Packaging materials and their manufacturing processes

Abstract

There is provided a packaging material comprising a core layer (201, 201', 401, 501), an outermost layer (202, 202', 402, 502) arranged to face the outside of a packaging container made of the packaging material (200, 200', 400, 500), and an innermost layer (203, 203', 403, 503) arranged to face the inside of the packaging container. The outermost layer (202, 202', 402, 502) and the innermost layer (203, 203', 403, 503) are laminated to the core layer (201, 201', 401, 501). The laminated packaging material (200, 200', 400, 500) further includes locally distributed heat-sealable material portions (204, 204', 404, 504) disposed on the innermost layer (203, 203', 403, 503).

Description

[Technical field]

[0001] The present invention relates to packaging materials, in particular to laminated packaging materials and methods for producing laminated packaging materials.

[0002] Additionally, the present invention relates to a packaging container made from the laminated packaging material. [Background technology]

[0003] Carton-based packaging for liquid food products is well known. For example, Tetra Brik® packaging is used for milk, juice and other beverages in many parts of the world. There are several reasons why carton-based packaging is gaining popularity. For example, the environmental benefits of the packaging, which is made mainly from renewable materials, and the efficient logistics of brick-shaped packaging are some of the reasons why consumers choose carton-based packaging instead of plastic bottles. Another reason for the popularity of carton-based packaging is that the packaging machines that make the packaging are robust and cost-effective compared to other alternatives, and the total cost of running a carton-based packaging machine is very competitive.

[0004] Packaging containers for pourable food products must have some barrier properties so that the filled, unopened packaging container can be properly stored. The shelf life required and the type of barrier required depend on the type of food product, the type of packaging material, the type of packaging container, the type of opening device for the packaging container, etc., as well as the aseptic regime and intended storage conditions. Generally, some degree of oxygen barrier is required in all cases.

[0005] The packaging material is made by laminating multiple polymer layers to a core material layer of carton or paperboard. The polymer layers typically protect the core material layer made of carton or paperboard from the liquid contents of the resulting packaging container and the moist external environment. As the packaging material manufacturing process improves in terms of speed and quality, and is improved and developed so that the polymer layers are laminated in even thinner layers, it becomes possible to reduce the total amount of polymer material for the laminated layers of the packaging material. However, the inner polymer layer is also used to seal the packaging material when the independent packaging container is formed and filled. The general desire to reduce the inner polymer layer thickness of the packaging material is therefore incompatible with the requirement to have a sufficiently thick polymer layer to ensure proper sealing of the packaging material.

[0006] Therefore, there is a need for improved packaging materials that ensure robust sealing while still allowing the total amount of polymer layer material to be reduced. Summary of the Invention [Problem to be solved by the invention]

[0007] It is an object of the present invention to at least partially overcome one or more of the above identified limitations of the prior art. [Means for solving the problem]

[0008] To achieve these objectives, a packaging material for liquid food products is provided, the packaging material comprising a core layer, an outermost layer arranged to face the exterior of a packaging container made of the packaging material, and an innermost layer arranged to face the interior of the packaging container, the outermost layer and the innermost layer being laminated to the core layer, the laminated packaging material further comprising a locally applied heat sealable material portion disposed on the innermost layer.

[0009] The heat-sealable material portion may be positioned in a sealing area that corresponds to the location of a transverse seal in the resulting package.

[0010] The heat-sealable material portion may be adhered to the innermost layer by a heat application process.

[0011] The heat application process may be an injection molding process, a sintering process, a welding process, a thermal spraying process, an inkjet type polymer printing process or a 3D printing process.

[0012] The heat-sealable material portion may have a cross-section that has an increasing width towards its base at the innermost layer, ie, the substrate surface.

[0013] The heat-sealable material portion may have a cross-section having the shape of a triangle or a truncated triangle. Alternatively, the heat-sealable material portion may have a cross-section having the shape of a circle or the top of a semicircle.

[0014] The heat-sealable material portion may have a cross-section having an asymmetric shape.

[0015] The portions of heat-sealable material may be arranged to have a varying cross-section along the extension of the transverse sealing region.

[0016] The heat-sealable material portion may have a cross-section that provides a greater amount of polymeric material at a given location along the extension of the transverse sealing area, in particular such a cross-section may have a wider base, a greater width towards the innermost layer and / or a steeper slope towards the highest point or apex of the cross-section.

[0017] The heat-sealable portion may be applied only in some portions along the extension of the transverse sealing area or along the entire extension of the transverse sealing area.

[0018] The heat-sealable material portion may have an enclosed cavity, i.e., may be hollow inside.

[0019] The thickness of the heat-sealable material portion may be from 2 to 50 μm, preferably from 3 to 30 μm, for example from 3 to 20 μm or from 5 to 20 μm, most preferably from 5 to 15 μm.

[0020] The heat-sealable material portion may be made of a thermoplastic material, for example a thermoplastic polymer.

[0021] The thermoplastic polymer may be selected from the group consisting of polyolefins and polyesters.

[0022] The thermoplastic polymer may be selected from the group consisting of polyethylene, polypropylene, polyethylene terephthalate (PET), polyethylene furanoate (PEF), polylactic acid polymer or copolymer (PLA), polyhydroxyalkanoate (PHA), and blends or copolymers of two or more thereof.

[0023] The thermoplastic polymer of the locally applied heat sealable material portion may be selected from the group consisting of low density polyethylene LDPE, high density polyethylene HDPE, linear low density polyethylene LLDPE or single-site catalyzed linear low density polyethylene m-LLDPE, very low density polyethylene (VLDPE), ultra low density polyethylene (ULDPE) and blends and copolymers of two or more thereof.

[0024] The thermoplastic polymer may be a biodegradable polymer selected from the group consisting of polylactic acid polymers or copolymers (PLA), polyhydroxyalkanoates (PHAs), cellulose or cellulose derivatives and blends or copolymers of two or more thereof. Examples of PHAs are poly-3-hydroxybutyric acid (PHB), polyhydroxyvaleric acid (PHV) and polyhydroxycaproic acid (PHH), among others.

[0025] The portion of heat-sealable material may be disposed along the entire extension of the transverse sealing area or partially along the extension of the transverse sealing area.

[0026] The portions of heat-sealable material may be arranged to have a varying cross-section along the extension of the transverse sealing region.

[0027] The packaging material may further include a shielding layer disposed between the core layer and the innermost layer.

[0028] The shielding layer may be an aluminum foil or a metallized aluminum layer. The shielding may alternatively be a non-aluminum foil ("non-foil") shielding such as a vapor deposition coating of an inorganic oxide, a metal oxide or diamond-like carbon (DLC), such as a dispersed coating layer of polyvinyl alcohol (PVOH), ethylene vinyl alcohol (EVOH), starch or a starch derivative, cellulose or a cellulose derivative (e.g., micro / nano fibrous cellulose), or a polymeric shielding such as polyamide or ethylene vinyl alcohol (EVOH).

[0029] The core layer may be a cellulosic material, such as paper or paperboard.

[0030] According to a second aspect, there is provided a method for making a packaging container using a laminated packaging material, the method comprising the steps of laminating an innermost layer and an outermost layer to a core layer or providing a laminated packaging material having an innermost layer and an outermost layer laminated to a core layer, locally heat applying a portion of heat-sealable material to the innermost layer, forming an open-ended packaging container from the packaging material, filling the packaging container through the open end, and heat-sealing the packaging container with the portion of heat-sealable material to form a closed packaging container.

[0031] The step of applying heat may be carried out using an injection molding process, a sintering process, a welding process, a thermal spraying process, an inkjet-type polymer printing process, a compression molding process or a 3D printing process. Preferred heat application processes are injection molding, such as high-pressure micro-injection molding, inkjet-type polymer printing and 3D printing, because these processes allow the shaping of the final shape of the locally applied heat-sealable material part in a better way. High-pressure micro-injection molding is the most preferred process, because it allows a faster heat application and requires a very small amount of polymer, thus being suitable for high-speed packaging processes in filling and packaging machines.

[0032] The innermost layer may be a heat-sealable polymer, preferably a thermoplastic polymer selected from polyolefins such as polyethylene and polyester.

[0033] The innermost layer may be a heat-sealable thermoplastic polymer selected from the group consisting of polyethylene, polypropylene, polyethylene terephthalate (PET), polyethylene furanoate (PEF), polylactic acid polymer or copolymer (PLA), polyhydroxyalkanoate (PHA), and blends or copolymers of two or more thereof.

[0034] The innermost layer may be a heat-sealable thermoplastic polymer selected from the group consisting of polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET), polyethylene furanoate (PEF), and any blend or copolymer of one or more thereof. The innermost layer may be a thermoplastic polymer selected from the group consisting of polyethylene (PE) or polyethylene terephthalate (PET), and the material of the heat-sealable material portion may be polyethylene (PE).

[0035] The thermoplastic polymers of the innermost layer and the locally applied heat sealable material portion may be the same or different types of polymers.

[0036] The innermost layer may comprise a thermoplastic polymer selected from the group consisting of low, medium and high density polyethylene (LDPE, MDPE, HDPE), linear low density polyethylene and single-site or metallocene catalyzed linear low density polyethylene (LLDPE, m-LLDPE) and polypropylene (PP), and blends and copolymers of two or more thereof.

[0037] The material of the heat sealable material portion may comprise a thermoplastic polymer selected from the group consisting of high / medium density polyethylene (HDPE, MDPE), low density polyethylene (LDPE), linear low density polyethylene (LLDPE, m-LLDPE) and blends and copolymers of two or more thereof.

[0038] The thermoplastic polymer of the innermost layer may be selected from the group consisting of low density polyethylene LDPE, high density polyethylene HDPE, linear low density polyethylene LLDPE or single-site catalyzed linear low density polyethylene m-LLDPE and blends and copolymers of two or more thereof. The seal initiation temperature, i.e. softening temperature, e.g. Vicat point or glass temperature (Tg), of the thermoplastic polymer of the locally applied heat-sealable material portion may be lower than or equal to the corresponding seal initiation temperature of the thermoplastic polymer of the innermost layer. The seal initiation temperature of the thermoplastic polymer of the locally applied heat-sealable material portion may be 4K, e.g. 5K, e.g. 10K lower than the respective or corresponding temperature of the innermost layer.

[0039] The melting temperature (Tm) of the thermoplastic polymer of the locally applied heat sealable material portion may be equal to or lower than the corresponding melting temperature of the thermoplastic polymer of the innermost layer. The melting temperature of the thermoplastic polymer of the locally applied heat sealable material portion may be 4K, such as 5K, such as 10K, lower than the melting temperature of the innermost layer. The heat sealable material portion may be applied such that the cross section has an increasing width towards the innermost layer. In an embodiment, the locally applied heat sealable material portion has a triangular cross section or a cross section having a truncated triangular shape. The triangular or truncated triangular cross-sectional configuration of the locally applied heat sealable material portion provides an optimal heat sealing operation in terms of operating efficiency, amount of material used and strength of the resulting heat seal joint.

[0040] The heat-sealable material portion may have a cross-section having the shape of a triangle or a truncated triangle. Alternatively, the heat-sealable material portion may have a cross-section having the shape of the apex of a circle or a semicircle.

[0041] The heat-sealable material portion may have a cross-section having an asymmetric shape.

[0042] The portions of heat-sealable material may be arranged to have a varying cross-section along the extension of the transverse sealing region.

[0043] The heat-sealable material portion may have a cross-section that provides a greater amount of polymeric material at a given location along the extension of the transverse sealing area. In particular, such a cross-section may have a wider base, an increased width toward the innermost layer, and / or a steeper slope toward the highest point or apex of the cross-section.

[0044] The heat-sealable portion may be applied only in some portions along the extension of the transverse sealing area or along the entire extension.

[0045] The heat-sealable material portion may have an enclosed cavity, i.e., a hollow structure.

[0046] According to a third aspect, there is provided a packaging container made of a packaging material comprising a core layer and an outermost layer and an innermost layer laminated thereto, wherein a portion of heat-sealable material is locally disposed on the innermost layer.

[0047] Still other objects, features, aspects and advantages of the present invention will become apparent from the following detailed description and drawings.

[0048] Embodiments of the present invention will now be described, by way of example, with reference to the accompanying schematic drawings, in which: [Brief description of the drawings]

[0049] [Figure 1] FIG. 1 is a schematic diagram of the principle of a packaging machine for continuous roll-fed packaging of liquid food products. [Figure 2a-b] 1A-1D are cross-sectional views of packaging materials according to different embodiments. [Figure 3a] FIG. 2 is a plan view of a packaging material according to one embodiment. [Figure 3b] FIG. 3b is an isometric view of a package formed from the packaging material shown in FIG. 3a. [Figure 4a-c] Three stages of an injection molding process for providing a portion of heat-sealable material to the innermost layer of a packaging material according to one embodiment are described. [Figure 5a-c] 1 illustrates three stages of an injection molding process for providing a portion of heat-sealable material to an innermost layer of a packaging material, according to one embodiment. [Figure 6] 1 is a flow chart of a method for making packaging material. [Figure 7a-d] A further alternative to the cross-sections in Figures 4c and 5c is shown. [Figure 8a] 1 shows a cross section of a prior art folded and formed tube that is to be transversely sealed from a conventional laminated packaging material. [Figure 8b-c]Instead, a variation of the cross section of a folded tube is shown having only a very thin layer of heat-sealable material on the inside of the laminated packaging material, and in addition having a locally applied portion of heat-sealable material applied along at least some portions of the extension of the transverse seal area. [Figure 9] 1 shows the transverse sealing area viewed from above on the inside of a web of flat packaging material. [Figure 10] 1 shows an isometric view along an extension of a transverse seal area with a locally applied portion of heat sealable material. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0050] Starting from Figure 1, the basic principle of a roll-fed carton-based packaging machine is shown. The packaging machine is designed for the continuous packaging of liquid food products and the like, and forms the general technical concept used for a variety of different packaging systems, for example the commercially successful Tetra Brik® packaging system. The packaging machine receives packaging material 100 either in the form of a continuous web (as shown in Figure 1).

[0051] After the packaging material 100 is unwound from the reel 110, its longitudinal side edges 101a-b are brought together to form a longitudinal seal LS, thereby also forming a continuous tube 140 of packaging material 100. More specifically, the longitudinal side edges 101a-b are attached to one another in a continuous overlapping manner. The tube 140 is filled with a desired product, preferably a liquid food product, from a filling pipe 150.

[0052] A series of packages 160 are formed from the tube 140 by making transverse seals TS at the ends of the tube 140 and severing the sealed portions, such that as they are formed, each sealed portion represents an independent package 160. To form the packages 160, different forming tools may be used during the transverse sealing operation or a separate forming process may be performed after the transverse sealing is performed.

[0053] Alternatively, a blank-fed packaging machine is used: a blank in the form of a pre-cut piece of packaging material, two ends of which are welded together to form a folded and sealed tubular sleeve, is fed to the filling machine. The blank is erected in the open sleeve and then folded and sealed to form a closed top or bottom. This is then filled with the product, sealed and folded at the open end to obtain a filled packaging container.

[0054] FIG. 2a shows a cross-section of a laminated packaging material 200 according to one embodiment. It comprises a bulk or core layer 201, which may be a fiber-based material, for example a cellulosic material. The bulk layer may comprise a cellulosic material, for example paper or paperboard. The laminated packaging material 200 further comprises an outermost layer 202 on the outside of the bulk layer 201. The outermost layer 202 is thus configured to face the outside of the package 160 formed from said laminated packaging material 200. The outermost layer 202 is preferably a protective thermoplastic polymer layer that acts as a barrier against liquids and also has thermoplastic properties for heat sealing purposes. In addition, the laminated packaging material 200 in FIG. 2a comprises an innermost layer 203 on the inside of the bulk or core layer 201. The innermost layer 203 is thus configured to face the inside of the package 160 made from the laminated packaging material 200 and to be in direct contact with its contents, for example milk, juice or other food products. The innermost layer 203 is conventionally a heat-sealable material portion, and when the two surfaces of the innermost layer 203 of the laminated packaging material 200 are placed in direct contact with each other, compressed and heated, they at least partially melt and adhere to each other to form a strong bonded seal. This is what happens when forming the transverse seal TS described with reference to FIG. 1. The innermost layer 203 can be a heat-sealable polymer, preferably a thermoplastic polymer selected from polyolefins, such as polyethylene and polyester. The innermost layer 203 may be formed from the group consisting of polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET), polyethylene furanoate (PEF) and any blend or copolymer of one or more thereof. The innermost layer 203 also has liquid barrier properties to provide a liquid-tight layer towards the filled liquid food product. The packaging material 200 in FIG. 2a further comprises a locally applied portion 204 of a heat-sealable material disposed on top of one or more portions of the innermost layer 203. The topically applied heat sealable portion 204 may also include a heat sealable thermoplastic polymer selected from polyolefins such as polyethylene or polypropylene and polyesters such as polyethylene terephthalate (PET) or polyethylene furanoate (PEF).In an embodiment, the innermost layer and the locally applied heat sealable material comprises polyethylene, such as low density polyethylene LDPE, high density polyethylene HDPE, linear low density polyethylene LLDPE or single-site catalyzed linear low density polyethylene m-LLDPE or blends or copolymers thereof.

[0055] Figure 2b shows yet another embodiment of a cross-section of a laminated packaging material 200'. Similar to the laminated packaging material 200 in Figure 2a, the packaging material 200' in Figure 2b includes a bulk layer 201', an outermost layer 202', an innermost layer 203' and a heat-sealable material portion 204'. In addition, the packaging material 200' may further include a shielding layer 205', such as an aluminum foil or a thin metallized aluminum layer, laminated between the innermost layer 203' and the bulk or core layer 201'. The cross-sections in Figures 2a and 2b are in a direction perpendicular to the longitudinal extension of the transverse seals TS and / or sealing elements 204, 204'. This is further illustrated below with reference to Figure 3.

[0056] The laminated packaging material 200, 200' shown in Figures 2a and 2b provides a layer that acts as a liquid-tight and gas barrier. The laminated packaging material 200, 200' may include additional plastic layers or other barriers (not shown) on either side of the bulk layer 201, 201'.

[0057] It should be noted that the dimensions of the heat-sealable material portions 204, 204' are exaggerated for illustrative purposes. The width of the heat-sealable material portions 204, 204' should be selected to provide sufficient sealing in the longitudinal direction of the package 160, while the length of the heat-sealable material portions 204, 204' should be selected to extend along the entire sealing of the package 160. The thickness of the heat-sealable material portions 204, 204' should be selected to provide sufficient bonding and may be 5 to 50 μm, such as 5 to 30 μm, for example 5 to 20 μm.

[0058] FIG. 3a shows a laminated packaging material 300 that will be folded, formed, and sealed into a package 160. The inner surface of the innermost layer 303 of the packaging material 300 is shown. The particular transverse seal areas TSA of the innermost layer 303 of the packaging material 300 are the portions of the transverse seals TS that will be formed when making the package 160. These areas TSA are shown by dotted areas in FIG. 3a. The dotted areas TSA extend in the transverse direction (TD) indicated by the arrows in FIG. 3a, and the heat sealable material portions 304 are applied to the transverse seal areas TSA of the packaging material 300. The packaging material 300 is provided with creases that indicate where the packaging material 300 will be folded to form the package 160, as shown in FIG. 3b. FIG. 3b shows a flat-top package 160 made of the disclosed laminated packaging material 200, 200'. The package 160 includes a longitudinal seal LS and two transverse seals TS (only the top transverse seal TS is shown). It includes an outermost surface 302, a corner 306 and a bottom side edge 307. The package shown in FIG. 3b is a flat-top package, but it should be understood that the package material 200, 200' of the present invention is applicable to any type of package having a transverse seal TS. When providing a thin liquid barrier layer by the package material before forming the package 160, it must be ensured that a sufficient liquid barrier effect is obtained in all the different parts of the package 160. The thickness of the innermost layer 203, 203' forming the transverse seal TS needs to be thick enough to provide the desired seal. However, it has been found that applying a continuous thick innermost layer 203, 203' of a thermoplastic polymer that is a heat-sealable plastic is expensive and in practice requires more of such thermoplastic polymer than is actually required for heat-seal performance and for the integrity of the resulting package.

[0059] The inventors have therefore surprisingly discovered that it is sufficient and resource-conserving, i.e. saving the total raw thermoplastic polymer amount, to not only reduce the total thickness of the innermost layer 203, 303', but instead provide the laminated packaging material 200, 200' with heat-sealable material portions 204, 204' applied locally to specific areas of the innermost layer 203, 203' of the packaging material, as shown, for example, in Figures 2a and 2b. The heat-sealable material portions 204, 204' are what will become the seals, e.g. the transverse seals TS, of the formed packaging, providing a sufficient amount of thermoplastic polymer material to obtain a robust seal. In this way, less material can be used for the innermost layer 203, 203', forming a thinner innermost layer 203, 203' and thereby a more environmentally sustainable packaging. In addition, the production costs can also be reduced, since less material is used for the innermost layer 203, 203. Additional amounts of topically applied thermoplastic polymer may be applied to areas of the packaging where additional protection and mechanical properties may be needed, such as corner folding areas and areas where the laminated packaging material will be folded multiple times over one another (e.g., under the bottom flap and TS folds).

[0060] Since the heat-sealable material portions 204, 204' are applied non-uniformly on the laminated packaging material 200, 200', they may preferably be provided to the packaging material 200, 200' after the packaging material 110, 300 has been made. The process of forming the laminated packaging material 100, 200, 200' without the heat-sealable material portions 204, 204' is carried out through a well-known manufacturing process, a conversion that includes a so-called lamination operation. The bulk layer 201, 201', the innermost layer 203, 203' and the outermost layer 202, 202' and optionally a barrier layer 205', such as an aluminum foil or a metallized film or other layer providing an oxygen barrier and additional laminations, are laminated together during the conversion process. The thickness of the innermost layer 203, 203' may be in the range of 1 to 50 μm, 2 to 50 μm, preferably 2 to 40 μm, 2 to 30 μm, 3 to 30 μm, 3 to 20 μm, 5 to 20 μm, 3 to 15 μm, 5 to 15 μm.

[0061] Exemplary configurations of heat-sealable material portions 204, 204', 404 using injection molding are shown in Figures 4a-4c. To form the heat-sealable material portions 204, 204', 404 into the innermost layer 203, 203', 403 of the laminated packaging material 110, 300, an injection molding unit 40 is used prior to forming the package 160.

[0062] 4a-c, a first example of how a heat-sealable material portion 404 can be formed through an injection molding process is shown. The laminated packaging material 400 in this example includes a bulk layer 401, an outermost layer 402 and an innermost layer 403. In a first step, shown in FIG. 4a, a molten plastic material 410, e.g., polyethylene, is transferred into a cavity 412 formed between a first mold 414 and a second mold 416.

[0063] In a second stage of this example shown in FIG. 4b, the molten plastic material 410 heats the innermost layer 403 such that it at least partially melts, as shown by the dotted areas representing solid material being replaced by dashed areas representing molten material.

[0064] In a third stage of this example shown in Figure 4c, the plastic material 410 and the innermost layer 403 have both solidified and the first mould 414 and the second mould 416 have been removed. At this stage, the heat-sealable material portion 404 has been formed. The heat-sealable material portion 404 and the innermost layer 403 are bonded together due to the innermost layer 403 having at least partially melted during the injection moulding of the heat-sealable material portion 404.

[0065] The heat-sealable material portion 404 shown in Fig. 4c has a rectangular cross-section. However, in some embodiments, it may be preferred to provide the heat-sealable material portion 404 to have an increasing width towards the base and substrate, i.e. the innermost layer, i.e. to have a triangular cross-section or a cross-section having the shape of a truncated triangle as shown in Figs. 5a-c. This is preferred because when the material 404 of the heat-sealable portion is brought together to form a seal, a continuously increasing pressure is obtained. This therefore prevents the polymer from flowing outside the transverse seal area TSA.

[0066] In addition, a larger interface area between the heat-sealable material portion 404 and the innermost layer 403 is achieved using a shape of the heat-sealable material portion 404 having an increasing width towards the innermost layer 403. By providing a cross-section perpendicular to the transverse direction TD of the heat-sealable material portion 404 or having a truncated triangular shape, more thermal energy is directed to the interface, thereby improving the bonding of the heat-sealable material portion 404 to the innermost layer 403. This is shown in Figures 5a-c.

[0067] 5a-c, the laminated packaging material 500 comprises a bulk layer 501, an outermost layer 502 and an innermost layer 503. In a first stage shown in FIG 5a, a molten plastic material 510, e.g. PE, is transferred into a cavity 512 formed between a mould 514 and the innermost layer 503.

[0068] In a second stage, shown in Figure 5b, the molten plastic material 510 heats and at least partially melts the innermost layer 503. This is shown by the dashed lines and dotted areas in the same manner as in Figure 4b.

[0069] In a third stage, shown in Figure 5c, the plastic material 510 and the innermost layer 503 have both solidified and the mould 514 has been removed. The heat-sealable material portion 504 has been formed.

[0070] It should be noted that the heat-sealable material portions 404, 504 in Figures 4a-c and 5a-c are not to scale.

[0071] To promote successful bonding between the innermost layer 203, 403, 503 and the heat sealable material portion 204, 404, 504, the interface between the innermost layer 203, 403, 503 and the heat sealable material portion 204, 404, 504 should have the desired temperature for as long as possible. A cross-section having a triangular or truncated triangular shape prevents the heat sealable material portion 204, 404, 504 from flowing outside the transverse seal area TSA, since the bonding of the heat sealable material portions 204, 404, 504 to form a seal creates increased pressure. The cross-section also creates a larger surface area at the interface between the two surfaces than a rectangular shape of the cross-section, when the same volume of material is used to form the sealing element 204, 404, 504.

[0072] 6 shows a block diagram of a method 600 for forming a laminated packaging material 200, 200', 400, 500 including one or more heat-sealable material portions 204, 204', 404, 504 according to one embodiment. The method includes providing a laminated packaging material 100, 300, such as the web shown in FIG. 1. The laminated packaging material 100, 300 may be made in a conversion process using a conversion process as disclosed, for example, in EP 3409462 A1 or WO 2018220134 A1 by the same applicant.

[0073] The provided packaging material 100, 300 produced in the converting process is unwound from its roll 110 and placed 620 in a heat sealable material portion forming station 40, 50 to form the heat sealable material portion 204, 404, 504. The station 40, 50 is located inside or just before entering the filling machine. The station 40, 50 may be an injection molding station as shown in Figures 4a-c and 5a-c, or it may be a thermal spray station, an inkjet type polymer printing station, a sintering station, a welding station or a 3D printing station.

[0074] Optionally, the laminated packaging material 100, 300 is placed 630 in contact with at least one mold 414, 416, 514. The mold 414, 416, 514 may have various shapes and form heat-sealable material portions 204, 204', 404, 504 of different geometric shapes. The mold 414, 416, 514 may have a cross section perpendicular to the extension of the sealing element 204, 204', 404, 504 that is, for example, triangular, rectangular, hemispherical or has a truncated triangular shape. Preferably, said cross section has an increasing width towards the innermost layer, as shown in Figures 5a-b.

[0075] The heat-sealable material portion 204, 204', 404, 504 is then formed 640 by applying a heat-sealable material 410, 510 to the innermost layer 203, 203', 403, 503 of the laminated packaging material 110, 300. Optionally, the heat-sealable material 410, 510 is applied by injecting the material into the cavity 412, 512 of the mold 414, 416, 514 shown in Figures 4a-c and 5a-c. The heat-sealable material 410, 510 may be a liquid or solid material. For example, it may be a molten material used during injection molding, thermal spraying, coating or during an inkjet process, or it may be a powder that is applied to the innermost layer 203, 203', 403, 503 and sintered to adhere to the innermost layer 203, 203', 403, 503.

[0076] Injection molding is a well-established technique for some of the proposed materials, namely PE, PP and PET, among others. When using high-pressure micro-injection molding to produce only small devices from these materials on advancing packaging laminate materials in a filling and packaging machine, a first mold half with a first cavity is placed on a first side of the fiber-based packaging laminate and a second mold half with a second cavity is placed on the opposite side of the fiber-based packaging laminate. Usually, the first mold cavity partially overlaps the second mold cavity in one or more overlapping regions. A small amount of polymer melt is then injected into at least the first cavity. Due to the pressure building up in the first cavity, the melt penetrates the fiber-based packaging laminate in the overlapping regions and fills the second cavity for the production of an opening device extending through the packaging laminate.

[0077] The small amount of plastic used by this technique ensures that even if only the surface layer starts to solidify, this is enough to hold the shape of the device until it is completely solidified, which therefore suggests that the mold be opened as soon as injection is finished. The outermost skin layer of the plastic melt solidifies as soon as it comes into contact with the walls of the mold cavity or the outermost layer of the packaging material. For uncomplicated designs, this ensures that the mold can be opened as soon as it is filled.

[0078] The connection of the two parts, one on each side of the packaging material, i.e. the molded so-called "bridge", may create an opening device that can apply force to both sides of the material during opening in an interactive manner to facilitate easy opening while still using very little polymer material for the molded parts of the opening device. Furthermore, high pressure micro injection molding technology ensures a very time-efficient molding process in high speed filling machines in the same operation where the packaging is formed, filled and sealed.

[0079] The heat sealable material 410,510 is applied along what will become the transverse seal TS in the package formed from the finished laminated packaging material 200,200',400,500.

[0080] After application of the heat-sealable material 410, 510, the material 410, 510 is in direct contact with the innermost layer 203, 403, 503 of the laminated packaging material 100. A large surface area at the interface between the innermost layer 203, 403, 503 and the heat-sealable material 410, 510 is advantageous for forming a seal between the heat-sealable material portion 410, 510 and the surface of the innermost layer 203, 403, 503.

[0081] Finally, when the heat sealable material 410, 510 solidifies, the heat sealable material portion 204, 204', 404, 504 is bonded to the innermost layer. The packaging material 200, 200', 300, 400, 500 can then proceed to a filling station and may be formed into a packaging container 160, such as the packaging container 160 shown in Figure 3b.

[0082] The method 600 for making the laminated packaging material 200, 200', 300, 400, 500 with locally distributed heat sealable material portions 204, 204', 304, 404, 504 is carried out after the conversion process. The method 600 is either carried out inside the filling machine or after the packaging material 100 is unwound from the reel 110 just before entering the filling machine. Therefore, the supply of the laminated packaging material 200, 200', 300, 400, 500 must be slow enough to allow the attached heat sealable material portions 204, 204', 304, 404, 504 to solidify. The speed of the packaging material can be, for example, in the range of 0.5 m / s. Even though the speed is slower than when the packaging material passes through a converting station, the slower speed allows for the use of several different application methods to apply the heat sealable material 410, 510 to the innermost layer 203, 203', 303, 403, 503.

[0083] The laminated packaging material 200, 200', 300, 400, 500, which includes locally distributed heat-sealable material portions 204, 204', 304, 404, 504, is no longer uniformly flat, so that applying the heat-sealable material portions 204, 204', 304, 404, 504 during the lamination / manufacturing process of conversion is similarly unsatisfactory. Thus, the laminated packaging material 200, 200', 300, 400, 500 cannot be wound as a damaged and problem-free material reel 110. The added heat-sealable material portions 204, 204', 304, 404, 504 may "build up" during winding, providing an uneven reel 110.

[0084] Furthermore, as mentioned above, the operating speed during conversion is typically much faster than in a filling machine, which makes it difficult to apply the heat-sealable material portions 204, 204', 304, 404, 504. Localized application of additional heat-sealable material portions 204, 204', 304, 404, 504 during conversion is therefore much less preferred.

[0085] Figures 7a-f show further alternatives to the cross-sections in figures 4c and 5c, taken in a direction perpendicular to the longitudinal extension of the transverse seals TS and / or sealing elements 704a-f.

[0086] In Fig. 7a, the cross section is triangular, which is an advantage of the ultrasonic heat sealing method. As mentioned above, the cross section may alternatively be a cut such triangular shape, providing the same effect. The apex or narrower peak of the applied profile of the additional material portion ensures that the heat generation occurs in a more concentrated manner. The apex or peak may alternatively be rounded, i.e., approximately triangular in cross section.

[0087] Figure 7b shows a similar, but asymmetrical cross-sectional view for the same purpose, where the bulk of the added material has been shifted laterally within the cross-section of the applied portion of heat-sealable material. This profile may be used along the entire transverse heat seal extension or a portion thereof where an additional amount of added material is desired. For heat sealing of packages with large liquid contents, it may be desirable to add a larger amount of polymeric material, but still avoid such excess material flowing into the sealing fin area and interfering with the cutting action, as will be explained below in connection with Figure 10.

[0088] FIG. 7c shows an embodiment that is asymmetric in cross section but can hold a larger amount of heat-sealable material, which may be advantageous for larger packaging containers for liquid products than for FIG. 7b.

[0089] In figures 7d, 7e and 7f, embodiments are shown with a cross section similar to figures 7a, 7b and 5c respectively, but with a hollow interior. These embodiments may be suitable for heat sealing of smaller packages, for example partial packages of liquid beverages or food products up to 300ml, when a less strong heat seal is suitable or a wider base of the seal towards the innermost layer is desired. These embodiments allow for an extensive transverse seal with a smaller amount of heat sealable material, but at the same time with a concentrated development of heat for an optimal sealing process.

[0090] 8a shows a cross-section of a prior art folded tube (of which the folded transverse edge region is not shown) from a conventional laminated packaging material 80 having an innermost heat-sealable layer 81 in the process of being transversely sealed such that the innermost heat-sealable layer 81 is sealed against itself at the opposing tube wall. A longitudinal band 82 of heat-sealable material is applied to the inside of the longitudinal edge 83 to cover the open edge 83 of the laminated packaging material inside the tube. The longitudinal band 82 is sealed onto the open inner longitudinal edge 83 and further sealed to the inside of the outer edge 84 of the packaging material 80 such that the longitudinal overlap seal region is securely sealed inside the tube by the longitudinal band 82 and is protected from contact with the filled liquid product.

[0091] 8b-c show variants of the cross-section of a folded tube to be transversely sealed, which instead of and in addition to having only a very thin layer of heat-sealable material on the inside of the laminated packaging material have a locally applied heat-sealable material portion applied at least partially along an extension of the transverse seal area. A longitudinal band 82 of heat-sealable material is still applied to the inner longitudinal edge 83 as described above to cover the open edge 83 of the laminated packaging material inside the tube, but for visibility reasons, in these figures the longitudinal band 82 is not shown.

[0092] FIG. 8b shows a cross section of a folded tube from a laminated packaging material 80b with a very thin innermost heat sealable layer 81b (of which the folded transverse edge area is not shown) in the process of being transversely sealed so that the inner surface with the innermost heat sealable layer 81b can be sealed to itself with the opposing tube wall. The applied thickness of the innermost layer 81b is sufficient to protect the inner layers of the packaging laminate, such as the paperboard bulk or core layer and the film or foil carrying the shielding layer or coating, against moisture and dirt, but is not sufficient to provide a strong and durable heat seal for liquid carton packaging. The locally applied heat sealable material portion 85 is applied along the extension of the transverse seal area seen from the perspective in this figure as a local thickness in addition to the previously applied innermost layer 81b. The locally applied heat sealable material portion 85 is applied along the entire extension area of ​​the transverse seal as a strand of material. Regardless of the cross-sectional profile, the applied strand appears simply as an additional thicker layer from this perspective. In addition, additional amounts of heat-sealable material 87b and 88b are applied to close the longitudinal edges 83 and 84 of the web of packaging material to form a strong and durable overlap seal 86b as well along the longitudinal seam of the packaging material tube. When the bars of the transverse sealing jaws press the walls of the tube together to form a flat transverse seal, higher pressure will be exerted in the area of ​​the longitudinal seal LS due to the double layer of material at the overlap seam. To ensure that sufficient heat-sealable material remains within the LS overlap area, additional amounts are applied to the edge areas as shown. Additional material 85b is applied along the entire extension of the transverse seal to accommodate at least the thicker innermost layer in the seal area.

[0093] FIG. 8c shows an alternative cross-sectional view of a folded tube from a laminated packaging material 80c with a very thin innermost heat-sealable layer 81c (of which the folded transverse edge area is not shown) in the process of being transversely sealed so that the inner surface with the innermost heat-sealable layer 81c can itself be sealed with the opposing tube wall. The applied thickness of the innermost layer 81c is only sufficient to protect the inner layers of the packaging laminate, such as the paperboard bulk or core layer and the film or foil carrying the shielding layer or coating, against moisture and dirt, and is not sufficient to provide a strong and durable heat seal for liquid carton packaging. The locally applied heat-sealable material portion 85c is applied along some parts of the extension of the transverse seal area, which from the perspective in this figure is seen as a local thickness in addition to the previously applied innermost layer 81c. The locally applied heat-sealable material portion 85c is thus applied as a strand of material along some of the extension of the transverse seal area. Regardless of the cross-sectional profile, the applied strand simply appears from this perspective as an additional thicker layer. In addition, additional amounts 87c and 88c of heat-sealable material are applied near the longitudinal edges 83c and 84c of the web of packaging material to form a strong and durable overlap seal 86c similarly along the longitudinal seam of the packaging material tube for the same purpose as described above.

[0094] FIG. 9 shows a transverse sealing area 140 surrounding a top end seal 5a (whose future location is indicated by a thick line) and a bottom end seal 5b (whose future location is indicated by a thick line) as seen from above on the inside of the web of flat packaging material. The area of ​​packaging material 132a above the top end seal 5a corresponds to one packaging unit and has a set of folds applied to it that allow the packaging to be folded and formed later. The end seal 5a will usually become the top seal of the formed package, which is why we also call it the "top" end seal. It may, however, alternatively become the bottom seal of the formed package, depending on how the filling machine is configured. The area of ​​packaging material 136a below the bottom end seal 5b therefore corresponds to another packaging unit and has a set of folds applied to it that allow the packaging to be folded and formed later. End seal 5b will usually be the bottom seal of the formed package, which is why we refer to it herein as the "bottom" end seal.

[0095] The to-be-formed cut region 5c of the tube extends between the top and bottom end seals 5a, 5b.

[0096] Thus, the transverse sealing area 140 includes a lower sealing area 142 for forming a lower seal of the packaging below as positioned on the tube when filled, an upper sealing area 144 for forming an upper seal of the packaging above as positioned on the tube when filled, and a cutting area 146 disposed between the lower and upper sealing areas 142, 144.

[0097] The packages are severed from the tube of packaging material along the centerline of transverse cut region 146, i.e., transverse linear cut 148. When the packages are severed from the tube, they have narrow fins of packaging material extending below and above the upper and lower transverse seals 5a and 5b, respectively.

[0098] Additional heat-sealable material is applied locally along the extensions of the bottom and top end seals 5a and 5b.

[0099] Generally, a greater amount of heat-sealable material may be placed along the extension of the end seal area 5a,b at a lateral position corresponding to the location of the longitudinal seal of the tube 150a, 150b, where the longitudinal edges of the web-shaped packaging material will overlap each other. When the bars of the transverse sealing jaws press the walls of the tube together to form a flat transverse seal, a higher pressure is applied in the area of ​​the longitudinal seal LS due to the double layer of material at the overlap seam 86. To ensure that some of the heat-sealable material stops within the overlap, an additional amount is applied in this area. The additional amount is visible as a higher locally applied portion or, when viewed from above as in this figure, a wider portion in the immediate vicinity of the overlap seam.

[0100] Greater amounts of heat sealable material may also be placed along the extensions of the end seal areas 5a,b at lateral locations corresponding to where the tube will be folded during sealing, i.e., locations corresponding to the side edges of the tube. Additional amounts of thermoplastic polymeric material have been found to increase the seal strength of the tube at such locations 150c, 150d, thus improving the integrity and appearance of the final package.

[0101] Similar greater amounts of heat sealable material may also be applied at other locations along the extensions of the end seal areas 5a, 5b to ensure a proper and durable transverse seal in the package formed in the tube filling and sealing operation.

[0102] Fig. 10 shows an isometric view along an extension of the locally applied portion 10 of heat-sealable material at the upper transverse seal 5a, i.e. the transverse seal that will become the top seal of the first package formed from the packaging unit 11. A linear area 12 that will become the transverse linear cut 148 is shown beside the dotted line. On the other side of the linear area 12 there is a corresponding locally applied portion of heat-sealable material, not shown, at the lower transverse seal 5b, i.e. the transverse seal area that will include the bottom seal of the package formed from the adjacent packaging unit below the first package. As shown in Fig. 10, the locally applied portion 10 of heat-sealable material has an asymmetric cross-section to avoid the locally applied additional material flowing too far below the top seal 5a and into the upper sealing fin 13 when sealed. If too much heat-sealable material flows in this direction during sealing, it may reach the active cutting knife and cause problems such as, for example, the molten heat-sealable material may solidify during the cutting operation, for example, causing the cut packages to still stick to each other, causing additional wear on the sharp knife, and causing clogging of the knife advancement and retraction mechanism. In this particular embodiment shown, the cross section of the locally applied portion of heat-sealable material is triangular, thus having a surface that is inclined towards the cutting line. In addition, as mentioned above, a larger amount of heat-sealable material may be added at some locations along the extension of the end seal, for example at the folded edge of the tube in the location for forming the longitudinal overlap seal and in the transverse seal area.

[0103] From the above description, although various embodiments of the present invention have been described and illustrated, the present invention is not limited thereto, but rather may be embodied in other ways within the scope of the subject matter defined in the following claims.

Claims

1. A packaging material comprising a core layer (201, 201', 401, 501), an outermost layer (202, 202', 402, 502) arranged to face the exterior of a packaging container made of said packaging material (200, 200', 400, 500), and an innermost layer (203, 203', 403, 503) arranged to face the interior of said packaging container, said outermost layer (202, 202', 402, 502) and said innermost layer (203, 203', 403, 503) being laminated to said core layer (201, 201', 401, 501), said packaging material further comprising a locally applied heat sealable material portion (204, 204', 404, 504) arranged on said innermost layer (203, 203', 403, 503), said heat sealable material portion (204, 204', 404, 504) having a cross-section with an increasing width towards said innermost layer (203, 203', 403, 503); The heat sealable material portion (204, 204', 404, 504) is disposed in a sealing area corresponding to the location of a transverse seal (TS) of the packaging container; packaging materials.

2. The packaging material of claim 1, wherein the heat sealable material portion (204, 204', 404, 504) is adhered to the innermost layer (203, 203', 403, 503).

3. The packaging material according to claim 1 or 2, wherein the packaging material has a rectangular shape.

4. The packaging material according to any one of claims 1 to 3, wherein the thickness of the heat sealable material portion (203, 203', 403, 503) is 2 to 50 μm, preferably 3 to 30 μm, such as 3 to 20 μm or 5 to 20 μm, most preferably 5 to 15 μm.

5. The packaging material according to any one of claims 1 to 4, wherein the heat-sealable material portion has a cross-section having the shape of a triangle or a truncated triangle.

6. The packaging material according to any one of claims 1 to 5, wherein the heat-sealable material portion has a cross-section having an asymmetric shape.

7. The packaging material according to any one of claims 1 to 6, wherein the length of said heat-sealable material portion (204, 204', 404, 504) extends along the entire transverse sealing area.

8. The packaging material according to any one of claims 1 to 7, wherein the portions of heat-sealable material are arranged to have a varying cross-section along the entire transverse sealing area.

9. The packaging material according to any one of claims 1 to 8, wherein the heat-sealable material portion has a cross-section that provides a greater amount of polymeric material at a given location along the entire transverse sealing area.

10. The packaging material according to any one of claims 1 to 9, wherein a greater amount of heat-sealable material is applied close to the longitudinal edges of the packaging material along the entire transverse sealing area.

11. 11. The packaging material according to any one of claims 1 to 10, wherein the seal initiation temperature, i.e. the softening temperature, e.g. the Vicat point or glass temperature (Tg) and / or the melting temperature (Tm) of the thermoplastic polymer of the locally applied heat sealable material portion is less than the corresponding seal initiation temperature of the thermoplastic polymer of the innermost layer.

12. The packaging material according to any one of claims 1 to 11, wherein said heat-sealable material portion (204, 204', 404, 504) is made of a thermoplastic polymer selected from the group consisting of polyolefins and polyesters.

13. The packaging material according to any one of claims 1 to 12, further comprising a shielding layer (205') disposed between the core layer (201, 201', 401, 501) and the innermost layer (203, 203', 403, 503).

14. The packaging material according to any one of claims 1 to 13, wherein the core layer (201, 201', 401, 501) is a cellulosic material, such as paper or paperboard.

15. A method for making a packaging container from a packaging material (200, 200', 400, 500), comprising the steps of: laminating (610) an innermost layer (203, 203', 403, 503) and an outermost layer (202, 202', 402, 502) to a core layer (201, 201', 401, 501) to provide said packaging material; locally heat applying (650) a portion of heat-sealable material (204, 204', 404, 504) to said innermost layer (203, 203', 403, 503); forming a packaging container from said packaging material (200, 200', 400, 500); filling the packaging container; heat sealing said packaging container with said heat sealable material portion (204, 204', 404, 504) to form a closed packaging container; Including, said heat sealable material portions (204, 204', 404, 504) are applied such that their cross-sections have an increasing width towards said innermost layer (203, 203', 403, 503); The heat sealable material portion (204, 204', 404, 504) is disposed in a sealing area corresponding to the location of a transverse seal (TS) of the packaging container; method.

16. 16. The method of claim 15, wherein the step of applying heat (650) is performed using an injection molding process, a sintering process, a welding process, a thermal spraying process, a compression molding process, an inkjet type polymer printing process, or a 3D printing process.

17. The method according to claim 15 or 16, wherein said innermost layer (203, 203', 403, 503) is selected from heat-sealable polymers, preferably thermoplastic polymers selected from polyolefins, such as polyethylene and polyesters.

18. A method according to any one of claims 15 to 17, wherein the packaging material has a rectangular shape and is fed in the form of a continuous web to a roll-fed carton-based packaging machine.

19. A packaging container made of the packaging material according to any one of claims 1 to 14, comprising a core layer (201, 201', 401, 501), an outermost layer (202, 202', 402, 502) and an innermost layer (203, 203', 403, 503) laminated to the core layer, wherein the heat-sealable material portion (204, 204', 404, 504) is the innermost layer (203, 203', 403, 504). 03′, 403, 503), The heat sealable material portion is locally disposed at the location of one or more transverse seals (TS) of the packaging container; packaging container.

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