JP2016175021A - Method for producing fine particle and production device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing fine particle capable of spraying a relatively large quantity of charged particles, further capable of promoting the further pulverization of the sprayed charged particles, and capable of efficiently producing a large quantity of fine particles with a reduced size produced by the splitting of the charged particles.SOLUTION: Provided is a method for producing fine particles where high pressure is directly applied to a conductive metal fine tube 21 through which a liquid as the raw material liquid of fine particles passes, and further, compressed air 41 for pulverization is jetted from the circumference of a liquid charge port 23 opening in one end side of the metal fine tube 21, thus the liquid is pulverized and atomized, and the flow F of the charged droplets produced by the atomization is sprayed with an ion carrying flow 45 including air ions charged at the polarity same as that of the charged droplets produced by the jet of corona discharge and compressed air with angle.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a fine particle production method and a production apparatus.

An electrospray method is known as a method for producing fine particles.
In the electrospray method, under a state where a high voltage is applied between a needle-shaped nozzle made of a conductor and a counter electrode facing the nozzle, a raw material liquid containing a fine particle forming material is led out from the nozzle, and the tip of the nozzle A hanging portion is formed in an inverted conical shape called a Taylor cone, and charged fine particle droplets are sprayed from the tip of the hanging portion. As the sprayed droplet moves toward the counter electrode, the solvent evaporates, and the charge density on the surface increases and the charge repulsion force overcomes the surface tension, thereby breaking up into smaller particles. This splitting is called Rayleigh splitting, and this splitting is repeated to make smaller particles.

  However, in this conventional electrospray method, since it is necessary to form a stable Taylor cone, the amount of spray cannot be increased, and the production efficiency of fine particles is low because it is limited to about several mL / hr.

Also, a method using a two-fluid nozzle is known as a method for atomizing and spraying a liquid. The two-fluid nozzle is for atomizing a liquid by using a flow of a high-speed gas such as compressed air, and is used for spraying the liquid in a spray dryer, for example. Atomization using a two-fluid nozzle can atomize a large amount of liquid compared to a conventional electrospray method that produces a Taylor cone.
Further, in Patent Document 1, as a fine particle manufacturing technology using a two-fluid nozzle, a raw material liquid and a high-pressure gas are supplied, and a spray mechanism unit that atomizes and blows off the raw material liquid, and a blowout port of the spray mechanism unit. And a fine particle production apparatus provided with a high voltage generating means for applying a high voltage between the collector and the collector provided at the outlet and the collector, and a fine particle production method using the apparatus. In the manufacturing method, a high voltage is applied between the spray mechanism and the collector, the droplets atomized and discharged are charged, and the droplets are split with the collector a plurality of times. Fine particles with submicron diameter are obtained.

  Further, in Patent Document 2, a high voltage is applied to a conductive metal thin tube that allows liquid to pass through, and compressed air for atomization is ejected from around a liquid discharge port that opens to one end of the metal thin tube. In addition to increasing the charge amount of the paint by injecting air flow including ions generated by corona discharge in parallel around the sprayed paint flow, the coating efficiency during painting is improved. Is described.

JP 2008-043944 A Japanese Patent Application Laid-Open No. 08-89853

In the fine particle manufacturing technique described in Patent Document 1, the amount of charge of the liquid atomized and blown out is small, and a large amount of fine droplets cannot be obtained by spraying a large amount of charged droplets.
Moreover, in the coating apparatus of patent document 2, the air flow containing the ion by corona discharge is injected in parallel with the flow of the injected paint, the charge amount of the injected paint is increased, and the paint It does not promote particle breakup.

  Therefore, the subject of this invention is providing the manufacturing method and manufacturing apparatus of microparticles | fine-particles which can solve the solution subject which the prior art mentioned above has.

  In the present invention, a high voltage is directly applied to a conductive metal thin tube through which a liquid, which is a raw material liquid for fine particles, and compressed air for atomization is ejected from the periphery of a liquid discharge port opened at one end of the metal thin tube. The liquid is atomized and sprayed, and the charged droplet generated by the spray is generated by corona discharge and compressed air jet and charged with the same polarity as the charged droplet. The present invention provides a method for producing fine particles, in which an ion carrier stream containing ions is sprayed at an angle.

  The present invention includes a liquid spray unit that sprays a liquid that is a raw material liquid of fine particles, a raw material liquid supply unit that supplies a liquid that is a raw material liquid to the liquid spray unit, and a compressed air that is supplied to the liquid spray unit The apparatus for producing fine particles, comprising: a compressed air supply means, a high voltage generation means, and a counter electrode disposed opposite to a liquid discharge port formed in the liquid spray section, wherein the liquid spray section includes: A liquid discharge nozzle having a conductive metal thin tube through which liquid passes, a liquid discharge port formed at one end of the liquid discharge nozzle, and a first injection port of compressed air for discharging compressed air from the periphery of the liquid discharge port And a second injection port for injecting compressed air and generating an ion carrier flow containing air ions generated by corona discharge, and the central axis of the second injection port through which the ion carrier flow is injected is Intersects the central axis of the liquid outlet In addition, a corona discharge needle electrode is provided at the second injection port, and the high voltage generating means can apply a high voltage to the conductive metal thin tube and is also applied to the corona discharge needle electrode. It is an object of the present invention to provide a fine particle manufacturing apparatus capable of applying a high voltage for generating corona discharge and capable of generating a potential difference between a conductive metal thin tube and a needle electrode and the counter electrode.

  According to the method and apparatus for producing fine particles of the present invention, a relatively large amount of charged particles can be sprayed, and further atomization of the sprayed charged particles can be promoted, and the charged particles are disrupted. Thus, a small amount of fine particles produced can be efficiently produced in large quantities.

FIG. 1 is a diagram showing a schematic configuration of an embodiment of the apparatus for producing fine particles of the present invention. FIG. 2 is a front view of the liquid spraying unit when the liquid spraying unit of the apparatus shown in FIG. 1 is viewed from the lower side in FIG. 1. FIG. 3 is a perspective view showing a main part of the liquid spraying part of the apparatus shown in FIG. FIG. 4 is a cross-sectional view showing the main part of the liquid spraying part of the apparatus shown in FIG. Fig.5 (a) and FIG.5 (b) are schematic diagrams which show the other example of arrangement | positioning of a 2nd injection nozzle. FIG. 6 is a schematic view of an apparatus used for the charging performance evaluation test. FIG. 7 is a graph showing the results of evaluation tests 1 and 2. FIG. 8 is a graph showing the particle size distribution of the fine particles obtained in Examples and Comparative Examples of the present invention.

The present invention Hereinafter, the drawings based on its preferred embodiment ^- reference will be described.
FIG. 1 shows a schematic configuration of an embodiment of the apparatus for producing fine particles of the present invention.
A fine particle production apparatus 1 shown in FIG. 1 includes a liquid spray unit 2 that sprays a liquid 3 that is a raw material of fine particles, and a raw material liquid supply unit that supplies a liquid that is a raw material liquid to the liquid spray unit 2 (not shown). ), A compressed air supply means (not shown) for supplying the compressed air 4 to the liquid spray part 2, a high voltage generating means 5, and a liquid discharge port 23 formed in the liquid spray part 2 The counter electrode 6 is provided.
The liquid spray unit 2 includes a liquid discharge nozzle 22 including a conductive metal thin tube 21 through which a liquid 3 that is a fine particle raw material passes, a liquid discharge port 23 formed at one end of the liquid discharge nozzle 22, A first injection port 24 for compressed air that ejects compressed air from the periphery of the liquid discharge port 23, and a second injection port 25 that injects compressed air and generates an ion carrier flow containing air ions generated by corona discharge. I have. The second injection port 25 is provided with a needle electrode 26 for corona discharge.
The high voltage generating means 5 can apply a high voltage to the conductive metal thin tube 21 and can also apply a high voltage to the corona discharge needle electrode 26 to generate a corona discharge. A potential difference may be generated between the metal thin tube and the needle electrode and the counter electrode.
The counter electrode 6 is grounded, or a voltage having a polarity opposite to that of the charged particles sprayed from the liquid discharge port 23 is applied.

  Further describing the present embodiment, the liquid discharge nozzle 22 in the present embodiment is composed of a conductive metal thin tube 21 itself. The metal thin tube 21 is a straight straight tube through which the liquid 3 can flow. The inner diameter of the metal thin tube 21 is, for example, not less than 0.1 mm and not more than 1.0 mm, preferably not less than 0.3 mm and not more than 0.5 mm. The outer diameter of the metal thin tube 21 is, for example, 0.2 mm or more and 2.0 mm or less, preferably 0.3 mm or more and 1.5 mm or less. By setting the inner diameter and outer diameter of the metal thin tube 21 within this range, the raw material liquid for particles can be easily and quantitatively fed, and the electric field concentrates in a narrow area around the nozzle, so that the raw material liquid It can be charged efficiently.

The metal thin tube 21 and the liquid discharge nozzle 22 are supported by the case body 20 of the liquid spray unit 2 such that a common central axis extends in one direction X, and an opening opening at one end of the liquid discharge nozzle 22 However, the liquid discharge port 23 is formed. When the liquid spray unit 2 is viewed from the front, the liquid discharge port 23 has a circular shape, and a compressed air first injection port 24 that ejects compressed air is formed around the liquid discharge port 23.
As shown in FIG. 2, the first injection port 24 is formed in an annular shape surrounding the liquid discharge port 23.
The front view of the liquid spray unit 2 refers to a state in which the liquid discharge port 23 of the liquid discharge nozzle 22 is viewed from the front. In the apparatus 1 of the present embodiment, the liquid spray unit 2 is viewed from the lower side in FIG. It is in a state of viewing.

The first injection port 24 is formed at one end of the first flow path 24A communicating with the internal space 42 to which compressed air is supplied by the compressed air supply means, and the compressed air 4 is introduced into the internal space 42 by the compressed air supply means. Is supplied, the compressed air that has passed through the first flow path 24 </ b> A is ejected from the first injection port 24 as the atomized compressed air 41. Further, the raw material liquid supply means can quantitatively supply the liquid 3 which is a fine particle raw material liquid to the liquid discharge nozzle 22. The liquid discharge nozzle 22 and the first injection port 24 function as a two-fluid nozzle by supplying the liquid 3 that is the raw material liquid to the liquid discharge nozzle 22 while ejecting the atomized compressed air from the first injection port 24. Then, the liquid 3 as the raw material liquid is atomized and sprayed from the liquid discharge port 23.
FIG. 1 shows an example in which the extending direction X of the central axis of the liquid discharge nozzle 22 coincides with the vertical direction, and the first flow path 24A extends along the axial direction of the liquid discharge nozzle 22. In the invention, the direction in which the compressed air 4 or the atomized liquid 3 is ejected is not particularly limited, and may be a horizontal direction, an obliquely upward direction, an obliquely downward direction, etc. instead of the downward direction in the vertical direction. The first flow path 24A may be parallel to the central axis of the liquid discharge nozzle 22 or may be non-parallel.

  Further, the counter electrode 6 disposed opposite to the liquid discharge port 23 is provided at a position separated from the liquid discharge port 23 of the liquid discharge nozzle 22. Specifically, the counter electrode 6 is disposed facing the opening of the liquid discharge port 23 at a position in front of the opening of the liquid discharge port 23 of the liquid discharge nozzle 22. The counter electrode 6 is made of metal or the like and has conductivity. The distance (shortest distance) between the tip of the liquid discharge nozzle 22 and the counter electrode 6 is preferably 200 mm or more, more preferably 300 mm or more, and preferably 1500 mm or less, more preferably 1000 mm or less. It is preferable that the shortest distance is not less than the above lower limit value from the viewpoint of sufficiently drying spray droplets and collecting them as particles.

  As shown in FIG. 1, the high voltage generating means 5 is configured to be able to apply a high voltage between the conductive metal thin tube 21 of the liquid discharge nozzle 22 and the counter electrode 6. In the example shown in FIG. 1, a negative voltage is applied to the metal thin tube 21 of the liquid discharge nozzle 22, the metal thin tube 21 is negative, the counter electrode 6 is grounded, and the metal thin tube 21 and the counter electrode 6 are interposed between them. Produces an electric field. In order to generate an electric field between the metal thin tube 21 and the counter electrode 6, instead of applying the voltage shown in FIG. 1, a positive voltage is applied to the metal thin tube 21 of the liquid discharge nozzle 22, The counter electrode 6 may be grounded. Further, the counter electrode 6 is not necessarily grounded, and a voltage having a polarity opposite to that of the metal thin tube 21 may be applied. The voltage generated by the high voltage generating means 5 is preferably a DC voltage.

  For the high voltage generating means 5, a known device such as a high voltage power supply device can be used. The potential difference applied between the metal thin tube 21 and the counter electrode 6 is preferably 1 kV or more, particularly 5 kV or more. The potential difference applied between the metal thin tube 21 and the counter electrode 6 is preferably 1 kV to 60 kV, and more preferably 5 kV to 50 kV.

The liquid spray unit 2 includes a second injection port 25 that injects compressed air and generates an ion carrier flow 45 that includes air ions generated by corona discharge.
As air ions (negative ions) generated by corona discharge, for example, O ₂ ⁻ (H ₂ O) _n , O ₃ ⁻ (H ₂ O) _n , NO ₂ ⁻ (H ₂ O) _n , NO ₃ ⁻ ( H ₂ O) _n , CO ₃ ⁻ (H ₂ O) _n , NO ₃ ⁻ , NO ₃ ⁻ (HNO ₃ ) _n , NO ₃ ⁻ NO _{3 and the} like.
As shown in FIG. 2, the second ejection port 25 in the manufacturing apparatus of the present embodiment is farther from the center of the liquid ejection port 23 than the first ejection port 24, and is The distance L3 to the second ejection port 25 is longer than the distance L1 from the center of the liquid ejection port 23 to the first ejection port 24. As shown in FIG. 2, a pair of second ejection ports 25 are formed at positions on both sides of the liquid ejection port 23. Further, as shown in FIG. 3, the second ejection port 25 is formed on an inclined surface 27 that is formed around the liquid ejection port 23 with a space between the second ejection port 23 and the liquid ejection port 23. The inclined surface 27 has an inclined lower end on the side closer to the liquid discharge port 23 and an inclined upper end on the side closer to the liquid discharge port 23. The inclined surface 27 is preferably planar, but may be convex or concave.
Instead of providing a pair of the second ejection ports 25 so as to sandwich the liquid ejection port 23, three or more second ejection ports 25 can be equally provided around the liquid ejection port 23. FIG. 5A shows an example in which four are equally provided, and FIG. 5B is an example in which three are provided equally. In each of the example shown in FIG. 5A and the example shown in FIG. 5B, the plurality of second ejection ports 25 are equally spaced on the circumference of a perfect circle having the center at the center of the liquid discharge port 23. Is arranged.

As shown in FIGS. 1 and 4, the second injection port 25 is connected to the above-described internal space 42 via the inclined channel 25 </ b> B having an angle with respect to the central axis of the distal channel 25 </ b> A and the liquid discharge nozzle 22. Communicate. When the compressed air 4 is supplied to the internal space 42 by the compressed air supply means, a part of the compressed air 4 is ejected from the first injection port 24 as the atomized compressed air 41 through the first flow path 24A as described above. On the other hand, the other part is injected from the second injection port 25 through the distal flow path 25A and the inclined flow path 25B. The first flow path 24A, the distal flow path 25A, and the inclined flow path 25B each preferably have a cylindrical inner surface.
The distal flow path 25A and the inclined flow path 25B communicate with each other to form a continuous flow path for supplying air to the second injection port 25. The distal flow path 25A is compared to the inclined flow path 25B. And far from the second injection port 25. The distal flow path 25A shown in FIG. 4 is formed in parallel to the central axis of the liquid discharge nozzle 22, but may be non-parallel, and the distal flow having an angle with respect to the inclined flow path 25B. The path 25A itself may not exist.

The second injection port 25 is provided with a needle electrode 26 for causing corona discharge. The high voltage generating means 5 of the present embodiment is configured to be able to apply a high voltage for causing corona discharge to the needle electrode 26 as well. As shown in FIG. 1, in the present embodiment, a voltage having the same polarity is applied to the metal thin tube 21 and the needle electrode 26 of the liquid discharge nozzle 22 via a branched metal conductor 51. Yes.
The needle electrode 26 is preferably arranged so that the tip of the needle electrode 26 protrudes from the second injection port 25. The needle electrode 26 may be fixed to the inner surface of the distal channel 25A or the inclined channel 25B, and is supported so as not to contact either the inner surface of the distal channel 25A or the inner surface of the inclined channel 25B. May be. As the needle electrode 26, a discharge metal wire or the like can be preferably used. As the material for the discharge metal wire used as the needle electrode, a material that is difficult to corrode with a conductive metal material such as tungsten, brass, copper, or molybdenum is preferable. In addition, the needle electrode 26 is preferably strong enough to withstand the injection of compressed air and has an appropriate thickness that does not hinder the injection. For example, the diameter of the needle electrode 26 is 60% or less of the diameter of the second injection port. Is preferably 40% or less, more preferably 20% or more of the diameter of the second injection port, and more preferably 30% or more. For example, when the diameter of the second injection port is 0.5 mm, 0.2 to 0.3 mm is preferable. The needle electrode 26 is used with its tip sharpened like a needle to facilitate discharge. When a metal wire or the like having a sharp tip is used as the needle electrode 26, the diameter of the needle electrode 26 is the diameter at the outlet cross section of the second injection port 25. Further, the needle electrode 26 may be a rod-like body with a sharp tip, but it is preferable that the tip is sharp.

In addition, the protrusion length L5 (see FIG. 4) of the needle electrode 26 from the second injection port 25 is preferably 0.5 mm or more, more preferably 1 mm or more, from the viewpoint of easy occurrence of corona discharge. From the viewpoint of reducing the degree of obstructing the air flow and preventing the adhesion of the liquid, it is preferably 3 mm or less, more preferably 2 mm or less. The protruding length L5 of the needle electrode 26 is preferably 0.5 mm or more and 3 mm or less, more preferably 1 mm or more and 2 mm or less.
In addition, when the member in which the distal flow path 25A and the inclined flow path 25B are formed is a conductor, the needle electrode 26 is fused to the member, and the metal lead 51 from the high voltage generating means 5 and the like are attached to the member. May be connected.

  The example shown in FIG. 1 is a case where the same negative voltage as that of the metal thin tube 21 of the liquid discharge nozzle 22 is applied to the needle electrode 26, but instead of the method of applying the voltage shown in FIG. A positive voltage may be applied to the metal thin tube 21 of the discharge nozzle 22 and the counter electrode 6 may be grounded. The voltage generated by the high voltage generating means 5 is preferably a DC voltage.

The potential difference applied between the needle electrode 26 and the counter electrode 6 is preferably 15 kV or more, particularly 20 kV or more from the viewpoint of generating a large amount of air ions by corona discharge. On the other hand, it is preferable that this potential difference is 60 kV or less, particularly 50 kV or less because it is not necessary to make the insulation of the device excessive. The potential difference applied between the needle electrode 26 and the counter electrode 6 is preferably 15 kV to 60 kV, more preferably 20 kV to 50 kV.
The high voltage generating means 5 may have a device for applying a voltage to the needle electrode 26 in addition to a device for applying a voltage to the metal thin tube of the liquid discharge nozzle 22, and has a function of generating different voltages. Different voltages may be applied independently to the metal thin tube of the liquid discharge nozzle 22 and the needle electrode 26 using the power supply device provided.

  The manufacturing apparatus 1 of the present embodiment includes a particulate collection unit 7 on the surface of the counter electrode 6. The fine particle collection unit 7 may be the surface of the counter electrode 6 made of a conductive material, but the surface of the counter electrode 6 may be covered with a thin film or the like and used as the collection unit 7.

Next, an embodiment of a method for producing fine particles using the fine particle production apparatus described above, that is, a method for producing fine particles of the present invention will be described.
In a preferred embodiment of the method for producing fine particles according to the present invention, the compressed air is supplied to the liquid spray unit 2 of the production apparatus 1 by the compressed air supply means, and the known raw material liquid supply means such as a metering liquid pump is used. A liquid 3 that is a raw material liquid for fine particles is supplied to the liquid spraying section 2 by means of (not shown). By supplying the compressed air, atomized compressed air 41 is ejected from the first injection port 24 located around the liquid discharge port 23 that opens to one end of the metal thin tube 21, and ion transport is performed from the second injection port 25. Compressed air is generated to generate a flow.

  In this state, when the high voltage generating means 5 is operated and a negative DC high voltage is applied to the conductive metal thin tube 21 and the needle electrode 26 through which the liquid as the raw material liquid for fine particles passes, The flowing liquid 3 is charged with a negative charge, and the charged liquid 3 is atomized and sprayed from the liquid discharge port 23 by the atomization compressed air 41 ejected from the periphery of the liquid discharge port 23. The liquid 3 becomes droplets by spraying and becomes charged droplets 31 charged.

The charged droplets 31 generated by the spray ride on the airflow generated by the injection of the compressed air from the first injection port 24 and flow toward the counter electrode 6 along the electric field generated in the metal thin tube 21 and the counter electrode 6. . Further, by applying a high negative voltage to the needle electrode 26, air ions are generated by corona discharge from the needle electrode 26, and air currents including air ions are generated by jetting compressed air from the second injection port 25. An ion carrier stream 45 is generated. Air ions contained in the ion transport flow 45 are negatively charged with the same polarity as the charged droplets 31.
Further, the second ejection port 25 is formed on an inclined surface 27 having an inclined lower end on the side close to the liquid discharge port 23, and the ion transport flow 45 containing air ions, as shown in FIG. The droplet flow F is sprayed at an angle.

By blowing the ion transport flow 45 containing air ions charged to the same polarity as the charged droplet 31 to the flow F of charged droplets generated by spraying, the charge amount of the charged droplet 31 in the flow F increases. The reason why the amount of charge increases is that charged droplets and air ions are usually of the same polarity, and if they are parallel flows, they will not repel and coalesce. Since air ions are collided, the air ions are taken into the charged droplets, and as a result, the charge amount is considered to increase.
As the charge amount of the charged droplets 31 increases in this way, the solvent evaporates during the flight of the charged droplets 31 and the surface charge density increases and the charges repel each other, and this charge repulsive force is the surface tension of the liquid. The phenomenon in which the droplets are overcome and break up into fine particles, that is, Rayleigh splitting, is promoted. The fine particles 32 that have been reduced in size by repeating a plurality of divisions are collected in the collection unit 7. The collection may be performed with the counter electrode 6 grounded, and the counter electrode has a voltage of the opposite polarity to that of the fine particles, that is, if the fine particles are negatively charged, the negative particles are positively charged. In some cases, a positive voltage may be applied.

From the viewpoint of more effectively increasing the amount of charge due to the blowing of the ion carrier flow 45, the central axis 25c of the second jet port 25, which is a jet port for jetting compressed air for generating the ion carrier flow, and liquid It is preferable to design so that the central axis 23c of the discharge port 23 intersects at an intersecting angle θ (see FIG. 4) of 40 to 80 degrees within a distance L from the liquid discharge port 23 of 2 to 6 mm.
By setting the distance L within the range of 2 to 6 mm, the ion transport flow 45 can be sprayed on the flow F of the charged droplets in a state where the charged droplets do not diffuse so much and the concentration of air ions is high, By increasing the charging efficiency and setting the crossing angle θ within the range of 40 to 80 degrees, the ion carrier flow 45 can be strongly collided with the flow F of the spray droplets, the charging efficiency is increased, and the angle is increased. It is also possible to prevent the droplets from being scattered widely.
Note that the intersection of the central axis 25c of the second ejection port 25 and the central axis 23c of the liquid discharge port 23 may intersect at the point P even if the central axes are in a twisted position. The central axis 25c of the second injection port 25 preferably passes through a spherical shell with a radius of 0.5 mm centered on the point P on the central axis 23c of the liquid discharge port 23, and the spherical shell with a radius of 0.35 mm More preferably, the central axis 25c of the second injection port 25 passes through the inside. If the central axis 25c of the second ejection port 25 passes through the inside of the spherical shell having the radius centered on the point P on the central axis 23c of the liquid discharge port 23, it is assumed that the point P intersects. .

From the same point of view, the central axis 25c of the second ejection port 25 and the central axis 23c of the liquid discharge port 23 intersect at an angle θ of 45 to 60 degrees within a range of a distance L from the liquid discharge port 23 of 3 to 5 mm. It is more preferable to cross at
The central axis 23 c of the liquid discharge port 23 is the central axis of the flow path of the fluid 3 adjacent to the liquid discharge port 23, and protrudes from the liquid discharge port 23 in addition to the portion located in the flow path of the liquid 30. An extension in the axial direction is also included. In the present embodiment, the central axis 23c of the liquid discharge port 23 coincides with the central axis of the liquid discharge nozzle 22 and an extension portion thereof in the axial length direction.
The central axis 25c of the second injection port 25 is a flow channel adjacent to the second injection port 25, that is, the central axis of the inclined flow channel 25B described above, and in addition to the portion located in the flow channel 25B, the second injection An extension in the axial length direction protruding from the mouth 25 is also included. In the example shown in FIGS. 5A and 5B as well, the distance from the liquid ejection port 23 is 2 with respect to the central axis of all the second ejection ports 25 with respect to the central axis of the liquid ejection port 23. It is preferable to intersect at an intersection angle θ (see FIG. 4) of 40 to 80 degrees within a range of ˜6 mm, and the distance intersects at an intersection angle θ of 45 to 60 degrees within a range of 3 to 5 mm. More preferably.

  In the production apparatus and production method of the present invention, the spray amount can be made relatively large. For example, the supply amount of the liquid 3 to the liquid discharge nozzle can be 0.5 mL / min or more, and can be 10 times or more that of the electrospray method. The supply amount of the liquid 3 to the liquid discharge nozzle is preferably 160 mL / min or less.

The raw material liquid for the fine particles can be appropriately determined according to the type of fine particles to be produced. It is preferable that it has electroconductivity.
In the case of producing fine particles containing an organic compound as fine particles, the fine particle constituent materials include aramid, collagen, cellulose, nylon, poly-m-phenylene terephthalate, poly-p-phenylene isophthalate, polyacrylonitrile, polyacrylonitrile Methacrylate copolymer, polyarylate, polyurethane, polyester carbonate, polyethylene, polyethylene oxide, polyethylene terephthalate, polyethylene naphthalate, polycarbonate, polycaprolactone, polyglycolic acid, polystyrene, polyhydroxybutyric acid, polyvinyl alcohol, polybutylene terephthalate, polyvinylidene fluoride , Polyvinylidene fluoride-hexafluoropropylene copolymer, polypropylene, polypeptide, polysalt Vinylidene - acrylate copolymer, polyvinyl chloride, polyvinyl acetate, polylactic acid and the like. The organic compound to be used is not limited to one type, and an arbitrary plurality of types can be used in combination from the organic compounds exemplified above.

  Further, when producing inorganic fine particles as fine particles, it is preferable to include inorganic fine particles as the fine particle constituent material, and the content of the inorganic fine particles in the raw material liquid is preferably 10 to 20% by mass. Examples of the inorganic fine particles include silica, titanium oxide, alumina, iron oxide, zinc oxide, zirconia, magnesium oxide, tin oxide, indium oxide, yttrium oxide, cerium oxide, copper oxide, manganese oxide, cobalt oxide, and calcium oxide. Metal oxides or composite oxides such as indium tin oxide, metals such as gold, silver, copper and platinum, nitrides such as aluminum nitride, silicon nitride and boron nitride, silicon carbide, barium silicon titanate, carbon nanotubes, etc. Can be mentioned. The inorganic fine particles to be used are not limited to one type, and any plurality of types of inorganic fine particles exemplified above can be used in combination.

  In addition, fine particles containing an inorganic compound and an organic compound can be produced as fine particles. In this case, the raw material liquid includes one or more of the above-described fine particle constituent materials for producing fine particles containing an organic compound, And those containing one or more of the above-described fine particle constituent materials for producing fine particles of an inorganic compound.

  Solvents include ethyl benzoate, propyl benzoate, methyl benzoate, ethyl chloride, methyl chloride, methylene chloride, carbon tetrachloride, ethyl bromide, propyl bromide, methyl bromide, acetic acid, ethyl acetate, propyl acetate, acetic acid Methyl, water, 1,1-dichloroethane, 1,2-dichloroethane, 1,3-dioxolane, 1,4-dioxane, 1-propanol, 2-propanol, N, N-dimethylformamide, m-xylene, o-xylene , P-xylene, o-chlorotoluene, p-chlorotoluene, acetonitrile, acetone, ethanol, formic acid, ethyl formate, propyl formate, methyl formate, chloroform, diisobutyl ketone, diisopropyl ketone, cyclohexanone, cyclohexane, cyclopentane, dichloropropane, Dibromoethane, Dibro Propane, dibenzyl alcohol, tetraethylene glycol, tetrahydrofuran, triethylene glycol, trichloroethane, toluene, pyridine, phenol, diethyl phthalate, dipropyl phthalate, dimethyl phthalate, hexafluoroacetone, hexafluoroisopropanol, hexane, benzene, methanol, Examples thereof include methyl-n-propyl ketone, methyl-n-hexyl ketone, methyl isobutyl ketone, and methyl ethyl ketone. The solvent to be used is not limited to one type, and a plurality of arbitrary types may be selected from the exemplified solvents and mixed.

  In addition, the raw material liquid can contain a polymer compound. Examples of water-soluble polymers include polyvinyl alcohol, polyethylene oxide, polyethylene glycol, polyacrylic acid, sodium polyacrylate, polymethacrylic acid, polysodium methacrylate, polyvinylpyrrolidone, chitosan, pullulan, hyaluronic acid, chondroitin sulfate, poly-γ- Glutamic acid, modified corn starch, β-glucan, gluco-oligosaccharide, heparin, keratosulfuric acid and other mucopolysaccharides, cellulose, pectin, xylan, lignin, glucomannan, galacturonic acid, psyllium seed gum, tamarind seed gum, gum arabic, tragacanth gum, soybean water Polysaccharides, alginic acid, carrageenan, laminaran, agar (agarose), gelatin, fucoidan, methylcellulose, hydroxypropylcellulose, hydroxyethyl Examples thereof include cellulose, hydroxypropylmethylcellulose, partially saponified polyvinyl alcohol, low saponified polyvinyl alcohol, and carboxymethylcellulose. Examples of water-insoluble polymers include polypropylene, polyethylene, polystyrene, polybutyl alcohol, polyurethane, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, poly-m-phenylene terephthalate, poly-p-phenylene isophthalate, polyvinylidene fluoride, polyfluoride. Vinylidene chloride-hexafluoropropylene copolymer, polyvinyl chloride, polyvinylidene chloride-acrylate copolymer, polyacrylonitrile, polyacrylonitrile-methacrylate copolymer, polycarbonate, polyarylate, polyester carbonate, nylon, aramid, polycaprolactone, poly Examples thereof include lactic acid, polyglycolic acid, collagen, polyhydroxybutyric acid, polyvinyl acetate, and polypeptide. The polymer compound to be used is not limited to one type, and any plurality of types can be used in combination from the exemplified polymer compounds.

  The liquid that is the raw material liquid for the fine particles needs to have conductivity because it is charged by a metal thin tube to which a high voltage is applied. The term “conductivity” as used herein means that the conductivity is 1 μS / m or more, for example.

The fine particles preferably produced by the method and apparatus of the present invention are fine particles having a number average particle diameter of 0.01 μm or more and 10 μm or less determined by the following method, and more preferably 0.01 μm or more and 5 μm. It is as follows. However, the particles produced in the present invention are not limited to those having such a number average particle diameter.
[Measurement method of average particle diameter]
Using a scanning electron microscope (JEOL Ltd., JSM-6510), particles are observed at an acceleration voltage of 20 kV and a magnification of 5000 times. The diameters of all the particles in a plurality of visual fields including 50 to 200 particles were measured on the image, and the average was calculated as the number average particle diameter.

As mentioned above, although this invention was demonstrated based on the preferable embodiment, this invention is not restrict | limited to embodiment mentioned above, It can change suitably.
For example, the compressed air injected from the first injection port 24 and the compressed air injected from the second injection port 25 may be supplied through independent paths without passing through the common internal space 42. .

In relation to the above-described embodiment, the present invention further discloses the following additional notes (fine particle production apparatus, fine particle production method).
<1>
By directly applying a high voltage to a conductive metal thin tube through which a liquid that is a raw material liquid for fine particles passes, and by spraying compressed air for atomization from the periphery of a liquid discharge port that opens on one end side of the metal thin tube, Atomizing and spraying the liquid,
An ion carrier stream containing air ions charged in the same polarity as the charged droplets, generated by corona discharge and jetting of compressed air, is sprayed at an angle to the flow of charged droplets generated by spraying. A method for producing fine particles.

<2>
The inner diameter of the metal thin tube is preferably 0.1 mm or more, more preferably 0.3 mm or more, preferably 1 mm or less, more preferably 0.5 mm or less, and preferably 0.1 mm or more and 1 mm or less. The method for producing fine particles according to <1>, more preferably 0.3 mm or more and 0.5 mm or less.
<3>
The outer diameter of the metal thin tube is preferably 0.2 mm or more, more preferably 0.3 mm or more, preferably 2 mm or less, more preferably 1.5 mm or less, and preferably 0.2 mm or more and 2 mm or less. More preferably, the method for producing fine particles according to <1> or <2>, wherein the particle size is 0.3 mm or more and 1.5 mm or less.
<4>
The method for producing fine particles according to any one of <1> to <3>, wherein the compressed air for atomization is ejected from a first ejection port formed in an annular shape around the liquid ejection port.
<5>
The method for producing fine particles according to any one of <1> to <4>, wherein the liquid discharge port is circular in a front view.

<6>
A counter electrode that generates a potential difference with the metal thin tube is disposed at a position spaced apart from the liquid discharge port, and the fine particles are manufactured.
The shortest distance between the liquid discharge port and the counter electrode is preferably 200 mm or more, more preferably 300 mm or more, and preferably 1500 mm or less, more preferably 1000 mm or less, <1> to <3> The method for producing fine particles according to any one of the above.
<7>
A negative voltage or a positive voltage is applied to the metal thin tube, and a reverse polarity voltage is applied to the counter electrode disposed at a position away from the liquid discharge port, or the counter electrode is grounded, <1 The manufacturing method of microparticles | fine-particles any one of>-<6>.
<8>
The potential difference applied between the metal thin tube and the counter electrode is preferably 1 kV or more, more preferably 5 kV or more, preferably 60 kV or less, more preferably 50 kV or less, and preferably 1 kV or more and 60 kV or less. The method for producing fine particles according to any one of <1> to <6>, preferably 5 kV or more and 50 kV or less.
<9>
The atomized compressed air is ejected from a first ejection port formed in an annular shape around the liquid ejection port, and the compressed air for generating the ion carrier flow is ejected from the second ejection port,
The second ejection port is farther from the center of the liquid ejection port than the first ejection port, and the distance L3 from the first ejection port to the second ejection port is the first distance from the center of the liquid ejection port. It is longer than the distance L1 to one injection port. The method for producing fine particles according to any one of <1> to <8>.
<10>
Any one of <1> to <9>, wherein a pair of second injection ports for injecting compressed air for generating the ion carrier flow is formed at least at positions on both sides of the liquid discharge port. The manufacturing method of microparticles | fine-particles of description.

<11>
The second ejection port that ejects compressed air for generating the ion carrier flow is formed on an inclined surface that is formed around the liquid ejection port and spaced from the liquid ejection port. The method for producing fine particles according to any one of <1> to <10>.
<12>
The central axis of the second injection port that injects compressed air for generating the ion carrier flow and the central axis of the liquid discharge port are within a range of 2 to 6 mm from the liquid discharge port. The method for producing fine particles according to any one of <1> to <11>, wherein the fine particles intersect at an intersection angle of 80 degrees.
<13>
The method for producing fine particles according to any one of <1> to <12>, wherein the air ions are generated from a needle electrode for corona discharge arranged so as to protrude from a jet port of compressed air.
<14>
The protruding length of the needle electrode from the compressed air injection port is preferably 0.5 mm or more, more preferably 1 mm or more, preferably 3 mm or less, more preferably 2 mm or less, and preferably 0.5 mm. The method for producing fine particles according to <13>, which is 3 mm or less and more preferably 1 mm or more and 2 mm or less.
<15>
Compressed air for generating the ion carrier flow is ejected through an inclined flow channel that is inclined with respect to the central axis of the liquid discharge nozzle having the liquid discharge port at the end. The method for producing fine particles according to any one of <1> to <14>.

<16>
The air ions are generated from a corona discharge needle electrode, and the needle electrode is fixed to an inner surface of a flow path for sending compressed air to a second injection port for injecting compressed air for generating the ion carrier flow. The method for producing fine particles according to any one of <1> to <15>, wherein the fine particles are supported so as not to contact the inner surface of the flow path.
<17>
The air ions are generated from a needle electrode for corona discharge, and the needle electrode is a distal flow channel, or an inclined flow channel inclined with respect to a central axis of a liquid discharge nozzle having the liquid discharge port at its end. The distance from the liquid discharge port is fixed to the inner surface of the distal flow path that is farther from the inclined flow path, or does not contact either the inner surface of the distal duct or the inner face of the inclined duct The method for producing fine particles according to any one of <1> to <16>, which is supported.
<18>
The diameter of the needle electrode is preferably 60% or less, more preferably 40% or less, and preferably 0.1% or more of the diameter of the second injection port, any one of <1> to <17> 2. The method for producing fine particles according to claim 1.
<19>
The method for producing fine particles according to any one of <1> to <18>, wherein the raw material liquid for the fine particles is a conductive liquid containing 10 to 20% by mass of inorganic fine particles.
<20>
The potential difference applied between the needle electrode and the counter electrode is preferably 15 kV or more, more preferably 20 kV or more, preferably 60 kV or less, more preferably 50 kV or less, and preferably 15 kV or more and 60 kV or less. More preferably, it is 20 kV or more and 50 kV or less, The manufacturing method of the microparticles | fine-particles as described in said <1>-<19>.

<21>
Liquid spray unit for spraying liquid as raw material liquid of fine particles, raw material liquid supply means for supplying liquid as raw material liquid to liquid spray unit, and compressed air supply for supplying compressed air to liquid spray unit An apparatus for producing fine particles, comprising: a means; a high-voltage generating means; and a counter electrode disposed opposite to a liquid discharge port formed in the liquid spraying portion,
The liquid spraying unit ejects compressed air from a liquid discharge nozzle having a conductive metal thin tube through which the liquid passes, a liquid discharge port formed at one end of the liquid discharge nozzle, and the periphery of the liquid discharge port A first injection port for compressed air; and a second injection port for injecting compressed air to generate an ion carrier flow containing air ions generated by corona discharge. The central axis of the ejection port intersects with the central axis of the liquid ejection port, and the second ejection port is provided with a needle electrode for corona discharge,
The high voltage generating means can apply a high voltage to the conductive metal thin tube and can also apply a high voltage to the corona discharge needle electrode to cause a corona discharge. An apparatus for producing fine particles, which can generate a potential difference between a needle electrode and the counter electrode.
<22>
The potential difference applied between the needle electrode and the counter electrode is preferably 15 kV or more, more preferably 20 kV or more, preferably 60 kV or less, more preferably 50 kV or less, and preferably 15 kV or more and 60 kV or less. The apparatus for producing fine particles according to <20>, more preferably 20 kV or more and 50 kV or less.
<23>
<21> The central axis of the second ejection port and the central axis of the liquid discharge port intersect at an intersecting angle of 40 to 80 degrees within a range of 2 to 6 mm from the liquid discharge port. The fine particle production apparatus according to ~ <22>.
<24>
<23> The central axis of the second ejection port and the central axis of the liquid ejection port intersect at an intersecting angle of 45 to 60 degrees within a range of 3 to 5 mm from the liquid ejection port. The fine particle production apparatus according to 1.
<25>
The fine particle production apparatus according to any one of <21> to <24>, wherein the supply amount of the liquid to the liquid discharge nozzle is 0.5 mL / min or more and 200 mL / min or less.

<26>
The method for producing fine particles according to any one of <1> to <20> or the apparatus for producing fine particles according to any one of <21> to <25>, wherein the fine particles containing an organic compound are produced.
<27>
Examples of the fine particle constituting material that constitutes the fine particles include aramid, collagen, cellulose, nylon, poly-m-phenylene terephthalate, poly-p-phenylene isophthalate, polyacrylonitrile, polyacrylonitrile-methacrylate copolymer, polyarylate, polyurethane, Polyester carbonate, polyethylene, polyethylene oxide, polyethylene terephthalate, polyethylene naphthalate, polycarbonate, polycaprolactone, polyglycolic acid, polystyrene, polyhydroxybutyric acid, polyvinyl alcohol, polybutylene terephthalate, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer Coalesced polypropylene, polypeptide, polyvinylidene chloride-acrylate copolymer, The method for producing fine particles according to any one of <1> to <20>, wherein a raw material liquid containing one or more organic compounds selected from vinyl chloride, polyvinyl acetate, and polylactic acid is used. Or the manufacturing apparatus of microparticles | fine-particles any one of said <21>-<26>.
<28>
The method for producing fine particles according to any one of <1> to <20> above, wherein a raw material liquid containing 10 to 20% by mass of inorganic fine particles in the raw material liquid is used as the fine particle constituent material to be a constituent material of the fine particles. The fine particle production apparatus according to any one of <21> to <27>.
<29>
Examples of the inorganic fine particles include silica, titanium oxide, alumina, iron oxide, zinc oxide, zirconia, magnesium oxide, tin oxide, indium oxide, yttrium oxide, cerium oxide, copper oxide, manganese oxide, cobalt oxide, and calcium oxide. Or a composite oxide such as indium tin oxide, a metal such as gold, silver, copper, or platinum, a nitride such as aluminum nitride, silicon nitride, or boron nitride, silicon carbide, barium silicon titanate, or carbon nanotube 1 The method for producing fine particles according to any one of <1> to <20> or the method according to any one of <21> to <28>, wherein a raw material liquid containing seeds or two or more kinds of inorganic fine particles is used. Fine particle production equipment.
<30>
Solvents include ethyl benzoate, propyl benzoate, methyl benzoate, ethyl chloride, methyl chloride, methylene chloride, carbon tetrachloride, ethyl bromide, propyl bromide, methyl bromide, acetic acid, ethyl acetate, propyl acetate, methyl acetate Water, 1,1-dichloroethane, 1,2-dichloroethane, 1,3-dioxolane, 1,4-dioxane, 1-propanol, 2-propanol, N, N-dimethylformamide, m-xylene, o-xylene, p-xylene, o-chlorotoluene, p-chlorotoluene, acetonitrile, acetone, ethanol, formic acid, ethyl formate, propyl formate, methyl formate, chloroform, diisobutyl ketone, diisopropyl ketone, cyclohexanone, cyclohexane, cyclopentane, dichloropropane, dibromo Ethane, dibromo Lopan, dibenzyl alcohol, tetraethylene glycol, tetrahydrofuran, triethylene glycol, trichloroethane, toluene, pyridine, phenol, diethyl phthalate, dipropyl phthalate, dimethyl phthalate, hexafluoroacetone, hexafluoroisopropanol, hexane, benzene, methanol, Any one of the above items <1> to <20>, wherein a raw material liquid containing one or more selected from methyl-n-propyl ketone, methyl-n-hexyl ketone, methyl isobutyl ketone, and methyl ethyl ketone is used. The manufacturing method of microparticles | fine-particles of description, or the manufacturing apparatus of microparticles | fine-particles any one of said <21>-<29>.

<31>
The method for producing fine particles according to any one of <1> to <20>, wherein the raw material liquid is a raw material liquid containing one or both of a water-soluble polymer compound and a water-insoluble polymer compound. Or the manufacturing apparatus of microparticles | fine-particles any one of said <21>-<30>.
<32>
The water-soluble polymer compound is polyvinyl alcohol, polyethylene oxide, polyethylene glycol, polyacrylic acid, sodium polyacrylate, polymethacrylic acid, polysodium methacrylate, polyvinylpyrrolidone, chitosan, pullulan, hyaluronic acid, chondroitin sulfate, poly -Γ-glutamic acid, modified corn starch, β-glucan, gluco-oligosaccharide, heparin, mucopolysaccharide such as keratosulfate, cellulose, pectin, xylan, lignin, glucomannan, galacturonic acid, psyllium seed gum, tamarind seed gum, gum arabic, tragacanth gum , Soybean water-soluble polysaccharide, alginic acid, carrageenan, laminaran, agar (agarose), gelatin, fucoidan, methylcellulose, hydroxypropylcellulose, hydroxy The method or apparatus for producing fine particles according to <31>, wherein the fine particles are one or more selected from siethylcellulose, hydroxypropylmethylcellulose, partially saponified polyvinyl alcohol, low saponified polyvinyl alcohol, and carboxymethylcellulose.
<33>
The water-insoluble polymer compound is polypropylene, polyethylene, polystyrene, polybutyl alcohol, polyurethane, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, poly-m-phenylene terephthalate, poly-p-phenylene isophthalate, polyfluorinated. Vinylidene, polyvinylidene fluoride-hexafluoropropylene copolymer, polyvinyl chloride, polyvinylidene chloride-acrylate copolymer, polyacrylonitrile, polyacrylonitrile-methacrylate copolymer, polycarbonate, polyarylate, polyester carbonate, nylon, aramid, poly Selected from caprolactone, polylactic acid, polyglycolic acid, collagen, polyhydroxybutyric acid, polyvinyl acetate, polypeptide That is one or more, the <31> or microparticles manufacturing process or manufacturing apparatus according to <32>.
<34>
The method for producing fine particles according to any one of <1> to <20> or the fine particles according to any one of <21> to <33>, wherein the liquid that is a raw material liquid for fine particles has conductivity. manufacturing device.

  Hereinafter, the present invention will be described in more detail with reference to examples. However, the scope of the present invention is not limited to such examples. Unless otherwise specified, “%” and “part” mean “% by mass” and “part by mass”, respectively.

(Evaluation Test 1)
Using the apparatus shown in FIG. 1, the charging performance for the liquid was evaluated by injecting water instead of the liquid which is the raw material liquid for fine particles and measuring the charge amount of the injected water.
For the evaluation test, an evaluation apparatus 8 shown in FIG. 6 was used. The evaluation device 8 includes a Faraday cage 81, a metal container 82, a charge amount measuring device 83, and a fixed amount feeding pump 84.
The Faraday cage 81 uses a Faraday cage (KQ-1400) manufactured by Kasuga Electric, the charge amount measuring device 83 uses a coulomb meter (NK-1002) manufactured by Kasuga Electric, and a syringe pump is used as the quantitative liquid feeding pump 84. Using. As water, tap water (8 mS / m) having conductivity was used. In FIG. 6, reference numeral 88 denotes charged water, and reference numerals 85 to 87 denote metal lead wires connected to the tip of the measurement probe, the measurement probe, and the ground.

Specifically, after measuring the mass of the metal container 82 of the Faraday cage, the metal container 82 was set in the Faraday cage, and the charge amount measuring device 83 was reset to zero. A high voltage of a negative voltage or a positive voltage is applied between the metal thin tube 21 of the liquid spraying part 2 and between the needle electrode 26 and the compressed air 4 is supplied to the liquid spraying part 2 to supply the first and second injection ports. It was sprayed from. Next, the fixed liquid feed pump 84 was operated to spray water from the liquid discharge port 23 at the lower end of the liquid discharge nozzle 22. After spraying an appropriate amount of water, the mass of the liquid 88 accumulated in the metal container 82 was measured, and the charge amount (C / g) per unit mass was calculated from the mass of the liquid and the measured value of the charge amount measuring device 83.
The conditions used for the evaluation test 1 are as follows.
The outer diameter of the metal thin tube 21: 1 mm
Inner diameter of metal thin tube 21: 0.35 mm
Distance L: 4mm
Crossing angle θ: 50 degrees Material of needle electrode 26: Discharge metal wire φ0.2 (Oki Electric Cable OS-Z)
Needle electrode 26 protrusion length L5: 1.5 mm
Liquid: Tap water (8mS / m)
Liquid flow rate: 0.5 mL / min
Pressure of compressed air 4: 0.01 MPa
Distance from the liquid discharge port 23 to the upper end of the metal container 82: 200 mm

(Evaluation test 2)
The amount of charge when the needle electrode 26 was not discharged was calculated in the same manner as in the evaluation test 1 except that the needle electrode 26 was removed and no corona discharge was generated.

The results of evaluation tests 1 and 2 are shown in FIG.
As can be seen from the results shown in FIG. 7, the charge amount clearly increased when discharging from the needle electrode 26 at 20 kV or higher when charged to either positive polarity or negative polarity. It was also confirmed that the negative charge has a larger charge amount. When the applied voltage is −30 kV, the C1 portion in the graph is the amount of charge increased by corona discharge from the needle electrode 26, and the C2 portion in the graph is corona discharge from a metal portion other than the needle electrode 26. It is estimated that the C3 portion in the graph is the charge amount directly charged to the liquid in the metal thin tube 21.

Example 1
Using the fine particle production apparatus shown in FIG. 1, the fine particle raw material liquid having the following formulation was sprayed to produce fine particles.
Formulation of raw material liquid Polymer compound Human oxyfluorocellulose
(HPC-SSL, 2.0-2.9mPa · s, Wako Pure Chemical Industries): 3%
Inorganic fine particles Silica particle dispersion
(Average particle size 20nm, solid content 40%, Nissan Chemical ST-40): 17%
Solvent Ultrapure water (specific resistance 18 MΩ · cm or more): 70%
EtOH (for adjusting the drying speed): 10%
Conductivity: 51mS / m
The conditions used in the examples are as follows.
The outer diameter of the metal thin tube 21: 1 mm
Inner diameter of metal thin tube 21: 0.35 mm
Distance L: 4mm
Crossing angle θ: 50 degrees Material of needle electrode 26: discharge metal wire φ0.2 (Oki Electric Cable OS-Z)
Needle electrode 26 protrusion length L5: 1.5 mm
Liquid flow rate: 0.5 mL / min
Pressure of compressed air 4: 0.4 MPa
Distance from liquid discharge port to counter electrode (collecting part): 850 mm
Applied voltage: -30 kV

(Comparative Example 1)
Fine particles were produced in the same manner as in Example 1 except that the needle electrode 26 was removed and no corona discharge was generated.

(Evaluation)
The particle size was measured from the electron microscope (SEM) photographs of the fine particles obtained in Example 1 and Comparative Example 1. The number of measured fine particles was 300 to 400.
The results are shown in FIG. 8 for the particle size distribution of Example 1 and Comparative Example 1, and various average particle sizes are shown in Table 1.
Here, the number average particle diameter and the volume average particle diameter are calculated by the following equations.
Number average particle diameter = Σ (di · ni) / Σni * di is the diameter of the particle, ni is the number of measurements Volume average particle diameter = Σ (Vi · di) / Σ (Vi) * Vi is the volume of the particle The particle diameter is calculated from the ratio of the total volume of particles and the total surface area according to the following formula.
Sauter average particle size = Σdi3 · ni / Σdi2 · ni

From the results shown in FIG. 8 and Table 1, it can be seen that the formation of fine particles was promoted by corona discharge from the needle electrode 26 as in the present invention.
From the results shown in FIG. 8, by performing corona discharge from the needle electrode 26 and spraying the ion carrier flow at an angle, particles having a large particle size of 3 μm or more are reduced compared to the comparative example in which corona discharge is not performed. And it turns out that the particle | grains of the small particle size of 1 micrometer or less are increasing. Also, from the calculation results of the average particle diameter shown in Table 1, it can be seen that fine particle formation was promoted by performing corona discharge from the needle electrode 26. That is, by performing corona discharge from the needle electrode 26, the charge amount of the spray droplets is increased, thereby promoting Rayleigh splitting and making it possible to efficiently produce fine particles.

DESCRIPTION OF SYMBOLS 1 Manufacturing apparatus 2 Liquid spray part 21 Conductive metal thin tube 22 Liquid discharge nozzle 23 Liquid discharge port 23c Center axis of liquid discharge port 24 1st injection port 25 2nd injection port 25c Center axis of 2nd injection port 26 Needle electrode 27 Inclined surface 3 Liquid (fine particle raw material liquid)
31 Charged droplets 4 Compressed air 41 Compressed air for atomization 45 Ion carrier flow 5 High voltage generating means 6 Counter electrode 7 Collection unit

Claims (6)

By directly applying a high voltage to a conductive metal thin tube through which a liquid that is a raw material liquid for fine particles passes, and by spraying compressed air for atomization from the periphery of a liquid discharge port that opens on one end side of the metal thin tube, Atomizing and spraying the liquid,
An ion carrier stream containing air ions charged in the same polarity as the charged droplets, generated by corona discharge and jetting of compressed air, is sprayed at an angle to the flow of charged droplets generated by spraying. A method for producing fine particles.   The central axis of the second injection port that injects compressed air for generating the ion carrier flow and the central axis of the liquid discharge port are within a range of 2 to 6 mm from the liquid discharge port. The method for producing fine particles according to claim 1, which intersects at an intersection angle of 80 degrees.   3. The method for producing fine particles according to claim 1, wherein the air ions are generated from a corona discharge needle electrode arranged so as to protrude from a jet port of compressed air.   The method for producing fine particles according to any one of claims 1 to 3, wherein the raw material liquid for the fine particles is a conductive liquid containing 10 to 20% by mass of inorganic fine particles. Liquid spray unit for spraying liquid as raw material liquid of fine particles, raw material liquid supply means for supplying liquid as raw material liquid to liquid spray unit, and compressed air supply for supplying compressed air to liquid spray unit An apparatus for producing fine particles, comprising: a means; a high-voltage generating means; and a counter electrode disposed opposite to a liquid discharge port formed in the liquid spraying portion,
The liquid spraying unit ejects compressed air from a liquid discharge nozzle having a conductive metal thin tube through which the liquid passes, a liquid discharge port formed at one end of the liquid discharge nozzle, and the periphery of the liquid discharge port A first injection port for compressed air; and a second injection port for injecting compressed air to generate an ion carrier flow containing air ions generated by corona discharge. The central axis of the ejection port intersects with the central axis of the liquid ejection port, and the second ejection port is provided with a needle electrode for corona discharge,
The high voltage generating means can apply a high voltage to the conductive metal thin tube and can also apply a high voltage to the corona discharge needle electrode to cause a corona discharge. An apparatus for producing fine particles, which can generate a potential difference between a needle electrode and the counter electrode.   The center axis of the second ejection port of compressed air and the center axis of the liquid discharge port intersect each other at an intersecting angle of 40 to 80 degrees within a range of 2 to 6 mm from the liquid discharge port. The fine particle production apparatus according to 1.

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