Method and apparatus for producing slightly acidic hypochlorous acid water

Abstract

To provide a method and apparatus for producing slightly acidic hypochlorous acid water that can be produced simply or inexpensively, achieves a high sterilization effect, and balances a sterilization effect with suppression of harmfulness.SOLUTION: There is provided a method for producing slightly acidic hypochlorous acid water containing fine bubbles by introducing a gas-liquid mixture flow containing hypochlorite salt aqueous solution and carbon dioxide gas under pressure to a fine bubble generation part, and using a turbulent disruption method, in which by adjusting the introduction pressure of the gas-liquid mixture flow to the fine bubble generation part and the supply pressure of the carbon dioxide gas, fine bubbles with a particle size distribution having predominantly a particle size of 500 [nm] or less are formed, and slightly acidic hypochlorous acid water with a pH within the range of 4.5 to 6.5 and an effective chlorine concentration adjusted within the range of 20 to 150 [ppm] is produced.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method and an apparatus for producing slightly acidic hypochlorous acid water. [Background technology]

[0002] Hypochlorous acid water (HClO) is used as a food additive (disinfectant) in fields such as food processing for cleaning and disinfection. Known methods for producing hypochlorous acid water include electrolyzing a hydrochloric acid (HCl) or sodium chloride (NaCl) aqueous solution and adding chlorine (Cl2), carbon dioxide (H2CO3), or the like to cause a reaction. Another known method is to prepare a slightly acidic hypochlorous acid aqueous solution by adjusting the pH, for example, by bubbling carbon dioxide gas into a sodium hypochlorite aqueous solution. Furthermore, a method is known in which slightly acidic hypochlorous acid water is passed through a microbubble generator to generate fine bubbles (see Patent Documents 1-4 below). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2015 / 071995 Brochure [Patent Document 2] Japanese Patent Application Laid-Open No. 2013-240742 [Patent Document 3] Japanese Patent Application Laid-Open No. 2013-017963 [Patent Document 4] Japanese Patent Publication No. 2018-202363 Summary of the Invention [Problem to be solved by the invention]

[0004] By the way, the above-mentioned conventional methods can produce slightly acidic hypochlorous acid water containing fine bubbles and can maintain the bactericidal effect for a long time. However, there are problems in that it is difficult to produce the method simply or at low cost because it requires multiple steps, such as generating fine bubbles after preparing hypochlorous acid water, generating a slightly acidic electrolyte and then mixing it with water to generate fine bubbles, or preparing a stock solution and water containing fine bubbles and then mixing them, or requiring complex manufacturing equipment.

[0005] Furthermore, in conventional methods, the concentration of particle size distribution and number concentration in the nano-size region are insufficient, and therefore the bactericidal effect of the fine bubbles is low, making it difficult to ensure high bactericidal power, and there are also problems in that it is difficult to achieve both bactericidal power and harmfulness suppression at the same time.

[0006] Therefore, the present invention solves the above problem, and its object is to provide a method and apparatus for producing slightly acidic hypochlorous acid water that can be produced easily or at low cost, can achieve a high bactericidal effect, and can achieve both a bactericidal effect and suppression of harmfulness. [Means for solving the problem]

[0007] In order to solve the above problems, the method for producing slightly acidic hypochlorous acid water according to the present invention is a method for producing slightly acidic hypochlorous acid water containing fine bubbles by introducing a gas-liquid mixed stream containing an aqueous hypochlorite solution and carbon dioxide gas into a fine bubble generating unit under pressure, and by adjusting the introduction pressure of the gas-liquid mixed stream into the fine bubble generating unit and the supply pressure of the carbon dioxide gas, fine bubbles having a particle size distribution mainly consisting of particles of 500 [nm] or less are generated, and slightly acidic hypochlorous acid water having a pH in the range of 4.5-6.5 and an effective chlorine concentration set in the range of 20-150 [ppm] is produced.

[0008] According to the present invention, a gas-liquid mixture containing an aqueous hypochlorite solution and carbon dioxide gas is introduced under pressure into a fine bubble generating section to produce slightly acidic hypochlorous acid water containing fine bubbles. This allows for continuous production through a simple process, thereby reducing production costs. Furthermore, by adjusting the introduction pressure of the gas-liquid mixture flow into the fine-bubble generating section and the supply pressure of the carbon dioxide gas, fine bubbles having a particle size distribution mainly consisting of particles of 500 nm or less can be generated, and the fine bubbles can be maintained for a long period of time. In addition, the pH adjusting and buffering effects of the carbon dioxide gas make it possible to produce slightly acidic hypochlorous acid water with a pH in the range of 4.5-6.5 and an effective chlorine concentration (residual chlorine concentration) set in the range of 20-150 ppm. At the same time, a large amount of carbon dioxide can be dissolved by the high concentration of fine bubbles, and carbon dioxide can be present at high pressure in the nano-sized fine bubbles. This means that the high bactericidal power is strengthened by the carbon dioxide gas and the fine bubbles, and the bactericidal power does not decrease even at a low effective chlorine concentration, making it possible to produce slightly acidic hypochlorous acid water with reduced harmful effects such as odor, discoloration, and corrosion.

[0009] In the present invention, the microbubble generator preferably has a turbulence-breaking microbubble generating structure that deforms bubbles (e.g., stretches them in the flow direction) as the pressurized gas-liquid mixture passes through, and then generates microbubbles by shearing the bubbles with turbulence. Using a turbulence-breaking microbubble generator makes it possible to generate high concentrations of microbubbles with a predominant particle size distribution in the nanosize range (500 nm or less). Furthermore, the microbubble generation pattern can be adjusted depending on the pressurization state (pressure of the hypochlorite aqueous solution and carbon dioxide gas) at the time of introduction, making it possible to adjust the pH and available chlorine concentration. Furthermore, minute amounts of available chlorine that escape from the aqueous solution can be easily captured and dissolved in the microbubbles, thereby further enhancing sterilization power while suppressing harmful effects. Furthermore, the high concentration of nanosize microbubbles containing carbon dioxide can further stabilize the pH and available chlorine concentration over a long period of time.

[0010] In the present invention, the fine bubbles preferably have a particle size distribution with a majority of particles of 400 nm or less. This can further improve the bactericidal effect and low toxicity, and can maintain and stabilize these properties for a longer period of time. In particular, it is desirable for the fine bubbles to have a particle size distribution in which 90% or more of the fine bubbles are in the particle size range of 10-400 nm.

[0011] In the present invention, the number concentration of the fine bubbles is 0.5 × 10 9 [cells / ml] or more, and particularly 1.0 × 10 9 The high concentration of nano-sized microbubbles allows a large amount of carbon dioxide to be dissolved, and high-pressure carbon dioxide to be present in the microbubbles, which makes it possible to enhance the sterilizing power without increasing the effective chlorine concentration.

[0012] In the present invention, the effective chlorine concentration is preferably within the range of 30-120 ppm, and more preferably within the range of 60-100 ppm. By having an effective chlorine concentration within these ranges, it is possible to further enhance the bactericidal power and further suppress harmful effects. In particular, an effective chlorine concentration of 60 ppm or more can enhance the virus inactivation effect.

[0013] In the present invention, the pressure of the gas-liquid mixed flow at the inlet of the micro-bubble generator is preferably 0.2-0.5 MPa, which allows for the generation of a high concentration of micro-bubbles mainly having a particle size in the nano-size range (500 nm or less).

[0014] In the present invention, the gas-liquid mixed flow is preferably formed by supplying carbon dioxide gas to a supply path for the hypochlorite aqueous solution. Here, the supply pressure of the carbon dioxide gas is preferably higher than the pressure of the supply path by a range of 0.02-0.10 [MPa]. By dissolving a sufficient amount of carbon dioxide gas in the aqueous solution, the pH can be maintained slightly acidic and the concentration of generated fine bubbles can be increased.

[0015] Next, the apparatus for producing slightly acidic hypochlorous acid water according to the present invention is characterized by comprising: a supply path for supplying an aqueous hypochlorite solution; a gas-liquid driving unit for supplying the aqueous hypochlorite solution in the supply path under a predetermined pressurized state; a gas supply unit for supplying carbon dioxide gas to the supply path; and a fine bubble generating unit capable of generating fine bubbles having a particle size distribution mainly consisting of particles of 500 nm or less by introducing a gas-liquid mixed flow of the aqueous hypochlorite solution and the carbon dioxide gas under pressure.

[0016] In the present invention, the gas supply unit is preferably configured to be able to adjust the supply pressure of carbon dioxide gas. By adjusting the supply pressure of carbon dioxide gas to the supply path of the hypochlorite aqueous solution, carbon dioxide gas can be supplied at an appropriate pressure corresponding to the pressure of the supply path, so that it is possible to adjust the pH and effective chlorine concentration of the hypochlorous acid water, the particle size distribution and number concentration of the microbubbles, etc.

[0017] In the present invention, it is preferable that the supply path is connected to a water supply unit that supplies water and a drug supply unit that supplies hypochlorite (undiluted solution) to the water supply unit. By supplying water and hypochlorite separately to the supply path, the concentration of the hypochlorite aqueous solution can be appropriately set. In particular, it is preferable that the water supply unit be adjustable in terms of the amount of water supplied (flow rate). It is also preferable that the drug supply unit be adjustable in terms of the amount of hypochlorite added (flow rate). Furthermore, it is preferable that the drug supply unit be configured to be able to add various additives in addition to hypochlorite.

[0018] In the present invention, the micro-bubble generating unit preferably has a turbulence destruction type micro-bubble generating structure in which bubbles are deformed by the passage of a pressurized gas-liquid mixture flow, and then the bubbles are sheared by turbulence to generate micro-bubbles. [Effects of the Invention]

[0019] According to the present invention, a method and an apparatus for producing slightly acidic hypochlorous acid water can be provided that can be easily or inexpensively produced, can achieve a high bactericidal effect, and can achieve both a bactericidal effect and suppression of harmfulness. [Brief explanation of the drawings]

[0020] [Figure 1] 1 is a schematic diagram showing the overall configuration of a manufacturing apparatus 1 according to an embodiment of a method and apparatus for manufacturing slightly acidic hypochlorous acid water according to the present invention. FIG. [Figure 2] FIG. 1 is a schematic diagram showing a manufacturing apparatus 1′ corresponding to a different overall configuration of the embodiment. [Figure 3] 1 is a schematic diagram showing a first example 1A of a manufacturing apparatus and a manufacturing method 1 according to the embodiment. FIG. [Figure 4] FIG. 10 is a schematic diagram illustrating a second example 1B of the manufacturing apparatus and a manufacturing method 2 according to the embodiment. [Figure 5] FIG. 10 is a schematic configuration diagram illustrating a third example 1C of the manufacturing apparatus and a manufacturing method 3 of the same embodiment. [Figure 6] FIG. 2 is a schematic diagram illustrating an example of the configuration of a gas supply unit according to the embodiment. [Figure 7] FIG. 2 is a schematic diagram illustrating a configuration example of a medicine supply unit according to the embodiment. [Figure 8] FIG. 1 is a schematic diagram showing a method for generating fine bubbles using a fine bubble generating device 1D. [Figure 9] FIG. 1 is a schematic diagram illustrating an example of a micro-bubble generator. [Figure 10] 1 is a graph showing the particle size distribution of fine bubbles generated by the fine bubble generator 1D. [Figure 11] Graph (a) shows the time course of the available chlorine concentration of the produced slightly acidic hypochlorous acid water, and graph (b) shows the time course of the pH. [Figure 12] (a) is an enlarged photograph showing the state of the produced slightly acidic hypochlorous acid water after 40 days, (b) is a graph showing the particle size distribution of fine bubbles in the slightly acidic hypochlorous acid water after 40 days, and (c) is an enlarged photograph showing the state of the slightly acidic hypochlorous acid water in combination with nitrogen gas after 40 days. [Figure 13] 1 is a graph showing the results of a sterilization test using Bacillus subtilis with the produced slightly acidic hypochlorous acid water. [Figure 14] FIG. 1 is an explanatory diagram showing a method for calculating the amount of discoloration in a decolorization test using slightly acidic hypochlorous acid water. [Figure 15] 1 is a graph showing the results of a decolorization test of the produced slightly acidic hypochlorous acid water. [Figure 16] 1 is a graph showing the results of a corrosion test of aluminum pieces using the produced slightly acidic hypochlorous acid water. [Figure 17] 1 is a graph showing the results of a corrosion test of iron pieces using the produced slightly acidic hypochlorous acid water. [Figure 18] 1 is a graph showing the relationship between the pH value of hypochlorous acid water and the available chlorine content. DETAILED DESCRIPTION OF THE INVENTION

[0021] Next, an embodiment of a method and apparatus for producing slightly acidic hypochlorous acid water according to the present invention will be described in detail with reference to the accompanying drawings. Before describing the embodiment according to the present invention, slightly acidic hypochlorous acid water will be described with reference to FIG.

[0022] FIG. 18 is a graph showing the relationship between the pH and the available chlorine content of hypochlorite (sodium hypochlorite) and hypochlorous acid water. Here, the available chlorine concentration (available chlorine remaining rate) is the concentration (rate) of chlorine with bactericidal activity in an aqueous solution, and is also called the available chlorine concentration. The available chlorine contained in hypochlorous acid water includes hypochlorous acid (HClO), hypochlorite ion (OCl), -), and chlorine (Cl2), which have different disinfecting powers. Hypochlorous acid (HClO) has the strongest disinfecting power and can kill spore-forming bacteria. It can also break through the outer and inner shells of viruses, just like bacteria, and destroy their genes. On the other hand, hypochlorous acid ions (OCl - ) has an odor and its bactericidal power is extremely weak, 1 / 80 that of hypochlorous acid. Chlorine (Cl2) has almost the same bactericidal power as hypochlorous acid (HClO), but is toxic. In particular, there is a risk of large amounts of chlorine gas being released from the liquid when the solution is strongly acidic.

[0023] The concentration of hypochlorous acid (HClO), the main component of hypochlorous acid water's bactericidal power, is highly dependent on the pH of the aqueous solution. The graph in Figure 18 shows the concentration of hypochlorous acid (HClO) in a sodium hypochlorite aqueous solution. Although sodium hypochlorite itself is a strong alkali, the content of hypochlorous acid (HClO) increases as the pH decreases. When the pH falls below 4.5, the content of chlorine (Cl2), a harmful substance, increases. In particular, when the pH is 3.0 or less, the content of hypochlorous acid (HClO) decreases rapidly. Therefore, by maintaining the pH within the range of 4.5-6.5, the content of hypochlorous acid (HClO), which is effective for sterilization, can be maintained high and stable. Furthermore, when the solution is discarded, the environmental impact can be reduced, and damage to waste disposal facilities can be minimized.

[0024] [Manufacturing equipment 1] FIG. 1 is a schematic diagram illustrating an example of an apparatus for producing slightly acidic hypochlorous acid water according to the present embodiment. The production apparatus 1 shown in FIG. 1 includes a circulation-type supply pipe 5. This supply pipe 5 is connected to a gas-liquid drive unit 4, which includes a fluid supply pump or the like for sending a pressurized gas-liquid mixed flow (gas-liquid two-phase flow) to a fine-bubble generator 10, and a gas supply unit 6 for pressurizing and supplying carbon dioxide gas. The gas-liquid drive unit 4, the gas supply unit 6, and the fine-bubble generator 10 (only if necessary) are controlled by a control system 20. The outlet of the fine-bubble generator 10 faces a storage unit 7, which includes a tank or the like, and this storage unit 7 initially contains an aqueous sodium hypochlorite solution. The aqueous sodium hypochlorite solution in the storage unit 7 moves along the supply pipe 5, and when pressurized carbon dioxide gas is supplied by the gas supply unit 6, it becomes a gas-liquid mixed flow and is sent to the fine-bubble generating unit of the fine-bubble generator 10.

[0025] In the manufacturing apparatus 1 of this embodiment, the supply pipe 5, which connects the gas supply unit 6, the fine bubble generator 10, and the storage unit 7 and through which the gas-liquid mixed flow circulates, adjusts the pH of the sodium hypochlorite aqueous solution by a neutralization reaction with carbon dioxide gas represented by the following formula (1), while adjusting the available chlorine concentration and generating fine bubbles. Note that hypochlorite salts other than sodium hypochlorite may be used as long as they have the same chemical properties as those described above. NaClO + H2CO3→HClO + NaHCO3…(1)

[0026] In the manufacturing apparatus 1, the supply pipe 5 forms a circulation path, and the gas-liquid mixture of aqueous solution and gas repeatedly passes through the micro-bubble generator 10, thereby increasing the concentration of micro-bubbles. The control system 20 controls the pressurization state of the gas-liquid mixture by the operating power of the gas-liquid drive unit 4 and can also control the circulation rate of the gas-liquid mixture by the operating time. The control system 20 can also adjust the supply rate of carbon dioxide by setting the supply pressure of carbon dioxide gas from the gas supply unit 6. The fluid introduction unit 11X (described later) inside the micro-bubble generator 10, together with the supply pipe 5, constitutes part of the supply path. The micro-bubble generating unit is also referred to as a micro-bubble generating structure and is the region where micro-bubbles are actually generated. Specifically, the micro-bubble generating unit 10 corresponds to the fluid diverting unit 11Y and fluid mixing unit 11Z, in which the flow path inhabitants 12 in the flow path structure 11 (described later) inside the micro-bubble generator 10 are disposed, as well as the fluid outlet 11c of the micro-bubble generator 10 and its exterior.

[0027] By operating the manufacturing apparatus 1, slightly acidic hypochlorous acid water containing fine bubbles can be produced from a hypochlorite aqueous solution. The hypochlorous acid water produced in the storage section 7 preferably has a pH in the range of 4.5-6.5 and an effective chlorine concentration of 20-150 ppm. The pH is more preferably in the range of 4.8-6.2, and the effective chlorine concentration is preferably in the range of 30-120 ppm. Here, the hypochlorous acid (HClO) production rate is preferably 95% or higher. Furthermore, by achieving an effective chlorine concentration of 60 or higher, a high level of inactivation effect against viruses can be achieved. In particular, by achieving an effective chlorine concentration in the range of 60-100 ppm, both improved sterilization power and reduced harmfulness can be achieved at a high level.

[0028] Furthermore, it is preferable that the microbubbles in the slightly acidic hypochlorous acid water have a particle size distribution mainly consisting of particles of 500 [nm] or less, and it is particularly preferable that the particle size distribution mainly consists of particles of 400 [nm] or less. More specifically, it is more preferable that the number of microbubbles included in the particle size distribution of 10-400 [nm] is 90% or more of the total. Furthermore, it is more preferable that the number concentration of such nano-sized microbubbles is 0.5 × 109 If the concentration is [number / ml] or more, the particle size distribution and number concentration of the microbubbles will have a significant effect. That is, dissolving a large amount of carbon dioxide gas under high pressure will provide high bactericidal properties, and dissolving chlorine gas will suppress harmful effects, while maintaining the microbubbles for a long period of time. As a result, the produced slightly acidic hypochlorous acid water can stably achieve both high bactericidal properties and suppress harmful effects.

[0029] In the production apparatus 1 of this embodiment, the concentration of microbubbles can be increased by producing slightly acidic hypochlorous acid water containing microbubbles while circulating the aqueous solution so that it passes through the microbubble generator 10 multiple times via the supply pipe 5. For example, when the number concentration is 1.0 × 10 9 [Number / ml] or more, especially 1.3 × 10 9 [Number / ml] or more, or 1.5 x 10 9 High values ​​of more than [number / ml] can be achieved. This allows the dissolved amount of carbon dioxide and chlorine gas to be further increased, which in addition to the base effect of hypochlorous acid (HClO), makes it possible to obtain high bactericidal properties from carbon dioxide and fine bubbles while suppressing harmful effects. Furthermore, the high concentration of fine bubbles and particle size distribution in the nano-size range make it possible to maintain stable fine bubbles over the long term and maintain efficacy.

[0030] As for the production conditions for the method for producing slightly acidic hypochlorous acid water containing fine bubbles according to this embodiment, it is generally preferable that the pressure of the gas-liquid mixed flow at the inlet (fluid inlet 11X described below) or inlet (inner inlet 11ib and outer inlet 11ob described below) of the fine bubble generator of the fine bubble generator 10 be set within the range of 0.2-0.5 [MPa] by the gas-liquid driver 4. Also, it is desirable that the supply pressure of carbon dioxide gas from the gas supply unit 6 be higher than the above pressure by 0.02-0.10 [MPa]. These details will be described later.

[0031] [Manufacturing equipment 1′] The manufacturing apparatus 1 described above is equipped with a supply pipe 5 used as a circulation path, but in this embodiment, slightly acidic hypochlorous acid water can be produced without using a circulation-type apparatus such as the one described above. Figure 2 is a schematic diagram showing the configuration of the manufacturing apparatus 1' of this embodiment. In this manufacturing apparatus 1', parts corresponding to those of the manufacturing apparatus 1 described above are assigned the same reference numerals.

[0032] In this manufacturing apparatus 1', a supply line 5 is connected to a water supply unit 2, which is an upstream portion thereof, and is connected downstream to a gas-liquid drive unit 4, such as a fluid supply pump. In the water supply unit 2, a connection point for the drug supply unit 3 is provided downstream of a water inlet through which raw water (e.g., distilled water) is introduced. From the drug supply unit 3, hypochlorites such as sodium hypochlorite and, if necessary, other additives are added to the supply line 5 downstream of the water inlet of the water supply unit 2. The drug supply unit 3 is controlled by a control unit 20 to determine whether or not to add hypochlorite or additives and to increase or decrease the amount of addition. Here, a flow meter and an aqueous solution flow controller are provided downstream of the connection point for the drug supply unit 3 in the water supply unit 2, and these set the concentration and flow rate of the hypochlorite aqueous solution, such as the sodium hypochlorite aqueous solution.

[0033] The gas-liquid drive unit 4, which is made up of a fluid supply pump, is controlled by the control unit 20 to determine whether to operate and the magnitude of its operating power, i.e., the magnitude of the supply amount of the gas-liquid mixed flow. The hypochlorite aqueous solution flows downstream in the supply pipeline 5 under pressure from the gas-liquid drive unit 4. The gas supply unit 6 is connected to a location on the supply pipeline 5 (preferably downstream of the drug supply unit 3). The gas supply unit 6 is also controlled by the control unit 20. The pressure and flow rate of the carbon dioxide gas in the gas supply unit 6 are adjusted by the control unit 20. The slightly acidic hypochlorous acid water containing fine bubbles released from the outlet of the fine-bubble generator 10 is stored in a storage unit 7, which is made up of a tank or the like.

[0034] In this way, in the manufacturing apparatus 1 'which does not form a circulation path, a gas-liquid mixture containing a hypochlorite aqueous solution and carbon dioxide gas is formed along a supply path composed of a water supply unit 2, a drug supply unit 3, a gas-liquid drive unit 4, a supply pipe 5, a gas supply unit 6, etc., and this gas-liquid mixture is introduced into the fine bubble generating unit under pressure, and slightly acidic hypochlorous acid water containing fine bubbles is released into the storage unit 7. By this continuous series of processes, slightly acidic hypochlorous acid water can be produced with a simple manufacturing apparatus 1 'and at low cost. Unlike conventional manufacturing methods, it is not necessary to connect multiple separate manufacturing parts or manage multiple processes, such as preparing slightly acidic hypochlorous water and then generating fine bubbles.

[0035] [Manufacturing Apparatus 1A and Manufacturing Method 1 of the First Embodiment] FIG. 3 is a schematic diagram showing a manufacturing apparatus 1A and a manufacturing method 1 according to a first embodiment. In this manufacturing apparatus 1A and manufacturing method 1, a drug supply unit 3 is connected to a location within a water supply unit 2 in a supply pipeline 5, and a gas-liquid drive unit (fluid supply pump) 4 is disposed downstream of the drug supply unit 3. A gas supply unit 6 is connected downstream of the gas-liquid drive unit 4, particularly to an inlet (fluid inlet 11X described below) of a fine-bubble generator 10. In particular, the location to which carbon dioxide gas is supplied by the gas supply unit 6 is not limited to the supply pipeline 5, and may be any location in the supply path where a hypochlorite aqueous solution is formed. In this embodiment, carbon dioxide gas is introduced into the inlet of the fine-bubble generator 10 separately from the hypochlorite aqueous solution. This allows the two to be mixed using separate pressure sources, or a swirling force to be applied to the hypochlorite aqueous solution by the introduction of carbon dioxide gas. This allows the generation, deformation, and destruction of bubbles within the fine-bubble generator 10 to be varied.

[0036] Unlike this embodiment, the gas supply unit 6 may be configured to be connected to the supply pipe 5 upstream of the fine-bubble generator 10 but downstream of the gas-liquid drive unit 4. Even in this case, the supply of carbon dioxide gas by the gas supply unit 6 is similar in that it is carried out near the introduction part of the fine-bubble generator 10, so that the above-mentioned effects can be obtained to some extent. Also, the arrows pointing to the gas supply unit 6 in Figures 3 and 4 indicate the function of a measuring means (such as a pressure sensor or differential pressure gauge) that detects the pressure inside the supply pipe 5 and enables the supply pressure of carbon dioxide gas to be set appropriately based on this pressure inside the pipe.

[0037] In this embodiment, the power supply power of the gas-liquid driver 4, for example, the fluid supply pump, is selected according to the water supply flow rate set in the water supply unit 2. The gas-liquid driver 4, with its power supply power selected in this manner, sets the pressurized state of the gas-liquid mixed flow introduced into the fine-bubble generator. The amount of drug introduced into the drug supply unit 3 (flow rate of the concentrate) is then adjusted according to the production conditions corresponding to the water supply flow rate. This amount affects the pH value and available chlorine concentration of the slightly acidic hypochlorous acid water. Furthermore, the supply pressure of carbon dioxide gas in the gas supply unit 6 is slightly higher than the pressure at the introduction section of the fine-bubble generator 10, but this affects the amount of dissolved carbon dioxide gas and ultimately affects the particle size distribution and number concentration of the fine bubbles.

[0038] By measuring the pH and effective chlorine concentration of the slightly acidic hypochlorous acid water contained in the storage unit 7, the pH and effective chlorine concentration of the produced slightly acidic hypochlorous acid water can be set within an optimal range by increasing or decreasing the supply pressure of carbon dioxide gas or changing the pressurized state of the gas-liquid mixed flow by the gas-liquid drive unit 4. That is, while measuring the pH and effective chlorine concentration of the slightly acidic hypochlorous acid water in the storage unit 7, the production conditions can be adjusted until the desired pH and effective chlorine concentration are obtained. It is desirable to set the amount of hypochlorite and the flow rate of the aqueous solution in advance before preparing the above production conditions. However, although the adjustment work becomes somewhat more difficult, measurements can also be performed while adjusting the concentration of hypochlorite and the flow rate of the aqueous solution.

[0039] [Manufacturing Apparatus 1B and Manufacturing Method 2 of Second Embodiment] As shown in Fig. 4, the manufacturing apparatus 1B of this embodiment differs from the manufacturing apparatus 1A in that the drug supply unit 3 is connected to the supply pipeline 5 downstream of the gas-liquid drive unit 4, but is otherwise similar to the manufacturing apparatus 1A. In this manufacturing apparatus 1B, the fluid supply pump, which is the gas-liquid drive unit 4, does not come into contact with the highly alkaline hypochlorite aqueous solution, making it easier to ensure the durability of the gas-liquid drive unit 4. Furthermore, in this manufacturing apparatus 1B, as in the manufacturing apparatus 1A, the pH and available chlorine concentration of the slightly acidic hypochlorous acid water in the storage unit 7 can be measured and the manufacturing conditions can be adjusted until the desired pH and available chlorine concentration are obtained.

[0040] [Manufacturing Apparatus 1C and Manufacturing Method 3 of the Third Embodiment] As shown in FIG. 5, the manufacturing apparatus 1C of this embodiment differs from the manufacturing apparatus 1A in that the gas supply unit 6 is connected to the supply line 5 upstream of the gas-liquid drive unit 4, but is otherwise similar to the manufacturing apparatus 1A. Here, the gas supply unit 6 is preferably connected to the supply line 5 downstream of the connection point of the drug supply unit 3. In this manufacturing apparatus 1C, after the hypochlorite aqueous solution and carbon dioxide gas are supplied, the gas-liquid mixed flow is pumped to the fine-bubble generator 10 by the gas-liquid drive unit 4, such as a fluid supply pump. This facilitates the pH adjustment effect of the carbon dioxide gas and facilitates the advancement of bubble miniaturization, further facilitating the miniaturization of bubbles in the fine-bubble generator 10. Furthermore, in this manufacturing apparatus 1C, as in the manufacturing apparatuses 1A and 1B, the pH and available chlorine concentration of the slightly acidic hypochlorous acid water in the storage unit 7 can be measured and the manufacturing conditions can be adjusted until the desired pH and available chlorine concentration are obtained.

[0041] FIG. 6 shows a specific configuration of the gas supply unit 6 used in each of the above-described embodiments. In the gas supply unit 6, a gas flow controller 6a connected to a gas source such as a gas cylinder, a pressure regulator 6b, and a check valve 6c are sequentially connected to form a gas supply path, which is then connected to the supply pipeline 5 and the inlet of the fine-bubble generator 10. A differential pressure gauge 6d is also provided to measure the differential pressure between the pressure in the supply pipeline 5 and the pressure between the gas flow controller 6a and the pressure regulator 6b. The pressure regulator 6b is adjusted so that the pressure difference indicated by the differential pressure gauge 6d becomes a desired value. Instead of the pressure regulator 6b, an automatic pressure adjustment means may be provided that automatically adjusts the differential pressure gauge 6d to a desired value.

[0042] In this embodiment, the pressure regulator 6b and the automatic pressure adjustment means are set so that the supply pressure of carbon dioxide gas is higher than the introduction pressure of the gas-liquid mixture flow sent to the fine-bubble generator 10 by the gas-liquid driver 4, and carbon dioxide gas is pressurized into the supply pipeline 5. This forms a gas-liquid mixture flow in the supply pipeline 5 and at the introduction section of the fine-bubble generator 10, ultimately generating high-concentration fine bubbles by the fine-bubble generator 10 and providing sufficient pH adjustment for the hypochlorite aqueous solution. Carbon dioxide gas has a buffering effect, so even if it is injected in excess, it will not deviate from the appropriate pH range of 4.5-6.5 to the acidic side (usually, it will not become lower than pH 5). However, even if the available chlorine concentration increases slightly, the fine bubbles maintain chlorine in a dissolved state, preventing the generation of chlorine gas or excessive toxicity. By setting the differential pressure between the internal pressure of the supply pipe 5 and the carbon dioxide gas supply pressure (injection pressure) within the range of 0.02-0.10 MPa, it is possible to set the pH adjustment and available chlorine concentration within the above ranges, and the generation of fine bubbles makes it possible to maintain the sterilization effect and harmfulness suppression effect for a long period of time. If the differential pressure is below the above range, the amount of carbon dioxide gas injected will be insufficient, making it difficult to obtain the carbon dioxide gas supply effects (pH adjustment effect, sterilization effect, etc.), and if the differential pressure is above the above range, it will affect and destabilize the generation of fine bubbles in the fine bubble generator 10, making it difficult to control the particle size distribution and concentration of the fine bubbles.

[0043] FIG. 7 shows the specific configuration of the drug supply unit 3 used in each of the above-described embodiments. The drug supply unit 3 includes a stock solution container 3a containing a stock solution of hypochlorite aqueous solution and a delivery unit 3b consisting of a metering pump (a pump that intermittently delivers a constant amount, such as a piston pump, diaphragm pump, plunger pump, or screw pump) for pushing the stock solution into the supply line 5. The delivery unit 3b is controlled to operate corresponding to the delivery amount set by the control unit 20, thereby supplying a precise amount of stock solution into the supply line 5. The drug supply unit 3 may be configured to not only deliver hypochlorite or its aqueous solution but also other additives. For example, depending on the purpose of using the hypochlorous acid water, additives such as acids, bases, salts, or combinations thereof may be added. Furthermore, when generating fine bubbles, buffers for pH control to adjust the particle size of the fine bubbles or to enhance the functionality of the slightly acidic hypochlorous acid water, or various additives commonly used in food, such as acetic acid, salts, and lactic acid, may be added.

[0044] The gas-liquid mixture flow is preferably pressurized at an inlet (fluid inlet 11X, described later) or an inlet (inner inlet 11ib and outer inlet 11ob, described later) of the micro-bubble generating section formed inside the micro-bubble generator 10 by the gas-liquid driver 4 within a pressure range of 0.2-0.5 MPa. If the pressure falls below this range, the bubbles are less likely to deform and turbulence is less likely to form due to insufficient pressure, making it difficult to generate micro-bubbles at a high concentration. Conversely, if the pressure exceeds this range, the internal state of the micro-bubble generating section becomes unstable, making it difficult to control the particle size distribution and concentration of the micro-bubbles.

[0045] The slightly acidic hypochlorous acid water containing fine bubbles produced by the production method and production apparatus of this embodiment has the following properties. First, the slightly acidic hypochlorous acid water containing fine bubbles of this embodiment preferably has a pH in the range of 4.5-6.5, and particularly preferably in the range of 4.8-6.2. As mentioned above, these ranges are regions in which the presence rate of hypochlorous acid (HClO) is high (95% or more), the bactericidal properties are high, chlorine gas is unlikely to be generated, and harmful effects such as odor and corrosion are suppressed. As mentioned above, carbon dioxide gas has a buffering effect, so even if a large amount is dissolved, the pH of the aqueous solution will not fall below 5. Even if other additives are added, there is little risk of the pH falling below 4.5, so the risk of a large amount of chlorine gas being generated can be avoided.

[0046] Furthermore, in the slightly acidic hypochlorous acid water containing fine bubbles of this embodiment, the effective chlorine concentration (effective chlorine concentration) is preferably within the range of 20-150 ppm, and particularly within the range of 30-120 ppm. Below these ranges, the bactericidal effect is likely to decrease, while above these ranges, harmfulness increases. In particular, when the effective chlorine concentration exceeds 30 ppm, sufficient bactericidal effect is achieved even against spore-forming bacteria such as Bacillus subtilis and Bacillus cereus, and when it exceeds 60 ppm, the virus inactivation effect also becomes significant. When the effective chlorine concentration exceeds 150 ppm, harmfulness becomes significant, increasing the possibility of causing discoloration, corrosion, etc. If the effective chlorine concentration is 150 ppm or less, harmfulness is reduced, if it is 120 ppm or less, harmfulness can be further suppressed, and if it is 100 ppm or less, harmfulness is negligible.

[0047] Furthermore, in the slightly acidic hypochlorous acid water containing fine bubbles of this embodiment, it is preferable that the particle size distribution of the fine bubbles is mainly in the particle size range of 500 [nm] or less, and particularly preferably in the particle size range of 400 [nm] or less. It is particularly preferable that 90% or more of the number of fine bubbles is contained within the particle size range of 10-400 [nm]. Furthermore, it is preferable that the mode diameter of the fine bubbles is within the range of 30-300 [nm], and preferably within the range of 50-150 [nm]. The presence of fine bubbles also has the effect of dissolving traces of chlorine gas released from the aqueous solution, thereby avoiding the harmful effects caused by the generation of chlorine gas and enhancing the bactericidal power based on available chlorine.

[0048] Next, the configuration and characteristics of the micro-bubble generator according to this embodiment will be described with reference to FIGS. 8 to 10. The micro-bubble generator 10 used in this embodiment is a UFB (ultra-fine bubble) generator (ultra-fine bubble generator) equipped with a turbulence destruction type micro-bubble generating section (structure) that generates micro-bubbles by deforming (stretching in the flow direction) bubbles as a pressurized gas-liquid mixture flow is introduced through the generator and then destroying the bubbles with turbulence. FIG. 9 shows a schematic configuration of this turbulence destruction type micro-bubble generator 10. As shown in FIG. 9, the micro-bubble generator 10 of this embodiment includes a flow path structure 11 that defines a flow path 11a therein and a flow path internal body 12 disposed within the flow path structure 11. The flow path structure 11 has a gas-liquid inlet 11b connected to the upstream side of a fluid introduction section 11X and a fluid outlet 11c formed downstream of a fluid mixing section 11Z. By disposing the flow path internal body 12 in the flow path 11a, an inner inlet 11ib and an outer inlet 11ob are formed on the upstream side of the flow path 11a, and an inner outlet 11ic and an outer outlet 11oc are formed on the downstream side of the flow path 11a. Furthermore, an inner branch channel 11ia running from the inner inlet 11ib to the inner outlet 11ic is formed inside the inner surface 12i of the flow path internal body 12, and an outer branch channel 11oa with a circular flow path cross section is formed around the outer surface 12o of the flow path internal body 12, running parallel to the inner branch channel 11ia and running from the outer inlet 11ob to the outer outlet 11oc.

[0049] The flow path 11a is provided with a fluid inlet 11X, which is configured on the upstream side of the flow path inhabitant 12 and into which a gas-liquid mixture fluid 10x made of gas and liquid is introduced, and an inner branch flow path 11ia into which a gas-liquid mixture fluid 10y in and the gas-liquid mixture fluid 10y in the outer branch channel 11oa out and a fluid dividing section 11Y in which the gas-liquid mixture 10y flows in parallel while being separated from the fluid flow path inhabitant 12. in and 10y out and a fluid mixing section 11Z where the gas and liquid mixtures 10z are mixed together to form a gas-liquid mixture fluid 10z.

[0050] The flow path structure 11 has a cylindrical structure in which both the upstream side of the fluid introduction section 11X and the downstream side of the fluid mixing section 11Z are closed. In the illustrated example, the flow path structure 11 is configured as a cylindrical container with a circular cross section configured with the same diameter in the flow path direction. Gas and liquid are supplied to the fluid introduction section 11X through the gas-liquid introduction port 11b. The structure and mode of the gas-liquid introduction port 11b will be described in detail later. The supply of the gas and liquid introduces a gas-liquid mixed fluid 10x into the fluid introduction section 11X. This gas-liquid mixed fluid 10x contains bubbles 10xa with a size and concentration according to the supply mode of the gas and liquid. This gas-liquid mixed fluid 10x is pressure-fed to the fluid diverting section 11Y according to the supply pressure of the gas and liquid. The supply pressure and the internal pressure of the fluid introduction section 11X are preferably higher than atmospheric pressure, desirably in the range of 2 to 10 atmospheres. In particular, a range of 3 to 5 atmospheres is realistic considering an actual supply system.

[0051] In the fluid dividing section 11Y, the flow path internal body 12 is disposed, so that the inner inlet 11ib and the outer inlet 11ob are both open on the upstream side, and therefore the gas-liquid mixture 10x flows into the inner divided flow path 11ia via the inner inlet 11ib. in and the gas-liquid mixture fluid 10y flowing into the outer branch channel 11oa through the outer inlet 11ob. out In each of the inner branch channel 11ia and the outer branch channel 11oa, it is preferable that a jet flow with a sufficient flow rate that is effective in breaking down air bubbles into fine particles is formed by the internal pressure of the fluid introduction section 11X.

[0052] The cross-sectional shape of the flow path inhabitant 12 in the radial direction along the flow path direction is a wing-like shape in which the leading edge 12a, which is the upstream edge, is convexly curved (e.g., arc-shaped) and the trailing edge 12b, which is the downstream edge, is sharply pointed. The flow path inhabitant 12 has a body of revolution structure formed when the above-described cross-sectional shape is rotated around an axis 11x extending in the flow path direction and spaced apart from the shape. However, the flow path inhabitant 12 does not necessarily have to have a strict body of revolution structure, as long as it is a cylindrical structure. By providing such a streamlined structure, the gas-liquid mixture fluid 10x can smoothly flow into the inner branch channel 11ia and the outer branch channel 11oa. Furthermore, as will be described later, when the gas-liquid mixture fluid 10x forms a swirling flow 10xb in the fluid introduction portion 11X, the propagation of the swirling flow 10xb to the downstream side is less likely to be hindered, and the swirling flow is more likely to promote the reduction of bubbles. In the illustrated example, the cross-sectional shape is streamlined, and the inner surface 12i and outer surface 12o of the flow path inclusion body 12, including the leading edge 12a, are smooth. However, in this embodiment, the above-mentioned surfaces do not necessarily have to be smooth, and may be formed as uneven surfaces that cause shearing action of bubbles.

[0053] The orientation of the cross-sectional shape is not particularly limited, but in the illustrated example, the cross-sectional shape has an inclination angle θ (angle based on the axis 11x) so as to open outward toward the downstream side of the flow path 11a. That is, the chord line connecting the leading edge 12a and the trailing edge 12b is inclined at the angle θ with respect to the flow path direction, which is the left-right direction in the figure. The inclination angle θ is preferably within a range of 3 to 30 degrees, and particularly preferably within a range of 5 to 20 degrees. As a result, as will be described later, the outflow velocity at the inner outlet 11ic can be made lower than the inflow velocity at the inner inlet 11ib of the inner branch flow path 11ia. Furthermore, due to the above-mentioned airfoil-shaped cross-section of the flow path internal body 12, the flow path cross-section is temporarily narrowed at the throat portion (restriction) 11is provided inside the narrowed portion 12s of the inner surface 12i on the upstream side of the inner branch flow path 11ia, so that the gas-liquid mixture fluid 10y flowing through the inner branch flow path 11ia inThe flow velocity of the outer branch channel 11oa is temporarily increased at the throat portion, and the pressure decreases. On the other hand, the cross-sectional area of ​​the outer branch channel 11oa initially decreases sharply, and then, due to the influence of the wing-shaped cross-section, the change in the cross-sectional area decreases or the cross-sectional area subsequently increases. By setting the inclination angle θ of the flow path internal body 12 having the wing-shaped cross-section within the above range, at least one of the inner branch channel 11ia and the outer branch channel 11oa can be configured so that the cross-sectional area of ​​the inner branch channel 11ia decreases once at the throat portions 11is and 11os along the flow path direction and then increases. In particular, by appropriately setting the wing-shaped shape and the inclination angle θ, it is possible to configure both the inner branch channel 11ia and the outer branch channel 11oa so that the cross-sectional area of ​​the inner branch channel 11ia changes along the flow path direction (branch channel structure having a throat portion).

[0054] The flow path internal body 12 is fixed by supports 12d inside the flow path constituent 11. In the illustrated example, the supports 12d are formed in a plate shape (more specifically, a thin material shape with a streamlined shape) along the flow path direction so as not to obstruct the flow of the fluid. Furthermore, by providing supports 12d at multiple locations around the flow path internal body 12 (around the axis 11x), the mounting rigidity of the flow path internal body 12 to the flow path constituent 11 can be increased.

[0055] In the inner branch channel 11ia, as described above, when the flow path cross-sectional area at the inner inlet 11ib is compared with the flow path cross-sectional area at the inner outlet 11ic, the flow path cross-sectional area at the inner inlet 11ib is relatively small, and the flow path cross-sectional area at the inner outlet 11ic is relatively large. More specifically, the flow path cross-sectional area of ​​the inner branch channel 11ia, when viewed in the flow path direction of the flow path 11a (the direction along the axis 11x), gradually decreases from the inner inlet 11ib, and after passing through the nozzle-like throat portion 11is inside the narrowed portion 12s having the smallest inner diameter of the inner surface 12i, gradually increases in a diffuser-like manner toward the inner outlet 11ic. Due to this change in the flow path cross-sectional area, the gas-liquid mixture fluid 10y in the inner branch channel 11ia inIn the inner branch channel 11ia, the flow velocity increases and the pressure decreases at the throat portion 11is. At this time, the bubbles expanded by the pressure decrease are broken down into smaller bubbles due to the high flow velocity. Thereafter, the flow velocity gradually decreases toward the inner outlet 11ic while the pressure increases, causing the bubbles to collapse. In the inner branch channel 11ia, the flow path cross-sectional area of ​​the inner outlet 11ic is larger than the flow path cross-sectional area of ​​the inner inlet 11ib, so the flow velocity at the inner outlet 11ic is smaller than initially, and the pressure is higher than initially. Here, the flow path cross-sectional area of ​​the inner branch channel 11ia gradually increases toward the flow path (downstream) over a range exceeding half of the total flow path length (approximately 80% in the illustrated example).

[0056] On the other hand, in the outer branch channel 11oa, when comparing the flow path cross-sectional area at the outer inlet 11ob and the flow path cross-sectional area at the outer outlet 11oc, the flow path cross-sectional area at the outer inlet 11ob is relatively large and the flow path cross-sectional area at the outer outlet 11oc is relatively small. The flow path cross-sectional shape of the outer branch channel 11oa is annular. When viewed along the flow path direction of the flow path 11a, the flow path cross-sectional area of ​​the outer branch channel 11oa gradually decreases from the outer inlet 11ob. Here, the flow path cross-sectional area of ​​the outer branch channel 11oa gradually decreases toward the flow path direction (downstream) over a range exceeding half of the total flow path length (approximately 65% ​​in the illustrated example). Midway through the outer branch channel 11oa, the flow path cross-sectional area almost stops decreasing or, conversely, increases slightly. If a throat section 11os similar to the throat section 11is exists, bubbles expanded by the pressure drop are broken down into smaller bubbles by the high flow rate, and then further collapsed by the pressure increase. As a whole, due to the above-described change in the cross-sectional area of ​​the flow path, the gas-liquid mixture 10y in the outer branch flow path 11oa out In the outer branch channel 11oa, the flow velocity gradually increases and the pressure gradually decreases toward the inner outlet 11ic. In the outer branch channel 11oa, the flow path cross-sectional area of ​​the outer outlet 11oc is smaller than the flow path cross-sectional area of ​​the outer inlet 11ob, so the flow velocity at the outer outlet 11oc is higher than at the beginning and the pressure is lower than at the beginning.

[0057] As mentioned above, the gas-liquid mixture 10y in and gas-liquid mixture fluid 10y outThe bubbles in the inner branch channel 11ia and the outer branch channel 11oa are subjected to shearing, pulling, crushing, etc., and are broken down into finer bubbles. In particular, if the increase in flow velocity and the decrease in pressure due to the nozzle action of the throat portions 11is and 11os become even greater, it is thought that the bubbles will be more likely to be broken down into finer bubbles. In both the inner branch channel 11ia and the outer branch channel 11oa, the branch channel shape equipped with the throat portions 11is and 11os allows the gas-liquid mixture fluid 10y to flow more easily. in ,10y out The degree to which the flow velocity increases and the pressure decreases depends on the flow path cross-sectional area As of the throat portions 11is and 11os. Generally, as the flow path cross-sectional area As of the throat portions 11is and 11os decreases, the flow velocity Vs in the throat portions 11is and 11os increases and the pressure Ps in the throat portions 11is and 11os decreases, which is thought to enhance the above-mentioned bubble atomization effect. Note that, as described above, the flow path cross-sectional area of ​​the inner branch portion 11ia increases over a large range toward the downstream side, and therefore the flow path cross-sectional area can be set large, allowing for a large difference in flow velocity and pressure between the throat portion 11is and the inner outlet 11ic, which is thought to particularly enhance the bubble atomization effect.

[0058] By reducing the flow path cross-sectional area As of the throat sections 11is and 11os, the flow velocity Vs can be increased and the pressure Ps can be reduced, creating a flow region with a large adverse pressure gradient between the throat sections 11is and 11os and the downstream flow path. By creating a large flow velocity Vs and a large adverse pressure gradient in this way, bubbles rapidly expand and are more susceptible to shearing, pulling, and crushing forces, thereby promoting bubble refinement. On the other hand, if the flow path cross-sectional area As is too small, the flow rate Qs decreases, reducing the amount of bubble-containing fluid produced. Therefore, it is preferable to set the flow path cross-sectional area As of the throat sections 11is and 11os within a range that maximizes the flow velocity Vs and ensures the required flow rate Qs, depending on conditions determined by the capacity of the gas-liquid supply system and the internal structure of the generator 10.

[0059] The gas-liquid mixture 10y split as described above in and gas-liquid mixture fluid 10y outThe gas-liquid mixture fluid 10y flows out from the inner outlet 11ic and the outer outlet 11oc and then joins in the fluid mixing section 11Z. in and gas-liquid mixture fluid 10y out It can be considered that the inner inlet 11ib and the outer inlet 11ob have almost the same velocity and pressure. Therefore, due to the difference in the change in velocity and pressure caused by the change in the cross-sectional area of ​​the flow path from the inlet to the outlet, the gas-liquid mixture fluid 10y in is a gas-liquid mixture of 10y out Therefore, in the fluid mixing section 11Z, the gas-liquid mixture fluid 10y having a velocity difference and a pressure difference is in and gas-liquid mixture fluid 10y out The convergence of the two flows forms a double-jet turbulent flow, which generates strong shear forces due to turbulent vortex motion, further reducing the size of the already-reduced bubbles 10za. The greater the velocity and pressure differences, the stronger the interference caused by the double-jet turbulence, generating vortices of various scales, further promoting the reduction of bubbles. Note that the velocity differences between the gas-liquid mixture fluids at the outlets of the multiple branch channels need only exist in a manner that results in turbulence. For example, turbulence can occur even when the flow direction at the inner outlet 11ic of the inner branch channel 11ia is simply different from the flow direction at the outer outlet 11oc of the outer branch channel 11oa.

[0060] In this embodiment, when a swirling flow 10xb of the gas-liquid mixture fluid 10xa is generated in the fluid introduction section 11X, the swirling flow propagates through the inner branch channel 11ia and the outer branch channel 11oa in the fluid distribution section 11Y, and the swirling flow also remains in the fluid mixing section 11Z. Therefore, the shearing action of these swirling flows acts on the bubbles 10xa, 10ya, and 10za, further reducing the bubbles. In this case, the swirling flow 10xb can be generated by setting the supply direction of the gas and liquid through the gas-liquid introduction port 11b to have a swirling component around the axis 11x. However, the swirling flow 10xb may also be forcibly generated by a swirling fan or the like installed in the flow channel 11a (fluid introduction section 11X). In this case, it is preferable that the cross-sectional shape of the flow path constituent 11 perpendicular to the flow path direction is circular around the axis 11x, and that the cross-sectional shape of the flow path internal body 12 is annular around the axis 11x. This makes it easier for a swirling flow to occur and for the swirling flow to propagate in the flow path direction.

[0061] Since the fluid outlet 11c is provided at the downstream end of the flow path 11a, the gas-liquid mixed fluid 10z in the fluid mixing section 11Z is discharged to the outside of the flow path constituent 11 through the fluid outlet 11c. That is, the gas-liquid mixed fluid 10z containing the bubbles 10za that have been atomized by the action of the turbulent flow described above in the fluid mixing section 11Z, which is under relatively high pressure, is ejected to the outside of the flow path constituent 11, which is under relatively low pressure, through the fluid outlet 11c. Then, due to the pressure difference between the internal pressure of the fluid mixing section 11Z and the pressure outside (downstream side) of the fluid outlet 11c, the fluid is ejected at high speed, which further breaks down the fine bubbles in the gas-liquid mixed fluid 10z, resulting in further atomization. That is, in this embodiment, the fluid outlet 11c constitutes a fluid ejection nozzle that ejects the bubbles at high speed due to the pressure difference between the inside and outside, so that the bubbles 10za in the gas-liquid mixed fluid 10z can also be further atomized at the fluid outlet 11c.

[0062] As shown in the figure, the fluid outlet 11c has an inclined surface 11d with a conical shape (frustum or inverse tapered shape) that widens from the inside to the outside of the fluid mixing section 11Z. This structure of the fluid outlet 11c that opens to the outside promotes the reduction of bubbles by suddenly releasing pressure at the fluid outlet 11c. The angle of inclination φ, which is the angle of inclination of the inclined surface 11d with respect to the axis 11x, is not particularly limited, but is preferably within the range of 15 to 75 degrees, and more preferably within the range of 25 to 65 degrees. A range of 30 to 60 degrees is even more effective. If the angle of inclination φ is too small, the reduction of bubbles is likely to be suppressed, while if the angle of inclination φ is too large, the rigidity of the opening edge is reduced. Furthermore, providing multiple fluid outlets 11c increases the flow rate. This is also effective in increasing the bubble concentration.

[0063] The above describes the general configuration of the micro-bubble generator 10 of this embodiment and the effects of this general configuration. With this configuration, this embodiment can generate micro-bubbles at a higher concentration than conventional techniques. In particular, this embodiment can generate bubbles with diameters of approximately several tens of nanometers to 1 micrometer at a higher concentration than conventional techniques. The bubble diameter is preferably in the range of 10-400 nm, and more preferably in the range of 20-380 nm, or even 40-260 nm.

[0064] Here, the length of the flow path constituent 11 along the axis 11x is preferably within a range of 2 to 4 times the length of the flow path internal body 12 along the axis 11x, or longer if size is not taken into consideration. The length of the fluid inlet section 11X and the fluid mixing section 11Z along the axis 11x is preferably 0.5 times or more the length of the flow path internal body 12 along the axis 11x. Furthermore, when the internal pressure of the generator 10 is within a range of 2 to 5 atmospheres, the diameter of the throat section 11is of the inner branch flow path 11ia and the radial gap of the throat section 11os of the outer branch flow path 11oa are preferably within a range of 1 to 4 mm, particularly preferably within a range of 1.5 to 3.5 mm, in order to increase the flow velocity at the throat section while suppressing a decrease in flow rate, as described above. Furthermore, for the same reason as above, the diameter of the narrowest opening cross section of the fluid outlet port 11c is also preferably within a range of 1 to 4 mm, particularly preferably within a range of 1.5 to 3.5 mm.

[0065] In the example shown in FIG. 9, gas and liquid are supplied together to the fluid introduction section 11X. That is, in the flow path constituent 11, a single supply port communicating with the fluid introduction section 11X is formed as the gas-liquid inlet 11b on the outer periphery on the upstream side of the flow path constituent 11. In this case, a two-phase flow of gas and liquid is supplied to the fluid introduction section 11X via the gas-liquid inlet 11b. Although the states of the liquid and gas supplied via the gas-liquid inlet 11b vary, there is an advantage that the liquid and gas can be supplied by a single supply system such as a pump. Note that in the illustrated example, the supply direction of the gas-liquid inlet 11b is set to a direction perpendicular to the axis 11x of the flow path 11a. Therefore, there is an advantage that the swirling flow 10xb can be easily formed by supplying the liquid in a direction having a pressure component around the axis 11x.

[0066] On the other hand, unlike the illustrated example, gas and liquid may be supplied separately to the fluid introduction portion 11X. In the previously described FIGS. 2, 3, and 4, the supply pipe 5 is connected axially to the fluid introduction portion 11X of the fine-bubble generator 10, while the gas supply portion 6 is connected from the outer periphery to the fluid introduction portion 11X of the fine-bubble generator 10. In such a configuration, for example, the gas / liquid introduction port 11b may be an outer periphery supply port formed on the outer periphery on the upstream side of the flow path constituent 11 and an inner periphery supply port formed on the inner periphery of the upstream end of the flow path constituent 11. The inner periphery supply port may be provided at the upstream end of the flow path constituent 11, closer to the inner periphery than the outer periphery supply port. The inner periphery supply port is preferably formed in the center opposite the axis 11x of the flow path constituent 11. However, the inner periphery supply port may be formed in an eccentric position other than the center to allow the supplied fluid to be carried by the swirling flow 10xb. By supplying liquid through one of the outer peripheral supply port and the inner peripheral supply port and supplying gas through the other supply port, gas and liquid can be introduced into the fluid introduction section 11X. In this way, the difference in supply direction can enhance the agitation effect of the gas and liquid. Furthermore, gas or liquid can be supplied at high speed toward the axis 11x (flow path direction) through the inner peripheral supply port, and a swirling flow can be formed around the axis 11x through the outer peripheral supply port. This is thought to be effective in miniaturizing bubbles in the fluid.

[0067] Alternatively, both gas and liquid may be supplied from at least one of the outer peripheral supply port and the inner peripheral supply port. For example, a gas-liquid mixture may be pumped through the supply pipe 5 using a pump or the like. Alternatively, both gas and liquid may be supplied from both supply ports. This allows gas and liquid to be introduced into the fluid introduction portion 11X. This allows the gas-liquid mixture to be supplied at high speed toward the axis 11x and also allows a swirling flow of the gas-liquid mixture to be formed around the axis 11x. In this case, if the gas-liquid mixture is supplied to both supply ports, the two gas-liquid mixtures are supplied in different directions, improving the mixing state within the fluid introduction portion 11X. This is believed to be effective in miniaturizing bubbles in the fluid. Alternatively, only one of the outer peripheral supply port and the inner peripheral supply port may be formed and the gas-liquid mixture may be supplied to that port. For example, the example shown in FIG. 5, described above, shows a case in which the supply pipe 5 is connected to the inner peripheral supply port.

[0068] The flow path constituent 11 may have, as the gas-liquid inlet 11b, a liquid supply port and a gas inlet communicating with a fluid introduction section 11X constituting a part of the supply path, separately formed on the outer periphery on the upstream side of the flow path constituent 11. In this case, it is necessary to supply the liquid and gas to the liquid supply port and the gas supply port at a predetermined pressure, respectively. On the other hand, there is an advantage that the supply amounts of the liquid and the gas can be individually controlled. Furthermore, in the illustrated example, the supply directions of the liquid supply port and the gas supply port are set in a direction perpendicular to the flow path direction F of the flow path 11a. Therefore, there is also an advantage that the swirling flow 10xb can be easily formed by supplying the liquid and the gas inlet in a direction having a pressure component around the axis 11x. Note that the liquid supply port and the gas inlet may be formed in a positional relationship in which they are arranged in a direction along the axis 11x, or in a positional relationship in which they are arranged around the axis 11x.

[0069] The inside dimension (inner diameter) of the flow path structure 11 may be changed in the flow path direction, so that the flow path cross-sectional area of ​​the fluid inlet section 11X is larger than the flow path cross-sectional area of ​​the fluid branch section 11Y and the fluid mixing section 11Z located downstream thereof. In this configuration, the flow path cross-sectional area of ​​the entire flow path 11a decreases when the gas-liquid mixture fluid 10x flows from the fluid inlet section 11X to the fluid branch section 11Y, so that the gas-liquid mixture fluid 10y flowing in the inner branch flow path 11ia and the outer branch flow path 11oa in and 10y out It is believed that the flow velocity of the air bubbles increases and the turbulence in the fluid mixing section 11Z also becomes more intense, which further promotes the reduction of air bubbles into finer bubbles in the fluid mixing section 11Z.

[0070] The outer shape (outer diameter) of the flow path structure 11 may change in the flow path direction, so that the flow path cross-sectional area of ​​the fluid branching section 11Y decreases along the way. In this way, the flow path cross-sectional area of ​​the outer branching flow path 11oa decreases along the way, so that the flow path cross-sectional area of ​​the gas-liquid mixture fluid 10y out The flow rate of the gas-liquid mixture fluid 10y at the inner outlet 11ic increases along the way. in Since the difference in flow velocity at the outer outlet 11oc with respect to the flow velocity at the inner outlet 11z becomes larger, it is considered that the reduction in size of bubbles in the fluid mixing section 11Z is further promoted.

[0071] The outer shape (outer diameter) of the flow path structure 11 may change in the flow path direction, so that the flow path cross-sectional area of ​​the fluid mixing section 11Z may decrease along the way. In this way, the gas-liquid mixture fluid 10y flowing in from the outer outlet 11oc of the outer branch flow path 11oa out The flow rate of the gas-liquid mixture fluid 10y increases inside the fluid mixing section 11Z. out The flow direction in the fluid mixing section 11Z is also shifted inward, so that the gas-liquid mixture fluid 10y flowing in from the inner outlet 11ic of the inner branch channel 11ia in This further enhances the entrainment of bubbles in the fluid mixing section 11Z.

[0072] A plurality of fluid outlets 11c may be provided at the downstream end of the flow path structure 11. That is, by providing a plurality of ejection nozzles for ejecting the gas-liquid mixture fluid 10z from the fluid mixing section 11Z, it is believed that the manner in which the bubbles generated during ejection are atomized changes. By providing a plurality of fluid outlets 11c, it is possible to increase the flow rate of the gas-liquid mixture fluid being ejected. However, if the internal pressure of the fine-bubble generator 10 decreases, the high-speed ejection action of the fluid due to the release of the pressure described above changes, and the manner in which the bubbles are atomized by this ejection also changes, so it is believed that it is necessary to maintain the internal pressure.

[0073] As shown in Figure 8, a supply line 5 connected to a gas-liquid driver 4 (fluid supply pump) that supplies gas and liquid to the above-mentioned micro-bubble generator 10 is connected to a storage unit (tank) 7 that stores water (pure water), and gas or additives are supplied by a gas supply unit 6 to the fluid introduction unit 11X of the micro-bubble generator 10 or the supply line 5 upstream thereof, thereby configuring a micro-bubble generator 1D that can produce water containing micro-bubbles in the storage unit 7. Here, a control system 20 controls the gas-liquid driver 4, the gas supply unit 6, and the micro-bubble generator 10 (only when necessary).

[0074] In the above-described fine-bubble generator 1D, a two-phase flow of gas and liquid can be supplied at a predetermined pressure by the fluid supply pump 2. At this time, the ratio of gas to liquid can be adjusted by controlling the gas supply unit 6 (which may be a gas introduction valve provided in the fluid supply pump 2). Furthermore, when the gas and liquid are supplied separately as described above, pumps and adjustment valves for supplying the gas and liquid separately can be provided.

[0075] As shown in the figure, it is preferable to circulate the fluid contained in the container 7 back to the gas-liquid driver 4 through the supply pipe 5. In this way, the fluid in the container 7, in which microbubbles have already been formed, can be introduced again into the microbubble generator 10, and by repeatedly passing the fluid through the microbubble generator 10, the bubble concentration in the fluid can be further increased.

[0076] FIG. 10 shows the results of comparing the particle size profiles of microbubbles obtained by the microbubble generator 1D. Sample 1 shows the results of a first test in which bubbles were generated by the microbubble generator 1D having the overall configuration shown in FIG. 8 using a microbubble generator 10 having the basic configuration shown in FIG. 9 as the gas / liquid inlet 11b of the fluid introduction section 11X, a flow path structure 11 with a uniform cross-section in the flow path direction, and a single fluid outlet 11c. The opening angle φ was 30°. Sample 2 shows the results of a second test in which bubbles were generated by the microbubble generator 10 having the same overall configuration as the first test in which bubbles were generated. The opening angle φ was 30°. Sample 3 shows the results of a third test in which bubbles were generated by the microbubble generator 1D having the overall configuration shown in FIG. 8 using a microbubble generator 10 having the same overall configuration as the first test in which bubbles were generated by the microbubble generator 1D having the overall configuration shown in FIG. 8 but with four fluid outlets 11c. The opening angle φ is 60 degrees.

[0077] In the first to third test examples, distilled water was used. The sample fluid was obtained by operating the micro-bubble generator 1D, having the overall configuration shown in FIG. 8, for a time equivalent to circulating the fluid in the accommodation unit 7 three times through the supply pipe 5. The supply pressure of the gas-liquid mixture fluid supplied to the gas-liquid inlet 11b was adjusted to maintain the internal pressure of the generator 10 within a range of 4 to 5 atmospheres. The diameters of the throat section 11is and the gap between the throat section 11os in each example were both between 2 and 3 mm, and the minimum diameter of the fluid outlet 11b was also set to a value between 2 and 3 mm. Furthermore, in each of the test examples, the length of the flow path structure 11 along the axis 11x was three times that of the flow path internal body 12, and the lengths of the fluid inlet 11X and the fluid mixing section 11Z along the axis 11x were set to be equal to each other. Then, five days after the microbubbles were generated, the bubble diameter and bubble concentration were measured using a particle tracking method (particle trajectory analysis (PTA)). Figure 10 shows Samples 1-3 as the results of each test example. The particle size distribution shown is the result of aggregation over a 30 nm aggregation width, with Sample 1 shown as a solid line, Sample 2 as a dashed line, and Sample 3 as a dotted line.

[0078] As shown in Figure 10, Samples 1-3 of the above test examples all generated fine bubbles with a particle size distribution centered around 10-400 nm in diameter. Furthermore, the bubble concentration of Samples 1-3 was greater than 1.5 billion, significantly exceeding conventional values. Furthermore, the bubble size distribution of each example was primarily in the 5-500 nm range, with a further concentration in the 20-380 nm range. In particular, a high bubble concentration was observed in the 40-260 nm range. Thus, Samples 1-3 showed a high concentration of bubbles centered around a bubble size of 100 nm, demonstrating the efficient generation of high-quality fine bubbles (nanobubbles). In particular, Sample 3 of the third test example showed an extremely small variance in the bubble size distribution, with an extremely high concentration centered around 100 nm. As described above, in each of Samples 1-3, it was possible to significantly increase the bubble concentration compared to conventional technology, and to generate high-quality fine bubbles concentrated in a specific bubble diameter. In all test examples, the diameter of the fine bubbles had a particle size distribution with a majority of particles of 500 nm or less. In particular, it can be said that Samples 1-3 all had a particle size distribution with a majority of particles of 400 nm or less.

[0079] Furthermore, the flow rate during the generation of microbubbles was 8.0 [l / min] in the first test example, 12.0 [l / min] in the second test example, and 12.5 [l / min] in the third test example, all of which were larger flow rates than conventional technology. Therefore, in each test example, it can be seen that bubbles can be generated efficiently with low running costs. Furthermore, the number concentration of microbubbles was 1.30 x 10 in the first test example. 9 [cells / ml], 1.53 × 10 in the second test example 9 [cells / ml], 1.56 × 10 in the third test example 9 The dispersion as particle size distribution was the largest in the first test example, followed by the second and third test examples. However, in all cases, the maximum particle concentration (approximately 1.7 × 10) was in the particle size range of 90-120 nm, around 100 nm. 7The particle size distribution showed a high concentration (mode diameter of 105 nm).

[0080] The zeta potential of the microbubbles generated in each test example was measured. Here, the zeta potential was measured by microscopic electrophoresis. This zeta potential is defined as the potential of the slip plane where fluid flow begins in the electric double layer formed around the microparticles in the solution. When the absolute value of the zeta potential is low, the microparticles become unstable and tend to aggregate, whereas when the absolute value of the zeta potential is high, the microparticles become stable and tend to remain dispersed. While the zeta potential of microbubbles in conventional technology is generally around -50 mV, Samples 1 to 3 in each test example all achieved a zeta potential of around -100 mV. This demonstrates that the microbubbles generated in each example have significantly higher stability than conventional ones.

[0081] It has been confirmed that the nano-sized fine bubbles generated from the gas-liquid mixed stream containing water and gas obtained by the above-described fine bubble generator 1D have essentially the same particle size distribution and number concentration as those from the gas-liquid mixed stream of hypochlorite aqueous solution and carbon dioxide gas according to this embodiment. The particle size distribution and number concentration of these fine functions can be adjusted by the introduction pressure of the gas-liquid mixed stream into the fine bubble generating unit and the supply pressure of the gas to the supply path. However, the specific state of the fine bubbles is determined by the fine bubble generating structure of the fine bubble generating unit. In addition to the above factors, the pH value and effective chlorine concentration of the hypochlorous acid water are affected by the concentration and flow rate of the original hypochlorite aqueous solution. As for the fine bubble generating structure, as described above, a turbulence destruction type fine bubble generating structure is preferred, which generates fine bubbles by deforming the bubbles by passing them through the gas-liquid mixed stream and then destroying the bubbles with the generated turbulence. The particle size distribution of the microbubbles is preferably a particle size distribution mainly consisting of particles of 500 [nm] or less, and more preferably a particle size distribution mainly consisting of particles of 400 [nm] or less. In particular, it is preferable that the number of microbubbles in the range of 10-400 [nm] is 90% or more (preferably 95% or more) of the total. The number concentration of microbubbles is 0.5 x 10 9 [cells / ml] or more is preferable, and 1.0 × 10 9 It is desirable that the number of cells is 1.30 × 10 9 If a particle concentration exceeding [particles / ml] can be obtained, extremely high bactericidal power can be achieved through the action of high-pressure carbon dioxide gas.

[0082] Next, the test results of the slightly acidic hypochlorous acid water containing fine bubbles produced by the manufacturing method and manufacturing apparatus of this embodiment will be compared with ordinary slightly acidic hypochlorous acid water (normal carbonated hypochlorous acid water), etc. First, Figure 11 shows the test samples, which are slightly acidic hypochlorous acid water without fine bubbles produced only by adjusting the pH of sodium hypochlorite (sample 1: normal carbonated hypochlorous acid water), slightly acidic hypochlorous acid water containing fine bubbles produced by the manufacturing apparatus 1A shown in Figure 3 (sample 2: carbonated UFB hypochlorous acid water), and slightly acidic hypochlorous acid water containing fine bubbles produced by mixing and supplying nitrogen with carbon dioxide gas using the gas supply unit 6 in the same manufacturing apparatus 1A (sample 3: carbonated UFB hypochlorous acid water + nitrogen), and the time transition of the effective chlorine concentration (a) and the time transition of the pH value (b) of each test sample were measured.

[0083] As shown in Figure 11, each sample maintained extremely stable quality and sufficient bactericidal properties over a long period of 90 days, with no problems with pH or chlorine concentration. Figure 12 shows a micrograph (a) and particle size profile (b) of the fine bubbles of Sample 2 40 days after production, and a micrograph (c) of the fine bubbles of Sample 3 40 days after production. It can be seen that neither Sample 2 nor Sample 3 had any problems with particle size or concentration, even after 40 days, and maintained a high concentration of fine bubbles in the nano-particle size range for a long period of time.

[0084] Next, FIG. 13 shows the results of a disinfection test of Bacillus subtilis for each of Samples 1 to 4, in which slightly acidic hypochlorous acid water containing fine bubbles (Sample 4: carbonated UFB hypochlorous acid water + acetic acid) was added, which was produced by mixing hypochlorite with acetic acid and supplying it using the drug supply unit 3 in the same manufacturing apparatus 1A as described above. Table 1 below shows the pH value and effective chlorine concentration of each sample tested. Specifically, the results were obtained by adding Bacillus subtilis spore solution (manufactured by Eiken Chemical Co., Ltd., 1.2 x 10 7Using a 1000-kJ / ml (CFU / ml), 4.5 ml of each sample was transferred to a sterile centrifuge tube, and 0.5 ml of test bacteria solution was added and mixed. After a predetermined time had passed, 0.02 ml of 1 M sodium thiosulfate solution was added to make a sample solution, and 1 ml of the sample solution was placed in a sterile petri dish and the viable bacterial count was measured using the agar pour plate method (SCDLP agar medium, cultured at 35°C for 48 hours).

[0085] [Table 1]

[0086] According to FIG. 13, when the sample 1 is contacted with the slightly acidic hypochlorous acid water, the viable cell count of Bacillus subtilis slowly decreases over time, whereas when the sample 2-4 is contacted with the slightly acidic hypochlorous acid water, the viable cell count of Bacillus subtilis decreases several minutes faster. In particular, the slightly acidic hypochlorous acid water of the present embodiment, sample 2, has a pH value equivalent to that of sample 1, and although the effective chlorine concentration is lower than that of sample 1, it can be seen that the bactericidal activity is greatly improved. This is thought to be because the slightly acidic hypochlorous acid water of the present embodiment contains a high concentration of fine bubbles in the nanoparticle size range. Note that Bacillus subtilis is a so-called spore-forming bacterium and has extremely high resistance, but all of samples 2-4 of the present embodiment exhibited high bactericidal activity.

[0087] Next, we tested the bactericidal activity against the novel coronavirus (SARS-CoV-2). We used a virus strain (isolated from human origin) that was isolated from saliva and cultured using Vero cells, and then confirmed the amplification of the SARS-CoV-2 gene using real-time PCR (Ministry of Health, Labour and Welfare notification method). Here, the cultured cells were Vero cells (a cell line derived from the kidney epithelium of African green monkeys), and fetal bovine serum was added to make a 5% virus solution.

[0088] Phosphate buffer solution was used as a comparison. Test material 1 was a slightly acidic hypochlorous acid water containing fine bubbles produced by the above-mentioned production apparatus 1A, with an effective chlorine concentration of 40 ppm. Test material 2 was a slightly acidic hypochlorous acid water containing fine bubbles produced by the above-mentioned production apparatus 1A, with an effective chlorine concentration of 80 ppm. One ml of the virus solution was added to 19 ml of each of the above-mentioned phosphate buffer solution (control), test material 1 (test material 1), and test material 2 (test material 2). The mixture was then allowed to stand at room temperature (25°C) for a predetermined period of time. The mixture was then serially diluted 10-fold, and 100 μl of each solution was inoculated onto cells cultured in a 96-well cell culture plate. After 5 days of incubation at 37°C under 5% carbon dioxide, the cultured cells were observed under a microscope. The presence or absence of virus was confirmed by CPE (cell degeneration) and the concentration was calculated. As a result, in test material 1, as in the control group, no change in the amount of virus was observed within 20 seconds after the start. On the other hand, in test material 2, a reduction rate of 99.99% was observed after 20 seconds. The virus infectivity was initially 10 5.5 [TCID 50 / ml], and there was no change in the control area or test area 1, but in test area 2, after 20 seconds, the 1.5 [TCID 50 / ml] or less. The reduction rate is calculated using the following formula (2): where the control group and test group in formula (2) represent the virus infectivity titer in the control group and the virus infectivity titer in the test group, respectively. Reduction rate [%] = 100 × (control group - test group) / control group … (2)

[0089] Next, we conducted a decolorization test on textiles using disinfectant solutions such as slightly acidic hypochlorous acid water. Figure 14 shows the calculation method for the discoloration amount Δr in this decolorization test. Details of the slightly acidic hypochlorous acid water and other solutions tested are shown in Table 2 below. In the test, three types of materials - polyethylene synthetic leather, felt, and genuine leather - were immersed in the following AE disinfectant solutions, and the discoloration amount Δr was calculated. The results are shown in Figure 15.

[0090] [Table 2]

[0091] According to this decolorization test, the disinfectant solution D (carbonated UFB hypochlorous acid water) of this embodiment caused little discoloration on all three of the above materials, and no decolorization effect was observed when used at a practical concentration.

[0092] Next, metal pieces of Cu, Fe, Al, Zn, Ni, and Pb were immersed in each of the disinfectant solutions AE listed in Table 2 above, and after thoroughly drying every 24 hours, the mass was measured and the corrosion rate was calculated from the mass loss and surface area. This process was repeated for about a week. 2 ] is expressed by the following equation (3). α=(m0-m n ) / 2S … (3) where m0 is the initial mass [g], m n is the mass at any time [g], S is the area of ​​the metal piece [m 2 ] is shown.

[0093] Figure 16 shows the change in corrosion rate of aluminum (Al) pieces over time, and Figure 17 shows the change in corrosion rate of iron (Fe) pieces over time. The test results for various metal pieces are shown in Table 3 below.

[0094] [Table 3]

[0095] As shown in Table 3, the disinfectant solution D (carbonated UFB hypochlorous acid water) of this embodiment is less corrosive to any metal pieces other than Fe, and exhibited low corrosiveness equivalent to that of the conventional disinfectant solution E (carbonated hypochlorous acid water).

[0096] As described above, the slightly acidic hypochlorous acid water containing fine bubbles produced by the manufacturing method and manufacturing apparatus of this embodiment is produced in a state containing fine bubbles by introducing a gas-liquid mixture containing a hypochlorite aqueous solution and carbon dioxide gas into the fine bubble generating unit under pressure, so that it can be continuously produced in a simple process, thereby reducing production costs. In addition, by adjusting the concentration of the hypochlorite aqueous solution, the introduction pressure of the gas-liquid mixture flow into the fine bubble generating unit, and the supply pressure of the carbon dioxide gas, fine bubbles having a particle size distribution mainly consisting of particles of 500 [nm] or less can be generated, and the fine bubbles can be maintained for a long period of time, and the pH adjusting action and buffering action of carbon dioxide gas can produce slightly acidic hypochlorous acid water with a pH in the range of 4.5-6.5 and an effective chlorine concentration in the range of 20-150 [ppm]. This allows a large amount of carbon dioxide gas to be dissolved in the high concentration of fine bubbles, and carbon dioxide gas can be made to exist at high pressure in the nano-sized fine bubbles, so that the high bactericidal power is strengthened by the carbon dioxide gas and the fine bubbles.Furthermore, even if the effective chlorine concentration is suppressed as in the above range, the bactericidal power does not decrease, so it is possible to obtain slightly acidic hypochlorous acid water that suppresses harmful effects such as odor, discoloration, and corrosion.

[0097] In particular, by forming high-concentration fine bubbles mainly having a particle size distribution of 10-400 [nm], carbon dioxide gas can be incorporated into slightly acidic hypochlorous acid water at high pressure. This is because the carbon dioxide gas inside nano-sized fine bubbles is highly pressurized, such as fine bubbles with a diameter of 100 [nm], which theoretically have an internal air pressure of about 30 atmospheres. Such high-pressure carbon dioxide gas is known to have high bactericidal power, such as destroying cell membranes. As described above, in this embodiment, nano-sized fine bubbles are generated at high concentrations, and the bactericidal power is enhanced by the high-pressure carbon dioxide gas contained inside the fine bubbles. Therefore, it is not necessary to set the effective chlorine concentration high as in the past. Therefore, by reducing the effective chlorine concentration and producing slightly acidic hypochlorous acid water, it is possible to suppress harmfulness while maintaining high bactericidal power.

[0098] As described in Patent Documents 1-4, the inclusion of fine bubbles in conventional hypochlorous acid water enhances its bactericidal power. When the particle size and concentration of the nano-sized region are increased as in this embodiment, the bactericidal power is increased compared to hypochlorous acid water produced by conventional methods. In this embodiment, the gas-liquid mixture flow is introduced into the fine bubble generating section under pressure, enabling continuous production despite the simple process not requiring multiple steps. As a result, production costs can be reduced, and a high concentration of nano-sized regions containing carbon dioxide is generated, resulting in high bactericidal power regardless of the effective chlorine concentration.

[0099] It should be noted that the manufacturing method and manufacturing device for slightly acidic hypochlorous acid water of the present invention are not limited to the above-mentioned illustrated examples, and can of course be variously modified within the scope of the present invention.For example, in each of the above-mentioned embodiments, a fluid supply pump is used as the gas-liquid driving unit 4, but the gas-liquid driving unit 4 can be any one that can ultimately introduce the gas-liquid mixed flow into the fine bubble generating unit under a predetermined pressurized state, and for example, can be any kind of water flow source that can send the water that is the source of hypochlorite aqueous solution into the supply path under pressurized state.

[0100] In the above embodiment, the gas supply unit 6 can supply only carbon dioxide gas, but in the present invention, other gases, for example, nitrogen, may be additionally supplied to carbon dioxide gas, or a mixture of carbon dioxide gas and other gases may be supplied. Furthermore, the aqueous hypochlorite solution may contain other additives, such as acetic acid or lactic acid. [Explanation of symbols]

[0101] 1, 1', 1A, 1B, 1C... manufacturing apparatus, 2... water supply section, 3... drug supply section, 4... gas-liquid drive section (supply pump), 5... supply pipeline, 6... gas supply section, 7... storage section (tank), 10... fine bubble generator, 10x, 10y in , 10y out10z…gas-liquid mixed fluid, 11…flow path structure, 11a…flow path, 11b…gas-liquid inlet, 11c…fluid inlet, 11d…inclined surface, 11X…fluid inlet, 11Y…fluid flow branching portion, 11Z…fluid mixing portion, 11ia…inner flow branching path, 11ib…inner flow inlet, 11ic…inner flow outlet, 11oa…outer flow branching path, 11ob…outer flow inlet, 11oc…outer flow outlet, 11is, 11os…slide portion, 12…flow path inner body, 12i…inner surface, 12o…outer surface, 12a…front edge, 12b…rear edge

Claims

1. A method for producing slightly acidic hypochlorous acid water containing fine bubbles by introducing a gas-liquid mixed flow containing a hypochlorite aqueous solution and carbon dioxide gas into a fine bubble generating section under pressure, By adjusting the introduction pressure of the gas-liquid mixed flow to the fine bubble generating unit and the supply pressure of the carbon dioxide gas, fine bubbles having a particle size distribution mainly consisting of particles of 500 nm or less are generated, and a slightly acidic hypochlorous acid water having a pH in the range of 4.5 to 6.5 and an effective chlorine concentration in the range of 20 to 150 ppm is produced. This method for producing slightly acidic hypochlorous acid water is characterized by:

2. The micro-bubble generating unit has a turbulence destruction type micro-bubble generating structure in which the gas-liquid mixture flow introduced under pressure passes through to deform the bubbles, and then destroys the bubbles with turbulence to generate micro-bubbles. The method for producing slightly acidic hypochlorous acid water according to claim 1.

3. The fine bubbles have a particle size distribution mainly consisting of particles of 400 nm or less. The method for producing slightly acidic hypochlorous acid water according to claim 1 or 2.

4. The fine bubbles have a particle size distribution in which 90% or more of the fine bubbles are in the particle size range of 10-400 nm. The method for producing slightly acidic hypochlorous acid water according to claim 3.

5. The number concentration of the fine bubbles is 0.5×10 ９ [pieces / ml] or more, The method for producing slightly acidic hypochlorous acid water according to claim 4.

6. The effective chlorine concentration is within the range of 30-120 ppm. The method for producing slightly acidic hypochlorous water according to claim 1.

7. The pressure of the gas-liquid mixed flow at the introduction part of the fine bubble generating part is 0.2-0.5 [MPa]. The method for producing slightly acidic hypochlorous acid water according to claim 2.

8. The gas-liquid mixed flow is formed by supplying carbon dioxide gas to a supply path for the hypochlorite aqueous solution. The method for producing slightly acidic hypochlorous acid water according to claim 1 or 2.

9. The supply pressure of the carbon dioxide gas is higher than the pressure of the supply path by 0.02-0.10 [MPa]. The method for producing slightly acidic chlorous acid water according to claim 8.

10. a supply path for supplying an aqueous hypochlorite solution; a gas-liquid driving unit that supplies the hypochlorite aqueous solution in the supply path under a predetermined pressurized state; a gas supply unit that supplies carbon dioxide gas to the supply path; A fine bubble generating unit capable of generating fine bubbles having a particle size distribution mainly consisting of particle sizes of 500 [nm] or less by introducing a gas-liquid mixed flow of the hypochlorite aqueous solution and the carbon dioxide gas in a pressurized state; An apparatus for producing slightly acidic hypochlorous acid water, comprising:

11. The gas supply unit is configured to be able to adjust the supply pressure of carbon dioxide gas. The apparatus for producing slightly acidic hypochlorous acid water according to claim 10.

12. A water supply unit that supplies water and a drug supply unit that supplies hypochlorite to the water supply unit are connected to the supply path. The apparatus for producing slightly acidic hypochlorous acid water according to claim 10 or 11.

13. The micro-bubble generating unit has a turbulence destruction type micro-bubble generating structure in which a pressurized gas-liquid mixture flow passes through the micro-bubble generating unit to deform the bubbles, and then the bubbles are destroyed by turbulence to generate micro-bubbles. The apparatus for producing slightly acidic hypochlorous acid water according to claim 10 or 11.

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