EP1152946A1

EP1152946A1 - Aseptically working packaging machines and method for pre-sterilizing them

Info

Publication number: EP1152946A1
Application number: EP00993397A
Authority: EP
Inventors: Gunter Kurth
Original assignee: Hassia Verpackungsmaschinen GmbH
Current assignee: Hassia Verpackungsmaschinen GmbH
Priority date: 1999-12-14
Filing date: 2000-12-11
Publication date: 2001-11-14
Anticipated expiration: 2020-12-11
Also published as: US6622457B2; ES2218282T3; US20020134051A1; EP1152946B1; DE50006955D1; DE19960155A1; WO2001044053A1

Abstract

The invention relates to aseptically working packaging machines and to a method for pre-sterilizing them. The aim of the invention is to simultaneously introduce under pressure the steam and the sterilizing agent at a single site into a sterile air feed channel (2) that leads to the sterile chamber (1) of the packaging machine. To this end, a mixing nozzle (3) is located in the air feed channel directly downstream of a sterile air filter (6). For the purpose of pre-sterilization, the treating elements disposed in the sterile chamber that are possibly still hot are brought to a temperature of less than 120 °C before the actual pre-sterilization begins. The steam and the sterilizing agent are mixed by means of a mixing nozzle (3) to which both components are fed. The steam is fed to the nozzle via a pressure-reducing valve (19) and an adjoining device (10) that regulates the steam quantity. The sterilizing agent is fed to the nozzle (3) from a sterilizing agent reservoir (12) that is maintained at a constant pressure. During the initial phase of the pre-sterilization, the supply of sterile air to the sterile air filter is shortly interrupted in order to generate a partial reflux of the atomized steam/sterilizing agent mixture upstream towards the sterile air filter (6).

Description

Aseptic packaging machines and processes for their pre-sterilization

BACKGROUND OF THE INVENTION

1. Field of the invention.

The invention relates to aseptically operating packaging machines and a method for their pre-sterilization. In the present case, packaging machines are to be understood in particular as two types, that is to say those in which a packaging material web made of suitable thermoplastic or plastic composite film is conveyed through the machine in time, preheated, formed into containers by the deep-drawing process, filled and filled with one Cover film is closed, and on the other hand so-called tubular bag machines, in which the packaging material web is also formed into a tube in the cycle, longitudinally sealed, the tube is closed at the bottom by cross-sealing, then filled and, after removal, is also closed by cross-sealing at the top and separated from the re-conveyed tube becomes.

2. Description of the prior art

The packaging of foodstuffs and luxury foods in packaging formed from packaging material webs must be sterile, ie practically germ-free. For this purpose, aseptically operating packaging machines of the type mentioned are available which have sterile rooms in which the processing and treatment elements for the packaging material web are also located. Thermoforming packaging machines are related to the processing elements around preheating plates, the deep-drawing tools and the filling and closing elements for the Packing material web running in time and in the case of tubular bag packaging machines, these are the entire bag forming 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 without 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 the end of a 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 Heating up surfaces. Only after such heating is the peroxide mixed into the steam, which additionally increases its temperature. After this pre-sterilization, the subsequently added Peroxγ_d is then flushed away by non-heated 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 sterilizing agent / steam 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 is not inevitable during pre-steaming that such gusset rooms and gaps no longer contain any peroxide subsequently mixed with the steam can be achieved because these are already blocked with pure steam condensate, ie 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 damping 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 AI 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 to be pre-sterilized during the production phase, or only at a delay.

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 sterilant 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 crevices, 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 not in contact 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 sterilant.

SUMMARY OF THE INVENTION

The invention is therefore based on the object not only to carry out the necessary pre-sterilization satisfactorily, but also to keep the outlay on equipment to a minimum, namely in conjunction with the requirement that the sterile air supply which is anyway required for normal packaging operation drove to use as a controllable funding for a steam-sterilizing agent mixture supplied from the start in a predeterminable mixing ratio and thereby to ensure that this total mixture finds temperature conditions in the room to be sterilized and on the processing tools located therein, which on the one hand the unhindered condensation of the steam-sterilizing agent mixture Surfaces as well as in crevices and crevices, and on the other hand also optimally ensures the temperature-dependent chemical reactivity of the sterilizing agent through defined temperature control.

Based on the practice previously practiced, 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 this is achieved, this object is achieved with respect to the method for the pre-sterilization according to the invention by the following process steps: a) the still hot treatment elements located in the sterile room are brought to a temperature below 120 ° C. before the start of the 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 room; 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 in order to partially generate the reverse flow of the steam-sterilizing agent mixture that has been ejected upstream of the sterile air filter.

The aseptically operating 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, heater and sterile filter. According to the invention, such a packaging machine for pre-sterilization is configured as follows:

Immediately downstream of 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 opening of the sterile air channel into the sterile room, and in the sterilizing agent supply line there is a pressure reducing valve connected upstream Sterilizing agent supply container kept at a constant pressure and a pressure reducing valve with a downstream steam quantity regulator in the steam supply line.

The invention is therefore not limited to the simple requirement that a large number of injection or injection points, as in the machines according to DE-A-197 26 222 and US-A-3,820,300, be reduced to one, because this alone would not achieve a satisfactory pre-sterilization result for the entire sterile room, but it also requires the additional process and objective features mentioned above, since on the one hand there is a special one Placement (utilization of the sterile air flow) and a directional orientation of the mixing nozzle have proven necessary and, on the other hand, the mixing ratio of steam and sterilizing agent, which ensures satisfactory germ killing, must be taken into account. In addition, the arrangement of the mixing nozzle directly downstream of the sterile air filter means that it is included in the pre-sterilization in the simplest and specifically controllable manner, namely by simply switching off the sterile air blower for a short period of time. In addition, the feature of lowering the temperature of the treatment elements ensures that the subsequently sterilized mixture of sterilizing agents can condense anywhere, ie, even in gussets and gaps, unhindered by moisture that may already be present. The temperature is preferably and advantageously reduced to a temperature below the condensation temperature of the steam / sterilizing agent mixture.

BRIEF DESCRIPTION OF THE DRAWINGS

The method according to the invention and in this way pre-sterilizing, aseptically operating packaging machines including advantageous further developments are explained in more detail below with reference to the drawing of exemplary embodiments.

It shows schematically

Fig.l in side view and in section, a packaging machine designed according to the invention for forming, filling and closing containers in the form of cups;

2 shows the nozzle for the mixing of steam and sterilizing agent in section; 3 shows a cross section through the sterile room of the packaging machine according to Fig.l and

4 in side view and in section, a packaging machine designed according to the invention for the production of tubular bags.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

1 shows an aseptically working thermoforming packaging machine for the production and filling of cups, the processing section VS of which for the packaging material web PB is covered by a so-called sterile tunnel 18 which borders the sterile space 1 with a sterile supply channel 2 and which only contains schematically illustrated stations 100, 101, 102, 103 for film preheating, shaping, filling and closing the cup-like containers B. Reg. such a machine is referred to EP-A-0 727 357.

In order to satisfy the method according to the invention for the 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 volume 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 duct 2 opening into the sterile space 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 in the direction of the opening 2 'of the sterile air channel 2 into the sterile room 1. In the sterile supply line 11 is a sterile medium supply container 12, which is kept under constant pressure with an upstream pressure reducing valve 13, and a pressure reducing valve 9 with a downstream steam quantity regulator 10 in the steam feed line 8.

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 far as the mixing nozzle 3 is concerned, this is designed with reference to FIG. 2 in the form of a double nozzle 3 ', the so-called nozzle assembly 3 "serving for the introduction of sterile, which, for example, is supplied as a hydrogen peroxide with a concentration of 35% in aqueous solution and sprayed into the steam jet emerging from line 3 '' 'as a flow hose and thereby intensively mixed with the steam, which carries the sterilizing agent together with the sterile air into the entire sterile room 1 and distributes it there, the steam also spreading with the sterilizing agent in all of them Nooks and crannies on the walls of the sterile room 1 and the treatment elements precipitate or condense.

During the start-up phase of the pre-sterilization, the sterile air supply is briefly interrupted in a defined manner for the purpose of partial backflow generation of the sterilizing agent mixture as far as the upstream sterile filter 6, in order to also facilitate the sterilization with the pre-sterilization. to detect air filter 6. "Defined for a short time" means 15 to 30 seconds, for example, with a total pre-sterilization time of, for example, about 3 to 5 minutes. For this purpose, the device is designed in such a way that a flow resistance 15, such as an illustrated duct kink, is arranged downstream of the mixing nozzle 3 at a short distance on the sterile air supply duct 2, which has narrowed until then. The drive 4 'of the fan 4 in a pre-filter 6' and an air heater 5 having sterile air generator 7 is provided with an adjustable timer 16 for such a brief interruption of the sterile air supply.

At least during the aforementioned start-up phase of the pre-sterilization, the sterile filter 6 is also sprayed on the inflow side with sterilizing agent, for which purpose a sterilizing agent nozzle 17 is arranged upstream of the sterile filter 6, which is connected to a line 17 ′ with the sterilizing agent supply container 12, as indicated by dash-dotted lines in FIG. 1 ,

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 as an obstacle to an inflow of the sterilizing agent / steam mixture into the inlet-side area 1 'of the sterile room 1 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 carried out in such machines using temperatures door sensors can be monitored and controlled by the machine control system.

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 pre-sterilization, i.e. have to be tempered, are the longitudinal sealing jaws 20, with which the packaging material tube 22 formed on the molded tube 21 is longitudinally sealed. Since such tubular bag machines with respect to their function is well known, 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 above in accordance with FIG.

The aforementioned temperature control, like all other control and regulating requirements, can be part of an overall control (not particularly shown) of the packaging machine in question, regardless of whether it is a machine according to Fig. 1 or Fig. 4.

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

The treatment elements, which are still hot and are located in the sterile room, are brought to a temperature below 120 ° C. by cooling before the start of the pre-sterilization, that is, below the dew point temperature of the steam-sterilizing agent mixture or preferably to 40-80 ° C. If the machine has cooled down due to a longer downtime, the heating of the preheating elements 100 or the longitudinal sealing jaws 20 is 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 like the previously switched on and incoming sterile air injected in the direction of sterile room 1. For the purpose of good mixing of steam and sterile agent, the sterilizing agent is injected centrally into the water vapor, which is sprayed out 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 which 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 extent against the sterile air filter 6 and also to expose it to the sterilizing agent.

Furthermore, the sterile filter 6 is also sprayed with sterilizing agent on the air inflow side, at least during the start-up phase of the pre-sterilization. Since it can be assumed, regardless of whether the pre-sterilization to be carried out is preceded by a longer downtime or only a short interruption

is that there is always some moisture on the walls of the sterile room 1 or the treatment elements, which, as mentioned, is an obstacle to the desired condensation of the steam-sterile mixture, are advantageous before the actual pre-sterilization of the sterile room and treatment elements located therein are dried by supplying sterile air supplied through the sterile filter, the sterile air being supplied for drying at a temperature of the order of 40 to 80 ° C., for which purpose the sterile air generator 7 is equipped with a correspondingly controllable heater 5.

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

Claims

Claims:

1. Aseptic packaging machine, consisting of a processing line (VS) equipped with packaging material treatment elements in a partially open to the atmosphere sterile room (1) with elements (3) for the supply of sterilizing agent and a connection (2) for a with blower (4 ), Heating (5) and sterile air filter (6) equipped sterile air generator (7), characterized in that downstream immediately behind the sterile air filter (6) in a sterile air duct (2) opening into the sterile space (1) one with a steam and a sterilizing agent supply line (8, 11) connected to the mixing nozzle (3) is arranged, which is arranged pointing in the direction of the mouth (2 ') of the sterile air channel (2) into the sterile room (1), and that in the sterilizing agent supply line (11) has an upstream pressure reducing valve (13) Sterilizing agent supply container (12) kept under constant pressure and in the steam supply line (8) a pressure reducing valve (9) with nachg switched steam quantity regulator (10) is arranged.

2. Machine according to claim 1, characterized in that the mixing nozzle (3) in the form of a double nozzle with a central nozzle assembly (3 ') and to which the outgoing from the distribution container (12) sterilizing agent line (11) is connected.

3. Machine according to claim 1 or 2, characterized in that downstream at a distance behind the mixing nozzle (3) in the sterile air channel (2), a flow resistance (15), such as connection kink, ring diaphragm, channel constriction or the like. is arranged.

4. Machine according to one of claims 1 to 3, characterized in that the drive of the fan (4) is provided with an adjustable timer element (16).

5. Machine according to one of claims 1 to 4, characterized in that a sterilizing agent nozzle (17) is arranged upstream of the sterile filter (5), which is connected to the sterilizing agent supply container (12) through a line (12 ¹ ) connection.

6. A method for pre-sterilizing sterile rooms of aseptically operating packaging machines according to claims 1 to 5, wherein, before starting up the packaging machine in question, a sterilizing agent mixed with water vapor as a carrier, in particular hydrogen peroxide dissolved in water, in the partially open to atmosphere, kept under a slight positive pressure and the The sterile room containing the packaging material treatment elements is sprayed in when the packaging material web is inserted and sterile-filtered sterile air is supplied as the conveying medium during the pre-sterilization, characterized by the following process steps: a) The treatment elements, which are still hot, in the sterile room are brought to a temperature below 120 ° C. before the pre-sterilization begins ; b) the mixing of water vapor and sterilizing agent is effected by means of a nozzle to which both components are supplied; c) the steam-sterilizing agent mixture is injected at a single point downstream immediately behind the sterile filter in the same direction as the incoming sterile air in the direction of the sterile room; d) 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 kept at a constant pressure, and e) during the start-up phase of the pre-sterilization, the sterile air supply is used for the partial generation of reverse flow of the steam steam / sterilizing agent mixture that is emitted to the sterile air filter briefly interrupted.

7. The method according to claim 6, characterized in that the sterilizing agent is injected centrally into the steam emitted in the form of a tube.

8. The method according to claim 6 or 7, characterized in that at least during the start-up phase of the pre-sterilization, the sterile filter is sprayed on the air inflow side with sterilizing agent.

9. The method according to any one of claims 6 to 8, characterized in that the mixture of water vapor, sterilizing agent and sterile air is passed through a flow restriction before entering the sterile room.

10. The method according to any one of claims 6 to 9, characterized in that the sterile room including the packaging material treatment elements therein for the pre-sterilization is set to a temperature below the condensation temperature of the steam-sterilizing agent mixture, preferably to 40 to 80 ° C.

11. The method according to any one of claims 6 to 10, characterized in that before the actual pre-sterilization of the sterile room and the treatment elements located therein are dried and tempered by supplying sterile air supplied through the sterile filter.

12. The method according to claim 11, characterized in that the sterile air is supplied for drying at a temperature in the order of 40 to 80 ° C.