Optical effect layer containing magnetic or magnetisable pigment particles and method for producing said optical effect layer - Patents.com

Abstract

The present invention relates to the field of protection of security documents, such as banknotes and identity documents, against counterfeiting and illegal duplication. In particular, the present invention provides security documents and decorative articles with one or more optical effect layers (OEL) comprising magnetically oriented plate-like magnetic or magnetisable pigment particles in an at least partially cured coating layer (x40), and a method for producing said OEL.

Description

Detailed Description of the Invention

[0001] [Field of the Invention]

[0001] The present invention relates to the field of optical effect layers (OELs) comprising magnetically oriented magnetic or magnetisable pigment particles. In particular, the present invention provides security documents and decorative articles with one or more optical effect layers (OELs), a method for producing said OELs and their use on security documents or articles as an anti-counterfeiting measure and for decorative purposes.

[0002] [Background of the invention]

[0002] It is known in the art to use inks, compositions, coatings or layers containing oriented magnetic or magnetizable pigment particles, in particular optically variable magnetic or magnetizable pigment particles, to produce security elements, for example in the field of security documents. Coatings or layers containing oriented magnetic or magnetizable pigment particles are disclosed, for example, in U.S. Pat. Nos. 2,570,856, 3,676,273, 3,791,864, 5,630,877 and 5,364,689. Coatings or layers containing oriented magnetic color-changing pigment particles, which show particularly good optical effects and are useful for the protection of security documents, are disclosed in WO 2002 / 090002 and WO 2005 / 002866.

[0003]

[0003] For example, security features of security documents can generally be classified into "covert" security features on the one hand and "overt" security features on the other hand. The protection provided by covert security features relies on the principle that such measures are difficult to detect, and that detection usually requires special equipment and knowledge. "Overt" security features, on the other hand, are easily detectable by human senses alone, for example allowing visual and / or tactile detection of such measures, while remaining difficult to manufacture and / or copy. However, the effectiveness of overt security features depends heavily on their recognizability as respective security features.

[0004]

[0004] Magnetic or magnetisable pigment particles in printing inks or coatings make it possible to produce magnetically inductive images, designs and / or patterns by locally orienting the magnetic or magnetisable pigment particles in the unsolidified / cured (i.e. wet) coating by application of a magnetic field of a corresponding configuration, followed by solidification of the coating. The result is a fixed and stable magnetically inductive image, design or pattern. Materials and techniques for the orientation of magnetic or magnetisable pigment particles in coating compositions are disclosed, for example, in U.S. Pat. No. 2,418,479, U.S. Pat. No. 2,570,856, U.S. Pat. No. 3,791,864, DE-A-2006848, U.S. Pat. No. 3,676,273, U.S. Pat. No. 5,364,689, U.S. Pat. No. 6,103,361, EP-A-0406667, U.S. Pat. Appl. Pub. No. 2002 / 0160194, U.S. Pat. Appl. Pub. No. 2004 / 0009309, EP-A-0710508, WO-A-2002 / 009002, WO-A-2003 / 000801, WO-A-2005 / 002866, WO-A-2006 / 061301. Thus, a magnetic induction pattern is obtained that is highly resistant to counterfeiting.The targeted security element is only achieved by utilizing both magnetic or magnetisable pigment particles or corresponding inks and the specific technology used for printing said inks and for orienting said pigments in the printed ink.

[0005]

[0005] Depending on the magnetic orientation pattern of the magnetic or magnetizable pigment particles of an optical effect layer (OEL) as well as the viewing direction, said OEL may exhibit light and dark areas. The optical properties of a particular zone of an OEL are directly dependent on the orientation of the magnetic or magnetizable pigment particles in the coating layers that make up said OEL.

[0006]

[0006] EP 2024451 discloses a coating composition consisting of a volatile component (S) and a non-volatile component, including in particular a UV-curable compound, the latter consisting of an ink vehicle (I) and a magnetically orientable optically variable interference pigment (P), characterized in that the ratio of the ink vehicle volume (V(I)) to the pigment volume (V(P)) is higher than 5.0 for producing a magnetically induced image (i.e., an optical effect layer). EP 2024451 further discloses that the optical effect layer is thicker than d50 / 3, d50 being the average diameter of the magnetically orientable optically variable interference pigment. In particular, EP 2024451 discloses an improved method of producing an optical effect layer by using a specific ratio of the ink vehicle volume (V(I)) to the pigment volume (V(P)) and a specific ratio between the thickness and the d50 value, compared to conventional solvent-based compositions, which are considered less suitable due to the vertical shrinkage of the printed ink layer during the drying step.

[0007]

[0007] EP 1819525 and US 8,025,952 disclose optical effect layer particles which are magnetically oriented according to a pattern known as Venetian blinds. The disclosed optical effect layer comprises at least one zone of magnetically oriented plate-like magnetic or magnetisable pigment particles which are parallel to one another. The magnetically oriented pigment particles have their magnetic axes parallel to one another and to a plane which is not parallel to the substrate to which they are applied and which have substantially the same elevation angle of at least 30° relative to the plane of the substrate.

[0008]

[0008] WO 2020 / 173693 discloses a method for performing authentication using an optical effect layer of a portable device such as those disclosed in EP 1 819 525 and US Pat. No. 8,025,952.

[0009]

[0009] The optical effect layers disclosed in EP 1819525, U.S. Pat. No. 8,025,952, and WO 2020 / 173693 are typically produced by using the coating compositions disclosed in EP 2024451.

[0010]

[0010] There remains a need for improved methods for producing optical effect layers (OELs) on a substrate comprising magnetically oriented plate-like magnetic or magnetizable pigment particles in terms of efficiency and freedom of selecting a magnetic field generating device that orients particles in a coating layer so that adjacent magnetically oriented plate-like magnetic or magnetizable pigment particles have one or more areas that are substantially parallel to each other.

[0011] [Summary of the Invention]

[0011] Accordingly, the present invention aims to overcome the deficiencies of the prior art.

[0012] This is accomplished by providing a method for producing an optical effect layer (OEL) and the resulting optical effect layer (OEL) as described herein.

[0013]

[0013] The present specification describes a method for producing an optical effect layer (OEL) on a substrate (x20) having a two-dimensional surface, comprising the steps of: a) applying a radiation curable coating composition in a first liquid state to the surface of a substrate (x20) comprising platelet-shaped magnetic or magnetisable pigment particles having a major axis X and a d50 value, so as to form a coating layer (x10); b) One or more areas (A, A', A iIn the step of exposing the coating layer (x10) to said magnetic field, at least a part of the plate-shaped magnetic or magnetizable pigment particles is oriented, and the substrate (x20) having the coating layer (x10) is exposed to said one or more areas (A, A', A i '), and a two-dimensional surface of the substrate (x20) at the position of the particle and one or more areas (A, A', A i an angle α between the tangent of the magnetic field lines of the magnetic field in the magnetic field magnet 1′) and the magnetic field line is greater than or equal to 12° and less than or equal to 75° (12°≦|α|≦75°) or greater than or equal to 105° and less than or equal to 168° (105°≦|α|≦168°); c) partially simultaneously with or after step b), at least partially curing the coating layer (x10) in a curing unit (x50) to fix the position and orientation of the platelet-shaped magnetic or magnetisable pigment particles in the coating layer (x10) to produce an at least partially cured coating layer (x40) having a thickness T, the thickness T of the at least partially cured coating layer (x40) being smaller than the d50 value of the platelet-shaped magnetic or magnetisable pigment particles and adjacent magnetically oriented platelet-shaped magnetic or magnetisable pigment particles have main axes X that are substantially parallel to each other at least in one or more regions (x40-a, x40-b) of the at least partially cured coating layer (x40); A method is described, comprising:

[0014]

[0014] Also described herein is an optical effect layer (OEL) comprising an at least partially cured layer (x40) constituted by a radiation curable coating composition having a thickness T and comprising magnetically oriented plate-like magnetic or magnetizable pigment particles having a major axis X and a d50 value, wherein the thickness T of the at least partially cured coating layer (x40) is smaller than the d50 value of the plate-like magnetic or magnetizable pigment particles, and wherein adjacent magnetically oriented plate-like magnetic or magnetizable pigment particles at least each have major axes X that are substantially parallel to each other in one or more regions (x40-a, x40-b) of the at least partially cured layer (x40).

[0015] In contrast to the disclosure of European Patent No. 2024451, in addition to the specific relationship (T < d50) according to the claims between the thickness of the at least partially cured coating layer (x40) (i.e., the thickness of the optical effect layer) described herein and the d50 value of the plate-shaped magnetic or magnetizable pigment particles, and the value of the specific angle α according to the claims, and preferably the relationship (T < d50 * (sin α)) between the thickness of the method according to the claims and the value of the angle α, by using these, regardless of the uniformity / non-uniformity of each magnetic field, a magnetic field generating device can be freely selected to generate the optical effect layer including one or more regions (x40-a, x40-b) of the at least partially cured coating layer (x40) in which adjacent magnetically oriented plate-shaped magnetic or magnetizable pigment particles each have at least a main axis X substantially parallel to each other. Further, the present invention is advantageous for enabling the generation of an optical effect layer (OEL) with uniform pigment orientation on a wide surface.

[0016]

[0016] Hereinafter, with reference to the drawings and specific embodiments, a security document or article including one or more optical effect layers (OELs) described herein and the method described herein for generating the OEL on a substrate (x20) will be described in more detail.

[0017] FIG. 1 is a diagram schematically showing plate-shaped magnetic or magnetizable pigment particles having main axes X and Y. FIGS. 2A to 2H are diagrams showing cross-sections of an OEL including one or more at least partially cured coating layers (240, 241) having thicknesses T, T' and incorporating magnetically oriented plate-shaped magnetic or magnetizable pigment particles. FIG. 2A is a diagram schematically showing a cross-section of an OEL including a single at least partially cured coating layer (240) having a thickness T and incorporating magnetically oriented plate-shaped magnetic or magnetizable pigment particles, in which substantially all plate-shaped magnetic or magnetizable pigment particles in one or more regions have substantially the same elevation angle γ and the particles have a d50 value larger than T. FIG. 2B shows a schematic representation of a cross-section of an OEL with a single at least partially cured coating layer (240) having a thickness T and comprising platelet-shaped magnetic or magnetisable pigment particles in one or more first regions (240-a) and platelet-shaped magnetic or magnetisable pigment particles in one or more second regions (240-b), in which substantially all of the platelet-shaped magnetic or magnetisable pigment particles in the one or more first regions (240-a) have substantially the same elevation angle γ and substantially all of the platelet-shaped magnetic or magnetisable pigment particles in the one or more second regions (240-b) have substantially the same another elevation angle γ', said elevation angle γ and the another elevation angle γ' being different and / or non-coplanar with respect to one another, and in which the particles have a d50 value greater than T. FIG. 2C illustrates an OEL comprising an at least partially cured first coating layer (240) having a thickness T and incorporating first platelet-shaped magnetic or magnetisable pigment particles that are magnetically oriented, and an at least partially cured second coating layer (241) having a thickness T′ and incorporating second platelet-shaped magnetic or magnetisable pigment particles that are magnetically oriented, wherein the at least partially cured second coating layer (241) at least partially overlaps the at least partially cured first coating layer (240) and substantially all of the first magnetic particles in the at least partially cured coating layer (240) are magnetically oriented. Schematic representation of a cross-section of an OEL, in which one platelet-shaped magnetic or magnetisable pigment particle has substantially the same elevation angle γ and substantially all second platelet-shaped magnetic or magnetisable pigment particles in an at least partially cured second coating layer (241) have substantially the same another elevation angle γ', said elevation angle γ and the another elevation angle γ' being different and / or non-coplanar, and in which first particles in the at least partially cured first coating layer (240) have a d50 value greater than T and second pigment particles in the at least partially cured second coating layer (241) have a d50 value greater than T'. FIG. 2D illustrates an OEL comprising an at least partially cured first coating layer (240) having a thickness T and incorporating first magnetically oriented platelet-shaped magnetic or magnetizable pigment particles, and an at least partially cured second coating layer (241) having a thickness T′ and incorporating second magnetically oriented platelet-shaped magnetic or magnetizable pigment particles, wherein the at least partially cured second coating layer (241) completely overlies the at least partially cured first coating layer (240) and substantially all of the first magnetic particles in the at least partially cured first coating layer (240). FIG. 2 shows a schematic cross-section of an OEL, in which all platelet-shaped magnetic or magnetisable pigment particles in the at least partially cured first coating layer (240) have substantially the same elevation angle γ and substantially all second platelet-shaped magnetic or magnetisable pigment particles in the at least partially cured second coating layer (241) have substantially the same another elevation angle γ', said elevation angle γ and the another elevation angle γ' being different and / or non-coplanar with respect to one another, and in which first particles in the at least partially cured first coating layer (240) have a d50 value greater than T and second particles in the at least partially cured second coating layer (241) have a d50 value greater than T'. 2E and 2F show an OEL comprising an at least partially cured first coating layer (240) having a thickness T and incorporating first magnetically oriented platelet-shaped magnetic or magnetisable pigment particles, and an at least partially cured second coating layer (241) having a thickness T' and incorporating second magnetically oriented platelet-shaped magnetic or magnetisable pigment particles, wherein the at least partially cured second coating layer (241) is adjacent to the at least partially cured first coating layer (240) (FIG. 2E) or spaced apart from the at least partially cured first coating layer (240) (FIG. 2F) and is in contact with the at least partially cured first coating layer (240). FIG. 2 shows a schematic cross-section of an OEL, in which substantially all first platelet-shaped magnetic or magnetisable pigment particles in the at least partially cured first coating layer (240) have substantially the same elevation angle γ and substantially all second platelet-shaped magnetic or magnetisable pigment particles in the at least partially cured second coating layer (241) have substantially the same other elevation angle γ', said elevation angle γ and the other elevation angle γ' being different and / or non-coplanar with respect to one another, and in which first particles in the at least partially cured first coating layer (240) have a d50 value greater than T and second particles in the at least partially cured second coating layer (241) have a d50 value greater than T'. 2G and 2H show an OEL comprising an at least partially cured first coating layer (240) having a thickness T and incorporating first magnetically oriented platelet-shaped magnetic or magnetisable pigment particles, and an at least partially cured second coating layer (241) having a thickness T' and incorporating second magnetically oriented platelet-shaped magnetic or magnetisable pigment particles, wherein the at least partially cured second coating layer (241) at least partially (FIG. 2G) or completely (FIG. 2H) overlaps the at least partially cured first coating layer (240) and is in contact with the at least partially cured first coating layer (240). FIG. 2 shows a schematic cross-section of an OEL, in which substantially all first platelet-shaped magnetic or magnetisable pigment particles in the at least partially cured second coating layer (240) have substantially the same elevation angle γ and substantially all second platelet-shaped magnetic or magnetisable pigment particles in the at least partially cured second coating layer (241) have substantially the same other elevation angle γ', said elevation angle γ and the other elevation angle γ' being different and / or non-coplanar with respect to one another, and in which first particles in the at least partially cured first coating layer (240) have a d50 value greater than T and second particles in the at least partially cured second coating layer (241) have a d50 value greater than T'. Figures 3A, 3B and 3D are schematic cross-sectional views of a suitable magnetic field generating device (330) consisting of a rod-shaped dipole magnet for orienting plate-shaped magnetic or magnetizable pigment particles in a coating layer (310) on a substrate (320), where the plate-shaped magnetic or magnetizable pigment particles are exposed to the magnetic field of the magnetic field generating device (330) (magnetic field lines shown as arrowed lines going from the north pole to the south pole) in two areas where the magnetic field is substantially non-uniform (shown as A and A'). FIG. 3C is a schematic cross-sectional view of a suitable magnetic field generating device (330) consisting of a rod-shaped dipole magnet for orienting plate-shaped magnetic or magnetizable pigment particles in a single discontinuous coating layer (310) having two regions (310-a and 310-b) or in two coating layers (310-a and 310-b) on a substrate (320), where the plate-shaped magnetic or magnetizable pigment particles in the two regions (310-a and 310-b) are exposed to the magnetic field (magnetic field lines shown as arrowed lines going from the north pole to the south pole) of the magnetic field generating device (330) in one area each, and the magnetic field is substantially non-uniform (shown as A and A'). FIG. 4 is a schematic diagram of a magnetic field generating device (430) suitable for orienting plate-shaped magnetic or magnetizable pigment particles in a coating layer (410) on a substrate (420), the magnetic field generating device (430) consisting of two rod-shaped dipole magnets (M1, M2) with the same magnetic field direction and an iron yoke (Y), in which the plate-shaped magnetic or magnetizable pigment particles are exposed to the magnetic field of the rod-shaped dipole magnets (430) in one area (magnetic field lines shown as arrowed lines going from the north pole to the south pole), the magnetic field is substantially uniform (shown as a dotted rectangle A), and the substrate (420) with the coating layer (410) is provided in the area A at a specific angle α. 5A and 5B are diagrams showing the change in elevation angle γ of plate-shaped magnetic or magnetizable pigment particles magnetically oriented by the magnetic field of the magnetic field generator shown in FIG. 3A in an at least partially cured coating layer (Examples E1, E2 and Comparative Examples C1, C2), where the x-axis (mm) corresponds to the distance from the edge of the at least partially cured layer (x40), and the value of 15 mm corresponds to the center of the magnetic field generator shown in FIG. 3A and the center of the at least partially cured layer (x40). FIG. 6 is a schematic diagram of a magnetic field generating device (630) as disclosed in co-pending European Patent Application No. 20194060.8, the magnetic field generating device (630) consisting of a rod-shaped dipole magnet used for orienting plate-shaped magnetic or magnetizable pigment particles in a coating layer (610) on a substrate (620), the plate-shaped magnetic or magnetizable pigment particles being exposed to the magnetic field of the magnetic field of the magnetic field generating device (630) in one area (shown as B) where the magnetic field is substantially uniform (magnetic field lines shown as arrowed lines going from the north pole to the south pole), the substrate (620) having a coating layer (610) being provided in said area B where the magnetic field is substantially uniform, the angle α between the coating layer (610) and the tangent of the magnetic field lines of the magnetic field in the area B where the magnetic field is substantially uniform being approximately 30°. [Brief description of the drawings]

[0018] [Figure 1] FIG. 1 is a schematic diagram of a plate-shaped magnetic or magnetisable pigment particle having principal axes X and Y. [Figure 2A] FIG. 2A is a schematic diagram showing a cross-section of an OEL comprising a single at least partially cured coating layer (240) having a thickness T and incorporating magnetically oriented plate-shaped magnetic or magnetizable pigment particles, where substantially all of the plate-shaped magnetic or magnetizable pigment particles in one or more regions have substantially the same elevation angle γ, and the particles have a d50 value greater than T. [Figure 2B]FIG. 2B shows a schematic representation of a cross-section of an OEL with a single at least partially cured coating layer (240) having a thickness T and comprising platelet-shaped magnetic or magnetisable pigment particles in one or more first regions (240-a) and platelet-shaped magnetic or magnetisable pigment particles in one or more second regions (240-b), in which substantially all of the platelet-shaped magnetic or magnetisable pigment particles in the one or more first regions (240-a) have substantially the same elevation angle γ and substantially all of the platelet-shaped magnetic or magnetisable pigment particles in the one or more second regions (240-b) have substantially the same another elevation angle γ', said elevation angle γ and the another elevation angle γ' being different and / or non-coplanar with respect to one another, and in which the particles have a d50 value greater than T. [Figure 2C] FIG. 2C illustrates an OEL comprising an at least partially cured first coating layer (240) having a thickness T and incorporating first platelet-shaped magnetic or magnetisable pigment particles that are magnetically oriented, and an at least partially cured second coating layer (241) having a thickness T′ and incorporating second platelet-shaped magnetic or magnetisable pigment particles that are magnetically oriented, wherein the at least partially cured second coating layer (241) at least partially overlaps the at least partially cured first coating layer (240) and substantially all of the first magnetic particles in the at least partially cured coating layer (240) are magnetically oriented. Schematic representation of a cross-section of an OEL, in which one platelet-shaped magnetic or magnetisable pigment particle has substantially the same elevation angle γ and substantially all second platelet-shaped magnetic or magnetisable pigment particles in an at least partially cured second coating layer (241) have substantially the same another elevation angle γ', said elevation angle γ and the another elevation angle γ' being different and / or non-coplanar, and in which first particles in the at least partially cured first coating layer (240) have a d50 value greater than T and second pigment particles in the at least partially cured second coating layer (241) have a d50 value greater than T'. [Figure 2D]FIG. 2D illustrates an OEL comprising an at least partially cured first coating layer (240) having a thickness T and incorporating first magnetically oriented platelet-shaped magnetic or magnetizable pigment particles, and an at least partially cured second coating layer (241) having a thickness T′ and incorporating second magnetically oriented platelet-shaped magnetic or magnetizable pigment particles, wherein the at least partially cured second coating layer (241) completely overlies the at least partially cured first coating layer (240) and substantially all of the first magnetic particles in the at least partially cured first coating layer (240). FIG. 2 shows a schematic cross-section of an OEL, in which all platelet-shaped magnetic or magnetisable pigment particles in the at least partially cured first coating layer (240) have substantially the same elevation angle γ and substantially all second platelet-shaped magnetic or magnetisable pigment particles in the at least partially cured second coating layer (241) have substantially the same another elevation angle γ', said elevation angle γ and the another elevation angle γ' being different and / or non-coplanar with respect to one another, and in which first particles in the at least partially cured first coating layer (240) have a d50 value greater than T and second particles in the at least partially cured second coating layer (241) have a d50 value greater than T'. [Figure 2E]2E and 2F show an OEL comprising an at least partially cured first coating layer (240) having a thickness T and incorporating first magnetically oriented platelet-shaped magnetic or magnetisable pigment particles, and an at least partially cured second coating layer (241) having a thickness T' and incorporating second magnetically oriented platelet-shaped magnetic or magnetisable pigment particles, wherein the at least partially cured second coating layer (241) is adjacent to the at least partially cured first coating layer (240) (FIG. 2E) or spaced apart from the at least partially cured first coating layer (240) (FIG. 2F) and is in contact with the at least partially cured first coating layer (240). FIG. 2 shows a schematic cross-section of an OEL, in which substantially all first platelet-shaped magnetic or magnetisable pigment particles in the at least partially cured first coating layer (240) have substantially the same elevation angle γ and substantially all second platelet-shaped magnetic or magnetisable pigment particles in the at least partially cured second coating layer (241) have substantially the same other elevation angle γ', said elevation angle γ and the other elevation angle γ' being different and / or non-coplanar with respect to one another, and in which first particles in the at least partially cured first coating layer (240) have a d50 value greater than T and second particles in the at least partially cured second coating layer (241) have a d50 value greater than T'. [Figure 2F]2E and 2F show an OEL comprising an at least partially cured first coating layer (240) having a thickness T and incorporating first magnetically oriented platelet-shaped magnetic or magnetisable pigment particles, and an at least partially cured second coating layer (241) having a thickness T' and incorporating second magnetically oriented platelet-shaped magnetic or magnetisable pigment particles, wherein the at least partially cured second coating layer (241) is adjacent to the at least partially cured first coating layer (240) (FIG. 2E) or spaced apart from the at least partially cured first coating layer (240) (FIG. 2F) and is in contact with the at least partially cured first coating layer (240). FIG. 2 shows a schematic cross-section of an OEL, in which substantially all first platelet-shaped magnetic or magnetisable pigment particles in the at least partially cured first coating layer (240) have substantially the same elevation angle γ and substantially all second platelet-shaped magnetic or magnetisable pigment particles in the at least partially cured second coating layer (241) have substantially the same other elevation angle γ', said elevation angle γ and the other elevation angle γ' being different and / or non-coplanar with respect to one another, and in which first particles in the at least partially cured first coating layer (240) have a d50 value greater than T and second particles in the at least partially cured second coating layer (241) have a d50 value greater than T'. [Figure 2G]2G and 2H show an OEL comprising an at least partially cured first coating layer (240) having a thickness T and incorporating first magnetically oriented platelet-shaped magnetic or magnetisable pigment particles, and an at least partially cured second coating layer (241) having a thickness T' and incorporating second magnetically oriented platelet-shaped magnetic or magnetisable pigment particles, wherein the at least partially cured second coating layer (241) at least partially (FIG. 2G) or completely (FIG. 2H) overlaps the at least partially cured first coating layer (240) and is in contact with the at least partially cured first coating layer (240). FIG. 2 shows a schematic cross-section of an OEL, in which substantially all first platelet-shaped magnetic or magnetisable pigment particles in the at least partially cured second coating layer (240) have substantially the same elevation angle γ and substantially all second platelet-shaped magnetic or magnetisable pigment particles in the at least partially cured second coating layer (241) have substantially the same other elevation angle γ', said elevation angle γ and the other elevation angle γ' being different and / or non-coplanar with respect to one another, and in which first particles in the at least partially cured first coating layer (240) have a d50 value greater than T and second particles in the at least partially cured second coating layer (241) have a d50 value greater than T'. [Figure 2H]2G and 2H show an OEL comprising an at least partially cured first coating layer (240) having a thickness T and incorporating first magnetically oriented platelet-shaped magnetic or magnetisable pigment particles, and an at least partially cured second coating layer (241) having a thickness T' and incorporating second magnetically oriented platelet-shaped magnetic or magnetisable pigment particles, wherein the at least partially cured second coating layer (241) at least partially (FIG. 2G) or completely (FIG. 2H) overlaps the at least partially cured first coating layer (240) and is in contact with the at least partially cured first coating layer (240). FIG. 2 shows a schematic cross-section of an OEL, in which substantially all first platelet-shaped magnetic or magnetisable pigment particles in the at least partially cured second coating layer (240) have substantially the same elevation angle γ and substantially all second platelet-shaped magnetic or magnetisable pigment particles in the at least partially cured second coating layer (241) have substantially the same other elevation angle γ', said elevation angle γ and the other elevation angle γ' being different and / or non-coplanar with respect to one another, and in which first particles in the at least partially cured first coating layer (240) have a d50 value greater than T and second particles in the at least partially cured second coating layer (241) have a d50 value greater than T'. [Figure 3A] FIG. 3A is a schematic cross-sectional view of a suitable magnetic field generating device (330) consisting of a rod-shaped dipole magnet for orienting plate-shaped magnetic or magnetizable pigment particles in a coating layer (310) on a substrate (320), in which the plate-shaped magnetic or magnetizable pigment particles are exposed to the magnetic field of the magnetic field generating device (330) (magnetic field lines shown as arrowed lines going from the north pole to the south pole) in two areas where the magnetic field is substantially non-uniform (shown as A and A'). [Figure 3B]FIG. 3B is a schematic cross-sectional view of a suitable magnetic field generating device (330) consisting of a rod-shaped dipole magnet for orienting plate-shaped magnetic or magnetizable pigment particles in a coating layer (310) on a substrate (320), in which the plate-shaped magnetic or magnetizable pigment particles are exposed to the magnetic field of the magnetic field generating device (330) (magnetic field lines shown as arrowed lines going from the north pole to the south pole) in two areas where the magnetic field is substantially non-uniform (shown as A and A'). [Figure 3C] FIG. 3C is a schematic cross-sectional view of a suitable magnetic field generating device (330) consisting of a rod-shaped dipole magnet for orienting plate-shaped magnetic or magnetizable pigment particles in a single discontinuous coating layer (310) having two regions (310-a and 310-b) or in two coating layers (310-a and 310-b) on a substrate (320), where the plate-shaped magnetic or magnetizable pigment particles in the two regions (310-a and 310-b) are exposed to the magnetic field (magnetic field lines shown as arrowed lines going from the north pole to the south pole) of the magnetic field generating device (330) in one area each, and the magnetic field is substantially non-uniform (shown as A and A'). [Figure 3D] FIG. 3D is a schematic cross-sectional view of a suitable magnetic field generating device (330) consisting of a rod-shaped dipole magnet for orienting plate-shaped magnetic or magnetizable pigment particles in a coating layer (310) on a substrate (320), in which the plate-shaped magnetic or magnetizable pigment particles are exposed to the magnetic field of the magnetic field generating device (330) (magnetic field lines shown as arrowed lines going from the north pole to the south pole) in two areas where the magnetic field is substantially non-uniform (shown as A and A'). [Figure 4]FIG. 4 is a schematic diagram of a magnetic field generating device (430) suitable for orienting plate-shaped magnetic or magnetizable pigment particles in a coating layer (410) on a substrate (420), the magnetic field generating device (430) consisting of two rod-shaped dipole magnets (M1, M2) with the same magnetic field direction and an iron yoke (Y), in which the plate-shaped magnetic or magnetizable pigment particles are exposed to the magnetic field of the rod-shaped dipole magnets (430) in one area (magnetic field lines shown as arrowed lines going from the north pole to the south pole), the magnetic field is substantially uniform (shown as a dotted rectangle A), and the substrate (420) with the coating layer (410) is provided in the area A at a specific angle α. [Figure 5A] 5A and 5B are diagrams showing the change in elevation angle γ of plate-shaped magnetic or magnetizable pigment particles magnetically oriented by the magnetic field of the magnetic field generator shown in FIG. 3A in an at least partially cured coating layer (Examples E1, E2 and Comparative Examples C1, C2), where the x-axis (mm) corresponds to the distance from the edge of the at least partially cured layer (x40), and the value of 15 mm corresponds to the center of the magnetic field generator shown in FIG. 3A and the center of the at least partially cured layer (x40). [Figure 5B] 5A and 5B are diagrams showing the change in elevation angle γ of plate-shaped magnetic or magnetizable pigment particles magnetically oriented by the magnetic field of the magnetic field generator shown in FIG. 3A in an at least partially cured coating layer (Examples E1, E2 and Comparative Examples C1, C2), where the x-axis (mm) corresponds to the distance from the edge of the at least partially cured layer (x40), and the value of 15 mm corresponds to the center of the magnetic field generator shown in FIG. 3A and the center of the at least partially cured layer (x40). [Figure 6]FIG. 6 is a schematic diagram of a magnetic field generating device (630) as disclosed in co-pending European Patent Application No. 20194060.8, the magnetic field generating device (630) consisting of a rod-shaped dipole magnet used for orienting plate-shaped magnetic or magnetizable pigment particles in a coating layer (610) on a substrate (620), the plate-shaped magnetic or magnetizable pigment particles being exposed to the magnetic field of the magnetic field of the magnetic field generating device (630) in one area (shown as B) where the magnetic field is substantially uniform (magnetic field lines shown as arrowed lines going from the north pole to the south pole), the substrate (620) having a coating layer (610) being provided in said area B where the magnetic field is substantially uniform, the angle α between the coating layer (610) and the tangent of the magnetic field lines of the magnetic field in the area B where the magnetic field is substantially uniform being approximately 30°.

[0019]

[0017] The magnetic field lines (shown as arrowed lines going from the north pole to the south pole) of the magnetic field generating device (x30) shown in the drawings for illustrative purposes were obtained by a magnetic field simulation performed using the software Vizimag 3.19.

[0020] [Detailed Description] (definition) The following definitions are intended to interpret the meaning of terms used in the specification and claims.

[0021]

[0019] As used herein, the term "at least one" is intended to define one or more than one (eg, 1, 2, or 3).

[0022]

[0020] In this specification, the terms "about" and "substantially" mean that the amount or value in question may be the specified particular value or other values ​​in its vicinity. In general, the terms "about" and "substantially" referring to a value are intended to indicate a range of ±5% of the value. As an example, the expression "about 100" indicates a range of 100 ±5, i.e., a range of 95 to 105. In general, when the term "about" is used, it can be expected that similar results or effects according to the present invention can be obtained within a range of ±5% of the specified value.

[0023] The term "substantially parallel" means at least 1 mm 2 represents a deviation from parallel alignment of no more than 2° on average over the surface of the coating layer or over at least about 100 particles.

[0024]

[0022] In this specification, the term "and / or" means that all or only one of the elements of the group may be present. For example, "A and / or B" is intended to mean "A only, B only, or both A and B." In the case of "A only," the term also covers the possibility that B is not present, i.e., "A only and not B."

[0025]

[0023] In this specification, the term "comprising" is intended to be non-exclusive and open-ended. Thus, for example, a coating composition containing compound A may contain compounds other than A. However, the term "comprising" also encompasses the more restrictive meanings of "consisting essentially of" and "consisting of" as a specific embodiment thereof, so that, for example, a "mixture comprising A, B, and optionally C" may consist essentially of A and B, or may consist essentially of A, B, and C.

[0026]

[0024] As used herein, the term "optical effect layer (OEL)" refers to a coating or layer comprising oriented magnetic or magnetizable pigment particles, wherein the magnetic or magnetizable pigment particles are oriented by a magnetic field and the oriented magnetic or magnetizable pigment particles are fixed / suspended in their respective orientation and position (i.e., after curing) to form a magnetically induced image.

[0027]

[0025] The term "coating composition" refers to any composition capable of forming an optical effect layer (OEL) on a solid substrate and suitable, but not exclusively, applicable by printing methods. The coating composition comprises the platelet-shaped magnetic or magnetizable pigment particles described herein and the binder described herein.

[0028]

[0026] As used herein, the term "wet" refers to an at least partially uncured coating layer (e.g., a coating in which the plate-like magnetic or magnetizable pigment particles are still able to change their respective positions and orientations under the influence of external forces acting on them).

[0029]

[0027] The term "security document" refers to a document that is typically protected against counterfeiting or fraud by at least one security feature. Examples of security documents include, but are not limited to, value documents and value items.

[0030]

[0028] The term "security feature" is used to denote an image, pattern, or graphic element that can be used for authentication purposes.

[0031]

[0029] Whenever "preferred" embodiments / features are referred to in this specification, combinations of these "preferred" embodiments / features are also considered to be disclosed to the extent that such combinations of "preferred" embodiments / features are technically significant.

[0032]

[0030] The present invention provides a method for producing one or more optical effect layers (OELs) and the resulting optical effect layer (OEL), said OEL comprising plate-like magnetic or magnetizable pigment particles on a substrate (x20) having a two-dimensional surface and based on magnetically oriented plate-like magnetic or magnetizable pigment particles incorporated in an at least partially cured coating layer (x40).

[0033]

[0031] The present invention further provides an OEL comprising an at least partially cured layer (x40) constituted by a radiation curable coating composition comprising magnetically oriented plate-like magnetic or magnetisable pigment particles having a thickness T and having a major axis X and a d50 value as described herein, wherein the thickness T of the at least partially cured coating layer (x40) is smaller than the d50 value of the plate-like magnetic or magnetisable pigment particles, and wherein adjacent magnetically oriented plate-like magnetic or magnetisable pigment particles at least each have major axes X that are substantially parallel to each other in one or more regions (x40-a, x40-b) of said at least partially cured layer (x40).

[0034]

[0032] The present invention further provides security documents and decorative articles comprising a substrate (x20) as described herein and one or more optical effect layers (OEL) on said substrate (x20).

[0035] Representative examples of decorative articles include, but are not limited to, luxury goods, cosmetic packaging, automotive parts, electronic / appliance products, furniture, and nail articles. Alternatively, one or more of the OELs described herein may be provided on a secondary substrate, such as a label, so that they can be transferred to the decorative article in a separate step.

[0036]

[0034] Security documents include, but are not limited to, value documents and value goods. Representative examples of value documents include banknotes, certificates, tickets, cheques, vouchers, revenue and tax stamps, contracts, etc., identity documents such as passports, identity cards, visas, driver's licenses, bank cards, credit cards, transaction cards, access documents or cards, admission tickets, public transport tickets, academic certificates or title deeds, etc., with banknotes, identity documents, title deeds, driver's licenses and credit cards being preferred, but not limited to them. The term "value commercial good" refers in particular to packaging materials for cosmetics, dietary supplements, medicines, alcohol, tobacco products, beverages or foodstuffs, electrical / electronic products, textiles or jewellery, i.e. goods whose contents should be guaranteed by protection against counterfeiting and / or illegal copying, for example genuine medicines. Examples of these packaging materials include, but are not limited to, labels and stickers, such as certified brand labels, tamper-proof labels, etc. It should be noted that the disclosed substrates, security documents, and decorative articles are presented for illustrative purposes only, without limiting the scope of the invention. Alternatively, one or more OELs described herein may be provided on a secondary substrate, such as a security thread, security stripe, foil, decal, window, or label, so that they are transferred to the security document in a separate step.

[0037]

[0035] The shape of one or more OELs described herein may be continuous or discontinuous. According to one embodiment, the shape of one or more OELs independently represent one or more indicia, dots, and / or lines. For embodiments in which the security document and decorative article comprises more than one OEL, i.e. two, three, etc., said OELs may be adjacent to each other, spaced apart from each other, or overlapping each other partially or completely.

[0038]

[0036] The platelet-shaped magnetic or magnetisable pigment particles are comprised in the radiation curable coating composition, the coating layer (x10) and the at least partially cured coating layer (x40) described herein. As described herein, the method described herein comprises a step c) of at least partially curing the coating layer (x10) to a second state, in which the platelet-shaped magnetic or magnetisable pigment particles are fixed in their current position and orientation and cannot move or rotate any more within said layer. In this specification, "at least partially curing the coating layer (x10)" means that the platelet-shaped magnetic or magnetisable pigment particles are fixed / stopped in their respective adopted positions and orientations and cannot move or rotate any more (also referred to in the art as "pinning" the particles).

[0039]

[0037] As described herein, one or more of the OELs described herein comprise magnetically oriented plate-like magnetic or magnetizable pigment particles in the at least partially cured coating layer (x40). The plate-like magnetic or magnetizable pigment particles described herein are preferably present in an amount of about 5% to about 40% by weight, more preferably about 10% to about 30% by weight, the weight percentage being based on the total weight of the at least partially cured coating layer. The plate-like magnetic or magnetizable pigment particles described herein are preferably present in an amount of about 5% to about 40% by weight, more preferably about 10% to about 30% by weight, the weight percentage being based on the total weight of the radiation curable coating layer described herein.

[0040]

[0038] The platelet-shaped magnetic or magnetisable pigment particles described herein are defined as being non-spherical in shape and therefore non-isotropically reflective to incident electromagnetic radiation to which at least a portion of the cured binder material is transparent. As used herein, the term "non-isotropic reflectivity" indicates that the proportion of incident radiation from a first angle that is reflected by the particle in a particular (viewing / observation) direction (second angle) is a function of the particle's orientation, i.e., the magnitude of reflection in the viewing / observation direction may vary as the particle's orientation changes relative to the first angle. The platelet-shaped magnetic or magnetisable pigment particles described herein are non-isotropically reflective to incident electromagnetic radiation in part or all of the wavelength range of from about 200 to about 2500 nm, more preferably from about 400 to about 700 nm, such that a change in particle orientation changes the reflection by the particle in a particular direction. As known to those skilled in the art, the magnetic or magnetizable pigment particles described herein differ from conventional pigments in that they exhibit reflectance, color, or both that depend on particle orientation, whereas conventional pigment particles exhibit the same color and reflectivity regardless of particle orientation. In contrast to needle-shaped pigment particles, which are considered one-dimensional particles, platelet-shaped pigment particles have x and y axes that define the particle's major plane of extension (Figure 1). In other words, as shown in Figure 1, platelet-shaped pigment particles may be considered two-dimensional particles due to their large dimensional aspect ratio, with dimensions X and Y being substantially larger than dimension Z. Platelet-shaped pigment particles are also referred to in the art as flat particles or flakes. Such pigment particles may be described with a major axis X corresponding to the longest dimension across each pigment particle, and a second major axis Y perpendicular to X that is also present within the pigment particle.

[0041]

[0039] The OEL described herein comprises magnetically oriented or platelet-shaped magnetic or magnetizable pigment particles in an at least partially cured coating layer (x40) described herein, wherein the orientation of the platelet-shaped magnetic or magnetizable pigment particles is defined by a plate vector, which is a vector parallel to the particle's primary axis X, the plate vectors of adjacent platelet-shaped magnetic or magnetizable pigment particles are substantially parallel to each other (see, for example, Figure 2A), and the plate vectors of the platelet-shaped magnetic or magnetizable pigment particles have, at the particle's location, an elevation angle γ as described herein relative to the two-dimensional surface of the substrate (x20).

[0042]

[0040] As described herein, the platelet-shaped magnetic or magnetisable pigment particles in the at least partially cured coating layer (x40) are oriented at an elevation angle γ as described herein, in other words, the elevation angle is made by the main axis X of the platelet-shaped magnetic or magnetisable pigment particle and the two-dimensional surface of the substrate (x20).

[0043]

[0041] In the embodiment where the platelet-shaped magnetic or magnetisable pigment particles are uniaxially oriented, the orientation of the platelet-shaped pigment particles is defined by a plate vector, which is a vector parallel to the particle's main axis X, the plate vectors of adjacent platelet-shaped magnetic or magnetisable pigment particles being substantially parallel to each other, i.e. only the main axes X of adjacent platelet-shaped magnetic or magnetisable pigment particles are substantially parallel to each other (in other words adjacent platelet-shaped magnetic or magnetisable pigment particles have substantially the same elevation angle γ).

[0044]

[0042] In the embodiment where the platelet-shaped magnetic or magnetisable pigment particles are biaxially oriented, the orientation of the platelet-shaped pigment particles is defined by a platelet vector, which is a vector parallel to the primary axis X of the particle, the platelet vectors of adjacent platelet-shaped magnetic or magnetisable pigment particles being parallel to each other. The orientation of the platelet-shaped pigment particles is further defined by a second platelet vector, which is a vector parallel to a second axis Y of the particle, the platelet vectors of adjacent platelet-shaped magnetic or magnetisable pigment particles being parallel to each other, and the second platelet vectors of said adjacent platelet-shaped magnetic or magnetisable pigment particles being parallel to each other.

[0045]

[0043] Suitable examples of platelet-shaped magnetic or magnetisable pigment particles as described herein include, but are not limited to, pigment particles comprising a magnetic metal selected from the group consisting of cobalt (Co), iron (Fe) and nickel (Ni), a magnetic alloy of iron, manganese, cobalt, nickel or a mixture of two or more thereof, a magnetic oxide of chromium, manganese, cobalt, iron, nickel or a mixture of two or more thereof, or a mixture of two or more thereof. The term "magnetic" with respect to metals, alloys and oxides covers ferromagnetic or ferrimagnetic metals, alloys and oxides. The magnetic oxides of chromium, manganese, cobalt, iron, nickel or a mixture of two or more thereof may be pure or mixed oxides. Examples of magnetic oxides include hematite (Fe2O3), magnetite (Fe3O4), chromium dioxide (CrO2), magnetic ferrite (MFe2O4), magnetic spinel (MR2O4), magnetic hexaferrite (MFe 12 O 19 Examples of iron oxides include, but are not limited to, iron oxides such as magnetic orthoferrite (RFeO3), magnetic garnet (M3R2(AO4)3), etc., where M represents a divalent metal, R represents a trivalent metal, and A represents a tetravalent metal.

[0046]

[0044] Examples of platelet-shaped magnetic or magnetisable pigment particles as described herein include, but are not limited to, pigment particles comprising a magnetic layer M made up of one or more of magnetic metals such as cobalt (Co), iron (Fe) or nickel (Ni) and magnetic alloys of iron, cobalt or nickel. The magnetic or magnetisable pigment particles may also be multi-layered, comprising one or more further layers. The one or more further layers are preferably a layer A independently composed of one or more materials selected from the group consisting of metal fluorides such as magnesium fluoride (MgF), silicon oxide (SiO), silicon dioxide (SiO), titanium oxide (TiO), and aluminum oxide (AlO), more preferably silicon dioxide (SiO); a layer B independently composed of one or more materials selected from the group consisting of metals and metal alloys, preferably reflective metals and reflective metal alloys, more preferably aluminum (Al), chromium (Cr), and nickel (Ni), even more preferably aluminum (Al); or a combination of one or more layers A as described above and one or more layers B as described above. Typical examples of platelet-shaped magnetic or magnetisable pigment particles having the above-mentioned multi-layer structures include, but are not limited to, A / M multi-layer structures, A / M / A multi-layer structures, A / M / B multi-layer structures, A / B / M / A multi-layer structures, A / B / M / B multi-layer structures, A / B / M / B / A multi-layer structures, B / M multi-layer structures, B / M / B multi-layer structures, B / A / M / A multi-layer structures, B / A / M / B multi-layer structures, B / A / B / M / B / A / B multi-layer structures, where layer A, magnetic layer M and layer B are selected from the above-mentioned layers.

[0047] According to one embodiment, the plate-shaped magnetic or magnetizable particles are preferably at least partially constituted by plate-shaped optically variable magnetic or magnetizable pigment particles. Optically variable pigments refer to pigments that exhibit a change in lightness or a combination of a change in lightness and a change in hue with a change in the viewing angle. According to one embodiment, at least partially the plate-shaped magnetic or magnetizable particles are constituted by particles that exhibit a metallic color, more preferably a silver or gold color.

[0048]

[0046] In addition to the overt security provided by the color changing properties of the optically variable magnetic or magnetisable pigment particles, which allows an article or security document having an ink, coating composition or coating layer comprising the optically variable magnetic or magnetisable pigment particles described herein to be easily detected, recognised and / or distinguished from possible counterfeits by human senses alone, the optical properties of the optically variable magnetic or magnetisable pigment particles may be used as a machine-readable tool for OEL recognition. Thus, the optical properties of the optically variable magnetic or magnetisable pigment particles may be used simultaneously as a covert or semi-covert security feature in an authentication process that analyses the optical (e.g. spectral) properties of the pigment particles, thereby improving counterfeit resistance.

[0049]

[0047] The use of plate-shaped optically variable magnetic or magnetisable pigment particles in an OEL makes said OEL a valuable security feature in security document applications, since such materials are intended for the security document printing industry and are not commercially available to the general public.

[0050] More preferably, the plate-shaped magnetic or magnetisable pigment particles are selected from the group consisting of magnetic thin film interference pigment particles, magnetic cholesteric liquid crystal pigment particles, interference coated magnetic pigment particles, and mixtures of two or more thereof.

[0051]

[0049] Magnetic thin film interference pigment particles are known to those skilled in the art and are disclosed, for example, in US Patent No. 4,838,648, WO 2002 / 073250, EP 0686675, WO 2003 / 000801, US Patent No. 6,838,166, WO 2007 / 131833, EP 2402401, WO 2019 / 103937, WO 2020 / 006286, and references cited therein. The magnetic thin film interference pigment particles preferably include pigment particles having a 5-layer Fabry-Perot multilayer structure, pigment particles having a 6-layer Fabry-Perot multilayer structure, pigment particles having a 7-layer Fabry-Perot multilayer structure, and / or pigment particles having a multilayer structure combining one or more multilayer Fabry-Perot structures.

[0052]

[0050] A preferred five-layer Fabry-Perot multilayer structure is made of a multilayer structure of absorber / dielectric / reflector / dielectric / absorber, where the reflector and / or absorber are also magnetic layers, preferably the reflector and / or absorber are magnetic layers containing nickel, iron, and / or cobalt, magnetic alloys containing nickel, iron, and / or cobalt, and / or magnetic oxides containing nickel (Ni), iron (Fe), and / or cobalt (Co). A preferred five-layer Fabry-Perot multilayer structure is made of a multilayer structure of dielectric / reflector / magnetic / reflector / dielectric, where the magnetic layers are preferably containing nickel, iron, and / or cobalt, magnetic alloys containing nickel, iron, and / or cobalt, and / or magnetic oxides containing nickel (Ni), iron (Fe), and / or cobalt (Co).

[0053] A preferred six-layer Fabry-Perot multilayer structure consists of an absorber / dielectric / reflector / magnetic / dielectric / absorber multilayer structure.

[0054] A preferred seven-layer Fabry-Perot multilayer structure consists of an absorber / dielectric / reflector / magnetic / reflector / dielectric / absorber multilayer structure as disclosed in US Pat. No. 4,838,648.

[0055]

[0053] Preferred pigment particles having a multilayer structure combining one or more Fabry-Perot structures are described in WO 2019 / 103937 and consist of a combination of at least two Fabry-Perot structures independently comprising a reflector layer, a dielectric layer and an absorber layer, each of which may independently comprise one or more magnetic materials and / or a magnetic layer is sandwiched between the two structures. WO 2020 / 006 / 286 and EP 3587500 disclose further preferred pigment particles having a multilayer structure.

[0056]

[0054] The reflector layers described herein are preferably independently comprised of one or more materials selected from the group consisting of metals and metal alloys, preferably selected from the group consisting of reflective metals and reflective metal alloys, more preferably selected from the group consisting of aluminum (Al), silver (Ag), copper (Cu), gold (Au), platinum (Pt), tin (Sn), titanium (Ti), palladium (Pd), rhodium (Rh), niobium (Nb), chromium (Cr), nickel (Ni), and alloys thereof, even more preferably aluminum (Al), chromium (Cr), nickel (Ni), and alloys thereof, still more preferably aluminum (Al). The dielectric layers are preferably independently composed of one or more materials selected from the group consisting of metal fluorides such as magnesium fluoride (MgF2), aluminum fluoride (AlF3), cerium fluoride (CeF3), lanthanum fluoride (LaF3), sodium aluminum fluoride (e.g., Na3AlF6), neodymium fluoride (NdF3), samarium fluoride (SmF3), barium fluoride (BaF2), calcium fluoride (CaF2), lithium fluoride (LiF), metal oxides such as silicon oxide (SiO), silicon dioxide (SiO2), titanium oxide (TiO2), aluminum oxide (Al2O3), more preferably magnesium fluoride (MgF2) and silicon dioxide (SiO2), even more preferably magnesium fluoride (MgF2). The absorber layers are independently composed of one or more materials preferably selected from the group consisting of aluminum (Al), silver (Ag), copper (Cu), palladium (Pd), platinum (Pt), titanium (Ti), vanadium (V), iron (Fe), tin (Sn), tungsten (W), molybdenum (Mo), rhodium (Rh), niobium (Nb), chromium (Cr), nickel (Ni), metal oxides thereof, metal sulfides, metal carbides, and metal alloys, more preferably selected from the group consisting of chromium (Cr), nickel (Ni), metal oxides thereof, and metal alloys, and even more preferably selected from the group consisting of chromium (Cr), nickel (Ni), and metal alloys thereof.The magnetic layer preferably comprises nickel (Ni), iron (Fe) and / or cobalt (Co), a magnetic alloy comprising nickel (Ni), iron (Fe) and / or cobalt (Co), and / or a magnetic oxide comprising nickel (Ni), iron (Fe) and / or cobalt (Co). When magnetic thin film interference pigment particles comprising a seven-layer Fabry-Perot structure are preferred, it is particularly preferred that the magnetic thin film interference pigment particles comprise a seven-layer Fabry-Perot multilayer structure of absorber / dielectric / reflector / magnetic / reflector / dielectric / absorber consisting of a Cr / MgF2 / Al / Ni / Al / MgF2 / Cr multilayer structure.

[0057]

[0055] The magnetic thin film interference pigment particles described herein are believed to be safe for human health and the environment and may be multi-layer pigment particles based on, for example, a 5-layer Fabry-Perot multi-layer, a 6-layer Fabry-Perot multi-layer, and a 7-layer Fabry-Perot multi-layer, said pigment particles comprising one or more magnetic layers comprising a substantially nickel-free magnetic alloy of a composition comprising, by weight, about 40% to about 90% iron, about 10% to about 50% chromium, and about 0% to about 30% aluminum. A typical example of a multi-layer pigment particle believed to be safe for human health and the environment can be found in EP 2402401, the entire contents of which are incorporated herein by reference.

[0058]

[0056] Suitable magnetic cholesteric liquid crystal pigment particles exhibiting optically variable properties include, but are not limited to, magnetic single-layer cholesteric liquid crystal pigment particles and magnetic multi-layer cholesteric liquid crystal pigment particles. Such pigment particles are disclosed, for example, in WO 2006 / 063926, U.S. Pat. No. 6,582,781, and U.S. Pat. No. 6,531,221. WO 2006 / 063926 discloses monolayers and pigment particles obtained therefrom having high brightness and color-changing properties as well as specific properties such as magnetizability. The disclosed monolayers and pigment particles obtained by grinding the monolayers comprise a three-dimensionally crosslinked cholesteric liquid crystal mixture and magnetic nanoparticles. U.S. Pat. No. 6,582,781 and U.S. Pat. No. 6,410,130 disclose a cholesteric liquid crystal pigment having a three-dimensionally crosslinked cholesteric liquid crystal mixture ... 1 / B / A2 The present invention discloses plate-shaped cholesteric multi-layer pigment particles of the formula: 1 and A 2 may be the same or different and each contain at least one cholesteric layer. B is layer A 1 and A 2 The intermediate layer absorbs all or part of the light transmitted from the substrate and imparts magnetic properties. U.S. Patent No. 6,531,221 discloses plate-like cholesteric multi-layer pigment particles in an arrangement A / B, optionally including C, where A and C are absorbing layers containing pigment particles imparting magnetic properties, and B is a cholesteric layer.

[0059]

[0057] Suitable interference coated magnetic pigment particles comprising one or more magnetic materials include, but are not limited to, structures consisting of a substrate selected from the group consisting of a core coated with one or more layers, where at least one of the core or the layer or layers is magnetic. For example, suitable interference coated pigment particles include a core composed of a magnetic material as described above, coated with one or more layers composed of one or more metal oxides, or have a structure consisting of a core composed of synthetic or natural mica, layered silicates (e.g., talc, kaolin, and sericite), glass (e.g., borosilicate), silicon dioxide (SiO2), aluminum oxide (Al2O3), titanium oxide (TiO2), graphite, and mixtures of two or more of these. In addition, one or more further layers, such as colored layers, may be present.

[0060]

[0058] The platelet-shaped magnetic or magnetisable pigment particles described in this specification may be surface treated to protect against any deterioration that may occur to the coating compositions and coating layers and / or to facilitate incorporation into said coating compositions and coating layers, typically with the use of corrosion inhibitors and / or wetting agents.

[0061] The method described herein comprises the steps of a) applying a radiation curable coating composition comprising platelet-shaped magnetic or magnetisable pigment particles as described herein to the surface of a substrate (x20) as described herein, said radiation curable coating composition being in a first liquid state allowing application as a coating layer (x10) and in an at least partially uncured (i.e. wet) state allowing the pigment particles to move and rotate within the layer. The radiation curable coating composition described herein, as applied to the surface of the substrate (x20), comprises at least a binder material and magnetic or magnetisable pigment particles and is in a form allowing processing on a desired printing or coating equipment. Step a) is preferably carried out by a printing process selected from the group consisting of screen printing, gravure printing, flexography, more preferably a printing process selected from the group consisting of screen printing and flexography, even more preferably flexography.

[0062] Depending on the printing process selected for the manufacture of one or more of the OELs described herein, suitable viscosity values ​​of the radiation curable coating compositions comprising platelet-shaped magnetic or magnetizable pigment particles are used: Screen printing inks have a viscosity of about 50 mPa·s to about 3000 mPa·s at 25° C., flexographic inks have a viscosity of about 50 mPa·s to about 2000 mPa·s at 25° C., and gravure inks have a viscosity of about 50 mPa·s to about 1000 mPa·s at 25° C. Viscosity measurements of security inks with viscosity values ​​between 100 mPa·s and 3000 mPa·s are carried out with a Brookfield viscometer (model "RVDV-I Prime"), the spindle and rotation speed (rpm) being adapted according to the viscosity range: spindle 21 at 100 rpm for viscosity values ​​between 100 and 500 mPa·s, spindle 27 at 100 rpm for viscosity values ​​between 500 mPa·s and 2500 mPa·s, and spindle 27 at 50 rpm for viscosity values ​​between 2500 mPa·s and 3000 mPa·s. Viscosity measurements of security inks with viscosity values ​​between 10 mPa·s and 100 mPa·s are carried out at 25°C and 1000 s. -1In this case, it is carried out using a TA Instruments rotational viscometer DHR-2 having a conical surface shape and a diameter of 40 mm.

[0063]

[0061] The method described in this specification includes, in b), exposing the coating layer (x10) to the magnetic field in one or more areas (A, A', A i ’) of the magnetic field of the magnetic field generating device (x30) described in this specification, thereby further including the step of orienting at least a part of the plate-shaped magnetic or magnetizable pigment particles. In step b) described in this specification, the substrate (x20) having the coating layer (x10) is provided in the one or more areas (A, A', A i ’ (where i corresponds to 2, 3, 4, etc.)), and the angle α formed by the tangent of the magnetic field lines of the magnetic field in the one or more areas and the two-dimensional surface of the substrate (x20) at the position of the particles is 12° or more and 75° or less (12° ≤ |α| ≤ 75°) or 105° or more and 168° or less (105° ≤ |α| ≤ 168°).

[0064]

[0062] In addition to the requirement that the thickness T of the at least partially cured coating layer (x40) is smaller than the d50 value of the plate-shaped magnetic or magnetizable pigment particles (T < d50), the thickness T of the at least partially cured coating layer (x40) is preferably smaller than d50 * sin(α) (T < d50 * (sinα)).

[0065]

[0063] According to one embodiment, the orientation of the plate-shaped magnetic or magnetizable pigment particles in the at least partially cured coating layer (x40) and the elevation angle γ of the particles are obtained by exposing the plate-shaped magnetic or magnetizable pigment particles to the magnetic field of the magnetic field generating device (x30) described in this specification in one or more areas (shown as areas A and A' in FIGS. 3A to 3D), and this magnetic field is substantially non-uniform (that is, the magnetic field does not have a substantially constant magnitude and direction throughout the (one or more) areas of interest (in the case of uniaxial orientation)), or is not substantially confined to a plane (in the case of biaxial orientation), and the angle α is the two-dimensional surface of the substrate (x20) at the position of the particles and one or more areas (A, A', A iand the tangent of the magnetic field lines in the magnetic field in the area x30'), said angle α being 12° to 75° (12°≦|α|≦75°) or 105° to 168° (105°≦|α|≦168°). If the plate-shaped magnetic or magnetizable pigment particles are exposed to the magnetic field of the magnetic field generator (x30) in two or more areas (for example the two areas shown in Figures 3A and 3C), then two angles α and α' are described, with angle α' being 12° to 75° (12°≦|α'|≦75°) or 105° to 168° (105°≦|α'|≦168°), and α' is different from α, preferably α' and α differ by at least 30°. In one embodiment, in which plate-shaped magnetic or magnetisable pigment particles are exposed to the magnetic field of a magnetic field generating device (x30) in two or more areas (for example the two areas shown in Figures 3A and 3C), a substrate (x20) having a coating layer (x10) is provided in said two or more areas at angles α and α', and when the angle α is 12° to 75° (12°≦|α'|≦75°), the angle α' is 105° to 168° (105°≦|α'|≦168°).

[0066]

[0064] The OEL obtained by exposure of platelet-shaped magnetic or magnetisable pigment particles in one or more areas where the magnetic field of a magnetic field generator (x30) is substantially non-uniform is provided that, during the orientation step, said magnetically oriented platelet-shaped magnetic or magnetisable pigment particles are subjected to different angles α as described herein (i.e. angle α in area A is different from angle α' in area A'), but these angles have values ​​within the ranges described herein. An example of a magnetic field generator suitable for orienting platelet-shaped magnetic or magnetisable pigments, where the magnetic field is substantially non-uniform in one or more areas denoted as A and A', is a rod-shaped dipole magnet with its magnetic axis substantially parallel to the surface of the substrate (x20), as shown in Figure 3 and described below. Other examples of magnetic field generating devices suitable for orienting platelet-shaped magnetic or magnetisable pigments, where the magnetic field is substantially non-uniform in one or more areas, are disclosed in Figures 5A, 5B, 9B-9E, 10A and 10B of US Patent No. 7,047,883, as described below. Advantageously, the present invention provides a method for producing OELs with uniform pigment orientation over a large surface, even when the exposure step is performed with a non-uniform magnetic field.

[0067] According to one embodiment, the orientation of the platelet-shaped magnetic or magnetisable pigment particles in the at least partially cured coating layer (x40) and the elevation angle γ of said particles are obtained by exposing the platelet-shaped magnetic or magnetisable pigment particles in one or more areas (shown as area A in FIG. 4 ) to a magnetic field of a magnetic field generator (x30) as described herein, which magnetic field is substantially uniform (i.e. the magnetic field has a substantially constant magnitude and direction over the area(s) of interest (in the case of uniaxial orientation)) or is substantially confined to a plane (in the case of biaxial orientation), and the angle α is determined by the relationship between the two-dimensional surface of the substrate (x20) at the location of the particles and one or more areas (A, A′, A′). iwith a tangent to the magnetic field lines of the magnetic field in the magnetic field generator (x30) within the region x10'), said angle α being between 12° and about 75° (12°≦|α|≦75°) or between 105° and 168° (105°≦|α|≦168°). The OEL obtained by exposure of the platelet-shaped magnetic or magnetisable pigment particles in one or more areas where the magnetic field of the magnetic field generator (x30) is substantially uniform is such that, during the orientation step, said magnetically oriented platelet-shaped magnetic or magnetisable pigment particles will be at substantially the same angle α as described herein.

[0068]

[0066] Step b) described herein is carried out in order to uniaxially or biaxially orient at least a portion of the platelet-shaped magnetic or magnetisable pigment particles described herein. In contrast to uniaxial orientation, in which the magnetic or magnetisable pigment particles are oriented such that only the main axis is subject to the constraint of the magnetic field, carrying out a biaxial orientation means orienting the platelet-shaped magnetic or magnetisable pigment particles such that the two main axes X and Y are subject to the constraint. That is to say, each platelet-shaped magnetic or magnetisable pigment particle can be considered to have a major axis in the plane of the pigment particle and a minor axis perpendicular to the plane of the pigment particle. The axes Y and Y of the platelet-shaped magnetic or magnetisable pigment particles are respectively oriented according to the magnetic field. In practical terms, this results in platelet-shaped magnetic pigment particles that are close to each other in space and adjacent to each other being substantially parallel to each other. In other words, biaxial orientation aligns the planes of the platelet-shaped magnetic or magnetisable pigment particles such that the planes of the platelet-shaped magnetic or magnetisable pigment particles are oriented such that they are substantially parallel to the planes of the adjacent platelet-shaped magnetic or magnetisable pigment particles (in all directions).

[0069] According to one embodiment, step b) is carried out to uniaxially orient at least a portion of the platelet-shaped magnetic or magnetisable pigment particles described herein. There are no limitations on suitable magnetic field generating devices for uniaxially orienting the platelet-shaped magnetic or magnetisable pigment particles described herein.

[0070] According to one embodiment shown in Figures 3A-3D, a suitable magnetic field generator (330) for uniaxially orienting at least a portion of the platelet-shaped magnetic or magnetizable pigment particles consists of a rod-shaped dipole magnet with its magnetic axis substantially parallel to the surface of the substrate (x20). As shown in Figures 3A-3D, the platelet-shaped magnetic or magnetizable pigment particles in the coating layer (310) on the substrate (320) are exposed in one or more areas (shown as areas A and A') to a magnetic field (magnetic field lines shown as arrowed lines going from north pole to south pole) of the magnetic field generator (330) as described herein, which is substantially non-uniform and the substrate (320) with the coating layer (310) is provided in said one or more areas at an angle α as described herein.

[0071] According to one embodiment shown in Fig. 4 and used in the following examples, a suitable magnetic field generator (430) for uniaxially orienting at least a portion of platelet-shaped magnetic or magnetizable pigment particles consists of a rectangular assembly with two rod-shaped dipole magnets (M1, M2) and two pole pieces (P1, P2). Platelet-shaped magnetic or magnetizable pigment particles in a coating layer (410) on a substrate (420) are exposed to a magnetic field (magnetic field lines shown as arrowed lines going from north pole to south pole) of the magnetic field generator (430) in one or more areas (shown as dotted rectangle A), which is substantially uniform and the magnetic field lines are substantially parallel to each other in said areas, and the substrate (420) with the coating layer (410) is provided in said one or more areas at an angle α as described herein. The magnetic field generator (430) shown in Fig. 4 comprises two spaced apart rod-shaped dipoles (M1, M2) having the same magnetic field direction and length, and two spaced apart magnetic pole pieces (P1, P2) having the same length, arranged in a rectangular assembly, where M1 faces M2 but not adjacent to it, P1 faces P2 but not adjacent to it, and P1 is located at a distance from P2 corresponding to the length of M1 / M2.

[0072]

[0070] According to another embodiment, in a suitable magnetic field generating device (430) for uniaxially orienting at least a portion of plate-shaped magnetic or magnetizable pigment particles as shown in Figures 5A, 5B, 9B-9E, 10A and 10B of U.S. Pat. No. 7,047,883, the plate-shaped magnetic or magnetizable pigment particles in a coating layer on a substrate are exposed to a magnetic field of the magnetic field generating device in one or more areas, which magnetic field is substantially non-uniform, and the substrate having a coating layer (410) is provided in said one or more areas at an angle α as described in the present specification. In particular, the magnetic field generating device shown in Figures 5A and 5B of US Patent No. 7,047,883 includes two spaced apart magnets 84 disposed on a magnetic base 62 with their north poles facing the substrate; the magnetic field generating device shown in Figure 9B of US Patent No. 7,047,883 includes a magnet 140 with the pigment article disposed at an offset position relative to the magnet axis; the magnetic field generating device shown in Figure 9C of US Patent No. 7,047,883 includes two magnets 142 and one magnet 142' having a diamond-shaped cross section, with the two magnets 142 facing their north poles toward the substrate while the magnet 142' between them faces their south pole toward the substrate; and the magnetic field generating device shown in Figure 9D of US Patent No. 7,047,883 includes two magnets 142 and one magnet 142' having a diamond-shaped cross section with the two magnets 142 facing their north poles toward the substrate while the magnet 142' between them faces their south pole toward the substrate. The magnetic field generating device shown in FIG. 9E of U.S. Pat. No. 7,047,883 includes a stone 144 and one magnet 142' with one magnet 144' having a roof-shaped, hexagonal, circular, trapezoidal, or other cross-section, where two of the magnets 144 face their north poles toward the substrate while the magnet 144' between them faces its south pole toward the substrate. The magnetic field generating device shown in FIG. 9E of U.S. Pat. No. 7,047,883 includes five magnets (a first magnet 142 which is a diamond-shaped magnet with its north pole facing the substrate, a second magnet 146 which is a rectangular magnet with its south pole facing the substrate, a third magnet 148 which is a circular top magnet with its north pole facing the substrate, a fourth magnet 150 which is a roof-shaped magnet with its south pole facing the substrate, and a fifth magnet 152 which is also a roof-shaped magnet with its north pole facing the substrate).

[0073]

[0071] According to another embodiment, step b) is performed to biaxially orient at least a portion of the platelet-shaped magnetic or magnetisable pigment particles. In the embodiment where the method described herein comprises the step of biaxially orienting at least a portion of the magnetic or magnetisable pigment particles by exposing the coating layer (x10) to the magnetic field of a magnetic field generator (x30) described herein, the coating layer (x10) may be exposed to said magnetic field generator more than once. There is no limitation on suitable magnetic field generators for biaxially orienting the platelet-shaped magnetic or magnetisable pigment particles described herein. As the skilled person will appreciate, biaxial orientation of platelet-shaped magnetic or magnetisable pigment particles requires a dynamic magnetic field (i.e. a time-variable / time-dependent magnetic field) that changes direction and / or intensity to vibrate the particles until both principal axes (X-axis and Y-axis) are aligned. In other words, biaxial orientation requires unentrained movement of the coating layer (x10) comprising the platelet-shaped magnetic or magnetisable pigment particles relative to the magnetic field generator.

[0074] According to one embodiment shown in figures 10A and 10B of WO 2018 / 019594, a suitable magnetic field generating device (430) for biaxially orienting at least a portion of the platelet-shaped magnetic or magnetisable pigment particles consists of a linear arrangement of at least four magnets (M1-M4) arranged in a staggered or zigzag manner, provided that the substrate with the coating layer is provided in one or more areas of the magnetic field of the device with the angle α values ​​described herein. EP 2 157 141 A1 discloses in figure 5 a similar suitable magnetic field generating device, which may be used for biaxially orienting at least a portion of the platelet-shaped magnetic or magnetisable pigment particles, and which consists of a linear arrangement of at least three, preferably at least four, magnets arranged in a staggered or zigzag manner.

[0075]

[0073] According to one embodiment shown in Figures 8A and 8B of WO 2018 / 019594, a suitable magnetic field generating device (430) for biaxially orienting at least a portion of the plate-shaped magnetic or magnetizable pigment particles consists of two dipole magnets (M1, M2) with opposite magnetic field directions, provided that the substrate with the coating layer is placed in one or more areas of the magnetic field of the device with an angle α value as described in this specification.

[0076]

[0074] According to one embodiment shown in Figures 7A and 7B of WO 2018 / 019594, a suitable magnetic field generating device (430) for biaxially orienting at least a portion of the plate-shaped magnetic or magnetizable pigment particles consists of two dipole magnets (M1, M2) with the same magnetic field direction, provided that the substrate with the coating layer is placed in one or more areas of the magnetic field of the device with the angle α value described in this specification.

[0077]

[0075] According to one embodiment shown in Figure 3A of WO 2018 / 019594, a suitable magnetic field generating device (430) for biaxially orienting at least a portion of the plate-shaped magnetic or magnetizable pigment particles consists of a Halbach array including five dipole magnets (M1 to M5), provided that the substrate having the coating layer is placed in one or more areas of the magnetic field of the device with the angle α values ​​described in the present specification.

[0078]

[0076] According to one embodiment shown in Figure 12A of WO 2016 / 083259, a suitable magnetic field generating device for biaxially orienting at least a portion of the plate-shaped magnetic or magnetizable pigment particles consists of a Halbach cylinder assembly including four structures (M1-M4) each comprising a magnetic bar surrounded by a magnet wire coil (not shown), provided that the substrate having a coating layer is located in one or more areas of the magnetic field of the device with an angle α value as described in the present specification.

[0079] According to one embodiment, shown in FIG. 2A of co-pending European Patent Application No. 20176506.2, a suitable magnetic field generating device (430) for biaxially orienting at least a portion of the plate-shaped magnetic or magnetisable pigment particles consists of an assembly of eight bar-shaped dipole magnets (M1-M8), including a first set including a first bar-shaped dipole magnet (M4) and two second bar-shaped dipole magnets (M1, M6), a second set including a first bar-shaped dipole magnet (M5) and two second bar-shaped dipole magnets (M3, M8), and a first pair of third bar-shaped dipole magnets (M2, M7), provided that the substrate with the coating layer is disposed in one or more areas of the magnetic field of the device with the angle α values ​​described herein.

[0080] According to one embodiment shown in Figures 5A1 to 5A3 of co-pending European Patent Application No. 20194060.8, a suitable magnetic field generating device for biaxially orienting at least a portion of the plate-shaped magnetic or magnetizable pigment particles consists of an assembly comprising nine rod-shaped dipole magnets (M1 to M5) arranged in a row with alternating N-S magnetic field directions, provided that the substrate with the coating layer is placed in one or more areas of the magnetic field of the device with the angle α values ​​described in this specification.

[0081]

[0079] According to one embodiment, step b) as described herein comprises two magnetic orientation steps as described in WO 2015 / 086257, i) a biaxial orientation of at least a portion of the platelet-shaped magnetic or magnetisable pigment particles by exposing a coating layer (x10) comprising the platelet-shaped magnetic or magnetisable pigment particles to a dynamic magnetic field of a first magnetic field generating device as described above or as described in WO 2015 / 086257, and ii) a uniaxial reorientation of at least a portion of the platelet-shaped magnetic or magnetisable pigment particles by exposing the coating layer (x10) to a static magnetic field of a second magnetic field generating device as described herein, provided that the substrate (x20) carrying the coating layer (x10) is provided in one or more areas of the second magnetic field of the second magnetic field generating device with an angle α value as described herein. When these two steps i) and ii) are carried out, at least the second step ii) is used to orient at least a portion of the platelet-shaped magnetic or magnetisable pigment particles by providing a substrate (x20) with a coating layer (x10) at an angle α value as described herein in one or more areas as described herein.

[0082]

[0080] During the magnetic orientation of the magnetic or magnetizable pigment particles described in this specification, the substrate (x20) having the coating layer (x10) may be arranged on a non-magnetic support plate (x40) composed of one or more non-metallic materials.

[0083]

[0081] The method described herein further comprises, partially simultaneously with or after step b), step c) of fixing the position and orientation of the platelet-shaped magnetic or magnetisable pigment particles in the coating layer (x10) by at least partially curing the coating layer (x10) in a curing unit (x50) as described herein to produce an at least partially cured coating layer (x40) having a thickness T. By "partially simultaneously" it is meant that both steps are performed partially at the same time, i.e. there is a partial overlap in the timing of the performance of each step. In the context described herein, if the curing is performed partially simultaneously with the orientation step b), it should be understood that the curing is effective after the orientation so that the pigment particles have time to orient before the full or partial curing or solidification of the OEL.

[0084]

[0082] When step c) is performed after step b) described herein, the timing between said steps is preferably from about 0.1 seconds to about 1.5 seconds, more preferably from about 0.1 seconds to about 0.5 seconds.

[0085]

[0083] The methods described herein produce the OELs described herein, in which adjacent magnetically oriented plate-shaped magnetic or magnetizable pigment particles at least each have major axes X that are substantially parallel to each other in one or more regions (x40-a, x40-b) of the at least partially cured coating layer (x40).

[0086]

[0084] Suitable curing units (x50) include UV-visible light curing equipment with high power light emitting diode (LED) lamps or arc discharge lamps such as medium pressure mercury arc (MPMA) or metal vapor arc lamps as actinic radiation sources. The selective curing units described herein may include one or more fixed or removable photomasks that include one or more voids corresponding to the pattern to be formed as part of the coating layer. The selective curing units may be addressable, such as a scanning laser beam as disclosed in EP 2468423, an array of light emitting diodes (LEDs) as disclosed in WO 2017 / 021504, or an actinic radiation LED source including an array of individually addressable actinic radiation emitters as disclosed in WO 2020 / 148076.

[0087]

[0085] Figures 2A-2E disclose cross-sections of OELs described herein having one or more at least partially cured coating layers (240, 241) having a thickness (T, T', etc.) and incorporating magnetically oriented plate-like magnetic or magnetizable pigment particles.

[0088]

[0086] For example, according to one embodiment shown in Figure 2A, the OEL described herein comprises a single at least partially cured coating layer (210) having a thickness T and incorporating magnetically oriented plate-like magnetic or magnetizable pigment particles, wherein substantially all of the plate-like magnetic or magnetizable pigment particles in one or more regions have substantially the same elevation angle γ, and the pigment particles have a d50 value greater than T.

[0089]

[0087] According to one embodiment, for example as shown in FIG. 2B, an OEL described herein independently comprises a single at least partially cured coating layer (240) having a thickness T and comprising platelet-shaped magnetic or magnetizable pigment particles in one or more first regions (240-a) and platelet-shaped magnetic or magnetizable pigment particles in one or more second regions (240-b), wherein substantially all of the platelet-shaped magnetic or magnetizable pigment particles in the one or more first regions (240-a) have substantially the same elevation angle γ and substantially all of the platelet-shaped magnetic or magnetizable pigment particles in the one or more second regions (240-b) have substantially the same another elevation angle γ', said elevation angle γ and the another elevation angle γ' being different and / or non-coplanar with respect to each other, and the particles have a d50 value greater than T.

[0090]

[0088] For example, according to one embodiment shown in Figures 2C-2F, an OEL as described herein independently comprises an at least partially cured first coating layer (240) incorporating magnetically oriented plate-like magnetic or magnetisable pigment particles, substantially all of the plate-like magnetic or magnetisable pigment particles having substantially the same elevation angle γ and having a thickness T', and further comprises an at least partially cured second coating layer (241) incorporating magnetically oriented second plate-like magnetic or magnetisable pigment particles, substantially all of the plate-like magnetic or magnetisable pigment particles having substantially the same another elevation angle γ', said elevation angle γ and the other elevation angle γ' being different and / or non-coplanar with respect to one another, the pigment particles in the at least partially cured coating layer (240) having a d50 value greater than T and the pigment particles in the at least partially cured second coating layer (241) having a d50 value greater than T'. The at least partially cured second coating layer (241) may at least partially or completely overlap the at least partially cured coating layer (240) (see Figures 2C and 2D), be adjacent to the at least partially cured coating layer (240) (see Figure 2E), or be spaced apart from the at least partially cured coating layer (x10) (see Figure 2F).

[0091] FIG. 2C shows a schematic cross-section of an OEL comprising an at least partially cured first coating layer (240) having a thickness T and incorporating first magnetically oriented platelet-shaped magnetic or magnetisable pigment particles, and an at least partially cured second coating layer (241) having a thickness T′ and incorporating second magnetically oriented platelet-shaped magnetic or magnetisable pigment particles, said at least partially cured second coating layer (241) partially overlapping the at least partially cured first coating layer (240) and forming an at least partially cured coating layer (240). ) have substantially the same elevation angle γ, and substantially all of the second platelet-shaped magnetic or magnetisable pigment particles in the at least partially cured second coating layer (241) have substantially the same another elevation angle γ', said elevation angle γ and the another elevation angle γ' being different and / or non-coplanar with each other, and the first particles in the at least partially cured first coating layer (240) have a d50 value greater than T, and the second pigment particles in the at least partially cured second coating layer (241) have a d50 value greater than T'.

[0092] FIG. 2D shows a schematic cross-section of an OEL comprising an at least partially cured first coating layer (240) having a thickness T and incorporating first magnetically oriented platelet-shaped magnetic or magnetisable pigment particles, and an at least partially cured second coating layer (241) having a thickness T′ and incorporating second magnetically oriented platelet-shaped magnetic or magnetisable pigment particles, said at least partially cured second coating layer (241) completely overlapping the at least partially cured first coating layer (240) and forming a first at least partially cured second coating layer (241) having a thickness T′. Substantially all of the first platelet-shaped magnetic or magnetisable pigment particles in the at least partially cured second coating layer (240) have substantially the same elevation angle γ and substantially all of the second platelet-shaped magnetic or magnetisable pigment particles in the at least partially cured second coating layer (241) have substantially the same another elevation angle γ', said elevation angle γ and the another elevation angle γ' being different and / or non-coplanar with respect to each other, and the first particles in the at least partially cured first coating layer (240) have a d50 value greater than T and the second particles in the at least partially cured second coating layer (241) have a d50 value greater than T'.

[0093] FIG. 2E shows a schematic cross-section of an OEL comprising an at least partially cured first coating layer (240) having a thickness T and incorporating first magnetically oriented platelet-shaped magnetic or magnetisable pigment particles, and an at least partially cured second coating layer (241) having a thickness T′ and incorporating second magnetically oriented platelet-shaped magnetic or magnetisable pigment particles, said at least partially cured second coating layer (241) being adjacent to the at least partially cured coating layer (240) and in contact with the at least partially cured first coating layer (240). substantially all of the first platelet-shaped magnetic or magnetisable pigment particles in the at least partially cured second coating layer (240) have substantially the same elevation angle γ, substantially all of the second platelet-shaped magnetic or magnetisable pigment particles in the at least partially cured second coating layer (241) have substantially the same another elevation angle γ', said elevation angle γ and the another elevation angle γ' being different and / or non-coplanar with each other, and the first particles in the at least partially cured first coating layer (240) have a d50 value greater than T, and the second particles in the at least partially cured second coating layer (241) have a d50 value greater than T'.

[0094] FIG. 2F shows a schematic cross-section of an OEL comprising an at least partially cured first coating layer (240) having a thickness T and incorporating first magnetically oriented platelet-shaped magnetic or magnetisable pigment particles, and an at least partially cured second coating layer (241) having a thickness T′ and incorporating second magnetically oriented platelet-shaped magnetic or magnetisable pigment particles, said at least partially cured second coating layer (241) being spaced apart from the at least partially cured coating layer (240) and at least partially cured with respect to the first at least partially cured coating layer (241). substantially all of the first platelet-shaped magnetic or magnetisable pigment particles in the at least partially cured second coating layer (240) have substantially the same elevation angle γ and substantially all of the second platelet-shaped magnetic or magnetisable pigment particles in the at least partially cured second coating layer (241) have substantially the same another elevation angle γ', said elevation angle γ and the another elevation angle γ' being different and / or non-coplanar with respect to one another, the first particles in the at least partially cured first coating layer (240) have a d50 value greater than T and the second particles in the at least partially cured second coating layer (241) have a d50 value greater than T'.

[0095] FIG. 2G shows a schematic cross-section of an OEL comprising an at least partially cured first coating layer (240) having a thickness T and incorporating first magnetically oriented platelet-shaped magnetic or magnetisable pigment particles, and an at least partially cured second coating layer (241) having a thickness T′ and incorporating second magnetically oriented platelet-shaped magnetic or magnetisable pigment particles, said at least partially cured second coating layer (241) partially overlapping the at least partially cured coating layer (240) and intersecting the at least partially cured first coating layer (241). substantially all of the first platelet-shaped magnetic or magnetisable pigment particles in the at least partially cured second coating layer (240) have substantially the same elevation angle γ and substantially all of the second platelet-shaped magnetic or magnetisable pigment particles in the at least partially cured second coating layer (241) have substantially the same another elevation angle γ', said elevation angle γ and the another elevation angle γ' being different and / or non-coplanar with respect to one another, the first particles in the at least partially cured first coating layer (240) have a d50 value greater than T and the second particles in the at least partially cured second coating layer (241) have a d50 value greater than T'.

[0096] FIG. 2H shows a schematic cross-section of an OEL comprising an at least partially cured first coating layer (240) having a thickness T and incorporating first magnetically oriented platelet-shaped magnetic or magnetisable pigment particles, and an at least partially cured second coating layer (241) having a thickness T′ and incorporating second magnetically oriented platelet-shaped magnetic or magnetisable pigment particles, said at least partially cured second coating layer (241) completely overlapping the at least partially cured coating layer (240) and intersecting the at least partially cured first coating layer (241). substantially all of the first platelet-shaped magnetic or magnetisable pigment particles in the at least partially cured second coating layer (240) have substantially the same elevation angle γ and substantially all of the second platelet-shaped magnetic or magnetisable pigment particles in the at least partially cured second coating layer (241) have substantially the same another elevation angle γ', said elevation angle γ and the another elevation angle γ' being different and / or non-coplanar with respect to one another, the first particles in the at least partially cured first coating layer (240) have a d50 value greater than T and the second particles in the at least partially cured second coating layer (241) have a d50 value greater than T'.

[0097] According to one embodiment, the method described herein for producing one or more OELs described herein (see, e.g., FIG. 2A) comprised of a single, at least partially cured coating layer (x40) comprises: a) applying a radiation-curable coating composition comprising platelet-shaped magnetic or magnetisable pigment particles as described herein and in a first liquid state to a surface of a substrate (x20) as described herein to form a coating layer (x10); b) exposing the coating layer (x10) described herein to a magnetic field of a magnetic field generating device (x30) described herein, wherein the substrate (x20) carrying the coating layer (x10) is coated with one or more areas (A, A', A i '), where the angle α as described herein is greater than or equal to 12° and less than or equal to about 75° (12°≦|α|≦75°) or greater than or equal to 105° and less than or equal to 168° (105°≦|α|≦168°); c) partially simultaneously with or after step b), at least partially curing the coating layer (x10) in a curing unit (x50) thereby fixing at least a portion of the platelet-shaped magnetic or magnetisable particles in their adopted positions and orientations to produce a single at least partially cured coating layer (x40) having a thickness T smaller than the d50 value of the platelet-shaped magnetic or magnetisable pigment particles; Includes.

[0098] According to another embodiment, there is provided a method as described herein for producing one or more OELs as described herein, independently composed of a single at least partially cured coating layer (x40) and comprising magnetically oriented plate-like magnetic or magnetisable pigment particles in said single at least partially cured coating layer (x40), said single at least partially cured coating layer (x40) comprising one or more first regions (x40-a) as well as one or more second regions (x40-b) (see, for example, FIG. 2B), the method comprising: a) applying a radiation curable coating composition in a first liquid state to a surface of a substrate (x20) as described herein, the radiation curable coating composition comprising platelet-shaped magnetic or magnetisable pigment particles as described herein, and forming a coating layer (x10) comprising one or more first regions (x10-a) and one or more second regions (x10-b); b) exposing the coating layer (x10) described herein to a magnetic field of a magnetic field generating device (x30-a) described herein, wherein the substrate (x20) having the coating layer (x10) is coated with one or more areas (A, A', A i '), where the angle α as described herein is greater than or equal to 12° and less than or equal to about 75° (12°≦|α|≦75°) or greater than or equal to 105° and less than or equal to 168° (105°≦|α|≦168°); c) partially simultaneously with or after step b), fixing at least a portion of the plate-like magnetic or magnetisable particles in their adopted positions and orientations by at least partially selectively curing one or more first regions (x10a) of the single coating layer (x10) in a curing unit (x50); d) exposing the single coating layer (x10) to the magnetic field of a second magnetic field generator (x30-b) to orient at least a portion of the platelet-shaped magnetic or magnetisable pigment particles in one or more second regions (x10b), wherein the substrate (x20) is aligned in the one or more areas (A, A', A i ') and a two-dimensional surface of the substrate (x20) at the location of the plate-shaped magnetic or magnetizable pigment particles and one or more areas (A, A', A i an angle α' between the tangent of the magnetic field line of the second magnetic field in step b) and the magnetic field line of the second magnetic field in step c) is 12° or more and 75° or less (12°≦|α'|≦75°) or 105° or more and 168° or less (105°≦|α'|≦168°), the second magnetic field generator (x30-b) is either the same as or different from the magnetic field generator (x30-a) in step b), α' is different from α, and preferably α' and α differ by at least 30°; e) partially simultaneously with step d) or after step d), at least partially curing the single coating layer (x10) in a curing unit (x50) as described herein to produce a single at least partially cured coating layer (x40), in which adjacent magnetically oriented plate-shaped magnetic or magnetizable pigment particles at least each in one or more first regions (x40-a) of the single at least partially cured coating layer (x40) have main axes X that are substantially parallel to each other and adjacent magnetically oriented plate-shaped magnetic or magnetizable pigment particles at least each in one or more second regions (x40-b) of the single at least partially cured coating layer (x40) have main axes X that are substantially parallel to each other, Includes.

[0099]

[0097] According to another embodiment, there is provided a method as described herein for producing one or more OELs as described herein comprising magnetically oriented first platelet-shaped magnetic or magnetizable pigment particles in an at least partially cured first coating layer (x40) and magnetically oriented second platelet-shaped magnetic or magnetizable pigment particles in an at least partially cured second coating layer (x41), wherein the at least partially cured second coating layer (x41) at least partially or completely overlaps the at least partially cured first coating layer (x40) (see, for example, Figures 2C, 2D, 2G, and 2H), the method comprising: a) applying a first radiation-curable coating composition comprising first platelet-shaped magnetic or magnetisable pigment particles as described herein and in a first liquid state to a surface of a substrate (x20) as described herein to form a first coating layer (x10); b) exposing the coating layer (x10) described herein to a magnetic field of a magnetic field generating device (x30-a) described herein, whereby the substrate (x20) carrying the first coating layer (x10) is coated with one or more areas (A, A', A') described herein. i '), where the angle α as described herein is greater than or equal to 12° and less than or equal to about 75° (12°≦|α|≦75°) or greater than or equal to 105° and less than or equal to 168° (105°≦|α|≦168°); c) partially simultaneously with or after step b), at least partially curing the first coating layer (x10) in a curing unit (x50) thereby fixing at least a portion of the first plate-shaped magnetic or magnetisable particles in their adopted positions and orientations to produce an at least partially cured first coating layer (x40); d) after step c), applying partially (FIG. 2C or FIG. 2G) or completely (FIG. 2D or FIG. 2H) to the at least partially cured first coating layer (x40) a second radiation-curable coating composition comprising second platelet-shaped magnetic or magnetisable pigment particles and in a first liquid state to form a second coating layer (x11), said second radiation-curable coating composition being either the same as or different from the radiation-curable coating composition of step a); e) One or more areas (A, A', A) of the second magnetic field of the second magnetic field generating device (x30-b) i a step of orienting at least a portion of the second plate-shaped magnetic or magnetizable pigment particles by exposing the second coating layer (x11) to the second magnetic field, in which the substrate (x20) having the second coating layer (x41) is aligned in the one or more areas (A, A', A i and a two-dimensional surface of the substrate (x20) at the location of the second plate-shaped magnetic or magnetizable pigment particles and one or more areas (A, A', A i an angle α' between the tangent of the magnetic field line of the second magnetic field in step b) and the magnetic field line of the second magnetic field in step c) is 12° or more and 75° or less (12°≦|α'|≦75°) or 105° or more and 168° or less (105°≦|α'|≦168°), the second magnetic field generator (x30-b) is either the same as or different from the magnetic field generator in step b), α' is different from α, and preferably α' and α differ from each other by at least 30°; f) partially simultaneously with or after step e) of exposing the second coating layer (x11) to a second magnetic field, at least partially curing the second coating layer (x11) in a curing unit (x50) to at least partially fix the position and orientation of the second platelet-shaped magnetic or magnetisable pigment particles in the second coating layer (x11) to produce an at least partially cured second coating layer (x41), wherein adjacent magnetically oriented first platelet-shaped magnetic or magnetisable pigment particles are at least partially cured by the at least partially cured first platelet-shaped magnetic or magnetisable pigment particles, respectively. in the at least partially cured coating layer (x40), the first and second magnetically oriented plate-like magnetic or magnetizable pigment particles have main axes X substantially parallel to each other, and at least each of the adjacent magnetically oriented second plate-like magnetic or magnetizable pigment particles in the at least partially cured second coating layer (x41) have main axes X substantially parallel to each other, the magnetically oriented first plate-like magnetic or magnetizable pigment particles in the at least partially cured coating layer (x40) having a different elevation angle than the magnetically oriented second plate-like magnetic or magnetizable pigment particles in the at least partially cured second coating layer (x41); Includes.

[0100]

[0098] According to another embodiment, a method as described herein for producing one or more OELs as described herein comprising magnetically oriented first platelet-shaped magnetic or magnetizable pigment particles in an at least partially cured first coating layer (x40) and magnetically oriented second platelet-shaped magnetic or magnetizable pigment particles in an at least partially cured second coating layer (x41), wherein the at least partially cured second coating layer (x41) is adjacent to the at least partially cured first coating layer (x40) (see, for example, FIG. 2E) or spaced apart from the at least partially cured first coating layer (x40) (FIG. 2F), the method comprising: a) applying a first radiation-curable coating composition comprising first platelet-shaped magnetic or magnetisable pigment particles as described herein and in a first liquid state to a surface of a substrate (x20) as described herein to form a first coating layer (x10); b) exposing the first coating layer (x10) as described herein to a magnetic field of a magnetic field generating device (x30) as described herein, whereby the substrate (x20) carrying the first coating layer (x10) is coated with one or more areas (A, A', A') as described herein. i '), where the angle α as described herein is greater than or equal to 12° and less than or equal to about 75° (12°≦|α|≦75°) or greater than or equal to 105° and less than or equal to 168° (105°≦|α|≦168°); c) partially simultaneously with or after step b), at least partially curing the first coating layer (x10) in a curing unit (x50) thereby fixing at least a portion of the first plate-shaped magnetic or magnetisable particles in their adopted positions and orientations to produce an at least partially cured first coating layer (x40); d) after step c), applying a second radiation-curable coating composition in a first liquid state comprising second platelet-shaped magnetic or magnetisable pigment particles to form a second coating layer (x11), said second coating layer (x11) being adjacent to coating layer (x40) (Figure 2E) or spaced apart from coating layer (x40) (Figure 2F), said second radiation-curable coating composition being either the same as or different from the radiation-curable coating composition of step a); e) The second coating layer (x11) is exposed to one or more areas (A, A', A) of the second magnetic field of the second magnetic field generating device. i orienting at least a portion of the second platelet-shaped magnetic or magnetisable pigment particles by exposing them to said second magnetic field in said one or more areas (A, A', A'), i and a two-dimensional surface of the substrate (x20) at the location of the second plate-shaped magnetic or magnetizable pigment particles and one or more areas (A, A', A ian angle α' between the tangent of the magnetic field line of the second magnetic field in step b) and the magnetic field line of the second magnetic field in step c) is 12° or more and 75° or less (12°≦|α'|≦75°) or 105° or more and 168° or less (105°≦|α'|≦168°), the second magnetic field generator (x30-b) is either the same as or different from the magnetic field generator in step b), α' is different from α, and preferably α' and α differ from each other by at least 30°; f) partially simultaneously with or after step e) of exposing the second coating layer (x11) to a second magnetic field, at least partially curing the second coating layer (x11) in a curing unit (x50) thereby at least partially fixing the position and orientation of the second platelet-shaped magnetic or magnetisable pigment particles in the second coating layer (x11) to produce an at least partially cured second coating layer (x41), wherein the adjacent magnetically oriented first platelet-shaped magnetic or magnetisable pigment particles are at least at least each of the adjacent magnetically oriented plate-like magnetic or magnetisable pigment particles in the at least partially cured first coating layer (x40) have a main axis X that is substantially parallel to each other, and at least each of the adjacent magnetically oriented plate-like magnetic or magnetisable pigment particles in the at least partially cured second coating layer (x41) have a main axis X that is substantially parallel to each other, and the magnetically oriented particles in the at least partially cured coating layer (x40) have a different elevation angle than the magnetically oriented plate-like magnetic or magnetisable pigment particles in the at least partially cured second coating layer (x41); Includes.

[0101]

[0099] The OELs described herein optionally comprise the magnetically oriented plate-like magnetic or magnetisable pigment particles described herein in an at least partially cured coating layer (x40) and an at least partially cured second coating layer (x41), wherein the thickness T (see, for example, Figures 2A-2E) of the at least partially cured coating layer (x40) is smaller than the d50 value of the plate-like magnetic or magnetisable pigment particles and the thickness T' (see, for example, Figures 2C-2E) of the at least partially cured second coating layer (x41) is smaller than the d50 value of the plate-like magnetic or magnetisable pigment particles. Typically, the platelet-shaped magnetic or magnetisable pigment particles described herein have a d50 size (as measured by direct optical granulometry) of about 5 μm to about 30 μm and the at least partially cured coating layer (x40) has a thickness of about 3 μm to about 30 μm (in particular about 6 μm to about 30 μm for layers applied by screen printing, about 3 μm to about 20 μm for layers applied by gravure printing, and about 3 μm to about 20 μm for layers applied by flexographic printing), provided that said thickness is smaller than the d50 value of the platelet-shaped magnetic or magnetisable pigment particles. The thickness (T, T', etc.) of the at least partially cured coating layer (x40, x41, etc.) has a direct effect on the elevation angle γ of the platelet-shaped magnetic or magnetisable pigment particles on exposure to the magnetic field of the magnetic field generating device by forcing the particles to adopt a maximum elevation angle γ as a result of said thickness and the d50 value of the particles. This is advantageous because it makes it possible to freely select a magnetic field generating device to generate the above-mentioned OEL, regardless of whether the magnetic field is uniform or non-uniform.

[0102]

[0100] As described herein, the OEL comprises magnetically oriented plate-like magnetic or magnetisable pigment particles in an at least partially cured coating layer on a substrate. The substrate (x20) described herein is preferably selected from the group consisting of paper or cellulose, paper-containing materials, glass, metal, ceramic, plastic and other fibrous materials such as polymers (including woven and non-woven fibrous materials), metallized plastics or polymers, composites, and mixtures or combinations of two or more thereof. Representative paper, paper-like or other fibrous materials are composed of various fibers such as, but not limited to, abaca, cotton, hemp, wood pulp, and mixtures thereof. As known to those skilled in the art, cotton and cotton / hemp blends are preferred for banknotes, while wood pulp is commonly used for security documents other than banknotes. According to another embodiment, the substrate (x20) described herein is based on plastics and polymers, metallized plastics or polymers, composites, and mixtures or combinations of two or more thereof. Suitable examples of plastics and polymers include polyolefins such as polypropylene (PP), including polyethylene (PE) and biaxially oriented polypropylene (BOPP), polyamides, polyesters such as poly(ethylene terephthalate) (PET), poly(1,4-butylene terephthalate) (PBT), poly(ethylene 2,6-naphthoate) (PEN), and polyvinyl chloride (PVC). The substrate may also be spunbond olefin fibers, such as those sold under the trademark Tyvek®. Representative examples of metallized plastics or polymers include the above-mentioned plastic or polymer materials having a metal disposed continuously or discontinuously on the surface. Representative examples of metals include, but are not limited to, aluminum (Al), chromium (Cr), copper (Cu), gold (Au), silver (Ag), alloys thereof, and combinations of two or more of these metals. The metallization of the above-mentioned plastic or polymer materials may be performed by an electrodeposition process, a high vacuum coating process, or a sputtering process.Representative examples of composites include, but are not limited to, multi-layers or laminates of paper and at least one plastic or polymeric material as described above, as well as plastic and / or polymeric fibers incorporated into paper-like or fibrous materials as described above. Of course, the substrate may also include other additives known to those skilled in the art, such as fillers, sizing agents, whitening agents, processing aids, reinforcing or wet-strength agents. When the OELs described herein are used for decorative or cosmetic purposes, such as nail lacquers, the OELs may be produced on other types of substrates, including nails, artificial nails, or other parts of animals or humans. The substrates (x20) described herein may be in the form of webs, sheets, thread reels, film reels, rolls of labels, or label stock.

[0103]

[0101] When one or more OELs as described herein are present on a security document, the substrate may comprise a printed, coated, laser marked or laser drilled indicia, watermark, security thread, fiber, planchette, luminescent compound, window, foil, decal, and combinations of two or more thereof, for the purpose of providing a higher level of security and resistance to counterfeiting and illegal duplication of the security document. The substrate may also comprise one or more marker or traceable materials and / or machine readable materials (e.g., luminescent materials, UV / visible / IR absorbing materials, magnetic materials, and combinations thereof) for the same purpose of providing a higher level of security and resistance to counterfeiting and illegal duplication of the security document.

[0104] According to one embodiment, the security document and decorative article comprising the substrate (x20) and one or more OELs described herein further comprises one or more primer layers, said one or more primer layers being between the substrate (x20) and the one or more OELs. This may improve the quality or promote adhesion of the one or more OELs described herein. Examples of such primer layers can be found in WO 2010 / 058026. According to one embodiment, the one or more OELs described herein may further comprise one or more printed indicia (in other words, the one or more OELs at least partially overlap the one or more indicia) being between the substrate (x20) and the at least partially cured coating layer (x40). Preferably, the one or more OELs described herein and the one or more indicia described herein each independently have the shape of an indicia. As used herein, the terms "indicium and indicia" are intended to mean continuous and discontinuous layer(s) of identifying markings, indicia, or patterns. The indicium described herein is selected from the group consisting of codes, symbols, alphanumeric symbols, motifs, geometric patterns (e.g., circles, triangles, and regular or irregular polygons), letters, words, numbers, logos, drawings, portraits, and combinations thereof. Examples of codes include coded marks such as encoded alphanumeric data, one-dimensional bar codes, two-dimensional bar codes, QR codes, data matrices, and IR readable codes. The one or more indicia described herein may be solid indicia and / or raster indicia.

[0105]

[0103] The present invention provides a method for producing one or more OELs as described herein and one or more printed indicia present between a substrate (x20) and an at least partially cured coating layer (x40), the method further comprising, prior to step a) as described herein, applying a composition in the form of one or more indicia as described herein and at least partially curing or solidifying said composition. The step of applying a composition in the form of one or more indicia as described herein may be performed by a non-contact fluid micro-dispensing process such as curtain coating, spray coating, aerosol jet printing, electrohydrodynamic printing, and inkjet printing, or by a printing process selected from the group consisting of offset, screen printing, gravure printing, flexography, intaglio printing (also referred to in the art as copperplate intaglio printing, steel die intaglio printing). The present invention provides a method for producing one or more OELs as described herein and one or more printed indicia between the substrate (x20) and the at least partially cured coating layer (x40), as well as between the substrate (x20) and the at least partially cured second coating layer (x41), for example in the case of an OEL with two at least partially cured coating layers (x40, x41) as shown in FIG. 2E, the method further comprising the steps of applying, prior to step a) as described herein, a composition in the form of one or more indicia as described herein and at least partially curing or solidifying the composition.

[0106]

[0104] In order to improve the stain or chemical resistance and cleanliness and thus the shelf life or to improve the aesthetic appearance (e.g. gloss) of a security document or decorative article comprising one or more OELs as described herein, one or more protective layers may be applied onto the OEL(s). When present, the protective layer(s) typically consists of a protective varnish. The protective varnish may be a radiation curable composition, a heat drying composition, or any combination thereof. The protective layer(s) is preferably a radiation curable composition, more preferably a UV-visible light curable composition. Also, the protective layer(s) is typically applied after formation of the OEL.

[0107]

[0105] The OEL described herein may be applied directly onto a substrate (x20) and may be permanent (e.g. for banknote or label applications) or may be applied onto a temporary substrate for manufacturing purposes, with the OEL being removed at a later time.

[0108] Alternatively, one or more adhesive layers may be present on the OEL(s) or on the substrate (x20), said adhesive layer(s) being present on the substrate side opposite to the side on which the OEL(s) are provided and / or on the same side as the OEL(s). Thus, one or more adhesive layers may be applied to the OEL(s) or substrate, said adhesive layer(s) being applied after completion of the curing step. Such an object may be adapted to be attached to any kind of document or other article without machinery or a laborious process such as printing. Alternatively, the substrate described herein with one or more OEL(s) described herein may be in the form of a transfer foil that can be applied to a document or article in a separate transfer step. For this purpose, the substrate is provided with a release coating, on which the OEL(s) are produced. EXAMPLES

[0109]

[0107] The examples and comparative examples were carried out by using a UV / visible curable flexographic printing ink having the formulation set forth in Table 1 and the first and second magnetic assemblies described below. [Table 1]

[0110]

[0108] For each sample, Examples E1 to E3 and Comparative Examples C1 to C3 were prepared by the following method. a) As described above, the UV / visible curable ink described in Table 1 was applied to the substrate (x20) to form a coating layer (x10). b) In one or two areas (shown as A / A' in Figures 3A and 4), at least a portion of the platelet-shaped magnetic or magnetisable pigment particles was oriented by exposing the coating layer (x10) to the magnetic field of the magnetic field generator (x30) described above. c) Partially simultaneously with or after exposure to a magnetic field (see Table 2), the coating layer (x10) was cured to form an optical effect layer (OEL) (x40) comprising magnetically oriented plate-shaped magnetic or magnetisable pigment particles having an elevation angle γ as described in Table 2.

[0111]

[0109] Figures 3A and 4 show schematic diagrams of different examples in which a substrate (x20) having a coating layer (x10) comprising pigment particles is exposed to a magnetic field of a magnetic field generating device (x30) in one or more areas (shown as A, A'), the magnetic field being non-uniform (Figure 3A) or substantially uniform (see Figure 4), and the angle α between the two-dimensional surface of the substrate (x20) at the position of the particles and the tangent to the magnetic field lines of the magnetic field in the two areas A and A' in Figure 3A or in the one area A in Figure 4 is 12° to 75° (12°≦|α|≦75°) or approximately 105° to 168° (105°≦|α|≦168°). [Table 2]

[0112]

[0110] Figures 5A and 5B show the variation of the elevation angle γ of the pigment particles in the at least partially cured layer (x40), where the x-axis (mm) corresponds to the distance from the edge of the at least partially cured layer (x40), with the value of 15 mm corresponding to the center of the magnetic field generator shown in Figure 3A and the center of the at least partially cured layer (x40). As can be seen in the examples shown in Figures 5A and 5B, the corresponding angles γ from 0 mm to 2 mm and from 28 mm to 30 mm could not be measured by conoscopic scattering measurements.

[0113]

[0111] For the magnetic field generator shown in Figure 3A, the angle α between the two-dimensional surface of the substrate (x20) at the position of the particle and the tangent to the magnetic field lines of the magnetic field in one or more areas was calculated using the software Vizimag 3.19 and is listed in Table 3. [Table 3]

[0114] Step a)

[0112] The UV-visible curable inks listed in Table 1 were applied to PET (Folex's BG71 color laser printer & copier OHP film (100 micrometer thick, 45 mm x 30 mm)) (x20) to form coating layers (45 mm x 30 mm) (x10). The application steps were performed with a semi-automatic laboratory coater (K101 Control Coater (RK Print)) by using coating bar Nr 4 (nominal coating layer thickness 36 μm, measured coating layer thickness of the cured coating layer 24 μm) for C1 to C3 and coating bar Nr 2 (nominal coating layer thickness 12 μm, measured coating layer thickness of the cured coating layer 8 μm) for E1 to E3.

[0115]

[0113] The inks used in Examples E1 to E3 and Comparative Examples C1 to C3 have viscosities suitable for flexographic printing, so a coating method that imitates the flexographic process was used.

[0116] Step b) Magnetic field generator for orientation in a non-uniform magnetic field (Figure 3A)

[0114] The pigment particles were oriented using a magnetic field generator (330) shown in Figure 3A (not drawn to scale for clarity of the drawing). The magnetic field generator (330) was a rod-shaped dipole magnet (M1) made of NdFeB N42 and having dimensions of 30 mm (L1) x 30 mm (L2) x 6 mm (L3). The distance between the surface of the magnetic field generator (330) facing the substrate (320) and the coating layer (310) was 6 mm.

[0117] Magnetic field generator for alignment in a uniform magnetic field (Figure 4)

[0115] The pigment particles were oriented using a magnetic field generator (430) shown in Figure 4 (not drawn to scale for clarity of the drawing) The magnetic field generator (430) comprised two rod-shaped dipole magnets (M1, M2) and two pole pieces (P1, P2).

[0118]

[0116] Each of the two rod-shaped dipole magnets (M1, M2) was made of NdFeB N42 and had dimensions of 40 mm (L1) x 40 mm (L2) x 10 mm (L3).

[0119]

[0117] The two rod-shaped dipole magnets (M1, M2) were placed at a distance (d1) of about 40 mm from each other. The magnetic axis of each of the two rod-shaped dipole magnets (M1, M2) was substantially parallel to the length (L1) of the magnet, and the magnetic field directions of the two rod-shaped dipole magnets (M1, M2) were directed in the same direction.

[0120]

[0118] The two pole pieces (P1, P2) each had a dimension of 60 mm (L4) x 40 mm (L5) x 3 mm (L6). The two pole pieces (P1, P2) were made of iron (ARMCO (registered trademark)).

[0121]

[0119] The two rod-shaped dipole magnets (M1, M2) and the two pole pieces (P1, P2) are arranged to form a rectangular prism having a rectangular void in the center consisting of an area A in which the magnetic field is substantially uniform and the magnetic field lines are substantially parallel to each other, such that the distance (d2) between the two pole pieces (P1, P2) is approximately 40 mm (i.e., the length (L1) of the two rod-shaped dipole magnets (M1, M2)) and the distance between the two rod-shaped dipole magnets (M1, M2) is 40 mm.

[0122]

[0120] The substrate (420) and coating layer (410) were disposed in the center of the void of the magnetic field generating device (430) shown in Figure 4 so that the angle α between the two-dimensional surface of the substrate (420) at the position of the particles and the tangent to the magnetic field lines of the magnetic field in area A where the magnetic field is uniform was approximately 30°.

[0123] Step c)

[0121] Simultaneously with or after partial exposure to the magnetic field of the magnetic field generator (x30) (see Table 2), a UV-LED lamp (Type FireFlex (50 × 75 mm, 395 nm, 8 W / cm) from Phoseon was used. 2 The coating layer (x10) was cured by exposure to a 1000 .mu.m (x10) solution for about 0.5 seconds to form an optical effect layer (OEL) comprising magnetically oriented plate-shaped magnetic or magnetizable pigment particles having an elevation angle .gamma. as listed in Table 2.

[0124]

[0122] In the case of Example E2 and Comparative Example C2, the UV-LED lamp was disposed at a distance of 10 cm from the edge of the magnetic field generating device (330). That is, the substrate (320) was exposed to the UV-LED lamp away from the magnetic field generating device (330). The distance between the UV-LED lamp and the coating layer (320) was about 1 cm, and the exposure time was about 0.5 seconds.

[0125]

[0123] In the case of Example E3 and Comparative Example C3, after about 1 second, a curing unit (450) (UV-LED lamp (Phoseon's FireFly (395 nm, 4 W / cm)) as shown in FIG. 2 ))) the coating layer (610) was at least partially cured.

[0126] Measurement of elevation angle by conoscopic scatterometry. Conoscopic scattering measurements were performed using a conoscopic scatterometer as described in FIG. 4A of WO 2019 / 038371 (available from Eckhart Optics LLC, 5430 Jefferson Ct, White Bear Lake, MN 55110 (http: / / eckop.com)). The elevation angle γ was approximately 1 mm. 2 The cured coating thickness was measured over the surface area of ​​the coating layer, i.e., the reported values ​​are averaged over approximately 1000 pigment particles. The measured cured coating thicknesses reported in Table 2 were determined by measuring the weight difference of the substrate before and after coating and dividing this by the surface area of ​​the coating layer and the density of the coating composition.

[0127]

[0125] As shown in Figures 5A and 5B, the optical effect layers (OEL) constructed according to the samples E1 and E2 according to the invention exhibited a variation of the elevation angle γ of the pigment particles according to a curve reaching a plateau value (regions A and A'). In the optical effect layers (OEL) thus obtained, adjacent magnetically oriented plate-like magnetic or magnetizable pigment particles, respectively, have substantially parallel main axes X in a first region (corresponding to area A of the magnetic field) of the at least partially cured coating layer (x40), adjacent magnetically oriented plate-like magnetic or magnetizable pigment particles, respectively, have substantially parallel main axes X in a second region (corresponding to area A' of the magnetic field) of the at least partially cured coating layer (x40), and the magnetically oriented plate-like magnetic or magnetizable pigment particles have different elevation angles in said first and second regions.

[0128]

[0126] In contrast to the optical effect layers (OELs) constituted by samples E1 and E2 according to the present invention, the optical effect layers (OELs) constituted by comparative samples C1 and C2 showed a change in the elevation angle γ of the pigment particles according to a constant increasing line without a plateau absolute value.

[0129]

[0127] An optical effect layer (OEL) constructed according to sample E3 of the present invention exhibited a constant elevation angle γ over the entire surface of the OEL as a result of exposure of the coating layer (410) to the magnetic field of a magnetic field generator (x40) in one area (designated as A) where the magnetic field was substantially uniform. The elevation angle γ was much smaller than the angle α as a result of the layer thickness (8 micrometers being smaller than the d50 value of the pigment particles (20 micrometers) (i.e. part of the present invention)).

[0130]

[0128] The optical effect layer (OEL) constructed according to Comparative Sample C3 exhibited a constant elevation angle γ across the surface of the OEL as a result of exposure of the coating layer (410) to the magnetic field of a magnetic field generator (x40) in one area (designated as A) where the magnetic field was substantially uniform, although the elevation angle γ was similar to the angle α as a result of the layer thickness (24 micrometers being larger than the d50 value of the pigment particles (20 micrometers) (i.e., not part of the present invention)).

[0131]

[0129] For comparison purposes, Fig. 6 discloses an example according to co-pending European Patent Application No. 20194060.8, in which a coating layer (510) comprising pigment particles is exposed to a magnetic field of a magnetic field generating device (530) in an area (denoted as B). This magnetic field is substantially uniform, and the substrate (520) carrying the coating layer (510) is exposed to a magnetic field of a magnetic field generating device (530) in the area (denoted as B) in which the magnetic field is substantially uniform, with the angle α between the coating layer (510) and the tangent of the magnetic field lines of the magnetic field in the area B where the magnetic field is substantially uniform being greater than 0° and less than 30° (0°

Claims

1. A method for producing one or more optical effect layers (OEL) comprising magnetically oriented plate-like magnetic or magnetisable pigment particles on a substrate (x20) having a two-dimensional surface, comprising: a) applying a radiation curable coating composition in a first liquid state to the surface of said substrate (x20), said radiation curable coating composition comprising plate-shaped magnetic or magnetizable pigment particles having a major axis X and a d50 value, so as to form a coating layer (x10); b) One or more areas (A, A′, A ｉ In the step of (A), the coating layer (x10) is exposed to the magnetic field to orient at least a portion of the plate-shaped magnetic or magnetizable pigment particles, and the substrate (x20) having the coating layer (x10) is exposed to the magnetic field to orient the one or more areas (A, A', A ｉ and a detection unit for detecting the two-dimensional surface of the substrate (x20) at the position of the particle and the one or more areas (A, A', A ｉ an angle α between a tangent to a magnetic field line of the magnetic field in the magnetic field 1′) and the magnetic field line is equal to or greater than 12° and equal to or less than 75° (12°≦|α|≦75°) or equal to or greater than 105° and equal to or less than 168° (105°≦|α|≦168°); c) partially simultaneously with or after step b), at least partially curing the coating layer (x10) in a curing unit (x50) thereby fixing the position and orientation of the plate-shaped magnetic or magnetisable pigment particles in the coating layer (x10) to produce an at least partially cured coating layer (x40) having a thickness T, wherein the thickness T of the at least partially cured coating layer (x40) is smaller than the d50 value of the plate-shaped magnetic or magnetisable pigment particles, and wherein adjacent magnetically oriented plate-shaped magnetic or magnetisable pigment particles have main axes X that are substantially parallel to each other, at least in one or more regions (x40-a, x40-b) of the at least partially cured coating layer (x40); A method comprising:

2. 2. The method of claim 1, wherein the thickness T of the at least partially cured coating layer (x40) is less than d50*sin(α) (T<d50*(sinα)).

3. 3. The method according to claim 1 or 2, wherein the step a) of applying the radiation curable coating composition to the surface of the substrate (x20) is carried out by a printing process selected from the group consisting of screen printing, gravure printing, and flexographic printing.

4. 3. The method according to claim 1 or 2, wherein at least a portion of the platelet-shaped magnetic or magnetisable pigment particles are constituted by platelet-shaped optically variable magnetic or magnetisable pigment particles.

5. 5. The method of claim 4, wherein the plate-shaped optically variable magnetic or magnetisable pigment particles are selected from the group consisting of plate-shaped magnetic thin film interference pigments, plate-shaped magnetic cholesteric liquid crystal pigments, interference coated magnetic pigment particles, and mixtures thereof.

6. 5. The method according to claim 4, wherein at least a portion of said platelet-shaped magnetic or magnetisable particles are constituted by platelet-shaped magnetic or magnetisable pigment particles exhibiting a metallic colour.

7. The method of claim 6, wherein the metallic color is silver or gold.

8. The magnetic field generating device (x30) is a rod-shaped dipole magnet with a magnetic axis substantially parallel to the two-dimensional surface of the substrate (x20), and the step b) comprises: ｉ 3. The method according to claim 1 or 2, comprising exposing said coating layer (x10) to said magnetic field in step (a) of the one or more areas of interest, said magnetic field not having a substantially constant magnitude and direction across said one or more areas of interest or not being substantially confined to a plane, said magnetically oriented plate-like magnetic or magnetisable pigment particles being at different angles α.

9. The step b) is for detecting the one or more areas (A, A′, A ｉ 3. The method according to claim 1 or 2, comprising exposing said coating layer (x10) to said magnetic field in step (a) of step (b) '), said magnetic field having a substantially constant magnitude and direction over said one or more areas of interest or being substantially confined to a plane, said magnetically oriented plate-like magnetic or magnetisable pigment particles being at substantially the same angle α.

10. 3. The method according to claim 1 or 2, wherein step b) comprises exposing the coating layer (x10) to a magnetic field having a substantially constant magnitude and direction throughout the one or more areas of interest or confined to a substantially plane, and wherein the magnetic field generating device (x30) comprises two spaced apart rod-shaped dipole magnets (M1, M2) having the same magnetic field direction and the same length, and two spaced apart magnetic pole pieces (P1, P2) having the same length and arranged as a rectangular assembly, wherein M1 faces M2 but not adjacent to it, P1 faces P2 but not adjacent to it, and P1 is arranged at a distance from P2 corresponding to the length of M1 / M2.

11. The magnetic field lines are in the one or more areas (A, A′, A ｉ 11. The method of claim 10, wherein in each of the first and second electrodes 11a, 11b, 11c, 11d, 11e, 11f, 11g, 11h, 11i and 11j are substantially parallel to each other.

12. The one or more optical effect layers (OEL) are independently composed of a single at least partially cured coating layer (x40), the single at least partially cured coating layer (x40) comprising magnetically oriented plate-shaped magnetic or magnetisable pigment particles, the single at least partially cured coating layer (x40) comprising one or more first regions (x40-a) and one or more second regions (x40-b), the method comprising: a) applying the radiation curable coating composition comprising the platelet-shaped magnetic or magnetisable pigment particles to a surface of the substrate (x20) to produce a single coating layer (x10) comprising one or more first regions (x10-a) and one or more second regions (x10-b); b) the substrate (x20) having the single coating layer (x10) is coated with the one or more areas (A, A′, A ｉ exposing the single coating layer (x10) to the magnetic field of the magnetic field generating device (x30) with the angle α being between 12° and 75° (12°≦|α|≦75°) or between 105° and 168° (105°≦|α|≦168°); c) partially simultaneously with or after step b), fixing at least a portion of the plate-shaped magnetic or magnetizable particles in their adopted positions and orientations by at least partially selectively curing the one or more first regions (x10a) of the single coating layer (x10) in the curing unit (x50); d) exposing said single coating layer (x10) to a magnetic field of a second magnetic field, thereby orienting at least a portion of said platelet-shaped magnetic or magnetizable pigment particles in said one or more second regions (x10b), wherein said substrate (x20) is aligned in said one or more areas (A, A′, A′). ｉ and a magnetic field is formed on said two-dimensional surface of said substrate (x20) at the location of said plate-shaped magnetic or magnetizable pigment particles and said one or more areas (A, A', A'). ｉ an angle α' between the tangent of the magnetic field line of the second magnetic field in step b) and the magnetic field line of the second magnetic field in step c) is 12° or more and 75° or less (12°≦|α'|≦75°) or 105° or more and 168° or less (105°≦|α'|≦168°), the second magnetic field generator (x30-b) is either the same as or different from the magnetic field generator in step b), and α' is different from α; e) partially simultaneously with or after step d), at least partially curing said single coating layer (x10) in said curing unit (x50) to produce said single at least partially cured coating layer (x40), in which adjacent magnetically oriented plate-shaped magnetic or magnetizable pigment particles at least each in said one or more first regions (x40-a) of said single at least partially cured coating layer (x40) have main axes X that are substantially parallel to each other, and adjacent magnetically oriented plate-shaped magnetic or magnetizable pigment particles at least each in said one or more second regions (x40-b) of said single at least partially cured coating layer (x40) have main axes X that are substantially parallel to each other, The method of claim 1 or 2, comprising:

13. The method of claim 12, wherein α' and α differ by at least 30°.

14. said one or more optical effect layers (OEL) comprising magnetically oriented plate-like magnetic or magnetisable pigment particles in said at least partially cured coating layer (x40) and magnetically oriented second plate-like magnetic or magnetisable pigment particles in an at least partially cured second coating layer (x41), said at least partially cured second coating layer (x41) at least partially or completely overlapping said at least partially cured coating layer (x40), adjacent to said at least partially cured coating layer (x40), or spaced apart from said at least partially cured coating layer (x40), said method comprising: d) after step c), applying a second radiation curable coating composition in a first liquid state comprising the second plate-like magnetic or magnetisable pigment particles to form the second coating layer (x11), the second radiation curable coating composition being either the same as or different from the radiation curable coating composition of step a); e) One or more areas (A, A′, A) of the second magnetic field of the second magnetic field generating device (x30-b) ｉ In the step of (A), the second coating layer (x11) is exposed to the second magnetic field to orient at least a portion of the second plate-shaped magnetic or magnetizable pigment particles, and the substrate (x20) having the second coating layer (x11) is aligned in the one or more areas (A, A', A'). ｉ and a second platelet-shaped magnetic or magnetizable pigment particle is provided on the substrate (x20) and the two-dimensional surface of the substrate (x20) at the location of the second platelet-shaped magnetic or magnetizable pigment particle and the one or more areas (A, A', A ｉ an angle α' between the tangent of the magnetic field line of the second magnetic field in step b) and the magnetic field line of the second magnetic field in step c) is 12° or more and 75° or less (12°≦|α'|≦75°) or 105° or more and 168° or less (105°≦|α'|≦168°), the second magnetic field generator (x30-b) is either the same as or different from the magnetic field generator in step b), and α' is different from α; f) partially simultaneously with or after step e) of exposing the second coating layer (x11) to the second magnetic field, at least partially curing the second coating layer (x11) in a curing unit (x50) to at least partially fix the position and orientation of the second plate-like magnetic or magnetizable pigment particles in the second coating layer (x11) to produce the at least partially cured second coating layer (x41), wherein adjacent magnetically oriented plate-like magnetic or magnetizable pigment particles are at least at least each of adjacent magnetically oriented plate-like magnetic or magnetizable pigment particles in the at least partially cured coating layer (x40) have a main axis X substantially parallel to each other, and in said second coating layer (x41) at least each of adjacent magnetically oriented plate-like magnetic or magnetizable pigment particles have a main axis X substantially parallel to each other, and said magnetically oriented plate-like magnetic or magnetizable pigment particles in said at least partially cured coating layer (x40) have a different elevation angle than said magnetically oriented plate-like magnetic or magnetizable pigment particles in said at least partially cured second coating layer (x41); The method of claim 1 or 2, comprising:

15. The method of claim 14, wherein α' and α differ by at least 30°.

16. 3. The method of claim 1 or 2, further comprising the steps of applying a composition in the form of one or more indicia and at least partially curing or solidifying said composition, said one or more indicia being between said substrate (x20) and said at least partially cured coating layer (x40), said steps being performed prior to step a) of applying said radiation curable coating composition to a surface of said substrate (x20).

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