Abstract:
The invention relates to a device for sterilization of the interior surface of packaging containers with electron beam, comprising an emitter provided with an electron exit window. The emitter is adapted to emit charge carriers, such as electrons, through the electron exit window, said electrons forming an electron cloud. The device comprises at least one outlet adapted to provide a flow of sterile gaseous medium adapted to maintain a local aseptic zone around at least an emitter portion including the electron exit window, thus preventing any flow of medium from outside the local aseptic zone from coming into the local aseptic zone. The invention also relates to a method.

Description:
TECHNICAL FIELD 
       [0001]    The present disclosure concerns a cap chamber for sterilizing caps or closures, and a method for sterilizing caps. 
       TECHNICAL BACKGROUND 
       [0002]    In filling of commercially sterile products into sterilized packaging containers it is important that all components of the packaging container are sterilized. With “all components” we refer to all components having a surface to which the contents of the packaging container may have access, and as minimum requirement at least that particular surface should be sterilized. In a wider perspective it may be desired to sterilize such components fully, or at least to sterilize a greater area than what is included in the surface that will be in contact with the contents of the packaging container. One reason may be to prevent the occurrence of reinfection, i.e. the migration of contaminants from a non-sterile to a sterile area, another may be to prevent contaminants from entering an otherwise sterile area. 
         [0003]    In the present disclosure the word “sterile” is frequently used. For most applications the definition conforms to the definition of “commercially sterile”. For all applications it will conform to the definition “sterile enough for the purposes of the application” and “sterilization” and similar may be defined as “treatment with a sterilant until sterile”. 
       SUMMARY 
       [0004]    To this end the present invention relates to a device and a method for sterilizing caps. As used herein caps are meant to include several types of closure arrangements, such as screw caps, flip caps, snap caps, sports caps, and closure arrangements comprising a cap and a portion of a packaging container, which will be described in greater detail in the description referring to the drawings. 
         [0005]    According to one aspect the present disclosure relates to a cap sterilization device comprising a sterilization chamber having a cap inlet and a cap outlet and guide means for guiding caps through the sterilization chamber. The device further comprises a nozzle for injecting a sterilant into the sterilization chamber and at least two exhaust outlets for evacuation of gases from the sterilization chamber. 
         [0006]    According to one or more embodiments the nozzle may be arranged to inject gaseous sterilant towards an open end of the caps. 
         [0007]    In one or several embodiments the first exhaust outlet may be arranged in the cap inlet and a second exhaust outlet may be arranged in the cap outlet. 
         [0008]    The caps may be arranged to be indexed forward in an intermittent manner while the nozzle is arranged to provide a continuous flow of sterilant. 
         [0009]    A valve may be arranged upstream the nozzle, between the nozzle and a vaporizer, the nozzle being able to selectively redirect a flow from the vaporizer into an exhaust manifold instead of to the nozzle. 
         [0010]    The nozzle may be arranged to provide an amount of sterilant such that the concentration in the sterilization chamber varies with less than 25% over a volume defined by the first exhaust outlet and the second exhaust outlet, counted as maximum concentration compared to minimum concentration in the volume. 
         [0011]    In any embodiment the sterilant may comprise hydrogen peroxide, or a mixture of components one of which is hydrogen peroxide. Other examples may include peracetic acid (PAA) and compounds thereof, or other sterilization agents or sterilants. 
         [0012]    According to a second aspect the intention relates to a method for sterilizing caps. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0013]      FIG. 1  shows a cross sectional side view of a sterilization device, or at least a schematic illustration thereof. 
           [0014]      FIG. 2  is a detailed view, still schematic, of a cap. 
           [0015]      FIG. 3  a schematic side view of a packaging container. 
       
    
    
     DETAILED DESCRIPTION 
       [0016]      FIG. 1  is a schematic cross section of a sterilization device  100  having a sterilization chamber  101 . The sterilization device  100  is shown from one side thereof. Caps  102  are arranged to follow guide means  104  through the sterilization chamber  101 . The caps  102  enter via a cap inlet  106  and exits via a cap outlet  108 . In the present embodiment the caps  102  are fed by gravity, and once a cap  102  is removed from the guide means  104  downstream the sterilization chamber  101  the entire line of caps  102  is incremented one step downstream. The removal of caps  102  downstream may be performed in a step to move the cap  102  from the line of caps to a cap-application device or another processing step. The caps may in other instances be directed to storage, awaiting later use. The one-by-one removal of caps will generate the intermittent motion pattern of caps. The sterilization device  100  as disclosed herein may in other embodiments be based on a continuous motion pattern. Furthermore, it is foreseeable to arrange another type of drive, yet use of gravity vouches for simplicity and a non-complex construction inside the sterilization chamber  101 . 
         [0017]    Inside the sterilization chamber  101  there is a hydrogen peroxide nozzle  110  arranged to inject hydrogen peroxide into the chamber  101 . The nozzle  110  is furthermore arranged to inject the hydrogen peroxide towards the caps  102 . In particular the nozzle  110  may be arranged to inject a spray towards and impact an area surrounding a particular cap position such as to fully reach all portions of a cap. It is preferable that the sterilant is injected in gaseous form. For this reason there is a vaporization device arranged upstream the nozzle  110 . As a non-limiting example the temperature in the vaporization device may be 210° C. and for one particular embodiment the consumption includes 0.7 l/h of hydrogen peroxide (3% concentration by volume) and the addition of about 80 l/min of air. All of these parameters may shift depending on the preferred level of sterilization and of the size of the sterilization chamber etc. 
         [0018]    Exhausts  112 ,  114  are arranged at the cap outlet  108  and the cap inlet  106  respectively. The exhausts ensure that the amount of hydrogen peroxide released to the atmosphere is kept at an absolute minimum, or is completely avoided, by evacuating it to a exhaust manifold leading to a destruction device (not shown). Rather than necessarily having an underpressure, i.e. a lower pressure inside the sterilization chamber than in the immediate surroundings, to prevent hydrogen peroxide or any other sterilant from leaving the sterilization chamber, the present sterilization chamber  101  rather controls gas flows locally in the area of the inlet  106  and the outlet  108  respectively. Thus the exhausts  112 ,  114  efficiently prevents gas passage into and out from the sterilization chamber  101 . Furthermore, the sterilant containing atmosphere of the sterilization chamber  101  will be pulled towards both the inlet  106  and towards the outlet  108 , meaning that as soon as a cap  102  enters through the inlet  106  the sterilization treatment will commence. When passing an impact area of the sterilization spray the cap  102  will experience a maximum load of sterilant, after which the concentration may gradually decrease, yet be maintained, until the cap  102  leaves the sterilization chamber  101  through the outlet  108 . It may be emphasized that the caps  102  pass the sterilization chamber  101  with their open end directed towards the hydrogen peroxide nozzle  110 . An effect of the present setup is that there will be a generally elevated concentration of sterilant in the sterilization chamber such that surfaces not reached directly by the sterilant spray provided by the nozzle  110  will still be exposed to such high concentrations of sterilant that adequate sterilization is enabled. Consequently the purpose of the nozzle  110  is not merely to supply an adequate amount of sterilant to the interior of a cap  102 , but also to ensure an adequate concentration of sterilant in the sterilization chamber as a whole. In the present embodiment the nozzle  110  is arranged in such a way that it is aligned with a particular cap position, meaning that as the caps are moved incrementally through the sterilization chamber they will all at one position be facing the sterilization nozzle  110 , and the spray will be directed to the interior of the cap  102 . 
         [0019]    After application and as the surface temperature of the cap  102  increases the condensed sterilant will start to vaporize such that a minimum amount of sterilant leaves the sterilization chamber via the caps. Furthermore, the flow balance of the sterilization chamber will be such that there is a flow of surrounding air entering through the outlet and the inlet respectively, and even though this air will leave through the nearest exhaust it will still fulfil a function of preventing sterilant from leaving into the surroundings. The source of heat is in the present embodiment only the heated sterilant spray, and the caps are only tempered by means of being stored in a particular temperature before being fed to the cap sterilization device. The present case does not exclude the possibility of using heaters (or coolers) to temper the caps or the sterilization device, if needed to increase controllability. 
         [0020]    As a further effect the concentration of sterilant will be evenly distributed within the constraints of the sterilization chamber  101 , at least in a volume defined by the first exhaust outlet  112  and the second exhaust outlet  114  as indicated by the dotted area in  FIG. 1 . The boundaries of the dotted area should not be construed as exact. In particular, the flow around the cap in the vicinity of the exhaust outlets may vary a bit, but given that the variation in the concentration of sterilant within the defined area may be less than 25%, the main variations being formed in the boundaries. Outside of the boundaries the concentration of sterilant may be negligent since surrounding air free from sterilant may be pulled in to the cap inlet and the cap outlet and straight into the exhaust outlets  112  and  114  respectively. To that end the present device provides sterilization by means of a direct spray of sterilant combined with an overall increased concentration of sterilant providing a topical sterilization of all accessible surface of a cap  102  sterilized in the sterilization chamber  101 . 
         [0021]    It is preferred that the sterilant leaves the nozzle  110  in a continuous manner in order to maintain a desired concentration of sterilant inside the sterilization chamber  101 . In the event of unexpected stops downstream the sterilization chamber a valve  116  may be switched directing the flow of sterilant directly to an exhaust manifold  113  rather than into the sterilization chamber through the nozzle  110 . In such a case the signal to the valve to effect the switch will come from a control unit the details of which are not relevant for explaining the present device. 
         [0022]    The guide means  104  are arranged to localize the caps  102  during their passage through the sterilization chamber. While fulfilling that main purpose they should avoid shadowing (covering) too much of the caps  102 , since that may inhibit proper sterilization. Also, the guide means  104  are arranged to maintain a distance between the caps  102  and a back wall of the sterilization chamber  101 , i.e. the wall remote to the hydrogen peroxide nozzle  110 . The purpose is to enable hydrogen peroxide to reach all surfaces of each cap. To that end it may be preferred to introduce the caps through the inlet  106  at a temperature being below the condensation point of the sterilant at prevailing conditions. In this way the sterilant will condensate at all surfaces of the cap or closure  102 . In the present embodiment the guide means comprises a number of rails  104  with a circular cross section, yet other options should be readily available for the skilled person. 
         [0023]      FIG. 2  is a view in the a longitudinal axis of the guide means  104 , i.e. a partial view from above of  FIG. 1 , illustrating one example of how guide means may be arranged. In the particular setup shown the caps  102  may be caused to rotate along a longitudinal axis (an axis extending parallel to an axis of rotational symmetry of the cap. As shown in  FIG. 2  there are more guiderails  104  arrange to one side of the cap  102 . This may generate a frictional force breaking this side in relation to the other side, which may cause a rotational motion as the cap travels through the sterilization chamber  101 . Due to the rotation more surfaces of the cap will be fully exposed to the hydrogen peroxide spray. There are obviously a number of ways of accomplishing rotation of the caps as they travel through the sterilization chamber  101 . The general approach of creating more friction on one side than on the other is a simplistic and efficient method, yet other method e.g. based on an individual drive for the rotation would in principle also be possible. 
         [0024]    While viewing the more detailed view of  FIG. 2  it may be worth mentioning that while the word cap is used in the present description and while the item being sterilized may actually be a cap according to any definition, a closure arrangement may be more suitable in the context of the embodiment shown in  FIG. 2 , as was mentioned in the summary portion. For the sake of simplicity “cap” is used to designate all such closure arrangements. For the sake of explaining the closure arrangement shown in  FIG. 2 , it the cap  102  and a portion of the neck, including a threaded neck  118  and an attachment flange  120 . Such attachment flange may be utilized when arranging the closure arrangement onto a packaging container. The packaging container  122 , as shown in  FIG. 3 , may comprise a packaging-laminate sleeve  124  e.g. made from a packaging laminate comprising plastic and paper layers as is commonly used. The sleeve  124  may be directly fused to the closure arrangement, yet the two components may also be connected via a plastic shoulder portion  126 . An example of such a packaging container is the one commercialized under the name Tetra Evero® Aseptic. In still other embodiments the  120  may be used to attach the closure arrangement onto a flat or folded piece of packaging laminate. Examples of this latter packaging container may be the ones commercialised by the present applicant under the names, Tetra Rex®, Tetra Gemina® Aseptic, Tetra Brik® Aseptic, etc.