Plasma processing apparatus and plasma processing method

Abstract

To provide a plasma treatment device capable of continuously and efficiently treating gas with plasma and excellent in handleability and workability at the time of production.SOLUTION: Two flat electrode layers each having a dielectric layer 2 on one surface side and a support layer 3 on the other surface side are disposed with a space layer 5 interposed therebetween. The plasma treatment device has a plasma generation part 10 having a structure in which the dielectric layers 2 are arranged so as to face each other, a power supply part for applying an AC voltage between the two electrode layers, and a gas flow part capable of flowing a gas in the space layer 5, and has a plurality of through-holes 6 penetrating the electrode layers and the support layer 3 in the thickness direction, and plasma treatment is performed on the gas passing through the space layer 5 by the plasma generated by the plasma generation part 10. The plasma processing method uses the plasma processing apparatus.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a plasma processing apparatus and a plasma processing method, and more particularly to a plasma processing apparatus and a method capable of continuously plasma processing gases. [Background technology]

[0002] In recent years, a method 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 application fields of plasma processing have expanded, and it is being used in a variety of applications. The purposes of plasma processing include sterilization, deodorization, surface modification, and decomposition of chemical substances.

[0003] Various plasma processing apparatuses have been developed to perform continuous plasma processing while flowing air. For example, Patent Document 1 discloses a plasma generating apparatus in which two or more plasma generating units are stacked, each of which has a flat first electrode and a flat second electrode facing each other across a gap. Patent Document 2 also discloses an air purifier that includes a plasma generator having a structure in which electrode members, at least a portion of which is covered with a dielectric, are arranged in the thickness direction and generate plasma in the gap between adjacent electrode members, a power source that applies voltage, and a blower that blows air through the gap and releases the generated ozone along with the air. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2022-190472 [Patent Document 2] Japanese Patent Application Publication No. 2018-130208 Summary of the Invention [Problem to be solved by the invention]

[0005] Both the plasma generator described in Patent Document 1 and the air purifier described in Patent Document 2 generate plasma in a slit-shaped space sandwiched between multiple metal layers and dielectric layers, and plasma treat the air flowing through the space. However, both devices have a structure in which multiple metal layers, dielectric layers, and gap spaces are stacked, and during manufacturing, the process of stacking each thin layer in order must be repeated many times, resulting in poor handling and workability during manufacturing.

[0006] The present invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to provide a plasma processing apparatus that can continuously and efficiently process gases with plasma and that is easy to handle and operate during manufacturing. [Means for solving the problem]

[0007] Manufacturing a plasma generation unit for a plasma processing apparatus requires carefully stacking relatively thin materials, such as electrode layers and dielectric layers, with uniform thicknesses. The inventors discovered that by configuring the plasma generation unit with a support layer, it becomes easier to sequentially stack the electrode layers, dielectric layers, and other layers on top of the support layer, thereby resolving the above-mentioned problems encountered during the manufacture of a plasma processing apparatus. Furthermore, the inventors discovered that forming multiple through-holes that penetrate the electrode layer and support layer in the thickness direction facilitates plasma generation in the spatial layer, enabling efficient plasma processing of gases. It is believed that this is because the through-holes formed in the electrode layer have sharp edges at their ends, which facilitate plasma generation. Here, the through-holes penetrate the stacked electrode layer and support layer in the thickness direction, but do not penetrate the dielectric layer. Therefore, the gas to be plasma-processed flows through the spatial layer sandwiched between two opposing dielectric layers without through-holes. The present invention has been completed through the above-mentioned investigations, and has the following features.

[0008] (1) A plasma processing apparatus having a plasma generation unit having a structure in which two flat electrode layers each having a dielectric layer on one side and a support layer on the other side are arranged with a space layer between them so that the dielectric layers face each other, a power supply unit that applies an AC voltage between the two electrode layers, and a gas flow unit that can flow gas through the space layer, wherein the plasma processing apparatus has a plurality of through holes that penetrate the electrode layer and the support layer in the thickness direction, and the gas passing through the space layer is plasma-processed using plasma generated in the plasma generation unit. (2) The plasma processing apparatus according to (1), wherein a cross section of the electrode layer is exposed to the outside within the through-hole. (3) The total perimeter of the plurality of through holes on the plane of the electrode layer is equal to or less than 1 cm of the area occupied by the electrode layer without the through holes. 2 The plasma processing apparatus according to (1) or (2), characterized in that the thickness is 0.5 cm or more. (4) A plasma processing apparatus according to (1) or (2), characterized in that not only the gas passing through the spatial layer but also the gas passing through the outer space is plasma-treated by flowing gas into the space outside the support layer. (5) The plasma processing apparatus according to (1) or (2), wherein the plasma generating section has a flat or curved surface. (6) The plasma processing apparatus according to (1) or (2), wherein the gas contains carbon dioxide, and the carbon dioxide is subjected to plasma processing to generate carbon monoxide. (7) A plasma processing method, characterized in that a gas passing through the spatial layer is plasma-processed using the plasma processing apparatus according to (1) or (2). (8) The plasma processing method according to (7) above, wherein the gas contains carbon dioxide, and the carbon dioxide is subjected to plasma processing to generate carbon monoxide. [Effects of the Invention]

[0009] The plasma processing apparatus of the present invention is capable of continuously and efficiently processing gases with plasma, and is excellent in handleability and workability during manufacturing. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a schematic perspective view of a plasma generating unit of a plasma processing apparatus according to an embodiment of the present invention; [Figure 2] FIG. 2 is a schematic cross-sectional view of the plasma generating unit of FIG. 1 taken along the line AA. [Figure 3] FIG. 3 is a schematic cross-sectional view of the plasma generating unit of FIG. 1 taken along the line BB. [Figure 4] 4A and 4B are schematic plan views showing through holes in a plasma generating unit of a plasma processing apparatus according to this embodiment. Fig. 4A shows a pattern in which many oblong shapes, each longer in the gas flow direction than in the direction perpendicular to the gas flow direction, are arranged in parallel. Fig. 4B shows a pattern in which many circles are arranged in a regular pattern vertically and horizontally. Fig. 4C shows a pattern in which many rectangles, each shorter in the gas flow direction than in the direction perpendicular to the gas flow direction, are arranged in parallel. Fig. 4D shows a pattern in which many squares are arranged in a regular pattern vertically and horizontally. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, embodiments of the present invention will be described in detail, but the embodiments of the present invention are not limited to the specific embodiments described below. The embodiments can be applied in appropriate combinations. Furthermore, terms indicating directions such as "up and down" and "left and right" in the description are used for convenience of explanation and do not limit the directions of the present invention.

[0012] The plasma generation unit of the plasma processing apparatus of this embodiment has a structure in which two flat electrode layers, each having a dielectric layer on one side and a support layer on the other side, are arranged so that the dielectric layers face each other with a space between them. The plasma processing apparatus of this embodiment also has a power supply unit that applies an AC voltage between the two opposing electrode layers to generate plasma in the space. The plasma processing apparatus of this embodiment also has a gas flow unit that can flow gas through the space to process the gas with plasma.

[0013] Dielectric barrier discharge can be classified into a single-barrier discharge type in which a dielectric layer is provided on only one of the electrodes, and a double-barrier discharge type in which a dielectric layer is provided on both of the electrodes. The plasma processing apparatus of this embodiment is a plasma processing apparatus using the double-barrier discharge type. That is, the plasma processing apparatus of this embodiment has a structure in which a dielectric layer is provided on one side of each of two electrode layers, facing the space layer between the two electrode layers. The plasma processing apparatus of this embodiment generates plasma in the space layer sandwiched between the two dielectric layers.

[0014] The plasma processing apparatus of this embodiment has a dielectric layer between each of the two electrode layers, which prevents localized concentration of plasma between the electrode layers and allows for uniform plasma generation in the space between the electrode layers. This also reduces the risk of localized temperature rise in the space between the electrode layers, allowing for stable generation of low-temperature plasma.

[0015] Furthermore, when electrons, ions, radicals, etc. in the plasma present in the space between the electrode layers collide with neutral particles, the neutral particles are excited. The excited neutral particles may then emit light when returning to their ground state. As a result, purple visible light or ultraviolet light may be observed from the plasma processing apparatus of this embodiment.

[0016] Fig. 1 is a schematic perspective view of a plasma generating unit 10 of a plasma processing apparatus according to this embodiment. Fig. 2 is a schematic cross-sectional view of the plasma generating unit taken along line AA in Fig. 1. Fig. 3 is a schematic cross-sectional view of the plasma generating unit taken along line BB in Fig. 1. Fig. 3 is a BB cross section of the plasma generating part in Fig. 1, which is a schematic cross section of a portion where a through-hole 6, which will be described later, does not exist. On the other hand, Fig. 2 is an AA cross section of the plasma generating part in Fig. 1, which is a schematic cross section of a portion where a through-hole 6, which will be described later, exists.

[0017] The spatial layer 5 is a space that communicates in the shape of a slit from the gas inlet of the plasma generation unit 10 to the gas outlet. In FIG. 1, as indicated by the arrows, the gas inlet is at the back of the page in the upper right corner and the gas outlet is at the front of the page in the lower left corner. Plasma can be generated in the spatial layer 5 by applying an AC voltage between two electrode layers 11 located above and below (see FIG. 3). By flowing gas into the spatial layer 5 from one inlet, the gas is plasma-treated in the spatial layer 5 and is discharged from the other outlet of the spatial layer 5.

[0018] 1 to 3, spacers 4 are installed on both sides of the gas flow path in the space layer 5. That is, the space layer 5 has a cross-sectional shape that is partitioned from above and below by the dielectric layer 2 and from below and by the spacers 4. The spacers 4 play a role in maintaining the shape of the space layer 5 so that the space layer 5 can be maintained at a predetermined height. The height of the space layer 5 can be adjusted by changing the height of the spacer 4. The height of the space layer 5 is not particularly limited, but from the viewpoint of increasing the efficiency of the plasma treatment, it is preferably 0.5 to 20 mm, and more preferably 1 to 10 mm.

[0019] 1 to 3, the electrode layers 11 are preferably sealed at their peripheral end faces (outer edges) with an insulating member 1. That is, the insulating member 1 serves to insulate the electrode layers 11, 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. The insulating member 1 also prevents short-circuiting between the two electrode layers 11, to which an AC voltage is applied, via the peripheral end faces or surfaces of other members.

[0020] 1 and 2 show a plurality of through holes 6 that penetrate adjacent electrode layers 11 and support layers 3 in the thickness direction. In Fig. 1, the through holes 6 have a pattern in which four oblong through holes 6 are arranged in parallel, and each of the through holes 6 has a length in the gas flow direction that is longer than the length in the direction perpendicular to the gas flow direction.

[0021] Here, the through holes 6 penetrate the stacked electrode layer 11 and support layer 3 in the thickness direction, but do not penetrate the dielectric layer 2 (see FIG. 2). Therefore, within the through holes 6, a surface 7 of the dielectric layer 2 opposite the space layer 5 is exposed to the outside. Also, within the through holes 6, a cross-sectional portion 8 of the electrode layer 11 is exposed to the outside. Similarly, a cross-sectional portion 9 of the support layer 3 is exposed to the outside. Meanwhile, the gas to be plasma processed flows through the space layer 5 sandwiched between two opposing dielectric layers 2 that do not have through holes 6 and are smooth.

[0022] The present inventors fabricated a prototype plasma generating unit 10 having a plurality of through holes 6 penetrating the electrode layer 11 and the support layer 3 in the thickness direction, as shown in Fig. 1, and measured its performance, finding that plasma is more easily generated in the space layer 5, enabling efficient plasma treatment of gas. It is presumed that this is because when the through holes 6 are formed in the electrode layer 11, there are sharp edges near the cross-sections 8 of the electrode layer 11 within the through holes 6, making it easier for plasma to be generated in the space layer 5.

[0023] Furthermore, when there are multiple through holes 6 penetrating the electrode layer 11 and the support layer 3, the back surface 7 of the dielectric layer 2 and the cross-section 8 of the electrode layer 11 are exposed to the outside within the through holes 6. This causes a phenomenon in which part of the plasma generated in the plasma generating unit 10 leaks out through the back surface 7 of the dielectric layer 2 and the cross-section 8 of the electrode layer 11. As a result, part of the plasma generated in the plasma generating unit 10 spreads to the space above the support layer 3 above the plasma generating unit 10 and the space below the support layer 3 below the plasma generating unit 10, making it possible to plasma treat gas present in the space outside the plasma generating unit 10. Therefore, if a gas flow section is used that is configured to allow gas to flow not only through the space layer 5 but also through the space outside the support layer 3, it becomes possible to plasma treat not only the gas passing through the space layer 5 but also the gas passing through the outer space (not shown).

[0024] A large number of through holes 6 and a large area of ​​the through holes 6 are preferable because the amount of cross-sectional area 8 of the electrode layer 11 inside the through holes 6 increases, thereby increasing the amount of plasma generated. Furthermore, although the shape and pattern of the through holes 6 are not particularly limited, it is preferable that the through holes 6 are formed uniformly in the same pattern over the entire surface of the electrode layer 11, because this prevents localization of the amount of plasma generated and makes it uniform over the entire electrode layer 11.

[0025] 4 is a schematic plan view of the plasma generating unit 10, showing several typical examples of the planar shape of the through-hole 6. The planar shape of the through-hole 6 indicates the shape of the back surface 7 exposed to the outside of the dielectric layer 2 formed on the plasma generating unit 10, and also indicates the shape of the exposed cross-sectional portion of the electrode layer 11 inside the through-hole 6.

[0026] Figure 4(a) shows a pattern in which many oblong shapes, each longer in the direction of gas flow than in the direction perpendicular to the gas flow, are arranged in parallel. Figure 4(b) shows a pattern in which many circles are arranged in a regular pattern both vertically and horizontally. Figure 4(c) shows a pattern in which many rectangles, each shorter in the direction of gas flow than in the direction perpendicular to the gas flow, are arranged in parallel. Figure 4(d) shows a pattern in which many squares are arranged in a regular pattern both vertically and horizontally.

[0027] A large number of through holes 6 and a large area of ​​the through holes 6 are preferable because the length of the cross section 8 of the electrode layer 11 inside the through holes 6 increases, which increases the amount of plasma generated. Therefore, various types of plasma generating units 10 with different numbers and shapes of through holes 6 were fabricated and the relationship with the plasma processing performance was evaluated. As a result, the total (average) perimeter length of the through holes 6 per unit area on the plane of the electrode layer 11 was measured, and it was found that the area occupied by the electrode layer 11 without the through holes 6 was 1 cm. 2 It has been found that the total perimeter of each through hole is preferably 0.5 cm or more, more preferably 1 cm or more, even more preferably 2 cm or more, and most preferably 3 cm or more.

[0028] Furthermore, it has been found that the total area (average value) occupied by the through holes 6 on the plane of the electrode layer 11 is preferably 20% or more of the area occupied by the electrode layer 11 in a state where the through holes 6 are not present. The total area occupied by the through holes 6 is more preferably 30% or more, and even more preferably 40% or more.

[0029] There are no particular restrictions on the number or planar shape of the through holes 6. The number and shape can be selected appropriately depending on the purpose of the plasma treatment, the effect of the plasma treatment, etc. Furthermore, the planar shape patterns of the through holes 6 on the front and back sides of the plasma generating unit 10 can be the same or different. Furthermore, in the plasma generating unit 10, the through holes 6 can be formed on both the upper (front) and lower (back) sides, or on only one side.

[0030] When it is desired to increase the plasma processing amount per unit time by increasing the cross-sectional area of ​​the space layer 5, a plurality of plasma generating parts 10 shown in Figures 1 to 3 can be stacked in the thickness direction. There is no limit to the number of layers that can be stacked. When a plurality of plasma generating units 10 are stacked in the thickness direction, two support layers 3 overlap between adjacent plasma generating units 10. In this case, the support layer 3 between the adjacent plasma generating units 10 may be shared as one, simplifying the layer configuration of the multilayer structure. Similarly, when a plurality of plasma generating units 10 are stacked in the thickness direction, the support layer 3 and the electrode layer 11 overlap between adjacent plasma generating units 10. In this case, one support layer 3 and one electrode layer 11 between adjacent plasma generating units 10 may be omitted, and the intermediate portions of the adjacent plasma generating units 10 may be configured as dielectric layer 2-electrode layer 11-dielectric layer 2, with the electrode layer 11 being shared by the upper and lower plasma generating units 10, thereby simplifying the layer configuration of the multilayer structure (not shown).

[0031] In this embodiment, the purpose of plasma treatment is various, such as sterilization, deodorization, surface modification, decomposition of chemical substances, etc., and there are no particular limitations on the gas to be treated. Furthermore, the treatment time and strength of the gas flow can be adjusted appropriately by changing the flow rate and the strength and frequency of the applied AC voltage depending on the purpose and application.

[0032] The electrode layer 11 is made of a conductive material, and may be made of a metal plate (including metal foil), conductive paint, conductive polymer, conductive film, etc., but is preferably a metal plate. Preferred metal materials include copper, aluminum, stainless steel, and iron, which have excellent conductivity. Of these, copper is more preferred from the standpoints of conductivity and cost.

[0033] The surface of the electrode layer 11 on one side having the dielectric layer 2 is preferably smooth. If the surface of the electrode layer 11 is smooth, it becomes a so-called solid flat plate, and plasma generated when an AC voltage is applied between the two electrode layers 11 is less likely to be localized in some places, allowing uniform plasma to be generated in the spatial layer 5. If the surface of the electrode layer 11 is uneven, localized discharge may occur more easily from the convex parts, raising the concern that plasma generation may be localized.

[0034] Furthermore, if the surface of the electrode layer 11 is smooth, it becomes possible to repeatedly reflect the visible light and ultraviolet light generated in the space layer 5 between the two electrode layers 11, thereby further enhancing the treatment effect of irradiating the gas to be treated with visible light and ultraviolet light. In order to improve the smoothness of the surface of the electrode layer 11, it is preferable that a metal layer is formed on the surface by plating or vapor deposition. The type of metal is gold, silver, aluminum, or the like. The thickness of the electrode layer 11 is not particularly limited, but in order to obtain a lightweight and compact processing device, it is preferably 10 μm to 1 mm, more preferably 10 μm to 0.2 mm, and even more preferably 10 μm to 0.1 mm.

[0035] The material constituting the dielectric layer 2 must be an insulating material so as to prevent easy discharge between the two electrode layers 11. Furthermore, since the material constituting the dielectric layer 2 will be exposed to the plasma generated in the spatial layer 5, it is preferable that the material be durable against the active substances generated in the plasma. Specific examples of materials constituting the dielectric layer 2 include glass, ceramics, and synthetic resins. Examples of glass include soda-lime glass (soda glass), borosilicate glass, quartz glass, lead glass, and oxide glass. Examples of ceramics include alumina, silica, titanium oxide, and zinc oxide. Examples of synthetic resins include thermoplastic resins and thermosetting resins. 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. Thermosetting resins include phenolic resin, melamine resin, urea resin, alkyd resin, epoxy resin, unsaturated polyester resin, and polyurethane resin. Among these, it is preferable that the material is mainly composed of glass or silicone resin, where "mainly" means that the component composition is 50% by mass or more (the same applies hereinafter). The thickness of the dielectric layer 2 is not particularly limited, but is preferably 0.1 to 5 mm, more preferably 0.1 to 1 mm, in order to obtain a lightweight and compact processing device.

[0036] The material constituting the spacer 4 also needs to be an insulating material so as to prevent easy discharge between the two electrode layers 11. Furthermore, since the material constituting the spacer 4 will be exposed to the plasma generated in the spatial layer 5, it is preferable that the material be durable against the active substances generated in the plasma. Specific examples of the material constituting the spacer 4 include glass, ceramics, and synthetic resins. Specific examples of glass, ceramics, and synthetic resins are the same as those of the material constituting the dielectric layer 2. Specific examples of the material constituting the insulating member 1 include the synthetic resins described as the material constituting the dielectric layer 2, and an adhesive that bonds the electrode layer 11 (described below) to the dielectric layer 2. Specific examples of the synthetic resins are the same as those of the synthetic resins constituting the dielectric layer 2.

[0037] The support layer 3 is a layer that supports the structure of the plasma generating part 10, and is a layer that maintains the shape of the plasma generating part 10 and stabilizes the shape. An insulating material is used for the support layer 3. The insulating material is not particularly limited, but it is preferable to use a synthetic resin to improve handling and provide appropriate flexibility. As with the synthetic resins used as the material for the dielectric layer 2, examples of the synthetic resin include thermoplastic resins such as general-purpose resins, engineering plastics, and super engineering plastics, and thermosetting resins. Among these, thermosetting resins such as silicone resins, phenolic resins, melamine resins, urea resins, alkyd resins, epoxy resins, unsaturated polyester resins, and polyurethane resins are preferred. Among thermosetting resins, epoxy resins are preferred because they are easy to handle and inexpensive. In order to reinforce the synthetic resin, it is preferable to add a filler to the synthetic resin, such as glass fiber, carbon fiber, aramid fiber, whisker, or cellulose fiber, or inorganic particles such as calcium carbonate, silica, talc, mica, clay, alumina, or kaolin.

[0038] Among these, composites using epoxy resin, phenolic resin, or polyimide resin as the synthetic resin and glass fiber or cellulose fiber (paper) as the filler are preferred. Furthermore, composites mainly made of glass fiber and epoxy resin are even more preferred. Specific examples include so-called printed wiring boards, such as glass-epoxy substrates made of glass fiber and thermosetting epoxy resin, paper-phenolic substrates made of paper and phenolic resin, polyimide resin substrates, and liquid crystal polymer substrates. Copper-clad laminates, in which these substrates are bonded with copper foil, are particularly preferred because the copper foil can be used as is as the electrode layer 11 of this embodiment.

[0039] The electrode layer 11 and the dielectric layer 2 that constitute the plasma generating unit 10 are both thin layers, making them difficult to handle and work with. For example, when laminating the electrode layer 11 and the dielectric layer 2, both layers are thin and weak, and are prone to wrinkling, air bubbles, and cracks due to deflection under their own weight when laminating and pressing together or when applying adhesive. On the other hand, the support layer 3 of this embodiment is flexible enough to bend to a certain extent, so it can absorb the distortion of each layer and laminate the electrode layer 11 and the dielectric layer 2 while bending the support layer 3. As a result, wrinkling, air bubbles, and cracks can be reduced when laminating and pressing together or when applying adhesive.

[0040] In this way, in this embodiment, by providing the support layer 3, the handleability and workability of the electrode layer 11 and the dielectric layer 2 that constitute the plasma generation section 10 are improved, making it possible to manufacture the plasma processing apparatus efficiently and with a high yield.

[0041] The plasma generating unit 10 of this embodiment may be flat or curved. By appropriately selecting the type and thickness of materials constituting the plasma generating unit 10, such as the support layer 3, electrode layer 11, and dielectric layer 2, the multilayer structure can be bent. The dimensions and shape of the plasma generating unit 10 must be adapted to various requirements, depending on the purpose and application of the plasma processing, the type of gas, and the like. This embodiment offers a high degree of freedom in the selection of the constituent materials and excellent handling and workability during manufacturing, making it possible to form various shapes according to desired needs. Curved shapes can also be cylindrical, conical, spiral, U-shaped, W-shaped, and other shapes.

[0042] The electrode layer 11 and the dielectric layer 2 may be laminated without using an adhesive, or may be bonded with an adhesive. Because the adhesive is in close proximity to the plasma generated in the spatial layer 5, a material that is durable against the active substances generated in the plasma is preferred. Adhesives include epoxy-based, acrylic-based, urethane-based, phenol-based, urea-based, melamine-based, silicone-based, cyanoacrylate-based, rubber-based, and vinyl acetate-based adhesives. Of these, silicone-based adhesives and UV-curable epoxy-based adhesives are preferred from the standpoint of durability, with silicone-based adhesives being more preferred. The thickness of the adhesive layer is preferably 0.01 to 0.2 mm, more preferably 0.01 to 0.1 mm.

[0043] Since plasma processing equipment is subject to temperature changes during use, if there is a large difference in the thermal expansion coefficient between the materials constituting the multilayer structure, there is a concern that problems such as peeling may occur over time. Therefore, it is preferable that the materials and adhesives constituting the dielectric layer 2 and support layer 3 laminated with the electrode layer 11 are highly flexible materials that can follow dimensional changes in the electrode layer 11. Synthetic resin-based materials are preferred as such materials, and it is preferable to select and use an appropriate material from among synthetic resin-based materials.

[0044] To manufacture the plasma generation section 10 of the plasma processing apparatus of this embodiment, it is necessary to carefully stack materials such as the support layer 3, electrode layer 11, dielectric layer 2, spacer 4, and insulating member 1 in order.

[0045] The power supply unit (not shown) of this embodiment applies an AC voltage between two electrode layers 11 facing each other across the spatial layer 5 in order to generate plasma in the spatial layer 5. There are no particular restrictions on the specific contents of the power supply unit, and any known power supply device can be used as long as it can apply an AC voltage of a predetermined voltage at a predetermined frequency to the two electrode layers 11 of the plasma generating unit 10. The frequency of the AC voltage is preferably 50 Hz to 30 MHz, more preferably 50 Hz to 100 kHz, and the AC voltage is preferably 1 to 50 kV, more preferably 2 to 10 kV.

[0046] The gas flow unit (not shown) of this embodiment is not particularly limited as long as it is a device that can cause a gas to flow through the spatial layer 5 in order to treat the gas with plasma. As shown in Fig. 1, a gas is supplied to the spatial layer 5 from one side of the plasma generation unit 10, and the gas is discharged from the spatial layer 5 on the other side of the plasma generation unit 10. It is preferable that the gas discharged from the spatial layer 5 can be discharged to the outside. As a driving device for moving the gas, a known device such as a centrifugal blower (such as a sirocco fan, a radial fan, or a turbo fan), an axial flow blower (such as a propeller fan), a mixed flow blower (such as a line fan), a cross flow blower, or a blower can be appropriately used.

[0047] Functions exhibited by performing plasma treatment using the plasma treatment apparatus of this embodiment include sterilization, virus inactivation, deodorization, surface modification, decomposition of chemical substances, and decomposition of carbon dioxide. The mechanism by which these functions are exhibited is thought to be that plasma treatment generates reactive oxygen species (Reactive Oxygen Species) such as singlet oxygen, hydrogen peroxide, OH radicals, superoxide, peroxy radicals, and ozone in the gas, which then kill or inactivate target microorganisms or decompose or modify chemical substances through oxidation reactions or the like. Examples of microorganisms include various bacteria, viruses, and mold.

[0048] In the plasma processing apparatus of this embodiment, the gas that has passed through the space layer 5 and been plasma-processed is subjected to sterilization, deodorization, etc. by killing or inactivating microorganisms present in the gas and decomposing chemical substances due to active species generated by the plasma while passing through the space layer 5. Furthermore, in the plasma processing apparatus of this embodiment, some active species do not disappear but remain (remain) in the gas that has been plasma-processed after passing through the spatial layer 5. Therefore, by spraying the gas that has been plasma-processed after passing through the plasma processing apparatus of this embodiment onto an object, microorganisms present in the object can be killed or inactivated, and chemical substances can be decomposed, thereby sterilizing, inactivating, deodorizing, etc. the object. Furthermore, the gas that has been plasma-treated using the plasma processing apparatus of this embodiment and that contains some active species can be mixed with a liquid such as water to produce a liquid containing plasma-activated species, which can be used for sterilizing, inactivating, deodorizing, etc., objects.

[0049] The plasma processing apparatus of this embodiment can be used to decompose chemical substances by performing plasma processing. In particular, by performing plasma processing on a gas containing carbon dioxide using the plasma processing apparatus of this embodiment, it is possible to decompose the carbon dioxide to generate carbon monoxide and convert it into a gas containing carbon monoxide. This can contribute to reducing carbon dioxide, which is a cause of global warming.

[0050] By utilizing these functions, the plasma processing apparatus of this embodiment can be used for purposes such as deodorization, odor removal, sterilization, disinfection, infection prevention, gas purification, and water purification in many industrial fields such as medicine (fiberscopes, endoscopes, various small cameras, etc.), housing, civil engineering, construction, agriculture, fisheries, livestock farming, food processing, transportation, storage, and retail. [Example]

[0051] An experiment was conducted to plasma treat carbon dioxide using the plasma treatment apparatus of this embodiment. (1) Measuring equipment A plasma processing casing having the plasma generating unit shown in FIG. 1 inside and having a gas inlet and gas outlet to the spatial layer, a power supply unit (neon transformer, variac), a small high-pressure carbon dioxide cylinder, a carbon dioxide regulator with an integrated low-flow solenoid valve, a portable carbon monoxide concentration meter, and a polyurethane pressure-resistant tube. (2) Processing conditions Carbon dioxide gas (99 vol% or more) was supplied from a high-pressure carbon dioxide cylinder via a carbon dioxide regulator and a pressure-resistant tube to the gas inlet of the plasma processing enclosure (gas flow rate 5 L / min). Plasma processing of carbon dioxide gas was performed at room temperature with a voltage of 6 kV. The carbon monoxide concentration of the gas discharged from the gas outlet was measured using a carbon monoxide concentration meter via a pressure-resistant tube. (3) Processing results At room temperature, the carbon monoxide concentration was recorded as 60 ppm approximately 1 minute after the start of plasma treatment with carbon dioxide gas, and as 660 ppm approximately 3 minutes after the start of plasma treatment.

[0052] As can be seen from the above description, the plasma processing apparatus of this embodiment has the following features. (1) The plasma processing apparatus of the present invention can continuously and efficiently process gases with plasma. (2) The plasma processing apparatus of the present invention can be manufactured with high yield by improving the handling and workability during manufacturing. (3) The plasma processing apparatus of the present invention can reduce the thickness of the dielectric layer, thereby reducing the energy required for plasma processing. (4) The plasma processing apparatus of the present invention can be made smaller in size. [Explanation of symbols]

[0053] 1. Insulating material 2. Dielectric Layer 3 Support layer 4 spacers 5 Spatial layer 6 through holes 10 Plasma generation unit 11 Electrode layer

Claims

1. a plasma generating unit having a structure in which two flat electrode layers each having a dielectric layer on one side and a support layer on the other side are arranged with a space layer sandwiched between them so that the dielectric layers face each other; a power supply unit that applies an AC voltage between the two electrode layers; a gas flow unit that can flow a gas through the spatial layer, a plurality of through holes penetrating the electrode layer and the support layer in a thickness direction; A plasma processing apparatus, characterized in that a gas passing through the spatial layer is plasma-processed by the plasma generated in the plasma generating unit.

2. 2. The plasma processing apparatus according to claim 1, wherein a cross section of the electrode layer is exposed to the outside within the through hole.

3. The total perimeter of the plurality of through holes on the plane of the electrode layer is 1 cm ２ 3. The plasma processing apparatus according to claim 1, wherein the thickness of the surface is 0.5 cm or more.

4. 3. The plasma processing apparatus according to claim 1, wherein not only the gas passing through the space layer but also the gas passing through the outer space is plasma-processed by flowing gas into the space outside the support layer.

5. 3. The plasma processing apparatus according to claim 1, wherein the plasma generating section has a flat surface or a curved surface.

6. 3. The plasma processing apparatus according to claim 1, wherein the gas contains carbon dioxide, and the carbon dioxide is subjected to a plasma processing to generate carbon monoxide.

7. 3. A plasma processing method, comprising: using the plasma processing apparatus according to claim 1 or 2 to plasma-process a gas passing through the spatial layer.

8. 8. The plasma processing method according to claim 7, wherein the gas contains carbon dioxide, and the carbon dioxide is subjected to a plasma processing to generate carbon monoxide.

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