solution, the material and diameter of the nanofibers produced, the manufacturing environment (temperature and humidity), and the range is several kilovolts to several tens of kilovolts. is there. As described above, the electric charge concentrates on the tip portion of the nozzle 1, so that the surface tension portion of the liquid at the nozzle tip portion is charged. The minute charged particles 3 at the tip of the nozzle are separated from the tip of the nozzle 1 by the strong electric field generated between the first collector 4 and the first collector 4 disposed through the insulating sheet 5 facing the nozzle 1 and charged droplets. Become sprayed. Since the sprayed charged droplets have the same polarity, they are repelled by the mutual Coulomb force, are uniformly diffused, and are attracted to the first collector 4.

  The distance from the tip of the nozzle 1 to the first collector 4 is preferably a distance of several tens of centimeters to several tens of centimeters. In Example 1, the distance was 20 centimeters. The distance from the tip of the nozzle 1 to the first collector 4 is determined in consideration of the specifications of the nanofiber to be generated, the value of the applied voltage, and the like. Therefore, you may comprise so that the position of the 1st collector 4 and the insulating sheet 5, or the nozzle 1 can be changed relatively.

  As described above, the mist-like liquid droplets sprayed from the tip portion of the nozzle 1 are charged, and the charges are attracted to the different polarity, so that they are sucked toward the first collector 4. On the way of the charge toward the first collector 4, since the liquid droplet is charged, the liquid particle is repeatedly divided by electrostatic repulsion several times, and the size of the liquid particle becomes finer. In this way, when the liquid droplets become finer, the solvent used as a solvent to make the material into solution evaporates, leaving only the nanofiber material. They are in a fiber state called nanofibers with a fiber diameter of several nanometers to several tens of nanometers.

  Even if the solution containing the polymer substance is in the nanofiber state, that is, the liquid is in the solid state, the charge initially given from the nozzle 1 is not lost and remains in the charged state. is there.

  In the spinning unit 22 of the electrostatic spraying apparatus of Example 1, the insulating sheet 5 is disposed between the nozzle 1 and the first collector 4 with a distance of several millimeters with respect to the first collector 4. ing. The distance between the first collector 4 and the insulating sheet 5 is set in the range of several millimeters to several tens of millimeters in consideration of the polymer material, the charge amount, and the like. The insulating sheet 5 is made of a dielectric material and has a sheet shape or a thin plate shape.

  Since the insulating sheet 5 has a property of inducing electric polarization by an external electric field, that is, a property showing induced polarization, due to the property of the dielectric material, the conductive plate 2 which is a metal block is at the time when a high voltage is applied. The surface is charged and induced polarization occurs. In the induced polarization, the surface of the insulating sheet 5 facing the spray port of the nozzle 1 has the same polarity as the metal block. Therefore, the material that is sprayed from the spray port of the nozzle 1 and becomes nanofibers due to the Coulomb force of “repulsive charges of the same pole” has the same pole as the insulating sheet 5, and therefore the charged insulating sheet 5 Repels against it. As a result, the material that has become nanofibers (fibers) is in a state of floating in a space of several tens of centimeters to several tens of centimeters from the insulating sheet 5 between the spray port of the nozzle 1 and the insulating sheet 5.

  In the spinning unit 22 of the electrostatic spraying apparatus of the first embodiment, the second power source 50 is connected to the metal mesh 16 provided on the back surface thereof, and a voltage of several tens to several hundred volts is applied to the metal mesh 16. Is applied. The polarity of the voltage applied to the metal net 16 is the same as the polarity of the voltage applied to the nozzle 1. On the other hand, a voltage of several volts is applied to the second collector 7 in the collection unit 13 disposed so as to face the metal net 16, and the polarity of the voltage is different from that of the metal net 16. . The voltage applied to the second collector 7 is set in the range of several volts to several hundred volts in consideration of the polymer material and the charge amount thereof, or set to the ground potential which is the reference potential. Is done. Therefore, the nanofiber charged in a floating state in the space between the spray port of the nozzle 1 and the insulating sheet 5 repels the metal net 16 having the same polarity, and has a second potential having a different polarity due to the Coulomb force. Is sucked in the direction of the collector 7.

  Furthermore, in the electrostatic spraying apparatus of Example 1, the dry air is sent to the spinning unit 22 attached to the collection unit 13 through the metal net 16 in the direction of the second collector 7 inside the duct 13. It is configured. The inside of the duct 13 is configured so as to reliably collect the nanofibers at a pressure lower than the ambient air pressure, that is, a negative pressure. Moreover, the dry air sent into the spinning unit 22 is set to a humidity of 40% or less, and transports the nanofibers floating in the spinning unit 22 in a dry state.

  As described above, in the electrostatic spraying apparatus of Example 1, the inside of the collection unit 13 is set to a negative pressure, and the second collector 7 is set to an electrode different from the electrode of the metal net 16 or a ground potential. And it becomes the structure which can collect nanofiber reliably inside the collection part 13 by blowing dry air toward the duct 13 from the metal net | network 16. FIG. In the first embodiment, each spinning unit 22 is provided with a fan so as to send indoor dry air (humidity of 40% or less). However, a duct may be provided so that dry air having a desired humidity is sent from the outside of the apparatus. .

  The reason for using the metal net 16 in Example 1 is to send dry air from the back of the spinning unit 22 and to ensure the generation of the air flow 17 in the direction of the collection unit 13. Any other member may be used as long as it has, for example, a conductive member having a structure in which a plurality of through holes are formed in a metal plate insulated from the housing 10.

  In addition, in the spinning unit 22 of the electrostatic spraying apparatus of Example 1, the air inlet 6 having a wire mesh structure was provided as an air flow forming unit, but the air inlet 6 in the present invention may not have a wire mesh structure. For example, a structure in which dry air whose air pressure has been adjusted can be introduced from an air inlet formed at the rear side end of the spray block 30 may be employed. In this case, the metal block in which the air inlet 6 is formed is connected to the first power source 40 and a voltage having the same polarity as that of the nozzle 1 is applied. As a result, an air flow 17 directed from the air inlet 6 toward the collecting portion 13 is generated in the space between the nozzle 1 and the insulating sheet 5, and charged nano particles from the air inlet 6 to the second collector 7 are generated. The structure is such that a fiber suction operation occurs.

  As described above, the nanofibers floating in the spinning unit 22 are fed in the direction of the collection unit 13 and sucked and collected on the surface of the collection sheet 8 conveyed along the second collector 7. And stacked. As a result, a polymer web made of nanofibers can be formed. For this reason, the slower the conveyance speed of the collection sheet 8, the longer it takes for the collection sheet 8 to pass through the spinning unit 22, and the more nanofibers are collected and stacked per unit area. As a result, it is possible to increase the thickness of the polymer web of nanofibers, which are non-woven fabrics. Moreover, the thickness of the nonwoven fabric can be increased as the number of spinning units 22 attached to the collection unit 13 is increased. By utilizing this, the thickness of the nanofiber polymer web nonwoven fabric can be controlled by the number of spinning units 22 to be mounted and / or the conveying speed of the collection sheet 8.

Since the nanofiber sprayed from the nozzle 1 is collected and stacked on the collection sheet 8 conveyed along the surface of the second collector 7, the charge of the nanofiber minute charged particles 3 is: It does not collect in the space between the spray port of the nozzle 1 and the insulating sheet 5 that is a dielectric material, and is conveyed in the direction of the second collector 7 according to the air flow 17. Therefore, in the electrostatic spraying apparatus of Example 1, materials are sprayed one after another from the nozzle 1, and a desired nonwoven fabric can be manufactured.
As described above, in the electrostatic spraying apparatus of Example 1, charges are accumulated between the spray port and the collector, which was a problem of the above-described conventional apparatus, and a new charge from the nozzle is generated by repulsion of the stayed charges. This solves the problem that the sprayed material cannot be sprayed.

  In the electrostatic spraying apparatus of Example 1, dry air is sent through the air inlet 6 of the spinning unit 22 attached to the collection unit 13, and the pressure inside the collection unit 13 is lower than the ambient air pressure. That is, the nanofibers are collected at a negative pressure. The feed rate of the dry air is such that the nanofibers are smoothly collected on the collection sheet 8 and the air flow produces a weak wind speed of about several centimeters / second so that the internal air flow of the spinning unit 22 is not disturbed. good. A strong wind speed of several tens of centimeters / second or more is not preferable because the trapped state is agitated due to the pressure of the air and generation of extra static electricity.

  The structure of injecting dry air in Example 1 enables not only measures against scattering of the nanofibers but also recovery of the organic solvent contained in the material solution. The material used in Example 1 uses an organic solvent or the like as a solvent because the polymer is used in a solution state as described above, and a large amount of the organic solvent is used during production. The recovery of organic solvents that vaporize during spraying has not been considered with conventional devices, and health hazards and fires from vaporized organic solvents are a major concern, as are the health hazards to the human body due to the scattering of nanofibers. there were. In the electrostatic spraying apparatus of the first embodiment, a recovery unit 19 is provided on the top of the collection unit 13 so as to collect dry air containing organic matter and the like from the spinning unit 22 through the collection unit 13. . The collection unit 19 is configured to discharge to a collection device (not shown) provided outside the device using a fan.

Hereinafter, the nanofiber collecting operation in the electrostatic spraying apparatus of Example 1 will be further described.
Dry air having a humidity of 40% or less is sent to each spinning unit 22 through the air inlet 6 using a conveyance path forming means such as a pipe or a duct, and the inside of the collection unit 13 communicating with each spinning unit 22 is collected. By making the negative pressure by the unit 19, the organic solvent vaporized in each spinning unit 22 or the like is sent into the collection unit 13 without being discharged outside the apparatus, and is collected by the collection unit 19. Thus, the electrostatic spraying apparatus of Example 1 has a structure that can reliably recover the vaporized organic solvent without leaking to the outside of the apparatus. In the collection unit 19 in the first embodiment, an exhaust fan is built in like the general draft chamber, and the wind speed to the collection unit 19 in the collection unit 13 is several centimeters to 10 centimeters / second. The inside of the collection unit 13 is set to a weak negative pressure of about 0.02 KPa with respect to the spinning unit 22.

  As described above, in the electrostatic spraying apparatus of Example 1, the collection unit 13 is set to a negative pressure by setting the collection unit 19 to a negative pressure, and the generated nanofibers are collected in the collection unit 13. It is a structure in which the organic solvent evaporated in the spinning unit 22 and the like is collected through the duct 13 while being stacked on the inner collection sheet 8.

In the electrostatic spraying apparatus of the first embodiment, the structure in which dry air is fed from each spinning unit 22 into the duct 13 is important, but mainly in the spinning unit 22 from the air inlet 6 toward the collection sheet 8. In this case, any structure may be used as long as the air flow is stably generated.
In addition, the electrostatic spraying apparatus of Example 1 is provided with a control device so that each spinning unit 22 can be driven independently, and the necessary spinning unit 22 is selected and selected according to the product to be manufactured. In this configuration, only the spinning unit 22 can be driven.

As described above, the electrostatic spraying apparatus of the present invention can perform stable electrostatic spraying using a plurality of nozzles, and can achieve mass production in response to a desired product.
As described above, by using the electrostatic spray device of the present invention, it is possible to mass-produce non-woven fabrics and filters formed of nanofiber fibers of several nanometers [nm] to several tens of nanometers [nm]. Become. Therefore, the filter manufactured by the electrostatic spraying device of the present invention can cover the role of the conventional filter, and can also remove dust and fungi, such as carbon bacteria, which could not be removed by the conventional filter. Become.
In addition, the filter manufactured by the electrostatic spraying apparatus of the present invention has an excellent effect not only in “removal” but also in “selection”. Capturing particles of several nanometers with a filter is not limited to removing unnecessary materials, and it is possible to take out the nanoparticles. For example, in the case of diamond abrasive grains or the like, if only abrasive grains of several tens of nanometers [nm] can be selected, the conventional polishing accuracy can be improved by two orders of magnitude or more. Moreover, the filter manufactured by the electrostatic spraying device of the present invention can also be used for drug delivery (drug delivery). As described above, the electrostatic spraying apparatus and the electrostatic spraying method of the present invention have excellent characteristics in “sorting” at the nano level.
In addition, products manufactured by the electrostatic spray device of the present invention can be used for regenerative medicine such as “artificial biological membranes” currently in the research stage, and the present invention is also expected from such special fields. Has been.

  The electrostatic spraying apparatus of the present invention is useful in an apparatus that stably performs electrostatic spraying using a plurality of nozzles to achieve mass production.

  The present invention relates to an electrostatic spraying apparatus and electrostatic spraying method for electrostatic spraying of a solution containing a polymer substance.

  Electrospraying is a solution in which a polymer substance, which is the material to be applied, is mixed with a solvent to form a solution, and the solution is stored in a container with a sharp tip, such as a needle tip of a syringe or a thin glass tube. This is done by applying a high voltage between the container and the spray object. In electrostatic spraying, a charge is given to the polymer substance in the container, and the charged polymer substance becomes a mist due to the repulsive force of the charge, from the tip of the container, using the Coulomb force to the spray side ( The light is emitted to the side called the collector having a different polarity from the container tip side) or to the ground side (ground side), and collected and stacked on the collector side. Electrostatic spraying is one that uses electrostatic spraying, and electrostatic coating for automobile bodies such as automobiles is generally known as an electrostatic coating application. Electrostatic coating is applicable not only to vehicle body coating but also to various other things. In particular, the present invention relates to an apparatus for electrostatic spraying using an artificial polymer substance as a material, and relates to an apparatus that can easily manufacture a nonwoven fabric having a fiber size smaller than 100 nanometers [nm], that is, a fiber size called a nanofiber. It is. The nonwoven fabric thus manufactured can be used in a wide range of filters and the like.

  The filter can also be manufactured using a “melting method” which is one of the conventional methods for manufacturing nonwoven fabrics. However, in such a conventional manufacturing method, a filter manufactured using a fiber having a diameter of several tens of micrometers is the mainstream, and it is limited to make a filter using a fiber having a size of several hundred nanometers. As described above, in the manufacturing method using electrostatic spraying, it is possible to manufacture a non-woven fabric having a fiber diameter that is one or two orders of magnitude thinner than a manufacturing method using a conventional “melting method” or the like. In electrostatic spraying, if only one nozzle has a spray port, only a few centimeter square filter can be manufactured. From the viewpoint of mass productivity and productivity, the nozzle that serves as the spray port A single configuration is not realistic. In the case of textile manufacturers and raw film manufacturers, it is necessary to use a plurality of nozzles when manufacturing a product with a width of 100 centimeters or a size similar to that of nonwoven fabrics and films manufactured by conventional manufacturing methods. was there.

  However, when using a plurality of nozzles, there is a problem that the operation state of electrostatic spraying is not stable due to the influence of charge interference or repulsion, and electrostatic spraying from some or most of the plurality of arranged nozzles. There was a case that could not be done. Therefore, in order to put the electrostatic spraying apparatus having a plurality of nozzles into practical use and mass production, it has been a problem to perform stable electrostatic spraying using the plurality of nozzles.

  In order to achieve the above object, Japanese Patent Laid-Open No. 2002-201559 proposes a mechanism called charge distribution plate for suppressing charge interference and repulsion. However, the position of the charge distribution plate has to be changed depending on the magnitude of the voltage applied for electrostatic spraying, which is not easy to handle. In addition, when a plurality of nozzles are arranged in a plurality of states in a plurality of vertical and horizontal directions, the use of the charge distribution plate deteriorates the ratio of the coating amount (lamination amount) to the spray amount, so-called collection efficiency. There was a problem.

Japanese Patent Application Laid-Open No. 8-153669 discloses a method of applying a high voltage by providing electrodes on the mounting surface of the nozzle and the spray object. In this manner, in the method of providing the electrodes on the nozzle and the mounting surface and electrostatically spraying the spray object, the electrostatically sprayed material is laminated so as to cover the surface of the counter electrode which is the mounting surface. Therefore, the ability of electrostatic spraying gradually weakens. Therefore, in the manufacturing method disclosed in Japanese Patent Laid-Open No. 8-153669, it is difficult to perform electrostatic spraying with high accuracy over a long period of time, and the manufacturing method is not suitable for mass production.
JP 2002-201559 A JP-A-8-153669

  The material sprayed with electrostatic charge is attracted to a collector, which is a collecting surface (stacked surface) having a charge of a different polarity, and collected (stacked) on the collector. Since the sprayed materials have the same polarity, they repel each other due to the Coulomb force, diffuse and reach the collector in a uniform state. At the same time as the material is collected (laminated) by the collector, a charge is released to the collector. The collector must always hold an equivalent amount of pole charge different from the charge of the material even after the charge has been released, or be grounded. This is because when the material sprayed one after another is sucked and collected by the collector, if the collector holds an equivalent amount of charge of a different polarity or is grounded, the charge is charged between the nozzle spray port and the collector. The material is smoothly sucked from the spray port toward the collection surface (lamination surface) without electrostatic accumulation, and electrostatic spraying is performed. However, when the amount of charge carried by the sprayed material increases, a state occurs in which charge accumulates between the spray port and the collector. Since the accumulated charge and the charge of the material to be sprayed are of the same polarity, they are repelled by Coulomb's law, and the spray operation from the spray port is suppressed, and electrostatic spray from the nozzle spray port The phenomenon that cannot be performed occurs. Such a phenomenon occurs similarly in a configuration in which one nozzle is provided or a configuration in which a plurality of nozzles are provided. The inventors conducted an experiment using an electrostatic spraying device having both a configuration in which one nozzle is provided and a configuration in which a plurality of nozzles are provided, and gradually increases the applied voltage to increase the polymer material. It has been confirmed that the electrostatic spraying is stopped by increasing the amount of electric charge. However, in the case of an electrostatic spraying device provided with a single nozzle, the amount of charge charged by the polymer material to be sprayed is smaller than in the case of an electrostatic spraying device provided with a plurality of nozzles. This configuration facilitates electrostatic spraying.

  If a plurality of nozzles are used in order to increase productivity, the amount of charge inevitably increases, and repulsion between charges increases, so electrostatic spraying often cannot be performed. For this reason, it is necessary to reduce the amount of charge, specifically, to reduce the applied voltage. However, when the applied voltage is reduced in this way, a problem arises that the spraying speed is lowered and the productivity is deteriorated. In addition, repulsive force of charge is necessary for spraying from the spray nozzle at the tip of the nozzle. However, when the applied voltage is lowered to reduce the charge, the repulsive force necessary for spraying is insufficient and spraying may not be possible.

  Therefore, even when the electrostatic spraying is performed efficiently in the configuration in which one nozzle is provided, for example, in a configuration in which a plurality of nozzles are provided even when the voltage and the spraying distance are set to be the same, There are many cases in which electrostatic spraying from a part or most cannot be performed. For this reason, when electrostatic spraying is performed even in a configuration in which a plurality of nozzles are provided under conditions where electrostatic spraying can be efficiently performed in a configuration in which one nozzle is provided, a special configuration is required.

  For example, in a conventional electrostatic spraying device, the collector is arranged parallel to the spray ports of a plurality of nozzles, and the collector is made of aluminum foil so that no electric charge is accumulated between the spray ports and the collector. For this, a material having good conductivity is used and / or the area of the collector is made as large as possible. However, even with such a configuration, a certain degree of effect can be expected, but it is not improved drastically and is not a fundamental solution.

  Moreover, in the conventional electrostatic spraying apparatus, even when electrostatic spraying is performed, the collection efficiency is low, and collection (stacking) only at the intended location is not possible, and things that are not collected around the apparatus are scattered. Have the problem. The problem of such scattering was confirmed by the present inventors performing electrostatic spraying by covering the apparatus with a cover such as acrylic. The problem of not being able to collect (laminate) the sprayed material in this way naturally leads to loss of the material, but not only that of fibers with a fiber diameter of several nanometers to tens of nanometers. It is necessary to pay attention to the health damage of workers due to the large amount of scattering.

  The present invention can stably perform electrostatic spraying using a plurality of spraying means, and can mass-produce products with high collection efficiency, excellent productivity, and high accuracy. An object is to provide a high electrostatic spraying device and an electrostatic spraying method.

  The electrostatic spraying apparatus and the electrostatic spraying method according to the present invention are configured as follows in order to solve various problems in the above-described conventional electrostatic spraying apparatus.

The electrostatic spraying device of the present invention is a plurality of nozzles arranged two-dimensionally to electrostatically spray a polymer solution containing a polymer substance and formed into a liquid state using a solvent, and opposed to the plurality of nozzles A plurality of spinning units having a first collector that is arranged via an insulating sheet and is grounded to a voltage of a polarity different from the voltage applied to the nozzle or a ground potential,
A first power source for applying a predetermined high voltage to the nozzle; and a collection unit to which the spinning unit is attached and movably holds a collection sheet,
The spinning unit includes air flow forming means that forms an air flow in a direction perpendicular to a spraying direction from the nozzle to the first collector and toward the collection sheet. The electrostatic spraying device of the present invention configured as described above can continuously perform electrostatic spraying stably and with high collection efficiency.

The electrostatic spraying method of the present invention includes a step of supplying a polymer solution containing a polymer substance and formed into a liquid state using a solvent to a plurality of nozzles arranged two-dimensionally,
Applying a high voltage to the nozzle to electrostatically spray the polymer solution from the nozzle;
Generating a flow of air that flows in a direction substantially perpendicular to the direction of electrostatic spraying in the spinning unit having the nozzle, and applying the air flow to the electrostatically sprayed and charged polymer material, A step of laminating the polymer substance on a collection sheet disposed in a direction substantially orthogonal to the flow direction of The above-described electrostatic spraying method of the present invention can reliably perform electrostatic spraying stably and with high collection efficiency.

According to the present invention, an electrostatic spraying apparatus capable of mass-producing a product with high collection efficiency, excellent productivity, and high accuracy using nozzles arranged two-dimensionally as a plurality of spraying means, and An electrostatic spraying method can be provided.
Moreover, according to this invention, since the organic solvent generate | occur | produced in an electrostatic spray process can be collect | recovered reliably, an electrostatic spray apparatus and an electrostatic spray method with high safety | security can be provided.

  Hereinafter, preferred embodiments of an electrostatic spraying apparatus and an electrostatic spraying method of the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a side view showing a schematic configuration of an electrostatic spraying apparatus according to a first preferred embodiment of the present invention. In the electrostatic spraying apparatus of Example 1, a solution containing a polymer substance is ejected from a nozzle by electrostatic spraying to produce fibers thinner than 100 nanometers [nm], that is, fibers called nanofibers. Is to be manufactured.

  First, the outline | summary of preparation of the nanofiber nonwoven fabric by electrostatic spraying of the electrostatic spraying apparatus of Example 1 which concerns on this invention using FIG. 1 is demonstrated. In order to produce nanofiber nonwoven fabric by collecting and laminating nanofiber fibers, a base substrate is required. As the substrate, for example, a collection sheet 8 that is an insulating resin sheet such as polyethylene is used. The collection sheet 8 is sent out from the supply roller 20 and taken up by the take-up roller 21 via a plurality of intermediate rollers 18 capable of controlling the conveyance speed. In the electrostatic spraying apparatus of Example 1, the conveying speed of the collection sheet 8 is determined by the thickness of the nonwoven fabric, the fiber diameter of the nanofiber, the material, and the like, and is configured to be able to handle a wide range of several meters to several hundred meters per minute. Has been.

  The collection sheet 8 as a substrate is conveyed through a section from the supply roller 20 to the winding roll 21 via the plurality of intermediate rollers 18. The plurality of spinning units 22 are provided along the conveyance path of the collection sheet 8. The spinning unit 22 is attached to a duct of a collection unit 13 having a collection sheet 8 in which nanofiber fibers are collected and stacked. When the collection sheet 8 passes through the inside of the collection unit 13, the nanofiber fibers from the spinning unit 22 are stacked on the collection sheet 8 with a thickness of several hundred nanometers to several hundred micrometers.

  As shown in FIG. 1, the spinning unit 22 is mounted substantially horizontally so as to be orthogonal to the side surface of the duct of the collecting portion 13 extending in the vertical direction or the horizontal direction, and each has an independent configuration. is doing. The number of the spinning units 22 attached is arbitrarily set according to the production speed and specifications of the nanofiber nonwoven fabric to be manufactured. In the electrostatic spraying apparatus of the first embodiment, the number of the spinning units 22 that can be mounted can be freely selected from the maximum number that can be mounted on the collection unit 13 when the number of the spinning units 22 is one. Further, since each spinning unit 22 is configured to operate independently, it is possible to operate only an arbitrary selected spinning unit 22 with the spinning unit 22 mounted. Therefore, in the electrostatic spraying apparatus according to the first embodiment, it is possible to remove a specific spinning unit 22 without stopping production and cope with a failure or maintenance of the spinning unit 22. In addition, if an accident occurs suddenly in some of the spinning units 22 during production, it is possible to continue production without stopping the entire device by simply stopping the relevant spinning unit 22. It is.

  Moreover, in the electrostatic spraying apparatus of Example 1, the material supplied to each spinning unit 22 does not need to be the same. Each spinning unit 22 is provided with a material holding tank 15 (see FIG. 2), which will be described later, for supplying material to the nozzles. Therefore, different materials are supplied to each spinning unit 22 and different materials are stacked. It is possible to produce a non-woven fabric. Of course, it is also possible to supply the same material to each spinning unit 22 to hold the same material in each material holding tank 15, and to connect the same supply pipe to each spinning unit 22 to the same material. It is also possible to have a configuration that always supplies.

  Next, the configuration and operation of the spinning unit 22 in the electrostatic spraying apparatus of Example 1 will be described.

  FIG. 2 is a side cross-sectional view showing the configuration of the plurality of spinning units 22 attached to the collection unit 13. 3 to 5 are diagrams showing the configuration of the spinning unit 22, FIG. 3 is a perspective view showing the spinning unit 22, FIG. 4 is a front view showing the mounting surface of the spinning unit 22, and FIG. FIG.

  As shown in FIG. 2, each spinning unit 22 is provided with a material holding tank 15 for storing a solution containing a polymer substance, and the solution is fed from the material holding tank 15 through a material supply pipe 14 to the spinning unit 22. Are supplied to a plurality of nozzles 1 provided in the interior of the nozzle. The plurality of nozzles 1 are integrally formed with a conductive plate 2 that is a metal block of a conductive material, and are two-dimensionally arranged vertically and horizontally on a straight line (lattice shape). In the electrostatic spraying apparatus of the first embodiment, the conductive plate 2 has a function of a solution reservoir for temporarily storing a solution containing a polymer substance as a material, and a plurality of nozzles 1 are provided below the solution reservoir. Yes. The plurality of nozzles 1 and the conductive plate 2 constitute a spray block 30 serving as a spray portion.

  On the conductive plate 2 of the spray block 30 configured as described above, a solution prepared by mixing a polymer substance such as polyurethane as a nanofiber material with a solvent such as toluene is independent for each spinning unit 22. The material is supplied from the material holding tank 15 disposed through the material supply pipe 14.

In the electrostatic spraying apparatus of the first embodiment, the spray block 30 having the plurality of nozzles 1 and the conductive plate 2 is integrally formed by pressing a metal block, for example, an aluminum material or a stainless material, but is manufactured by cutting. You may do it. The nozzle 1 has a spray port of a predetermined diameter and is formed in a conical shape with a sharp tip, and is configured so that the solution reservoir of the conductive plate 2 and the spray port communicate with each other.

  The conductive plate 2 has a configuration in which a high voltage (for example, a high voltage of several kilovolts to several tens of kilovolts) is applied from the first power source 40, and the upper portion of the conductive plate 2 where the nozzle 1 is not disposed is an insulating resin. The insulating cover 9 is covered. The insulating cover 9 holds the solution in the solution reservoir of the conductive plate 2 in a state in which dust and the like are prevented from being mixed. Further, in the spinning unit 22, the spray block 30 is fixed while being insulated from the housing 10 by the insulating cover 9.

  In addition, an insulating sheet 5 and a first collector 4 made of a thin metal plate are stacked in order from the top so as to face the nozzle 1 on the entire lower surface inside the spinning unit 22. In the electrostatic spraying apparatus according to the first embodiment, the first collector 4 is grounded. However, a voltage of an electrode different from the spray block 30 may be applied.

  FIG. 6 is a cross-sectional view of a spray portion having the spray block 30 and the insulating cover 9 and the like covering the spray block 30 in the spinning unit 22 of the electrostatic spraying apparatus of the first embodiment. In addition to the spray block 30 and the insulating cover 9, a material supply pipe 14 and a material holding tank 15 are provided in the spray portion. FIG. 7 is an exploded perspective view of the spray portion of FIG.

  The conductive plate 2 formed integrally with the plurality of nozzles 1 is formed in a saucer shape, and the plurality of nozzles 1 having a conical and sharply sprayed nozzle at the bottom portion thereof are two-dimensionally on a vertical and horizontal straight line. That is, they are arranged at equal intervals from each other at positions that are lattice-like intersections. As described above, the spray block 30 having the conductive plate 2 and the plurality of nozzles 1 is integrally formed by pressing a metal block. A solution containing a polymer is accommodated in the space of the tray portion which is a recessed space of the conductive plate 2, and the amount of the solution is always constant from the material holding tank 15 through the material supply pipe 14. Supplied as The plurality of nozzles 1 arranged on the bottom surface of the conductive plate 2 are arranged so that the intervals in the vertical and horizontal rows are the same. In Example 1, 48 nozzles 1 of 4 rows × 12 columns were formed on the conductive plate 2 having a size of 250 mm (width) × 500 mm (length) × 180 mm (height). The size of the conductive plate 2 and the number of nozzles 1 are examples, and the specifications and the production speed of the nonwoven fabric to be produced, the voltage applied to the nozzle 1 and the spray direction of the nozzle 1 flow substantially orthogonally. It is appropriately set according to the strength of the air flow 17.

  The material used for the spray block 30 is preferably a conductive material that is generally easy to process, such as stainless steel. If the inner diameter of the spray port of the nozzle 1 is too thin, liquid clogging may occur. Conversely, if it is too thick, liquid dripping will occur. Therefore, it is preferably within a range of 0.1 mm to 1.0 mm. The through hole that becomes the spray port of the nozzle 1 is processed with high accuracy by drilling. Further, the height of the nozzle 1 (distance from the tip serving as the spray port of the conical nozzle 1 to the root) during press working is at least 5 mm or more in order to use the property that charges are concentrated on a pointed portion. Is formed. The spray block 30 having the conductive plate 2 and the nozzle 1 formed as described above is covered with an insulating cover 9 made of an insulating resin and fixed to each other.

  The insulating cover 9 serves as a lid for the saucer-shaped recessed space formed on the conductive plate 2, and the polymer substance injected into the recessed space of the conductive plate 2 from the material holding tank 15 via the material supply pipe 14. This prevents the contamination of contaminants and other solutions. The solution stored in the recessed space of the conductive plate 2 flows into each nozzle 1 integrally provided at the bottom of the conductive plate 2 and is sprayed.

  In the electrostatic spraying apparatus of the first embodiment, an organic solvent such as toluene is used as a solvent in order to make a polymer material or the like into a solution, so that the insulating cover 9, the material supply pipe 14, the material holding tank 15, etc. As the material of the portion in contact with the solution, a resin material such as a fluororesin having corrosion resistance, PE (polyethylene resin) or PP (polypropylene resin) is preferable.

  The solution containing the polymer supplied from the material holding tank 15 to the conductive plate 2 through the material supply pipe 14 is uniformly supplied to each nozzle 1 provided on the bottom surface of the concave space of the conductive plate 2. The level of the solution is constantly detected by using a general level detector so that all the nozzles 1 are sufficiently filled with the solution and the solution is held at a predetermined level in the recessed space of the conductive plate 2. Then, it is comprised so that a solution may be supplied.

  As shown in FIG. 7, the insulating cover 9 is formed with a mounting hole 12 for mounting the material supply pipe 14 and a recess for fitting the solution reservoir of the spray block 30 to be sealed. Yes. The material supply pipe 14 and the spray block 30 are configured to be easily removable from the insulating cover 9 and have a structure excellent in maintenance properties such as cleaning.

  The casing that forms the outer surface of the spinning unit 22 is a resin that is an insulator, is formed of a resin that has rigidity to support its own load, and a flange 11 that is attached to the duct of the collection unit 13. Is provided. Each spinning unit 22 is configured such that the flange 11 of the housing 10 is screwed to the duct with a bolt and is easily detached. An opening which is an air inlet 6 serving as an air flow forming means is formed on the back side of the housing 10, that is, on the side surface opposite to the flange 11. The air inlet 6 is provided with a metal net 16 that is electrically insulated from the housing 10. The metal net 16 is connected to the second power source 50. The second power supply 50 is supplied with a voltage that is lower than the voltage supplied from the first power supply 40 and has the same polarity. The reference potential is the wall surface of the duct that constitutes the collection unit 13, and the reference potentials of the first power source 40 and the second power source 50 are also the wall surfaces of the duct. The reference potential is usually connected to earth ground.

  When a high voltage from the first power supply 40 is applied to the conductive plate 2, an electric charge is generated by an electrostatic electric field. The charge has a property of concentrating on the pointed portion, and the charge is concentrated on the tip portion of the nozzle 1. The high voltage applied to the conductive plate 2 is determined by the material and viscosity of the solution, the material and diameter of the nanofibers produced, the manufacturing environment (temperature and humidity), and the range is several kilovolts to several tens of kilovolts. is there. As described above, the electric charge concentrates on the tip portion of the nozzle 1, so that the surface tension portion of the liquid at the nozzle tip portion is charged. The minute charged particles 3 at the tip of the nozzle are separated from the tip of the nozzle 1 by the strong electric field generated between the first collector 4 and the first collector 4 disposed through the insulating sheet 5 facing the nozzle 1 and charged droplets. Become sprayed. Since the sprayed charged droplets have the same polarity, they are repelled by the mutual Coulomb force, are uniformly diffused, and are attracted to the first collector 4.

  The distance from the tip of the nozzle 1 to the first collector 4 is preferably a distance of several tens of centimeters to several tens of centimeters. In Example 1, the distance was 20 centimeters. The distance from the tip of the nozzle 1 to the first collector 4 is determined in consideration of the specifications of the nanofiber to be generated, the value of the applied voltage, and the like. Therefore, you may comprise so that the position of the 1st collector 4 and the insulating sheet 5, or the nozzle 1 can be changed relatively.

  As described above, the mist-like liquid droplets sprayed from the tip portion of the nozzle 1 are charged, and the charges are attracted to the different polarity, so that they are sucked toward the first collector 4. On the way of the charge toward the first collector 4, since the liquid droplet is charged, the liquid particle is repeatedly divided by electrostatic repulsion several times, and the size of the liquid particle becomes finer. In this way, when the liquid droplets become finer, the solvent used as a solvent to make the material into solution evaporates, leaving only the nanofiber material. They are in a fiber state called nanofibers with a fiber diameter of several nanometers to several tens of nanometers.

  Even if the solution containing the polymer substance is in the nanofiber state, that is, the liquid is in the solid state, the charge initially given from the nozzle 1 is not lost and remains in the charged state. is there.

  In the spinning unit 22 of the electrostatic spraying apparatus of Example 1, the insulating sheet 5 is disposed between the nozzle 1 and the first collector 4 with a distance of several millimeters with respect to the first collector 4. ing. The distance between the first collector 4 and the insulating sheet 5 is set in the range of several millimeters to several tens of millimeters in consideration of the polymer material, the charge amount, and the like. The insulating sheet 5 is made of a dielectric material and has a sheet shape or a thin plate shape.

  Since the insulating sheet 5 has a property of inducing electric polarization by an external electric field, that is, a property showing induced polarization, due to the property of the dielectric material, the conductive plate 2 which is a metal block is at the time when a high voltage is applied. The surface is charged and induced polarization occurs. In the induced polarization, the surface of the insulating sheet 5 facing the spray port of the nozzle 1 has the same polarity as the metal block. Therefore, the material that is sprayed from the spray port of the nozzle 1 and becomes nanofibers due to the Coulomb force of “repulsive charges of the same pole” has the same pole as the insulating sheet 5, and therefore the charged insulating sheet 5 Repels against it. As a result, the material that has become nanofibers (fibers) is in a state of floating in a space of several tens of centimeters to several tens of centimeters from the insulating sheet 5 between the spray port of the nozzle 1 and the insulating sheet 5.

  In the spinning unit 22 of the electrostatic spraying apparatus of the first embodiment, the second power source 50 is connected to the metal mesh 16 provided on the back surface thereof, and a voltage of several tens to several hundred volts is applied to the metal mesh 16. Is applied. The polarity of the voltage applied to the metal net 16 is the same as the polarity of the voltage applied to the nozzle 1. On the other hand, a voltage of several volts is applied to the second collector 7 in the collection unit 13 disposed so as to face the metal net 16, and the polarity of the voltage is different from that of the metal net 16. . The voltage applied to the second collector 7 is set in the range of several volts to several hundred volts in consideration of the polymer material and the charge amount thereof, or set to the ground potential which is the reference potential. Is done. Therefore, the nanofiber charged in a floating state in the space between the spray port of the nozzle 1 and the insulating sheet 5 repels the metal net 16 having the same polarity, and has a second potential having a different polarity due to the Coulomb force. Is sucked in the direction of the collector 7.

  Furthermore, in the electrostatic spraying apparatus of Example 1, the dry air is sent to the spinning unit 22 attached to the collection unit 13 through the metal net 16 in the direction of the second collector 7 inside the duct 13. It is configured. The inside of the duct 13 is configured so as to reliably collect the nanofibers at a pressure lower than the ambient air pressure, that is, a negative pressure. Moreover, the dry air sent into the spinning unit 22 is set to a humidity of 40% or less, and transports the nanofibers floating in the spinning unit 22 in a dry state.

  As described above, in the electrostatic spraying apparatus of Example 1, the inside of the collection unit 13 is set to a negative pressure, and the second collector 7 is set to an electrode different from the electrode of the metal net 16 or a ground potential. And it becomes the structure which can collect nanofiber reliably inside the collection part 13 by blowing dry air toward the duct 13 from the metal net | network 16. FIG. In the first embodiment, each spinning unit 22 is provided with a fan so as to send indoor dry air (humidity of 40% or less). However, a duct may be provided so that dry air having a desired humidity is sent from the outside of the apparatus. .

  The reason for using the metal net 16 in Example 1 is to send dry air from the back of the spinning unit 22 and to ensure the generation of the air flow 17 in the direction of the collection unit 13. Any other member may be used as long as it has, for example, a conductive member having a structure in which a plurality of through holes are formed in a metal plate insulated from the housing 10.

  In addition, in the spinning unit 22 of the electrostatic spraying apparatus of Example 1, the air inlet 6 having a wire mesh structure was provided as an air flow forming unit, but the air inlet 6 in the present invention may not have a wire mesh structure. For example, a structure in which dry air whose air pressure has been adjusted can be introduced from an air inlet formed at the rear side end of the spray block 30 may be employed. In this case, the metal block in which the air inlet 6 is formed is connected to the first power source 40 and a voltage having the same polarity as that of the nozzle 1 is applied. As a result, an air flow 17 directed from the air inlet 6 toward the collecting portion 13 is generated in the space between the nozzle 1 and the insulating sheet 5, and charged nano particles from the air inlet 6 to the second collector 7 are generated. The structure is such that a fiber suction operation occurs.

  As described above, the nanofibers floating in the spinning unit 22 are fed in the direction of the collection unit 13 and sucked and collected on the surface of the collection sheet 8 conveyed along the second collector 7. And stacked. As a result, a polymer web made of nanofibers can be formed. For this reason, the slower the conveyance speed of the collection sheet 8, the longer it takes for the collection sheet 8 to pass through the spinning unit 22, and the more nanofibers are collected and stacked per unit area. As a result, it is possible to increase the thickness of the polymer web of nanofibers, which are non-woven fabrics. Moreover, the thickness of the nonwoven fabric can be increased as the number of spinning units 22 attached to the collection unit 13 is increased. By utilizing this, the thickness of the nanofiber polymer web nonwoven fabric can be controlled by the number of spinning units 22 to be mounted and / or the conveying speed of the collection sheet 8.

Since the nanofiber sprayed from the nozzle 1 is collected and stacked on the collection sheet 8 conveyed along the surface of the second collector 7, the charge of the nanofiber minute charged particles 3 is: It does not collect in the space between the spray port of the nozzle 1 and the insulating sheet 5 that is a dielectric material, and is conveyed in the direction of the second collector 7 according to the air flow 17. Therefore, in the electrostatic spraying apparatus of Example 1, materials are sprayed one after another from the nozzle 1, and a desired nonwoven fabric can be manufactured.
As described above, in the electrostatic spraying apparatus of Example 1, charges are accumulated between the spray port and the collector, which was a problem of the above-described conventional apparatus, and a new charge from the nozzle is generated by repulsion of the stayed charges. This solves the problem that the sprayed material cannot be sprayed.

  In the electrostatic spraying apparatus of Example 1, dry air is sent through the air inlet 6 of the spinning unit 22 attached to the collection unit 13, and the pressure inside the collection unit 13 is lower than the ambient air pressure. That is, the nanofibers are collected at a negative pressure. The feed rate of the dry air is such that the nanofibers are smoothly collected on the collection sheet 8 and the air flow produces a weak wind speed of about several centimeters / second so that the internal air flow of the spinning unit 22 is not disturbed. good. A strong wind speed of several tens of centimeters / second or more is not preferable because the trapped state is agitated due to the pressure of the air and generation of extra static electricity.

  The structure of injecting dry air in Example 1 enables not only measures against scattering of the nanofibers but also recovery of the organic solvent contained in the material solution. The material used in Example 1 uses an organic solvent or the like as a solvent because the polymer is used in a solution state as described above, and a large amount of the organic solvent is used during production. The recovery of organic solvents that vaporize during spraying has not been considered with conventional devices, and health hazards and fires from vaporized organic solvents are a major concern, as are the health hazards to the human body due to the scattering of nanofibers. there were. In the electrostatic spraying apparatus of the first embodiment, a recovery unit 19 is provided on the top of the collection unit 13 so as to collect dry air containing organic matter and the like from the spinning unit 22 through the collection unit 13. . The collection unit 19 is configured to discharge to a collection device (not shown) provided outside the device using a fan.

Hereinafter, the nanofiber collecting operation in the electrostatic spraying apparatus of Example 1 will be further described.
Dry air having a humidity of 40% or less is sent to each spinning unit 22 through the air inlet 6 using a conveyance path forming means such as a pipe or a duct, and the inside of the collection unit 13 communicating with each spinning unit 22 is collected. By making the negative pressure by the unit 19, the organic solvent vaporized in each spinning unit 22 or the like is sent into the collection unit 13 without being discharged outside the apparatus, and is collected by the collection unit 19. Thus, the electrostatic spraying apparatus of Example 1 has a structure that can reliably recover the vaporized organic solvent without leaking to the outside of the apparatus. In the collection unit 19 in the first embodiment, an exhaust fan is built in like the general draft chamber, and the wind speed to the collection unit 19 in the collection unit 13 is several centimeters to 10 centimeters / second. The inside of the collection unit 13 is set to a weak negative pressure of about 0.02 KPa with respect to the spinning unit 22.

  As described above, in the electrostatic spraying apparatus of Example 1, the collection unit 13 is set to a negative pressure by setting the collection unit 19 to a negative pressure, and the generated nanofibers are collected in the collection unit 13. It is a structure in which the organic solvent evaporated in the spinning unit 22 and the like is collected through the duct 13 while being stacked on the inner collection sheet 8.

In the electrostatic spraying apparatus of the first embodiment, the structure in which dry air is fed from each spinning unit 22 into the duct 13 is important, but mainly in the spinning unit 22 from the air inlet 6 toward the collection sheet 8. In this case, any structure may be used as long as the air flow is stably generated.
In addition, the electrostatic spraying apparatus of Example 1 is provided with a control device so that each spinning unit 22 can be driven independently, and the necessary spinning unit 22 is selected and selected according to the product to be manufactured. In this configuration, only the spinning unit 22 can be driven.

As described above, the electrostatic spraying apparatus of the present invention can perform stable electrostatic spraying using a plurality of nozzles, and can achieve mass production in response to a desired product.
As described above, by using the electrostatic spray device of the present invention, it is possible to mass-produce non-woven fabrics and filters formed of nanofiber fibers of several nanometers [nm] to several tens of nanometers [nm]. Become. Therefore, the filter manufactured by the electrostatic spraying device of the present invention can cover the role of the conventional filter, and can also remove dust and fungi, such as carbon bacteria, which could not be removed by the conventional filter. Become.
In addition, the filter manufactured by the electrostatic spraying apparatus of the present invention has an excellent effect not only in “removal” but also in “selection”. Capturing particles of several nanometers with a filter is not limited to removing unnecessary materials, and it is possible to take out the nanoparticles. For example, in the case of diamond abrasive grains or the like, if only abrasive grains of several tens of nanometers [nm] can be selected, the conventional polishing accuracy can be improved by two orders of magnitude or more. Moreover, the filter manufactured by the electrostatic spraying device of the present invention can also be used for drug delivery (drug delivery). As described above, the electrostatic spraying apparatus and the electrostatic spraying method of the present invention have excellent characteristics in “sorting” at the nano level.
In addition, products manufactured by the electrostatic spray device of the present invention can be used for regenerative medicine such as “artificial biological membranes” currently in the research stage, and the present invention is also expected from such special fields. Has been.

  The electrostatic spraying apparatus of the present invention is useful in an apparatus that stably performs electrostatic spraying using a plurality of nozzles to achieve mass production.

The figure which shows schematic structure of the electrostatic spraying apparatus of Example 1 which concerns on this invention. Sectional drawing which shows typically the state with which the several spinning unit in the electrostatic spraying apparatus of Example 1 was mounted | worn with the duct. The perspective view which shows the spinning unit of the electrostatic spraying apparatus of Example 1. FIG. The figure which shows the mounting surface of the spinning unit of the electrostatic spraying apparatus of Example 1. The figure which shows the back side of the spinning unit of the electrostatic spraying apparatus of Example 1. Sectional drawing of the spray block vicinity in the spinning unit of the electrostatic spraying apparatus of Example 1. The disassembled perspective view of the vicinity of the spray block in the spinning unit of the electrostatic spraying apparatus of Embodiment 1.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Nozzle 2 Conductive plate 3 Charged particle 4 1st collector 5 Insulation sheet 6 Air inlet 7 2nd collector 8 Collection sheet 9 Insulation cover 10 Housing | casing 11 Flange 12 Mounting hole 13 Collection part 14 Material supply pipe 15 Material Holding tank 16 Metal mesh 17 Air flow 18 Intermediate roller 19 Recovery unit 20 Supply roller 21 Winding roller 22 Spinning unit 30 Spray block 40 First power supply 50 Second power supply

Claims (20)

A plurality of nozzles arranged two-dimensionally to electrostatically spray a polymer solution containing a polymer substance and formed in a liquid state using a solvent, and arranged via an insulating sheet facing the plurality of nozzles A plurality of spinning units having a first collector grounded to a voltage of a polarity different from the voltage applied to the nozzle or to a ground potential;
A first power source for applying a predetermined high voltage to the nozzle; and a collection unit to which the spinning unit is attached and movably holds a collection sheet,
The electrostatic spraying apparatus which has an air flow formation means in which the said spinning unit forms an air flow in the direction of the said collection sheet | seat orthogonal to the spray direction from the said nozzle to the said 1st collector. The air flow forming means has an air introduction port formed at a position facing the mounting surface of the spinning unit to the collection unit, and a power source of the same polarity applied to the nozzle is provided at the air introduction port. A connected conductive member is provided,
A second collector having conductivity is disposed on the back surface of the collection sheet of the collection unit, and the second collector has a voltage or ground having a polarity different from the voltage applied to the conductive member of the air introduction port. Grounded to potential,
The electrostatic spraying device according to claim 1, wherein the collection sheet is configured to be conveyed along a surface of the second collector.   The spinning unit includes a conductive plate formed of a conductive metal integrally with the nozzle, and a polymer solution is accommodated in a recess formed in the conductive plate, and the polymer solution is supplied to the nozzle. The electrostatic spraying device according to claim 1 configured as described above. The spinning unit is
A first collector disposed opposite the nozzle;
An insulating sheet disposed between the nozzle and the first collector;
An air inlet that is formed on a surface facing the mounting surface to the collection unit, and generates an air flow to the collection unit in a direction substantially orthogonal to the spray direction of the polymer substance; The electrostatic spray device according to claim 1, comprising: A supply roller in which the collection sheet is wound into a roll, and
A take-up roller that is supplied from the supply roller and moves up the collection unit and winds up the collection sheet on which a polymer material is laminated;
The electrostatic spraying device according to claim 1, further comprising:   Each of the plurality of spinning units is attached to a collection unit having a collection sheet disposed in a direction substantially perpendicular to the direction of the air flow, and the second collector of the collection unit is electrostatically The electrostatic spray device according to claim 2, wherein the sprayed polymer material is attracted to form a polymer web on which the polymer material is laminated on the collection sheet.   The electrostatic spraying device according to claim 1, wherein the pressure in the collection unit is set to a negative pressure lower than the surrounding air pressure.   The electrostatic spraying device according to claim 1, wherein a collection unit into which air in the spinning unit flows is provided in the collection unit, and the solvent of the polymer solution is collected.   The electrostatic spraying device according to claim 1, wherein the plurality of spinning units are continuously arranged in a moving direction of the collection sheet.   The electrostatic spraying device according to claim 1, wherein a height of the nozzle is 5 mm or more, and an inner diameter at a tip of the nozzle is in a range of 0.1 mm to 1.0 mm.   The electrostatic spraying device according to claim 1, wherein the spinning unit attached to the collection unit is configured to be detachable. Supplying a polymer solution containing a polymer substance in a liquid state using a solvent to a plurality of nozzles arranged two-dimensionally;
Applying a high voltage to the nozzle to electrostatically spray the polymer solution from the nozzle;
Generating a flow of air that flows in a direction substantially perpendicular to the direction of electrostatic spraying in the spinning unit having the nozzle, and applying the air flow to the electrostatically sprayed and charged polymer material, A step of laminating the polymer substance on a collection sheet arranged in a direction substantially perpendicular to the flow direction of
An electrostatic spraying method.   The method according to claim 12, further comprising a step of laminating the polymer substance on the collection sheet by moving the polymer substance electrostatically sprayed from the nozzle by a Coulomb force in a direction orthogonal to a spraying direction. Electrostatic spraying method.   The step of supplying a polymer solution liquefied using a solvent containing a polymer substance to a plurality of nozzles has an operation of constantly detecting the amount of the polymer solution retained and keeping the level constant. Electrostatic spraying method.   A first collector disposed opposite the nozzle is applied to the nozzle in order to generate a suction force for charged droplets separated from the nozzle and electrostatically sprayed into micro charged particles. The electrostatic spraying method according to claim 12, wherein the electrostatic spraying method is grounded to a voltage having a polarity different from the voltage or an earth potential.   The second collector disposed along the surface opposite to the collection sheet surface on which the polymer substance is stacked is provided with the nozzle for generating a suction force for the finely charged particles electrostatically sprayed from the nozzle. The electrostatic spraying method according to claim 12, wherein the electrostatic spraying is grounded to a voltage having a polarity different from a voltage applied to the electrode or an earth potential.   The electrostatic spraying method according to claim 12, further comprising a step of recovering the solvent of the polymer solution from the air flow of the spinning unit.   The electrostatic spraying method according to claim 12, wherein a plurality of spinning units each having the nozzle are provided, and each has a step of independently laminating a polymer substance on the same collection sheet.   The electrostatic spraying method according to claim 18, further comprising a step of controlling operating states of the plurality of spinning units according to the specifications of the polymer web to be manufactured.   The electrostatic spraying method according to claim 18, wherein at least one of a plurality of spinning units includes a step of laminating different polymer substances on a collection sheet.

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