JP2020142232A - Ultra fine bubble generation method, ultra fine bubble generation device, and ultra fine bubble containing liquid - Google Patents

Abstract

To provide an ultra fine bubble generation device which can efficiently generate an ultra fine bubble containing liquid having high purity, and to provide an ultra fine bubble generation method.SOLUTION: An ultra fine bubble generation device 1 includes: a generation unit 300 for generating ultra fine bubbles 11 in a liquid; and an after-treatment unit 400 which performs predetermined after-treatment to an ultra fine bubble containing liquid W generated by the generation unit 300. In the generation unit 300, a heating element 10 provided in a liquid W in which preliminary treatment is performed is heated to cause film boiling on an interface between the liquid W and the heating element 100 and thereby generate the ultra fine bubbles 11.SELECTED DRAWING: Figure 1

Description

The present invention relates to an ultrafine bubble generation method for generating ultrafine bubbles having a diameter of less than 1.0 μm, an ultrafine bubble generation device, and an ultrafine bubble-containing liquid.

In recent years, techniques have been developed that apply the characteristics of fine bubbles such as microbubbles having a diameter of micrometer and nanobubbles having a diameter of nanometer. In particular, the usefulness of Ultra Fine Bubble (hereinafter, also referred to as “UFB”) having a diameter of less than 1.0 μm has been confirmed in various fields.

Patent Document 1 discloses a fine bubble generator that generates fine bubbles by ejecting a pressurized liquid in which a gas is pressurized and dissolved from a pressure reducing nozzle. Further, Patent Document 2 discloses an apparatus for generating fine bubbles by repeatedly dividing and merging gas mixed liquids using a mixing unit.

Japanese Patent No. 6118544 Japanese Patent No. 4456176

In any of the devices described in Patent Documents 1 and 2, in addition to the UFB having a diameter of nanometer size, a relatively large amount of microbubbles having a diameter of millimeter size and microbubbles having a diameter of micron meter size are generated. However, since buoyancy acts on millibubbles and microbubbles, they tend to gradually rise to the liquid surface and disappear during long-term storage.

On the other hand, UFB having a diameter of nanometer size is not easily affected by buoyancy and floats in the liquid while performing Brownian motion, so that it is suitable for long-term storage. However, even in UFB, if it is generated together with microbubbles or microbubbles, or if the gas-liquid interface energy is small, it is affected by the disappearance of the millibubbles and microbubbles and decreases with the passage of time. That is, in order to obtain a UFB-containing liquid in which a decrease in UFB concentration is suppressed even after long-term storage, UFB having a high gas-liquid interface energy is generated with high purity and high concentration at the time of producing the UFB-containing liquid. Is required.

The present invention has been made to solve the above problems. Therefore, an object of the present invention is to provide a UFB generator and a UFB generation method capable of efficiently producing a highly pure UFB-containing liquid.

Therefore, the present invention has a generation step of generating an ultrafine bubble by generating heat of a heat generating element provided in the liquid and causing a film to boil at the interface between the liquid and the heat generating element, and a generation step of generating the ultrafine bubble. It is characterized by having a post-treatment step of performing a predetermined post-treatment on the ultra-fine bubble-containing liquid containing the ultra-fine bubbles.

According to the present invention, it is possible to efficiently produce a highly pure UFB-containing liquid.

It is a figure which shows an example of a UFB generator. It is a schematic block diagram of a pretreatment unit. It is a schematic block diagram of a dissolution unit and the figure for demonstrating the dissolution state of a liquid. It is a schematic block diagram of the T-UFB generation unit. It is a figure for demonstrating the detail of a heat generating element. It is a figure for demonstrating the state of the film boiling in a heating element. It is a figure which shows the state that UFB is generated with the expansion of a membrane boiling bubble. It is a figure which shows the state that UFB is generated with the contraction of a membrane boiling bubble. It is a figure which shows a mode that UFB is generated by reheating of a liquid. It is a figure which shows the state that UFB is generated by the shock wave at the time of defoaming a membrane boiling bubble. It is a figure which shows the state that UFB is generated by the change of the saturation solubility. It is a figure which shows the 4th post-processing mechanism. It is a figure which shows the 5th post-processing mechanism.

<< Configuration of UFB generator >>
FIG. 1 is a diagram showing an example of a UFB generator applicable to the present invention. The UFB generator 1 of this embodiment includes a pretreatment unit 100, a dissolution unit 200, a T-UFB generation unit 300, a posttreatment unit 400, and a recovery unit 500. The liquid W such as tap water supplied to the pretreatment unit 100 is subjected to treatment unique to each unit in the above order, and is recovered as a T-UFB-containing liquid in the recovery unit 500. The functions and configurations of each unit will be described below. Although the details will be described later, in the present specification, the UFB generated by utilizing the film boiling associated with the rapid heat generation is referred to as T-UFB (Thermal-Ultra Fine Bubble).

FIG. 2 is a schematic configuration diagram of the pretreatment unit 100. The pretreatment unit 100 of the present embodiment degass the supplied liquid W. The pretreatment unit 100 mainly has a degassing container 101, a shower head 102, a decompression pump 103, a liquid introduction path 104, a liquid circulation path 105, and a liquid outlet path 106. For example, the liquid W such as tap water is supplied to the degassing container 101 from the liquid introduction path 104 via the valve 109. At this time, the shower head 102 provided in the degassing container 101 atomizes the liquid W and sprays it into the degassing container 101. The shower head 102 is for promoting the vaporization of the liquid W, but a centrifuge or the like can be substituted as a mechanism for producing the vaporization promoting effect.

After a certain amount of liquid W is stored in the degassing container 101, when the decompression pump 103 is operated with all valves closed, the already vaporized gas component is discharged and dissolved in the liquid W. The vaporization and discharge of existing gas components are also promoted. At this time, the internal pressure of the degassing container 101 may be reduced to about several hundred to several thousand Pa (1.0 Torr to 10.0 Torr) while checking the pressure gauge 108. The gas degassed by the degassing unit 100 includes, for example, nitrogen, oxygen, argon, carbon dioxide and the like.

The degassing treatment described above can be repeated for the same liquid W by using the liquid circulation path 105. Specifically, the shower head 102 is operated with the valve 109 of the liquid introduction path 104 and the valve 110 of the liquid lead-out path 106 closed and the valve 107 of the liquid circulation path 105 open. As a result, the liquid W stored in the degassing container 101 and once degassed is sprayed again on the degassing container 101 via the shower head 102. Further, by operating the decompression pump 103, the vaporization treatment by the shower head 102 and the degassing treatment by the decompression pump 103 are performed repeatedly on the same liquid W. Then, each time the above-mentioned repeated treatment using the liquid circulation path 105 is performed, the gas component contained in the liquid W can be gradually reduced. When the liquid W degassed to a desired purity is obtained, the liquid W is sent to the dissolution unit 200 via the liquid lead-out path 106 by opening the valve 110.

Although FIG. 2 shows a degassing unit 100 in which the gas portion is made low pressure to vaporize the dissolved liquid, the method for degassing the dissolved liquid is not limited to this. For example, a heating boiling method in which the liquid W is boiled to vaporize the dissolved substance may be adopted, or a membrane degassing method in which a hollow fiber is used to increase the interface between the liquid and the gas may be adopted. As a degassing module using a hollow thread, the SEPAREL series (manufactured by Dainippon Ink Co., Ltd.) is commercially available. This is used for the purpose of using poly4-methylpentene-1 (PMP) as a raw material for the hollow fiber membrane and degassing air bubbles mainly from ink supplied to the piezo head. Further, two or more of the vacuum degassing method, the heating boiling method, and the membrane degassing method may be used in combination.

3A and 3B are a schematic configuration diagram of the dissolution unit 200 and a diagram for explaining the dissolution state of the liquid. The dissolution unit 200 is a unit that dissolves a desired gas in the liquid W supplied from the pretreatment unit 100. The dissolution unit 200 of the present embodiment mainly includes a dissolution container 201, a rotary shaft 203 to which a rotary plate 202 is attached, a liquid introduction path 204, a gas introduction path 205, a liquid lead-out path 206, and a pressurizing pump 207.

The liquid W supplied from the pretreatment unit 100 is supplied to and stored in the dissolution container 201 from the liquid introduction path 204. On the other hand, the gas G is supplied to the dissolution container 201 from the gas introduction path 205.

When a predetermined amount of the liquid W and the gas G are stored in the dissolution container 201, the pressurizing pump 207 is operated to raise the internal pressure of the dissolution container 201 to about 0.5 Mpa. A safety valve 208 is arranged between the pressurizing pump 207 and the dissolution container 201. Further, by rotating the rotating plate 202 in the liquid via the rotating shaft 203, the gas G supplied to the dissolution container 201 is bubbled, the contact area with the liquid W is increased, and the gas G is dissolved in the liquid W. Facilitate. Then, such an operation is continued until the solubility of the gas G reaches almost the maximum saturated solubility. At this time, in order to dissolve as much gas as possible, means for lowering the temperature of the liquid may be arranged. Further, in the case of a poorly soluble gas, the internal pressure of the dissolution container 201 can be increased to 0.5 MPa or more. In that case, it is necessary to optimize the material of the container from the viewpoint of safety.

When the liquid W in which the components of the gas G are dissolved at a desired concentration is obtained, the liquid W is discharged via the liquid lead-out path 206 and supplied to the T-UFB generation unit 300. At this time, the back pressure valve 209 adjusts the flow pressure of the liquid W so that the pressure at the time of supply does not become higher than necessary.

FIG. 3B is a diagram schematically showing how the gas G mixed in the dissolution container 201 is dissolved. The bubble 2 containing the component of the gas G mixed in the liquid W dissolves from the portion in contact with the liquid W. Therefore, the bubble 2 gradually contracts, and the gas-dissolved liquid 3 exists around the bubble 2. Since buoyancy acts on the bubbles 2, the bubbles 2 move to a position deviated from the center of the gas-dissolved liquid 3 or separate from the gas-dissolved liquid 3 to become residual bubbles 4. That is, in the liquid W supplied to the T-UFB generation unit 300 via the liquid lead-out path 206, the gas-dissolved liquid 3 surrounds the bubbles 2, or the gas-dissolved liquid 3 and the bubbles 2 are separated from each other. Some of the states are mixed.

In the figure, the gas-dissolved liquid 3 means "a region in which the dissolved concentration of the mixed gas G is relatively high in the liquid W". In the gas component actually dissolved in the liquid W, the concentration is highest in the periphery of the bubble 2 or in the center of the region even when separated from the bubble 2, and the concentration of the gas component is continuous as the distance from the position increases. It becomes low. That is, in FIG. 3B, the region of the gas-dissolved liquid 3 is surrounded by a broken line for explanation, but in reality, such a clear boundary does not exist. Further, in the present invention, it is permissible for a gas that is not completely dissolved to exist in the liquid in the form of bubbles.

FIG. 4 is a schematic configuration diagram of the T-UFB generation unit 300. The T-UFB generation unit 300 mainly includes a chamber 301, a liquid introduction path 302, and a liquid lead-out path 303, and a flow pump from the liquid introduction path 302 through the chamber 301 to the liquid lead-out path 303 is not shown. Is formed by. As the flow pump, various pumps such as a diaphragm pump, a gear pump, and a screw pump can be adopted. In the liquid W introduced from the liquid introduction path 302, the gas-dissolved liquid 3 of the gas G mixed by the dissolution unit 200 is mixed.

An element substrate 12 provided with a heat generating element 10 is arranged on the bottom surface of the chamber 301. When a predetermined voltage pulse is applied to the heat generating element 10, bubbles 13 generated by film boiling (hereinafter, also referred to as film boiling bubbles 13) are generated in a region in contact with the heat generating element 10. Then, an ultrafine bubble (UFB11) containing a gas G is generated as the film boiling bubble 13 expands or contracts. As a result, the UFB-containing liquid W containing a large number of UFB 11s is derived from the liquid lead-out path 303.

5 (a) and 3 (b) are views showing the detailed structure of the heat generating element 10. FIG. 5A shows a cross-sectional view of the element substrate 12 in the vicinity of the heat-generating element 10, and FIG. 5B shows a cross-sectional view of the element substrate 12 in a wider area including the heat-generating element 10.

As shown in FIG. 5A, in the element substrate 12 of the present embodiment, a thermal oxide film 305 as a heat storage layer and an interlayer film 306 also serving as a heat storage layer are laminated on the surface of the silicon substrate 304. .. As the interlayer film 306, a SiO ₂ film or a SiN film can be used. A resistance layer 307 is formed on the surface of the interlayer film 306, and a wiring 308 is partially formed on the surface of the resistance layer 307. As the wiring 308, an Al alloy wiring such as Al, Al—Si, or Al—Cu can be used. A protective layer 309 made of a SiO ₂ film or a Si3N4 film is formed on the surfaces of the wiring 308, the resistance layer 307, and the interlayer film 306.

On the surface of the protective layer 309, the portion corresponding to the heat acting portion 311 that eventually becomes the heat generating element 10 and its surroundings are protected from the chemical and physical impacts caused by the heat generated by the resistance layer 307. A cavitation resistant film 310 is formed to protect the surface. On the surface of the resistance layer 307, the region where the wiring 308 is not formed is the heat acting portion 311 in which the resistance layer 307 generates heat. The heat generating portion of the resistance layer 307 on which the wiring 308 is not formed functions as a heat generating element (heater) 10. As described above, the layers in the element substrate 12 are sequentially formed on the surface of the silicon substrate 304 by the semiconductor manufacturing technology, whereby the silicon substrate 304 is provided with the heat acting portion 311.

The configuration shown in the figure is an example, and various other configurations can be applied. For example, a configuration in which the stacking order of the resistance layer 307 and the wiring 308 is reversed, and a configuration in which an electrode is connected to the lower surface of the resistance layer 307 (so-called plug electrode configuration) can be applied. That is, as will be described later, the structure may be such that the liquid can be heated by the heat acting unit 311 to cause film boiling in the liquid.

FIG. 5B is an example of a cross-sectional view of a region of the element substrate 12 including a circuit connected to the wiring 308. The surface layer of the silicon substrate 304, which is a P-type conductor, is partially provided with an N-type well region 322 and a P-type well region 323. By introducing and diffusing impurities such as ion implantation by a general MOS process, P-MOS 320 is formed in the N-type well region 322, and N-MOS 321 is formed in the P-type well region 323.

The P-MOS 320 is composed of a source region 325 and a drain region 326 formed by partially introducing N-type or P-type impurities into the surface layer of the N-type well region 322, a gate wiring 335, and the like. The gate wiring 335 is deposited on the surface of the N-type well region 322 excluding the source region 325 and the drain region 326 via a gate insulating film 328 having a thickness of several hundred Å.

The N-MOS 321 is composed of a source region 325 and a drain region 326 formed by partially introducing N-type or P-type impurities into the surface layer of the P-type well region 323, a gate wiring 335, and the like. The gate wiring 335 is deposited on the surface of the P-shaped well region 323 excluding the source region 325 and the drain region 326 via a gate insulating film 328 having a thickness of several hundred Å. The gate wiring 335 is made of polysilicon with a thickness of 3000Å to 5000Å deposited by the CVD method. The C-MOS logic is composed of these P-MOS 320 and N-MOS 321.

In the P-type well region 323, an N-MOS transistor 330 for driving an electric heat conversion element (heat generation resistance element) is formed in a portion different from the N-MOS 321. The N-MOS transistor 330 is composed of a source region 332 and a drain region 331 partially formed on the surface layer of the P-type well region 323 by steps such as introduction and diffusion of impurities, and a gate wiring 333 and the like. The gate wiring 333 is deposited on the surface of the portion of the P-shaped well region 323 excluding the source region 332 and the drain region 331 via the gate insulating film 328.

In this example, an N-MOS transistor 330 is used as a driving transistor for the electrothermal conversion element. However, the driving transistor may be any transistor that has the ability to individually drive a plurality of electrothermal conversion elements and can obtain the fine structure as described above, and the N-MOS transistor 330 has Not limited. Further, in this example, the electrothermal conversion element and the driving transistor thereof are formed on the same substrate, but these may be formed on different substrates.

An oxide membrane separation region 324 is formed by field oxidation with a thickness of 5000Å to 10000Å between each element such as between P-MOS320 and N-MOS321 and between N-MOS321 and N-MOS transistor 330. ing. Each element is separated by the oxide membrane separation region 324. In the oxide film separation region 324, the portion corresponding to the heat acting portion 311 functions as the first heat storage layer 334 on the silicon substrate 304.

An interlayer insulating film 336 made of a PSG film or BPSG film having a thickness of about 7,000 Å is formed on the surface of each element of the P-MOS 320, N-MOS 321 and N-MOS transistor 330 by the CVD method. After the interlayer insulating film 336 is flattened by heat treatment, an Al electrode 337 serving as a first wiring layer is formed through a contact hole penetrating the interlayer insulating film 336 and the gate insulating film 328. On the surfaces of the interlayer insulating film 336 and the Al electrode 337, an interlayer insulating film 338 composed of a SiO ₂ film having a thickness of 10000 Å to 15000 Å is formed by a plasma CVD method. On the surface of the interlayer insulating film 338, a resistance layer 307 made of a TaSiN film having a thickness of about 500 Å is formed by a co-splat method on a portion corresponding to the heat acting portion 311 and the N-MOS transistor 330. The resistance layer 307 is electrically connected to the Al electrode 337 in the vicinity of the drain region 331 via a through hole formed in the interlayer insulating film 338. On the surface of the resistance layer 307, Al wiring 308 as a second wiring layer serving as wiring to each electric heat conversion element is formed. The wiring 308, the resistance layer 307, and the protective layer 309 on the surface of the interlayer insulating film 338 are made of a SiN film having a thickness of 3000 Å formed by the plasma CVD method. The cavitation-resistant film 310 deposited on the surface of the protective layer 309 is at least one metal selected from Ta, Fe, Ni, Cr, Ge, Ru, Zr, Ir, etc., and is a thin film having a thickness of about 2000Å. Consists of. As the resistance layer 307, various materials other than the above-mentioned TaSiN, such as TaN0.8, CrSiN, TaAl, and WSiN, which can cause film boiling in a liquid, can be applied.

6 (a) and 6 (b) are views showing a state of film boiling when a predetermined voltage pulse is applied to the heat generating element 10. Here, the case where the film boiling under atmospheric pressure is caused is shown. In FIG. 6A, the horizontal axis represents time. The vertical axis of the lower graph shows the voltage applied to the heat generating element 10, and the vertical axis of the upper graph shows the volume and internal pressure of the film boiling bubbles 13 generated by the film boiling. On the other hand, FIG. 6B shows the state of the film boiling foam 13 in association with the timings 1 to 3 shown in FIG. 6A. Hereinafter, each state will be described over time. As will be described later, the UFB 11 generated by the film boiling is mainly generated near the surface of the film boiling bubble 13. In the state shown in FIG. 6B, as shown in FIG. 1, the UFB 11 generated in the generation unit 300 is re-supplied to the dissolution unit 200 via the circulation path, and the liquid is again supplied to the liquid passage of the generation unit 300. Indicates the supplied state.

Before the voltage is applied to the heating element 10, the inside of the chamber 301 is maintained at substantially atmospheric pressure. When a voltage is applied to the heating element 10, the liquid in contact with the heating element 10 undergoes film boiling, and the generated bubbles (hereinafter referred to as film boiling bubbles 13) expand due to the high pressure acting from the inside (timing 1). .. The foaming pressure at this time is considered to be about 8 to 10 MPa, which is a value close to the saturated vapor pressure of water.

The voltage application time (pulse width) is about 0.5 ussec to 10.0 ussec, but even after the voltage is no longer applied, the membrane boiling bubble 13 expands due to the inertia of the pressure obtained at timing 1. However, inside the membrane boiling foam 13, the negative pressure generated by the expansion gradually increases, and acts in the direction of contracting the membrane boiling foam 13. Eventually, the volume of the membrane boiling bubble 13 becomes maximum at the timing 2 when the inertial force and the negative pressure are balanced, and then the volume of the film boiling bubble 13 rapidly contracts due to the negative pressure.

When the film boiling bubble 13 disappears, the film boiling bubble 13 disappears not in the entire surface of the heat generating element 10 but in one or more extremely small regions. Therefore, in the heat generating element 10, a larger force is generated in the extremely small region where the film boiling bubbles 13 disappear than at the time of foaming shown in timing 1 (timing 3).

The generation, expansion, contraction, and disappearance of the film boiling bubbles 13 as described above are repeated each time a voltage pulse is applied to the heat generating element 10, and a new UFB 11 is generated each time.

Next, with reference to FIGS. 7 to 10, how UFB11 is generated in each process of generation, expansion, contraction and disappearance of the membrane boiling bubble 13 will be described in more detail.

7 (a) to 7 (d) are diagrams schematically showing how UFB 11 is generated with the generation and expansion of the membrane boiling bubbles 13. FIG. 7A shows a state before the voltage pulse is applied to the heat generating element 10. A liquid W in which the gas-dissolving liquid 3 is mixed flows inside the chamber 301.

FIG. 7B shows a state in which a voltage is applied to the heat generating element 10 and the film boiling bubbles 13 are uniformly generated in almost the entire area of the heat generating element 10 in contact with the liquid W. When a voltage is applied, the surface temperature of the heat generating element 10 rapidly rises at a rate of 10 ° C./μsec or more, and when the temperature reaches approximately 300 ° C., film boiling occurs and film boiling bubbles 13 are generated.

After that, the surface temperature of the heating element 10 rises to about 600 to 800 ° C. during the application of the pulse, and the liquid around the film boiling bubble 13 is also rapidly heated. In the figure, the region of the liquid that is located around the membrane boiling foam 13 and is rapidly heated is shown as the unfoamed high temperature region 14. The gas-dissolved liquid 3 contained in the unfoamed high-temperature region 14 precipitates beyond the thermal dissolution limit and becomes UFB. The diameter of the precipitated bubbles is about 10 nm to 100 nm, and has a high gas-liquid interface energy. Therefore, it does not disappear in a short time and floats in the liquid W while maintaining its independence. In the present embodiment, the bubbles generated by the thermal action from the generation of the film boiling bubbles 13 to the expansion are referred to as the first UFB11A.

FIG. 7C shows the process of expansion of the membrane boiling foam 13. Even after the application of the voltage pulse to the heating element 10 is completed, the film boiling foam 13 continues to expand due to the inertia of the force obtained when it is generated, and the unfoamed high temperature region 14 also moves and diffuses due to the inertia. That is, in the process of expanding the membrane boiling foam 13, the gas-dissolved liquid 3 contained in the unfoamed high-temperature region 14 is newly precipitated as bubbles to become the first UFB 11A.

FIG. 7D shows a state in which the membrane boiling foam 13 has the maximum volume. The membrane boiling foam 13 expands due to inertia, but the negative pressure inside the membrane boiling foam 13 gradually increases with the expansion, and acts as a negative pressure for contracting the membrane boiling foam 13. Then, when this negative pressure is balanced with the inertial force, the volume of the membrane boiling bubble 13 becomes maximum, and then it starts to contract.

In the contraction stage of the membrane boiling foam 13, UFB (second UFB11B) generated by the processes shown in FIGS. 8 (a) to 8 (c) and UFB generated by the processes shown in FIGS. 9 (a) to 9 (c). There is (third UFB). It is considered that these two processes coexist.

8 (a) to 8 (c) are views showing how UFB 11 is generated as the membrane boiling bubbles 13 contract. FIG. 8A shows a state in which the membrane boiling foam 13 has started contraction. Even if the membrane boiling bubble 13 starts contracting, the surrounding liquid W still has an inertial force in the expanding direction. Therefore, an inertial force acting in a direction away from the heat generating element 10 and a force acting toward the heat generating element 10 as the film boiling bubble shrinks act on the polar periphery of the film boiling bubble 13, and the pressure is reduced. Become. In the figure, such a region is shown as an unfoamed negative pressure region 15.

The gas-dissolved liquid 3 contained in the unfoamed negative pressure region 15 exceeds the pressure dissolution limit and precipitates as bubbles. The diameter of the precipitated bubbles is about 100 nm, and then the precipitated bubbles float in the liquid W while maintaining their independence without disappearing in a short time. In the present embodiment, the bubbles precipitated by the pressure action when the membrane boiling bubbles 13 contract in this way are referred to as the second UFB 11B.

FIG. 8B shows the process of contraction of the membrane boiling foam 13. The speed at which the membrane boiling foam 13 contracts is accelerated by the negative pressure, and the unfoamed negative pressure region 15 also moves with the contraction of the membrane boiling foam 13. That is, in the process of contraction of the membrane boiling foam 13, the gas-dissolved liquid 3 at the portion where the unfoamed negative pressure region 15 passes is deposited one after another to become the second UFB 11B.

FIG. 8C shows a state immediately before the film boiling bubble 13 disappears. The accelerated contraction of the membrane boiling foam 13 also increases the moving speed of the surrounding liquid W, but pressure loss occurs due to the flow path resistance in the chamber 301. As a result, the region occupied by the unfoamed negative pressure region 15 becomes larger, and a large number of second UFB 11Bs are generated.

9 (a) to 9 (c) are views showing how UFB is generated by reheating the liquid W when the membrane boiling foam 13 is contracted. FIG. 9A shows a state in which the surface of the heat generating element 10 is covered with the shrinking film boiling bubbles 13.

FIG. 9B shows a state in which the film boiling bubbles 13 are contracted and a part of the surface of the heat generating element 10 is in contact with the liquid W. At this time, heat remains on the surface of the heat generating element 10 so that the film does not boil even if the liquid W comes into contact with the surface. In the figure, the region of the liquid that is heated by coming into contact with the surface of the heat generating element 10 is shown as the unfoamed reheating region 16. Although the film does not boil, the gas-dissolved liquid 3 contained in the unfoamed reheating region 16 precipitates beyond the thermal dissolution limit. In the present embodiment, the bubbles generated by reheating the liquid W when the membrane boiling bubbles 13 contract in this way are referred to as a third UFB 11C.

FIG. 9C shows a state in which the film boiling bubbles 13 are further contracted. As the film boiling bubble 13 becomes smaller, the region of the heat generating element 10 in contact with the liquid W becomes larger, so that the third UFB 11C is generated until the film boiling bubble 13 disappears.

10 (a) and 10 (b) are diagrams showing how UFB is generated by the impact (a kind of so-called cavitation) at the time of defoaming the membrane boiling foam 13 generated by the membrane boiling. FIG. 10A shows a state immediately before the film boiling bubble 13 disappears. The membrane boiling foam 13 rapidly contracts due to the internal negative pressure, and the unfoamed negative pressure region 15 covers the periphery thereof.

FIG. 10B shows a state immediately after the film boiling bubble 13 disappears at the point P. When the membrane boiling bubble 13 is defoamed, the acoustic wave spreads concentrically starting from the point P due to the impact. Acoustic waves are a general term for elastic waves that propagate regardless of whether they are gas, liquid, or solid. In this embodiment, the density of liquid W, that is, the high-pressure surface 17A and low-pressure surface 17B of the liquid W propagate alternately. Will be done.

In this case, the gas-dissolved liquid 3 contained in the unfoamed negative pressure region 15 is resonated by the shock wave at the time of defoaming of the film boiling foam 13, and undergoes a phase transition beyond the pressure dissolution limit at the timing when the low pressure surface 17B passes. .. That is, at the same time as the film boiling bubbles 13 disappear, a large number of bubbles are precipitated in the unfoamed negative pressure region 15. In the present embodiment, the bubbles generated by the shock wave when the film boiling bubbles 13 are defoamed are referred to as the fourth UFB11D.

The fourth UFB11B generated by the shock wave at the time of defoaming the membrane boiling bubble 13 suddenly appears in an extremely narrow thin film region in an extremely short time (1 μS or less). The diameter is sufficiently smaller than the first to third UFBs, and the gas-liquid interface energy is higher than that of the first to third UFBs. Therefore, it is considered that the fourth UFB 11D has different properties from the first to third UFB 11A to 11C and produces different effects.

Further, since the fourth UFB11D is uniformly generated everywhere in the concentric spherical region where the shock wave propagates, it will be uniformly present in the chamber 301 from the time when it is generated. At the timing when the fourth UFB11D is generated, a large number of the first to third UFBs already exist, but the existence of these first to third UFBs has a great influence on the generation of the fourth UFB11D. Absent. Further, it is considered that the first to third UFBs will not disappear due to the generation of the fourth UFB11D.

As described above, it is assumed that the UFB 11 is generated at a plurality of stages until the film boiling bubbles 13 are generated and defoamed by the heat generated by the heat generating element 10. The first UFB11A, the second UFB11B and the third UFB11C are generated in the vicinity of the surface of the film boiling foam generated by the film boiling. Here, the vicinity is a region within about 20 μm from the surface of the membrane boiling foam. The fourth UFB11D is generated in the region where the shock wave generated when the bubbles are defoamed (disappeared) propagates. In the above-mentioned example, an example until the membrane boiling bubble 13 is defoamed is shown, but the method is not limited to this in order to generate UFB. For example, by communicating with the atmosphere before the generated membrane boiling bubbles 13 are defoamed, UFB can be generated even when the membrane boiling bubbles 13 are not exhausted.

Next, the residual characteristics of UFB will be described. The higher the temperature of the liquid, the lower the dissolution characteristics of the gas component, and the lower the temperature, the higher the dissolution characteristics of the gas component. That is, the higher the temperature of the liquid, the more the phase transition of the dissolved gas component is promoted, and the more easily UFB is generated. The temperature of the liquid and the solubility of the gas are in inverse proportion to each other, and as the temperature of the liquid rises, the gas exceeding the saturated solubility becomes bubbles and is deposited in the liquid.

Therefore, when the temperature of the liquid rises sharply from room temperature, the dissolution characteristics drop at once, and UFB begins to be generated. Then, as the temperature rises, the thermal melting characteristics decrease, and a large amount of UFB is generated.

On the contrary, when the temperature of the liquid drops from room temperature, the dissolution characteristics of the gas increase, and the produced UFB becomes easy to liquefy. However, such temperatures are well below room temperature. Further, even if the temperature of the liquid is lowered, since the UFB once generated has a high internal pressure and a high gas-liquid interface energy, it is extremely unlikely that a pressure high enough to destroy the gas-liquid interface acts. That is, the UFB once generated does not easily disappear as long as the liquid is stored at normal temperature and pressure.

In the present embodiment, the first UFB11A described with reference to FIGS. 7 (a) to 7 (c) and the third UFB11C described with reference to FIGS. 9 (a) to 9 (c) have thermal dissolution characteristics of such a gas. It can be said that it is a UFB generated by using.

On the other hand, regarding the relationship between the pressure of the liquid and the dissolution characteristics, the higher the pressure of the liquid, the higher the dissolution characteristics of the gas, and the lower the pressure, the lower the dissolution characteristics. That is, the lower the pressure of the liquid, the more the phase transition of the gas-dissolved liquid dissolved in the liquid to the gas is promoted, and the UFB is easily generated. When the pressure of the liquid drops from normal pressure, the dissolution characteristics drop at once and UFB begins to be generated. Then, as the pressure decreases, the pressure dissolution characteristics decrease, and a large amount of UFB is generated.

On the contrary, when the pressure of the liquid rises from the normal pressure, the dissolution property of the gas rises, and the produced UFB becomes easy to liquefy. However, such a pressure is sufficiently higher than the atmospheric pressure, and even if the pressure of the liquid rises, the UFB once generated has a high internal pressure and a high gas-liquid interface energy, so that the gas-liquid interface is destroyed. It is extremely unlikely that moderately high pressure will act. That is, the UFB once generated does not easily disappear as long as the liquid is stored at normal temperature and pressure.

In the present embodiment, the second UFB11B described with reference to FIGS. 8 (a) to 8 (c) and the fourth UFB11D described with reference to FIGS. 10 (a) to 10 (c) have such gas pressure dissolution characteristics. It can be said that it is a UFB generated by using.

In the above, the first to fourth UFBs having different generation factors have been described individually, but the above-mentioned generation factors occur simultaneously and frequently with the event of film boiling. Therefore, at least two or more types of UFBs among the first to fourth UFBs may be generated at the same time, and these generation factors may cooperate with each other to generate UFBs. However, it is common that all the generation factors are induced by the film boiling phenomenon. In the present specification, the method of producing UFB by utilizing the film boiling accompanying the rapid heat generation is referred to as a T-UFB (Thermal-Ultra Fine Bubble) production method. Further, the UFB produced by the T-UFB production method is referred to as T-UFB, and the liquid containing T-UFB produced by the T-UFB production method is referred to as a T-UFB-containing liquid.

Most of the bubbles generated by the T-UFB generation method are 1.0 um or less, and it is difficult to generate millibubbles and microbubbles. That is, according to the T-UFB generation method, UFB is produced dominantly and efficiently. Further, the T-UFB produced by the T-UFB production method has a higher gas-liquid interface energy than the UFB produced by the conventional method, and does not easily disappear as long as it is stored at normal temperature and pressure. Further, even if a new T-UFB is generated by the new film boiling, it is suppressed that the previously generated T-UFB disappears due to the impact. That is, it can be said that the number and concentration of T-UFB contained in the T-UFB-containing liquid have a hysteresis characteristic with respect to the number of times of film boiling in the T-UFB-containing liquid. In other words, the concentration of T-UFB contained in the T-UFB-containing liquid can be adjusted by controlling the number of heat-generating elements arranged in the T-UFB generation unit 300 and the number of times voltage pulses are applied to the heat-generating elements. ..

See FIG. 1 again. When the T-UFB-containing liquid W having a desired UFB concentration is generated in the T-UFB generation unit 300, the UFB-containing liquid W is supplied to the post-treatment unit 400.

11 (a) to 11 (c) are diagrams showing a configuration example of the post-processing unit 400 of the present embodiment. The post-treatment unit 400 of the present embodiment removes impurities contained in the UFB-containing liquid W in the order of inorganic ions, organic substances, and insoluble solid substances.

FIG. 11A shows a first post-treatment mechanism 410 for removing inorganic ions. The first post-treatment mechanism 410 includes an exchange container 411, a cation exchange resin 412, a liquid introduction path 413, a water collection pipe 414, and a liquid outlet path 415. The exchange container 411 contains the cation exchange resin 412. The UFB-containing liquid W generated by the T-UFB generation unit 300 is injected into the exchange container 411 via the liquid introduction path 413 and absorbed by the cation exchange resin 412, where cations as impurities are removed. To. Such impurities include a metal material peeled off from the element substrate 12 of the T-UFB generation unit 300 and the like. For example, in addition to compounds such as SiO ₂ , SiN, SiC, Ta, Al ₂ O ₃ , Ta ₂ O ₅ , amorphous alloys composed of Si, AL, W, Pt, Pd, Ta, Fe, Cr and Ni, Ir, Platinum group such as Ru can be mentioned.

The cation exchange resin 412 is a synthetic resin in which a functional group (ion exchange group) is introduced into a polymer base having a three-dimensional network structure, and the synthetic resin contains spherical particles of about 0.4 to 0.7 mm. Presented. As the polymer base, a copolymer of styrene-divinylbenzene is generally used, and as the functional group, for example, methacrylic acid type and acrylic acid type can be used. However, the above material is an example. The materials can be changed in various ways as long as the desired inorganic ions can be effectively removed. The UFB-containing liquid W absorbed by the cation exchange resin 412 and from which the inorganic ions have been removed is collected by the water collecting pipe 414 and sent to the next step via the liquid outlet path 415. In this step in the present embodiment, it is not necessary to remove all the inorganic ions contained in the UFB-containing liquid W supplied from the liquid introduction path 413, and if at least some of the inorganic ions are removed. good.

FIG. 11B shows a second post-treatment mechanism 420 for removing organic matter. The second post-treatment mechanism 420 includes a storage container 421, a filtration filter 422, a vacuum pump 423, a valve 424, a liquid introduction path 425, a liquid outlet path 426, and an air suction path 427. The inside of the storage container 421 is divided into two upper and lower regions by a filtration filter 422. The liquid introduction path 425 is connected to the upper region of the upper and lower regions, and the air suction passage 427 and the liquid outlet passage 426 are connected to the lower region. When the vacuum pump 423 is driven with the valve 424 closed, the air in the storage container 421 is discharged through the air suction path 427, the inside of the storage container 421 becomes negative pressure, and the UFB-containing liquid is discharged from the liquid introduction path 425. W is introduced. Then, the UFB-containing liquid W in a state where impurities have been removed by the filtration filter 422 is stored in the storage container 421.

Impurities removed by the filtration filter 422 include organic materials that can be mixed in tubes and units, such as organic compounds containing silicon, siloxanes, epoxies and the like. Examples of the filter membrane that can be used for the filtration filter 422 include a sub μm mesh filter that can remove even bacterial systems (a filter having a mesh diameter of 1 μm or less) and an nm mesh filter that can remove even viruses. In a filtration filter having such a fine opening diameter, bubbles larger than the opening diameter of the filter can also be removed. In particular, when fine bubbles are adsorbed on the opening (mesh) of the filter, the filter may be clogged and the filtration rate may be reduced. However, as described above, most of the bubbles generated by the T-UFB generation method described in the present invention have a diameter of 1.0 um or less, and are larger than 1.0 μm, such as millibubbles and microbubbles. Is hard to generate. That is, since the generation rate of millibubbles and microbubbles is very small, it is possible to suppress a decrease in the filtration rate due to the adsorption of bubbles on the filter. Therefore, a filtration filter 422 including a filter having a mesh diameter of 1 μm or less can be preferably applied to a system including a T-UFB generation method.

As an example of the filtration method applicable to this embodiment, there are a so-called dead-end filtration method and a cross-flow filtration method. In the dead-end filtration method, the flow direction of the supply liquid and the flow direction of the filter liquid passing through the filter opening flow in the same direction, that is, in directions along each other. On the other hand, in the cross-flow filtration method, the flow of the feed liquid flows in the direction along the filter surface, that is, the flow of the feed liquid and the flow of the filter liquid passing through the filter opening intersect. In order to suppress the adsorption of air bubbles to the filter opening, it is preferable to apply a cross-flow filtration method.

When the vacuum pump 423 is stopped and the valve 424 is opened after the UFB-containing liquid W is stored in the storage container 421 to some extent, the T-UFB-containing liquid in the storage container 421 is sent to the next step via the liquid outlet path 426. Be liquid. Here, the vacuum filtration method is adopted as a method for removing impurities of organic substances, but as a filtration method using a filter, for example, a gravity filtration method or a pressure filtration method can also be adopted.

FIG. 11C shows a third post-treatment mechanism 430 for removing insoluble solids. The third post-treatment mechanism 430 includes a settling container 431, a liquid introduction path 432, a valve 433, and a liquid outlet path 434.

First, with the valve 433 closed, a predetermined amount of UFB-containing liquid W is stored in the settling container 431 from the liquid introduction path 432 and left for a while. During this time, the solid matter contained in the UFB-containing liquid W is settled on the bottom of the settling container 431 by gravity. Further, among the bubbles contained in the UFB-containing liquid, bubbles having a relatively large size such as microbubbles also float on the liquid surface by buoyancy and are removed from the UFB-containing liquid. When the valve 433 is opened after a sufficient time has elapsed, the UFB-containing liquid W from which solid matter and large-sized bubbles have been removed is sent to the recovery unit 500 via the liquid outlet path 434. In the present embodiment, an example in which the three post-processing mechanisms are applied in order is shown, but the present invention is not limited to this, and the order of the three post-processing mechanisms may be changed, and at least one post-processing mechanism is provided as required. You may adopt it.

By including the removal treatment for removing impurities as described above in the post-treatment, the T-UFB-containing purity can be increased in the produced T-UFB-containing liquid.

See FIG. 1 again. The T-UFB-containing liquid W from which impurities have been removed by the post-treatment unit 400 may be sent to the recovery unit 500 as it is, or may be returned to the dissolution unit 200 again to form a circulation system. In the latter case, the post-treatment unit 400 is a unit that pre-treats the liquid supplied to the dissolution unit 200. Further, when the UFB-containing liquid after producing T-UFB is returned to the dissolution unit 200 again, the gas dissolution concentration of the T-UFB-containing liquid W lowered by the production of T-UFB can be increased. Preferably, the dissolution unit 200 can be replenished to the saturated state again. If a new T-UFB is then generated by the T-UFB generation unit 300, the UFB-containing concentration of the T-UFB-containing liquid can be further increased under the above-mentioned characteristics. That is, the UFB-containing concentration can be increased by the number of circulations around the dissolution unit 200, the T-UFB generation unit 300, and the post-treatment unit 400, and after the desired UFB-containing concentration is obtained, the UFB-containing liquid W Can be sent to the recovery unit 500. In this embodiment, the UFB-containing liquid treated by the post-treatment unit 400 is returned to the dissolution unit 200 and circulated. However, the present invention is not limited to this, for example, after the liquid is returned to the dissolution unit 200 and circulated a plurality of times to increase the T-UFB concentration before being supplied to the post-treatment unit 400 after passing through the T-UFB generation unit. Post-processing may be performed by the post-processing unit 400.

Here, the effect of returning the generated T-UFB-containing liquid W to the dissolution unit 200 again will be briefly described according to the verification contents specifically verified by the present inventors. First, in the T-UFB generation unit 300, 10,000 heat generating elements 10 are arranged on the element substrate 12. Industrial pure water was used as the liquid W, and the liquid W was allowed to flow in the chamber 301 of the T-UFB generation unit 300 at a flow velocity of 1.0 liter / hour. In this state, a voltage pulse having a voltage of 24 V and a pulse width of 1.0 μs was applied to each heat generating element at a drive frequency of 10 KHz.

When the generated T-UFB-containing liquid W is recovered by the recovery unit 500 without returning to the dissolution unit 200, that is, when the number of circulations is one, the T-UFB-containing liquid W recovered by the recovery unit 500 may be charged. 3.6 billion UFBs were identified per 1.0 mL. On the other hand, when the operation of returning the T-UFB-containing liquid W to the dissolution unit 200 is performed 10 times, that is, when the number of circulations is 10, the T-UFB-containing liquid W recovered by the recovery unit 500 has 1. Approximately 36 billion UFBs were identified per 0 mL. That is, it was confirmed that the UFB content concentration increased substantially in proportion to the number of circulations. Regarding the number density of UFB as described above, a measuring instrument (model number SALD-7500) manufactured by Shimadzu Corporation is used to count UFB11 having a diameter of less than 1.0 μm contained in a predetermined volume of UFB-containing liquid W. Obtained.

In this way, it is possible to generate a liquid having a desired UFB concentration by circulating the liquid in this order through the dissolution unit 200, the T-UFB generation unit 300, and the post-treatment unit 400 via the circulation path. ..

The recovery unit 500 collects and stores the UFB-containing liquid W that has been sent from the post-treatment unit 400. The T-UFB-containing liquid recovered by the recovery unit 500 becomes a highly pure UFB-containing liquid from which various impurities have been removed.

In the recovery unit 500, the UFB-containing liquid W may be classified according to the size of T-UFB by performing a filtering process in several steps. Further, since the T-UFB-containing liquid W obtained by the T-UFB method is expected to have a temperature higher than room temperature, the recovery unit 500 may be provided with a cooling means. In addition, such a cooling means may be provided in a part of the post-processing unit 400.

The above is the outline of the UFB generator 1, but of course, a plurality of units as shown in the figure can be changed, and it is not necessary to prepare all of them. Depending on the type of liquid W or gas G to be used and the purpose of use of the T-UFB-containing liquid to be generated, a part of the above-mentioned units may be omitted, or another unit may be added in addition to the above-mentioned units. You may.

For example, when the gas contained in the UFB is the atmosphere, the degassing unit 100 and the dissolution unit 200 can be omitted. If the UFB is to contain a plurality of types of gases, a dissolution unit 200 may be further added. In addition, the functions of several units shown in FIG. 1 can be integrated into one unit. For example, by arranging the heat generating element 10 in the melting container 201 shown in FIGS. 3A and 3B, the melting unit 200 and the T-UFB generation unit 300 can be integrated. In this case, T-UFB containing the gas is generated while dissolving the gas in one unit.

Further, the removal unit for removing impurities as shown in FIGS. 11A to 11C may be provided as a part of the pretreatment unit upstream of the T-UFB generation unit 300, or may be provided upstream. It may be provided both downstream. When the liquid supplied to the UFB generator is tap water, rainwater, contaminated water, or the like, the liquid may contain organic or inorganic impurities. If the liquid W containing such impurities is supplied to the T-UFB generation unit 300, the heat generating element 10 may be altered or a salting out phenomenon may occur. By providing a mechanism as shown in FIGS. 11 (a) to 11 (c) upstream of the T-UFB generation unit 300, the above impurities are removed in advance, and a more pure UFB-containing liquid can be obtained. It becomes possible to generate more efficiently.

<< Modification example of post-processing unit >>
FIG. 12 shows a fourth post-processing mechanism 450 that can be added or replaced with each of the post-processing units 400 described above. The fourth post-treatment mechanism 450 is an amplification processing unit for further amplifying the T-UFB content of the T-UFB-containing liquid W by utilizing ultrasonic vibration.

The fourth post-treatment mechanism 450 includes a storage container 451, a vibration generating unit 455, a liquid introduction path 452, a valve 453, and a liquid outlet path 454. The vibration generating unit 455 includes a cable 456, a transducer 457, a booster 458, and a horn 459. The electric power supplied from the cable 456 is converted into a mechanical vibration amplitude by the transducer 457, and then amplified by the booster 458 and horned. Vibrate 459.

When operating the fourth post-treatment mechanism 450, first, the T-UFB-containing liquid W is stored in the storage container 451 via the liquid introduction path 452 with the valve 454 closed. The amount of the T-UFB-containing liquid W to be stored is such that at least the tip of the horn 459 is immersed in the T-UFB-containing liquid W. Then, in a state where the T-UFB-containing liquid W is stored and the inside of the storage container is open to the atmosphere, the vibration generating unit 455 is driven to vibrate the horn 459 immersed in the T-UFB-containing liquid W. As a result, ultrasonic vibration occurs in the T-UFB-containing liquid W in which the tip of the horn 459 is immersed, and the number of T-UFBs increases.

At this time, in order to improve efficiency, it is preferable that the vibration generating unit 455 is repeatedly driven for a predetermined time at a predetermined interval. The T-UFB content can be adjusted by changing the frequency, vibration time, and number of vibrations of the horn 459.

After repeating the vibration for a predetermined time a predetermined number of times, when the vibration generating unit 455 is stopped and the valve 453 is opened, the T-UFB-containing liquid W adjusted to a desired content concentration is recovered via the liquid lead-out path 454. The liquid is sent to 500.

Hereinafter, the contents specifically verified by the present inventors will be described using the T-UFB generation unit 300 and the post-processing unit 400 provided with the fourth post-processing mechanism 450. First, in the T-UFB generation unit 300, 10,000 heat generating elements 10 are arranged on the element substrate 12. Industrial pure water was used as the liquid W, and the liquid W was allowed to flow in the chamber 301 of the T-UFB generation unit 300 at a flow velocity of 1.0 liter / hour. In this state, a voltage pulse having a voltage of 24 V and a pulse width of 1.0 μs was applied to each heat generating element at a drive frequency of 10 KHz.

When the generated T-UFB-containing liquid W was recovered as it was by the recovery unit 500 and the UFB content concentration was confirmed, 3.6 billion UFBs per 1.0 mL were confirmed in the recovered T-UFB-containing liquid W. Was done. On the other hand, when the generated T-UFB-containing liquid W was supplied to the fourth post-treatment mechanism 450 and the operation of vibrating the horn 459 at 100 KHz and 80 W was performed 10 times for 1 second each, the recovered T-UFB was contained. In liquid W, about 7.2 billion UFBs were confirmed per 1.0 mL. That is, the UFB content concentration could be increased by applying ultrasonic vibration with the fourth post-treatment mechanism 450. The number density of UFB as described above was obtained by counting UFB11 having a diameter of less than 1.0 μm contained in a predetermined volume of UFB-containing liquid W using a measuring instrument (model number SALD-7500) manufactured by Shimadzu Corporation. ..

An example of preferable conditions for increasing UFB by applying ultrasonic vibration to the T-UFB-containing liquid W as in the present embodiment is as follows. The ultrasonic horn is inserted into the T-UFB-containing water in which the inside of the container is in communication with the atmosphere, and the horn is vibrated at 50 to 500 KHz and 50 to 100 W for 1 to 5 seconds. More preferably, this operation is repeated about 2 to 10 times. Further, when ultrasonic waves are applied through the container from the outside of the container containing the T-UFB-containing liquid, the operation of vibrating the horn at 1 to 10 MHz and 10 to 50 W while communicating with the atmosphere inside the container is performed. Apply for ~ 50 seconds. Alternatively, application for 5 to 10 seconds is repeated about 2 to 10 times.

For comparison, when industrial pure water was directly supplied to the fourth post-treatment mechanism 450 and the same ultrasonic vibration as described above was applied, UFB was hardly confirmed in the recovered liquid. That is, the fourth post-treatment mechanism 450 that applies ultrasonic vibration does not generate a new UFB in the liquid that does not contain UFB, but has a function of amplifying the number of UFB in the liquid that already contains UFB. It is a thing.

FIG. 13 shows a fifth post-processing mechanism 460 that can be added or replaced with the post-processing unit 400. The fifth post-treatment mechanism 460 is an amplification processing unit for further amplifying the T-UFB content of the T-UFB-containing liquid W by utilizing focused ultrasonic vibration (HIFU: High Intensity Focused Ultrasound).

The fifth post-treatment mechanism 460 includes a storage container 461, a vibration generating unit 465, a liquid introduction path 462, a valve 463, and a liquid outlet path 464. Further, the vibration generating unit 465 includes a cable 466, a transducer 467, and an ultrasonic probe 468. When power is supplied from the cable 466, the transducer 467 converts this power into mechanical vibration amplitude, and the ultrasonic probe 468 oscillates ultrasonic waves in the MHz band. The oscillated ultrasonic wave is focused at a position several mm to several tens of mm away from the ultrasonic probe 468, and sudden heat generation and cavitation are invited at the focused point.

Due to such sudden heat generation and cavitation, the UFB existing near the focusing point fluctuates and splits depending on the conditions. Further, when the oscillation of the ultrasonic wave from the ultrasonic probe 468 is continued, the UFB existing near the focusing point bursts, and as a result, a larger number of UFBs are generated.

After a predetermined time has elapsed after oscillating the ultrasonic wave, when the vibration generating unit 465 is stopped and the valve 463 is opened, the T-UFB-containing liquid W adjusted to the desired content concentration is routed through the liquid outlet path 464. Is sent to the recovery unit 500.

Hereinafter, the contents specifically verified by the present inventors will be described using the post-processing unit 400 provided with the T-UFB generation unit 300 and the fifth post-processing mechanism 460. First, in the T-UFB generation unit 300, 10,000 heat generating elements 10 are arranged on the element substrate 12. Industrial pure water was used as the liquid W, and the liquid W was allowed to flow in the chamber 301 of the T-UFB generation unit 300 at a flow velocity of 1.0 liter / hour. In this state, a voltage pulse having a voltage of 24 V and a pulse width of 1.0 μs was applied to each heat generating element at a drive frequency of 10 KHz.

When the generated T-UFB-containing liquid W was recovered as it was by the recovery unit 500 and the UFB content concentration was confirmed, 3.6 billion UFBs per 1.0 mL were confirmed in the recovered T-UFB-containing liquid W. Was done. On the other hand, when the generated T-UFB-containing liquid W was supplied to the fifth post-treatment mechanism 460 and ultrasonic waves were oscillated from the ultrasonic probe 468 at 3.0 MHz and 36 W for 20 seconds, the recovered T-UFB was recovered. In the containing liquid W, about 10.8 billion UFBs were confirmed per 1.0 mL. That is, the UFB content concentration could be increased by applying focused ultrasonic waves by the fifth post-treatment mechanism 460. The number density of UFB as described above was obtained by counting UFB11 having a diameter of less than 1.0 μm contained in a predetermined volume of UFB-containing liquid W using a measuring instrument (model number SALD-7500) manufactured by Shimadzu Corporation. ..

For comparison, when industrial pure water was directly supplied to the fifth post-treatment mechanism 460 and the same focused ultrasonic waves as described above were applied, UFB was hardly confirmed in the recovered liquid. That is, the fifth post-treatment mechanism 460 that applies focused ultrasonic waves does not generate new UFB in the liquid that does not contain UFB, but has a function of amplifying the number of UFB in the liquid that already contains UFB. It is a thing.

<< Liquids and gases that can be used in T-UFB-containing liquids >>
Here, the liquid W that can be used to generate the T-UFB-containing liquid will be described. Examples of the liquid W that can be used in the present embodiment include pure water, ion-exchanged water, distilled water, physiologically active water, magnetically activated water, cosmetic water, tap water, seawater, river water, water and sewage, lake water, and groundwater. Rainwater and the like can be mentioned. Further, a mixed liquid containing these liquids and the like can also be used. Further, a mixed solvent of water and a water-soluble organic solvent can also be used. The water-soluble organic solvent used in combination with water is not particularly limited, and specific examples thereof include the following. Alcohols having 1 to 4 carbon atoms such as methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, sec-butyl alcohol, and tert-butyl alcohol. Amides such as N-methyl-2-pyrrolidone, 2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone, N, N-dimethylformamide, N, N-dimethylacetamide. Ketone or keto alcohols such as acetone and diacetone alcohol. Cyclic ethers such as tetrahydrofuran and dioxane. Ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol. 1,2-Butanediol, 1,3-Butanediol, 1,4-Butanediol, 1,5-Pentanediol, 1,2-Hexanediol, 1,6-Hexanediol, 3-Methyl-1,5- Glycos such as pentandiol, diethylene glycol, triethylene glycol, and thiodiglycol. Ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, triethylene glycol monobutyl ether, etc. Lower alkyl ethers of valence alcohols. Polyalkylene glycols such as polyethylene glycol and polypropylene glycol. Triols such as glycerin, 1,2,6-hexanetriol, trimethylolpropane. These water-soluble organic solvents may be used alone or in combination of two or more.

Examples of the gas component that can be introduced in the dissolution unit 200 include hydrogen, helium, oxygen, nitrogen, methane, fluorine, neon, carbon dioxide, ozone, argon, chlorine, ethane, propane, and air. Further, it may be a mixed gas containing some of the above. Further, the dissolution unit 200 does not necessarily have to dissolve a substance in a gaseous state, and a liquid or a solid composed of a desired component may be dissolved in the liquid W. In this case, the dissolution may be natural dissolution, dissolution by applying pressure, hydration by ionization, ionization, or dissolution accompanied by a chemical reaction.

<< Effect of T-UFB generation method >>
Next, the features and effects of the T-UFB generation method described above will be described in comparison with the conventional UFB generation method. For example, in a conventional bubble generator represented by the Venturi method, a mechanical decompression structure such as a decompression nozzle is provided in a part of the flow path, and a liquid is flowed at a predetermined pressure so as to pass through the decompression structure. As a result, bubbles of various sizes are generated in the area downstream of the decompression structure.

In this case, among the generated bubbles, buoyancy acts on bubbles having a relatively large size such as millibubbles and microbubbles, so that they may eventually rise to the liquid surface and disappear. Further, UFB on which buoyancy does not act does not have such a large gas-liquid interface energy, so that it disappears together with millibubbles and microbubbles. In addition, even if the decompression structure is arranged in series and the same liquid is repeatedly flowed through the decompression structure, the number of UFBs corresponding to the number of repetitions cannot be stored for a long period of time. That is, in the UFB-containing liquid produced by the conventional UFB production method, it was difficult to maintain the UFB-containing concentration at a predetermined value for a long period of time.

On the other hand, in the T-UFB generation method of the present embodiment using film boiling, a sudden temperature change from normal temperature to about 300 ° C. and a sudden pressure change from normal pressure to about several megapascals are generated by the heat generating element. It is generated locally in the very vicinity of. The heat generating element has a quadrilateral shape having a side of several tens of μm to several hundreds of μm. Compared to the size of a conventional UFB generator, it is about 1/1 to 1/1000. Moreover, a phase transition occurs when the gas-dissolved liquid existing in the extremely thin film region on the surface of the boiling foam momentarily exceeds the thermal dissolution limit or the pressure dissolution limit (in an ultra-short time of microseconds or less). It becomes UFB and precipitates. In this case, bubbles having a relatively large size such as millibubbles and microbubbles are hardly generated, and the liquid contains UFB having a diameter of about 100 nm with extremely high purity. Further, since the T-UFB thus produced has a sufficiently high gas-liquid interface energy, it is not easily destroyed under a normal environment and can be stored for a long period of time.

In particular, in the present invention using the film boiling phenomenon in which a gas interface can be locally formed with respect to the liquid, the interface is formed on a part of the liquid existing in the vicinity of the heat generating element without affecting the entire liquid region. The region that acts thermally and pressure can be an extremely local range. As a result, the desired UFB can be stably produced. Further, by circulating the liquid and further imparting the UFB generation condition to the generated liquid, it is possible to additionally generate a new UFB with less influence on the existing UFB. As a result, a UFB liquid of a desired size and concentration can be produced relatively easily.

Furthermore, since the T-UFB production method has the above-mentioned hysteresis characteristics, the content concentration can be increased to a desired concentration while maintaining high purity. That is, according to the T-UFB production method, a UFB-containing liquid having high purity, high concentration and long-term storage can be efficiently produced.

<< Specific use of T-UFB-containing liquid >>
In general, ultrafine bubble-containing liquids have different uses depending on the type of gas contained therein. Any gas that can dissolve an amount of PPM to BPM in the liquid can be converted to UFB. As an example, it can be applied to the following applications.

-The UFB-containing liquid containing air can be suitably used for cleaning industrial, agricultural and fishery industries, medical use, etc., and for growing plants and agricultural and marine products.

-The ozone-containing UFB-containing liquid is suitable for cleaning applications such as industrial, agricultural and fishery industries, and medical applications, as well as for sterilization, sterilization, and sterilization, and for environmental purification of wastewater and contaminated soil. Can be used.

-The UFB-containing liquid containing nitrogen is suitable for cleaning applications such as industrial, agricultural and fishery industries, and medical applications, as well as for sterilization, sterilization, and sterilization, and for environmental purification of wastewater and contaminated soil. be able to.

-The UFB-containing liquid containing oxygen can be suitably used for growing plants and agricultural and marine products in addition to cleaning applications such as industrial, agricultural and fishery industries, and medical uses.

-The UFB-containing liquid containing carbon dioxide can be suitably used for purposes such as sterilization, sterilization, and sterilization, in addition to cleaning applications such as industrial, agriculture, fishery, and medical applications.

-A UFB-containing liquid containing perfluorocarbon, which is a medical gas, can be suitably used for ultrasonic diagnosis and treatment. In this way, the UFB-containing liquid can exert its effects in a wide range of fields such as medical care, pharmaceuticals, dentistry, food, industry, agriculture and fisheries.

In each application, the purity and concentration of UFB contained in the UFB-containing liquid are important in order to quickly and surely exert the effect of the UFB-containing liquid. That is, if the T-UFB production method of the present embodiment capable of producing a UFB-containing liquid having a desired concentration with high purity is used, more effects than ever can be expected in various fields. The following is a list of T-UFB production methods and applications where the T-UFB-containing liquid is expected to be suitably applicable.

(A) Use for purification of liquid-By arranging a T-UFB generation unit in a water purifier, it can be expected to enhance the water purification effect and the purification effect of the PH preparation liquid. Further, the T-UFB generation unit can be arranged in a carbonated water server or the like.

-By arranging the T-UFB generation unit in a humidifier, an aroma diffuser, a coffee maker, etc., it can be expected to improve the indoor humidifying effect, deodorizing effect, and scent diffusion effect.

・ The dissolution unit produces a UFB-containing solution in which ozone gas is dissolved, and by using this for dental treatment, burn treatment, wound care when using an endoscope, etc., medical cleaning effect and disinfection effect are improved. You can expect it to happen.

-By arranging the T-UFB generation unit in the water tank of an apartment house, it can be expected to improve the water purification effect and chlorine removal effect of drinking water stored for a long period of time.

-In the sake brewing process where high-temperature sterilization cannot be performed, such as sake, shochu, and wine, pasteurization can be performed more efficiently than before by using a T-UFB-containing liquid containing ozone and carbon dioxide. Can be expected.

-In the manufacturing process of specified health foods and foods with functional claims, by mixing UFB-containing liquids with raw materials, pasteurization treatment becomes possible, and it is possible to provide safe and functional foods without degrading the flavor. ..

-At aquaculture sites for fish and pearls, it can be expected that spawning and growth of seafood will be promoted by arranging the T-UFB production unit in the supply route of seawater and freshwater for aquaculture.

-By arranging the T-UFB generation unit in the purification process of the food storage water, it can be expected to improve the food storage state.

-By arranging the T-UFB generation unit in the decolorizer for decolorizing pool water, groundwater, etc., a higher decolorization effect can be expected.

-By using the T-UFB-containing liquid for repairing cracks in concrete members, it can be expected that the effect of repairing cracks will be improved.

-By adding T-UFB to liquid fuel of equipment (automobiles, ships, airplanes) that use liquid fuel, it can be expected to improve the energy efficiency of the fuel.

(B) Cleaning Applications In recent years, UFB-containing liquids have attracted attention as cleaning water for removing stains and the like adhering to clothing. It is expected that the detergency will be further improved by arranging the T-UFB generation unit described in the above embodiment in the washing machine and supplying the UFB-containing liquid having higher purity and excellent permeability than before to the washing layer. it can.

-By arranging the T-UFB generation unit in the bath shower or toilet bowl washing machine, it can be expected to have the effect of cleaning the human body and other organisms in general, as well as the effect of promoting the removal of stains and mold on the bathroom or toilet bowl.

-By arranging T-UFB generation units in window washers of automobiles, high-pressure washing machines for washing wall materials, car washing machines, dishwashers, food washing machines, etc., the cleaning effect of each is further improved. Can be expected.

-It can be expected that the cleaning effect will be improved by using the T-UFB-containing liquid when cleaning and servicing parts manufactured in the factory such as the deburring process after press working.

-It can be expected that the polishing effect can be improved by using the T-UFB-containing liquid as the polishing water for the wafer at the time of manufacturing the semiconductor element. Further, in the resist removing step, by using the T-UFB-containing liquid, it can be expected to promote the peeling of the resist which is difficult to peel.

-By arranging the T-UFB generation unit in the equipment for cleaning and disinfecting medical equipment such as medical robots, dental treatment equipment, and organ storage containers, the cleaning effect and disinfection effect of these equipment can be improved. You can expect it. It can also be applied to the treatment of living things.

(C) Pharmaceutical applications-By containing a T-UFB-containing solution in cosmetics, etc., it promotes penetration into subcutaneous cells and significantly reduces additives such as preservatives and surfactants that adversely affect the skin. Can be done. As a result, it is possible to provide cosmetics that are more secure and have functionality.

-By utilizing a high-concentration nanobubble preparation containing T-UFB as a contrast medium for medical examination equipment such as CT and MRI, it is possible to efficiently utilize the reflected light from X-rays and ultrasonic waves, and more detailed captured images. Can be used for initial diagnosis of malignant tumors.

・ It is an ultrasonic therapy device called HIFU (High Intensity Focused Ultrasound). By using high-concentration nanobubble water containing T-UFB, the irradiation power of ultrasonic waves can be reduced, and treatment can be performed more non-invasively. can do. In particular, it is possible to reduce damage to normal tissues.

-Using high-concentration nanobubbles containing T-UFB as seeds, phospholipids that form liposomes are modified in the negatively charged region around the bubbles, and various medical substances (DNA, RNA, etc.) are passed through the phospholipids. Can be prepared as a nanobubble preparation.

-As a treatment for pulp and dentin regeneration, when a drug containing high-concentration nanobubble water produced by T-UFB is sent into the dental canal, the drug penetrates deeply into the dentin canal due to the penetrating action of the nanobubble water and promotes the sterilization effect. Infected root canal treatment of dental pulp can be performed quickly and safely.

As described above, according to the ultrafine bubble generation method of the present invention, by providing a post-treatment unit after the T-UFB generation unit, it is possible to efficiently generate a high-purity UFB-containing liquid. ..

1 UFB generator 10 Heat generating element 11 UFB (ultra fine bubble)
300 T-UFB generation unit 400 Post-processing unit

Claims (30)

A generation step of generating an ultrafine bubble by generating heat from a heat generating element provided in the liquid and causing a film to boil at the interface between the liquid and the heat generating element.
A post-treatment step of performing a predetermined post-treatment on the ultra-fine bubble-containing liquid containing the ultra-fine bubbles generated by the production step, and
An ultrafine bubble generation method characterized by having. The ultrafine bubble generation method according to claim 1, wherein the post-treatment step includes a removal treatment for removing impurities from the ultrafine bubble-containing liquid. The ultrafine bubble generation method according to claim 2, wherein the removal treatment includes a first treatment for removing inorganic ions using a cation exchange resin. The ultrafine bubble generation method according to claim 3, wherein the inorganic ion removed by the first treatment contains a metal constituting the heat generating element. The claim is characterized in that the inorganic ion removed by the first treatment contains at least one of Si, AL, W, Pt, Pd, Ta, Fe, Cr, Ni, Ir, and Ru. The ultrafine bubble generation method according to 4. The ultrafine bubble generation method according to any one of claims 2 to 5, wherein the removal treatment includes a second treatment for removing organic substances using a filtration filter. The ultrafine bubble generation method according to claim 6, wherein the organic substance removed by the second treatment contains at least one of an organic compound containing silicon, siloxane, epoxy, and bacteria. The ultrafine bubble according to any one of claims 2 to 7, wherein the removal treatment includes a third treatment for removing the solid matter by utilizing the property of insoluble solid matter to settle. Generation method. The ultrafine bubble generation method according to any one of claims 1 to 8, wherein the post-treatment step includes an amplification treatment for amplifying the concentration of the ultrafine bubbles in the ultrafine bubble-containing liquid. .. The ultrafine bubble generation method according to claim 9, wherein the amplification process amplifies the content concentration of the ultrafine bubbles by oscillating ultrasonic waves in the ultrafine bubble-containing liquid. The ultrafine bubble generation method according to claim 9, wherein the amplification treatment amplifies the concentration of the ultrafine bubbles by applying focused ultrasonic waves to the ultrafine bubble-containing liquid. The liquid to be supplied to the production step can be hydrogen, helium, oxygen, nitrogen, methane, fluorine, neon, carbon dioxide, ozone, argon, chlorine, ethane, propane, air, or a mixed gas containing them. It also has a dissolution step to dissolve the gas,
The ultrafine bubble generation method according to any one of claims 1 to 11, wherein in the generation step, an ultrafine bubble containing a gas dissolved in the dissolution step is generated. The ultrafine bubble generation method according to any one of claims 1 to 12, wherein the generation step is performed again after the post-treatment step is performed. The ultrafine bubble generation method according to any one of claims 1 to 13, further comprising a step of recovering the ultrafine bubble-containing liquid treated in the post-treatment step. A generation means for generating ultrafine bubbles by generating heat from a heat generating element provided in a liquid to cause film boiling at the interface between the liquid and the heat generating element.
A post-treatment means for performing a predetermined post-treatment on the ultra-fine bubble-containing liquid containing the ultra-fine bubbles generated by the generation means,
An ultrafine bubble generator characterized by being equipped with. The ultrafine bubble generating apparatus according to claim 15, wherein the post-treatment means includes a removing unit for removing impurities from the ultrafine bubble-containing liquid. The ultrafine bubble generator according to claim 16, wherein the removing unit includes a first unit that removes inorganic ions using a cation exchange resin. The ultrafine bubble generator according to claim 17, wherein the inorganic ion removed by the first unit contains a metal constituting the heat generating element. The claim is characterized in that the inorganic ion removed by the first unit contains at least one of Si, AL, W, Pt, Pd, Ta, Fe, Cr, Ni, Ir, and Ru. 18. The ultrafine bubble generator according to 18. The ultrafine bubble generator according to any one of claims 16 to 19, wherein the removing unit includes a second unit that removes organic substances using a filtration filter. The ultrafine bubble generator according to claim 20, wherein the organic substance removed by the second unit contains at least one of an organic compound containing silicon, a siloxane, an epoxy, and a bacterium. The ultrafine bubble generator according to claim 20, wherein the filtration filter has a mesh diameter of 1 μm or less. The ultrafine bubble according to any one of claims 16 to 22, wherein the removal unit includes a third unit that removes the solid matter by utilizing the property of insoluble solid matter to settle. Generator. The ultrafine bubble generation according to any one of claims 15 to 23, wherein the posttreatment means includes an amplification processing unit that amplifies the concentration of the ultrafine bubbles in the ultrafine bubble-containing liquid. apparatus. The ultrafine bubble generation device according to claim 24, wherein the amplification processing unit amplifies the content concentration of the ultrafine bubbles by oscillating ultrasonic waves in the ultrafine bubble-containing liquid. The ultrafine bubble generation device according to claim 24, wherein the amplification processing unit amplifies the content concentration of the ultrafine bubbles by applying focused ultrasonic waves to the ultrafine bubble-containing liquid. The liquid to be supplied to the production means may be hydrogen, helium, oxygen, nitrogen, methane, fluorine, neon, carbon dioxide, ozone, argon, chlorine, ethane, propane, air, or a mixed gas containing them. Further equipped with a dissolving means for dissolving the gas,
The ultrafine bubble generating apparatus according to any one of claims 15 to 26, wherein the generating means generates an ultrafine bubble containing a dissolved gas inside. The ultrafine bubble generator according to any one of claims 15 to 27, further comprising a circulation path for supplying the liquid treated by the post-treatment means to the generation means. The ultrafine bubble generator according to any one of claims 15 to 28, further comprising means for recovering the ultrafine bubble-containing liquid treated by the post-treatment means. An ultrafine bubble-containing liquid containing ultrafine bubbles produced by the ultrafine bubble generation method according to any one of claims 1 to 14.

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