Laminated packaging material, method for manufacturing laminated packaging material, and packaging container containing laminated packaging material

Abstract

The present invention relates to a laminate packaging material (10) for packaging oxygen-sensitive foods and a method for making the same, and further relates to a packaging container including the laminate packaging material for packaging oxygen-sensitive products such as foods.

Description

[Technical Field]

[0001] The present invention relates to a laminate packaging material comprising a bulk layer of cellulosic material such as paper or paperboard and at least one barrier layer or multi-layer barrier material portion, and a packaging container comprising the laminate packaging material for packaging aqueous liquid, semi-liquid or viscous food products. The present invention further relates to a method for producing the laminate packaging material. [Background technology]

[0002] Single-serve packaging containers for liquid foods are often manufactured from paperboard or carton-based packaging laminates. One such commonly used packaging container is sold under the trademark "Tetra Brik® Aseptic" and is primarily employed for the aseptic packaging of liquid foods, such as milk and fruit juice, that are sold for extended shelf life. The packaging material of this known packaging container is typically a laminate including a bulk or core layer of paper, paperboard, or other cellulose-based material and an outer liquid-tight layer of thermoplastic plastic. To make the packaging gas-tight, and particularly oxygen-tight, for aseptic packaging of, for example, milk or fruit juice, these packaging laminates typically include at least one additional layer, most commonly aluminum foil.

[0003] On the inside of the laminate, i.e., the side of the container made from the laminate intended to face the filled food contents, there is an innermost layer coated on the aluminum foil, which innermost layer comprises one or more sub-layers comprising adhesive polymers and / or heat-sealable thermoplastic polymers such as polyolefins, and outside the bulk layer there is an outermost heat-sealable polymer layer.

[0004] Packaging containers are typically produced by modern high-speed packaging machines that form, fill, and seal packages from webs of packaging material or prefabricated blanks. The packaging containers are produced by joining the longitudinal edges of a web of laminate packaging material together at overlap joints by welding together the inner and outer heat-sealable thermoplastic polymer layers and forming the web into a tube. The tube is filled with the desired liquid food product and then divided into individual packages by repeatedly transversely sealing the tube at predetermined distances from each other below the level of the contents within the tube. The packages are separated from the tube by scoring along the transverse seals and formed into the desired geometric shape, usually a parallelepiped, by scoring the packaging material along pre-prepared crease lines.

[0005] The main advantage of this continuous tube forming, filling and sealing packaging concept is that the web can be continuously sterilized just prior to tube formation, offering the possibility of an aseptic packaging process, i.e. a process in which the liquid contents to be filled and the packaging material itself are reduced from bacteria and the filled packages are produced under clean conditions so that they can be stored for long periods, even at ambient temperature, without risk of microbial growth in the filled product. Another important advantage of Tetra Brik® type packaging processes is that, as mentioned above, continuous high speed packaging is possible, which has a major impact on cost efficiency.

[0006] Packaging containers for sensitive liquid foods, such as milk or juice, can be manufactured from sheet blanks or pre-assembled blanks of the laminate packaging material of the present invention. Packages are manufactured from flat-folded tubular blanks of the packaging laminate by first assembling the blanks to form an open tubular container capsule, and then closing one open end of the container capsule by folding and heat-sealing an integral end panel. The closed container capsule is then filled with a food product, such as juice, through the other open end, and then closed by further folding and heat-sealing the corresponding integral end panel. Examples of packaging containers manufactured from sheet and tubular blanks include conventional gable-top packages. These types of packages also include those with molded plastic tops and / or screw caps.

[0007] The aluminum foil layer in packaging laminates provides significantly better gas barrier properties than other gas barrier materials. At their performance level, traditional aluminum foil-based packaging laminates for aseptic packaging of liquid foods are the most cost-effective and low-carbon-footprint packaging materials available on the market today. However, efforts are underway to replace aluminum foil with non-foil barrier materials to further reduce the carbon footprint. Aluminum foil barriers for liquid carton food packaging are typically 5-9 μm thick, with the most common being around 6 μm.

[0008] Other materials that compete with foil-based materials need to be cost-effective in terms of raw materials, have comparable food preservation properties, reduce carbon dioxide emissions, and require comparable low complexity in converting the material into the finished packaging laminate.

[0009] In the effort to develop non-aluminum foil materials for liquid food carton packaging, there is also a general motivation to develop pre-fabricated films or sheets with high or multiple barrier properties that can replace aluminum foil barrier materials in traditional laminate packaging materials or combine multiple separate barrier layers in laminate materials and be compatible with traditional processes for lamination and manufacturing.

[0010] Such non-aluminum foil, "non-foil" packaging laminates may be more sensitive to mechanical stresses and strains. Aluminum foil-based packages and materials may require additional mechanical robustness, especially for distribution and handling under harsh climatic and infrastructure conditions, or in connection with packages or packaging shapes having more demanding geometries.

[0011] A preferred type of alternative, more environmentally sustainable barrier material is a barrier-coated paper substrate, produced by aqueous dispersion coating or vapor deposition coating onto a thin paper carrier substrate. The barrier coatings obtained by wet aqueous dispersion coating or vapor deposition coating are very thin, measuring only a few microns in thickness, or in the case of vapor deposition coating, a double-digit nanometer scale. Such thin coatings are vulnerable to mechanical stress and strain, and additional protection from adjacent layers is beneficial. Furthermore, such thin barrier coatings are not as reliable as thick metal foils in preventing the migration or penetration of substances other than oxygen. Therefore, such barrier coatings must be complemented with a stronger polymer layer on the inside of the laminate packaging material, i.e., toward the product in the packaging container made from the packaging material.

[0012] International Publication WO 2011 / 003565 A1 discloses a non-aluminum foil laminate packaging material for liquid food carton packaging, which comprises a dispersion-coated and then metallized paper substrate that functions as both a barrier material and an induction-sensitive material, thereby replacing the conventional aluminum foil barrier. In addition to a stiff paperboard bulk layer, the laminate comprises an additional "paper barrier" material.

[0013] International Publication WO 2017 / 089508 A1 discloses that by selecting a paper substrate with optimal properties, barrier properties can be improved in a similar manner from metallized paper in similar carton-based packaging laminates. Such metallized paper substrates not only improve barrier properties but also the stability of the metallized layer in induction heat sealing applications.

[0014] International Publication WO 2011 / 088854 A1 discloses a different laminate packaging material for pouch-shaped liquid food packaging containers. This is based on a thinner bulk paper layer laminated to aluminum foil to provide, for example, gas and light barrier properties. Furthermore, it has an outer layer of thermoplastic polymer that includes a prefabricated polyethylene film on the inner polymer layer to improve mechanical robustness.

[0015] Paper-based barrier laminate packaging materials have great potential to replace aluminum foil-based packaging laminates for liquid and wet food carton packaging, but there is a need for further improvements to these and similar laminate packaging materials, for example in terms of increasing the recyclability and environmental sustainability of the materials used.

[0016] There is also a need to provide improved laminated paper-based materials for pouch packaging and other demanding carton laminate packaging formats for liquid, semi-liquid, and viscous foods, where such materials and barrier foils lack sufficient dimensional stability compared to conventional folded, cubic liquid carton packaging, which is subject to significant stresses and strains. Summary of the Invention [Problem to be solved by the invention]

[0017] It is therefore an object of the present invention to provide an improved laminate packaging material comprising a bulk layer of cellulosic material, such as paper or paperboard, and a layer of oxygen barrier material, for packaging oxygen-sensitive liquid foods, such as liquid, semi-liquid or viscous foods.

[0018] A further object is to provide a non-foil laminate packaging material for liquid, semi-liquid and viscous foods that has a thinner and more delicate material coating instead of aluminum foil and that requires good gas and other barrier properties and good mechanical robustness of the package made from the packaging material, but does not impair openability so that the packaged food can be easily accessed by the consumer.

[0019] A further object is to provide a paper or paperboard based laminated packaging material that offers good gas and water vapor barrier properties compared to aluminum foil based barrier materials and has a high proportion of recyclable and renewable (i.e. plant-based) material for producing easy-open packages for long-term aseptic storage of liquid foods.

[0020] A further specific object is to provide an improved paper-based laminate packaging material for pouch packages that has good barrier properties and good integrity and heat seal strength, and thus meets the requirements for long-term ambient storage of liquid foods, while still being releasable for consumer use.

[0021] These objects can be achieved according to the present invention by a laminated packaging material and a packaging container made from the laminated packaging material, as defined in the appended claims. [Means for solving the problem]

[0022] According to a first aspect of the present invention, there is provided a laminate packaging material for packaging liquid, semi-liquid or viscous food, the laminate packaging material comprising: a bulk layer of paper, paperboard or other cellulosic material; a first outermost liquid-tight heat-sealable layer comprising a thermoplastic polymer; a barrier layer or barrier multi-layer portion comprising at least one gas barrier material and arranged on the opposite inner side of the bulk layer; and a second innermost liquid-tight heat-sealable layer arranged on the inner side of the barrier layer or barrier multi-layer portion, the second innermost liquid-tight heat-sealable layer being oriented toward the inside of a package container formed from the packaging material, the second innermost liquid-tight heat-sealable layer being a pre-fabricated polyethylene film which is a cast biaxially oriented film and comprises 60 to 100% linear low density polyethylene, LLDPE, the pre-fabricated polyethylene film further comprising: - Total thickness is 15 to 25 μm, - Elastic modulus of at least 400 MPa in MD and at least 500 MPa in CD, measured according to ASTM D 882-02 (2018) at an initial strain rate of 0.1 mm / (mm*min) at a crosshead speed of 10 mm / min; - Tensile strength measured at a crosshead speed of 200 mm / min according to ASTM D638M-14 (2017) of 40 MPa or more in MD, e.g., 50 MPa or more, and 100 MPa or more in CD; - Elongation at break of 350% or less in MD and 100% or less in CD measured at a crosshead speed of 200 mm / min according to ASTM D638M-14 (2017); - The seal initiation temperature (SIT) measured at 2N according to ASTM F19211 (2018) is 80-100°C; - Maximum hot tack force measured according to ASTM F1921 (2018) is 7N or more; - Puncture resistance of 10 N or greater measured at a crosshead speed of 500 mm / min according to ASTM F1306-16 (2016).

[0023] The prefabricated polyethylene film may have a core layer comprising greater than 60% by weight m-LLDPE and a first "skin" layer on one side of the core layer that also comprises m-LLDPE and is more compatible with heat sealing of the film than the polyethylene polymer of the core layer; and optionally, the prefabricated polyethylene film has a second skin layer on the other side of the core layer.

[0024] The laminate packaging material defined in accordance with the present invention is particularly well suited for liquid carton packaging under demanding conditions, such as when thin, delicate gas barrier coatings are relied upon for oxygen barrier performance instead of conventional aluminum foil. It also generally significantly improves package integrity and barrier performance, thereby particularly meeting the needs of more demanding packaging formats. An example of such a more demanding packaging format is a liquid pouch container, which lacks the dimensional stability provided by a thick paperboard bulk layer; i.e., it is constructed solely of thin paper as a bulk or core layer, and has no or very low inherent bending stiffness. Another example of a demanding packaging format is a package with a volume greater than 1 liter, such as a 2-liter or half-gallon package. Even more demanding packaging formats include folded and formed packaging formats with higher strain and more severe fold points. Pouch containers and other such large or multi-folded liquid-filled packages are naturally subjected to greater forces and strains during handling and distribution, as the flowable food contents or liquids move independently of the package itself during transport, lifting, unloading and handling.

[0025] However, it has been known that the inclusion of pre-fabricated films in liquid carton packaging laminates, such as pre-cut laminate holes for beverage straws, screw corks and other opening devices, or tear perforations, can simply make the laminate material too strong from an openability perspective, resulting in problems with the openability of the resulting package. In the laminate packaging material of the present invention, the properties of package integrity, protection of sensitive barrier materials, and package openability are unexpectedly improved and are not simply optimized but balanced with each other to provide an acceptable compromise. By integrating these conflicting properties in liquid carton packaging containers, the advancement and development of such laminate packaging materials has significantly advanced toward sustainable yet durable packaging materials for aseptic, long-term packaging of liquid foods.

[0026] The pre-manufactured polyethylene film may be laminated to the barrier layer or barrier multilayer portion by a second adhesive layer of thermoplastic polymer, which may provide further improved mechanical robustness and protective properties to the complete laminate structure of the packaging material.

[0027] An example of the aforementioned "non-foil" laminate packaging material, where a thin, delicate gas barrier coating is required, is a material in which the barrier multilayer portion comprises a paper substrate to which is applied at least one coating of a gas barrier material having a thickness of 2 to 5000 nm (5 μm). Such non-foil laminate packaging materials provide more environmentally sustainable and recyclable packaging materials.

[0028] Typically, the use of a barrier-coated paper substrate instead of aluminum foil in such laminates and packaging allows for a higher proportion of fiber content that is renewable, i.e., of non-fossil origin, can be redispersed into pulp and recycled, and allows the use of old material in the manufacture of new products, as required by the circular economy for fiber materials.

[0029] According to a second aspect of the present invention, there is provided a method for producing the laminate packaging material of the first aspect, comprising the steps of, in any order, laminating a continuous web of bulk layer of paper, paperboard or other cellulosic material to the outside of a continuous web of barrier layer or barrier multilayer portion comprising at least one gas barrier material; on the inside of the other of the webs of barrier layer or barrier multilayer portion, laminating a continuous web of pre-manufactured inner polyethylene film as defined in the first aspect as a second, innermost liquid-tight, heat-sealable layer with an adjacent second tie layer of tie polymer, such as by melt extrusion lamination; and extrusion coating the outside of the bulk layer with a first, outermost liquid-tight, heat-sealable layer.

[0030] According to a third aspect of the present invention, there is also provided a packaging container for packaging liquid, semi-liquid or viscous food products, comprising the laminate packaging material of the first aspect. The packaging container is at least partially manufactured from the laminate packaging material, and according to a further embodiment, is manufactured entirely from the laminate packaging material. The packaging container formed from the laminate packaging material can be partially sealed, filled with a liquid or semi-liquid food product, and then sealed by sealing the packaging material itself, optionally in combination with a plastic opening or top of the package.

[0031] (Detailed explanation) The term "long-term shelf life" as used in connection with the present invention means that the packaging container is capable of preserving the quality of the packaged food, i.e., nutritional value, hygienic safety and taste, for at least 1 or 2 months, such as at least 3 months, preferably 6 months, such as 12 months or more, at ambient temperature conditions.

[0032] The term "sterile" in relation to packaging materials and containers refers to a state in which microorganisms have been removed, inactivated, or killed. Examples of microorganisms include bacteria and spores. Generally, an aseptic process is used when a product is aseptically filled into a packaging container. The integrity characteristics of the package are very important to maintain the sterility throughout the shelf life of the package. For the long-term storage of the packaged food, and to preserve the original taste and nutritional value, e.g., vitamin C content, it is important to have a barrier against gases and vapors, such as oxygen gas.

[0033] The term "bulk layer" generally refers to the thickest layer or the layer containing the most material in a multi-layer laminate, i.e., the layer that contributes most to the mechanical properties and dimensional stability of the laminate and the packaging container folded from the laminate, such as paperboard or carton. It can also refer to the layer that provides a greater thickness distance in a sandwich structure, which further interacts with stabilizing opposing layers having a higher Young's modulus on either side of the bulk layer to achieve sufficient mechanical properties, such as bending stiffness, to achieve structural stability of the formed packaging container.

[0034] The term LLDPE covers all linear low-density polyethylenes, including "ZN-LLDPE" polymerized with Ziegler-Natta type catalysts, "m-LLDPE" polymerized with so-called "constrained geometry" or "single-site" catalysts (such as "metallocene" catalysts), and other linear low-density polyethylenes.

[0035] As used herein, the term "dispersion coating" refers to a coating technique in which an aqueous or substantially aqueous dispersion, suspension, emulsion, or solution of a polymer is applied to the surface of a substrate layer, usually in the form of a continuous web, to form a solid, substantially non-porous coating after drying. The term "dispersion" therefore also includes solutions, suspensions, emulsions, solutions, or mixtures thereof that are capable of providing such a coating after drying. Polyvinyl alcohol (PVOH, PVAL) is a typical polymer suitable for dispersion coating, but, for example, with a high degree of saponification, it may actually be a polymer solution or a mixture of dispersed and dissolved PVOH. Dispersion-coated barrier layers or coatings are formed by a dispersion coating technique also known as "liquid film coating." The aqueous dispersion consists of fine polymer particles and may be a latex.

[0036] The paper basis weight is measured in g / m according to the official test method of ISO 536:2019. 2 and thickness and density are measured in accordance with ISO 534:2011 in units of μm (m) and kg / m 3 was measured.

[0037] The thickness of the polymer layer coated on the paper can be measured and estimated by taking a cross-sectional slice of the structure and examining it under a SEM microscope. Slicing can be performed using a cryomicrotome, for example.

[0038] The term "package integrity" generally refers to the tightness of the package, i.e., the resistance of the package to leakage or breakage. This term encompasses the resistance of the package to the ingress of microorganisms such as bacteria, dirt, and other substances that may deteriorate the food product contained therein and shorten the expected shelf life of the package.

[0039] One major contribution to the integrity of a laminate packaging material comes from good internal adhesion between adjacent layers of the laminate material. Another contribution comes from the material's resistance to defects such as pinholes within each layer itself, and yet another comes from the strength of the seal joints where the materials are sealed together to form the package. The integrity of the laminate packaging material itself is primarily focused on the adhesion between each laminate layer and its adjacent layers and its ability to withstand thermal and mechanical stresses, such as folding and sealing, without rupturing the material or substantially reducing its thickness. With regard to the sealing of the package, integrity primarily focuses on the quality of the seal joints, which are ensured by a well-functioning, robust sealing operation in the filling machine, and which are further ensured by the laminate packaging material's properly matched heat-sealing properties.

[0040] "Liquid or semi-liquid food" generally refers to food that is flowable and optionally contains food particles. Liquid foods include water. Non-limiting examples of contemplated foods include dairy, milk, soy, rice, grain, and seed-based beverages, juice, nectar, carbonated drinks, water, flavored water, energy drinks, sports drinks, coffee and tea beverages, coconut water, wine, soup, jalapeños, tomatoes, sauces (e.g., pasta sauce), and olive oil.

[0041] Thus, the laminate packaging material of the present invention comprises a bulk layer of paper or paperboard or other cellulosic material, with a barrier layer or multi-layer barrier portion laminated between the bulk layer and a second, innermost, liquid-tight, heat-sealable layer facing the inside of a container formed from the laminate packaging material.

[0042] Suitable paper or paperboard bulk layers have thicknesses of from about 100 μm to about 650 μm and weights of from about 100 to about 520 g / m 2 , preferably about 150 to about 300 g / m 2The bulk layer may have a surface weight of 1000 psi and may be conventional paper or paperboard of suitable packaging quality. The purpose of the bulk layer in the laminate packaging material of the present invention is to provide dimensional stability, stiffness, and rigidity to the packaging container, for example, for use under wet and humid conditions and / or for storage of liquid and wet (heavy) foods. The preferred bending stiffness is 80 mN.

[0043] For low-cost, long-term packaging of liquid foods in a sterile manner, thinner packaging laminates with thinner paper core layers may be used. Packages made from such packaging laminates are formed into flexible, pillow-shaped pouches rather than foldable pouches. Suitable papers for such pouch packages range from about 50 to about 140 g / m 2 , preferably about 70 to about 120 g / m 2 , more preferably about 70 to about 110 g / m 2 It may have a surface weight of 150 g / m 2 Above this, the bending stiffness is too high for a pouch.

[0044] The barrier layer or barrier multilayer may be laminated to the bulk layer by a first adhesive layer of one or more polymers, such as a thermoplastic polymer, such as a polyolefin.

[0045] Thus, the barrier layer or multi-layer barrier section can be bonded to the bulk layer by an intermediate adhesive polymer or binder, or by a thermoplastic polymer as a first tie layer. According to one embodiment, the first tie layer is a polyolefin layer, such as a layer of a polyethylene-based polyolefin homopolymer, copolymer, or blend containing a majority of ethylene monomer units. The first tie layer can be bonded to the bulk layer or multi-layer barrier section by melt-extrusion laminating the first tie polymer layer between a web of the bulk layer and a web of barrier material, and simultaneously pressing the three materials together while advancing the laminate web through a lamination roller nip, thus providing a laminate structure by extrusion lamination. Such melt-extrusion lamination is suitable for most barrier layer or multi-layer barrier section selections, and sufficient adhesion between the adhesive material layers can be achieved and maintained.

[0046] In a further embodiment in which the multilayer barrier section is a barrier-coated cellulose-based substrate, such a paper-based or cellulose-based barrier material may be adhered to the bulk layer by wet-applying an aqueous dispersion composition containing an adhesive polymer binder to one surface of the webs to be laminated and pressing the two webs together while advancing them through a lamination roller nip, thus providing a laminate structure by wet lamination. The moisture in the aqueous adhesive composition is absorbed into the fibrous cellulose network of the two paper layers and partially evaporates over time during the subsequent lamination process. Therefore, no forced drying step is required. The adhesive polymer binder can be selected from the group consisting of acrylic polymers and copolymers, starch, cellulose and polysaccharide derivatives, and polymers and copolymers of vinyl acetate and vinyl alcohol. For the best possible environmental and sustainability profile, plant-derived or non-fossil-derived adhesive binders are preferred for the first adhesive layer in this case.

[0047] In one embodiment, the barrier coated paper substrate is coated with 0.5 to 5 g / m of a contiguous adhesive composition comprising a binder selected from the group consisting of acrylic polymers and copolymers, starch, starch derivatives, cellulose derivatives, polymers and copolymers of vinyl acetate, copolymers of vinyl alcohol, and copolymers of styrene-acrylic latex or styrene-butadiene latex. 2 The adhesive composition can be laminated to the bulk layer by wet lamination. Such low amounts of contiguous adhesive composition can be applied by aqueous dispersion or solution coating of the polymer binder, and cannot be applied by extrusion coating or extrusion lamination of a polymer melt to achieve sufficient melt adhesion. Such wet lamination is accomplished by absorption of an aqueous medium into each cellulose layer, since both surfaces of the layers to be bonded are made of cellulose, resulting in the formation of a thin, dry adhesive layer at the interface of the two layers.

[0048] Therefore, lamination of the bulk layer onto the barrier layer or multilayer barrier section is carried out by applying an aqueous dispersion of an adhesive composition containing an adhesive polymer binder onto the web of the bulk layer or onto the web of the barrier layer or multilayer barrier section in an amount of 1 to 5 g / m2 in dry weight. 2 and pressing the two webs together while advancing them through a lamination roller nip without forcing them to dry.

[0049] The outermost and innermost liquid-tight layers of thermoplastic polymers, as well as the laminate layers within the laminate structure, typically do not add appreciable barrier properties to migrating gas molecules or small molecules. Their purpose is to act as a direct barrier to prevent water and other liquids from penetrating through the cellulosic bulk material and other sensitive layers, and as a sterility barrier that maintains the integrity of the package to protect the filled contents within. Liquid barrier layers also prevent water vapor migration to the extent that the cellulose becomes wet, but they cannot maintain the moisture content of the laminate structure at zero or the low levels of "dry" paper (approximately 7-8% at ambient temperature, i.e., 23°C and 50% relative humidity). The moisture content in laminate carton materials for liquid-filled packaging containers is typically quite high, and migration will occur through the material unless an additional water vapor barrier is included, such as aluminum foil, vapor-deposited metal layers, other vapor-deposited coatings, inorganic material layers, or other polymeric material layers.

[0050] Suitable thermoplastics for the outermost liquid-tight layer are polyolefins such as homopolymers or copolymers of polyethylene and polypropylene, preferably polyethylene, more preferably polyethylene selected from the group consisting of low-density polyethylene (LDPE), linear LDPE (LLDPE), single-site catalyst metallocene polyethylene (m-LLDPE), and blends or copolymers thereof. According to one embodiment, the outermost liquid-tight layer is LDPE.

[0051] The outermost liquid-tight polymer layer is approximately 5 to 15 g / m² of the bulk layer. 2 , e.g., 8 to 15 g / m 2 It can be applied with

[0052] The same thermoplastic polyolefin-based materials, particularly polyethylene, suitable for the outermost layer are also suitable for the adhesive layer within the laminate material, i.e., between a bulk or core layer, such as paper or paperboard, and an additional barrier layer or multilayer barrier film or sheet. In one embodiment, the first adhesive layer may be a simpler or more conventional polyethylene layer, such as a low-density polyethylene (LDPE) layer. In another embodiment, the internal adhesive layer between the bulk layer and the barrier layer may have a three-part layer configuration, with the center layer being linear polyethylene and the side layers being LDPE. Thus, three layers are coextrusion laminated between the bulk layer and the barrier layer, with the center layer preferably being metallocene-polymerized mLLDPE and the side layers being LDPE.

[0053] The prefabricated polyethylene film, which constitutes the second, innermost liquid-tight, heat-sealable layer, may be laminated to the barrier layer or barrier multilayer portion by a second tie layer of a thermoplastic polymer such as a polyolefin, such as polyethylene or a polyethylene-based copolymer or graft copolymer, having functional groups for adhesively bonding to adjacent layers in the laminate.

[0054] Thus, suitable first and second adhesive layers or additional bonding layers within a laminate material, such as between a bulk or core layer and a barrier-coated paper substrate, or between a prefabricated polyethylene film and a barrier layer, may be so-called adhesive thermoplastic polymers, such as adhesive polyolefins based on LDPE or LLDPE copolymers or graft copolymers containing functional group-containing monomer units, such as carboxyl or glycidyl functional groups. For example, (meth)acrylic acid monomers or maleic anhydride (MAH) monomers (i.e., ethylene-acrylic acid copolymer (EAA) or ethylene-methacrylic acid copolymer (EMAA)), ethylene-glycidyl (meth)acrylate copolymer (EG(M)A), or MAH-grafted polyethylene (MAH-g-PE). Other examples of such adhesive polymers are so-called ionomers or ionomeric polymers. Preferably, the adhesive polyolefin is ethylene-acrylic acid copolymer (EAA) or ethylene-methacrylic acid copolymer (EMAA).

[0055] In another embodiment, a pre-fabricated polyethylene film may be laminated to a barrier layer or multilayer barrier section by so-called solventless lamination, using a very thin layer of a curable adhesive. Examples of such curable adhesives are based on polyether, polyester, acrylic, or polyurethane binder compositions. These may be applied as a primer onto the polymer film or substrate to be laminated. Curing of the applied adhesive composition may be induced by a variety of methods, including moisture from the environment, heat, or radiation energy.

[0056] In one embodiment, the laminate packaging material has a density of 100 to 520 g / m 2 , for example, 150 to 300 g / m 2 and a barrier multilayer portion, the barrier multilayer portion comprising a paper substrate coated with at least one coating of a gas barrier material of 2 to 5000 nm (0.002 to 5 μm) to provide a more environmentally sustainable and recyclable packaging material.

[0057] In a further embodiment, which can be combined with the above-described embodiment, a pre-fabricated polyethylene film is laminated to the barrier layer of the multi-layer barrier section by melt extrusion lamination of an adjacent co-extruded film of adhesive polymer directed towards the barrier layer and a layer of LDPE polymer directed towards the pre-fabricated polyethylene film. Preferably, the second adhesive layer thus melt co-extruded consists of an ethylene acrylic acid (EAA) "tie" layer and a thicker LDPE layer. The EAA tie layer may be, for example, 3-6 g / m 2 The LDPE adhesive layer may be applied in an amount of 10 to 20 g / m 2 may be applied in an amount of

[0058] In the gas barrier coated paper substrate for the gas barrier material in the laminate packaging material of the present invention, the upper surface of the thin paper substrate has at least one coating of at least one gas barrier material in a total coating thickness of 2 to 5000 nm (5 μm), for example, 2 to 4000 nm (4 μm). Such a thin coating does not generate rejects or waste when used laminate packaging materials containing such a coating are recycled in conventional cellulose fiber recycling streams, and does not require a large amount of material for the benefits such a coating provides.

[0059] The paper substrate is relatively thin, e.g., 30 to 75 g / m 2 It has a basis weight of 900 kg / m² and has properties suitable for applying thin gas barrier and other barrier coatings. To obtain good barrier coating quality, the top surface to be coated must have a high smoothness, i.e., a low surface roughness. This can be achieved by the paper itself or by applying a base coat and / or impregnating the paper substrate. Furthermore, the paper substrate has a sag of 900 kg / m². 3 Such high density is beneficial.

[0060] At least one gas barrier coating may be formed by applying a dispersion or solution of an aqueous composition of at least one gas barrier material, followed by drying. The gas barrier coating applied in this manner forms a continuous, uninterrupted layer of the gas barrier material on the surface of the paper substrate. This may be facilitated by impregnating or basecoating the paper substrate with an impregnating polymeric material composition or a basecoating polymeric material composition. The impregnated or basecoated paper substrate may have a smoother and / or denser surface, allowing the subsequently applied gas barrier coating to be applied at a much lower thickness, yet still with high coating quality, achieving a uniform surface and thickness, and exhibiting homogeneity throughout its thickness and in the lateral extent of the continuous coating layer.

[0061] The top side of the paper substrate may, according to one embodiment, be coated with a polymeric gas barrier material to a dry coating thickness of 100-5000 nm (0.1-5 μm), for example 100-4000 nm (0.1-4 μm), for example 300-3500 nm (0.3-3.5 μm), for example 300-2500 nm (0.3-2.5 μm).

[0062] The gas barrier material may comprise a polymer selected from the group consisting of a vinyl alcohol polymer or copolymer, such as polyvinyl alcohol, PVOH, or ethylene vinyl alcohol, EVOH, and a polysaccharide or polysaccharide derivative. Suitable polysaccharides or polysaccharide derivatives may be selected from the group consisting of starch, starch derivatives, chitosan, chitosan derivatives, cellulose, cellulose derivatives, and lignocellulosic compounds. In one embodiment, the polymer is of renewable (i.e., non-fossil-based) origin.

[0063] In more specific embodiments, the gas barrier material may comprise a polymer selected from the group consisting of vinyl alcohol polymers and copolymers, such as polyvinyl alcohol, PVOH, and ethylene vinyl alcohol, EVOH, starch and starch derivatives, xylan, xylan derivatives, nanofibril cellulose / microfibril cellulose, NFC / MFC, nanocrystalline cellulose, NNC, and blends of two or more thereof.

[0064] According to another embodiment, the gas barrier material may be a water-dispersible polyamide or polyester, or polyvinylidene chloride. Preferably, such water-dispersible polyamide, polyester, or polyvinylidene chloride is bio-based and / or can be applied at very low coating weights, i.e., less than 1 g / m 2 It is possible to provide oxygen gas barrier properties with only a very thin coating amount of 1.5 μm or less, and the purpose is to provide a gas barrier material that can be recycled in the cellulose fiber recycling stream without leaving behind an undesirable amount of waste, i.e., so-called "rejected products."

[0065] Such thin coatings are obtained by dispersion or solution coating of the gas barrier material contained in the water gas barrier composition, followed by drying, and cannot be applied at such thin coating thicknesses by other methods, such as extrusion coating. Polymers and materials can also be applied as solutions or dispersions in organic solvents other than water, but such methods are generally not relevant to providing environmentally sustainable packaging materials of the future.

[0066] In a preferred embodiment, the amount is 0.5 to 3.5 g / m 2 , e.g., 1 to 3 g / m 2 A coating of PVOH is applied to the top surface of the paper substrate.

[0067] Furthermore, when the gas barrier material coating is formed by coating a dispersion or solution of the gas barrier composition and then drying it, it may further contain a layered compound such as nano-dimensional layered clay, talcum, or CaCO3.

[0068] The polymer for the impregnation or base coat may be selected from starch, starch derivatives, carboxymethyl cellulose, CMC, or other cellulose ethers, and may be applied in an amount of 0.5 to 4 g / m 2 , e.g., 0.5 to 3 g / m 2 , for example, 0.5 to 2 g / m 2 , for example, 0.5 to 1.5 g / m 2 The gas barrier coating may then be applied as a continuous, uninterrupted coating on top of the impregnated or base-coated paper to a total thickness of 2 to 4000 nm (4 μm), for example 2 to 3000 nm (3 μm).

[0069] The paper substrate thus gas-barrier coated may further have a vapor-deposited coating of a gas-barrier material selected from metals, metal oxides, inorganic oxides, and amorphous diamond-like carbon coatings on the upper coated surface. More specifically, the vapor-deposited coating may be selected from the group consisting of aluminum vapor-deposited coatings and aluminum oxide (AlOx). Preferably, the vapor-deposited coating is aluminum.

[0070] The coated paper substrate with the gas barrier material coating may be further subsequently coated by vapor deposition coating to a thickness of 2 to 200 nm, for example 2 to 150 nm, for example 2 to 100 nm, for example 5 to 80 nm, for example 5 to 50 nm, for example 2 to 45 nm.

[0071] A coated paper substrate may further be provided, the back side of which may be coated and / or impregnated with at least one coating of at least one gas barrier material as defined in any of the above embodiments.

[0072] The vapor-deposited barrier coating that is ultimately applied on top of the paper substrate is applied by physical vapor deposition (PVD) or chemical vapor deposition (CVD), such as plasma-enhanced chemical vapor deposition (PECVD).

[0073] Generally, below 5 nm the barrier properties may be too low to be useful, and above 200 nm, e.g., above 100 nm, e.g., above 50 nm, depending on the type of vapor-deposited coating, the flexibility of the barrier coating may be reduced, resulting in increased susceptibility to cracking when applied to flexible substrates and increased cost.

[0074] Other examples of vapor-deposited coatings include aluminum oxide (AlOx, Al2O3) and silicon oxide (SiOx) coatings. Generally, PVD coatings of such oxides may not be well suited for incorporation into packaging materials by lamination, whereas metallized layers such as those produced by PVD are very suitable for flexible packaging laminates.

[0075] Typically, aluminum vapor deposition layers have a thin surface portion that consists essentially of aluminum oxide due to the nature of the metal vapor coating process used.

[0076] The purpose of aluminum vapor deposition coatings and aluminum oxide coatings is to provide oxygen barrier properties. Alternatively, they may provide primarily water vapor barrier properties to protect the inherent oxygen barrier properties of other initially applied coatings. Coatings applied as aqueous dispersions of gas barrier polymers and then dried are often moisture-sensitive, such that oxygen barrier properties decrease as the moisture content in the laminate layer increases. Applying a metal vapor deposition layer over such moisture-sensitive coatings can effectively protect the dispersion-coated coating against moisture migration from wet or liquid food within the packaging container. Therefore, it is important that the metal vapor deposition coating completely covers the underlying oxygen barrier coating and remains intact during lamination and folding operations, so that the filled package maintains effective barrier properties against migration of not only water vapor but also oxygen.

[0077] In one embodiment, such an aluminum vapor-deposited layer is applied to an optical density (OD) of 1.8 to 4, preferably 1.9 to 3.5. If the optical density is lower than 1.8, the barrier properties of the metal vapor-deposited film may be too low. On the other hand, if the metal thickness is too high, the metal vapor-deposited layer may become brittle, and the heat load during long-term metal vapor deposition of the substrate film increases, resulting in low heat resistance during the metal vapor deposition process. This may adversely affect the quality and adhesion of the coating. In one embodiment, in terms of flexibility of the applied metal vapor-deposited coating and coating operation efficiency, the metal vapor-deposited coating is applied to a thickness of 10 to 200 nm, for example, 10 to 150 nm, for example, 10 to 100 nm, for example, 10 to 95 nm, for example, 10 to 80 nm, for example, 10 to 50 nm, which corresponds to less than 1 to 3% of the aluminum metal material present in aluminum foil of a conventional thickness for packaging, such as 6 to 9 μm.

[0078] Other coatings may be applied by plasma-enhanced chemical vapor deposition (PECVD), in which vapors of compounds are deposited on the substrate in a more or less oxidizing environment. For example, silicon oxide coatings (SiOx) may also be coated using the PECVD process, and can achieve very good barrier properties under certain coating conditions and gas recipes.

[0079] DLC defines a type of amorphous carbon material (diamond-like carbon) that exhibits some of the typical properties of diamond. Preferably, hydrocarbon gases such as acetylene or methane are used as the plasma process gas for producing the amorphous hydrogenated carbon barrier layer coating, i.e., DLC, applied by PECVD vacuum process. DLC coatings applied by PECVD under vacuum provide good adhesion to adjacent polymer or adhesive layers in laminate packaging materials. In particular, polyolefins, especially polyethylene and polyethylene-based copolymers, provide good adhesion to adjacent polymer layers.

[0080] Further coating layers may be applied for the common purpose of improving the oxygen barrier properties of the barrier-coated paper, such as further topcoats or basecoats for vapor deposition coatings.

[0081] The total applied thickness of the continuous, uninterrupted gas barrier coating may be up to 5 μm, such as 4 μm, for example 3.5 μm.

[0082] In another embodiment, the laminate packaging material has a density of 70 to 140 g / m for the production of a pouch package. 2 , for example, 70 to 120 g / m 2 , for example, 70 to 110 g / m 2 and a barrier layer of aluminum foil.

[0083] In demanding packaging formats such as pouch packages and larger than normal packaging containers, the traditional aluminum foil barrier layer may require the additional support of a pre-fabricated polyethylene film as the innermost liquid-tight, heat-sealable layer.

[0084] Further alternative sensitive barrier layers and materials can include polymeric barrier materials such as melt-extrusion grades of polyamides and vinyl alcohol copolymers, such as ethylene vinyl alcohol and EVOH. While these polymeric barrier materials can be applied as thick barrier layers by melt extrusion, they are susceptible to fold distortion and degradation during heat-sealing and other processes. Therefore, even in laminate packaging materials consisting solely of a single barrier layer of polyamide or EVOH, the use of certain pre-fabricated polyethylene films as the innermost liquid-tight, heat-sealable layer significantly improves the properties of the laminate packaging material in all aspects, including package integrity and ease of opening.

[0085] Until now, balancing package integrity and openability in demanding packaging materials and containers has been difficult, and to achieve sufficient openability, cumbersome solutions have been developed for materials related to tear holes and perforations, such as pre-cutting or perforating in a single layer or other pre-treatment of material layers. Such difficulties have always been prominent in relation to the use of bidirectional polymer film substrates for stable support of thin vapor-deposited gas barrier coatings, and therefore, the inclusion of such additional, or non-barrier-related, bidirectional pre-manufactured films in laminate materials has not been given much consideration until now. For many years, only blown films pre-manufactured by film-blowing processes have been considered for the innermost or inner polymer layer portion of laminate materials. Thus, the specific selection of films for the laminate packaging material of the present invention has brought about significant advances in several respects, including openability.

[0086] Thus, a pre-manufactured polyethylene film suitable as the innermost layer of a laminate packaging material is cast instead of blown and contains 60-100% by weight of linear low density polyethylene such as LLDPE, e.g., m-LLDPE; The total thickness is 15 to 25 μm. - Elastic modulus of at least 400 MPa in MD and at least 500 MPa in CD, measured at an initial strain rate of 0.1 mm / (mm*min) according to ASTM D 882-02 (2018); - Tensile strength of 40 MPa or more, e.g., 50 MPa or more, in the MD and 100 or more in the CD, measured according to ASTM D638M-14 (2017) at a crosshead speed of 200 mm / min; - Elongation at break of 350% or less in MD and 100% or less in CD, measured according to ASTM D638M-14 (2017) at a crosshead speed of 200 mm / min; - Seal initiation temperature SIT of 80-100°C measured at 2N according to ASTM F19211 (2018), - Maximum hot tack force of 7N or more, measured according to ASTM F1921 (2018) - Puncture resistance of 10 N or more, measured according to ASTM F1306-16 (2016) at a crosshead speed of 500 mm / min; It is preferable that the film is subjected to biaxial stretching such as axial stretching.

[0087] Preferably, the prefabricated polyethylene film has a core layer comprising greater than 60% by weight of m-LLDPE, and a first "skin" layer on one side of the core layer, also comprising m-LLDPE, that is more adapted to heat-sealing the film than the polyethylene of the core layer; and optionally, the prefabricated polyethylene film has a second skin layer on the other side of the core layer. The LLDPE of the heat-sealable skin layer may be further adapted to improve the heat-sealing properties of the film by having a higher melt flow rate (i.e., melt index) and lower density than the LLDPE of the core layer.

[0088] Thus, the primary LLDPE polymer in a prefabricated polyethylene film may be m-LLDPE, a linear low-density polyethylene produced by metallocene-type catalytic polymerization technology (constrained geometry, single-site). While m-LLDPE is preferably used in the core layer, other layers, such as skin layers, may suitably comprise Ziegler-Natta LLDPE.

[0089] Pre-manufactured polyethylene films are polyethylene-based films, but may contain small amounts of polyolefin compounds, such as ethylene and propylene copolymers, to adjust various film properties.

[0090] LLDPE for cast films, such as the core layer of a cast film, may have a melt flow rate / melt flow index (MFR / MFI) of 2-5 g / 10 min at 2.16 kg and 190°C, as measured according to ASTM D1238 or ISO 1133. On the other hand, the primary LLDPE base for blown films has a melt flow ratio of 1 or less to meet the requirements of the film-blowing manufacturing process. This may result in significant differences in the polymer's suitability for prefabricated heat-sealable films for the innermost layer, making cast biaxially oriented films more suitable for such heat-sealable films. This may also be reflected in the fact that blown films typically require an additional extrusion-coated polyethylene layer on the innermost layer, i.e., the inner side of the blown film, to be heat-sealed and in contact with the filled food product.

[0091] Examples of LLDPE suitable for the core layer include those with a melting index of 1 to 4 g / 10 min (measured at 190°C and 2.13 kg) and a density of 0.915 to 0.930 g / cm 3 Examples of such polysaccharides include those having a melting peak in the range of 90 to 138°C.

[0092] The LLDPE of the first (sealant side) skin and tie layers may have a higher melt index and lower density than the LLDPE of the core layer and / or any second skin and tie layers to enhance sealant side heat sealability and avoid visual distortion and rheological defects due to sealing.

[0093] The sealability of the film can be optimized by further adapting the heat-sealable skin layer to further preserve and provide the film with a low seal initiation temperature and high hot tack strength. Because the film blowing process and the type of polymer used therein cause the film layers to vary considerably in thickness within the film's planar extension, blown films must be significantly thicker to achieve sufficient and reliable heat-sealability properties. Because film thickness adaptability is better in biaxially oriented cast films, such films containing heat-sealable skin layers can be made thinner, for example, by increasing the orientation of the film's layers. Thus, the heat-sealable portion or layer of the film may be as thin as a "skin" layer, 0.5 to 3 μm, e.g., 1 to 3 μm, and the total film thickness may be as low as 16 to 20 μm.

[0094] Preferably, the prefabricated polyethylene film has a stretch ratio of 5 to 7 in the machine direction (MD) and a stretch ratio of 7 to 10 in the cross direction (CD). Thus, the degree of orientation of the polymer in the film, i.e., the degree of stretch, is very high, especially compared to blown films and even compared to many cast biaxially oriented films, with an unusually high CD to MD orientation ratio. Such stretching is achievable using a tenter frame apparatus. The high degree of stretching is reflected in the film's properties, such as significantly higher tensile strength and lower elongation at break in the CD. Such films are produced, for example, on bidirectional lines such as those described in U.S. Pat. No. 8,080,294.

[0095] Preferably, the pre-manufactured polyethylene film has a total thickness of 16 to 23 μm, for example 16 to 20 μm. For the openability of the laminated packaging material, it is important that the biaxially oriented film is not too thick, while maintaining good mechanical properties as described above.

[0096] In one embodiment, the core layer of pre-fabricated polyethylene film has a thickness of 10 to 18 μm, such as 10 to 16 μm, for example 10 to 14 μm.

[0097] Preferably, the core layer comprises 80 to 100% by weight of LLDPE polymer, for example m-LLDPE, more preferably 90 to 100% by weight, for example 90% or more by weight of LLDPE, for example preferably m-LLDPE.

[0098] In a further embodiment, the thickness of the first skin layer and optional second skin layer is 0.5 to 3, e.g., 1 to 3, e.g., 2 to 3 μm. Preferably, the film has one skin layer on each side of the core layer for optimal film stability and mechanical symmetry, thereby avoiding phenomena such as film curl. The polymer of the optional skin layer need not be specifically adapted to any properties, but is preferably adapted to the mechanical and melt-processability properties of the core and heat-sealable skin layers. This may include an LDPE polymer and, optionally, an LLDPE polymer of the same or different type as that contained in the core layer. The surface of the optional skin layer may be adapted or treated, for example, to optimize adhesion or friction properties.

[0099] The prefabricated polyethylene film may be provided with an additional thin layer, the so-called tie layer, to more firmly bond the skin layer to the core layer, which may contain the same or a different polymer type as that used in the core layer. The thickness of the tie layer is usually in the range of 0.50 to 25 μm.

[0100] The pre-manufactured polyethylene film may further contain additives such as antiblocking agents (such as zeolites or silicates), anti-slip agents (such as erucamide, silicone gum or PMMA), hydrocarbon resins or other polymer compounds to further improve the quality and processability of the film. The skin layer on the sealant side may contain a higher concentration of antiblocking agent than the other layers.

[0101] In another embodiment, the optional second skin layer comprises an adhesive polymer, e.g., an ethylene-based polymer with functional carboxyl groups, such as a copolymer of ethylene and (meth)acrylic acid, which can improve adhesion and bonding with adjacent layers, i.e., layers that are subsequently laminated or coated. Such films can be heat-pressurized laminated to a metal foil layer without applying an adhesive between the skin layer and the surface of the metal layer.

[0102] In one embodiment, the prefabricated polyethylene film has a seal initiation temperature (SIT) of 80-95°C, e.g., 80-90°C, as measured at 2N according to ASTM F1921 (2018). This is achieved, at least in part, by an adapted heat-sealable skin layer facing the inside of a packaging container made from the laminate packaging material, which is intended to come into contact with the filled product. The heat-sealable skin layer comprises a polymer that provides the important heat-sealability properties of high hot tack and low seal initiation temperature, e.g., attributable to polyethylene of the m-LLDPE type.

[0103] In a further embodiment, the pre-manufactured polyethylene film has a maximum hot tack seal strength of greater than 8 N as measured by ASTM F1921 (2018). The combination of a low seal initiation temperature and a high maximum hot tack force at low temperatures ensures a fast and immediate sealing operation, enabling high speed filling machines and reliable seal strength of the filled packaging containers.

[0104] In yet a further embodiment, the pre-manufactured polyethylene film has a puncture resistance of 10 N or greater, measured at a crosshead speed of 500 mm / min according to ASTM F1306-16 (2016), and exhibits an elongation upon puncture (i.e., at maximum load) of less than 10 mm. This property is important for the film's ability to withstand penetration and rupture due to the sudden impact of a protruding object on its surface, i.e., its resistance to "sharp impact." This is believed to be a useful property in packaging that relies on paper-based oxygen barriers or other less flexible materials and is subject to sudden impacts or forces. A high puncture resistance value of 10 N or greater ensures that such impacts or forces must be significant before damage to the film occurs.

[0105] Suitable pre-made films are disclosed in U.S. Patent Application Publication No. 2018 / 361722A to Jindal Films Americas LLC. A preferred pre-made polyethylene film is SealTOUGH 18XE400 manufactured by Jindal Films. The amount of additives can be fine-tuned, for example, for food safety.

[0106] The elastic modulus measurements were performed at a sample length of 100 mm. The strain rate was adjusted to this sample length using a grip separation rate of 10 mm / min according to ASTM D 882-18. Therefore, the initial strain rate was 0.1 mm / (mm*min).

[0107] Thickness measurements were performed in accordance with ASTM E252-06.

[0108] Tensile strength was measured according to ASTM D638M-14 (2017) at a crosshead speed of 200 mm / min.

[0109] The elongation at break was measured according to ASTM D638M-14 (2017) at a crosshead speed of 200 mm / min.

[0110] The seal initiation temperature (SIT) of 80–100°C was measured at 2N according to ASTM F1921 (2018).

[0111] The maximum hot tack force was measured according to ASTM F1921 (2018).

[0112] Puncture resistance was measured according to ASTM F1306-16 (2016) at a crosshead speed of 500 mm / min. Examples and Description of the Preferred Embodiments

[0113] Preferred embodiments of the present invention will now be described with reference to the drawings. [Brief explanation of the drawings]

[0114] [Figure 1] 1 is a cross-sectional view schematically showing one embodiment of a laminate packaging material according to the present invention. [Figure 2] 1 shows a further embodiment of a laminate packaging material according to the present invention. [Figure 3a] FIG. 1 is a schematic diagram showing a method for dispersion coating an aqueous barrier composition onto a paper substrate. [Figure 3b] FIG. 1 is a diagram showing a schematic diagram of a method for bonding two webs together by melt extrusion lamination. [Figure 3c] FIG. 1 is a schematic diagram illustrating a method for melt (co)extrusion coating layers of thermoplastic heat-sealable liquid-tight polymer onto a web substrate to form the innermost and outermost layers of the packaging laminate of the present invention. [Figure 4] FIG. 1 is a perspective view of a plant for physical vapor deposition (PVD) coating of paper substrates or films using solid metal evaporation flakes. [Figure 5] 5a, 5b, 5c and 5d are diagrams showing typical examples of packaging containers made from the laminate packaging material according to the present invention. [Figure 6]5a and 5b illustrate how packaging containers such as those shown in FIGS. 5a and 5b are manufactured from packaging laminate in a continuous roll-fed, form-fill-seal process. [Figure 7] FIG. 1 illustrates how the laminate material of the present invention improves the packaging integrity of paper pouch packages to withstand shipping and rough handling. [Figure 8] 8a, 8b and 8c are schematic diagrams plotting force versus deformation for laminated packaging materials of the present invention and comparative laminated packaging materials when opening a package for drinking beverages with a drinking straw. [Figure 9] 9a and 9b are further diagrams relating the total energy required to open a package for drinking a beverage with a drinking straw for laminated packaging materials of the present invention and comparative laminated packaging materials. [Figure 10] 10a and 10b are diagrams relating to the reduction in tear strength of the laminate packaging material of the present invention.

[0115] FIG. 1 shows a cross section of an embodiment of a laminate packaging material 10 for a liquid carton package, which has a bending force of 80 mN and a compressibility of about 200 g / m 2 The packaging laminate comprises a bulk layer 11 of paperboard having a basis weight of 120 ... 2 is applied in an amount of

[0116] The innermost liquid-tight, heat-sealable pre-fabricated polyethylene film 14 is positioned opposite the bulk layer 11 and faces the inside of the packaging container made from the packaging laminate, i.e., the film 14 is in direct contact with the packaged product. The pre-fabricated polyethylene film 14 forms a strong transverse heat seal for the liquid packaging container made from the laminate packaging material and comprises a biaxially oriented film primarily made of LLDPE. It has a thickness of 18 μm, exhibits the mechanical properties of the film in Table 1, and meets the requirements of claim 1.

[0117] The bulk layer 11 is laminated to the barrier coated paper substrate 15 by an intermediate bonding layer 16 of low density polyethylene (LDPE). The intermediate bonding layer 16 is formed by melt extruding a thin molten curtain of polymer between the two paper webs, so that the bulk layer and the barrier coated paper substrate are laminated together when all three layers pass through the chilled press roller nip. The basis weight of the intermediate bonding layer 16 is 12-20 g / m 2 , e.g., 14 to 16 g / m 2 The intermediate adhesive layer may comprise a single LDPE polymer or may comprise two or more partial layers of different polyethylenes to tailor the adhesion between the bulk layer and the barrier layer. In a preferred embodiment, the intermediate adhesive layer 16 is comprised of three partial layers, with an intermediate layer of metallocene-polymerized linear low-density polyethylene (mLLDPE) and adjacent layers of LDPE. The basis weight of each of the three layers is approximately 5 g / m. 2 Thus, the LDPE layer is directly adjacent to and adhered to the bulk layer 11 and the paper barrier 15, respectively.

[0118] The paper barrier is approximately 40 g / m 2The paper substrate includes a thin paper substrate 15a having a basis weight of 1.5 g / m. The paper substrate may be base coated or impregnated 15a with a polymer composition to provide a smooth and / or dense surface and improve the quality of the subsequently applied gas barrier coating. However, in this case, the paper substrate is simply coated with two coatings 15a, 15b of PVOH. PVOH, a polymer with high gas barrier properties, is applied by aqueous dispersion coating, and then each of the two layers is dried to a dry basis weight of 1.5 g / m. 2 This means that the total amount of PVOH is about 3 g / m 2 The gas barrier coatings 15a and 15b are further coated with a metallized layer 15c to provide the paper barrier with the protection of a polymeric gas barrier coating and to provide the paper barrier with water vapor barrier properties in addition to the oxygen barrier properties. The metallized coating 15d is applied to an optical density of about 2. The paper barrier 15 is pre-fabricated before being laminated to the full laminate packaging material, i.e., by melt extrusion laminating an intermediate tie layer 16 to the bulk layer 11 as a pre-fabricated barrier unit 15.

[0119] An innermost biaxially oriented heat-sealable film, such as ethylene acrylic acid copolymer (EAA), is well adhered to the surface of the metal barrier vapor deposition coating 15d by an intermediate coextruded tie or adhesive polymer layer 17a, which is coextruded with an additional inner primary adhesive layer 17b of extrusion-grade polyethylene, such as LDPE. This inner polymer layer configuration provides strong protection for the photosensitive paper barrier 15. The tie and adhesive layers 17a and 17b are each 5-7 g / m², depending on the size and type of packaging container being manufactured. 2 and 5 to 20 g / m 2 In this embodiment, the inner adhesive layers may each be applied at 6 g / m 2 and 13g / m 2 was applied.

[0120] Alternatively, the bulk layer 11 may be laminated to the barrier-coated paper substrate 15 by wet lamination with an intermediate adhesive layer 16b, e.g., a thin layer of adhesive polymer, obtained by applying an aqueous dispersion of PVOH, starch, or polyvinyl acetate adhesive to one of the surfaces to be bonded together and then pressing them together in a roller nip. Thanks to the relatively thick absorbent bulk layer of cellulosic structure, this lamination process can be carried out in an efficient low- or ambient-temperature lamination process at industrial speeds, without the energy-consuming drying operations normally required to promote water evaporation. The dry coating weight of the intermediate adhesive layer 16b is only a few g / m 2 For example, 2 to 6 g / m 2 and no drying or evaporation is required.

[0121] Therefore, the amount of thermoplastic polymer in this laminate layer can be significantly reduced compared to conventional polyethylene 16 melt extrusion laminate adhesive layers.

[0122] FIG. 2 shows a different embodiment of a laminate packaging material 20 of the present invention for a liquid paper pouch package, which has a bending force of 0 mN and a bending strength of about 72 g / m 2 and a liquid-tight, heat-sealable outer layer 22 of polyolefin applied to the outside of the bulk layer 21, the outer layer 22 facing the outside of a packaging container made from the packaging laminate. The polyolefin of the outer layer 22 is a conventional heat-sealable low-density polyethylene (LDPE) having a basis weight of 12 g / m 2 Layer 22 is transparent to reveal the decorative pattern 23 printed on the bulk layer of paper 21.

[0123] The paper core layer 21 is further laminated to an aluminum foil which forms a barrier layer 24 which imparts various barrier properties to the packaging laminate, in particular oxygen and light barrier properties. The barrier layer 24 is adhered to the paper core layer 21 by a thermoplastic polymer adhesive layer 25 by melt extrusion lamination of a thermoplastic polymer. The thermoplastic polymer of the intermediate adhesive layer 25 is LDPE, which is applied as a single layer in an amount of 15 g / m2.

[0124] The innermost liquid-tight, heat-sealable layer 26 is a prefabricated polyethylene film, positioned opposite the barrier layer 24 and facing the interior of the packaging container produced from the packaging laminate. Thus, the film 26 comes into direct contact with the packaged product. The prefabricated polyethylene film 26 is identical to the biaxially oriented film 14 of the packaging laminate 10 of FIG. 1 and is composed primarily of LLDPE. The biaxially oriented film 26 is well adhered to the surface of the aluminum barrier foil 24 by an intermediate coextruded tie layer or adhesive polymer layer 27, for example, of ethylene acrylic acid copolymer (EAA), which is coextruded with an additional inner primary adhesive layer 28 of LDPE. This configuration of the inner polymer layer provides strong, robust protection for the aluminum foil and improved integrity of the filled and heat-sealed pouch package. The tie layer 27 and adhesive layer 28 each have a weight average of 5 to 7 g / m², depending on the size and type of pouch container being produced. 2 and approximately 5 to 20 g / m 2 In this embodiment, the inner adhesive layers were applied at 6 g / m2 and 13 g / m2, respectively.

[0125] Figure 3a shows an aqueous dispersion coating process 30a, which may be used to apply a gas barrier coating 12 from an aqueous gas barrier composition onto a substrate or to apply an aqueous adhesive composition for wet laminating two webs together, at least one of which has a fibrous cellulosic surface. A paper substrate web 31a (e.g., paper substrate 15a in Figure 1) is fed to a dispersion coating station 32a, where an aqueous dispersion composition is applied to the upper surface of the substrate by a roller. The aqueous composition has an aqueous content of 80-99% by weight, and much of the water on the wet-coated substrate must be dried and evaporated by heat to form a continuous coating that is homogeneous and has consistent quality in terms of barrier and surface properties, i.e., uniformity and wettability. Drying is accomplished by a hot air dryer 33a, which also evaporates water from the surface of the paper substrate. The temperature of the substrate is maintained constant at 60-80°C as it passes through the dryer. Alternatively, drying may be partially assisted by radiant heat from infrared IR lamps in combination with hot air convection drying.

[0126] The resulting barrier coated paper substrate web 34a is cooled and wound onto a reel for intermediate storage, at a later time, before the paper substrate 34a is further vapor-deposited with a barrier vapor-deposition coating.

[0127] FIG. 3b illustrates a method for melt-extrusion laminating two webs together, such as a barrier material 31b formed by method 30a of FIG. 3a, or an aluminum foil barrier 24 as shown in FIG. 2, and a bulk paperboard or paper layer 34b; 11; 21. Thus, the two webs are unwound from intermediate storage reels (not shown) and advanced to be spliced ​​together at a lamination roller nip 35b, while a hot melt curtain of bonding layer thermoplastic polymer 33b is extruded through a feedblock and tie layer 32b between the two webs to be spliced. The melt curtain solidifies upon contact with the two cold webs and is pressed between them into a laminated sandwich. One roller in the nip functions as a press roller, and the anvil roller, which may be a water-cooled steel roller, supports the rapid solidification of the melt curtain polymer into a thick, stable bonding layer, bonding the lamination layers of material 36b.

[0128] Figure 3c shows the process (30c) for the final lamination step in the production of a laminated packaging material such as 10 or 20 in Figures 1 and 2, respectively, after bulk layers 11, 21 have first been laminated to barrier layers 15, 24. The bulk layer paperboard may be laminated to a barrier-coated paper substrate by wet, cold dispersion adhesive lamination, or melt extrusion lamination, as described above.

[0129] The resulting paper prelaminate web 31c, 36b is transported from an intermediate storage reel or directly from a lamination station for laminating the paper prelaminate. The non-laminated, i.e., printed, side of the bulk layer 11; 21 is joined in a chilled roller nip 63 to a molten polymer curtain 33c of LDPE that forms the outermost layer 12; 22 of the laminate material, as the LDPE is extruded through an extruder feedblock and die 32c.

[0130] The paper prelaminate web, with the outermost layer 12; 22 coated on the print side, i.e., the outside, then passes through a second extruder feedblock and tie layer 35c and a lamination nip 37c, where a molten polymer curtain 36c is bonded to and coated on the other side of the prelaminate, i.e., the barrier-coated side of the paper substrate, while a prefabricated polyethylene film 38c is simultaneously laminated to the inside of the barrier layers 15, 24. In this way, the innermost heat-sealable biaxially oriented film 14; 26 is (co)extrusion laminated to the inside of the bulk barrier prelaminate web 31c, finally forming a laminated packaging material 39c, which is then wound up on a storage reel (not shown).

[0131] These two co-extrusion steps in lamination roller nips 34c and 37c may alternatively be performed as two successive steps in reverse order.

[0132] FIG. 4 is a perspective view of an example of a plant 40 for physical vapor deposition (PVD) of, for example, an aluminum metal coating or an aluminum oxide coating onto a web substrate of the present invention. A coated or uncoated paper substrate 43 is subjected to continuous vapor deposition 41 of vaporized aluminum, instead of a mixture of oxygen and aluminum vapor, to form a metal vapor-deposited layer of aluminum or a vapor-deposited barrier coating of aluminum oxide on its precoated side. The coating is provided to a thickness of 5 to 200 nm, e.g., 5 to 100 nm, e.g., 10 to 50 nm, to form a barrier-coated paper substrate 44 of the present invention. The aluminum vapor may be formed by ion bombardment of a solid aluminum piece evaporation source 41. For aluminum oxide coatings, oxygen gas may also be injected into the plasma chamber through an inlet port.

[0133] FIG. 5a shows an embodiment of a packaging container 50a made from a packaging laminate according to the present invention. This packaging container is particularly suitable for beverages, sauces, soups, and the like. Typically, such a packaging container has a volume of approximately 100-1000 ml. It can be any shape, but is preferably brick-shaped, with longitudinal seals 51a and lateral seals 52a, and optionally, an opening device 53. In another embodiment, not shown, the packaging container can be wedge-shaped. To achieve this "wedge" shape, only the bottom of the package is folded, with the bottom lateral heat seal formed so that it is hidden under triangular corner flaps that are folded and sealed to the bottom of the package. The top lateral seal remains unfolded. In this way, the only partially folded packaging container remains easy to handle and dimensionally stable enough to be placed on a grocery store shelf or flat surface.

[0134] Figure 5b shows an alternative packaging container 50b made from an alternative packaging laminate according to the present invention. The alternative packaging laminate is thinner than the type of packaging shown in Figure 5a by having a thinner paper bulk layer, and therefore is not a carton with sufficient bending stiffness to form a dimensionally stable parallelepiped or wedge-shaped package. Since no folds are formed after transverse seal 52b, no crease lines are provided. The package remains a pillow-like bag-like container after transverse sealing, and is distributed and sold in this form.

[0135] Figure 5c shows a gable-top package 50c that is folded and formed from a pre-cut sheet or blank of laminate packaging material comprising a bulk layer of paperboard and a barrier-coated paper substrate of the present invention. Flat-top packages may also be formed from similar blanks.

[0136] 5d shows a bottle-like package 50d that combines a sleeve 54 formed from a pre-cut blank of the laminate packaging material of the present invention with a top 55 formed from injection-molded plastic in combination with an opening device such as a screw cork. This type of package is sold, for example, under the trade names Tetra Top® and Tetra Evero®. Such a package is formed by attaching a molded top 55 with an opening device in a closed state to a tubular sleeve 54 of laminate packaging material, sterilizing the resulting bottle-top capsule, filling it with a food product, and finally folding and sealing the bottom of the package.

[0137] Figure 6 illustrates the principle described at the beginning of this application. A web of packaging material is formed into a tube 61 by overlapping longitudinal edges 62a, 62b of the web and heat-sealing them together, forming an overlap joint 63. The tube is continuously filled (64) with the liquid food product to be filled and divided into individual filled packages by repeating double transverse seals 65 of the tube at predetermined intervals below the level of the filled contents in the tube. Packages 66 are separated by cutting between the double transverse seals (top and bottom seals) and finally formed into the desired geometric shape by forming folds along pre-defined crease lines in the material. Corresponding pouch containers can be manufactured using the same principle, but the final folding step after separating the tube into individual pouch packages is omitted.

[0138] The present invention is not limited to the embodiments shown and described above, but various modifications may be made within the scope of the claims. Furthermore, it should be noted that the physical proportions of objects and items shown by way of purely illustrative drawings do not necessarily reflect the true proportions of such objects and items in real life.

[0139] Example Table 1: Properties of the manufactured polyethylene film [Table 1]

[0140] Example 1 Laminate 1 of the present invention A laminate material was produced with the following main structure: / LDPE / Paperboard / / LDPE / / mLLDPE / / LDPE / / -Coextrusion / / Paper base material / / PVOH / / Metal deposition / / EAA adhesive / / LDPE / / Biaxially oriented LLDPE film BO-F /

[0141] The biaxially oriented film BO-F was a prefabricated film (SealTOUGH 18XE400, manufactured by Jindal Films) composed primarily of LLDPE and LDPE, with LLDPE comprising at least 60% by weight of the major polymer component. It was extrusion cast and then oriented in both the MD and CD, i.e., a biaxially oriented film. This film was only 18 μm thick and included a heat-sealable skin layer of m-LLDPE on the free surface (the inner surface of the packaging container) a few microns thick, with a high degree of orientation in both the MD and CD. On the opposite side of the film, the film had a co-oriented skin layer of a different polymer composition from the core layer. This additional skin layer is not necessary for the present invention but is present primarily for layer symmetry to facilitate extrusion casting and subsequent biaxial orientation operations. No tie layer was present.

[0142] The standard measurement method for this application differs from Jindal's internal measurement method specified in the SealTOUGH datasheet, meaning values ​​will not match exactly.

[0143] The bulk layer, i.e., the paperboard, is 15 g / m 2 by melt extrusion lamination with an intermediate adhesive layer of LDPE, or 5 g / m² per layer 2 The biaxially oriented LLDPE film BO-F was laminated to a barrier-coated thin paper substrate using a three-layer coextrusion structure of 6g / m2 LLDPE / LDPE / LDPE. 2Adhesive EAA polymer bonding layer of approximately 13 g / m 2 The EAA was further laminated to the other side of the barrier-coated paper substrate by melt-extrusion lamination with an adhesive layer of LDPE, forming an intermediate adhesive layer portion in which the EAA was adjacent to the barrier-coated paper and the LDPE was adjacent to the biaxially oriented LLDPE film BO-F.

[0144] Comparison Laminate 1A: A laminate was prepared having the same main structure as Inventive Laminate 1, except that a pre-prepared blown LLDPE film A / was used. / LDPE / Paperboard / / LDPE / mLLDPE / LDPE / -Coextrusion / / Paper substrate / PVOH / Metal deposition / EAA adhesive / LDPE / Blown LLDPE film A /

[0145] Blown LLDPE film A was pre-fabricated as a monolayer film with a thickness of 22 μm by a film-blowing process and contained about 80 wt % LLDPE and about 20 wt % LDPE.

[0146] As with Inventive Laminate 1, the same paperboard was used on the same barrier-coated thin paper substrate, with 5 g / m of LDPE / mLLDPE / LDPE / each. 2 The blown film A was further laminated on the other side of a barrier-coated paper substrate by melt coextrusion lamination having an intermediate adhesive layer portion of a three-layer structure. 2 Adhesive EAA polymer of approximately 13 g / m 2 The EAA was melt-coated with the LDPE to form an intermediate adhesive layer between the EAA adjacent to the barrier-coated paper and the LDPE adjacent to the blown LLDPE film A.

[0147] Comparison Laminate 1B: A laminate was produced having the same main structure as Inventive Laminate 1, except that a pre-made blown LLDPE film B / was used: / LDPE / Paperboard / LDPE / Paper / PVOH / Metal deposition / EAA adhesive / LDPE / Blown LLDPE film B /

[0148] Blown LLDPE film B is pre-fabricated into a 25 μm thick three-layer film mainly from LLDPE and LDPE by a film-blowing process, with LLDPE being the main polymer component at more than 60 wt %, including a layer of adhesive polymer of ethylene acrylic acid copolymer EAA, and the core layer containing approximately 80 wt % LLDPE.

[0149] The same paperboard was laminated with 5g / m² of LDPE, m-LLDPE, and LDPE, respectively, in the same manner as in the present invention laminate 1. 2 The adjacent intermediate adhesive layer portion of the three-layer structure was melt-extrusion-laminated to the same barrier-coated thin paper substrate. This blown film B was then laminated to the other side of the barrier-coated paper substrate at a rate of about 6 g / m. 2 Adhesive EAA polymer of approximately 13 g / m 2 The EAA was melt-coated with the LDPE to form an intermediate adhesive layer between the EAA adjacent to the barrier-coated paper and the LDPE adjacent to the blown LLDPE film B.

[0150] The detailed structure of the above laminate material is as shown in Table 2.

[0151] [Table 2]

[0152] Therefore, the packaging materials exemplified in Table 2 are non-foil packaging materials for liquid carton packages, have thin and delicate oxygen barrier coatings, and are more vulnerable to stress and strain than similar laminate materials using aluminum foil as the oxygen barrier.

[0153] Integrity of packaging and packaging materials Packages were fabricated from the packaging laminates shown in Table 2 and filled with water in a Tetra Pak® A3 / Compact Flex filling machine. This type of filling machine is capable of filling small packages at a rate of 9,000 packages per hour and is flexible enough to quickly change between different package formats. The packages were in the Tetra Brik® format with a 200 ml capacity. The packages were then emptied and unfolded to examine the inner laminate area, where mechanical stresses are greatest during the filling and forming operations. In these areas, the laminate material is typically subjected to high stresses from multiple folds; an example of such an area on a Tetra Brik® package is the bottom corner flap.

[0154] The one or more polymer layers inside the metallized coating, i.e., on the side facing the filled product, were investigated in these areas of each package using X-ray tomography, an imaging technique that can distinguish between the various layers of the laminate, i.e., resolve and quantify the thickness of the pre-fabricated polyethylene film and the inner polymer layers.

[0155] Thus, the bi-folds were rated at one of three levels depending on the average frequency and size of small weaknesses or imperfections, or so-called defects, in the inner polymer layer. None of the laminates and packages examined had any or very few actual defects in the inner polymer layer, but the assessment of the occurrence of defects, i.e., defects that may occur later when the filled package is subjected to greater stresses and strains, gives an overview of the potential risk of eventual leakage or leak failure. The rating levels are as follows: 1 = Approved, minimal polymer flakes and defects as determined by X-ray analysis (OK) 2 = Polymer thinning and defects detected by X-ray analysis are accepted at a higher level, but within a safety margin to prevent actual defects from occurring ("acceptable"). 3 = X-ray analysis of polymer thinning and defects is not within the approved safety margin to prevent actual defects from occurring under severe conditions ("unacceptable").

[0156] [Table 3]

[0157] Additionally, the metallized coating of the paper barrier structure was evaluated by visual inspection of the folded section using a magnifying device. For this evaluation, a Peak N2044 measuring instrument with 16x magnification was used, achieving a resolution and accuracy of 0.1 mm. (Table 4) shows the occurrence of very fine defect lines and cracks in the metallized coating.

[0158] [Table 4]

[0159] It can therefore be concluded that the laminate material of the present invention has improved mechanical robustness and a better margin of safety for package integrity, i.e., the inner polymer layer remains intact and protects the contents contained therein throughout the storage, distribution, and life of the package. This improved robustness of the inner polymer layer is also believed to protect the sensitive barrier coating of the paper barrier material in an improved manner.

[0160] Cleavage test Tear strength according to ISO 1974 (Elmendorf test) is the force, expressed in mN, required to continue a tear initiated by an initial cut in the part of the sample sheet being tested. This measurement is usually adapted for testing paper and paperboard, but it can also be used to measure the tear force required for laminated materials made from paper or paperboard.

[0161] Thus, the tear strength test results according to ISO 1974 (Elmendorf test) for Inventive Laminate 1 and Comparative Laminates 1A and 1B are shown in the graphs in Figure 10a (MD and CD, respectively). The graphs show values ​​relative to the highest measured value of the laminates tested, and therefore reflect the relative differences in properties between the inventive laminate (Inventive Laminate 1) and Comparative Laminates 1A and 1B.

[0162] Inventive Laminate 1 exhibited significantly lower tear strength in both the MD and CD than Comparative Laminate 1A and Comparative Laminate 1B.

[0163] This supports the results of consumer panel testing of the tear-open ability of these materials, i.e., the ability to tear open the material in packages, etc., that have other weakenings, such as weakened notches or tear-open perforations. Thus, Inventive Laminate 1 was perceived as easier to tear open than Comparative Laminate 1A and Comparative Laminate 1B.

[0164] Total energy required to penetrate a drinking straw through a pre-cut hole in a laminate The laminate materials tested were manufactured and converted to accommodate one pre-cut, laminated straw hole per package. Therefore, the bulk layers of paper or paperboard were pre-cut at intervals to provide one 6mm diameter hole per package, suitable for the opening of a drinking straw. In a subsequent lamination operation, these straw holes were covered with the overlaminate, i.e., all other layers of the laminate, to form the laminate tested herein. Within the paperboard hole area, the outermost LDPE layer was bonded to the LDPE laminate layer, resulting in a laminate membrane with a paper barrier and inner polymer layers, including the innermost pre-fabricated polyethylene film.

[0165] In internal experiments, a standard compression test machine (Zwick Roell) was used to evaluate the total energy required to penetrate and open the membrane using a diagonally cut metal straw, similar in size to the plastic or paper straws consumers typically use to open portion packs. The purpose of the metal straw test was to eliminate the effects of variability due to the softer, more flexible diagonally cut ends of disposable drinking straws. It was found that the Inventive Laminate 1 and Comparative Laminate 1A required approximately the same total energy (total area under the measured force curve). However, previous consumer panel testing more clearly demonstrated that the Inventive Laminate 1 provided a better straw opening, which was then further investigated and measured.

[0166] Thus, it was found that the shape of the required penetration force plot, i.e., the appearance of the deformation curve, in both the MD and CD of the laminate material of the present invention differed between the two laminates.

[0167] As shown in the graphs of Figures 8b and 8c, the plotted force reaches a maximum prior to penetration much sooner for Inventive Laminate 1 than for Comparative Laminate 1A (Figure 8a). This likely explains the results obtained from the test panel, namely, that it was easier to open the straw hole with Inventive Laminate 1. While this opening experience is likely due to the more pronounced penetration of the straw hole membrane by the straw, which occurs directly when the straw is pressed against the straw membrane, the total force required at the moment of penetration may be comparable or even greater. In CD, the required force was measured to be lower for Inventive Laminate 1. This is further illustrated in the graph of Figure 9a, measuring the energy required to reach the maximum force "F-max," i.e., the force measured just prior to membrane penetration, and in the diagram of Figure 9b, measuring the increase in force dL leading to "F-max." The graph shows values ​​relative to the highest measured value for both laminates, and therefore reflects the relative differences in properties between the laminate of the present invention (Inventive Laminate 1) and Comparative Laminate 1A.

[0168] In conclusion, even in the case of straw opening or pre-cut hole-through membrane opening mechanisms, the inventive laminate 1 provides significantly improved openability, despite the fact that certain pre-fabricated polyethylene films significantly improve the packaging integrity and mechanical robustness of the laminate material.

[0169] Example 2 Laminate 2 of the present invention: A laminated packaging material was produced having the following structure: / LDPE / Laminated paper for pouch packaging, (0mN) 72g / m 2 / LDPE / Aluminum foil / EAA adhesive / LDPE / Innermost layer: biaxially oriented polyethylene film BO-F /

[0170] The biaxially oriented polyethylene film BO-F was the same pre-made film as described in Example 1 above.

[0171] Different bulk layers, i.e., about 72 g / m 2 The paper, which does not have inherent bending stiffness and is intended for the production of paper pouch packages, not folded cubic packaging containers as in Example 1, was used at a density of 15 g / m 2 The biaxially oriented LLDPE film BO-F was further laminated to the other inner side of the aluminum foil by melt extrusion lamination with an adjacent adhesive layer of 6 g / m LDPE. 2 adhesive EAA polymer tie layer of approximately 13 g / m 2 The EAA and the LDPE adhesive layer were melt-extrusion laminated together to form an intermediate adhesive layer portion in which the EAA was adjacent to the aluminum foil and the LDPE was adjacent to the biaxially oriented LLDPE film BO-F.

[0172] Comparison Laminate 2: Laminates were produced with the following structure: / LDPE / paper 72g / m 2 / LDPE / Aluminum foil / Blown polyethylene film B / EAA adhesive polymer / 70wt% mLLDPE + 30wt% LDPE innermost layer blend /

[0173] In Comparative Laminate 1B, Blown LLDPE Film B was the same as in Example 1.

[0174] Same bulk layer, i.e., about 72 g / m 2 of paper, approximately 15 g / m 2 The film was laminated to the same aluminum foil as inventive laminate 2 by melt extrusion lamination with the adhesive layer of 6 g / m LDPE adjacent to it. Blown film B was simultaneously laminated to the opposite side of the aluminum foil by hot pressure laminating the foil to the film with the adhesive layer of EAA facing the aluminum foil. 2 of adhesive EAA polymer at approximately 19 g / m 2 The innermost layer was formed by coextrusion on the opposite side of the film with a blend of 70 wt% mLLDPE and 30 wt% LDPE, which allowed the inner layer to be heated for a longer period of time, further improving the adhesion of the blown film to the aluminum foil.

[0175] The detailed structure of the above laminate material is as shown in Table 5.

[0176] [Table 5]

[0177] The construction with Comparative Laminate 2 has been state of the art for many years and is recognized as the most robust and mechanically strong packaging laminate for paper pouch packaging materials. Other pre-made films and configurations have been tested over time, but no one has been found to be superior. The strains and stresses placed on the packaging materials in such pouch packages (sold as Tetra Fino® Aseptic) are extraordinary, while this packaging concept is targeted at emerging economies and the low-cost segment.

[0178] In this way, pouch package containers were produced from the laminate materials of Table 5 in a Tetra Pak® A1 filling machine. This type of filling machine has the capacity to fill small pouch packages at a rate of approximately 12,000 packages / hour. The packages were in the Tetra Fino® Aseptic format and had a capacity of 250 ml.

[0179] Transport Test To evaluate the ability of these pouch packages to withstand transport, handling, and distribution, an adapted vibration transport test was used. The vibration test method simulates the transport and distribution of the packages. The vibration test was performed in accordance with ASTM D 4728-17: "Standard Test Method for Random Vibration Testing of Shipping Containers" and followed a standard 45-minute vibration cycle program, "Level 1." Prior to testing, the pouch packages were packed into secondary carton packages in a standardized manner, each containing 24 pouches. The resulting distribution cartons were conditioned in a climate chamber until a stable temperature and humidity were reached. They were then placed on distribution pallets in a standardized manner, with the secondary cartons stacked seven deep.

[0180] When converting cylindrical tubes into pillow pouch-shaped packages, defects occur, especially in the side panels of the laminate material. This transformation cannot be performed geometrically without the formation of several deformations and wrinkles. These deformations can become initial weak points for fatigue propagation during distribution and handling, ultimately transforming into defects in the barrier layer and package seal.

[0181] The vibration test was selected to induce a level of failure in the pouch package, i.e., leakage of the filled fluid. After the vibration test, the number of leaking packages was counted. Furthermore, the packages that failed within such a test could be classified into different levels of severity of failure, allowing further study of the details and nature of the failure. For purposes of this invention, the percentage of packages that leaked was evaluated.

[0182] The results of a comparison of packages made with Inventive Laminate 2 and Comparative Laminate 2 are shown in the graph of Figure 7. This shows that a significantly improved packaging material has been developed that allows for a reduction in particles per 100 containers from 3.5 to 1.75, a 50% reduction.

[0183] This result was quite surprising, as the packaging material did not need to be made thicker by simultaneously increasing the polymer content, but rather the opposite.

[0184] Cleavage test Tear strength was measured on samples of the laminate material in Table 5 by the same method as was performed on the laminate material tested in Example 1, except that the laminate was thinner in this case, so testing was performed on a total of four layers of the laminate material in Table 5. Tear strength is the force, in mN, required to continue a tear initiated at a small cut in the sample test piece, measured according to the Elmendorf test of ISO 1974.

[0185] The results of comparing the inventive laminate 2 with the comparative laminate 2 are shown in Figure 10b.

[0186] These results demonstrate that Inventive Laminate 2 is significantly more robust in supporting the integrity of the filled and sealed pouch package, while at the same time being much easier to open, as indicated by a tear test evaluated in the same manner as described above in connection with Example 1. The graph shows values ​​relative to the highest measured value for both laminates tested, and therefore reflects the relative differences in properties between the inventive laminate (Inventive Laminate 2) and comparative laminate 2.

[0187] Inventive Laminate 2 exhibited significantly lower tear strength than Comparative Laminate 2 in both the MD and CD directions.

[0188] This is supported by the results of tests conducted by a consumer test panel evaluating the openability of pouch packages according to the present invention and pouch packages according to the prior art. These panel evaluations demonstrated that the pouch made of Comparative Laminate 2 could not actually be opened by tearing, even when a slit was made in the material, and had to be cut open with scissors, whereas the pouch made of Inventive Laminate 2 could be easily opened by tearing.

[0189] Conclusion of this Example The laminate packaging material of this embodiment has several advantages.

[0190] The laminated barrier and inner layers maintained sufficient strength despite repeated folding and high stress during folding and forming into filled and heat-sealed packages, and were able to withstand rigorous transport and vibration simulation tests of pouch packages, significantly improving package integrity. At the same time, the openability of the laminated packaging material was significantly improved, as evidenced by tear strength tests and tests on the total energy behavior during opening with a straw.

[0191] Improving the fundamentally opposing properties of a liquid carton laminate, such as package strength and integrity on the one hand, and package openability on the other, is a true achievement that goes beyond the usual optimization effort, which usually means some trade-off or compromise on one or both properties.

[0192] These competing property improvements further enable the use of more demanding packaging formats such as larger packages, pouch packages, and folded packages with more severe fold points, which is an important advantage in that different consumer needs can be reflected in more tailored packages for different purposes and desires.

[0193] Without using thick metal foil such as conventional aluminum foil, gas barrier properties are ensured by a laminate material based on a foldable carton, resulting in a mechanically robust, high-performance, sustainable packaging material for long-term storage of liquid foods at room temperature in a sterile environment.

[0194] Such materials use one polymer (polyolefin / polyethylene) in addition to cellulose fibers, which requires less carbon dioxide in the manufacturing process, simplifies the recycling process, and is more environmentally and climate-sustainable. Therefore, the amount of waste products consisting of materials other than polyethylene and cellulose is minimized. Simplifying the recycling process is essential to achieving a sustainable circular materials economy.

[0195] Finally, it should be noted that the present invention is not limited to the embodiments shown and described above, but may be modified within the scope of the claims.

Claims

1. A laminate packaging material for packaging liquid food, comprising: a bulk layer (11; 21) of paper, cardboard or other cellulosic material; a first outermost liquid-tight and heat-sealable layer (12; 22) comprising a thermoplastic polymer; a barrier layer or barrier multilayer (15; 24) disposed on the inside opposite the bulk layer (11; 21) and comprising at least one gas barrier material; and a second innermost liquid-tight and heat-sealable layer (15) disposed inside the barrier layer or barrier multilayer, wherein the second innermost liquid-tight and heat-sealable layer (14; 26) is oriented toward the inside of a packaging container formed from the packaging material, and the second innermost liquid-tight and heat-sealable layer (14; 26) is a pre-fabricated polyethylene film (14; 26) which is a cast biaxially oriented film comprising 60-100% linear low-density polyethylene (LLDPE), and the pre-fabricated polyethylene film further comprises: A total thickness of 15-25 μm, According to ASTM D 882-02 (2018), the elastic modulus measured at an initial strain rate of 0.1 mm / (mm*min) was at least 400 MPa in the MD direction and at least 500 MPa in the CD direction. According to ASTM D638M-14 (2017), tensile strengths of 40 MPa or higher for MD and 100 MPa or higher for CD were measured at a crosshead speed of 200 mm / min. According to ASTM D638M-14 (2017), the elongation at break was less than 350% for MD and less than 100% for CD, measured at a crosshead speed of 200 mm / min. The seal start temperature (SIT) for 80-100°C was measured in 2N according to ASTM F1921 (2018), The maximum hot tack force, measured at ASTM F1921 (2018), was 7N or more. According to ASTM F1306-16 (2016), the puncture resistance is 10N or more, measured at a crosshead speed of 500 mm / min. Equipped with, Laminate packaging material.

2. The LLDPE of the aforementioned pre-fabricated polyethylene film (14; 26) has a melt flow rate / melt flow index (MFR / MFI) of 2-5 g / 10 min at 2.16 kg and 190°C, as measured according to ASTM D1238 or ISO 1133. The laminate packaging material according to claim 1.

3. The aforementioned pre-fabricated polyethylene film (14; 26) contains 60-100% m-LLDPE. The laminate packaging material according to claim 1.

4. The pre-fabricated polyethylene film (14; 26) has a core layer containing more than 60% by weight of m-LLDPE, and on one side of the core layer, a first skin layer containing LLDPE that is more suitable for heat sealing the film than the polyethylene of the core layer, and optionally, the pre-fabricated polyethylene film has a second skin layer on the other side of the core layer. The laminate packaging material according to claim 1.

5. The aforementioned pre-fabricated polyethylene film (14; 26) has a total thickness of 16 to 23 μm. The laminate packaging material according to claim 1.

6. The core layer of the pre-fabricated polyethylene film (14; 26) has a thickness of 10 to 16 μm. The laminate packaging material according to claim 4.

7. The thickness of the first skin layer and any second skin layer is 1 to 3 μm. The laminate packaging material according to claim 4.

8. The aforementioned pre-fabricated polyethylene film (14; 26) has a seal start temperature (SIT) of 80–95°C, as measured at 2N according to ASTM F1921 (2018). The laminate packaging material according to claim 1.

9. The aforementioned pre-fabricated polyethylene film (14; 26) has a maximum hot tack force exceeding 8 N as measured by ASTM F1921 (2018). The laminate packaging material according to claim 1.

10. The aforementioned pre-fabricated polyethylene film (14; 26) has a puncture resistance of 10 N or more as measured according to ASTM F1306-16 (2016) at a crosshead speed of 500 mm / min, and exhibits an elongation at puncture (i.e., at maximum load) of less than 10 mm. The laminate packaging material according to claim 1.

11. The barrier multilayer portion (15) includes a paper substrate (15a) coated with at least one coating (15b to 15d) of a gas barrier material. The laminate packaging material according to claim 1.

12. The coatings (15b to 15d) include vapor-deposited coatings of gas barrier materials selected from gas barrier polymers and / or metals, metal oxides, inorganic oxides and amorphous diamond-like carbon coatings. The laminate packaging material according to claim 11.

13. The barrier layer or the barrier multilayer portion (14; 26) is laminated onto the bulk layer (11; 21) by a first adhesive layer (16; 25) of one or more polymers. The laminate packaging material according to claim 1.

14. The pre-fabricated polyethylene film (14; 26) is laminated to the barrier layer or the barrier multilayer portion (15; 24) by a second adhesive layer (17b; 28) of a thermoplastic polymer. The laminate packaging material according to claim 1.

15. The aforementioned pre-fabricated polyethylene film (14; 26) has a stretch ratio of 5 to 7 in the mechanical direction MD and 7 to 10 in the intersecting direction CD. The laminate packaging material according to claim 1.

16. The present invention comprises a paper substrate (15a) having a paperboard bulk layer (11) having a basis weight of 100 to 520 g / m2 and a barrier multilayer (15), wherein the barrier multilayer (15) includes at least one coating (15b to 15d) of gas barrier material applied to a thickness of 2 to 5000 nm, in order to provide a more environmentally sustainable and recyclable packaging material. The laminate packaging material according to claim 1.

17. For the purpose of manufacturing pouch packaging, a bulk layer is provided which is a paper core layer (21) having a basis weight of 50 to 140 g / m2, and an aluminum foil barrier layer (24) is provided. The laminate packaging material according to claim 1.

18. A method for producing the laminate packaging material (10; 20) according to claim 1, comprising the following steps in any order: a) Laminating a continuous web of a bulk layer (11; 21; 34b) of paper, cardboard, or other cellulosic material to the outside of a continuous web of a barrier layer or barrier multilayer (15; 24; 31b) made of at least one gas barrier material (30b, 35b), b) Laminating a continuous web of a pre-fabricated inner polyethylene film (14; 26; 38c) to the other side of the web of the barrier layer or the barrier multilayer portion (15; 24; 31b) with the adjacent second binding layer of the binding polymer (17a, 17b; 27, 28; 36c) as a second innermost liquid-tight heat-sealable layer, by melt extrusion lamination or the like; c) A step (32c, 34c) of extruding and coating the outside of the bulk layer (11; 21; 31c; 34b) with the first outermost liquid-tight heat-sealable layer (12; 22; 33c), Equipped with, The aforementioned pre-fabricated polyethylene film (14; 26; 38c) is a cast biaxially oriented film containing 60-100% linear low-density polyethylene (LLDPE), and the aforementioned pre-fabricated polyethylene film is further, A total thickness of 15-25 μm, According to ASTM D 882-02 (2018), the elastic modulus measured at an initial strain rate of 0.1 mm / (mm*min) was at least 400 MPa in the MD direction and at least 500 MPa in the CD direction. According to ASTM D638M-14 (2017), tensile strengths of 40 MPa or higher for MD and 100 MPa or higher for CD were measured at a crosshead speed of 200 mm / min. According to ASTM D638M-14 (2017), the elongation at break was less than 350% for MD and less than 100% for CD, measured at a crosshead speed of 200 mm / min. The seal start temperature (SIT) for 80-100°C was measured in 2N according to ASTM F1921 (2018), The maximum hot tack force, measured at ASTM F1921 (2018), was 7N or more. According to ASTM F1306-16 (2016), the puncture resistance is 10N or more, measured at a crosshead speed of 500 mm / min. Equipped with, method.

19. Step a) involves applying an aqueous dispersion of an adhesive composition containing an adhesive polymer binder to the web of the bulk layer (11; 21) or the web of the barrier layer or the multilayer barrier portion (15; 24) at a dry weight of 1 to 5 g / m². ２ This is done by wet coating in a certain amount and pressing the two webs together while advancing them through a lamination roller nip without forcing them to dry. The method according to claim 18.

20. A packaging container (50a; 50b; 50c; 50d) for packaging liquid, semi-liquid, or viscous foods or oxygen-sensitive foods such as water, comprising the laminate packaging material (10; 20) described in claim 1.

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