WO2023117143A2

WO2023117143A2 - Sterilisation of flexible packaging material and of packaging machines

Info

Publication number: WO2023117143A2
Application number: PCT/EP2022/025597
Authority: WO
Inventors: Paul Newman; Mark Blackman
Original assignee: Sterafill Limited
Priority date: 2021-12-24
Filing date: 2022-12-24
Publication date: 2023-06-29
Also published as: GB202119024D0; WO2023117143A3

Abstract

An improved package forming and filling apparatus is described which has three chambers 1,2,3 in series. Packaging foil is fed through the first, where it is exposed to some sterilising radiation, then through the second where it is exposed to ozone generated by corona discharge between electrodes 20 which the foil passes between, and then fed into the third chamber 3 where it is formed into a tube and the tube filled with fluent material and then separated into individual sealed sachets. The third section may be subjected to vigorous sterilisation before a filling operation by passing high ozone concentration air into it. Cooled air may flow in the direction of movement of the foil through the area of the corona discharge and accompany the foil into the third chamber 3 while maintaining the sterilising effects of the ozone generated by the corona discharge.

Description

STERILISATION OF FLEXIBLE PACKAGING MATERIAL AND OF PACKAGING MACHINES

5 FIELD OF THE INVENTION

This invention relates to the sterilisation of flexible packaging materials which are used to form packages of various types and which are to contain products which need to be kept sealed and which are protected from

10 contamination by the package itself. It is important that no contamination is introduced from the packaging material itself, particularly where the product to be packaged is itself sterile, for example foodstuffs or pharmaceuticals, whether in liquid or solid form. It also relates to the sterilisation of packaging machines prior to their use in packaging products under sterile conditions.

15

BACKGROUND OF THE INVENTION

It is well known to package such products which need to be maintained sterile using flexible packaging materials (often simply referred to as “foil”)

20 and where, in the packaging step, the flexible material is formed into a package, for example in the form of a stick, sachet or bag containing the product, or the foil can be formed into a cover around an already packaged product.

The formation of the foil into a package and filling of the package with product and its subsequent sealing into sections, each of which corresponds to a single package, and then separating the packages from one another can be carried out as a continuous process, enabling large numbers of packages to be produced automatically.

30

While it is satisfactory for some applications to form the filled packages under ambient conditions, where the package is to contain sterile product,

Received at EPO via Web-Form on Dec 24, 2022 particularly foodstuff such as a dairy product or sauce, or a pharmaceutical material, it is imperative that the process is carried out under sterile conditions, and that the relevant parts of foil-fed apparatus or machinery are also sterile and that while they are in use, they remain in a sterile

5 environment.

PRIOR ART

EP3549878 AND WO22/167400 disclose packaging machines which render

10 a continuously fed strip of foil sterile, form it into a tube, fill the tube and then seal sections of the tube and separate them from one another to form a series of separate product-containing sachets or the like. Both specifications disclose the need to process the foil under aseptic conditions, in order to ensure that the finished sachets have a long shelf life. More complex sachet

15 filling machines are disclosed in US9856045 and JP5047676 particularly for filling pre-formed bags or sachets, and both disclose methods of sterilising the sachet foil feed and maintaining the parts of the apparatus designed to fill the sachet in an aseptic environment.

20 WO201 7/220688 describes a filling head arrangement where at least the side of the foil which is going to be in contact with the filling is exposed to plasma in mist or aerosol form, i.e. exposed to a concentration of ozone sufficient to render the interior of the formed tube sterile.

GENERAL DESCRIPTION OF THE INVENTION

According to a first feature of the present invention, there is provided apparatus for forming a continuous series of filled packages from a strip of packaging film which comprises three chambers in communication with one

30 another and wherein a first chamber comprises means for sterilising the sides of a strip of foil fed through the first chamber, the second chamber comprises means to effect a further sterilisation step, and the third chamber

Received at EPO via Web-Form on Dec 24, 2022 comprises apparatus for forming the strip into a series of packages and filling each package with a desired quantity of sterile product and sealing around each such quantity to form a series of filled packages, and means for discharging the filled packages from the third section, and characterised in

5 that the means to effect a further sterilisation step in the second chamber comprises one or more pairs of spaced plates in the chamber, and means to feed the foil through the space between the plates and means to subject the foil while passing between the plates to an ozone-generating corona discharge, by means for elevating the pressure of the atmosphere in the

10 second chamber so that it flows out into the first and third chambers respectively and by means for feeding cooled filtered air into the second chamber at a rate sufficient to prevent overheating of the foil passing through it.

15

The present invention may be embodied in integrated packaging apparatus for the continuous production of a series of filled packages from a strip of packaging film where each package contains the same amount of content, the apparatus comprising a housing, means to maintain a positive pressure

20 in the interior of the housing, means for feeding a strip of packaging material into the housing, through a sterilisation zone within the housing, and through a package-forming and filling station within the housing, to emerge as a series of filled packages therefrom, wherein the sterilisation zone includes a first section where the strip is exposed to sterilising radiation followed by a second section where the strip is passed into a plasma-generated ozonecontaining atmosphere, and a third section in which the strip is formed into a series of packages with each of the packages being filled with a desired quantity of the sterile product and sealed around that quantity of product prior to its emergence from the housing.

30

In a preferred such embodiment, the interior of the

Received at EPO via Web-Form on Dec 24, 2022 housing is split into several zones, each zone being designed to work in conjunction with the others and the overall construction being designed to achieve the desired degree of dry sterilisation, for example a bacterial spore kill of bacillus atrophaeus, of 10⁵ log reduction. The first sterilisation zone is

5 preferably in the form of a box containing a series of high powered UV-C tubes, for example 135watt tubes emitting UV-C at a wavelength of 254nm. The strip is preferably fed over a series of rollers between the UV-C tubes so as to expose both sides of the strip to the UV-C radiation. The arrangement may be such as to expose the strip for a sufficient period of time to provide

10 preliminary sterilisation, for example between 20 and 30 seconds depending on the speed and throughput of the packaging machine. Chilled air, which is preferably passed through a high efficiency particulate absorbing filter (Hepa filter) of known type in order to clean the air and remove particulates, is preferably blown through the box containing the UV-C tubes, at a controlled

15 level to keep the tubes cool and to ensure a positive air pressure is maintained throughout the housing.

In a second zone of the housing, the strip is preferably passed under a tensioned roller into a plasma generation zone, where it is fed between a pair

20 or series of pairs of plasma electrodes. These produce ozone which provides a highly effective bacterial spore kill. In order not to damage the strip, the ozone-containing atmosphere produced between the electrodes is drawn through the gap between them, and thus accompanies the strip as it travels towards a third zone within the overall housing, the movement of the atmosphere being generated by way of the positive pressure within the housing. Preferably this is arranged so that the ozone-containing atmosphere is drawn down forming tubes designed to form the strip into a tube and extracted from the interior of the tube formed from the strip of foil just before the point of fill, so that the sterilising process continues to operate to sterilise

30 the surface of the strip. The airflow is preferably arranged to move down the foil, through the forming tubes and is then extracted up the inside of the filling tubes and the ozone allowed to degrade back to oxygen.

Received at EPO via Web-Form on Dec 24, 2022 Prior to using the apparatus according to the first feature of the present invention, it is desirable to ensure that the interior of the housing and all the components within it, are satisfactorily sterile, particularly areas that may

5 have been contaminated by human intervention for example between filling operations on different materials where thorough cleaning of the filling head in particular may have taken place. This desirable pre-sterilisation step applies to any sterile filling and packaging machine or apparatus which is used to fill and package sterile product, and in which the core components of

10 the apparatus are surrounded by a housing of some sort.

In accordance with a second feature of the present invention there is provided a method of effecting pre-sterilisation of parts of a packaging machine where those parts are located within a housing, and which

15 comprises flushing the interior of the housing, prior to the commencement of a filling operation, with a cooled atmosphere containing a high ozone content and of high relative humidity, the through-flow rate, concentration of ozone and time for which the flushing is carried out being sufficient to achieve the desired degree of sterilisation.

20

The atmosphere containing a high concentration of ozone may be provided by using a high output industrial ozone generator of known type, preferably one designed to produce an output flow consisting predominantly of oxygen and having an ozone concentration of between 20,000 ppm and 50,000 ppm. Various proprietary ozone generators are available, the preferred types being those which are fed with ambient air, which is then treated to remove the non-oxygen components from the air and the resulting flow of oxygen is then passed through a corona plasma discharge which converts some of the molecular oxygen to ozone.

30

The high ozone concentration atmosphere is then treated in a humidifier arrangement designed to increase the relative humidity (RH) up to 80%+ but

Received at EPO via Web-Form on Dec 24, 2022 at the same time without raising the temperature of the ozone-containing atmosphere, and in particular to keeping it preferably below 18^QC, most preferably below 10^QC. By operating in this way, it is possible to secure, within the housing, a very effective sterilisation, for example to achieve a 10⁵

5 log kill of bacillus atrophaeus.

We have found that it is preferable to provide means for keeping the temperature within the enclosure below ambient and at the same time to maintain the relatively humidity of the air flowing through the enclosure fairly

10 high, preferably at least 80%+. This is of particular value when commencing filling operations because it enables rapid sterilisation of the apparatus inside the enclosure before filling commences.

Apparatus of this nature forms a second feature of the present invention and

15 is defined in the claims appended to this description.

When this approach is applied to packaging apparatus according to the first feature of the present invention, the high ozone concentration high humidity atmosphere is drawn through the forming, sealing and filling area from the

20 end of the plasma electrodes to the bottom of the filling tubes where it is then extracted and the ozone then extracted safely to avoid danger to personnel who may be present and allowed to degrade back to oxygen.

In the apparatus according to the first feature of the present invention, means are provided in customary fashion to feed the packaging film through the apparatus, to form it from a flat strip into a sealed tube, to fill it with the relevant product at a metered rate and, optionally within the enclosure, to seal the filled strip transversely and cut the filled sealed strip transversely into a sequence of sealed sachets.

30

Received at EPO via Web-Form on Dec 24, 2022 The actual filling head arrangements are, particularly when the material to be filled into sachets is for human consumption, preferably of the type described in specification WO2017/220688.

5 The apparatus may include means for adjusting the degree of intensity of the sterilising effects in the first and second sections and the speed at which the strip is fed through the apparatus, so as to enable a very high degree of sterilisation to be achieved while maintaining an adequate continuous throughput.

10

DESCRIPTION OF PREFERRED EMBODIMENT

The invention is described by way of example further with reference to a particular unit for the production of sterile filled packages and a system for

15 effecting pre-sterilisation of packaging equipment, which are illustrated diagrammatically in the accompanying drawings in which:

Figure 1 is a diagrammatic drawing showing the arrangement of a sachet formation and filling machine;

20

Figure 2 is a diagrammatic illustration of apparatus for producing a supply of chilled high humidity high ozone concentration atmosphere for effecting presterilisation; and

Figure 3 is a diagrammatic illustration of apparatus forming one component of the apparatus shown in Figure 2.

Referring first to Figure 1 This shows in very diagrammatic form a sachet forming and filling machine. The majority of the engineering detail is omitted

30 for the sake of clarity, and particular the detailed mechanism for feeding the packaging film through the machine and the means for feeding the material

Received at EPO via Web-Form on Dec 24, 2022 to be encapsulated in the sequence of sachets which the machine makes, as well as the various controls to adjust the desired operation of the machine.

The basic arrangement of the operative portions of the machine is located

5 within a three part enclosure, consisting of a first housing section 1 surrounding UV sterilisation apparatus, a subsequent housing section 2 containing a plasma generating system, and a third housing section 3 containing a filling head.

10 The packaging film/foil is provided on a reel 4, shown on the left in Figure 1 . The strip is unwound from the reel and passes via a roller system of known type and enters the side of the first housing section 1 .

Hepa filtered chilled air is pumped into the housing section 2 by a fan 5

15 upstream of a hepa filter unit 6. The cooling of the air may be effected by standard techniques. No cooler is shown in Figure 1 for the sake of simplicity. Within housing section 2, the chilled air flows over, and in the gap between, a pair of plasma electrodes 20, and out of both sides of the second housing section 2. Part of the chilled air flows through housing section 1 to

20 cool UV-C tubes 13 located in that housing section. Part of the chilled air also passes into housing section 3 and emerges via an outlet pipe 8 at the bottom of housing section 3.

The strip, following its entry into housing section 1 , is threaded around rollers 12 and thus passes between the multiple UV-C tubes 13. The dwell time of the strip in housing section 1 will depend on the speed required of the packaging machine, but may be typically around 30 seconds. The strip then passes out of the housing section 1 under a final tensioning roller 12 and moves into housing section 2 where it passes between plasma electrode

30 plates 20. The housing section 2 may accommodate a pair of such plates each extending across the majority of the housing section itself, or a series of pairs of plates. The electrical drive system for generating the plasma

Received at EPO via Web-Form on Dec 24, 2022 discharge can also be accommodated in housing section 2 if desired, where it may be cooled by the cooled air flowing through it. During operation a plasma discharge is maintained between the plates 20, thus generating ozone in the chilled air flow. Depending on the machine speed the dwell time

5 of the strip between the plates 20 will vary, but a typical dwell time is about 5 seconds.

The strip then comes out of the housing section 2 and into the housing section 3 which contains a known filling and packaging system 30 (not shown

10 in detail but of any conventional design or as described in WO2017/220688 referred to above) by means of which the strip is formed into a package and filled. The filling system may be fed with the product to be filled into a sequence of sachets via a suitable feed system, for example a feed pipe 15 for liquid products. The ozone-containing air flow from housing section 2

15 surrounds the strip and the filling and packaging system 30 and provides a sterilising atmosphere throughout housing section 3. The ozone containing air is drawn out through the outlet pipe 8 at the bottom of housing section 3, and is then fed via carbon filters (not shown) which degrade the ozone to oxygen which is released to the ambient atmosphere. The filled sachet strip

20 formed continuously below system 30 may be transversely welded and cut by a conventional such system denoted 18, whereafter detached filled sachets fall into a catch basket or collection tray (not shown) located below a spring- loaded flap door 20.

Referring now to Figure 2, this shows a system for the production of a high ozone concentration airflow, suitable in particular for the thorough sterilisation of housing section 3. Before a filling and packaging run is started it is necessary to ensure that housing 3 and all of the components within it are thoroughly sterile.

30

As shown diagrammatically in Figure 2, ambient air 60 is sucked to an ozone generating unit consisting of an oxygen generator 61 connected to an ozone

Received at EPO via Web-Form on Dec 24, 2022 generator 62. Such units are available commercially from a variety of manufacturers. The concentration of ozone in the airstream produced by ozone generator 61 is preferably 25,000ppm to 50,000ppm, and can be maintained at the desired level by control of ozone generator 62 in

5 dependence on the ozone concentration sensed by an ozone monitoring unit

63. The relative humidity of this airflow is increased to 80 - 90% by passing the output from the ozone generator 61 to and through an ultrasonic fogger

64. In order to produce good results, i.e. highly effective sterilisation capacity, the temperature of the emergent fog is critical, and this is kept low by keeping

10 the water in the fogger 64 at as near to 4^Q C as possible. This is effected by the use of an ice bath 73 through which water which has been deionised by a deionisation unit 70 and fed into a header tank 71 is pumped by means of a pump 72. This provides a feed of chilled water to the ultrasonic fogger 64. It also feeds chilled water, in the system illustrated, to the ozone generator 62,

15 which reduces the temperature of the outflow from generator 62. The high RH high ozone concentration cold outflow from the fogger 64 is fed via a conduit 65 to a manifold 75 whence it may be directed as desired via a series of feedpipes 76, into the housing section 3 of a unit as shown in Figure 1 during a pre-sterilisation stage before a filling operation is commenced.

20

During the pre-sterilisation stage the outflow from the manifold 75 is fed into housing section 3 via feedpipe 76, an opened valve 31 and an inlet pipe 32, in order to introduce an extra strong highly concentrated ozonised air into housing section 3. During this pre-sterilisation phase the UV-C tubes 13 and the plasma electrodes 20 are not activated. Components of the forming and sealing unit forming part of the system 30 in housing section 3 and the cross cut mechanism 18 for separating individual packages may be switched off or operated at low speed to ensure all moving parts are exposed to the thigh

30 ozone concentration atmosphere and thus do not escape its sterilising effects. The high concentration of ozone in the flow from the system described with reference to Figure 2, may be fed through housing section 3,

Received at EPO via Web-Form on Dec 24, 2022 typically for a period of 20 to 30 minutes, entering housing section 3 via pipe 32 and leaving via a pipe 33 and an opened discharge valve 34, whence it is fed to a suitable absorption system to reduce the ozone emissions to the surrounding environment to an acceptable level or below a regulated

5 emissions level. At this point pipe 8 is closed by a valve 35. After an adequate pre-sterilisation treatment, following which the system shown in Figure 2 can be switched off. An extract fan and vacuum system (not shown) may be attached to pipe 33 to ensure that residual ozone is removed and degraded by being fed into a filter system to remove the ozone. Finally, at the

10 end of the pre-sterilisation period, valve 31 is closed and the housing section 3 is flushed out by turning on the supply of above ambient pressure hepa filtered air until all the high ozone level atmosphere has been removed following which filled package production can be started.

15 Figure 3 shows diagrammatically the construction of the ultrasonic fogger 64 shown in Figure 2. It consists of an upper chamber 80 into one end of which the high ozone concentration feed from ozone generator 62 is fed via duct 81 , and which passes over a water bath, the water level being denoted 83. This level is controlled via a float switch 84 connected to a solenoid valve 85

20 set in an infeed pipe 89. Mounted on the floor of the ultrasonic flogger, between two lower chambers 86, 87, is an array of ultrasonic disc-shaped transducers 88 which are actuated to generate a mist above the water level so that the high ozone concentration atmosphere from chamber 80 passes into duct 65 with a high relative humidity, preferably over 80%. The ultrasonic action warms the water in the fogger, and the warmed water flows out of the fogger via an exit pipe 90 to return to the header tank 71 , as shown in Figure 2.

Tests carried out by Campden Bri on a system as illustrated in Figures 1 to 3

30 have shown that by using this system a bacterial log reduction of 10⁵ on bacillus atrophaeus, which is internationally used for assessing dry sterilisation on production sterilisation systems, can be achieved, both during

Received at EPO via Web-Form on Dec 24, 2022 a continuous filling and packaging process and by using the ozone presterilisation procedure using high RH high ozone concentration atmosphere as described above.

5 The system shown in Figures 2 and 3 for producing a high ozone concentration high relative humidity outflow can be applied in other circumstances where it is desired to sterilise the interior of an item of apparatus, particularly processing apparatus for items such as pharmaceuticals or foodstuffs, or to sterilise a piece of apparatus or io equipment before its use or deployment.

Received at EPO via Web-Form on Dec 24, 2022

Claims

1 . Apparatus for forming a continuous series of filled packages from a strip of packaging film which comprises three chambers in communication

5 with one another and wherein a first chamber comprises means for sterilising the sides of a strip of foil fed through the first chamber, the second chamber comprises means to effect a further sterilisation step, and the third chamber comprises apparatus for forming the strip into a series of packages and filling each package with a desired quantity of sterile product and sealing around

10 each such quantity to form a series of filled packages, and means for discharging the filled packages from the third section, and characterised in that the means to effect a further sterilisation step in the second chamber comprises one or more pairs of spaced plates in the chamber, and means to feed the foil through the space between the plates and means to subject the

15 foil while passing between the plates to an ozone-generating corona discharge, by means for elevating the pressure of the atmosphere in the second chamber so that it flows out into the first and third chambers respectively and by means for feeding cooled filtered air into the second chamber at a rate sufficient to prevent overheating of the foil passing through

20 it.

2. Apparatus according to claim 1 wherein the first chamber includes a series of UV radiation emitters to sterilise the foil as it passes through.

3. Apparatus according to claim 1 or 2 wherein the cooled air introduced into the second chamber passes through one or more HEPA filters.

4. Apparatus according to any one of claims 1 to 3 and including means for introducing high concentration ozonised atmosphere into the third

30 chamber to effect vigorous pre-sterilisation of its content.

Received at EPO via Web-Form on Dec 24, 2022

5. Apparatus for sterilisation comprising a high output ozone generator, adapted to provide an outflow of predominantly oxygen containing atmosphere with an ozone concentration of at least 20,000 parts per million, an ultrasonic fogging unit having its input connected to the

5 output of the ozone generator and its output consisting of a predominantly oxygen containing flow having a relatively humidity of at least 80%, and means for operating the ultrasonic fogging unit by ultrasonically agitating a water bath over which the atmosphere flows while the temperature of the water bath is kept below 18 °C. io

6. Apparatus according to claim 5 including means for maintaining the the temperature of the water bath at 10°C or below.

7. Packaging apparatus according to any one of claims 1 to 4 and

15 including a sterilising atmosphere generator according to claim 5 or 6 and means for allowing the output of the generator to pass through the third chamber to sterilise its content prior to a filling operation.

Received at EPO via Web-Form on Dec 24, 2022