Method for applying patterns to a workpiece

Abstract

The invention relates to a method for applying patterns to a workpiece (2) that preferably consists at least partly of wood, a wood material, or plastic, having the steps of: providing a workpiece (2) and a coating material (4), applying the coating material (4) onto the workpiece (2), in particular in the region of a narrow surface (2') of the workpiece (2), and printing the coating material (4) with a printing material by means of at least one printing unit (10, 20) which functions according to the drop-on-demand printing principle, wherein the printing material has matte properties.

Description

[0001] Method for sampling a workpiece

[0002] Technical area

[0003] The invention relates to a method for patterning a workpiece, which preferably consists at least in sections of wood, wood-based material or plastic, and to a device for carrying out the method.

[0004] State of the art

[0005] In the furniture and construction component industries, workpieces, usually made of wood, wood-based materials, plastic, or various composite materials, are typically coated and patterned on their surfaces. The pattern can either be pre-applied to the coating material or applied after or during the coating process.

[0006] For this purpose, various devices for printing workpieces are known. For example, EP 1 867 488 A discloses a device for patterning the surface of workpieces, in which a printing unit prints a coating material while the material is being fed to a workpiece to be coated. The device comprises a plurality of conveyor and pressure rollers.

[0007] The workpieces are often also provided with natural patterns that replicate, for example, wood or stone. The goal is for such patterned workpieces to have as realistic an appearance as possible.

[0008] For this purpose, EP 1 990 204 A discloses a method and a device for influencing the gloss level of the patterned surface. However, it has been shown that such methods and devices entail comparatively high expenditure, for example, due to additional components or additional process steps.

[0009] Description of the invention

[0010] The invention is based on the object of providing a method and a device for patterning a workpiece which enable a natural or desired appearance of the workpiece to be patterned with little effort.

[0011] This object is achieved according to the invention by a method for patterning a workpiece according to claim 1 and by a device for carrying out the method according to claim 11. Particularly preferred developments of the invention are specified in the dependent claims.

[0012] The inventive use of a matt printing material makes it possible to achieve a matt and therefore particularly natural appearance for the patterned workpiece in a particularly simple and direct manner. The result is an overall matt appearance for the patterned workpiece, which corresponds most closely to the natural appearance of most natural materials such as wood or stone. In contrast, common printing processes which work according to the drop-on-demand printing principle have not yet permitted the use of matt printing materials and therefore require complex additional measures which can be dispensed with thanks to the invention. The result is a process for patterning a workpiece which in itself enables a matt and therefore natural appearance for the patterned workpiece and reduces the process complexity.

[0013] The degree of mattness of the printing material can be suitably selected by a person skilled in the art within the scope of the invention. However, a particularly natural appearance of the patterned workpiece is achieved if, according to a further development of the invention, the printing material, at least in the cured or dried state, has a gloss level according to ISO 2813 of at most 70 GU, preferably at most 50 GU, particularly preferably at most 30 GU, with a substantially uniform layer thickness.

[0014] According to a further development of the invention, it is further provided that the printing material contains ink and / or varnish, so that diverse and lasting optical effects can be achieved. The method according to the invention becomes particularly versatile when the printing material is transparent, since it is then possible to work with multiple printing layers in order to finally create the desired mattness using a matte and transparent printing material. In addition, transparent printing material is particularly easy to produce as a matte printing material.

[0015] According to a development of the invention, the printing material is cured after printing by means of a curing unit, preferably by irradiation such as in particular by UV radiation. This results in the applied printing material being very durable, but on the other hand it can also speed up the process and successive process steps can be carried out in faster succession. The use of irradiation has proven to be particularly simple and effective, particularly in the case of UV radiation. Although the present invention already enables the patterned workpiece to have a natural and matt appearance through the selection of the printing material, further measures can also be used within the scope of the invention to support the mattness of the patterned workpiece or to increase the variability of the mattness.Against this background, according to a further development of the invention, it is provided that a first workpiece is irradiated with a first wavelength spectrum and / or intensity and a subsequent second workpiece is irradiated with a second wavelength spectrum and / or intensity, so that the printed area of ​​the first workpiece has a different degree of gloss than the printed area of ​​the second workpiece.

[0016] Furthermore, according to a further development of the invention, excimer radiation, which preferably has a wavelength in the range of 150-190 nm, is used at least partially during curing. The use of excimer radiation allows the (matt) gloss level of the patterned surface to be additionally influenced in a targeted manner, thereby further increasing the variability of the method according to the invention and allowing the desired gloss level to be adjusted with particular precision.

[0017] Furthermore, according to a further development of the invention, the curing of the printing material after printing takes place at least partially in an inert environment, in particular in a nitrogen environment. This allows for particularly rapid and homogeneous curing, especially when using excimer radiation. Thanks to the homogeneous curing, a particularly uniform appearance with homogeneous matting is achieved.

[0018] To further influence the degree of gloss in a targeted manner, a further development of the invention provides for the surface of the printing material to be provided with a topography after and / or during printing. This measure allows, among other things, particularly matte surfaces to be created. In addition, the surface can also be given haptic properties.

[0019] It is particularly preferred that the topography is carried out by irradiation and / or mechanical processing of the surface of the printing material.

[0020] According to a development of the invention, the coating material is printed several times in succession with a printing material according to the drop-on-demand printing principle, and matte printing material is used in at least one printing process, in particular the last printing process. This process makes it possible to create special visual effects and a particularly high-quality appearance. For example, the first printing process can be carried out using a particularly high-quality, highly pigmented and, if appropriate, glossy printing material in order to provide the desired colors with high intensity. Subsequently, for example, matte and preferably transparent printing material can be used in a second or final printing process in order to give the previously applied print image a matte appearance.This allows the advantages of different printing concepts to be combined, whereby a first printing concept can, for example, provide a particularly high resolution, color brilliance or the like, while the other printing process ultimately ensures the desired (matt) gloss level.

[0021] A device for carrying out the method according to the invention is the subject of independent claim 11. By using this device, the advantages described above can be achieved particularly effectively.

[0022] According to a further development of the invention, the device comprises a curing unit for curing the printing material after printing, which preferably emits radiation, such as UV radiation. The resulting advantages have already been described above.

[0023] Alternatively or additionally, according to a further development of the invention, the device comprises a joining device for applying the coating material to the workpiece. This results in an integrated machine concept in which raw workpieces can be both coated and patterned on one machine, thereby reducing the number of required devices and increasing throughput. The coating material can be printed before, during, and / or after the coating process using the joining device.

[0024] According to a further development of the invention, it is further provided that the device has at least two printing units which are set up to print the coating material one after the other, wherein at least the printing unit set up for the last printing process has access to matt printing material. This initially makes it possible to achieve the advantages described above for carrying out a plurality of printing processes one after the other. In addition, however, the provision of a plurality of printing units enables even greater flexibility, since in addition to matt patterns, glossy patterns can also be produced, for example by only using one printing unit for glossy patterns, while the other printing unit, which works with matt printing material, remains deactivated in this case.

[0025] Furthermore, according to a further development of the invention, the device comprises a detection unit configured to detect at least the gloss level of the printed and preferably at least partially cured coating material. This allows the sampling result to be reliably verified, for example, with regard to the actual gloss level achieved, so that appropriate measures can be taken on this basis if necessary.

[0026] In this regard, according to a further development of the invention, the device comprises a control device connected to the at least one printing unit and the detection unit and configured to control the at least one printing unit based on a detection result of the detection unit. Thus, the printing process can be controlled or regulated particularly precisely, enabling particularly high-quality workpieces to be produced and waste to be minimized.

[0027] Short description of the drawings

[0028] Fig. 1 shows schematically a plan view of an apparatus for patterning a workpiece according to an embodiment of the invention.

[0029] Detailed description of preferred embodiments

[0030] Preferred embodiments of the invention are described in detail below with reference to Fig. 1, which schematically illustrates a device 1 for patterning a workpiece 2 in a plan view.

[0031] The workpiece 2 can be in the form of a plate or strip and can be made, for example, of wood, wood-based material, plastic or other comparable materials. Such workpieces are widely used in the furniture and building element industry, for example as carcass parts, furniture fronts, doors, etc. As can be seen in Fig. 1, such workpieces 2 are often provided with a coating material 4, which can also be made of wood, wood-based material or plastic, but also of other suitable materials such as metal, etc. Such coating materials 4 are particularly frequently used in the region of the narrow surface of the workpiece 2 and are then usually referred to as the edge. In the present embodiment, the device 1 is used for patterning the coating material 4, but is also suitable in principle for patterning various other surfaces of the workpiece 2.

[0032] In the present embodiment, the device 1 comprises two printing units 10, 20 for printing the coating material 4 with a printing material, which are described in more detail below.

[0033] Furthermore, the device 1 comprises a conveyor unit 6, which conveys the workpiece 2 and, if applicable, subsequent workpieces 2' in a throughput direction (from right to left in Fig. 1) along the print heads 10, 20. For this purpose, the conveyor device 6 can, for example, comprise conveyor troughs, conveyor chains, and various other conveyor elements.

[0034] Although not shown in Fig. 1, the conveyor device 6 can also serve to guide the printing units 10, 20 and optionally further units along a stationary workpiece 2. For this purpose, the printing units 10, 20 and optionally further units can be arranged on a carrier which can be moved in the plane of the workpiece 2 and rotated about an axis running perpendicular to the plane of the workpiece. Mixed forms of the two concepts are also possible within the scope of the invention. The printing units 10, 20 each have a print head 12, 22. These work according to the drop-on-demand printing principle, in which individual drops of printing material can be ejected as required. For this purpose, for example, piezo print heads, thermal print heads or other suitable print heads can be used.

[0035] Furthermore, the printing units 10, 20 each have a printing material supply 14, 24 in which suitable printing material is stored and fed to the print heads 12 and 22 respectively. At least the supply 24 of the second printing unit 20 contains a printing material that has matte properties. The supply 14 of the first printing unit 10 can likewise contain corresponding printing material or also a different type of printing material, possibly glossy. Furthermore, it should be noted that the respective supply 14 or 24 can also contain a plurality of similar or different printing materials, for example different colors such as preferably cyan, magenta, yellow and black or also transparent printing materials. Furthermore, the printing materials can be, for example, ink, varnishes and a wide variety of other printing materials, which can have different colors and can be both transparent and opaque.In any case, the printing material stored in the second printing reservoir is preferably matt and transparent.

[0036] In the present embodiment, the matt printing material in the cured or dried state with a substantially uniform layer thickness has a gloss level according to ISO 2813 of no more than 70 GU, although depending on the application, significantly lower gloss levels of, for example, no more than 50 GU down to values ​​of less than 30 GU may be appropriate. The uniform layer thickness for determining the inherent gloss level of the printing material can be achieved, for example, by applying the printing material to a substrate using a squeegee, then fully or partially curing or drying it and determining the gloss level according to ISO 2813. Alternatively, the uniform layer thickness can also be achieved by a printing process that is set as uniformly as possible in order to then carry out a measurement according to ISO 2813 and determine the gloss level.The matt printing material is therefore a material which, even without additional measures such as roughening, targeted topography or the like, has a low gloss level of, for example, a maximum of 70 GU according to ISO 2813.

[0037] To achieve this material property, the printing material can, for example, contain the largest possible particles, which, due to their reduced reflective properties compared to small particles, result in a matte material property of the printing material. At the same time, the particles should not be too large, so that the printing material can still be processed using the drop-on-demand printing process, which is generally based on small droplet sizes and small nozzle outlet openings.

[0038] Furthermore, the device 1 in the present embodiment comprises a curing unit 30 for curing the printing material after printing, which in the present embodiment has one or more UV lamps. The curing device 30 and the adjacent area in which the curing process takes place can be shielded by a housing 32 within which a nitrogen environment or another suitable inert environment prevails. The residual oxygen content in the inert environment can, for example, be at most 1%, preferably at most 0.5%.

[0039] The printing material applied by the printing units 10, 20 can be cured by simple irradiation with UV radiation. If necessary, the curing unit 30 can also be operated with different wavelengths or wavelength spectra and, if necessary, with different intensities, so that the gloss level of the printed area of ​​successive workpieces 2, 2' can be specifically influenced by different operating parameters of the curing unit 30.

[0040] Alternatively or additionally, the curing unit 30 can also be set up to allow various other radiation to act on the printing material. For example, excimer radiation can also be used here, which can have a wavelength of 172 nm, for example. The excimer radiation can thus be used to harden a surface layer of the applied printing material and, in the subsequent step, to harden the entire printing material using UV light. As a result of this measure, a different deformation behavior occurs in the surface layer than in the layers below, which leads to a topography in the cover layer and thus to a reduced degree of gloss. In this way, the (matt) degree of gloss of the applied printing material can be further reduced and influenced in a targeted manner.

[0041] Within the scope of the invention, other measures for influencing the degree of gloss or for achieving a topography of the applied printing material are also possible, for example, other types of irradiation, mechanical action, or even a targeted operation of the printing units 10 or 20 in such a way that a topography is established. Such settings are particularly useful when particularly low gloss levels are desired.

[0042] As can be seen in Fig. 1, the device 1 in the present embodiment further comprises a joining device 40 for applying the coating material 4 to the workpiece 2. It should be noted, however, that the joining device 40 is optional and can, for example, also be provided in a separate device. The joining device 40 in the present embodiment comprises a pressure roller 42 and an energy source 44, such as a hot air source, a laser, an infrared source, a microwave source, a plasma source or the like. The energy source 44 can serve to activate (make adhesive) the side of the coating material 4 facing the energy source 44. For this purpose, the coating material 4 can be pre-coated with an appropriate adhesive or consist of a suitable material that develops adhesive properties when subjected to energy.

[0043] Alternatively or additionally, the joining device 40 can also have an adhesive application roller 46, by means of which an adhesive such as hot melt can be applied to the side of the coating material 4 facing the workpiece 2'. The energy source 44 can then be either passive or used to keep the applied adhesive activated or to further activate it. The pressure roller then serves to press the coating material 4, supplied with an activated adhesive, onto the workpiece 2' and thus attach it.

[0044] Furthermore, the device 1 in the present embodiment also comprises a detection unit 50 for detecting the degree of gloss of the printed and at least partially cured coating material 4. The detection unit 50 can be, for example, a camera or a sensor suitable for detecting parameters such as the degree of gloss, the color spectrum, etc. of the printed coating material 4.

[0045] The detection unit 50 is connected to a control device 60, for example a machine controller, which in turn can also be connected to the conveyor unit 6, the printing units 10, 20 and the curing unit 30. In this way, the control device 60 is enabled to control the printing units 10, 20 on the basis of a detection result of the detection unit 50. This makes it possible not only to detect the actually achieved gloss levels or color spectra of the patterned coating material 4, but also to influence at least one of the printing units 10, 20 and / or the curing unit 20 in the event of target / actual deviations. If necessary, other machine parameters can also be corrected, such as the conveyor speed of the conveyor unit 6.

[0046] Overall, a workpiece 2 can therefore be conveyed into the device according to the invention by means of the conveying unit 6 and provided with a coating material 4 in the area of ​​the joining unit 40. The workpiece 2 then reaches the printing units 10, 20 and is patterned there with one or more printing materials in the area of ​​the coating material 4, with at least the second (last) printing unit 20 outputting a matt and preferably transparent printing material. The applied printing material is then cured or dried in the area of ​​the curing unit 30, whereupon, for example, the degree of gloss of the applied printing material is detected by the detection unit 50. The detection result of the detection unit 50 is passed on to the control unit 60, which controls the further operation of the device 1 on this basis.

[0047] In the next step, a subsequent workpiece 2' basically goes through the same process, whereby, as required, other parameters can be used to give the subsequent workpiece 2' the desired pattern. For example, other printing materials can be used, or if required, only the first printing unit 10 can be used, so that glossy patterns can also be applied if required. Furthermore, the

[0048] Curing units work with different operating parameters in order to achieve different properties, such as gloss levels, on different workpieces and, if necessary, even within individual workpieces.

Claims

CLAIMS Method for sampling a workpiece (2) which preferably consists at least partially of wood, wood-based material or plastic, comprising the steps: Providing a workpiece one coating material (4) , Applying the coating material (4) to the workpiece (2), in particular in the area of ​​a narrow surface (2') of the workpiece (2) , and Printing the coating material (4) with a printing material using at least one printing unit (10, 20) operating according to the drop-on-demand printing principle, characterized in that the printing material has matte properties. A method according to claim 1, wherein the printing material, at least in the cured or dried state and with a substantially uniform layer thickness, has a gloss level according to ISO 2813 of at most 70 GU, preferably at most 50 GU, and particularly preferably at most 30 GU. A method according to claim 1 or 2, wherein the printing material comprises ink and / or varnish and is preferably transparent. A method according to any one of the preceding claims, wherein the printing material is cured after printing using a curing unit (30), preferably by irradiation, in particular by UV radiation. The method according to claim 4, wherein a first workpiece (2) is irradiated with a first wavelength spectrum and / or intensity, and a subsequent second workpiece (2') is irradiated with a second wavelength spectrum and / or intensity, such that the printed area of ​​the first workpiece (2) has a different gloss level than the printed area of ​​the second workpiece (2'). A method according to claim 4 or 5, wherein excimer radiation, preferably having a wavelength in the range of 150 to 190 nm, is used at least partially during curing. A method according to any one of claims 4 to 6, wherein the curing of the printing material after printing takes place at least partially in an inert environment, in particular in a nitrogen environment. A method according to any one of the preceding claims, wherein the surface of the printing material is treated with a topography is provided to reduce its gloss level and / or influence its feel. Method according to claim 8, wherein the topography is achieved by irradiation and / or mechanical treatment of the surface of the printing material. Method according to any of the preceding claims, wherein the coating material (4) is printed repeatedly with a printing material according to the drop-on-demand printing principle, and matte printing material is used in at least one printing process, in particular the last printing process. Device (1) for carrying out the method according to any of the preceding claims, comprising: at least one printing unit (10, 20) for printing the coating material (4) with a printing material, which operates according to the drop-on-demand printing principle, a conveying unit (6) for bringing about a Relative motion between the at least one Printing unit (2) and the coating material (4), characterized in that at least one printing unit (20) has a supply (24) of printing material that can be used by the printing unit (20) for printing and has matte properties. Device according to claim 11, in which a curing unit (30) is provided for curing the printing material after printing, which preferably emits radiation, in particular UV radiation. Device according to claim 11 or 12, in which a Joining device (40) for attaching the A device according to any one of claims 11 to 13, wherein at least two printing units (10, 20) are provided which are configured to print the coating material (4) successively, wherein at least the printing unit (20) configured for the last printing process has access to matte printing material. A device according to any one of claims 11 to 14, wherein a detection unit (50) is provided which is configured to detect at least the gloss level of the printed and preferably at least partially cured coating material (4). Device according to one of claims 11 to 15, in which a control device (60) is provided which is connected and configured to the at least one pressure unit (10, 20) and the detection unit (50), which displays at least one pressure unit (10, 20) on the Basis of a data collection result of the To control the acquisition unit (50).

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