Liquid plasma treatment equipment

Abstract

A liquid plasma treatment device is provided that can reduce the generation of bubbles and can perform continuous and uniform plasma treatment on a liquid. [Solution] This liquid plasma treatment apparatus has a liquid flow layer (106) sandwiched between a pair of protective dielectric layers (116, 117), and on the upstream side of the liquid flow layer (106) are a pair of electrolysis electrodes (129, 130) on the surfaces of the pair of protective dielectric layers that sandwich the liquid flow layer and apply a voltage to the liquid, and on the downstream side of the liquid flow layer (106) is a plasma generation unit (100) configured to sandwich a dielectric layer between a pair of electrode layers that is stacked on the protective dielectric layer (116), and comprises a liquid flow layer, an AC power supply unit that applies an AC voltage between the pair of electrode layers, and an electrolysis power supply unit that applies a voltage between the pair of electrolysis electrodes, and is characterized in that the liquid passing through the liquid flow layer (106) is plasma treated using plasma generated in the plasma generation unit (100).

Description

[Technical Field]

[0001] The present invention relates to a liquid plasma treatment apparatus for plasma treating a liquid. [Background technology]

[0002] In recent years, a technique called dielectric barrier discharge (DBD) has been developed in plasma processing technology, making it possible to generate low-temperature plasma at atmospheric pressure. As a result, the range of applications of plasma processing has expanded, and it is increasingly being used in a variety of applications. The purposes of plasma processing include sterilization, deodorization, surface modification, and decomposition of chemical substances. Furthermore, the substances that can be subjected to plasma processing can be solid, liquid, or gaseous.

[0003] There are already many prior art methods for obtaining a liquid containing an active component generated by plasma treatment (hereinafter referred to as a "plasma liquid"). For example, Patent Documents 1 and 2 can be cited. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 7180927 [Patent Document 2] Patent No. 7312400 Summary of the Invention [Problem to be solved by the invention]

[0005] Methods for obtaining plasma liquid can be classified into several methods as follows. (1) A method in which gas is plasma-treated and the resulting gas (hereinafter sometimes referred to as "plasma gas") flow is mixed with a liquid flow in a mixer: In this method, the plasma gas flow from the pipe and the liquid flow from the pipe are joined in a mixer and stirred and mixed. When the gas and liquid flows are combined and stirred and mixed, bubbles tend to form in the mixed liquid. In particular, to obtain plasma liquid with a high concentration of active ingredients, it is necessary to vigorously stir and mix the gas and liquid, which poses the problem of the tendency for numerous bubbles to form. These bubbles are particularly problematic when freezing plasma water to make plasma ice, making it difficult to produce transparent ice or ice with few bubbles.

[0006] (2) Method of injecting plasma gas into a liquid tank and mixing the plasma gas with the liquid: In this method, plasma gas is introduced into a liquid tank, and the plasma gas is stirred and mixed while being finely dispersed in the liquid tank, dissolving the plasma gas into the liquid. In particular, to obtain a plasma liquid with a high concentration of active ingredients, it is necessary to vigorously stir and mix the gas and liquid, but there is a problem in that bubbles are easily generated in the liquid.

[0007] (3) A method in which a pair of electrodes is inserted into a liquid to generate plasma in the liquid, producing a plasma liquid: While this method can generate plasma using small needle-shaped electrodes, it is difficult to generate uniform plasma over a large surface, making it difficult to process large quantities. Because a high voltage is applied to the liquid, there is a risk of electrical leakage. Furthermore, the large change in impedance between the electrodes makes it difficult to control the voltage applied to the electrodes. Furthermore, with conductive liquids containing salt, for example, this method either does not work, or if it does work, the liquid deteriorates, or there is a risk of electrical leakage or electric shock. The in-liquid plasma devices described in Patent Documents 1 and 2 correspond to this method.

[0008] The present invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to provide a liquid plasma treatment apparatus that can reduce the generation of bubbles and can perform continuous and uniform plasma treatment on a liquid. [Means for solving the problem]

[0009] The inventor discovered that by utilizing plasma leaking out from a plasma generating section composed of an electrode layer and a dielectric layer to continuously and uniformly plasma treat liquid passing through a liquid flow layer stacked in the plasma generating section, it is possible to stably obtain plasma liquid, and was able to arrive at the present invention.

[0010] That is, the present invention has the following configuration. (1) A plasma treatment apparatus for liquid, comprising: a liquid flow layer sandwiched between a pair of protective dielectric layers; a pair of electrolysis electrodes disposed on the upstream side of the liquid flow layer on the liquid flow layer side surfaces of the pair of protective dielectric layers for applying a voltage to the liquid across the liquid flow layer; and a plasma generation unit configured to sandwich a dielectric layer between a pair of electrode layers laminated on the downstream side of the liquid flow layer on the protective dielectric layers; a liquid flow unit capable of passing a liquid through the liquid flow layer; an AC power supply unit for applying an AC voltage between the pair of electrode layers; and an electrolysis power supply unit for applying a voltage between the pair of electrolysis electrodes; characterized in that the liquid passing through the liquid flow layer is plasma-treated using plasma generated in the plasma generation unit. (2) The liquid plasma treatment apparatus according to (1), characterized in that the plasma generating units are laminated on the pair of protective dielectric layers, respectively, downstream of the liquid fluidized bed. (3) The liquid plasma treatment apparatus according to (1) above, wherein one of the two electrode layers constituting the plasma generating unit is grounded. (4) The liquid plasma processing apparatus described in (2) above, characterized in that no potential difference is established between two of the four electrode layers constituting the pair of plasma generating units that face each other across the liquid flow layer. (5) The liquid plasma processing apparatus according to (1) above, wherein the outer edge of the electrode layer is sealed with an insulating member. (6) The liquid plasma treatment apparatus according to (1) above, wherein at least one of the electrode layers has a plurality of through holes, and the through holes are sealed with an insulating member. [Effects of the Invention]

[0011] The liquid plasma treatment apparatus of the present invention is capable of reducing the generation of bubbles and of subjecting liquid to continuous and uniform plasma treatment. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 2 is a perspective view for explaining a plasma generating unit. [Figure 2] FIG. 2 is a perspective view for explaining a plasma generating unit. [Figure 3] FIG. 2 is a cross-sectional view for explaining a plasma generating unit. [Figure 4] FIG. 10 is a perspective view for explaining a plasma generating unit according to a first modified example. [Figure 5] FIG. 10 is a perspective view for explaining a plasma generating unit according to a second modified example. [Figure 6] FIG. 10 is a cross-sectional view illustrating a plasma generating unit according to a third modified example. [Figure 7] 1 is a perspective view for explaining a first embodiment of a liquid plasma treatment apparatus. FIG. [Figure 8] FIG. 8 is a cross-sectional view of the first embodiment of FIG. 7. [Figure 9] FIG. 10 is a perspective view for explaining a second embodiment of a liquid plasma treatment apparatus. [Figure 10] FIG. 10 is a cross-sectional view of the second embodiment of FIG. 9. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, embodiments of the present invention will be described in detail, but the embodiments of the present invention are not limited to the embodiments described below. Each embodiment and modified example can be applied in appropriate combination. Furthermore, directions such as "upper and lower" and "front and back" in the description are used for convenience of explanation and do not limit the directions of the present invention.

[0014] In this embodiment, the liquid to be treated with plasma is not particularly limited, and examples of the liquid include water, aqueous solutions, aqueous dispersions, organic solvents, beverages, etc., but are not limited thereto, and water or aqueous solutions are the main target.

[0015] In this embodiment, the liquid is not moved between a pair of electrodes to which an AC voltage is applied, but is moved in the space outside the pair of electrode layers to which an AC voltage is applied. Therefore, even if the liquid is conductive, electricity does not flow through the conductive liquid, and plasma processing can be performed safely.

[0016] The liquid plasma treatment apparatus of this embodiment includes a liquid flow layer sandwiched between a pair of protective dielectric layers. A pair of electrolysis electrodes are provided on the upstream side of the liquid flow layer, on the liquid flow layer-side surfaces of the pair of protective dielectric layers, for applying a voltage to the liquid across the liquid flow layer. A plasma generation unit is stacked on the downstream side of the liquid flow layer on the protective dielectric layers. The plasma generation unit has a configuration in which a dielectric layer is sandwiched between a pair of electrode layers. The plasma generation unit further includes a liquid flow unit that can pass a liquid through the liquid flow layer, an AC power supply unit that applies an AC voltage between the pair of electrode layers, and an electrolysis power supply unit that applies a voltage between the pair of electrolysis electrodes. By applying an AC voltage to the pair of electrode layers of the plasma generation unit, plasma can be generated, and the liquid flowing through the liquid flow layer can be plasma-treated. First, the plasma generation unit will be described.

[0017] <Basic structure of the plasma generation unit> As shown in FIGS. 1 and 2, the plasma generating unit 10 includes a dielectric layer 11, an upper electrode layer 12, a lower electrode layer 13, an upper mask layer 14, and a lower mask layer 15. The plasma generating unit 10 is a thin-film member and may be made of a flexible material. For convenience, the dielectric layer 11 is depicted as a single dielectric layer, but it may also have a multilayer structure in which multiple dielectric layers, including one or more air layers, are stacked. The mask layer is intended to protect the electrode layer and improve assembly of the electrode layer, and may be omitted. Furthermore, by appropriately selecting the thickness and position of the mask layer, excessive electric field concentration on the electrode layer can be prevented, thereby extending the life of the electrode layer.

[0018] As shown in FIGS. 1 to 3, the dielectric layer 11 is a layered member disposed between the upper electrode layer 12 and the lower electrode layer 13. The material of the dielectric layer 11 is an insulating material with a large breakdown voltage so that discharge does not easily occur between the upper electrode layer 12 and the lower electrode layer 13. Furthermore, since the material of the dielectric layer 11 will be exposed to the generated plasma, it is preferable that the material be durable against active substances generated in the plasma. The material of the dielectric layer 11 is preferably a material selected mainly from glass, ceramics, and synthetic resins. The term "mainly" means that the component composition is 50% by mass or more (the same applies hereinafter).

[0019] Examples of glass include soda-lime glass (soda glass), borosilicate glass, quartz glass, lead glass, oxide glass, etc. Examples of ceramics include alumina, silica, titanium oxide, zinc oxide, etc.

[0020] Synthetic resins include thermoplastic resins and thermosetting resins. Examples of thermoplastic resins include general-purpose resins such as polyolefin, polystyrene, polyvinyl acetate, polyurethane, polylactic acid, ABS resin, AS resin, acrylic resin, polyvinyl chloride, and polyvinylidene chloride; engineering plastics such as polyamide, polyacetal, polycarbonate, modified polyphenylene ether, polyester, and cyclic polyolefin; and super-engineering plastics such as polyphenylene sulfide, polysulfone, polyethersulfone, polyarylate, liquid crystal polymer, polyetheretherketone, polyimide, polyamideimide, polyetherimide, fluorine-based resin, and silicone-based resin. Examples of thermosetting resins include phenolic resin, melamine resin, urea resin, alkyd resin, epoxy resin, unsaturated polyester resin, and polyurethane resin. Among these synthetic resins, silicone-based resins, polyimide-based resins, and Teflon®-based resins, which are highly durable, are particularly preferred. The thickness of the dielectric layer 11 is not particularly limited, but is preferably 0.1 mm to 5.0 mm, more preferably 0.1 mm to 3.0 mm, and even more preferably 0.1 mm to 1.0 mm, in order to achieve light weight and compactness.

[0021] As shown in FIGS. 1 to 3, the upper electrode layer (electrode layer) 12 and the lower electrode layer (electrode layer) 13 are layered members disposed on the front and back of the dielectric layer 11. The outer edges (peripheries) of the electrode layers 12 and 13 are preferably sealed with an insulating member. The insulating member serves to insulate the electrode layers 12 and 13, which are exposed to high temperatures and active substances when an AC voltage is applied, from the outside world and to protect them from deterioration over time. The insulating member also serves to prevent short-circuiting between the electrode layers 12 and 13, to which an AC voltage is applied, via the surrounding end faces or surfaces of components.

[0022] At least one of the electrode layers 12, 13 preferably has a plurality of through holes 16. The upper electrode layer 12 and the lower electrode layer 13 shown in Figures 1 to 3 are each provided with through holes 16 that penetrate in the thickness direction. In this embodiment, the through holes 16 are oval in plan view, and five through holes 16 are formed, but the shape and number are not limited. When through holes 16 are formed in the electrode layer, acute-angled edges are present near the cross-section of the electrode layer within the through holes 16, which makes it easier to generate plasma in the surrounding area, which is preferable. Therefore, by forming many through holes 16, more plasma can be generated.

[0023] 1 to 3, through holes 16 formed in the upper electrode layer 12 and the lower electrode layer 13 and through holes 17 formed in the upper mask layer 14 and the lower mask layer 15 (described later) are formed in the same position and with the same shape, and are continuous. As a result, the insides of the through holes 16 and 17 are exposed to the outside. At this time, plasma generated near the cross-sections of the electrode layers in the through holes 16 and 17 leaks out to the outside through the through holes 16 and 17, and is effective in plasma processing of liquids and the like moving outside the plasma generation unit 10.

[0024] On the other hand, there is an embodiment in which through holes are formed in the upper electrode layer 12 and the lower electrode layer 13, but no through holes are formed in the upper mask layer 14 and the lower mask layer 15 described below. In this case, the through holes 16 formed in the electrode layers 12 and 13 are preferably sealed with an insulating member. Forming the through holes 16 in the electrode layers 12 and 13 has the advantage of facilitating plasma generation near the cross-sectional portions of the electrode layers within the through holes 16. On the other hand, if the formed through holes 16 are sealed with an insulating member, there is no cavity (space) where the through holes 16 are formed, and therefore it is possible to suppress the occurrence of a discharge phenomenon between the electrode layers through the cavity (space), and it is possible to suppress a decrease in the durability of the plasma generation unit 10.

[0025] The shape, number, and orientation of the through holes 16, 17 relative to the liquid movement direction can be appropriately selected depending on the purpose of the plasma treatment, the effect of the plasma treatment, etc. Furthermore, the shapes of the through holes may be different on the front and back sides of the plasma generating unit 10. Furthermore, through holes may be provided on the front side of the plasma generating unit 10, and no through holes may be provided on the back side. Furthermore, the ratio of the area of ​​the through holes 16, 17 to the area of ​​the conductor (electrode) is not particularly specified, but the same effect can be obtained with a structure in which the hole dimensions of the through holes 16, 17 are large, for example, a mesh-like structure.

[0026] The upper electrode layer 12 and the lower electrode layer 13 are formed of a conductive material, and may be a metal plate (including metal foil), a conductive paint, a conductive polymer, a conductive film, etc. The thickness of the upper electrode layer 12 and the lower electrode layer 13 is not particularly limited, but is preferably 5 μm to 1.0 mm, more preferably 5 μm to 0.2 mm, and even more preferably 5 μm to 0.1 mm, respectively, in order to provide a flexible, lightweight, and compact processing device.

[0027] The dielectric layer 11, the upper electrode layer 12, and the lower electrode layer 13 may be laminated without using an adhesive, or may be bonded with an adhesive. The adhesive is preferably a material that is durable against active substances generated in plasma. Examples of adhesives include epoxy, acrylic, urethane, phenol, urea, silicone, polyamide, polyimide, cyanoacrylate, rubber, and vinyl acetate adhesives. Among these, silicone adhesives and UV-curable epoxy adhesives are preferred from the viewpoint of durability, with polyamide adhesives, polyimide adhesives, and silicone adhesives being more preferred. The thickness of the adhesive is preferably 0.01 to 0.2 mm, and more preferably 0.01 to 0.1 mm.

[0028] As shown in FIGS. 1 to 3 , the upper mask layer 14 and the lower mask layer 15 are members disposed on the outer sides of the upper electrode layer 12 and the lower electrode layer 13, respectively. More specifically, the upper mask layer 14 is disposed on the upper surface of the upper electrode layer 12. The lower mask layer 15 is disposed on the lower surface of the lower electrode layer 13. The upper mask layer 14 and the lower mask layer 15 are each provided with through holes 17. In this embodiment, the through holes 17 are oval in shape, and five through holes 17 are formed, but the shape and number are not limited thereto. The through holes 17 may be omitted. Furthermore, for ease of manufacture, the through holes 17 are preferably the same as the through holes 16, but are not limited thereto.

[0029] In the structures shown in FIGS. 2 and 3, through-hole 17 is illustrated as having the same shape as through-hole 16. As a result, the surface of dielectric layer 11 is exposed to the outside at multiple locations where through-holes 16 and 17 are formed. Furthermore, hole walls (cross-sectional portions) 16a and 17a of through-holes 16 and 17 are also exposed to the outside, respectively. Furthermore, through-holes 16 and 17 may be provided on only one side. Furthermore, when a mask layer is formed using a liquid resin or the like, the mask layer penetrates into areas where there are no electrodes and directly covers dielectric layer 11. However, in such cases, in areas where dielectric layer 11 is exposed, the material constituting the mask layer functions as part of dielectric layer 11. At the same time, the mask layer can also be used to protect dielectric layer 11.

[0030] The upper mask layer 14 and the lower mask layer 15 are formed of an insulating material. Similar to the dielectric layer 11, the insulating material is preferably a material selected from glass, ceramics, and synthetic resins. Furthermore, the hardness of the upper mask layer 14 and the lower mask layer 15 is preferably equal to or less than that of the upper electrode layer 12 and the lower electrode layer 13. While the plasma generation unit 10 can be difficult to handle if it is manufactured using a thin material, providing the upper mask layer 14 and the lower mask layer 15 improves ease of handling. Furthermore, the upper mask layer 14 and the lower mask layer 15 can protect the thin conductor from mechanical and physical shocks during manufacture and use, as well as deterioration caused by the surrounding environment. Furthermore, they can provide mechanical protection against scratches that may occur during manufacture. On the other hand, when considering that the plasma generating unit 10 will be installed on an object to be mounted, it is preferable that the upper mask layer 14 and the lower mask layer 15 have a hardness that allows them to be easily installed along the object to be mounted and also improves handling. Furthermore, by dividing the dielectric layer 11 into two, the upper and lower structures of the plasma generating unit 10 can be made symmetrical. Manufacturing can be easily achieved by assembling the upper and lower structures and bonding them together in the center. In this case, the dielectric layer 11 is divided into three layers: the upper layer, the lower layer, and the adhesive layer, but can be considered electrically as a single dielectric.

[0031] The thicknesses of the upper mask layer 14 and the lower mask layer 15 are not particularly limited, but in order to provide a flexible, lightweight, and compact processing device, they are preferably 5 μm to 1.0 mm, more preferably 5 μm to 0.2 mm, and even more preferably 5 μm to 0.1 mm. The thicknesses of the upper mask layer 14 and the lower mask layer 15 may be set appropriately, but in this embodiment they are formed to be thicker than the thicknesses of the upper electrode layer 12 and the lower electrode layer 13.

[0032] The plasma generating unit 10 can be made very thin and flexible, which can lead to problems such as difficulty in handling during assembly. Furthermore, the plasma generating unit 10 is installed to conform to the shape of the target object. However, if the upper and lower mask layers 14 and 15 are not provided and only the upper and lower electrode layers 12 and 13 are used, problems arise in that the metal constituting the electrodes may wrinkle or gaps may form between the dielectric layer 11 and the upper and lower electrode layers 12 and 13, respectively, if the electrodes are made of thin metal. Gaps between the upper and lower electrode layers 12 and 13 and the dielectric layer 11 can cause abnormal or partial discharges.

[0033] In this regard, according to the present embodiment, the upper mask layer 14 and the lower mask layer 15 can protect the upper electrode layer 12 and the lower electrode layer 13, making the plasma generation unit 10 easier to handle and improving workability and assembly. Furthermore, the provision of the upper mask layer 14 and the lower mask layer 15 allows the plasma generation unit 10 to be installed on an object without forming wrinkles or gaps. Furthermore, when multiple pairs of electrodes are provided in a multi-stage configuration, the upper mask layer 14 and the lower mask layer 15 also serve as part of the dielectric constituting the barrier discharge, making it less likely that abnormal discharge will occur even if gaps are formed during installation. However, the upper mask layer 14 and the lower mask layer 15 are not particularly necessary for applications in which mechanical strength, electrode life, etc. are not a consideration. Furthermore, as long as the dielectric layer 11 sufficiently protrudes from the ends of the upper electrode layer 12 and the lower electrode layer 13, the upper mask layer 14 and the lower mask layer 15 are not necessarily required. Furthermore, an insulating layer (not shown) may be provided on the outside of the upper mask layer 14 and the lower mask layer 15 .

[0034] The plasma generating unit 10 may have a configuration in which a plurality of electrode layers and dielectric layers 11 are alternately stacked as needed. Also, it may have a configuration in which a plurality of the layer configurations shown in Figs. 1 to 6 are stacked. In this case, in addition to the electrode layers and dielectric layers 11, mask layers, insulating layers, etc. may be appropriately combined.

[0035] <First Modification of Plasma Generation Unit> 4 is a perspective view for explaining a plasma generating unit according to a first modified example. The plasma generating unit 10A according to the first modified example differs from the basic structure described above in that it does not have an upper mask layer 14. As in the plasma generating unit according to the first modified example, the mask layer may be provided only on one side of the plasma generating unit 10A.

[0036] <Second Modification of Plasma Generation Unit> FIG. 5 is a perspective view illustrating a plasma generating unit according to a second modified example. The plasma generating unit 10B according to the second modified example differs from the basic structure described above in that it does not include the upper mask layer 14 and the lower mask layer 15. As with the plasma generating unit 10B according to the second modified example, the upper mask layer 14 and the lower mask layer 15 may be omitted. By configuring the plasma generating unit 10B with a dielectric layer 11, an upper electrode layer 12, and a lower electrode layer 13, it is possible to further reduce the size of the unit, reduce the number of electrode manufacturing steps, and reduce the number of parts. Furthermore, by thinning the dielectric layer 11, the upper electrode layer 12, and the lower electrode layer 13, the electrode layers themselves can be made flexible, allowing them to be manufactured to conform to curved surfaces.

[0037] Furthermore, as in the first and second modified examples, by omitting both or one of the upper mask layer 14 and the lower mask layer 15, the upper electrode layer 12 and the lower electrode layer 13 can be brought into direct contact with the liquid, and plasma can be brought into contact with the liquid at the edge of the electrode layer, thereby performing plasma treatment.

[0038] <Third Modification of Plasma Generation Unit> FIG. 6 is a cross-sectional view illustrating a plasma generating unit according to a third modified example. The plasma generating unit 10C according to the third modified example differs from the basic structure described above in that it does not include an upper mask layer 14 and a lower mask layer 15. Furthermore, the plasma generating unit 10C according to the third modified example does not have a monolithic dielectric layer, but is composed of an upper dielectric layer 18 and a lower dielectric layer 19, which are separated vertically and arranged facing each other. However, since air is also considered a type of dielectric, if the upper dielectric layer 18, air layer 20, and lower dielectric layer 19 are combined into a single dielectric layer 11, the structure is the same as that of the plasma generating unit 10B shown in FIG. 5. An upper electrode layer 12 is provided on the upper surface of the upper dielectric layer 18, and a lower electrode layer 13 is provided on the lower surface of the lower dielectric layer 19. An air layer 20 is provided between the upper dielectric layer 18 and the lower dielectric layer 19. In the third modified example, plasma can also be generated in the air layer 20.

[0039] First Embodiment Next, a liquid plasma processing apparatus according to a first embodiment of the present invention will be described. FIG. 7 is a perspective view illustrating the first embodiment of the liquid plasma processing apparatus according to the present invention, and FIG. 8 is a cross-sectional view of the first embodiment shown in FIG. 7. The liquid plasma processing apparatus according to the first embodiment of the present invention has a liquid fluidization layer 106 sandwiched between a pair of protective dielectric layers 116, 117. On the upstream side of the liquid fluidization layer 106, a pair of electrolysis electrodes 129, 130 are provided on the surfaces of the pair of protective dielectric layers 116, 117 facing the liquid fluidization layer 106, sandwiching the liquid fluidization layer 106 and applying a voltage to the liquid. Furthermore, on the downstream side of the liquid fluidization layer 106, a plasma generation unit 100 having a configuration in which a dielectric layer 114 is sandwiched between a pair of electrode layers 110, 112 is stacked on the protective dielectric layer 116.

[0040] The liquid plasma treatment apparatus of the first embodiment also has a liquid flow unit (not shown) that can pass a liquid through the liquid flow bed 106, an AC power supply unit (not shown) that applies an AC voltage between the pair of electrode layers 110, 112, and an electrolysis power supply unit (not shown) that applies a voltage between the pair of electrolysis electrodes 129, 130.

[0041] The plasma generating unit 100 includes a dielectric layer 114, a pair of electrode layers (first electrode layer 110, second electrode layer 112), and a first mask layer 108. A protective dielectric layer 116 functions as a mask layer for the second electrode layer 112, and also forms a liquid flow layer 106, which is a flow path for the liquid. The outer edges of the first electrode layer 110 and the second electrode layer 112 are sealed with an insulating member 113. As described using FIGS. 1 to 6, the plasma generating unit 100 can be made in a variety of variations.

[0042] The liquid flow layer 106 is a space below the plasma generating unit 100, through which a liquid can pass. In this space, wall materials (not shown) are installed on both sides along the liquid flow path to hold back the flow of the liquid and form the liquid flow layer 106. The pair of protective dielectric layers 116, 117 are in direct contact with the liquid and form the liquid flow path, and are selected from materials that are required to be durable against the liquid.

[0043] A plurality of through holes 118 are formed in the first electrode layer 110 and the second electrode layer 112 of the plasma generating unit 100, penetrating in the thickness direction. The optimal size of the through holes 118 depends on the frequency of the AC power supply and the characteristics of the dielectric layer 114, but a minimum diameter length of approximately 0.1 mm to 20 mm is preferable. In this embodiment, the through holes 118 may have the same symmetrical shape in the first electrode layer 110 and the second electrode layer 112, but this is not a particular limitation. The through holes 118 are sealed with an insulating member.

[0044] 7 and 8, the plasma generating unit 100 is configured to be linear (flat), but if the plasma generating unit 100 is configured from a thin, flexible material, it can be bent within a range that does not destroy the material. As a result, even if the center of the liquid flow layer 106 expands due to pressure caused by moving liquid in the liquid flow layer 106, the electrode layers 110 and 112 can bend accordingly, allowing them to absorb mechanical strain.

[0045] A pair of electrolysis electrodes 129, 130 are installed on the liquid-fluidized layer-side surfaces of the pair of protective dielectric layers 116, 117, located within the liquid-fluidized layer 106, allowing voltage to be applied to the liquid across the liquid-fluidized layer 106. Applying voltage to the electrolysis electrodes 129, 130 from an electrolysis power supply promotes electrolysis of the liquid, and the resulting substance is used for plasma processing. A specific example is water as the liquid, and hydrogen gas and oxygen gas as the substances produced by electrolysis. When AC voltage is used, bubbles containing hydrogen and oxygen nanobubbles and microbubbles are generated around the electrolysis electrodes. When DC voltage is used, oxygen is generated around the positive electrode layer, and bubbles containing hydrogen nanobubbles and microbubbles are generated around the negative electrode layer. By appropriately selecting the power supply frequency and flow rate, it is possible to create invisible bubbles and mix them into the water. These very fine bubbles, unlike methods such as directly spraying gas into water, can efficiently produce plasma water without vigorously agitating the fluid. As a result, in the part of the liquid fluidized bed 106 where plasma is generated, three substances, water, oxygen gas, and hydrogen gas, are present and mixed together, making it easier to create activated species than when only water is plasma treated.

[0046] The voltage applied to the pair of electrolysis electrodes 129, 130 may be DC or AC. In the case of AC, a similar effect can be achieved with an AC bias voltage source by selecting an appropriate frequency and voltage or slightly changing the AC phase. When water is used as the liquid, the voltage required for water electrolysis is approximately 1.2 V, but a higher voltage may be used. The DC voltage is preferably 1.2 V to 30 V, more preferably 3 to 15 V. The AC voltage has a frequency of preferably 0.001 Hz to 30 kHz, more preferably 0.01 Hz to 100 Hz. The voltage is preferably 1 to 30 V, more preferably 3 to 15 V. Plasma treatment of the liquid can be performed more safely if one of the two electrolysis electrodes 129, 130 facing each other across the liquid fluidized bed 106 is grounded.

[0047] A pair of electrolysis electrodes 129, 130 are located upstream of the liquid flowing bed 106 and apply a voltage to the liquid flowing in the liquid flowing bed 106 to electrolyze the liquid. Substances produced by electrolysis are easily converted into activated species by plasma treatment. The liquid then moves downstream within the liquid flowing bed 106 and passes the position of the protective dielectric layer 116 on which the plasma generating unit 100 is laminated. At this time, the liquid is effectively treated by the plasma generated by the plasma generating unit 100.

[0048] The material of the electrolysis electrodes 129, 130 is preferably one that is resistant to corrosion in water, and is preferably platinum, carbon, platinum-coated titanium, or the like, but is not limited to these.

[0049] <Action and effect> In the plasma generating unit 100, an AC voltage is applied between the first electrode layer 110 and the second electrode layer 112 by an AC power supply unit (not shown). As a result, plasma is generated in the dielectric layer 114 between the first electrode layer 110 and the second electrode layer 112. Most of the plasma is generated in the dielectric layer 114 between the first electrode layer 110 and the second electrode layer 112, but some of the plasma leaks out to the back side of the second electrode layer 112 through the through-holes 118, etc. The plasma then passes through the protective dielectric layer 116 and reaches the liquid flowing layer 106. The liquid moving in the liquid flowing layer 106 is plasma-treated by coming into contact with the plasma that has leaked into the liquid flowing layer 106.

[0050] The amount of plasma leaking into the liquid flow layer 106 below the protective dielectric layer 116 can be controlled by appropriately selecting the number and pattern of the through holes 118 formed in the second electrode layer 112, the thickness, relative dielectric constant, and dielectric strength of the protective dielectric layer 116, etc. Therefore, the amount of plasma in the liquid fluidized bed 106 is hardly affected by the liquid moving through the liquid fluidized bed 106. As a result, the liquid moving through the liquid fluidized bed 106 can be stably treated with a constant amount of plasma.

[0051] Furthermore, in this embodiment, plasma treatment can be performed without applying a high voltage to the liquid passing through the liquid flow bed 106, so plasma treatment can be performed stably even with conductive liquids, which was difficult to do with conventional methods, or in situations where the conditions in the space change from moment to moment.

[0052] Furthermore, in this embodiment, even if the properties of the liquid (e.g., dielectric constant, conductivity, etc.) change, the impedance between the electrode layers does not change, so larger electrode layers can be used, and therefore the plasma and the liquid can come into contact over a larger area. As a result, in this embodiment, a large amount of plasma liquid can be produced.

[0053] In addition, in this embodiment, there is no need for a process of mixing gas and liquid, and plasma can be applied directly to the liquid, so the liquid does not foam due to the gas, and the generation of bubbles can be reduced. Furthermore, by using a material that transmits light (mainly ultraviolet light) generated from the plasma for the protective dielectric layer 116, it is possible to simultaneously sterilize, disinfect, and deodorize the liquid using plasma light such as ultraviolet light.

[0054] The AC power supply unit is not particularly limited as long as it can apply an AC voltage of a predetermined frequency and voltage to each electrode of the plasma generating unit, and any known power supply device can be used. The frequency of the AC voltage is preferably 50 Hz to 30 MHz, more preferably 50 Hz to 100 kHz. The AC voltage is preferably 0.1 to 50 kV, more preferably 0.2 to 10 kV. It is preferable that one of the two electrode layers constituting the plasma generating unit is grounded, as this allows for safer operation.

[0055] Second Embodiment Next, a liquid plasma treatment apparatus according to a second embodiment of the present invention will be described. Below, explanations of the content common to the first embodiment will be omitted, and the focus will be on matters not described in the second embodiment. Figure 9 is a perspective view for explaining the second embodiment of the liquid plasma treatment apparatus according to the present invention, and Figure 10 is a cross-sectional view of the second embodiment of Figure 9.

[0056] The liquid plasma processing apparatus of the second embodiment of the present invention differs from the first embodiment in that plasma generating units 101 and 102 are stacked on protective dielectric layers 116 and 117 on both sides of the liquid flowing bed 106, respectively, downstream of the liquid flowing bed 106. That is, downstream of the liquid flowing bed 106, plasma generating unit 101, which has a configuration in which a dielectric layer 114 is sandwiched between a pair of electrode layers 110 and 112, is stacked on protective dielectric layer 116. Furthermore, downstream of the liquid flowing bed 106, plasma generating unit 102, which has a configuration in which a dielectric layer 126 is sandwiched between a pair of electrode layers 122 and 124, is stacked on protective dielectric layer 117. The upper plasma generating unit 101 and the lower plasma generating unit 102 have a mirror structure, with the layers arranged symmetrically to each other.

[0057] The upper plasma generating unit 101 includes a dielectric layer 114, a first electrode layer 110, a second electrode layer 112, a first mask layer 108, and a protective dielectric layer 116 that functions as a mask layer. The lower plasma generating unit 102 includes a dielectric layer 126, a first electrode layer 122, a second electrode layer 124, a first mask layer 120, and a protective dielectric layer 117 that functions as a mask layer. The two plasma generating units 101, 102 are stacked in parallel and face each other with a liquid flow layer 106 sandwiched between them. In Figures 9 and 10, the first electrode layers 110, 122 and the second electrode layers 112, 124 are shown as having the same size and shape, but this is not necessarily the case.

[0058] The outer edges of the first electrode layer 110 and the second electrode layer 112 of the upper plasma generating unit 101 are sealed with an insulating member 113. Similarly, the outer edges of the first electrode layer 122 and the second electrode layer 124 of the lower plasma generating unit 102 are sealed with an insulating member 123. Furthermore, similar to the first embodiment, the first electrode layers 110, 122 and the second electrode layers 112, 124 of the plasma generating units 101, 102 have a plurality of through holes 118, 130 formed therethrough in the thickness direction. The through holes 118, 130 are sealed with an insulating member.

[0059] The liquid passing through the liquid fluidized bed 106 is treated from both above and below by the plasma generated by the upper plasma generating section 101 and the lower plasma generating section 102, allowing for more effective and more intense treatment.

[0060] In the liquid plasma processing apparatus of the second embodiment, of the four electrode layers 110, 112, 122, and 124 constituting a pair of plasma generating units 101 and 102, it is preferable to have no potential difference between the two electrode layers 112 and 124 facing each other across the liquid flow layer 106. That is, by maintaining the same potential between the second electrode layer 112 of the upper plasma generating unit 101 and the second electrode layer 124 of the lower plasma generating unit 102, even if a conductive liquid is present in the liquid flow layer 106 sandwiched between the two electrode layers, no current flows between the two electrode layers, allowing for safe plasma processing. Furthermore, by grounding the second electrode layer 112 of the upper plasma generating unit 101 and the second electrode layer 124 of the lower plasma generating unit 102, current flow through the liquid can be prevented, preventing electrical leakage through the liquid and enabling safer operation.

[0061] By using the liquid plasma treatment apparatus of the first and second embodiments, it is possible to produce a plasma liquid containing a large amount of active ingredients. Furthermore, the resulting plasma liquid does not contain bubbles, or even if it does, they are very fine, so when the plasma water is frozen to produce plasma ice, it can be made into clear ice with few bubbles.

[0062] <Sterilization and disinfection methods> Plasma treatment is known to be capable of sterilizing, inactivating, deodorizing, and decomposing chemical substances. The mechanism by which plasma treatment exerts these functions is thought to be that reactive oxygen species (ROS) such as singlet oxygen, hydrogen peroxide, OH radicals, superoxide ions, and ozone are generated in the gas, which then kill or inactivate target microorganisms and decompose or modify chemical substances through oxidation reactions, etc. Examples of microorganisms include various bacteria, viruses, and mold.

[0063] The liquid plasma treatment apparatus of this embodiment can perform plasma treatment on a variety of liquids. For example, it can perform plasma treatment on liquids containing dispersed solids, liquids containing conductive substances such as ions, liquids whose marketability deteriorates when stirred or whipped, and highly viscous liquids. In particular, it can be used to plasma treat beverages such as drinking water, mineral water, tea, coffee, cocoa, soft drinks, fruit juice drinks, carbonated drinks, vegetable drinks, jelly drinks, functional drinks, sports drinks, alcoholic beverages, milk, dairy drinks, soy milk, and soup.

[0064] The liquid plasma treatment device of this embodiment can continuously and uniformly treat a beverage with plasma by passing the beverage through a liquid fluidized bed, thereby sterilizing and disinfecting the beverage. Many beverages lose their marketability when stirred or whipped. For example, when milk is stirred or whipped vigorously, the milk components solidify and form a cheese-like substance. Therefore, the liquid plasma treatment device of this embodiment is suitable for sterilizing and disinfecting beverages.

[0065] Although various embodiments of the present invention have been described above, appropriate design changes can be made within the scope of the present invention. [Explanation of symbols]

[0066] 100, 101, 102 Plasma generating unit 110, 112, 122, 124 electrode layer 106 Liquid fluidized bed 114, 126 Dielectric layer 108, 116, 120, 128 mask layers 116, 117 Protective dielectric layer 129, 130 Electrode for electrolysis

Claims

1. a liquid flow layer sandwiched between a pair of protective dielectric layers; a pair of electrolysis electrodes for applying a voltage to the liquid across the liquid flow layer, the pair of protective dielectric layers being disposed on the surfaces of the pair of protective dielectric layers facing the liquid flow layer, on the upstream side of the liquid flow layer; a plasma generating unit having a dielectric layer sandwiched between a pair of electrode layers is laminated on the protective dielectric layer at the downstream side of the liquid flowing bed; a liquid flow section that allows liquid to pass through the liquid flow bed; an AC power supply unit that applies an AC voltage between the pair of electrode layers; an electrolysis power supply unit that applies a voltage between the pair of electrolysis electrodes, A plasma treatment apparatus for liquid, characterized in that the liquid passing through the liquid fluidized bed is plasma-treated with the plasma generated in the plasma generating section.

2. 2. The liquid plasma treatment apparatus according to claim 1, wherein the plasma generating section is laminated on each of the pair of protective dielectric layers downstream of the liquid flowing bed.

3. 2. The plasma processing apparatus for liquid according to claim 1, wherein one of the two electrode layers constituting the plasma generating section is grounded.

4. 3. The plasma processing apparatus for liquid according to claim 2, wherein, of the four electrode layers constituting the pair of plasma generating units, no potential difference is provided between two electrode layers facing each other across the liquid flow layer.

5. 2. The plasma processing apparatus for liquid according to claim 1, wherein the outer edge of the electrode layer is sealed with an insulating member.

6. 2. The plasma processing apparatus for liquid according to claim 1, wherein at least one of the electrode layers has a plurality of through holes, and the through holes are sealed with an insulating member.

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