Packaging, and sheet, coil of packaging material arranged to found

Abstract

There is provided a sheet of packaging material arranged for holding a package of a food product, the packaging material comprising an outer protective layer arranged to face the ambient environment, a cellulosic base layer, and an inner protective layer for preventing the food product from contacting the cellulosic base layer, the sheet comprising: at least one sealing portion arranged to form a fin of the package, wherein the sealing portion comprises an edge region arranged to form a peripheral fin edge of the package, the peripheral fin edge being formed by folding the different sides towards each other and sealing the different sides together, thereby forming the fin, the edge region being provided with a first weakening element and a second weakening element, the first and second weakening elements are placed on different sides of the peripheral fin edge at first and second lateral distances from the peripheral fin edge such that the material of the sheet is pushed away from the peripheral fin edge during folding, thereby obtaining a more reliable seal in the peripheral fin edge.

Description

Technical Field

[0001] The utility model relates to a packaging technology, and more specifically, to a cellulose-based packaging material sheet, a packaging material roll, a package, a method for producing the sheet, and a method for producing the package. Background Art

[0002] Roll-fed filling machines for producing carton-based packaging have been known since the 1940s. A well-known example currently available is the (Tetra )Sales A3 high speed machine (Tetra A3 Speed). The general principle of this machine is to form a tube from a web of packaging material, fill the tube with the food from above, and seal and cut the tube at the lower end to form the package. In addition to providing speed, by sterilizing the packaging material and treating the food, the package can have the ability to protect the food for a long period of time. For example, a roll-fed filling machine can be used to package UHT (ultra-high temperature) treated milk in an aseptic package.

[0003] As an alternative to a reel-fed filling machine, a blank-fed filling machine can be used. In contrast to a reel-fed packaging machine, a blank-fed packaging machine uses pre-made sleeves of flat, folded packaging material, usually called blanks. In such a machine, after the blanks have been removed from a magazine, they are laid upright to form a sleeve. In a bottom forming station, the sleeve is folded and sealed, thus forming the bottom. Downstream of this station, in a filling station, the food product is filled into the sleeve provided with the bottom. Once the food product has been filled into the package, the top part is formed by the top forming station. An example of such a blank-fed filling machine is the production of (Tetra )Packaging TR / 27(Tetra TR / 27).

[0004] In order to ensure that the package can be folded in a consistent and reliable manner, crease lines may be provided in the packaging material. Most commonly, the crease lines are formed so that portions of the packaging material are deformed between the male and female molds, causing the carton layer of the packaging material in these portions to be weakened. The effect of weakening the carton layer is that the fold can be directed to the portion having the deformed carton layer.

[0005] Different techniques for forming crease lines have been developed. For example, Tetra Laval Holdings & Finance SA in WO 2015 / 193358 A1 proposes a method of how crease lines can be provided in the corner area of ​​a package. In WO 2009 / 131496 A1, it is disclosed how internal creases on a packaging laminate can be used to reduce the risk of cracking of the aluminum foil layer during folding. In US 4,287,247, a packaging laminate with crease lines is also proposed, which can reduce the risk of cracks or leaks caused by folding. EP 0 027 668 also discloses a packaging laminate provided with crease lines, which are arranged to solve the problem of cracks caused during folding, in particular cracks that appear at the intersection between the transverse and longitudinal seals.

[0006] Although today's packaging materials provide the ability to form packages in a reliable and consistent manner, there is still room for improvement. For example, there is a need for a packaging material that can be easily folded into a package while keeping the risk of insufficient sealing of the peripheral edges of the transverse seals (i.e., the top fin and the bottom fin) at a low level. The packaging material can be folded, for example, by about 180 degrees. This may result in buckling of the cellulose-based (e.g., carton) layer, in other words, the cellulose-based layer becomes wavy. Buckling may result in such insufficient sealing. Utility Model Content

[0007] An object of the present invention is to at least partially overcome one or more of the above limitations of the prior art. In particular, an object of the present invention is to reduce the risk of insufficient sealing around the fins.

[0008] According to a first aspect, a sheet of packaging material is provided, the sheet of packaging material being arranged to hold a package of a food. The packaging material may include an outer protective layer arranged to face the surrounding environment, a cellulose base layer and an inner protective layer for preventing contact between the food and the cellulose base layer. The sheet may include at least one sealing portion arranged to be shaped as a fin of the package. The sealing portion may include an edge region arranged to be shaped as a peripheral fin edge of the package. The edge region may be provided with a first weakening element and a second weakening element, the first weakening element and the second weakening element being arranged on different sides of the peripheral fin edge at a first lateral distance and a second lateral distance from the peripheral fin edge, respectively.

[0009] The advantage of having a first weakening element and a second weakening element is that the material pushed towards the peripheral fin edge during folding is pushed out in the form of a bulge at the first weakening element and the second weakening element, respectively, instead of bulging at the peripheral fin edge. By moving the material away from the peripheral fin edge in this way, a more reliable seal can be obtained in the peripheral fin edge. Therefore, during folding, the bulge (including at least a part of the cellulose base layer) will not be located between the inner protective layers facing each other, and they can therefore be sealed to each other, thereby avoiding any unsealed channels between the facing and sealed inner protective layers.

[0010] The package can be formed by folding the packaging material, like a parallelepiped, or by not folding it, like a bag-type package. An essential feature is the presence of a sealing portion which enables the package to be sealed before and / or after the food product is filled.

[0011] The cellulose substrate can provide strength to the sheet and the package. It can be a paper layer, in particular a paperboard layer known in the field of liquid food packaging.

[0012] The inner and outer protective layers may be layers known in the art to protect the cellulose base from wetting, such as polymer layers extruded or laminated on one or both sides of the cellulose base. The number of protective layers may be one or more depending on the desired protection of the package.

[0013] The packaging material may comprise further layers besides the protective layer and the cellulose base layer.

[0014] The folding area between the first weakening element and the second weakening element may be free of a weakening element, in other words, the folding area between the first weakening element and the second weakening element may be formed without any weakening element.

[0015] By not having any weakening elements at the peripheral fin edges, a positive effect is achieved in that the risk of rupture of the packaging material, in particular of the "inner layer" on the side of the cellulose base layer facing the food when the package is formed and filled, is reduced due to the bulging effect of the weakening elements located on the fin edges.

[0016] Other weakening elements that are avoided may be any weakening in any direction, such as linear folds in the longitudinal or transverse direction.

[0017] The folding area can be defined not only as the area between the presence of the first weakening element and the second weakening element, but also between the protrusions, in particular the longitudinal protrusions (assuming continuation) of the first weakening element and the second weakening element. In this case, in the folding area, the packaging material may lack a transverse fold that may be present in the periphery of the first weakening element and the second weakening element of some types of packaging.

[0018] The weakening element mentioned in the present application may be at least one of a slit, a hole, a fold or a compression. The compression may be formed by forming a recess on the sheet. The recess may not result in any protrusion on the other side of the sheet.

[0019] All weakening types can be applied only on the cellulose base itself, or on any step of the lamination process and on any layer on the cellulose base. At the end of any alternative, the effect of having a weakening element on the cellulose base is valuable.

[0020] The first weakening element and the second weakening element, for example as a fold, can be provided by a female mold and a male mold. Thus, the transformation process of the packaging material can be facilitated compared to other types of weakening forming processes in the art. The cross section of the mold can be symmetrical, such as U-shaped, or asymmetrical, as explained later. The fold can have a concave portion on one side of the sheet and a protruding portion on the other side of the sheet.

[0021] If the packaging material is to be folded to form a package, the first and second weakening elements may be connected to any top flap fold lines and any bottom flap fold lines that may be present or separated therefrom. By being made connected or spaced apart, different designs can be achieved with the first and second weakening elements and the top and bottom flap fold lines, as long as the design covers the scope of the claims and is technically possible in the art. At least one sealing portion may include a top sealing portion and a bottom sealing portion, wherein the top sealing portion may include a first top fin edge area and a second top fin edge area, and the bottom sealing portion may include a first bottom fin edge area and a second bottom fin edge area.

[0022] The packaging material may further include a barrier layer positioned between the cellulose base layer and the inner protective layer.

[0023] The barrier layer may be more sensitive to stress and strain than the cellulose based layer and / or the protective layer.Therefore, having the first weakening element and the second weakening element may be particularly relevant if the packaging material comprises a barrier layer.

[0024] The barrier layer can be used to avoid spoilage of food stored in the package. For example, it can be an oxygen and / or light barrier layer. It can be one or more layers with the same or different barrier properties.

[0025] In one possible example, the barrier layer can be a fiber-based barrier layer (e.g., a paper-based barrier layer). The fiber-based barrier layer has a paper-based layer, which is provided with a coating having barrier properties, which is applied to the paper-based layer. The paper-based layer can be coated with an aqueous dispersion coating method, with a dispersion or solution of a composition that can provide a barrier to oxygen, water vapor, and / or further migrating substances. Examples of such compositions are aqueous compositions comprising vinyl alcohol polymers or starch or other polysaccharides, optionally also comprising fillers or layered mineral compounds, such as talc or bentonite or other clay minerals. Alternatively, or alternatively, the paper substrate layer can also be coated by a vapor deposition method, such as chemical vapor deposition and / or physical vapor deposition, and in a preferred embodiment, the paper substrate layer can be metallized, such as deposited with a metal (e.g., aluminum) coating that is only nanometer thick.

[0026] In another possible example, the barrier layer may be a polymer-based barrier layer. The polymer-based barrier layer may include: a single polymer layer having inherent gas barrier properties; or a layer having a polymer base layer with a coating having barrier properties, which is coated on the polymer base layer. The polymer base layer may be a prefabricated film having a single or multilayer structure, which is further coated by a deposition method such as chemical vapor deposition and / or physical vapor deposition in the same manner as described above for the fiber-based barrier substrate, for example, such a polymer barrier substrate may be metallized and / or deposited with an inorganic oxide, such as a metal oxide. Such polymer-based barrier layers are also considered difficult to punch or penetrate, and therefore require specific and powerful equipment.

[0027] Fiber-based or polymer-based barrier layers of this type are believed to be beneficial, in particular in the recycling cycle of packaging formed from the packaging material as claimed.

[0028] The distance between the first weakening element and the second weakening element can be 1-6mm. This distance can be defined according to the sheet thickness or the cellulose base thickness. In a possible embodiment, for a package with an internal volume of about 50-500ml, this distance can be about 2mm, or for a package with an internal volume of about 500-2000ml, it can be about 2.2mm. The intervals between the weakening elements can be between 5 times and 20 times the thickness of the cellulose base. Therefore, the risk of bulges can be avoided, thereby avoiding sealing problems.

[0029] The first and second weakening elements have an outer inclination angle that is steeper than the inner inclination angle; or an inner inclination angle that is steeper than the outer inclination angle. The advantage of having asymmetric first and second weakening elements is that the packaging material can be subjected to less stress and strain, while the risk of bulges in the peripheral fin edge can be kept low.

[0030] According to a second aspect, a packaging material roll is provided, which comprises a plurality of sheets trailing one after another, wherein the sheets are arranged according to the first aspect. Thus, a continuous roll of packaging material can be converted or produced in an efficient manner. There can also be further sheets underneath each other to form a multi-channel continuous roll of packaging material. This can make production more efficient. The production of packaging material can be carried out at a material flow speed of 200m / min or faster. Thus, a continuous and large-scale production of packaging material can be achieved.

[0031] The packaging material can be converted into a package in a filling machine for forming a package from a sheet according to the first aspect. The filling machine may include a transverse sealing station arranged to form a sealing portion into the fin of the package by folding the edge area of ​​the sheet into the peripheral fin edge and then sealing the sealing portion into the fin. The filling machine may be a roll-fed filling machine, in which the sheet is provided in the form of a coil according to the second aspect. Thus, continuous filling and package forming can be achieved. The transverse sealing station can use induction heating or ultrasonic heating to melt the inner protective layer of the sheet. Thus, different types of laminated layers, such as barrier layers can be used for the packaging material, while keeping the seal still possible.

[0032] According to a third aspect, a method for producing a sheet of packaging material is provided. The method may include attaching an outer protective layer and an inner protective layer to a cellulose base layer and deforming the cellulose base layer so that a first weakening element and a second weakening element are formed in an edge region of the sheet, wherein the first weakening element and the second weakening element may be arranged on different sides of the peripheral fin edge at a first lateral distance and a second lateral distance from the peripheral fin edge, respectively.

[0033] The same features and advantages as presented above in relation to the first aspect also apply to this aspect.

[0034] According to a fourth aspect, a method for producing a package from a sheet of packaging material is provided. An edge region of the sheet may be provided with a first weakening element and a second weakening element, the first weakening element and the second weakening element being provided on different sides of a peripheral fin edge at a first lateral distance and a second lateral distance from the peripheral fin edge, respectively. The method may comprise providing a sheet, and folding and sealing the sheet such that a fin is formed, wherein the first weakening element and the second weakening element cause a protrusion of the packaging material to be directed from the peripheral fin edge towards the first weakening element and the second weakening element, respectively.

[0035] The same features and advantages as presented above in relation to the first aspect also apply to this aspect.

[0036] According to a fifth aspect, there is provided a package obtainable by the method according to the fourth aspect.

[0037] Other objects, features, aspects and advantages of the present invention will become apparent from the following detailed description and the accompanying drawings.

[0038] All terms, such as transverse and longitudinal, refer to the production of packaging materials, wherein the direction of flow of the roll of cellulose substrate and / or sheet material defines the longitudinal direction and the direction orthogonal to the longitudinal direction defines the transverse direction. All terms, such as top or bottom, refer to the package formed by the packaging material, such that, if appropriate, the upper part of the package when standing on a surface is the top and the lower part resting on the surface is the bottom; or the part of the package filled with food is the top and the sealed part on the other side of the package is the bottom. In any case, the directional or relative terms used are those familiar to those skilled in the art of food packaging. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Embodiments of the present invention will now be described by way of example with reference to the accompanying drawings, in which

[0040] Figure 1 is a perspective view of a roll-fed filling machine.

[0041] Figure 2 A sheet of packaging material roll is shown without showing the present invention.

[0042] Figure 3 Is Figure 2 A perspective view of a package formed from the sheet is shown.

[0043] Figure 4 is a general illustration of how bulging occurs during folding of a sheet according to the prior art.

[0044] Figure 5 is a cross-sectional view of a peripheral fin edge of a package in which a bulge is formed due to the folding of the sheet according to the prior art.

[0045] Figure 6 is a general illustration of how the first weakening element and the second weakening element can mitigate the formation of bulges in a crease line.

[0046] Figure 7 is a cross-sectional view of a peripheral fin edge, wherein the first weakening element and the second weakening element are arranged such that a first offset edge protrusion and a second offset edge protrusion are formed.

[0047] Figure 8 Shows the application Figure 2 A crease line pattern of a packaging type in the embodiment of the present invention comprises a first weakening element and a second weakening element.

[0048] Fig. 9A cross-sectional view of a tool that may be used to provide the first weakening element and the second weakening element is shown.

[0049] Fig.10 is a flow chart illustrating a method of producing a sheet of packaging material.

[0050] Fig.11 is a flow chart illustrating a method of forming a package from a sheet of packaging material. DETAILED DESCRIPTION

[0051] Figure 1 The general principle of a roll-fed filling machine 100 is shown. Packaging material 102 can be provided in the form of a coil wound on a reel. After the coil is unwound from the reel, it can be sterilized (not shown), for example, by using a hydrogen peroxide bath or a low-pressure electron beam (LVEB) station to carry out. Except being sterilized, i.e. killing unwanted microorganisms from the packaging material 102, an opening device can be molded onto the packaging material 102, sometimes referred to as a pre-installed or pre-applied opening device (also not shown). The coil can be formed into a tube 104 by forming a longitudinal seal 106. This sealing can be provided by guiding the coil so that the first longitudinal edge 108 of the coil overlaps with the second longitudinal edge 110, generates heat so that the outer protective layer and the inner protective layer of the packaging material 102 are at least partially melted and pressure is applied so that bonding occurs between two edges 108, 110. As shown in the figure, the formation of the longitudinal seal 106 can be carried out continuously. Even though not shown, a so-called LS strip (longitudinal sealing strip) may be applied to the inside of the tube 104 so that contact between the food FP inside the tube 104 and the cellulose based layer of the packaging material 102 may be prevented.

[0052] The food FP can be provided into the tube 104 from above via the food pipe 112. In the lower end of the tube 104, a transverse seal 114 can be formed. While making the transverse seal 114, the tube 104 can be cut. In this way, the top fin of the first package and the bottom fin of the second package can be provided simultaneously, wherein the second package is after the first package. The transverse sealing and cutting can be carried out in the transverse sealing station 118, which is generally shown as a box shape. In order to generate heat during the sealing process, induction heating can be used. Another option is to use ultrasound to generate heat. Downstream of the transverse sealing station 118, the packages 116 can be folded into their final shape. For example, the panels and fins can be formed by the final folder, so that brick-shaped packages can be produced.

[0053] Instead of producing the package with the top pointing upwards and the bottom pointing downwards, the package can also be produced in the opposite direction, ie with the top pointing downwards and the bottom pointing upwards.

[0054] Although a roll-fed filling machine 100 is shown, there are other ways to produce the package 116. For example, a so-called blank-fed machine can be used. In these machines, the most common, the longitudinal seal 106 and the cut are pre-made, that is, not made in the filling machine. Therefore, the packaging material is provided in the form of a blank, i.e. a flat folded sleeve of the packaging material. Unlike the roll-fed filling machine 100, the top and bottom of the package are formed at different stations.

[0055] Figure 2 The packaging material 102 is shown in more detail. As shown, the packaging material web 102 can be divided into sheets 200, one of which produces one package 116. If a blank-fed filler is used instead of a roll-fed filler 100, the sheets 200 can be longitudinally sealed and folded flat.

[0056] A crease line 202 may be provided so that the sheet 200 may be conveniently folded into a package 116. The packaging material 200 may be a carton-based packaging material, more particularly a laminate comprising a polymer-based outer protective layer that is used to prevent moisture from reaching a carton base layer placed within the outer protective layer. The carton base layer or more generally a cellulose base layer is used for the purpose of providing firmness, but also reduces the environmental impact of the package 116. Since the carton may deteriorate over time if it comes into contact with a liquid (e.g., food FP), an inner protective layer may be provided so that the food FP held within the package 116 is prevented from coming into direct contact with the carton base layer. In most cases, not only one inner protective layer is used, but multiple layers are used, and multiple outer protective layers may be used in the same manner. A barrier layer may be added to block light from reaching the food FP held within the package 116. If the above-described carton-based packaging material 200 is used, a crease line 202 may be provided by deforming the carton at the crease line 202. By deforming the carton, the fibers are damaged, which causes these portions to be weakened, thereby facilitating folding.

[0057] Figure 2 The sheet 200 shown is an example of a sheet to be formed into a block package 116. A top flap fold line 202a is provided to facilitate forming a top fin to be folded down and bonded to the side panels of the package 116. In addition, a longitudinal main portion fold line 202b may be provided to facilitate forming a front panel, a side panel, and a back panel. A bottom flap fold line 202c may be provided to form a bottom fin. A cut line 204 may be provided between the edge regions 206a-206d of the continuous sheet 200.

[0058] As shown, a top seal portion 208 can be disposed in the upper portion of the sheet 200, and on the other side of the cut line 204, next to the top seal portion 208, a bottom seal portion 210 of the trailing sheet can be disposed. Below the top seal portion 208, a top portion 212 can be disposed. Further down, a main portion 214 can be disposed. Even further down, a bottom portion 216 can be disposed. Next to the bottom portion 216, the bottom seal portion 210 can be disposed.

[0059] Figure 3 It shows that Figure 2 The example of the package 116 formed by the sheet 200 shown. More particularly, the top 300 can be formed by the top portion 212, the main body 302 can be formed by the main portion 214, and the bottom 304 can be formed by the bottom portion 216. The longitudinal seal 306 can be arranged between the two rear panels of the package 116. Another option (although not shown) is to place the longitudinal seal in the corner area between the rear panel and one of the side panels. A transverse seal 308 with two peripheral fin edges 310 can be provided so that fins 312 are formed. Although not shown, in addition to the fins 312 shown (that is, top fins), bottom fins can also be provided. However, instead of folding the fins downward onto the side panels, the fins of the bottom fins can be folded inwards.

[0060] Problems that may occur when folding the packaging material 102 to form the peripheral fin edge 310 are, for example, Figure 4 As shown, a bulge 400 is formed on the inner side of the packaging material 102. When the two sides of the packaging material 102 are folded towards each other, as shown by the arrows, the material in the packaging material 102 moves towards the fold line, i.e. the peripheral fin edge 310 also shown by the arrows. The effect of the material being pushed towards the fold center is that the material is pushed out in the form of a bulge 400. As shown in the figure, if no crease line is provided, a bulge 400 may appear. In the case of a crease line for facilitating folding, this may further increase the risk of forming a bulge 400. The effect of a crease line may also be that the portion of the packaging material 102 at the peripheral fin edge 310 is weakened, thereby increasing the risk of material being pushed out in the form of a bulge 400. The meaning of the bulge 400 is that the transverse seal 308 is negatively affected, which in turn may lead to insufficient package integrity.

[0061] Figure 5An example of a peripheral fin edge 310 having a protrusion 400 formed therein is shown. In this particular example, the packaging material includes an outer protective layer 500, a cellulose base layer 502, more particularly a carton base layer, and an inner protective layer 504. As shown, the cellulose base layer 502 can produce the protrusion 400. One reason for this is that the cellulose base layer 502 is constructed in a different manner than the outer protective layer 500 and the inner protective layer 504, being polymer-based in this particular example.

[0062] like Figure 6 As shown, by placing the first weakening element 604 and the second weakening element 606 on either side of the peripheral fin edge 310, i.e. the fold center, the material pushed toward the fold center encounters portions of the packaging material 102 that have been deformed, i.e. the fibers have been damaged. As an effect of the weakening of the packaging material 102, the material pushed toward the fold center is redirected to the interior of the transverse seal 308, and as an effect, the first offset edge protrusion 600 and the second offset edge protrusion 602 are formed. Therefore, by having the first weakening element 604 and the second weakening element 606, less material is pushed toward the peripheral fin edge 310. One positive effect of this is that stress and shear forces in the peripheral fin edge 310 can be reduced, thereby reducing the risk of packaging material breakage. In addition, by having less material pushed into the peripheral fin edge 310, a more robust and reliable transverse seal can be achieved.

[0063] Figure 7 An example of a peripheral fin edge 310 is shown when the packaging material 102 used is provided with a first weakening element 604 and a second weakening element 606. Figure 5 Unlike the packaging material 102 shown, the packaging material 102 in this example includes an outer protective layer 500, a cellulose base layer 502, a barrier layer 506, and an inner protective layer 504. Although the principle of using the first weakening element 604 and the second weakening element 606 to provide the first offset edge protrusion 600 and the second offset edge protrusion 602 is also applicable Figure 5 The packaging material 102 is shown, but the principle may be more relevant for a packaging material 102 including an aluminum foil layer as a barrier layer, as this may be more susceptible to rupture due to stress or strain forces than, for example, the outer protective layer 500 and the inner protective layer 504.

[0064] In January 2023, when the inventors Figure 4 Reference packaging materials shown and Figure 6 When the packaging material according to the present invention is tested to seal a package with a volume of 1000 ml having an aluminum foil barrier layer, it can be seen that the problem of fin edge protrusion is reduced by about 37% for the present invention compared to the reference packaging material (Table 1).

[0065] Table 1

[0066]

[0067] Similar tests were also carried out on a package with a fiber-based barrier layer with a volume of 200 ml in April 2023. The results again showed a specific reduction in relation to this problem, e.g. no bulges on the inventive packaging material, but 12.5% ​​on the reference (Table 2).

[0068] Table 2

[0069]

[0070] Figure 8 A crease line pattern that can be used to provide a first weakening element 604 and a second weakening element 606 is shown. Figure 2 The crease line pattern of the sheet 200 shown is different. Figure 8 The crease line pattern shown includes a first weakening element 604 and a second weakening element 606 in a first bottom fin edge region 206c of one sheet and a first top fin edge region 206a of another trailing sheet. In the first bottom fin edge region 206c, a first folding region 800 may be provided. In the first top fin edge region 206a, a second folding region 802 may be provided. As shown, the first folding region 800 and the second folding region 802 may be free of creases. By omitting crease lines in these regions, the risk of damaging the packaging material 102 may be reduced.

[0071] The first weakening element 604 may be placed at a first lateral distance TD1 from the peripheral fin edge 310, and the second weakening element 606 may be placed at a second lateral distance TD2 from the peripheral fin edge 310. In other words, the first weakening element 604 and the second weakening element 606 and the top flap crease line 202a and the bottom flap crease line 202c may be spaced apart, respectively.

[0072] like Fig. 9 As shown, the first weakening element 604 and the second weakening element 606 can be provided in the packaging material 200 by using a tool including a female mold 900 and a male mold 902. As shown, the external inclination angle OS-A and the internal inclination angle IS-A can be different. More particularly, the internal inclination angle IS-A can be steeper than the external inclination angle OS-A. Alternatives are also possible. This means that the external inclination angle OS-A can be steeper than the internal inclination angle IS-A (not shown).

[0073] Fig.101 is a flow chart illustrating a method 1000 for producing a sheet 200 of a packaging material 102. The method includes attaching 1002 an outer protective layer 500 and an inner protective layer 504 to a cellulose base layer 502, and deforming 1004 the cellulose base layer 502 such that a first weakening element 604 and a second weakening element 606 are formed in edge regions 206a-206d of the sheet 200. The first weakening element 604 and the second weakening element 606 may be placed on different sides of the peripheral fin edge 310 at a first lateral distance TD1 and a second lateral distance TD2, respectively, from the peripheral fin edge.

[0074] Fig.11 A method 1100 of producing a package 116 from a sheet 200 of packaging material 102 is shown, wherein edge regions 206a-206d of the sheet 200 are provided with first and second weakening elements 604, 606, which are placed at different sides of a peripheral fin edge 310 at a first transverse distance TD1 and a second transverse distance TD2, respectively, from the peripheral fin edge. The method may include providing 1102 the sheet 200, folding and sealing 1104 the sheet 200 such that a fin 312 is formed, wherein the first and second weakening elements 604, 606 are such that a protrusion of the packaging material 102 is directed from the peripheral fin edge 310 towards the first and second weakening elements 604, 606, respectively.

[0075] In known solutions, the problem of cracks in the foil or other layers of packaging material with low ductility has been mitigated by adding crease lines to reduce stress in the packaging material, thereby reducing the risk of cracks and lack of package integrity caused by these cracks. For example, in order to reduce stress on the low ductility layer of the packaging material, it is known to add crease lines to treat the intersection of the package where the longitudinal and transverse seals meet.

[0076] As mentioned above, with the method proposed herein, the purpose of the first weakening element 604 and the second weakening element 606 is to provide material to be removed from the peripheral fin edge 310, so that there is a risk that excess material (e.g., material from the inner protective layer of the packaging material) may form a bulge 400, so that the sealing quality is affected. Figure 5 As shown, by having excess material in the peripheral fin edge 310, there is a risk of an inadequate seal, thereby causing leakage of the package due to the inadequate seal and failure to shield the food product held in the package from the surrounding environment.

[0077] From the above description, although various embodiments of the invention have been described and shown, the invention is not restricted thereto but may also be implemented in other ways within the scope of the subject matter defined in the following claims.

Claims

1. A sheet (200) of packaging material (102), characterized in that: The sheet material (200) is arranged as a package (116) for holding a food (FP), the packaging material (102) comprising an outer protective layer (500) arranged to face the surrounding environment, a cellulose base layer (502) and an inner protective layer (504) for preventing the food (FP) from contacting the cellulose base layer (502), the sheet material (200) comprising: at least one sealing portion (208, 210) arranged to be formed as a fin (312) of the package (116), wherein the sealing portion (208, 210) comprises an edge region (206a-206d) arranged to be formed as a peripheral fin edge (310) of the package (116), wherein the peripheral fin edge (310) is formed by folding different sides toward each other and sealing the different sides together to form a fin (312), The edge region (206a-206d) is provided with a first weakening element (604) and a second weakening element (606), and the first weakening element and the second weakening element are placed on different sides of the peripheral fin edge (310) at a first lateral distance (TD1) and a second lateral distance (TD2) from the peripheral fin edge (310), so that the material of the sheet (200) is pushed away from the peripheral fin edge (310) during the folding process, thereby obtaining a more reliable seal in the peripheral fin edge (310).

2. The sheet material (200) according to claim 1, wherein the folding area (800, 802) between the first weakening element (604) and the second weakening element (606) is free of weakening elements.

3. The sheet material (200) according to claim 1 or 2, wherein the first weakening element (604) and the second weakening element (606) are at least one of a slit, a hole, a fold or a compression.

4. A sheet material (200) according to claim 1 or 2, wherein the at least one sealing portion (208, 210) includes a top sealing portion (208) and a bottom sealing portion (210), wherein the top sealing portion (208) includes a first top fin edge area (206a) and a second top fin edge area, and the bottom sealing portion (210) includes a first bottom fin edge area (206c) and a second bottom fin edge area.

5. The sheet material (200) according to claim 1 or 2, wherein the packaging material (102) further comprises a barrier layer (506) disposed between the cellulose-based layer (502) and the inner protective layer (504).

6. The sheet material (200) according to the preceding claim 1 or 2, wherein the distance between the first weakening element (604) and the second weakening element (606) is 1-6 mm.

7. The sheet material (200) according to claim 1 or 2, wherein the first weakening element (604) and the second weakening element (606) are provided by using a tool, the tool comprising a female mold (900) and a male mold (902), the tool having an external inclination angle (OS-A) that is steeper than an internal inclination angle (IS-A).

8. The sheet material (200) according to claim 1 or 2, wherein the first weakening element (604) and the second weakening element (606) are provided by using a tool, the tool comprising a female mold (900) and a male mold (902), the tool having an internal inclination angle (IS-A) that is steeper than an external inclination angle (OS-A).

9. A coil of packaging material (102), characterized in that: The coil comprises a plurality of sheets (200) trailing one after the other, in which a sheet (200) according to any one of the preceding claims is arranged.

10. A package (116), characterized in that: The package (116) is obtained from a sheet (200) according to any one of claims 1-8.

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