Plasma processing equipment 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. In particular, it relates to a plasma processing apparatus and a method thereof that can continuously perform plasma processing on a gas.

Background Art

[0002] In recent years, regarding plasma processing technology, a technique called dielectric barrier discharge (DBD) has been developed, making it possible to generate low-temperature plasma under atmospheric pressure. As a result, the application fields of plasma processing have expanded and are being increasingly used in various applications. The purposes of plasma processing include sterilization, deodorization, surface modification, decomposition of chemical substances, etc.

[0003] In order to continuously perform plasma processing while flowing air, various plasma processing apparatuses have been developed. For example, Patent Document 1 discloses a plasma generator in which two or more plasma generation units are stacked and arranged such that a flat plate-shaped first electrode and a second electrode are provided to face each other with a gap therebetween. Further, Patent Document 2 discloses a plasma generator having a structure in which electrode members at least partially covered with a dielectric are arranged side by side in the thickness direction and generating plasma in a gap between adjacent electrode members, an air cleaner including a power supply for applying a voltage, and a blowing means for flowing air through the gap and discharging the generated ozone together with the air.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems 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 then plasma-treat the air flowing through that space. However, both devices have a structure in which many metal layers, dielectric layers, and gaps are stacked, and during manufacturing, it is necessary to repeatedly stack each thin layer in sequence, resulting in poor handling and workability during manufacturing.

[0006] This invention has been made in view of the above circumstances. Specifically, the object of this invention is to provide a plasma processing apparatus that can continuously and efficiently perform plasma processing on gases and has excellent handling and workability during manufacturing. [Means for solving the problem]

[0007] To manufacture the plasma generation section of a plasma processing apparatus, it is necessary to carefully stack relatively thin materials such as electrode layers and dielectric layers to a uniform thickness. The inventors have found that by making the plasma generation section have a support layer, it becomes easier to stack electrode layers, dielectric layers, etc. sequentially based on the support layer, thereby solving the above problem in the manufacturing of the plasma processing apparatus. Furthermore, the inventors have found that by forming multiple through-holes that penetrate the electrode layer and the support layer in the thickness direction, plasma is more easily generated in the space layer, making it possible to efficiently plasma-treat gases. It is presumed that when through-holes are formed in the electrode layer, sharp edges exist at the ends of the through-holes, making it easier for plasma to be generated. Here, the through-holes penetrate the stacked electrode layer and support layer in the thickness direction, but not the dielectric layer. Therefore, the gas to be plasma-treated flows through the space layer sandwiched between two opposing dielectric layers in which no through-holes are formed. This invention was completed after the above-mentioned considerations. In other words, this invention has the following configuration.

[0008] (1) A plasma processing apparatus 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 in between 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 electrode layer and the support layer have a plurality of through holes that penetrate in the thickness direction, and the plasma generated in the plasma processing unit processes the gas passing through the space layer. (2) The plasma processing apparatus according to (1), characterized in that the cross-section of the electrode layer is exposed to the outside within the through hole. (3) The sum of the perimeter lengths of the multiple through holes on the plane of the electrode layer equals the area occupied by the electrode layer without through holes in a 1 cm² area 2 The plasma processing apparatus according to (1) or (2) above, characterized in that the area is 0.5 cm or more per unit. (4) The plasma processing apparatus according to (1) or (2) above, characterized in that not only the gas passing through the space layer, but also the gas passing through the space outside the support layer is subjected to plasma treatment. (5) The plasma processing apparatus according to (1) or (2) above, characterized in that the plasma generation section is planar or curved. (6) The plasma processing apparatus according to (1) or (2) above, characterized in that the gas contains carbon dioxide and carbon monoxide is produced by plasma treatment of the carbon dioxide. (7) A plasma treatment method characterized by performing plasma treatment on a gas passing through the space layer using the plasma treatment apparatus described in (1) or (2) above. (8) The plasma treatment method according to (7), characterized in that the gas contains carbon dioxide and carbon monoxide is produced by plasma treatment of the carbon dioxide. [Effects of the Invention]

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

[0010] [Figure 1] This is a schematic perspective view of the plasma generation section of the plasma processing apparatus of this embodiment. [Figure 2] Figure 2 is a schematic cross-sectional view of the AA section of the plasma generation area in Figure 1. [Figure 3] Figure 3 is a schematic cross-sectional view of the BB cross-section of the plasma generation section in Figure 1. [Figure 4] This is a schematic plan view showing the through-holes in the plasma generation section of the plasma processing apparatus of this embodiment. Figure 4(a) shows a pattern in which many elongated ellipses, whose length in the gas flow direction is longer than their length perpendicular to the gas flow direction, are arranged in parallel. Figure 4(b) shows a pattern in which many circles are arranged regularly in a vertical and horizontal direction. Figure 4(c) shows a pattern in which many rectangles, whose length in the gas flow direction is shorter than their length perpendicular to the gas flow direction, are arranged in parallel. Figure 4(d) shows a pattern in which many squares are arranged regularly in a vertical and horizontal direction. [Modes for carrying out the invention]

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

[0012] The plasma generation section 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 with a space layer in between, so that the dielectric layers face each other. The plasma processing apparatus of this embodiment also has a power supply section that applies an AC voltage between the two opposing electrode layers in order to generate plasma in the space layer. The plasma processing apparatus of this embodiment also has a gas flow section that can flow gas through the space layer in order to process the gas with plasma.

[0013] Dielectric barrier discharge can be classified into a single-barrier discharge method, in which a dielectric layer is placed on only one of the two electrodes, and a double-barrier discharge method, in which dielectric layers are placed on both electrodes. The plasma processing apparatus of this embodiment is a plasma processing apparatus of the double-barrier discharge method. That is, the plasma processing apparatus of this embodiment has a structure in which a dielectric layer is provided on one side of the space layer between the two electrode layers for each of 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 suppresses localized concentration of plasma generated between the electrode layers and makes the plasma generation in the space between the electrode layers more uniform. Furthermore, it reduces the temperature rise that may occur locally in the space between the electrode layers, enabling the stable generation of low-temperature plasma.

[0015] Furthermore, when electrons, ions, radicals, etc., in the plasma present in the space between electrode layers collide with neutral particles, the neutral particles are excited. When these excited neutral particles return to their ground state, they may emit light. Therefore, purple visible light and ultraviolet light emission may be observed from the plasma processing apparatus of this embodiment.

[0016] FIG. 1 is a schematic perspective view of a plasma generation unit 10 of the plasma processing apparatus according to the present embodiment. FIG. 2 is a schematic cross-sectional view of an A-A cross-section of the plasma generation unit of FIG. 1. FIG. 3 is a schematic cross-sectional view of a B-B cross-section of the plasma generation unit of FIG. 1. FIG. 3 is a schematic cross-sectional view of a B-B cross-section of the plasma generation unit of FIG. 1, showing a location where the through-hole 6 described later does not exist. On the other hand, FIG. 2 is a schematic cross-sectional view of an A-A cross-section of the plasma generation unit of FIG. 1, showing a location where the through-hole 6 described later exists.

[0017] The space layer 5 is a space that communicates in a slit shape from the gas inlet to the gas outlet of the plasma generation unit 10. In FIG. 1, as indicated by the arrow, the back of the upper right paper surface is the gas inlet, and the front of the lower left paper surface is the gas outlet. By applying an alternating voltage between the two electrode layers 11 existing vertically, plasma can be generated in the space layer 5 (see FIG. 3). By flowing gas into the space layer 5 from one inlet of the space layer 5, the gas is plasma-treated in the space layer 5 and discharged from the other outlet of the space layer 5.

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

[0019] In Figures 1 to 3, it is preferable that the electrode layer 11 has its surrounding end face (outer edge) sealed by an insulating member 1. That is, the insulating member 1 protects the electrode layer 11, which is exposed to high temperatures and active substances when an AC voltage is applied, from the outside world and prevents deterioration. In addition, the insulating member 1 prevents the two electrode layers 11 to which the AC voltage is applied from short-circuiting via the surrounding end face or the surface of the member.

[0020] Figures 1 and 2 disclose multiple through-holes 6 that penetrate adjacent electrode layers 11 and support layers 3 in the thickness direction. In Figure 1, a pattern of through-holes 6 is disclosed in which four elongated elliptical through-holes 6 are arranged in parallel, with the length in the gas flow direction being longer than the length in the direction perpendicular to the gas flow direction.

[0021] Here, the through-hole 6 penetrates the stacked electrode layer 11 and support layer 3 in the thickness direction, but does not penetrate the dielectric layer 2 (see Figure 2). Therefore, within the through-hole 6, the surface 7 of the dielectric layer 2 opposite to the space layer 5 is exposed to the outside. Also, within the through-hole 6, the cross-sectional portion 8 of the electrode layer 11 is exposed to the outside. Similarly, the cross-sectional portion 9 of the support layer 3 is exposed to the outside. On the other hand, the gas to be plasma-treated flows through the space layer 5 sandwiched between two opposing dielectric layers 2, where no through-hole 6 is formed and there are no irregularities.

[0022] The inventors fabricated a plasma generation unit 10, as shown in Figure 1, in which multiple through-holes 6 are formed in the thickness direction of the electrode layer 11 and the support layer 3. When they measured its performance, they found that plasma was more easily generated in the space layer 5, making it possible to efficiently plasma-treat gases. The inventors presume that when through-holes 6 are formed in the electrode layer 11, sharp edges are present near the cross-sectional portion 8 of the electrode layer 11 within the through-holes 6, which makes it easier for plasma to be generated in the space layer 5.

[0023] Furthermore, if 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-sectional portion 8 of the electrode layer 11 are exposed to the outside within the through-holes 6. As a result, a phenomenon occurs in which a portion of the plasma generated in the plasma generation unit 10 leaks out to the outside through the back surface 7 of the dielectric layer 2 and the cross-sectional portion 8 of the electrode layer 11. Consequently, a portion of the plasma generated in the plasma generation unit 10 spreads into the space above the support layer 3 above the plasma generation unit 10 and the space below the support layer 3 below the plasma generation unit 10, making it possible to plasma treat the gas present in the space outside the plasma generation unit 10. Therefore, if a configuration is used for the gas flow section that allows gas to flow not only through the space layer 5 but also through the space outside the support layer 3, it becomes possible to perform plasma treatment not only on the gas passing through the space layer 5 but also on the gas passing through the outer space (not shown).

[0024] A large number of through-holes 6 and a large area of ​​through-holes 6 is preferable because it increases the amount of cross-sectional portion 8 of the electrode layer 11 within the through-holes 6, thereby increasing the amount of plasma generated. Furthermore, while the shape and pattern of the through-holes 6 are not particularly limited, it is preferable that they are uniformly formed with the same pattern across the entire surface of the electrode layer 11, as this prevents localization of the plasma generation and ensures uniformity throughout the electrode layer 11.

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

[0026] Figure 4(a) shows a pattern of many elongated ellipses arranged in parallel, where the length in the direction of gas flow is longer than the length perpendicular to the direction of gas flow. Figure 4(b) shows a pattern of many circles arranged regularly in a vertical and horizontal direction. Figure 4(c) shows a pattern of many rectangles arranged in parallel, where the length in the direction of gas flow is shorter than the length perpendicular to the direction of gas flow. Figure 4(d) shows a pattern of many squares arranged regularly in a vertical and horizontal direction.

[0027] A larger number of through-holes 6 and a larger area of ​​through-holes 6 is desirable, as it increases the length of the cross-sectional portion 8 of the electrode layer 11 within the through-holes 6, thereby increasing the amount of plasma generated. Therefore, various types of plasma generation units 10 with different numbers and shapes of through-holes 6 were prototyped and their relationship to plasma processing performance was evaluated. As a result, when the sum (average value) of the perimeter length of the through-holes 6 per unit area on the plane of the electrode layer 11 was measured, the area occupied by the electrode layer 11 without through-holes 6 was found to be 1 cm². 2 It was found that the sum of the circumferences of the through-holes is preferably 0.5 cm or more. More preferably the sum of the circumferences of the through-holes is 1 cm or more, even more preferably 2 cm or more, and most preferably 3 cm or more.

[0028] Furthermore, it was 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 without the through holes 6. More preferably, the total area occupied by the through holes 6 is 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 appropriately selected and implemented according to the purpose and effect of the plasma treatment. Furthermore, the planar shape patterns of the through-holes 6 can be the same or different on the front and back sides of the plasma generation unit 10. In addition, the surfaces of the plasma generation unit 10 that form the through-holes 6 can be both the upper (front) and lower (back) sides, or only one side.

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

[0031] In this embodiment, the purposes of plasma processing are varied, including sterilization, deodorization, surface modification, and decomposition of chemical substances, and there are no particular restrictions on the gas to be treated. Furthermore, the processing time and intensity when flowing the gas can be appropriately adjusted by changing the flow rate, the strength and frequency of the applied AC voltage, etc., according to the purpose and application.

[0032] The electrode layer 11 is composed of a conductive material, and can be a metal plate (including metal foil), conductive paint, conductive polymer, conductive film, etc., but a metal plate is preferred. Preferred metal materials include copper, aluminum, stainless steel, and iron, which have excellent conductivity. Among these, copper is more preferred in terms of conductivity and cost.

[0033] The surface of one side of the electrode layer 11 having the dielectric layer 2 is preferably smooth. When the surface of the electrode layer 11 is smooth, it becomes a so-called solid plate, and the plasma generated when an AC voltage is applied between the two electrode layers 11 is less likely to be localized in place, and a uniform plasma can be generated in the space layer 5. If there are irregularities on the surface of the electrode layer 11, discharge is more likely to occur locally from the convex parts, raising concerns that the generation of plasma will 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 visible light and ultraviolet light irradiation on the gas to be treated. To improve the surface smoothness of the electrode layer 11, it is preferable that a metal layer is formed on the surface by plating or vapor deposition. Examples of metals include gold, silver, and aluminum. The thickness of the electrode layer 11 is not particularly limited, but in order to make the processing apparatus lightweight and compact, 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 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 space layer 5, it is preferable that it be a material that is resistant to 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. Examples of thermoplastic resins include general-purpose resins such as polyolefins, 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, fluororesins, and silicone resins. Examples of thermosetting resins include phenolic resins, melamine resins, urea resins, alkyd resins, epoxy resins, unsaturated polyester resins, and polyurethane resins. Among these, it is preferable that the material is mainly composed of glass or silicone resin. Here, "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 in order to make the processing apparatus lightweight and compact, it is preferably 0.1 to 5 mm, and more preferably 0.1 to 1 mm.

[0036] The material constituting the spacer 4 must also be an insulating material 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 space layer 5, it is preferable that it be a material that is resistant to active substances generated in the plasma. Specific examples of materials constituting the spacer 4 include glass, ceramics, and synthetic resins. Specific examples of glass, ceramics, and synthetic resins are the same as those for the material constituting the dielectric layer 2. Specific examples of materials constituting the insulating member 1 include the synthetic resin described as the material constituting the dielectric layer 2, and the adhesive used to bond the electrode layer 11 and the dielectric layer 2, as described later. Specific examples of the synthetic resin are the same as those for the synthetic resin constituting the dielectric layer 2.

[0037] The support layer 3 is a layer that supports the structure of the plasma generation unit 10, and is a layer that maintains the shape of the plasma generation unit 10 and stabilizes its shape. An insulating material is used as the support layer 3. While the insulating material is not particularly limited, it is preferable to use a synthetic resin to improve handling and provide appropriate flexibility. Examples of synthetic resins include thermoplastic resins such as general-purpose resins, engineering plastics, and super engineering plastics, as well as thermosetting resins, similar to the synthetic resin used to constitute the dielectric layer 2. 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 offer excellent handling and are readily available at low cost. Furthermore, it is preferable to add fillers to the synthetic resin to reinforce it. Examples of fillers include fibers such as glass fibers, carbon fibers, aramid fibers, whiskers, and cellulose fibers, as well as inorganic particles such as calcium carbonate, silica, talc, mica, clay, alumina, and 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 of glass fiber and epoxy resin are more preferred. Specifically, examples include so-called printed circuit 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 formed by bonding these substrates with copper foil are particularly preferred because the copper foil can be used directly as the electrode layer 11 in this embodiment.

[0039] The electrode layer 11 and dielectric layer 2 that constitute the plasma generation unit 10 are both thin layers, making them difficult to handle and work with. For example, when laminating the electrode layer 11 and dielectric layer 2, both layers are thin and lack rigidity, making them prone to wrinkling, air bubbles, and cracking due to bending under their own weight when laminating and pressing them together or when applying adhesive. On the other hand, the support layer 3 of this embodiment has the flexibility to bend to a certain extent, so it can absorb the distortion of each layer, allowing the electrode layer 11 and dielectric layer 2 to be laminated while the support layer 3 is bent. As a result, it is possible to reduce the occurrence of wrinkles, air bubbles, and cracks when laminating and pressing them together or when applying adhesive.

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

[0041] The plasma generation unit 10 in this embodiment may be planar or curved. By appropriately selecting the type and thickness of materials such as the support layer 3, electrode layer 11, and dielectric layer 2 that constitute the plasma generation unit 10, it is possible to bend the multilayer structure. Depending on the purpose and application of the plasma treatment, the type of gas, etc., it is necessary to accommodate various dimensions and shapes of the plasma generation unit 10. In this embodiment, there is a high degree of freedom in selecting each constituent material, and it is also excellent in handling and workability during manufacturing, so it is possible to form various shapes according to the required needs. As for curved shapes, cylindrical, conical, spiral cross-section, U-shaped cross-section, W-shaped cross-section, etc. can be accommodated.

[0042] The electrode layer 11 and the dielectric layer 2 may be laminated without using an adhesive, or they may be bonded together with an adhesive. Since the adhesive is in close proximity to the plasma generated in the space layer 5, it is preferable that the adhesive be made of a material that is resistant to active substances generated in the plasma. Adhesives include epoxy, acrylic, urethane, phenol, urea, melamine, silicone, cyanoacrylate, rubber, and vinyl acetate types. Among these, silicone adhesives and UV-curing epoxy adhesives are preferred in terms of durability, with silicone adhesives being more preferred. The thickness of the adhesive layer is preferably 0.01 to 0.2 mm, and more preferably 0.01 to 0.1 mm.

[0043] Because plasma processing equipment experiences temperature changes during use, there is a concern that problems such as delamination may occur over time if there are large differences in the coefficients of thermal expansion between the materials constituting the multilayer structure. 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 made of highly flexible materials that can follow the dimensional changes of the electrode layer 11. As such materials, synthetic resin-based materials are preferred, and it is even more preferable to select and use an appropriate material from among synthetic resin-based materials.

[0044] In order to manufacture the plasma generation unit 10 of the plasma processing apparatus of this embodiment, it is necessary to carefully layer 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 that face each other across the space layer 5 in order to generate plasma in the space layer 5. There are no particular restrictions on the specific contents of the power supply unit; 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 generation unit 10. The frequency of the AC voltage is preferably 50Hz to 30MHz, and more preferably 50Hz to 100kHz. Furthermore, the AC voltage is preferably 1 to 50kV, and more preferably 2 to 10kV.

[0046] The gas flow section (not shown) in this embodiment is not particularly limited as long as it is a device capable of flowing gas into the space layer 5 in order to process the gas with plasma. As shown in Figure 1, gas is supplied to the space layer 5 from one side of the plasma generation section 10, and the gas is discharged from the space layer 5 on the other side of the plasma generation section 10. It is preferable to have a configuration that allows the gas discharged from the space layer 5 to be discharged to the outside. As a drive device for flowing gas, known devices such as centrifugal fans (sirocco fans, radial fans, turbo fans, etc.), axial-flow fans (propeller fans, etc.), mixed-flow fans (line fans, etc.), cross-flow fans, and blowers are used as appropriate.

[0047] The functions exhibited by performing plasma treatment using the plasma processing 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 such as singlet oxygen, hydrogen peroxide, OH radicals, superoxide, peroxyl radicals, and ozone in the gas, and these then kill or inactivate target microorganisms or decompose and modify chemical substances through oxidation reactions. Examples of microorganisms include various bacteria, viruses, and fungi.

[0048] In the plasma processing apparatus of this embodiment, the gas that has been plasma-treated after passing through the space layer 5 can be sterilized and deodorized by the active species generated by the plasma during its passage through the space layer 5, which kill or inactivate microorganisms present in the gas, or decompose chemical substances. Furthermore, in the plasma processing apparatus of this embodiment, some active species remain in the gas that has passed through the space layer 5 and been plasma-treated, rather than being eliminated. Therefore, by blowing the plasma-treated gas that has passed through the plasma processing apparatus of this embodiment onto an object, it is possible to kill or inactivate microorganisms present in the object, or decompose chemical substances, thereby sterilizing, inactivating, and deodorizing the object. Furthermore, a gas that has been plasma-treated using the plasma processing apparatus of this embodiment and contains some active species can be mixed with a liquid such as water to create a liquid containing plasma-activated active species. This liquid can then be used for sterilization, inactivation, deodorization, and other purposes.

[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 back into a gas containing carbon monoxide. This can contribute to reducing carbon dioxide, which is a cause of global warming.

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

[0051] An experiment was conducted to perform plasma treatment on carbon dioxide using the plasma processing apparatus of this embodiment. (1) Measuring device The plasma processing enclosure, which has a plasma generation unit as shown in Figure 1, and includes gas inlet and outlet ports for the space layer, a power supply unit (neon transformer, variac), a small high-pressure carbon dioxide cylinder, a low-flow solenoid valve integrated carbon dioxide regulator, a portable carbon monoxide concentration meter, and a polyurethane pressure-resistant tube. (2) Processing conditions Carbon dioxide gas (99 vol% or higher) was supplied from a high-pressure carbon dioxide cylinder through a carbon dioxide regulator and pressure-resistant tubing to the gas inlet of the plasma treatment enclosure (gas flow rate 5 L / min). Plasma treatment of carbon dioxide gas was performed at a voltage of 6 kV and room temperature. The carbon monoxide concentration of the gas discharged from the gas outlet was measured using a carbon monoxide concentration meter after passing through pressure-resistant tubing. (3) Processing results At room temperature, carbon monoxide concentrations of 60 ppm were recorded approximately 1 minute after the start of plasma treatment with carbon dioxide gas, and 660 ppm was recorded approximately 3 minutes after the start of plasma treatment.

[0052] As can be seen from the above explanation, the plasma processing apparatus of this embodiment has the following features. (1) The plasma processing apparatus of the present invention can continuously and efficiently perform plasma processing on a gas. (2) The plasma processing apparatus of the present invention improves handling and workability during manufacturing, and enables manufacturing with a high yield. (3) The plasma processing apparatus of the present invention can reduce the energy required for plasma processing because the dielectric layer can be made thinner. (4) The plasma processing apparatus of the present invention can be miniaturized. [Explanation of symbols]

[0053] 1. Insulating component 2 Dielectric layers 3 Support layer 4 Spacers 5 Spatial layer 6 Through hole 10 Plasma generation unit 11 Electrode layer

Claims

1. A plasma generation unit having a structure in which two flat electrode layers, one having a dielectric layer on one side and the other having a support layer, are arranged with a space layer in between so that the dielectric layers face each other, A power supply unit that applies an AC voltage between the two electrode layers, A plasma processing apparatus having a gas flow section capable of flowing gas through the aforementioned space layer, The electrode layer and the support layer have a plurality of through holes that penetrate in the thickness direction, A plasma processing apparatus characterized by performing plasma treatment on a gas passing through the space layer using plasma generated in the plasma generation unit.

2. The plasma processing apparatus according to claim 1, characterized in that the cross-sectional portion of the electrode layer is exposed to the outside within the through hole.

3. The sum of the perimeter lengths of the multiple through holes on the plane of the electrode layer equals the area occupied by the electrode layer without through holes in a 1 cm² area. ２ The plasma processing apparatus according to claim 1 or 2, characterized in that the area is 0.5 cm or more per unit.

4. The plasma processing apparatus according to claim 1 or 2, characterized in that not only the gas passing through the aforementioned space layer, but also the gas passing through the space outside the support layer is subjected to plasma treatment.

5. The plasma processing apparatus according to claim 1 or 2, characterized in that the plasma generation section is planar or curved.

6. The plasma processing apparatus according to claim 1 or 2, characterized in that the gas contains carbon dioxide, and carbon monoxide is produced by plasma treatment of the carbon dioxide.

7. A plasma treatment method characterized by performing plasma treatment on a gas passing through the space layer using the plasma treatment apparatus described in claim 1 or claim 2.

8. The plasma treatment method according to claim 7, characterized in that the gas contains carbon dioxide, and carbon dioxide is plasma-treated to produce carbon monoxide.

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