EP3656566B1 - Method for printing longitudinal profile strips and profile strips - Google Patents

Description

The invention relates to a method for printing elongate profile strips, in particular skirting boards, with a pattern, in particular a wood grain decor, in which, in order to form a three-dimensionally structured surface, a haptic ink is first applied to at least a partial area of a basic profile moved relative to the print head arrangement by means of digital direct printing by means of a print head arrangement is printed on the profile strip, and that a colored pattern is then printed in the correct position on the previously three-dimensionally structured printed surface by means of a further print head arrangement, also by means of digital direct printing.

The invention also relates to a profile strip, in particular a skirting board, with a three-dimensionally structured pattern printed on it.

It is already known to print a pattern, in particular with a wood grain decor, on profile strips, in particular baseboards, such as are used on the edge of floors ( AT 508 572 B1 ). In this prior art, the pattern is first printed onto an applicator roller and then indirectly onto the profile strip.

Out of WO 2013/161846 A1 or EP-A-1479524 it is known to print flat surfaces with haptic ink and then print a pattern (e.g. a wood grain pattern) with the aim of achieving a more realistic appearance. When printing profile strips, in contrast to flat workpieces such as panels for floors, there is the problem that the profile strips have spatially differently aligned sub-areas that border one another either with sharp edges or via a curved surface.

The object of the invention is to specify a method for printing profile strips, in which patterns, in particular wood grain reproductions, can be applied with high reproduction accuracy and with a realistic appearance.

According to the invention, this is achieved by a method according to the feature of claim 1.

In the method according to the invention, not only is a colored pattern applied, but also a three-dimensional surface structure is formed by digital direct printing. This can be used to achieve a realistic look, especially the reproduction of wood that has natural peaks and valleys, i.e. a 3D structure. In order to print all surfaces of the profile bar with a three-dimensional surface structure and/or a colored pattern, it is provided that the haptic ink and/or the colored pattern is printed on spatially differently aligned partial areas of the profile bar in such a way that the different print areas are partially in an overlapping zone overlap. These overlapping zones generally lie along a longitudinal edge of the molding or along a transition from a flat area to a curved area.

By overlapping, it can be ensured that when using separately aligned print heads for the individual partial areas, no empty space remains, which is particularly important when the background—as preferably provided—is formed by a white haptic ink. By using several separate, preferably pivotable print heads and the idea of overlapping adjacent print areas with different orientations, a consistently clean print image can also be achieved on the profile strips ("around the corner").

Of course, the position of the colored pattern must be exactly in the correct position to the underlying, three-dimensionally printed haptic ink. This can be achieved by printing both the haptic ink and the colored pattern with digital direct printing, i.e. without transfer foils or indirectly printed application rollers. An inkjet or laser printing process is particularly suitable for digital direct printing, which applies the color or ink directly from the print heads to the workpiece, in particular the profile strip, without contact. Although application in two different printing processes is also conceivable and possible, it is more favorable to apply the printing with the haptic ink on the one hand and with the colored pattern on the other in one and the same printing process, i.e. in one run, driven by a transport device that has a electronic control device is synchronized with the printheads.

On the one hand, printing in one pass allows higher production speeds and, on the other hand, it also enables the relative alignment, i.e. the positional correctness, between the haptic ink and the colored pattern to be implemented exactly.

The workpiece (basic profile of the profile bar) is preferably driven and the print heads are essentially stationary during operation, at least as far as the alignment in the transport direction/longitudinal direction of the profile bar is concerned.

In principle, however, it would also be possible to move the print heads in the longitudinal direction, since it ultimately depends on the movement of the print heads relative to the workpiece (profile strip).

The invention also relates to a profile strip--preferably produced using the method described above. The profile strip according to the invention is characterized by the features of claim 12.

Further advantages and details of the invention are explained in more detail with reference to the following description of the figures.

Fig. 1a

ein Grundprofil des Ausführungsbeispiels einer erfindungsgemäßen Profilleiste,

Fig. 1b

dieses Grundprofil mit einer aufgebrachten Grundierung.

Fig. 1c

die Profilleiste mit einer auf die Grundierung aufgebrachten haptischen Tinte,

Fig. 1d

eine Profilleiste nach einem weiteren Arbeitsschritt, nämlich dem lagerichtigen Aufbringen eines farbigen Musters auf die dreidimensional strukturierte haptische Tinte.

Fig. 1e

die fertige Profilleiste nach dem Aufbringen einer dünnen Klarlackschickt,

Fig. 2

eine schematische Ansicht einer Vorrichtung zur Durchführung des erfindungsgemäßen Verfahrens anhand eines einfach dargestellten Ausführungsbeispiels,

Fig. 3

ein Ausführungsbeispiel einer Druckkopfanordnung zur Aufbringung eines farbigen Musters mit schwenkbaren Druckköpfen,

Fig. 4

in einer schematischen, perspektivischen Darstellung einer Profilleiste das Aufbringen eines farbigen Musters (hier streifenförmig) auf räumlich unterschiedlich ausgerichtete Teilbereiche der Profilleiste.

It shows:

Fig. 1a

a basic profile of the exemplary embodiment of a profile strip according to the invention,

Fig. 1b

this basic profile with an applied primer.

1c

the molding with a haptic ink applied to the primer,

Fig. 1d

a profile strip after a further work step, namely the application of a colored pattern in the correct position to the three-dimensionally structured haptic ink.

Fig. 1e

the finished profile strip after the application of a thin layer of clear lacquer,

2

a schematic view of a device for carrying out the method according to the invention based on a simply illustrated embodiment,

3

an embodiment of a print head arrangement for applying a colored pattern with pivotable print heads,

4

in a schematic, perspective view of a profile strip, the application of a colored pattern (striped here) to spatially differently aligned sub-areas of the profile strip.

This in Figure 1a illustrated basic profile 1 of a profile strip 100 has, for example, the dimensions of 16×60 mm. The base profile 1 can consist of finger-jointed spruce wood, but also of any other material, in particular wood, plastic or metal. The fact that they have a front side 1a and a cover side 1b, which are usually both to be printed, is typical of basic profiles 1 between the two flat sides 1a and 1b there is a curved surface 1c which is also to be printed, in such a way that the surfaces 1a, 1b, 1c are printed continuously. In contrast to flat panels, such as are used for floors, for example, one has to print on spatially differently aligned partial areas 1a, 1b, 1c of the profile strip. The back 1d is also profiled, but this is not critical since it is not printed.

It is relatively easy to provide the basic profile 1 of the profile strip 100 with a primer 2 that has the same layer thickness everywhere. This can be done either inline in a printing process above the transport device described later, or also outside of an inline printing process. The purpose of the primer 2 is to achieve good adhesion of the haptic ink 3 that is applied later to the base profile 1 . For this it is also possible to grind the primer 2. In principle, water-based or UV paints (i.e. paints that harden under the influence of UV light) can be used. However, other primers 2 are also entirely conceivable and possible.

According to Figure 1c a haptic ink 3 is now printed onto the primer 2, namely onto the planar partial area 1a and 1b, as well as onto the curved transitional area (longitudinal edge) 1c. According to the invention, the haptic ink 3 then forms a three-dimensionally structured surface, which simulates a wood grain in the present example. A realistic image of natural wood is thus possible. Of course, not only wood designs can be "imitated", but also other three-dimensional surface structures.

The three-dimensionally structured haptic ink 3 has depressions 3a and elevations 3b. Overall, it is preferably provided that the thickness of the printed haptic ink 3 is at least in regions over 100 μm, preferably over 200 μm.

The variation in thickness, ie the difference between the height of the depression 3a and the elevation 3b, is preferably more than 100 μm, preferably more than 200 μm, distributed over the surface, in order to achieve a realistic 3D image.

According to Figure 1e a colored pattern is now printed in the correct position on this three-dimensionally structured surface according to the method according to the invention. This pattern bears the reference number 4. figure 1 shows a (finished) profile strip 100.

The printed colored pattern 4 is adapted to the underlying haptic ink 3 with its 3D structure. This can be done by only printing partial areas 4a and omitting partial areas 4b. The color of the haptic ink 3 then shines through in these partial areas 4b. This is especially possible if it has a basic color that deviates from white. However, it is preferably provided that the printing with the colored pattern 4 extends over the entire surface to be printed, with the different areas of the 3D structure (in particular elevations on the one hand and depressions on the other) simply being printed with different colors, but overall the layer thickness the color of the colored pattern 4 runs essentially the same everywhere on the three-dimensionally structured surface of the haptic ink 3 .

According to a preferred embodiment, a continuous layer of clear lacquer 5 is finally applied over the colored pattern 4 in order to protect the underlying design. This layer of clear lacquer should not be too thick so as not to cover up the three-dimensional haptics created previously.

An exemplary embodiment of a device, shown in simplified form, for carrying out the method according to the invention is shown in figure 2 shown. With the reference numeral 6, a transport device is generally shown that has the task of holding the base profile 1 of the profile strip 100 lying thereon and moving it in the transport direction 7, which coincides with the longitudinal direction of the profile strip 100. The holding device 8 is shown only schematically; it can, for example, work with negative pressure and be either fixed or also moved. When holding devices 8 are moved along, clamps can also be provided which hold the basic profile 1 exactly. In any case, the transport device 6 ensures that the basic profile 1 is moved under the print head arrangements 10 and 12 described below. An electronic control device 9 controls the transport on the one hand and the print head assemblies 10 and 12 on the other hand, as well as the curing and drying stations 11 and 13.

In the first print head arrangement 10, a haptic ink 3 is applied to the basic profile 1 of the profile bar 100 in order to realize a three-dimensional surface structure. UV light is radiated in the curing station 11 in order to allow the UV-curable ink to cure at least partially before a colored pattern 4, in particular a wood decor, is applied in the correct position in the print head arrangement 12. This can also consist of a UV-curable ink, for which purpose a curing or drying station 13 is provided. As has been mentioned above, the printing of basic profiles 1 represents a problem in particular because the area to be printed is generally divided into a number of sub-areas, which adjoin one another but are spatially differently aligned. At the in figure 3 The illustrated embodiment shows a typical basic profile 1, which has a front side 1a, a top side 1b and a curved transition area 1c in between. These three areas 1a, 1b, 1c are to be printed with a continuous pattern, in particular a wood grain decor.

In order to realize this, according to the method according to the invention, a printhead arrangement 12 can be used in which some printheads are pivotably arranged. This is indicated by an arrow 14. the The pivoting direction runs about an axis which is parallel to the transport direction 7 which coincides with the longitudinal direction of the profile strip 100 . In general, a pivoting range of 0 to 90° is sufficient. The pivoting can be adjusted to a specific type of profile strip by a one-off adjustment, in such a way that the printing is carried out as perpendicularly as possible to the area to be printed. With a curved surface 1c, a compromise has to be made here. In figure 3 For example, the curved surface 1c undergoes a substantially 90° curvature, so it will be beneficial to position the printheads in the first (rear) portion 12' of the printhead assembly 12 at about 45° relative to the printheads in the second (front) portion 12''. of the printhead assembly 12.

In principle, it would also be possible to change the pivoting position of the print heads electronically during the run in order to achieve an optimal print image. However, it will be cheaper and easier to simply adjust the print heads in their pivoting position to the profile type and then slightly adjust their alignment during the printing process.

The problem of printing curved areas 1c using pivotable or differently aligned print heads can also be solved by printing overlapping zones between the individual areas to be printed. This is based on the figure 4 explained in more detail.

In figure 4 1 is a simplified molding 100 having a flat front face 1a, a flat top face 1b and an intermediate curved portion 1c along the longitudinal edge. The aim is now to print these three areas 1a, 1b, 1c precisely with a continuous decor without leaving any unprinted areas. Pivoting printheads or printheads that can be adjusted in other ways can be used for this purpose, as for example in figure 3 are shown. In figure 3 However, only two areas 12" and 12' are shown. For the profile strip 100 according to figure 4 would a third area to be considered for printing on the top side 1b. However, it is also possible for the first area 12' of the print head arrangement 12 to take over at once with the curved area 1c. In any case, it works figure 4 from three areas of the printhead assemblies. First, the print heads in the first area 12′ of the print head arrangement, which are aligned essentially perpendicularly to the top side 1b, could print the area 14 that still extends into the area 1c in an overlapping zone 14a, i.e. the subsequent curved area 1c of the longitudinal edge. The transition region 1c can then be printed with at least one print head pivoted essentially at 45°. This print area is denoted by 15 and has an overlapping zone 15a and an overlapping zone 15b. The overlapping zone 15a is not absolutely necessary, it can be provided. However, it is also sufficient if the overlapping zone 15a overlaps with the printing 15. The overall width of the overlapping zone is denoted by B and is advantageously between 0.5 mm and 5 mm for profile strips 100 .

When printing on the front side 1a, the idea is repeated with the printing beyond the transition edges 16, the print heads for the front side 1a are aligned essentially perpendicularly to this and mainly print on the area 17, which in turn can have an overlapping zone 17a.

Ultimately, the overlapping of the print areas in differently aligned or curved sub-areas of the base profile 1 of the profile strip 100 achieves a continuous, exact, clean printed image without the underlying layer showing through. The print image is particularly accurate when the print head is aligned exactly perpendicular to the surface. In the case of curved surfaces, this is basically not possible with a single print head or a single print head arrangement 12 . But if two areas 12' and 12" of a printhead assembly 12 interact with different pivot positions, a good print image can also be achieved in an overlapping area that is not exactly perpendicular to any of the print heads.

Controlled by suitable software, it can be achieved that the image, which does not impinge exactly perpendicularly from the print heads, but instead impinges on curved surfaces, is distorted or rectified in such a way that it ultimately corresponds to the desired printed image. In addition, this software control can be used to ensure that the color application in the overlapping zones (transition zones) is reduced compared to those zones where only a single application takes place, so that - if these overlapping zones are printed by two different print heads - the color application is not doubled, but overall the correct color application takes place. In the overlapping zones, two print heads print in a reduced manner.

The above considerations apply in principle both to the application of the colored pattern and to the haptic ink 3, i.e. for the print head arrangement 10 and 12.

With regard to the printhead assemblies 10 and 12 as a whole, as shown in figure 3 shown consist of several individual print heads, which are designed for the application of different colors, in particular cyan, magenta, yellow and black.

The invention is not limited to the exemplary embodiments shown. In particular, differently profiled profile strips can also be used.

Reference list:

1

basic profile

1a

flat surface (front)

1b

flat surface (top side)

1c

curved surface

2

primer

3

haptic ink

4

sample

5

clear coat

6

transport device

7

transport direction

8th

holding device

9

electronic control device

10

Printhead assembly (for haptic tine)

11

Curing and drying station

12

Print Head Arrangement (for Color Pattern)

12'

first (back) area

12"

second (front) area

13

Curing and drying station

14

area

14a

overlap zone

15

Oppression

15a

overlap zone

15b

overlap zone

B

width of the overlap

16

transition edges

17

area

17a

overlap zone

100

profile bar

Claims (14)

1. A method for printing elongated profile strips (100), in particular skirting boards, with a pattern (4), in particular a wood grain decor, wherein, in order to construct a three dimensional structured surface, firstly, a tactile ink (3) is printed by direct digital printing by means of a print head assembly (10) onto at least one subsection of a base profile (1) of the profile strip (100), which base profile is moved relative to the print head assembly (10), and that next, by means of a further print head assembly (12) and also by means of direct digital printing, a coloured pattern (4) is printed in the correct position onto the three dimensional structured surface which has already been printed, wherein the tactile ink (3) and/or the coloured pattern (4) is/are overlapped and printed onto subsections of the profile strip (100) which are in different spatial orientations in different print regions which partially overlap in an overlapping zone (14a, 15a, 15b, 17a), preferably along a longitudinal edge of the profile strip (100) or along a transition from a flat region (1a, 1b) to a curved region (1c), characterized in that, in order to print subsections of the profile strip (100) which are in different spatial orientations, print heads are used within the print head assembly (10) for the tactile ink (3) which are in different spatial orientations, preferably pivotally mounted.
2. The method according to claim 1, characterized in that the printed subsection of the profile strip (100) comprises a curved surface (1c) or a longitudinal edge of the profile strip (100).
3. The method according to claim 1 or 2, characterized in that the printed subsection of the profile strip (100) furthermore comprises at least one flat surface (1a, 1b) of the profile strip (100) which is contiguous with the curved surface (1c) or the longitudinal edge.
4. The method according to one of the claims 1 to 3, characterized in that in order to print subsections of the profile strip (100) with different spatial orientations, print heads are used within the print head assembly (12) for the coloured pattern (4) which are in different spatial orientations, preferably pivotally mounted.
5. The method according to one of the claims 1 to 4, characterized in that the tactile ink (3) is printed consecutively onto subsections of the profile strip (100) with different spatial orientations by means of separate print heads.
6. The method according to one of the claims 1 to 5, characterized in that the coloured pattern (4) is printed consecutively onto subsections of the profile strip (100) with different spatial orientations by means of separate print heads.
7. The method according to one of the claims 1 to 6, characterized in that the width of the overlapping zone (14a, 15a, 15b, 17a) is 0.5 mm to 5 mm.
8. The method according to one of the claims 1 to 7, characterized in that prior to printing the tactile ink (3), a primer (2) is applied to the profile strip (100) - preferably with the same overall layer thickness.
9. The method according to one of the claims 1 to 8, characterized in that after printing the coloured pattern (4), a layer of clear lacquer (5) is applied to the profile strip (100) - preferably with the same overall layer thickness.
10. The method according to one of the claims 1 to 9, characterized in that inkjet printing and/or laser printing is employed as the direct digital printing.
11. A profile strip (100), in particular a skirting board, with a printed pattern (4), in particular produced in accordance with a method of claims 1 to 10, characterized in that the profile strip (100) has:

    - a base profile (1), preferably produced from a wood, metal or plastic,

    - a tactile ink (3) printed thereon in regions and which forms a three dimensional structured surface on the surface of the base profile (1) which is preferably substantially smooth, and

    - a coloured pattern (4) which is printed in the correct position onto the tactile ink (3), preferably with a uniform layer thickness.
12. The profile strip according to claim 11, characterized in that the printed tactile ink (3) and/or the printed coloured pattern (4) overlaps adjacent subsections with different spatial orientations in overlapping zones (14a, 15a, 15b, 17a).
13. The profile strip according to claim 11 or 12, characterized in that the thickness of the printed tactile ink (3) is over 100 µm, preferably over 200 µm, at least in regions.
14. The profile strip according to one of the claims 11 to 13, characterized in that the thickness of the printed tactile ink (3) varies over the printed surface by more than 100 µm, preferably by more than 200 µm.

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