Plasma sterilizing water generator

Abstract

To provide a plasma sterilization water generator for generating plasma sterilization water having high sterilization effect.SOLUTION: A plasma sterilized water generator includes: a cooling mechanism 2 for precooling supplied water 11 to a predetermined temperature; a plasma treatment unit 3 for storing the water 11 and configured to be capable of decompression; a decompression pump 31a for decompressing gas phase atmosphere so that the inside of the plasma treatment unit 3 becomes extremely low vacuum; a planar electrode 33a disposed so as to be positioned above the water surface of the water 11 stored in the plasma treatment unit 3; a dielectric body 34 disposed at an undersurface side of the planar electrode 33a and facing the water surface of the water 11 stored in the plasma treatment unit 3 via a space; a grounding electrode 33b disposed so as to be positioned in the water 11 stored in the plasma treatment unit 3; and a power source 35 that applies AC voltage to the electrode 33a.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a plasma sterilized water generating device that generates plasma sterilized water used for sterilizing a target object. [Background technology]

[0002] As the global spread of the novel coronavirus continues for a long time, it has become common to disinfect hands and surfaces of objects that people have touched. Hypochlorous acid water-based disinfectants and alcohol-based disinfectants have been widely used to disinfect hands and objects. However, problems have arisen with rough hands caused by the chlorine component and the degreasing effect of alcohol. Other functional waters with disinfecting power include electrolytic water and ozone water. However, when ozone water is used, problems such as odors caused by residual components and corrosion of surrounding materials have arisen.

[0003] In light of this background, in recent years, a sterilization method using discharge plasma has been proposed as a sterilization method that does not use chemical solutions. This method sterilizes by using the oxidizing power of highly reactive chemically active species and ions generated by discharge plasma. Since a high sterilization effect can be obtained using only electrical energy and there is no residual effect as with methods that use chemical solutions, it is applied in various fields. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 1999-187872 A [Patent Document 2] JP 2001-252665 A Summary of the Invention [Problem to be solved by the invention]

[0005] As described above, in recent years, problems such as rough hands caused by disinfectants and decay caused by residual components of disinfectants have become a problem, and there has been a growing demand for safe plasma disinfectant water to disinfect hands and surfaces of objects that people have touched. However, no plasma disinfectant water generator suitable for disinfecting hands and surfaces of objects has yet been proposed, and its development has been eagerly awaited.

[0006] The present invention has been proposed to solve the problems of the prior art as described above. The object of the present invention is to provide a plasma sterilized water generating device that generates plasma sterilized water having a high sterilization effect. [Means for solving the problem]

[0007] In order to achieve the above object, the plasma sterilized water generating apparatus of the present invention has the following features. (1) a cooling mechanism for pre-cooling supplied water to a predetermined temperature; The pre-cooled cooling medium is supplied from the cooling mechanism. The plasma processing apparatus includes: a plasma processing unit configured to store water and to be capable of reducing pressure; a pressure reducing pump that reduces the pressure of a gas phase atmosphere so that the inside of the plasma processing unit is an extremely low vacuum; a flat electrode provided so as to be located above the surface of the water stored in the plasma processing unit; a dielectric provided on the lower surface side of the flat electrode and facing the surface of the water stored in the plasma processing unit across a space; a ground electrode provided so as to be located in the water stored in the plasma processing unit; and a power source that applies an AC voltage to the electrode. The amount of water to be plasma-treated in the plasma treatment section is 50 mL or less. .

[0008] (2) The cooling device may be configured to include a raw water cartridge for storing the water, and the water may be supplied from the raw water cartridge to the cooling device.

[0009] (3) The cooling mechanism may be configured to include a cooling tank for storing the supplied water and a cooling device for cooling the cooling tank, and the water pre-cooled to a predetermined temperature in the cooling tank may be introduced into the plasma processing unit.

[0010] (4) The cooling mechanism may be configured to include a liquid-cooled jacket through which the supplied water flows and a Peltier element that cools the liquid-cooled jacket, and the water that has been pre-cooled to a predetermined temperature in the liquid-cooled jacket is introduced into the plasma processing unit.

[0011] (5) The cooling mechanism may pre-cool the water to be plasma-treated in the plasma treatment unit so that the temperature of the water is 15° C. or lower.

[0013] ( 6 ) The plasma processing unit may be configured so that the water level stored therein is 10 mm or less.

[0014] ( 7 ) The discharge area of ​​the dielectric barrier discharge caused by the electrodes and the dielectric may be configured to be 15% or more of the water surface area of ​​the water stored in the plasma treatment unit.

[0015] ( 8 ) The system may further include a storage tank for storing the plasma sterilized water generated in the plasma processing unit.

[0016] ( 9 ) The storage tank may be provided with a cooling device for cooling the stored plasma sterilized water. Effect of the Invention

[0017] According to the present invention, it is possible to provide a plasma sterilized water generating device that generates plasma sterilized water having a high sterilization effect. [Brief description of the drawings]

[0018] [Figure 1] 1 is a configuration diagram showing an example of a plasma sterilized water production device according to a first embodiment. [Diagram 2] 1 is a configuration diagram showing an example of a plasma sterilized water production device according to a first embodiment. [Diagram 3]1 is a configuration diagram showing a plasma processing unit of a plasma sterilized water production device according to a first embodiment. FIG. [Figure 4] 1 is a partially enlarged view showing an example of a plasma sterilized water production device according to a first embodiment. [Diagram 5] 1 is a flowchart showing a process for producing plasma sterilized water. [Figure 6] FIG. 13 is a diagram showing the results of a palm sterilization test using plasma sterilized water. [Figure 7] 1 is a graph showing the life span of the sterilization effect of plasma sterilized water. [Figure 8] FIG. 11 is a configuration diagram showing an example of a plasma sterilized water generating device according to a second embodiment. [Figure 9] FIG. 13 is a diagram showing the results of a sterilization test on an object surface using plasma sterilized water. [Figure 10] FIG. 13 is a diagram showing the results of a sterilization test on an object surface using sprayed plasma sterilizing water. [Figure 11] FIG. 11 is a configuration diagram showing an example of a plasma sterilized water generating device according to another embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] [First embodiment] [1. Overall composition] (Device configuration overview) A plasma sterilized water generating apparatus A according to an embodiment of the present invention will be described with reference to the drawings. The plasma sterilized water generating apparatus A is an apparatus that generates plasma sterilized water to be supplied to a sterilization target. In this embodiment, in particular, human hands and fingers are the main sterilization target.

[0020] Plasma sterilized water is water that contains dissolved radicals generated by performing plasma discharge on the water to be treated. The disinfecting power of these radicals is believed to be the disinfecting power of the target to disinfect. The pH of the plasma sterilized water generated by the plasma sterilized water generating device A is weakly acidic. Therefore, pernitric acid (HOONO2) is generated from nitrous acid (HNO2) and hydrogen peroxide (H2O2) by dielectric barrier discharge, and dissolves in the water. It is believed that these substances are the source of hydroperoxy radicals (HOO·), which have high disinfecting power.

[0021] Plasma sterilized water does not contain any chemicals or alcohol, so there is no residual residue. Furthermore, the radicals of the sterilization factors are inactivated by temperature (over time), so it quickly returns to water after sterilization, making it highly safe. Furthermore, plasma sterilized water is weakly acidic, so it does not cause rough hands, making it a sterilized water that is low-irritation and low-invasive to the human body. Plasma sterilized water generator A provides this type of plasma sterilized water in a form that is particularly suitable for disinfecting hands and fingers.

[0022] The plasma sterilized water generating device A has a raw water cartridge 1, a cooling mechanism 2, a plasma processing section 3, and a supply port T. Each component will be described in detail below with reference to FIG.

[0023] <Raw water cartridge> The raw water cartridge 1 is a bottomed container with an opening that contains water 11 before it is turned into plasma sterilized water by plasma treatment. It is preferable to use pure water or purified water as the water 11 in terms of improving the sterilizing power of the generated plasma sterilized water. However, it is also possible to generate plasma sterilized water using tap water or the like. Mineral water may also be used as long as it is soft water with a hardness of about 30. One example of the form of the plasma sterilized water generating device A is a water server type device that supplies plasma sterilized water by performing plasma treatment on water 11 supplied from a replaceable raw water cartridge 1.

[0024] In the plasma sterilized water generating device A, piping is provided to connect the various components so that the water 11 contained in the raw water cartridge 1 can be supplied to the plasma processing unit 3 via the cooling mechanism 2. Specifically, the opening of the raw water cartridge 1 is configured to be detachable from a cartridge mounting port provided at the end of the piping connected to the cooling mechanism 2. For example, like a water server, the raw water cartridge 1 may be configured to be attachable to the cartridge mounting port with the opening facing downward.

[0025] A pump 12 is provided in the piping connecting the raw water cartridge 1 and the cooling mechanism 2. When the pump 12 is driven, the pump 12 sucks in water 11 from the raw water cartridge 1 side and discharges it to the cooling mechanism 2 side to transfer the water 11. The pump 12 is controlled to transfer a predetermined amount of water 11 to the cooling mechanism 2 side.

[0026] A vent filter (not shown) may be provided at the opening of the raw water cartridge 1. By providing a vent filter, contamination of the water 11 due to air sucked into the raw water cartridge 1 can be prevented when the water 11 in the raw water cartridge 1 is supplied to the cooling mechanism 2. The vent filter can be a product used in a storage tank of a pure water device for analysis, etc.

[0027] Furthermore, when tap water or the like is used as the water 11, it is preferable to use a hollow fiber filter or an activated carbon filter to filter the water 11 before supplying it to the cooling mechanism 2. Specifically, an activated carbon filter can be used to remove chlorine and organic matter from the tap water, and an ion exchange filter can be used to remove ionic components. As a filter used to filter the tap water, for example, a filter having a performance capable of increasing the purity of tap water to the level of primary pure water using two types of filters is used. Note that instead of providing the raw water cartridge 1, a pure water production device or the like may be directly connected to the cooling mechanism 2 of the plasma sterilized water production device A to supply the water 11.

[0028] <Cooling mechanism> The cooling mechanism 2 is a mechanism for pre-cooling the water 11 supplied from the raw water cartridge 1 to 15°C or less. By setting the temperature of the water 11 to be plasma-treated in the plasma treatment unit 3 to 15°C or less, the temperature of the generated plasma sterilized water is about 20°C, so that decomposition of sterilization factors is suppressed and the sterilization effect of the generated plasma sterilized water can be maintained. By pre-cooling the water 11 to 15°C or less, the high sterilization power of the plasma sterilized water can be maintained for 5 minutes after generation and stored in a room temperature atmosphere of about 25°C.

[0029] As described above, the cooling mechanism 2 can be said to be configured to pre-cool the supplied water 11 so that the temperature of the water 11 to be plasma treated is 15° C. or less. Therefore, taking into consideration the piping of the actual plasma sterilized water production apparatus A, it is sufficient to cool the water 11 so that the temperature of the water 11 to be plasma treated is 15° C. or less, and the cooling temperature by the cooling mechanism 2 is not limited to 15° C. or less.

[0030] The cooling mechanism 2 may be a cooling tank 21 that pre-cools the water 11 supplied from the raw water cartridge 1. A liquid cooling jacket 22 may also be provided on the piping that connects the raw water cartridge 1 and the plasma processing unit 3. In this embodiment, the cooling mechanism 2 is provided as a pre-stage of the plasma processing unit 3, but there is no intention to exclude a configuration in which a cooling device is provided in the plasma processing unit 3 and the water 11 is cooled during plasma processing. However, if a cooling device is provided in the plasma processing unit 3, it is necessary to provide a heat exchanger in the plasma processing unit 3. Therefore, by using the cooling mechanism 2 to pre-cool the water 11, the configuration of the plasma sterilized water generating device A is simplified, and the device can be made smaller and less expensive.

[0031] (Cooling tank) The cooling tank 21, which is an example of the cooling mechanism 2, is a metal container that stores the water 11 supplied from the raw water cartridge 1. The capacity of the cooling tank 21 can be appropriately determined taking into consideration the amount of plasma processing performed at one time, and can be, for example, about 50 mL to several L. The cooling tank 21 is equipped with a cooling device 21a that cools the water 11 in the cooling tank 21 to 15°C or less. For example, a cooling compressor system such as a water server or a water cooler may be used, in which a copper tube is wound around the outside of the cooling tank 21 and a refrigerant is circulated inside the copper tube. Also, a Peltier element system may be used to circulate water (brine) cooled by a Peltier element through a pipe wound around the outside of the cooling tank 21.

[0032] Furthermore, the cooling tank 21 may be provided with a temperature sensor that detects the temperature of the water 11 inside, and a water level sensor that detects the water level inside the cooling tank 21. For example, the cooling device 21a may be configured to operate when the temperature detected by the temperature sensor exceeds a predetermined upper limit temperature. Also, the pump 12 may be configured to replenish the water 11 when the water level detected by the water level sensor falls below a predetermined water level.

[0033] With the above-mentioned configuration, the water 11 in the cooling tank 21 is pre-cooled to a low temperature (15° C. or lower). This cooling is performed by controlling the pump 12 and the cooling device 21a with a control device (not shown) that receives signals from a temperature sensor and a water level sensor. An outlet for the pre-cooled water 11 is provided on the bottom surface of the cooling tank 21. A pipe is connected to the outlet, and the other end of the pipe is connected to the plasma processing unit 3. The water 11 in the cooling tank 21 can be introduced into the plasma processing unit 3 by opening and closing a discharge valve provided on the pipe.

[0034] (Liquid cooling jacket) As shown in FIG. 2, another example of the cooling mechanism 2 is a mode in which a liquid cooling jacket 22 is provided on a pipe connecting the raw water cartridge 1 and the plasma processing unit 3. The liquid cooling jacket 22 is a heat sink configured by sandwiching a pipe made of copper, aluminum, or the like with a base body made of aluminum, or the like. The water 11 in the raw water cartridge 1 is supplied to the pipe of the liquid cooling jacket 22. A Peltier element 22a is disposed adjacent to the liquid cooling jacket 22 with its heat absorption side. The water 11 passing through the pipe of the liquid cooling jacket 22 is pre-cooled to a low temperature (15° C. or lower) by the heat absorption effect of the Peltier element 22a. The flow path, length, and diameter of the pipe of the liquid cooling jacket 22 can be appropriately determined in consideration of the amount of plasma processing performed at one time.

[0035] The cooling mechanism 2 using the liquid cooling jacket 22 may also be provided with a temperature sensor that detects the temperature of the water 11 discharged from the liquid cooling jacket 22. For example, the Peltier element 22a is controlled based on the temperature detected by the temperature sensor. The water 11 is cooled by controlling the pump 12 and the Peltier element 22a by a control device (not shown) that receives a signal from the temperature sensor. A pipe is connected to the outlet of the liquid cooling jacket 22, and the other end of the pipe is connected to the plasma processing unit 3. The water 11 discharged from the liquid cooling jacket 22 can be introduced into the plasma processing unit 3 by opening and closing a discharge valve provided in the pipe.

[0036] <Plasma processing section> The plasma processing unit 3 is a component that performs plasma treatment on pre-cooled water supplied from the cooling mechanism 2. When the plasma sterilized water is to be used for sterilization of human hands and fingers, the amount of water 11 subjected to plasma treatment in the plasma processing unit 3 at one time is preferably about 5 to 50 mL. This treatment amount is assumed to be about 5 mL of plasma sterilized water per person for sterilization, and is assumed to produce plasma sterilized water for 10 people in the case of continuous use.

[0037] The method of supplying the plasma sterilized water may be an on-demand method in which the plasma sterilized water is generated in a short time with 5 mL generated per cycle, or the plasma sterilized water may be generated for multiple cycles (for example, 10 mL to 50 mL) and continuously supplied. That is, it is preferable to set the upper limit of the plasma treatment amount per time to 50 mL. When the upper limit of the plasma treatment amount is set to 50 mL, the plasma sterilized water can be generated in a short time of about 1 minute with a relatively inexpensive and simplified device configuration, so that the device can be made smaller and less expensive. The amount of plasma treatment of the water 11 can be appropriately changed after considering the storage time during which the sterilization effect of the plasma sterilized water is sufficiently maintained. As shown in FIG. 3, the plasma treatment unit 3 has a reduced pressure chamber 31, a plasma treatment tank 32, an electrode 33a, a dielectric 34, and a power source 35.

[0038] (Decompression chamber) The decompression chamber 31 is a vacuum vessel having a pressure-resistant structure made of metal or resin. The volume of the decompression chamber 31 can be 1 to 2 L or less. For example, the decompression chamber 31 having a volume of 0.2 L can be used to perform plasma processing of 50 mL of water 11. In this embodiment, a configuration in which the plasma processing tank 32 and the electrode 33a are arranged in the decompression chamber 31 will be described. However, when a plasma processing tank 32 having a volume of 1 to 2 L that can be decompressed is used, the decompression chamber 31 can be omitted. When a plasma processing tank 32 that can be decompressed is used, the configuration of the decompression chamber 31, such as a decompression pump and a valve described below, may be applied to the plasma processing tank 32. In addition, the time required for the decompression process can be shortened by making the volume of the decompression chamber 31 or the decompressible plasma processing tank 32 as small as possible, taking into consideration the amount of plasma processing performed at one time.

[0039] An exhaust duct E having a decompression pump 31a and a valve 31b is connected to the decompression chamber 31. The exhaust duct E is a duct that exhausts gas inside the decompression chamber 31. The decompression pump 31a is a pump that sucks in and exhausts gas inside the decompression chamber 31. The valve 31b is a valve that adjusts the amount of exhaust when exhausting the gas inside the decompression chamber 31. The decompression pump 31a and the valve 31b are connected to a control device (not shown), and the flow rate of the decompression pump 31a and the opening degree of the valve 31b are controlled by control signals from this control device.

[0040] Specifically, the decompression pump 31a decompresses the gas phase atmosphere in the decompression chamber 31. The applied voltage required to generate a dielectric barrier discharge is reduced by decompressing the gas phase atmosphere with the decompression pump 31a. Here, it is sufficient for the decompression pump 31a to exhaust the gas inside the decompression chamber 31 so as to reduce the dielectric strength of air to a certain degree and create an extremely low vacuum state in which plasma can easily progress.

[0041] An extremely low vacuum refers to a state in which the degree of vacuum is 50 kPa (abs) or less when the power supply voltage is 20 kV / cm, and more preferably, a state in which the degree of vacuum is about 50 kPa (abs) to 30 kPa (abs). By making the reduced pressure chamber 31 an extremely low vacuum, it is possible to reduce the applied voltage required for discharge by about 50%. For example, if the reduced pressure chamber 31 requires an applied voltage of 30 kVpp when it is at atmospheric pressure, making the reduced pressure chamber 31 an extremely low vacuum of 30 kPa (abs) will reduce the required applied voltage to 14 kVpp.

[0042] The inside of the decompression chamber 31 only needs to be at an extremely low vacuum, and since the plasma processing tank 32 is disposed inside the decompression chamber 31, the gas phase volume of the decompression chamber 31 is relatively small. Therefore, even if an inexpensive pump with an ultimate vacuum of about 30 kPa (abs) to 70 kPa (abs) and an exhaust speed of about several L / min is used as the decompression pump 31a, the decompression chamber 31 can be in an extremely low vacuum state. For example, when plasma processing 50 mL of water 11 is performed using the decompression chamber 31 with a volume of 0.2 L, the decompression chamber 31 can be in an extremely low vacuum state in a few seconds even if an ULVAC DAP-6D pump with an exhaust speed of 6 to 7 L / min and an ultimate vacuum of about 10 kPa (abs) is used.

[0043] (Plasma treatment tank) The plasma processing tank 32 is a metal or resin tank that stores the water 11 disposed inside the decompression chamber 31. The plasma processing tank 32 is a box-shaped member with an opening on the top surface. The planar shape of the plasma processing tank 32 may be designed to match the shape of the apparatus, such as a rectangle or a circle. However, when using a plasma processing tank 32 that can be decompressed as described above, the tank may be a vacuum container. The plasma processing tank 32 has a size that can store, for example, 5 mL to 50 mL of water 11.

[0044] As an example, a plasma treatment tank 32 with an upper opening of about φ100 mm may be provided as the plasma treatment tank 32 for storing 50 mL of water 11. In this case, the depth of the 50 mL of water 11 is 10 mm or less. During plasma treatment, the surface of the water 11 is swayed by the dielectric barrier discharge, so it can be said that the dielectric barrier discharge has a stirring effect. If the depth of the water 11 is 10 mm or less, the water 11 may be automatically stirred during plasma treatment. Note that if the amount of water 11 stored is too large for the electrode configuration and power supply capacity used, plasma sterilized water with sufficient sterilizing power cannot be obtained. In this embodiment, a configuration that can provide sufficient sterilizing power to 5 to 50 mL of water 11 will be described as an example.

[0045] A water supply pipe S having a valve 32a is connected to the plasma processing tank 32. The water supply pipe S is a pipe for introducing pre-cooled water 11 into the plasma processing tank 32. The valve 32a is a valve for adjusting the amount of water 11 introduced. The valve 32a is connected to a control device (not shown), and the opening degree of the valve 32a is controlled by a control signal from this control device. The pre-cooled water 11 is supplied to the plasma processing tank 32 from the water supply pipe S.

[0046] A supply pipe D having a valve 32b and a liquid feed pump 32c is connected to the plasma treatment tank 32. The supply pipe D is a pipe that supplies the plasma sterilized water to an outlet T for the plasma sterilized water. The valve 32b is a valve for adjusting the supply amount when the plasma sterilized water is supplied to the outlet T. The liquid feed pump 32c is a pump for adjusting the flow rate of the supplied plasma sterilized water. The valve 32b and the liquid feed pump 32c are connected to a control device (not shown), and the opening degree of the valve 32b and the flow rate of the liquid feed pump 32c are controlled by a control signal from this control device. When the plasma sterilized water is used for disinfecting human hands and fingers, the valve 32b and the liquid feed pump 32c are controlled so that about 5 mL of the plasma sterilized water is supplied from the outlet T at one time.

[0047] It is also possible to configure the device so that a sensor is placed near the outlet T and automatically supplies a predetermined amount of plasma sterilized water when it detects that a disinfection target is located near the outlet T. The sensor mechanism can be a photoelectric method using visible light or infrared light (laser light, LED, etc.), an ultrasonic method, an eddy current method, an image recognition method, or the like. Also, a spray mechanism may be provided at the outlet T to spray the plasma sterilized water.

[0048] A cooling device may be provided in the plasma treatment tank 32 to cool the water 11 during plasma treatment. If the temperature of the water 11 rises due to plasma discharge, the sterilization factors may be decomposed, possibly reducing the sterilization effect. For example, when the device is used at high temperatures, the temperature of the water 11 may rise due to the influence of air temperature. In such a case, cooling the water 11 suppresses the decomposition of the sterilization factors and enhances the sterilization power of the generated plasma sterilized water. However, if the cooling mechanism 2 is provided to sufficiently pre-cool the water 11, there is no need for further cooling in the plasma treatment tank 32.

[0049] (electrodes and dielectrics) An electrode 33a and a ground electrode 33b are disposed facing each other inside the decompression chamber 31. A dielectric 34 is disposed between the electrode 33a and the ground electrode 33b.

[0050] The electrode 33a is a flat plate electrode made of metal. As the metal, for example, nickel, titanium, various stainless steels, aluminum, copper, palladium, gold, and silver can be used as a corrosion-resistant metal. Alternatively, Kovar may be used because of its compatibility with glass, which is an example of the dielectric 34. The horizontal size of the electrode 33a is smaller than the opening of the plasma processing tank 32 and is large enough to fit inside the plasma processing tank 32.

[0051] The planar areas of the electrode 33a and the dielectric 34 can be appropriately designed in consideration of the amount of water 11 to be treated, the power supply capacity, the electrode production cost, etc. In this embodiment, it is preferable to configure the electrode 33a and the dielectric 34 so that the area where the dielectric barrier discharge occurs is 15% or more of the water surface area. If the water level of the water 11 stored in the plasma treatment tank 32 is 10 mm or less, it is considered that the stirring effect of the dielectric barrier discharge will allow sufficient plasma treatment to be performed on the entire amount of the stored water 11.

[0052] The flat electrode 33a may be disk-shaped or rectangular with rounded corners. By making the shape round, it is possible to prevent electrolytic concentration at the edges and the progression of spark discharge. For this reason, the electrode 33a may be disk-shaped with a diameter of 40 mm when treating, for example, 50 mL of water 11. Heat generated by application of an AC voltage is conducted to the metal part of the electrode 33a. Therefore, a metal heat sink may be placed on the upper surface of the electrode 33a to promote heat dissipation.

[0053] The electrode 33a is disposed on the upper side of the plasma treatment tank 32. Specifically, as shown in Fig. 3, the electrode 33a is provided so as to be located above the surface of the water 11 when the water 11 is supplied so as to fill the plasma treatment tank 32. That is, a space is generated between the surface of the water 11 and the electrode 33a.

[0054] In this embodiment, the lower surface of the electrode 33a is covered with a dielectric 34. Therefore, the dielectric 34 faces the water surface of the water 11 stored in the plasma processing tank 32 across a space. Therefore, the space between the electrode 33a and the water surface of the water 11 actually means the space between the dielectric 34 and the water surface of the water 11.

[0055] (Dielectric) The narrower the space between the dielectric 34 and the surface of the water 11, the lower the resistance, and therefore the easier it is to discharge. However, if the plasma sterilized water generating device A is placed in a location where slight shaking occurs, there is a risk that the dielectric 34 and the water 11 may come into contact when the water 11 becomes rippled due to vibration or the like. For this reason, it is preferable that the space between the dielectric 34 and the surface of the water 11 be 5 mm or more and 10 mm or less. In particular, by making the space 8 mm, discharge is possible with an appropriate applied voltage, and contact between the dielectric 34 and the water 11 is prevented.

[0056] It is preferable that the dielectric 34 has a relatively large relative dielectric constant (εr), a small dielectric loss tangent (tanδ), and a good dielectric strength (KV / mm). However, when a ferroelectric material such as barium titanate having a relative dielectric constant exceeding several thousand is used, the heat generated by the dielectric effect caused by the application of an AC voltage may reach a high temperature. In that case, it is preferable to provide a heat dissipation mechanism such as a heat sink on the electrode 33a to dissipate the heat. The thinner the thickness of the dielectric 34, the easier it is to discharge. However, it is necessary to consider the balance between the applied voltage of the power source 35 described later and the dielectric strength of the dielectric 34. The thickness of the dielectric 34 is determined taking into consideration the durability and mechanical strength of the electrode 33a.

[0057] Considering the above conditions, the material that can be used for dielectric 34 may be glass (εr: 3 to 10, tan δ: 0.003), polyethylene (εr: 2 to 2.5, tan δ: ~0.0005), polypropylene (εr: 2 to 2.3, tan δ: ~0.0005), polytetrafluoroethylene (εr: 2.0, tan δ: ~0.0002), or ceramics such as anodized aluminum (oxalic acid anodized aluminum; εr: 6 to 10, tan δ: ~0.001) or silicon nitride (εr: 7 to 8, tan δ: 0.0005).

[0058] (Example of electrode configuration) The electrode 33a does not necessarily have to be flat, and may be formed of a metal film. For example, a glass plate or ceramic plate of about 2 to 3 mm thick may be used as the dielectric 34 so as to have sufficient strength, and a metal layer of about 50 μm may be vapor-deposited thereon as the electrode 33a. The metal to be vapor-deposited may be, for example, nickel or titanium. In particular, glass and nickel are compatible with each other, and are suitable for uniform vapor deposition without generating holes in the nickel layer. It is also possible to use Kovar sealing glass for the dielectric and fuse it to Kovar.

[0059] Alternatively, a silicon nitride substrate or an alumina-zirconia substrate having a diameter of 75 mm (or 75 mm×75 mm) and a thickness of about 1 mm may be used as the dielectric 34, and a metal layer of titanium or copper having a diameter of 40 to 50 mm and a thickness of 0.1 μm to 1 μm or less may be formed on the dielectric 34 by sputtering as the electrode 33a. When the electrode 33a is formed by sputtering, a base layer having a thickness of 0.1 μm to 1 μm or less may be provided on the dielectric 34, and a metal layer as the electrode 33a may be provided on the base layer. The dielectric 34, the base layer, and the metal layer as the electrode 33a may be collectively regarded as the electrode.

[0060] When the electrode 33a is formed on the dielectric 34 by sputtering, the adhesion of the formed layer to the dielectric 34 is improved, and the film stress can also be increased. As the underlayer, it is preferable to form titanium, palladium, nickel, or chromium, which has high adhesion to the dielectric 34, by sputtering. By forming the underlayer, the adhesion of the metal layer as the electrode 33a to the dielectric 34 is further improved. If the total thickness of the electrode 33a and the underlayer is 0.2 to 1 μm or less, the weight of the electrode 33a can be reduced. In addition, it is preferable that the total thickness of the electrode 33a and the underlayer is 0.2 to 0.5 μm. When a thin film having a total thickness of 0.2 to 0.5 μm is formed, the time required for sputtering is shortened while maintaining the electrode performance. Therefore, the number of manufacturing steps is reduced, and the electrode can be manufactured at a lower cost.

[0061] (ground electrode) The ground electrode 33b is disposed on the lower side of the plasma processing tank 32. In the example of Fig. 3, the plasma processing tank 32 is made of resin, and the ground electrode 33b is provided at a position where it is submerged in the water 11 stored in the plasma processing tank 32. The discharge current of the dielectric barrier discharge is configured to flow through the water 11 to the ground electrode 33b.

[0062] The material of the ground electrode 33b may be any metal, and its shape may be freely changed. However, it must be configured so that the discharge current of the dielectric barrier discharge can be reliably guided to the earth. Experiments have revealed that the pH of the water 11 becomes about 3 due to the influence of nitric acid generated by the plasma. Therefore, when the ground electrode 33b is submerged in the water 11 of the plasma processing tank 32, it is preferable to use, for example, stainless steel, which is highly corrosion-resistant and relatively resistant to nitric acid-based acids.

[0063] If the plasma treatment tank 32 is made of metal, the plasma treatment tank 32 may be connected to earth to function as the ground electrode 33b. That is, the ground electrode 33b disposed in the water 11 of the plasma treatment tank 32 includes the plasma treatment tank 32 itself. However, if the plasma treatment tank 32 is made of metal, and the inner wall surface of the plasma treatment tank 32 exposed to the gas phase side from the water surface of the water 11 becomes significantly close to the electrode 33a, a spark discharge toward the inner wall surface of the plasma treatment tank 32 may occur.

[0064] 4, it is advisable to secure a certain distance between the side surface of the electrode 33a and the inner wall surface of the plasma processing tank 32. This distance varies depending on the voltage applied to the electrode 33a, the thickness of the dielectric 34, and the air pressure in the decompression chamber 31, but considering that the insulation of air is 30 kV per cm, a distance of 50 mm or more can be secured to prevent spark discharge. In addition, the part of the inner wall surface of the plasma processing tank 32 that is exposed to the gas phase may be insulated and coated with a resin coating 32d.

[0065] (power supply) 3, the power supply 35 is a high-voltage power supply that applies an AC voltage for generating a dielectric barrier discharge to the electrode 33a. The power supply 35 has an AC frequency of about 20 kHz and an applied voltage of 10 to 20 kV. 0-p(2-3 kV / cm) and a power supply capacity of 100 W or less can be used. The power supply 35 may be appropriately selected so that the peak sterilizing power of the plasma sterilized water can be obtained in a short time of about 1 minute when plasma treating 5-50 mL of water 11. The power supply 35 is provided outside the reduced pressure chamber 31 and connected to the electrode 33a.

[0066] The circuit configuration of the power supply 35 is a sine wave, triangular wave, and pulse wave of several kHz to several tens of kHz, and 10 to 20 kV 0-p It is sufficient if it can generate an AC voltage of about (2 to 3 kV / cm). The higher the applied voltage, the higher the processing efficiency. However, since the gas phase in the decompression chamber 31 is decompressed to an extremely low vacuum of 50 kPa or less, a voltage of 10 kV is used. 0-p The plasma can be developed by applying a voltage of about 2 to 3 kV / cm.

[0067] Here, the power source 35 is configured to input 10 Wh or more, more preferably 20 Wh or more, of power per 1 L of water to be treated. For example, by treating 3 L of water to be treated at 180 W for 20 minutes, 20 Wh of power can be input per 1 L of water to be treated. When the same amount of power is input, even if the power and input time are different, the same sterilization effect can be obtained as long as the total input power amount is the same. In the plasma sterilized water generating device A of this embodiment, plasma treated water having a sterilization effect is generated by inputting 10 Wh / L or more of power. The sterilization effect of the generated plasma sterilized water is improved by inputting 20 Wh / L or more of power. The input power amount can be monitored by installing a power meter in the power supply system.

[0068] An example of the power source 35 is an inverter neon transformer (α Neon M5) manufactured by LESIP LP. In this case, a dielectric barrier discharge is generated at a voltage of 18 kVp-p (Max), a frequency of about 20 kHz, and 60 to 70 W, and 50 mL of plasma sterilized water is generated in one minute. At this time, by inputting DC 141 V to the AC 100 V input of the inverter neon transformer, the p-p value of the voltage, which usually fluctuates greatly (when AC 100 V is input), can be oscillated without fluctuating at the Max value of 18 kVp-p, thereby shortening the time for inputting power to the water 11.

[0069] [2. Plasma sterilization water production process] The plasma sterilized water production device A having the above-mentioned configuration produces plasma sterilized water through the following steps, as shown in FIG. (1) Pre-cooling process with water 11 (2) Supplying water 11 to the plasma treatment tank 32 (2) Decompression process of the decompression chamber 31 (3) Plasma treatment process using dielectric barrier discharge (4) Step of releasing the decompression chamber 31 to atmospheric pressure (5) Supply process of plasma sterilized water

[0070] (Water pre-cooling process) In the pre-cooling step of the water 11, the water 11 supplied from the raw water cartridge 1 side is cooled by the cooling mechanism 2 to, for example, 15° C. or less. As described above, the reason why the water 11 is cooled to 15° C. or less is that by setting the temperature of the water 11 to be plasma-treated in the plasma treatment unit 33 to 15° C. or less, decomposition of sterilization factors can be suppressed and the sterilization effect of the generated plasma-sterilized water can be improved.

[0071] (Water supply process) In the step of supplying water 11, 5 to 50 mL of pre-cooled water 11 is supplied to the plasma treatment tank 32. That is, valve 32a of the plasma treatment tank 32 is opened in response to a control signal from the control device. By opening valve 23a, water 11 is supplied to the plasma treatment tank 32 via water supply pipe S of the plasma treatment tank 32 connected to the cooling tank 21. When a predetermined amount of water 11 has been supplied to the plasma treatment tank 32, valve 23a is returned to a closed state in response to a control signal from the control device.

[0072] (Decompression process) In the decompression process, the gas inside the decompression chamber 31 is discharged to create a decompressed state. That is, the valve 31b of the decompression chamber 31 is opened in response to a control signal from the control device. When the valve 31b is opened, the decompression pump 31a is operated in response to a control signal from the control device. The decompression pump 31a sucks and discharges the gas inside the decompression chamber 31 until the decompression chamber 31 reaches an extremely low vacuum state. Here, the extremely low vacuum refers to a state in which the degree of decompression is 50 kPa or less. After the decompression chamber 31 reaches an extremely low vacuum state, the control device stops the decompression pump 31a and closes the valve 31b.

[0073] (Plasma treatment process) In the plasma treatment step, plasma is generated by dielectric barrier discharge in the space between the electrode 33a covered with the dielectric 34 and the surface of the water to be treated. That is, when a high voltage from the power source 35 is applied to the electrode 33a, plasma is generated in the space between the surface of the water 11 and the dielectric 34. Since the water 11 is electrically connected to the ground electrode 33b, plasma is generated in the space between the surface of the water 11 and the dielectric 34. This plasma generated in the gas phase generates radicals in the water 11, and plasma sterilized water is obtained.

[0074] (Atmospheric pressure release process) In the atmospheric pressure release step, the reduced pressure in the decompression chamber 31 is released to atmospheric pressure. That is, the valve 31b of the decompression chamber 31 is opened in response to a control signal from the control device.

[0075] (Plasma sterilized water supply process) In the plasma sterilized water supply process, the generated plasma sterilized water is supplied to the sterilization target via the outlet T. That is, the valve 32b of the plasma treatment tank 32 is opened in response to a control signal from the control device. When the valve 32b is opened, the liquid delivery pump 32c is operated in response to a control signal from the control device. The liquid delivery pump 32c sucks and discharges the plasma sterilized water from inside the plasma treatment tank 32 until a predetermined amount of the plasma sterilized water stored in the plasma treatment tank 32 is discharged. Then, when the predetermined amount of the plasma sterilized water has been discharged, the valve 32b is returned to a closed state in response to a control signal from the control device.

[0076] [3. Experiment] (Plasma disinfection test on palms) To examine the sterilization effect of the plasma sterilized water generated by the plasma sterilized water generator A, a sterilization test was conducted on bacteria normally present on the palm of an actual person. The experiment was conducted using the contact plate method (hand petan check) with a palm-shaped culture medium. An unwashed palm was used as the control. Sample 1 was a palm that was immersed for a moment in the plasma sterilized water and rubbed so that the plasma sterilized water came into contact with the entire palm. Sample 2 was a palm that was rubbed with one push of a commercially available alcohol spray. Sample 3 was a palm that was rubbed with one push of a commercially available alcohol gel (designated quasi-drug). The general viable bacteria counts of the culture medium were compared for these controls and samples 1 to 3.

[0077] Figure 6 shows the results of the sterilization test using the hand petan check. As shown in Figure 6, a clear reduction in the general viable bacteria count was confirmed for sample 1, which was applied with plasma sterilized water, compared to the control, which was contacted with unwashed palms. Furthermore, when sample 1 was compared with sample 2 and sample 3, which used commercially available alcohol sterilizers, it became clear that the sterilization effect of the plasma sterilized water generated by plasma sterilizing water generator A was equal to or greater than that of the alcohol sterilizer.

[0078] (Safety of plasma sterilized water) Regarding the safety of the plasma sterilized water generated by the plasma sterilized water generator A, it has been confirmed that there were no abnormalities in the acute oral toxicity test (based on OECD420), that there was no irritation in the primary skin irritation test (based on OECD404), and that there was no irritation in the eye irritation test (based on OECD405). In other words, it has been proven that it is safe even if people accidentally ingest it, touch it with their hands, or get it in their eyes.

[0079] (Ingredients and pH of plasma sterilizing water) Table 1 shows the results of measuring the components and pH of the plasma sterilized water generated by the plasma sterilized water generator A. [Table 1]

[0080] As is clear from Table 1, the plasma sterilized water generated by the plasma sterilized water generator A had a pH of 3.55 to 4.27, which was weakly acidic, in the same pH range as the human palm. It was found that the plasma sterilized water does not have the degreasing effect of alcohol-based disinfectants, so there is no need to worry about rough hands.

[0081] (Lifespan of Plasma Sterilizing Water) An experiment was conducted to confirm the lifespan of the sterilization effect of the plasma sterilized water generated by the plasma sterilized water generating device A. The plasma sterilized water used in the experiment was generated using 50 mL of each of the following: pure water pre-cooled to 5°C (2 samples), pure water pre-cooled to 10°C (2 samples), pure water pre-cooled to 15°C (2 samples), and pure water at room temperature (25°C) (1 sample). The degree of vacuum in the decompression chamber 31 was set to 50 kPa (abs), and a dielectric barrier discharge was generated by a sine wave generated with a power supply alternating frequency of 20 kHz and an applied voltage of 10 kV0-p (18 kVp-p). The voltage application time, i.e., the plasma processing time, was set to 1 minute.

[0082] The experiment was carried out at a concentration of about 10 8Several ampoules containing 1 mL of E. coli (ATCC13706) suspension adjusted to CFU / mL were prepared. 9 mL of pure water of each temperature was added to each ampoule to dilute it 10-fold, resulting in a concentration of approximately 10 8 A control sample of CFU / mL was used. In addition, 9 mL of plasma sterilized water at each temperature was added to different ampoules and diluted 10 times to prepare test samples. Test samples were prepared using four types of plasma sterilized water: plasma sterilized water 1 minute after plasma treatment, plasma sterilized water 5 minutes after plasma treatment, plasma sterilized water 10 minutes after plasma treatment, and plasma sterilized water 15 minutes after plasma treatment. The temperature at which the plasma sterilized water was left standing was room temperature (approximately 25°C). After culturing the control sample and the four test samples, the number of colonies was counted.

[0083] The results of counting the number of colonies are shown in Figure 7. From Figure 7, it can be seen that the number of live bacteria in the test sample using plasma sterilized water one minute after plasma treatment was reduced by 5 to 6 orders of magnitude compared to the control sample, and that regardless of the temperature of the plasma-treated water, the plasma-sterilized water immediately after production has a strong sterilizing power. Next, in the test sample using plasma sterilized water five minutes after plasma treatment, it was found that if the temperature of the plasma-treated water was 15°C or lower, sterilization was achieved by 3 to 5 orders of magnitude, and the sterilization power was sufficient. However, when the temperature of the plasma-treated water was 25°C, sterilization was reduced by less than one order of magnitude after 5 minutes, indicating a significant decrease in sterilization power.

[0084] Furthermore, in test samples using plasma-sterilized water 10 and 15 minutes after plasma treatment, the sterilization rate was less than one digit at all temperatures, indicating a significant decrease in sterilization power. These results show that by pre-cooling the water to be plasma-treated to below 15°C, it is possible to store the plasma-sterilized water in a room temperature atmosphere of around 25°C while maintaining its high sterilization power for 5 minutes after it is generated.

[0085] [4. Effects] The effects of the plasma sterilized water generating apparatus A of this embodiment as described above are as follows. (1) The plasma processing unit has a cooling mechanism 2 for pre-cooling the supplied water 11 to a predetermined temperature, a plasma processing unit 3 configured to store the water 11 and to be capable of reducing the pressure, a pressure reduction pump 31a for reducing the pressure of the gas phase atmosphere so that the inside of the plasma processing unit 3 becomes an extremely low vacuum, a flat electrode 33a disposed so as to be located above the surface of the water 11 stored in the plasma processing unit 3, a dielectric 34 disposed on the underside of the flat electrode 33a and facing the surface of the water 11 stored in the plasma processing unit 3 across a space, a ground electrode 33b disposed so as to be located in the water stored in the plasma processing unit, and a power source 35 for applying an AC voltage to the electrode 33a.

[0086] With the above configuration, the water 11 to be subjected to plasma treatment is cooled in advance to a predetermined temperature. By pre-cooling the water 11, it is possible to generate plasma sterilized water with high sterilizing power, and the effect of the generated plasma sterilized water can be maintained after generation. Furthermore, by using the cooling mechanism 2 to pre-cool the water 11, the configuration of the plasma sterilized water generating device A is simplified compared to the case where a heat exchanger is provided in the plasma processing unit 3, and therefore the device can be made smaller and less expensive.

[0087] (2) It has a raw water cartridge 1 that stores water 11 , and is configured so that the water 11 is supplied from the raw water cartridge 1 to the cooling mechanism 2 .

[0088] By providing a raw water cartridge 1 that stores water 11, it becomes possible to generate plasma sterilized water even in an installation environment where there is no supply source of water 11. In addition, since there is no need to install piping or the like in conjunction with the supply source of water 11, the device can be made compact.

[0089] (3) The cooling mechanism 2 comprises a cooling tank 21 for storing the supplied water 11 and a cooling device 21a for cooling the cooling tank 21, and is configured so that the water 11 pre-cooled to a predetermined temperature in the cooling tank 21 is introduced into the plasma processing unit 3.

[0090] By using the cooling tank 21 as the cooling mechanism 2, for example in the case of a cooling compressor system, it is possible to cool water of 2 to 3 L or less from room temperature to 5° C. or less within 30 minutes. Therefore, with a simple configuration, a relatively large amount of water 11 can be reliably pre-cooled.

[0091] (4) The cooling mechanism 2 is configured to include a liquid-cooled jacket 22 through which supplied water 11 flows and a Peltier element 22a that cools the liquid-cooled jacket 22, and the water 11 pre-cooled to a predetermined temperature by the liquid-cooled jacket 22 is introduced into the plasma processing unit 3.

[0092] When the cooling mechanism 2 is a liquid cooling jacket 22, it becomes possible to cool the water 11 in the piping path that supplies the water 11 to the plasma processing unit 3. Therefore, it becomes possible to further reduce the size of the plasma sterilized water production device A.

[0093] (5) The cooling mechanism 2 pre-cools the water 11 to be plasma-treated in the plasma treatment unit 3 so that the temperature of the water 11 is 15° C. or lower.

[0094] By pre-cooling the water 11 to be plasma treated to below 15° C., the plasma sterilized water can be stored for 5 minutes after production while retaining its high sterilizing power in a room temperature atmosphere of about 25° C. This makes it possible to continuously supply the plasma sterilized water to multiple objects to be disinfected.

[0095] (6) The amount of water 11 that is plasma-treated in the plasma treatment unit 3 is 50 mL or less.

[0096] When the upper limit of the plasma processing volume is set to 50 mL, it is possible to generate plasma sterilized water in a short time of about 1 minute using the plasma sterilized water generating device A, which has a relatively inexpensive and simple configuration. This makes it possible to realize a compact and cost-effective device.

[0097] (7) The plasma processing unit 3 is configured so that the water level of the stored water 11 is 10 mm or less.

[0098] During plasma treatment, the dielectric barrier discharge causes pulsation on the surface of the water 11. In other words, it can be said that the dielectric barrier discharge has an effect of stirring the water 11. If the depth of the water 11 is 10 mm or less, the water 11 is automatically stirred during plasma treatment, making it possible to produce plasma sterilized water that is uniform and has high sterilizing power.

[0099] (8) The discharge area of ​​the dielectric barrier discharge caused by the electrode 33a and the dielectric 34 is configured to be 15% or more of the water surface area of ​​the water 11 stored in the plasma processing unit 3.

[0100] By setting the area where the dielectric barrier discharge occurs to 15% or more of the water surface area, if the water level of the water 11 stored in the plasma treatment tank 32 is 10 mm or less, the stirring effect of the dielectric barrier discharge can enable sufficient plasma treatment to be performed on the entire amount of the stored water 11.

[0101] [Second embodiment] (composition) The plasma sterilized water generating apparatus B according to the second embodiment has a configuration basically similar to that of the first embodiment, as shown in Fig. 8. However, in this embodiment, the main target of sterilization is the surfaces of objects that people may touch or that may have droplets attached thereto. Possible objects include, for example, tables, chairs, doorknobs, and partitions.

[0102] When the plasma sterilized water is used for sterilization of the surface of an object, it is preferable that the upper limit of the amount of water 11 to be plasma-treated in the plasma treatment unit 3 at one time is 50 mL. This treatment amount is based on the assumption that about 50 mL of plasma sterilized water is used for sterilization at one time. The amount of plasma treatment of the water 11 can be changed as appropriate after considering the storage time during which the sterilization effect of the plasma sterilized water is sufficiently maintained. In the following explanation, the configuration unique to the second embodiment will be explained, and the same components as those in the plasma sterilized water generating apparatus A will be assigned the same reference numerals and their explanation will be omitted.

[0103] In the plasma sterilized water generating apparatus B, the capacity of the cooling tank 21 can be several hundred mL to several L, taking into consideration the amount of plasma treatment per time. Similarly, the plasma treatment tank 32 has a size large enough to store, for example, 50 mL of water 11. In this embodiment, a configuration capable of imparting sufficient sterilizing power to 50 mL of water 11 will be described as an example.

[0104] As for the power source 35, a power source that can obtain the peak sterilizing power of the plasma sterilized water in a short time of about one minute when plasma treating 50 mL of water 11 may be appropriately selected. For example, using the above-mentioned inverter neon transformer, one cycle may consist of generating 50 mL of plasma sterilized water in one minute. The method of supplying the plasma sterilized water may be an on-demand method with the amount of generation per cycle set at an upper limit (e.g., 50 mL), or a configuration in which two to three cycles' worth of plasma sterilized water (e.g., 100 mL to 150 mL) is generated and stored.

[0105] In the case where the generated plasma sterilized water is to be stored, a storage tank 4 can be provided. However, the storage time after generation is limited by the time during which the plasma sterilized water maintains a sufficient sterilization effect. After the storage time has elapsed, the plasma sterilized water remaining in the storage tank 4 and the plasma treatment tank 32 may be discharged or returned to the cooling mechanism 2 via the piping P for reuse. The piping P may be provided for each of the plasma treatment tank 32 and the storage tank 4, or a common piping P may be used. The piping P may be provided with an appropriate valve or liquid delivery pump so that the plasma sterilized water can be returned to the cooling mechanism 2.

[0106] To extend the storage time, a cooling mechanism 41 is provided in the storage tank 4, and the plasma sterilized water can be stored for about 10 to 15 minutes by keeping the stored water at a low temperature (10°C or lower). In order to maintain the sterilizing effect of the generated plasma sterilized water for a longer period, it is preferable to store the plasma sterilized water at a storage temperature of 7°C or lower. A supply pipe D having a valve 42 and a liquid delivery pump 43 is connected to the storage tank 4. The configuration of these components can be the same as the valve 32b and liquid delivery pump 32c provided in the supply pipe D connected to the plasma treatment tank 32.

[0107] The plasma sterilized water generating device B is preferably provided with an outlet T suitable for disinfecting the surface of an object. For example, a faucet or a spray nozzle can be used as the outlet T. It is also possible to configure the device to automatically supply a predetermined amount of plasma sterilized water via such an outlet T in response to the operation of a faucet, the pressing of a foot switch, or the detection of an object to be disinfected by a sensor.

[0108] In this embodiment, in addition to directly supplying the plasma sterilized water to the surface of an object through the outlet T, it is also assumed that a certain amount of the plasma sterilized water is filled into a spray bottle or the like, and the plasma sterilized water is sprayed onto the object to be disinfected using the spray bottle. When using a sensor to automatically fill the spray bottle through the outlet T, a photoelectric, ultrasonic, eddy current, or image recognition sensor that detects the approach of the spray bottle can be used. Furthermore, a capacitance sensor that detects the capacitance of the spray bottle (or the filled plasma sterilized water), or a weight sensor that detects the weight of the spray bottle (or the filled plasma sterilized water) may also be used.

[0109] Alternatively, the spray bottle may be filled with plasma sterilized water by manually operating the outlet T. A push button for turning on / off the water or a push lever used in water servers may be used as a switch for manual filling. A lever, cock, faucet handle, etc. may also be used.

[0110] As shown in Fig. 8, the plasma sterilized water generating device B can be provided with a sink 5 for collecting excess plasma sterilized water supplied from the outlet T. The sink 5 can be provided with a drainage outlet, to which a drainage pipe can be connected to discharge the plasma sterilized water after sterilization. A splash prevention hood can also be provided above the sink 5 to prevent the scattering of mist and splashes caused by rebounding when the plasma sterilized water is sprayed on the object to be sterilized.

[0111] In addition, by filling a spray bottle or the like with the plasma sterilized water generated by the plasma sterilized water generator B, it is possible to sterilize objects located far away from the plasma sterilized water generator B or large objects that cannot be moved to the plasma sterilized water generator B. In this case, it is preferable that the spray bottle into which the plasma sterilized water is filled has a cooling function. For example, it is preferable to use a thermos-type spray bottle with a vacuum insulation mechanism or one with a coolant attached to a body with high thermal conductivity such as aluminum.

[0112] In the case of a spray bottle with a structure in which a coolant is filled in advance on the bottom or around the bottle, if the spray bottle is cooled in a freezer before filling it with plasma sterilized water, the plasma sterilized liquid filled in the bottle is kept cold, so that the sterilization effect can be maintained. Alternatively, a general-purpose cooler bottle cover containing a general-purpose coolant for cooling bottles or a food cooling agent may be attached to a general-purpose spray bottle. It is preferable to use a spray bottle made of metal. The amount of plasma sterilized water filled into the spray bottle at one time is limited to an upper limit of 100 mL to 150 mL, and the bottle is filled again after it has been used up, so that the sterilization effect of the plasma sterilized water can be maintained together with the cooling effect.

[0113] (Sterilization test of object surfaces using plasma sterilizing water) A disinfection test was conducted on the surface of an object using the plasma disinfectant water generated by the plasma disinfectant water generator B. The disinfection test was conducted using a concentration of 10 6The experiment was carried out using a CFU / mL E. coli suspension. 30 μL of the E. coli suspension was dropped and spread on a glass surface, and 120 μL of plasma sterilized water was dropped and spread on this. After 5 minutes, it was brought into contact with an agar medium (Petan Check SCD medium) and cultured for one day. Similarly, pure water (DW) and tap water were dropped onto the E. coli suspension spread on a glass surface and cultured. The results of the sterilization test are shown in Figure 9. With pure water (DW), there was almost no difference from the state where the E. coli suspension was spread (control). When tap water was dropped, the sterilization effect was about two orders of magnitude. When the plasma sterilized water was dropped, almost no bacteria were detected, demonstrating a high sterilization effect.

[0114] Next, a test was conducted in which the plasma sterilized water was sprayed onto a glass surface on which the E. coli suspension (30 μL) had been spread. This sterilization test was conducted because it was expected that the appropriate amount would be relatively large compared to a drop, as there would be losses when spraying due to diffusion and floating on surfaces other than the area where the bacteria are present and in the air. The sterilization test was conducted using a spray bottle that sprays 100 μL of plasma sterilized water with one push, and the sterilization effect was confirmed when the spray bottle was pushed once (100 μL), twice (200 μL), and three times (300 μL). The results are shown in Figure 10. At a control concentration of 10 6 It was confirmed that one push reduced the number of bacteria by about one digit for CFU / mL, two pushes reduced it by more than two digits, and three pushes sterilized the bacteria to the point where almost no bacteria remained. In other words, it was found that even when the plasma sterilizing water was sprayed on the surface of an object, a high sterilizing effect could be achieved by adjusting the amount of application.

[0115] (Action and effect) The plasma sterilized water generating apparatus B of this embodiment as described above has the following advantageous effects in addition to those of the above embodiment. (1) A storage tank 4 is further provided for storing the plasma sterilized water generated in the plasma processing unit 3.

[0116] By configuring the generated plasma sterilized water to be stored in storage tank 4, it becomes possible to supply a larger amount of plasma sterilized water at one time.

[0117] (2) The storage tank 4 is equipped with a cooling device for cooling the stored plasma-sterilized water.

[0118] By providing a cooling device in the storage tank 4 and keeping the plasma sterilized water at a low temperature during storage, it is possible to store the plasma sterilized water for a longer period of time while maintaining its sterilizing effect.

[0119] [Other embodiments] (1) In the above embodiment, a configuration has been described in which a sensor is disposed near the outlet T, and a predetermined amount of plasma sterilized water is automatically supplied upon detecting that a disinfection target is located near the outlet T. In addition to such a sensor, a sensor may be provided that detects the approach of a user to the plasma sterilized water generating devices A and B. Such a sensor may be a commonly used human presence sensor, and may be interlocked with an automatic door at the building entrance. By controlling the start of the supply of water 11 to the cooling mechanism 2 and the decompression of the decompression chamber 31 based on the sensor detecting the approach of the user, it is possible to shorten the total time until the plasma sterilized water is supplied to the palm.

[0120] (2) A decompression tank with a volume equal to or greater than that of the decompression chamber 31 and connected to the decompression pump 31a may be connected to the decompression chamber 31 via a valve. With this configuration, the decompression tank can be decompressed by the decompression pump 31a while the device is idling when no user is present. If the valve between the decompression chamber 31 and the decompression tank is opened at the timing when the generation of plasma sterilized water starts, the inside of the decompression chamber 31 can be instantly decompressed. This makes it possible to further reduce the time of the decompression process.

[0121] (3) The plasma sterilized water generator A may be provided with an air blower so that the palms can be drained (dried) after the plasma sterilized water is supplied to them. Conventional hand dryers are often not used because splashes of water can be a source of infection, but the plasma sterilized water generator A sterilizes the palms using plasma sterilized water, so the possibility of infection from water droplets is low and the draining mechanism can be kept clean.

[0122] (4) In the above embodiment, an example was introduced in which the plasma sterilized water generating apparatus B is configured to continuously supply plasma sterilized water by providing a storage tank 4 to store the generated plasma sterilized water. However, continuous supply of plasma sterilized water may be realized by providing two plasma processing units 3A and 3B in the plasma sterilized water generating apparatus B and having the plasma processing units 3A and 3B alternately supply plasma sterilized water, as shown in FIG. 11. The number of plasma processing units installed in one plasma sterilized water generating apparatus B is not limited to two, and may be more than two. Also, a configuration in which the plasma processing unit 3A and the plasma processing unit 3B share the decompression pump 31a may be used. Even when multiple plasma processing units are provided, a configuration in which a storage tank 4 is provided to store the generated plasma sterilized water may be used. Two or more storage tanks 4 may also be provided.

[0123] (5) In order to keep the plasma sterilized water generating device B hygienic, a cleaning mode for cleaning the piping system of the device B may be installed. Also, a mechanism for periodically spraying plasma sterilized water onto the inner surface of the sink 5 to clean and sterilize it may be provided. The cleaning and sterilization of the piping system and the inside of the sink 5 may be configured to flow newly generated plasma sterilized water at a preset time. Also, the piping system and sink 5 of the device may be cleaned using plasma sterilized water remaining in the storage tank 4 and the plasma treatment tank 32 within the storage time limit.

[0124] (6) In the above embodiment, the plasma sterilizing water generator A intended for disinfecting human hands and the plasma sterilizing water generator B intended for disinfecting the surface of an object have been described. However, the configuration of the plasma sterilizing water generator A and the configuration of the plasma sterilizing water generator B can be freely combined as necessary. That is, the plasma sterilizing water generator A can be appropriately provided with a plurality of plasma processing units 3A and 3B, a storage tank 4, a sink 5, etc. In addition, the plasma sterilizing water generators A and B can also be regarded as plasma sterilizing water generators intended for both disinfecting human hands and disinfecting the surface of an object. That is, the plasma sterilizing water generators A and B are not limited by the object to be disinfected.

[0125] (7) The control of the plasma sterilized water generators A and B using the input power amount described in the above embodiment may be configured so that a control device calculates and controls a voltage application time based on the amount of water to be treated and the power. In the above embodiment, it is assumed that the control device is built into the plasma sterilized water generators A and B, but an external control device may be connected to the plasma sterilized water generators A and B. The control device can be realized by controlling a computer with a predetermined program or by a dedicated electronic circuit. The amount of water to be treated, the input power amount, and the voltage application time may also be configured so that the user inputs them. [Explanation of symbols]

[0126] A, B Plasma sterilizing water generator 1 Raw water cartridge 11 water 12 Pump 2 Cooling mechanism 21 Cooling Tank 21a Cooling device 22 Liquid cooling jacket 22a Peltier element 3, 3A, 3B Plasma treatment section 31 Decompression Chamber E Exhaust duct 31a Pressure reducing pump 31b Valve 32 Plasma treatment tank S Water supply pipe 32a Valve D Supply piping 32b Valve 32c Liquid delivery pump 32d resin coating 33a electrode 33b Ground electrode 34 Dielectric 35 Power supply 4. Storage Tank 41 Cooling mechanism 42 Valve 43 Liquid delivery pump T spout 5. Sync

Claims

1. A cooling mechanism that pre-cools the supplied water to a predetermined temperature; a plasma processing unit configured to store the pre-cooled water supplied from the cooling mechanism and to be capable of reducing pressure; a decompression pump that decompresses a gas phase atmosphere so that an inside of the plasma processing unit becomes an extremely low vacuum; a flat electrode provided above the water surface of the water stored in the plasma processing unit; a dielectric body provided on a lower surface side of the flat electrode and facing a water surface of the water stored in the plasma processing unit across a space; a ground electrode disposed in the water stored in the plasma processing unit; A power source that applies an AC voltage to the electrodes, The plasma sterilized water generating apparatus, wherein the amount of water plasma-treated in the plasma treatment unit is 50 mL or less.

2. The plasma sterilizing water generating device according to claim 1 , further comprising a raw water cartridge for storing the water, and the water is supplied from the raw water cartridge to the cooling mechanism.

3. the cooling mechanism includes a cooling tank that stores the supplied water and a cooling device that cools the cooling tank, 3. The plasma sterilizing water generating device according to claim 1, wherein the water pre-cooled to a predetermined temperature in the cooling tank is introduced into the plasma processing section.

4. the cooling mechanism includes a liquid-cooling jacket through which the supplied water flows, and a Peltier element that cools the liquid-cooling jacket, 3. The plasma sterilizing water generating device according to claim 1, wherein the water pre-cooled to a predetermined temperature by the liquid cooling jacket is introduced into the plasma processing section.

5. The plasma sterilizing water generating device according to any one of claims 1 to 4, wherein the cooling mechanism pre-cools the water so that the temperature of the water to be plasma-treated in the plasma treatment unit is 15°C or lower.

6. The plasma sterilizing water generating device according to any one of claims 1 to 5, wherein the plasma processing unit is configured so that the water level stored therein is 10 mm or less.

7. The plasma sterilizing water generating device according to claim 6, wherein the discharge area of ​​the dielectric barrier discharge caused by the electrodes and the dielectric is configured to be 15% or more of the water surface area of ​​the water stored in the plasma treatment unit.

8. The plasma sterilized water generating apparatus according to any one of claims 1 to 7, further comprising a storage tank for storing the plasma sterilized water generated in the plasma processing unit.

9. 9. The plasma sterilized water generating apparatus according to claim 8, wherein the storage tank is provided with a cooling device for cooling the stored plasma sterilized water.

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