Laminated packaging material, packaging container comprising laminated packaging material, and method of manufacturing such material and container

Abstract

A laminated packaging material for packaging liquid or semi-liquid food products, comprising each layer of the following sequence of layers:-a liquid-tight polymer outermost layer; -a bulk layer of paper or paperboard or other cellulose-based material; -a barrier layer comprising: an oriented substrate film comprising 50 to 100% by weight of high density polyethylene (HDPE), a first vinyl alcohol polymer barrier coating on the substrate film and a second vapor deposited metal barrier coating on the vinyl alcohol barrier coating, the barrier layer being arranged such that the metal barrier coating faces the bulk layer and the substrate film faces the innermost layer; and-a liquid-tight, heat-sealable polymer product comprising polyethylene contacting the innermost layer. A packaging container comprising the laminated packaging material and methods of making the laminated packaging material and packaging container are also disclosed.

Description

Technical Field

[0001] The present invention relates to: a laminated packaging material comprising a barrier coating substrate film, in particular for liquid carton food packaging; a method for manufacturing such a laminated packaging material; a packaging container comprising the laminated packaging material; and a method for manufacturing such a packaging container. Background Art

[0002] Disposable type packaging containers for liquid foods are usually made of packaging laminates based on paperboard or carton. A common packaging container is (Tetra Brik ) trademark, and is mainly used for aseptic packaging of liquid foods such as milk and juice for long-term ambient storage. The packaging material in such known packaging containers is usually a laminate, which includes a body or core layer of paper, paperboard or other cellulose-based material, and an outer liquid-tight layer of thermoplastic. In order to make the packaging container airtight, especially oxygen-tight, such as for aseptic packaging and packaging of milk or juice, the laminate in these packaging containers usually includes at least one additional layer, most commonly aluminum (Al) foil.

[0003] On the inside of the laminate, i.e. the side that is to face the food content filled container made of the laminate, there is an innermost layer, which is applied on the aluminum foil, said innermost layer on the inside may consist of one or more partial layers, including a heat sealable thermoplastic polymer, such as an adhesive polymer and / or a polyolefin. Likewise on the outside of the body layer, there is an outermost layer of a heat sealable polymer.

[0004] The packaging containers are usually produced using modern high-speed packaging machines, which form, fill and seal packages from coils or prefabricated packaging material blanks. Thus, packaging containers can be produced by converting a coil of laminated packaging material into a tube by joining the two longitudinal edges of the coil to each other at an overlap joint, which is formed by connecting the innermost and outermost layers of a heat-sealable thermoplastic polymer together. The tube is filled with the desired liquid food and then divided into individual packages by repeatedly sealing the tube transversely at predetermined distances from each other below the liquid level of the contents in the tube. The packages are separated from the tube by incisions along the transverse seals and formed into the desired geometric shape, usually a cuboid shape, by folding along prepared crease lines in the packaging material.

[0005] The main advantage of this continuous tube form, fill and seal packaging process concept is that the coil can be continuously sterilized before tube forming, thereby providing an aseptic packaging process, i.e. a process in which the liquid contents to be filled as well as the packaging material itself are germ-reduced, and the filled packaging containers are produced under clean conditions, so that the filled packages can be stored for long periods of time even at ambient temperature without the risk of microbial growth in the filled product. As mentioned above, Another important advantage of this type of packaging method is that it can be packaged continuously at high speed, which has a considerable impact on cost-effectiveness.

[0006] Packaging containers for sensitive liquid foods, such as milk or juice, can also be made from sheet blanks or preformed blanks of the laminated packaging material of the present invention. Starting from a folded flat tubular blank of the packaging laminate, the blank is first built into an open tubular container capsule, and then the package is produced by folding and heat-sealing an integral end panel to close one of the open ends. The container capsule thus closed is filled with the desired food, such as juice, through its open end, and then the open end is closed by further folding and heat-sealing the corresponding integral end panel. An example of a packaging container produced from sheet and tubular blanks is the traditional so-called mountain-top package. There are also packages of this type with a molded top and / or a screw cap made of plastic.

[0007] The aluminum foil layer in the packaging laminate provides superior gas barrier properties than most other gas barrier materials. In terms of its performance level, traditional aluminum foil-based packaging laminates for aseptic packaging of liquid foods remain the most cost-effective packaging material available on the market today.

[0008] The applicant's WO03095200A relates to a packaging laminate with an aluminum foil barrier layer. It points out that when the laminate is used for long-term packaging and storage of aggressive or acidic foods such as juice, the adhesion between the layers will decrease over time due to the migration of free fatty acids from the product through the inner layer of thermoplastic material to the interface between the aluminum foil and the adjacent adhesive polymer layer (which can be a modified polyolefin, such as maleic anhydride grafted modified LLDPE, MAH-g-LLDPE or ethylene and (meth) acrylic acid copolymer, EAA or EMAA). This causes the adhesion between these layers and the openability of the container to be greatly reduced after a few months or a year. WO03095200A solves this problem by including an internal partial layer that provides barrier properties to the migration of free fatty acids. The internal partial layer may include a cyclic olefin copolymer, or may include a blend of polyethylene and a finely dispersed filler.

[0009] There is a need to provide alternative barrier materials to aluminium foil to further reduce the carbon footprint. Aluminium foil barriers for liquid carton food packaging are typically 5 to 9 μm, with around 6 μm being the most common.

[0010] Any other material competing with foil-based materials should be cost-effective in terms of raw materials, have comparable food preservation properties, a reduced carbon footprint, and have relatively low complexity in converting the material into a finished packaging laminate.

[0011] In the efforts to develop non-aluminum foil materials for liquid food carton packaging, it is also generally encouraged to develop prefabricated films or sheets with high barrier properties, or to combine several individual barrier materials in multilayer films or sheets. Such films or sheets will replace aluminum foil barrier materials in traditional laminated packaging materials, and can also be suitable for traditional lamination and manufacturing processes of laminated packaging materials.

[0012] With the increasing demand to use only sustainable materials, polymer barrier materials derived from fossil sources are becoming less popular, so there is still a need to use various thin barrier coatings that are almost negligible in the recycling process and cause almost no problems in an economy based on the circulation of materials and renewable (non-fossil) materials, namely aqueous dispersion coatings and vapor deposited coatings. Such coatings are applied to substrates that usually do not provide significant barrier properties themselves. The thickness of the dispersion-coated polymer is about 1-2μm, while the vapor deposited barrier coating is as thin as less than 0.5μm, such as 10 to 100nm, such as 15 to 80nm, such as 20 to 50nm. Over the years, various such coatings have been developed and combined in multilayer packaging material structures in search of improved overall performance. Although some of these coatings show excellent barrier properties, the beverage carton packaging industry is still looking for the best coating or coating combination that can replace aluminum foil in all aspects.

[0013] Past development materials have involved, for example, waterborne polymer compositions suitable for thin layer dispersion and / or solution coating, such as PVOH, starch, etc. A common difficulty with this type of polymer binder is that they are sensitive to high moisture conditions and lose their inherent oxygen barrier properties with increasing moisture exposure and content (i.e., the conditions of laminated packaging materials for filled liquid carton packaging containers). It has been concluded that such thin dispersion-coated polymer layers need to be supplemented with other materials to improve the gas barrier properties, either in the form of additional compounds in the dispersion composition, such as crosslinking agents or inorganic particles, or in the form of additional layers of material that act as a water vapor barrier.

[0014] CN115257108 of SIG Combibloc Suzhou Co Ltd discloses a barrier layer for packaging, a sheet-like composite layer and a packaging container having the sheet-like composite layer. The barrier layer for packaging does not include a metal layer, but includes a base layer and a first barrier layer of a metal oxide disposed on top of the base layer. The base layer includes at least two different polymers, so that the barrier layer for packaging has at least two melting point peaks, thereby preventing the formation of bubbles during the sealing process.

[0015] Therefore, there is a need to improve laminated packaging materials at reasonable costs to meet future requirements regarding recyclability and sustainable material sourcing and manufacturing. Summary of the invention

[0016] According to a first aspect, the invention relates to a laminated packaging material for packaging liquid or semi-liquid foods, comprising the following layer sequence of layers: - Liquid-tight polymer outermost layer; - a bulk layer of paper or paperboard or other cellulose based material; - a barrier layer comprising an oriented substrate film, a first vinyl alcohol polymer barrier coating on the substrate film, and a second vapor deposited metal barrier coating on the vinyl alcohol barrier coating, the oriented substrate film comprising 50 to 100 wt% high density polyethylene (HDPE), the barrier layer being arranged with the metal barrier coating towards the bulk layer and the substrate film towards the innermost layer; and - A liquid-tight, heat-sealable polymer product comprising polyethylene contacts the innermost layer.

[0017] In a second aspect of the present invention, there is provided a method of manufacturing a laminated packaging material as described above, comprising laminating the body layer, the barrier layer, the outermost layer and the innermost layer.

[0018] In a third aspect of the present invention, a packaging container is provided, comprising the above-mentioned laminated packaging material. According to one embodiment, the packaging container is at least partially made of the laminated packaging material of the present invention, and according to another embodiment, it is completely made of the laminated packaging material.

[0019] In a fourth aspect of the present invention, a method of manufacturing a packaging container is provided.

[0020] All features described in conjunction with any aspect of the invention may be used on any other aspect of the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings, in which:

[0022] Figure 1 A cross-sectional view showing a laminated packaging material according to a preferred embodiment of the present invention.

[0023] Figure 2a and 2b Shows Figure 1 The lamination step process in the manufacture of the laminated packaging material.

[0024] Figure 3a , 3b , 3c and 3d show the Figure 1 A typical example of a liquid carton packaging container produced from this laminated packaging material.

[0025] Figure 4 Shows how this liquid carton packaging container is made of Figure 1 The principle of manufacturing laminated packaging materials in a continuous roll-fed, form, fill and seal process.

[0026] Figure 5 It is used for physical vapor deposition to form Figure 1 Schematic diagram of an example of an apparatus for laminating the barrier layer of the packaging material.

[0027] Figure 6 is a graph showing the package weight loss results for the laminated packaging material F2356-2 of Example 1 and the comparative laminated packaging material.

[0028] Figure 7 is a graph showing the opening force results for the laminated packaging material F2356-2 of Example 1 and a comparative laminated packaging material. DETAILED DESCRIPTION

[0029] The term "long-term storage" used in conjunction with the present invention means that the packaging container should be able to maintain the quality (i.e. nutritional value, hygienic safety and taste) of the packaged food under ambient conditions for at least 1 or 2 months, for example at least 3 months, preferably longer, for example 6 months, for example 12 months or more.

[0030] The term "package integrity" generally refers to the sealing of the package, i.e., the leak-proofness or resistance to breakage of the packaging container. The term includes the resistance of the package to the invasion of microorganisms (such as bacteria, dirt and other materials) that may spoil the filled food and shorten the expected shelf life of the package.

[0031] One major contribution of a laminated packaging material to the integrity of the package is good internal adhesion between adjacent layers of the laminate. Another contribution derives from the material's resistance to defects (e.g. pinholes, tears, etc. within each material layer itself), and yet another contribution derives from the strength of the sealing joints by which the materials are sealed together when forming the packaging container. Thus, with respect to the laminated packaging material itself, the integrity focuses primarily on the adhesion of the individual laminate layers to their adjacent layers, as well as on the quality of the individual material layers. With respect to the sealing of the package, the integrity focuses primarily on the quality of the sealing joints, which is ensured by a well-functioning and robust sealing operation in the filling machine, which in turn is ensured by appropriate heat sealing properties of the laminated packaging material.

[0032] The term "liquid or semi-liquid food" generally refers to a food with a flowing content, i.e. including foods with a high viscosity, such as sauces, pastes and soups, and foods which may optionally contain food chunks. Dairy products and milk, soy, rice, grain and seed drinks, fruit juices, nectar, still drinks, energy drinks, sports drinks, coffee or tea drinks, coconut water, wine, soups, tomatoes, sauces (such as pasta sauces) and olive oil are some non-limiting examples of the foods contemplated.

[0033] The term "sterile" in relation to packaging materials and packaging containers refers to conditions under which microorganisms are eliminated, inactivated or killed. Examples of microorganisms are bacteria and spores. Typically, when a product is aseptically packaged in a packaging container, an aseptic process is used. In order to maintain sterility during the shelf life of the package, the integrity of the package is of course very important. For a long shelf life of filled foods, it may also be important that the package has barrier properties to gases and vapors (e.g. to oxygen) in order to preserve its original taste and nutritional value, such as its vitamin C content.

[0034] The term "body layer" generally means the thickest layer or the layer containing the most material in a multilayer laminate, ie, the layer that contributes most to the mechanical properties and dimensional stability of the laminate and a packaging container (such as paperboard or carton) folded from the laminate.

[0035] The term "polyethylene" refers to a polymer comprising about 90 to 100 mole percent ethylene monomers. There are various types of polyethylene, as explained below.

[0036] The density of low-density polyethylene (LDPE) is 917 to 930 kg / m 3 It is usually polymerized from ethylene monomers only and has a branched polymer chain structure (on about 2% of the carbon atoms), so its molecules are not tightly packed and have low crystallinity, so its density is lower than that of linear polyethylene, such as linear low-density polyethylene LLDPE or high-density polyethylene HDPE.

[0037] The term "linear low density polyethylene" (or "LLDPE") covers all linear low density polyethylene, including "ZN-LLDPE" polymerized by Ziegler-Natta type catalysts, and "m-LLDPE" polymerized by so-called "constrained geometry" or "single-site" catalysts (such as "metallocene" catalysts), as well as other linear low density polyethylenes. ZN-LLDPE and m-LLDPE (also called "mPE") are generally produced by copolymerizing ethylene monomers with C4-C8, more preferably C6-C8 alpha-olefin alkylene monomers, the latter in the presence of a metallocene catalyst. The comonomer content is generally 1 to 10 mol%, suitably 8 to 10 mol%. LLDPE has a large number of short chain branches. Due to the absence of long chain branches, it is structurally different from traditional low density polyethylene (LDPE). LLDPE polymers generally have a narrower molecular weight distribution than traditional LDPE (especially m-LLDPE) and have significantly different rheological properties.

[0038] The density of high-density polyethylene (HDPE) is 930 to 970 kg / m 3 The comonomer content is typically up to 2 mol%. The absence of branching is ensured by appropriate choice of catalyst (eg ZN catalyst) and reaction conditions.

[0039] The term "dispersion coating" herein relates 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 substantially non-porous solid film after drying. The term "dispersion" therefore also encompasses any solution, suspension, emulsion or solution or mixture thereof capable of providing such a coating after drying. Vinyl alcohol polymers, such as polyvinyl alcohol (PVOH, PVAL) and ethylene-vinyl alcohol copolymers with a low ethylene content are typical polymers suitable for dispersion coating, but in practice, for example at a high degree of saponification, it may be a polymer solution, or a mixture of dispersed and dissolved PVOH or EVOH. The barrier layer or coating coated with the dispersion is formed by a dispersion coating (also called "liquid film coating") technique. The aqueous dispersion may contain fine polymer particles in a suspension or emulsion, and is therefore a latex.

[0040] The barrier layer includes an oriented substrate film including 50 to 100 weight percent high density polyethylene.

[0041] Suitably the total amount of comonomer present in the HDPE is from 0.0 to 0.40 mol%, more preferably from 0.01 to 0.30 mol%, most preferably from 0.02 to 0.20 mol%. Examples of such membranes are given in EP4052902 to Borealis, for example the resin Borstar FB5600 from Borouge.

[0042] Preferably, the density of HDPE is 950 to 965 kg / m 3 , and / or a melt flow index at 190°C / 2.16kg of 0.1 (or less) to 2.0 g / 10 min (measured according to ISO 1133).

[0043] Suitably, the film is a multilayer film, for example comprising a core layer and skin layers. Suitably, the skin layers are based on an ethylene terpolymer, containing an alpha-olefin comonomer, for example a C4 or C6 alpha-olefin.

[0044] The barrier layer also includes a first vinyl alcohol polymer barrier coating on the substrate film and a second vapor deposited metal barrier coating on the vinyl alcohol barrier coating.

[0045] The barrier layers are arranged in a laminated packaging material with the metal barrier coating towards the bulk layer and the substrate film towards the innermost layer. This is referred to as "coating facing laminate" (CFL). The opposite arrangement is referred to as "coating facing inside" (CFI).

[0046] Preferably, the barrier layer substrate film comprises 60 to 100 wt% HDPE, more preferably 80 to 100 wt% HDPE, most preferably 90 to 100 wt% HDPE.In a preferred embodiment, the barrier layer substrate film consists of HDPE.

[0047] Preferably, the barrier layer substrate film has a single melting peak as measured by differential scanning calorimetry (DSC) under the conditions defined in CN115257108 with reference to DIN EN ISO 11357-1:2010-03.

[0048] Preferably, the oriented substrate film is uniaxially oriented in the machine direction (MD) (also referred to as "MDO", "MO", "M" or "O") and is substantially unstretched in the cross direction (CD). Alternatively, it can be biaxially oriented in both the MD and the cross direction (CD) (also referred to as "BO" or "Bo"). Preferably, the uniaxially oriented substrate film has a stretch ratio in the MD of 3 to 12, more preferably 4 to 8. In alternative embodiments where the film is biaxially oriented, a suitable stretch ratio (i.e., stretch ratio in MD: stretch ratio in CD) is in the range of 3 to 12, preferably 5 to 12. This degree of stretching can be achieved using rollers for uniaxial orientation (e.g., as described in WO2009 / 112256, which discloses the use of at least 10 rollers) or in a tenter frame apparatus for biaxial orientation. The high degree of stretching is reflected in the properties of the film, such as high tensile strength and low elongation at break. The film may be (co)extruded and blown or cast before stretching, as also described in WO 2009 / 112256. Preferably, the film is blown before stretching.

[0049] Suitably, the substrate film has a thickness of 10 to 30 μm, more preferably 15 to 25 μm, for example 20 μm. It is important for the openability of the laminated packaging material that the substrate film is not too thick while still providing good mechanical properties.

[0050] Suitably, the breaking strength of the substrate film is 130 to 160 MPa in MD and / or 20 to 25 MPa in CD. Suitably, the breaking elongation of the substrate film is 40 to 90% in MD and / or 300 to 1100% in CD. MD performance is more important than CD performance. These properties are measured according to ASTM D882 (suitably using an Instron 3365 device with a 100N load cell, a crosshead rate of 100 mm / min, and recording the elongation with a video extensometer).

[0051] Preferably, the vinyl alcohol polymer barrier coating comprises polyvinyl alcohol (PVOH, PVAl) and / or polyethylene vinyl alcohol (EVOH). EVOH is particularly preferred.

[0052] Kuraray is sold under the trade name EVAL TM Suitable EVOH grades are provided. Preferably, the ethylene comonomer content is in the range of 27 to 44 mol%, more preferably 27 to 32 mol%, as such grades provide particularly good oxygen barrier properties and are suitable for use in mono-oriented films. A suitable grade is F171B (ethylene comonomer content 32 mol%).

[0053] Preferably, the vinyl alcohol polymer barrier coating is coextruded with the substrate film. This is particularly applicable to EVOH. Alternatively, the vinyl alcohol polymer can be coated on a pre-oriented substrate film, for example by dispersion coating. This is applicable to PVOH, which has a higher solubility in water than EVOH, and also to EVOH; however, heat drying is difficult on HDPE substrate films.

[0054] Preferably, the vinyl alcohol polymer barrier coating has a thickness of 0.5 to 3 μm, more preferably 1 to 2 μm.

[0055] Preferably, the metal of the second barrier coating is aluminum. The vapor deposited barrier coating is preferably applied by physical vapor deposition (PVD) or chemical vapor deposition. This layer is also referred to herein as "metallised" or "met".

[0056] Typically, due to the nature of the metallization coating process used, aluminum metallization layers inherently have a thin surface portion composed of aluminum oxide.

[0057] The purpose of the metallized aluminum coating may be to provide oxygen barrier properties and / or to provide water vapor barrier properties to protect the inherent oxygen barrier properties of the first barrier coating. As described above, gas barrier polymer coatings are typically sensitive to moisture and therefore their oxygen barrier properties deteriorate as the moisture content of the laminate increases. The metallized layer on such a moisture sensitive coating effectively protects the coating from the migration of moisture from humid or liquid foods within the packaging container. It is therefore important that the metallized coating completely covers the oxygen barrier coating beneath it and remains intact throughout the lamination operation, folding and forming operations so that the filled package still has effective barrier properties to the migration of oxygen and water vapor.

[0058] Preferably, the second vapor deposited metal barrier coating has a thickness of 2 to 200 nm, such as 2 to 150 nm, such as 2 to 100 nm, such as 5 to 80 nm, such as 5 to 50 nm, 10 to 50 nm, or 25 to 50 nm.

[0059] Such thin coatings do not generate scrap or waste when used laminated packaging materials containing such coatings are recycled in conventional cellulose fiber recycling streams, and they do not require much material to provide the benefits.

[0060] Typically, below 5nm, the barrier properties of the metallization layer may be too low to be useful, while above 200nm, such as above 100nm, such as above 50nm, depending on the type of vapor deposited coating, the barrier coating may be less flexible and therefore more susceptible to cracking, and the cost will also be higher. In addition, due to the higher heat load when metallizing the substrate film for a longer period of time, the thermal stability of the metallization process will be lower. The coating quality and adhesion may be adversely affected.

[0061] Preferably, the optical density of the coating is from 1.8 to 4, more preferably from 1.8 to 3. Such optical density provides light-barrier properties.

[0062] Suitable barrier layers are metallized films supplied by Constantia Flexibles of Austria, such as the interlayer used in their EcoLam High Plus materials.

[0063] The thickness of the paper or paperboard body layer used in the present invention is generally about 100 μm to about 600 μm, and the surface weight is about 100 to 500 g / m 2 (gsm), preferably about 200 to 300 g / m 2 and may be a conventional paper or paperboard with suitable packaging qualities. The purpose of the body layer in the laminated packaging material of the present invention is to provide dimensional stability, rigidity and stiffness to the packaging container, for example for use in moist and humid conditions and / or for storing liquids and wet (heavy) foods. The paper or paperboard body layer may comprise bleached or unbleached virgin fibers, recycled paper materials and / or other renewable fiber materials. The paper or paperboard body layer may be obtained from bleached or unbleached chemical thermomechanical pulp (CTMP), sulfite or sulfate pulp, i.e. produced using a sulfite or sulfate production process. The paper or paperboard body layer may comprise a clay coating or a polymer coating, such as a starch-based polymer coating (starch coating). Polymer coatings, such as starch-based polymer coatings, may also contain small amounts of particles such as carbonates or clays. The paperboard may have a brown natural printing surface without a clay coating, which may be regarded as an original uncoated printable surface. The paper or paperboard bulk layer may be an unbleached paperboard, which may be clay coated, starch coated, or uncoated, such as clay coated, starch based polymer coated, or uncoated unbleached CTMP, or clay coated, starch based polymer coated, or uncoated unbleached kraft paperboard, or clay coated double paperboard. The paper or paperboard bulk layer may be an unbleached liquid packaging board (LPB), which may be coated with a starch based polymer coating, or uncoated. Clay coated double paperboard is preferred. For larger packages, 400 to 500 μm paperboard is preferred. For a sub-packaging capacity of 150 to 250 ml, the bending stiffness is preferably 80 mN.

[0064] The liquid-tight thermoplastic polymer outermost and innermost layers do not typically add identifiable barrier properties to migrating gas molecules or small molecules. Their purpose is to provide a direct barrier to prevent water or other liquids from penetrating the cellulose-based body material and other sensitive layers, and to act as a sterile barrier, maintaining the integrity of the package to protect the filled contents within the package. Liquid barrier layers can also prevent water vapor from migrating to the cellulose and causing it to become wet, but they cannot maintain the moisture content of the laminate structure to zero or to the low levels of "dry" paper (approximately 7-8% at ambient temperature, i.e., 23°C / 50% relative humidity). The moisture content in the laminated carton material of a packaging container filled with liquid is typically quite high, and unless another water vapor barrier, such as a vapor deposited metallized layer, is also included, migration through the material will occur.

[0065] The outermost layer can be a protective polymer layer or coating to prevent dirt and moisture from reaching the interior of the laminate, such as a polymer layer, such as a thermoplastic polymer layer, such as a liquid-tight and heat-sealable polymer layer, as discussed in more detail below.

[0066] The innermost layer of liquid-tight and heat-sealable material comprises polyethylene, preferably consists of polyethylene. The innermost layer may comprise two or more sublayers. Optionally, one sublayer may be extruded at a higher temperature than another sublayer. The sublayers may have two different compositions, such as an LDPE layer and an innermost blended layer, or two blended layers with different compositions.

[0067] Suitable thermoplastics for the liquid-tight and heat-sealable outermost layer are polyolefins, such as polyethylene and polypropylene (PP) homopolymers or copolymers, preferably polyethylene, more preferably polyethylene selected from LDPE, LLDPE, m-LLDPE and blends or copolymers thereof. According to one embodiment, the liquid-tight and heat-sealable outermost layer is of LDPE, while the heat-sealable liquid-tight innermost layer is a blended composition of m-LLDPE and LDPE to obtain optimal lamination and heat-sealing properties. In a preferred embodiment, the innermost layer comprises 50 to 90 wt.% mLLDPE and 10 to 50 wt.% LDPE, for example 70 wt.% mLLDPE and 30 wt.% LDPE. However, it is also conceivable that the proportion of mLLDPE in such a blend is lower, for example 10 to 50 wt.%, for example 30 wt.%.

[0068] The outermost layer is preferably transparent. In this way, any printed decorative pattern applied on the outside of the body layer can be seen. This helps to inform the audience of the packaging content, packaging brand and other relevant consumer information in retail facilities and / or food stores. In one embodiment, a separate thin printing substrate paper layer is used for printing together with a cheaper brown body layer without a clay coating. The printing substrate layer is laminated to the body layer, for example, by wet lamination with an aqueous adhesive (such as starch or ethylene-vinyl acetate copolymer, EVAc). By omitting the clay coating, the use of inorganic particles can be avoided.

[0069] The outermost layer is usually applied at a thickness of 5 to 20 μm, for example 10 to 15 μm, or 5 to 15 g / m 2 , for example 8 to 15 g / m 2 The innermost layer may be applied at a thickness of 10 to 50 μm, such as 15 to 40 μm, such as 20 to 40 μm, or 10 to 50 g / m 2 , e.g. 15 to 45 g / m 2 , e.g. 20 to 45 g / m 2 or 20 to 40 g / m 2 .

[0070] The outermost layer and / or the innermost layer is preferably applied by extrusion coating.

[0071] The metal coating of the barrier layer can be bonded to the bulk layer via an intermediate bonding layer, preferably a thermoplastic polymer. According to one embodiment, the intermediate bonding layer is a polyolefin layer. The thermoplastic polyolefin-based materials listed for the outermost layer and the innermost layer, in particular polyethylene, are also suitable for the intermediate bonding layer.

[0072] The intermediate adhesive layer may bond the bulk layer to the barrier layer by melt extrusion, thereby laminating the intermediate adhesive layer between the bulk layer web and the barrier layer web, and simultaneously pressing the three layers together while advancing through the nip of laminating rollers, thereby providing a laminated structure by extrusion lamination.

[0073] In an alternative preferred embodiment, the intermediate bonding layer comprises two sub-layers. These are preferably applied at different temperatures. Preferably, the sub-layer adjacent to the bulk layer uses a higher temperature (e.g. 325°C) and the sub-layer adjacent to the metal coating uses a lower temperature (e.g. 300°C).

[0074] The total amount of the intermediate adhesive layer applied is usually 10 to 25 μm, such as 10 to 20 μm, such as 10 to 15 μm, or 9 to 23 g / m 2 , for example 9 to 20 g / m 2 , for example 9 to 18 g / m 2 or 9 to 14 g / m 2Where two sub-layers are used, these may for example be applied in amounts of 13 gsm and 7 gsm respectively, or two sub-layers may be applied, each at 7.5 gsm.

[0075] As an alternative to the thermoplastic intermediate adhesive layer, the bulk layer can be wet laminated to the barrier layer using an aqueous adhesive composition. In one embodiment, the barrier coating film can be dispersion coated with an aqueous adhesive polymer or adhesive composition and then laminated to the inside of the bulk layer by pressing the surfaces together in a lamination nip. The advantages of such wet lamination are reduced demand for polymeric materials in the laminate structure and potential redispersibility of the thin adhesive layer in a subsequent recycling step to recover the cellulose fibers of the bulk layer.

[0076] In a preferred embodiment, adhesive or tie layers within the laminate, in particular between the barrier layer and the innermost layer, are avoided. Such tie layers are usually so-called adhesive thermoplastic polymers, such as modified polyolefins, which are mainly based on copolymers or graft copolymers of LDPE or LLDPE with monomer units containing functional groups, such as carboxyl or glycidyl functional groups, such as (meth)acrylic acid monomers or maleic anhydride (MAH) monomers (such as EAA, EMAA, ethylene-glycidyl (meth)acrylate copolymers (EG(M)A) or MAH-g-PE). Other examples of such modified polymers or adhesive polymers are so-called ionomers or ionomeric polymers.

[0077] Preferably, there is no adhesive polymer (such as modified polyolefin; more preferably, no adhesive, substrate or anchoring agent other than polyethylene) between the barrier layer substrate film and the innermost layer. In a preferred embodiment, the barrier layer substrate film is immediately adjacent to the innermost layer.

[0078] Furthermore, preferably no adhesive polymer is present between the second barrier coating and the intermediate adhesive layer.

[0079] In a preferred embodiment, no EAA and / or EMAA is present in the laminated packaging material. More preferably, no adhesive polymer is present in the laminated packaging material.

[0080] Preferably, the outermost layer, innermost layer, intermediate adhesive layer and / or barrier layer substrate film (preferably the laminate packaging material as a whole) does not include carbon black and / or titanium dioxide. More preferably, these layers (again preferably the laminate packaging material as a whole) do not include any particulate fillers and / or pigments, except for an optional clay coating to provide a white printing surface on the bulk layer.

[0081] In a preferred embodiment, the laminated packaging material is composed of a cellulose based body material, a polyethylene based material, a vinyl alcohol polymer and a metal.

[0082] Preferably, the laminated packaging material comprises at most 1 wt % of other materials, in addition, the cellulose-based material (including optional clay coating) is at least 70 wt %, and the balance is polyethylene-based material and vinyl alcohol polymer. More preferably, the laminated packaging material comprises 72 wt % of cellulose material and 28 wt % of polyethylene-based material and vinyl alcohol polymer. In a preferred embodiment, the vinyl alcohol polymer content is about 3-4 wt % of the polyethylene part, for example 3.1 wt % or 3.9 wt %. The metal content is very low, for example 0.17 wt % of the polyethylene part.

[0083] In a preferred embodiment, the laminated packaging material comprises at least one laminated open hole, wherein the hole in the bulk layer is covered by other layers of the laminated packaging material.

[0084] Preferably, the oxygen permeability of the laminated packaging material at 100% O2 / 23°C / 50% RH is 0.5 cm 3 / (m 2 24h) or less, more preferably 0.4cm 3 / (m 2 ·24h) or lower, most preferably 0.3cm 3 / (m 2 24h) or less.

[0085] Preferably, the water vapor transmission rate of the laminated packaging material at 38°C / 90% RH is 2.5 g / (m 2 ·24h) or lower, more preferably 2g / (m 2 ·24h) or lower, most preferably 1.5g / (m 2 24h) or less.

[0086] The method of making a laminated packaging material comprises laminating a bulk layer, a barrier layer, an outermost layer and an innermost layer, and may further comprise coating the barrier layer substrate layer with one or more barrier coatings. The layers of the laminated packaging material may be connected in any order.

[0087] In a preferred embodiment, the body layer and barrier layer are laminated, then the innermost layer is applied, then the outermost layer (or less preferably, then the outermost layer is applied, then the innermost layer). This sequence is called "LID", where L = paperboard is laminated to the barrier layer through an intermediate adhesive layer; I = innermost layer is applied to the barrier layer; D (decoration) = outermost layer is applied to paperboard. A less preferred alternative is called "LDI".

[0088] Alternatively, the bulk layer can initially be connected to the outermost layer. This sequence is called "DLI". This sequence is particularly suitable when the outermost layer is a thin layer coated with a dispersion. In this case, the dispersion coating can be carried out after the bulk layer printing, because printing and dispersion coating are similar coating processes. Extrusion coating of the outermost layer is also possible. DLI is also suitable for protecting the printed decoration on the paperboard from being scratched or worn, or from being scratched or worn in the following lamination station.

[0089] Where a separate printed substrate layer is included, it is typically joined to the bulk layer (eg by wet lamination) prior to the above steps.

[0090] According to another embodiment, the packaging container formed from the laminated packaging material can be partially sealed, filled with a liquid or semi-liquid food and subsequently sealed to the plastic opening or top part of the package by sealing the packaging material to itself, optionally joined to the plastic opening or top part of the package. Ultrasonic heat sealing is preferred.

[0091] Preferably, the packaged product loses less than 5g in 12 months.

[0092] In summary, in preferred embodiments of the present invention, a robust and reliable package with excellent oxygen barrier properties for liquid food packaging for long shelf life and storage can be obtained. Examples and Description of Preferred Embodiments Measurement method

[0093] The paper weight is measured in g / m according to the official test method of ISO 536:2019. 2 The thickness and density are measured in μm and kg / m according to ISO 534:2011 respectively. 3 Measured in units.

[0094] The thickness of each layer can be measured and estimated by taking a section of a sample of the structure and studying it under a SEM microscope. Sectioning can be performed using, for example, a cryo microtome.

[0095] In production, optical density is measured by a densitometer, i.e. an instrument that uses the principle of diffuse light transmission (such as Macbeth, Tobias or similar instruments). This instrument is suitable for measuring the optical density values ​​of films coated with aluminum metal. The accuracy and precision of the measurement are very high, about + / - 0.2 OD and about + / - 0.01 OD respectively in the measurement range of 0 to 6.60 OD. In laboratory measurements, a spectrophotometer can alternatively measure the light transmittance over the full visible spectrum (380-800 nm). According to the formula OD = -log 10The optical density is calculated based on the light transmittance (T, also called I1 / I0, the ratio of incident light to transmitted light) value at 560 nm. The value obtained is equally accurate (+ / - 0.2OD) and comparable to the light transmission densitometer value.

[0096] Oxygen transmission rate was measured according to ASTM F1927-14 at 100% oxygen at 23°C / 50% RH using an Oxtran 2 / 22 (Mocon) instrument based on a coulometric sensor.

[0097] Water vapor transmission rate was measured according to ASTM F1249 at 38°C / 90%RH. Adhesion peel test

[0098] The short-term adhesion results of laminates treated with a standard solution containing free fatty acids (stored at 40°C) correlated closely with the results of long-term storage of orange or other citrus juices.

[0099] Adhesion peel testing was performed in the machine direction according to ASTM D903 with the following settings: 180° peeling angle Peeling speed: 100mm / min Width: 15mm.

[0100] The peel force is measured in N / m. The peel force can be measured for the "inner adhesion" between the barrier layer and the innermost layer and for the "outer adhesion" between the barrier layer and the intermediate adhesive layer. Package weight test

[0101] This is a simplified test used to monitor how water vapor transmission of a filled package affects the moisture content of the filled liquid product.

[0102] 10 packages filled with water and numbered 1 to 10 are stored in each environment per variant. The packages must be placed in the storage environment conditions for 24 hours before the first weighing. The test is performed in Tetra Pak standard environment: 23°C / 50% RH. The same samples are weighed every 2 weeks for 4 months and the package weight is reported.

[0103] Package weight loss = package weight at time x - package weight at measurement time (at Time)

[0104] Shelf life was estimated by linear extrapolation of package weight loss to the storage time at which 5 g package weight was lost. Straw puncture opening test

[0105] The following test method is used to determine the maximum force required to puncture or first penetrate a laminated straw hole (also known as "PPH", pre-punched hole) film.

[0106] During the manufacturing and conversion operations, pre-cut laminated straw holes are provided for the laminates tested, one for each packaging unit. Therefore, the body layer of paper or paperboard is pre-cut at intervals to obtain a small hole with a diameter of 6 mm for each packaging unit, suitable for the opening of the straw. In the subsequent lamination operation, in order to form the laminate tested in this paper, these straw holes are laminated (over-laminated), that is, covered by all other layers of the laminate. In the cardboard hole area, the outermost LDPE layer adheres to the LDPE intermediate adhesive layer to form a laminated film together with the barrier layer and the innermost layer. A standard compression tester (Zwick Roell) is used to evaluate the maximum force required to open the film by penetrating with an oblique paper straw with a diameter of about 5 mm. Example 1

[0107] Example CFL laminated packaging material F2356-2 / PM012036 was prepared having the following structure: LDPE 12gsm / Paperboard / LDPE 13gsm / LDPE 7gsm / Metalized aluminum layer on the following substrate film: / Coextruded unidirectional EVOH 1-2μm and unidirectional HDPE 20μm / Extrusion coated blend of 70wt% mLLDPE and 30wt% LDPE 25gsm /

[0108] The paperboard was a standard clay-coated double-ply paperboard BK-G from Billerud with a bending stiffness of 80 mN and a basis weight of 200 g / m 2 .

[0109] The barrier layer (HDPE-EVOH-metal) is a metallized film provided by Constantia Flexibles of Austria for the middle layer of its EcoLam High Plus material.

[0110] The layers are laminated in a "DLI" order, i.e. the outermost LDPE (decoration, D) layer is extrusion coated onto the paperboard; the paperboard is laminated (L) to the barrier layer via an LDPE intermediate adhesive layer; and the innermost (I) blended polymer layer is extrusion coated onto the barrier layer.

[0111] The example laminated packaging material was compared to a comparative example CFI laminated packaging material F2356-4 having the following structure: LDPE 12gsm / paperboard / LDPE 13gsm / LDPE 7gsm / coextruded unidirectional HDPE 20μm and unidirectional coextruded EVOH 1-2μm / coextruded metallized aluminum layer on substrate film / EAA 6gsm / blend of 70 wt% mLLDPE and 30 wt% LDPE 19gsm /

[0112] This corresponds to the example laminated packaging material, but has the barrier layers (HDPE-EVOH-metal) arranged in the opposite way (CFI instead of CFL) and includes an EAA adhesive layer for bonding the metallized aluminum layer to the innermost layer comprising mLLDPE. In this arrangement, EAA is necessary for long-term adhesion.

[0113] The long-term adhesion of the Examples and Comparative Examples was tested using an adhesion peel test by pulling the "inner material portion" including the barrier coating film and the innermost layer of mLLDPE+LDPE blend away from the bulk layer coated with the LDPE intermediate adhesive layer by a peeling arm. The results are shown in Table 1.

[0114] Table 1 1: Peel force between laminated PE (middle adhesive layer)-metallization and EVOH-metallization 2: Peel force between laminated PE and metallization 3: Peel force between VOH and metallization 4: Peel force between metallization and EAA

[0115] For this embodiment, even after 21 days, high internal adhesion was seen between the metallized aluminum layer and the innermost layer containing mLLDPE, so that adhesion failure occurred between the intermediate lamination layer of LDPE and the metallized coating (external adhesion). The initial adhesion strength was very high, so that the adhesion between the metallized layer and the intermediate LDPE layer, or between the metallized coating and the EVOH barrier layer of the film, was damaged to varying degrees at about up to 100 N / m. For the comparative example, after 21 days, no adhesion was seen between the metallized aluminum layer and the EAA inner layer. Although the initial adhesion in the "inner material part" was high, so that adhesion failure occurred between the EVOH barrier layer and the metallized layer, the interlayer adhesion of the inner material part still failed at about 25 N / m, and the adhesion value was quite low. Therefore, the laminated packaging material of the embodiment of the present invention has higher robustness to long-term adhesion failure caused by free fatty acid migration.

[0116] The oxygen permeability of the laminated packaging material of the example was measured at 100% O2 / 23°C / 50% and was found to be an average of 0.28 cm 3 / (m 2 ·24h).

[0117] The water vapor transmission rate of the laminated packaging material of the example was measured at 38°C / 90%RH and was found to be 0.15 g / (m 2 ·24h).

[0118] Laminated packaging materials with MoPE-metal (PM12036, according to the invention), BoPP-metal (PM11974, comparative example) and BoPP-AlOx (PM12041, comparative example; AlOx is aluminum oxide) barrier layers were tested for product loss using the package weight test. Figure 6 As shown. For the preferred MoPE-metal barrier layer, the shelf life is 58 months. For the comparative barrier layer, the shelf life is 25 months (BoPP-metal) and 16 months (BoiP-AlOx), respectively. This confirms that the MoPE-metal barrier layer in the preferred embodiment of the present invention provides better water vapor barrier properties, thereby reducing product loss and extending the shelf life.

[0119] The openability of paper straws was tested using the straw puncture test on laminated packaging materials with MoPE-metal (according to the invention) and BoPP-metal (comparative example) barrier layers. Figure 7 As shown. BoPP film requires a high opening force, causing the tip of the paper straw to deform or bend back. The MoPE film used in the barrier layer of the preferred embodiment of the present invention has a much lower opening force (3.4 times lower in MD; 2.6 times lower in CD) and is not challenging for consumers to open. Example 2

[0120] A second example CFL laminated packaging material PM012040 having the following structure was prepared: LDPE 12gsm / Paperboard / LDPE 7.5gsm / LDPE 7.5gsm / Metallized aluminum layer on the following substrate film: / Coextruded unidirectional EVOH 1-2μm and unidirectional HDPE 20μm / Extrusion coating blend of 70wt% mLLDPE and 30wt% LDPE 15gsm /

[0121] Compared to the laminated packaging material of Example 1, this laminated packaging material uses less LDPE (including mLLDPE) and therefore has a higher proportion of renewable cellulose based materials.

[0122] In addition, regarding the attached drawings:

[0123] exist Figure 1 In the figure, a laminated packaging material 10 for liquid carton packaging is shown in cross section, wherein the laminated material comprises a paperboard body layer 11, the bending force of which is 80 mN and the grammage is about 200 g / m2 , further comprising a liquid-tight and heat-sealable polyolefin outer layer 16 applied on the outer side of the body layer 11, which side faces the outside of the packaging container made of the packaging laminate. The layer 16 is transparent to show the printed decorative pattern 17 applied on the outer side of the paperboard body layer.

[0124] The polyolefin outer layer 16 is a conventional low density polyethylene (LDPE) of heat sealable quality, but may also include other similar polymers, including LLDPE. It is applied at a rate of about 12 g / m 2 .

[0125] The barrier layer 12 is arranged on the side of the body layer 11 opposite to the outer layer 16. The barrier layer 12 includes an oriented HDPE substrate film 12a arranged farthest from the body layer 11, a first barrier coating 12b of coextruded EVOH on the substrate film 12a, and a second barrier coating 12c of metallized aluminum on the first barrier coating 12a. The second barrier coating 12c is arranged closest to the body layer 11 (coating facing the laminate, CFL) and adhered to the body layer 11 through an intermediate adhesive layer 13 of LDPE (optionally including an additional sublayer 13a).

[0126] The liquid-tight and heat-sealable innermost layer 14 is arranged on the side of the barrier layer 12 which will be facing the inner side of the packaging container made of the packaging laminate, i.e. the layer 14 will be in direct contact with the packaged product. Thus, the heat-sealable innermost layer 14 will form a strong transverse heat seal for the liquid packaging container made of the laminated packaging material, comprising one or more polyethylene combinations selected from LDPE, LLDPE and m-LLDPE. The heat-sealable innermost layer 14 may consist of one or alternatively two or more layers of the same or different kinds of LDPE or LLDPE or their blends, and adheres well to the substrate film 12a of the barrier layer 12 without the need for an intermediate coextruded tie layer, such as an ethylene acrylic acid copolymer (EAA) layer. Its application amount is 15 or 25 g / m 2 .

[0127] Turning to the production of the barrier layer, Figure 5 Schematic diagram of an example of an apparatus 50a for PVD of a metal coating such as aluminum on a barrier layer substrate film. The substrate film 54b (12a / b) is subjected to continuous evaporative deposition of evaporated aluminum on its pre-coated side to form a metallized aluminum layer (12c). The barrier coating substrate film 54c (12) of the present invention is formed. Aluminum vapor can be formed by ion bombardment of an evaporation source of a solid aluminum sheet 51.

[0128] Figure 2a Shows Figure 1 The laminated packaging material 10 is manufactured in the form of a laminated packaging material 10, wherein the body layer 11 is laminated to the barrier layer 12.

[0129] The bulk layer 11 is laminated to the barrier layer 12 via an LDPE intermediate adhesive layer 13, 23. The intermediate adhesive layer 13 is formed by melt extruding a thin polymer melt curtain between the webs comprising the bulk layer 11 and the barrier layer 12, respectively, so that the bulk layer 11 and the barrier layer 12 are laminated to each other when all three layers pass through the nip 21 between the press roll and the cold roll, thereby cooling the laminate 24 to properly solidify the extruded LDPE intermediate adhesive layer 13. The amount of the intermediate adhesive layer 13 is 20 g / m 2 , corresponding to a thickness of about 21.7 μm. In an alternative embodiment, two LDPE sub-layers are used for the intermediate adhesive layer 13, 23 to reduce the thermal load on the barrier layer.

[0130] The resulting pre-laminate 24 is sent on reels for intermediate storage or directly to a subsequent lamination operation.

[0131] exist Figure 2b The resulting roll of pre-laminated board 24 consisting of bulk layer 11 and barrier layer 12 is directly obtained from Figure 2a lamination operation, or splicing and unwinding from intermediate storage reels to further lamination steps.

[0132] The non-laminated side of the body layer 11, ie its printed side, is joined at the cooled nip 27 to a molten polymer curtain 27a of LDPE which will form the outermost layer 16 of the laminated packaging material 10, the LDPE 27a being extruded from an extruder feed block and die 27b.

[0133] The pre-laminate, now coated with the outermost layer 16 on its printed side (outside), then passes through a second extruder feed block and die 28b and a lamination nip 28 where a curtain of molten polymer 28a is joined and coated to the other side of the pre-laminate, i.e. the uncoated inner side of the barrier layer 12. Thus, the heat sealable innermost layer 14 is coextrusion coated onto the barrier layer substrate film of the barrier layer to form a finished laminated packaging material 29, 10 which is ultimately wound onto a storage reel not shown.

[0134] like Figure 2a As shown, the two coextrusion steps at the lamination roll nips 27 and 28 may alternatively be carried out in reverse order as two consecutive steps and may be carried out before or after the lamination of the two webs at the lamination nip 21 .

[0135] The body layer 11 may be provided with holes (not shown) which are covered by other layers of the laminated packaging material 10 to form pre-laminated holes.

[0136] Figure 3aAn embodiment of a packaging container 30a produced by a packaging laminate 10 according to the present invention is shown. The packaging container is particularly suitable for beverages, sauces, soups, etc. Typically, the volume of such a package is about 100 to 1000 mL. It can be in any configuration, but is preferably brick-shaped, with longitudinal and transverse seals 31a and 32a, respectively, and optionally with an opening device 33 on a pre-laminated hole (not shown). In another embodiment not shown, the packaging container can be formed into a wedge shape. In order to obtain this "wedge shape", only the bottom of the package is folded and formed so that the transverse heat seal at the bottom is hidden under the triangular corner wings, which are folded and sealed to the bottom of the package. The top section of the transverse seal is not unfolded. In this way, the only partially folded packaging container is still easy to handle and is stable enough to be placed on a shelf in a food store or on any flat surface.

[0137] Figure 3b An alternative example of a packaging container 30b produced from an alternative packaging laminate 10 according to the present invention is shown. The alternative packaging laminate is thinner due to having a thinner paper body layer, so its dimensional stability is not sufficient to form a parallelepiped or wedge-shaped packaging container and will not fold into shape after the transverse seal 32b. The packaging container will remain a pillow bag-like container and be distributed and sold in this form.

[0138] Figure 3c A gable top package 30c is shown, folded from a pre-cut sheet or blank, made from a laminated packaging material 10, comprising a body paperboard layer 11 of the present invention and a barrier layer 12. Optionally, there may be an opening device and / or a pre-laminated hole (not shown). A flat top package may also be formed from a similar material blank.

[0139] Figure 3d A bottle-shaped package 30d is shown which is a combination of a sleeve 34 and a top 35 formed from a pre-cut blank of the laminated packaging material 10 of the present invention, the top 35 being formed by injection molding plastic in combination with an opening device such as a screw plug. For example, these types of packages are (Tetra )and (Tetra These particular packages are formed by attaching a moulded top 35 with an opening device attached in a closed position to a tubular sleeve 34 of laminated packaging material, sterilising the bottle cap capsule thus formed, filling it with the food product and finally folding over to form the bottom of the package and sealing it.

[0140] Figure 4The principle described in the introduction to the present application is shown, namely that a web of packaging material is formed into a tube 41 by overlapping its longitudinal edges 42, 42' and heat-sealing them to each other, thereby forming an overlapping joint 43. The tube is continuously filled 44 with the liquid food to be filled and divided into individual filled packages by repeated double transverse seals 45 forming the tube at a predetermined distance from each other below the level of the filled content in the tube. The packages are separated 46 by cutting between the double transverse seals (top seal and bottom seal) and finally formed into the desired geometry by folding along prepared crease lines in the material.

[0141] In a preferred embodiment, various advantages are achieved:

[0142] - The laminated packaging material is recyclable. The laminated packaging material has a high proportion of recyclable and renewable (i.e. plant-based) materials, consisting mainly of polyethylene and paper, with very small amounts of aluminum metal (this is approximately 23 wt% of the polyethylene portion or 6.3 wt% of the laminate when 6.3 μm aluminum foil is used, compared to approximately 0.17 wt% of the polyethylene portion or 0.05 wt% of the laminate for Example 1) and EVOH (approximately 3 wt% of the polyethylene portion), which can be recycled together with the polyethylene. Apart from the cellulose fibers, essentially only one polymer (PE) is used. The HDPE barrier substrate layer is adjacent to the innermost layer comprising extruded mLLDPE; the layers are compatible, which means that the use of EAA or other adhesives to connect the barrier layer and the innermost layer can be avoided. As a result, the number of layers in the laminate is smaller. Avoiding the use of adhesives has further production advantages, including reduced complexity in raw material handling and a reduced need for screw purging. The absence of pigment or filler particles, and especially the absence of carbon black, is essential for recycling. Transparent, natural or lighter colors are compatible with PE or PP mechanical recycling; black and dark colors have limited compatibility; materials containing carbon black are not compatible with PE or PP mechanical recycling (Designing for a Circular Economy: Recyclability of polyolefin-based flexible packaging, D4ACE guidelines, CEFLEX, 2020).

[0143] - Openability of the straw holes is good because the unidirectionality of HDPE provides a low opening force, which enables the use of paper straws without the need for other processes to weaken the PPH. Previously it was difficult to maintain a balance between package integrity and openability, and cumbersome solutions were developed for materials related to opening and perforation, such as single-layer pre-cut pieces and perforation or other pre-treatment of the material layers to achieve adequate openability. These difficulties are evident when using biaxially oriented polymer film substrates to stably support thin vapor deposited barrier coatings.

[0144] - The metallized aluminum layer and the EVOH layer together provide good oxygen and water vapor barrier properties.

[0145] - Low product losses due to the low water vapor transmission rate of oriented HDPE compared to barrier substrates such as paper, LDPE or LLDPE.

[0146] - The metallized aluminum layer is insensitive to humidity, while the AlOx vapor deposited layer is sensitive to humidity (BM Henry et al., Thin Solid Films 382 (2001) 194-201; Nehm et al., ACS Appl. Mater. Interfaces 2015, 7, 22121-22127). This is important in liquid packaging.

[0147] -The metallized aluminum layer provides light blocking, which means that the addition of fillers and pigments can be avoided. AlOx does not provide light blocking.

[0148] - Delamination of the EAA adhesive over time due to free fatty acids (FFA) in juice or other acidic food contents is avoided because such adhesives are not used. As discussed in the introduction, such delamination is a problem with long-term storage and can also affect openability. The problem is specific to metal and metallized layers because the FFA migrates to the EAA / metal interface and cannot enter the metal, so it accumulates at the interface. It can be solved by using an adhesive polymer with carboxylic acid functional groups; if long-term shelf life is required, an adhesive polymer with a higher acid content will be required. However, eventually, due to the high concentration of FFA, the adhesion between the metal and the interior will be lost. In contrast, in the preferred embodiment of the present invention, good long-term interlayer adhesion is maintained and the use of EAA is avoided. Oriented HDPE is believed to help to more effectively prevent migration to the metallized coating as this will occur gradually over time.

[0149] Barrier films similar to those used in the present invention (e.g. from Constanta) are known to be useful for dry food applications. However, due to the above-mentioned food interactions, transferring them from dry food to liquid food applications is very challenging.

[0150] Thus, a preferred embodiment of the present invention provides a non-foil or paperboard based laminate packaging material for oxygen sensitive, liquid, semi-solid or wet foods, which does not contain aluminum foil but has excellent oxygen and water vapor barrier properties, is suitable for long-term aseptic packaging, is cost-effective, has good recyclability and environmentally sustainable properties. The laminate is cost-effective, mechanically robust), heat sealable and has good openability.

[0151] Finally, the invention is not limited to the embodiments shown and described above, but may be varied within the scope of the claims.

Claims

1. A laminated packaging material for packaging liquid or semi-liquid food, comprising the following layer sequence: - Liquid-tight polymer outermost layer; - a bulk layer of paper or paperboard or other cellulose based material; - a barrier layer comprising: an oriented substrate film comprising 50 to 100 wt% of high density polyethylene (HDPE), a first vinyl alcohol polymer barrier coating on the substrate film, and a second vapor deposited metal barrier coating on the vinyl alcohol barrier coating, the barrier layer being arranged with the metal barrier coating facing the bulk layer and the substrate film facing the innermost layer; as well as - A liquid-tight, heat-sealable polymer product comprising polyethylene contacts the innermost layer.

2. The laminated packaging material according to claim 1, wherein the substrate film is uniaxially oriented, preferably with a stretch ratio of 3 to 12.

3. The laminated packaging material as claimed in claim 1 or 2, comprising at most 1 wt% of other materials, in addition to which is at least 70 wt% of cellulose-based materials and the remainder of polyethylene-based materials and vinyl alcohol polymers, the laminated packaging material preferably comprising 72 wt% of cellulose materials and 28 wt% of polyethylene-based materials and vinyl alcohol polymers.

4. A laminated packaging material as claimed in any preceding claim, consisting of a cellulose based material, a polyethylene based material, a vinyl alcohol polymer and a metal.

5. The laminated packaging material according to any one of the preceding claims, wherein the barrier layer substrate film comprises 60 to 100 wt% HDPE, preferably 80 to 100 wt% HDPE, more preferably 90 to 100 wt% HDPE.

6. The laminated packaging material according to any one of the preceding claims, wherein the vinyl alcohol polymer barrier coating is coextruded with or dispersion coated on the oriented substrate film.

7. A laminated packaging material as claimed in any preceding claim, wherein the metal is aluminium.

8. The laminated packaging material according to any one of the preceding claims, wherein the barrier layer substrate film is immediately adjacent to the innermost layer.

9. The laminated packaging material according to any one of the preceding claims, wherein no adhesive polymer is present between the barrier layer substrate film and the innermost layer.

10. The laminated packaging material according to any one of the preceding claims, wherein ethylene acrylic acid copolymer (EAA) and / or ethylene methacrylic acid copolymer (EMAA) are absent from the laminated packaging material.

11. A laminated packaging material as claimed in any preceding claim, wherein the innermost layer is extrusion coated.

12. A laminate packaging material as claimed in any one of the preceding claims, wherein the innermost layer comprises low density polyethylene (LDPE), more preferably metallocene linear low density polyethylene (mLLDPE).

13. The laminated packaging material according to claim 12, wherein the innermost layer comprises a blend of mLLDPE and LDPE, preferably 50 to 90 wt% mLLDPE and 10 to 50 wt% LDPE, more preferably 70 wt% mL LDPE and 30 wt% LDPE.

14. A laminated packaging material as claimed in any preceding claim, wherein the outermost layer comprises a polyolefin, preferably polyethylene, more preferably LDPE.

15. A laminated packaging material as claimed in any preceding claim, wherein the metal barrier coating is bonded to the bulk layer via an intermediate bonding layer.

16. A laminated packaging material as claimed in any preceding claim, wherein the intermediate adhesive layer comprises a polyolefin, preferably polyethylene, more preferably LDPE.

17. A laminated packaging material as claimed in any one of the preceding claims, wherein the intermediate adhesive layer comprises two sub-layers, wherein preferably the two sub-layers are applied at different temperatures, more preferably the sub-layer adjacent to the bulk layer is applied at a higher temperature than the sub-layer adjacent to the metal barrier coating.

18. A laminated packaging material as claimed in any one of the preceding claims, wherein the outermost layer, innermost layer, intermediate adhesive layer and / or barrier layer substrate film does not comprise carbon black and / or titanium dioxide.

19. A laminated packaging material as claimed in any preceding claim, wherein the laminated packaging material does not comprise particulate fillers or pigments other than the optional clay coating of the body layer.

20. The laminated packaging material according to any one of the preceding claims, comprising at least one laminated open hole, wherein the hole in the bulk layer is covered by other layers of the laminated packaging material.

21. A laminated packaging material as claimed in any one of the preceding claims, wherein the bulk layer is an unbleached paperboard, which may be uncoated or coated with a starch-based polymer coating, preferably the bulk layer is an unbleached liquid packaging board (LPB), which may or may not be coated with a starch-based polymer coating.

22. A method of manufacturing a laminated packaging material as claimed in any one of claims 1 to 21, comprising laminating the body layer, barrier layer, outermost layer and innermost layer.

23. The method of claim 22, further comprising coating the barrier layer substrate layer with one or more of the barrier coatings.

24. The method of claim 22 or 23, comprising the following steps in any order: (L) Laminating the bulk layer to the barrier layer (I) Applying the innermost layer (D) applying the outermost layer.

25. A packaging container comprising the laminated packaging material according to any one of claims 1 to 21.

26. A method of manufacturing a packaging container according to claim 25.

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