EP1152946B1 - Aseptically working packaging machines and method for pre-sterilizing them - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the invention.

The invention relates to aseptically operating packaging machines and a method for their pre-sterilization. Under Packaging machines are special in the present case to understand two ways, i.e., one in which a packaging material web made of a suitable thermoplastic film continuously conveyed through the machine in time, preheated, thermoformed, filled and with a cover film is closed, and the other so-called Tubular bag machines, in which the packaging material web also formed into a tube in the cycle, longitudinally sealed, the Hose closed at the bottom, then filled and closed at the top is and separated from the re-fed hose becomes.

2. Description of the prior art

The packaging of foodstuffs and luxury foods in packaging made from packaging material webs must be sterile, that is to say largely sterile. For this purpose, aseptically operating packaging machines of the type mentioned are available, which have sterile rooms in which the processing or treatment elements for the packaging material web are also located. With regard to the processing elements, thermoforming packaging machines are preheating plates, the deep-drawing tools and the filling and closing elements for the packaging material web running through in cycles, and with tubular bag packaging machines, these are the entire bag-form and filling station with its heatable longitudinal sealing tools and all packaging material guide elements upstream of this station. The sterile rooms of such machines are continuously supplied with sterile air during operation with a slight overpressure in order to maintain the sterile atmosphere during operation free of recontamination, certain areas of the sterile rooms ensuring that the sterile air can flow out of the sterile room again. After such machines have been shut down, be it for reasons of an end of work shift or for whatever reason, it is necessary to sterilize the sterile rooms and the above-mentioned processing elements before starting up again.
According to DE-A-24 35 037 C2, for example, a method for pre-sterilizing the surfaces of objects is known, in which the surfaces are first treated with flowing steam before the supply of hydrogen peroxide (so-called peroxide) as a sterilizing agent in order to treat all those to be treated Really heat surfaces. Only after such heating is the peroxide mixed into the steam, which additionally increases its temperature. After this pre-sterilization, the subsequently added peroxide is then flushed away by unheated sterile air. Since the desired heating of the surfaces is inevitably also associated with their initially sterilizing agent-free condensate wetting, it remains to be seen to what extent the steam-sterilizing agent mixture flowing in in the second stage can then become fully effective. In addition, since such sterile rooms and the processing tools located therein are not free of gussets and gaps, it does not fail during pre-steaming that such gusset rooms and gaps can no longer be reached by the peroxide mixed with the steam afterwards, because these are quasi already with pure steam condensate, ie blocked with water. Apart from this, this method does not ensure, precisely because the sterilization mixture meets condensate that has already precipitated, that the actual sterile agent reaches the germs shielded by condensate drops with the required concentration. A further disadvantage is that the surfaces to be sterilized are heated by the steam heating and the subsequent further steaming with the addition of sterilizing agent in such a way that condensation of the steam / sterilizing agent mixture is no longer reliably guaranteed on all surfaces. The dilemma to be noted here is that the chemical reactivity of the condensing, i.e. liquid, sterilizing agent increases on the one hand, but on the other hand its reactivity with respect to the killing of microorganisms and spores decreases significantly as soon as the sterilizing agent is no longer in liquid form, but instead changes into the gaseous state (evaporation).
DE-A-197 26 222 A1 also deals with the question of pre-sterilization, specifically in connection with a device specially designed for this purpose, equipped with a so-called reversing fan, in order to gas the sterile rooms with their tools therein in two different directions -respectively. to be able to flow through sterile vapor. Apart from the reversing blower required for this, this device requires a disproportionately large amount of line and a considerable number of reversible valves with a corresponding control and monitoring effort for the valves. In addition, the sterilizing agent is introduced between two filters in this device, which is associated with the risk of clogging of the fine filter downstream of the blower. It must also be left open here how much sterilizing agent is retained by the filter or is already chemically converted in the filter material, and thus does not reach the tunnel area that is to be pre-sterilized during the production phase or is delayed at all.
Pre-sterilization of a sterile tunnel is also provided in a device according to US Pat. No. 3,820,300, a liquid sterilizing agent being injected before the actual packaging processing of the supplied sterile air. After the pre-sterilization is complete, the sterilization agent injection is simply switched off. The supply of the mixture of sterile air and sterilizing agent and also the subsequent sole supply of sterile air take place similarly to DE-A-197 26 222 via a complex and individually difficult to control large number of individual nozzles distributed over the entire sterile space, which are connected to so-called distributors. A detection of gusset spaces and gaps, where, as mentioned above, usually or even in particular accumulations of germs are to be expected, cannot be achieved here, since the sterile air as carrier of the injected sterilizing agent has no reason to have no connection with the atmosphere to penetrate standing gussets and crevices, quite apart from the fact that a gaseous sterilizing agent, as it is a mixture of sterile air and sterilizing agent, as mentioned, has a lower sterilizing effect than a condensing, ie locally liquid sterilizing agent.
According to DE-A-37 28 595, a method using hydrogen peroxide is also known, but this is the special type of preparation of a hydrogen peroxide-air mixture, specifically for the sterilization of containers into which the gas mixture generated by a Venturi nozzle is blown becomes.

SUMMARY OF THE INVENTION

The invention is accordingly based on the object, the necessary Not only perform pre-sterilization satisfactorily, but also the equipment expenditure to a minimum hold and connected with the stipulation that for the normal Packaging company requires sterile air supply anyway with as controllable funding for one right from the start Steam-sterilizing agent mixture supplied in a predeterminable mixing ratio to use and thereby ensure that this total mixture in the room to be sterilized and on the processing tools in it temperature conditions finds the one hand the unimpeded condensation of the steam sterilizing agent mixture on surfaces as well guaranteed in crevices and crevices and on the other hand also by means of defined temperature control optimally ensures chemical reactivity of the sterilizing agent.

a) Die etwa noch heißen, im Sterilraum befindlichen Behandlungselemente werden vor Beginn der Vorsterilisation auf eine Temperatur unter 120°C gebracht;

b) die Mischung von Wasserdampf als Trägermedium und Sterilisationsmittel wird mittels einer Düse bewirkt, der beide Komponenten zugeführt werden;

c) das wasserdampf-Sterilisationsmittelgemisch wird an einer einzigen Stelle stromab unmittelbar hinter dem Sterilfilter in gleicher Richtung wie die zuströmende, als Fördermedium dienende Sterilluft in Richtungsterilraum eingedüst;

d) die Dampfzufuhr zur Düse erfolgt durch ein Druckminderventil und eine anschließende Dampfmengenregelung und die Sterilisationsmittelzufuhr zur Düse erfolgt aus einem unter konstantem Druck gehaltenen Sterilisationsmittelvorrat und

e) während der Anlaufphase der Vorsterilisation wird die Sterilluftzufuhr zwecks partieller Rückstromerzeugung des ausgedüsten Wasserdampf-Sterilisationsmittelgemisches stromauf zum Sterilluftfilter hin kurzzeitig unterbrochen.

Based on the previous practice, according to which a sterilizing agent, such as hydrogen peroxide or the like, is sprayed into the sterile room before the packaging machine in question is put into operation and, after this pre-sterilization, sterile air is permanently supplied to the sterile room during the operating period or packaging processing and at the same time again from it is accomplished, this object is achieved with respect to the method for the pre-sterilization according to the invention by the following method steps:

a) The still hot treatment elements in the sterile room are brought to a temperature below 120 ° C before the start of pre-sterilization;

b) the mixing of water vapor as carrier medium and sterilizing agent is effected by means of a nozzle to which both components are supplied;

c) the steam-sterilizing agent mixture is injected in a single point downstream immediately behind the sterile filter in the same direction as the incoming sterile air serving as the conveying medium in the direction of the sterile space;

d) the steam is fed to the nozzle by means of a pressure reducing valve and a subsequent steam quantity control, and the sterilizing agent is fed to the nozzle from a sterilizing agent supply kept at constant pressure and

e) during the start-up phase of the pre-sterilization, the supply of sterile air is briefly interrupted upstream of the sterile air filter for the purpose of generating partial backflow of the steam-sterilizing agent mixture that has been emitted.

The aseptic packaging machine still consists of a processing line equipped with packaging material treatment elements in a partially open to the atmosphere sterile room, which is provided with elements for supplying sterile agent and a connection for a sterile air generator equipped with blower, heating and sterile filter. According to the invention, such a packaging machine for pre-sterilization is configured as follows:
Downstream immediately behind the sterile air filter, a mixing nozzle connected to a steam and a sterilizing agent supply line is arranged in a sterile air channel opening into the sterile room, which is arranged pointing in the direction of the confluence of the sterile air channel in the sterile room, and in the sterilizing agent supply line is an upstream pressure reducing valve under constant pressure held sterilizing agent supply container and in the steam supply line a pressure reducing valve with downstream steam quantity regulator is provided.

The invention is therefore not limited to itself simple requirement, a large number of injection or injection points, as in the machines according to DE-A-197 26 222 and to reduce the US-A-3,820,300 to one because with that alone would be a satisfactory pre-sterilization result for the whole Not reachable sterile room, but it is also the above additional procedural and figurative Characteristics required because, on the one hand, there is a special Placement (utilizing the sterile air flow) and a directional orientation the mixing nozzle have proven necessary and on the other hand satisfactory germ killing ensuring the mixing ratio of steam and sterilizing agent Must be taken into account. Additionally, that immediately downstream by the arrangement of the mixing nozzle behind the sterile air filter this is the simplest and most targeted controllable way is included in the pre-sterilization, This is because the sterile air blower is easy for one is switched off for a short period of time. Besides, with that Characteristic of lowering the temperature of the treatment elements therefor ensured that the sterilized mixture subsequently injected everywhere, i.e. unhindered even in gussets and crevices of any moisture that is already present can. This is preferably and advantageously carried out Temperature reduction to a temperature below the condensation temperature of the steam sterilant mixture.

BRIEF DESCRIPTION OF THE DRAWINGS

The method according to the invention and pre-sterilizing in this way, aseptic packaging machines including Advantageous further developments are as follows based on the graphic representation of exemplary embodiments explained in more detail.

Fig.1

in Seitenansicht und im Schnitt eine erfindungsgemäß ausgebildete Verpackungsmaschine zum Formen, Füllen und Schließen von Behältnissen in Form von Bechern;

Fig.2

im Schnitt die Düse für die Vermischung von Dampf und Sterilisationsmittel;

Fig.3

einen Querschnitt durch den Sterilraum der Verpackungsmaschine gemäß Fig.1 und

Fig.4

in Seitenansicht und im Schnitt eine erfindungsgemäß ausgebildete Verpackungsmaschine zur Herstellung von Schlauchbeuteln.

It shows schematically

Fig.1

in side view and in section an inventive packaging machine for forming, filling and closing containers in the form of cups;

Fig.2

on average the nozzle for mixing steam and sterilizing agent;

Figure 3

a cross section through the sterile room of the packaging machine according to Fig.1 and

Figure 4

in side view and in section an inventive packaging machine for the production of tubular bags.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

In Fig.1 is an aseptic thermoforming packaging machine shown for the production and filling of cups, whose processing line VS for the packaging material web PB from a so-called bordering the sterile room 1 to the outside Sterile tunnel 18 covered with a sterile air supply channel 2 and is the stations shown only schematically 100, 101, 102, 103 for film preheating, molding, filling and Closing the cup-like containers B contains. Bezgl. Such a machine is referred to EP-A-0 727 357.

In order to satisfy the method according to the invention for pre-sterilization of the sterile room 1, namely to inject the sterilizing agent mixed with water vapor as the carrier medium at a single point downstream behind the sterile air filter 6 from the sterile air supply area in the direction of the sterile room 1 and thereby the steam supply through a pressure reducing valve 9 for setting a constant steam pressure to effect with subsequent steam quantity control and to supply the sterilizing agent, usually 35% in aqueous solution, to the mixing point under constant pressure, is essential for the machine that downstream immediately after the sterile air filter 6 in the sterile air channel 2 opening into the sterile room 1, one with a steam and a mixing nozzle 3 connected to a sterile agent supply line 8, 11 is arranged, which is arranged pointing towards the mouth 2 'of the sterile air channel 2 into the sterile room 1. In the sterile medium supply line 11 there is a sterile medium supply container 12 which is kept under constant pressure with an upstream pressure reducing valve 13 and in the steam supply line 8 there is a pressure reducing valve 9 with a downstream steam quantity regulator 10.
3 shows a cross section through a so-called half-tunnel 18 which delimits the sterile room 1. 3 also illustrates the partial openness of the sterile room 1 to the atmosphere, namely at the lower edges 18 'of the sterile tunnel 18. This partial openness to the atmosphere enables the sterile air flowing under slightly overpressure in the sterile room 1 to flow continuously during normal packaging operation, as illustrated by arrows P, but also of the steam sterilizing agent mixture during the pre-sterilization that is of interest here.

As for the mixing nozzle 3, this is with reference on Figure 2 in the form of a double nozzle 3 ', the so-called nozzle set 3 "for sterile introduction, that for example with a concentration of 35% in aqueous solution as Hydrogen peroxide supplied and in the from line 3 '' ' sprayed out as a flow hose and thereby being intensely mixed with the steam that comes together with the sterile air the sterilant throughout Sterile room 1 carries and distributed there, the Steam with the sterilizing agent also in all corners and Gussets on the walls of the sterile room 1 and the treatment elements precipitates or condenses.

The sterile air supply is activated during the start-up phase of the pre-sterilization for the purpose of partial reverse current generation of the Sterilizer mixture up to the upstream Sterile filter 6 out briefly defined to the sterile air filter is also easy with the pre-sterilization 6 to be recorded. Under "defined for a short time" are understood to mean, for example, 15 to 30 seconds for one Total pre-sterilization time of, for example, approx. 3 to 5 minutes. For this purpose, the device is designed such that downstream in a short distance behind the mixing nozzle 3 a flow resistance 15, as shown on a canal kink itself there arranged conically narrowing sterile air supply channel 2 is. The drive 4 'of the blower 4 in a pre-filter 6' and an air heater 5 having sterile air generator 7 is for such a brief interruption of the sterile air supply an adjustable timer 16 provided.

At least during the aforementioned start-up phase of pre-sterilization is also the sterile filter 6 on the upstream side with sterilizing agent sprayed for what upstream of the sterile filter 6 a sterilizing agent nozzle 17 is arranged, with the sterilant dispenser 12 as shown in Fig. 1 indicated by dash-dotted lines, connected to a line 17 ' is.

In order to avoid heat accumulation or the formation of a heat bubble in the area of packaging material preheating elements 19 in the machine according to FIG. 1, which would stand in the way of an obstacle to an inflow of the sterilizing agent / steam mixture into the inlet-side area 1 'of the sterile room 1, the Temperature for the pre-sterilization advantageously kept below 120 ° C, ie at a temperature level of preferably 40-80 ° C. If the pre-sterilization should be carried out after a brief interruption of the machine's operation, after which the preheating elements 19 are still relatively hot, the pre-sterilization is only initiated when these elements have cooled down accordingly. This process can be monitored and controlled by the machine controller via temperature sensors which are already present in this area in such machines.
This also applies to the packaging machine shown in FIG. 4, which is a tubular bag machine. The heatable elements, which have to cool here for the pre-sterilization, ie, have to be tempered, are the longitudinal sealing jaws 20, with which the packaging material tube 22 formed on the molded tube 21 is sealed longitudinally.
Since tubular bag machines of this type are sufficiently known with regard to their function, there is no need to describe them in detail. Otherwise, the same reference numerals are used for corresponding elements of such a tubular bag machine as in the deep-drawing packaging machine described in accordance with FIG.

The temperature control mentioned above can, like all others Control and regulation requirements Part of an overall control (not particularly shown) of the packaging machine in question be no matter whether it is a machine after Fig.1 or Fig.4 is.

The procedure for pre-sterilization is also in both Cases the same, summarized in a preferred embodiment is carried out as follows:

The still hot treatment elements located in the sterile room are carried out before the start of pre-sterilization Allow to cool to a temperature below 120 ° C, i.e. to below the dew point temperature of the steam sterilizing agent mixture or preferably to 40-80 ° C. If the machine the heater has cooled down due to a long period of inactivity the preheating elements 100 or the longitudinal sealing jaws 20 are switched on until they have reached this temperature.

The mixing of water vapor and sterilizing agent (hydrogen peroxide) takes place directly in the mixing nozzle 3, to which both components are fed, and the water vapor-sterilizing agent mixture is passed through the mixing nozzle 3 at a single point in the sterile air supply channel 2 downstream immediately behind the sterile filter 6 in the same direction as that previously switched on and incoming sterile air injected in the direction of sterile room 1. To ensure that steam and sterile are mixed well, the sterilizing agent is injected centrally into the water vapor, which is provided in the form of a tube. In order to further intensify the mixing, the total flow of sterile air, steam and sterilizing agent can be accelerated by conically narrowing the channel 2 leading to the sterile room 1, which leads to a higher turbulence of the flow.
The steam is supplied to the nozzle by means of a pressure reducing valve and a subsequent steam quantity control, and the sterilizing agent is supplied to the nozzle from a sterilizing agent supply or the supply container 12 which is kept under constant pressure and contains the amount of sterile agent required for the pre-sterilization. This pressure and quantity control of steam and sterilizing agents is important in order to meet the requirements and regulations for perfect pre-sterilization.

During the start-up phase of the pre-sterilization, the supply of sterile air is briefly interrupted for about 15 to 30 seconds in order to allow the steam-sterilizing agent mixture to flow back to a certain degree against the sterile-air filter 6 and also to expose it to the sterilizing agent.
Furthermore, at least during the start-up phase of the pre-sterilization, the sterile filter 6 is also sprayed with sterilizing agent on the air inflow side.

Since it can be assumed, regardless of a longer downtime due to the pre-sterilization to be carried out or just a short break is that that on the walls of the sterile room 1 or Treatment elements usually always have some moisture which, as mentioned above, is an obstacle to the desired Represents condensation of the steam-sterile mixture, are advantageous before the actual pre-sterilization begins the sterile room and the treatment elements inside by supplying through the sterile filter supplied sterile air dried, the sterile air to Drying at a temperature on the order of 40 to 80 ° C is supplied, for which the sterile air generator 7 with a is equipped accordingly adjustable heater 5.

Together with the pre-drying and the cooling or heating period (Tempering) the treatment elements takes the whole Pre-sterilization takes a relatively short time of only about 12 up to 20 minutes depending on the machine type and size in Claim, then maintaining the sterile air supply but switched off steam and sterilizing agent supply the sterile room 1 is blown out, so that it also dries and then the packaging machine is set in the conventional way becomes.

Claims (12)

1. An aseptic packaging machine consisting of a processing zone (VS) equipped with packaging material sheeting handling elements in a sterile space (1) that is partially open to the atmosphere and is equipped with elements for supplying a sterilization medium and a connection (2) for a sterile air generator (7) equipped with a fan (4), heating (5) and sterile air filter (6),
   characterized in that a mixing nozzle (3) which is connected to a steam line and a sterilizing agent line (8, 9) is situated downstream directly after the sterile air filter (6) in a sterile air channel (2) which opens into the sterile space (1), this mixing nozzle being situated so that it points in the direction of the mouth (2') of the sterile air channel (2) into the sterile space (1); and a sterilizing agent apportioning container (12) which is kept under a constant pressure with an upstream pressure-reducing valve is situated in the sterilizing agent supply line (11) to the nozzle (3), and a pressure-reducing valve with a downstream steam flow regulator (10) is situated in the steam supply line (8).
2. The machine according to Claim 1,
   characterized in that the mixing nozzle (3) is designed in the form of a double nozzle with a central nozzle assembly (3'), and the sterilizing agent line (11) leading from the apportioning container (12) is connected to it the nozzle assembly.
3. The machine according to Claim 1 or 2,
   characterized in that a flow resistance (15) such as a kink in the connection, a ring orifice, a constriction in the channel or the like is situated downstream in the sterilization air channel (2) at a distance behind the mixing nozzle (3).
4. The machine according to one of Claims 1 through 3,
   characterized in that the drive for the fan (4) is provided with an adjustable timer (16).
5. The machine according to any one of Claims 1 through 4,
   characterized in that a sterilizing agent nozzle (17) is situated upstream from the sterile filter (6) on the incoming flow end and is connected to the sterilizing agent apportioning container (12) by a line (17').
6. A method of presterilizing sterile spaces of aseptic packaging machines according to Claims 1 through 5, whereby before starting operation of the respective packaging machine, a sterilizing agent mixed with steam as the vehicle, in particular hydrogen peroxide dissolved in water, is sprayed into the sterile space (1), which is partially open to the atmosphere, is kept under a slight excess pressure and contains the packaging material sheeting handling elements, said spraying being performed when the sheeting of the packaging material (PB) has been introduced into the space and sterile-filtered sterile air is supplied as the delivery medium during the preliminary sterilization,
   characterized by the following process steps:

   a) the treatment elements which are in the sterile space (1) and are still hot are brought to a temperature of less than 120 °C before the start of preliminary sterilization;

   b) the mixture of steam and sterilizing agent is created by using of a nozzle (3) to which the two components are supplied;

   c) the mixture of steam and sterilizing agent is sprayed in the direction of the sterile space (1) in the same direction as the incoming sterile air at a single location downstream and directly behind the sterile filter (6);

   d) the steam is supplied to the nozzle (3) through a pressure-reducing valve and a subsequent steam flow control device, and the sterilizing agent is supplied to the nozzle (3) from a sterilizing agent supply container that is kept under a constant pressure, and

   e) during the startup phase of presterilization, the sterile air supply is interrupted briefly for the purpose of creating a partial return flow of the steam-sterilizing agent mixture sprayed out upstream from the sterile air filter (6).
7. The method according to Claim 6,
   characterized in that the sterilizing agent is sprayed centrally into the steam which is sprayed out in the form of a tube.
8. The method according to Claim 6 or 7,
   characterized in that at least during the startup phase of presterilization the sterile filter (6) is sprayed with sterilizing agent on the incoming air side.
9. The method according to one of Claims 6 through 8,
   characterized in that the mixture of steam, sterilizing agent and sterile air is passed through a flow constriction (15) before entering the sterile space (1).
10. The method according to one of Claims 6 through 9,
    characterized in that the sterile space (1) including the packaging material sheeting handling elements situated therein is adjusted to a temperature below the condensation temperature of the steam-sterilizing agent mixture, preferably 40 °C to 80 °C, for the presterilization.
11. The method according to one of Claims 6 through 10,
    characterized in that before the start of the actual presterilization the sterile space (1) and the treatment elements therein are dried and thermally regulated by supplying sterile air which is fed in through the sterile filter (6).
12. The method according to Claim 11,
    characterized in that the sterile air is supplied at a temperature on the order of magnitude of 40 °C to 80 °C for drying.

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