Lamination method and lamination station

Abstract

A method and wet lamination station for laminating a barrier film or sheet (6) to a bulk layer (5) of cellulosic material such as paper or paperboard, said bulk layer (5) being provided with through holes (3).

Description

[Technical field]

[0001] The present invention relates to a method for laminating a barrier film to a bulk layer of a laminate packaging material for packaging liquid food products, the bulk layer being provided with perforations. The present invention also relates to a lamination station. [Background technology]

[0002] Disposable packaging containers for liquid foods are often manufactured from packaging laminates based on paperboard or carton. One such common packaging container is sold under the name 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 of this known packaging container is typically a laminate comprising a bulk or core layer of paper, paperboard or other cellulosic material and an outer liquid-tight layer of thermoplastic plastic. To make the packaging container gas-tight, and in particular oxygen-tight, for example for the purposes of aseptic packaging or packaging of milk or fruit juice, the laminates of these packaging containers usually comprise at least one additional layer, most commonly an aluminum foil, which acts as a barrier.

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

[0004] Packaging containers are generally produced by modern high-speed packaging machines of the type that form, fill and seal packages from webs or from prefabricated blanks of packaging material. Thus, packaging containers can be produced by converting a web of laminate packaging material into a tube by joining both longitudinal edges of the web together with an overlapping joint by welding together the inner and outermost heat-sealable thermoplastic polymer layers. The tube is filled with the desired liquid food product and then divided into individual packages by repeated transverse sealing of the tube at a predetermined distance from each other below the level of the contents in the tube. The packaging material is separated from the tube by scoring along the transverse seals and given the desired geometric shape (usually a parallelepiped) by folding the packaging material along pre-prepared crease lines.

[0005] The main advantage of this continuous tube forming, filling and sealing packaging process concept is that the web can be continuously sterilized just before tube forming, thus offering the possibility of an aseptic packaging process, i.e. a process in which the liquid contents to be filled and the packaging material itself are reduced from bacteria, the filled packaging containers are produced under clean conditions, there is no risk of microbial growth in the filled product and it can be stored for long periods even at room temperature. Another important advantage of Tetra Brik® type packaging processes is, as mentioned above, the possibility of continuous high speed packaging, which has a considerable impact on cost efficiency.

[0006] Packaging containers for sensitive liquid foods, such as milk and juice, can also be produced from sheet blanks or preassembled blanks of the laminate packaging material of the invention. Packaging containers are produced from tubular blanks of the flat-folded packaging laminate by first assembling the blanks to form an open tubular container capsule, which is closed at one of its open ends by folding and heat sealing an integral end panel. The container capsule thus closed is filled from its open end with the food product, such as juice, and is then closed by further folding and heat sealing the corresponding integral end panel. Examples of packaging containers produced from sheet and tubular blanks are the conventional so-called gable-top packages. Packages of this type may also have a molded plastic top and / or a screw cap.

[0007] The disposable packaging may be provided with an opening structure, for example to allow a straw to be inserted into the packaging. To reduce the penetration force required by the consumer, laminate packaging materials are modified in various ways. One common method is to puncture the bulk or core layer before lamination and cover the inner and outer holes with an additional laminate layer containing a barrier material. Such a configuration eliminates the need for the consumer to penetrate the bulk or core layer, significantly reducing the required penetration force. The intact barrier provides the desired integrity of the packaging until the straw is inserted.

[0008] The lamination of the barrier layer to the bulk or core layer is usually performed by extrusion lamination, where the extruded molten polymer is brought into contact with the bulk or core layer and the barrier layer just upstream of the nip formed between the nip roller and the chill roller. At this nip, the bulk or core layer and the barrier layer are contacted with the molten extruded polymer almost simultaneously and pressed together, allowing the lamination of the bulk layer and the barrier layer. The laminate structure is then cooled, usually by running along a portion of the chill roller, while the molten extruded polymer completely solidifies. To obtain adequate adhesion and laminate strength, a minimum thickness of the molten extruded polymer is required to bond the two layers, the bulk or core layer and the barrier layer. The minimum thickness depends on the stiffness and thickness of the bulk layer, but is usually at least 15 g / m 2 , e.g. at least 18 g / m 2 , e.g. at least 20 g / m 2 It is.

[0009] In order to improve the sustainability of packaging materials, reducing the thickness of laminate packaging materials, especially the thickness of the extrusion laminate layer or adhesive layer, can not only increase the fiber content of the laminate packaging material but also reduce the CO2 footprint. For this reason, it has been proposed to replace extrusion lamination with wet lamination.

[0010] Wet lamination as applied in the above context is accomplished by applying a wet adhesive coating to the barrier before it enters the nip to contact the bulk or core layer. The nip roller applies pressure against a motor-driven backup roller, or vice versa, to force adhesion between the barrier and the bulk or core layer.

[0011] However, wet lamination of bulk or core layers with holes presents many drawbacks. For example, the adhesive utilized to bond the barrier to the bulk or core layer can leak through the holes and get on the nip rollers, which can cause contamination of the laminating equipment, including the formation of residue on the packaging material at any stage downstream of the nip. This can result in performance problems and integrity issues for the packaging container.

[0012] Therefore, there is a need for an improved method and apparatus for wet lamination of perforated substrates that reduces the risk of wet adhesive adhering to the lamination rollers. Summary of the Invention [Problem to be solved by the invention]

[0013] It is an object of the present invention to at least partially overcome one or more of the above identified limitations of the prior art, in particular to prevent contamination of lamination equipment during wet lamination of substrates having through holes.

[0014] To achieve these objectives, a method is provided for laminating a barrier film or sheet to a bulk layer of perforated paper or paperboard or cellulosic material. The method comprises coating the barrier film or sheet with a wet adhesive and feeding the coated barrier to a nip. The nip is formed between a nip roller and a support roller such that an uncoated side of the barrier film or sheet contacts the nip roller. The nip roller comprises a surface material that is softer than the surface material of the support roller. The term "surface material" in this context should be interpreted as the material of the respective roller that contacts the barrier film or sheet or bulk layer during use.

[0015] The method further includes feeding the bulk layer into said nip such that the bulk layer contacts a support roller, and feeding the bulk layer and the coated barrier film or sheet through the nip, whereby the bulk layer is adhered to the barrier film or sheet by the adhesive.

[0016] By providing the barrier film or sheet with the uncoated side in contact with the nip roller and the bulk layer in contact with the support roller, the risk of contact with the rollers can be reduced because the wet adhesive is contained between the barrier film or sheet and the bulk layer.

[0017] The bulk layer may be provided as a continuous web.The barrier film or sheet may be provided as a continuous web.

[0018] The barrier film or sheet may be an aluminum foil, a plastic film with a barrier coating, or a paper or cellulosic sheet with a barrier coating.

[0019] The bulk layer and the barrier film or sheet may have a combined thickness of 0.2 to 0.45 millimeters.

[0020] The method may include adjusting the distance between the support roller and the nip roller based on the combined thickness of the bulk layer and the barrier film or sheet, which allows the nip to be adapted to the material at hand and reduces the risk of the rollers filling the perforations to an undesirable extent due to the distance not being adapted to the thickness of the material, thus further reducing the risk of contamination of the laminator.

[0021] This distance may be adjusted to be less than the combined thickness of the bulk layer and the barrier film or sheet.

[0022] The distance may be adjusted based on input provided by the user through the user interface, thus providing a user-friendly and reliable method for achieving a desired distance.

[0023] To further solve the above-mentioned object, a wet lamination station for laminating a barrier film or sheet to a bulk layer of perforated paper or paperboard or other cellulosic material is provided, the wet lamination station comprising a coating unit configured to coat the barrier film or sheet with a wet adhesive, and a lamination unit including a nip roller and a support roller, the wet lamination station further comprising a barrier film or sheet supply unit configured to continuously supply the barrier film or sheet through the lamination unit such that the uncoated side is in contact with the nip roller, a bulk layer supply unit configured to continuously supply the bulk layer through the lamination unit such that the bulk layer is in contact with the support roller, and an actuation means configured to urge the nip roller towards the support roller or to urge the support roller towards the nip roller.

[0024] The positioning of the support roller and nip rollers ensures that the wet adhesive is contained between the barrier film or sheet and the bulk layer, reducing the risk of contact with the rollers.

[0025] The outer circumferential surface of the nip roller may be formed of an elastomeric material, which can provide a more uniform pressure distribution within the nip.

[0026] The elastomeric material may have a Shore hardness of at least 90ShA, preferably at least 92ShA. A harder elastomeric material is less prone to filling the through holes in the base layer compared to a softer elastomeric material, as less pressure needs to be applied by the actuation means.

[0027] The wet lamination station may include a drive configured to drive the rotation of the support roller.

[0028] The actuation means may be hydraulically actuated, which is more resistant to being pushed out of engagement with the material to be laminated as the splice of material passes through, thus enabling a wet lamination process that is more robust against air entrapment between the base layer and the barrier film or sheet at the splice.

[0029] The wet lamination station may comprise an adjustment means for adjusting the distance between the support roller and the nip roller, which allows the nip to be adapted depending on the material and reduces the risk that the roller will fill the through-hole to an undesirable extent because the distance is not adapted to the thickness of the material, thus further reducing the risk of contamination of the lamination device by wet adhesive.

[0030] One of the support roller and the nip roller may be adjustably disposed within the support structure. The adjustment means may comprise at least one linear actuator. Each linear actuator may be connected to a moveable adjustment member arranged to engage the support roller or the nip roller for adjusting the position of the support roller or the nip roller relative to the support structure. In this manner, a user friendly and reliable method of achieving a desired distance between the support roller and the nip roller is provided.

[0031] Further objects, features, aspects and advantages of the present invention will become apparent from the following detailed description and drawings. [Means for solving the problem]

[0032] Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which: [Brief description of the drawings]

[0033] [Figure 1a] FIG. 2 is a perspective view of a package formed from the packaging material laminate. [Figure 1b] 1 is a schematic diagram of a wet lamination station and lamination method according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a perspective view of a lamination unit of a wet lamination station according to an embodiment of the present invention. [Diagram 3] FIG. 2 is a side view of a laminating unit according to an embodiment of the present invention; [Figure 4] 1A and 1B are a perspective view and a partial cross-sectional view of a laminating unit according to an embodiment of the present invention; [Diagram 5] FIG. 2 is a detailed view of a portion of a lamination unit according to an embodiment of the present invention. [Figure 6] 4 is a schematic diagram showing a part of a mechanism for adjusting the distance between rollers of the laminating unit. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0034] In Fig. 1a a packaging container P is shown. The packaging container P is manufactured from a packaging material as described herein. In particular the packaging material comprises a bulk layer covered with a barrier film or sheet. The packaging container comprises a pre-cut laminate hole PLH, for example forming a straw hole.

[0035] Referring to Figure 1b, a wet lamination station is shown. The wet lamination station 1 is for coating a bulk layer 5 with a barrier film or sheet 6, the laminated bulk layer 5 and barrier film or sheet 6 being subsequently used to form a packaging material.

[0036] The bulk layer 5 is provided with through holes 3, i.e. holes extending through the material sheet of the bulk layer. Each through hole 3 together with a part of the barrier film or sheet 6 extending across said through hole 3 may be intended to form part of the opening structure of the packaging container, for example in the form of a straw hole as shown in Figure 1a. The through holes 3 may be punched holes, for example pre-punched holes, which form for example a straw hole in the final packaging container.

[0037] The barrier film or sheet 6 may be an aluminium foil, a plastic film with a barrier coating, or a paper or cellulosic sheet with a barrier coating.

[0038] The barrier coating may comprise a polymer selected from the group consisting of vinyl alcohol polymers and copolymers, such as polymers selected from the group consisting of polyvinyl alcohol (PVOH) and ethylene vinyl alcohol (EVOH), starch, starch derivatives, nanofibril / microfibril cellulose (NFC / MFC), nanocrystalline cellulose (NCC), and blends of two or more thereof. Such polymers are dispersible or soluble in substantially aqueous compositions. Barrier dispersion coatings from such dispersions or solutions have a dry weight of 0.2 to 5 g / m2. 2 , for example 0.5 to 4 g / m 2 , for example 0.5 to 3.5 g / m 2 , for example 1 to 3 g / m 2 may be applied by dispersion or solution coating in an amount of

[0039] The barrier coating may alternatively or additionally comprise a material selected from metals, metal oxides, inorganic oxides and amorphous diamond-like carbon coatings. The vapor deposition coating is applied by physical vapor deposition (PVD) or chemical vapor deposition (CVD), such as plasma enhanced chemical vapor deposition (PECVD). More specifically, it may be selected from the group consisting of aluminum metallized coatings and aluminum oxide AlOx. Preferably, it is an aluminum metallized coating.

[0040] The wet lamination station includes a lamination unit (not shown in FIG. 1). The wet lamination station includes a nip roller 12 and a support roller 11. The nip roller 12 and the support roller 11 form a nip. The nip is configured to receive the bulk layer 5 and the barrier film or sheet 6. The support roller 11 may be a cooling or chill roller. The cooling or chill roller may be cooled by an internal water cooling device (not shown).

[0041] The bulk layer 5 and the barrier film or sheet 6 may have a combined thickness of 0.2 to 0.45 millimeters. The bulk layer 5 may constitute at least 80%, preferably at least 90%, of the combined thickness of the bulk layer 5 and the barrier film or sheet 6.

[0042] The wet lamination station 1 comprises a coating unit 16. The coating unit 16 is configured to coat the barrier film or sheet 6 with a wet adhesive 19. The wet adhesive is also referred to herein as adhesive.

[0043] The coating unit 16 is configured to apply a wet adhesive, which may be in the form of a dispersion or solution based on an aqueous acrylic polymer adhesion promoting composition, onto the barrier film or sheet 6. ... onto the barrier film or sheet 6. The coating unit 16 is configured to apply a wet adhesive, which may be in the form of a dispersion or solution based on an aqueous acrylic polymer adhesion promoting composition onto the barrier film or sheet 6. The coating unit 16 is configured to apply a wet adhesive, which may be in the form of a dispersion or solution based on an aqueous acrylic polymer adhesion promoting composition onto the barrier film or sheet 6. 2 Compared to extrusion lamination, which requires a quantity of polymer of 2-5 g / m2 of barrier film or sheet for sufficient adhesion, wet lamination requires 2-5 g / m2 of barrier film or sheet for sufficient adhesion. 2 Thus, the coating unit 16 only needs to apply 2-5 g / m2 of wet adhesive onto the barrier film or sheet. 2 The adhesive may be configured to apply a coating of wet adhesive.

[0044] To supply the barrier film or sheet 6 to the lamination unit, the wet lamination station 1 comprises a barrier film or sheet supply unit 24. The barrier film or sheet supply unit 24 is configured to continuously supply the barrier film or sheet 6 through the lamination unit 10. The barrier film or sheet 6 may be supplied as a continuous web. The barrier film or sheet supply unit 24 may be a reel configured to unwind a roll of the web of barrier film or sheet 6 and supply the web of barrier film or sheet 6 through the lamination unit.

[0045] To supply the bulk layer 5 to the lamination unit, the wet lamination station 1 comprises a bulk layer supply unit 13. The bulk layer supply unit 13 is configured to continuously supply the bulk layer 5 through the lamination unit 10. The bulk layer 5 may be supplied as a continuous web. The bulk layer supply unit 13 may be a reel configured to unwind a roll of the web of bulk layer and supply the web of bulk layer through the lamination unit.

[0046] As can be seen in Figure 1b, a barrier film or sheet 6 is fed by a barrier film or sheet feeding unit 24 through a nip formed between nip roller 12 and support roller 11. The barrier film or sheet 6 is fed to the nip via a coating unit 16 where the barrier film or sheet 6 is coated on one side with a wet adhesive 19. The barrier film or sheet feeding unit feeds the barrier film or sheet 6 such that an uncoated side of the barrier film or sheet 6 contacts nip roller 12. Thus, the coated side of said barrier film or sheet 6 may face support roller 11 at the nip.

[0047] The bulk layer 5 is fed to the nip by a bulk layer feed unit 13. The bulk layer feed unit 13 feeds the bulk layer to the nip such that the bulk layer contacts the support roller 11.

[0048] The bulk layer 5 and the barrier film or sheet 6 are fed through the nip, with the bulk layer 5 being adhered to the barrier film or sheet 6 by an adhesive. The bulk layer 5 and the barrier film or sheet 6 may be fed through the nip by a bulk layer supply unit 13 and a barrier film or sheet supply unit 24, respectively.

[0049] The pressure from the nip laminates the barrier film or sheet 6 to the bulk layer 5 to provide a laminate material that may be directed downstream of the nip to a wet lamination station dryer 91 to dry the wet adhesive 19.

[0050] In a typical lamination system, the materials contacting the nip roller 12 and the support roller 11 are such that the nip roller contacts the thicker or more stable layer and the support roller contacts the thinner sensitive layer such as a film or foil. However, in a typical lamination setup, as the bulk layer with the perforations and the thin barrier film or sheet are compressed together in the nip, there is a risk that the wet adhesive will come into contact with the nip roller. Since the nip roller is generally a softer material than the support roller, the nip roller may partially fill the perforations during compression and come into contact with the wet adhesive, which may cause wet adhesive contamination at the lamination station.

[0051] The above-described method and wet lamination station according to the present invention eliminates or reduces the risk of this type of contamination.

[0052] 2-4, a lamination unit of a wet lamination station is shown.

[0053] The laminating unit 10 constitutes a part of a wet laminating station. The laminating unit 10 includes a support roller 11 and a nip roller 12.

[0054] The support roller 11 may be a driven support roller 11. Thus, the wet lamination station may include a drive unit 30. The drive unit 30 is configured to drive the rotation of the support roller 11. As illustrated in Figures 2-4, the drive unit 30 may be configured within the lamination unit 10.

[0055] To generate the pressure required for lamination, the bulk layer 5 and the barrier film or sheet are pressed together between a nip roller 12 and a support roller. The area subjected to pressure between the rollers is commonly called the nip. The extent of the nip in the longitudinal direction is determined on the one hand by the force between the support roller and the nip roller and on the other hand by the elasticity of the material between the nip roller and the support roller.

[0056] To maintain sufficient pressure in the nip, the wet lamination station may comprise an actuating means 60 configured to press the nip roller 12 towards the support roller 11. As depicted in Figures 2-4, the actuating means 60 may be configured in the lamination unit 10. The actuating means 60 may be adapted to press the nip roller 12 towards the support roller 11 against the barrier film or sheet 6. The actuating means provides a pressing force from the nip roller 12 to the coated barrier film or sheet and the bulk layer while the bulk layer and the coated barrier film or sheet are fed through the nip.

[0057] The actuation means 60 may be hydraulically or pneumatically actuated. Advantageously, the actuation means are hydraulic.

[0058] The actuation means 60 may comprise an actuator 61 for pressing the nip roller 12 towards the support roller. The actuator 61 may be configured to exert a pressing force on the barrier film or sheet, the bulk layer and the support roller 11 via the nip roller 12. The actuator 61 may be configured to exert a biasing force on the nip roller to maintain the nip roller at a set distance relative to the support roller. The actuator may be hydraulically actuated and thus may be a hydraulic actuator.

[0059] The actuator 61 may be connected to the nip roller 12 and the actuation means may comprise first and second actuators connected to first and second lateral ends of the nip roller 12 respectively.

[0060] Alternatively or additionally, the nip roller 12 may be of the shoe roller type. Such a nip roller may comprise a pressure web and a pressure bar connected to an actuator. The pressure bar can be actuated by the actuator. During actuation, the pressure web runs at the same speed as the support roller, the web of the base layer and the barrier film or sheet. The pressure is generated by the pressure bar pressing the pressure web against the support roller. The pressure bar is stationary with respect to the support roller. The pressure web is arranged to slide against the front face of the bar.

[0061] The outer circumferential surface of the nip roller 12 may be an elastomeric material. The elastomeric material may be rubber. Preferably, the elastomeric material has a Shore hardness of at least 90ShA, more preferably at least 92ShA. Conventional nip rollers generally utilize a relatively soft rubber material. A soft material fills the through holes to a greater extent than a harder material. Furthermore, a soft material requires a higher pressure from the actuating means to ensure compression of the material at the nip, which further enhances the filling effect. A hard rubber material not only provides a sufficient pressure distribution, but also has a relatively low tendency to fill the through holes.

[0062] As one skilled in the art will appreciate, Shore hardness is typically measured by a Shore durometer, which is an instrument used to measure the hardness of materials such as polymers, elastomers, rubbers, etc. Shore hardness is measured by the depth of indentation caused by a predefined force / pressure applied by the durometer. As used herein, ShA refers to the Shore A hardness scale, which is commonly utilized to measure the hardness of relatively soft and flexible elastomeric materials.

[0063] Nip roller 12 may have a metal core encased in an elastomeric coating that forms the outer circumferential surface of nip roller 12. The metal core may be made of aluminum or steel.

[0064] The support roller has an outer peripheral surface made of a rigid material such that the surface of the nip roller is softer than the surface of the support roller. Preferably, the material of the surface of the support roller is metallic, for example steel, optionally coated with chromium.

[0065] The distance or gap between the nip roller 12 and the support roller 11 may be adjustable to accommodate different thicknesses of the barrier film or sheet and the bulk layer. The wet lamination station may comprise an adjustment means for adjusting this distance. Advantageously, the adjustment means may be configured within the lamination unit. The adjustment means make it possible to adjust the distance between the support roller 11 and the nip roller 12 based on the combined thickness of the bulk layer 5 and the barrier film or sheet 6, i.e. the adjustment means makes it possible to adjust the nip or nip distance. To ensure proper compression, preferably the distance is adjusted such that the distance between the support roller 11 and the nip roller 12 is smaller than the combined thickness of the bulk layer and the barrier film or sheet.

[0066] Therefore, the distance between the nip roller 12 and the support roller 11 is preferably smaller than the combined thickness of the bulk layer 5 and the barrier film or sheet 6. Preferably, the distance between the nip roller 12 and the support roller is 60-70% of the combined thickness of the bulk layer 5 and the barrier film or sheet 6. For example, when the total thickness of the bulk layer 5 and the barrier film or sheet 6 is 0.45 mm, the distance is preferably 0.3 mm.

[0067] 2, the wet lamination station may further include a controller 82. The controller 82 may be operatively connected to the drive unit 30. The controller 82 may be configured to control the operation of the drive unit 30.

[0068] The controller 82 may be operatively connected to the adjusting means 50. The controller 82 may be configured to control operation of the adjusting means 50 to adjust the distance between the nip roller 12 and the support roller 11. Thus, the controller 82 may be configured to control the adjusting means 50 to adjust the distance between the support roller 11 and the nip roller 12 based on user input received by the user interface 81.

[0069] The wet lamination station may further include a user interface 81 to allow a user to interface with the controller 82 and the lamination station. The user interface 81 may be a graphical user interface (GUI). The user interface 81 is operatively connected to the controller 82. The user interface 81 may be configured to allow a user to vary the distance between the nip roller 12 and the support roller 11.

[0070] A user may provide data to the controller 82 via the user interface 81. The data may include data regarding the combined thickness of the bulk layer and the barrier film or sheet. In response to receiving the data, the controller 82 is configured to adjust the distance between the nip roller 12 and the support roller 11. Preferably, the distance is adjusted to be less than the combined thickness.

[0071] Advantageously, the user input, i.e., provided via the user interface 81, may include one or both of the Shore hardness of the outer peripheral surface of the nip roller and the combined thickness of the barrier film or sheet and the bulk layer. The combined thickness of the barrier film or sheet and the bulk layer may be provided as a single value or may be provided as separate values ​​for each of the bulk layer and the barrier film or sheet. The Shore hardness of the outer peripheral surface may be provided as a Shore hardness value or may be provided as an identification value associated with a nip roller type having a predefined Shore hardness value.

[0072] Thus, a user may provide instructions to the controller 82 via the user interface 81 by providing user input consisting of either or both of the Shore hardness of the outer circumferential surface of the nip roller and the combined thickness of the barrier film or sheet and the bulk layer before lamination takes place. In response to the user data, the controller 82 prompts the actuation means 50 to set the distance between the nip roller 12 and the support roller 11, thereby adjusting the distance between said nip roller 12 and the support roller 11.

[0073] Alternatively or additionally, the aforementioned thicknesses may be provided by means of the controller 82 acquiring external or sensor data from an optical sensor configured to measure the thickness of the bulk layer and the barrier film or sheet.

[0074] 6 shows the adjustment means 50 diagrammatically. One of the support roller 11 and the nip roller 12 is adjustably arranged in a support structure 70. The support structure 70 may comprise rails 78. A support bearing 77 of the support roller 11 or a support bearing 79 of the nip roller 12 may be arranged on the rails 78 to allow movement and adjustment of the nip roller or the support roller. In the example shown, the nip roller 12 is movable relative to the support roller 11 to adjust the distance between the nip roller and the support roller. Thus, the support bearing 79 of the nip roller 12 is arranged on the rails 78.

[0075] Advantageously, the nip rollers are further arranged to be biased against the movable adjustment members 58, 59 by actuation means (not depicted in FIG. 6). The movable adjustment members 58, 59 may thus be arranged to constitute stops for the actuation of the nip roller 12 relative to the support roller 11.

[0076] Preferably, the nip roller 12 and the support roller 11 may be provided with a support bearing at each of their lateral ends. The support structure may include first and second rails 78 that adjustably receive first and second support bearings of the nip roller or the support roller.

[0077] The adjustment means 50 may comprise at least one actuator 51. The actuator 51 may be a linear actuator, such as a linear servo motor. The linear actuator 51 may be connected to movable adjustment members 58, 59. The adjustment members are arranged to engage the support roller 11 or the nip roller 12 to adjust the position of the support roller 11 or the nip roller 12 relative to the support structure 70.

[0078] The linear actuator 51 is coupled to the movable adjustment members 58, 59 by an arm mechanism 55. The arm mechanism 55 is connected to at least one of the movable adjustment members 58, 59. The movable adjustment members 58, 59 are disposed on a threaded shaft 53. The threaded shaft 53 is connected to the arm mechanism 55 such that the arm mechanism 55 is disposed to rotate the threaded shaft in response to actuation by the linear actuator 51, thereby moving the movable adjustment members 58, 59 and facilitating adjustment of the distance between the nip roller 12 and the support roller 11. In this manner, the arm mechanism 55 may be disposed to convert linear motion of the linear actuator 51 into rotational motion of the threaded shaft 53.

[0079] 6, the movable adjustment members 58, 59 may be disposed between a support bearing 79 of the nip roller and a support bearing 77 of the support roller 12. Rotation of the screw shaft 53 moves the movable adjustment members and engages with the support bearing 79 of the nip roller 12, forcing the nip roller 12 to move relative to the rail 78.

[0080] A pair of movable adjustment members 58, 59 may be disposed on the threaded shaft 53 such that rotation of the threaded shaft causes the adjustment members to move towards or away from each other along the threaded shaft 53.

[0081] The movable adjustment members 58, 59 may be arranged in a guide arrangement arranged to urge the movable adjustment members 58, 59 in a direction away from or extending towards the adjustable roller (nip roller in the illustrated example) in response to rotation of the threaded shaft 53, thereby causing movement of the adjustable roller. The guide arrangement may comprise guide pins 41, 42 guided in tracks 43, 44. The tracks may extend obliquely to the threaded shaft 53 in a plane perpendicular to the axial direction of the nip roller and the support roller. In the illustrated example, each adjustment member of the pair of movable adjustment members 58, 59 comprises a track 43, 44 which engages with a fixed guide pin 41, 42. Upon movement of the adjustment members along the threaded shaft, the obliquely oriented tracks also urge the adjustment members in a direction extending towards or away from the nip roller 12 due to engagement between the tracks 41, 42 and the guide pins 43, 44.

[0082] 6, rotation of the threaded shaft in a first direction causes the movable adjustment members 58, 59 to move toward each other and toward the nip roller 12, thereby engaging the nip roller 12 and urging it away from the support roller 11. Rotation of the threaded shaft in a second, opposite direction causes the movable adjustment members 58, 59 to move away from each other and away from the nip roller 12, thereby engaging the nip roller 12 and urging it toward the support roller.

[0083] Preferably, the adjustment means comprises two linear actuators 51. The first linear actuator may be connected to a first arm mechanism which in turn is connected to a movable adjustment member arranged in a first transverse plane of the nip roller or support roller for adjusting the nip roller or support roller. Similarly, the second linear actuator may be connected to a second arm mechanism which in turn is connected to a movable adjustment member arranged in a second transverse plane of the nip roller or support roller for adjusting the nip roller or support roller.

[0084] As one skilled in the art will appreciate, adjustment means 50 may comprise any conventional means for moving the rollers relative to one another.

[0085] From the foregoing description, while various embodiments of the present invention have been described and illustrated, the invention is not limited thereto and may be embodied in other ways within the scope of the subject matter defined in the following claims.

Claims

1. A method for laminating a barrier film or sheet (6) to a bulk layer (5) of paper or paperboard or other cellulosic material, said bulk layer (5) comprising perforations (3), the method comprising: coating said barrier film or sheet (6) with a wet adhesive (19); The coated barrier film or sheet is supplied to a nip formed between a nip roller (12) and a support roller (11) so that the uncoated surface of the barrier film or sheet (6) contacts the nip roller (12), and the surface material of the nip roller (12) is softer than the surface material of the support roller (11); feeding the bulk layer (5) into the nip portion so that the bulk layer (5) contacts the support roller (11); feeding the bulk layer (5) and the coated barrier film or sheet through the nip, thereby adhering the bulk layer (5) to the barrier film or sheet (6) by the adhesive (19); method.

2. The bulk layer (5) is provided as a continuous web, The method of claim 1.

3. The barrier film or sheet (6) is provided as a continuous web, 3. The method according to claim 1 or 2.

4. The barrier film or sheet (6) is an aluminum foil, a barrier-coated plastic film, or a barrier-coated paper or cellulose-based sheet. The method of claim 1.

5. The bulk layer (5) and the barrier film or sheet (6) have a combined thickness of 0.2 to 0.45 millimeters; The method of claim 1.

6. further comprising adjusting the distance between the support roller (11) and the nip roller (12) based on the combined thickness of the bulk layer (5) and the barrier film or sheet (6). The method of claim 1.

7. adjusting the distance between the support roller (11) and the nip roller (12) so that the distance is smaller than the total thickness of the bulk layer (5) and the barrier film or sheet (6); The method of claim 6.

8. adjusting said distance based on input provided by a user using a user interface (81); The method of claim 6.

9. A wet lamination station (1) for laminating a barrier film or sheet (6) to a bulk layer (5) of paper or paperboard or other cellulosic material, the bulk layer (5) being provided with through holes (3), the wet lamination station (1) comprising: a coating unit (16) configured to coat the barrier film or sheet (6) with a wet adhesive (19); A laminating unit (10) including a nip roller (12) and a support roller (11), wherein the surface material of the nip roller (12) is softer than the surface material of the support roller (11), a barrier film or sheet supply unit (24) configured to continuously supply the barrier film or sheet (6) through the laminating unit (10); and the laminating unit (10) and the barrier film or sheet supply unit (24) are mutually arranged so that an uncoated side of the barrier film or sheet (6) contacts the nip roller (12); a bulk layer supply unit (13) configured to continuously supply the bulk layer (5) through the laminating unit (10); and the bulk layer supply unit (13) and the laminating unit (10) are mutually arranged so that the bulk layer (5) contacts the support roller (11); an actuation means (60) configured to press the nip roller (12) towards the support roller (11) or to press the support roller (11) towards the nip roller (12); A wet lamination station (1) comprising:

10. The outer circumferential surface of the nip roller (12) is made of an elastomeric material. A wet lamination station (1) according to claim 9.

11. the elastomeric material has a Shore hardness of at least 90 ShA; A wet lamination station (1) according to claim 10.

12. a drive unit (30) configured to drive the rotation of the support roller (11); A wet lamination station (1) according to claim 9.

13. The actuating means (60) is hydraulic. A wet lamination station (1) according to claim 9.

14. Further provided is an adjusting means (50) for adjusting the distance between the support roller (11) and the nip roller (12). A wet lamination station (1) according to claim 9.

15. one of the support roller (11) and the nip roller (12) is adjustably disposed within a support structure (70), and the adjustment means (50) comprises at least one linear actuator (51), each linear actuator (51) connected to a movable adjustment member (58, 59) arranged to engage the support roller (11) or the nip roller (12) to adjust the position of the support roller (11) or the nip roller (12) relative to the support structure (70); A wet lamination station (1) according to claim 14.

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