Manufacturing method of laminated packaging material

Abstract

A continuous in-line method for manufacturing a laminated packaging material web, the method comprising: inkjet printing a plurality of ink droplets onto a paperboard layer, the ink droplets comprising a color pigment and a solvent; determining an adjusted drying power based on a determined ratio of a first subset of the ink droplets to the entire plurality of ink droplets, the first subset comprising a color pigment of only one particular color; and evaporating at least a portion of the solvent by applying hot air and / or infrared radiation at the adjusted drying power, such that the color pigment is immobilized.

Description

[Technical Field]

[0001] The present invention relates to a method for producing a laminated packaging material web for liquid food packaging containers, a converting apparatus, and a laminated packaging material web. [Background technology]

[0002] Disposable packaging containers for liquid foods are often manufactured from laminate packaging material, which is manufactured as a continuous web for use in roll-fed fillers or cut into individual blanks for use in blank-fed packaging machines.

[0003] Laminated packaging materials are manufactured using a converting process in which multiple materials are joined and processed to form a web of ready-to-use laminated packaging material.

[0004] During the converting process, the paperboard layer that forms the core layer of the laminate packaging material is typically printed on the outside (i.e., the side intended as the outside of the laminate packaging material) by digital printing, such as inkjet printing, dried, and laminated between the sealable layers. Optionally, the paperboard layer may be precoated before printing and / or may already be adhered to one or more layers.

[0005] Maintaining the desired moisture level in the paperboard layers throughout the converting process is important not only to ensure optimal performance of the various converting processes, but also to control the desired properties of the final packaging.

[0006] Infrared radiation is a proposed technique for drying paperboard layers after printing, especially digital printing, using aqueous inks such as pigmented water-based inks. While this technique allows for fast drying, it has been observed that more powerful drying also dries the paperboard layers, i.e., reduces their moisture content. The moisture loss in a given area of ​​the paperboard layer varies depending on the print design, particularly the amount of color, especially black pigment, printed in that area. In the case of liquid food packaging materials, printing inks are sometimes not covered with a coating such as a varnish after printing. They are overlaid with, for example, a polymer layer to protect the print after drying. As a result, it can be difficult to avoid over-drying, especially on unprinted surfaces, when drying the ink-printed areas. Therefore, uniform drying is difficult. A low moisture content in paperboard can have a negative impact on the converting process, especially if the paperboard layers are creased before lamination. If the moisture content of the paperboard layers drops to a certain level, the paperboard layers may crack rather than bend, potentially reducing the quality of the final laminated packaging web and the packaging containers produced from it. On the other hand, if the printed design is not dried sufficiently, defects related to rubbing or smearing of the printed color pattern of the decorative layer may occur. Therefore, there is a need in the art for improvements in the manufacturing techniques of laminated packaging material webs, particularly with regard to ink drying. Summary of the Invention [Problem to be solved by the invention]

[0007] It is an object of the present invention to overcome at least some or more of the above-identified limitations of the prior art, and in particular to provide a reliable and efficient method for producing a laminated packaging material web in which the moisture level of the paperboard layers is maintained even as print designs change. [Means for solving the problem]

[0008] To achieve these objectives, a continuous in-line method for manufacturing a laminated packaging material web is provided. The method includes inkjet printing a plurality of ink droplets onto a paperboard layer, for example to form a decorative layer, the ink droplets including a color pigment and a solvent; determining a proportion of a first subset of the ink droplets relative to the total number of ink droplets, the first subset including only one specific color of color pigment; and determining an adjusted drying power based on the determined proportion of the first subset of ink droplets; and applying hot air and / or infrared radiation at the adjusted drying power to evaporate, or dry, at least a portion of the solvent so that the color pigment is fixed. This is advantageous in that the moisture content of the paperboard layer is substantially maintained even when the print design is changed. The moisture content of the paperboard layer may be, for example, 4% or more, 5% to 10%, and preferably 5% to 8.5%.

[0009] The likely paperboard layer is one used in liquid food packaging. In other words, the likely laminated packaging web is a laminated liquid food packaging web, also known as liquid packaging paperboard.

[0010] Generally, paperboard used for liquid packaging has a top surface, which is optimal for printing, and a back surface, which is water-repellent and resistant to water absorption from the external environment. Therefore, paperboard is not suitable for rewetting from the back side as needed, as this can lead to over-drying after drying. Furthermore, paperboard printed with water-based inks cannot be rewetted from the top side after drying, in order to avoid decomposing the ink. Furthermore, when producing liquid food packaging materials, rewetting is not recommended for food safety reasons.

[0011] In one embodiment, a print with a CMYK (cyan, magenta, yellow, black) combination exceeding 200% TAC (Total Area Coverage) can be produced. Such prints cannot be dried using infrared alone without overheating the black areas, which would result in over-drying the paperboard, affecting the paperboard's drying consistency and moisture content.

[0012] In one embodiment, the ink may contain not only water but also some organic volatile components. The combination of water and volatile organics may result in a high boiling point for drying the ink. Therefore, using IR alone may require higher drying energy, which may lead to over-drying of the paperboard.

[0013] The method may further include flexographic printing or other printing techniques, so that the decorative layer may be obtained by inkjet printing alone or by a hybrid approach combining two or more printing techniques. In other words, the decorative layer may be inkjet printed and flexographically printed. The ink used in inkjet printing may have a higher solvent-to-color pigment ratio than the ink used in flexographic printing. For example, the inkjet ink may have about four times the water content of the flexographic ink. Furthermore, the total amount of ink laid down on the paperboard layer is several times higher in inkjet printing than in flexographic printing. Therefore, it is even more important in inkjet printing to provide a fast-drying process that does not reduce the moisture content of the paperboard layer.

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

[0015] In one embodiment, the present invention is believed to be more beneficial when it is necessary to dry the paperboard layer as quickly as possible. For example, when the paperboard has a printing substrate layer that avoids the ink solvent, which is most likely an aqueous ink, being transferred by the paperboard, it may be more beneficial to dry the packaging material as quickly as possible without drying it too much. In other words, when the paperboard has a printing substrate layer that can retain almost all of the ink solvent, which is most likely an aqueous ink printed on the printing substrate layer, it may be more beneficial to dry the packaging material as quickly as possible without drying it too much.

[0016] Applying the printing substrate may comprise, for example, applying a pre-coating to the paperboard layer, priming the paperboard layer by plasma treatment to create an optimal surface tension / wetting property for the printing substrate layer on its surface, or applying a surface conditioner, thereby changing the topological or electrostatic properties. The printing substrate may completely cover the paperboard layer, or may cover only the area to be covered with the decorative layer, or may cover a medium-sized area of ​​the paperboard layer.

[0017] In one embodiment, the paperboard layer may be provided with a printable coating, such as a white pigment and clay coating, as a printing substrate layer. Such a clay coating forms a water-repellent surface on the paperboard layer, meaning that ink solvents do not migrate or are absorbed into the paperboard fiber layer. Because it is important for the ink to dry quickly before further downstream processing, high drying power is required.

[0018] In one embodiment, the printing substrate layer may be a clay coating that is primed prior to inkjet printing.

[0019] In one embodiment, the printing substrate layer may be provided on the paperboard layer prior to inkjet printing at the same production site and / or well in advance, for example at a different production site, so that application of the printing substrate layer is not achieved at the site where inkjet printing is achieved.

[0020] In one embodiment, the ratio of the first subset of ink droplets to the complete plurality of ink droplets is substantially constant for the predefined cyclically repeating print pattern, and the adjusted drying power is determined for each predefined cyclically repeating print pattern, which is beneficial because it enables efficient and uniform drying of each print pattern and facilitates maintaining the moisture content of the paperboard layer.

[0021] In one embodiment, the method further includes providing the paperboard layer with a crease pattern. As an example, the crease pattern may be repeated in the machine direction.

[0022] In a possible embodiment, the fold lines may be provided upstream and / or downstream of the inkjet printing.

[0023] Preferably, the paperboard layer has a minimum thickness of 90 μm and / or a minimum weight of 65 gsm.

[0024] The paperboard layer may be uncoated paperboard or may be paperboard that has been laminated with one or more layers, such as a polymer layer, prior to inkjet printing and / or application of the printing substrate layer.

[0025] The paperboard layers may be conveyed along the machine direction at a substantially constant speed, for example 200 m / min or greater.

[0026] In one embodiment, the solvent is evaporated using a combination of hot air and infrared radiation, the hot air being applied after the infrared radiation.

[0027] 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 flow of hot air, which is beneficial because it allows for precise control of the decorative layer and the paperboard layer, making it easier to maintain moisture content with minimal drying time.

[0028] Drying the decorative layer may further include controlling the moisture content of the paperboard layer by adjusting the mass flow rate of the hot air to a target flow rate of the supply air slot of the dryer (i.e., impingement dryer) and adjusting the temperature of the hot air.

[0029] The hot air dryer may have a slot speed of 45 to 85 m / s and an air temperature of 55 to 80° C. The humidity in the hot air supplied from the hot air dryer to dry the decorative layer may be controlled, preferably in-line.

[0030] In one embodiment, the temperature of the paperboard may be controlled, preferably in-line. If the printed and laminated packaging material has two or more lanes, each one of the lanes used to feed the liquid food filling machine may be individually controlled during and / or downstream of printing and / or drying to avoid having temperature gradients.

[0031] In one embodiment, controlling the moisture level comprises determining a drying time and determining the ratio of infrared radiation to hot air flow by minimizing the amount of infrared radiation while ensuring complete drying within the drying time, thereby minimizing problems related to moisture loss in the paperboard layers.

[0032] Drying of the decorative layer may be performed by exposing an area of ​​the paperboard layer to infrared radiation and then exposing the same area of ​​the paperboard layer to a stream of hot air. As an example, an area of ​​the paperboard layer may be exposed to infrared radiation until a determined moisture level of the paperboard is reached, and drying of the remainder of the decorative layer may be performed by a stream of hot air. This ensures time efficiency of the method while ensuring the desired moisture content of the paperboard layer.

[0033] The infrared radiation may have a spectral radiation between 0.4 μm and 4 μm, in other words, the infrared radiation may be near infrared, short wave infrared, mid wave infrared, or radiation in multiple infrared regions.

[0034] The present invention may be practiced without re-moistening or wetting downstream of drying, thus avoiding the extra operations and associated controls.

[0035] In one embodiment, the printing and drying method for the laminate packaging material may be performed roll-to-roll. That is, a roll of paperboard may be unwound upstream for printing and wound downstream for lamination with additional layers. When the laminate packaging material is wound into a roll, friction and stretching forces are applied to the printed matter, so it is necessary to properly dry the printed matter while avoiding over-drying the paperboard. Furthermore, if crease patterns are formed in the laminate packaging material, these patterns should be able to withstand friction and stretching forces by maintaining the moisture content in the paperboard. The rolled packaging material web may be easily transported to further processes, such as filling the interior of the packaging material web with a product, perhaps a liquid food product.

[0036] The order of the method steps is not a limitation of the present invention, and those skilled in the art may use various orders of the steps mentioned, so long as it is technically possible to achieve the advantage of substantially maintaining the moisture content of the paperboard layers through IR drying and hot air drying.

[0037] The ink solvent may comprise different volatile and non-volatile organic content, such as glycols. The ink solvent may also comprise water.

[0038] In one embodiment, the method further comprises laminating at least a further layer to the printed paperboard layer.

[0039] In one embodiment, evaporation of at least a portion of the solvent by application of hot air and / or infrared radiation at a regulated drying power is conducted such that the surface temperature of the paperboard layers does not exceed 65° C., preferably the surface temperature of the paperboard layers does not exceed 60° C., and more preferably the surface temperature of the paperboard layers does not exceed 56° C. This minimizes defects associated with the surface temperature of the paperboard layers. Additionally, increased control of the surface temperature facilitates increased control of the moisture content of the paperboard layers.

[0040] A first subset of ink droplets may have a darker color than the entire plurality of ink droplets. Determining the adjusted drying power based on the proportion of dark-colored ink droplets is an efficient way to dry printed decorations on paperboard layers so that the moisture content of the paperboard is maintained even when the decoration design changes. Especially in the case of IR drying, dark colors tend to absorb more IR radiation, generating more heat, increasing the surface temperature and drying the moisture content of the paperboard layer. Setting a drying power limit for dark-colored areas, even if only a portion of the ink is used, can limit the surface temperature increase even in light-colored printed areas, thereby maintaining a sufficiently high moisture content of the paperboard layer.

[0041] Dark color may refer to a color that has a high amount of black pigment compared to other colors used in printing.

[0042] In one embodiment, after laminating at least an additional layer, the printed and laminated packaging material may be rolled onto a roller. If the paperboard layer is provided with a crease pattern, after laminating at least an additional layer, the printed, creased, and laminated packaging material may be wound onto a roller. In this way, the rolled packaging material web may be transported in an easy manner for further processing, such as filling the interior of the packaging material web with a product, perhaps a liquid food product.

[0043] Another aspect of the present invention relates to a converting unit configured to produce a laminated packaging material web. The converting unit may be configured to perform the continuous in-line method for producing a laminated packaging material web described herein, and therefore all aspects disclosed with respect to that method are intended to be included. The converting unit includes a paperboard layer supply station, an inkjet printer configured to print an ink containing a color pigment and a solvent onto the paperboard layer, and a drying station configured to dry the ink with adjusted drying power by exposing the paperboard layer to infrared radiation and a stream of hot air. The drying station includes a control unit configured to determine the adjusted drying power based on a determined ratio of a first subset of inks to the total ink, the first subset comprising only one specific color pigment. This allows the moisture content of the produced paperboard layer to be maintained at a sufficiently high level even when the printed design changes.

[0044] In one embodiment, the converting unit may include a creasing station configured to provide a crease pattern to the paperboard layer.

[0045] The included stations may be arranged in the following order from upstream to downstream: paperboard layer supply station, inkjet printer, drying station, and creasing station.

[0046] The converting unit may further include at least one laminating station configured to laminate multiple layers to the printed and creased paperboard layer.

[0047] The drying station may comprise separate hot air and infrared dryers, with the hot air dryer being located downstream of the infrared dryer, thereby minimizing moisture loss in the paperboard layers while ensuring time efficiency of the process.

[0048] It is also possible to place the creasing station upstream of the inkjet printer, or to place multiple creasing stations both downstream and upstream of the inkjet printer, or to have a combined inkjet printer and creasing station unit that allows creasing before and / or after printing.

[0049] The converting unit may further include a print substrate station configured to apply a print substrate layer to prepare the paperboard layer before being printed by the inkjet printer. As described above, applying the print substrate layer may include coating the paperboard layer with a pre-coating, such as a clay coating or a primed clay coating, or priming the paperboard layer with a plasma treatment to form the print substrate layer on the surface of the paperboard layer, or applying a surface conditioner, or otherwise modifying the surface properties of the paperboard layer. The converting unit may further include a second drying station for drying the print substrate layer.

[0050] The order of the stations is not limiting to the present invention, and those skilled in the art may use various orders of the described stations as long as it is technically possible to achieve the benefit of substantially maintaining the moisture content of the paperboard layers through IR drying and hot air drying.

[0051] In one embodiment, the converting unit may be a roll-to-roll unit, meaning that a roll of paperboard may be unwound upstream of printing and rolled downstream of lamination with additional layers. When the laminated packaging material is wound into a roll, friction and stretching forces are applied to the printed matter, so it is necessary to properly dry the printed matter while avoiding over-drying the paperboard. Furthermore, if crease patterns are formed in the laminated packaging material, these patterns should be able to withstand friction and stretching forces by maintaining the moisture content in the paperboard. The rolled packaging material web may be easily transported to further processes, such as filling the interior of the packaging material web with a product, perhaps a liquid food product.

[0052] Another aspect of the present invention provides a laminated packaging material web. The laminated packaging material web comprises a paperboard layer having an inkjet-printed decorative layer composed of a plurality of ink droplets. The moisture content of the paperboard layer is 4% or more, preferably 5% to 8.5%.

[0053] As an example, after inkjet printing the decorative layer, the moisture content of the paperboard layer may be 6% to 8.5%, and in the final laminated packaging material web, the moisture content of the paperboard layer may be substantially the same or slightly lower, meaning that the paperboard layer has not suffered significant moisture loss, at least not enough to result in significant defects in the laminated packaging material web.

[0054] The laminate packaging material may have a crease pattern, for example, the crease pattern may repeat periodically in the machine direction.

[0055] Embodiments of all aspects of the invention may be combined and preferred with each other, unless stated to the contrary above or below.

[0056] Further objects, features, aspects and advantages of the present invention will become apparent from the following detailed description and drawings.

[0057] Non-limiting embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which: [Brief explanation of the drawings]

[0058] [Figure 1] 1 is a flowchart of a method for manufacturing a laminated packaging material web according to one embodiment. [Figure 2a] 1 is a schematic diagram of a printed paperboard layer according to one embodiment. [Figure 2b] 1 is a schematic diagram of a printed paperboard layer according to one embodiment. [Figure 2c] 1 is a schematic diagram of a printed paperboard layer according to one embodiment. [Figure 3] 1 is a cross-sectional view of a laminated packaging material web according to one embodiment. [Figure 4] FIG. 2 is a schematic side view of a conversion unit according to an embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0059] Referring to FIG. 1 , an embodiment of a continuous in-line method 1 for producing a laminated packaging material web 100 is shown. The method 1 includes inkjet printing S10 a plurality of ink droplets 300 onto a paperboard layer 130. The paperboard layer 130 may comprise paper, paperboard, or other cellulosic material. Inkjet printing is a type of digital or computer-generated printing. During inkjet printing, a digital image is reproduced by jetting droplets of ink onto a substrate, such as the paperboard layer 130 or a print substrate layer (not shown) described further herein. The ink droplets 300 include a color pigment and a solvent. The solvent may include water and a volatile organic component, such as glycol. The method further includes determining S20 an adjusted drying power based on the determined proportion of a first subset 310 of ink droplets relative to the entire plurality of ink droplets 300, the first subset 310 including a color pigment of only one specific color. Thus, method 1 may select a particular color of the intended decorative layer and, from there, select a first subset of ink droplets 310 corresponding to the selected color. Based on the determined subset of ink droplets 310, method 1 determines an adjusted drying power.

[0060] The method further includes evaporating at least a portion of the solvent (S30) by applying hot air (HA) and / or infrared radiation (IR) with a drying power adjusted to immobilize the color pigment. The infrared radiation (hereinafter IR) is radiated onto the paperboard layer, where it is absorbed to some extent by the pigment in the ink (300), evaporating the solvent in the ink (300). The evaporation step (S30) including IR ensures a more reliable process that is not affected by the air boundary layer. Infrared drying also facilitates a more time-efficient process because it is a highly efficient energy transfer process (high spectral energy per square area).

[0061] However, high radiation intensity penetrating the ink 300 not only removes moisture from the ink 300, but also from the cellulosic paperboard layer 130, which can cause various problems with the performance of the laminated packaging material web 100. A laminated packaging material web 100 made of a paperboard layer 130 with a reduced moisture content can suffer from cracking, especially at the intersections of multiple fold lines, delamination of the laminated packaging material web 100, and problems with the integrity of the final package. The drying power of the IR can be adjusted to minimize problems with paperboard moisture loss.

[0062] Adjusted drying power can be achieved by varying the spectral radiance, radiation intensity, or exposure time of infrared radiation, which affects the transmission level of the printed ink 300. Because black pigments absorb infrared more than other colors, the density of the ink 300 also affects infrared transmission. It is beneficial to adjust the drying power based on the determined proportion of ink droplet subsets 310 with a specific color relative to the total ink 300, particularly the determined proportion of dark ink droplet subsets 310. This allows for appropriate adjustment of the drying power and maintains the moisture content of the paperboard under different design conditions. For example, light colors, such as red, green, or violet, require higher IR energy to evaporate the solvent. On the other hand, dark colors, such as black, brown, and dark green, require approximately 20% less IR energy.

[0063] Alternatively, or additionally, hot air drying may be used to evaporate at least a portion of the solvent (S30). Hot air drying is a simple and well-established technique in which the surrounding air is heated, heat is transferred from the hot air flow to the printing ink by convection, and the solvent evaporated from the ink (i.e., together with the saturated air) is also transported to the air by convection. Therefore, the hot air HA acts mainly on the surface of the paperboard layer 130, with minimal penetration into the interior of the paperboard. The drying power of the hot air HA may be adjusted, for example, by adjusting the flow rate or temperature of the hot air HA.

[0064] To take advantage of the benefits of both technologies, it is preferable to combine IR and hot air HA to dry the board layers. Hot air HA may be applied after IR. This allows the IR to first evaporate as much solvent as possible without losing too much moisture from the board layers, keeping the board temperature below the target value, and then the surface hot air HA to evaporate the remaining solvent, providing a time-efficient process while maintaining the moisture content of the board layers.

[0065] FIG. 2a shows a paperboard layer 130 with a design pattern of four different color regions inkjet printed on it. Each of the four regions comprises a different proportion of a first subset 310 of ink droplets, shown in FIG. 2a as consisting of black pigment, relative to the total number of ink droplets 300. Typically, the different colored regions have different color distributions and / or color selections. FIGS. 2b and 2c show increasingly complex design patterns that highlight the need for adaptive ink drying. With such patterns, a non-adjustable drying method risks drying out the paperboard when controlling the IR drying power to sufficiently dry the light-colored ink droplets. An adjusted drying power is determined (S20) based on the determined ratio of the first subset 310 of ink droplets to the entire plurality of ink droplets 300, where the first subset 310 includes only one specific color pigment, and by applying hot air HA and / or infrared light IR at the adjusted drying power (S30), the solvent can be evaporated from the entire target area so that all the color pigments are immobilized while maintaining the moisture content of the paperboard layer 130. The ratio of the first subset 310 of ink droplets to the entire plurality of ink droplets 300 may be substantially constant for a predefined, periodically repeating print pattern, as shown in FIGS. 2b and 2c. The adjusted drying power may be determined (S20) for each predefined, periodically repeating print pattern.

[0066] The ratio of ink subset 310 to the total ink 300 (if subset 310 is composed of a specific color pigment) further affects the temperature of ink 300. Darker color pigments absorb more infrared radiation, thereby increasing the surface temperature of printed paperboard layer 130. Step S30 of evaporating the solvent may be performed so that the surface temperature of paperboard layer 130 does not exceed 65°C. Preferably, the surface temperature of paperboard layer 130 does not exceed 60°C, and more preferably, the surface temperature of paperboard layer 130 does not exceed 56°C.

[0067] Returning to FIG. 1 , the method may further include providing a crease pattern (S40) in the paperboard layer 130 after evaporating the solvent. The crease pattern facilitates the formation of a package container from the laminated packaging material web 100 (not shown). The crease pattern may be periodically repeated in the machine direction MD. The machine direction MD may be defined as the direction parallel to the movement of the paperboard layer 130 through a manufacturing device, such as the converting unit 200 illustrated in FIG. 4, or as the circumferential direction of a roll of paper used to provide the paperboard layer 130, such as those illustrated in FIGS. 2a-c. The laminated packaging material web 100 may have a machine direction MD and a transverse direction TD defined perpendicular to the machine direction MD. The dimensions of the laminated packaging material web in the machine direction MD may be substantially larger than those in the transverse direction TD. During the method, the paperboard layer 130 may be conveyed along the machine direction, as defined above, at a substantially constant speed. A preferred converting speed is 200 m / min or greater. An example of the path of paperboard layer 130 through conversion unit 200 is shown in FIG.

[0068] Continuing with reference to FIG. 1 , the method may further include laminating S50 at least additional layers 110, 120, 160 to the printed and creased paperboard layer 130. A cross-section of an example laminated packaging web including a paperboard layer 130 printed with ink 300 and multiple layers 110, 120, 160 laminated thereto is shown in FIG. 3. The illustrated laminated packaging web 100 includes two sealable layers 110, 160, one positioned at the top of the laminated packaging web 100 to form the exterior or outer casing of a package formed from the laminated packaging web 100, and the other positioned at the bottom of the laminated packaging web 100 to directly contact the filled food within the package. The sealable layers 110, 160 are preferably liquid-tight. The sealable layers 110, 160 may be heat-sealable or may comprise a thermoplastic material. FIG. 3 further illustrates a barrier layer 120, as defined above, laminated to, preferably on the inside, paperboard layer 130. The barrier layer 120 may comprise any barrier material suitable for maintaining a food-safe environment for the packaged liquid food. This includes metals such as aluminum foil; polymeric materials such as ethylene vinyl alcohol copolymer (EVOH) or polyamide (PA); polysaccharides such as starch or fibrous or crystalline cellulose; and polymer-based film substrates coated with a barrier coating selected from metals, metal oxides, inorganic oxides, other inorganic compounds, or carbon-based coatings such as amorphous diamond-like carbon (DLC) coatings. The barrier layer 120 may also comprise cellulosic materials and / or composites or multi-layer coatings composed of non-metallic materials, such as plastics, paper, or cellulosic materials, and metallic materials, such as aluminum.

[0069] Although not shown, the method may include the application, printing, and / or drying processes of an additional printing substrate layer. For example, a surface treatment may be applied to the paperboard layer 130, followed by printing using flexography, and drying the printed areas by exposing them to infrared radiation (IR) and / or hot air (HA). Subsequently, a printing substrate layer may be applied to the paperboard layer 130, and the printing substrate layer may be dried by IR and / or hot air (HA). Next, a decorative layer may be inkjet printed (S10) on the printing substrate layer, and the paperboard layer 130 may be dried (S30) by exposing it to a stream of infrared radiation (IR) and / or hot air (HA). The paperboard layer 130 may be further printed using flexography and dried again.

[0070] A printing substrate layer may be applied to the paperboard layer 130 prior to inkjet printing S10. Applying the printing substrate layer may include, for example, coating the paperboard layer 130 with a pre-coating, priming the paperboard layer 130 by plasma treatment, flame treatment, or corona treatment, or applying a surface conditioner to condition the surface, for example, to modify the topology, surface tension, wettability, electrostatic properties, or other surface properties. In certain embodiments, the printing substrate layer may be a clay coating or a primed clay coating to modify the surface properties of the paperboard. Typically, the clay coating forms a water-repellent surface on the paperboard layer, meaning that the ink solvent cannot migrate to the paperboard layer. This increases the drying power because it is important to quickly dry the ink before further downstream processing. The printing substrate layer may also comprise a polymer film or a metallized polymer film. These alternatives also form a water-repellent surface on the paperboard layer, preventing the ink solvent from migrating to the paperboard layer. This increases the drying power because it is important to quickly dry the ink before further downstream processing. The printing substrate layer may completely cover the paperboard layer 130, may cover only the area to be covered by the decorative layer (plurality of ink droplets), or may cover an intermediate sized area of ​​the paperboard layer 130. The method may further include drying the printing substrate layer before printing the decorative layer, if desired.

[0071] After the method of FIG. 1 , the paperboard layer 130 of the laminated packaging material web 100 may have a crease pattern, preferably a crease pattern that repeats periodically in the machine direction, and may have a moisture content of 4% or more, 5% or more and 10% or less, preferably 5% or more and 8.5% or less. The moisture content of the paperboard layer 130 after the above-described method may not be significantly lower than the moisture content provided before the method steps are performed. As an example, the provided moisture content of the paperboard layer 130 may be between 6% and 8.5% before the step of evaporating the S30 solvent from the paperboard layer 130. This means that the paperboard layer 130 of the laminated packaging material web 100 has not suffered moisture loss of a magnitude that would result in defects in the paperboard layer 130, ensuring the quality of the final product.

[0072] 4, there is shown a schematic diagram of a converting unit 200 configured to produce laminated packaging material web 100. Converting unit 200 may be configured to perform the method as described above, and all aspects disclosed with respect to the method may also be implied for converting unit 200 and vice versa.

[0073] Converting unit 200 preferably includes a paperboard layer feed station 210 configured to advance paperboard layer 130 at a constant speed, more preferably continuously in the machine direction. One or more feed stations 210 may be included in converting unit 200, with two feed stations 210 illustrated in Figure 4.

[0074] Conversion unit 200 further comprises an inkjet printer 220 configured to print ink 300, which includes color pigments and a solvent, onto paperboard layer 130. In the figures, inkjet printer 220 is illustrated as a support cylinder and multiple printer heads for cyan C, magenta M, yellow Y, and black K, but may be expanded for multi-color printing, for example, with orange, green, and violet. It should be noted that the exact configuration of inkjet printer 220 may vary depending on the particular application; for example, inkjet printer 220 may comprise multiple printer heads arranged in the machine direction and / or cross direction to cover the entire width of paperboard layer 130.

[0075] The converting unit 200 further includes a drying station 230 configured to dry the ink 300 with an adjusted drying power by exposing the paperboard layer 130 to a flow of infrared radiation IR and hot air HA. The drying station 230 may include a separate hot air dryer 233 and an infrared dryer 232, and the hot air dryer 233 may be disposed downstream of the infrared dryer 232. The drying station 230 includes a control unit 231 configured to determine an adjusted drying power based on a determined ratio of the first subset 310 of inks to the total ink 300, the first subset 310 including only one specific color pigment. The infrared dryer 232 may be disposed in a direction substantially perpendicular to the machine direction MD so as to extend across the paperboard layer 130 in the transverse direction, or substantially in the transverse direction TD. The infrared dryer 232 may be comprised of multiple dryers. The control unit 231 may be programmed to control the operation of each dryer. Depending on the design pattern, each dryer may be individually controlled to provide a desired level of infrared radiation that minimizes absorption by the paperboard layer. As an example, for drying paperboard layer 130 as shown in Figure 2a, all individual dryers may be controlled to provide the same first adjusted drying power to a first region, and then a second adjusted drying power to a second region. For drying paperboard layer 130 as shown in Figures 2b and 2c, each dryer may be controlled to provide an individual adjusted drying power to each region.

[0076] The converting unit 200 further includes a creasing station 240 configured to provide a crease pattern to the paperboard layer 130. The stations may be arranged from upstream to downstream in the following order: paperboard layer supply station 210, inkjet printer 220, drying station 230, and creasing station 240. The converting unit 200 may further include at least one laminating station 250 configured to laminate the multiple layers 110, 120, and 160 to the printed and creased paperboard layer 130. The converting unit (200) may also include a print substrate station (not shown) prior to the inkjet printer (220), in parallel with the method described above.

[0077] From the foregoing description, while various embodiments of the present invention have been described and shown, 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 continuous in-line process for producing a laminated packaging material web (100), comprising: Inkjet printing (S10) a plurality of ink droplets (300) onto a paperboard layer (130), the ink droplets (300) comprising a color pigment and a solvent; determining (S20) an adjusted drying power based on the determined ratio of a first subset (310) of ink droplets to the entire plurality of ink droplets (300); the first subset (310) including color pigments of only one specific color; evaporating at least a portion of the solvent by applying hot air (HA) and / or infrared radiation (IR) with adjusted drying power to fix the color pigment (S30); A method comprising:

2. a ratio of the first subset of ink droplets (310) to the total number of ink droplets (300) being substantially constant for a predefined periodically repeating printing pattern, and the adjusted drying power being determined for each predefined periodically repeating printing pattern (S20); The method of claim 1.

3. After evaporating the solvent, the paperboard layer (130) is provided with a crease pattern (S40).

3. The method according to claim 1 or 2.

4. the crease pattern repeats periodically in the machine direction (MD); The method of claim 3.

5. The paperboard layer (130) is conveyed along a machine direction (MD) at a substantially constant speed; The method according to any one of claims 1 to 4.

6. The solvent is evaporated by a combination of the application of the hot air (HA) and the application of the infrared radiation (IR), and the hot air (HA) is applied after the infrared radiation (IR). The method according to any one of claims 1 to 5.

7. the infrared (IR) has a spectral emission of 0.4 μm to 4 μm; The method according to any one of claims 1 to 6.

8. the ink solvent contains a volatile organic component; The method according to any one of claims 1 to 7.

9. and further comprising laminating (S50) at least a further layer (110, 120, 160) to said paperboard layer (130). The method according to any one of claims 1 to 8.

10. evaporating at least a portion of the solvent by applying the hot air (HA) and / or the infrared radiation (IR) with the adjusted drying power is performed such that the surface temperature of the paperboard layer (130) does not exceed 65°C, preferably such that the surface temperature of the paperboard layer (130) does not exceed 60°C, more preferably such that the surface temperature of the paperboard layer (130) does not exceed 56°C. The method according to any one of claims 1 to 9.

11. the first subset of ink droplets (310) having a dark color compared to the entire plurality of ink droplets (300); The method according to any one of claims 1 to 10.

12. A converting unit (200) configured to continuously produce a laminated packaging material web (100), comprising: a paperboard layer supply station (210); an inkjet printer (220) configured to print an ink (300) containing a color pigment and a solvent onto the paperboard layer (130); and a drying station (230) configured to dry the ink (300) with regulated drying power by exposing the paperboard layer (130) to a stream of infrared (IR) and / or hot air (HA); the conversion unit (200), the drying station (230) comprising a control unit (231) configured to determine the adjusted drying power based on a determined ratio of a first subset (310) of inks to the total ink (300), the first subset (310) including only one specific color of color pigment; Conversion unit (200).

13. the drying station (230) comprises a separate hot air dryer (233) and an infrared dryer (232), the hot air dryer (233) being located downstream of the infrared dryer (232); Transformation unit (200) according to claim 12.

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