Method of manufacturing a decorative panel

Abstract

Decorative panels are manufactured using a roll-to-roll inkjet printer. During the feeding of the substrate to be printed, the tension of the substrate is controlled by a bouncing unit (720), which includes a bouncing roller (200) having connectors (120) at both ends of the roller, wherein the two connectors (120) are connected to a pair of parallel guides (110) for floating the roller along a floating path (210); and wherein the control step includes moving one of the pair of guides (110) parallel to the floating path (210), thereby tilting the bouncing roller (200).

Description

Technical Field

[0001] The present invention relates to the manufacture of decorative panels, wherein decorative images such as wood patterns are printed on a substrate by a web-feed inkjet printing system to form a decorative layer, which is then pressed onto the decorative panel together with one or more other layers; the decorative panel may be cut into multiple decorative laminates for use as decorative flooring, decorative wall elements, etc. Background Technology

[0002] Gravure, offset, and flexographic printing are increasingly being replaced by industrial inkjet printing systems for various applications. Industrial inkjet printing systems have now proven their flexibility in use (such as variable data printing, which makes short production runs and personalized products possible) and their enhanced reliability, thus allowing them to be integrated into production lines (also known as manufacturing lines).

[0003] Inkjet technology has also been implemented in manufacturing lines for decorative panels. This is discussed in "Handbook of Industrial Inkjet Printing: A Full System Approach" edited by Werner Zapka (publisher Wiley-VCH Verlag GmbH & Co., 22 / 11 / 2017, page 984). Patrik Lutz Chapter 44, "Industrial Inkjet Printing in Decorative Web Print Applications," was created and... Aliasgar Eranpurwala Chapter 48, “Hymmen Digital Décor Printing: Empowering the Laminate Industry,” discloses a historical overview and specific case studies of roll-to-roll inkjet printing systems used to print decorative images on decorative paper to manufacture decorative panels.

[0004] In the manufacture of decorative panels, not only single-pass inkjet printers are used as roll-to-roll inkjet printing systems, but multi-pass inkjet printers are also used as roll-to-roll inkjet printing systems. For example, a multi-pass inkjet printing system is disclosed in the following published European patent application EP2905145 A1 (UNILIN BVBA), in which, in paragraph

[0024] , a multi-pass inkjet printing system for manufacturing decorative panels is disclosed. An example of such an inkjet printing system is one using CMYK inkjet ink from AGFA. TM The pioneer of the ●factory TM Then came Hymmen TMJPT-W digital printing line and from Koenig & Bauer TM RotaJET TM 225, they are all used as the manufacturing line for decorative panels.

[0005] A major problem is the use of thin roll paper substrates on which decorative layers are printed in the manufacture of decorative panels. During the feeding of these thin roll paper substrates, wrinkles easily form in roll-to-roll inkjet printers, resulting in poorly printed decorative layers. Small, invisible wrinkles in both the fed and printed roll paper substrates also cause delamination of the decorative panels, including the decorative layers, on these invisible, wrinkled substrates.

[0006] The rollers are mostly pre-treated offline before entering a web-fed inkjet printer, for example, by applying a coating or ink-receiving layer, or by being cut from the master roller. Due to unwinding and (re)winding, the rollers cut during this offline process to make the web-fed paper substrate printable for the web-fed inkjet printer create tension differences within the rollers, and even if the 'printable' rollers of the web-fed paper substrate are made of the same material, tension differences still exist between them. Operators of web-fed inkjet printers require components for controlling, predicting, and maintaining these changes in tension within and between the rollers. Summary of the Invention

[0007] To overcome the problems described above, a preferred embodiment of the present invention has been implemented using the following method for manufacturing decorative surfaces, the method comprising the following steps:

[0008] - Feed the roll paper substrate along the feed path in a roll-feed inkjet printer;

[0009] - Print a decorative layer on the substrate using the printing press;

[0010] - A layer assembly is formed by applying one or more other layers to the printed substrate and / or by applying the printed substrate to one or more other layers;

[0011] - Press the component to constrain the layer of the component to form a decorative panel; and

[0012] - During the feed, the tension of the substrate is controlled to avoid one or more wrinkles in the substrate; wherein the control step is performed by a jumping unit within the feed path, wherein the jumping unit includes a jumping roller having:

[0013] - An axis, positioned parallel to a first direction, the first direction being the transverse direction of the feed base; and...

[0014] - Connectors are provided at both ends of the shaft, wherein the two connectors are connected to a pair of parallel guides for causing the roller to float along a floating path perpendicular to the first direction; and,

[0015] The control steps include:

[0016] - Move one of the paired guides parallel to the floating path to tilt the axis at the location where the axis is connected to the moving guide.

[0017] Therefore, in a web-fed inkjet printer, the web substrate is fed without wrinkles, and if there are differences in tension within the input rollers of the web substrate or in the tension within different input rollers of the web substrate, the tension can be quickly controlled and predicted. The tension can be measured along the feed path. (See attached figures)

[0018] Figure 1 and Figure 2 The same dancer unit of the preferred embodiment is illustrated, but is shown in close view.

[0019] Figure 3 The illustration shows a web-fed inkjet printer according to a preferred embodiment. Roman numeral I illustrates a top view of the web-fed inkjet printer, and Roman numeral II illustrates a cross-section of the web-fed inkjet printer.

[0020] Figure 4 The illustration shows a preferred embodiment of the tapping unit. Roman numeral III illustrates a front view of the tapping unit. A roll of paper substrate is present as it enters the tapping unit. Detailed Implementation

[0021] Roll-to-roll inkjet printing system

[0022] A roll-to-roll inkjet printing system includes components for transporting a roll of paper substrate and uses one or more inkjet printheads to print a decorative layer 500 on the roll of paper substrate. The one or more inkjet printheads are preferably included in an inkjet printhead unit 400, and more preferably include an inkjet ink assembly for printing the colored decorative layer 500, which preferably represents an oligochromatic image, and more preferably a wood pattern. The roll-to-roll inkjet printing system includes components for transporting one or more rolls of paper substrate.

[0023] A roll comprising a web paper substrate 300 is mounted on a web paper feeder implementing one or more spindles. The spindles rotate by torque distributed from a drive shaft by a drive mechanism. The spindle is a coaxial shaft used to hold the roll comprising the web paper substrate. The spindle is also referred to as a shaft. Goldenrod TM The company provides equipment for winding a substrate onto a roller and unwinding the substrate from the roller. Such shaft and roller manipulation is well known in the current state of technology.

[0024] The web-fed inkjet printing system preferably includes a drying device for drying the decorative layer 500 for inkjet printing. The drying device (such as a radiation curing device or an infrared dryer) depends on the type of ink pack used in the web-fed inkjet printing system.

[0025] The transport of the decorative layer 500 to a press (preferably a hot press) after forming the layer assembly can be performed by one or more connecting stations and / or one or more transport tables and / or one or more conveyor modules until the designated press is reached. After pressing, the decorative panel can be supplied to the stacking area.

[0026] The roll-to-roll inkjet printing system preferably includes a roll-to-roll guide and / or a roll-to-roll substrate 300 spreading device for providing straight transport under multiple inkjet printheads. Due to poor color-to-color registration, oscillation of the roll-to-roll substrate 300 and roll-to-roll floating can cause color deviations in the decorative layer 500.

[0027] A roll-to-roll inkjet printing system includes a printing table for supporting a roll-to-roll substrate without wrinkles under the inkjet printhead unit. The printing table can be a vacuum table for better holding the roll-to-roll substrate 300 during printing in a multi-pass roll-to-roll inkjet printing system. The printing table can also be a conveyor belt, whereby the roll-to-roll substrate is supported and preferably pressed by vacuum. When vacuum power is used to press the roll-to-roll substrate 300, the conveyor belt is also referred to as a vacuum belt. The principles of conveyor belts, vacuum belts, printing tables, and vacuum tables are known to those skilled in the art.

[0028] A roll-fed inkjet printer can be a single-pass inkjet printer, but is preferably a multi-pass inkjet printer.

[0029] The roll-to-roll inkjet printer preferably includes: an input area 710 with an input roller 150; a stepping unit 720; a printing area 730 with an inkjet printhead unit 400; and an output area 740 with an output roller 250.

[0030] Jumping unit

[0031] In this embodiment, a bouncing unit 720 is present within the feed path 155 of the roll paper substrate 300. The bouncing unit 720 controls and maintains the tension of the substrate to avoid one or more wrinkles in the substrate. Such a bouncing unit 720; wherein the control steps are performed by the bouncing unit 720 within the feed path 155, wherein the bouncing unit 720 includes a bouncing roller 200 having:

[0032] - An axis, positioned parallel to a first direction, which is the transverse direction of the feed base; and,

[0033] - Connectors 120 are provided on both sides of the shaft, wherein the two connectors 120 are connected to a pair of parallel guides 110 for floating the roller along a floating path 210 perpendicular to the first direction.

[0034] The bouncing unit may include other rollers 205 for guiding the roll paper substrate 300 through the bouncing unit.

[0035] The maximum diameter of the bouncing roller 200 is preferably between 10 mm and 500 mm. More preferably, the diameter is smaller at the side edge of the bouncing roller 200 than at the middle of the bouncing roller 200, so as to achieve a roll paper spreading effect.

[0036] In this embodiment, one of the paired guides 110 is capable of moving parallel to the floating path 210 perpendicular to the first direction, thereby tilting the shaft at its side end having a connector 120 connected to the moving guide 110. This movement is possible when feeding the web substrate 300 through a web-feed inkjet printer. Thus, tension at the edges of the web substrate 300 is better controlled during feeding, and wrinkles are prevented. Consequently, the bouncing roller 200 is forced at an angle (i.e., tilted to one side; rather than horizontal) when floating in the floating path 210. Due to this floating and tilting at one side of the shaft, a better solution is found than tilting the clamping roller in the feed path 155 or the roller in the bouncing unit 720 (wherein, the roller is not a bouncing roller) to one side. This is especially true when the web-feed inkjet printer is a multi-pass inkjet printer, where the feeding of the web substrate 300 is performed using continuous distance movement.

[0037] Because of the possibility of movement of one of the guides 110 during feeding, even small and inconspicuous wrinkles can be avoided. Due to these wrinkles, it is understood that layer delamination occurs within the decorative panel from the pressed layer components, which degrades the quality of the manufactured decorative panel. Therefore, any wrinkles, cracks, or folds in the roll paper substrate 300 before or after printing the decorative layer 500 must be avoided. This embodiment solves this problem very efficiently.

[0038] The tilt at one side is preferably limited to a distance of 4 times the diameter of the bouncing roller 200, wherein the diameter is measured at the middle of the shaft.

[0039] In a preferred embodiment, each connector 120 is a gear, and the paired parallel guides 110 are paired racks (see [link]). Figure 1 and Figure 2 ).

[0040] During the feeding of the roll paper substrate 300, the roll paper substrate 300 can be sensed at its edge to determine the tension at the edge. Subsequently, the guide 110 moves according to the determination to control and maintain the tension of the roll paper substrate 300. The sensing is preferably performed by a non-contact method (such as image-captured edge), thereby determining the undulation of the edge, which in turn determines the tension at the edge.

[0041] The jumping unit 720 is preferably located between the following:

[0042] - Input roller 150, from which the paper roll substrate 300 is fed; and

[0043] - The printing area of ​​a roll-to-roll inkjet printer, in which a decorative layer 500 is printed. In a preferred embodiment, the thickness of the input roller 150 is determined during feeding, after which the guide 110 moves according to the determination.

[0044] The humidity in the web paper substrate 300 can also cause relaxation tension within the web paper substrate 300, which can be controlled by the operator using the movement of the guide 110. The humidity in the web paper substrate 300 may be uneven and may vary between several 'print-ready' rollers of the web paper substrate.

[0045] The web-fed inkjet printer may also include one or more heated rollers or dehumidifier components along the feed path 155, which may be implemented at the agitation unit 720. The agitation roller 200 in the agitation unit 720 may also be heated. The temperature is preferably between 40°C and 70°C. If the web substrate 300 is thermoplastic foil, the temperature is preferably between 40°C and 60°C to avoid dimensional changes in the web substrate 300.

[0046] Figure 1 and Figure 2 The diagram shows the Jeti TAURO constructed on AGFA NV. TM The bouncing unit 720 in H2500. The bouncing unit 720 may be part of a preferred embodiment of the invention and includes a bouncing roller 200 having connectors 120 at both ends of the roller 200 connected to the guide 110. Figure 1 This is a close-up view of the left side of the bouncing roller 200, wherein the guide 110 is configured to move up and down (indicated by white arrows) by rotating the main shaft with handle 105 clockwise and counterclockwise, and... Figure 2 This is a close-up view of the right side of the bouncing roller 200, where the guide 110 is not movable. By making it as shown on the left side of the bouncing roller 200... Figure 1 The guide 110 shown in the figure is movable, which can tilt the bouncing roller 200. The two guides 110 form a pair of guides parallel to each other. The connectors 120 on the left and right sides are shown here as gears, and the guides 110 on the left and right sides are shown here as racks.

[0047] Figure 4 The bouncing unit 720 is also illustrated in a front view. A roll paper substrate is present, entering the bouncing unit 720 from an input area (not shown) on a guide roller 205; below the bouncing roller 200 and returning on another roller (not shown), the roll paper substrate is further fed towards the printing area (not shown). The bouncing roller 200 is tilted to one side at an angle α by a movement 115 of one of the guides 110 to which it is attached, and is capable of floating along a floating path 210. In a preferred embodiment, the angle is between 0.05 degrees and 15 degrees. This angle may be less large to avoid separation of the bouncing roller 200 from the paired guides 110.

[0048] Floor panels: vinyl tiles and vinyl strips, as well as vinyl rollers

[0049] In a preferred embodiment, the decorative panels are selected from the group consisting of kitchen panels, floor panels, furniture panels, ceiling panels, and wall panels, wherein the floor panels are preferably selected from the group consisting of vinyl tiles, vinyl strips, and vinyl rollers; and...

[0050] The layer assembly includes a decorative layer 500 and one or more thermoplastic foils. A possible manufacturing process is disclosed in WO2016188743 A1 (AGFANV). The one or more thermoplastic foils may be polyvinyl chloride foils.

[0051] In this document, the roll paper substrate 300 is preferably a thermoplastic foil, more preferably a polyvinyl chloride foil. The layer assembly may also include a protective layer, and preferably includes a polyurethane finishing layer on top of the protective layer.

[0052] To achieve good image quality, the decorative layer 500 is preferably formed from droplets from a free radical UV-curable inkjet ink assembly; and wherein the decorative layer 500 is at least partially UV-cured on the roll paper substrate 300 before forming the layer assembly. In a preferred embodiment, the decorative layer 500 is cured using a UV LED.

[0053] To enhance the flexibility of the decorative panel, one of the thermoplastic foils within the layer assembly is coated with a layer containing vinyl chloride-vinyl acetate-vinyl alcohol.

[0054] To better bond the layers in the layer assembly, the pressing step can be a hot pressing step.

[0055] Floor panels with core layers of MDF, HDF, and OSB

[0056] In a preferred embodiment, the decorative panel is selected from the group consisting of kitchen panels, floor panels, furniture panels, ceiling panels, and wall panels; and...

[0057] The layer assembly includes a decorative layer 500 and one or more layers selected from the group consisting of a balancing layer, a paper layer, a resin-impregnated paper layer, a protective layer, and a core layer. The core layer is preferably selected from the group consisting of MDF (medium-density fiberboard), HDF (high-density fiberboard), and OSB (oriented strand board).

[0058] Prior to forming the layer components, the printed decorative layer 500 is resin impregnated with a thermosetting resin preferably selected from the group consisting of melamine-formaldehyde resin, urea-formaldehyde resin and phenol-formaldehyde resin.

[0059] The pressing step is a hot pressing step. Therefore, the preferred embodiment may be part of a CPL (Compact Lamination) or HPL (High Pressure Lamination) process.

[0060] Therefore, the paper roll substrate 300 is preferably paper, and more preferably has a porosity according to the Gurley method (DIN 53120) between 8 seconds and 35 seconds and a porosity of 35 g / m³. 2 With 160 g / m 2 The weight of the paper.

[0061] Therefore, the decorative layer 500 is preferably formed from droplets from an aqueous dyeing inkjet ink assembly, which preferably includes cyan (C) ink, magenta (M) or red (R) ink, yellow (Y) ink, and black (K) ink. The ink assembly may also include diluted inks, such as light cyan ink, light black ink, or light magenta ink.

[0062] Before the web paper substrate 300 is fed into the web paper feed inkjet printer, the web paper substrate 300 is preferably coated with one or more inkjet receiving layers.

[0063] Core layer

[0064] Particleboard, plywood, or even solid wood can be used as the core layer. However, solid wood is less preferred because it shrinks and causes fluctuations to appear on the surface of the decorative panel. Particleboard and plywood are preferred, especially for specific decorative panel requirements such as: stability, flatness, rigidity, mechanical properties, thickness consistency, water and moisture resistance, and fire resistance.

[0065] As disclosed in WO 2013 / 050910 (UNILIN), the core layer may also be assembled from at least a plurality of paper sheets or other carrier sheets impregnated with a thermosetting resin. For example, as described in US 4952277 (BET PAPERCHEM), preferred paper sheets include so-called kraft paper obtained through a chemical pulping process (also known as the kraft paper process). The core layer may also be impregnated with a resin, more preferably with a thermosetting resin.

[0066] In another preferred embodiment, the core layer is a board material consisting essentially of wood fibers bonded by means of a polycondensation adhesive, wherein the polycondensation adhesive forms 5 to 20 percent by weight of the board material, and at least 40 percent by weight of the wood fibers are obtained from recycled wood.

[0067] Instead of a wood-based core layer, a synthetic core layer may also be used. In a preferred embodiment, the core layer comprises a foamed synthetic material, such as foamed polyethylene or foamed polyvinyl chloride.

[0068] The thickness of the core layer is preferably between 2 mm and 12 mm, and more preferably between 5 mm and 10 mm.

[0069] Ink receiving layer

[0070] One or more ink receiving layers may be present on the roll paper substrate 300 of the decorative layer 500 to enhance image quality.

[0071] It has been found that applying one or more ink-receiving layers to a roll paper substrate 300 inevitably affects the tension within the substrate at its edges. Therefore, this embodiment is an important solution to avoid wrinkles caused by varying tensions within the substrate. The application is mostly performed offline, so the roll paper substrate 300 is unrolled, coated with the one or more ink-receiving layers, and then wound up before entering the roll-to-roll inkjet printing process. This unrolling-winding process also introduces varying tensions within the substrate and tension differences between the rolls of the substrate.

[0072] Multiple ink receiving layers may be pure polymer-based ink receiving layers, but preferably include inorganic pigments and polymer binders. The inorganic pigments may be a single type of inorganic pigment or a variety of different inorganic pigments. The polymer binders may be a single type of polymer binder or a variety of different polymer binders.

[0073] In a preferred embodiment, the ink receiving layers have a density of 2.0 g / m³. 2 With 10.0 g / m 2 Between, more preferably at 3.0 g / m 2 With 6.0 g / m 2 The total dry weight between.

[0074] In a particularly preferred embodiment, the ink receiving layer comprises a polymeric adhesive (preferably a water-soluble polymeric adhesive (>1 g / L water at 25°C)) having hydroxyl groups as hydrophilic structural units, such as polyvinyl alcohol.

[0075] Inorganic pigments are preferably selected from the group consisting of alumina hydrate, alumina, aluminum hydroxide, aluminum silicate and silicon dioxide.

[0076] The (multiple) ink receiving layers may consist of a single layer, or even two, three, or more layers with different compositions. The (multiple) ink receiving layers may be applied to the support side of the substrate using any conventional coating technique, such as dip coating, doctor blade coating, extrusion coating, spin coating, slide coating, and curtain coating. Alternatively, the (multiple) ink receiving layers may also be applied using printing techniques, such as flexographic printing, screen printing, and inkjet printing processes (such as valve-jet printheads).

[0077] Surface matching

[0078] The top surface of the layer assembly preferably has an embossed pattern matching the decorative layer 500, such as a representation of wood grain, cracks, and knots. Embossing techniques for achieving such embossing, as disclosed in, for example, EP 1290290 A (FLOORING IND), US2006144004 (UNILIN), EP 1711353 A (FLOORING IND), and US 2010192793 (FLOORING IND), are well known in the flooring panel industry. Most preferably, the embossing is formed by pressing a digital embossed panel, column, or strip against the top surface of the layer assembly. This can be performed in the pressing step of this embodiment, wherein the layers of the layer assembly are constrained. The pressing step is preferably a hot pressing step.

Claims

1. A method for manufacturing a decorative panel, comprising the following steps: - Feed the web paper substrate (300) along the feed path (155) in a web-feed inkjet printer; - A decorative layer (500) is printed on the roll paper substrate using the roll paper feed inkjet printer; - A layer assembly is formed by applying one or more other layers to a roll paper substrate with a printed decorative layer and / or by applying the roll paper substrate with the printed decorative layer to one or more other layers; - Press the layer assembly to constrain the layers of the layer assembly to form a decorative panel; as well as - During feeding, the tension of the roll paper substrate is controlled to avoid one or more wrinkles in the roll paper substrate; wherein the control step is performed by a jumping unit (720) within the feed path (155), wherein the jumping unit (720) includes a jumping roller (200) having: - An axis, positioned parallel to a first direction, the first direction being transverse to the feed roll paper substrate; and... - Connectors (120) are provided on both sides of the shaft, wherein the two connectors (120) are connected to a pair of parallel guides (110) for floating the roller along a floating path (210) perpendicular to the first direction; and, The control steps include: - Move one of the paired parallel guides (110) parallel to the floating path (210) to tilt the axis at the position where the axis is connected to the moving guide (110).

2. The method according to claim 1, in, The decorative panels are selected from a group consisting of kitchen panels, floor panels, furniture panels, ceiling panels, and wall panels; and... The layer assembly includes the decorative layer (500) and one or more layers selected from the group consisting of paper layers and resin-impregnated paper layers; and, Prior to forming the layer assembly, the printed decorative layer (500) is resin impregnated with a thermosetting resin selected from the group consisting of melamine-formaldehyde resin, urea-formaldehyde resin and phenol-formaldehyde resin. The pressing step is a hot pressing step.

3. The method according to claim 2, in, The roll paper substrate (300) has a porosity between 8 seconds and 20 seconds according to the Gurley method DIN 53120 and a porosity of 40 g / m³. 2 With 150 g / m 2 The weight of the paper.

4. The method according to claim 3, in, The decorative layer (500) is formed from droplets from an aqueous dyeing inkjet ink assembly.

5. The method according to claim 4, in, Before the web paper substrate (300) is fed in the web paper feed inkjet printer, the web paper substrate (300) is coated with one or more inkjet receiving layers.

6. The method according to claim 1, in, The decorative panels are selected from the group consisting of kitchen panels, floor panels, furniture panels, ceiling panels, and wall panels, wherein the floor panels are selected from the group consisting of vinyl tiles, vinyl strips, and vinyl rollers; and... The layer assembly includes the decorative layer (500) and one or more thermoplastic foils.

7. The method according to claim 6, in, The roll paper substrate (300) is a thermoplastic foil.

8. The method according to claim 7, in, The decorative layer (500) is formed from droplets from a free radical UV-curable inkjet ink assembly; and wherein, prior to forming the layer assembly, the decorative layer (500) is at least partially UV-cured on the roll paper substrate (300).

9. The method according to claim 8, in, One of the thermoplastic foils within the layer assembly is coated with a layer comprising vinyl chloride-vinyl acetate-vinyl alcohol.

10. The method according to claim 1, in, The movement of the guide (110) is limited to a distance of four times the diameter of the bouncing roller (200), wherein the diameter is measured at the midpoint of the shaft.

11. The method according to claim 10, in, The diameter is larger than the diameter of the bouncing roller (200) at the side edge of the shaft.

12. The method according to claim 1, in, The edge of the roll paper substrate (300) is sensed during the feeding process to determine the tension at the edge, after which the guide (110) moves according to the determined tension at the edge.

13. The method according to claim 1, in, The jumping unit (720) is located between the following: - An input roller (150) from which the paper roll substrate (300) is fed; and - The printing area of ​​the web-fed inkjet printer, in which the decorative layer (500) is printed; and, Thus, the thickness of the input roller (150) is determined during the feeding period, and thereafter the guide (110) moves according to the thickness of the input roller determined during the feeding period.

14. The method according to claim 1, in, Each connector (120) is a gear, and the paired parallel guides (110) are paired racks.

15. The method according to claim 1, in, The roll-fed inkjet printer is a multi-pass inkjet printer.

16. The method according to claim 1, in, The layer assembly includes the decorative layer (500) and one or more layers selected from the group consisting of a balancing layer, a protective layer, and a core layer, wherein the core layer is selected from the group consisting of medium-density fiberboard, high-density fiberboard, and oriented strand board.

Images