JP4797652B2 - Electrostatic spray device and electrostatic spray monitoring method - Google Patents

Description

  The present invention relates to a polymer substance solution electrostatic spraying apparatus and a sprayed electrostatic spray monitoring method.

  Electrostatic spraying (electrospinning) is a polymer that is the material you want to apply in solution, put the solution in a needle tip of a syringe or a pointed container, add a charge by applying a high voltage, A mist-like material charged by the repulsive force of the charge from the tip is directed to the ground or the side called the collector on the side opposite to the spray side using the Coulomb force, and the material is directed to the collector or collector. It is to make it collect (lamination) to the substrate arrange | positioned along. Generally, electrostatic coating on a vehicle body is known. It can be applied to various things, not limited to car body painting, but in the present invention, particularly when artificial spraying is performed using an artificial polymer as a material, fibers smaller than 100 nanometers, that is, fiber sizes called nanofibers are used. The non-woven fabric produced can be applied to a filter or the like.

  Filters can also be manufactured by the “melting method”, which is one of the conventional nonwoven fabric methods, but in the conventional method, a filter of a fiber with a diameter of several tens of micrometers is the mainstream, and a filter with a size of several hundreds of nanometers is made. Is the limit. As mentioned above, it is possible to create nonwoven fabrics with fiber diameters that are one or two orders of magnitude thinner than conventional ones by a method that uses electrostatic spraying. However, if there is only one nozzle that is a spray nozzle, Since only a centimeter square piece can be produced, the configuration with one nozzle serving as a spray port is not realistic from the viewpoint of mass productivity and productivity. In the case of non-woven fabrics, films, and sheets produced by conventional methods at textile manufacturers and film manufacturers, multiple nozzles must be used. .

  However, when multiple nozzles are used, the state of electrostatic spraying may not be stable due to interference or repulsion of electric charge, or electrostatic spraying may not be performed from some or most of the arranged nozzles. It is necessary to monitor the spray state that affects the quality, such as the uniformity of the thickness of the nonwoven fabric produced from the nanofiber (fiber).

Japanese Patent Application Laid-Open No. 2002-201559 and Japanese Patent Application Laid-Open No. 8-153669 disclose devices using a plurality of nozzles, but monitoring of the spray state is not considered.
JP 2002-201559 A JP-A-8-153669

  In the conventional electrostatic spraying apparatus using a large number of nozzles, the nozzles arranged in the inner peripheral part are hidden by the shadow of the nozzles in the outer peripheral part, so that it is impossible to confirm from the side with respect to the spraying port. Even if a camera or the like is installed so as to face the spray port, products such as nanofibers (fibers) are laminated on the lens of the camera, making observation impossible in a short time. Therefore, even if spraying cannot be performed due to clogging, charge interference, or repulsion due to part of the nozzle, or if it stops midway, the spraying state cannot be confirmed during production, and the thickness of the finished nonwoven fabric is uneven. May cause a malfunction.

  An object of the present invention is to solve the conventional problems and to provide an electrostatic spraying device capable of constantly monitoring the state of electrostatic spraying with a plurality of nozzles.

In order to solve the above-mentioned problem, in the electrostatic spraying apparatus of the present invention, a polymer material solution obtained by liquefying a polymer material using a solvent is a plurality of two-dimensional lattices arranged in the X and Y directions. in electrostatic spraying device which performs electrostatic spraying on a resin sheet using a nozzle, a laser light source for irradiating a laser beam to Te Irakon during electrostatic spraying from the plurality of nozzles, the laser from the laser light source A camera for confirming the spray state by copying the minute charged particles of the Taylor cone diffusely reflected by the light beam , and the laser light source is arranged on one end side of the nozzles arranged in the X direction and in the X direction. It is characterized by irradiating with laser light .

Further, the electrostatic spray monitoring method of the present invention is a resin sheet using a plurality of nozzles arranged in a two-dimensional lattice in the X and Y directions , using a polymer material solution in which the polymer material is liquefied using a solvent. electrostatically sprayed above, in the electrostatic atomization monitoring method for monitoring the electrostatic spraying conditions, the Taylor cone which is electrostatically sprayed from the plurality of nozzles, arranged on one end side of the nozzle arranged in the X direction The sprayed state of the nozzle is monitored by irradiating a laser beam from the laser light source in the X direction and copying the fine charged particles of the Taylor cone diffusely reflected by the laser beam with a camera. is there.

  Especially in electrostatic spraying with multiple nozzles with conventional equipment, there is no way to monitor the spraying state that affects the quality of the nonwoven fabric, such as the uniformity of film thickness, and the quality of the nonwoven fabric can only be confirmed when it is completed. However, in the present invention, even if a plurality of nozzles are used, the spraying state can be monitored at all nozzles at all times. Therefore, even if a malfunction occurs, the apparatus is temporarily stopped to deal with recovery at any time. Therefore, it is possible to provide an electrostatic spraying apparatus capable of generating a nonwoven fabric having a stable quality while eliminating the wasteful nonwoven fabric as a product.

  Embodiments of the electrostatic spray device and the electrostatic spray monitoring method of the present invention will be described below in detail with reference to the drawings.

  First, the outline | summary of the production | generation of the nonwoven fabric which consists of a polymeric material is demonstrated using the electrostatic spraying apparatus in this invention using FIG. A substrate is required to collect and laminate the nonwoven fabric, and a roller 18 capable of controlling the feeding speed by feeding a resin sheet 8 made of insulating polyethylene such as polyethylene or the like from the roll 20 to serve as a non-woven fabric. Is taken up by a roll 21 for winding.

  The resin sheet 8 is fitted with a nanofiber spinning unit 22 between the roll 20 and the roll 21 and passes through the inside of a duct 13 having a collector 7 for collecting (stacking) nanofibers (fibers). This is a mechanism in which nanofibers (fibers) are collected (laminated) on the resin sheet 8. Each of the nanofiber spinning units 22 is independent, and a plurality of required nanofiber spinning units 22 are mounted on the duct 13 of the apparatus main body as shown in FIG.

  FIG. 1 shows a configuration in which a monitoring camera 25 and a laser light source 24 are mounted inside the nanofiber spinning unit 22 and mounted in the duct 13. In the present embodiment, a configuration in which a laser light source 24 is installed on the insulating resin plate 9 of the spray block 100 via a laser mounting portion 23 and a camera 25 for monitoring the spray state of the nozzle 1 is installed on the collector 4. Will be explained.

  In the nanofiber spinning unit 22 of FIG. 1, the nanofiber spinning unit 22 has a spray block 100 that constitutes a spraying section that is composed of a metal block 2 and a plurality of nozzles 1 that are integrally formed with the metal block 2 and arranged in a grid pattern. Yes.

  A high voltage is applied from the high voltage power source A to the conductive plate 2 of the metal block having a hollow inside. Inside the plurality of nozzles 1 formed in the spray block 100, a polymer material such as polyurethane, which is a material of nanofibers (fibers), is made into a solution with a solvent such as toluene and independent for each nanofiber spinning unit 22. It is supplied from the tank 15 through the pipe 14.

  The nozzle 1 is integrally formed in a conical shape by pressing or the like on a metal block of the conductive plate 2, and a high voltage is applied to the conductive plate 2 by a high voltage power source A, and the nozzle 1 is attached to the duct 13. In particular, the insulating resin plate 9 is insulated from the duct 13 at a portion indicated by 9a. The insulating resin plate 9 has a metal block conductive plate 2 attached thereto, and a laser light source 24 that generates a visible laser beam is installed via a laser attachment portion 23 in order to monitor a so-called Taylor cone portion during electrostatic spraying. .

  When a high voltage is applied to the conductive plate 2 from the high voltage power source A, an electrostatic charge is generated due to the application of a high voltage in the range of several kilovolts to several tens of kilovolts determined by the fiber diameter and material of the generated nanofibers. The generated charges are concentrated on the tip portion of the nozzle 1 due to the nature of being concentrated on the tip portion. Due to the concentration of the electric charge, an electrostatic attractive force (Coulomb) generated from the collector 4 disposed opposite to the nozzle and having a polarity different from or grounded with respect to the surface tension of the liquid at the tip of the nozzle. When the force is larger, the liquid becomes mist-like. That is, the polymer substance solution becomes minute charged particles 3 by a strong electric field, is separated from the nozzle tip, and is sprayed as charged droplets.

  Each of the liquid droplets in the state 3 in the mist has an electric charge, and since the electric charge is attracted to a different polarity, it is directed to the collector 4. On the way to the surface, the liquid droplets are charged with electric charges, so the liquid particles are repeatedly divided by electrostatic repulsion several times, and the size of the liquid droplets becomes finer. At the time of the miniaturization, the solvent for making the material into solution evaporates, leaving only the nanofiber (fiber) material, which is a nanofiber (fiber) with a fiber diameter of several nanometers to several tens of nanometers It will be called state.

  Even if the solution containing the polymer material is in the state of nanofibers (fibers), that is, even if the liquid is in a solid state, the charge initially given from the nozzle is not lost, but is charged. Remains.

  A transparent insulating sheet or a transparent plate-like insulating plate 5 using a dielectric material is disposed between the nozzle 1 and the collector 4, and the insulating sheet (plate) 5 is in the nature of the dielectric material. The surface is charged when a high voltage is applied to the metal block 2 because it has the property of showing electric polarization induced by an external electric field, that is, induced polarization. The surface 5a facing the spray port of the insulating sheet (plate) 5 has the same polarity as that of the metal block 2. Therefore, according to the Coulomb force that “the charge of the same potential repels”, the nanofiber (fiber) Since the material becomes repulsive to the charged insulating sheet (plate) 5, the material becomes floating in the space 10 between the nozzle spray port and the insulating sheet (plate) 5.

  The nanofibers (fibers) that have floated are applied to the metal net 6 by the high-voltage power source B and the same voltage applied to the nozzles by the high-voltage power source A to collect the nanofibers (fibers). ) Collector 7 is set to a different polarity or ground potential. By doing so, the nanofibers (fibers) do not go in the direction of the metal net 6 having the same polarity, but are always drawn in the direction of the collector 7 having a different polarity. This also means that “charges with the same potential repel and charges with different potentials attract each other. It is a movement that follows the Coulomb force.

  In FIG. 1, the air introduction port 6 is shown in a wire mesh structure, but the air introduction port 6 may be provided with an air introduction port that can introduce air whose air pressure is adjusted from the other end portion of the spray block 100 without using the wire mesh structure. Good. Dry air 11 is introduced from the air inlet 6 in the direction of the arrow to generate an air flow, and nanofibers (fibers) are laminated on the resin sheet 8. And it can be set as the structure which applies the high voltage power supply B to an air inlet, and produces | generates the air flow to the resin sheet 8 between the nozzle 1 and the transparent insulating board 5. FIG.

  Therefore, the attracted nanofibers (fibers) are collected (laminated) on the surface of the resin sheet 8 placed and sent along the collector (laminate) collector 7, and the polymer web of nanofiber fibers is collected. Can be formed. The speed of the dry air may be a low wind speed of about several centimeters / second so as not to stir the collection of the nanofibers (fibers) into the resin sheet 8. Avoid sending air at a strong wind speed of several tens of centimeters per second because the air pressure and excessive static electricity generation will stir the collection.

  As described above, charged nanofibers (fibers) are collected (laminated) on the resin sheet 8 placed along the collector 7, so that the nozzle 1 serving as a spraying port and the dielectric are collected. It does not stay between the insulating sheets (plates) 5 of the conductive material. Further, the nanofiber (fiber) does not adhere to the insulating sheet (plate) 5 as described above. Utilizing this, the insulating sheet (plate) made of a dielectric material is made transparent, and the camera 25 is installed facing the spraying port so that the spraying port can be projected between the collector 4 and the insulating sheet (plate) 5.

  One camera may be used, but if the number of nozzles is large and the resolution deteriorates when trying to capture all the nozzles, the number of cameras is increased and the nozzle group is divided and captured. Normally, it is appropriate to capture a spray nozzle of about 5 × 5 with one camera. One camera can be operated using an XY stage, etc., so that the whole camera can be covered without using multiple cameras, but the configuration is selected in consideration of the cost of operating the stage, etc. . However, depending on the number of cameras, multiple cameras are cheaper, and maintenance of operating parts is not necessary, so there is no need to stick to a single camera. Further, it is not necessary to select an expensive camera, and a monochrome CCD camera may be used.

  FIG. 2 is a view for explaining a state in which the laser light source 24 is attached to the insulating resin plate 9 of the spray block 100 via the laser attachment portion 23.

Although the fine charged particles 3 to be sprayed are mostly colorless and transparent, depending on the material, the sprayed state cannot be observed whether it is a camera or a visual observation as it is. If the nozzle body is made of transparent glass with one nozzle, the spray state can be estimated from the decrease in the solution of the material filled in the nozzle, but in the case of multiple nozzles and metallic I can't do that either. Therefore, small charged Taylor cone composed of particles 3 established the laser light source 24 as as possible visible 2 in the insulating resin 9 in the mount 23, fine charged particles lasers light ray 28 to be sprayed Irradiate. This is because the sprayed state is made visible by scattering the minute charged particles by applying the visible laser beam 28. As the laser beam 28, a red laser having a wavelength of 650 nm used for a laser pointer may be inexpensive. If it is difficult to see, a green laser having a high specific luminous efficiency with a wavelength of 532 nm that is also used for a pointer or the like may be used. In either case, it is only necessary to irradiate the microparticles and diffusely reflect them, so there is no need for high power. Usually choose class 2 or 3 class.

  FIG. 3 schematically shows a bottom view of the spray block 100 when a laser beam is applied to the Taylor cone portion during electrostatic spraying.

In that case, as shown in FIG. 3B, a configuration may be adopted in which one laser light source 24 is placed for the nozzle row and a nonflammable, heat-resistant absorber or diffuse reflector 27 is placed at the end thereof. but it may be configured so as to irradiate all of the spray opening at one lasers light source by installing a mirror or prism 26 for reflecting, as in FIG. 3 (a). Even in this configuration, a heat-resistant absorber or diffuse reflector 27 is also installed at the final end. 3A and 3B, the plurality of nozzles 1 are arranged in a two-dimensional grid in the X and Y directions, and the laser light sources 24 are arranged in the X direction (laser light irradiation direction). It arrange | positions at the one end part side of the nozzle 1 provided. Therefore, the nozzle light source 24 irradiates the laser beam in the X direction toward the Taylor cone of the minute charged particles sprayed from the nozzle 1 (see also FIGS. 1 and 2).

Here, the laser beam absorber for use in lasers termination, diffuser, usually, generally may be those used lasers termination as (end), it is said to be such as "shielding plate""shieldingshutter" It is what. The laser beam 28 exiting the Without this lasers termination from lasers light source 24 the possibility of fire caused by heat of eye disorders and lasers light rays by irregular reflection.

  The mirror or prism 26 and the laser terminal 27 are attached to the insulating resin plate 9 in the same manner as the laser light source 24.

The laser irradiation point irradiates between the spray port and a few millimeters from the spray port. If it is above the spray port, the spray state is unknown, and conversely, even if it is too far from the spray port, the sprayed mist-like solution spreads in a conical shape, so the number of charged fine particles in the unit volume from the spray port Therefore, the diffuse reflection that can be observed with the camera cannot be obtained. Height adjustment from the tip of the nozzle of the lasers light sources, and so keep the allow adjustment screws, are not fixed. Solution of the material, such as by voltage indicia pressure, because irregular reflection of the laser beam spray state is easily visible location different.

  In this way, the minute charged particles irregularly reflected by the laser beam 28 are copied by the camera 25, and the spray state can be confirmed. Since the minute charged particles 3 to be sprayed are colorless and transparent as described above, the state of the spray cannot be confirmed even with a camera or visually, so that the generation of fog can be recognized by irregular reflection with a laser beam or the like. When no is performed, only the nozzle is copied, but when spraying is performed, the state of fog is recognized. At that time, the nozzle mouth and nozzles become invisible or difficult to see due to diffusely reflected fog.

  When this non-woven fabric and filter made of nanofiber fibers of several nanometers to several tens of nanometers can be mass-produced using this electrostatic spraying, the conventional filter can cover the role of the conventional filter and can be removed with the conventional filter. Dust and fungi, such as carbon bacteria, that could not be screened can also be screened out. In addition to “removal”, screening with a few nanometers from the viewpoint of “selection” is not limited to removal of unnecessary substances, and nanoparticles can be taken out. For example, if only diamond abrasive grains of several tens of nanometers can be selected, the conventional polishing accuracy is improved by two orders of magnitude or more. In addition, “selection” at the nano level is promising for drug delivery.

  In addition, it can be used for regenerative medicine such as “artificial biological membranes” currently in the research stage, and is expected from this special field.

The figure which shows the nanofiber spinning unit part of the electrostatic spraying apparatus in Example 1 of this invention. The side view for demonstrating the spray block of the electrostatic spraying apparatus in Example 1 of this invention The figure which shows the monitoring method of the electrostatic spray monitoring method in Example 1 of this invention. The figure which shows typically the whole structure of an electrostatic spraying apparatus in Example 1 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Nozzle 2 Conductive plate 3 Minute charged particle 4 Collector which attracts charged particle from nozzle tip 5 Transparent insulating sheet or transparent insulating plate (dielectric material)
5a Nozzle side of transparent insulating sheet or transparent insulating plate (dielectric material) 6 Air inlet (metal mesh)
7 Collection Collector for Collecting (Laminating) Charged Nanofibers 8 Resin Sheet for Collecting (Lamination) Nanofibers (Fibers) 9 Insulating Resin 9a Insulating Portion between Conductive Plate 2 and Insulating Resin 9 Charge 11 Dry air 12 Sealing part 13 Duct 14 Material supply pipe 15 Material tank 18 Roller for resin sheet transfer direction 20 Feeding roller 21 Take-up roller 22 Nanofiber spinning unit 23 Laser attachment part 24 laser light source 25 camera 26 reflecting mirror 27 lasers termination 28 lasers light ray 100 spray block

Claims (2)

In an electrostatic spraying apparatus that performs electrostatic spraying on a resin sheet using a plurality of nozzles arranged in a two-dimensional grid in the X and Y directions , using a polymer material solution that has been liquefied using a solvent. ,
A laser light source for irradiating a laser beam to Te Irakon during electrostatic spraying from the plurality of nozzles,
A camera for confirming the spray state by copying the minutely charged particles of the Taylor cone diffusely reflected by the laser beam from the laser light source ;
The said laser light source is arrange | positioned at the one end part side of the said nozzle arranged in the X direction, and irradiates a laser beam to a X direction, The electrostatic spray apparatus characterized by the above-mentioned . Electrostatic spraying of a polymer material solution in which a polymer material is liquefied using a solvent on a resin sheet using a plurality of nozzles arranged in a two-dimensional grid in the X and Y directions. In the electrostatic spray monitoring method for monitoring
The Taylor cone to be electrostatically sprayed from the plurality of nozzles, a laser beam is irradiated in the X direction from a laser light source disposed at one end of the nozzle arranged in the X-direction, was irregularly reflected by the laser beam the An electrostatic spray monitoring method , wherein the spray state of the nozzle is monitored by copying fine charged particles of a Taylor cone with a camera .

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