Laminated packaging material and method for manufacturing the same

Abstract

A laminated packaging material (16) for packaging liquid food (12), a corresponding manufacturing method, and a packaging container (10) are provided. The laminated packaging material (16) includes a paper or paperboard or other cellulose-based material body layer (20), a first outermost liquid-tight layer (22), a second innermost liquid-tight layer (24), and a metal barrier film or sheet (26) not laminated between the body layer (20) and the second innermost liquid-tight layer (24), wherein the body layer (20) and the barrier film or sheet (26) together form a main layer (28). The main layer (28) is provided with at least one slit (30), which is at least covered by the second innermost liquid-tight layer (24).

Description

Technical Field

[0001] This invention relates to a laminated packaging material for packaging liquid food, a method for manufacturing such a laminated packaging material, and a packaging container comprising the laminated packaging material. Background Art

[0002] Single-use packaging containers for liquid foods are typically made of cardboard or rigid cardboard-based packaging laminates. One such common type of packaging container is branded with Tetra Brik. These are aseptically packaged containers for sale, primarily for liquid foods (such as milk, juice, etc.) intended for long-term storage at room temperature. The packaging materials in these known containers are typically laminated materials, comprising a body or core layer of paper, cardboard, or other cellulose-based material, and a liquid-tight outer layer of thermoplastic. To ensure the containers are airtight, particularly oxygen-tight, for purposes such as aseptic packaging and packaging milk or juice, the laminated materials in these containers usually include at least one additional layer, most commonly aluminum foil.

[0003] On the inner side of the laminate, i.e., the side facing the food contents of the container made from the laminate, there is an innermost layer applied to the aluminum foil. This innermost layer may consist of one or more component layers containing a heat-sealable thermoplastic polymer, such as an adhesive polymer and / or a polyolefin. Similarly, on the outer side of the body layer, there is an outermost heat-sealable polymer layer.

[0004] Packaging containers are typically produced using modern high-speed packaging machines that form, fill, and seal rolls or pre-made packaging material blanks. Therefore, packaging containers can be produced by reforming a roll of laminated packaging material into a tube by welding the innermost and outermost heat-sealable thermoplastic polymer layers together, with the two longitudinal edges of the roll joined together at an overlap. This tube is filled with the intended liquid food and is subsequently separated into individual packages by repeating transverse sealing at predetermined intervals below the level of the contents. The packages are separated from the tube by cuts along the transverse seal and given the desired geometry, typically a parallelepiped, by folding along pre-prepared crease lines in the packaging material.

[0005] The main advantage of this continuous tube forming, filling, and sealing packaging method is that the roll material can be continuously sterilized before tube formation, thus providing the possibility of aseptic packaging methods. Aseptic packaging methods are those in which both the liquid contents to be filled and the packaging material itself have reduced bacteria, and the filled packaging containers are produced under clean conditions, allowing the filled packaging to be stored for extended periods even at ambient temperatures without the risk of microbial growth in the filled product. As mentioned above, Tetra... Another important advantage of this type of packaging method is the possibility of continuous high-speed packaging (which has a considerable impact on cost efficiency).

[0006] Packaging containers for sensitive liquid foods such as milk or juice can also be produced from sheet preforms or preforms of the laminated packaging material of the present invention. Packaging is produced from tubular preforms of folded flat packaging laminates by first constructing the preform to form an open tubular container capsule, one open end of which is closed by folding and heat-sealing an integral end plate. The thus closed container capsule is filled with the food in question (e.g., juice) through its open end, and then the open end is closed by further folding and heat-sealing of the corresponding integral end plate. An example of packaging containers produced from sheet and tubular preforms is the conventional so-called mountain-top packaging. This type of packaging also exists, which has a molded top and / or nuts made of plastic.

[0007] Aluminum foil layers in packaging laminates have been used for many years to provide the required gas barrier properties, and traditional aluminum foil packaging laminates for aseptic packaging of liquid foods remain the most cost-effective packaging materials at the performance levels available on the market today.

[0008] However, there is a growing trend towards developing laminated packaging materials that do not contain aluminum foil in their laminated structures, in an effort to improve the environmental characteristics of the resulting materials. Naturally, there is also a desire to reduce the manufacturing cost of laminated packaging materials while maintaining the performance required for the aseptic long-term storage of packaging containers produced from these materials.

[0009] Any material that can compete with aluminum foil must be cost-effective in terms of raw materials, have at least comparable food preservation performance, and be relatively less complex to convert into finished packaging laminates.

[0010] In efforts to develop non-aluminum foil materials for paperboard packaging of liquid foods, there is a general encouragement to develop prefabricated films or sheets with high and multiple barrier functions, that is, not only oxygen or gas barrier functions, but also water vapor, chemical substances or aromatic substances barrier properties, so as to replace aluminum foil barrier materials of traditional laminated packaging materials and adapt them to the lamination and manufacturing of traditional aluminum foil processes.

[0011] To meet industrial demands, the applicant has proposed a series of alternatives to aluminum foil-free laminated packaging materials. For example, EP 3517291 proposes a barrier film comprising a polyester selected from polyethylene 2,5-furandicarboxylate (PEF) and polytrimethylene furandicarboxylate (PTF), blends therewith, and copolymers thereof, coated with a vapor-deposited barrier coating comprising a metal or metal oxide. US11046060 discloses a barrier film comprising a diamond-like carbon PECVD coating.

[0012] While the proposed barrier films and the resulting laminated packaging materials offer promising performance in terms of environmental friendliness, cost-effectiveness, and providing the required integrity, these non-aluminum barrier materials typically exhibit significant differences in permeability. For laminated packaging materials intended for use with straws, it is generally necessary to puncture the barrier film. This pore is provided by punching holes in the body layer or core layer prior to lamination, and then covering the inner and outer pores with an additional laminate layer comprising the barrier material. With this construction, the consumer does not have to puncture the body layer or core layer, thus significantly reducing the required puncture force. However, pre-punching in the body layer or core layer increases the complexity of the manufacturing process.

[0013] To satisfy consumers, the puncture force should be as low as possible, but the opening structure needs to have a certain degree of resistance to prevent accidental penetration. Consumer surveys indicate that a puncture force of approximately 15N or less is required. A puncture force of approximately 10N to 12N has proven satisfactory in terms of packaging container integrity and handling. However, laminated packaging materials using aluminum foil alternatives as barrier materials require significantly higher puncture forces, for example, in the range of 25N, even after removing the body layer or core layer as described above.

[0014] In view of this, existing technologies for laminated packaging materials that do not use aluminum foil as a barrier film do not allow the use of straws, because the required puncture force is far beyond what consumers can accept.

[0015] Therefore, there is a need for an improved laminated packaging material that does not require a barrier layer made of aluminum foil, but at the same time provides reduced puncture force for the laminated packaging material, so that straws can be used with the final packaging container. Summary of the Invention

[0016] One object of the present invention is to overcome, at least in part, one or more of the aforementioned limitations of the prior art. Specifically, one object is to provide a laminated packaging material for packaging liquid foods that securely encapsulates the liquid food, reduces the puncture force required when using straws and packaging materials, and reduces the amount of metal material constituted by the packaging material.

[0017] To achieve these objectives, a first aspect of the present invention provides a laminated packaging material for packaging liquid food. The laminated packaging material comprises a body layer of paper or cardboard or other cellulose-based material, a first outermost liquid-tight layer disposed outside the body layer to form the outer side of a packaging container formed by the packaging material, a second innermost liquid-tight layer disposed inside the body layer to directly contact the filled food, and a non-metallic barrier film or sheet laminated between the body layer and the second innermost liquid-tight layer, wherein the body layer and the barrier film or sheet together form a main layer.

[0018] The barrier film or sheet is at least proportionately a non-metallic barrier film or sheet, that is, the barrier film or sheet is a non-metallic barrier film or sheet, or a barrier film or sheet with a metal content of less than 5% by mass.

[0019] According to the laminated packaging material of the present invention, the main layer is provided with at least one slit, which is at least covered by a second liquid-tight layer. In some embodiments, the slit is covered by a first liquid-tight layer and a second liquid-tight layer.

[0020] A slit covered at least by a second liquid-tight layer and optionally also by a first liquid-tight layer is advantageous because the piercing force required to insert, for example, a straw into the area of ​​the slit is significantly reduced, while maintaining protection for the food packaged with the laminated packaging material of the present invention. The piercing force is particularly reduced to a level well below 25 N. Simultaneously, the oxygen permeability (OTR) of the packaged components remains at a low level, not exceeding 0.002 cm⁻¹. 3 / Component (24 hours, 23 degrees Celsius and 50% relative humidity at 0.2 atmospheres). By including at least a proportionally proportioned non-metallic barrier film or sheet, in other words, meaning that the barrier film or sheet at least partially comprises non-metallic material, the amount of metal in the laminated packaging material is significantly reduced or eliminated. This improves the environmental characteristics of the laminated packaging material. Another problem can be solved due to the slit, based on the fact that in known laminated packaging materials, holes are provided in the body layer by a stamping action before laminating the inner and outer layers. This process produces stamping residues in the body layer in the manufacturing environment, which was previously known as the "confetti problem." This problem is solved by the slit in the laminated packaging material of the present invention, because the material around the slit is only displaced, not stamped away.

[0021] The first outermost liquid-tight layer and / or the second innermost liquid-tight layer are preferably heat-sealable. More preferably, the first outermost liquid-tight layer and / or the second innermost liquid-tight layer may comprise a thermoplastic material. Preferably, the first outermost liquid-tight layer and / or the second innermost liquid-tight layer are heat-sealable thermoplastic layers.

[0022] Barrier films or sheets can include any barrier material suitable for maintaining a food-safe environment for packaged liquid foods. This encompasses materials with inherent gas-barrier properties, particularly those forming an oxygen transport barrier. Such materials can be found, for example, in polymers, such as ethylene vinyl alcohol films, EVOH films, or polyamide films. Alternatively, the barrier film can comprise a polyolefin-based substrate with a vacuum-deposited barrier coating. The vacuum-deposited or vapor-deposited coating can be a metallic coating, a metal oxide coating, an inorganic oxide coating, a coating of other inorganic compounds, or a carbon-based coating, such as an amorphous diamond-like carbon (DLC) coating. However, it should be noted again that if the barrier film or sheet includes a metallic material, it also includes, in part, at least one or more non-metallic materials. It can also be composed entirely of non-metallic materials. Some preferred materials are described below.

[0023] The barrier film or sheet can be a composite material, for example, comprising a large amount of non-metallic material and a small amount of metallic material. In some embodiments, the metallic material can provide the advantage of preventing light transmission, thereby further protecting the product encapsulated by the packaging material from the external environment. Preferably, the amount of metallic material does not exceed 5% of the total composite material, more preferably not more than 4%, more preferably not more than 3%, even more preferably not more than 2%, and most preferably not more than 1%. The amount of metallic material can refer to the mass or volume of the total composite material, meaning that it is expressed as a percentage of the total mass or volume, respectively. Preferably, it refers to the mass amount. All intermediate values ​​from 5% to 0% are also disclosed herein, limited only by the precision achievable by known manufacturing processes.

[0024] For example, non-metallic materials may include plastics, paper, or cellulose-based materials. Metallic materials may include aluminum. Other preferred materials will be described further below. Non-metallic materials can form a substrate that supports the barrier material.

[0025] In one embodiment of the laminated packaging material of the present invention, the at least one slit extends completely through the main layer. This further reduces the piercing force required to pierce the main layer (e.g., with a straw).

[0026] In one embodiment of the laminated packaging material of the present invention, the barrier film or sheet includes a base layer coated with a barrier material. Such a barrier film or sheet may be an embodiment of the aforementioned composite material.

[0027] In one embodiment of the laminated packaging material of the present invention, the base layer is made of a plastic, paper, or cellulose-based material. For example, the base layer may be metallized, preferably with aluminum. Such a metal coating (e.g., aluminum) on the base layer can have a thickness of, for example, 60 nm. The base layer can typically have a thickness of 12 μm or greater, for example, 12 to 50 μm, depending on the material, the desired application, and machine parameters. In this merely exemplary combination, the amount of metal is typically much less than 1% by volume or 1% by thickness of the barrier film or sheet.

[0028] Generally, the barrier film or sheet, and if applicable, the coatings included therein, may comprise thin material coatings or combinations of such coatings, either vapor-deposited coatings or dispersed coating materials. The substrate layer may also include a barrier material, which may be an EVOH surface layer or coating or a polyamide polymer surface layer or coating.

[0029] Gas-barrier materials or coatings applied by coating with aqueous dispersions or solution compositions may include polymers with inherent gas-barrier properties, and are food-safe and environmentally sustainable in terms of recyclability and their application in industrial coating and lamination processes. Therefore, such polymers are water-dispersible and / or soluble in water, and can be applied by aqueous dispersion coating processes or liquid film coating processes. Non-aqueous or only partially aqueous coating compositions, such as those based on alcohols or mixtures of alcohols and water, are also suitable for the invention disclosed herein.

[0030] The barrier dispersion coating may include polymers selected from vinyl alcohol polymers and copolymers, such as polyvinyl alcohol (PVOH) and ethylene vinyl alcohol (EVOH), starch, starch derivatives, nanofibrillated cellulose / microfibrillated cellulose (NFC / MFC), nanocrystalline cellulose (NCC), and blends of two or more of these.

[0031] Barrier dispersion coatings can be applied by means of dispersion or solution coating, with reference to the dry weight of the barrier material, ranging from 0.2 to 5 g / m³. 2 For example, 0.5 to 4 g / m 2 For example, 0.5 to 3.5 g / m 2 Or, for example, 1 to 3 g / m³ 2 Apply in equal amounts.

[0032] The process suitable for coating low dry content polymer dispersions or solution compositions is broadly any suitable wet coating method, such as gravure roll coating, air spraying, airless spraying, reverse roll coating, wire rod coating, lip coating, air knife coating, curtain coating, spraying, dip coating, scraping and brushing methods.

[0033] Barrier dispersion coating compositions can be based on two of the most common types of polymers and copolymers suitable for dispersion coating, which are based on vinyl alcohol monomers, namely polyvinyl alcohol (PVOH) and ethylene vinyl alcohol (EVOH).

[0034] Gas barrier polymers are preferably PVOH because they offer good film-forming properties, gas barrier properties, cost efficiency, food compatibility, and odor barrier properties.

[0035] Gas barrier compositions based on PVOH perform best when the PVOH has a saponification degree of at least 98%, preferably at least 99%, but PVOH with a lower saponification degree will also provide oxygen barrier properties.

[0036] On the other hand, EVOH can be advantageous by providing some moisture barrier properties to the barrier material because the copolymer includes ethylene monomer units. The amount of ethylene monomer units depends on the choice of EVOH grade, but its presence will come at the cost of some oxygen barrier performance compared to pure PVOH. Conventional EVOH polymers are typically used for extrusion and cannot be dispersed or dissolved in aqueous media to produce 3.5 g / m³ materials. 2 The following thin liquid film coating barrier film is used. Such EVOH should include a relatively high content of vinyl alcohol monomer units to be water-dispersible, and its performance should be as close as possible to that of liquid film coating grade PVOH. The extruded EVOH layer can be incorporated into the polymer base film, preferably as a surface layer on a polyolefin base film.

[0037] The barrier dispersion coating composition may also include an inorganic layered compound, such as exfoliated nanoclay particles, such as bentonite, based on about 1 to about 20% by weight of the dry coating. Therefore, the barrier layer may include a polymer based on about 99 to about 80% by weight of the dry coating.

[0038] Therefore, it can be obtained at a dry weight of 0.2 to 4 g / m³. 2 More preferably 0.5 to 4 g / m 2 For example, 0.5 to 3.5 g / m 2 For example, 1 to 3 g / m 2 The total amount applied is a barrier dispersion coating. Less than 0.2 g / m³. 2 It is impossible to achieve gas barrier performance at all, and the value is higher than 3.5g / m 2 Coatings offer lower cost-effectiveness for packaging laminates because barrier polymers are generally more expensive, and the energy costs of evaporating the liquid are also higher. PVOH at 0.5 g / m 2 A identifiable oxygen barrier level can be achieved at levels of 0.5 to 3 g / m³ and above. 2 Achieving a good balance between blocking performance and cost.

[0039] The barrier dispersion coating can be applied as two partial layers in two consecutive steps with an intermediate drying. When applied as two partial layers, each layer is appropriately applied at a concentration of 0.2 to 2 g / m³. 2 Preferably 0.5 to 1.5 g / m 2 The amount applied allows for a higher quality overall layer to be obtained with a smaller amount of liquid gas barrier composition. More preferably, each of the two partial layers is applied at a rate of 0.5 to 1.5 g / m². 2 The amount applied.

[0040] The substrate may also have a vapor-deposited coating on its first side surface made of a gas barrier material selected from metals, metal oxides, inorganic oxides, and amorphous diamond-like carbon coatings. The vapor-deposited coating can be applied by physical vapor deposition (PVD) or chemical vapor deposition (CVD), for example by plasma-enhanced chemical vapor deposition (PECVD). More specifically, it can be selected from aluminum metallization coatings and alumina (AlO2) applied by a PVD process. x The group consists of, preferably, aluminum metallization coatings. PVD processes are used for metal deposition, such as aluminum or aluminum oxide (AlO). x The deposition of amorphous carbon and diamond-like carbon is provided by CVD or PECVD processes.

[0041] For example, the substrate of a paper or cellulose-based material sheet may have a first dispersion coating of a gas barrier material formed by coating and subsequently drying a dispersion or solution of an aqueous gas barrier composition on the first top side surface, and further apply a vapor-deposited coating of a gas barrier material selected from metals, metal oxides, inorganic oxides and amorphous diamond-like carbon to the first barrier dispersion coating.

[0042] Therefore, the barrier-coated cellulose-based substrate can also be coated with a gas barrier material by vapor deposition onto its top surface to a thickness of 2 to 80 nm, for example 2 to 50 nm, or for example 2 to 45 nm.

[0043] Vapor-deposited barrier coatings applied to the top surface of a substrate can be applied by physical vapor deposition (PVD) or chemical vapor deposition (CVD), such as by plasma-enhanced chemical vapor deposition (PECVD). However, the latter process is particularly suitable for polymer thin film substrates.

[0044] Generally speaking, when the thickness is less than 5nm, the barrier performance may be too low to be used, while for thicknesses greater than 200nm, such as greater than 100nm or greater than 50nm, depending on the type of vapor-deposited coating, the barrier coating may be less flexible, and therefore more prone to cracking when applied to flexible substrates, and the cost is also higher.

[0045] Other examples of vapor-deposited coatings are alumina (AlO2). x Al2O3 and silicon dioxide (SiO2) x ) Coating. Generally, PVD coatings of this type of oxide are more brittle and less suitable for lamination into packaging materials, while metallized layers are an exception, although they are made by PVD, they do have mechanical properties suitable for laminated materials.

[0046] Typically, due to the nature of the metallization coating process used, aluminum metallization layers inherently have a thin surface portion composed of aluminum oxide.

[0047] The optical density (OD) of the applied aluminum metallization layer can be from 1.8 to 3.0 or even 3.5, for example, from 1.8 to 2.5, preferably from 1.9 to 2.2. When the optical density is below 1.8, the blocking performance of the metallization film may be too low. On the other hand, at a density above 3.5, for example above 3.0, for example above 2.5, the metallization layer may become brittle, and the thermal stability during the metallization process will be low due to the high heat load during metallization of the base film over a longer period of time. Coating quality and adhesion may be negatively affected.

[0048] Other coatings can be applied using plasma-enhanced chemical vapor deposition (PECVD), where the vapor of a compound is deposited onto a substrate in a more or less oxidizing environment. Silicon oxide coatings (SiO2) x It can also be applied, for example, via a PECVD process, and then very good barrier properties can be obtained under certain coating conditions and gas formulations.

[0049] DLC defines a class of amorphous carbon materials (diamond-like carbon) that exhibit some of the typical properties of diamond. Preferably, hydrocarbon gases, such as acetylene or methane, are used as process gases in the plasma to produce an amorphous hydrogenated carbon barrier layer coating, i.e., a DLC coating, applied via a PECVD vacuum process. DLC coatings applied under vacuum via PECVD provide good adhesion to adjacent polymer or adhesive layers in laminated packaging materials. Particularly good adhesion to adjacent polymer layers is achieved using polyolefins, particularly polyethylene and polyethylene-based copolymers.

[0050] In one embodiment of the laminated packaging material of the present invention, the at least one slit does not extend completely through the main layer. In this case, the slit or perforation may extend partially or completely through the body layer and the base film or sheet layer, such that these layers are weakened, but do not penetrate the barrier coating or surface layer, thereby leaving the thin or coated barrier layer intact.

[0051] Preferably, the slit is provided by an action designed to create material separation rather than removal. Suitable techniques for providing the slit may include, for example, using a laser, cutting with a knife or sharp blade, or applying spark treatment.

[0052] Depending on the required piercing force and the opening device (e.g., paper straw, plastic straw, etc.), the slit can have different shapes. Generally, the slit design is determined by a trade-off between OTR and piercing force. Minimum OTR usually requires a minimum slit size, while minimum piercing force requires a fairly large slit size. However, minimum piercing force is generally undesirable, as a certain amount of piercing force will effectively prevent accidental opening.

[0053] Puncture force typically exhibits a continuous bimodal behavior. When piercing packaging material with a straw, a first puncture force is required to penetrate the first layer of the packaging material. A second puncture force is then needed to push the straw through the slit, causing the packaging material around the straw to deflect. The widespread use of paper straws presents additional challenges compared to plastic straws. On one hand, paper straws are not as sharp as plastic straws, thus requiring a higher first puncture force to penetrate the initial layer of packaging material. On the other hand, paper straws typically have a larger diameter than plastic straws, and they may be less easily compressed, thus requiring an even higher second puncture force.

[0054] The inventors have recognized that, in a preferred embodiment, the slit is very narrow in one direction and extends in another longitudinal, vertical direction. This "narrow" dimension is achieved, for example, by a sharp cutting blade or a focused laser beam. The longitudinal extension of the slit allows the packaging material, particularly the body layer and the barrier film or sheet, to be separated sufficiently easily to allow the straw to pierce the packaging material.

[0055] The slit can extend along the machine direction. This allows the slit tool to remain stationary at least in the longitudinal direction, as the movement of the packaging material will cause the slit to extend as desired.

[0056] The slit preferably has a partially circular shape, such as a quarter circle, a third circle, or a semicircle, and for example, a two-thirds circle or a three-quarters circle. The diameter of the partial circle preferably corresponds to the diameter of a known straw and may include, for example, a diameter of 6 mm. The partial circle, in other words, refers to a single or multiple-discontinuity circle, preferably comprising a single discontinuity in a circular shape with a length not exceeding 2 mm or 1 mm. The discontinuity may also preferably be measured to be any length between 1 mm and 2 mm, which can be manufactured by known methods. Of course, the geometry of the slit is also compatible with other embodiments described herein.

[0057] In one embodiment of the laminated packaging material of the present invention, the main layer is provided with at least two intersecting slits. This significantly reduces the required puncture force compared to a single slit. Alternatively, multiple non-intersecting slits may be provided, such as perforation-type slits.

[0058] In one embodiment of the laminated packaging material of the present invention, the slit is in the form of a cross. This has been considered a particularly advantageous design, as it reduces the required puncture force to the level of approximately 10 N, while the OTR of the packaged component does not exceed 0.002 cm. 3 / Component 24h 0.2atm.

[0059] Furthermore, each slit of the cross can extend at an angle relative to the longitudinal direction of the laminated packaging material. Regarding the longitudinal extension, it should be understood that laminated packaging materials are typically manufactured in a continuous process with a material feed direction (also known as the manufacturing direction or machine direction). The longitudinal extension of the laminated packaging material is defined herein as parallel to the machine direction. However, it should be noted that the longitudinal extension of the laminated packaging material can be oriented at 90° relative to the longitudinal extension of the final packaging container; in some cases, the area of ​​the laminated packaging material roll intended to form a single packaging container is oriented such that the intended longitudinal extension of the final packaging container is aligned with the transverse machine direction, i.e., perpendicular to the machine direction.

[0060] When a cross is created, the corresponding cutting tool needs to deviate from the machine direction as it moves relative to the workpiece. Therefore, the faster the laminated packaging material moves during production, the higher the control requirements for adapting the movement of the cutting tool relative to the machine direction to create, for example, slits extending transversely to the machine direction. This makes it more difficult to manufacture symmetrical crosses that include, for example, a slit transverse to the manufacturing direction (meaning an angle of 90 degrees) and an intersecting slit parallel to the machine direction (meaning an angle of 0 degrees). However, if both slits are angled relative to the machine direction, for example, each at 45 degrees, the control requirements for moving the cutting tool relative to the machine direction to create these slits are reduced. Simultaneously, symmetrical crosses can be manufactured, for example, two slits intersecting perpendicularly, meaning an X-shaped form.

[0061] In one implementation, the slit can be Y-shaped. This has been considered another preferred shape, which reduces the required puncture force to approximately 14 N while the OTR of the packaging container component does not exceed 0.002 cm. 3 / Component 24h 0.2atm.

[0062] Furthermore, the slit can be in the form of a single straight line. This significantly reduces manufacturing effort and achieves a puncture force far below 25N, meaning approximately 21N, for example. Meanwhile, the OTR of the packaging container components does not exceed 0.002cm. 3The component's 24-hour pressure is 0.2 atm and can be experimentally reduced to no more than 0.001 cm. 3 / Component 24h 0.2atm level.

[0063] In one embodiment, the barrier membrane or sheet is a gas barrier membrane or sheet, preferably an oxygen barrier membrane or sheet.

[0064] Another aspect of the invention relates to a method for manufacturing a laminated packaging material for packaging liquid food. This method may specifically correspond to the laminated packaging material of the invention described herein, and therefore means that all methods relate to the disclosed aspects concerning this laminated packaging material, and vice versa.

[0065] The method of the present invention includes the following steps:

[0066] Provides a body layer of paper or paperboard or other cellulose-based material.

[0067] A non-metallic barrier film or sheet is laminated onto the body layer in at least a proportional proportion, such that the barrier film or sheet and the body layer form the main layer.

[0068] Provide at least one slit for the main layer, and

[0069] The first outermost liquid-tight layer is laminated onto the outside of the body layer to form the outside of the packaging container formed of the packaging material, and

[0070] The second innermost liquid-tight layer is laminated onto the inside of the barrier film or sheet to directly contact the filled food, such that the second liquid-tight layer covers at least one slit of the main layer.

[0071] In this document, at least proportionally nonmetallic barrier films or sheets should be interpreted as nonmetallic barrier films or sheets, or barrier films or sheets with relatively low metal content (e.g., less than 5% by mass).

[0072] In one embodiment of the method of the present invention, a first outermost liquid-tight layer and a second innermost liquid-tight layer are laminated such that the first outermost liquid-tight layer and the second innermost liquid-tight layer cover at least one slit of the main layer.

[0073] In cases where the outermost liquid-tight layer is also cut through by a slit or perforation, the slit or perforation can be locally coated after the packaging container is formed in the filling machine, for example by coating with an aqueous dispersion of a barrier polymer (e.g., PVOH, EVOH, or PA).

[0074] In one embodiment of the method of the present invention, the step of laminating the barrier film or sheet to the body layer is performed by extrusion lamination or wet lamination.

[0075] In addition to previously known laminated packaging materials, particularly those containing pre-punched holes in the body layer, the method of this invention involves laminating a barrier film or sheet to the body layer before forming the slits. Therefore, materials added during extrusion lamination or wet lamination processes (e.g., adhesives) do not penetrate the barrier film or sheet or the body layer. This effectively prevents contamination of various manufacturing equipment, such as the clamping rollers used for lamination.

[0076] In one embodiment of the method of the present invention, a further step includes printing a decorative layer on the outside of the body layer before providing at least one slit for the main layer. This effectively prevents any printed material from entering the slit.

[0077] In one embodiment of the method of the present invention, the step of providing at least one slit for the main layer is performed by laser cutting and / or by mechanical cutting.

[0078] Both variants are particularly effective when a single slit is provided in the manufacturing direction. Laser cutting is especially suitable for efficiently creating slits of one or more flexible geometries. Mechanical cutting (e.g., by a blade or piercing tool) can be done with less technical difficulty.

[0079] In one embodiment of the method of the invention, the at least one slit extends at least a certain distance along the longitudinal direction of the laminated packaging material. This significantly reduces manufacturing workload, as described above regarding the laminated packaging material of the invention. This is particularly advantageous if the manufacturing process is a continuous process.

[0080] Another aspect of the invention relates to a packaging container comprising the laminated packaging material of the invention and / or comprising laminated packaging material manufactured by the method of the invention.

[0081] Other objects, features, aspects, and advantages of the invention will become apparent from the following detailed description and accompanying drawings. Attached Figure Description

[0082] Embodiments of the invention will now be described by way of example with reference to the accompanying schematic diagrams, wherein...

[0083] Figure 1 An embodiment of a packaging container for liquid food is shown;

[0084] Figure 2 An embodiment of a laminated packaging material for packaging liquid foods is shown in cross-sectional view, with reference to the corresponding manufacturing method; and

[0085] Figure 3 Different implementations of laminated packaging materials with alternative variations through slits are shown. Detailed Implementation

[0086] refer to Figure 1 An embodiment of the packaging container 10 of the present invention for use with liquid food 12 is shown. For example, a packaging production machine 14, not further specified, can convey the laminated packaging material 16 of the present invention (see [link to documentation]). Figure 2 and Figure 3 The packaging container 10 of the present invention can be manufactured from this material. The packaging container 10 of the present invention can be manufactured, by way of example, by filling it with liquid food 12 and then cutting and sealing the laminated packaging material 16 of the present invention by means of a corresponding cutting and sealing device 18.

[0087] refer to Figure 2 A cross-sectional view shows 12 (for packaging liquid food). Figure 1 An embodiment of the laminated packaging material 16 of the present invention is shown in the figure. The laminated packaging material 16 mainly comprises a paper or paperboard or other cellulose-based material body layer 20, disposed on the outside of the body layer 20 to form a packaging container 10 formed by the packaging material 16. Figure 1 The first outermost liquid-tight layer 22 (shown in the diagram) is arranged inside the body layer 20 to interact with the filled food 12. Figure 1 (shown in the figure) a second innermost liquid-tight layer 24 in direct contact, and a non-metallic barrier film or sheet 26 laminated between the body layer 20 and the second innermost liquid-tight layer 24 in at least proportionate form, wherein the body layer 20 and the barrier film or sheet 26 together form a main layer 28.

[0088] According to the invention, the main layer 28 is provided with at least one slit 30, which is at least covered by the second liquid-tight layer 24. Figure 2 In the illustrated embodiment, the first liquid-tight layer 22 also covers the slit. However, in some embodiments, the first liquid-tight layer 22 is applied before the slit is formed, such that the slit also extends through the first liquid-tight layer 22.

[0089] It should be noted that slit 30 may extend partially or completely through the main layer 28, which is in Figure 2 As exemplarily shown in the figure.

[0090] Furthermore, it should be noted that at least proportionally, the non-metallic barrier film or sheet 26 can be composed entirely of non-metallic materials. In this case, a single layer made of a barrier material 32 that does not contain any metal can be used.

[0091] The first outermost liquid-tight layer 22 and the second innermost liquid-tight layer 24 are preferably, but optionally, heat-sealable thermoplastic layers.

[0092] like Figure 2 As exemplarily shown, at least proportionally proportioned nonmetallic barrier membranes or sheets 26 can also be specifically implemented as composite materials, and thus each comprises more than one layer. Figure 2 In the example, the barrier film or sheet 26 includes a base layer 34 coated with a barrier material 32. In this case, the barrier material 32 may contain a metallic material because the base layer 34 is made of a non-metallic material. However, the amount of non-metallic material should be very high relative to the amount of metallic material.

[0093] As a preferred example only, the substrate 34 is made of a non-metallic material including plastic, paper, or cellulose-based materials. As a further preferred example only, the barrier material 32 comprises aluminum. However, in this example, the thickness of the barrier material 32 is preferably measured to be only 60 nm, while the thickness of the substrate 34 is preferably measured to be 6 μm. Therefore, in this example, the amount of metallic material does not exceed 1 vol% of the amount of non-metallic material and is therefore relatively very low.

[0094] The laminated packaging material 16 of the present invention can be manufactured using the method of the present invention, such as... Figure 2 As shown.

[0095] In the first step I of the method, a body layer 20 is provided and a non-metallic barrier film or sheet 26 at least proportionally is laminated onto the body layer 20, such that the barrier film or sheet 26 and the body layer 20 are forming a main layer 28.

[0096] In the second step II, the main layer 28 is provided with at least one slit 30, which, exemplarily, completely passes through the main layer 28.

[0097] In the third step III, the first outermost liquid-tight layer 22 is laminated on the outside of the body layer 20 to form the outside of the packaging container 10 formed by the packaging material 16, and the second innermost liquid-tight layer 24 is laminated on the inside of the barrier film or sheet 26 to directly contact the filled food 12, such that the first liquid-tight layer 22 and the second liquid-tight layer 24 cover the slit 30 of the main layer 28.

[0098] In step I, the barrier film or sheet 26 is preferably laminated to the body layer 20 by extrusion lamination or wet lamination.

[0099] Before providing at least one slit 30 for the main layer 28 in step II, a decorative layer 36 is preferably printed on the outer side of the body layer 20. This can be done, for example, in step I or at the beginning of step II.

[0100] To form the slit 30 in step II, laser cutting, mechanical cutting, or a combination thereof is preferred.

[0101] Now refer to another source Figure 3 The different implementations of the laminated packaging material 16 will be described in more detail, with particular attention to preferred variations of the slit 30.

[0102] For this purpose, Figure 1 , 2 The manufacturing direction 38 is defined and shown in Figure 3. The machine direction 38 refers to the fact that the laminated packaging material 16 is typically manufactured in a continuous process having a material feed direction (in other words, the machine direction 38). Based on this, the longitudinal direction 38 of the laminated packaging material 16 is obtained, which is parallel to the machine direction 38. It is well known that parallel direction vectors can move relative to each other as long as they still point in the same direction. Therefore, in the following description, there will no longer be a distinction between the machine direction 38 and the longitudinal direction 38, and the same reference numeral 38 will be used to emphasize their equivalence.

[0103] Figure 3 The upper part shows the laminated packaging material 16, but without the first outermost liquid-tight layer 22 and the second innermost liquid-tight layer 24.

[0104] Different variations of slit 30 in Figure 3 The lower part is shown. The variations shown can be alternatives or used in any combination. According to detail D, in Figure 3 The slit 30 is shown in the top view of the upper main layer 28, the view being projected onto... Figure 3 The lower part.

[0105] In all the alternative embodiments shown in detail D, such as in step II of the method of the invention, the slit 30 is made such that at least one slit 30 extends at least a certain extent in the longitudinal direction 38 of the laminated packaging material 16. However, this is optional.

[0106] In one embodiment, the slit 30 is formed by a perforated slit 40, preferably in a straight line. In another embodiment, the slit 30 is formed by a single straight line 42.

[0107] In another embodiment, the main layer 28 is provided with at least two intersecting slits 44. For example, the intersecting slits 44 may be in the form of a cross 46. For example, some of the slits 44 in the cross 46 may be angled relative to the longitudinal extension 38 of the laminated packaging material 16, as shown in the case of cross 48. In the case of cross 48, only one slit 44 (shown horizontally) is angled relative to the longitudinal extension 38 of the laminated packaging material 16. Furthermore, all the slits 44 of cross 46 may be angled relative to the longitudinal extension 38, as shown in the case of cross 50.

[0108] In some other embodiments, the slit 44 may be formed as Y-shaped 52a, Z-shaped 52b, or T-shaped 52c.

[0109] Finally, in two other embodiments, a partially circular slit 54 is provided. One embodiment has a slit 54 in the form of a single-discontinuous circle 56. The other embodiment has a slit 54 in the form of a double-discontinuous circle 58.

[0110] As can be seen from the above description, although various embodiments of the present invention have been described and illustrated, the present invention is not limited thereto, but may be implemented in other ways within the scope of the subject matter defined in the appended claims.

Claims

1. A laminated packaging material (16) for packaging liquid food (12), comprising: The package consists of a paper or paperboard or other cellulose-based material body layer (20), a first outermost liquid-tight layer (22) disposed on the outside of the body layer (20) to form the outside of a packaging container (10) formed of the packaging material (16), a second innermost liquid-tight layer (24) disposed on the inside of the body layer (20) to be in direct contact with the filled food (12), and a non-metallic barrier film or sheet (26) laminated between the body layer (20) and the second innermost liquid-tight layer (24), wherein the body layer (20) and the barrier film or sheet (26) together form a main layer (28), characterized in that the main layer (28) is provided with at least one slit (30) covered at least by the second innermost liquid-tight layer (24).

2. The laminated packaging material (16) according to claim 1, wherein the slit (30) is covered by the first outermost liquid-tight layer and the second innermost liquid-tight layer.

3. The laminated packaging material (16) according to claim 1 or 2, wherein the at least one slit (30) extends completely through the main layer (28).

4. The laminated packaging material (16) according to claim 1 or 2, wherein the barrier film or sheet (26) comprises a base layer (34) coated with a barrier material (32).

5. The laminated packaging material (16) according to claim 4, wherein the base layer (34) is made of plastic or paper or cellulose-based material.

6. The laminated packaging material (16) according to claim 1 or 2, wherein the main layer (28) is provided with at least two intersecting slits (30; 44).

7. The laminated packaging material (16) according to claim 1 or 2, wherein the slit (30; 44) is in the form of a cross (46).

8. The laminated packaging material (16) according to claim 7, wherein each slit (30; 44) of the cross (46; 50) is angled relative to the longitudinal extension (38) of the laminated packaging material (16).

9. The laminated packaging material (16) according to claim 6, wherein the slit (44) is in the form of a Y (52).

10. The laminated packaging material (16) according to claim 1 or 2, wherein The slit (30) described herein is in the form of a single straight line (42).

11. A method for manufacturing a laminated packaging material (16) for packaging liquid food (12), comprising: - Provide a body layer of paper or paperboard or other cellulose-based material (20), - A non-metallic barrier film or sheet (26) at least proportionally is laminated onto the body layer (20), such that the barrier film or sheet (26) and the body layer (20) form the main layer (28). - Provide at least one slit (30) for the main layer (28), and - The first outermost liquid-tight layer (22) is laminated onto the outside of the body layer (20) to form the outside of the packaging container (10) formed by the packaging material (16), and - A second innermost liquid-tight layer (24) is laminated on the inside of the barrier film or sheet (26) to be in direct contact with the filled food (12) such that the second innermost liquid-tight layer (24) at least covers the at least one slit (30) of the main layer (28).

12. The method of claim 11, wherein lamination of the first outermost liquid-tight layer (22) and the second innermost liquid-tight layer (24) is performed such that the first outermost liquid-tight layer (22) and the second innermost liquid-tight layer (24) cover the at least one slit (30) of the main layer (28).

13. The method according to claim 11 or 12, wherein the step of laminating the barrier film or sheet (26) to the body layer (20) is performed by extrusion lamination or wet lamination.

14. The method according to claim 11 or 12, further comprising printing a decorative layer (36) on the outside of the body layer (20) prior to providing the at least one slit (30) to the main layer (28).

15. The method according to claim 11 or 12, wherein the step of providing the at least one slit (30) for the main layer (28) is performed by laser cutting and / or by mechanical cutting.

16. The method according to claim 11 or 12, wherein, The at least one slit (30) extends along the longitudinal direction of the laminated packaging material (16).

17. A packaging container (10) comprising a laminated packaging material (16) according to any one of claims 1 to 10 and / or made by the method according to any one of claims 11 to 16.

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