METHOD FOR PRODUCING A VIRTUAL THREE-DIMENSIONAL PATTERN IN A COATING

Abstract

The present invention relates to a gravure printing process for the production of a virtual three-dimensional pattern in a coating comprising flake-form effect pigments on a print substrate, to a coating produced in this way, and to the use thereof.

Claims

1. Process for the production of a virtual three-dimensional pattern in a coating on a print substrate, in which cells and/or hachures located on a surface of a gravure printing plate are filled with printing ink and subsequently the printing ink is transferred to a print substrate and solidified, where the printing ink comprises flake-form effect pigments and a first type of cells and/or hachures which have a flat base and side flanks, where the base is aligned parallel to the surface of the gravure printing plate and the flanks have an inclination angle α in the range from 70° to 90°, relative to the base, and a second type of cells and/or hachures which have a flat base and side flanks, where the base has an inclination angle β, relative to an imaginary base line running parallel to the surface of the gravure printing plate, that is smaller than the inclination angle of the flanks of the first type of cells and/or hachures, are arranged on the surface of the gravure printing plate, and where the first and second types of cells and/or hachures are arranged alongside one another, at least on a part-area of the surface of the gravure printing plate, with formation of boundary regions.

2. Process according to claim 1, characterised in that the boundary regions are formed as continuous lines which form at least part of an outer contour of virtually three-dimensional print motifs.

3. Process according to claim 2, characterised in that the virtually three-dimensional print motifs are regularly or irregularly shaped area elements having an area of at least 4 mm.sup.2, where the area elements are at least partly surrounded by an outer contour line.

4. Process according to claim 3, characterised in that the area elements in the coating on the print substrate appear to be raised.

5. Process according to claim 1, characterised in that the inclination angle β is at least 30 degrees smaller than the inclination angle α.

6. Process according to claim 1, characterised in that the inclination angle β is in the range from 4 to 30°.

7. Process according to claim 1, characterised in that the second type of cells and/or hachures has a greater maximum depth than the depth of the first type of cells and/or hachures.

8. Process according to claim 1, characterised in that the second type of cells and/or hachures has a maximum depth of 40 μm.

9. Process according to claim 1, characterised in that the printing ink transferred to the print substrate by means of the first type of cells and/or hachures has a volume per area unit which is smaller than a volume of printing ink per area unit which is transferred to the print substrate by means of the second type of cells and/or hachures.

10. Process according to claim 8, characterised in that the volume per area unit transferred to the print substrate by means of the second type of cells and/or hachures is at least 5 ml/m.sup.2 and at most 20 ml/m.sup.2.

11. Process according to claim 1, characterised in that the printing ink is a UV radiation-drying gravure printing ink.

12. Process according to claim 1, characterised in that the flake-form effect pigments are selected from the group pearlescent pigments, interference pigments, metal-effect pigments, liquid-crystal pigments, flake-form functional pigments, flake-form structured pigments, or mixtures comprising these.

13. Process according to claim 1, characterised in that a black, dark or coloured substrate is employed.

14. Process according to claim 1, characterised in that the print substrate is coated over the entire area or in part-areas with the printing ink comprising flake-form effect pigments, where at least some of the part-areas has at least one boundary region in a length of at least 2 mm.

15. Process according to claim 1, characterised in that the print substrate is a plastic film, a metal foil, a laminate, a paper, a cardboard or a wallpaper, where the substrate has optionally been precoated.

16. Coating comprising flake-form effect pigments on a print substrate, which has a visible, virtual three-dimensional pattern formed by orientation of the flake-form effect pigments in the coating at various angles, relative to the print substrate, produced by a process according to claim 1.

17. Coating comprising flake-form effect pigments according to claim 16, where the virtual three-dimensional pattern is a macroscopic pattern and has area elements having a size of at least 4 mm.sup.2.

18. Coating comprising flake-form effect pigments according to claim 16, characterised in that the coating has a planar outer surface.

19. A process for preparing decoration materials, packaging materials, works of art or security products which comprises incorporating a coating comprising flake-form effect pigments according to claim 16 therein.

20. Decoration materials, packaging materials, works of art or security products containing a coating comprising flake-form effect pigments according to claim 16.

Description

[0093] FIG. 1: shows diagrammatic representations of the cross sections of cell pairs of gravure printing plates in accordance with the prior art; [0094] left: depth-variable cell pair, [0095] right: area-variable cell pair

[0096] FIG. 2: shows a diagrammatic representation of the cross sections of cells and/or hachures in accordance with the invention arranged alongside one another; [0097] left: cell or hachure of the first type, [0098] right: cell or hachure of the second type

[0099] FIG. 3: shows a diagrammatic representation of the cross sections of a further variant of cells and/or hachures in accordance with the present invention arranged alongside one another; [0100] left: cell or hachure of the first type, [0101] right: cell or hachure of the second type

[0102] FIG. 4: shows an enlarged photograph of a 3D surface profile of cells of the first type in accordance with the present invention (not true to scale)

[0103] FIG. 5: shows an enlarged photograph of a 3D surface profile of hachures of the second type in accordance with the present invention (not true to scale)

[0104] The present invention will be explained in greater detail below with reference to an example, but is not intended to be reduced thereto.

EXAMPLE 1

[0105] A printing ink comprising 95% by weight of a gravure printing varnish (Schmid Rhyner UV-Lack Wessco 3741) and 5% by weight of a flake-form effect pigment (Iriodin® 6111 Icy White Pristine KU26) is prepared. The printing ink has a viscosity of about 35 sec., determined using a DIN 4 cup. The printing ink is printed onto a paper coated on one side (Sappi Algro Finess 70 g/m.sup.2) that has been precoated in black in advance over the entire area by conventional solvent gravure printing using a Moser Rototest gravure printing machine at a maximum printing speed of 70 m/min. The gravure printing cylinder used is a special cylinder which has been engraved with one type of cells (conventional) and one type of hachures (“second type” in accordance with the present invention), which are arranged alongside one another and form boundary lines with one another which form a checkered pattern which is visible to the naked eye. The conventional cells have a depth of 16 μm and a width of 135 μm with a flat cell base. The hachures have a maximum depth of 21 μm (measured at the lowest point of the base), a width of 110 μm and a flat base, where the base has on one side an inclination angle of 5°, relative to an imaginary flat base line at the lowest point of the base. After application of the printing ink to the print substrate, the printed print substrate with a still-wet print layer is exposed to air at a temperature of 80° C. between the printing machine and a UV dryer, which favours the formation of a readily visible 3D effect. The printed layer is subsequently dried by means of a conventional UV lamp. This gives a silvery white, glossy print image on a black background which has a readily visible, three-dimensional, macroscopic checkered pattern whose raised area parts are transferred by the conventional cells and whose three-dimensional appearance arises through contours formed at the boundary lines between conventional cells and special hachures.