JP2001145689A - Plasma sterilizing treatment apparatus and plasma sterilizing treatment method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a plasma sterilizing treatment apparatus which is capable of shortening the time required for a sterilizing treatment, continuously treating a large quantity of materials to be treated and easily executing the sterilizing treatment of even the materials to be treated of large sizes and intricate shapes and is high in safety. SOLUTION: This apparatus has a cylindrical reaction tube 1 and a pair of electrodes 2 and 3. A plasma forming gas consisting of inert gas or a gaseous mixture composed of the inert gas and a reactive gas is introduced into the reaction tube 1 and an AC electric field is impressed into the reaction tube 1 in a position corresponding to the part between the electrodes 2 and 3, by which a glow discharge is generated under atmospheric pressure and a plasma P is formed from the plasma forming gas. The plasma sterilizing treatment apparatus kills fungi by supplying such plasma P to the surfaces of the materials 4 to be treated. A blow-off port 5 for blowing the plasma P formed in the reaction tube 1 in the form of a jet toward the materials 4 to be treated is formed in the reaction tube 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to foods and food containers,
The present invention relates to a plasma sterilization apparatus for sterilizing (sterilizing) medical supplies, medical materials, clothes, packaging materials, and the like with plasma and a plasma sterilization method using the same.

[0002]

2. Description of the Related Art Conventionally, many sterilizers and sterilization methods using reduced-pressure plasma which are more effective than sterilization by ultraviolet rays or ozone have been proposed. For example, JP-A-7-1
No. 84618 discloses that a container to be sterilized is placed in a vacuum container, the inside of the vacuum container is depressurized by a vacuum pump, and high-frequency power is applied to electrodes to generate plasma in the vacuum container. After sterilizing the container to be treated,
Stop the vacuum pump and open the vacuum vessel to the atmosphere,
A sterilization method in a container using plasma in which a sterilized container to be processed is removed from a vacuum container is described.

However, in this method, a process of decompression and opening is required, so that sterilization cannot be performed in a short time, and furthermore, a batch type method in which a container to be processed is introduced into a vacuum vessel and sterilization is performed. Therefore, there is a problem that a large number of containers cannot be sterilized continuously.

Japanese Patent Application No. 10-99415 discloses a method in which plasma is generated under atmospheric pressure without using a decompression process, and an object to be processed is sterilized with the plasma. However, there is a problem that a large amount of objects to be processed cannot be sterilized continuously because of the batch type in which the objects to be processed are introduced into the chamber and sterilization is performed.

On the other hand, Japanese Patent Application Laid-Open No. Hei 8-156920 describes a method in which an atmospheric pressure glow discharge is generated between a pair of electrodes facing each other and an object to be processed is positioned between the electrodes to sterilize the electrodes. . However, according to this method, the object to be processed is limited to an object having a size and a shape that can be located between electrodes set at an interval at which glow discharge can be performed at atmospheric pressure. Is difficult to sterilize.

Furthermore, sterilization with silent discharge plasma, that generates Although air has been proposed a method of sterilizing by ozone generated by the plasma by a high electric field, harmful NO and NO _2, etc. so-called NO _X in the body sub Therefore, it was low in safety and was unsuitable especially for sterilizing foods and food containers.

[0007]

DISCLOSURE OF THE INVENTION The present invention has been made in view of the above points, and can reduce the time required for sterilization and can continuously process a large number of objects to be processed. A plasma sterilization apparatus and a plasma sterilization apparatus which can easily sterilize large and complicated-shaped workpieces, and have high safety and can be suitably used for sterilizing foods and food containers. It is intended to provide a method.

[0008]

A plasma sterilization apparatus A according to a first aspect of the present invention includes a tubular reaction tube 1 and a pair of electrodes 2 and 3. A glow discharge is generated under atmospheric pressure by introducing a plasma generation gas composed of a mixed gas of an active gas and a reaction gas and applying an AC electric field into the reaction tube 1 at a position corresponding to between the electrodes 2 and 3. A plasma sterilization apparatus for generating plasma P from the plasma generation gas and supplying the plasma P to the surface of the object to be treated 4 to kill fungi, wherein the plasma P generated in the reaction tube 1 is generated. To be treated 4
The outlet 5 is formed in the reaction tube 1 for jetting in the direction of a jet.

In the plasma sterilization apparatus A according to a second aspect of the present invention, in addition to the structure of the first aspect, one electrode 2 is formed as an outer electrode provided in contact with the outer surface of the reaction tube 1, and the other electrode is formed as the other electrode. The electrode 3 is formed as an inner electrode provided in the reaction tube 1.

A third aspect of the present invention is a plasma sterilization apparatus A according to the third aspect of the present invention.
Is provided in contact with the outer periphery of the reaction tube 1.

[0011] A plasma sterilization apparatus A according to a fourth aspect of the present invention, in addition to any one of the first to third aspects,
It is characterized in that a component for generating active oxygen, hydroxy ions or hydroxyl radicals by glow discharge is contained as a reaction gas in the plasma generating gas.

[0012] A plasma sterilization apparatus A according to claim 5 of the present invention has the structure of any one of claims 1 to 4,
At least one of a helium gas and an argon gas is contained as an inert gas in a plasma generation gas.

[0013] A plasma sterilization apparatus A according to claim 6 of the present invention has the structure of any of claims 1 to 5,
The reaction gas is oxygen, and the oxygen is 0.1 to
It is characterized in that a plasma generating gas is formed by containing 10 vol%.

[0014] A plasma sterilization apparatus A according to claim 7 of the present invention is characterized in that, in addition to any one of claims 1 to 5,
The reaction gas is H ₂ O or H ₂ O ₂ vapor.

The plasma sterilization apparatus A according to an eighth aspect of the present invention includes, in addition to the configuration of the seventh aspect, a vaporization means 10 for vaporizing liquid H ₂ O or H ₂ O _2. It is a feature.

According to a ninth aspect of the present invention, in the plasma sterilizing apparatus A, in addition to the constitution of the seventh or eighth aspect, 0.001 to ₂ vol% of H ₂ O or H ₂ O ₂ vapor is contained in the inert gas. It is characterized by being formed by forming a gas for plasma generation by containing it.

A plasma sterilization apparatus A according to a tenth aspect of the present invention includes a moving means 6 for moving the reaction tube 1 or the workpiece 4 in addition to any one of the first to ninth aspects. It is characterized by the following.

The plasma sterilization apparatus A according to claim 11 of the present invention further comprises a cooling means 7 for cooling at least one of the electrodes 2 and 3 in addition to any one of the constitutions of claims 1 to 10. It is characterized by comprising.

A plasma sterilization apparatus A according to a twelfth aspect of the present invention, in addition to any one of the first to eleventh aspects, further comprises:
Hz to 200 MHz.

A plasma sterilization method according to a thirteenth aspect of the present invention includes a cylindrical reaction tube 1 having a blowout port 5 and a pair of electrodes 2 and 3, wherein an inert gas or an inert gas and a reaction gas are used. Is introduced into the reaction tube 1 at the position corresponding to between the electrodes 2 and 3 to generate a glow discharge under atmospheric pressure. To generate plasma P from the plasma-generating gas, and the plasma P generated in the reaction tube 1 is blown out from the blow-out port 5 toward the processing object 4 to be supplied to the surface of the processing object 4 to be jetted. Processed material 4
Characterized in that the fungus is killed by the plasma supplied to the surface.

A plasma sterilization method according to a fourteenth aspect of the present invention is characterized in that, in addition to the structure of the thirteenth aspect, the reaction tube 1 or the workpiece 4 is moved.

[0022]

Embodiments of the present invention will be described below.

FIG. 1 shows an example of a plasma sterilization apparatus A of the present invention. This plasma sterilization apparatus A is formed by providing a pair of electrodes 2 and 3 in contact with the outer peripheral surface of a reaction tube 1 and arranging the electrodes 2 and 3 so as to face each other up and down. A discharge space 25 is formed inside the reaction tube 1 at a position corresponding to between the electrodes 3. One electrode 2 of the pair of electrodes 2 and 3 is formed as a high-voltage electrode to which a high voltage is applied by being connected to a power supply 11 for generating a high frequency, and the other electrode 3
Is formed as a ground electrode which is grounded and has a low voltage.

The reaction tube 1 is made of a high melting point insulating material (dielectric material) and is formed in a cylindrical shape, and its upper end is opened as a gas inlet 12. At the lower part of the reaction tube 1, there is formed a converging portion 13 having a tapered structure narrowed down to a tapered shape such that the diameter becomes smaller toward the lower side, and a lower surface of the converging portion 13 which is a lower end surface of the reaction tube 1. Is provided with an outlet 5. The diameter (inner diameter) of the reaction tube 1 is not particularly limited, but is preferably formed to 1 to 50 mm. Further, the diameter of the outlet 5 may be formed to be substantially the same as the diameter of the reaction tube 1 without providing the focusing section 13.

As described above, the lower portion of the reaction tube 1 is formed as a converging portion 13 which is narrowed down to a small diameter, thereby accelerating the flow rate of the jet-shaped plasma P without reducing the volume of the discharge space 25. Before the reactive gas active particles such as short-lived radicals are extinguished, the plasma P can be made to reach the object 4 and the object 4 can be efficiently sterilized. is there. When the converging section 13 is provided, the taper angle α is set to 10
It is preferable to set it to 〜30 °.

The opening area of the outlet 5 is formed to have a size corresponding to the area of a perfect circle having a diameter of 0.1 to 5 mm. If the opening area of the outlet 5 is smaller than the above range, the processing range of the plasma P to be blown becomes too small, and it takes a long time to sterilize the object 4 to be processed. If the opening area of the opening 5 is too large, the processing range of the plasma P to be blown out becomes too large, and there is a possibility that the object to be processed cannot be locally sterilized.

The dielectric constant of the insulating material forming the reaction tube 1 is an important factor in lowering the temperature in the discharge space 25.
It is preferably at most 00. Specifically, examples of the insulating material include glassy materials such as quartz, alumina, and partially stabilized zirconium yttria, and ceramic materials.

The electrodes 2 and 3 are made of a metal material having high thermal conductivity, for example, copper, aluminum, brass, stainless steel having high corrosion resistance (SUS30) in order to increase the cooling efficiency.
4 and the like, and as shown in FIG. 2, the electrodes 2 and 3 have the same shape and are formed in a ring shape (ring shape). An insertion hole 14 penetrating vertically is formed substantially at the center of the electrodes 2 and 3, and the diameter of the insertion hole 14 is formed to be substantially the same as the outer diameter of the reaction tube 1. The inside of the electrode 2 and the electrode 3 is formed as a circulation part 15 through which the refrigerant can flow, and the outer periphery of the electrode 2 and the electrode 3 is formed on the circulation part 1.
The supply pipe 16 and the discharge pipe 17 which communicate with 5 protrude.

The inner peripheral surfaces of the electrodes 2 and 3 (the surfaces constituting the insertion holes 14) are formed as contact surfaces 18 that come into contact with the reaction tube 1, and the surfaces of the contact surfaces 18 are represented by the arithmetic average roughness. The roughness is set to 10 to 1000 μm. By setting the surface roughness of the contact surface 18 to 10 to 1000 μm in this manner, the discharge in the discharge space 25 can be made uniform, and a glow-like discharge can be generated. The glow-like discharge is considered to be an aggregate of very fine micro-discharges when viewed from a microscopic viewpoint. By forming the fine irregularities on the surfaces of the electrodes 2 and 3 as described above, the glow-like discharge is prevented. Migration is inhibited. If the surface roughness of the contact surface 18 between the electrode 2 and the electrode 3 is less than 10 μm, there is a possibility that discharge becomes difficult, and the electrode 2 and the electrode 3
If the surface roughness of the contact surface 18 exceeds 1000 μm, there is a possibility that the discharge becomes non-uniform. As described above, as a process for roughening the contact surface 18 between the electrode 2 and the electrode 3, physical means such as sandblasting can be adopted.
The arithmetic average roughness Ra (μm) when the surface roughness is expressed in the form of y = f (x) is defined by JIS B 0601 by the following equation (1).

[0030]

(Equation 1)

The electrode 2 and the electrode 3 are attached to the outer periphery of the reaction tube 1 by inserting the reaction tube 1 into the insertion hole 18, and the contact surface 18 of the inner peripheral surface of the electrode 2 and the electrode 3 is connected to the reaction tube 1. It is arranged to be in contact with the outer peripheral surface. The electrode 3 is disposed so as to be located below the electrode 2 and above the focusing unit 20, that is, between the outlet 5 and the electrode 2. As a result, the electrode 3 is located closer to the object 4 than the electrode 2, that is, the electrode 2 having a high voltage is located farther from the object 4 than the electrode 3, The arc discharge does not easily fly from the electrode 2 to the object 4, and damage to the object 4 due to the arc discharge can be prevented.

The distance L between the electrodes 2 and 3 (the distance L between the lower end of the electrode 2 and the upper end of the electrode 3) is preferably set to 3 to 20 mm. If the distance L between the electrode 2 and the electrode 3 is less than 3 mm, a short circuit may occur between the electrode 2 and the electrode 3 outside the reaction tube 1 and no discharge may occur in the discharge space 25.
In addition, the discharge space 25 becomes narrow, and it may be difficult to efficiently generate the plasma 5. When the distance L between the electrode 2 and the electrode 3 exceeds 20 mm, the discharge space 2
5 makes it difficult for discharge to occur, which may make it difficult to efficiently generate the plasma 5.

The above electrodes 2 and 3 are cooled by cooling means 7. As shown in FIG. 3, the cooling means 7 includes a refrigerant and a cooling circulator (chiller) 19, a refrigerant supply pipe 20, and a refrigerant return pipe 21. Ion exchange water or pure water can be used as the refrigerant. By using ion-exchanged water or pure water, no impurities are contained in the refrigerant, and the electrodes 2 and 3 are hardly corroded by the refrigerant. In addition, it has antifreeze at 0 ° C. as a refrigerant,
In addition, it is preferable that the liquid has electrical insulating properties, nonflammability, and chemical stability.
The withstand voltage at m intervals is preferably 10 kV or more. The reason for using a refrigerant having an insulating property in this range is to prevent electric leakage from an electrode to which a high voltage is applied. Examples of the refrigerant having such properties include perfluorocarbon, hydrofluoroether and the like, and may be a mixed liquid obtained by adding 5 to 60% by weight of ethylene glycol to pure water. Further, the refrigerant may be air. Note that the temperature of the plasma P is preferably set to 250 ° C. or less in order to prevent the workpiece 4 from being thermally destroyed. In order to reach such a temperature, it is preferable that the electrodes 2 and 3 are cooled so that the surface temperature thereof is 350 ° C. or less. When the surface temperature of the electrodes 2 and 3 exceeds 350 ° C., a streamer discharge is generated in the discharge space 25, and a uniform glow discharge may not be generated. The lower limit of the surface temperature of the electrodes 2 and 3 is not particularly set.
° C or lower, as long as the temperature does not freeze the refrigerant.

The cooling circulator 19 has a function of cooling the refrigerant and a function of sending the refrigerant to the electrodes 2 and 3. The cooling circulator 19 is connected to the supply pipe 16 of the electrodes 2 and 3 by the refrigerant supply pipe 20. The cooling circulator 19 is connected to the discharge pipe 17 of the electrodes 2 and 3 via a refrigerant return pipe 21. The electrodes 2 and 3 are connected to the cooling circulator 19 and the electrodes 2 and 3
Is cooled by the refrigerant circulating between the two. That is, the refrigerant cooled by the cooling circulator 19 is supplied to the supply pipes 16 of the electrodes 2 and 3 through the refrigerant supply pipe 20, and then flows through the supply pipes 16 and the inside of the electrodes 2 and 3 as indicated by arrows. The electrode 2 and the electrode 3 are cooled by the coolant supplied to the circulation unit 15 flowing through the circulation unit 15. Further, the cooling capacity of the refrigerant supplied to the circulation part 15 is reduced by cooling the electrodes 2 and 3, and the refrigerant having the reduced cooling capacity is discharged from the circulation part 15 through the discharge pipe 17 as shown by an arrow. Then, through the refrigerant return pipe 21, the cooling circulator 19
Will be returned to Then, the refrigerant having reduced cooling capacity is cooled by the cooling circulator 19 to increase the cooling capacity, and is sent to the electrodes 2 and 3 again as described above.

In the present invention, an inert gas or a mixed gas of an inert gas and a reaction gas can be used as the plasma generating gas. As the inert gas, a rare gas such as helium gas, argon gas, neon gas, or krypton gas can be used alone or in combination of two or more, but in consideration of discharge stability and economy,
It is preferable to use argon gas or helium gas. As the reaction gas, oxygen for generating active oxygen in the plasma P or H ₂ O or H ₂ O ₂ vapor for generating hydroxy ions or hydroxyl radicals in the plasma P can be used. Active oxygen, hydroxy ions and hydroxyl radicals effectively act on sterilization (sterilization), and can enhance the sterilization effect.

When a mixed gas of an inert gas and oxygen is used as the plasma-generating gas, the total amount of the plasma-generating gas (the total amount of the inert gas and oxygen) is 0.1 to 10%.
It is preferable to contain vol% of oxygen. Oxygen content is 0.1 vol% with respect to total amount of plasma generation gas
If it is less than 10%, the amount of active oxygen generated in the plasma P may be too small and the sterilization effect may be reduced, and the oxygen content is 10 vol% with respect to the total amount of the plasma generating gas.
If it exceeds, the discharge may be unstable. In addition, an inert gas and H ₂ O or H ₂ O ₂
When using a gaseous mixture of steam, the 0.001～2Vol% relative to the total amount of the plasma generation gas (inert gas and H ₂ O or the total amount of vapor H ₂ O ₂₎ H ₂ O or H ₂ O
_It is preferable to contain ₂ vapors. If the H ₂ O or H ₂ O ₂ vapor content is less than 0.001 vol% with respect to the total amount of the plasma generating gas, the amount of hydroxy ions and hydroxyl radicals generated in the plasma P becomes too small to sterilize. The effect may be reduced, and if the content of H ₂ O or H ₂ O ₂ vapor exceeds ₂ vol% with respect to the total amount of the plasma generating gas, the discharge may be unstable.

FIG. 3 shows a plasma generator gas generator 2.
6 is shown. The gas generator 26 includes a gas control unit 27 and the vaporizing means 10. Gas control unit 2
7 is provided with a plurality of cylinder connecting portions 28, and each cylinder connecting portion 28 is connected to a gas cylinder 39 storing different types of gas. At least one of the gas cylinders 39 can be an oxygen cylinder storing oxygen as a reaction gas, and the other gas cylinder 39 can be an inert gas cylinder such as an argon gas cylinder storing argon gas or a helium gas cylinder storing helium gas. . Also,
Each cylinder connection portion 28 is connected to a mixer 30 via an adjustment valve 29. One end of a gas supply pipe 31 is connected to the mixer 30, and the other end of the gas supply pipe 31 is connected to the gas inlet 12 of the reaction tube 1. Gas supply pipe 3
1, an introduction switching valve 32 and a derivation switching valve 33 are provided. One end of the introduction pipe 34 is connected to the gas supply pipe 31 via the introduction switching valve 32, and the derivation switching valve 3 is connected.
One end of the outlet pipe 35 is connected to the gas supply pipe 31 via 3.

The vaporizing means 10 comprises a vessel 36 for storing water or hydrogen peroxide solution 38 and a warmer 37 for keeping the water or hydrogen peroxide solution 38 stored in the vessel 36 at a constant temperature. The other end of the introduction pipe 34 and the other end of the outlet pipe 35 are introduced into the vessel 36. The other end of the introduction pipe 34 is immersed in water or a hydrogen peroxide solution 38 stored in a vessel 36. Outlet pipe 35
Is disposed in a generation space 40 above the surface of the water or hydrogen peroxide solution 38 stored in the vessel 36. The thermostat 37 is provided with a thermostat. When the thermostat 37 is turned on and off by the thermostat, the water or the hydrogen peroxide solution 3 stored in the vessel 36 is turned on and off.
8 can be maintained at a substantially constant temperature.

When the gas generator 26 prepares a plasma generation gas using argon gas and helium gas as inert gases and oxygen as a reaction gas, the regulating valve 29 is opened and each gas cylinder 39 is opened. The gas is introduced into the mixer 30, and the gas for plasma generation can be prepared by mixing the argon gas, the helium gas, and the oxygen in the mixer 30. The mixing ratio of each gas can be adjusted by the degree of opening and closing of the adjusting valve 29 connected to each gas cylinder 39. The gas for plasma generation thus prepared is sent to the gas inlet 12 of the reaction tube 1 through the gas supply tube 31 and introduced into the reaction tube 1 from the gas inlet 12.

In preparing the plasma generating gas using the above-mentioned gas generator 26 with argon gas and helium gas as inert gases and H ₂ O or H ₂ O ₂ vapor as a reaction gas, First, the introduction switching valve 32 is operated to make the introduction pipe 34 and the gas supply pipe 31 conductive. Further, the water or the hydrogen peroxide solution 38 is added to the
Heat to ℃ and keep warm. Next, the control valve 29 connected to the argon gas cylinder and the control valve 29 connected to the helium gas cylinder are opened to introduce gas from each gas cylinder 39 to the mixer 30, and the mixer 30 mixes argon gas and helium gas. . Next, a part or the whole of the mixed gas is introduced into the vessel 36 through the introduction pipe 34, and is blown out from the introduction pipe 34 in water or hydrogen peroxide water 38 for bubbling. Then, by causing the mixed gas to flow through the water or the hydrogen peroxide solution 38 by bubbling, a plasma generation gas containing a predetermined amount of H ₂ O or H ₂ O ₂ vapor is easily introduced into the generation space 40. Can be generated. Thereafter, the plasma generating gas is introduced into the reaction tube 1 through the gas outlet pipe 35 and the gas supply pipe 31 by operating the outlet switching valve 33 to make the outlet pipe 35 and the gas supply pipe 31 conductive. The gas is sent to the port 12 and is introduced into the reaction tube 1 from the gas inlet 12.

When the aqueous hydrogen peroxide solution 38 is used as described above, its concentration control is important, and it is preferable to use an aqueous solution of 2 to 60% by mass. When the concentration of the hydrogen peroxide solution 38 is 2
If it is less than mass%, H ₂ contained in the plasma generating gas
There is a possibility that the amount of O ₂ vapor becomes too smaller than the above-mentioned predetermined amount, and the sterilization effect may be reduced. If the concentration of the hydrogen peroxide solution 38 exceeds 60% by mass, H contained in the plasma generation gas may be reduced. The amount of the vapor of ₂ O ₂ may become too large than the above-mentioned predetermined amount, and the discharge may become unstable.

As described above, water or hydrogen peroxide is vaporized at a predetermined concentration, mixed with a gas for plasma generation, and introduced into a reaction tube (reaction vessel) by a conventional method under reduced pressure. It was extremely difficult with the plasma generation method described above. That is, it is extremely difficult in operation to accurately supply a constant amount of liquid to the decompression chamber and keep the pressure constant, and if the supply amount and the pressure become non-uniform, the plasma becomes unstable. In the present invention, since the plasma P is generated under the atmospheric pressure, the water or the hydrogen peroxide water 38 is vaporized at a predetermined concentration by bubbling as described above, mixed with the plasma generating gas, and introduced into the reaction tube 1. Can be.

When performing the plasma sterilization using the plasma sterilization apparatus A formed as described above,
As shown by the arrow, a plasma generating gas is introduced into the reaction tube 1 from the gas inlet 12, and the plasma generating gas introduced into the reaction tube 1 flows from top to bottom to cause the electrode 2 to flow.
A gas for plasma generation is introduced into the discharge space 25 between the electrode 3 and the electrode 3, and a high-frequency voltage is applied to the electrode 2 from the power supply 11 to apply a high-frequency AC electric field to the discharge space 25. Then, the application of the AC electric field causes the discharge space 25 under atmospheric pressure.
A glow discharge is generated, and the plasma generating gas is turned into plasma by the glow discharge to generate a plasma P containing plasma active species.
Is generated, the plasma P is continuously discharged downward from the outlet 5 in the form of a jet, and the plasma P is blown onto the surface of the workpiece 4 arranged below the outlet 5. In this manner, the bacteria (bacteria) adhered and propagated on the surface of the processing object 4 can be killed by the plasma P and sterilized. It is considered that the mechanism of sterilization is that oxygen radicals (active oxygen) and hydroxy (OH) radical ions generated by plasma P destroy bacterial cell membranes and DNA. And compared to other methods,
It is considered that the large sterilizing effect of the plasma sterilization apparatus of the present invention is due to the large amount of these radicals and ions. The distance between the outlet 5 and the object 4 varies depending on the application conditions, the type of the object 4 and the like, and can be set to 2 to 10 mm.

In the present invention, the frequency of the AC electric field applied to the discharge space 25 is preferably set to 1 kHz to 200 MHz. If the AC frequency is less than 1 kHz, the discharge in the discharge space 25 cannot be stabilized, and the plasma sterilization may not be performed efficiently. When the AC frequency exceeds 200 MHz, the temperature of the plasma P in the discharge space 25 rises remarkably, and the life of the reaction tube 1 and the electrodes 2 and 3 may be shortened. There is a possibility that the size will increase.

In the present invention, the voltage is applied to the discharge space 25.
Applied power is 20-3500 W / cm^ThreeSet to
Is preferred. When the applied power applied to the discharge space 25 is 2
0W / cm^ThreeIf less than, the plasma P is sufficiently generated.
Can no longer be applied to the discharge space 25.
Applied power is 3500 W / cm^ThreeOver, stable
Discharge may not be obtained. In addition, application
Power density (W / cm ^Three) Is (applied power / discharge space body)
Product).

As shown in FIG. 3, a moving means 6 formed by a belt conveyor, an XY table or the like is provided below the blow-out port 5, and a large number of workpieces 4 are formed by the moving means 6.
By continuously moving (transporting) the plasma P to the workpiece 4 in order as described above, a large amount of workpiece can be continuously sterilized. In addition, by moving the moving means 6 up and down or tilting it up and down, the processing object 4 can be moved three-dimensionally by the moving means 6. By moving the processing object 4 three-dimensionally, the processing object 4 has a complicated shape and has a shadow portion that the plasma P does not reach (can not go around) when the plasma P is sprayed from above. Even if the processing is performed, the plasma P can reach the shadowed portion to perform the sterilization processing, and even the processing target having a complicated shape and a different shape can be easily sterilized.

In the present invention, the plasma P
The process of decompression release is not required,
The sterilization process can be performed in a short time. In addition, the plasma P blown out of the reaction tube 1 is
To be sterilized by supplying the
The plasma P can be supplied to the object 4 while continuously moving, and a large amount of the object can be continuously sterilized. The plasma P can be sprayed on the workpiece 4 of any size without limitation, and the large workpiece 4 can be blown.
However, sterilization can be easily performed. Furthermore, those of mixed gas of reactive gas and inert gas or inert gas so used as the plasma generation gas, which can be so harmful NO _X does not occur in the human body, it is possible to increase the safety It is.

Also, in the present invention, since both the electrodes 2 and 3 for applying an AC electric field to the discharge space 25 are provided outside the reaction tube 1, both the electrodes 2 and 3 are plasma P
The electrode 2 and the electrode 3 can be prevented from being directly exposed to the plasma P, not subject to the sputtering by the plasma P, and not corroded by the reaction gas. Is what you can do. In addition, since impurities due to the above-mentioned sputtering and corrosion do not occur, the object to be treated 4 can be prevented from being contaminated by impurities even when used for a long period of time. It can be suitably used.

Also, the electrodes 2 and 3 are arranged vertically facing each other without the reaction tube 1 interposed therebetween so that electric lines of force are formed along the inner surface of the reaction tube 1. The lines of electric force are hardly generated in the direction perpendicular to the inner surface of the reaction tube 1, and the deterioration of the reaction tube 1 due to the lines of electric force can be reduced. Can be reduced from being contaminated by impurities.

The electrodes 2 and 3 are arranged so as to be substantially parallel to the direction of introduction of the plasma generating gas,
And the electrodes 3 are vertically arranged and opposed to each other, so that the direction of the AC electric field generated in the discharge space 25 and the flow directions of the plasma generating gas and the plasma P can be substantially matched, and the active species of the plasma P Can be efficiently generated, and the size of the discharge space 25 can be easily changed by changing the distance L between the electrode 2 and the electrode 3, and the amount of generated plasma P can be easily adjusted. Is what you can do. Further, the size of the electrode 2 and the electrode 3 is not unnecessarily increased, and the discharge space 25 is prevented.
Since it can be designed into a shape corresponding to the size of
The electrodes 2 and 3, which are radiation sources of high-frequency noise, can be made compact. As a result, radiation high-frequency noise can be reduced, and malfunction of peripheral devices can be prevented.

Further, by changing the degree of constriction of the converging section 13, the blowing speed (flow rate) of the plasma P from the outlet 5 can be easily changed, and the diameter of the outlet P can be further reduced. By changing, the processing area can be easily expanded or reduced. Further, while the plasma P is being generated as described above, the electrodes 2 and 3 are cooled by the refrigerant,
Even if plasma is generated with high frequency AC under atmospheric pressure,
The temperature rise of both the electrode 2 and the electrode 3 can be further suppressed, so that the temperature (gas temperature) of the plasma P can be prevented from becoming higher, and the thermal damage of the processing object 4 can be further reduced. Can be done. Further, by cooling both the electrode 2 and the electrode 3, local heating of the discharge space 25 can be further prevented, a more uniform glow discharge can be generated, and generation of a streamer discharge can be suppressed. The damage of the object 4 due to the streamer discharge can be further reduced. This is achieved by cooling both electrode 2 and electrode 3 so that electrode 2 and electrode 3 are cooled.
It is considered that partial emission of electrons from both is suppressed.

FIG. 4 shows another embodiment. This plasma sterilization apparatus A can be formed in the same manner as in the above embodiment, except that the shape of the reaction tube 1 and the shapes of the electrodes 2 and 3 are different from those in FIG. The reaction tube 1 has a pair of opposed side walls 1a arranged in the thickness direction (indicated by an arrow a).
And a pair of side walls 1b opposed to each other side by side in the width direction of the reaction tube 1 (indicated by an arrow a), and a rectangular (rectangular when viewed from the bottom) bottom portion 1c that forms the lower surface of the reaction tube 1 and has a bottomed rectangle. It is formed in a tubular shape (square tubular shape). The upper surface of the reaction tube 1 is open almost entirely as a gas inlet 12, and the lower surface of the reaction tube 1, which is the outer surface of the bottom 1c, is formed as a substantially flat surface. Then, as shown in FIG.
At a substantially central portion of the lower surface of the reaction tube 1 in the thickness direction, a long and wide outlet 5 is formed in a direction parallel to the longitudinal direction (width direction) of the reaction tube 1. The outlet 5 has a slit shape and penetrates through the bottom 1 c of the reaction tube 1 and communicates with the discharge space 25 inside the reaction tube 1.

The reaction tube 1 has a flat shape whose width is much larger than its thickness, and has an inner dimension W in the thickness direction (narrow direction) of the reaction tube 1, ie, the thickness direction of the reaction tube 1. A pair of side walls 1a opposed to each other side by side (in the narrow direction)
Is preferably formed in a range of 0.1 to 5 mm. By setting the inner dimension W of the reaction tube 1 in the thickness direction to 0.1 to 5 mm, the volume of the discharge space 25 becomes relatively small, and the power per unit space in the discharge space 25 can be increased. In other words, it is possible to increase the discharge space density in the discharge space 25, and to achieve low power and small gas flow,
In addition, the plasma generation efficiency is increased, and the capability of plasma sterilization can be improved.

If the inner dimension W of the reaction tube 1 is less than 0.1 mm, the outlet 5 becomes too small, so that the range of plasma discharge becomes narrow, and the range in which sterilization can be performed may be reduced. Further, the strength of the reaction tube 1 may be reduced. On the other hand, if the inner dimension W of the reaction tube 1 is larger than 5 mm, the outlet 5 becomes too large, the flow rate of the jet-shaped plasma P blown out from the outlet 5 becomes small, and the speed of the sterilization process may be reduced. And the volume of the discharge space 25 becomes too large and the discharge space 2
5, the input power (AC electric field) per unit volume is reduced, the efficiency of plasma P generation is reduced, and the speed of the sterilization process may be reduced. The only solution to these problems is to increase the gas flow rate and power. However, as a result, a large amount of gas and power are consumed, and the cost performance may decrease. Therefore, the reaction tube 1
Is preferably formed to have an inner dimension W of 0.1 to 5 mm.

The electrodes 2 and 3 have the same shape, and are formed in a square shape (square ring) in plan view. That is, an insertion hole 14 penetrating vertically is formed substantially at the center of the electrodes 2 and 3. The size of the insertion hole 14 is substantially the same as the outer diameter of the reaction tube 1, and the shape of the insertion hole 14 in plan view is substantially the same as the outer shape of the reaction tube 1. By forming the electrodes 2 and 3 in a rectangular shape in plan view in this manner, the electrodes 2 and 3 are formed over the entire circumference of the reaction tube 1.
And the electrode 3 can be arranged, the contact area between the electrode 2 and the electrode 3 and the reaction tube 1 can be increased to improve the contact property, and the plasma P can be easily generated.
Note that the supply pipe 16 and the discharge pipe 17 are not shown in FIG.

By inserting the reaction tube 1 into the insertion hole 14, the electrodes 2 and 3 are attached to the outer periphery of the reaction tube 1 and the inner peripheral surfaces of the electrodes 2 and 3 are connected to the outer peripheral surface (side wall) of the reaction tube 1. 1a and the outer surface of the side wall 1b), and a power supply 11 for generating an AC electric field is connected to the electrode 2 and the electrode 3 is grounded to form a plasma sterilization apparatus as shown in FIG. be able to.

In this embodiment, the plasma P is blown out from the outlet 5 in the form of a jet and supplied to the workpiece 4 in the same manner as described above, but the elongated slit-shaped outlet 5 is formed on the lower surface of the reaction tube 1. Therefore, the object to be processed 4 or the plasma sterilization apparatus A is moved in a direction perpendicular to the longitudinal direction of the outlet 5 while the jet-shaped plasma having a width such as a curtain is blown out from the outlet 5. By scanning and spraying the plasma P over the entire surface of the workpiece 4, a large area of the workpiece 4 can be sterilized at a time as compared with the apparatus that blows out the spot-like plasma P, and the workpiece 4 having a large surface area Can shorten the processing time when sterilizing.
Further, by vibrating the plasma sterilizing apparatus A or the workpiece 4 in a direction perpendicular to the moving direction of the workpiece 4, the plasma P is repeatedly sprayed on the workpiece 4 to make the sterilization process uniform. Can also be increased.

FIG. 5 shows another embodiment. This plasma sterilization apparatus A can be formed in the same manner as in the above embodiment, except that the shape of the reaction tube 1 and the shapes of the electrodes 2 and 3 are different from those in FIG. The reaction tube 1 shown in FIG. 1 does not have the gas inlet 12 on the upper surface, but instead has a gas tube 70 projecting from the upper side surface of the reaction tube 1, and the tip of the gas tube 70 is opened as the gas inlet 12. Have been. Other configurations are the same as those in FIG.

The electrodes 2 and 3 are formed such that one electrode 2 is formed as an outer electrode provided in contact with the outer surface of the reaction tube 1 and the other electrode 3 is formed as an inner electrode provided in the reaction tube 1. Is formed. A discharge space 25 is formed in the reaction tube 1 at a position corresponding to between the electrodes 2 and 3. The outer electrode shown in FIG. 2 can be used as it is. In the outer electrode shown in FIG. 6, the positions of the supply pipe 16 and the discharge pipe 17 of FIG. 2 are different. The inner electrode is formed of a double pipe composed of an electrode main pipe 45 and a refrigerant injection pipe 46. The electrode body tube 45 is formed in a hollow rod shape whose upper and lower surfaces are closed.
A discharge pipe portion 47 is provided at a position protruding upward. The coolant injection pipe 46 having a smaller diameter than the electrode main pipe 45 is provided so as to penetrate the center of the electrode main pipe 45 and project from the lower part of the electrode main pipe 45 to the upper side of the electrode main pipe 45. The portion protruding above the electrode body tube 45 is formed as an injection portion 48. In addition, a flow path 49 communicating with the discharge pipe 47 is formed between the electrode body pipe 45 and the refrigerant injection pipe 46 inside the inner electrode. The electrode body tube 45 and the coolant injection tube 46 are preferably formed of the same metal material as the outer electrode,
Further, it is preferable that the outer surface of the electrode main body tube 45 is roughened like the outer electrode.

In order to stabilize the discharge in the discharge space 25 and prevent the electrodes 2 and 3 from corroding, the electrode body tube 4 of the inner electrode is used.
The surface of No. 5 is preferably coated with a coating of an insulating material having a dielectric constant of 2000 or less. As the insulating material used for this coating, specifically, quartz,
Vitreous materials and ceramic materials such as alumina and yttria partially stabilized zirconium can be exemplified. Further, alumina, titania, SiO ₂ , AlN,
Examples of the material include dielectric materials such as Si ₃ N, SiC, DLC (diamond-like carbon film), barium titanate, and PZT (lead zirconate titanate). In addition, magnesia (MgO) alone or an insulating material containing magnesia can be used, thereby stabilizing glow discharge. This is because magnesia has a high secondary electron emission coefficient, and when ions in the plasma collide with the coating on the surface of the inner electrode 3, a large amount of secondary electrons are emitted from the surface of the coating. It is presumed that secondary electrons are accelerated by the sheath formed on the surface of the coating and ionize the plasma generating gas, and as a result, the stabilization of the discharge is maintained. Examples of such an insulating material containing magnesia include a sintered body obtained by adding a small amount (0.01 to 5 vol%) of magnesia to a ceramic powder such as alumina and sintering the same, and a vitreous material such as quartz. Having an MgO film formed on the surface by CVD or the like.

When coating the surface of the electrode body tube 45 of the inner electrode, a cylindrical body (ceramic tube or glass tube) is formed from an insulating material, and the inner electrode (electrode body tube 45) is inserted inside the cylindrical body. A plasma spraying method in which powder such as alumina, barium titanate, or PZT is dispersed in a plasma and sprayed on the surface of an inner electrode (electrode main body tube 45);
After dispersing an inorganic powder such as tin oxide, titania, zirconia, or alumina with a solvent or the like, and spraying the surface of the inner electrode (electrode main tube 45) with a spray or the like to cover the surface,
A so-called enamel coating method of melting at a temperature of 600 ° C. or more, a method of forming a vitreous film by a sol-gel method, and the like can be employed. Furthermore, the surface of the inner electrode (electrode body tube 45) can be coated with an insulating material by a vapor deposition method (CVD) or a physical vapor deposition method (PVD), and by adopting these methods, it is extremely dense and smooth. The surface of the inner electrode (electrode body tube 45) can be coated with a film of an insulating material having poor adsorption properties, and the stabilization of discharge can be further promoted.

In cooling such an inner electrode with a refrigerant, the injection part 48 of the refrigerant injection pipe 46 is connected to the refrigerant supply pipe 20 and the discharge pipe 47 of the electrode body pipe 45 is connected to the refrigerant return pipe 21. . After doing this,
The refrigerant is supplied to the refrigerant injection pipe 46 from the opening at the upper end of the injection part 48 through the refrigerant supply pipe 20 (arrow), and the refrigerant flows into the flow path part 49 inside the inner electrode from the opening at the lower end of the refrigerant injection pipe 46. This can be performed by filling the flow path 49 with the refrigerant. The temperature of the refrigerant filled in the flow channel portion 49 rises due to a rise in the temperature of the inner electrode, and the cooling capacity decreases. However, the refrigerant having the lowered cooling capability is discharged from the flow channel portion 49 through the discharge pipe portion 47. At the same time, a refrigerant having a high cooling capacity is newly introduced into the flow path 49 through the refrigerant injection pipe 46. The refrigerant having a reduced cooling capacity discharged from the flow path 49 is returned to the cooling circulator 19 through the refrigerant return pipe 21. By circulating the coolant in this way, the inner electrode can be constantly cooled and maintained at a desired temperature.

In this embodiment, as described above,
By introducing a plasma generating gas into the discharge space 25 between the electrode 2 and the electrode 3 and applying a high-frequency AC electric field to the discharge space 25, a plasma P is generated in the reaction tube 1 and the plasma P is blown out. By blowing out the jet from the port 5 and supplying the jet to the workpiece 4, the surface of the workpiece 4 can be sterilized.

FIG. 6 shows another embodiment. This plasma sterilization apparatus A is a bottle transport system provided with a transporter 51 (moving means 6) for transporting a bottle 50 (object to be processed 4) for holding a beverage or the like to the apparatus shown in FIG. The conveyor 51 is formed with an introduction conveyor 52 for holding the bottle 50 sideways (in a laid state), a delivery conveyor 53 and a star wheel 54, and a star wheel 54 is provided between the introduction conveyor 52 and the delivery conveyor 53. Are arranged so as to be rotatable on a vertical plane about a horizontal direction. In addition, a number of bottle holding portions 55 are recessed at the peripheral end of the star wheel 54. The reaction tube 1 having the electrodes 2 and 3 is provided above the uppermost end of the star wheel 54. The reaction tube 1 is arranged such that the outlet 5 opens toward the star wheel 54 toward the lower side.

This plasma sterilization apparatus A (bottle transport system) continuously sterilizes the vicinity of the mouth of the bottle 50 while transporting the bottle 50. That is, first, the bottle 50 that has been conveyed by the introduction conveyor 52 and has reached the star wheel 54 is sandwiched and held by the bottle holding unit 55 of the star wheel 54. Next, when the star wheel 54 is rotationally driven, the held bottle 50 is lifted so as to approach the outlet 5 of the reaction tube 1 and moves upward. Next, the plasma P blown from the outlet 5 is
Is sprayed near the mouth and sterilized. At this time, the bottle 50 is configured to rotate around the horizontal direction while being held by the bottle holding portion 55, so that the sterilization process can be performed over the entire periphery of the vicinity of the mouth of the bottle 50. it can. Thereafter, the bottle 50 subjected to the sterilization process is moved downward by the rotation drive of the star wheel 54 so as to approach the outlet conveyor 53. Next, the bottle 50 sterilized by releasing the holding by the bottle holding unit 55 is taken out from the conveyer 53.
To be held. Then, the bottle 50 is delivered by the delivery conveyor 53.
Is transported to the next step. Thus, the sterilization process can be continuously performed while continuously transporting a large number of bottles 50. In FIG. 6, the reaction tube 1 and the electrodes 2, 3 shown in FIG. 1 are used, but those shown in FIGS. 3, 4 may be used.

FIG. 7 shows another embodiment. The plasma sterilization apparatus A is the same as the apparatus shown in FIG. 3 except that a traveling belt 57 (moving means 6) for transporting a plate-like workpiece 4 is provided. The traveling belt 57 is disposed below the outlet 5 of the reaction tube 1 and is driven to travel in one direction. The reaction tube 1 is provided with a moving means 6 for moving the reaction tube three-dimensionally.
Is held on a stand 60. The stand 60 is formed by a pillar 61 vertically erected, an arm 62 provided on the pillar 61 so as to protrude in the horizontal direction, and a holding part 63 provided at the tip of the arm 62. The holding section 63 holds a gas supply pipe 31 connected to the gas inlet 12 of the reaction tube 1. The stand 60 thus formed is capable of moving the reaction tube 1 three-dimensionally. That is, the above-described arm portion 62 is formed so as to be vertically movable with respect to the column portion 61.
By vertically moving the arm portion 62, the reaction tube 1 is moved.
Can be moved up and down. The holding portion 63 is formed so as to be rotatable up and down and left and right with respect to the arm portion 62. Therefore, by rotating the holding portion 63 up and down and right and left, the blowing angle of the plasma P is changed. Thus, the reaction tube 1 can be rotated up, down, left and right. Further, the arm portion 62 is formed so as to be able to expand and contract, so that the reaction tube 1 can also be moved horizontally. Note that an XY table or the like for horizontally moving the reaction tube 1 can be used as the moving means 6.

This plasma sterilization apparatus A is a
Is conveyed by the traveling belt 57 to sterilize the upper surface of the processing object 4. That is, a large number of workpieces 4 are placed on the traveling belt 57 and the outlets 5 of the reaction tube 1 are sequentially placed.
, The plasma P blown out from the outlet 5 is sequentially blown onto the upper surface of each of the workpieces 4, so that a large number of the workpieces 4 can be continuously sterilized. Things. In FIG. 7, the reaction tube 1 shown in FIG. 3 is used, but the one shown in FIGS. 1 and 4 may be used. In FIG. 7, the electrodes 2 and 3 are not shown.

[0068]

The present invention will be described below in detail with reference to examples.

Example 1 Escherichia coli (Escherichi
iaco1iIF03301) was suspended in pure water to prepare a suspension, and the above-mentioned Escherichia coli cell concentration was 10 ⁴ / sheet on a non-woven fabric (1.5 cm × 1.5 cm) made of polyethylene terephthalate (PET). The suspension was contained in a nonwoven fabric, and this nonwoven fabric was subjected to plasma sterilization treatment as an object to be processed 4 in a plasma sterilization apparatus A shown in FIG. 1 under the following conditions.

The reaction tube 1 of the plasma sterilization apparatus A is made of quartz glass and has an outer diameter of 16 mm and an inner diameter of 13 mm. The electrodes 2 and 3 provided on the outer periphery of the reactor 1 are formed as a high-voltage electrode on the upstream side (upper side) and as a ground side electrode on the downstream side (lower side). The electrodes 2 and 3 are made of copper and have a structure in which a cooling liquid (coolant) can be circulated. Pure water was circulated and used as a refrigerant. The arithmetic average roughness of the surface of both electrodes 2 and 3 was 100 μm.

Plasma P was sprayed on the entire nonwoven fabric in the plasma sterilizing apparatus A as described above to uniformly sterilize the nonwoven fabric. Conditions for generating plasma P are as follows: RF output is 100 kHz
, And the composition of the plasma generating gas was helium gas flow rate: 0.25 liters per minute, argon gas flow rate:
1.25 liters / minute, oxygen: 0.02 liters / minute, processing time (plasma P spray time) is 3 seconds, and the nonwoven fabric is located 20 mm downstream (downward) of the outlet 5 of the reaction tube 1. I let it.

After the plasma sterilization in this manner,
The non-woven fabric is put in 10 ml of distilled water, the bacteria are removed by stirring well, 1 ml of the resulting solution is mixed with a standard agar medium, and then cultured at 37 ° C. for 24 hours. The number was measured. A blank was compared with a nonwoven fabric treated with Escherichia coli without plasma sterilization. The number of the objects to be processed 4 is three,
The above operation was performed on each of the workpieces 4.

As a result, on the non-sterilized one, the proliferation of bacteria corresponding to an average value of about 10 ³ / ml was observed, but no colony was detected on the plasma-sterilized non-woven fabric.

Example 2 Escherichia coli (Escherich)
iaco1iIF03301) was suspended in pure water to prepare a suspension, and the suspension was dropped on the surface of a glass plate (3 cm × 3 cm) so that the concentration of the above-mentioned Escherichia coli cells was 10 ⁵ cells / sheet. And air-dried. Next, this glass plate was used as the object to be treated 4 and the same plasma sterilizer A as in Example 1 was used for X-ray processing.
While moving on the Y table, plasma P was sprayed on the entire glass plate to uniformly sterilize it. The conditions for generating the plasma P are as follows: the RF output is 150 W at 60 MHz, the composition of the plasma generating gas is helium gas flow rate: 2 liters per minute,
Argon gas flow rate: 10 liters per minute, H ₂ O ₂ vapor:
The processing time (time of spraying the plasma P at each point) was 2 seconds, and the glass plate was positioned 10 mm downstream (downward) of the outlet 5 of the reaction tube 1. The H ₂ O ₂ vapor was added to the plasma generation gas using a gas generator 26 shown in FIG. That is,
A part of the mixed gas of helium gas and argon gas (5 vol% of the total amount) is bubbled into the hydrogen peroxide solution (H ₂ O ₂ concentration is 34 mass%) 38 stored in the vessel 36,
H ₂ O ₂ vapor was added to a mixed gas of helium gas and argon gas. The H ₂ in the plasma generation gas
The concentration of the O ₂ vapor was 0.01 vol% of the whole as determined by gas chromatography analysis.

After the plasma sterilization in this manner,
The glass plate was placed in 10 ml of distilled water, the bacteria were removed by thorough stirring, and 1 ml of the solution was mixed with a standard agar medium, and then cultured at 37 ° C. for 24 hours. The number of colonies was counted. A blank was compared with a glass plate treated with Escherichia coli without plasma sterilization as a blank. The number of the processing objects 4 was set to three, and the above-described operation was performed on each of the processing objects 4.

As a result, in the case of the unsterilized one, germs corresponding to an average value of about 10 ² cells / milliliter were found, but no colonies were detected in the plasma-sterilized glass plate.

Example 3 Escherichia coli (Escherich)
iaco1iIF03301) suspended in pure water
Prepared on the surface of a glass plate (3 cm in diameter)
Bacterial cell concentration 10 ^FiveDrop the suspension so that it becomes pieces / sheet and empty
Air dried in the air. Next, this glass plate is combined with the object 4 to be treated.
Then, the glass plate is processed by the plasma sterilization apparatus A shown in FIG.
While transporting, plasma P is sprayed on the entire glass
First, it was sterilized. Conditions for generating plasma P are as follows: RF output
To 800 W at 13.56 MHz and the plasma generation gas
Helium gas flow rate: 0.25 liters per minute,
Argon gas flow rate: 1.25 liters per minute, H_TwoO steam
Gas (steam): 0.02 vol%, processing time (progress
The belt speed is set to 20 mm / sec.
The plate is placed 10 mm downstream (below) of the outlet 5 of the reaction tube 1.
Was located. In addition, H to the plasma generation gas_TwoO steam
Was added using the gas generator 26 shown in FIG. Sand
The helium is added to the distilled water 38 stored in the vessel 36.
Part of mixed gas of gas and argon gas (5vol of total volume)
%) And bubbling of helium gas and argon gas.
H in the gas mixture_TwoO vapor was added. And plastic
H in gas for generation of zuma_TwoO vapor concentration is gas chromatograph
According to the analysis of the lithography, it was 0.02% by volume.
Was.

After the plasma sterilization in this manner,
The glass plate was placed in 10 ml of distilled water, the bacteria were removed by thorough stirring, and 1 ml of the solution was mixed with a standard agar medium, and then cultured at 37 ° C. for 24 hours. The number of colonies was counted. A blank was compared with a glass plate treated with Escherichia coli without plasma sterilization as a blank. The number of the processing objects 4 was set to three, and the above-described operation was performed on each of the processing objects 4.

As a result, in the case of the unsterilized one, the proliferation of bacteria corresponding to an average value of about 10 ² cells / milliliter was observed, but no colony was detected in the glass plate subjected to the plasma sterilization.

(Embodiment 4) In a bottle transport system having a plasma sterilization apparatus A as shown in FIG.
Was used as a treatment object 4, and plasma P was sprayed around the mouth of the bottle 50 to uniformly sterilize it. Conditions for generating plasma P are as follows:
The RF output was 150 W at 13.56 MHz, the composition of the plasma generation gas was argon gas flow rate: 1.25 liters per minute, oxygen was 0.02 liters per minute, and the processing time per bottle 50 (bottle 50 (One rotation time) was set to 0.5 seconds, and the mouth of the bottle 50 was positioned 5 mm downstream (downward) of the outlet 5 of the reaction tube 1.

After the plasma sterilization in this manner,
Around the mouth of the bottle 50 is placed in 10 ml of distilled water, the bacteria are removed by stirring well, 100 μl of the solution is applied to a standard agar medium, and then cultured at 37 ° C. for 24 hours by an agar plate culture method. The number of colonies that appeared was counted. As a blank, a comparison was made with a bottle 50 treated with Escherichia coli without plasma sterilization. The number of the processing objects 4 was set to three, and the above-described operation was performed on each of the processing objects 4.

As a result, in the case of the non-sterile treatment, 10 to 1
Proliferation of bacteria corresponding to 00 cells / milliliter was observed, but no colonies were detected in the bottle 50 subjected to the plasma sterilization treatment.

[0083]

As described above, the invention according to claim 1 or 2 of the present invention comprises a cylindrical reaction tube and a pair of electrodes, and the reaction tube has an inert gas or a mixture of the inert gas and the reaction gas. By introducing an AC electric field into the reaction tube at a position corresponding to between the electrodes while introducing a gas for plasma generation consisting of a gas, a glow discharge is generated under atmospheric pressure to generate plasma from the plasma generation gas, A plasma sterilization apparatus that supplies the plasma to the surface of the object to kill fungi, and blows out the plasma generated in the reaction tube in a jet shape toward the object in the reaction tube. Since it is formed, by generating the plasma under the atmospheric pressure, the process of opening under reduced pressure is not required, and the sterilization can be performed in a short time. Also,
By supplying the plasma blown out of the reaction tube to the workpiece and performing the sterilization process, the plasma can be supplied to the workpiece while continuously moving a large number of workpieces, and a large amount of the workpiece can be supplied. The treatment can be continuously sterilized, and plasma can be sprayed on the treatment of an arbitrary size without being limited by the distance between the electrodes and the like. However, sterilization can be easily performed. Furthermore, those of mixed gas of reactive gas and inert gas or inert gas so used as the plasma generation gas, which can be so harmful NO _X does not occur in the human body, it is possible to increase the safety It is.

According to the third aspect of the present invention, since both electrodes are provided in contact with the outer periphery of the reaction tube, the electrodes are not directly exposed to the plasma, and are not subjected to sputtering by the plasma. In addition, the electrode can be prevented from being corroded by the reaction gas, and the electrode can be prevented from being damaged and the life can be prolonged. In addition, since no impurities are generated by the above-described sputtering and corrosion, the object to be processed can be prevented from being contaminated by the impurities even when used for a long time, and is particularly suitable for sterilizing foods and food containers. It can be used for.

Further, according to the invention of claim 4 of the present invention, since a component for generating active oxygen or hydroxy ions or hydroxyl radicals by glow discharge is contained as a reactive gas in the plasma generating gas, the active oxygen or hydroxy ion Can be supplied to the object to be processed, and the effect of the sterilization process can be enhanced.

In the invention of claim 5 of the present invention, since at least one of helium gas and argon gas is contained in the plasma generation gas as an inert gas, the stability of glow discharge can be improved and the cost can be reduced. In this way, it is possible to generate a plasma and to perform an efficient and inexpensive sterilization process.

Further, according to the invention of claim 6 of the present invention, the reactant gas is oxygen, and oxygen is added to the inert gas at 0.1 to 10 V.
ol% to form a gas for plasma generation,
A device that can increase the stability of glow discharge and can supply plasma containing active oxygen having a high sterilizing effect to an object to be processed, and can perform a sterilizing process with high efficiency and a high sterilizing effect. It is.

Further, according to the invention of claim 7 of the present invention, since the reaction gas is H ₂ O or H ₂ O ₂ vapor, a plasma containing hydroxy ions having a high sterilizing effect can be generated, and the sterilizing treatment can be performed. Can enhance the effect.

[0089] Further, an invention according to claim 8 of the present invention, since the H ₂ O or of H ₂ O ₂ liquid comprising a vaporizing means for vaporizing, of H ₂ O or H ₂ O ₂ was vaporized by vaporization means Vapor can be added to the gas for plasma generation, and plasma containing hydroxy ions having a high sterilizing effect can be generated, and the effect of the sterilizing process can be enhanced.

Further, according to the ninth aspect of the present invention, the inert gas contains 0.001 to ₂ vol. Of H ₂ O or H ₂ O ₂ vapor.
% To form a gas for plasma generation, so that the stability of glow discharge can be enhanced and plasma containing hydroxy ions having a high sterilizing effect can be supplied to the processing object. It is possible to perform a sterilization treatment with a high effect of the treatment.

Further, since the invention according to claim 10 of the present invention is provided with a moving means for moving the reaction tube or the object to be processed, the moving means can move the reaction tube or the object to be processed, so that the object having an arbitrary shape can be obtained. The plasma can be easily sprayed to an arbitrary position of the processing object, and the processing object having a complicated shape can be efficiently sterilized.

In the eleventh aspect of the present invention, since the cooling means for cooling at least one of the electrodes is provided, the temperature rise of the electrodes can be further suppressed by cooling the electrodes by the cooling means. Therefore, the temperature of the plasma (gas temperature) can be prevented from becoming higher, and the thermal damage to the object can be reduced. Also, by cooling the electrodes, local heating of the discharge space can be further prevented, a more uniform glow discharge can be generated, and the generation of a streamer discharge can be suppressed. It can be less.

Further, according to a twelfth aspect of the present invention, the frequency of the AC electric field applied between the electrodes is 1 kHz to 200 MHz.
Hz, the discharge in the discharge space can be stabilized, the plasma sterilization can be performed efficiently, and the temperature rise of the plasma in the discharge space can be suppressed. It can reduce the heat history of the tube and the electrode and extend the life.
It is possible to suppress the complexity and size of the device.

A thirteenth aspect of the present invention is directed to a plasma generating apparatus comprising a cylindrical reaction tube having a blowing port and a pair of electrodes, and comprising an inert gas or a mixed gas of an inert gas and a reaction gas. A gas is introduced into the reaction tube and an AC electric field is applied to the reaction tube at a position corresponding to between the electrodes, thereby generating a glow discharge under atmospheric pressure to generate plasma from the gas for plasma generation, thereby forming a plasma in the reaction tube. The plasma generated in the above is blown out from the outlet to the object to be processed in a jet form and supplied to the surface of the object to be processed, and the fungus is killed by the plasma supplied to the surface of the object to be processed. By generating the plasma by the above method, the process of opening under reduced pressure is not required, and the sterilization can be performed in a short time. In addition, by supplying the plasma blown out from the reaction tube to the workpiece and performing the sterilization process, the plasma can be supplied to the workpiece while continuously moving a large number of workpieces. It is possible to continuously sterilize the object to be processed, and further, it is possible to spray plasma on the object to be processed of any size without being limited by the interval between the electrodes,
Even large objects can be easily sterilized. Furthermore, those of mixed gas of reactive gas and inert gas or inert gas so used as the plasma generation gas, which can be so harmful NO _X does not occur in the human body, it is possible to increase the safety It is.

Further, according to the invention of claim 14 of the present invention, since the reaction tube or the object to be processed is moved, the plasma can be easily blown to an arbitrary position on the object having an arbitrary shape, and a complicated shape is obtained. The object to be treated can be efficiently sterilized.

[Brief description of the drawings]

FIG. 1 is a front view showing an example of an embodiment of the present invention.

FIG. 2 is a perspective view showing the electrode of the above.

FIG. 3 is a schematic diagram of the above.

FIG. 4A is a perspective view showing another embodiment of the same,
(B) is a bottom view.

FIG. 5 is a front view showing an example of another embodiment of the above.

FIG. 6 is a front view showing an example of another embodiment of the above.

FIG. 7 is a perspective view showing an example of another embodiment of the above.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Reaction tube 2 Electrode 3 Electrode 4 Workpiece 5 Outlet 6 Moving means 7 Cooling means 10 Vaporization means A Plasma sterilization apparatus

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Noriyuki Taguchi 1048 Kadoma Kadoma, Osaka Pref.Matsushita Electric Works, Ltd. (72) Inventor Keiichi Yamazaki 1048 Kadoma Kadoma, Kadoma, Osaka Pref. 72) Inventor Yoshiyuki Nakazono 1048 Kadoma Kadoma, Kadoma-shi, Osaka Pref. Matsushita Electric Works Co., Ltd. (72) Inventor Yoshitami Inoue 1048 Kadoma Kadoma, Kadoma-shi, Osaka Pref. AA21 AA25 BB06 CC02 CC04 DD03 DD04 EE23 EE26 KK06 KK14 KK26

Claims (14)

[Claims] An inert gas or a gas mixture of an inert gas and a reactive gas is introduced into a reaction tube, and a plasma generating gas is introduced between the electrodes. A glow discharge is generated under atmospheric pressure by applying an AC electric field to the reaction tube at a position where the plasma is generated, and plasma is generated from the plasma generation gas, and this plasma is supplied to the surface of the object to be treated to kill fungi What is claimed is: 1. A plasma sterilization apparatus, wherein an outlet for jetting plasma generated in a reaction tube toward an object to be processed is formed in the reaction tube. 2. The method according to claim 1, wherein one electrode is formed as an outer electrode provided in contact with the outer surface of the reaction tube, and the other electrode is formed as an inner electrode provided in the reaction tube. 2. The plasma sterilization apparatus according to 1. 3. The plasma sterilization apparatus according to claim 1, wherein both electrodes are provided in contact with the outer periphery of the reaction tube. 4. The plasma generating gas according to claim 1, wherein a component for generating active oxygen, hydroxy ions or hydroxy radicals by glow discharge is contained as a reactive gas in the plasma generating gas. Plasma sterilization equipment. 5. The plasma sterilization apparatus according to claim 1, wherein at least one of helium gas and argon gas is contained as an inert gas in the plasma generation gas. 6. The plasma generating gas according to claim 1, wherein the reactive gas is oxygen, and the inert gas contains 0.1 to 10 vol% of oxygen to form a plasma generating gas. The plasma sterilization treatment device according to item 1. 7. The plasma sterilization apparatus according to claim 1, wherein the reaction gas is H ₂ O or H ₂ O ₂ vapor. 8. The plasma sterilization apparatus according to claim 7, further comprising vaporizing means for vaporizing liquid H ₂ O or H ₂ O ₂ . 9. The plasma generating gas according to claim 7, wherein the inert gas contains 0.002 to ₂ vol% of H ₂ O or H ₂ O ₂ vapor. Plasma sterilization equipment. 10. The plasma sterilization apparatus according to claim 1, further comprising a moving means for moving a reaction tube or an object to be processed. 11. The plasma sterilization apparatus according to claim 1, further comprising cooling means for cooling at least one of the electrodes. 12. The plasma sterilization apparatus according to claim 1, wherein the frequency of the AC electric field applied between the electrodes is set to 1 kHz to 200 MHz. 13. A reaction system comprising a cylindrical reaction tube having a blow-out port and a pair of electrodes, wherein a plasma generating gas comprising an inert gas or a mixed gas of an inert gas and a reaction gas is introduced into the reaction tube, and an electrode is provided. By applying an AC electric field to the reaction tube at a position corresponding to the above, a glow discharge is generated under atmospheric pressure to generate plasma from the plasma generating gas, and the plasma generated in the reaction tube is covered from the outlet. A plasma sterilization method, comprising jetting a jet toward a processed object, supplying the jetted surface to the surface of the object, and killing fungi with the plasma supplied to the surface of the object. 14. The plasma sterilization method according to claim 13, wherein the reaction tube or the object is moved.