Method of manufacturing web of laminated packaging material

Abstract

A continuous in-line process for manufacturing a web of laminated packaging material comprising: inkjet printing a decorative layer on a cardboard layer; drying the decorative layer by exposing the paperboard layer to infrared radiation and a flow of hot air; and laminating at least another layer onto the printed and creased paperboard layer.

Description

Technical Field

[0001] The invention relates to a method for producing a roll of laminated packaging material for liquid food packaging containers, a conversion unit and a roll of laminated packaging material. Background Art

[0002] Disposable packaging containers for liquid foods are usually made of laminated packaging materials. Laminated packaging materials are produced in continuous roll form for use in roll-fed filling machines or cut into individual blanks for use in blank-fed packaging machines.

[0003] Laminated packaging materials are produced using a converting procedure in which multiple materials are joined and processed to form a ready-to-use laminated packaging material roll.

[0004] In the converting process, the paperboard layer forming the core layer of the laminated packaging material can be digitally printed on the outside (i.e., the side that is the outside of the laminated packaging material), for example by ink-jet printing, dried and laminated between the sealable layers. Optionally, the paperboard layer can be pre-coated before printing, and / or already bonded to one or more layers.

[0005] Throughout the converting process it is important to maintain the desired moisture levels in the paperboard plies; not only to ensure optimal performance of the various converting processes, but also to control the desired characteristics of the final packaging container.

[0006] After digital printing with water-based inks (e.g. pigment-based water-based inks), it is recommended to use infrared radiation technology to dry the paperboard layers. Although this technology allows for rapid drying, it has been observed that more powerful drying also dries the paperboard layers, i.e. the moisture content of the paperboard layers decreases. The moisture loss in a certain area of ​​the paperboard layer will vary with the printed design, especially in relation to the color printed on that area. For liquid food packaging materials, the printed inks may not be covered by a coating (e.g. varnish) after printing. They are laminated by, for example, a polymer layer to protect the printing after drying. Therefore, when drying the ink-printed areas, it may be difficult to avoid overdrying, especially on the unprinted surfaces. Therefore, it is difficult to provide even drying. Low paperboard moisture content can have a negative impact on the converting process, especially when the paperboard layers are creased before lamination. If the moisture content of the paperboard layers decreases to a certain level, the paperboard layers will crack instead of bending, which may reduce the quality of the final laminated packaging material roll and the packaging container made from the laminated packaging material roll. On the other hand, if the printed pattern is not dried sufficiently, it may cause defects related to the wear or staining of the printed color pattern of the decorative layer. Therefore, there is a need in the art for improvements in the manufacture of laminated packaging material webs, particularly with respect to ink drying. Summary of the invention

[0007] It is an object of the present invention to at least partially overcome one or more of the above limitations of the prior art.In particular, it is an object of the present invention to provide a reliable and efficient method of manufacturing a roll of laminated packaging material while maintaining the moisture level of the paperboard layer.

[0008] To solve these objects, a continuous in-line method for manufacturing a roll of laminated packaging material is provided. The method comprises inkjet printing a decorative layer on a paperboard layer, drying the decorative layer by exposing the paperboard layer to infrared radiation and a stream of hot air, and laminating at least one further layer to the printed paperboard layer.

[0009] The most likely paperboard layer is a paperboard layer used for liquid food packaging. In other words, the most likely laminated packaging material roll is a laminated liquid food packaging material roll, or liquid packaging board.

[0010] Paperboard used in liquid packaging boards usually has one side, called the top side, optimized for printing, and the other side, the back side, has water-repellent properties to resist water absorption from the external environment. Therefore, paperboard is not suitable for wetting from the back side if necessary, such as over-drying after drying. For paperboard printed with water-based inks, it is also not possible to wet it from the top side after drying to avoid problems with dissolving the printed ink. Rewetting is also not preferred for liquid food packaging material production due to food safety requirements.

[0011] In one embodiment, using a CMYK (cyan, magenta, yellow and black) combination, it is possible to achieve over 200% TAC (total area coverage) in the print. These prints cannot be dried with infrared alone, otherwise the black areas will overheat. This can cause areas of the board to be over-dried and result in uneven drying and uneven moisture content of the board.

[0012] In one embodiment, the ink may contain not only water but also some organic volatiles. The combination of water and volatile organic content may result in a higher boiling point to dry the ink. Therefore, if only IR is used, higher drying energy may be required, which may result in over-drying of the paperboard. The advantage of this method is that the moisture content of the paperboard layer is substantially maintained. The moisture content of the paperboard layer may be, for example, 4% or more, between 5% and 10%, or preferably between 5% and 8.5%.

[0013] The method may also include flexographic printing or other printing techniques, so the decorative layer can be obtained only by inkjet printing or by a hybrid method combining two or more printing techniques. In other words, the decorative layer can be inkjet printed and flexographic printed.

[0014] The method may further comprise applying a printed substrate layer to the paperboard layer prior to inkjet printing the decorative layer.

[0015] Applying the printed substrate layer may include, for example, coating the paperboard layer with a pre-coating layer, or priming the paperboard layer by plasma treatment to form a printed substrate layer on the surface of the paperboard layer, or applying a surface conditioning agent to change the topology or properties related to electrostatics. The printed substrate layers may completely cover the paperboard layer, may only cover the area to be covered by the decorative layer, or they may cover a medium-sized area of ​​the paperboard layer.

[0016] In one embodiment, the present invention may be more beneficial when the paperboard layer needs to be dried as quickly as possible. For example, if the paperboard has a printed substrate layer that can prevent ink solvents (most likely water-based inks) from migrating through the paperboard, then it may be more beneficial to dry as quickly as possible without overdrying the packaging material. In other words, if the paperboard has a printed substrate layer that can keep almost all of the ink solvents (most likely water-based inks) printed on the printed substrate layer, then it may be more beneficial to dry as quickly as possible without overdrying the packaging material.

[0017] In one embodiment, the paperboard may include a printable coating, such as a white pigment and a clay coating as a printing substrate layer. This clay coating will form a waterproof surface on the paperboard layer, which means that the ink solvent cannot migrate and be absorbed into the paperboard fiber layer. This requires increased drying capacity because it is very important to dry the ink quickly before further downstream processing.

[0018] In one embodiment, the printing substrate layer may be a clay coating which is also primed upstream of inkjet printing.

[0019] In one embodiment, the printed substrate layer can be provided on the paperboard layer before inkjet printing at the same production site; and / or the application of the printed substrate layer is not effected before this, for example at another production site, i.e. at the site where inkjet printing is effected.

[0020] In one embodiment, the method further comprises providing the paperboard layer with a crease line pattern.As an example, the crease line pattern may repeat in the machine direction.

[0021] In a possible embodiment, the crease lines can be arranged upstream and / or downstream of the inkjet printing.

[0022] Preferably, the paperboard layer has a thickness of at least 90 μm, and / or a weight of at least 65 gsm.

[0023] Prior to inkjet printing and / or application of the printed substrate layer, the paperboard layer may be an uncoated paperboard, or a paperboard laminated with one or more layers, such as polymer layers.

[0024] The paperboard layers may be conveyed in the machine direction at a substantially constant speed, for example 200 m / min or faster.

[0025] In one embodiment, drying the decorative layer further comprises controlling the moisture content of the paperboard layer by adjusting the ratio between the infrared radiation and the hot air flow. This is beneficial because it allows precise control of the decorative layer and the paperboard layer and helps maintain moisture content in the shortest drying time.

[0026] Drying the decorative layer may also include controlling the moisture content of the paperboard layer by adjusting the temperature of the hot air stream.

[0027] The slot speed of the hot air dryer may be 45-85 m / s and the air temperature may be 55-80° C. The humidity in the hot air supplied by the hot air dryer for drying the decorative layer may be controlled, preferably online.

[0028] In one embodiment, the temperature of the paperboard can be controlled, preferably in-line. If the printed and laminated packaging material has more than one lane, each lane to be fed to the liquid food filling machine can be controlled individually during printing and / or during and / or downstream of drying to avoid temperature gradients.

[0029] In one embodiment, controlling the moisture level includes determining the drying time and determining the ratio between the infrared radiation and the hot air flow by minimizing the amount of infrared radiation while still ensuring complete drying within the drying time. In this way, problems associated with moisture loss in the paperboard layers are minimized.

[0030] The decorative layer may be dried by exposing a region of the paperboard layer to infrared radiation and then exposing the same region of the paperboard layer to a hot air stream. For example, a region of the paperboard layer may be exposed to infrared radiation until a determined moisture level of the paperboard is reached, and the remaining drying of the decorative layer may be performed by the hot air stream. In this way, the time efficiency of the method is ensured, while still ensuring the desired moisture content in the paperboard layer.

[0031] The infrared radiation may have a spectral emission within 0.4 μm-4 μm. In other words, the infrared radiation may be near infrared radiation, short wave infrared radiation, mid wave infrared radiation, or radiation in multiple infrared regions.

[0032] In one embodiment, the printing and drying process of the laminated packaging material can be carried out roll-to-roll, which means that the paperboard web can be unwound upstream of printing and reeled downstream after lamination with another layer. Rolling up the laminated packaging material will cause friction and tensile forces on the printed matter, so the printed matter should be properly dried without causing excessive drying of the paperboard. In addition, if crease line patterns are formed on the laminated packaging material, these patterns should resist friction and tensile forces with the help of the moisture content maintained in the paperboard. The rolled-up packaging material web can be transported to the next step in a convenient manner, such as filling the packaging material web with a product (possibly a liquid food).

[0033] The order of the method steps may not be a limitation of the present invention. A skilled person may use various orders of the above steps as long as the advantage of substantially maintaining the moisture content of the paperboard layer by infrared drying and hot air drying can be achieved technically.

[0034] Another aspect of the invention relates to a conversion unit configured to manufacture a web of laminated packaging material.The conversion unit may be configured to perform the continuous in-line method for manufacturing a web of laminated packaging material as described herein, thus meaning all aspects related to the method.

[0035] The converting unit comprises an inkjet printer configured to print a decorative layer on a paperboard layer, a drying station configured to dry the decorative layer by exposing the paperboard layer to infrared radiation and a hot air flow, and at least one laminating station configured to laminate at least one further layer onto the printed paperboard layer.

[0036] In one embodiment, the converting unit may include a creasing station configured to provide a crease line pattern to the paperboard layer.

[0037] The included stations can be arranged in the following order, from upstream to downstream: inkjet printer, drying station, creasing station, laminating station.

[0038] It is also possible to place a creasing station upstream of the inkjet printer; or to arrange multiple creasing stations both downstream and upstream of the inkjet printer; or to have a combined unit for inkjet printer and creasing station, which allows creasing before and / or after printing.

[0039] The drying station may comprise a hot air dryer different from the infrared dryer, and the hot air dryer may be arranged downstream of the infrared dryer. In this way, the time efficiency of the method is ensured while minimizing moisture loss in the paperboard layer and / or ensuring a desired moisture content level in the paperboard layer.

[0040] In one embodiment, the conversion unit further comprises a feed unit configured to continuously advance the paperboard layers at a constant speed.

[0041] The conversion unit may also include a printing substrate station configured to apply a printing substrate layer to prepare the paperboard layer prior to printing by the inkjet printer. As described above, applying the printing substrate layer may include coating the paperboard layer with a pre-coating layer (e.g., a clay coating or a primed clay coating), or priming the paperboard layer by plasma treatment to form a printing substrate layer on the surface of the paperboard layer, or applying a surface conditioner or otherwise changing the surface characteristics of the paperboard layer. The conversion unit may also include a second drying station for drying the printing substrate layer.

[0042] The process sequence of each station is not limited to the present invention. A person skilled in the art can use various sequences of the above stations as long as the advantage of substantially maintaining the moisture content of the paperboard layer by infrared drying and hot air drying can be achieved technically.

[0043] In one embodiment, the conversion unit can be a roll-to-roll unit, which means that the paperboard web can be unwound upstream of printing and reeled downstream after lamination with another layer. The rolling of the laminated packaging material will cause friction and tensile forces on the printed matter, so the printed matter should be properly dried without causing excessive drying of the paperboard. In addition, if crease line patterns are formed on the laminated packaging material, these patterns should resist friction and tensile forces with the help of the moisture content maintained in the paperboard. The rolled-up packaging material web can be conveniently transported to the next step, such as filling the packaging material web with products, which may be liquid food.

[0044] Another aspect of the invention relates to a laminated packaging material roll. The laminated packaging material roll can be obtained from a conversion unit and / or by the method steps described herein. The laminated packaging material roll comprises a paperboard layer and an inkjet printed decorative layer, and at least one further layer laminated to the paperboard layer. The moisture content of the paperboard layer is 4% or more.

[0045] The moisture content of the paperboard layer may be between 5% and 10%. More preferably, the moisture content may be between 5% and 8.5%.

[0046] For example, after inkjet printing the decorative layer, the moisture content of the paperboard layer may be between 6% and 8.5%, and in the final laminated packaging material web, the moisture content of the paperboard layer may be essentially the same or slightly lower. This means that the paperboard layer has not suffered any significant moisture loss, at least not to an extent that would result in any major defects in the laminated packaging material web.

[0047] The laminated packaging material may have a crease line pattern, and, for example, the crease line pattern may repeat cyclically in the machine direction.

[0048] If not stated to the contrary above or below, all embodiments of all aspects of the invention can be combined and are applicable to each other.

[0049] Other objects, features, aspects and advantages of the present invention will become apparent from the following detailed description and the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Embodiments of the present invention will now be described by way of example with reference to the accompanying drawings, in which:

[0051] Figure 1 is a flow chart of a method for manufacturing a laminated packaging material roll according to an embodiment.

[0052] Figure 2 is a cross-sectional view of a roll of a laminated packaging material according to an embodiment.

[0053] Figure 3 is a schematic diagram of a conversion unit according to an embodiment.

[0054] Figure 4 is a schematic diagram of a drying station according to an embodiment. DETAILED DESCRIPTION

[0055] refer to Figure 1 , shows an embodiment of a continuous in-line method for manufacturing a laminated packaging material web 100. The method includes inkjet printing S20 on a paperboard layer 130 to form a decorative layer 150. The paperboard layer 130 may include paper, paperboard or other cellulose-based materials. Inkjet printing is a type of digital printing or computer printing. During inkjet printing, a digital image is reconstructed by ejecting ink droplets onto a substrate, such as a paperboard layer 130 or a printed substrate layer 140, which will be discussed further herein. The ink used may include a solvent and a color pigment or dye. The solvent may include water and a volatile organic compound, such as ethylene glycol. The method may also include other printing techniques, such as flexographic printing, and therefore, the decorative layer 150 may be obtained only by inkjet printing S20, or by a hybrid method combining two or more printing techniques. In other words, the decorative layer 150 may be printed by inkjet printing and flexographic printing. The ink used for inkjet printing S20 may contain a higher solvent to pigment ratio than the ink used for flexographic printing. For example, the inkjet ink may contain about 4 times more water content than the flexographic printing ink. Furthermore, compared to flexographic printing, inkjet printing places several times more total amount of ink on the paperboard layer 130. Therefore, providing a fast drying process that does not reduce the moisture content of the paperboard layer 130 is even more important for inkjet printing.

[0056] The method further comprises drying S30 the decorative layer 150 by exposing the paperboard layer 130 to infrared radiation IR and a hot air flow HA. Infrared drying is an indirect drying method that does not rely on an intermediate agent such as air or water. Instead, infrared radiation (hereinafter referred to as IR) is radiated onto the decorative layer 150, to the extent that it will be absorbed by the molecules in the ink, thereby causing the solvent of the ink to evaporate from the layer 150. The intensity of the IR affects the level of transmission through the decorative layer 150 and can be adjusted. By including the drying step S30 of IR, a more reliable process can be ensured, which is not affected by the air boundary layer. Infrared drying further promotes a more time-saving process because the energy transfer process is very efficient. The rapid removal of solvent from the ink can further form a brighter and more colorful decorative layer 150.

[0057] The drying process can be controlled by selecting the wavelength, intensity and exposure time of the infrared radiation. Ideally, the infrared radiation should be selected so that the minimum amount of energy is transmitted to the paperboard layer 130 and absorbed by its water molecules, thereby reducing the moisture loss of the paperboard layer 130. However, this alone is not sufficient to maintain the desired moisture content of the paperboard.

[0058] Before further method steps for manufacturing the laminated packaging material web 100 are performed, it is essential to dry the decorative layer 150, at least to avoid defects due to wear or soiling. However, drying processes that rely solely on IR may suffer from disadvantages related to reduced moisture content in the printed paperboard layer 130. The high radiation intensity passing through the layers 130, 150 removes moisture not only from the ink of the decorative layer 150, but also from the cellulose-based paperboard layer 130 and may lead to various problems related to the performance of the laminated packaging material web 100. The laminated packaging material web 100 including the paperboard layer 130 with reduced moisture content may suffer from problems related to cracks (especially in the area where multiple fold lines intersect) and delamination of the laminated packaging material 100 and the integrity of the final packaging container. In addition, drying processes based solely on IR may be energy consuming and require high equipment costs. On the other hand, drying the decorative layer 150 using only hot air may be very time consuming and may lead to unreliable product performance.

[0059] Hot air drying is a simple and inexpensive technology where the ambient air is heated and the heat is transferred from the hot air stream to the printed ink by convection and the evaporated solvent in the ink is also transported into the air by convection. Using ambient air means that the drying results will be unpredictable and will vary depending on current weather conditions. Drying processes based solely on hot air are inefficient and time consuming and will significantly reduce the yield of the manufacturing process. Figure 1 In the illustrated method, the decoration layer 150 is dried S30 using a combination of IR and hot air.

[0060] The drying step S30 of the method may further include controlling the moisture content of the paperboard layer 130 by adjusting the ratio between IR and the hot air flow HA. Alternatively or additionally, drying S30 the decorative layer 150 may further include the step of controlling the moisture content of the paperboard layer 130 by adjusting the temperature of the hot air flow HA. In other words, the moisture content of the paperboard layer 130 may be controlled by adjusting the power, spectral emission, radiation intensity or exposure time of the IR and / or by adjusting the flow rate or temperature of the hot air. Controlling the moisture content may include determining a required drying time and determining the ratio between the infrared radiation IR and the hot air flow HA by minimizing the amount of infrared radiation IR while still ensuring complete drying within the required drying time. The required drying time may be defined as the total time that the paperboard layer 130 is arranged in a certain part of the production line, such as the drying station 230 or the part between the inkjet printing position and other converting equipment arranged downstream of the drying station.

[0061] The required drying time therefore depends on the operating speed of the conversion unit, and on the distances between the different stations of the conversion unit. Preferred conversion speeds are 200 m / min or higher.

[0062] The drying S30 of the decorative layer 150 may be performed by exposing a region of the paperboard layer 130 to infrared radiation IR and then exposing the same region of the paperboard layer 130 to the hot air flow HA. Alternatively, a first region of the paperboard layer 130 may be first exposed to IR and then a second region of the paperboard layer 130 (larger than the first region and at least partially including the first region) may be exposed to the hot air flow HA. This means that IR radiation may be provided only locally to certain regions of the decorative layer 150.

[0063] The method may include additional printing substrate layer application, printing and / or drying steps. For example, a surface treatment may be applied to the paperboard layer 130, which may then be printed using flexographic printing and dried by exposing the printed area to infrared radiation IR and / or hot air HA. Subsequently, a printing substrate layer 140 may be applied S10 to the paperboard layer 130, and the printing substrate layer 140 may be dried by IR and / or hot air HA. Then, a decorative layer 140 may be inkjet printed S20 on the printing substrate layer 140, and dried S30 by exposing the paperboard layer 130 to infrared radiation IR and a hot air flow HA. The paperboard layer 130 may be further printed using flexographic printing and then dried again.

[0064] like Figure 1As shown, the method also includes providing S40 a crease line pattern for the paperboard layer 130. The crease line pattern facilitates the formation of a packaging container from a laminated packaging material web 100 (not shown). The crease line pattern may be repeated in the machine direction. The machine direction may be defined as a direction parallel to the movement of the paperboard layer 130 through a manufacturing device (e.g., a conversion unit 200), or a circumferential direction of a paper roll for providing the paperboard layer 130. The laminated packaging material web 100 may have a machine direction and a transverse direction, the transverse direction being defined as a direction perpendicular to the machine direction. The dimension of the laminated packaging material web in the machine direction may be significantly greater than the dimension in the transverse direction. During the method, the paperboard layer 130 may be conveyed at a substantially constant speed along the machine direction as defined above. Figure 3 An example path of paperboard layer 130 through converting unit 200 is shown as a continuous line with arrows pointing in the machine direction.

[0065] The method further comprises laminating S50 at least one further layer 110 , 120 , 160 onto the printed and creased paperboard layer 130 . Figure 2 A cross section of an example of a laminated packaging material web is shown, the laminated packaging material web comprising a paperboard layer 130, a decorative layer 150 and at least another layer 110, 120, 160. The laminated packaging material web 100 shown in the figure comprises two sealable layers 110, 160, which are arranged on the outside of the laminated packaging material web 100 (topmost in the figure) to constitute the outside or exterior of the packaging container formed by the laminated packaging material web 100, and the inside of the laminated packaging material web 100 (bottommost in the figure) to be in direct contact with the filled food in the packaging container. The sealable layers 110, 160 are preferably liquid-tight. The sealing layers 110, 160 can be heat-sealed or include thermoplastic materials. Figure 2 Further shown is a barrier layer 120, which is laminated to the paperboard layer 130, preferably on the inside, as described above. The barrier layer 120 may include any barrier material suitable for maintaining a food-safe environment for the packaged liquid food product. This includes metals (e.g., aluminum foil), polymeric materials (e.g., ethylene vinyl alcohol copolymer, EVOH or polyamide, PA), polysaccharides (e.g., starch or fibrous or crystalline cellulose), polymer-based film substrates with a barrier coating; the barrier coating is selected from metals, metal oxides, inorganic oxides, other inorganic compounds, or carbon-based coatings (e.g., amorphous diamond-like carbon DLC coatings). The barrier layer 120 may be a cellulose-based material and / or a composite or multi-layer coating material, for example, including a non-metallic material (e.g., plastic, paper, or cellulose-based material) and a metallic material (e.g., including aluminum).

[0066] Figure 2 Also shown is a printed substrate layer 140 disposed between the paperboard layer 130 and the decorative layer 150. The printed substrate layer 140 may be Figure 1As shown, S10 is applied to the paperboard layer 130 before inkjet printing S20 the decorative layer 130. Applying S10 the printing substrate layer 140 may, for example, include coating the paperboard layer 130 with a pre-coating, priming the paperboard layer 130 by plasma treatment, flame treatment, corona treatment, or applying a surface conditioner to adjust the surface, for example, to change the topology, surface tension, wettability, electrostatic-related properties, or other surface properties. In a particular embodiment, the printing substrate layer 140 may be a clay coating or a primed clay coating, for example, to change the surface properties of the paperboard. Typically, the clay coating will form a waterproof surface on the paperboard layer, which means that the solvent of the ink cannot migrate into the paperboard layer. This requires increased drying capacity because it is very important to quickly dry the ink before further downstream processes. The printing substrate layer 140 may include a polymer film or a metallized polymer film. These alternatives also form a waterproof surface on the paperboard layer, which means that the solvent of the ink cannot migrate into the paperboard layer. This requires increased drying capacity because it is very important to quickly dry the ink before further downstream processes. The printed substrate layer 140 may completely cover the paperboard layer 130, or may only cover the area to be covered by the decorative layer 150, or may cover a medium-sized area of ​​the paperboard layer 130. If necessary, the method may further include drying the printed substrate layer 140 before printing the decorative layer 150. Figure 2 Although not explicitly shown, the paperboard layer 130 of the laminated packaging material web 100 will be Figure 1 After the method, the paperboard layer 130 has a crease line pattern, preferably the crease line pattern is cyclically repeated in the machine direction, and the moisture content will be 4% or more, between 5% and 10%, or preferably between 5% and 8.5%. After the above method, the moisture content of the paperboard layer 130 may not be significantly lower than the moisture content provided before the steps of the method are performed. For example, before the decorative layer 150 on the paperboard layer 130 is dried S30, the given moisture content of the paperboard layer 130 may be between 6% and 8.5%. This means that the paperboard layer 130 of the laminated packaging material web 100 does not suffer from moisture loss sufficient to cause any defects in the paperboard layer 130, and the quality of the final product is guaranteed.

[0067] Now go to Figure 3, a converting unit 200 configured to manufacture a web 100 of laminated packaging material is shown schematically. The converting unit 200 may be configured to perform the method as described above, and all aspects related to the method may also apply to the converting unit 200, and vice versa. The converting unit 200 comprises an inkjet printer 220, which is configured to print a decorative layer 150 on a paperboard layer 130, and is shown in the figure as a support cylinder and a plurality of print heads for cyan C, magenta M, yellow Y and black K. It should be noted that the exact configuration of the inkjet printer 220 may vary depending on the specific application; for example, the inkjet printer 220 may include a plurality of print heads arranged in the machine direction and / or in the cross direction so as to cover the entire width of the paperboard layer 130. The converting unit 200 also comprises a drying station 230, which is configured to dry the decorative layer 150 by exposing the paperboard layer 130 to infrared radiation IR and a hot air flow HA. The drying station 230 may include a hot air dryer 231 different from the infrared dryer 232, and the hot air dryer 231 may be arranged downstream of the infrared dryer 232. The conversion unit 200 also includes a crease station 240, which is configured to provide a crease line pattern to the paperboard layer 130, and at least one lamination station 250, which is configured to laminate at least another layer 110, 120, 160 onto the printed and creased paperboard layer 130. The stations included in the conversion unit 200 may be arranged in the following order from upstream to downstream: inkjet printer 220, drying station 230, crease station 240, lamination station 250. The conversion unit 200 may also include at least one feeding unit 210 (in Figure 3 The feed unit 210 may be configured to continuously advance the paperboard layer 130 at a constant speed, preferably in the machine direction. The conversion unit 200 may also include a printing substrate station (not shown), in parallel with the method explained above, located before the inkjet printer 220.

[0068] Now go to Figure 4 , shows an example of a paperboard layer 130 which has been provided with an inkjet printed decorative layer 150. The paperboard layer 130 has a certain width corresponding to six channels L1-L6. Each channel L1-L6 corresponds to a specific width of the final packaging container. After the conversion process, the laminated packaging material web 100 is cut to separate the channels L1-L6 so that each channel L1-L6 of the laminated packaging material web 100 can be fed into a filling and forming machine to produce a separate packaging container.

[0069] Each channel L1-L6 is printed with a decorative layer 150 corresponding to the final design of the packaging container. An infrared dryer 232 is arranged on the paperboard layer 130. In the example shown, the infrared dryer 232 includes a plurality of dryers 232a-f. Although not required, the number of dryers may correspond to the number of channels L1-L6 of the paperboard layer 130. A hot air dryer 231 is arranged downstream of the infrared dryer 232.

[0070] The controller 260 may be programmed to control the operation of the individual dryers 232a-f. Each dryer 232a-f may be individually controlled to provide a desired level of infrared radiation to minimize absorption by the paperboard layer 130, depending on the decorative layer.

[0071] From the above it can be seen that, although various embodiments of the invention have been described and shown, the invention is not restricted thereto but may also be embodied in other ways within the scope of the subject matter defined in the following claims.

Claims

1. A continuous in-line method for manufacturing a roll of laminated packaging material (100), comprising: Inkjet printing (S20) a decorative layer (150) on the paperboard layer (130), drying (S30) the decorative layer (150) by exposing the paperboard layer (130) to infrared radiation (IR) and a hot air flow (HA), and At least one further layer (110, 120, 160) is laminated (S50) to the printed paperboard layer (130).

2. The method according to claim 1, further comprising applying (S10) a printing substrate layer (140) to the paperboard layer (130) before inkjet printing (S20) the decorative layer (150).

3. The method according to claim 1 or 2, further comprising providing (S40) the paperboard layer (130) with a crease line pattern.

4. The method of claim 3, further comprising repeating the crease line pattern in a machine direction.

5. The method according to any of the preceding claims, wherein the paperboard layer (130) is conveyed in the machine direction at a substantially constant speed.

6. The method according to any one of the preceding claims, wherein drying (S30) the decorative layer (150) further comprises controlling the moisture content of the paperboard layer (130) by adjusting a ratio between the infrared radiation (IR) and the hot air flow (HA).

7. The method according to any one of the preceding claims, wherein drying (S30) the decorative layer (150) further comprises controlling the moisture content of the paperboard layer (130) by adjusting the temperature of the hot air flow (HA).

8. The method according to claim 6 or 7, wherein controlling the moisture level comprises determining a drying time and determining the ratio between the infrared radiation (IR) and the hot air flow (HA) by minimizing the amount of infrared radiation (IR) while still ensuring complete drying within the drying time.

9. The method according to any of the preceding claims, wherein drying (S30) the decorative layer (150) is performed by exposing a region of the paperboard layer (130) to infrared radiation (IR) and then exposing the same region of the paperboard layer (130) to the hot air flow (HA).

10. The method according to any of the preceding claims, wherein the infrared radiation (IR) has a spectral emission in the range 0.4 μm - 4 μm.

11. A conversion unit (200) configured to manufacture a web (100) of laminated packaging material, comprising: an inkjet printer (220) configured to print a decorative layer (150) on the paperboard layer (130); a drying station (230) configured to dry the decorative layer (150) by exposing the paperboard layer (130) to infrared radiation (IR) and hot air flow (HA); and at least one laminating station (250) configured to laminate at least one further layer (110, 120, 160) to the printed paperboard layer (130).

12. The conversion unit (200) of claim 11, further comprising a creasing station (240) configured to provide a creasing line pattern to the paperboard layer (130).

13. The conversion unit (200) according to claim 11 or 12, wherein: The drying station (230) comprises a hot air dryer (231) which is different from the infrared dryer (232), and wherein the hot air dryer (231) is arranged downstream of the infrared dryer (232).

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