The present invention relates to a horizontal packaging machine with film sterilization comprising at least a film welding station for welding the film such as to form at least the bottom of the packages. The invention further relates to a method for forming packages from a film.
BACKGROUND OF THE INVENTION
Many applications require providing packages made from a film to be sterilized so that the final package, which could comprise the package itself filled with a desired product therein, is under aseptic conditions.
For this aim, some prior art packaging machines include an aseptic section in which a sterilizing station is operable to aseptically sterilize the packages after they have been formed and prior to their filling.
A sterilizing station of this type is known from PCT application W09908932 in which packages are placed under a sprayer device where hydrogen peroxide gas is sprayed thereon. Packages are carried to a sterilizing chamber, irradiated with ultraviolet rays and dried by high temperature air. Hydrogen peroxide gas is washed away and removed. Packages are then filled with the desired product and sealed up.
The sterilization is typically carried out after the package is being formed, that is, once the folded film or sheet material from which packages are made has been welded at least to form the bottom of the package. However, the welding operation may involve wrinkle formation in the bottom of the package, and this could give rise to areas that are not completely exposed to chemical action, such that there is a risk that the package is not sufficiently sterilized.
This risk is especially relevant in the case of packages such as pouches of the so-called "stand-up" type, in which the bottom of the pouch has a double fold and a curved shape around the welding. Such packages have a double-fold bottom and need to be opened thoroughly in order to expose the whole inner bottom portion, and areas shielded from chemical sterilization may arise very easily.
DESCRIPTION OF THE INVENTION
The present invention aims to at least reduce the above disadvantage. For this purpose, there is provided a horizontal packaging machine with film sterilization which comprises at least a film welding station for welding the film such as to form at least the bottom of the packages and a film sterilizing station, arranged upstream of the film welding station. The film is therefore sterilized before any sealing or welding operations are performed, for example those required for forming the bottom of the packages.
Provision of a film sterilizing station for sterilizing the film before the packages are formed facilitates the complete exposure of the film surface to the sterilization chemicals: complete sterilization of all points in the package surface is thus more easily accomplished, and consequently packages are more completely and efficiently sterilized.
In one embodiment of the invention, the film sterilizing station comprises a chemical sterilizing unit in which chemical sterilization of the film is performed by means of a sterilizing gas, such as for example, hydrogen peroxide. The use of hydrogen peroxide in the gas phase has the advantage that it has a stronger sporecide action and consequently the sterilization is carried out within a shorter period of time. A further advantage is that once the gas has been applied to the film, it may be easily removed therefrom such that waste peroxide is sparsely present after application of the sterilizing gas. Finally, the use of gas allows the sterilizing station to be smaller.
The sterilizing station comprises a housing that is under negative pressure and it is provided with means for the passage of the film therethrough.
In one alternative embodiment, said negative pressure is established by a chamber located outside the housing which is connected to a draw duct therein.
The chemical sterilizing unit comprises means for sterilizing at least a surface of the film intended to form the inner surface of the package.
Preferably, the machine comprises a filling station and an aseptic section arranged downstream of said welding station. The aseptic section comprises said filling station.
Still in a further embodiment of the invention, the machine includes a film folding device for folding the film longitudinally. Said film folding device is arranged upstream of the welding station. In this case, the film sterilizing station is arranged between the film folding device and the welding station.
The machine of the invention may comprise a film unwinding section for unwinding a film from a feed reel. In this case, the film sterilizing station is arranged in said film unwinding section.
The film may travel through said film sterilizing station either along a substantially straight path or along a wave-like path.
Both in the case of sterilizing the film in the unwinding section with the film completely unfolded or sterilizing the film between the unwinding section and the welding station, it is possible, according to the invention, to fully sterilize the inner and the outer surface of the film.
The present invention further relates to a method for forming packages from a film, comprising at least the steps of unwinding the film from a feed reel, chemically sterilizing the film; and forming at least the bottom of the packages by welding the film.
BRIEF DESCRIPTION OF THE DRAWINGS
A particular embodiment of the present invention will be described in the following, only by way of non-limiting example, with reference to the appended drawings, in which:
- Fig. 1 is a front elevational view of a film sterilizing station according to one embodiment of the invention;
- Fig. 2 is a side elevational view of the film sterilizing station in Fig. 1;
- Fig. 3 is a top plan view of the film sterilizing station in Fig. 1;
- Fig. 4 is a side elevational part view of one embodiment of the invention in which the film sterilizing station is fitted in the machine located in the unwinding section;
- Fig. 5 is a side elevational part view of a one embodiment of the invention in which the film sterilizing station is fitted in the machine located upstream of the film welding station, between the film folding device and the welding station;
- Fig. 6 is a perspective part view of the film sterilizing station of the embodiment in Fig. 4 in which the film sterilizing station is located in the unwinding section;
- Fig. 7 is a perspective part view of the film sterilizing station of the embodiment in Fig. 5 in which the film sterilizing station is located between the film folding device and the welding station; and
- Fig. 8 is a top plan view of a horizontal packaging machine having a film sterilizing station according to the embodiment in Figs. 5 and 7.
DESCRIPTION OF PREFERRED EMBODIMENTS
The drawings show two embodiments of a horizontal packaging machine according to the invention differing from each other in the position of the sterilizing station in the machine.
In the figures, the horizontal packaging machine has been indicated generally at 1 and it comprises an unwinding section 2 for unwinding a film 3 from a feed reel 4, a film welding station 5 that performs the welding of the film 3. A film folding device 16 is provided downstream the unwinding section 2.
A film sterilizing station 10 is further provided in the packaging machine 1 shown in the figures. The film sterilizing station 10 is generally placed upstream the film welding station 5 and it serves the purpose of sterilizing the film 3 before the bottom of the packages is formed.
Said film sterilizing station 10 comprises a chemical sterilizing unit in which chemical sterilization of the film is performed by means of a sterilizing gas. In the embodiment shown in the figures, the sterilizing gas is hydrogen peroxide in the gas phase. Gas hydrogen peroxide is used for sterilizing the film 3 since it has been found its physical properties are notably advantageous for sterilization.
As it may be seen from figures, particularly figs. 1 to 3, the film sterilizing station 10 comprises a housing 11 which is provided with inlet and outlet grooves for enabling the passage of the film 3 therethrough. The film 3 may travel through said film sterilizing station 10 along a substantially straight path or a wave-like path.
The housing 11 is under negative pressure for operator's safety. Negative pressure may be established either within the housing 11 of the film sterilizing station 10 itself or from a chamber (not shown) located outside the housing 11 and connected to a draw duct therein.
The housing 11 is provided with gas nozzles 12 for injecting the hydrogen peroxide gas to the film 3 as it passes through the inside of the housing 11 as shown in Fig. 1. The gas nozzles 12 are connected to a hydrogen peroxide source through a corresponding tube 13. The housing 11 is also provided with a pivotable door 14 with a handle 14a which may be opened for accessing the film 3 therein.
In the particular embodiment shown in figs. 4 and 6 of the drawings, the film sterilizing station 10 is fitted in the machine 1 in the unwinding section 2. As the film 3 is unwound from the feed reel 4 in the unwinding section 2, it passes through a number of alternated rollers 15, as shown in fig. 6, within the housing 11 of the film sterilizing station 10 where it is chemically sterilized.
In the embodiment shown in figs. 5 and 7 of the drawings, the film sterilizing station 10 is fitted in the machine 1, between the film folding device 16 and the welding station 5.
The common feature in both embodiments is that the film sterilizing station 10 is located in the machine 1 upstream the welding station 5 in which at least the bottom of the packages are formed by welding the film 3.
While the embodiments described herein with reference to figs. 1 to 8 refers to a horizontal packaging machine 1 having one film sterilizing station 10, it is to be noted that said film sterilizing station 10 could be a station additional to a first film sterilizing station. In both cases, the film sterilizing station 10 is always located upstream the welding station, in particular, upstream the welding station 5 that forms the bottom of the package. Also in both cases, the film 3 is sterilized by at least one of its inner and outer surfaces. In the embodiments shown in the figures, in which only one film sterilizing station 10 is present in the machine 1, the inner and outer surfaces of the film 3 are sterilized by said film sterilizing station 10. In other embodiments having more than one film sterilizing station, it is sufficient for the film sterilizing station 10 to sterilize the inner surface of the film 3.