Method for manufacturing laminated packaging material, laminated packaging material, and packaging container made therefrom

Abstract

The present invention relates to a method for producing a laminated cellulose-based packaging material for liquid or semi-liquid foods, the laminate packaging material having a bulk material layer and a further sheet laminated to the bulk material layer by means of an aqueous adhesive composition. The present invention further relates to a laminate packaging material obtained by this method and a packaging container for liquid food packaging comprising or made from the laminate packaging material obtained by this method.

Description

[Technical field]

[0001] The present invention relates to a method for producing a laminated packaging material and to the laminated packaging material obtainable by this method.

[0002] Furthermore, the present invention relates to a packaging container that includes or is entirely made from the laminate packaging material, in particular, the present invention relates to a packaging container intended for liquid food packaging that includes the laminate packaging material. [Background technology]

[0003] Single-use disposable packaging containers for liquid foods are often produced from packaging laminates based on paperboard or cardboard. One such commonly existing packaging container is sold under the trademark Tetra Brik Aseptic® and is mainly used for the aseptic packaging of liquid foods such as milk, fruit juices, etc., sold for long-term ambient storage. The packaging material in this known packaging container is typically a laminate comprising a bulk layer of paper or paperboard and an outer liquid-tight layer of thermoplastic material. To make the packaging container airtight, in particular oxygen gas-tight, for example for the purpose of aseptic packaging and packaging of milk or fruit juice, the laminate in these packaging containers usually comprises at least one additional layer, usually aluminum foil.

[0004] On the inside of the laminate, i.e. on the side of the container produced from the laminate that is intended to face the filled food contents, there is an innermost layer, attached to the aluminum foil, which may consist of one or more partial layers comprising a heat-sealable thermoplastic polymer, such as an adhesive polymer and / or a polyolefin, and, outside the bulk layer, there is an outermost heat-sealable polymer layer.

[0005] Packaging containers are generally produced using modern high-speed packaging machines of the type that form, fill and seal packages from webs of packaging material or prefabricated blanks. Thus, packaging containers can be produced by reforming a web of laminated packaging material into a tube with both longitudinal edges of the web being integrated with each other at overlap seams by welding together the innermost and outermost heat-sealable thermoplastic polymer layers. The tube is filled with the intended 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 tube's contents. The packages are separated from the tube by cutting along the transverse seals and given the desired geometric configuration, usually a parallelepiped or cube, by creasing along prepared crease lines in the packaging material.

[0006] The main advantage of this continuous tube forming, filling and sealing packaging process concept is that the web is continuously sterilized just before tube formation, thereby offering the possibility of an aseptic packaging process, i.e. a process in which the liquid contents to be filled as well as the packaging material itself are reduced in bacteria 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 risking microbial growth in the filled product. Another important advantage of the Tetra Brik® type packaging process is the possibility of continuous high speed packaging, which, as mentioned above, has a considerable impact on cost efficiency.

[0007] Packaging containers for sensitive liquid foods, such as milk or fruit juice, can also be produced from sheet blanks or prefabricated blanks of the laminate packaging material of the invention. From tubular blanks of the flat-folded packaging laminate, the packages are first produced by assembling the blanks to form an open tubular container capsule, one open end of which is closed by folding and heat sealing of the integral width face. The container capsule thus closed is then filled with the target food, for example fruit juice, through the open end, which is closed by further folding and heat sealing of the corresponding integral width face. An example of a packaging container produced from sheet and tubular blanks is the conventional so-called gable top package. There are also packages of this type with a moulded top and / or a screw cap made of plastic.

[0008] The aluminum foil layer in the packaging laminate provides gas barrier properties that are significantly superior to most polymeric gas barrier materials. Traditional aluminum foil-based packaging laminates for aseptic packaging of liquid foods remain the most cost-effective packaging materials at their performance levels available on the market today.

[0009] Other materials that compete with such foil-based materials must be cost-effective in terms of raw materials, have comparable food preservation properties, be sufficiently mechanically stable, and be relatively low complexity when converted into a final packaging laminate.

[0010] Further reducing the cost of today's packaging materials may be done by down-gauging the thickness of the polymer layer or by replacing the aluminum foil barrier layer with one or more different barrier layers, which has proven to be extremely difficult. A further method of cost saving, which has not been considered practical in the field of liquid carton packaging, is by down-gauging the cellulose-based bulk layer by the type and / or amount of cellulose fiber material. This method usually results in the loss of important properties of mechanical strength and package integrity, as well as material barrier properties, and was previously considered to be a less advantageous method going forward. Paperboard is the major part of liquid carton packaging materials, but also represents a major part of the total packaging material cost.

[0011] A further need for future laminate packaging materials for liquid packaging containers is that the appearance of such packaging containers should be able to be differentiated to a higher degree, i.e., by providing new, interesting, appealing decorative or tactile features to attract consumers and retailers. Such features are, for example, printed decorative patterns such as gold metallization or other different glossy colors, embossed and engraved features such as holographic decoration, texture or embossed surface effects, background effects for matte / glossy surfaces, etc. The demand for such differentiation options is increasing, but is a challenge to meet, since adding features and materials usually automatically increases the cost of raw materials and / or manufacturing processes. Moreover, such special materials with shiny or glossy features or embossed features are often sensitive materials and cannot withstand high lamination pressures and temperatures. [Prior art documents] [Non-patent literature]

[0012] [Non-Patent Document 1] SCAN(Scandinavian Pulp and Paper Norms)P21-67 [Non-Patent Document 2] TAPPI UM535 (ISO 8791-2) Summary of the Invention [Problem to be solved by the invention]

[0013] In view of the above, it is therefore an object of the present invention to provide a new method for reducing the cost of laminated cellulose-based liquid or semi-liquid food packaging materials.

[0014] It is also a general object of the present invention to provide a cost-effective method of laminating cellulose-based packaging materials that provides sufficient mechanical stability as well as good barrier and integrity properties, which addresses the needs in carton laminate packaging materials for liquids.

[0015] It is a further object of the present invention to provide a method for producing low-cost laminate packaging materials based on biological and renewable materials, i.e., with an increased relative content of materials from sources that do not utilize fossil raw materials.

[0016] A still further object is to provide a method of laminating a sensitive material layer to a cellulose-based bulk material layer or paper substrate, such as a substrate layer having prefabricated sensitive decorative features, without damaging the sensitive material or delicate barrier coatings thereon.

[0017] A further object is to allow cost-effective differentiation of the outer layer of the laminated packaging material on the outside of the packaging container, i.e. the layer that attracts and appeals to the consumer. Such outer layer can be easily replaced by the method of the present invention, whereby different decorative and / or tactile features can be laminated into the material according to different desires among dairy and filler customers, consumers and retailers. Such customization allows for the production of a shorter series of differently decorated and tailored packaging materials without causing stoppages, waste and logistical problems in the main material production line.

[0018] Finally, an additional object is to provide a method of laminating such materials that saves energy and waste, especially when changing between different outer and inner materials ("differentiation").

[0019] Thus, some or all of these objectives can be achieved according to the present invention by a method for producing a laminated packaging material, the packaging material obtainable by this method, and also the packaging containers made therefrom, as described in the accompanying claims. [Means for solving the problem]

[0020] The term "long term storage" in the context of the present invention means that the packaging container should be able to preserve the quality, i.e. nutritional value, hygienic safety and taste, of the packed food under ambient conditions for at least 1 or 2 months, such as at least 3 months, preferably longer, such as 6 months, such as 12 months or more.

[0021] The term "package integrity" generally refers to package durability, i.e., resistance to leakage or breakage of the package. A major contributing factor to this property is the provision of good internal adhesion between adjacent layers of laminate packaging material in the packaging laminate. Another contributing factor is the resistance of the material to defects such as pinholes, punctures, and the like in the material layers, and yet another contributing factor is the strength of the closure seam that seals the material when it is formed into a package. Thus, with respect to the laminate packaging material itself, the integrity property is directed solely to the adhesion of each laminate layer to the adjacent layers, as well as the quality of the individual material layers.

[0022] The term "liquid or semi-liquid food" generally refers to food with a liquid content that may optionally include food particles. Dairy and milk, soy, rice, grain, and seed drinks, fruit juices, nectars, still drinks, energy drinks, sports drinks, coffee or tea drinks, coconut water, tea drinks, wine, soup, jalapeno, tomato, sauces (such as pasta sauce), soybean oil, and olive oil are some non-limiting examples of foods that are contemplated.

[0023] The term "sterile" in relation to packaging materials and containers refers to a condition in which microorganisms have been eliminated, inactivated, or killed. Examples of microorganisms are bacteria and spores. Generally, an aseptic process is used when a product is aseptically packed into a packaging container.

[0024] The term "heat sealing" refers to the process of welding one surface of a thermoplastic material to another surface of a thermoplastic material. A heat sealable material should be one that, under appropriate conditions, such as application of sufficient heat and pressure, is capable of forming a seal when pressed into contact with another suitable thermoplastic material. Suitable heating may be accomplished by induction or ultrasonic heating or other conventional contact or convection heating means, such as hot air.

[0025] The term "bulk" layer usually means the thickest layer or the layer that contains the most material in a multi-layer laminate, i.e. the layer that is responsible for the most mechanical properties and dimensional stability of the laminate and the package folded from the laminate. In the context of the present invention, this can also mean that the layer provides a greater thickness distance in a sandwich structure that further interacts with a stabilizing facing layer, which has a higher Young's modulus, on each side of the bulk layer to achieve sufficient such mechanical properties and dimensional stability.

[0026] A "spacer layer" is a layer that forms a distance or space between significantly thinner layers of material with higher Young's modulus and density, such as high tensile stiffness paper layers, films or metal foils, i.e. layers that provide stiffness and stability, so-called facing layers, arranged on at least one side of the spacer layer. The spacer layer has a low or reduced inherent bending stiffness and therefore does not directly contribute significantly to the bending stiffness of the laminated packaging material itself. Indirectly, however, it can be very strongly involved by interaction with adjacent or laminated layers on both sides, some of which have a higher Young's modulus but are thin compared to the spacer layer. In a sandwich structure, it is important that there is at least one such facing layer or a stiffening layer on each side of the spacer layer. One facing layer on each side of the spacer layer is necessary when the spacer layer has a very low density and is not involved by its own bending stiffness properties. When the distance between the paper facing layers is increased, the bending strength and bending stiffness of the laminated sandwich structure also increases.

[0027] A "bulk layer" may include a "spacer layer" and further combined or integrated layers within the bulk, but may be the same as a "spacer layer."

[0028] According to a first aspect of the present invention, there is provided a method for the manufacture of a laminate packaging material for carton packaging for liquid foods, the method comprising the steps of providing a first web comprising a layer A of paper or paperboard or other cellulose-based material, providing a second web comprising a film or sheet B, the first web comprising a layer A of paper or paperboard or other cellulose-based material A, the second web comprising a layer B of paper or paperboard or other cellulose-based material B ... 2 and feeding the first and second webs, one of which has the aqueous adhesive composition applied thereto, towards a pressure roller nip so that they are bonded and laminated by the intervening aqueous adhesive composition while passing through the nip and while the adhesive composition is partially absorbed into at least one of the first and second web surfaces of A and B.

[0029] In a preferred embodiment, there is no forced drying or curing or crosslinking of the applied adhesive composition, and lamination occurs at ambient temperature. Even if the adhesive composition contains a very large amount of water, in order to spread the adhesive binder polymer fully and evenly over the entire surface of the substrate to be coated, drying is not necessary because the at least one cellulose-based layer surface to be laminated absorbs water without the cellulose material being significantly affected by the water, to the extent that drying is not necessary. This was surprising in itself, since curling problems and blistering effects in the subsequent hot lamination operation were expected from the absorbed moisture, but no such effects were observed. Even more surprising, the adhesion level was high enough for the standards required in carton packaging materials for liquids, and remained strong during storage and sale. The applied adhesive was found to be stable at 1 to 3 g / m2. 2 Despite these very low amounts, adhesion has exceeded 100 N / m in all test runs so far and is expected in any case to be well above the required minimum of around 60 N / m.

[0030] One of the major advantages of the method of the present invention is that no expensive heat or forced drying equipment is required, nor is irradiation equipment or irradiation adaptation of the materials required.

[0031] The adhesive composition may comprise an adhesive binder polymer selected from the group consisting of polyvinyl alcohol (PVOH), polysaccharides and polysaccharide derivatives such as starch and cellulose and its derivatives, polyvinyl acetate, and acrylic modified polyolefin adhesive polymers.

[0032] Although other adhesive compositions may serve to adhere to cellulose-based and other layers, the above adhesive binder polymers are preferred because they are water-soluble / dispersible, can be derived from renewable sources or biodegradable materials, and are safe for use in connection with packaging of food-grade products.

[0033] The second web of film or sheet B may have a surface roughness of 200 Bendtsen or less, such as 100 Bendtsen or less, such as 150 Bendtsen or less, as defined in Non-Patent Documents 1 and 2, and the aqueous adhesive composition may be applied onto the second web.

[0034] When one of the surfaces to be laminated has a smooth, low absorbency surface, it is advantageous to first apply the adhesive composition to that surface to form a flat, uniform adhesive wet applied film at the time of the lamination operation when pressure is applied to the layers to be laminated. This ensures an optimal number of adhesion points to rougher or porous (fibrous) cellulose-based surfaces, or to paperboard surfaces.

[0035] When Layer B has a low surface roughness value, the adhesive binder polymer may be an acrylic modified polyolefin adhesive, such as an ethylene-(meth)acrylic acid copolymer dispersion in water, having a solids content of 30 to 50% by weight.

[0036] When the concentration of the aqueous adhesive polymer composition is low and / or the amount coated on the lamination surface is small, it may be advantageous to heat or post-heat the laminate material by one additional warm or hot roller nip, alternatively a heated lamination roller nip. By such heating, the adhesive polymer is suspended and melt-fused between the cellulose fibers on the cellulose-based web surface, and upon cooling, a kind of heat seal is obtained between the laminated surfaces, which therefore spreads over the interface of the adhesive web surfaces.

[0037] Suitably or preferably, the amount of adhesive binder polymer applied is, in terms of dry content, 2 g / m 2 Less than 0.5 to 1.8 g / m 2 etc., 1 to 1.5 g / m 2 etc., 3g / m 2 For acrylic modified adhesives, the dry content is 0.5 to 1.8 g / m2 when one of the surfaces to be laminated has the above low surface roughness. 2 and very small amounts are almost always sufficient in practice, and in many cases, dry contents of 1 to 1.5 g / m 2 It has been shown that it is possible to remain

[0038] The web of layer B may be paper or paperboard or other cellulose-based layer, whereby the adhesive binder polymer is selected from PVOH, polyvinyl acetate, starch or starch derivatives, and cellulose and cellulose derivatives.

[0039] In this case, the adhesive binder polymer typically has a dry content of 2 to 3 g / m 2 and 1 to 3 g / m2 depending on the absorptive capacity of the cellulose-based surface of each of the first and second webs. 2 etc., 0.5 to 4 g / m 2 may be applied in an amount of

[0040] The most reliable bonding results may be obtained when the thickest, bulkiest cellulose-based layer, usually layer A, has a moisture content of 5 to 10% RH, such as 5.5 to 7.5% RH. This moisture level ensures rapid and uniform absorption into the cellulose fiber network at the surface of layer A, and / or layers A and B, without adversely affecting the properties of the cellulose-based layer or web or any of the cellulose-based layers or webs.

[0041] Layer A may have a surface roughness of 300 Bendtsen or more, such as 500 Bendtsen or more, such as 400 Bendtsen or more, as defined in Non-Patent Documents 1 and 2. Such a surface roughness is usually accompanied by sufficient absorption properties within the surface of the cellulose-based layer.

[0042] Through the lamination roller nip, the web speed enabled by the methods described above may be at least 200 m / min, such as 300 m / min or more, such as 400 m / min or more, such as 500 m / min or more.

[0043] In particular, the adhesion between the two laminate layers A and B is at least 60 N / m, such as at least 100 N / m.

[0044] In one embodiment of the method, film or sheet B is laminated to the outside of layer A, i.e., to the outside of a packaging container made from the packaging material, and comprises a printed substrate, or a pre-laminated structure comprising a printed substrate with a printed decorative pattern and an outer transparent protective polymer layer.

[0045] In another embodiment of the method, film or sheet B is laminated to the inside of layer A, i.e., to the inside of a packaging container made from the packaging material, and comprises a pre-laminate structure comprising at least one barrier layer or barrier coating, or a barrier layer or barrier coating and an innermost heat-sealable liquid-tight thermoplastic polymer.

[0046] In one particular embodiment, a film or sheet B comprises a metallized polymer film to be laminated to the outside of layer A, i.e. to be on the outside of a packaging container made from the packaging material, and to be a printing substrate for further decorative printing patterns by flexographic printing, offset printing, or any of the other modern printing techniques. Thus, what is provided is a first web comprising a layer A of paper or paperboard or other cellulose-based material and a second web B of metallized polymer film intended for the outside of the packaging material, such as an oriented polypropylene (OPP, BOPP) or oriented PET film, in which an aqueous composition comprising an adhesive is applied onto the metallized surface of the metallized film during delivery. The two webs are delivered towards a pressure roller nip, the second web having an aqueous adhesive applied to its surface, and during the passage through the nip, they are joined and laminated by the intervening aqueous adhesive composition, the adhesive composition being partially absorbed into the first web A. No forced drying or heat curing of the aqueous adhesive composition is necessary and the lamination speed can be kept as high as normal lamination speeds of more than 300 m / min, or more than 400 m / min, or even more than 500 m / min. In particular, in this embodiment, the web of layer A can be a conventional clay-coated paperboard of the type suitable for carton packaging for liquids. The clay-coated surface partially absorbs the aqueous adhesive composition, as well as the cellulose fiber network without such a coating. The metallized surface of film web B has a high smoothness to provide a uniform wet coating with a thin film application of the liquid adhesive, ensuring a controlled and uniform (over the entire surface) absorption of the adhesive composition onto the opposing surface to be bonded in the pressure nip, i.e. the clay-coated paperboard of web A. The adhesive binder polymer is an ethylene acrylic acid copolymer dispersion in water, with a solids content of 40 to 50% by weight and a dry content of about 2 g / m 2 A quantity of 100 mg / g is applied.

[0047] The laminated paperboard and the outer metallized film are then wound on a reel and mass-produced for intermediate storage on the reel. When it is time to produce a laminated packaging material with the metallized film as the printing substrate, the paperboard-metallized film laminate is unwound from the reel and led to a printing station for conventional printing of a decorative pattern on the film side, where a metallized shiny decorative background is obtained. The printed material is then further laminated to the outermost and innermost heat-sealable liquid-tight protective thermoplastic polymer layers by extrusion coating or film lamination in the usual manner. The outermost heat-sealable liquid-tight protective thermoplastic polymer layer can alternatively be applied using an aqueous dispersion coating of a thermoplastic polymer when only a thin thickness of such an outermost layer is desired or when such a process is preferred for other reasons. This also includes lamination to a barrier material layer, such as aluminum foil, on the inside of the bulk paperboard layer, between the paperboard and the innermost thermoplastic layer, i.e., on the side of the paperboard layer facing the printed decorated outside. Alternatively, the first aqueous adhesive absorption lamination step of the paperboard to the metallized film is connected as an in-line operation to the subsequent printing and creasing operation without intermediate winding on a storage reel. This choice depends on the setup of the lamination line as well as the size of the incoming orders for different decorative patterns and different printed substrates, and is determined in view of the most economical way of working. The first lamination step is quick and easy to perform, and is easy and flexible enough to be connected to an in-line operation, since it requires only one lamination station.

[0048] The resulting adhesion between the outer metallized film and the paperboard exceeds 100 N / m and has been proven to be strong enough throughout the entire lamination production, intermediate reel storage of the laminate material, further printing and lamination steps, and even throughout the entire production of the folded, filled and sealed packaging containers for liquid foods from the laminate material. The advantages therefrom are significant and greatly simplify the packaging laminate production process. Up to now, the lamination of metallized films to paperboard has been achieved using approximately 10-15 g / m2 of low density polyethylene (LDPE). 2 Previously, the metallized film had to be laminated by melt extrusion lamination with an intervening layer of LDPE, which, of course, is rather expensive in terms of raw material costs. Furthermore, the metallized film, which is thin and delicate to handle during lamination, is exposed to significant heat loads from the hot melt extruded LDPE at about 280-320°C while the film web moves under tension into the chilled pressure roller nip. Defects caused by such rough handling can be avoided by methods such as those described above. The subsequent heat lamination step is performed when the film is already adhered and set to the paperboard, and is therefore not as vulnerable to similar heat loads as later in the manufacturing process.

[0049] According to a second aspect of the present invention, there is provided a laminated packaging material produced by the method of the present invention, as a result of which the packaging material laminated in one or two steps by the method of the present invention contains a significantly lower amount of thermoplastic adhesive polymer compared to current conventional packaging materials for liquids, i.e. laminated by melt extrusion lamination, and therefore contains a high relative content of cellulose fibers and renewable materials, which is advantageous from the point of view of environmental and climate protection.

[0050] According to a third aspect of the present invention, there is provided a packaging container manufactured from the laminated packaging material of the method of the present invention. It is therefore concluded that the packaging container, also when made by the lamination method of the present invention, has good package integrity and can be easily adapted to customer and market requirements in terms of decorative features, as well as using sensitive raw materials and pre-manufactured or pre-laminated semi-materials.

[0051] In yet a further embodiment, the method of the invention comprises: a) Density is 850 kg / m 3 Less than 60 to 250 g / m 2 providing a web of central modular bulk material with a cellulose spacer layer having little or no inherent bending stiffness, b) providing a web of outer material modules comprising at least one printed substrate layer with or without a decoration printed or applied thereto, the outer material modules intended for that side of the bulk material that should be directed towards the outside of the packaging container made from the laminated packaging material; c) laminating the outer side of the web of bulk material and the web of the outer material module together; d) adding decoration to the outer material module; e) providing a web of inner material modules comprising at least a barrier layer, the inner material modules being intended for that side of the bulk material that should be directed towards the inside of a packaging container made from the laminate packaging material; f) laminating the inner side of the web of inner material module and the web of bulk material to each other; g) applying an outermost transparent liquid-tight protective layer to the outside of the outer material module; h) applying an outermost thermoplastic liquid-tight heat-sealable layer to the inside of the inner material module; i) thereby obtaining a web of laminated cellulose-based liquid or viscous food packaging material and further winding it onto a reel; It may include The spacer layer forms the center of a sandwich structure within the laminate packaging material, the sandwich structure having a barrier layer arranged with a paper or polymer-based facing layer on the inside of the spacer layer and interacting with further facing layers arranged on the outside of the spacer layer, at least one of the facing layers being a paper facing layer, both facing layers having a significantly smaller thickness and a higher Young's modulus than the spacer layer.

[0052] These method steps may be performed in any order, but the order listed above is considered to be preferred from the standpoint of lamination set-up. Alternatively, the inner and outer material modules may be prefabricated, i.e., prelaminated, so that the low-density, relatively sensitive central module with the bulk layer, including or consisting of the spacer layer, only needs to withstand two lamination operations. Since the low-density spacer layer may be more sensitive to pressure and stress, it may be advantageous to handle it as little as possible until the final packaging laminate. In certain embodiments, the outer paper facing layer should be laminated to the bulk layer first, so that it is pre-cut together with making the pre-cut holes, openings, or slits in the thicker bulky parts of the material, as is done today with conventional bulk paperboard. Such pre-cut holes or openings or slits are then encapsulated between other laminate layers which are laminated in subsequent operations, including the inner layer and inner barrier layer, as well as the outermost polymer layer, which together form the polymer laminate membrane and barrier material layer.

[0053] Such packaging laminates with a paper facing layer inside the bulk layer are particularly advantageous in that improved opening and closing of the laminate membrane of the layer in the pre-cut hole area may be obtained when the laminate has pre-cut holes in the bulk and outer paper facing layers. The opening device usually has a cutting or slitting feature such that the membrane across the pre-cut hole is cut or torn open when twisting / turning the cap or screw cork of the opening device is performed. If the cutting or slitting resistance in the laminate membrane is too high, the package to which the opening device is attached will be difficult to open when very strong polymeric films or layers are used as material layers in the membrane. Also, if the adhesion between the layers of the laminate membrane is low, delamination and edge tearing of the material will occur, resulting in a less attractive appearance after opening. When a paper facing layer is used as the main inner barrier substrate layer, the laminate membrane is mechanically stable and has high laminate quality, i.e., no breaks or delamination occurs between the layers before or after opening.

[0054] Thus, the laminate packaging material obtained by the method of the present invention may be a three-module sandwich material comprising a mechanically stabilizing facing layer of a cellulose-based spacer layer and an oriented film or high density paper layer on the outer side of the spacer layer, the laminate further comprising a barrier paper or film on the inner side having at least some oxygen barrier properties, and a heat-sealable layer, and a tie or adhesive layer.

[0055] Thus, the spacer layer may be a layer that forms a distance or space between significantly thinner layers of material with higher Young's modulus and density, such as high density paper layers arranged on each side of the spacer layer, i.e. layers that provide stiffness and stability, so-called facing layers. Further layers may be arranged on each side of the spacer layer, which participate in the entire sandwich structure, but the main effect was seen in the paper facing layers. The spacer layer has a low or reduced inherent bending stiffness and therefore does not directly participate in the bending stiffness or strength of the laminated packaging material. However, indirectly, this may be very strongly involved by interaction with adjacent or laminated layers on both sides, some of which have a higher Young's modulus but are thin in thickness compared to the spacer layer. In a sandwich structure, it is important that there is at least one such facing layer or a stiffening layer on each side of the spacer layer. One paper facing layer is necessary on each side of the spacer layer, as the spacer layer has a very low density and is not involved by its own bending stiffness properties. As the distance between the paper facing layers increases, the mechanical strength and bending stiffness of the laminate sandwich structure also increases.

[0056] A suitable cellulose-based material for the spacer layer may for example be so-called foamed cellulose, i.e. foam-forming fibrous cellulose, which is a fibrous material with adjustable density that can be produced by a foam-forming process.

[0057] Thus, the bulk layer comprising the cellulose foam is 700 kg / m 3 Less than 100 to 600 kg / m 3 etc., 100 to 500 kg / m 3 etc., 200 to 500 kg / m 3 etc., 200 to 400 kg / m 3 etc., 300 to 500 kg / m 3 etc., 300 to 400 kg / m 3 etc., 750kg / m 3The lower the density of the foamed cellulose layer, the more cost-effective it is in terms of raw materials consumed, while the resistance to thickness reduction properties of the foamed cellulose is less than 300 kg / m 3 According to one embodiment, the optimum density of the expanded cellulose to be used in the laminate packaging material is between 300 and 500 kg / m 3 , especially 300 to 400 kg / m 3 It was concluded that.

[0058] Bulk layers comprising foamed cellulose as described in aspects and embodiments herein further provide desirable strength against delamination, i.e., they do not easily delaminate under standard conditions. The delamination strength is measured, for example, in J / m according to TAPPI T569. 2 The internal bonding energy of the packaging material herein may be determined by a Huygen Internal Bonding Energy tester, which gives a value of 60 to 250 J / m 2 etc., 80~200J / m 2 etc., 140~200J / m 2 60~300J / m 2 In some aspects and embodiments, the bulk layer provides a distance between the barrier layer and the outermost thermoplastic decorative layer, thereby enabling a tailored laminate packaging construction. In some embodiments, the bulk layer comprising foamed cellulose provides interlayer peel strength in combination with compressive strength in the thickness direction (ZD) to provide sufficient distance between the barrier layer and the decorative layer.

[0059] The foamed cellulose can be produced by mixing cellulose fibers with a foaming fluid, such as water and optionally a surfactant, such as sodium dodecyl sulfate (SDS). The amount of surfactant should be 0.1 w% to 20 w%, such as 0.5 w% to 10 w%, such as 1 w% to 5 w%, such as 1.5 w% to 3 w%. A rotor mixer on a typical foam generator produces the foamed cellulose. The foam is typically formed by introducing a gas into the mixture. Air is one example of a suitable gas. Another suitable gas is oxygen. Typically, the gas is forced into the mixture by a vortex caused by compressed gas and agitation. Typically, the cellulose is provided as a liquid dispersion that includes the cellulose fibers. One example of a liquid is water. Some examples of cellulose fibers are cellulose-based fibers, such as chemical pulp fibers, chemi-thermomechanical pulp fibers, thermomechanical pulp fibers, and kraft pulp fibers. The fiber dispersion may be added to the foaming fluid, for example, after the foam is generated by the fluid (including the surfactant). Optionally, the liquid dispersion containing cellulose fibers may be combined with a foamable fluid before foaming. Additives for controlling the firmness of the foam may be added if necessary. The foamed cellulose produced as described herein is passed through a nozzle arrangement ("headbox"), where it is subjected to pressure and forming equipment to produce a web of foamed cellulose that is at least partially dried and then wound on a reel and stored for future use, for example, to prepare packaging materials. Optionally, the foamed cellulose web can be used in-line, i.e., the foamed cellulose web can be converted into a laminate packaging material to directly apply additional layers for liquid or semi-liquid food packaging. Compared to conventional papermaking, additional or modified drying can be used appropriately to obtain the desired dryness and density.

[0060] In some embodiments, the foamed cellulose may be mixed with other materials, such as additives such as starch and its derivatives, mannogalactan, carboxymethylcellulose, melamine formaldehyde colloid, urea formaldehyde resin, polyamide polyamine epichlorohydrin resin, and / or microfibrous cellulose, and / or refined pulp, and / or reinforcing chemicals or agents.

[0061] Another example of a spacer layer is made from so-called corrugated board material, which usually has a very high density but a low inherent bending stiffness as well as other differences in mechanical properties, i.e. poor mechanical properties compared to conventional liquid packaging paperboard, so that the dimensional and mechanical stability, and therefore the integrity and barrier properties, of packages made from laminates with bulk layers of such materials are compromised when made by conventional manufacturing of packaging laminates.

[0062] In particular, it has a substantially lower bending stiffness per se compared to laminate packaging materials suitable for liquid packaging. Although bending stiffness is not generally measured on the baseboard material since it was intended for corrugated carton production anyway, such materials have been measured to have a bending stiffness at least 30%, such as at least 40%, such as at least 50%, lower than that of liquid carton paperboard of the Triplex or Duplex type at the corresponding basis weight when excluding the printable coating (clay coat) basis weight. In general, fluting materials have a higher bending stiffness per basis weight than linerboard materials.

[0063] However, this still relates to the overall bending stiffness of the laminate packaging material by providing distance layers in a sandwich structure between the facing layers, which have a high Young's modulus, and by providing higher compressive strength properties in the plane of the layers (xy) compared to conventional paperboard for liquid packaging.

[0064] Corrugated linerboard is also known as corrugated case material (CCM) and the material required for corrugated linerboard is corrugated medium (or corrugated media) which is fluted (welded) in use by bonding adhesive between two flat liners or liner media and then arranged. Such a corrugated construction provides high sandwich bending stiffness due to the corrugated middle layer acting as a distance or spacer layer between the two relatively thin liner layers. Thus, the two types of papers that make up corrugated linerboard are liner material, also commonly called kraft liner or test liner, and fluted (or corrugated medium) material.

[0065] The two types of paper that make up linerboard are liner material, and fluting (or corrugating medium) material. Linerboard is made exclusively from natural unbleached cellulose fibres, so it is generally brown or beige in colour, although its colour intensity can vary depending on the type of cellulose. 835 kg / m 3 It is lower than 100%, brown or beige in color, and contains primarily softwood fibers, such as spruce and pine fibers.

[0066] Therefore, the fluting is 600 to 700 kg / m 3 , usually about 650 kg / m 3 etc., 600 to 750 kg / m 3 Fluting paper is a paper product used as a corrugating medium in corrugated container board, having a density of 10 ...

[0067] However, the fluting material forms a non-corrugated spacer layer by being a fibrous material with low stiffness and low cost that can provide sufficient distance in the sandwich structure for the laminated liquid carton packaging material. Corrugated spacer layers, i.e. shapely spacer layers, are not within the scope of the present invention. Corrugated carton materials bring very different technical meanings and requirements to the liquid carton laminate packaging material and are not addressed here.

[0068] Fibers commonly used in the manufacture of containerboard materials can be broadly classified into two main types: recycled fibers and new, i.e., virgin fibers. The properties of the paper depend on the structural properties of the various fibers that make up the sheet. Generally speaking, the higher the virgin fiber content, the stronger and stiffer (higher compression resistance) the fluting or liner material will be. The fluting material investigated for the purposes of this invention is semi-chemical fluting made from 100% virgin fibers from Powerflute, made from hardwoods such as birch. Birch is the optimal fluting raw material. Its structure contains high concentrations of lignin and hemicellulose. The pulping process preserves the naturally highly hydrophobic lignin and modifies the remaining hemicellulose so that the soft, flexible cellulose core of the fiber is protected. This results in higher stiffness and creep properties. When used for liquid packaging, fluting materials available on the market need to be supplemented with one or more additional sizing agents during cellulosic web manufacture to handle the liquid and high moisture conditions for this new use and application. Conventional sizing techniques and chemicals (AKD, ASA, rosin, etc.) can be used on the fluting material to meet the necessary requirements for a particular product.

[0069] Liners made from virgin fibers are called kraft liners, while liners from recycled fibers are called test liners. A mix of virgin and recycled fibers is also possible. Kraft liners should have at least 80 wt.%, and preferably 100 wt.%, virgin fibers. The fibers used in liners are longer than those used in fluting materials, and because liners are originally intended for the liner layer of the outer carton material, they are also sized with a sizing agent to withstand different degrees of moisture and wet conditions.

[0070] Thus, the linerboard material has a lower bending stiffness than the corresponding paperboard for liquid packaging, but on the other hand has a higher SCT index, i.e. a higher SCT value per basis weight in the machine direction (MD), than normal liquid board materials, or other paper or cellulose materials suitable in this context. The SCT value is measured according to the international standard ISO 9895 and is the property on which different linerboard materials are relied upon to compare with each other. The SCT or short compression test measures the internal compression resistance of the paper fibres, i.e. the in-plane compressive strength of the paper, in the CD and MD. This property varies with the basis weight of the particular paper being measured. The basis weight of the paper product is measured according to ISO 536.

[0071] Packages made from materials with a higher SCT index have better stackability, and thus this is a measure of the compressive strength per basis weight in the plane (xy plane) of the carton material. Baseboard paper usually has an SCT index in MD greater than 30 Nm / g, which provides the necessary compressive strength and stacking properties, among others, for liquid carton laminates. These materials do not need to be optimized with respect to stiffness properties, since they are used only as (non-corrugated) spacer layers in laminate materials for liquid carton packaging. Thus, although such liner materials are originally intended for facing layers in corrugated carton sandwich structures, for the purposes of the present invention they are used as spacer layers in laminate structures, which have further facing layers laminated on each side and provide the necessary stiffness properties for liquid carton laminate materials.

[0072] For comparison, today's liquid board materials have an SCT index of about 25 Nm / g, but are then also optimized for all other properties because they are relied upon as the primary contributor to dimensional stability in liquid carton laminate packaging materials. When today's optimized liquid board is replaced in the sandwich structure in the laminate with a low-cost spacer layer, such spacer layer needs to have a higher SCT index, above 30 Nm / g, to compensate for the loss of properties when the state-of-the-art board is removed.

[0073] Because the new spacer layer is laminated to an additional facing layer in a sandwich configuration in the laminate structure, there is no need to provide a white or smooth (e.g., clay coated) print surface on the spacer layer itself, and in that regard, linerboard material is therefore a suitable material for such a spacer layer.

[0074] In terms of moisture resistance, the baseboard material is rated at 35 g / m2 to function better within the liquid carton packaging laminate. 2The Cobb Water Sorption Value may be less than 0.01 mm. The Cobb Value is measured according to ISO 535 and is already met by most liner materials, however some fluted materials may require additional sizing to be used as non-corrugated spacer layers in liquid carton packaging laminates. Therefore, the linerboard material in the bulk layer includes at least one sizing additive.

[0075] In further embodiments, the spacer layer may comprise a combination of different cellulose or paper types. If the spacer layer comprises foamed cellulose, the foamed cellulose portion is at least 20%, such as at least 25%, such as at least 30%, such as at least 40%, of the thickness of the bulk layer. These percentages may be determined by examining a cross-section of the packaging material under a microscope.

[0076] It was found that when downgauging from conventional liquid board to such alternative cellulosic materials for the bulk layer, the aluminum foil barrier laminated to the inside of the bulk layer could develop small cracks and was no longer airtight to gas transmission. It was therefore found necessary to spend more on the barrier material to make up for the loss of oxygen barrier when saving on the cost of the board material. Of course, there was also the alternative idea of ​​replacing the aluminum foil with a different, better barrier anyway, but this has, to date, been seen as a costly wish and / or a costly juxtaposition of several different barrier layers that are rather thick and laminated together to provide the necessary barrier properties.

[0077] In another embodiment, the bulk layer comprises primarily a layer of spacer material, but may additionally include one or more integrated paper layers having a relatively high Young's modulus but a thin thickness compared to the spacer layer, which provide some mechanical strength and bending stiffness to the final laminate material produced.

[0078] According to one embodiment, the final laminate material includes at least one such relatively thin, stiff paper arranged on each side of the spacer layer, where the thinner paper with a higher Young's modulus acts like a flange in an I-beam structure or like a facing layer in a sandwich structure, thereby mechanically stabilizing the sandwich, e.g., in terms of bending stiffness and compressive strength in various directions within the material.

[0079] Suitable such stabilizing paper facing layers may be found in thin kraft, greaseproof, or parchment papers. These may range from 30 to 70 g / m 2 etc., 30 to 60 g / m 2 etc., 20 to 100 g / m 2 Gravity: 600 to 1500 kg / m 3 The density should be 0.01 to 0.01.

[0080] Typically, the paper facing layer should have a Young's modulus of from 1 to 10 GPa, such as from 5 to 10 GPa.

[0081] The paper facing layer can be included in the laminate material structure in different ways. For example, the bulk material layer can comprise the fluting material layer and such a thin, denser paper facing layer on one side of the spacer layer when the spacer layer has a higher density and inherent stiffness by itself, such as a fluting material spacer layer. It may then be sufficient for the final laminate material to just have a compact surface barrier paper on the inside and a less stable facing layer of a different material, such as an oriented plastic film, on the outside of the spacer layer. Alternatively, the paper facing layer can also be included in the outer material module to be laminated to the fluting material layer.

[0082] The bending stiffness of the packaging material laminate can be derived from the thickness and Young's modulus of the individual layers. To balance the mechanical properties of the sandwich laminate material structure, the sandwich facing layers should be arranged on each respective side of the spacer layer so that they have substantially equal tensile stiffness. The tensile stiffness is given by the product of Young's modulus and thickness. This may be adjusted by varying the thickness and Young's modulus of the paper, and when there are multiple such paper facing layers on one side of the spacer layer, there is a formula to calculate the total bending stiffness of a particular combination of facing layers.

[0083] In one embodiment where the bulk layer comprises expanded cellulose, the final laminate material comprises one paper facing layer arranged on each side of the spacer layer to provide sufficient stability to the final laminate package.

[0084] Thus, in one embodiment, the bulk material comprises a spacer layer and a barrier coated paper as a facing layer on the first side (inner) of the spacer layer, while the outer material module also comprises a paper facing layer, which is a print substrate, to be laminated to the second side (outer) of the bulk and spacer layer. In another embodiment, the bulk material layer comprises a spacer layer and an integrated paper facing layer on the second side of the spacer layer, while the inner material module comprises a barrier paper facing layer, which is thus laminated to the first side of the bulk and spacer layer.

[0085] In a further embodiment, the bulk material comprises a spacer layer and one integral paper facing layer on each side of the spacer layer.

[0086] In one particular embodiment, the spacer layer is a fibrous layer made by a foam forming process and has a thickness of 150 g / m 2 and a thickness of 600 μm, and arranged on each side is a 70 g / m 2 etc., 60 to 80 g / m 2 The paper has a high density of 100 g / m2.

[0087] Suitable printing substrates may be stabilized stretched and pre-manufactured polymer films, which may be polymer films selected from the group consisting of films based on any of the following: oriented or non-oriented polyethylene terephthalate (PET), oriented or non-oriented polyethylene furanoate (PEF), oriented or non-oriented polybutylene terephthalate (PBT), polyethylene naphthanate (PEN), polyamides such as non-oriented or oriented polyamides (PA, OPA, BOPA), ethylene vinyl alcohol copolymers (EVOH), polyolefins such as polypropylene, uniaxially or biaxially oriented polypropylene (PP, OPP, BOPP), polyethylenes such as oriented or non-oriented high density polyethylene (HDPE), linear low density polyethylene (LLDPE), and cycloolefin copolymers (COC), and polyesters such as blends of any of the aforementioned polymers, or multilayer films having a surface layer comprising any of the aforementioned polymers or blends thereof.

[0088] The printing substrate may have a printable surface that is a clay coated white paper surface, or a brown natural paper surface, or a metallized film, or a metallized paper surface.

[0089] Thus, the outer material module contains 1 to 3 g / m of the water-based adhesive composition. 2 etc. 1 to 4 g / m 2 may be applied to one of the surfaces to be bonded together and then laminated to the bulk material layer by pressing.

[0090] The inner material module contains 1 to 3 g / m of water-based adhesive composition. 2 etc. 1 to 4 g / m 2 may be applied to one of the surfaces to be bonded together and then laminated to the bulk material by pressing.

[0091] When laminating the two webs of the inner and outer material modules to the web of the bulk layer, one of the lamination steps may be carried out using melt extrusion lamination with an intervening molten thermoplastic bonding polymer, which is a common method of laminating two webs together. In one embodiment of the present invention, good adhesion between the laminated surfaces results when the surfaces to be laminated together are all paper or cellulose-based surfaces. Some types of surfaces may require an oxidative pretreatment of the surface before adhering to the other surface, or alternatively or in addition, the bonding polymer to be melt extruded may at least partially comprise an adhesive thermoplastic polymer, i.e. a polymer with functional groups that are compatible with various surfaces, usually carboxyl or maleic anhydride groups.

[0092] Suitable adhesive polymers for bonding the barrier film to the inner melt-extruded bonding layer of the laminate material, i.e. between the outer heat-sealable layer and the barrier or primer-coated substrate layer, or to the bulk layer in such a bonding laminate layer of a single layer or multiple layers, are so-called adhesive thermoplastic polymers, such as modified polyolefins based mostly on LDPE or LLDPE copolymers or graft copolymers, e.g. (meth)acrylic acid or maleic anhydride (MAH) monomers (i.e. ethylene acrylic acid copolymers (EAA) or ethylene methacrylic acid copolymers (EMAA)), ethylene glycidyl (meth)acrylate copolymers (EG(M)A) or MAH-grafted polyethylene (MAH-g-PE), with functional groups containing monomeric units, such as carboxyl or glycidyl functional groups. Another example of such modified or adhesive polymers are so-called ionomers or ionomeric polymers. Preferably, the modified polyolefins are ethylene acrylic acid copolymers (EAA) or ethylene methacrylic acid copolymers (EMAA).

[0093] Corresponding modified polypropylene based thermoplastic adhesives or tie layers may also be useful, depending on the requirements of the final packaging container.

[0094] Such adhesive polymer layers or tie layers are typically applied together with the respective outer layer or additional bulk-barrier bonding layer in a coextrusion coating operation.

[0095] Thus, the aqueous adhesive composition may be applied to one of the surfaces to be laminated together and then bonded to the other surface in a lamination station, which involves one or more lamination pressure roller nips.

[0096] Preferably, and generally, there should be only one lamination nip in the lamination station to apply as little pressure as possible to the weaker low density spacer layer. However, to increase adhesion, in some embodiments, a lower nip pressure is applied, but it is possible that several consecutive nips may be advantageous, either by several consecutive roller nips or by one extended nip arrangement.

[0097] The laminate packaging material of the present invention may have a higher content of fibers and materials from renewable resources, which is advantageous from an environmental point of view. Furthermore, by increasing the proportion of cellulose fibers in the material, handling in the recycling process may be easier, especially when the amount of thermoplastic polymer layers and aluminum foil can be reduced proportionately at the same time. This is an advantageous effect, for example, when the lamination of cellulose-based modules can be carried out by using aqueous adhesive absorption lamination, i.e., a lamination method in which a very small amount of polymer adhesive is applied, and bonding the two surfaces to be laminated, and the aqueous medium or solvent is absorbed into the cellulose fiber network of the laminate layer, and no further drying or heating is required. Thus, as in melt extrusion lamination, a less thermoplastic bonding material is required, but the relative proportion of paper or cellulose-based material layers in the packaging material is increased, and further, the barrier layer can be down-gauged due to the efficient combination of the properties of the various material layers contained in the laminate packaging material.

[0098] Suitable thermoplastic polymers for the outermost and innermost heat-sealable liquid-tight layers in the laminate packaging material of the present invention are polyolefins such as polyethylene and polypropylene homo- or copolymers, preferably polyethylene, and 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 a preferred embodiment, the outermost heat-sealable and liquid-tight layer is LDPE, while the innermost heat-sealable and liquid-tight layer is a blend composition of m-LLDPE and LDPE for optimal lamination and heat-sealing properties. The outermost and innermost thermoplastic polymer layers may be applied by (co)extrusion coating the molten polymer to the desired thickness. According to another embodiment, the outermost and / or innermost liquid-tight and heat-sealable layers may be applied in the form of prefabricated oriented or non-oriented films.

[0099] The same thermoplastic polyolefin-based materials, particularly polyethylene, as listed above for the outermost and innermost layers are also suitable within the inner bonding layers of the laminate material, i.e., between a bulk or core layer such as paper or paperboard and a pre-laminate material that includes a barrier film or another film layer.

[0100] A possible additional barrier layer may involve a film or tissue substrate having a barrier coating, such as a dispersion or liquid film coated barrier coating, or a vapor deposited barrier coating.

[0101] Suitable film substrates for such barrier films may be polymer films selected from the group consisting of films based on any of oriented or non-oriented polyethylene terephthalate (PET), oriented or non-oriented polyethylene furanoate (PEF), oriented or non-oriented polybutylene terephthalate (PBT), polyethylene naphthanate (PEN), polyamides such as non-oriented or oriented polyamides (PA, OPA, BOPA), ethylene vinyl alcohol copolymers (EVOH), polyolefins such as polypropylene, polyethylenes such as uniaxially or biaxially oriented polypropylene (PP, OPP, BOPP), oriented or non-oriented high density polyethylene (HDPE), linear low density polyethylene (LLDPE), and cycloolefin copolymers (COC), and polyesters such as blends of any of the aforementioned polymers, or multilayer films having a surface layer comprising any of the aforementioned polymers or blends thereof.

[0102] According to some embodiments, the barrier properties may be provided by a polymer layer or layers, or a film from one or more barrier polymers, while in other embodiments the polymer of the film is only intended to prepare the substrate for a subsequently applied barrier coating.

[0103] The oxygen barrier properties can be provided by a thin liquid film coating, for example a barrier polymer that is coated on a substrate such as a paper or polymeric film substrate in the form of a dispersion or solution in a liquid medium or solvent and then dried to form a thin barrier coating. It is important that the dispersion or solution is homogeneous and stable, resulting in a uniform coating with uniform barrier properties. Examples of suitable polymers for aqueous compositions are polyvinyl alcohol (PVOH), water-dispersible ethylene vinyl alcohol (EVOH) or polysaccharide-based water-dispersible or soluble polymers. Such dispersion coatings or so-called liquid film coating (LFC) layers can be applied in layers up to 1 m. 2It can be very thinned, up to a few tenths of a gram per unit area, and can form a high quality homogeneous layer if the dispersion or solution is homogeneous and stable, i.e., well prepared and mixed. PVOH has excellent oxygen barrier properties under dry conditions, and also provides very good odor barrier properties, i.e., the ability to prevent odorous substances from entering the packaging container from the ambient environment, for example in a refrigerator or storage room, which is important during long-term storage of the package. Furthermore, such liquid film coating polymer layers from water-dispersible or soluble polymers often provide good internal adhesion to adjacent layers, which is related to good integrity of the final packaging container.

[0104] Suitably, such barrier polymers are therefore selected from the group consisting of vinyl alcohol-based polymers such as PVOH or water-dispersible EVOH, polysaccharides such as starch or starch derivatives, cellulose nanofibrils (CNF), nanocrystalline cellulose (NCC), hemicellulose, chitosan or other cellulose derivatives, water-dispersible polyvinylidene chloride (PVDC) or water-dispersible polyesters, or combinations of two or more of these.

[0105] More preferably, the polymeric binder is selected from the group consisting of PVOH, water dispersible EVOH, polysaccharides such as starch or starch derivatives, chitosan or other cellulose derivatives, or a combination of two or more thereof.

[0106] Such barrier polymers are therefore suitably applied using a liquid film coating process, i.e., in the form of a water or solvent-based dispersion or solution which, upon application, is spread into a thin, uniform layer on the substrate and then dried prior to lamination or coating of further layers.

[0107] Aqueous compositions generally have several environmental advantages. Preferably, the liquid gas barrier compositions are water-based, as such compositions also typically have better operating environment considerations than solvent-based systems.

[0108] Most preferably, the gas barrier polymer is PVOH because it has all of the good properties mentioned above, namely, film forming properties, gas barrier properties, cost effectiveness, food compatibility, and odor barrier properties.

[0109] PVOH-based gas barrier compositions perform best when the PVOH has a degree of saponification of at least 98%, preferably at least 99%, although PVOH having a lower degree of saponification will also provide oxygen barrier properties.

[0110] According to a further embodiment, the liquid composition additionally comprises inorganic particles to further improve the oxygen gas barrier properties.

[0111] The polymeric binder material may, for example, be in a lamellar form or mixed with a flaked inorganic compound. Due to the layered arrangement of the flaked shaped inorganic particles, the oxygen gas molecules must travel a tortuous path through the oxygen barrier layer rather than the normal straight path across the barrier layer.

[0112] The inorganic lamellar compounds are dispersed in an exfoliated state, so-called nanoparticle compounds, i.e. the lamellar inorganic compounds are separated from each other by means of a liquid medium. The lamellar compounds may therefore preferably be swollen or cleaved by a polymer dispersion or solution, which permeates the lamellar structure of the inorganic material when dispersed. It may also be swollen by a solvent before being added to the polymer solution or dispersion. The inorganic lamellar compounds are therefore dispersed in an exfoliated state in the liquid gas barrier composition and in the dried barrier layer. There are many chemically suitable nanoclay minerals, the preferred nanoparticles being those of montmorillonite, such as purified montmorillonite or sodium-exchanged montmorillonite (Na-MMT). The nano-sized inorganic lamellar compounds or clay minerals preferably have an aspect ratio of 50 to 5000, and a particle size of up to about 5 μm in the exfoliated state.

[0113] The preferred inorganic particles consist primarily of lamellar bentonite particles having an aspect ratio of 50 to 5000.

[0114] Preferably, the barrier layer comprises about 1 to about 40% by weight, more preferably about 1 to about 30% by weight, and most preferably about 5 to about 20% by weight of the inorganic thin layer compound based on the dry coating weight. If the amount is too low, the gas barrier properties of the coated and dried barrier layer are not appreciably improved compared to when no inorganic thin layer compound is used. If the amount is too high, the liquid composition is more difficult to apply as a coating and more difficult to handle in the storage tanks and conduits of the applicator system. Preferably, the barrier layer comprises about 99 to about 60% by weight, more preferably about 99 to about 70% by weight, and most preferably about 95 to about 80% by weight of the polymer based on the dry coating weight. Additives such as dispersion stabilizers or the like may be included in the gas barrier composition, preferably in an amount of about 1% by weight or less based on the dry coating. The total dry content of the composition is preferably 5 to 15% by weight, more preferably 7 to 12% by weight.

[0115] According to different preferred embodiments, the inorganic particles mainly consist of lamellar talcum particles having an aspect ratio of 10 to 500. Preferably, the composition contains talcum particles in an amount of 10 to 50% by weight, more preferably 20 to 40% by weight, based on dry weight. Below 20% by weight, there is no significant increase in gas barrier properties, and above 50% by weight, the coating layer is more brittle and fragile, since the internal cohesive forces between the particles in the layer are small. The polymer binder appears to be in too small an amount to surround, disperse and laminate the particles together in the layer. The total dry content of such liquid barrier composition from PVOH and talcum particles may be 5 to 25% by weight.

[0116] The preferred polymer binder is PVOH, even when inorganic particles are used to provide oxygen barrier properties, due in part to the advantageous properties mentioned above. In addition, PVOH is advantageous from a mixing standpoint, i.e., it is generally easy to disperse or exfoliate inorganic particles in an aqueous solution of PVOH to form a stable mixture of PVOH and particles, thereby allowing for good coated films with homogeneous composition and morphology.

[0117] Preferably, according to the invention, the oxygen gas barrier layer has a dry weight of 0.1 to 5 g / m 2 , preferably 0.5 to 3.5 g / m 2 , more preferably 0.5 to 2 g / m 2 It is applied in a total amount of 0.1g / m 2 Below 5 g / m, no gas barrier properties are achieved. 2 Above this level, the coated layer is generally not cost effective for packaging laminates due to the high cost of the barrier polymer and the high energy cost of evaporating the liquid. Appreciable levels of oxygen barrier are achieved above 0.5 g / m 2 Above this, a good balance between barrier properties and cost is achieved with PVOH, ranging from 0.5 to 3.5 g / m 2 This is achieved between

[0118] According to one preferred embodiment of the invention, the oxygen gas barrier layer is applied as a two-part layer in two successive steps with intermediate drying. When applied as a two-part layer, each layer has a thickness of 0.1 to 2.5 g / m 2 , preferably 0.5 to 1 g / m 2 This allows for a higher quality overall layer from a smaller amount of liquid gas barrier composition. More preferably, the two part layers are each applied in an amount of 0.5 to 2 g / m 2 , preferably from 0.5 to 1 g / m 2 is administered in an amount of

[0119] According to different embodiments of the present invention, the barrier coating may be applied onto the substrate surface of the film material using physical vapor deposition (PVD) or chemical vapor deposition (CVD). The substrate material itself may be involved with several properties as well, among which are that it should have suitable surface properties suitable for receiving the vapor deposition coating and should work efficiently in the vapor deposition process.

[0120] Deposited thin layers are usually only nanometers thick, i.e., have a thickness on the order of nanometers, for example, from 1 to 500 nm (50 to 5000 Å), preferably from 1 to 200 nm, more preferably from 1 to 100 nm, and most preferably from 1 to 50 nm.

[0121] One common type of vapor-deposited coating that often has some barrier properties, particularly water vapor barrier properties, is the so-called metallized layer, for example an aluminum metal physical vapor deposition (PVD) coating.

[0122] Such vapor-deposited layers, consisting essentially of aluminum metal, may have a thickness of 5 to 50 nm, which corresponds to less than 1% of the aluminum metal material present in the conventional thickness of packaging, i.e., aluminum foil of 6.3 μm. Although vapor-deposited metal coatings require significantly less metal material, they provide at best only a low level of oxygen barrier properties and need to be combined with further gas barrier materials to form a final laminate material with sufficient wall properties. On the other hand, this may be complemented by further gas barrier layers that do not have water vapor barrier properties but are rather sensitive to moisture.

[0123] Another example of a vapor deposition coating is aluminum oxide (AlO x ) and silicon oxide (SiOx) coatings. In general, such PVD coatings are more brittle and less suitable for incorporation into packaging materials by lamination. Metallized layers are an exception, as they have suitable mechanical properties for lamination materials, even though they are made by PVD, but generally have a low barrier to oxygen gas.

[0124] Other coatings that have been investigated for laminate packaging materials may be applied using plasma enhanced chemical vapor deposition (PECVD), where vapors of compounds are deposited on a substrate under more or less oxidizing conditions. Silicon oxide coatings (SiO x ) may also be applied, for example, by a PECVD process and may then obtain very good barrier properties under some coating conditions and gas recipes. Unfortunately, SiO x Coatings exhibit reduced adhesion properties when laminated by melt extrusion lamination to polyolefins and other adjacent polymer layers, and the laminate materials are exposed to wet or humid packaging conditions. Special expensive adhesives or adhesive polymers are required to reach and maintain sufficient adhesion in packaging laminates of the type intended for carton packaging for liquids.

[0125] According to the present invention, the deposition coating is an amorphous hydrogenated carbon barrier layer, so-called diamond-like carbon (DLC), applied by plasma enhanced chemical vapor deposition (PECVD). DLC defines a family of amorphous carbon materials that exhibit some of the typical properties of diamond. Preferably, a hydrocarbon gas, for example acetylene or methane, is used as process gas in the plasma to form the coating. As pointed out above, it has been found that such DLC coatings provide good and sufficient adhesion to adjacent polymer or adhesive layers in laminate packaging materials under wet testing conditions. Particularly good adhesive affinity with adjacent laminate polymer layers, i.e. polymer layers that adhere to or are coated with the DLC barrier coating, has been found in the case of polyolefins, and in particular polyethylene and polyethylene-based copolymers.

[0126] Thus, DLC barrier coatings impart good barrier and integrity properties to liquid-filled packaging containers made from packaging laminates comprising barrier films with barrier coatings by engaging with good mechanical properties, good barrier properties to various substances that migrate through such laminate materials in either the inward or outward direction from the filled package, and also by resulting in good adhesion to adjacent polymer layers in the laminate. Thus, barrier films from polyester or polyamide substrate layers with DLC barrier coatings can form packaging laminates and packaging containers with oxygen barrier properties and even water vapor barrier properties for long-term ambient storage, such as up to 2-6 months, up to 12 months. In addition, DLC barrier coatings provide good barrier properties to various aroma and flavor substances present in the packed food, to low molecular substances likely to appear in adjacent layers of materials, and to odors and gases other than oxygen. Furthermore, DLC barrier coatings, when laminated into carton-based packaging laminates, exhibit good mechanical properties as coated onto polymeric film substrates, withstand lamination and subsequent creasing of the packaging laminate, and seal within the filled package.

[0127] DLC coatings have the further advantage that they can be easily recycled without leaving any residue in the recycled content, including elements or materials that do not naturally occur in nature and our surrounding environment.

[0128] The use of adhesive polymers as described above would not be necessary for sufficient bonding, especially to the metallized layer or DLC barrier coating of the present invention. It was concluded that the metallized adhesion to the polyethylene layer was good and sufficient and adequate adhesion to the polyolefin layer as the adjacent layer also concerns DLC at a level of at least 200 N / m, such as at least 300 N / m. Adhesion measurements were performed at room temperature with a 180° peel force tester (Telemetric Instrument AB) 24 hours after LDPE lamination. Peeling was performed at the DLC / LDPE interface, the peel arm being the barrier film. When necessary, a drop of distilled water was added to the peel interface during peeling to evaluate adhesion in wet conditions, i.e. when the laminated packaging material is saturated with moisture migrating through the material layers, from liquids stored in packaging containers made from the laminated material, and / or by storage in wet or very humid environments. The given adhesion value is given in N / m and is the average of 6 measurements.

[0129] Thus, a dry adhesion of more than 200 N / m ensures that the layers will not delaminate under normal package manufacturing conditions, for example when the laminate material is bent and creased. This same level of wet adhesion ensures that the layers of the packaging laminate will not delaminate after filling and package formation during transportation, distribution, and storage. The internal bonding polymer layer can be coated directly onto the polymer film substrate onto which the DLC barrier layer is coated, by using common techniques and machines, for example those used for lamination of aluminum foil, especially for high temperature lamination (extrusion) of polymer layers from molten polymer onto the DLC barrier coating. It is also possible to use a pre-made polymer film and melt it locally and attach it directly to the barrier coating carrier film by applying heat, for example with a hot cylinder or heated roller. From the above, it is clear that the DLC barrier film can be handled in a similar manner to aluminum foil barriers in lamination and conversion methods into laminate packaging materials, i.e., using extrusion lamination and extrusion coating. The lamination equipment and methods do not require any modification, for example by adding specific adhesive polymers or binder / tie layers, as is required with other plasma-coated materials. In addition, the new barrier film, with the DLC barrier layer coated thereon, can be made as thin as aluminum foil without adversely affecting the barrier properties in the final food package.

[0130] It has been found that when manufacturing the laminate packaging material of the present invention, in asymmetric laminates having a layer structure with unequal tensile stiffness properties on the two sides of the spacer layer, a problem called moisture-induced curling appears, i.e. the flat material does not remain flat when placed on a flat surface, but curls up so that the ridges rise above the plane of the flat part of the packaging material and bend towards each other. A further advantage of the flat laminate length sides in the packaging container is that the grip stiffness is improved. This is due to the straight panels without initial "defects", such as bends. Naturally, there are fewer problems when passing flat packaging materials through a filling machine compared to curled and curved ones.

[0131] It has been found that curling is primarily prevented by matching the paper facing layers on each side of the spacer layer to have equal overall tensile stiffness. By doing so, it has been surprisingly found that the compressive strength of the laminate in the xy direction is also increased due to the flatness of the laminate material panels. This means, for example, that packaging containers folded from laminate packaging material can be stacked on top of each other during distribution and storage at higher loads than liquid food packages available on the market today.

[0132] As a result, packages made from such symmetrically sized laminate packaging materials having a paper facing layer on each side of the sandwiched spacer layer may have improved package integrity, i.e., the laminate material is less prone to damage and cracks in the barrier layers due to simple handling and shipping.

[0133] When the mechanical properties of the sandwich material are balanced in this manner, the various laminate layers, including the barrier layers that protect the packaged food from slowly moving oxygen and other gases and vapors, are also more resistant to damage and delamination, and as a result, the integrity of the filled and sealed package is also improved in this respect.

[0134] Thus, a further aspect of improving package integrity is to improve the adhesion between various layers. Particularly good initial adhesion is obtained between dispersion or solution coated barrier coatings having hydrophilic functional groups such as hydroxyl and carboxyl groups and adjacent layers such as polyolefins and polyethylenes. Also, vapor deposition metallized coatings and DLC PECVD coatings have been demonstrated to impart very good adhesive properties to adjacent organic polymer layers and films such that no extra primers or adhesives should be used between them and their adjacent layers in laminate packaging materials.

[0135] However, at least with respect to the metallized barrier coating layer, further adhesion enhancement by lamination to an adjacent layer of a tie polymer or adhesive polymer has also been shown to surprisingly improve the oxygen barrier properties of the laminate material to an even greater extent.

[0136] Additional oxygen barrier properties can be provided by including a further layer of polymer that acts as a barrier to migrating free fatty acids, such as a polyamide in the first pre-laminated material to be laminated to the bulk layer. In particular, when the polyamide is added to the inside of the metal barrier layer, it prevents free fatty acids from the packed food from migrating from the food to the metal barrier layer, and thus the barrier properties of the barrier layer are not compromised and the adhesion (heat seal) of the inner polymer layer to the metal barrier can be maintained over long storage periods.

[0137] The paper facing layer on the outside of the bulk layer may in one embodiment be the same or a different compact surface barrier paper, coated or uncoated, as laminated to the inside of the bulk layer, and of course such a paper facing layer then also contributes to the oxygen barrier of the final packaging laminate.

[0138] According to yet further embodiments, packaging based on bio-based renewable materials can be obtained, wherever possible. For example, packaging materials can be produced that have cellulose-based spacer and bulk layers, paper facing layers with barrier properties and further with very thin nano-thin barrier coatings. Furthermore, thermoplastic polymers can be produced from vegetable or organic materials, such as the so-called green polyethylene.

[0139] In addition, the adhesives or adhesive polymers used in the lamination operation to produce the final laminated packaging material are entirely bio-based and may be used in very small quantities, which further increases the relative proportion of renewable and cellulose fibre content.

[0140] The outermost heat sealable layer of the laminate material can alternatively be prepared as one or two pre-manufactured films. Such a film can therefore be pre-laminated to a barrier layer in a first pre-laminate material to be laminated to the first side of the bulk layer, and / or pre-laminated to a printed and decorated outer surface layer to be laminated to the second side of the bulk layer. When the film is pre-laminated to the barrier layer or the printed and decorated layer, this can be by only heat pressure lamination of the film to the other layer, especially when a layer pre-coated or integrated with an adhesive polymer such as EAA or EMAA is present on one of the lamination surfaces. Alternatively, it can be by using melt extrusion lamination, which is costly due to the high consumption of the intervening melt extruded polymer, or by pre-coating with a small amount of water-based adhesive that can penetrate at least into the paper or cellulose-based surface to be laminated, without the need for a drying step.

[0141] In an effort to generally reduce the cost of laminate packaging materials, it is highly desirable to combine properties in the various layers so as to minimize the number of added layers required.

[0142] When the conventional liquid packaging paperboard of today's packaging laminate is replaced by a weaker bulk layer, thereby allowing significant cost reduction, some additional costs can be spent instead on a tailored decorative substrate for printing and decoration of the laminated packaging material. Since the bulk layer of the present invention no longer constitutes the printing surface, i.e. the surface to be printed, the expensive clay coat can be omitted from the bulk layer, and a smooth white printing surface can be obtained by other means on the outer printing substrate facing paper, which is to be laminated on the other side of the bulk layer. Such a printing substrate can be, for example, a color film or a white printable paper facing layer. Alternatively, the white paper for forming the white printing background surface is pre-laminated to a transparent film, i.e. a reverse printing film, which is printed before lamination on the back side, so that the printed decoration is directed towards the white paper surface and is protected by the transparent film substrate. Thus, printing and lamination to the outer white paper facing layer and optionally further lamination to the outermost heat-sealable layer may be performed in a pre-lamination operation to provide a second pre-laminate material for the second side, i.e., the outside, of the laminate packaging material.

[0143] To further add light barrier properties and whiteness, such films or papers may be provided with a metallized layer, or alternatively with a white filler material or a clay coat in the case of paper. For some products and appearances of packaging containers, a metallized printed surface is preferred, while in other cases a color printed surface or a brown natural cellulose printed surface is preferred. By leaving the printed surface layer out of the bulk layer, versatility in possible exterior appearances is possible, which is an additional advantage of the three-part modular lamination model of the present invention. Yet another oxygen barrier layer may be included in the second pre-laminate material to enhance the overall barrier performance of the final laminate material.

[0144] In the following, preferred embodiments of the present invention will be described with reference to the drawings. [Brief description of the drawings]

[0145] [Figure 1a] 1 is a schematic cross-sectional view of a specific example of a laminated packaging material having a compact surface barrier paper layer according to the present invention. [Figure 1b] FIG. 2 is a schematic cross-sectional view of a further such specific embodiment of a laminated packaging material having a compact surface barrier paper layer. [Figure 1c] FIG. 2 shows a cross-sectional view of a third embodiment of a laminate packaging material. [Figure 2a] FIG. 2 is a schematic diagram showing the lamination process of the method of the present invention. [Figure 2b] FIG. 2 shows a schematic diagram of an example of different lamination operations that can be combined with the method of the present invention. [Figure 3a] FIG. 2 is a diagram showing a typical example of a packaging container produced from a laminate packaging material according to the present invention. [Figure 3b] FIG. 2 is a diagram showing a typical example of a packaging container produced from a laminate packaging material according to the present invention. [Figure 3c] FIG. 2 is a diagram showing a typical example of a packaging container produced from a laminate packaging material according to the present invention. [Figure 3d] FIG. 2 is a diagram showing a typical example of a packaging container produced from a laminate packaging material according to the present invention. [Figure 4] FIG. 1 illustrates the principle by which packaging containers are produced from packaging laminates in a continuous, roll-fed, form-fill-and-seal process. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0146] 1a there is shown a cross-sectional view of a first embodiment of a laminate packaging material 10a of the present invention, which comprises a bulk material layer 11a of paperboard or other cellulose-based material.

[0147] Inside the bulk layer 11a, the laminate material comprises a thin high density paper layer 12a, in this particular example a metallised coating, on which is applied a barrier coating 13a. The paper layer 12a is a thin high density compact surface barrier paper layer having a surface roughness of less than 300 Bendtsen ml / min, such as 250 ml / min. In particular, here a 32 g / m2 barrier paper from Nordic Paper is used. 2 A greaseproof paper of the type Super Perga WS Parchment having a weight of about 100 g / m2 and a surface roughness of about 200 ml / min was used.

[0148] The packaging material also includes an innermost heat-sealable thermoplastic layer 14a, which is the layer of the packaging laminate that will be in direct contact with the filled food product in the final package. The innermost heat-sealable polymer layer 14a is applied to the inside of the bulk material layer using melt extrusion coating of a multi-layer polymer structure, or melt coextrusion coating.

[0149] The barrier paper 12a, 13a on the inside of the bulk material layer may be first coated with one or more additional barrier coatings. In an alternative embodiment, it may be first pre-coated with a PVOH barrier polymer, which is applied onto the paper surface layer 12a using an aqueous dispersion in a preceding coating and drying operation. Afterwards, the metallized coating 13a may then be applied on top of the pre-coated surface. The barrier-coated barrier paper 12a is oriented in the laminate such that the barrier coating faces outward (i.e., from the laminate packaging material toward the outside, which is the inside of the package) in the packaging laminate. In an alternative embodiment, the paper 12a provides some barrier properties by itself when laminated between the polymer layers, such that it is uncoated and still provides some barrier properties and thus is a barrier layer without the application of an additional barrier coating. In a further alternative embodiment, the metallized barrier-coated paper may be oriented in the other direction in the laminate, whereby the metallization faces toward the interior of the laminate, i.e., toward the bulk material layer.

[0150] The (co)extrusion coating of the innermost layer 14a may be performed before or after lamination of the barrier paper 12a to the spacer layer 11a. The innermost heat-sealable layer or multilayer 14a may alternatively be applied in the form of a prefabricated film, adding additional stability and durability by being an oriented film to a greater extent than is obtainable in an extrusion coating operation. Again, the inner material layer may be prelaminated as a separate module on the inside before laminating to the spacer layer 11c. However, in this particular embodiment, the barrier coated paper 12a-13a is first laminated to the bulk material layer 11a, or the remainder of the laminate material. The bulk material layer is then melt extrusion coated onto the inner side of the layer or multilayer 14a of heat-sealable polymer, which is a polyolefin, which is a low density polyethylene composition comprising a blend of metallocene-catalyzed linear low density polyethylene (m-LLDPE) and low density polyethylene (LDPE).

[0151] On the other side, outside the metallized barrier paper layers 12a, 13a, the packaging material comprises an outermost liquid-tight transparent layer 15a of a heat-sealable thermoplastic such as a polyolefin, such as a polyethylene material layer. The printed substrate and metallized barrier paper 12a, 13a may be printed before or after a coating with the outermost plastic layer 15a is applied onto the printed barrier paper substrate layer 12a, 13a in a separate operation, either before or after lamination to the bulk material layer 11a.

[0152] The lamination of the print substrate and barrier paper layers 12a, 13a to the bulk material layer 11a is carried out by applying a small amount of an aqueous composition of adhesive that is partially absorbed into the respective cellulose layers and effectively bonds the two paper cellulose layers together, the adhesive binder polymer being starch or nano / micro fibrous cellulose or polyvinyl alcohol / polyvinyl acetate or similar hydrophilic substances that easily bond to cellulose molecules. Of course, when the adhesive material has inherent barrier properties, such adhesive binder polymer is applied in a very small amount, but can be even more involved in the resulting oxygen barrier properties of the laminated packaging material.

[0153] In Fig. 1b, a cross-sectional view of a second embodiment of a laminate packaging material 10b is shown. In principle, this is a laminate consisting of three initial modules of material layers involved in a sandwich structure that essentially gives the laminate material mechanical strength properties and dimensional stability to the final packaging container. Module 1A is a central layer of bulk material from a spacer layer 11b of low density or low grade cellulose material, such as a foam-forming fibrous cellulose layer or a layer of fluting material.

[0154] The outer material module 1B comprises a printing substrate layer of thin high density paper 12b having a printing surface. The paper 12b also constitutes a facing layer on the outside of the sandwich structure that interacts with the spacer layer 11b. In the final laminate material, the substrate 12b is printed and decorated with a printing pattern from various colors, images and texts. The outer material module 1B also comprises an outermost liquid-tight transparent layer 14b of a plastic, preferably a heat-sealable thermoplastic such as a polyolefin, such as a polyethylene material layer. The printing substrate and paper facing layer 12b may be printed before or after lamination to the central spacer layer, and the outermost plastic layer 14b is applied on the printing substrate layer in a separate operation before or after lamination to the spacer layer 11b. If the decorative print coating with plastic layer 14b is carried out prior to lamination to the central module spacer layer, then the entire outer material module is prepared as one module, i.e. as a pre-laminated outer side, which is then laminated to the remainder of the central module or laminate, outside the central spacer layer.

[0155] The lamination operation of the printing substrate paper facing layer 12b to the central module spacer layer 11b is carried out by applying a small amount of an aqueous composition of an adhesive binder polymer which is partially absorbed within the respective cellulose layer and effectively bonds the two paper cellulose layers together, the adhesive being starch or nano / micro fibrous cellulose or polyvinyl alcohol / polyvinyl acetate or similar renewable / biodegradable material which can bond well to the cellulose molecules.

[0156] The other side, inside, of the central module 2A, the inner material module 2C comprises a barrier film 16b, which is a polymer substrate film with a barrier coating applied to the side. The inner material module also comprises an innermost heat-sealable thermoplastic layer 15b, which is also the layer of the packaging laminate that directly contacts the filled food in the final packaging container. The innermost heat-sealable polymer layer 15b is applied onto the barrier film using melt extrusion coating, or melt coextrusion coating, of a multilayer polymer structure onto the inside of the barrier film 16b. The barrier coating is provided in this embodiment with a vapor deposition barrier coating applied onto the polymer film substrate using a vapor deposition coating in a preceding vapor deposition operation. The barrier coating is a metallized coating applied in this embodiment using a physical vapor deposition method, which is not shown in the figure. The barrier coating film may alternatively be oriented within the laminate so that the barrier coating faces outward in the packaging laminate, toward the central module and the paper facing layer 12b, but in this particular embodiment it is oriented inward, toward the innermost encapsulation layer. The (co)extrusion coating of the innermost layer 15b can be done before or after lamination of the inner material module 2C to the central module 2A. The innermost heat-sealable layer or multi-layer 15b can alternatively be applied in the form of a pre-fabricated film, adding some additional stability and durability by being a uniaxially or biaxially oriented film to a greater extent than that obtained in an extrusion coating operation. Again, the inner material module 2C can be pre-laminated as a separate module on the inside before laminating to the central module 2A. However, in this particular embodiment, the barrier coating film 16b is first laminated to the bulk material, or the rest of the laminate material, i.e., module 2A is laminated to the outer module 2B, and then melt extrusion coated on the inner side of the barrier coating film with a layer or multi-layer 15b of heat-sealable polymer, which is a polyolefin, which is a low-density composition comprising a blend of metallocene-catalyzed linear low-density polyethylene (m-LLDPE) and low-density polyethylene (LDPE).

[0157] The lamination operation for laminating the barrier substrate film 16b to the bulk material layer 11b is carried out using 1 to 2 g / m2 of an aqueous dispersion of ethylene acrylic acid copolymer having a dry content of about 45 wt. %. 2 , i.e. about 1.5 g / m 2 may be carried out by first applying the aqueous adhesive composition coating to the free surface of the barrier film 16b, and then pressing the inside of the bulk material layer against the surface of the adhesive coated barrier film, whereupon the layers are laminated to one another with the aqueous adhesive composition coating providing an intervening bond between the layers.

[0158] The printing substrate 12b typically has a decorative pattern printed on its surface, which is however not shown in Figure 1b. Alternatively, the printing substrate may be a colored or metallized polymer film.

[0159] The barrier substrate 16b may alternatively be a barrier coated paper, such as a metallized paper.

[0160] FIG. 1c shows a cross-sectional view of a third embodiment of a laminate packaging material 10c.

[0161] There is provided a first web A with a layer of liquid carton board 11c and a second web of metallized polymer film 12c intended for the outside of packaging materials, such as oriented polypropylene (OPP, BOPP) or oriented PET film. An aqueous composition containing an adhesive is applied (21) onto the metallized surface 13c of the metallized film as it is conveyed. The two webs 11c;A, 12c;B are conveyed towards a pressure roller nip 22, the second web is applied with an aqueous adhesive 18c on its surface and is joined and laminated during the passage through the nip by the intervening aqueous adhesive composition, which is partially absorbed into the first web 11c. No forced drying or heat curing of the aqueous adhesive composition is required and the lamination speed can be kept as high as the usual lamination speeds of more than 300 m / min, or more than 400 m / min, or even more than 500 m / min. In particular, in this embodiment, the web of layer 11c is a conventional clay-coated paperboard of a type suitable for carton packaging for liquids. The clay-coated surface partially absorbs the aqueous adhesive composition, as well as the cellulose fiber network without such a coating. The metallized surface of film web 12c;B has a high smoothness to provide a uniform wet coating with a thin film application of the liquid adhesive, ensuring a controlled and uniform (over the entire surface) absorption of the adhesive composition onto the opposing surface to be bonded in the pressure nip 22, i.e., the clay-coated paperboard of web A. The adhesive binder polymer is an ethylene acrylic acid copolymer (EAA) dispersion in water, with a solids content of 40 to 50% by weight and a dry content of about 2 g / m. 2 A quantity of 100 mg / g is applied.

[0162] The laminated paperboard and outer metallized film 11c, 12c-13c;A+B are then wound on reels and mass-produced for intermediate storage on the reels. When it is time to produce the laminated packaging material with the metallized film 12c-13c as the printing substrate, the paperboard metallized film laminate is pulled off the reel and led to a printing station for conventional printing of a decorative pattern on the film side, where a metallized shiny decorative background is obtained. The printed material is then further laminated to the outermost heat-sealable liquid-tight protective thermoplastic polymer layer 14c and the innermost heat-sealable liquid-tight protective thermoplastic polymer layer 15c by extrusion coating or film lamination in the usual manner, which includes lamination to a barrier material layer 16c, such as aluminum foil, on the inside of the bulk paperboard layer 11c, between the paperboard and the innermost thermoplastic layer 15c, i.e., on the side of the paperboard layer facing the printed decorated outside. The barrier layer 16c is bonded to the paperboard layer 11c using a tie layer 17c of a thermoplastic polymer, such as a polyolefin, such as polyethylene. The innermost heat sealable layer is bonded to the barrier layer, the aluminum foil, using an adhesive polymer, such as EAA, that is coextrusion coated with the innermost heat sealable polymer, i.e., as a two-layer configuration of the heat sealable olefin-based polymer 15c.

[0163] The resulting adhesion between the outer metallized films 12c-13c and the paperboard 11c exceeds 100 N / m and has been proven to be strong enough throughout the entire lamination production, intermediate reel storage of the laminate material, further printing and lamination steps, and even throughout the entire production of the folded, filled and sealed packaging containers for liquid foods from the laminate material. The advantages therefrom are significant and greatly simplify the packaging laminate production process. Up to now, the lamination of metallized films to paperboard has been achieved using a thickness of about 15 g / m2 of low density polyethylene (LDPE). 2Previously, the metallized film had to be laminated by melt extrusion lamination with an intervening layer of LDPE, which, of course, is rather expensive in terms of raw material costs. Furthermore, the metallized film, which is thin and delicate to handle during lamination, is exposed to significant heat loads from the hot melt extruded LDPE at about 280-320°C while the film web moves under tension into the chilled pressure roller nip. Defects caused by such rough handling can be avoided by methods such as those described above. The subsequent heat lamination step is performed when the film is already adhered and set to the paperboard, and is therefore not as vulnerable to similar heat loads as later in the manufacturing process.

[0164] In Fig. 2a it is shown as a schematic how one layer or module of layers can be laminated to another layer / module by low-temperature aqueous adhesive absorption lamination, where a very small amount of aqueous adhesive solution is applied to one of the surfaces to be laminated to each other, the aqueous adhesive solution is absorbed into one or both of the two surfaces and then adheres under pressure. Thus, in the embodiment for producing the laminated packaging material of Fig. 1a-b, an aqueous adhesive solution is applied to the surfaces to be laminated, i.e. the non-printed surfaces of the printed substrate layers 16a; 16b, of the outer layer / material modules 1B; 2B, representing the outer layers of the bulk and spacer layers, in an adhesive application operation 21. In the lamination nip between the two nip rollers, the web of central module material 1A; 2A, representing the bulk layer including the spacer layer, is laminated to the web of outer module material 1B; 2B at the lamination station 22 under a step of simultaneously sending the two webs through the lamination nip with a pressure high enough to bond the two surfaces together, but not so high that the low density spacer layer of the sandwich structure is crushed. The resulting web of intermediate pre-lamination of the two layers / modules 1A+1B; 2A+2B is sent to a further lamination station for lamination to a third module or part thereof as described below in FIG. 2b, or alternatively, wound on a reel for intermediate storage or transport at a different time or place, where the final lamination and final step takes place. A low-temperature water-based adhesive absorption lamination method can also or alternatively be applied when laminating the inner material module 1C; 2C to the central layer / module material or to the pre-laminated central and outer modules.

[0165] In Fig. 2b it is shown as a schematic how one layer / module can be laminated to another layer / module by melt extrusion lamination so that the two surfaces to be laminated are bonded to each other by an intermediate thermoplastic bonding layer. According to this example, the webs of the pre-laminate of the two modules laminated in the example of Fig. 2a are fed into the lamination nip simultaneously with the webs of the inner material modules 1C; 2C. At the same time, a molten curtain of thermoplastic bonding polymer 23; 19a; 19b is extruded into the lamination roller nip and cooled while pressing the two webs together, so that sufficient adhesion is obtained between the surface of the cellulose-based central module, i.e. the spacer layer 11a; 11, and the barrier paper 13a; 13b of the inner material modules.

[0166] FIG. 3a shows an embodiment of a packaging container 30a produced from a packaging laminate 10a; 10b; 10c; 10d according to the invention. The packaging container is particularly suitable for beverages, sauces, soups or the like. Typically such packages have a volume of about 100 to 1000 ml. It may have any configuration, but is preferably brick-shaped, with longitudinal seals 31a and transverse seals 32a, respectively, and optionally an opening device 33. In another embodiment, not shown, the packaging container may be wedge-shaped. To obtain such a "wedge shape", only the bottom part of the package is creased such that the transverse heat seal at the bottom is hidden under a triangular corner flap that is folded and sealed against the bottom of the package. The transverse seal at the top is left unfolded. In this way, the half-folded packaging container is still easy to handle and dimensionally stable when placed on a shelf in a grocery store, or on a table, or the like.

[0167] Figure 3b shows an alternative preferred example of a packaging container 30b produced from an alternative packaging laminate according to the present invention. The alternative packaging laminate is thinner by having a thinner cellulose bulk layer 11 and therefore does not have sufficient dimensional stability to form a cubic, parallelepiped or wedge shaped packaging container and is not creased after transverse seal 32b. It therefore remains a pouch-like container with a pillow-like shape and is distributed and sold in this form.

[0168] 3c shows a gable-top package 30c that is folded from a pre-cut sheet or blank of laminated packaging material including bulk layers of paperboard and the durable barrier film of the present invention. Flat-top packages may also be formed from similar blanks of material.

[0169] Fig. 3d shows a bottle-like package 30d, which is a combination of a sleeve 34 formed from a pre-cut blank of the laminated packaging material of the present invention and a top 35 formed by injection molding plastic in combination with an opening device such as a screw cork or the like. This type of package is sold, for example, under the trademarks Tetra Top® and Tetra Evero®. Those particular packages are formed by attaching a molded top 35 to a tubular sleeve 34 of laminated packaging material with the opening device attached in a closed position, sterilizing the bottle-top capsule so formed, filling it with a food product, and finally creasing and sealing the bottom of the package.

[0170] 4 shows the principle as explained in the introduction of this application, i.e. a web of packaging material is formed into a tube 41 with the longitudinal ridges 42 of the web being joined to one another at overlap seams 43. The tube is filled (44) with the intended liquid food product and divided into individual packages by repeatedly transversely sealing (45) the tube at predetermined distances from one another below the level of the contents filled in the tube. The packages 46 are separated by cutting in the transverse seals and given the desired geometric configuration by creasing along prepared crease lines in the material.

[0171] We have therefore seen that the new method of the invention also makes it possible to achieve packaging containers that have good integrity properties even under wet conditions, i.e. for packaging liquid or moist foods with a long shelf life.

[0172] Generally, the basis weights mentioned in the above and following description are as measured by SCAN P 6:75. Material density and layer thickness were measured according to ISO 534:1988.

[0173] The present invention is not limited by the embodiments shown and described above, but may be modified within the scope of the claims. In general, the relative proportions of layers, the distances between layers, and the sizes of other features compared to one another and their relative sizes should not be construed as being precisely as shown in these figures, which are merely indicative of the order and types of layers relative to one another, with all other features to be understood as described in the specification. [Explanation of symbols]

[0174] A. First Web 1A Module 1B Outer Material Module 1C;2C Inner Material Module 2A Core Module 2B Outer module 2C Inner Material Module 10a;10b;10c;10d Packaging laminate 10a Laminated packaging materials 10b Laminated packaging materials 11a;11 Spacer layer 11a Bulk material layer 11b Spacer layer 11c Liquid Carton Board 11c;A Web 12 Barrier Coated Barrier Paper 12a Thin high density paper layer 12b thin high density paper 12c Metallized polymer film 12c;B Film Web 12c~13c;A+B Laminated paperboard and outer metallized film 13a Barrier Coatings 13a;13b Barrier paper 13c metallized surface 14a Innermost heat sealable thermoplastic layer 14b Outermost liquid-tight transparent layer 14c Outermost heat sealable liquid-tight protective thermoplastic polymer layer 15a Outermost liquid-tight transparent layer 15a Outermost plastic layer 15b Innermost heat sealable thermoplastic layer 15c Innermost heat sealable liquid-tight protective thermoplastic polymer layer 15c Innermost thermoplastic layer 16a;16b Printing base layer 16b Barrier Film 16c Barrier material layer 17c Thermoplastic polymer tie layer 18c Water-based adhesive 21 Adhesive application work 22 Pressure Roller Nip 23;19a;19b Thermoplastic bonding polymers 30a packaging container 30b Packaging container 30d Package 31a Longitudinal Seal 32a Transverse Seal 32b Transverse Seal 33 Open Device 34 Sleeve 35 Top 41 Tube 42 Longitudinal Ridge 43 Overlap seam allowance 44 Filled 45 Transverse sealing 46 Packages

Claims

1. A method for the manufacture of a laminate packaging material (10a; 10b) for carton packaging of liquid foods, comprising the steps of: a. providing a first web comprising a layer A of paper or paperboard, or other cellulose-based material (11a; 11b; 11c); b. Providing a second web comprising a film or sheet B (12a; 12b); c. 1-4g / m dry content ２ applying an aqueous adhesive composition onto a surface of one of the first and second webs, the aqueous adhesive composition comprising an amount of adhesive; d. feeding said first and second webs, one of which has said aqueous adhesive composition applied thereto, towards a pressure roller nip (22) where said first and second webs are bonded and laminated by said aqueous adhesive composition while passing through said nip and while said aqueous adhesive composition is partially absorbed into at least one of the first and second web surfaces of A and B; e. attaching an outermost thermoplastic polymer layer and an innermost thermoplastic polymer layer to form said laminate packaging material; there is no forced drying of the applied aqueous adhesive composition and the lamination occurs at ambient temperature; There is no forced drying of the aqueous adhesive composition even after the laminating step. method.

2. 10. The method of claim 1, wherein the aqueous adhesive composition comprises an adhesive binder polymer selected from the group consisting of polyvinyl alcohol (PVOH), polysaccharides and polysaccharide derivatives such as starch and cellulose and their derivatives, polyvinyl acetate, and acrylic modified polyolefin adhesive polymers.

3. 3. The method according to claim 1 or 2, wherein the second web of film or sheet B (12b) has a surface roughness as defined in SCAN (Scandinavian Pulp and Paper Norms) P21-67 and TAPPI UM 535 (ISO 8791-2) of 100 Bendtsen or less, or 150 Bendtsen or less, or 200 Bendtsen or less, and the aqueous adhesive composition is applied onto the second web.

4. The method of claim 2 , wherein the adhesive binder polymer has a solids content of 30 to 50% by weight.

5. The amount of adhesive binder polymer applied is 0.5 to 1.8 g / m2 in terms of dry content. ２ , or 1 to 1.5 g / m2 in dry content ２ , or 0.5 to 2 g / m ２ The method according to claim 2 or 4, wherein

6. 3. The method of claim 2, wherein the web of layer B is a paper or paperboard or cellulose-based layer and the adhesive binder polymer is selected from the group consisting of PVOH, polyvinyl acetate, starch or starch derivatives, and cellulose and cellulose derivatives.

7. The adhesive binder polymer has a dry content of 2 to 3 g / m ２ , or 1 to 3 g / m ２ The method of claim 2 wherein the amount of

8. The method of claim 1, wherein said layer A has a moisture content of 5-10% RH.

9. 9. The method according to any one of claims 1 to 8, wherein layer A has a surface roughness as defined in SCAN (Scandinavian Pulp and Paper Norms) P21-67 and TAPPI UM 535 (ISO 8791-2) of 500 Bendtsen or more, or 400 Bendtsen or more, or 300 Bendtsen or more.

10. A method according to any one of the preceding claims, wherein the web speed of the lamination through the roller nip is 300m / min or more, or 400m / min or more, or 500m / min or more, or at least 200m / min.

11. A method according to any one of the preceding claims, wherein the adhesion between layers A and B is at least 100 N / m, or at least 60 N / m.

12. 12. The method according to any one of claims 1 to 11, wherein said film or sheet B (12a; 12b) is laminated on the outside of layer A (11a; 11b), i.e. on the outside of a packaging container made from said packaging material, and comprises a pre-laminate structure comprising a printed substrate or a printed substrate with a printed decorative pattern and an outer transparent protective polymer layer (14a; 14b).

13. 13. The method according to any one of claims 1 to 12, wherein said film or sheet B (16b) is laminated to the inside of layer A (11b), i.e. to the inside of a packaging container made from said packaging material, and comprises a pre-laminate structure comprising at least one barrier layer or barrier coating (17b), or a barrier layer or barrier coating and an innermost heat-sealable liquid-tight thermoplastic polymer (15b).

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