TECHNICAL FIELD

The field of invention relates to vacuum packages and vacuum packing methods. Particular embodiments relate to vacuum packing using polymer films.

BACKGROUND

In the field of packaging, there is an increasing need for packages that have better recyclability. This is especially true for packaging made essentially from polymers which are, by nature, mostly originating from fossil resources. Such better recyclability clearly provides benefits in that the package will waste less resources, and, after having ended its service life, will not simply end as waste which goes to landfill or is burned for energy recovery. For polymer-based packaging, the package as a whole, or part of a package, may be manufactured from polymer films. However, polymer films are usually made from several layers comprising different classes of polymers, hindering the sorting and recycling process of polymers drastically. It would therefore be advantageous to have a package with an improved recyclability while still enabling the implementation of widespread packaging technologies, such as vacuum packing. Additionally, using vacuum packing, filled flexible packages can be easily stacked directly for transportation which, in turn, decreases the need of secondary packaging, e.g. corrugated cardboard boxes, and contribute to a reduced usage of packaging materials.

In prior art solutions, polymer films for polymer-based packaging are indeed based on a multilayer arrangement, each layer having distinct properties regarding flexibility, puncture resistance, tear resistance, environmental barrier properties, seal initiation temperature, seal integrity, stretchability, etc. Each of the layers composing the film has also a different role which will affect the mechanical requirements for the considered layer, and thus the chemical composition of the considered layer. These different compositions will then affect the suitability of the polymer-based package to be recycled. So, there is a need for this suitability to be properly addressed.

SUMMARY The object of embodiments of the invention is to provide a package and a method for vacuum packing allowing an increased recyclability of the package and a reduced use of waste material when shipping these filled packages.

According to a first aspect of the invention, there is provided a package packing a product under vacuum, preferably a pillow-type package. The package is formed by a polymer film. The polymer film comprises: an outer film layer and an inner film layer. The outer film layer is a first polyethylene film layer. The inner film layer is a thermally sealable second polyethylene film layer having different thermal properties from said first polyethylene film layer. For example, the seal initiation temperature of the inner film layer may be between 105°C and 115°C, and the seal initiation temperature of the outer film layer may be between 125 °C and 135 °C. The package is provided with at least one opening on a side thereof. The at least one opening is configured for vacuum packing and for being closed by at least one closure element.

By having a package with two layers of polymer material of the same class, i.e. a mono-material package, the overall composition of the material composing the package is more uniform. And the more uniform a material is, the easier it is to be recycled. Depending on embodiments, the multiple layers of the polymer film may be laminated or co-extruded together.

At the same time, the product being packed within the package needs to be protected against the environment surrounding the package in order to avoid degradation caused from moisture intake or oxidation, for example. Also, the package should prevent the product packed within from spilling out of it.

Typically, the package taken individually has a substantial rectangular shape. To obtain that shape, the polymer film may first be sealed along one longitudinal edge such as to define a tube, then sealed at a bottom edge, filled, and finally sealed at an upper edge. Alternatively, the package may be obtained by starting from a tubular polymer film fed to a Vertical Form-Fill-Seal (VFFS) machine to be sealed at a bottom edge, filled, and finally sealed at an upper edge. So, the inner film layer is configured to allow sealing. Conventional heat sealing is implemented by application of heat locally for a certain time and with a certain pressure on the polymer films at the sealing location. However, while the inner film layer is being heated above its seal initiation temperature, the outer film layer also subject to the local application of heat is preferably at a temperature below its seal initiation temperature. Therefore, it is important for the first polyethylene film layer and the second polyethylene film layer to have different thermal properties. More particularly, the seal initiation temperature of the second polyethylene film layer is preferably significantly below the seal initiation temperature of the first polyethylene film layer. For example, the seal initiation temperature of the inner film layer 20 may be between 105 °C and 115°C and the seal initiation temperature of the outer film layer 10 may be between 125°C and 135°C.

Additionally, for vacuum to be achieved in the package, at least one opening is provided. The positioning of the at least one opening on the side of the package is especially suitable for the air within the package to be removed in a horizontal laying position of the package. When done that way, packages can then be laid easily on their side for palletization and transport. Indeed, the vacuumizing of the flexible package often ‘fixes’ the shape of the flexible package around the packed product and defines its encumbrance. Allowing for vacuumizing to be achieved in a horizontal position of the package allows for increased pallet stacking convenience and as such, transport performance security.

According to a preferred embodiment, the outer film layer and the inner film layer comprises >85.0 wt%, preferably >90.0 wt%, more preferably >95.0 wt%, of polyethylene with regard to the weight of the first polyethylene film layer and the second polyethylene film layer, respectively.

In this manner, a high fraction of polymer material composing the polymer film of the package is made of polymer of the same class. Suitability for the recyclability of the package is therefore ensured.

According to an exemplary embodiment, the outer film layer has a thickness between 8pm and 50pm, preferably between 10pm and 40pm, more preferably between 10pm and 30pm.

In this way, a low amount of material is used for the outer film layer, thereby reducing the potential waste of raw resources while still ensuring mechanical strength.

According to a preferred embodiment, the inner film layer has a thickness between 60pm and 150pm.

In this manner, an appropriate thickness is given for the inner film layer such that sealing strength and package integrity is maintained.

According to an exemplary embodiment, the outer film layer is a machine direction-oriented polyethylene (MDOPE) film layer.

It is to be noted that MDOPE film layers can be produced out of different grades of high density PE (HDPE) and/or grades or blends with medium density PE (MDPE) and linear low density PE (LLDPE). In this way, the thickness of the outer film layer is reduced while still obtaining mechanical properties for the film layer that are superior to those of a conventional polyethylene film layer having a similar thickness and produced via processes such as cast extrusion or blown film extrusion without orientation stretching. When producing a machine direction-oriented polyethylene film, the starting thickness is higher than the end thickness and the film is subject to an orientation process at temperatures below the melting temperature of the polyethylene material. Such orientation results in the film being stretched, decreasing its thickness. Depending on embodiments the outer film layer may be subjected to a mono or bi-directional orientation process.

According to a preferred embodiment, the inner film layer is a PE/EVOH/PE, a PE/SiOx, a PE/AlOx, or a metallized PE film layer, preferably a PE/EVOH/PE film layer.

In this manner, the inner film layer contains improved oxygen and migration barrier properties to protect the packed product, such as a food product, from deterioration. Examples are fat oxidation, aroma loss and unwanted migration and contamination coming from the outside atmosphere into the package.

According to an exemplary embodiment, the polymer film is a laminated film or a coextruded film.

In this way, bonding of the different film layers ensures better mechanical properties of the polymer film. The laminate may be formed using an adhesive layer between the outer film layer and the inner film layer. The adhesive layer may be a solvent-based adhesive or a solvent-free adhesive, for example a polyurethane-based adhesive. The laminate may be formed by applying the adhesive layer to one of the inner film layer or the outer film layer, putting in contact the inner film layer and the outer film layer, and applying a contact pressure.

In another embodiment, the adhesive may be a melt adhesive applied as an adhesive layer in molten form. The melt adhesive may be a thermoplastic material with adhesion capabilities relative to both the inner film layer and the outer film layer, for example a polyethylene -based material.

Alternatively, the polymer film may be prepared by a water-cooling co-extrusion inflation process, an air-cooling co-extrusion inflation process, a co-extrusion T-die process, a dry lamination process or an extrusion lamination process. According to an exemplary embodiment, the package further comprises an intermediate film layer between the outer film layer and the inner film layer. The intermediate film layer is a third polyethylene film layer, preferably a coextruded PE/EVOH/PE film layer.

Depending on embodiments, the intermediate film layer has a thickness between 8pm and 50pm, preferably between 10pm and 40pm, more preferably between 10pm and 30pm.

In this way, the package still retains its suitability to recycling. By addition of this intermediate polymer layer, the polymer film has improved mechanical properties such as an increased sealing window, puncture resistance, tear resistance, and environmental barrier properties.

According to a preferred embodiment, the intermediate film layer comprises >85.0 wt%, preferably >90.0 wt%, more preferably >95.0 wt%, of polyethylene with regard to the weight of the third polyethylene film layer.

As observed above, having a high fraction of polymer material of the same class composing the polymer film from which the package is made improves its suitability to recycling.

According to an exemplary embodiment, the at least one opening is formed by laser cutting.

In this way, the at least one opening may be formed with increased precision. In addition, sharp edges on the surface of the cut can be obtained, thereby decreasing the risk of having material tearing during the vacuumizing of the package.

Depending on embodiments, the at least one opening may be made in the polymer film in its sheet state or reel state before being shaped as a tube, after shaping it as a tube, or after filling it with the product. In the most preferred embodiment, the at least one opening is made when the polymer film is in its sheet state or reel state.

In addition, the at least one opening is formed such that it will preferably be located at the center on the side of the package. This allows for a more uniform vacuumizing of the package.

According to a preferred embodiment, the at least one opening comprises an opening with a rounded edge. Preferably, the at least one opening comprises a substantially oval shaped opening.

In this manner, tears in the package originating from a sharp angle change in the shape of the at least one opening are reduced. Depending on embodiments, the at least one opening may be a single opening or a plurality of openings, preferably a single opening. In a further embodiment, the inner film layer and/or the outer film layer is a machine direction-oriented polyethylene (MDOPE) film layer, the at least one opening comprises an opening with a rounded edge, preferably a substantially oval shaped opening. Despite, the inner film layer and/or the outer film layer being thinner than a conventional PE film layer, the shape of the at least one opening reinforces structurally the at least one opening and improves the resistance of the at least one opening when stress is applied thereto, for example when vacuumizing is performed and the at least one opening is subject to tensions from the surrounding material defining the at least one opening.

According to an exemplary embodiment, the at least one opening has a longest dimension (L) between 2mm and 20mm, preferably between 5mm and 18mm, more preferably between 8mm and 15mm.

In this way, the influence of the at least one opening on the structural integrity of the package is reduced. Additionally, the longest dimension of the at least one opening is preferably lower than a lowest dimension of an individual unit of the packed product for said individual unit of the product not to escape the package during vacuumizing.

It is to be noted that the evacuation of air from the package may be done directly through the at least opening, or, alternatively, after at least one valve has been provided to the at least one opening using an adhesive or by welding.

According to a preferred embodiment, the at least one opening has a shortest dimension (w) between 1mm and 10mm, preferably between 1mm and 8mm.

In this manner, evacuation of air from the package through the at least one opening is not impeded and can be achieved relatively quickly, preferably in an amount of time below 10 seconds.

Depending on embodiments, the evacuation of air from the package through the at least one opening may be performed manually or in an automated manner, preferably in an automated manner.

According to an exemplary embodiment, the at least one closure element comprises a sticker configured for sealing the at least one opening.

In this way, the at least one opening may be sealed in a simple manner. The sticker is provided with an adhesive layer on its face facing the package to ensure adhesion of the sticker to the package. Preferably, the sticker is circularly shaped and has a diameter of at least 100mm in order to avoid intake of air from the at least one opening, especially due to the appearance of air tunnels. According to a preferred embodiment, the sticker comprises >85.0 wt%, preferably >90.0 wt%, more preferably >95.0 wt%, of polyethylene with regard to the weight of the sticker.

In an embodiment, at least one valve has been provided to the at least one opening; the at least one valve is then sealed within the at least one opening. The valve may be self-closing after removal of the machine for vacuumizing. Additionally, a sticker may be provided over the at least one valve.

According to a preferred embodiment, the package has a first side and a second side. The first side is sealed to the second side along at least one edge seal of the first and second side. The at least one opening is provided in one of the first side and the second side.

In this manner, due to having two sides, handling of the package when laying horizontally is facilitated as well as the usage of a machine for vacuumizing through the at least one opening. Horizontal laying for vacuumizing is also beneficial for products whose individual units are in the millimeter range and above and which present interstitial spaces in-between.

According to an exemplary embodiment, the package has a length direction and a width direction. The at least one edge seal comprises a longitudinal edge seal in the length direction, a bottom edge seal in the width direction, and an upper edge seal in the width direction.

In this way, a pillow-type package is obtained which can be handled in a simple manner. When the polymer film is formed as a tube, an upper edge seal of a currently filled package may be made at the same time as a bottom edge seal of the next package in line. Additionally, cutting in between the upper edge seal and the bottom edge seal may be achieved simultaneously as the sealing to separate the currently filled package from the next package.

According to a preferred embodiment, the bottom edge seal and the upper edge seal have both a seal strength above 30N/15mm, preferably above 40N/15mm, more preferably above 50N/15mm, most preferably above 60N/15mm.

Additionally, the longitudinal edge seal may have a seal strength above 30N/15mm, preferably above 40N/15mm, more preferably above 50N/15mm, most preferably above 60N/15mm.

In this manner, high sealing strength is obtained, thereby preventing unintentional opening of the package from the bottom edge seal or the upper edge seal during pallet transportation, handling or during its shelf life. The skilled person will understand that the same advantages apply to the longitudinal edge seal.

According to an exemplary embodiment, the first side and the second side have both a side length (Ls) between 200mm and 800mm, preferably between 400mm and 700mm, and have a side width (w _s ) between 100mm and 500mm, preferably between 300mm and 500mm. A package characterized by the dimensions previously defined is qualified of being “large”.

According to a preferred embodiment, the package contains a load between 3kg and 30kg, preferably between 5kg and 25kg. A package characterized by the loads previously defined is qualified of being “heavy”.

In a further embodiment, there is provided a large and/or heavy package, and the at least one opening provided to the package comprises an opening with a rounded edge, preferably a substantially oval shaped opening. The shape of the at least one opening reinforces structurally the at least one opening and improves the resistance of the at least one opening when stress is applied thereto, for example when the at least one opening is subject to tensions from the surrounding material defining the at least one opening due to the dimensions of the package and/or the amount of load contained by the package. Additionally, the inner film layer and/or the outer film layer may be a machine direction-oriented polyethylene (MDOPE) film layer.

According to an exemplary embodiment, the product packed in the package is particulate matter, preferably food products, for example chocolate drops. More particularly, the particulate matter may be shaped as a disk-like format whose diameter is between 28mm and 35mm, and whose height is between 4mm and 8mm. The skilled person will understand that the at least one opening is sized so as not to allow the particulate matter to pass through the at least opening before or during vacuumizing.

By particulate matter, it is meant matter which is neither gaseous, nor liquid, nor in powder form, but can be divided in a plurality of individual units whose sizes can be in the millimeter range and above.

According to a preferred embodiment, the polymer film has a puncture resistance above 3N, preferably above 5N, more preferably above 10N.

In this way, products comprising sharp edges can still be packed safely and under vacuum. Indeed, it is important for the packing of these products that no perforation occur, either during the process of packaging or during the shelf life of the product including transportation and usage of the package. In the case perforation occurs, the product will be exposed to the environment and thus will be prone to quality degradation. This has to be avoided.

The skilled person will understand that the herein above described technical considerations and advantages for package embodiments also apply to the below described corresponding method of vacuumizing packing embodiments, mutatis mutandis.

According to a second aspect of the invention, there is provided a method of vacuum packing particulate matter, preferably food products, in a package. The method comprises the steps of: providing a tube made of a polymer film with at least one opening, said polymer film being configured for forming the package and comprising an outer film layer and an inner film layer, said outer film layer being a first polyethylene film layer and said inner film layer being a thermally sealable second polyethylene film layer having different thermal properties from said first polyethylene film layer; forming a bottom seal of the package by sealing facing sections of the inner film layer; filling the package with the particulate matter from a top direction; forming an upper seal of the package above the filled particulate matter by sealing facing sections of the inner film layer; optionally conveying the package from a vertical to a horizontal position; vacuumizing the package through the at least one opening; and closing the at least one opening.

According to an exemplary embodiment, the step of vacuumizing is performed on a substantially horizontal filled package.

In this manner, the distribution of the product along the length of the package is substantially uniform prior to vacuumizing, which facilitates the handling and the subsequent palletization of the package.

According to a preferred embodiment, the method further comprises the steps of: after the step of forming the upper edge seal, cutting the filled package from the tube so as to obtain a first filled package under vacuum, and repeating the steps of filling and forming an upper edge seal so as to obtain a plurality of filled packages; stacking the plurality of the filled packages on a pallet in a layered manner, wherein adjacent filled packages of the stacked plurality of filled packages are in direct contact. In this way, additional material, such as for example corrugated board boxes to pack individual or multiple filled packages could be avoided. Thus, the described method allows to decrease the generation of waste material after the shipping of the packages, whilst packing more product weight per individual pallet.

In a preferential embodiment, the different layers of packages on the pallet are separated from each other by skidproof sheets made of paper such as to improve the overall stability of the load on the pallet. Additionally, a PE-stretch film may be used to be wrapped around the stack of filled packages, and thus further stabilize the load on the pallet. Alternatively, the different layers of packages may be fixed to each other using glue.

According to an exemplary embodiment, the step of closing the at least one opening comprises providing at least one closure element, preferably a sticker, over the at least one opening.

According to a preferred embodiment, a vacuum level corresponding to a maximum absolute pressure of 600mbar, preferably a vacuum level corresponding to a maximum absolute pressure of 400mbar, is obtained during the step of vacuumizing the package.

In this manner, an evacuation of air is performed below a predetermined acceptable threshold such that degradation of the packed product due to the remaining air within the package is limited.

According to an exemplary embodiment, the at least one opening is provided by cutting, preferably laser cutting.

According to a preferred embodiment, the package is filled with a load of the particulate matter between 5kg and 25kg, preferably between 10kg and 20kg.

According to an exemplary embodiment, the dimensions of the at least one opening are smaller than the dimensions of a particle of the particulate matter.

BRIEF DESCRIPTION OF THE FIGURES

This and other aspects of the present invention will now be described in more detail, with reference to the appended drawings showing a currently preferred embodiment. Like numbers refer to like features throughout the drawings. Figures 1A-1B schematically depict schematic sections of a polymer film for a package according to different exemplary embodiments of the invention;

Figures 2A-2B illustrate schematic top views of packages according to further exemplary embodiments of the invention;

Figure 3 shows a flow chart of a method of vacuum packing particulate matter in a package according to exemplary embodiments of the invention.

DESCRIPTION OF EMBODIMENTS

Figures 1A-1B schematically depict schematic sections of a polymer film for a package according to different exemplary embodiments of the present invention.

The aim of the invention is to provide a package packing a product under vacuum. The package is formed by a polymer film 1, 1’.

In the embodiment of Fig.1 A, the polymer film 1 comprises an outer film layer 10 and an inner film layer 20. The outer film layer 10 and the inner film layer 20 have different thermal properties. More particularly, the outer film layer 10 and the inner film layer 20 may have different seal initiation temperatures, the seal initiation temperature of the inner film layer 20 being lower than the seal initiation temperature of the outer film layer 10. For example, the seal initiation temperature of the inner film layer 20 may be between 105°C and 115°C, and the seal initiation temperature of the outer film layer 10 may be between 125°C and 135°C.

Both the outer film layer 10 and the inner film layer 20 are polyethylene film layers. The outer film layer 10 will be referred to in the following as the first polyethylene film layer and the two terms can be used interchangeably. The inner film layer 20 will be referred to in the following as the second polyethylene film layer and the two terms can be used interchangeably. The inner film layer 20 is thermally sealable. In other words, when heated locally over an area, the heated area of the inner film layer 20 will melt, allowing upon cooling the adhesion of another area of overlapping inner film layer 20.

The first polyethylene film layer 10 and the second polyethylene film layer 20 form together the polymer film 1 by being laminated together or by being coextruded together. Preferably, the laminate may be formed using an adhesive layer between the first polyethylene film layer 10 and the second polyethylene film layer 20. The adhesive layer may be a solvent-based adhesive or a solvent-free adhesive, for example a polyurethane-based adhesive. The laminate may be formed by applying the adhesive layer to one of the first polyethylene film layer 10 or the second polyethylene film layer 20, putting in contact the first polyethylene film layer 10 and the second polyethylene film layer 20, and applying a contact pressure. In another embodiment, the adhesive layer may be a melt adhesive applied as an adhesive layer in molten form. The melt adhesive may be a thermoplastic material with adhesion capabilities relative to both the first polyethylene film layer 10 and the second polyethylene film layer 20, for example a poly ethylenebased material. Alternatively, the polymer film may be prepared by water-cooling co-extrusion inflation process, an air-cooling co-extrusion inflation process, a co-extrusion T-die process, a dry lamination process or an extrusion lamination process.

In an embodiment, the first polyethylene film layer 10 comprises >85.0 wt%, preferably >90.0 wt%, more preferably >95.0 wt%, of polyethylene with regard to the weight of the first polyethylene film layer. Additionally, the first polyethylene film layer 10 may be a machine direction-oriented polyethylene film layer. When producing a machine direction-oriented polyethylene film, the starting thickness is higher than the end thickness and the film is subject to an orientation process at temperatures below the melting temperature of the polyethylene material. Such orientation results in the film being stretched, decreasing its thickness. Depending on embodiments the first polyethylene film layer 10 may be subjected to a mono or bi-directional orientation process.

The first polyethylene film layer 10 may have a first thickness ti as seen in the plane of the section. The first thickness ti may be between 8pm and 50pm, preferably between 10pm and 40pm, more preferably between 10pm and 30pm.

Similarly as the first polyethylene film layer 10, in an embodiment, the second polyethylene film layer 20 also comprises >85.0 wt%, preferably >90.0 wt%, more preferably >95.0 wt%, of polyethylene with regard to the weight of the second polyethylene film layer 20. Additionally, the second polyethylene film layer 20 may be a PE/EVOH/PE, a PE/SiOx, a PE/AlOx, or a metallized PE film layer, preferably a PE/EVOH/PE film layer. The second polyethylene film layer 20 may have a second thickness tz as seen in the plane of the section. The second thickness tz may be between 60pm and 150pm.

Fig. IB differs from the above described embodiment of Fig.lA only in that the polymer film 1’ further comprises an intermediate film layer 30’ between an outer film layer 10’ and an inner film layer 20’ . The intermediate film layer 30’ is referred to as a third polyethylene film layer and the two terms can be used interchangeably. In an embodiment, the third polyethylene film layer 30’ comprises >85.0 wt%, preferably >90.0 wt%, more preferably >95.0 wt%, of polyethylene with regard to the weight of the third polyethylene film layer 30’ . Additionally, the third polyethylene film layer 30’ may be a PE/EVOH/PE film layer. The intermediate film layer 30’ may have a third thickness tz’ as seen in the plane of the section. The third thickness tz’ may be between 8pm and 50pm, preferably between 10pm and 40pm, more preferably between 10pm and 30pm. Figures 2A-2B illustrate schematic top views of packages according to further exemplary embodiments of the present invention. The packages in the embodiments of Figs.2A-2B are formed by a polymer film as described with reference to Fig.lA or Fig. IB. The embodiment illustrated in Fig.2B is the preferred embodiment of the invention.

In both the embodiments of Figs.2A-2B, the package 100 has a first side 110 and a second side 120. The first side 110 is sealed to the second side 120 along at least one edge seal 50, 60, 115 of the first side 110 and the second side 120. More particularly, the at least one edge seal 50, 60, 115 is obtained by heating locally a sealing area at the location where a seal is required at a temperature above the seal initiation temperature of an inner film layer composing the polymer film. The sealing area is defined by an overlapping of a first inner film layer portion belonging to the first side 110 and of a second inner film layer portion belonging to the second side 120.

In another embodiment, the first side 110 is sealed to the second side 120 along three edge seals 50, 60, 115 of the first side 110 and the second side 120.

In the embodiments of Figs.2A-2B, the package has a substantially rectangular shape. The skilled person will understand that this shape is only by way of example and that other shapes of packages may also be used and adapted readily to the benefits and advantages of the present invention. The package 100 of Figs.2A-2B has a length direction and a width direction. The at least one edge seal of Figs.2A-2B comprises three edge seals 50, 60, 115: a longitudinal edge seal 115 in the length direction, a bottom edge seal 50 in the width direction, and an upper edge seal 60 in the width direction, opposite the bottom edge seal. The longitudinal edge seal 115 is preferably located substantially centrally relative to the second side 120.

In the embodiments of Figs.2A-2B, the polymer sheet is folded in two and sealed with the longitudinal edge seal 115 along its length direction to define a tube.

The bottom edge seal 50 and the upper edge seal 60 have both a seal strength above 30N/15mm, preferably above 40N/15mm, more preferably above 50N/15mm, most preferably above 60N/15mm. Also, the longitudinal edge seal 115 has a seal strength above 30N/15mm, preferably above 40N/15mm, more preferably above 50N/15mm, most preferably above 60N/15mm. The first side 110 and the second side 120 have both a side length L _s between 200mm and 800mm, preferably between 400mm and 700mm, and have a side width w _s between 100mm and 500mm, preferably between 300mm and 500mm.

The package 100, after being filled and completely sealed, may contain a load between 3kg and 30kg, preferably between 5kg and 25kg. It is also important that products comprising sharp edges can still be packed safely and under vacuum. Indeed, it would be detrimental for the packing of these products if a perforation through the polymer materials would occur, either during the process of packing, the supply chain or during the shelf life of the product. In the case perforation occurs, the product will be exposed to the environment and thus will be prone to degradation. To avoid that, the polymer film may have a puncture resistance above 3N, preferably above 5N, more preferably above ION.

At least one opening 40, 40’ is provided in one of the first side 110 and the second side 120, in the first side 110 in the embodiments of Figs.2A-2B. The at least one opening 40, 40’ is formed by laser cutting in order to obtain sharp edges on the surface of the cut, thereby decreasing the risk of having material tearing during the vacuumizing of the package. In other embodiments, the at least one opening may be obtained by physically puncturing, thermally puncturing, and/or by punching a through-hole. Additionally, the at least one opening 40, 40’ may comprise an opening with a rounded edge.

The at least one opening 40, 40’ may be made in the polymer film 100 in its sheet state or reel state before being shaped as a tube, after shaping it as a tube, or after filling it with the product. In the most preferred embodiment, the at least one opening 40, 40’ is made when the polymer film 100 is in its sheet state or reel state.

In Fig.2A, the at least one opening 40 consists of three circular openings describing an equilateral triangular shape. The at least one opening 40 of Fig.2A is located substantially in the middle of the first side 110 in the width direction and near the upper edge seal 60 in the length direction. In the preferred embodiment of Fig.2B, the at least one opening 40’ consists of a single oval shaped opening. The at least one opening 40’ is located in the center of the first side 110 in both the width direction and the length direction, opposite the longitudinal edge seal 115. This allows for a more uniform vacuumizing of the package 100. The oval-shaped opening of the at least one opening 40’ is oriented along the length direction of the package 100.

The at least one opening 40’ of Fig.2B has a longest dimension Lo between 1mm and 20mm, preferably between 5mm and 18mm, more preferably between 8mm and 15mm. Also, the at least one opening 40’ of Fig.2B has a shortest dimension wo between 1mm and 10mm, preferably between 1mm and 8mm.

The product packed in the package 100 is particulate matter, preferably food products such as chocolate drops. It is advisable for the dimensions of the at least one opening 40, 40’ to be smaller than the dimensions of a particle, i.e. an individual unit, of the particulate matter such that the product is not evacuated through or blocking the vacuum opening when evacuating air during the vacuumizing. More particularly, the particulate matter may be shaped as a disk-like format whose diameter is between 28mm and 35mm, and whose height is between 4mm and 8mm. The skilled person will understand that, generally, the at least one opening is sized so as not to allow the particulate matter to pass through the at least one opening during vacuumizing.

After performing the vacuumizing, the at least one opening 40, 40’ is sealed by at least one closure element 45, 45’. In the embodiments of Figs.2A-2B, the at least one closure element 45, 45’ comprises a sticker configured for sealing the at least one opening 40, 40’ . In another embodiment, at least one valve may be provided to the at least one opening 40, 40’ and sealed within the at least one opening 40, 40’ using an adhesive or welding to attach it to the polymer film. The at least one valve may be self-closing after performing the vacuumizing but can additionally be covered by a sticker. The sticker included in the at least one closure element 45, 45’ is provided with an adhesive layer facing the package 100 to ensure adhesion of the sticker to the package 100. Preferably, the at least one closure element 45, 45’ is circularly shaped and has a diameter of at least 100mm in order to avoid intake of air from the at least one opening 40, 40’. According to a preferred embodiment, the sticker comprises >85.0 wt%, preferably >90.0 wt%, more preferably >95.0 wt%, of polyethylene with regard to the weight of the sticker.

The skilled person will understand that the sticker included in the at least one closure element 45, 45’ is not limited by a particular shape and may be a rectangular sticker 45 such as depicted in Fig.2A or a circular sticker such as depicted in Fig.2B, for example.

Figure 3 shows a flow chart of a method of vacuum packing particulate matter in a package according to exemplary embodiments of the present invention. The package obtained is similar to embodiments of packages depicted in Figs.2A-2B.

The first step S10 of the method comprises the providing of a tube made of a polymer film with at least one opening. The tube may be provided by a forming and sealing machine configured for forming the polymer film in the shape of a tube from a polymer film reel, and for sealing the formed tube in a longitudinal direction. This tube is then fed to a subsequent machine configured for sealing and filling the package. In a preferred embodiment, a VFFS machine is used for forming the tube in line prior to a sealing step (for a bottom edge seal and/or an upper edge seal of the package) and a filling step of the package.

The polymer film used is similar to embodiments of polymer films depicted in Figs.lA-lB. The polymer film is configured for forming the package and comprises an outer film layer and an inner film layer. The outer film layer is a first polyethylene film layer and the inner film layer is a thermally sealable second polyethylene film layer having different thermal properties from the first polyethylene film layer. The tube may be formed with a single polymer film folded in two such as to have facing portions of the inner film layer, and sealed by a longitudinal edge seal along its length direction.

In the first step S10 of the method, the at least one opening may be obtained by physically puncturing, thermally puncturing, cutting, e.g. laser cutting, and/or by punching a through-hole through the polymer film. In the embodiment of Fig.3, the at least one opening may be made in the polymer film in its sheet state or reel state before being shaped as a tube, or after having obtained a polymer tube from the at least one polymer film sheet. The dimensions of the at least one opening are smaller than the dimensions of a particle of the particulate matter. The second step SI 1 of the method comprises forming a bottom edge seal of the package by sealing facing sections of the inner film layer. The forming of the bottom edge seal is performed by heating locally the polymer tube across its entire width at a temperature above the seal initiation temperature of the inner film layer and below the seal initiation temperature of the outer film layer.

In the next step SI 2, the method comprises the filling of the package with the particulate matter from a top direction. For practicality reasons, when the polymer tube is provided in the first step S10, it is arranged around a substantially cylindrical conduit from a top direction. The polymer tube will then further travel along the length of the conduit. The second step Sil will be performed by a sealing clamp following the end of the conduit, below it. After making the polymer tube travel along a predetermined distance (the length of the package) along the conduit following step Si l, step S12 will proceed. The conduit will then be used in step S12 to funnel the product from the top direction, which will pile over the formed bottom edge seal. The package may be filled in step S12 with a load of the particulate matter between 5kg and 25kg, preferably between 10kg and 20kg.

Following the filling of the package, the method comprises step S13 of forming an upper edge seal of the package above the filled particulate matter by sealing facing sections of the inner film layer. To achieve this, the same sealing clamp as used in step Si l may be utilized. More particularly, the sealing clamp may at the same time form the upper edge seal of the current package and a bottom edge seal of a next package. In an alternative embodiment, the polymer tube is precut in sections of predetermined length (the length of the package) and the upper edge seal of the current package and the bottom edge seal of the next package are formed in individual steps. In yet another embodiment, the package is preformed and only the upper edge seal needs to be formed after the filling of the package.

Then, the method comprises step S15 of vacuumizing the package through the at least one opening. The step of vacuumizing S15 may be performed on a substantially horizontal filled package by conveying the filled and sealed package from a vertical position to a horizontal position. This allows for the particulate matter packed in the package to be more uniformly spread across the length of the package, thereby rendering subsequent handling and palletization easier. Additionally, air located in interstitial spaces between individual units (particles) of the particulate matter can be evacuated more easily. A vacuum of at least 600mbar, preferably a vacuum of at least 400mbar, may be obtained during the step of vacuumizing S15 the package.

Finally, the method comprises a step of closing S16 the at least one opening. The step of closing S16 the at least one opening may comprise providing at least one closure element, preferably a sticker, over the at least one opening. In an alternative embodiment, at least one valve may be provided to the at least one opening and sealed within the at least one opening. The at least one valve may be self-closing after removal of a machine used for step S15. The skilled person will understand that, depending on embodiments, the at least one valve may be sealed within the at least one opening and incorporated already to the polymer film in its sheet state or reel state, or may be sealed within the at least one opening inline prior to step S10, or inline between step S14 and step S15.

In the embodiment of Fig.3, in the case that the polymer tube is provided, after the step of forming S13 the upper seal, the method may further comprises the step of cutting S14 the filled package from the polymer tube so as to obtain a first filled package under vacuum, and repeating the steps of filling S12 and forming S13 an upper edge seal so as to obtain a plurality of filled packages.

Once filled packages of particulate matter are obtained by vacuum packing, they are stacked in a final step S20 of the method. The skilled person will understand that this step is optional and not necessarily needed for forming and filling the package. The step of stacking S20 comprises the stacking of the plurality of the filled packages on a pallet in a layered manner, wherein adjacent filled packages of the stacked plurality of filled packages are in direct contact. This is made possible thanks to the horizontal laying of the packages prior to vacuumizing through the at least one opening provided to the side of the package.

In a preferential embodiment, the different layers of packages on the pallet are separated from each other by skidproof sheets made of paper such as to improve the overall stability of the load on the pallet. Additionally, a PE-stretch film may be used to be wrapped around the stack of filled packages, and thus further stabilize the load on the pallet. Alternatively, the different layers of packages may be fixed to each other using glue.

Whilst the principles of the invention have been set out above in connection with specific embodiments, it is to be understood that this description is merely made by way of example and not as a limitation of the scope of protection which is determined by the appended claims.