Multilayer sheet of packaging material to produce a sealed package

Abstract

A multilayer sheet of packaging material (M) for producing a sealed container (1) of a pourable food product comprises: at least a base layer (10) for imparting rigidity; a plurality of lamination layers (11) applied to and covering both sides of said base layer (10); a pre-laminated opening (12) formed by a through-slot provided in said base layer (10) and covered by one or more of said lamination layers (11), said pre-laminated opening (12) being configured to receive an opening device for pouring the pourable food product; a plurality of fold lines (15) configured to define a rim between two adjacent walls of a sealed container, wherein the pre-laminated opening (12) is not intersected by any of said fold lines (15) and includes an outer arc-shaped rim for defining a first portion of a first circumference.

Description

Multilayer sheet of packaging material to produce a sealed package Technical field The present invention relates to a multilayer sheet packaging material for producing pourable sealed food product containers. As is well known, many pourable food products, such as fruit juice, UHT (ultra-high temperature treated) milk, wine, tomato sauce, etc., are sold in containers made of sterilized packaging material. A typical example is the rectangular container for liquid or pourable food products known as Tetra Brik Aseptic (registered trademark), which is manufactured by folding and sealing a laminated strip packaging material. The packaging material has a multi-layered structure comprising a base layer, for example, paper, covered on both sides with layers of heat-sealable plastic material, for example, polyethylene.In the case of aseptic packaging for long-term storage products, such as UHT milk, the packaging material also comprises a layer of oxygen barrier material, for example, an aluminum foil, which is overlaid on a layer of heat-sealable plastic material and which, in turn, is covered with another layer of heat-sealable plastic material that forms the inner face of the packaging that finally comes into contact with the food product.Packaging of this type is normally produced on fully automatic packaging machines, in which a continuous tube is formed from the packaging material using a web feed; the web of packaging material is sterilized in the packaging machine, for example, by applying a chemical sterilizing agent, such as a hydrogen peroxide solution, which, once sterilization is complete, is removed from the surfaces of the packaging material, for example, by evaporating through heating; the web sterilized in this way is then kept in a closed, sterile environment, and folded and sealed lengthwise to form a tube, which is fed vertically.To complete the forming process, the tube is filled with the sterilized or sterile-processed food product, sealed, and then cut along equally spaced cross-sections. This creates pillow-shaped packages, which are then mechanically folded to form the finished containers. Alternatively, the packaging material can be cut into blanks, formed into packages on forming screws, and then filled with the food product and sealed. An example of this type of packaging is the so-called "gable-top" carton, known by the trade name Tetra Rex (registered trademark). To open the aforementioned containers, they are typically provided with a detachable section, which is partially separated from the rest of the packaging material (M) by an opening device to create a pouring opening through which the product is poured. The detachable section is formed into the packaging material before the material is folded and sealed to form the finished container. The removable portion typically comprises what is termed a "pre-laminated" hole, i.e., a hole formed through the base layer of the packaging material only and covered, when the material is laminated, with layers of heat-sealable plastic material and barrier material, which adhere to each other at the hole. The "pre-laminated" hole is normally circular, although other shapes may be provided for, as described in patent documents EP2287082A1 and EP3260386A1 issued to Tetra Laval and patent document EP0577867A1. Typically, the container comprises an opening device consisting of a frame, which defines a nozzle and fits around the detachable portion of the container; a detachable cap, screwed to the outside of the frame to close the nozzle; and a substantially tubular, cylindrical cutting element, screwed inside the frame and configured to break the detachable portion during the first opening of the container. Such opening devices are typically made of plastic. Recently, research has focused on reducing plastic consumption in order to increase the sustainability of packaging. Specifically, the research focuses on providing reusable opening devices that can be used multiple times on various containers. In this case, the containers do not come with an opening device already attached. The end consumer must first apply the opening device to the container, then extract the liquid product, and once the container is empty, remove the opening device for reuse on another container. Therefore, there is a perceived need to provide a container suitable for receiving a reusable opening device. Specifically, there is a perceived need for a container with a pre-laminated opening that securely holds a reusable opening device, preventing any liquid product from dripping down the container during dispensing. Furthermore, there is a perceived need to provide a container that has a pre-laminated opening to receive a reusable opening device in which the pre-laminated opening can be cleanly cut by the cutting element of the opening device, without fraying that interferes with the pouring of the food product. Furthermore, there is a perceived need to provide a container that has a pre-laminated opening to receive a reusable opening device in which the pre-laminated opening does not inadvertently break during storage and transport of the container. Disclosure of the invention Therefore, an objective of the present invention is to provide a multilayer sheet of packaging material for producing sealed pourable food containers that overcomes one or more of the aforementioned drawbacks. Furthermore, an objective of the present invention is to provide a sealed pourable food container that overcomes one or more of the aforementioned drawbacks. These objectives are fully achieved by means of the multi-layer sheet of packaging material and by means of the sealed packaging according to the attached claims. Brief description of the drawings Two non-limiting embodiments of the present invention will be described by way of example, with reference to the accompanying drawings, in which: Figure 1 illustrates a cross-sectional view of a multilayer sheet of packaging material according to this disclosure; Figure 2A illustrates a sealed container according to an embodiment of the present disclosure; Figure 2B illustrates a multilayer sheet of packaging material for producing the sealed package of Figure 2A; Figure 2C illustrates an enlarged detail of Figure 2B; Figure 3A illustrates a sealed container according to an embodiment of the present disclosure; Figure 3B illustrates a multilayer sheet of packaging material for producing the sealed package of Figure 3A; Figure 3C illustrates an enlarged detail of Figure 3B; Figure 4A illustrates a sealed container according to an embodiment of the present disclosure; Figure 4B illustrates a multilayer sheet of packaging material for producing the sealed package of Figure 4A; Figure 4C illustrates an enlarged detail of Figure 4B; Figure 5A illustrates a sealed container according to an embodiment of the present disclosure; Figure 5B illustrates a multilayer sheet of packaging material for producing the sealed package of Figure 4A; Figure 5C illustrates an enlarged detail of Figure 5B; Figure 6A illustrates a sealed container according to an embodiment of the present disclosure; Figure 6B illustrates a multilayer sheet of packaging material for producing the sealed package of Figure 6A; Figure 6C illustrates an enlarged detail of Figure 6B; Figures 7-9 illustrate respective details of a multilayer sheet of packaging material according to further embodiments of this disclosure. Figure 10 illustrates an embodiment that is not included within the scope of the claims. Best ways to carry out the invention Number 1 indicates, as a whole, a sealed container for pourable food products, made of multilayer foil packaging material M, and designed to receive an opening device for extracting the pourable food product. In particular, the sealed container 1 is designed to receive a reusable opening device on a top or upper wall of the container 1. Preferably, the opening device includes a cutting element configured to break a pre-laminated opening 12 to define a pouring opening. By way of example only, the opening device is of the type described in EP3260386A1. It should also be noted that other opening devices may be used. In particular, a reusable opening device may be used, which can be applied to the sealed container by the end consumer and removed once the container is empty, so that it can be applied to another container. Container 1 can be a rectangular or prism-shaped container, or a gable-top container. According to a non-limiting embodiment, container 1 has the rectangular shape described in WO2015 / 169656A1. With reference to 2A, 3A, 4A, 5A, and 6A, container 1 comprises a quadrilateral-shaped (particularly rectangular or square) upper wall 5, a quadrilateral-shaped (particularly rectangular or square) lower wall 6, and four side walls 7 extending between the upper wall 5 and the lower wall 6. The opening device is configured to be applied to the upper wall 5. Preferably, container 1 comprises a transverse sealing line 8 across the upper wall 5 and an additional transverse sealing line, not visible in the figures, across the lower wall 6. Preferably, container 1 comprises a longitudinal sealing line 9 perpendicular to the transverse sealing line 8. The packaging material M for producing the sealed package 1 has a multi-layer structure comprising at least one base layer 10, for example, made of paper, configured to impart rigidity, and multiple lamination layers 11 applied to, and covering, both sides of the base layer 10. In the example shown, the lamination layers 11 include a layer 11a made of oxygen barrier material, for example, an aluminum foil, and a series of layers 11b of heat-sealable plastic material covering both sides of the base layer 10 and layer 11a. In other words, the packaging material comprises, in succession and from the side that ultimately forms the inside of the package 1, a layer 11b of heat-sealable plastic material, a layer 11a of oxygen barrier material, another layer 11b of heat-sealable plastic material, a base layer 10, and another layer 11b of heat-sealable plastic material. The inner layer 11b of heat-sealable plastic material that comes into contact with the food product during use can be made, for example, of rigid linear low-density polyethylene (LLD), in particular, high-stretch, metallocene-catalyzed. Typically, the 11b layers of heat-sealable plastic material are laminated onto the base layer 10 and / or the 11a layer of oxygen barrier material in a molten state, with successive cooling. As a possible alternative, at least the inner 11b layers of plastic material can be provided as prefabricated films, which are laminated onto the base 10 layer and / or the 11a layer of oxygen barrier material; this technique allows reducing any risk of holes or cracks forming in or around the detachable part during forming operations to produce the sealed container 1. Preferably, said plurality of lamination layers 11 includes at least a first lamination layer applied to a first side of the base layer 10 and a second lamination layer 11 applied to a second side of the base layer 11. For example, the first lamination layer may include said oxygen barrier layer 11a and / or a heat-sealable plastic layer 11b; the second lamination layer may include another heat-sealable plastic layer 11b. At the pre-laminated opening 12, the first lamination layer and the second lamination layer are sealed to each other. Figures 2B, 3B, 4B, 5B, 6B show a basic unit of packaging material M, with which packaging 1 is produced, and which can be a pre-cut blank, or a part of a strip of packaging material M comprising a succession of units. In the first case, the basic unit is folded on a known folding spindle (not shown), filled with the food product, and sealed at the top to form the container 1. In the second case, the strip of packaging material, comprising a succession of basic units, is folded on a cylinder to form a vertical tube; it is continuously filled with the food product; and it is transversely sealed and cut into basic units, which are then folded to form respective containers 1. Said packaging material M comprises multiple crease lines 15 configured to define a border between two adjacent walls of the sealed package 1 formed by folding and sealing the packaging material M. In particular, each basic unit of packaging material M has a crease pattern, i.e., a series of crease lines 15 along which the packaging material M can be folded to form the finished package 1. Preferably, the crease lines 15 are obtained by pressing the base layer 10 between a pair of tools so that the base layer 10 is locally deformed, before mating the base layer 10 with the lamination layers 11. In the example shown, the fold pattern comprises first fold lines, which extend horizontally, second fold lines, which extend vertically (i.e., perpendicular to the first fold lines), and third fold lines, inclined (at an acute angle) with respect to the first and second fold lines. The fold lines 15 define, in a known manner, the edges between the various walls of the formed container 1. The packaging material M further comprises a pre-laminated opening 12 formed by a through-slot provided in the base layer 10 and covered by one or more of the lamination layers 11. The pre-laminated opening 12 is configured to receive an opening device (in particular, a reusable opening device) for extracting the pourable food product from the container 1. The pre-laminated opening 12 is configured to be broken by a cutting element of the opening device to define a pouring opening. In particular, under the action of a cutting element of the opening device, the detachable portion can be partially separated from the rest of the packaging material M to define the pouring opening. Preferably, the pre-laminated opening 12 is formed in the packaging material M before the packaging material M is folded and sealed to form the package 1. Preferably, none of the fold lines 15 intersect the pre-laminated opening 12. In other words, the fold lines 15 are at a distance from the pre-laminated opening 12. Consequently, in the formed package 1, the pre-laminated opening 12 is entirely contained within the top wall 5 and does not extend into any of the side walls 7. Preferably, the pre-laminated opening 12 includes an outer flange 120 extending between a first end 120a and a second end 120b away from the first end 120a. The outer flange 120 is arc-shaped (or curved) to define a first part C11 of a first circumference C1. The curved arc shape of the outer edge of the pre-laminated opening serves as a guide for rotating the cutting element of the opening device during its insertion through the opening, thus defining a pouring hole. This rotation of the cutting element precisely controls the tearing of the pre-laminated opening, ensuring the opening device adheres firmly to the packaging material M. Furthermore, the fact that the first end 120a is offset from the second end 120b, such that the outer flange defines only a portion of a circumference, helps prevent small pieces of the packaging material M from falling into the container during the insertion of the opening device. In one or more embodiments, illustrated in Figures 2C, 3C, 4C, 5C, 6C, 10, the first end 120a and the second end 120b of the outer flange 120 are located along the first circumference C1. In this way, the first part C11 of the first circumference C1 is defined (or extends) between the first end 120a and the second end 120b of the outer flange 120, that is, from the first end 120a to the second end 120b of the outer flange 120. In other embodiments, illustrated in Figures 7, 8, 9, the first end 120a and / or the second end 120b of the outer flange 120 are located outside the first circle C1. In these cases, the outer flange 120 extends partly along the first circle C1 and partly outside the first circle C1. Preferably, the multilayer sheet of packaging material M comprises a line of weakness 13 in said base layer 10. Preferably, the line of weakness 13 extends from the pre-laminated opening 12. In particular, the line of weakness 13 extends from the first end 120a and / or the second end 120b of the outer flange 120 of the pre-laminated opening 12. Preferably, the line of weakness 13 extends at least partially along a second part C12 of the first circumference C1. Preferably, the first part C11 of the first circumference C1 (including the outer flange 120) does not overlap with the second part C12 of the first circumference C1 (including the line of weakness 13). According to some embodiments, the first part C11 of the first circumference C1 (including the outer rim 120) is longer than the second part C12 of the first circumference C1 (including the line of weakness 13). According to some other embodiments, the first part C11 of the first circumference C1 (including the outer rim 120) is shorter than the second part C12 of the first circumference C1 (including the line of weakness 13). According to some non-limiting embodiments, the first circumference C1 includes: the first part C11, which has the outer rim 120 of the pre-laminated opening 12, the second part, which has the line of weakness 13, and a third part that is free from both the outer rim 120 of the pre-laminated opening 12 and the line of weakness 13. According to some non-limiting embodiments illustrated in Figures 2C and 6C, the base layer 10 is at least partially cut along the line of weakness 13. In particular, the line of weakness 13 has a depth in the base layer 10 that is less than the thickness of the base layer 10. In particular, the base layer 10 has cut perforations along the line of weakness 13. According to some non-limiting embodiments illustrated in Figures 3C, 7, and 9, the base layer 10 is marked with a fold line along the line 13 of weakness. Preferably, the marking with a fold line defining the line 13 of weakness is obtained by pressing the base layer 10 between a pair of tools so that the base layer 10 is locally deformed, before mating the base layer 10 with the lamination layers 11. The line of weakness 13 provides a guide for the opening device during the first opening of package 1. Specifically, the opening device is inserted through the pre-laminated opening 12, breaking the lamination layers 11 covering it to form the pouring hole. Furthermore, the pouring hole is enlarged by also breaking the base layer 10 along the line of weakness 13. In this way, the formation of the pouring hole is precisely controlled, and its final size and shape are accurately predictable. As a result, the opening device will adhere firmly to the packaging material M. According to one or more embodiments, illustrated in Figures 2C, 3C, 4C, 5C, 6C, 7, 8, 9, the prelaminated opening 12 includes an arc-shaped inner rim extending along a second circumference C2. The second circumference C2 is smaller than the first circumference C1. The prelaminated opening 12 is bounded at least partially by the inner rim of the second circumference C2 and by the outer rim 120 of the first circumference C1. Preferably, the first circle C1 and the second circle C2 have a common center. Therefore, the inner rim of the second circle C2 and the outer rim of the first circle C1 are parallel to each other. In other embodiments, the first circle C1 and the second circle C2 have different centers, so that the inner rim of the second circle C2 and the outer rim of the first circle C1 are not parallel to each other. In these embodiments, the pre-laminated aperture 12 is C-shaped. Therefore, the pre-laminated aperture 12 partially surrounds a central portion of the base layer. The C-shape is particularly useful for providing enhanced robustness to the pre-laminated aperture 12, preventing it from inadvertently breaking during transport. According to an alternative embodiment illustrated in Figure 10 and not included within the scope of the claims, the pre-laminated opening 12 is delimited by the outer arc-shaped flange 120, which extends along the first part C11 of the first circumference C1 from the first end 120a to the second end 120b, and by a line connecting the first end 120a to the second end 120b inside the first circumference C1. Preferably, the line of weakness 13 extends along the first circumference C1 in the second part C12, which does not have the outer flange 120. According to one or more embodiments, the packaging material M includes an additional pre-laminated opening (not shown in the figures) formed by an additional through-slot provided in the base layer 10 and covered by one or more of the lamination layers 11. The additional pre-laminated opening is configured to receive a straw connected to the opening device. The straw is configured to allow air to escape from the container 1 during the removal of the liquid food product through the pre-laminated opening and the opening device attached thereto. Preferably, the additional pre-laminated opening 12 is shaped as a circle. Preferably, the pre-laminated opening 12 and the additional pre-laminated opening are located in an area of ​​the sheet not intersected by any fold line 15; consequently, the pre-laminated opening 12 and the additional pre-laminated opening are both included in the upper wall 5 of the formed container 1. According to one embodiment, shown in Figure 8, the packaging material M includes an additional pre-laminated opening 16 formed by an additional through-slot provided in the base layer 10 and covered by one or more of the lamination layers 11. The additional pre-laminated opening 16 cooperates with the pre-laminated opening 12 to surround the central portion of the base layer 10 (which is useful for providing improved robustness to the pre-laminated opening 12). Preferably, the pre-laminated opening 12 and the additional pre-laminated opening are located in an area of ​​the sheet not intersected by any fold line 15; consequently, the pre-laminated opening 12 and the additional pre-laminated opening are both included in the upper wall 5 of the formed package 1. It should be noted that the additional pre-laminated opening 16 can be provided in combination with, or in addition to, the additional pre-lamination opening configured to receive the straw.

Claims

1. A multilayer sheet of packaging material (M) for producing a sealed container (1) for a pourable food product, wherein said packaging material (M) comprises: - at least one base layer (10) for imparting rigidity; - multiple lamination layers (11) applied to, and covering both sides of, said base layer (10); - a pre-laminated opening (12) formed by a through-slot provided in said base layer (10) and covered by one or more of said lamination layers (11), wherein said pre-laminated opening (12) is configured to receive an opening device for extracting the pourable food product; - multiple fold lines (15) configured to define a rim between two adjacent walls of a sealed container formed by folding and sealing the packaging material (M), wherein the pre-laminated opening (12) is not traversed by any of said fold lines (15),wherein the pre-laminated opening (12) includes an outer flange (120) extending between a first end (120a) and a second end (120b) located away from the first end (120a), wherein the outer flange (120) is arc-shaped to define a first part (C11) of a first circumference (C1), wherein the pre-laminated opening (12) includes an inner arc-shaped flange extending along a second circumference smaller than the first circumference, characterized in that the pre-laminated opening (12) is C-shaped.

2. Multilayer sheet of packaging material (M) according to claim 1, wherein the first end (120a) and the second end (120b) of the outer flange (120) are located along the first circumference,such that said first part of the first circumference is defined from the first end (120a) to the second end (120b) of the outer flange (120).

3. Multilayer sheet of packaging material (M) according to claim 1 or 2, further comprising a line (13) of weakness in said base layer (10), wherein the line (13) of weakness extends from the pre-laminated opening (12).

4. Multilayer sheet of packaging material (M) according to claim 3, wherein the line (13) of weakness extends from the first end (120a) and / or the second end (120b) of the outer flange (120) of the pre-laminated opening (12).

5. Multilayer sheet of packaging material (M) according to claim 3 or 4, wherein the line (13) of weakness extends along a second part (C12) of the first circumference (C1).

6. Multilayer sheet of packaging material (M) according to claim 5,wherein the first part (C11) of the first circumference (C1) is as long as, or longer than, the second part (C12) of the first circumference (C1).

7. Multilayer sheet of packaging material (M) according to claim 5 or 6, wherein the first circumference (C1) includes: the first part (C11), which has the outer rim (120) of the pre-laminated opening (12), the second part (C12), which has the line (13) of weakness, and a third part which is free from both the outer rim (120) of the pre-laminated opening (12) and the line (13) of weakness.

8. Multilayer sheet of packaging material (M) according to any one of claims 3 to 7 above, wherein the base layer (10) is at least partially cut along said line (13) of weakness.

9. Multilayer sheet of packaging material (M) according to claim 8,wherein the line (13) of weakness has a depth in said base layer (10) that is less than a thickness of the base layer (10).

10. Multilayer sheet of packaging material (M) according to claim 8 or 9, wherein the base layer (10) has cut perforations along said line (13) of weakness.

11. Multilayer sheet of packaging material (M) according to any one of claims 3 to 10 above, wherein the base layer (10) is marked with a fold line along said line (13) of weakness.

12. Multilayer sheet of packaging material (M) according to any one of the preceding claims, wherein said plurality of lamination layers (11) includes a first lamination layer applied to a first side of the base layer (10) and a second lamination layer (12) applied to a second side of the base layer (11).wherein in the pre-laminated opening (12) the first lamination layer and the second lamination layer are sealed together.

13. Sealed container for pourable food products, formed by folding and sealing a packaging material (M) according to any one of the preceding claims, and configured to receive an opening device for extracting the pourable food product, wherein the pre-laminated opening (12) is configured to be broken by a cutting element of the opening device, to define a pouring opening.

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