JP5843115B2 - Sterilization method and sterilizer using dinitrogen tetroxide - Google Patents

Description

  The present invention relates to a sterilization method and apparatus for sterilizing microbial adherents using nitrogen oxides.

  In the medical and research fields, when a used medical device or a test instrument contaminated with microorganisms is sterilized and reused, the instrument is generally sterilized using an autoclave (high pressure steam sterilizer). In autoclave sterilization, for example, a used medical device is placed in a pressure chamber, pressurized and heated in the presence of moisture, and the medical device is held in the pressure chamber for several tens of minutes. A sterilization treatment is adopted that decomposes the biopolymers that make up and kills all bacteria. Autoclave sterilization that heats up to 130 ° C cannot sterilize instruments composed of materials with low heat resistance such as rubber, and when instruments composed of resin materials are sterilized, the instruments physically expand due to heat cycles. The compressed water vapor of about 2 atm penetrates into the gap between the resins by repeating the contraction, and therefore, deterioration of the resin is promoted by the repeated sterilization operation.

In contrast, sterilization using ethylene oxide (C ₂ H ₄ O) gas (EOG) can be sterilized at a lower temperature, lower pressure and lower humidity than autoclave sterilization, so sterilizing rubber and resin with low heat resistance and water resistance. can do. However, ethylene oxide gas is highly reactive, and there is a danger of ignition and explosion due to pressurization. It is very troublesome to handle, and is very toxic to the human body. In the United States Pharmacopeia (USP), restrictions on use are strengthened, and the need for alternative substances is increasing.

Nitrogen oxide has attracted attention as a sterilant that does not require heating and pressurization and is relatively easy to handle. Nitrogen oxides include nitric oxide (NO), nitrogen dioxide (NO ₂ ), nitrous oxide (dinitrogen monoxide) (N ₂ O), dinitrogen trioxide (N ₂ O ₃ ), dinitrogen tetroxide ( N ₂ O ₄ ) and dinitrogen pentoxide (N ₂ O ₅ ) are generic names for compounds composed of nitrogen and oxygen. Patent Document 1 is directed to a sterilant gas containing one or more nitrogen oxides of NO, NO ₂ , NO ₃ , N ₂ O ₃ , N ₂ O ₄ , N ₂ O ₅ , N ₂ O and mixtures thereof. Disclosed is a system for exposing a medical device to sterilize or decontaminate a medical device. Nitrogen oxide gas is generated from the sterilant gas generating composition, and an object accommodated in a sealed sterilization chamber is sterilized with the nitrogen oxide gas.

  Patent Document 2 includes a sterilization chamber that forms a sealed space for sterilization processing, and an atmospheric pressure plasma generation unit that generates nitrogen oxide gas. Nitrogen dioxide gas passes from the atmospheric pressure plasma generation unit to the sterilization chamber via a catalyst unit. A sterilization apparatus is disclosed that performs sterilization by exposing a medical instrument such as a scalpel, forceps, and catheter or a food packaging material such as a packaging sheet, tray, and bottle to nitrogen dioxide gas. The atmospheric pressure plasma generator includes a microwave supply device and a plasma nozzle that converts the source gas into plasma by applying microwave energy from the microwave supply device. In Patent Document 2, nitrogen and oxygen in raw material air are converted into plasma to generate nitrogen oxide gas.

In Patent Document 1, a diazeniumdiolate compound (R ³ —C (R ¹ ) _x (N ₂ O ₂ R ² ) _y ) as a sterilant gas generating composition is reacted with oxalic acid in a gas generating chamber. Or other sterilant gas generating composition and an acid are reacted to generate nitrogen oxide gas. That is, since a plurality of substances are mixed in the gas generation chamber and nitrogen oxide gas is supplied to the sterilization chamber, the nitrogen oxides supplied to the sterilization chamber must be controlled unless the reaction conditions in the gas generation chamber are appropriately controlled. The concentration may become unstable and the object may not be sterilized sufficiently. On the contrary, if an excessive amount of nitrogen oxide is supplied, the nitrogen oxide adheres to the sterilized medical device at a high concentration, which is not preferable for safety. Also, if it is necessary to mix a solid sterilant gas generating composition and an acid for each sterilization, it is practically difficult to use it for sterilization of medical equipment in an actual medical field. . Furthermore, the use of acids is dangerous for handling, including transportation and storage.

  In the sterilization apparatus of Patent Document 2 that obtains nitrogen oxide gas by converting to plasma, since nitrogen and oxygen in the air are used as raw materials, there is no danger of transport and storage of raw materials, but generation of generating nitrogen oxide gas The efficiency is very low. For this reason, not only the preparation process for generating a desired amount of nitrogen oxide gas to fill the sterilization chamber and starting sterilization, but also maintaining the nitrogen oxide concentration in the sterilization chamber and completing the sterilization of the object The sterilization process requires considerable time and energy costs. Moreover, in the apparatus of patent document 2, it is necessary to convert the nitrogen oxide produced | generated by the plasma generation part into highly sterilized nitrogen dioxide by a catalyst part, and the manufacture price of a sterilizer is made from platinum or palladium used as a catalyst. It will be expensive.

  Further, in Patent Documents 1 and 2 and other conventional sterilization methods, there has been no study or research on a method for efficiently recovering a sterilant from a sterilization chamber after the sterilization process is completed. For this reason, depending on the shape of the medical device and the concentration of the sterilizing agent, there is a possibility that the toxic sterilizing agent component may not be completely removed from the sterilized medical device. It was a big safety issue.

Special table 2009-542333 JP2011-4802

  Therefore, an object of the present invention is to provide a sterilization method and a sterilization apparatus that can safely sterilize microbial adherents with nitrogen oxides. Another object of the present invention is to provide a sterilization method and a sterilization apparatus that can quickly and reliably sterilize an object to be sterilized in any shape. Furthermore, an object of the present invention is to provide a sterilization method and a sterilization apparatus in which no harmful sterilant components remain in an object to be sterilized and the sterilant can be efficiently recovered after the sterilization operation.

  The sterilization method using dinitrogen tetroxide according to the present invention includes a process of placing the object (1) in the housing cavity (2), and holding the housing cavity (2) in a hermetically sealed state using a decompression device (3). The process of depressurizing the containment cavity (2) to a reduced pressure state or vacuum state below the saturated vapor pressure curve of nitrogen, and the liquid dinitrogen tetroxide from the storage tank (4) containing the liquid dinitrogen tetroxide Supplying to the spraying device (25), spraying liquid dinitrogen tetroxide into the vacuum or vacuum containing cavity (2) through the spraying device (25), and storing the cavity through the spraying device (25). At least part of the liquid dinitrogen tetroxide sprayed in (2) is vaporized by reducing its pressure below the saturation vapor pressure curve, and the object (1) is removed by gaseous dinitrogen tetroxide in the containing cavity (2). Sterilization process.

When liquid nitrogen oxide is introduced from the storage tank (4) into the decompression state or vacuum state accommodation cavity (2) having a pressure equal to or lower than the saturation vapor pressure curve of the nitrogen oxide, at least a part of the nitrogen oxide is contained in the accommodation cavity. Vaporizes from liquid to gas in (2). Nitrogen oxide gas with strong oxidizing power instantly disperses in the containment cavity (2) and diffuses into the details of the object (1), so that the surface of the complex-shaped object (1) can be quickly and completely Can be sterilized. As used herein, “sterilization” means aseptic conditions that completely kill or remove any proliferating microorganisms (mainly bacteria), or a condition where the possibility of growth of microorganisms is as close to zero as possible. The sterility assurance level (Sterility Assurance level: SAL), which is an index indicating the probability of the presence of microorganisms after sterilization, is 10 ⁻⁶ or less. Therefore, it is different from “disinfection” that diminishes the ability of pathogenic microorganisms but does not mean to kill all microorganisms, and “sterilization” that kills bacteria but does not include the target and degree of killing. “Sterilization” is required to completely inactivate the function of microorganisms in molecular biology or biotechnology. Further, in the present invention, endotoxin which is a dead body of bacteria can also be effectively removed, and depyrogen treatment that is more advanced than sterilization can be performed.

  In addition, liquid nitrogen oxides are introduced into the containment cavity (2) under negative pressure, vaporized, and sterilized, so that it is possible to sterilize nitrogen at a stable concentration without the need for mixing multiple substances and expensive plasma generators and catalytic metals. Oxide can be supplied to the receiving cavity (2). Furthermore, if liquid nitrogen oxides are used at normal temperature and normal pressure, a high pressure tank for storing nitrogen oxides is not required, handling is easy, and transportation and maintenance costs of the sterilant can be greatly reduced. .

  The sterilization apparatus using nitrous oxide includes a storage tank (4) that stores liquid nitrous oxide, a storage cavity (2) that can store the object (1) and can be kept in a sealed state, and a storage cavity ( 2) a spraying device (25) connected to the storage tank (4) and a decompression device for decompressing the containing cavity (2) to a decompressed state or a vacuum state below the saturated vapor pressure curve of dinitrogen tetroxide ( And 3). The liquid dinitrogen tetroxide is supplied from the storage tank (4) to the spraying device (25) without being vaporized, and the liquid nitrous oxide is supplied to the containing cavity (2) in a reduced pressure or vacuum state through the spraying device (25). Nitrogen is sprayed, and at least part of the liquid dinitrogen tetroxide sprayed to the accommodation cavity (2) through the spraying device (25) is vaporized by reducing the vapor pressure below the saturation vapor pressure curve. The object (1) can be sterilized, and a sterilizer can be manufactured relatively easily.

  In the present invention, microorganisms including bacteria and viruses attached to an object to be sterilized can be completely killed and destroyed by nitrogen oxides, thereby preventing infection of microorganisms and damage to precision parts. In addition, since liquid nitrogen oxide that does not mix multiple substances is efficiently introduced into the housing cavity under negative pressure, nitrogen oxide can be supplied safely at a predetermined concentration, and the time and energy cost required for the sterilization operation can be reduced. Can be reduced. Further, after the sterilization treatment, nitrogen oxides are efficiently removed and no nitrogen oxide component remains in the sterilization target, so that the sterilized instrument can be safely reused.

Schematic showing a first embodiment of a sterilizer according to the present invention Graph showing saturation vapor pressure curve of dinitrogen tetroxide (nitrogen dioxide) Schematic showing a second embodiment of the sterilization apparatus according to the present invention Schematic showing a third embodiment of the sterilization apparatus according to the present invention Schematic showing a fourth embodiment of a sterilization apparatus according to the present invention

  An embodiment in which the sterilization method and sterilization apparatus using dinitrogen tetroxide according to the present invention is applied to the sterilization operation of a medical device will be described below with reference to FIGS.

  As shown in FIG. 1, a medical device (1) of an object to be sterilized is placed in a receiving cavity (2) formed in a sterilization chamber (10). The present invention can be applied to medical devices (1) made of any material that does not deteriorate against nitrogen oxides, such as metal, plastic, rubber, etc., and the medical device (1) is a surgical instrument such as a scalpel, forceps, scissors, tweezers, etc. Diagnostic instruments such as soft and rigid endoscopes, thermometers, stethoscopes, ophthalmoscopes, otoscopes, therapeutic instruments such as catheters, syringes, medical tubes, pacemakers, implantable aggregates, surgical bolts, etc. Includes medical equipment. The objects (1) to be sterilized include plastic containers, glass containers, vials, spray containers, aluminum tubes, rubber stoppers, elastomer resin parts, and pharmaceutical containers such as injection needles. The present invention can be applied not only to pre-sterilization but also to in-use sterilization immediately before use. A lid (not shown) is attached to the accommodation cavity (2) in which the medical device (1) is arranged, and the accommodation cavity (2) is hermetically closed, and the sealed state of the accommodation cavity (2) is maintained.

In the housing cavity (2) in the sterilization chamber (10) for housing the medical device (1), a suction pipe (11) connected to the discharge port (6) and the discharge port (6) provided in the sterilization chamber (10). ) And the vacuum pump (decompression device) (3) is connected, and when the vacuum valve (24) is open, the vacuum pump (3) sucks the gas (gas) in the storage cavity (2) into the storage cavity. (2) is depressurized. It is preferable to release the suction gas into the atmosphere after the bacteria in the suction gas are filtered and removed by the removal filter (19) connected to the vacuum pump (3). A storage tank (4) containing liquid dinitrogen tetroxide (N ₂ O ₄ ) is connected to the receiving cavity (2) via the introduction pipe (12) and the introduction valve (5). Dinitrogen tetroxide is a strong oxidizer, but in a liquid state if the storage tank (4) is pressurized and filled at a temperature of 21 ° C. (boiling point) or lower or an absolute pressure of about 200 kPa (about 2 atmospheres). It can be stored safely. FIG. 2 shows a saturated vapor pressure curve of dinitrogen tetroxide (nitrogen dioxide) that is in chemical equilibrium with the temperature [° C.] on the horizontal axis and the vapor pressure [kPa] on the vertical axis. Represents a liquid state and a gas state, respectively. For example, it is liquid at point O2 in a state where the storage tank (4) is pressurized and filled with liquid dinitrogen tetroxide at 15 ° C. under atmospheric pressure as indicated by point O1 at an absolute pressure of 200 kPa (about 2 atm). The pressure of dinitrogen tetroxide filled in the storage tank (4) is increased by the nitrogen gas pressure of the pressurization device (16) connected to the storage tank (4). Dinitrogen tetroxide has the following chemical equilibrium with nitrogen dioxide (NO ₂ ).

N ₂ O ₄ = 2NO ₂ -57.2 kJ

  In the chemical equilibrium formula, when the pressure is increased at a constant temperature, the reaction proceeds to the left and the proportion of dinitrogen tetroxide increases. Conversely, when the pressure is lowered, the reaction proceeds to the right and the proportion of nitrogen dioxide increases. Dinitrogen tetroxide itself is colorless, but exhibits a color derived from nitrogen dioxide through chemical equilibrium, that is, reddish brown for gas and yellow for liquid. In the present invention, not only dinitrogen tetroxide but also dinitrogen trioxide and nitrous pentoxide can be used as liquid nitrogen oxides, and two or more kinds of dinitrogen tetroxide, dinitrogen trioxide and dinitrogen pentoxide can be used. It can also be used in combination.

  When the introduction valve (5) is opened while the pressure of the storage cavity (2) is reduced by the vacuum pump (3) or the pressure of the storage cavity (2) is kept in vacuum, the liquid nitrous oxide is stored. Nitrogen tetroxide is supplied from the storage tank (4) to the containing cavity (2) through the introduction pipe (12) in a pressurized state. For this reason, nitrous oxide does not vaporize between the storage tank (4) and the inlet of the receiving cavity (2), and an accurate amount of liquid nitrous oxide can be supplied. A reliable sterilization process can be performed by always maintaining dinitrogen tetroxide at a desired concentration. A spray device (25) for atomizing dinitrogen tetroxide is provided at the entrance of the housing cavity (2). The spray device (25) is a nozzle or a valve. Any spraying device (25) capable of adjusting or not adjusting the nozzle hole area can be used. The flow rate of dinitrogen tetroxide supplied to the accommodation cavity (2) is measured by a flow meter (13) disposed in the introduction pipe (12). In this case, the flow rate of nitrous oxide can also be calculated from the pressure difference between the liquid storage tank (4) passing through the introduction valve (5) and the containing cavity (2). Further, the pressure and temperature of the housing cavity (2) are measured by the pressure gauge (14) and the thermometer (15) connected to the housing cavity (2). The degree of vacuum of the housing cavity (2) is preferably 0.5 kPa to 80 kPa, which is included in the range of low vacuum (absolute pressure 100 Pa to atmospheric pressure).

  At least a portion of the nitrous oxide introduced into the housing cavity (2) under negative pressure moves from the point O2 at 15 ° C. and 200 kPa in FIG. And the proportion of nitrogen dioxide increases according to the chemical equilibrium equation. As a result, the liquid is instantly vaporized and gaseous nitrogen dioxide is dispersed throughout the containing cavity (2), and instantly enters the details of the medical device (1). Gaseous nitrogen dioxide comes into contact with and adheres to the entire surface, which strongly oxidizes or nitrates the deposits on the surface and sterilizes the medical device (1) quickly and reliably. The sterilization time while maintaining the negative pressure and the predetermined temperature of the housing cavity (2) is several tens of seconds to several tens of minutes depending on the capacity of the housing cavity (2) and the size and quantity of the medical device (1). It selects suitably in the range of. Further, if a heater (21) is provided adjacent to or in the introduction pipe (12), the dinitrogen tetroxide introduced into the accommodation cavity (2) is heated to promote vaporization. The rate at which nitrogen dioxide increases can be controlled. The temperature of dinitrogen tetroxide may be controlled in the range of 30 to 50 ° C. or 50 to 80 ° C. by the heater (21). The heater (21) is provided with a housing that surrounds the introduction pipe (12), and a heating medium such as a spiral, fin, coil, or serpentine pipe has a large surface area on the outer surface of the introduction pipe (12). The liquid nitrogen oxide passing through the inside of the introduction pipe (12) can be heated by contact with steam or a heating fluid by thermal contact. In addition, heating elements such as nichrome wire and film heater provided on the outer surface of the introduction pipe (12) can be used as the heater (21), and a part of the introduction pipe (12) is electrically insulated and insulated. The introduction pipe (12) itself may be used as a heating element by energizing from both ends. Furthermore, an electrode may be installed inside the introduction pipe (12) (in the fluid), and the internal fluid may be directly heated by Joule heat by applying a voltage.

  In this embodiment, not only dinitrogen tetroxide is introduced into the accommodation cavity (2), but also the dilute gas is accommodated by the gas supply device (17) before, after or simultaneously with the introduction of dinitrogen tetroxide. Can be added to the cavity (2). If a diluting gas is added to the housing cavity (2), the nitrogen dioxide changed from dinitrogen tetroxide can be diluted to reduce the amount of dinitrogen tetroxide to be used and sterilize at low cost. In addition, the concentration of nitrogen dioxide can be freely adjusted according to the size, quantity, shape, and material of the medical device (1) to be sterilized placed in the containing cavity (2), and water vapor, oxygen, nitrogen, air And an appropriate diluting gas can be selected from one or more of inert gases. The diluting gas not only dilutes nitrogen oxides containing nitrogen dioxide as a main component in the housing cavity (2), but also water vapor adjusts the humidity and oxygen exerts a bactericidal action as an oxidizing agent. The concentration of nitrogen dioxide relative to the total gas including the dilution gas is, for example, 0.01 to 80% on a volume basis.

  After sterilizing the medical device (1), the vacuum valve (24) is closed, and the gaseous nitrogen oxide in the storage cavity (2) is sucked from the discharge port (6) by the vacuum pump (3) and stored. A cooling device (22) connected to the cavity (2) is passed. In the cooling device (22), the gaseous nitrogen oxide is cooled below the temperature at which the nitrogen oxide used is sufficiently liquefied (arrow B in FIG. 2), and dinitrogen tetroxide is the main component from the drain pipe (23). The liquefied nitrogen oxide is recovered. If nitrogen oxides are cooled at 4 to 10 ° C., liquefied dinitrogen tetroxide can be efficiently recovered. Further, nitrogen gas is introduced into the accommodation cavity (2) from the gas supply device (17), or air is introduced into the accommodation cavity (2) through the return pressure filter (18) by the return pressure valve (7) as a pressure control device. After the introduction, the cleaning operation of sucking with the vacuum pump (3) may be performed again. By repeating this operation, nitrogen oxides remaining in the housing cavity (2) and the medical device (1) can be completely removed. The return pressure filter (18) blocks all bacteria present in the air and supplies sterile air to the housing cavity (2).

  After removing liquefied dinitrogen tetroxide from the drain pipe (23), air is introduced into the containing cavity (2) through the return pressure valve (7) and the return pressure filter (18), and the containing cavity (2) is at atmospheric pressure. Then, the lid of the sterilization container (10) is opened, and the medical device (1) is taken out from the accommodation cavity (2). During sterilization, gaseous nitrogen oxides come into contact with the entire area of the medical device (1), and bacteria and viruses are completely killed and destroyed, so that the medical device (1) can be reused immediately. Since the sterilant component is completely recovered by sucking nitrogen dioxide in the housing cavity (2), it is non-toxic to human body and extremely safe.

  In the above embodiment, an example of recovering gaseous nitrogen oxide filling the accommodation cavity (2) by suction has been shown, but hereinafter, the accommodation cavity (2) is pressurized to liquefy and collect gaseous nitrogen oxide. A second embodiment will be described with reference to FIG.

  After the sterilization operation is completed, air or other inert gas is introduced into the housing cavity (2) under negative pressure through the return pressure filter (18) by the return pressure valve (7) as a pressure control device, and the vapor pressure curve is moved upward. When the pressure in the accommodation cavity (2) is increased beyond this (arrow C in FIG. 2), liquefaction of gaseous nitrogen oxide proceeds. As a result, the gaseous nitrogen oxide that contacts the details of the medical device (1) is liquefied, and at the same time, the liquid nitrogen oxide falls to the bottom of the housing cavity (2). While the nitrogen oxide is liquefied, the introduced air maintains a gaseous state, so that the nitrogen oxide can be efficiently separated from the air, and the recovery time can be shortened. Nitrogen oxide liquefied at a temperature of 20 ° C. and atmospheric pressure (101.3 kPa) is approximately 25% nitrogen dioxide and approximately 75% dinitrogen tetroxide with respect to all nitrogen oxides according to the chemical equilibrium equation. Exists.

  Next, the drainage valve (20) is opened, and through the discharge port (6) provided at the bottom of the sterilization chamber (10), a liquid nitrogen oxide mainly containing dinitrogen tetroxide is contained (2 ) To the outside. This makes it possible to recover dinitrogen tetroxide with high efficiency from the outlet (6) without the need to provide additional equipment such as a ventilator for exhausting gaseous nitrogen oxides. The gas introduced to pressurize the housing cavity (2) is not limited to air, and nitrogen gas can also be used. A centrifuging mechanism is provided in the sterilization chamber (10) to forcibly remove the liquefied nitrogen oxide from the medical device (1), and the liquefied nitrogen oxide remaining in the medical device (1) in the containing cavity (2) May be completely removed.

  In the second embodiment, the nitrogen oxide is liquefied by increasing the pressure of the housing cavity (2). Alternatively, the temperature of the housing cavity (2) is lowered by a temperature control device (not shown). The nitrogen oxides contained in the accommodation cavity (2) can also be liquefied.

  In the third embodiment shown in FIG. 4, unlike the first and second embodiments, a pressure gauge (56) is provided upstream of the introduction valve (5) without providing a flow meter (13). Place. Since the unit time flow rate of liquid nitrogen oxide is determined by the pressure value of the pressure gauge (56) and the inner diameter of the introduction pipe (12), by controlling the opening and closing time of the introduction valve (5) according to the pressure value, the accommodation cavity The supply amount of liquid nitrogen oxide delivered to (2) can be easily and accurately controlled.

  In the fourth embodiment shown in FIG. 5, a sterilization apparatus in which a storage tank (4) is preliminarily filled with a liquid nitrogen oxide by a required amount is shown. In this embodiment, when sterilizing the object (1) in the accommodation cavity (2), the introduction valve (5) is connected with the storage tank (4) connected to the accommodation cavity (2) through the introduction pipe (12). By opening, all liquid nitrogen oxides are discharged from the storage tank (4). For this reason, a constant amount of liquid nitrogen oxide can always be supplied to the accommodation cavity (2) without performing flow rate control, and the object (1) can be reliably sterilized. The storage tank (4) may be a small cylinder. Further, in this embodiment, the flow meter (13), the pressurizing device (16), and the pressure gauge (56) on the upstream side of the introduction valve (5) are not required.

  In the first to fourth embodiments, the introduction valve (5) is disposed between the storage tank (4) and the heater (21), but between the heater (21) and the accommodation cavity (2). An introduction valve (5) may be provided. Further, the spraying device (25) formed at the inlet of the housing cavity (2) with or without the introduction valve (5) may be used as the valve.

  Examples in which a sterilization test of microorganisms was performed using the sterilization method and sterilization apparatus according to the present invention will be described below.

Sterilization test An SCBI (Self-Contained Biological Indicator) was placed in the accommodating cavity (2) of about 8 L (20 cm x 20 cm x 20 cm) in the vacuum chamber (10). SCBI is a sterilization test kit in which a filter paper with attached microorganism spores and a glass capsule containing a culture solution are housed in a small test tube and sealed with aeration filter paper. In a state where the storage cavity (2) where the SCBI is disposed is reduced to 5 kPa, liquid dinitrogen tetroxide (N ₂ O ₄ ) having a pressure higher than atmospheric pressure is introduced into the storage cavity (2) and vaporized by the spraying device (25). I let you. Immediately after the dinitrogen tetroxide is vaporized, the return pressure valve (7) is opened and clean air is introduced to maintain the nitrous oxide concentration in the containing cavity (2) at 8500 ppm (16.54 mg / L) for 20 minutes for sterilization. Processed.

  After sterilization, dinitrogen tetroxide was removed from the SCBI small test tube by pressure operation, and then the vacuum chamber (10) was opened and the SCBI was taken out from the housing cavity (2). The glass capsule was broken in a small test tube, the filter paper was immersed in the culture solution, and the sterilized SCBI was cultured in a 58 ° C. incubator for about 24 hours (sterilization SCBI). On the other hand, SCBI which was not sterilized and left in the atmosphere for 20 minutes was similarly cultured in a 58 ° C. incubator for about 24 hours (non-sterilized SCBI).

Test result The sterilization SCBI showed no change, indicating that the microorganisms were not growing, and it was confirmed that the sterilization was sufficiently performed. On the other hand, non-sterilized SCBI showed discoloration, and it was confirmed that microorganisms were growing without being sterilized.

  The present invention can be applied to sterilization of medical equipment, precision machinery, electronic parts, pharmaceutical raw materials, pharmaceutical containers, foods, food raw materials, food containers, and all other microbial adherents. The present invention can also be applied to the beverage field and the pharmaceutical field dealing with microorganisms.

  (1) ・ ・ Object (medical equipment), (2) ・ Containment cavity, (3) ・ Decompression device (vacuum pump), (4) ・ Storage tank, (6) ・ ・ Discharge port, (7 ) ・ ・ Pressure control device (return pressure valve),

Claims (19)

Placing the object in the containment cavity;
The process of depressurizing the containment cavity to a reduced pressure state or vacuum state below the saturated vapor pressure curve of dinitrogen tetroxide by a decompression device while holding the containment cavity in a sealed state;
Supplying liquid nitrous oxide to a spraying device without vaporizing from a storage tank containing liquid nitrous oxide;
Spraying liquid dinitrogen tetroxide through a spraying device into a vacuum or vacuum containing cavity;
A process in which at least a portion of the liquid nitrous oxide sprayed into the receiving cavity through the spraying device is vaporized by reducing the pressure below the saturation vapor pressure curve, and the object is sterilized with gaseous nitrous oxide in the receiving cavity; A sterilization method using dinitrogen tetroxide characterized by comprising:   The process of supplying the liquid nitrous oxide to the spraying device without vaporizing is performed by supplying the liquid nitrous oxide contained in the storage tank in a pressurized state to the spraying device at the entrance of the storage cavity. The sterilization method according to claim 1, comprising a step of preventing vaporization of liquid nitrous oxide until it reaches   The sterilization method according to claim 2, wherein the step of supplying liquid nitrous oxide to the spraying device without vaporizing includes a step of measuring and controlling the flow rate of liquid nitrous oxide using a flow meter or a pressure gauge. Including a process of pressurizing and filling liquid nitrous oxide in a small amount as a storage tank in advance.
The process of supplying liquid nitrous oxide includes the process of opening the introduction valve of the introduction pipe connecting the small cylinder and the accommodating cavity and discharging all liquid nitrous oxide from the small cylinder through the introduction pipe. Item 3. The sterilization method according to Item 2.   The object is selected from one or more of medical equipment, precision machinery, electronic components, pharmaceutical raw materials, pharmaceutical containers, food, food raw materials, food containers, and microbial adherents. The sterilization method according to item. Introducing a dilute gas into the containment cavity before, after or simultaneously with spraying the liquid nitrous oxide on the containment cavity;
The sterilization method according to any one of claims 1 to 5, wherein the diluting gas is selected from one or more of water vapor, oxygen, nitrogen, air and inert gas.   The sterilization method according to any one of claims 1 to 6, wherein the process of spraying liquid dinitrogen tetroxide into the housing cavity includes a process of atomizing liquid dinitrogen tetroxide. After sterilizing the object, the process of sucking and collecting gaseous nitrous oxide through the outlet of the containment cavity;
The sterilization method according to any one of claims 1 to 7, further comprising a step of cooling and collecting the collected gaseous dinitrogen tetroxide to liquefy. Placing the object in the containment cavity;
The process of holding the containment cavity in a sealed state and depressurizing the containment cavity with a decompression device;
Introducing liquid dinitrogen tetroxide from a storage tank containing liquid dinitrogen tetroxide into a vacuum or vacuum containing cavity;
A process in which at least part of the introduced liquid dinitrogen tetroxide is vaporized by reducing the pressure below the saturated vapor pressure curve of nitrous oxide in the containing cavity;
Sterilizing the object with gaseous nitrous oxide in the containment cavity;
After sterilizing the object, pressurizing or cooling the containment cavity to liquefy gaseous dinitrogen tetroxide beyond the saturation vapor pressure curve;
A process of recovering liquefied nitrous oxide from the containment cavity through the outlet;
A method of sterilizing with dinitrogen tetroxide, comprising the step of removing the object from the containing cavity. A storage tank containing liquid dinitrogen tetroxide;
An accommodation cavity capable of accommodating an object and holding it in a sealed state;
A spraying device provided in the receiving cavity and connected to the storage tank;
A depressurization device for depressurizing the containing cavity to a depressurized state or a vacuum state below a saturated vapor pressure curve of dinitrogen tetroxide, and
Supplying liquid nitrous oxide from the storage tank to the spraying device without vaporizing, spraying the liquid nitrous oxide to the containment cavity under reduced pressure or vacuum through the spraying device,
Dinitrogen tetroxide sprayed into the housing cavity through the spraying device is vaporized by reducing the vapor pressure below the saturated vapor pressure curve to sterilize the object in the housing cavity. By sterilizer. An introduction pipe connecting the storage tank and the receiving cavity;
An introduction valve provided in the introduction pipe,
By opening the introduction valve, liquid nitrous oxide contained in the storage tank is supplied through the introduction pipe to the spraying device at the inlet of the containing cavity under pressure, and the liquid tetraoxidation is performed until the spraying device is reached. The sterilizer according to claim 10, which prevents vaporization of dinitrogen.   The sterilizer according to claim 11, wherein the flow rate of the liquid dinitrogen tetroxide supplied to the accommodation cavity is measured by a flow meter provided in the introduction pipe.   The sterilization apparatus according to claim 11, wherein the supply amount of liquid dinitrogen tetroxide delivered to the accommodation cavity is controlled by controlling the opening and closing time of the introduction valve in accordance with the pressure value of a pressure gauge provided upstream of the introduction valve. . The storage tank is composed of a small cylinder pre-filled with liquid nitrous oxide for the required amount in advance,
The sterilizer according to claim 11, wherein the small cylinder is connected to the accommodation cavity through the introduction pipe, the introduction valve is opened, and all the liquid nitrous oxide is discharged from the small cylinder to sterilize the object in the accommodation cavity.   The target object is selected from one or more of medical equipment, precision machinery, electronic components, pharmaceutical raw materials, pharmaceutical containers, food, food raw materials, food containers, and microbial adherents. The sterilizer according to item.   The sterilizer according to any one of claims 10 to 15, wherein the spray device atomizes the liquid dinitrogen tetroxide introduced into the housing cavity. An outlet provided in the receiving cavity and connected to the decompression device;
A cooling device connected to the discharge port and the decompression device,
The sterilizer according to any one of claims 10 to 16, wherein the dinitrogen tetroxide gas exhausted from the accommodation cavity through the discharge port by the decompression device is cooled and liquefied by the cooling device. A storage tank containing liquid dinitrogen tetroxide;
An accommodation cavity connected to the storage tank and capable of accommodating an object and holding it in a sealed state;
A decompression device for decompressing the containing cavity to a decompressed state or a vacuum state below a saturated vapor pressure curve of dinitrogen tetroxide;
A pressure control device for increasing the gas pressure in the housing cavity;
A discharge port provided at the bottom of the housing cavity,
Introducing liquid dinitrogen tetroxide from the storage tank into the containment cavity held in a reduced pressure or vacuum state by a decompression device,
At least part of the introduced liquid dinitrogen tetroxide is vaporized by reducing the vapor pressure below the saturated vapor pressure curve of dinitrogen tetroxide in the containing cavity, sterilizing the object in the containing cavity,
A sterilizer characterized in that, after sterilization of an object, the gas pressure in the accommodation cavity is increased by a pressure control device to liquefy dinitrogen tetroxide, and the liquefied dinitrogen tetroxide is discharged from the discharge port. A storage tank containing liquid dinitrogen tetroxide;
An accommodation cavity connected to the storage tank and capable of accommodating an object and holding it in a sealed state;
A decompression device for decompressing the containing cavity to a decompressed state or a vacuum state below a saturated vapor pressure curve of dinitrogen tetroxide;
A temperature control device for lowering the temperature of the containing cavity;
A discharge port provided at the bottom of the housing cavity,
Introducing liquid dinitrogen tetroxide from the storage tank into the containment cavity held in a reduced pressure or vacuum state by a decompression device,
At least part of the introduced liquid dinitrogen tetroxide is vaporized by reducing the vapor pressure below the saturated vapor pressure curve of nitrous oxide in the containing cavity, and sterilizing the object in the containing cavity,
A sterilizer characterized in that, after sterilization of an object, the temperature of the housing cavity is lowered by a temperature control device to liquefy dinitrogen tetroxide, and the liquefied dinitrogen tetroxide is discharged from the discharge port.

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