METHOD AND MACHINE FOR PRODUCING RELIEFS AND PANEL COMPRISING SAID RELIEFS

Abstract

A method for producing a relief on a substrate, the relief having a recess area and a no-recess area, the recess area being adjacent to the no-recess area and forming a recess with respect to the no-recess area. The method extending a relief base layer on the substrate, digitally printing with a first volume per area of printed product on the outer surface of the extended relief base layer to obtain the recess area, the recess area forming the recess with respect to the outer surface of the extended relief base layer, and digitally printing with a second volume per area of printed product on the outer surface of the extended relief base layer at least adjacently to the recess area, to obtain the no-recess area.

Claims

1. A method for producing a relief on a substrate, the relief comprising a recess area and a no-recess area, the recess area being adjacent to the no-recess area and forming a recess with respect to the no-recess area, comprising: extending a relief base layer on the substrate, digitally printing with a first volume per area of liquid recess printing product in the form of droplets on the outer surface of the extended relief base layer to obtain the recess area, the recess area forming the recess with respect to the outer surface of the extended relief base layer, digitally printing with a second volume per area of liquid recess printed product in the form of droplets on the outer surface of the extended relief base layer, at least adjacently to the recess area, to obtain the no-recess area.

2. The method for producing a relief on a substrate according to claim 1, further comprising removing a mixture of printed product and relief base layer, such that the recess corresponds to the volume occupied by the mixture removed in the relief base layer.

3. The method for producing a relief on a substrate according to claim 1, wherein the recess is obtained by digital embossing.

4. The method for producing a relief on a substrate according to claim 1, wherein the digital printing is performed on the liquid relief base layer.

5. The method for producing a relief on a substrate according to claim 1, wherein the relief base layer is cured together with the printed product.

6. The method for producing a relief on a substrate according to claim 1, wherein the digital printing with the second volume per area is performed simultaneously or before the digital printing with the first volume per area.

7. The method for producing a relief on a substrate according to claim 1, wherein the digital printing with the second volume per area is also performed on the extended relief base layer on which the digital printing is performed with the first volume per area.

8. The method for producing a relief on a substrate according to claim 1, wherein the second volume per area is greater than or equal to 5% of a maximum first volume per area for the recess area, and/or less than or equal to said maximum first volume per area of said maximum first volume per area.

9. The method for producing a relief on a substrate according to claim 1 wherein a droplet volume for the second volume per area is less than or equal to 70% of a maximum droplet volume for the first volume per area.

10. The method for producing a relief on a substrate according to claim 1, wherein the second volume per area and, optionally, the droplet volume for said second volume per area, is uniform along the relief base layer.

11. The method for producing a relief on a substrate according to claim 1, wherein the no-recess area obtained has a superficial roughness less than or equal to 20 microns, and/or a brightness at 60° greater than or equal to 10 GU measured.

12. The method for producing a relief on a substrate according to claim 1, wherein the relief is made in register with an image printed on the substrate, visible through the relief base layer.

13. The method for producing a relief on a substrate according to claim 1, wherein the extended relief base layer has a thickness greater than or equal to 20 microns, and/or less than or equal to 300 microns.

14. A machine for producing a relief on a substrate, further comprising a computer system that stores a computer program configured to carry out the method according to claim 1 when the computer program is run by the computer system.

15. A panel comprising a substrate with a relief on the substrate, wherein the relief is produced according to the method according to claim 1.

16. The method for producing a relief on a substrate according to claim 8, wherein the second volume per area is greater than or equal to 30% of the maximum first volume per area for the recess area, and/or less than or equal to 70% of said maximum first volume per area.

17. The method for producing a relief on a substrate according to claim 9, wherein the droplet volume for the second volume per area is less than or equal to 50% of the maximum droplet volume for the first volume per area.

18. The method for producing a relief on a substrate according to claim 11, wherein the no-recess area obtained has a superficial roughness less than or equal to 10 microns, and/or a brightness at 60° greater than or equal to 20 GU measured.

19. The method for producing a relief on a substrate according to claim 13, wherein the thickness is greater than or equal to 30 microns, and/or less than or equal to 200 microns.

Description

DESCRIPTION OF THE FIGURES

[0046] Advantages, features and additional application possibilities of the present invention are obtained from the following description in relation to the exemplary embodiments represented in the drawings.

[0047] The invention is explained in more detail below by way of an example and in reference to the attached drawings. The drawings show:

[0048] FIG. 1 shows a schematic view of an embodiment of a method for producing reliefs on substrates, as well as a production machine for carrying out such method.

[0049] FIG. 2 shows a schematic view of an embodiment of a panel with a relief on a substrate, which is obtained according to the embodiment of FIG. 1.

[0050] FIGS. 3a and 3b schematically show an interpretation of the operations of the invention.

[0051] FIG. 4 shows a relief representation used in an exemplary embodiment of the invention.

[0052] FIG. 5 shows relief representations processed from the relief representation in FIG. 4 for the exemplary embodiment.

[0053] FIG. 6 shows photographs of relief samples obtained according to the exemplary embodiment.

[0054] FIGS. 7 to 10 show detailed photographs of reliefs obtained according to the exemplary embodiment.

DETAILED DESCRIPTION OF THE INVENTION

[0055] FIG. 1 schematically represents an embodiment of the method for producing a relief (20) on a substrate (3) to form a panel (1), as well as a machine (10) for carrying out said method according to the invention.

[0056] As shown in FIG. 1, the method comprises digitising a relief representation (30), which is carried out through a computer system (16). The computer system (16) stores a computer program (17) configured to carry out the method by running the computer program (17). The digitisation of a relief representation (30) is carried out, in particular, by receiving, recording, processing, generating, etc. the relief representation (30) and/or relief representations processed in the computer system (16).

[0057] A relief representation (30) defines the recess area (21) and the no-recess area (22) of the relief (20) to be produced, i.e., by delimiting those areas and assigning a recess depth value in the recess area (21) with respect to the no-recess area (22). An example of relief representation (30) is the image shown in FIG. 4, wherein the recess area (21) is defined as black, while the no-recess area (22) is defined as white. In this case, the depth value of the recess area (21) is constant.

[0058] The method comprises extending a relief base layer (2) by means of a roller application unit (11) of the liquid material of the relief base layer (2). Then, using a digital printer (12), digital printing is performed on the relief base layer (2) with a first volume per area (41) of liquid printed product in the form of droplets per point of the relief representation (30). Also, in this case with the same digital printer (12), digital printing is performed with a second volume per area (42) of liquid printed product in the form of droplets per point of the relief representation (30). The digital printing comprises depositing or injecting the liquid printed product onto the relief base layer (2).

[0059] According to a variant of the embodiment described above, digital printing with the second volume per area (42) of printed product is performed on the entire outer surface of the relief base layer (2), i.e., for both the recess area (21) and the no-recess area (22). However, it is also envisaged that digital printing with the second volume of printed product can be performed only in a no-recess area (22) adjacent to or joined to the recess area (21), for example, arranged surrounding, bordering, around or in a contour of the recess area (21), in particular, in at least one contour subarea of the recess area (21). In contrast, the digital printing with the first volume per area (41) of the printed product is performed for the recess area (21), and said volume may be variable according to the depth value of the recess to be obtained.

[0060] The printed product deposited or injected onto the relief base layer (2) is mixed with the material of the relief base layer (2), penetrating the relief base layer (2). In this embodiment described above, the relief base layer (2) is made of a UV-curing resin material, while the injectable printed product to be mixed with the relief base layer (2) is configured to facilitate, after curing the relief base layer (2) together with the printed product, the removal of the cured mixture (40) with respect to the cured relief base layer (2) to form the relief, in particular, the recess area (21). When curing the printed product together with the relief base layer (2), an easily removable mixture(40) with respect to the material of the unmixed relief base layer (2) is produced.

[0061] Following the description of the embodiment as shown in FIG. 1, after the digital printing, the relief base layer (2) is cured with the application of UV radiation on the relief base layer (2) together with the printed product mixed therein. This application of UV radiation is carried out by a UV curing unit (13).

[0062] As shown in FIG. 1, the mixture (40) of the printed product and the relief base layer (2) are removed after the curing, such that the recess area (21) obtained corresponds to the volume occupied by the mixture (40) that was removed in the relief base layer (2), i.e., the volume on the recess area (21). The mixture (40) can be removed, for example, with a brushing unit (14) on the outer surface of the relief base layer (2).

[0063] In the embodiment described above, the substrate (3) or panel (1) on which the relief (20) is extended is displaced by a transport unit (18), for example, a conveyor belt, as it moves forward through the successive stations of the method described above.

[0064] The computer system (16) carries out the method by actuating the different units of the production machine (10) through a data communication (15) between the computer system (16) and the different units (11, 12, 13, 14).

[0065] With respect to the form of the substrate (3) to which the method is applied according to the invention, it is preferably provided as a panel (1); however, there is no limitation in the application of the production method of the invention to any form of substrate (3), for example, panel profiles (1). Also, preferably, the outer surface of the extended relief base layer (2) is envisaged to be substantially flat, such that the no-recess area (22) is substantially flat; however, there is also no limitation as to the surface on which the reliefs (20) formed by recesses according to the invention can be curved, for example, undulating, or have any other shape, such as being provided with protrusions, bumps or recesses, depressions or cavities on which the recesses according to the invention can be obtained.

[0066] Any material can be used as material for the substrate (3). For example, the application to panels (1) made of wood materials or derivatives, such as solid wood, agglomerate wood, HDF, MDF or plywood, is envisaged. The use of synthetic materials, for example, is also envisaged, especially for synthetic floors, MMLF (“Multi-Layer Modular Floor”). Examples of application of synthetic materials include LVT (“Luxury Vinyl Tiles”), SPC (“Stone Plastic Composites”), WPC (“Wood Plastic Composite”), or PE or PVC panels (1) or profiles, etc. Other applications of materials envisaged include fibre cement, aluminium or steel panels (1) or profiles, etc.

[0067] Returning to the description of the production method, it also envisages including other steps or stations of the corresponding production machine (10) as explained below, also for a preferred embodiment wherein the substrate (3) is a panel (1).

[0068] Beginning with the substrate (3), once the outer surface thereof has been prepared and cleaned, a first primer layer that may be cured can be applied on the substrate (3). This primer layer facilitates the application of an image base layer, which is applied on the primer layer and may also be cured. An image that is digitally printed with visible ink, which can also be cured, is applied on the image base layer. A protection layer of the printed image, which can also be cured, can subsequently be applied. The curing can be carried out through UV-curing.

[0069] The relief base layer (2) can be applied on this assembly of layers, as well as the subsequent steps of the method according to the invention described above. Once the mixture (40) of printed product and the relief base layer (2) have been removed, a surface finish layer can be applied on the assembly, which may also be cured, for example through UV curing.

[0070] The layers on the image base layer with the printed image, in particular, the relief base layer (2), can be transparent or translucent, such that the image can be seen on the substrate (3) from the top of the relief (20). The relief (20) and the printed image can be carried out in sync, i.e., in register with each other, such that, for example, a design effect can be provided wherein the relief (20) and the image are associated or linked to each other, for example, by overlapping when seen from the top of the substrate (3). In particular, it is thus possible to simulate a real design such as a wood texture. The image can comprise a pattern, a colour, a shape, and so on. Alternatively or in addition, it is also envisaged that a printed image can be made on the relief (20), in particular, in sync, i.e., in register between the image and the relief (20).

[0071] With respect to the first volume per area (41) of printed product and the second volume per area (42) of printed product, it may vary depending on, for example, the level, volume or size of the injection droplet, the number of injection points per area or printer resolution (e.g., measured in dpi, meaning dots per inch). The higher the volume of printed product injected at each print point, the greater the depth of its penetration within the relief base layer (2) in which the drop are injected, and therefore, the greater the depth of the recesses.

[0072] In this vein, a parameter associated with the volume per area of printed product that can be injected onto the relief base layer (2) can be defined, added to a digital printing method and/or a digital printer (12) for obtaining reliefs (20). A value of 100% is assigned to the maximum volume per area of printed product that can be obtained by means of a certain method and/or digital printer (12). An input percentage of 0% indicates that no printed product is applied. The higher the input percentage or the volume per area of printed product, the greater the recess depth that can be obtained.

[0073] Preferably, the input percentage corresponding the second volume per area (42) of printed product is relatively low compared to the input percentage corresponding to the first volume per area (41) of printed product. This way, the no-recess area (22) is not substantially recessed, perforated or worn, while providing a recess area (21) with an improved definition and therefore, reliefs (20) of a very high quality.

[0074] FIG. 2 shows a substrate (3) in the form of a panel (1). A relief (20) formed by recesses in a relief base layer (2) is applied on the substrate (3) The relief (20) is formed by recess areas (21) and no-recess areas (22). For the purposes of clarity, the figure shows the substrate (3) with the mixture (40) of the material of the relief base layer (2) and printed product in the relief base layer (2), before the mixture (40) is removed to obtain the recesses corresponding to the volume occupied by the mixture (40). Both droplets of the first volume per area (41) of printed product (for recess areas (21)) and droplets of the second volume per area (42) of printed product (for no-recess areas (22)) have been deposited on the relief base layer (2).

[0075] FIGS. 3a and 3b seek to represent an interpretation of the operating principle of the invention (FIG. 3b) compared to the state of the art (FIG. 3a). By injecting the printed product for the entire relief (20) and not only for the recess areas, it is possible to confine, hold or anchor the mixture (40) formed in the relief base layer (2), possibly preventing or reducing coalescence among the droplets of the first volume per area (41) and of the second volume per area (42) of printed product that are deposited or injected onto the relief base layer (2). When the droplets of printed product are not injected onto the area adjacent to the recess area (21) (FIG. 3a), the printed product can expand into its surroundings in a greater and more uncontrolled basis than if the printed product were injected adjacent to or around it in order to favour confinement.

Exemplary Embodiment

[0076] The digital printing of the printed product was performed with a single pass digital printer (12) with two print heads, at a resolution of 360 dpi and three droplet levels (injected droplet volume): 14 pl, 28 pl and 43 pl.

[0077] The “trueTexture” jet ink, made by Italian manufacturer ZEETREE, SRL, was used as printed product.

[0078] The volume per area of printed product can vary, for example, by selecting the number of nozzles of the digital printer (12) per area, the droplet level per nozzle, as well as the number of passes or number of print heads per single pass digital printer (12) to deposit the printed product on the relief base layer (2).

[0079] In this exemplary embodiment, one pass was carried out with said digital printer (12). The printing was performed at a speed of 25 m/min on a 1000×200×4 mm SPC (“Stone Plastic Composite”) substrate (3) (common dimensions for floor slats).

[0080] The maximum volume per area of printed product for the exemplary embodiment corresponds to an injection with a maximum resolution of 360 dpi×360 dpi and a maximum droplet level of 43 pl in a single pass with the two print heads, i.e., a volume per area of printed product of 17.276 ml/m2. This maximum volume per area of printed product corresponds to the input percentage of 100%.

[0081] The input percentage of printed product for the digital printing varies between 0% and 100%, such that the higher the input percentage, the greater the depth of its penetration within the relief base layer (2) onto which the printed product is injected and therefore the depth of the recess obtained.

[0082] A UV-curing resin, which can be obtained from the manufacturer KLUMPP under reference 161-000-00430 (“UV Sealer”), was used as a material for the relief base layer (2). The resin was extended on the substrate (3) by means of a roller, with a thickness of the relief base layer (2) of approximately 100 microns, corresponding to a weight of approximately 100 gr/m2.

[0083] The image shown in FIG. 4, wherein the recess area (21) is defined as black and the no-recess area (22) is defined as white, was used as an example of a relief representation (30). According to this relief representation (30), the recess depth value for the recess area (21) is constant.

[0084] According to this relief representation (30), for the recess area (21) the relief base layer (2) was printed uniformly with a constant first volume per area (41) of printed product, corresponding to the 100% input percentage. Also, for the no-recess area (22), the relief base layer (2) was printed uniformly with a constant second volume per area (42) of printed product, which is less than the first volume per area (41) of printed product. In this exemplary embodiment, the second volume per area (42) of printed product was extended along the entire relief base layer (2) for the no-recess area (22).

[0085] For this relief representation (30), different samples were obtained by varying the second volume per area (42) of printed product, respectively, for different input percentages: 5% (0.864 ml/m2), 15% (2.591 ml/m2), 30% (5.183 ml/m2) and 50% (8.638 ml/m2).

[0086] In addition, the relief representation (30) of FIG. 4, corresponding to a fine stroke texture (I), was modified by gradually increasing the width of the strokes of the texture to obtain a relief representation (30) corresponding to a medium stroke texture (II) and a thick stroke texture (III).

[0087] In addition, for the fine stroke (I) relief representation (30), the medium stroke (II) relief representation (30) and the thick stroke (III) relief representation, different samples were also obtained by varying the second volume per area (42) of printed product, respectively, for different input percentages, 5% (0.864 ml/m2), 15% (2.591 ml/m2), 30% (5.183 ml/m2) and 50% (8.638 ml/m2).

[0088] The processed relief representations of FIG. 5 were generated for the digital printing of the recess areas (21) and the no-recess areas (22) with the corresponding input percentages for the respective fine stroke (I), medium stroke (II) and thick stroke (III) relief representations (30). These processed relief representations are images that define the input percentage of printed product using a grayscale ranging between white, which corresponds to a 0% input, and black, which corresponds to a 100% input.

[0089] The processed relief representations are shown in FIG. 5 arranged in an array, where the rows correspond to the input percentage corresponding to the second volume per area (42) of printed product, for 0%, where nothing is printed on the no-recess areas (22) (adjacent to the recess areas), 5%, 15%, 30% and 50%. The columns of the array correspond to the width of the recess areas, in the example of the strokes forming the relief (20), that is, fine (I), medium (II) and thick (III) widths.

[0090] The processed relief representations are processed by a computer program (17) of the computer system (16) for the digital printer (12) to determine the injection, the volume per area of printed product, the number of droplets per area, the droplet level, etc.

[0091] Samples with the printed product deposited or injected onto the relief base layer (2) were cured by means of UV lamps applying a total energy of 200 mJ/cm2, with a wavelength of between 230-410 nm and a peak power of 600 mW/cm2 to initiate the curing reaction.

[0092] After curing the samples, the mixture (40) between the printed product and the relief base layer (2) was removed by brushing, thus obtaining the reliefs (20) or textures formed by recesses corresponding to the recess areas.

[0093] The results obtained from the samples are described below.

[0094] FIG. 6 shows photographs of the samples provided, which correspond to the processed relief representations in FIG. 5. After obtaining the relief (20), a black powder filling pigment was applied on the recesses in order to appreciate the same in the photographs, the relief base layer (2) being transparent and applied on a substrate (3) with a white surface.

[0095] As shown in the photographs in FIG. 6, if only the recess area (21) is printed, that is, for 0% input in the no-recess area (22), the relief (20) is barely noticeable and poorly defined for a fine texture (I), i.e. a narrow stroke. On the other hand, for thick textures (III) with wider strokes, the relief (20) is uneven, rough to the touch and with sharp edges.

[0096] Surprisingly, when the background or no-recess area (22) is injected with an increasing input percentage of up to 50%, it is possible to obtain a better definition of the relief (20), as well as a smooth or progressive transition between the recess area (21) and the no-recess area (22), resulting in a greater quality for the relief (20) or texture. Thus, for example, a relief (20) with a 50% input and a fine stroke (I) is well defined and visible compared to a relief (20) with a 0% input and a fine stroke (I) where the relief (20) is barely appreciated. On the other hand, a relief (20) with a 50% input and a thick stroke (III) is much more defined and not rough to the touch, unlike the relief (20) with a 0% input and a thick stroke (III).

[0097] FIGS. 7 to 10 show photographs showing the reliefs (20) with contrast and in detail, without the black pigment of FIG. 6. FIG. 7 shows the relief (20) with a 0% input and a fine stroke (I). FIG. 8 shows the relief (20) with a 0% input and a thick stroke (III). FIG. 9 shows the relief (20) with a 50% input and a fine stroke (I). FIG. 10 shows the relief (20) with a 50% input and a thick stroke (III).

[0098] In short, it has been found that, if the areas adjacent to the recess areas are printed as well as the recess areas where the recess is to be generated, the textures are more defined and appreciable for the fine strokes, i.e., narrower strokes, in the recess areas. Even if the thickness were to be increased, for example, to further improve the definition of the reliefs (20), then smoother reliefs (20) are obtained.

[0099] It has also been found that injecting printed product onto the relief base layer (2) up to a maximum input percentage, for example, 50%, after curing and removing the mixture (40) produced, generates recesses that are barely noticeable to the touch or that cannot be seen in plain sight, even if a certain matting can be observed.

[0100] As has been explained above, it is possible to achieve a more precise and defined relief (20), texture or embossing of a greater quality by means of the present invention.

LIST OF REFERENCES

[0101] 1 Panel [0102] 2 Relief base layer [0103] 3 Substrate [0104] 10 Relief production machine [0105] 11 Roller application unit [0106] 12 Digital printer [0107] 13 Curing unit [0108] 14 Brushing unit [0109] 15 Data communication [0110] 16 Computer system [0111] 17 Computer program [0112] 18 Transport unit [0113] 20 Relief [0114] 21 Recess area [0115] 22 No-recess area [0116] 30 Relief representation [0117] 40 Mixture [0118] 41 First volume of printed product [0119] 42 Second volume of printed product [0120] I Fine texture [0121] II Medium texture [0122] Ill Thick texture