Method for the protective gas flushing of a packaging, and gas flushing station

Abstract

In a gas flushing station (5), a packaging (4) is gas-flushed, which packaging comprises a shell (22) filled with a product (23). The shell (22) is covered by a cover film (24) and is sealed thereby, and the packaging (4) comprises a packaging opening (26). The packaging (4) is introduced into the opened chamber (6) before the chamber (6) is closed and a negative pressure is produced in the chamber (6). A protective gas (16) is introduced into the chamber (6) via a gas flushing aperture (28), which gas flushing aperture (28) is located outside the packaging (4). When the protective gas (16) is introduced, such a concentration gradient of the protective gas is produced within the chamber (6) that the packaging opening (26) is located in the region of a peak of the concentration of the protective gas (26) within the chamber (6).

Description

[0001] Process for protective gassing of packaging and gassing station

[0002] The invention relates to a method for protective gassing of a packaging and to a gassing station configured to carry out the method.

[0003] Methods and devices are known from the prior art in which, in order to extend the shelf life of a product contained in the packaging, a protective gas is introduced into the packaging before the packaging is sealed with a top film. The protective gas is introduced through the space between a tray of the packaging and the top film. Such methods and devices are disclosed, for example, in DE2421531A1, DE102007047058A1, US5,271,207A, EP2668102B1, WO2011 / 124548A1, DE3130616A1 or US3,815,322. However, since these methods and devices require the protective gas to be introduced through a space between the tray and the lidding film, these conventional devices are unsuitable for protective gassing of packaging in which the tray is already covered by the lidding film and, in particular, sealed with it.

[0004] In contrast to the aforementioned methods, a method for inert gassing a package already sealed with a lidding film is proposed in EP1845807B1. In this method, the inert gas is introduced into the package via a cannula, which is pierced through the already sealed package. However, this approach has disadvantages: Firstly, the insertion of the cannula is only possible with comparatively small dimensions, which in turn impedes the flow of inert gas. Secondly, there is a risk that the cannula will damage the product already in the package.

[0005] In a deliberate departure from EP1845807B1, EP3846638B1 therefore discloses a different method for the protective gassing of already sealed packages, in which a negative pressure is first created in a vacuum chamber accommodating the package, in particular to remove water vapor from the package, whereby any residual oxygen present is also displaced from the package, before a protective gas is introduced from a storage container into the vacuum chamber - in the expectation that the protective gas will be sucked into the package through an opening in the latter. However, it has been shown that even with the modified method according to EP3846638B1, optimal protective gassing is not achieved. Another disadvantage is that significant product weight is lost due to evaporation. The object of the invention is to further improve the protective gassing of already sealed packages, in particular with regard to improved gas exchange within the package.

[0006] This object is achieved by a method having the features of claim 1 or claim 6 or by a gassing station configured to carry out the method. Advantageous developments of the invention are specified in the dependent claims.

[0007] In a first aspect of the invention, a method for protective gassing of a package in a gassing station is disclosed, wherein the package comprises a tray filled with a product. The tray is covered by a lidding film and sealed with the lidding film, in particular in a ring shape along an edge of the tray. The package has a packaging opening. This packaging opening can be located in the region of the tray, but is preferably located in the lidding film. The tray can optionally also have two or more packaging openings. The packaging opening allows gas exchange. The gassing station has a closable chamber. This means that the chamber is configured to be adjusted between an open state and a closed state, wherein in its closed state the chamber is in particular hermetically sealed from the environment of the gassing station.The procedure includes the following steps:.

[0008] Placing the packaging in the chamber in its opened state,

[0009] Closing the chamber around the packaging,

[0010] Creating a negative pressure in the chamber, and

[0011] Introducing protective gas into the chamber via a gassing opening, whereby the gassing opening is arranged outside the packaging.

[0012] In other words, a protective gas escapes from the gas inlet into the chamber's interior. The protective gas can be, for example, nitrogen (N2), oxygen (O2), or carbon dioxide (CO2).

[0013] According to the first aspect, when the protective gas is introduced inside the chamber, a concentration gradient of the protective gas is created such that the packaging opening is located in the area of ​​a peak in the concentration of the protective gas inside the chamber. Starting from an area around the packaging opening, the concentration of the protective gas inside the chamber decreases but outside the packaging. In conventional processes, the concentration of a protective gas in the chamber is generally highest in the area of ​​a chamber wall. The resulting unsatisfactory gas exchange inside the packaging could be caused by the fact that the gassing of the chamber in the conventional process led to flow conditions inside the chamber through which residual air (but not, or to a lesser extent, the protective gas) initially enters the suppressed packaging.The residual air that returned to the packaging then prevented the desired protective gas from entering. The invention avoids this disadvantage by creating a concentration gradient that reaches a maximum in the area of ​​the packaging opening. This measure ensures that primarily protective gas enters the packaging, thus optimizing gas exchange. Thus, with the invention, a kind of "bubble" of protective gas can form in the area of ​​the packaging opening, preventing the return of residual air with a lower concentration of protective gas from other areas of the chamber into the packaging.

[0014] Preferably, the packaging opening is located in the area of ​​the peak concentration of the protective gas within the chamber, not only at the beginning of the introduction of the protective gas, but also until the chamber returns to normal pressure. Normal pressure refers to the usual ambient pressure outside the gassing station, i.e., approximately 1 bar. This measure further improves gas exchange within the packaging, as the return of residual air into the packaging is further hindered.

[0015] A simple but effective measure for achieving the goal of locating the packaging opening in the area of ​​a peak in the protective gas concentration has proven to be to position the gassing opening at a maximum of 10 cm, preferably at a maximum of 6 cm, or more preferably at a maximum of 3 cm, from the packaging opening during the introduction of the protective gas. Alternatively or additionally, the gassing opening can be configured to direct the flow of the protective gas toward the packaging opening.

[0016] It is expedient if the gassing opening is at least 0.3 cm, preferably at least 0.5 cm, and more preferably at least 1 cm away from the packaging opening during the introduction of the protective gas. This prevents the risk of damage to the packaging during the introduction of the protective gas.

[0017] It can be advantageous to begin introducing the protective gas while the vacuum is being generated, meaning that the supply of protective gas is not initiated until the evacuation is already complete. This results in gas purging of at least the area of ​​the chamber around the packaging opening. During this gas purging, a gas flow is created in which protective gas is supplied and residual air is removed. Such flow conditions can further improve gas exchange in the packaging.

[0018] In a second aspect, a method for protective gassing a package in a gassing station is disclosed, wherein the package comprises a tray filled with a product, wherein the tray is covered by a lidding film and sealed with the lidding film, and wherein the package has a package opening. The package opening can be located on the tray or - preferably - in the lidding film. The package can have more than one package opening. The gassing station has a closable chamber, i.e. the chamber is adjustable between an open and a hermetically sealed position. The method comprises introducing the package into the chamber in its open state, closing the chamber around the package, generating a negative pressure in the chamber, and introducing protective gas into the chamber via a gassing opening, wherein the gassing opening is arranged outside the package.The process is characterized by the fact that the introduction of the shielding gas begins before the vacuum is created. This has the advantage of "gas flushing" the volume inside the chamber—that is, a potentially laminar flow is created, in which shielding gas is simultaneously supplied and residual air is removed from the chamber's interior.

[0019] The processes mentioned above and below are particularly advantageous in cases where the product is at a temperature above 50°C, preferably above 60°C, more preferably above 70°C, or generally at a temperature higher than ambient temperature (usually 23°C), at least at the start of the protective gas treatment. For this purpose, the protective gas treatment can be preceded by the process step of heating the product already in the packaging, for example, in a heating station located upstream of the gas treatment station, such as a microwave tunnel. This heating can lead to pasteurization of the product.

[0020] Advantages are particularly evident when the product contains moisture. In the context of the invention, moisture refers to the content of water and / or other liquids in the product material, for example simply the water content. With moist products, and in particular heated moist products, water vapor can form around the products. The method according to the invention has the advantage of minimizing or even completely preventing condensation of large quantities of water vapor that may have escaped from the packaging in the chamber during protective gas flushing. With a moist, i.e. water-containing product, it is advantageous if the desired negative pressure lies above a temperature-dependent evaporation point of the moisture. This measure reduces or even completely prevents the evaporation of moisture from the product.This has the advantage that the consistency, weight and texture of the product are retained and that a higher concentration of protective gas is achieved in the packaging, since the packaging is not filled with steam or is only filled to a very small extent.

[0021] With a view to greater processing efficiency or speed, it can be advantageous if two, three, four, or more packages are accommodated in the closed chamber, and the chamber also has at least an equal number of gas vents, so that each package is assigned exactly one or at least one gas vent. This allows multiple packages to be subjected to inert gas treatment simultaneously, increasing the number of packages treated per unit of time.

[0022] If two, three, or more packages are accommodated in the chamber, it is advantageous to create a concentration distribution of the protective gas within the chamber when introducing the protective gas such that each package opening of the number of packages is located in the area of ​​a (local) peak of the protective gas concentration within the chamber. This has the advantage that each package within the chamber is optimally gassed.

[0023] The gassing opening - or, if there are several gassing openings, either a majority or all of the gassing openings - can be located on a section of a gas supply line for the protective gas that projects from a chamber wall into the chamber. The line section forms, for example, a projection or a lance that projects from the chamber wall into the chamber. The chamber wall can be one or more side walls of the chamber or a cover wall of the chamber. The advantage of the line section projecting into the chamber is that it is possible to reduce the distance between the packaging opening and the gassing opening to a level that creates the desired concentration gradient of the protective gas when the protective gas is introduced into the chamber.

[0024] It is possible for the position of a gassing opening within the chamber to be adjustable to accommodate changing packaging geometries. For example, with a conduit section extending into the chamber, it would be possible to adjust the distance to which the conduit section extends from a chamber wall into the chamber. It has proven advantageous if the packaging opening and / or the at least one gassing opening have an area of ​​12 mm 2 up to 180 mm 2 preferably an area of ​​20 mm 2 up to 150 mm 2 If the respective opening is circular, this means an opening diameter of approximately 4 to 15 mm. Openings of this size allow for rapid gas exchange.

[0025] The desired negative pressure (i.e., the absolute value of the target pressure) can, for example, be in a range of 250 mbar to 750 mbar, preferably in the range of 250 mbar to 350 mbar. The advantage is that at these values, smaller amounts of moisture evaporate from the product than at lower pressures.

[0026] In a further aspect, a gassing station is disclosed, which has a chamber, wherein the gassing station is configured to carry out a method according to one or more of the variants explained above. The gassing station has one or more than one gassing opening, for example, two, three, or four gassing openings.

[0027] Each gassing opening can be located on a section of pipe extending from a chamber wall into the chamber. As explained above, a chamber wall in this regard is understood to mean a side wall or the top wall of the chamber.

[0028] In a further aspect, a packaging machine with a gassing station according to one of the variants explained above is disclosed. The packaging machine can be configured, for example, as a tray-sealing machine, a chamber machine, or a chamber-belt machine. A chamber-belt machine has a conveyor belt by means of which the packages are transported into and out of the gassing station.

[0029] In each of the variants of the method, the gassing station, or the packaging machine described above, the packaging opening can be sealed after the protective gas has been introduced into the package, for example, using an adhesive label. For this purpose, a labeler can be provided in the gassing station or downstream of the gassing station, which is configured to apply an adhesive label to the package that seals the packaging opening. The labeler can be arranged in the interior of the chamber of the gassing station.

[0030] In the following, exemplary embodiments of the invention are explained in more detail with reference to the drawings. In detail: Figure 1 shows a schematic representation of an exemplary embodiment of a gassing station,

[0031] Figure 2 is a schematic view of the chamber in a first variant of the gassing station,

[0032] Figure 3 is a schematic view of the chamber in a second variant of the gassing station.

[0033] Identical components are provided with the same reference numerals throughout the figures.

[0034] Figure 1 shows a packaging machine 1, which here is specifically designed in the form of a chamber belt machine 2. The chamber belt machine 2 has a conveyor belt 3 on which packages 4 can be transported in a transport direction 100. Furthermore, the chamber belt machine 2 has a gassing station 5 in which the package 4 can be evacuated (i.e., placed under negative pressure) and gassed with a protective gas.

[0035] The gassing station 5 has a chamber 6 that can assume an open and a closed state. For this purpose, the gassing station 5 comprises a chamber lid 7, which is, for example, hood-shaped and has side walls 8 and a lid wall 9. The chamber lid 7 is vertically movable between a raised and a lowered position in the direction indicated by the double arrow 200. In the raised position of the chamber lid 7, the chamber 6 is open and ready for the introduction of one or more packages 4 by means of the conveyor belt 3. In the lowered position of the chamber lid 7, the chamber lid 7, together with the conveyor belt 3, forms a chamber 6 in a state hermetically sealed from the surroundings of the gassing station 5. The chamber lid 7 and the conveyor belt 3 can be mounted on a frame 10 of the gassing station 5.

[0036] The gassing station 5 further comprises a vacuum source 11, for example a reservoir (under negative pressure) or a vacuum pump, which is connected to the chamber 6 via a vacuum line 12. A vacuum valve 13 is located in the vacuum line 12.

[0037] The gassing station 5 is further connected via a gas supply line 14 to a reservoir 15 for protective gas 16. The protective gas 16 can be, for example, nitrogen (N2). A gassing valve 17 is located in the gas supply line 14. Upstream of the gassing station 5, the packaging machine 1 can have further components, for example, a filling station 18 for filling the packages 4 with a product, a sealing station 19 for sealing the packages 4, and a heating station 20, for example, a microwave tunnel 20, for heating the product within the package 4.

[0038] Figure 2 schematically shows a cross-section through a first embodiment of the gassing station 5, viewed in (or opposite) the transport direction 100. In Figure 2, the chamber 6 of the gassing station 5 is in its closed position, in which the chamber lid 7, together with the conveyor belt 3, forms a hermetically sealed space. The hermetic seal is supported by seals 21 running along an outer edge of the chamber lid 7.

[0039] At least two packages 4 are located inside the chamber 6. However, there can also be only one package 4 or more than two packages 4 in the chamber 6, for example a number N of packages 4, where N is an integer. Each package 4 comprises a tray 22 filled with a product 23. The product 23 can be a moisture-containing product. The product 23 can be a food product. Each package 4 further has a lidding film 24. The lidding film 24 is sealed to the tray 22 along a peripheral edge 25 of the tray 22.

[0040] Each package 4 has a packaging opening 26. The packaging opening 26 can be provided on the tray 22, for example in an upper region of a side wall of the tray 22; however, the packaging opening 26 is preferably located (as shown) in the lidding film 24. The packaging opening 26 can, for example, have an area of ​​12 to 180 mm 2 The packaging opening 26 can be circular and have a diameter of 4 to 15 mm. The packaging opening 26 can be arranged in a central region of the lidding film 24.

[0041] Both the vacuum line 12 and the gas supply line 14 either form part of the gassing station 5 or are connected to it. In the chamber lid 7 - in the illustrated embodiment specifically in or on the lid wall 9 - a gas line 27 is connected to the gas supply line 14. The gas line 27 leads to one or more gassing openings 28 in the interior of the chamber 6. Expediently, (at least) as many gassing openings 28 are provided as the number of packages 4 that are to be supplied with protective gas 16 in one cycle in the chamber 6. In the exemplary embodiment, the gassing openings 28 are located at the distral end of line sections 29, which protrude from a chamber wall (here specifically from the lid wall 9) into the interior of the chamber 6, i.e. they protrude from the chamber wall.The gassing openings 28 are positioned such that, during operation of the gassing station 5, a distance A between the gassing opening 28 and the packaging opening 26 associated with it is a maximum of 10 cm, preferably a maximum of 6 cm, and more preferably a maximum of 3 cm. On the other hand, the distance A is at least 0.3 cm, preferably at least 0.5 cm, and more preferably at least 1 cm. The gassing opening 28 can have an area similar in size to the area of ​​the packaging opening 28, for example, also in the range of 12 mm. 2 up to 180 mm 2 . The line section 29 can be aligned such that the flow of the protective gas 16 conducted through the line section 29 is directed towards the packaging opening 26 of the packaging 4 associated with this gassing opening 28.

[0042] During operation of the gassing station 5 or the packaging machine 1 containing this gassing station 5, one or more packages 4 are brought into the interior of the chamber 6 when the chamber 6 is open, before the chamber 6 is brought into its closed position shown in Figure 2 by lowering the chamber lid 7. The interior of the chamber 6 is evacuated, i.e., placed under a negative pressure, via the vacuum line 12. The desired negative pressure can, for example, be set to a value in the range of 250 to 750 mbar. For evacuation, the vacuum valve 13 is opened.

[0043] After the evacuation is complete (i.e., upon or after the vacuum valve 13 is closed) or during the evacuation (i.e., with the vacuum valve 13 still open), the introduction of protective gas 16 from the reservoir 15 into the chamber 6 begins by opening the gassing valve 17. The protective gas 16 is distributed via the gas line 27 and flows out of the gassing openings 28 in the manner indicated by arrows. This creates a concentration gradient of the protective gas 16 within the chamber 6, with the concentration of the protective gas 16 between the gassing opening 28 and the packaging opening 26 being higher than in remote areas 61 of the chamber 6.This concentration gradient of the protective gas 16, at which the packaging opening 26 is located in the region of a maximum of the concentration of the protective gas 16 within the chamber 6, is achieved by the set, comparatively small distance A between the gassing opening 28 and the packaging opening 26, and is supported by the alignment of the line sections 29 with the packaging openings 26. The concentration gradient causes residual air to be further displaced from the edge regions 61 and primarily protective gas 16 to flow through the packaging opening 26 into the interior of the packaging 4 in order to compensate for the negative pressure prevailing there. A labeler 30 is shown schematically in Figure 2. This can be located inside the chamber 6 or outside the chamber 6. It is used to apply an adhesive label to the packaging 4 after the protective gas supply has ended, so that the adhesive label (not shown) seals the packaging opening 26 in a gas-tight manner.

[0044] As soon as or after the interior of the chamber 6 has reached normal pressure again by supplying protective gas 16, the chamber 6 is opened and the packages 4 are removed.

[0045] Figure 3 shows another embodiment of a gassing station 5 with a chamber 6. The vacuum line 12 is connected to the chamber 6 at an evacuation opening 40 (or a plurality of evacuation openings 40). The chamber 6 further comprises one or more gassing openings 28, through which protective gas supplied from the gas supply line 14 can be introduced into the chamber 6. The evacuation opening(s) 40 and the gassing opening(s) 28 are located at opposite positions in the chamber 6, specifically here on opposite side walls 8 of the chamber 6.

[0046] During operation of the gassing station 5 according to Figure 3, the chamber 6 is brought into its open state by lifting the chamber lid 7. In the open state of the chamber 6, one or more packages 4 are conveyed into the chamber 6, for example by means of a conveyor belt 3. As in the exemplary embodiment according to Figure 2, the packages 4 have a tray 22 filled with a product 23 and sealed with a lidding film 24, wherein a package opening 26 is provided in the lidding film 24.

[0047] After the packaging 4 has been introduced, the chamber 6 is closed by lowering the chamber lid 7. By opening the vacuum valve 13, the chamber 6 is evacuated by the vacuum source 11 sucking air out of the chamber 6. While the evacuation process is still in progress, i.e. while the vacuum valve 13 is open, the supply of protective gas 16 into the chamber 6 begins by opening the gassing valve 17. The protective gas 16 can be nitrogen, for example. The simultaneous evacuation and supply of protective gas 16 results in a "gas purging" of the chamber 6, during which the air or residual air in the chamber 6 is forced by the incoming protective gas 16 to one or more evacuation openings 40. Firstly, this measure accelerates the expulsion of residual air from the chamber 6.Secondly, it ensures that protective gas 16 primarily enters the packages 4 through the packaging openings 26 to compensate for the negative pressure prevailing there. This optimizes the protective gas flushing of the packages 4. In this exemplary embodiment, a labeler 30 can also be provided within the gas flushing station 5 or immediately downstream of it to seal the packaging openings 26 by applying adhesive labels after the protective gas flushing has been completed. In this embodiment, too, the target negative pressure can be set, for example, to a value in the range of 250 to 750 mbar.

[0048] Based on the illustrated embodiments, the invention can be modified in many ways. For example, the features of one or more claims can be used in each of the embodiments.

Claims

Claims 1 . A method for the protective gassing of a package (4) in a gassing station (5), wherein the package (4) comprises a tray (22) filled with a product (23), wherein the tray (22) is covered by a lidding film (24) and sealed therewith, and wherein the package (4) has a packaging opening (26), wherein the gassing station (5) further has a closable chamber (6), and wherein the method comprises the following steps: Inserting the packaging (4) into the opened chamber (6), Closing the chamber (6) around the packaging (4), Creating a negative pressure in the chamber (6), Introducing protective gas (16) via a gassing opening (28) into the chamber (6), wherein the gassing opening (28) is arranged outside the packaging (4), characterized in that when the protective gas (16) is introduced within the chamber (6), a concentration gradient of the protective gas (16) is generated such that the packaging opening (26) is located in the region of a peak of the concentration of the protective gas (16) within the chamber (6).

2. Method according to claim 1, characterized in that the packaging opening (26) is located in the region of a peak of the concentration of the protective gas (16) within the chamber (6) until normal pressure is reached again.

3. Method according to one of the preceding claims, characterized in that the gassing opening (28) is a maximum of 10 cm, preferably a maximum of 6 cm, more preferably a maximum of 3 cm away from the packaging opening (26) during the introduction of the protective gas (16).

4. Method according to one of the preceding claims, characterized in that the gassing opening (28) is at least 0.3 cm, preferably at least 0.5 cm, more preferably at least 1 cm away from the packaging opening (26) during the introduction of the protective gas (16).

5. Method according to one of the preceding claims, characterized in that the introduction of the protective gas (16) begins during the generation of the negative pressure.

6. A method for the protective gassing of a package (4) in a gassing station (5), wherein the package (4) comprises a tray (22) filled with a product (23), wherein the tray (22) is covered by a lidding film (24) and sealed with the lidding film (24), and wherein the package (4) has a packaging opening (26), wherein the gassing station (5) further has a closable chamber (6), and wherein the method comprises the following steps: Inserting the packaging (4) into the opened chamber (6), Closing the chamber (6) around the packaging (4), Creating a negative pressure in the chamber (6), Introducing protective gas (16) via a gassing opening (28) into the chamber (6), wherein the gassing opening (28) is arranged outside the packaging (4), characterized in that the introduction of the protective gas (16) begins during the generation of the negative pressure.

7. Method according to one of the preceding claims, characterized in that the product (23) is at a temperature of above 50°C, preferably at a temperature of above 60°C, more preferably at a temperature of above 70°C, at least at the start of the protective gassing.

8. Method according to one of the preceding claims, characterized in that the product (23) contains moisture.

9. Method according to one of the preceding claims, characterized in that a desired negative pressure is above a temperature-dependent evaporation point of the moisture of the product (23).

10. Method according to one of the preceding claims, characterized in that a number of two, three, four or more packages (4) are accommodated in the closed chamber (6) and the chamber (6) has at least as many gassing openings (28), so that each package (4) is assigned at least one gassing opening (28).

11. Method according to claim 10, characterized in that when the protective gas (16) is introduced within the chamber (6), a concentration distribution of the protective gas (16) is generated such that each packaging opening (26) of the number of packages (4) is located in the region of a peak of the concentration of the protective gas (16) within the chamber (6).

12. Method according to one of the preceding claims, characterized in that the one gassing opening (28) or each of the more than one gassing opening (28) is located on a line section (29) which projects from a chamber wall (8, 9) into the chamber (6).

13. Method according to one of the preceding claims, characterized in that the packaging opening (26) and / or the at least one gassing opening (28) has an area of ​​12 mm 2 up to 180 mm 2 preferably has an area of ​​20 mm 2 up to 150 mm 2 .

14. A gassing station (5) comprising a chamber (6), wherein the gassing station (5) is configured to carry out a method according to any one of the preceding claims.

15. Gassing station according to claim 14, wherein the one gassing opening (28) or each of the more than one gassing openings (28) is located on a line section (29) which projects from a chamber wall (8, 9) into the chamber (6).

16. Packaging machine (1) with a gassing station (5) according to one of claims 13 or 14, wherein the packaging machine (1) is configured as a tray sealing machine, as a chamber machine or as a chamber belt machine (2).

Images