JP2018058047A - Wet type atomization method for raw material and wet type atomization device therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wet type atomization method and a wet type atomization device capable of surface modification and atomization more efficient than the conventional one and capable of performing surface modification and atomization suitable for dispersion per material.SOLUTION: Provided is a wet type pulverization method having a constitution in which a high pressure jet treatment apparatus 152 performing high pressure jet from a high pressure nozzle 41 provided at the inside of a chamber 40 and an in-liquid plasma generation apparatus 160 are combined, and the electrodes 31, 32 of the in-liquid plasma generation apparatus 160 are oppositely arranged in the chamber 40, where, by applying pulse voltage to the electrodes 31, 32 and/or by jetting a raw material solution 10 from the high pressure nozzle 41 of the high pressure jet treatment apparatus 152 to increase the temperature of the raw material solution 10, then applying pulse voltage to the electrodes 31, 32 to generate in-liquid plasma, and, by applying cavitation by the high pressure jet to a plasma generation region, the in-liquid plasma treatment of the raw material solution 10 is performed.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a raw material wet atomization method and a wet atomization apparatus.

Fine particles, especially nanoparticles, have a very large specific surface area due to their nanometer (nm) order size and exhibit specific physical properties due to the quantum size effect, and are being studied and used in various fields. ing. In recent years, nanoparticles have been widely used in various material fields such as electronic parts, pigments, cosmetics, pharmaceuticals, foods, and agricultural chemicals. On the other hand, since nanoparticles easily aggregate, in order to effectively utilize the properties of the nanoparticles, an appropriate dispersion treatment that matches the properties of the nanoparticles is required.
On the other hand, the safety of chemical substances is debated. In particular, in the case of cosmetics, pharmaceuticals, and foods, the fine particles directly touch the human body or are directly administered to the human body. Therefore, when the fine particles are atomized, the impurities adhere to the fine particles, and if impurities are mixed, safety is guaranteed. It becomes a big problem. Further, in electronic materials, mixing of impurities into fine particles has a considerable adverse effect on electrical characteristics and magnetic characteristics.

As a method for atomizing particles, generally known are a dispersion by ultrasonic vibration, a wet mechanical contact grinding using a grinding medium such as a bead mill, and a method by simultaneous friction grinding (mechanical contact grinding). Yes. However, in mechanical contact type pulverization using a bead mill or the like, the energy density for pulverization becomes too high due to point contact between the pulverizing medium and the particles, and the particle structure itself is easily broken. As a result of excessive temperature rise (heat generation) at the point contact point, the desired functionality of the particles deteriorates. Furthermore, there is a problem that contaminants (also called contaminants) generated from a grinding medium such as a bead mill are mixed.
On the other hand, the wet jet mill using water jet technology was developed as a atomization method that does not break the particles themselves by mixing the raw material solution from the high pressure nozzle and does not contaminate the particles. It is considered promising as a wet atomization method and is being put to practical use. However, only by atomization by a high-pressure wet injection type atomizer, that is, dispersion by a physical action such as injection or collision, there is a limit to disperse electrical aggregation, and it is difficult to obtain nano-sized particles. In order to disperse the electrical aggregate as described above, the surface charge of the aggregate is adjusted by adding an inorganic acid / inorganic base or organic acid / organic base to the raw material liquid, and dispersed by a high-pressure wet-jet atomizer There is a way to do it. By using this method, nano-sized particles can be obtained. However, since the above-described addition of the acid / base is necessary, there may be a problem that the purity of the entire raw material is lowered.
Recently, methods for dispersing fine particles in water by various plasma treatments have been studied. Agglomeration atomization performed by a conventional high-pressure wet-jet atomization apparatus is performed by atomizing a raw material liquid containing aggregates at a predetermined pressure from a chamber nozzle. The surface of the aggregate is modified by generating plasma in the raw material liquid containing the fine particle aggregate, thereby creating an environment in which the aggregate is easily dispersed. The applicant of the present application provides, as Patent Document 1, a atomization apparatus in which these high-pressure wet-jet atomization apparatus and in-liquid plasma generation apparatus are combined in one apparatus.

  Patent Document 1 states that “a high-pressure injection processing device 152 that injects high-pressure from a high-pressure nozzle 41 provided in a chamber 40 and a plasma generator are combined, and the electrodes 31 and 32 of the plasma generator are arranged oppositely in the chamber 40. The wet atomization apparatus 100 (FIG. 1) which is the structure which carried out the plasma processing in the liquid liquid immediately in the said chamber 40 by carrying out the high pressure injection of the raw material solution 10 containing the aggregate of fine particles from the high pressure nozzle 41 by the predetermined pressure. Is described.

  Japanese Patent Application Laid-Open No. H10-228561 includes a submerged plasma electrode that generates plasma in a liquid, and includes a conductive wire 12 and an insulating member 14 that covers an outer periphery of the conductive wire 12, and the insulating member 14 includes the insulating member 14. 14 is formed so that the front end surface 14a of the conductive wire 12 protrudes further to the front end side than the front end surface 12a of the conductive wire 12, and between the inner peripheral surface 14b of the insulating member 14 and the outer peripheral surface 12b of the conductive wire 12. Describes a submerged plasma electrode 10 </ b> A (FIG. 2) provided with a gap d in which the conductive wire 12 can slide, and “a front end surface 12 a of the conductive wire 12 of the submerged plasma electrode 10 </ b> A”. And the front end surface 12a of the conductive wire 12 of the counter electrode 10B are arranged with a predetermined distance L3, which is defined as an interelectrode distance L3, which is, for example, 0.5 mm to 3 mm. Is preferable. " There is a predicate (see the 0026 paragraph).

Non-Patent Document 1 discloses that “a lot of H radicals are generated at an interelectrode distance of 0.5 mm (FIG. 1A), and OH radicals are generated at an interelectrode distance of 1.5 cm (FIG. 1B). It is known to produce a lot. " There is also a report regarding plasma in liquid that “H radicals are preferentially generated when the distance between the electrodes is less than 2 mm, and OH radicals are preferentially generated when the distance between the electrodes is 2 mm or more” (Non-patent Document 2). .
Non-Patent Document 3 describes a radical generated by in-liquid plasma: “H radicals have a strong reducing action and OH radicals have a strong oxidizing action on the material surface” (20 Page). Cellulose is a polysaccharide consisting only of glucose, and forms a polymer chain by strong hydrogen bonds between and within the molecule. Non-patent document 3 states that “cellulose has a glucose structure by treatment with a single plasma in liquid. The molecular weight is reduced while holding the “.” (See page 16).
Non-patent document 4 relates to a hydrophilic carbon nanotubes (CNT) surface, "so far submerged pulse streamer discharge and the gas-liquid O generated from O ₂ plasma at the interface ₂ ^- by radicals or OH radicals, the CNT surface hydrophilic There is a report example that has been converted to "" (see page 939).

JP, 2006-107196, A JP 2014-167880 A

Dai Harada, et al., “Chemical Modification and Dispersibility Improvement of Carbon Nanotube Surfaces by Solution Plasma”, Japan Society of Resources and Materials, Spring 2014 Conference Lecture Manuscript http://www.mmij.or.jp/convention/doc_file .inc.cpx? est = 798c275d1177eef59dd5ce216f153ea4 Osamu Takai, et al., “Creative Research Promotion Project CREST Research Area“ Creation of Innovative Manufacturing Technology Based on Nanoscience ”Research Project“ Autonomous Control of Solution Plasma Reaction Field and Application to Nanosynthesis / Processing ”” FY2007 Results Report, page 2 Osamu Takai, et al., “Creative Research Promotion Project CREST Research Area“ Creation of Innovative Manufacturing Technology Based on Nanoscience ”Research Project“ Autonomous Control of Solution Plasma Reaction Field and Application to Nanosynthesis / Processing ”” Research Completion Report pages 16, 20 Junko Hamada, et al., “Preparation of nanocarbon-dispersed composite materials using solution plasma surface modification”, Journal of the Japan Institute of Metals, Vol. 73, No. 12 (2009), pages 938-942

  However, even with the methods described in Patent Documents 1 and 2, there are still many problems to be solved for stably obtaining nanoparticles. That is, in a compound atomization apparatus equipped with a high-pressure wet injection type atomizer and an in-liquid plasma generator, the material is dispersed by high-pressure wet injection, and the surface modification of the material is performed by in-liquid plasma. Although atomization is performed, its surface modification action and refinement effect are limited. In addition, since the optimum surface state for dispersion varies depending on the type of material, the surface modification method must be changed accordingly. Various factors are considered as the cause, but the inventor of the present application has obtained experimental results in which the generation efficiency of in-liquid plasma cannot be increased, particularly in the case of low pressure injection (50 MPa or less). Then, the present inventors have found that depending on the temperature of the raw material solution, there is a factor that affects the surface modification effect and can be expected to improve the miniaturization effect.

  Therefore, an object of the present invention is to provide a wet atomization method and a wet atomization apparatus capable of performing surface modification and atomization more efficiently than conventional methods and capable of performing surface modification and atomization suitable for dispersion for each material. Is to provide.

The inventor of the present application uses a wet atomization apparatus in which a high-pressure injection processing apparatus that performs high-pressure injection and a submerged plasma generator are used as they are, but it can increase the generation efficiency of submerged plasma as compared with the conventional apparatus. The experimental results were obtained and the present invention was completed. In addition, the inventors of the present application have obtained knowledge that surface modification suitable for dispersion and improvement of atomization can be obtained for each material by controlling the distance between the electrodes and the temperature of the raw material solution, and have completed the present invention. It was.
The wet atomization method of the present invention is a combination of a high-pressure injection processing apparatus that injects high pressure from a high-pressure nozzle provided in a chamber and a submerged plasma generator, and the electrodes of the submerged plasma generator are opposed to each other in the chamber. A pulse voltage is applied to some of the electrodes to raise the temperature of the raw material solution, and then a pulse voltage is applied to some of the electrodes to generate plasma, and / or Alternatively, the raw material solution is injected from the high-pressure nozzle of the high-pressure injection processing apparatus, the temperature of the raw material solution is increased, and then a pulse voltage is applied to some of the electrodes to generate plasma in liquid, in the plasma generation area. Cavitation by the high pressure injection can be extended.
According to the present invention, when a pulse voltage is applied to the electrode to raise the temperature of the raw material solution, the plasma generation efficiency is improved. In other words, the cavitation bubbles generated by high-pressure injection have many bubbles, but they are not always in the vicinity between the electrodes, and it is assumed that there are few bubbles in the vicinity of the electrode pair in the downstream area of injection. Moreover, since there are few cavitation bubbles in low pressure injection, plasma generation due to bubbles cannot be expected so much. Even in such a situation where there are few bubbles, a temperature rise (such as a temperature rise due to the frictional force of the nozzle tube) occurs when the raw material solution is injected, and the plasma generation efficiency is improved.
Further, raising the temperature of the raw material solution can also be performed by injecting the raw material solution from the high-pressure nozzle of the high-pressure injection processing apparatus. Efficiency is improved.
Therefore, although the wet atomization apparatus is used as it is, the generation efficiency of the in-liquid plasma can be improved as compared with the conventional apparatus. In particular, even in the case of low-pressure injection (50 MPa or less), the generation efficiency of plasma in liquid can be increased.

In the wet atomization method of the present invention, the distance between the electrodes is set between 1 mm and 10 mm to generate plasma, and the temperature of the raw material solution is set to 40 ° C. or higher. Injecting the raw material solution from the high-pressure nozzle of the above to raise the temperature of the raw material solution, and then applying a pulse voltage to some of the electrodes to generate plasma, so that the temperature of the raw material solution is 40 degrees or more Features.
In the wet atomization method of the present invention, the pH of the raw material solution is controlled by controlling the generation amount of the O radical and OH radical, and the atomization is promoted. There is an effect to. In the cellulose solution, the particle size, viscosity, pH and the like of the raw material can be changed. In addition, with titanium oxide, silica, and carbon nanotubes, the particle size, zeta potential, and pH of the raw material can be changed. In addition, for example, even between particles with strong cohesive force and particles with poor wettability, nano-sized particles are obtained by stepwise atomization by repeating the operation of high-pressure injection and plasma treatment in liquid several times. It becomes easy.

In the present invention, the raw material solution is cellulose, and the distance between the electrodes is set to 2 mm or more and 10 mm or less to generate OH radicals. It is characterized by that.
According to the present invention, since the OH radical is effective for a material that forms a polymer by hydrogen bonding, such as cellulose (cellulose nanofiber), the distance between electrodes of the plasma in liquid is desirably 2 mm or more.

In the present invention, the raw material solution is titanium oxide, the distance between the electrodes is 1 mm or more and 2 mm or less to generate H radicals, and the pH of the raw material solution is shifted from the isoelectric point of titanium oxide to the acidic side. The particle surface of the titanium oxide is changed to a positively charged state, and electrostatic repulsive force is generated between the particles to make the particles fine.
Further, according to the present invention, the raw material solution is silica, the distance between the electrodes is 2 mm or more and 10 mm or less to generate OH radicals, and the pH of the raw material solution is shifted from the isoelectric point of silica to the basic side. Then, the surface of the silica particles is changed to a negatively charged state, and electrostatic repulsive force is generated between the particles to atomize the particles.
According to the present invention, the metal oxides such as titanium oxide and silica have different radicals effective for atomization at each isoelectric point specific to the material. In titanium oxide having an isoelectric point of pH 6, H radicals are effective for atomization, and therefore the distance between electrodes of plasma in liquid is desirably 2 mm or less. In silica having an isoelectric point in the vicinity of pH 2 to 3, OH radicals are effective for atomization. Therefore, the inter-electrode distance of the plasma in liquid is desirably 2 mm or more.

According to the present invention, the raw material solution is a carbon nanotube, and the distance between the electrodes is set to 1 mm or more and 2 mm or less to generate H radicals, thereby generating a radical substitution reaction between the H radicals and the carbon nanotubes. It is characterized by making it.
According to the present invention, in a material such as CNT that does not have polarity on the surface of the material and is poorly compatible with water, hydrophilization with H radicals is effective for atomization, so the distance between electrodes of plasma in liquid is 2 mm or less. Is desirable.

The wet atomization apparatus of the present invention comprises a high-pressure nozzle for high-pressure injection of a raw material solution containing agglomerates of fine particles, and a plasma generator provided with an electrode, and the high-pressure nozzle is disposed in the chamber. The wet atomization apparatus is provided, wherein the electrodes are arranged opposite to each other in the chamber, and the cavitation caused by the high-pressure jet extends to a plasma generation area between the electrodes, and controls a distance between the electrodes. It is characterized by comprising an interval adjusting means capable of
According to the present invention, the temperature condition of the raw material solution that affects the plasma generation efficiency can be controlled by controlling the distance between the electrodes in the plasma generation unit, and the generated radical species can be controlled for each material. By performing surface modification suitable for dispersion, atomization can be performed more efficiently than before.

As for this invention, the said electrode is used also as an electrode for the temperature rise of a raw material solution, It is characterized by the above-mentioned. According to the present invention, the electrode includes a plurality of electrode pairs. In addition, the present invention is characterized by comprising temperature control means for increasing the temperature of the raw material solution.
According to the present invention, when the pulse voltage is applied to some of the plurality of electrodes or the temperature of the raw material solution is increased by the temperature control means, the plasma generation efficiency is improved, and the plasma in liquid is reduced with less Joule heat. Can be generated.

  According to the present invention, by controlling the temperature of the solution in which the electrode is immersed, it is possible to perform atomization more efficiently than in the past. In addition, according to the present invention, the radical species generated by controlling the distance between the electrodes in the plasma generation unit is controlled, and surface modification suitable for dispersion for each material is performed, so that efficient atomization that differs for each material is achieved. It can be performed. Accordingly, plasma can be generated with less Joule heat, and the surface modification effect is further increased by increasing the plasma generation rate, so that an improvement in the miniaturization effect can be expected. In addition, a wet atomization apparatus in which a high-pressure jet processing apparatus and an in-liquid plasma generation apparatus are combined is used as it is, but the generation efficiency of in-liquid plasma can be improved as compared with the conventional apparatus.

It is a block diagram which illustrates schematic structure of the wet atomization apparatus of embodiment of this invention. It is a structural diagram which illustrates the high pressure nozzle and chamber which concern on the said embodiment. It is a principal part enlarged view of the chamber which concerns on the said embodiment. It is a principal part enlarged view explaining the space | interval adjustment means and the distance adjustment method between electrodes which concern on the said embodiment. It is a principal part enlarged view which illustrates the in-liquid plasma generation location produced when the in-liquid plasma generator which concerns on the said embodiment is metal. It is a structural diagram which illustrates the high pressure nozzle and chamber which concern on the said embodiment. It is a structural diagram which illustrates the high pressure nozzle and chamber which concern on the said embodiment. It is a structural diagram which illustrates the high pressure nozzle and chamber which concern on the said embodiment. It is a manufacturing process flowchart which illustrates the manufacturing procedure of embodiment of this invention. It is a block diagram which illustrates the wet atomization apparatus concerning Example 1 of the present invention. It is a structural diagram which illustrates the high pressure nozzle and chamber which concern on the said Example. It is a structural diagram which illustrates the high pressure nozzle and chamber which concern on the said Example. It is a block diagram which illustrates the plasma generator and chamber concerning Example 2 of the present invention. It is a block diagram which illustrates the wet atomization apparatus which concerns on the said Example.

  The form for implementing this invention is demonstrated below.

About Raw Material In the present invention, the raw material is an aggregate of fine particles. Examples of the raw material include metal fine particles, metal oxide fine particles, nanofibers, and other known fine particles. Examples of the metal oxide raw material include titanium oxide, barium titanate, ferrite, alumina, silica, and other known aggregates of metal oxide fine particles. Examples of the nanofiber include cellulose, chitin, chitosan, and other known biomass nanofibers which are biomass raw materials. Other known fine particles include, for example, carbon nanotube (CNT).
The raw materials targeted by the present invention include pharmaceutical raw materials. Examples of the raw material for pharmaceuticals include aggregates of phenytoin, magnesium hydroxide, caffeine, calcium carbonate, bidoxypropylcellulose, magnesium stearate, and acetaminophen.
When the raw material is subjected to high-pressure injection processing with the high-pressure injection processing apparatus according to the present invention, for example, the biomass raw material becomes thin by untangling the fibers while maintaining the length of the fibers. And it is possible to reduce the fiber cutting or the molecular weight by changing the processing conditions such as the injection pressure and the number of processing of the high-pressure injection processing apparatus. In the present invention, the nanofiber means a fiber having a nano width. When the fibers are unwound and become one minimum unit fiber by carrying out the method of the present invention, the diameter of cellulose becomes about 10 to 51 nm.
In the present invention, the raw material solution is a liquid containing fine particle aggregates. The solvent of the raw material solution is water, IPA or a known aqueous solution.

FIG. 1 is a block diagram showing a schematic configuration of a wet atomization apparatus 100 according to an embodiment of the present invention. FIG. 2 is an enlarged view of a main part of the wet atomization apparatus 100 and is a schematic diagram showing a schematic configuration of the chamber 40 in which the in-liquid plasma treatment of the raw material solution 10 is performed. In the present embodiment, the chamber 40, a high-pressure injection processing device 152 that performs high-pressure injection from the high-pressure nozzle 41 provided in the chamber, and a plasma generator 160 are combined (FIG. 1). Further, the electrodes 31 and 32 of the plasma generator are arranged opposite to each other (FIG. 2). The electrodes 31 and 32 are arranged so as to face each other so that cavitation caused by high-pressure injection reaches the plasma generation area between the electrodes (FIG. 2). In the present embodiment, the raw material solution 10 containing fine particle aggregates is jetted at a high pressure from a high pressure nozzle 41 at a predetermined pressure, and a pulse voltage is applied between the electrodes S1 and 32 to change the temperature of the raw material solution 10. The plasma treatment of the raw material solution 10 in the chamber 40 is performed in the chamber 40 by raising the cavitation by the high-pressure jetting to the plasma generation area of the electrode S1 disposed between the electrodes (FIG. 2). The temperature of the raw material solution 10 is preferably set to 40 degrees or more and 90 degrees or less. By making the raw material solution 10 40 degreeC or more, vaporization of the raw material solution 10 required for generation | occurrence | production of plasma can be produced at the minimum, and plasma can be generated between electrodes. In the present invention, plasma is generated in the liquid. However, when the raw material solution 10 is set to 90 ° C. or higher, the suspension is excessively vaporized and becomes close to the atmosphere in the atmosphere. Even if plasma is generated in the atmosphere, the situation is the same as when atmospheric pressure plasma is generated, and the in-liquid plasma effect is reduced. In other words, in the liquid, the atomization reaction tends to proceed because the reactant exists near the plasma generation region. However, in the atmosphere in the atmosphere, the reactant disappears near the plasma generation region, so the plasma effect in the liquid is reduced. The atomization reaction is difficult to proceed. Therefore, in the present invention, by setting the raw material solution 10 to 90 ° C. or less, excessive vaporization (evaporation of the raw material solution 10) can be suppressed, and the atomization reaction by submerged plasma can be efficiently performed. . Reference numeral 52 denotes a container for containing the processing liquid 20 (FIG. 1). Symbol P1 schematically shows plasma discharge (FIG. 2).

The high-pressure injection processing device 152 includes a hydraulic pressure generation and control unit 101 that hydraulically drives and controls the high-pressure pump 102, a raw material tank 103 that inputs the raw material solution 10, and a high-pressure pump 102 that pressurizes the raw material solution 10, and is supplied and pressurized The sprayed particles 1a in the raw material solution 10 are jetted, accelerated, and collided to refine and disperse the particles 1a, and a heat exchanger 105 that cools the processing liquid (FIG. 1). As the high-pressure injection processing device 152, for example, a water jet developed by Sugino Machine Co., Ltd. is used, the pressure of the high-pressure injection is 100 to 245 MPa, the injection speed is 440 to 700 m / s, and the raw material solution 10 is the high-pressure nozzle. Although it is conceivable to perform atomization and dispersion by high-pressure injection from 41, the present invention is not limited to this.
The plasma generator 160 includes a plasma generation power source 30 and electrodes 31 and 32 (FIG. 1). In the liquid in the chamber 40, plasma electrodes 31 and 32 are arranged to face each other and are electrically connected to the plasma generation power source 30 (FIG. 1).
The plasma electrode 31 is provided with a distance adjusting means 33, and the distance S1 between the electrodes with the plasma electrode 32 arranged opposite to the plasma electrode 31 can be adjusted. Similarly, the plasma electrode 32 is provided with an interval adjusting means, and the inter-electrode distance S1 with the plasma electrode 31 disposed opposite to the plasma electrode 32 can be adjusted. Thereby, atomization according to the raw material solution 10 can be performed. Reference numeral 80 denotes a pump for refluxing the solution that has been subjected to the plasma treatment in liquid (FIG. 1).
The temperature control means for the raw material solution 10 includes means for increasing the temperature by injecting the raw material solution 10 at a predetermined pressure from the high pressure nozzle 41, or applying a pulse voltage between the electrodes S1, 32 to increase the temperature. In addition to the means, means using a widely used temperature control apparatus and method can be considered.

FIG. 3 is an enlarged view of a main part of the chamber 40 of the present embodiment. The chamber 40 (plasma chamber) is configured to inject the raw material solution 10 into the liquid from the high-pressure nozzle 41 to accelerate the particles to generate cavitation C1, and to discharge the suspension 20 from the outlet. Preferably, a chamber is formed by combining one end of the high-pressure injection processing device 152 having an orifice nozzle built in as the high-pressure nozzle 41 and the main part of the in-liquid plasma generator 160, and the inter-electrode distance S1 between the electrode pairs 31 and 32 The observation window 60 for adjusting the position is provided (FIG. 3).
FIG. 4 is a diagram showing, as an example, the structure of the interval adjusting means and the inter-electrode distance adjusting procedure of the present embodiment. The inter-electrode distance adjustment procedure is as follows. First, the scale bar 70 (reference bar) is directed from the OUT side of the suspension 20 toward the electrode pair 31 and 32 in a state where the high-pressure injection processing device 152 and the in-liquid plasma generator 160 are stopped. ) Is inserted. Then, while looking through the observation window 60, the scale bar 70 is disposed at an intermediate position between the electrode pairs 31 and 32, and the electrode pairs 31 and 32 are pressed toward the scale bar 70. Then pull out the scale bar. The distance adjusting means and the inter-electrode distance adjusting procedure of the present embodiment are not particularly limited to this content. For example, the electrodes may be slid by the distance adjusting means (FIG. 6) or adjusted as a nozzle type ( In addition to manual operation, a method of adjusting the distance between electrodes by driving electrically by a motor is conceivable.
FIG. 5 is a diagram showing in-liquid plasma generated when the in-liquid plasma generator 160 of the present embodiment is made of metal. When the in-liquid plasma generator 160 is made of metal, particularly when the distance between the electrodes is large, in addition to the generation of normal plasma P1, as an unintended plasma P2, the electrode 31 or electrode 32 and the in-liquid plasma generator are also used. Plasma may be generated (FIG. 5). If energization of the in-liquid plasma generator 160 occurs, there is a risk of electric shock for the operator. Therefore, in-liquid plasma generator 160 is preferably an insulating material, more preferably a resin (PTFE) in order to prevent electric shock. The high pressure nozzle 41 (orifice nozzle) is preferably made of diamond to withstand high pressure injection, and the high pressure injection processing device 152 is preferably made of stainless steel (FIGS. 3 and 4).
The chamber 40 includes various types such as a single nozzle chamber, an oblique collision chamber, and a ball collision chamber depending on the application.

  FIG. 2 is a schematic diagram showing a schematic configuration of the single nozzle chamber 40. The single nozzle chamber 40 is a type of chamber in which the raw material solution 10 is injected into the liquid from one nozzle 41 to accelerate the particles 1a and discharge the suspension 20 from the outlet 42 (FIGS. 1 and 2). The nozzle 41 uses, for example, single crystal diamond, and atomizes and disperses by a shearing force when particles pass through the nozzle 41 and a cavitation impact force caused by submerged jetting. The single nozzle chamber 40 uses the action of water cavitation and water turbulence due to its structure. Reference sign C1 is a cavitation bubble, and reference sign P1 schematically shows plasma discharge. Plasma is generated by setting the distance S1 between the electrodes to 1 mm or more and 10 mm or less, and H radicals and OH radicals are generated in the plasma generation area.

  The distance S1 between the electrodes differs depending on the type of the raw material solution 10 and the optimum distance for atomization. This is because the radical species generated by the inter-electrode distance S1 are different, and the radical species suitable for atomization are different for each type of the raw material solution 10. When the raw material solution 10 is cellulose or silica, the interelectrode distance S1 is preferably 2 mm or more and 10 mm or less, and may be 3 mm or more and 10 mm or less. When the raw material solution 10 is titanium oxide or CNT (carbon nanotube), the interelectrode distance S1 is preferably 1 mm or more and 2 mm or less. Thus, by changing the inter-electrode distance S1 between 1 mm and 10 mm, optimum atomization is achieved by controlling the generation amount of H radicals and OH radicals according to the raw material solution.

In FIG. 6, a plurality of plasma electrodes 31 (31a, 31b, 31c, 31d) and a plurality of plasma electrodes 32 (32a, 32b, 32c, 32d) are arranged at predetermined intervals in a chamber 40 directly connected to a high-pressure nozzle 41. The configuration is shown. The single nozzle chamber 40 provided with the plurality of plasma electrodes 31 and 32 has a single nozzle chamber 40 provided with the single plasma electrode pair of FIG. 2 by arranging a plurality of plasma electrodes 31 and 32 (FIG. 6). Atomization is performed more efficiently.
As in FIG. 2, each plasma electrode 31 (31a, 31b, 31c) is provided with interval adjusting means 33 (33a, 33b, 33c), and plasma that forms a pair with each plasma electrode 31 (31a, 31b, 31c). Each of the electrodes 32 (32a, 32b, 32c) also includes an interval adjusting means 34 (34a, 34b, 34c) (FIG. 6). A plurality of inter-electrode distances S <b> 1 are adjusted according to the type of the raw material solution 10, and the generation amounts of H radicals and OH radicals are controlled according to the type of the raw material solution 10. Therefore, by having a plurality of interval adjusting means 33 (33a, 33b, 33c), 34 (34a, 34b, 34c), it is possible to control atomization more optimally than the chamber 40 of FIG. 2 having only one plasma electrode pair. Do.
For example, when the raw material solution 10 is cellulose or silica, atomization is more effectively performed by setting the plurality of inter-electrode distances S1 to 2 mm to 10 mm.
Further, in the case of the raw material solution 10 in which a plurality of solutions such as cellulose, titanium oxide, and CNT are mixed, atomization is efficiently performed by changing the interelectrode distance S1 for each electrode pair. For example, the distance between the plasma electrodes 31a and 32a is set to 1 mm or more and 2 mm or less, which is optimum for atomization of titanium oxide or CNT, by the distance adjusting means 33a and 34a, and the distance by the distance adjusting means 33b and 34b. The distance between the electrodes 31b and 32b is set to 2 mm or more and 10 mm or less, which is the optimum distance between cellulose electrodes (FIG. 6). The interval adjusting means 33 and 34 may drive the electrodes arranged opposite to each other synchronously or independently. Further, the plasma electrodes 31 and 32 may generate plasma near the side wall of the chamber 40 by positioning the electrodes near the side wall in the chamber 40 like the plasma electrodes 31c and 32c. It is not necessary to have an interval adjusting means like the plasma electrode 32d.

  FIG. 7 is a schematic diagram showing a schematic configuration of the ball collision chamber 40. The ball collision chamber 40 is a type in which the raw material solution 10 is injected into the liquid from one nozzle 41 to accelerate the particles to collide with the ceramic balls 43 and discharge the suspension 20 from the outlet 42. The nozzle 41 uses single crystal diamond or the like, and the ceramic ball 43 is made of silicon nitride or the like. Atomization and dispersion are performed by the chamber shearing force of the particles that have passed through the nozzle 41, the cavitation impact force caused by submerged jetting, and the impact force when the particles collide with the ceramic balls 43. Also in the example shown in FIG. 7, a plurality of plasma electrodes 31 and 32 can be arranged in the chamber 40 at a predetermined interval as in the example shown in FIG.

  FIG. 8 is a schematic diagram showing a schematic configuration of the oblique collision chamber 40. The oblique collision chamber 40 injects the raw material solution 10 into the liquid from a pair of nozzles 41 and 41 arranged so as to collide obliquely, and accelerates the particles to cause oblique collision (face-to-face collision) with each other. In this type, the suspension 20 is discharged from 42. The nozzle 41 uses single crystal diamond or the like, facing the shearing force when particles pass through the nozzle 41, the cavitation impact force caused by submerged injection, and the impact force when particles collide obliquely. Atomization and dispersion are performed by the shear force generated by the relative velocity increase in the jet. In the case of the oblique collision chamber 40, it is possible to efficiently atomize a plurality of types of raw material solutions 10 simultaneously. Atomization is performed by spraying the raw material solution 10 into the liquid from the nozzle 41 and spraying different types of raw material solutions 10 into the liquid from the other nozzle 41 arranged oppositely. For example, it can be used when simultaneously atomizing a plurality of polysaccharides such as cellulose and hemicellulose, or when atomizing a mixture of a plurality of metals. In the case of the raw material solution 10 in which raw materials having different interelectrode distances that are optimal for atomization are mixed, a plurality of electrode pairs are prepared, and the interelectrode distances of the electrode pairs can be changed to be atomized simultaneously.

Method for Producing Dispersion of the Present Invention FIG. 9 is a production process flow chart showing a procedure for producing a dispersion in which fine particles according to an embodiment to which the present invention is applied is dispersed. The example of FIG. 9 includes step S12 and step S20. In the present embodiment, the raw material solution 10 containing the aggregates of fine particles is jetted at a high pressure from the high-pressure nozzle 41 of the high-pressure jet treatment apparatus 152 shown in FIG. 1 and immediately subjected to in-liquid plasma treatment in the chamber 40 ( Step S12). Then, depending on the degree of dispersion of the fine particles, the operation of performing high-pressure injection of the raw material solution 10 at a predetermined pressure from the high-pressure nozzle 41 of the high-pressure injection processing device 152 and performing in-liquid plasma processing in the chamber 40 is repeated a plurality of times (step) S20).

  Examples of the present invention will be described below.

Example 1
(Purpose of Example 1)
By changing the inter-electrode distance S1 of the plasma in liquid, the optimum inter-electrode distance S1 is found for each raw material solution, and the refinement effect is improved. That is, the material surface is modified to an optimum state for dispersion by controlling the interelectrode distance S1.

(Apparatus configuration of Example 1)
FIG. 10 is a schematic diagram showing the wet atomization apparatus 100 of the present embodiment. FIG. 11 is a diagram schematically showing the chamber 40, the high-pressure nozzle 41, and the plasma electrodes 31 and 32 according to the present embodiment. About the wet atomization apparatus 100 of a present Example, description is abbreviate | omitted about the point similar to FIG.
As the high-pressure injection processing device 152 (abbreviation: SBS), Starburst HJP25005 (5.5 kw) (manufactured by Sugino Machine Co., Ltd.), which is a method of causing a slurry solution jet to collide with a hard sphere, was used. The injection pressure was 200 MPa in Experiment 1, and 245 MPa in Experiment 2, Experiment 3, and Experiment 4. As the plasma generating power source 30 (abbreviation: SP), MPP-HV01 for pulse plasma (manufactured by Kurita Manufacturing Co., Ltd.) was used (FIG. 10), the maximum voltage was 4 kV, the frequency was 30 kHz, and the pulse width was 3 μs. The nozzle diameter of the high-pressure nozzle 41 provided in the chamber 40 was φ0.14 mm. The inter-electrode distance S1 of the plasma chamber 40 was 1 mm or 5 mm in Experiments 1 and 2, and 1 mm or 8 mm in Experiments 3 and 4.

(Raw material solution 10 of Example 1)
As a raw material solution 10 (atomization material), a cellulose solution having a concentration of 1 wt% suspended in 10 g of cellulose KC frog and 990 g of ion-exchanged water as a solvent was used in Experiment 1. In Experiment 2, a titanium oxide solution having a concentration of 1 wt% suspended using 6 g of titanium oxide P25 powder (manufactured by Degussa) as a solute and 594 g of a solvent was used. In Experiment 3, a silica solution having a concentration of 1 wt% in which the solute was colloidal silica SI-50 (JGC Catalysts & Chemicals) and the solvent was suspended as ion-exchanged water was used. In Experiment 4, a carbon nanotube solution having a concentration of 0.1 wt% suspended in carbon nanotube aligned multilayer (Wako Pure Chemical Industries) 0.6 g and a solvent as ion exchange water 599.4 g was used.

(Experimental procedure of Example 1)
1) The above-mentioned solvent and solute were suspended and stirred well to prepare a raw material solution 10. 2) Next, the interelectrode distance S1 of the plasma chamber 40 was set to the above-mentioned interval. 3) Thereafter, the raw material solution 10 was put into the raw material tank 103 of the starburst 152, and the starburst 152 was operated at a predetermined set value. 4) Then, it was visually confirmed that the electrodes 31 and 32 in the chamber 40 were filled with the liquid, and the plasma generating power source 30 was operated at a predetermined set value. During this time, 350 mL of the initial discharge liquid that was a dead volume in the apparatus was discarded. 5) Next, after disposal, the processed sample was stored in a separate tank, and the sample in the separate tank was returned to the raw material tank 103 as soon as the raw material tank 103 was emptied. 6) After returning, the processed samples were accumulated, and it was judged that the one-pass process was completed when the dead volume (about 350 mL) was reached. 7) Thereafter, the time required for the above procedure 5) and 6) was measured, and the number of subsequent passes was managed by time. 8) The outlet hose was fixed so that the treated sample returned to the raw material tank 103, and the raw material was circulated in the apparatus. 9) Separately, the 0-pass raw material solution 10 and the raw material solution 10 after the completion of a predetermined pass (for example, 10 pass, 20 pass, 30 pass, 60 pass) are used as sampling solutions for verifying the atomization effect. Recovered. 10) Thereafter, particle size distribution measurement, viscosity measurement or zeta potential measurement, and pH measurement were performed using the sampling solution of 0 pass and each sampling solution after a predetermined pass.

  The starburst HJP25005 includes two pressure boosters (syringes), and the injection flow rate is 500 ml / min. Since two syringes are provided, the other syringe can be discharged when one syringe is inhaled, and continuous operation is possible. Since plasma is generated when the raw material solution 10 is discharged, the plasma generation efficiency is improved. On the other hand, for example, in the case of a device having an injection flow rate of 100 ml / min and only one pressure intensifier (syringe), the device is a simple operation for performing either the suction or discharge of the raw material solution 10. That is, while the raw material solution 10 is sucked, the plasma generation effect generated when the raw material solution 10 is discharged cannot be obtained, and only the plasma generation effect by heat can be obtained. Therefore, the plasma generation efficiency is lower than that of HJP25005. Note that the starburst HJP25005, which is the high-pressure injection processing apparatus 152 of this embodiment, does not include the chamber 40 and the plasma generator 160 (the plasma generating power supply 30 and the plasma electrodes 31, 32), and the starburst HJP25005 is a chamber. 40 and the plasma generator 160 may be combined to form the wet atomization apparatus 100, and some modifications may be made.

Experiment 1 of Example 1
(Experiment conditions for Experiment 1)
The raw material solution 10 (fine material) of Experiment 1 was a 1 wt% cellulose solution containing a biomass material cellulose powder, and the interelectrode distance S1 was 1 mm or 5 mm. The sampling solution used for the measurement was the sampling solution after completion of 0 pass and 30 pass, and particle size distribution measurement, viscosity measurement, and pH measurement were performed. In addition, about the same conditions between each experiment of Example 1, it has already described as the conditions of Example 1, and description is abbreviate | omitted.

(Experiment 1 result)
Table 1 shows the particle size distribution measurement results of the treatment performed at each electrode distance S1. SBS alone indicates a case where the high-pressure injection processing device 152 is used but the plasma generation device 160 is not used, and SBS + SP is a case where the high-pressure injection processing device 152 and the plasma generation device 160 are used. Table 1 shows a comparison of experimental results (experimental results of SBS alone) in which the processing was performed with the plasma generator 160 turned off in the experimental procedure 4) of Example 1. Since the median diameters of 30 paths of the interelectrode distances S1 are different, it has been found that the atomization effect varies depending on the interelectrode distances S1. In addition, since the median diameter becomes the smallest when the distance between the electrodes is 5 mm, it has been found that the cellulose has a higher refining effect (atomization effect) than the distance between the electrodes of 1 mm.

Particle size distribution measuring device: Laser diffraction type particle size distribution measuring device (Mastersizer 3000) Spectris solute refractive index: 1.596, solvent refractive index: 1.33

  When the cellulose suspension 10 is processed by the wet atomizer (high-pressure atomizer) 100 of this example, the viscosity of the suspension increases as the fibers become finer. Therefore, the miniaturization effect of each inter-electrode distance S1 was evaluated by comparing the viscosity of 30-pass processed products. Table 2 shows the viscosity measurement results of the 30-pass treated product with each electrode distance S1. Similar to the particle size distribution measurement, in the viscosity measurement, the viscosity of the 30-pass processed product was different, and it was confirmed that a difference in the atomization effect was caused by the interelectrode distance S1. In addition, since the distance between the electrodes is 5 mm, which is the highest viscosity, it has been found that the refining effect (atomization effect) is higher when the distance between the electrodes is 1 mm than when it is 1 mm.

Viscosity measuring apparatus: B-type viscometer Measurement temperature: Brookfield, Inc. Measurement temperature: 25 ° C. (constant), Spindle: SC-21, Number of revolutions: 100 rpm, Sample amount: 8.5 g. (Read the value 30 minutes after the start of measurement.)

  Next, changes in pH are shown in Table 3. When the SBS alone and the distance between the electrodes were 5 mm, there was almost no pH change, but when the distance between the electrodes was 1 mm, the pH changed to the acidic side.

(Summary of experimental results of Experiment 1)
From the above results, it was confirmed that the miniaturization effect (atomization effect) differs depending on the interelectrode distance S1. In the cellulose treatment, the effect of miniaturization could be improved by setting the interelectrode distance S1 to 5 mm.

Experiment 2 of Example 1
(Experimental conditions for Experiment 2)
The raw material solution 10 of Experiment 2 was a 1 wt% titanium oxide solution containing titanium oxide powder as a solute, and the interelectrode distance S1 was 1 mm or 5 mm. Each sampling solution used for the measurement was obtained after completion of 0 pass, 30 pass, and 60 pass, and particle size distribution measurement, zeta potential measurement, and pH measurement were performed. In addition, the same conditions are already described in each experiment of Example 1, and the description is omitted.

(Experimental result of Experiment 2)
Table 4 shows the particle size distribution measurement results for each inter-electrode distance S1. In addition, Table 4 also shows the results of an experiment performed in the experimental procedure 4) of Example 1 while the plasma generator 160 was turned off (experimental result of SBS alone). Since the median diameters of the 30-pass and 60-pass of each inter-electrode distance S1 are different, it was found that the atomization effect is different depending on the inter-electrode distance S1. Further, since the median diameter becomes the smallest when the distance between the electrodes is 1 mm, it has been found that the titanium oxide has a higher refining effect (atomization effect) than the distance between the electrodes of 5 mm.

Particle size distribution measuring device: Dynamic scattering type particle size distribution measuring device (Zetasizer Nano ZS) Spectris, Inc. Solute refractive index: 2.72, solvent refractive index: 1.33

  In zeta potential measurement, electrostatic interaction (attraction or repulsion) acting between particles can be evaluated. For example, a particle whose absolute value of zeta potential is close to 0 is theoretically likely to agglomerate because there is little repulsive force acting between the particles. On the other hand, as the absolute value is larger than 0, the repulsive force acting between the particles increases, so that the dispersion tends to occur theoretically. Table 5 shows the zeta potential measurement results for each inter-electrode distance S1. Similarly to the particle size distribution measurement, the zeta potentials of the 30-pass and 60-pass distances between the respective electrodes were different, and it was found that the atomization effect was different depending on the inter-electrode distance S1. In addition, since the distance between the electrodes is 1 mm that has the highest zeta potential, it was found that the effect of atomization is higher when the distance between the electrodes is 1 mm than when the distance between the electrodes is 5 mm.

Particle size distribution measurement: Dynamic scattering type particle size distribution measuring device (Zetasizer Nano ZS) made by Spectris

  Next, changes in pH are shown in Table 6. The pH hardly changed when the SBS alone and the distance between the electrodes were 5 mm, but when the distance between the electrodes was 1 mm, the pH changed to the acidic side.

(Summary of experimental results of Experiment 2)
From the above results, it was confirmed that even the titanium oxide had different atomization effects depending on the interelectrode distance S1. In the titanium oxide treatment, miniaturization could be improved by setting the distance between the electrodes to 1 mm.

Experiment 3 of Example 1
(Experimental conditions for Experiment 3)
As the raw material solution 10 of Experiment 3, a 1 wt% concentration silica solution containing metal oxide colloidal silica was used as a solute, and the distance between the electrodes was set to 1 mm or 8 mm. The sampling solution used for the measurement was the sampling solution after completion of 0 pass and 30 pass, and particle size distribution measurement, viscosity measurement, and pH measurement were performed.
In addition, although the effect of the distance between electrodes is verified by the dispersion degree of colloidal silica, since colloidal silica is sold in a monodispersed state, agglomerated by pH adjustment or the like was used as a raw material. In addition, the same conditions are already described in each experiment of Example 1, and the description is omitted.

(Experimental result of Experiment 3)
Table 7 shows the particle size distribution measurement results for the distances S1 between the electrodes. In addition, Table 7 also shows the results of an experiment performed in the experimental procedure 4) of Example 1 while the plasma generator 160 was turned off (experimental results of SBS alone). Since the median diameters of 10 paths of the interelectrode distances S1 are different, it has been found that the atomization effect varies depending on the interelectrode distances S1. Further, since the median diameter becomes the smallest when the distance between the electrodes is 8 mm, it was found that the colloidal silica has a higher refining effect (atomization effect) when the distance between the electrodes is 1 mm than when the distance between the electrodes is 1 mm.

Particle size distribution measuring apparatus: Dynamic scattering type particle size distribution measuring apparatus (Zetasizer Nano ZS), solute refractive index: 1.457, solvent refractive index: 1.33 manufactured by Spectris

  Table 8 shows the zeta potential measurement results for each interelectrode distance S1. When the SBS alone after 10 passes and the inter-electrode distance S1 are 1 mm, the zeta potential is not changed, whereas when the inter-electrode distance S1 is 8 mm, the zeta potential is large. From this, it was found that in the zeta potential measurement, the effect of atomization was higher when the distance between the electrodes was 8 mm than when the distance between the electrodes was 1 mm.

Particle size distribution measurement: Dynamic scattering type particle size distribution measuring device (Zetasizer Nano ZS) made by Spectris

  Next, changes in pH are shown in Table 9. When SBS alone and the distance between the electrodes were 1 mm, the pH hardly changed, but when the distance between the electrodes was 8 mm, the pH slightly changed to the basic side.

(Summary of experimental results of Experiment 3)
From the above results, it was confirmed that even the colloidal silica had different atomization effects depending on the interelectrode distance S1. In the treatment of colloidal silica, it was possible to improve the miniaturization by setting the distance between the electrodes to 8 mm.

Experiment 4 of Example 1
(Experimental conditions for Experiment 4)
As the raw material solution 10 of Experiment 4, a 0.1 wt% carbon nanotube solution containing carbon nanotubes (CNT) as an electronic material was used as a solute, and the interelectrode distance S1 was set to 1 mm or 8 mm. The sampling liquid used for the measurement was the sampling liquid after completion of 0 pass, 10 pass, and 20 pass, and particle size distribution measurement, zeta potential measurement, and pH measurement were performed. In addition, the same conditions are already described in each experiment of Example 1, and the description is omitted.

(Experimental result of Experiment 4)
Table 10 shows the particle size distribution results of the distances S1 between the electrodes. Since the median diameters of the 10-pass and 20-pass of the interelectrode distance S1 are different, it was found that the atomization effect varies depending on the interelectrode distance S1. In addition, since the median diameter becomes the smallest when the distance between the electrodes is 1 mm, it was found that the carbon nanotube (CNT) has a higher atomization effect when the distance between the electrodes is 1 mm than when the distance between the electrodes is 8 mm.

Particle size distribution measuring device: Laser diffraction type particle size distribution measuring device (Mastersizer 3000) Spectris solute refractive index: 1.596, solvent refractive index: 1.33

  Table 11 shows the zeta potential measurement results for each electrode distance S1. Similar to the particle size distribution measurement, since the zeta potentials of the 10-pass and 20-pass distances between the electrodes are different, it was found that the atomization effect varies depending on the distance S1 between the electrodes. Since the zeta potential is the highest in 20 paths with an interelectrode distance of 1 mm, it was found that the CNT has a higher atomization effect at 1 mm than the interelectrode distance of 8 mm.

Particle size distribution measurement: Dynamic scattering type particle size distribution measuring device (Zetasizer Nano ZS) made by Spectris

  Next, changes in pH are shown in Table 12. In CNT, there was almost no pH change at any electrode distance S1.

(Summary of experimental results of Experiment 4)
From the particle size distribution measurement and the zeta potential measurement results, it was confirmed that the atomization effect varies depending on the interelectrode distance S1 even in CNT. In the CNT treatment, the effect of miniaturization could be improved by setting the interelectrode distance S1 to 1 mm.

Consideration of Example 1 In liquid plasma, it is reported that H radicals are preferentially generated when the interelectrode distance S1 is less than 2 mm, and OH radicals are preferentially generated when the interelectrode distance S1 is 2 mm or more (non-patent document). 2). In addition, these radicals are said to have a strong reducing action on the material surface, and an OH radical has a strong oxidizing action (see page 20 of Non-Patent Document 3). Based on these, it was considered what kind of reaction occurred at each electrode distance S1.
(Experiment 1 Consideration when Raw Material Solution 10 is Cellulose)
Cellulose is a polysaccharide consisting only of glucose, and forms a polymer chain by strong hydrogen bonds between and within the molecule. Cellulose has been reported to be reduced in molecular weight while having a glucose structure by treatment of plasma alone in liquid (see page 16 of Non-Patent Document 3). Also in this experiment, since the refinement of cellulose (particle size distribution measurement result, viscosity measurement result) was progressing due to the presence of plasma in the liquid, it is considered that the same molecular weight reduction of cellulose occurred. Furthermore, in this experiment, the effect of miniaturization was higher when the interelectrode distance S1 was set to 5 mm than to 1 mm, and thus it was clarified that the reduction in molecular weight is a reaction mainly occurring in the OH radical. That is, it was considered that the reduction in molecular weight of cellulose occurs when a reaction is caused by OH radicals and the covalent bond of oxygen is cleaved. In addition, in the present invention, since the treatment is performed with high-temperature and high-pressure water, it is considered that the effect of miniaturization is enhanced by synergistically combining the dispersing action by the hydrothermal method or the mechanochemical method of mechanically pulverizing. From these facts, it is considered that the present invention is effective not only for cleaving β1- → 4 bonds of cellulose but also for decomposing other polysaccharides. For example, it is also effective for decomposing hemicellulose into xylose, mannose, and furfural. It is guessed.
In addition, low molecular weight of cellulose by plasma alone in liquid is considered to be a limited reaction only on the cellulose surface (see Non-Patent Document 3, page 16). In this experiment, since the specific surface area of cellulose was increased by high-pressure wet jetting, it was considered that the lowering of the molecular weight was performed more efficiently than the liquid plasma alone. On the other hand, in pH, after 30-pass treatment with a distance between electrodes of 1 mm, the pH slightly changed. This is because some H radicals having a strong reducing action were generated and reacted with oxygen and nitrogen in the air to generate nitric acid or nitrous acid. It is said that fibrillation efficiency is improved by high-pressure jetting of cellulose under acidic conditions. However, after 30-pass treatment with a distance between electrodes of 1 mm, the pH was 4.58, indicating weak acidity. I think it didn't happen.
(Experiment 2 Raw Material Solution 10 is Titanium Oxide, Experiment 3 Consideration when Raw Material Solution 10 is Colloidal Silica)
Since titanium oxide has a high refining effect when the distance between the electrodes is 1 mm, it is assumed that surface modification with H radicals is effective. As in the case of cellulose, when the distance between the electrodes of titanium oxide was 1 mm, the pH changed to the acidic side after 60 passes. That is, titanium oxide is considered to be in the form of the hydroxyl group of Ti—OH in the solution, but this is added to H ⁺ by the reducing action of H radicals to become Ti— (OH ₂ ) ⁺ , and the raw material solution Is presumed to be inclined toward the acidic side. Since titanium oxide is a metal oxide material having an isoelectric point near pH 6, the particle surface changes to a positively charged state when the pH is shifted to the acidic side. As a result, an electrostatic repulsive force is generated in the inter-particle distance, and it is considered that the atomization effect is improved. However, since the isoelectric point differs depending on the type of metal oxide material, it is assumed that the effective radicals differ depending on the type of material and the isoelectric point. For example, colloidal silica (silicon oxide particles) is a metal oxide material having an isoelectric point in the vicinity of pH 2 to 3, so that the generated OH radical shifts the pH to the basic side from the isoelectric point. The particle surface changes to a negatively charged state. As a result, an electrostatic repulsion force is generated in the inter-particle distance, and it is assumed that the atomization effect is improved.
Thus, in the wet atomization method of the present invention, in the metal oxide atomization apparatus, the metal oxide particles are shifted from the isoelectric point of the metal oxide to the acidic side or the basic side by the high pressure injection method with increased temperature. It has been inferred that the surface is charged with a positive charge or a negative charge, and an effect of miniaturization is generated by electrostatic repulsion.
(Experiment 4 Consideration in case raw material solution 10 is carbon nanotube)
Carbon nanotubes (CNT) are hydrophobic, poorly compatible with water, and difficult to disperse. This is because CNT is a nonpolar material composed of a six-membered ring of carbon atoms, and therefore does not form hydrogen bonds with water molecules having polarity. So far, O ₂ generated from the O ₂ plasma in the pulse streamer discharge and the gas-liquid interface in the liquid ^- by radicals or OH radicals, CNT surfaces are reported to have hydrophilic (non-patent document 4). Non-patent document 4 reports the hydrophilicity of the surface of carbon nanoballs, which are spherical carbon nanomaterials with nano-order diameters. As with carbon nanomaterials, the surface of carbon nanoballs before solution plasma treatment has hydrophobic functionalities. Group exists, and the surface of carbon nanoballs is oxidized by oxygen radicals, hydroxyl radicals, hydrogen peroxide, etc. generated from solution plasma, and hydrophilic functional groups such as hydroxy groups (—OH), aldehyde groups (—COH), and carboxyls. By becoming a group (—COOH), the carbon nanoball surface is expected to change to hydrophilicity. In the present application, since the reducing action is caused by the generation of H radicals, it is assumed that the following mechanism is working different from the above mechanism.
That is, in this experiment, the effect of refinement (particle size distribution measurement, zeta potential measurement result) was improved at a distance of 1 mm between the electrodes. The reason why the dispersion of N is superior is that the H radical worked effectively in the dispersion from the experimental results of CNT (dispersion is good at a distance between electrodes of 1 mm). It is thought that radical substitution reaction occurred and the following dispersion progressed. The first dispersion progression pattern is that 1) the C—C bond is broken by the radical substitution reaction, and 2) the overall strength of the CNT is reduced, so that the refinement by the wet atomizer proceeds. . As the second pattern, 1) C radicals generated by radical substitution reaction cleave the O—H bond of water (H—O—H), and 2) have hydroxyl groups on the surface, so that wetting is possible. And the refinement by the wet atomization apparatus has progressed. In addition, as with cellulose, hydrophilization with liquid plasma alone is considered to be a limited reaction only on the surface, but in this experiment, the specific surface area of CNT is increased by high-pressure wet jet, so It is thought that hydrophilization is efficiently performed.

  In the present embodiment, the paired plasma electrodes 31 and 32 have been described as being one, but there may be a plurality of paired plasma electrodes 31 and 32 (FIG. 12). FIG. 12 is a schematic diagram when a plurality of plasma electrodes 31 and 32 forming a pair are arranged to face each other and are driven electrically as a nozzle shape so that the distance between the electrodes can be adjusted. That is, the electrode 32a is disposed opposite to the electrode 31a, the electrode 32b is disposed opposite to the electrode 31b, and the electrode 32c is disposed opposite to the electrode 31c. Even when the plurality of plasma electrodes 31 and 32 are arranged to face each other (FIG. 12), the above-described case according to the distance S1 between the electrodes is the same as the case where one plasma electrode 31 and 32 is arranged to face each other (FIG. 11). Can be expected.

Example 2
Example 2 of the present invention is an experiment relating to plasma in liquid and liquid temperature. FIG. 13 is a schematic view illustrating the plasma generator 160 and the chamber 40 of this embodiment. FIG. 14 is a schematic view illustrating the wet atomization apparatus 100 of this embodiment. The wet atomization apparatus 100 (FIG. 13) of the present embodiment differs from the wet atomization apparatus 100 of the first embodiment (FIG. 10) in the arrangement configuration of the heat exchanger 105. Reference symbol T denotes a tube pump T for feeding the raw material solution 10 from the chamber 40 to the raw material tank 103, and high-pressure injection is not performed in this embodiment. Note that points that are the same as those in the apparatus of FIGS. 1 and 10 are omitted.

Purpose, experimental method and results of Example 2 (purpose)
In order to verify the problem that the plasma generation status changes depending on the raw material temperature, a test was conducted to confirm the presence or absence of plasma generation using the simple circuit of FIG. 13 and the pseudo circuit of FIG. 14 (a circuit similar to an actual experimental circuit). did.
(experimental method)
As the experimental raw material solution 10, a solution obtained by adding 0.012 g of NaCl to 600 g of ion-exchanged water was used. First, the temperature of the raw material solution 10 was adjusted to 60 ° C. in a constant temperature room. Thereafter, 200 g of the raw material solution 10 having reached 60 ° C. in the circuit of FIG. 13 was used, and the presence or absence of plasma generation at 60 ° C. was confirmed. The remaining raw material solution 10 was equally divided into 400 g, and the temperature was adjusted to 20 ° C. and 40 ° C. by natural cooling. Thereafter, similarly, the presence or absence of plasma generation at each liquid temperature was confirmed. A similar experiment was also performed in the pseudo circuit of FIG.
(result)
As a result of confirming the presence or absence of plasma generation at each temperature, plasma was generated within 5 seconds after discharge at 60 ° C., plasma was generated in about 1 minute at 40 ° C., and plasma was generated in about 7 minutes at 20 ° C. From this, it was found that the time required to generate plasma differs depending on the temperature of the initial raw material solution 10. Further, when the temperature of the liquid near the electrodes 31 and 32 was measured when plasma was generated under the conditions of 20 ° C. and 40 ° C., the temperature increased to 32 ° C. and 48 ° C., respectively. This temperature rise is thought to be due to the generation of Joule heat accompanying the discharge. That is, it is considered that the temperature of the raw material solution 10 was increased by applying a pulse voltage to the electrodes 31 and 32. Further, while the raw material solution 10 circulates in the wet atomization apparatus 100, physical friction occurs between the raw material solution 10 and the wet atomization apparatus 100, and Joule heat is generated, so that the temperature of the raw material solution is increased. The rise is thought to have occurred. This friction is, for example, friction when jetting the high-pressure raw material solution 10 from the high-pressure nozzle 41 of the high-pressure jet processing device 152.
Moreover, it was guessed from the liquid temperature measured after plasma generation that plasma generate | occur | produces at about 40 degreeC or more liquid temperature. Therefore, by setting the raw material solution 10 to 40 ° C. or higher, vaporization of the raw material solution 10 necessary for generating plasma can be generated at a minimum, and plasma can be generated between the electrodes S1 of the plasma electrodes 31 and 32. it can. Moreover, by setting it as 90 degrees C or less, atmospheric pressure plasma by excessive vaporization (evaporation of the raw material solution 10) can be suppressed, and the plasma effect in a liquid can be obtained efficiently.
As a result of performing the same experiment in the pseudo circuit of FIG. 14, in the state where the cooling water of the heat exchanger 105 is emptied (without cooling), all of the simple circuits (60 ° C., 40 ° C., and 20 ° C.) Plasma was generated in the same time as in the experiment using FIG. However, when the experiment was performed with the raw material at 20 ° C. while flowing the cooling water through the heat exchanger 105, plasma was not generated even after 1 hour or more.

Consideration of Example 2 From the above results, it is considered that in-liquid plasma is generated through the following steps.
1. The discharge of the plasma electrodes 31 and 32 activates the thermal motion of free electrons and cations (generates Joule heat).
2. As the temperature rises, the solvent in the vicinity of the plasma electrodes 31 and 32 is vaporized and bubbles are generated.
3. Plasma is generated in the generated bubbles, and the atomization effect is improved.
The time required for generating plasma in this test is considered to be the time required for the raw material solution 10 to vaporize. When the initial raw material temperature is high, the thermal movement of the cation is active and the rate of increase of Joule heat is high, so that the amount of heat necessary for the vaporization of the solvent can be easily obtained, and the vaporization has occurred rapidly. On the other hand, when the initial raw material temperature is low, the thermal motion of cations is slow and the rate of increase in Joule heat is low, so that the amount of heat obtained is small and it takes time for vaporization. Further, in the case where there is the heat exchanger 10, since the generated Joule heat is lost by cooling, it is considered that vaporization does not occur and plasma is not generated.

Summary of Considerations for Example 1 and Example 2 Considerations for Example 1 (Experiments 1 to 4) and Example 2 are summarized below.
1. Since OH radicals are effective for materials that form a polymer by hydrogen bonding such as cellulose fiber, the inter-electrode distance S1 of plasma in liquid is desirably 2 mm or more and 10 mm or less, more preferably 5 mm or more and 10 mm or less. Is desirable.
2. Metal oxides such as titanium oxide and colloidal silica have different effective radicals for each isoelectric point specific to the material. In titanium oxide having an isoelectric point of pH 6, since H radicals are effective, the interelectrode distance S1 of the plasma in liquid is desirably 2 mm or less, and more desirably 1 mm or more and 2 mm or less. In colloidal silica having an isoelectric point in the vicinity of pH 2 to 3, OH radicals are effective. Therefore, the interelectrode distance S1 of the plasma in liquid is preferably 2 mm or more and 10 mm or less, more preferably 5 mm or more and 10 mm or less.
3. In a material such as CNT that does not have polarity on the surface of the material and does not easily blend with water, hydrophilicity by H radicals is effective. Therefore, the inter-electrode distance S1 of the plasma in liquid is desirably 2 mm or less, more preferably 1 mm or more. Within 2 mm is desirable.
4. By making high-pressure injection of 200 MPa or more, or increasing the number of treatments by increasing the number of passes to 10 or more, the atomization effect is further improved.
5. After the temperature of the raw material solution 10 of the atomization apparatus 100 is raised in advance, the atomization effect is improved by performing plasma treatment in liquid.

  The present invention is not limited to the embodiment described above. The above-described cellulose atomization can be applied to aggregates of biomass nanofibers. Titanium oxide atomization can be applied to aggregates of barium titanate, ferrite, alumina, silica, and other known metal oxide fine particles, and CNT atomization can be applied to atomization of carbon nanomaterials. In addition, the present invention can be applied to aggregates of pharmaceutical materials. Various embodiments can be used in appropriate combination. For example, an additive having at least electrostatic repulsion or steric hindrance action may be added to the fine particles. Thus, it goes without saying that the present invention can be modified as appropriate without departing from the spirit of the present invention.

10 Raw material solution,
20 dispersion,
1a particles,
1b fine particles,
30 Plasma generation power source,
31 (31a, 31b, 31c, 31d), 32 (32a, 32b, 32c, 32d) electrodes,
33 (33a, 33b, 33c), 34 (33a, 33b, 33c) interval adjusting means,
40 chambers,
41 high pressure nozzle,
52 containers,
60 observation window,
70 Scale bar (reference bar),
80 pumps,
90 air supply means,
100 Wet atomization apparatus of the present invention,
152 high pressure injection processing device,
160 In-liquid plasma generator,
C1 cavitation (bubbles),
P1 Plasma generation location in liquid,
S1 Distance between electrodes

Claims (10)

  A high-pressure injection processing apparatus that injects high pressure from a high-pressure nozzle provided in the chamber and a submerged plasma generator are combined, and the electrodes of the submerged plasma generator are arranged to face each other in the chamber, A pulse voltage is applied to some of the electrodes to raise the temperature of the raw material solution, and then a pulse voltage is applied to some of the electrodes to generate plasma and / or the high pressure of the high-pressure injection processing apparatus The raw material solution is injected from the nozzle to raise the temperature of the raw material solution, and then a pulse voltage is applied to some of the electrodes to generate a plasma in liquid, and the cavitation due to the high pressure injection is exerted on the plasma generation area. Wet atomization method characterized by the above.   Plasma is generated with the distance between the electrodes being 1 mm or more and 10 mm or less, and the temperature of the raw material solution is set to 40 degrees or higher, and / or the raw material solution is injected from the high pressure nozzle of the high pressure injection processing apparatus, The wet atomization according to claim 1, wherein the temperature of the raw material solution is raised to 40 ° C or more by generating a plasma by applying a pulse voltage to some of the electrodes after raising the temperature of the raw material solution. Method.   The raw material solution is cellulose, the distance between the electrodes is 2 mm or more and 10 mm or less, OH radicals are generated, and the cellulose is reduced in size by the reaction mainly composed of OH radicals, and is atomized. The wet atomization method according to claim 1 or 2.   The raw material solution is titanium oxide, the distance between the electrodes is 1 mm or more and 2 mm or less to generate H radicals, and the pH of the raw material solution is shifted from the isoelectric point of titanium oxide to the acidic side, whereby the titanium oxide 3. The wet atomization method according to claim 1 or 2, wherein the particle surface is changed to a positively charged state and an electrostatic repulsive force is generated between the particles to cause atomization.   The raw material solution is silica, and the distance between the electrodes is set to 2 mm or more and 10 mm or less to generate OH radicals, and the pH of the raw material solution is shifted from the isoelectric point of silica to the basic side, thereby the surface of the silica particles 3. The wet atomization method according to claim 1 or 2, wherein the particles are atomized by changing to a negatively charged state and generating an electrostatic repulsive force between the particles.   The raw material solution is a carbon nanotube, wherein the distance between the electrodes is 1 mm or more and 2 mm or less, H radicals are generated, and a radical substitution reaction is caused between the H radicals and the carbon nanotubes to atomize. The wet atomization method according to claim 1 or 2.   A high-pressure nozzle for high-pressure injection of a raw material solution containing agglomerates of fine particles and a plasma generator provided with an electrode, the high-pressure nozzle is provided in a chamber, and the electrode is opposed to the chamber A wet atomization apparatus that is disposed and disposed at a position where cavitation by the high-pressure injection extends to a plasma generation area between the electrodes, comprising a gap adjusting means capable of controlling a distance between the electrodes. Wet atomization equipment.   The wet atomization apparatus according to claim 7, wherein the electrode is also used as an electrode for increasing a temperature of the raw material solution.   The wet atomization apparatus according to claim 7 or 8, wherein the electrode comprises a plurality of electrode pairs.   The wet atomization apparatus according to claim 7 or 8, further comprising temperature control means for increasing the temperature of the raw material solution.