DE2744637B2 - Method and device for sterilizing objects with the aid of a liquid sterilizing agent - Google Patents

Description

The invention relates to a method and a device as described in the preamble of patent claims 1 and 5 mentioned Art.

Such a method and such a device are already known (DE-AS 18 15 538). With this one known method is blown hot air heated to 230 ° C on a surface provided with a coating, thereby evaporating the sterilant previously inflated on the surface worder. was. Due to the small additional droplets when applying a very fine spray of the Sterilizing agent on the material creates an uneven distribution of the sterilizing agent

ίο the same thing inexpedient for various reasons is. In addition, difficulties arise when corners, niches or the like of preformed Containers should be well sterilized without residues of sterilizing agent remaining there and without the material consisting in particular of thermoplastic material being heated too much.

In addition, a method is known (DE-OS 18 02 778) in which the object to be sterilized does not come into contact with liquid particles. There it is ensured that the sterilizing agent is available the contact with the object to be sterilized splits into its gaseous phase, including in nascie / end oxygen, which has the sterilizing effect evokes. This procedure uses sterilant mixed with compressed air.

In addition, sterilization methods are known in which the material to be sterilized by a bath of the sterilant is drawn and the sterilant is drawn from the

jo surface of the material can be removed again. Of the However, the latter process step, i.e. the complete removal, presents difficulties. aside from that this method cannot readily be applied to already preformed objects.

γ, Finally, it is also known to sterilize by evaporation of the sterilizing agent and evaporation of the same to carry out the object to be sterilized as well as subsequent cooling, thereby forming a precipitate. Although the resulting

If the coating is relatively uniform, it has been shown that too high a water content leads to a Inadequate sterilization leads, in particular, when higher temperatures are present, since hot Water counteracts the sterilizing effect of the sterilizing agent.

The invention is based on the object of providing better control and sterilization without that there is a risk of remaining sterilant residues on the sterilized object and without it that the risk of thermal damage to the material due to the use of excessively high temperatures in Purchase must be made.

The invention is in claim 1 with regard to the method and in claim 5 with regard to the Device for performing the method characterized. Further training and improvements of the invention emerge from the claims.

The fact that tiny droplets of the sterilizing agent are evaporated creates a connection

with other partial features overcoming the disadvantages of the previously known methods. As a result of exceptionally small droplets, the hot air can instantly vaporize these "mini-droplets", so that also the actual sterilizing agent, in particular

_b 5 hydrogen peroxide, completely evaporated and absorbed by the air. The dry hot air is actually "moistened" by the sterilizing agent; no real "fog" arises. The Ver-

Steam product / nut cannot be seen at all with the naked eye be perceptible, as is the case, for example V ei air with high "humidity".

The efficiency of the process according to the invention is therefore also much better than with known ones', Process, because the air can "carry" the sterilizing agent much longer, which also ensures * v that the evaporation product even in very distant areas - in small corners and niches of in particular prefabricated disposable containers or parts thereof - arrived and not before "Fails" or does not "fall down" beforehand.

In addition, practical Always the same amount of sterilizing agent absorbed into the air , thereby avoiding that the! ■> The moisture level of the mixture fluctuates in an uncontrolled manner between large limits.

The heating or the "evaporation" (spraying) of the sterilizing agent by hot air even causes it an overlapping effect: the ; product contains a precisely adjustable concentration of the sterilizing agent and therefore also of the Dew point. The consequence of this is that it depends on the temperature of the object to be sterilized the time after which the vapor-deposited product can condense can be predicted fairly precisely and this happens in a soft layer thickness. From this one can in turn deduce after what time sufficient sterilization has taken place. The controllability of the sterilization process according to the invention is r therefore substantially favored without the risk of a there is uneven stabilization.

The invention can therefore be used advantageously for sterilizing disposable packs or so-called disposable packs »Disposable containers«, which are mainly used to package liquid food, such as milk or others Drinks dzw. Dairy products. Such disposable packs are for example made from a tube made of multilayer packaging material. Such packs point because of the production of longitudinal seams - for tube formation - and transverse seams - for subdivision of the hose in single sectionsp - pronounced places that are difficult to access, such as niches; by using the method according to the invention 'However, such packs can also be sterilized quickly and easily.

The invention is described in more detail below with reference to the drawing, which shows an exemplary embodiment of the arrangement for carrying out the method in this way. The schematic figure illustrates the use of the invention in a packaging machine for producing packaging from a continuously moving web.

The invention uses the known property of air to absorb, retain or release moisture as a function of the temperature. The air's ability to retain moisture increases and decreases with temperature. When a certain amount of atomized liquid or vapor is blown into heated air, it will be absorbed and retained by the air as long as the temperature is sufficiently high, ie higher than the condensation or dew point of the mixture. If, for one reason or another, the temperature of the air so saturated falls below the condensation or dew point, it is no longer able to hold back such a large amount of liquid, but releases part of the liquid which condenses. This phenomenon can now be used to cover a certain surface with an even layer of the liquid retained by the air, in that a body of a lower temperature than the condensation temperature of the air is introduced into the humidified air. That part of the air that comes into contact with the body is cooled down, and the moisture is deposited and condenses on the surface of the body. During the condensation heat is released, which warms the colder body, and the condensation therefore only lasts as long as the temperature of the surface is sufficiently low.The amount of precipitated liquid is therefore a direct function of the temperature of the surface, i.e. the enthalpy and thermal conductivity of the body. If it is assumed that these quantities are the same for the entire surface, the process must be exactly the same on every part of the surface, and in this way a condensation which is invariable over the entire surface is achieved and the surface therefore with a uniform layer of the surface in question Liquid coated.

The principle just described can also be used to cover a given surface with a uniform layer of a liquid sterilizing agent for sterilization purposes. This can be done by using a suitable liquid sterilant to moisten the air. Since the air normally contains a certain amount of water, it is desirable to remove as much water as possible from the air, ie to make the air as dry as possible, in order to avoid dilution of the sterilizing agent. This dry air is supplied with energy or heat in such an amount that the sterilizing agent can evaporate and the air then still has a temperature sufficient to retain the desired amount of sterilizing agent. By controlling or regulating the temperature of the air and the quantitative ratio of sterilizing agent and air, the condensation or dew point of the air moistened with the sterilizing agent can be adjusted to a temperature that is a certain 5 'higher than the temperature of the sterilizing agent area to be covered. When the desired mixture of air and sterilant is achieved, the mixture is fed to the surface to be sterilized, which cools the air and reduces its ability to retain sterilant so that a large part of the sterilant condenses on the surface after a suitable reaction time , which depends on the type and concentration of the sterilizing agent and the required bactericidal effect, the sterilizing agent is removed again. This can be done in various ways, for example by means of hot air or by irradiation with a heating element such as an infrared lamp.

In the following, the method will now be based on its Application in a packaging machine of known type described in more detail. In the schematic Representation is shown on the right side of the figure, the packaging machine. The machine processes a packaging material web 1 which is wound onto a roll 2. Lane 1 is taken from the roll passed through two chambers 3, 4 connected in series, which are described in more detail below will. Lane 1 becomes over two

Deflection rollers 5, and then vertically downwards through the packaging machine during the downward movement through the machine is converted into the web to a hose or tube 6 by its two longitudinal edges joined and sealed along a longitudinal seam. After forming the web into a tube and sealing it along the longitudinal seam, the desired filling material, for example milk, is introduced through a filling tube 7 which extends through the open upper end of the tube towards its lower end and ends there. At a certain distance below the lower end of the filling tube, the sealing jaws 8 are arranged, which provide the filled tube 6, which progresses in the vertical direction, with transverse seals at equal intervals, in the area of which the tube is divided by likewise aligned cuts. The packages 9 formed in this way and completely filled are then passed to a post-processing or refolding station 10 , in which they are given a parallelepiped shape.

The sterilization system, which interacts with the packaging machine, has an air compressor 11, a cooler 12 connected to this for the compressed air and a water separator 13 in which the moisture precipitating from the air is removed. The air dried in this way is fed via a pipe system to two control valves 15, 16 which determine the continuous flow. The main mass of the air is supplied via the control valve 15 to a heating arrangement or a heating element 17, which supplies the desired amount of energy or heat to the air. The air then flows from the heating element 17 into a chamber 18. At the upper end of the chamber there is an ultrasonic nozzle 19 which is operated with the part of the air flow from the water separator 13 controlled by the control valve 16. A supply line for sterilizing agent also leads to the ultrasonic nozzle 19 and is supplied to the nozzle 19 via suitable lines and a pump 21 from a container 20. The ultrasonic nozzle is of known design and works in such a way that the air flow from the control valve 16 generates a standing wave of very high frequency (approx. 30 kHz), into which the standing wave sterilizing agent is introduced, causing the liquid to form droplets the size of 5 to 15μπι is atomized. This highly atomized liquid or mist is mixed with hot air in the container or mixing chamber 18 so that the mist is converted into steam which is guided through a pipe 22 into the aforementioned chamber 3 through which the packaging material is on its way passes from the roll 2 to the forming part of the packaging machine.In the chamber 3, the mixture of sterilizing agent and air is brought into contact with the movable material web 1, and this cools the mixture so that the sterilizing agent condenses into a uniform layer on the web surface Sterilizing agent which condenses on the wall of the chamber is removed through a drain pipe 23.

As already mentioned above, the web 1 migrates through a further chamber 4, that of the chamber 3, in the direction the path movement is seen downstream at some distance If in the chamber 3 the layer of the sterilant has been applied to the web 1, the web exits the chamber 3 and after a certain distance into the chamber 4, in which the sterilizing agent is removed again from the web will. The distance between the chambers 3 and 4 determines the time during which the path of the Effect of the sterilant is exposed, and is such that this period of time is sufficient to to bring about the desired germicidal effect. The removal of the sterilant from the web in the chamber 4 takes place by means of a stream of hot air which is generated in a water ring compressor 24. Of the Water ring compressor is of a known type, and the

ίο generated compressed air is passed through a water separator 25, which removes the remaining sealing water from the air from the water ring, and reaches the chamber 4 via a heating element 26 Air is again supplied to the water ring compressor 24, in which the sterilizing agent is removed from it, and the sterilizing agent is mixed with the sealing water and separated in the water separator 25.

As can be seen from the above, it is important for the process that the air used is able to absorb a certain amount of hydrogen peroxide. To make this possible and to prevent the hydrogen peroxide from being mixed with the moisture normally present in the air, dried luff is used. This is obtained by compressing the air by means of the compressor 11 to a pressure of 6 to 7 kp / cm ² . The air heated by the compression is then fed to the cooler 12, in which it is cooled to a temperature of 15 to 20 ° C. This causes a large proportion of the moisture carried along by the air to condense, and this is eliminated in the downstream water separator 13. The dried air obtained in this way now has an absolute moisture content reduced from approx. 0.01 to 0.003 kg / kg.

As already mentioned, the dried air is fed partly via the heating element 17 to the mixing chamber 18 and partly to the ultrasonic nozzle 19, so that it actuates the latter and generates the standing wave which atomizes the sterilizing agent also fed to the ultrasonic nozzle. The standing wave has a frequency of approx. 30 kHz and breaks up the pumped sterilizing agent into a mist with a droplet size of approx. The mist is sprayed directly into the mixing chamber 18, in which it meets and is mixed with the main mass of the dried air from the water separator 13, which has been supplied with the desired amount of heat in the heating arrangement 17 by heating to a high temperature. The high temperature has the effect that the droplets of the sterilant which form the injected mist are brought to a boil and vaporize directly. The temperature of the mixture is thereby reduced to about 100 ⁰ C, and the condensation temperature, or dew point at an absolute moisture content of about 0.150 kg / kg is approximately 60 ° C. This dew point ensures as determined, condensing the sterilizing agent on the material web 1 even under unfavorable conditions, ie when the outside air temperature is high. Of course, the dew point can be shifted up or down by changing the quantity ratio of sterilizing agent and air.

The mixture of sterilant vapor and air that reaches the chamber 3 is guided in such a way that it

7th 8th

through the entire length of the chamber along the proportions as well as other liquid sterilization

Packaging material web 1 flows. The dividing means is conceivable. The ones in the description

of the mixture, the numerical values given with the packaging material sheet relate to the case

come into contact, cooled down, and the sterilization of the use of hydrogen peroxide and water

agent condenses on the surface of the web to form 5 water.

an even layer. When condensing, if a sterile type packaging machine is used in Heat is released, and this reaches the material web and is to be put into operation, it is important that the heats this. The condensation process continues until parts of the machine that contain the product or the the temperature difference is equalized (whereby the web of packaging material comes into contact it is believed that the relevant portion of FIG. 10 may be pre-sterilized. It is known this Packaging material web 1 the chamber 3 is not already pre-sterilized on one of several different this time leaves). As the walls of the chen species carry out. For the described Chamber 3 is on a procedure at least at the start of operations and the arrangement shown is more expedient Temperature are than the air mixture, Big, as during the operation of the machine, from which in the sterilizing agent also condenses on these. 15 of the chamber 18 generated mixture of air and The excess sterilant will make use of the sterilant. If the Chamber 3 is derived via the tube 23 and can be pre-sterilized in the machine, so the be collected in a vessel. From the chamber 3 output nozzle of the mixing chamber 18 in such a way escaping air still contains a certain amount with the parts of the packaging that are to be pre-sterilized of sterilizing agent and can therefore be used as a machine (the supply pipe for the filling material that is in the moderately again the water ring compressor 24 supplied tubular part of the packaging material in which the sterilizing agent then protrudes, the elements for regulating the contents mixed with the sealing water and mirrored in the dehumidifier, etc., the chamber in which the packaging 25 can be separated from this again, material web 1 from the chamber 3 into the sealing

After a suitable reaction time, the station is running, etc.) in such a way that a closed

Sterilizing agent in the chamber 4, as already nes system is created through which the mixture

described, can be circulated by the packaging material web 1. As the walls of the pipes and

removed by continuously passing lines through this chamber through which the mixture is circulated

Hot air with a temperature of approx. 130 ° C through - temperature below the dew point of the mixture

is sent. Appropriately, the air will have 30, condensation of the sterilizing agent

this chamber to remove the sterilizing agent instead. The mixture is made to last long enough

means also to flow through the machine via a return line to ensure that

Water ring compressor 24 returned. to sterilize the sterilizing agent on all

The sterilant can also condense from the web in the surfaces. After the feed is finished

removed in another suitable manner, 35 of the sterilizing agent mixture, the condensing agent

for example by the web through a heating element te sterilizing agent after a corresponding

of the infrared type is heated. Response time eliminated again by through the

When the packaging material web 1 is sent from the sterilization lines hot air. This will be

is completely freed, this runs in against the walls, so that the sterilizing agent

Bacteria and contamination are protected by vaporization and the steam escapes with the hot air

the packaging machine in which they are in the further up the machine. Blowing in the hot air is

described manner to a pipe or hose 6 brought about that the water ring compressor

is converted, which is filled with sterile filling material, 24, the water separator 25 and the heating element 26

transversely sealed and to form completely filled via a suitable valve with the to be sterilized

Single packaging container is cut up. 45 rooms can be connected.

In this way it is possible to use the pre-sterilization of packaging machines of any known type of packaging machine. If the arrangement is to be used in conjunction with the method described in association and the arrangement shown with a packaging machine for processing prefabricated blanks without great expense in terms of facilities, 50 men. The pre-sterilization is particularly effective, since the chambers 3 and 4 must of course be modified in a suitable manner similar to the sterilization of the packaging material and the shape of the packaging material web sterilizing agent must be adapted to each part and in cut material. However, the description of each cavity along the path of movement of the functional processes applies to packaging material web is brought to condensation, with kung machines of all types. The only requirement is that the temperature of these parts or cavities is preferably a sufficient mixture of 35% hydrogen peroxide and 65% low to allow condensation.
Water used although the use of others

1 sheet of drawings

Claims (8)

Patent claims: 1. Method for sterilizing objects with the aid of a liquid, in particular hydrogen peroxide containing sterilizing agent, in which the liquid sterilizing agent with Druck'uft mixed and applied to the surface of the object to be sterilized to produce a coating of the liquid sterilizing agent is blown onto the surface and then - after sterilizing - from there is removed again, and with the air heated to the surface provided with the coating is blown, characterized in that the compressed air prior to mixing with the Sterilizer wildly dried that the liquid sterilant with the compressed air is mixed such that the liquid droplets have a size between 5 to 15 μΐη, and that the droplets are evaporated by means of hot air in such a way that the dew point of the sterilization f medium-saturated air is higher than the temperature of the compartments to be sterilized. 2. The method according to claim 1, characterized in that the sterilizing agent is mixed with dried air at a temperature of 90 to 120 ⁰ C and an absolute degree of humidity of 0.1 to 0.2 kg of steam or moisture per 1 kg of dry air. 3. The method according to any one of the preceding claims, characterized in that a steam-air mixture of about 100 ⁰ C is blown onto the surface to be sterilized. 4. The method according to any one of the preceding claims, characterized in that the Steam-air mixture is adjusted so that it has a dew point of about 60 ° C. 5. Apparatus for performing the method according to any one of the preceding claims in one Machine for the production of sterile packaging, with a compressor for generating compressed air, with a mixer for mixing the compressed air with liquid, in particular containing hydrogen peroxide Sterilizing agent and with a blowing device for inflating the mixture towards the Sterilizing surface, characterized in that a drying system (11, 12, 13) for drying the air and a heating element (17) for generating the hot air are provided and that the mixer tap (15,21) has an ultrasonic nozzle (19) serving to atomize the sterilizing agent. 6. Apparatus according to claim 5, characterized in that the drying system (11,12,13) one Having an air compressor (11), a cooler (12) and a water separator (13). 7. Apparatus according to claim 5 or 6, characterized in that the ultrasonic nozzle (19) with Compressed air is operable. 8. Arrangement according to claim 7, characterized in that the ultrasonic nozzle with compressed air is operated.