WO2025242569A1

WO2025242569A1 - Apparatuses and processes for producing optical effects layers

Info

Publication number: WO2025242569A1
Application number: PCT/EP2025/063558
Authority: WO
Inventors: Neda Nikseresht Ghanepour; Thibault ZURLINDEN; Andrea Callegari
Original assignee: SICPA Holding SA
Current assignee: SICPA Holding SA
Priority date: 2024-05-22
Filing date: 2025-05-16
Publication date: 2025-11-27
Anticipated expiration: 2026-11-22

Abstract

The invention relates to the field of the protection of security documents such as for example banknotes and identity documents against counterfeit and illegal reproduction In particular, the present invention provides apparatuses and processes for producing optical effect layers (OELs) comprising magnetically oriented, said optical effect layers (OELs) exhibiting not only a dynamic movement but also an eye- catching relief and/or 3D effect upon tilting and may be used as anti-counterfeit means on security documents or security articles or for decorative purposes.

Description

APPARATUSES AND PROCESSES FOR PRODUCING OPTICAL EFFECTS LAYERS

FIELD OF THE INVENTION

[001] The present invention relates to the field of apparatuses and processes for producing optical effect layers (OELs) and the use of said OELs as anti-counterfeit means on security documents or security articles as well as decorative purposes.

BACKGROUND OF THE INVENTION

[002] It is known in the art to use inks, compositions, coatings or layers containing oriented magnetic or magnetizable pigment particles, particularly also optically variable magnetic or magnetizable pigment particles, for the production of security elements, e g. in the field of security documents. Coatings or layers comprising oriented magnetic or magnetizable pigment particles are disclosed for example in US 2,570,856; US 3,676,273; US 3,791 ,864; US 5,630,877; and US 5,364,689. Coatings or layers comprising oriented magnetic color-shifting pigment particles, resulting in particularly appealing optical effects, useful for the protection of security documents, have been disclosed in WO 2002/090002 A2 and WO 2005/002866 A1 .

[003] Security features, e.g. for 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 features are difficult to detect, typically requiring specialized equipment and knowledge for detection, whereas “overt” security features rely on the concept of being easily detectable with the unaided human senses, e.g. such features may be visible and/or detectable via the tactile sense while still being difficult to produce and/or to copy. However, the effectiveness of overt security features depends to a great extent on their easy recognition as a security feature.

[004] Magnetic or magnetizable pigment particles in printing inks or coatings allow for the production of magnetically induced images, designs and/or patterns through the application of a correspondingly structured magnetic field, inducing a local orientation of the magnetic or magnetizable pigment particles in the not yet hardened (i.e. wet) coating, followed by the hardening of the coating. The result is a fixed and stable magnetically induced image, design or pattern (also known in the art as optical effect layer (OEL)). Materials and technologies for the orientation of magnetic or magnetizable pigment particles in coating compositions have been disclosed for example in US 2,418,479; US 2,570,856; US 3,791 ,864; DE 2006848-A; US 3,676,273; US 5,364,689; US 6,103,361 ; EP 0 406 667 B1 ; US 2002/0160194; US 2004/0009309; EP 0 710 508 A1 ; WO 2002/09002 A2; WO 2003/000801 A2; WO 2005/002866 A1 ; and WO 2006/061301 A1. In such a way, magnetically induced patterns which are highly resistant to counterfeit can be produced. The security element in question can only be produced by having access to both, the magnetic or magnetizable pigment particles or the corresponding ink, and the particular technology employed to print said ink and to orient said pigment in the printed ink.

[005] Methods and devices have been developed to produce dynamic magnetically induced images on substrates, said images exhibiting a dynamic appearance upon tilting said substrates. Typical examples of said images include for example one or more moving bright reflective bars, or one or more moving loop-shaped bodies and one or more varying shape loop-shaped bodies such as described in US 2005/0106367 A1 ; WO 2020/193009 A1 ; WO 2020/160993 A1 ; WO 2013/167425 A1 ; WO 2021/083809 A1 ; WO 2021/083808 A1 ; WO 2014/108404 A2; WO 2014/108303 A2; WO 2018/054819 A1 ; WO 2019/215148 A1 ; WO 2020/025218 A1 ; WO W02020/025482 A1 ; WO 2017/064052 A1 ; WO 2017/080698A1 ; WO 2017/148789 A1 ; and WO 2020/193009 A1 ,

[006] The methods and devices described hereabove use magnetic assemblies to mono-axially orient magnetic pigment particles. Mono-axial orientation of magnetic pigment particles result in neighboring particles having their main (second longest) axis parallel to each other and to the magnetic field, while their minor axis in the plane of the pigment particles is not, or much less constrained by the applied magnetic field. Accordingly, a sole mono-axial orientation of magnetic pigment particles results in optical effect layers that may suffer from a low reflectivity and brightness as light is reflected in a wide range of directions, especially in directions that are substantially perpendicular to the magnetic field lines.

[007] WO 2015/086257 A1 discloses an improved method for producing an optical effect layer (OEL) on a substrate, said process comprising two magnetic orientation steps, said steps consisting of i) exposing a coating composition comprising platelet-shaped magnetic or magnetisable pigment particles to a dynamic, i.e. direction changing, magnetic field of a first magnetic-field-generating device so as to bi-axially orient at least a part of the platelet-shaped magnetic or magnetisable pigment particles and ii) exposing the coating composition to a static magnetic field of a second magnetic-field-generating device, thereby mono-axially re-orienting at least a part of the platelet-shaped magnetic or magnetisable pigment particles according to a design transferred by said second magnetic-field-generating device.

[008] Methods and devices have been developed to produce magnetically induced images on substrates exhibiting static indicia. EP 1 641 624 B1 ; EP 1 937 415 B1 ; and EP 2 155 498 B1 disclose devices and method for magnetically transferring indicia into a not yet hardened (i.e. wet) coating composition comprising magnetic or magnetizable pigment particles so as to form optical effect layers (OELs). The disclosed methods advantageously allow the production of security documents and articles having a customer-specific magnetic design.

[009] Improved methods have been developed to produce optical effect layers (OELs) exhibiting eyecatching indicia having a 3D appearance and are disclosed in WO 2018/019594 A1 and WO 2018/033512 A1 and in the co-pending application EP23166324.6.

[010] However, the methods of the prior art fail to provide eye-catching magnetically induced images combining a dynamic appearance and indicia in easy way to be implemented and to work at a high production speed. Furthermore, magnetically induced images simultaneously exhibiting more than one optical effects according to the prior art require not only at least two sequential magnetic orientation steps but also the use of special curing apparatus such as photomask, laser or addressable LED and as disclosed in EP 3 170 566 B1 ; EP 3 459 758 A1 ; EP 2 542 421 B1 ; and WO 2020/148076 A1 .

[OH] Therefore, a need remains for improved apparatuses and processes for producing eye-catching optical effect layers (OELs), wherein said processes should be reliable, easy to implement and able to work at a high production speed while allowing the production of OELs not only an eye-catching relief and/or 3D indicia effect but also a dynamic movement. SUMMARY OF THE INVENTION

[012] Accordingly, it is an object of the present invention to overcome the deficiencies of the prior art as discussed above. This is achieved by the provision of an apparatus (xOO) [to be finalized before filing] [013] Also described herein are devices comprising the apparatus (xOO) described herein and a magnetic assembly (x60), wherein the soft magnetic plate (x10) is placed above the magnetic-field- generating device (x40), and wherein the magnetic-field-generating device (x40) and the soft magnetic plate (x30) are arranged on or in a cylinder so that, when the cylinder is rotated, the apparatus (xOO) and the magnetic assembly (x60) are moved relative to each other so that the surface of the apparatus (xOO) faces the magnetic assembly (x60) allowing at least a part of the particles to be bi-axially oriented. [014] Also described herein are uses of the apparatuses (xOO) for magnetically orienting plateletshaped magnetic or magnetizable pigment particles in a coating layer (x20) and producing the optical effect layer (OEL) described herein on the substrate (x10) described herein.

[015] Also described herein are processes for producing the optical effect layers (OELs) described herein, said processes comprising the steps of: a) applying onto a substrate (x10) surface a coating composition comprising i) platelet-shaped magnetic or magnetizable pigment particles and II) a binder material so as to form a coating layer (x20) on said substrate (x10), said coating composition being in a first state, b) forming an assembly (x100) comprising the substrate (x10) carrying the coating layer (x20) and the apparatus (xOO) described herein, c) moving the assembly (x100) comprising the substrate (x10) carrying the coating layer (x20) and the apparatus (xOO) recited in any one of claims 1 to 7 obtained under step b) through an inhomogeneous magnetic field of a static magnetic assembly (x60) so as to bi-axially orient at least a part of the plateletshaped magnetic or magnetizable pigment particles, and d) hardening the coating composition to a second state so as to fix the platelet-shaped magnetic or magnetizable pigment particles in their adopted positions and orientations, wherein the optical effect layer (OEL) is made of a single cured coating layer (x20) comprising at least a first area exhibiting a 3D effect in the form of one or more indicia and at least a second area exhibiting a dynamic movement upon tilting the substrate (x10), said at least one of said first area and at least one of said second area being adjacent to each other.

[016] Also described herein are optical effect layers (OELs) produced by the process described herein and security documents as well as decorative elements and objects comprising one or more optical OELs described herein.

[017] Also described herein are methods of manufacturing a security document or a decorative element or object, comprising a) providing a security document or a decorative element or object, and b) providing an optical effect layer such as those described herein, in particular such as those obtained by the process described herein, so that it is comprised by the security document or decorative element or object.

[018] The present invention provides apparatuses advantageously allowing the manufacture of eyecatching optical effect layers (OELs), said OELs comprising at least a first area exhibiting a 3D effect in in the form of the one or more indicia and at least a second area exhibiting a dynamic movement upon tilting, wherein at least one of said first area and at least one of said second area are adjacent as described herein.

[019] The present invention also provides a reliable and easy to implement process to magnetically orient platelet-shaped magnetic or magnetizable pigment in a coating layer made of a coating composition in a first state, i.e. not yet hardened (i.e. wet) state, wherein the platelet-shaped magnetic or magnetizable pigment particles are free to move and rotate within the layer so as to form an optical effect layer (OEL) combining a dynamic movement with an eye-catching relief and/or 3D effect after having hardened said coating layer to a second state wherein orientation and position of the plateletshaped magnetic or magnetizable pigment particles are fixed/frozen.

[020] The magnetic orientation of the platelet-shaped magnetic or magnetizable pigment particles is carried out by forming the assembly (x100) comprising the substrate (x10) carrying the coating layer (x20), the apparatus (xOO) comprising the soft magnetic plate (x30) carrying the one or more indicia in the form of one or more indentations (x31) and/or one or more voids (x32) and the magnetic-field- generating device (x40) comprising the at least one dipole magnet described herein and moving said assembly through the inhomogeneous magnetic field of a static magnetic assembly (x60). The process described herein advantageously allow the production of optical effect layers comprising at least a first area exhibiting a 3D effect in the form of one or more indicia and at least a second area exhibiting a dynamic movement upon tilting, wherein at least one of said first area and at least one of said second area are adjacent as described herein, using a single composition comprising platelet-shaped magnetic or magnetizable pigment particles, in a single magnetic orientation step without requiring a selective hardening step. Accordingly, the process provided by the present invention is mechanically robust, easy to implement with an industrial high-speed printing equipment, without resorting to cumbersome, tedious and expensive modifications of said equipment.

[021] The magnetic orientation of the platelet-shaped magnetic or magnetizable pigment particles is carried out by exposing the radiation curable coating composition comprising said pigments to a magnetic field of the apparatus (xOO) described herein so as to orient at least a part of the plateletshaped magnetic or magnetizable pigment particles. The process described herein advantageously allow the production of OELs comprising at least a first area exhibiting a 3D effect in the form the one or more indicia and at least a second area exhibiting a dynamic movement upon tilting, wherein at least one of said first area and at least one of said second area are adjacent as described herein, using a single composition comprising platelet-shaped magnetic or magnetizable pigment particles, in a single magnetic orientation step without requiring a selective hardening step. Accordingly, the process provided by the present invention is mechanically robust, easy to implement with an industrial highspeed printing equipment, without resorting to cumbersome, tedious and expensive modifications of said equipment.

BRIEF DESCRIPTION OF DRAWINGS

[022] Figs 1-8 provided therein schematically illustrates the present invention and are not true to scale. The optical effect layers (OEL) described herein and their production are now described in more detail with reference to the drawings and to particular embodiments, wherein Fig. 1 A schematically illustrates an example of an assembly (1100) for producing an optical effect layer (OEL) on a substrate (110) according to the present invention, wherein the assembly (1100) concomitantly moves (see the arrow) through an inhomogeneous magnetic field of a static magnetic assembly (160), said assembly (1100) comprising a) the substrate (110), b) a coating layer (120) comprising platelet-shaped magnetic or magnetizable pigment particles and c) an apparatus (100) according to the present invention and comprising a magnetic-field-generating device (140), a soft magnetic plate (130) carrying indicia in the form of indentations/voids (131 , 132) and a non-magnetic holder case (150). The so-obtained magnetic orientation of the platelet-shaped magnetic or magnetizable pigment particles is fixed/frozen by at least partially curing with a curing unit (170).

Fig. 1B schematically illustrate a cross-section of Fig. 1A, wherein the assembly (1100) moves (see the arrow) in the vicinity of the magnetic assembly (160). As shown in Fig. 1 B, the magnetic-field-generating device (140) is placed at a distance d-a from the soft magnetic plate (130) by means of the non-magnetic holder case (150).

Fig. 1C-1 (top view) and Fig. 1C-2 (cross-section) schematically illustrate a non-magnetic holder case comprising a recess for receiving the soft magnetic plate (x30) and an area for receiving the magnetic assembly (x40).

Figs 2A-B shows devices in which the apparatus (200) forms the assembly with the substrate (210) carrying the coating layer (220) while being mounted in or on a cylinder. The cylinder can be rotated so that it moves together with the substrate (210) on which the coating layer (220) is arranged. The cylinder comprises cavities, in which the apparatus (200) is inserted.

Fig. 3A schematically illustrates examples of apparatus for producing an optical effect layer (OEL) on a substrate (310) according to the present invention, wherein the apparatus comprises a soft magnetic plate (330) comprising one or more indicia in the form one or more indentations and/or one or more voids (not shown) and a magnetic-field-generating device (340), and optionally a non-magnetic holder case (350). The apparatus (300) is configured to receive a substrate (310) carrying a coating layer (320) comprising magnetic of magnetizable pigment particles.

Figs 4A to 4C schematically illustrate top views of suitable soft magnetic plates (430) comprising indentations (431) (see Fig. 4A), voids (432) (see Fig. 4B) and indentations (431) and voids (432) (see Fig. 4C).

Figs 5A-1 and 5A-2 (comparative) schematically illustrate cross-sections of soft magnetic plates (530) comprising an indentation (531) in Fig. 5A-1 or a void (532) in Fig. 5A-2, said indentations/voids having a having a U-shaped cross-section.

Figs 5B-1 and 5B-2 (invention) schematically illustrate cross-sections of soft magnetic plates (530) comprising an indentation (531) in Fig. 5B-1 or a void (532) in Fig. 5B-2, said indentations/voids having a V-shaped cross-section.

Figs 5C-1 and 5C-2 (invention) schematically illustrate cross-sections of soft magnetic plates (530) comprising an indentation (531) in Fig. 5C-1 or a void (532) in Fig. 5C-2, said indentations/voids having a stepped-shaped cross-section and four steps.

Figs 6A-1 to 6A-12 schematically illustrate top views of suitable soft magnetic plates (630) placed on top of a non-magnetic holder case (650) of apparatuses (not shown) according to the present invention, wherein said soft magnetic plates (630) comprise one or more indentations (631) and/or one or more voids (632), wherein said plates (630) have various shapes, various sizes and various locations.

Fig 7 illustrates a magnetic assembly (760) used in the Examples provided therein.

Figs 8 illustrate a suitable apparatus (800) used in the Examples provided therein, said apparatus (800) comprising a soft magnetic plate (830) carrying one or more indicia and a non-magnetic holder case (850) (Fig. 8A) and magnetic-field-generating device (840) (Figs 8B).

[023] The distances provided in the Figures are only illustrative and not true to scale.

DETAILED DESCRIPTION

Definitions

[024] The following definitions are to be used to interpret the meaning of the terms discussed in the description and recited in the claims.

[025] As used herein, the indefinite article "a" indicates one as well as more than one and does not necessarily limit its referent noun to the singular.

[026] As used herein, the term “at least one” is meant to define one or more than one, for example one or two or three.

[027] As used herein, the term “at least n”, wherein n is a integer, is meant to define n or more than n, for example n+1 or n+2 (i.e. in case of “at least one”, it is meant one, two .three, etc.; in case of “at least two”, it is meant two, three, four, etc.)

[028] As used herein, the term “about” means that the amount or value in question may be the specific value designated or some other value in its neighborhood. Generally, the term “about” denoting a certain value is intended to denote a range within ± 5% of the value. As one example, the phrase “about 100” denotes a range of 100 ± 5, i.e. the range from 95 to 105. Generally, when the term “about” is used, it can be expected that similar results or effects according to the invention can be obtained within a range of ±5% of the indicated value.

[029] As used herein, the term “and/or” means that either all or only one of the elements of said group may be present. For example, “A and/or B” shall mean “only A, or only B, or both A and B”. In the case of “only A”, the term also covers the possibility that B is absent, i.e. “only A, but not B”.

[030] The term “comprising” as used herein is intended to be non-exclusive and open-ended. Thus, for instance a coating composition comprising a compound A may include other compounds besides A. However, the term “comprising” also covers, as a particular embodiment thereof, the more restrictive meanings of “consisting essentially of and “consisting of, so that for instance “a fountain solution comprising A, B and optionally C” may also (essentially) consist of A and B, or (essentially) consist of A, B and C.

[031] The term “optical effect layer (OEL)” as used herein denotes a coating or layer that comprises oriented platelet-shaped magnetic or magnetizable pigment particles and a binder, wherein said plateletshaped magnetic or magnetizable pigment particles are oriented by a magnetic field and wherein the oriented platelet-shaped magnetic or magnetizable pigment particles are fixed/frozen in their orientation and position (i.e. after hardening/curing) so as to form a magnetically induced image. [032] The term "coating composition" refers to any composition which is capable of forming an optical effect layer (EOL) on a solid substrate and which can be applied preferably but not exclusively by a printing method. The coating composition comprises the platelet-shaped magnetic or magnetizable pigment particles described herein and the binder described herein.

[033] As used herein, the term “wet” refers to a coating layer which is not yet cured, for example a coating in which the platelet-shaped magnetic or magnetizable pigment particles are still able to change their positions and orientations under the influence of external forces acting upon them.

[034] As used herein, the term “indicia” shall mean discontinuous layers such as patterns, including without limitation symbols, alphanumeric symbols, motifs, letters, words, numbers, logos and drawings. [035] The term “hardening” is used to denote a process wherein the viscosity of a coating composition in a first physical state which is not yet hardened (i.e. wet) is increased so as to convert it into a second physical state, i.e. a hardened or solid state, where the platelet-shaped magnetic or magnetizable pigment particles are fixed/frozen in their current positions and orientations and can no longer move nor rotate.

[036] The term "security document" refers to a document which is usually protected against counterfeit or fraud by at least one security feature. Examples of security documents include without limitation value documents and value commercial goods.

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

[038] Where the present description refers to “preferred" embodiments/features, combinations of these “preferred” embodiments/features shall also be deemed as disclosed as long as this combination of “preferred” embodiments/features is technically meaningful.

[039] The terms “above”, “below”, “top” and “bottom” define the relative position of the different elements and do not limit and define their absolute position.

[040] The present invention provides apparatuses (xOO) and processes for making optical effect layers (OELs) being suitable as security features against counterfeit or fraud and comprising magnetically oriented platelet-shaped magnetic or magnetizable pigment particles on substrates (x10), wherein said optical effect layers (OELs) exhibit a 3D effect in the form one or more indicia and a dynamic movement upon tilting and provides processes for producing said OELs through the magnetic orientation of said pigment particles. The optical effect layers (OELs) described herein consists of at least a motif comprising at least a first area exhibiting a 3D effect in the form of the one or more indicia and at least a second area exhibiting a dynamic movement upon tilting, wherein at least one of said first area and at least one of said second area are adjacent. By “adjacent”, it means that the first and second areas are contiguous (i.e. they share at least one region together and have a common border). The first and second areas of the motif are adjacent, preferably juxtaposed or interlaced. The first and second areas may be continuous or discontinuous.

[041] The apparatuses (xOO) and processes described herein allow the preparation of the optical effect layers (OELs) described herein, wherein said OELs comprise a motif made of at least two areas made of a single applied and cured layer and comprising magnetically oriented platelet-shaped magnetic or magnetizable particles [042] The process according to the present invention comprises the steps of: a) applying on the substrate surface (x10) the coating composition comprising i) the platelet-shaped magnetic or magnetizable pigment particles described herein and ii) the binder material described herein so as to form the coating layer (x20) on said substrate, said coating composition being in a first state, b) forming an assembly (x100) comprising the substrate (x10) carrying the coating layer (x20) and the apparatus (xOO) described herein, c) moving the assembly (x100) comprising the substrate (x10) carrying the coating layer (x20) and the apparatus (xOO) described herein obtained under step b) through an inhomogeneous magnetic field of a static magnetic assembly (x60) so as to bi-axially orient at least a part of the platelet-shaped magnetic or magnetizable pigment particles, and d) hardening the coating composition to a second state so as to fix the platelet-shaped magnetic or magnetizable pigment particles in their adopted positions and orientations,

[043] When used during the process for producing the optical effect layer (OEL) described herein, the apparatus (xOO) described herein can be placed in any orientation. As shown in Figs 1A and 3A, the substrate (x10) carrying the coating layer (x20) is preferably arranged above the apparatus (xOO) in or or along a vertical axis and the soft magnetic plate (x30) is disposed between the magnetic field generating device (x40), in particular between the at least one dipole magnet (x40-a), and the substrate (x10) in or along a vertical axis. By specifying that “the substrate (x10) carrying the coating layer (x20) is arranged above the apparatus (xOO)”, it is encompassed that the soft magnetic plate (x30) is arranged vertically above the magnetic-field-generating device (x40) i.e. the direction of their arrangement relative to each other being in essence vertical.

[044] The process described herein comprises a step a) of applying onto the substrate (x10) surface described herein the coating composition comprising platelet-shaped magnetic or magnetizable pigment particles described herein so as to form a coating layer (x20), said coating composition being in a first physical state which allows its application as a layer and which is in a not yet hardened (i.e. wet) state wherein the platelet-shaped magnetic or magnetizable pigment particles can move and rotate within the binder material. Since the coating composition described herein is to be provided on the substrate (x10), it is necessary that the coating composition comprising at least the binder material described herein and the platelet-shaped magnetic or magnetizable pigment particles is in a form that allows its processing on the desired printing or coating equipment. Preferably, said step a) is carried out by a printing process, preferably selected from the group consisting of screen printing, rotogravure printing, flexography printing, pad printing and intaglio printing (also referred in the art as engraved copper plate printing and engraved steel die printing), more preferably selected from the group consisting of screen printing, rotogravure printing and flexography printing.

[045] The coating composition described herein as well as the coating layer (x20) described herein comprise platelet-shaped magnetic or magnetizable pigment particles. Preferably, the platelet-shaped magnetic or magnetizable pigment particles described herein are present in an amount from about 5 wt-% to about 40 wt-%, more preferably about 10 wt-% to about 30 wt-%, the weight percentages being based on the total weight of the coating composition.

[046] In contrast to needle-shaped pigment particles which can be considered as quasi onedimensional particles, platelet-shaped pigment particles are quasi two-dimensional particles due to the large aspect ratio of their dimensions. Platelet-shaped pigment particle can be considered as a two- dimensional structure wherein the dimensions X and Y are substantially larger than the dimension Z. Platelet-shaped pigment particles are also referred in the art as oblate particles or flakes. Such pigment particles may be described with a main axis X corresponding to their longest dimension crossing the pigment particle and a second axis Y perpendicular to X and corresponding to the second longest dimension crossing the pigment particle. In other words, the XY plane roughly defines the plane formed by the first and second longest dimensions of the pigment particle, the Z dimension being ignored.

[047] The platelet-shaped magnetic or magnetizable pigment particles described herein have, due to their platelet-shaped shape, non-isotropic reflectivity with respect to incident electromagnetic radiation for which the hardened/cured binder material is at least partially transparent. As used herein, the term “non-isotropic reflectivity” denotes that the proportion of incident radiation from a first angle that is reflected by a particle into a certain (viewing) direction (a second angle) is a function of the orientation of the particles, i.e. that a change of the orientation of the particle with respect to the first angle can lead to a different magnitude of the reflection to the viewing direction.

[048] In the OELs described herein, the platelet-shaped magnetic or magnetizable pigment particles described herein are dispersed in the coating composition comprising a hardened binder material that fixes the orientation of the platelet-shaped magnetic or magnetizable pigment particles. The binder material is at least in its hardened or solid state (also referred to as second state herein), at least partially transparent to electromagnetic radiation of a range of wavelengths comprised between 200 nm and 2500 nm, i.e. within the wavelength range which is typically referred to as the “optical spectrum” and which comprises infrared, visible and UV portions of the electromagnetic spectrum. Accordingly, the particles contained in the binder material in its hardened or solid state and their orientation-dependent reflectivity can be perceived through the binder material at some wavelengths within this range. Preferably, the hardened binder material is at least partially transparent to electromagnetic radiation of a range of wavelengths comprised between 200 nm and 800 nm, more preferably comprised between 400 nm and 700 nm. Herein, the term “transparent” denotes that the transmission of electromagnetic radiation through a layer of 20 pm of the hardened binder material as present in the OEL (not including the platelet-shaped magnetic or magnetizable pigment particles, but all other optional components of the OEL in case such components are present) is at least 50%, more preferably at least 60 %, even more preferably at least 70%, at the wavelength(s) concerned. This can be determined for example by measuring the transmittance of a test piece of the hardened binder material (not including the plateletshaped magnetic or magnetizable pigment particles) in accordance with well-established test methods, e.g. DIN 5036-3 (1979-11). If the OEL serves as a covert security feature, then typically technical means will be necessary to detect the (complete) optical effect generated by the OEL under respective illuminating conditions comprising the selected non-visible wavelength; said detection requiring that the wavelength of incident radiation is selected outside the visible range, e.g. in the near UV-range. In this case, it is preferable that the OEL comprises luminescent pigment particles that show luminescence in response to the selected wavelength outside the visible spectrum contained in the incident radiation. The infrared, visible and UV portions of the electromagnetic spectrum approximately correspond to the wavelength ranges between 700-2500 nm, 400-700 nm, and 200-400 nm respectively. [049] Suitable examples of platelet-shaped magnetic or magnetizable pigment particles described herein include without limitation 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” in reference to the metals, alloys and oxides is directed to ferromagnetic or ferrimagnetic metals, alloys and oxides. 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 without limitation iron oxides such as hematite (Fe2<D3), magnetite (Fe3<D4), chromium dioxide (CrO2), magnetic ferrites (MFe2<34), magnetic spinels (MR2O4), magnetic hexaferrites (MFe^O ), magnetic orthoferrites (RFeCh), magnetic garnets MsR2(AO4)3, wherein M stands for two-valent metal, R stands for three-valent metal, and A stands for four-valent metal.

[050] Examples of platelet-shaped magnetic or magnetizable pigment particles described herein include without limitation pigment particles comprising a magnetic layer M made from one or more of a magnetic metal such as cobalt (Co), iron (Fe), or nickel (Ni); and a magnetic alloy of iron, cobalt or nickel, wherein said magnetic or magnetizable pigment particles may be multilayered structures comprising one or more additional layers. Preferably, the one or more additional layers are layers A independently made from one or more selected from the group consisting of metal fluorides such as magnesium fluoride (MgF2), silicon oxide (SiO), silicon dioxide (SiO2), titanium oxide (TiO2), and aluminum oxide (AI2O3), more preferably silicon dioxide (SiC ); or layers B independently made from one or more selected from the group consisting of metals and metal alloys, preferably selected from the group consisting of reflective metals and reflective metal alloys, and more preferably selected from the group consisting of aluminum (Al), chromium (Cr), and nickel (Ni), and still more preferably aluminum (Al); or a combination of one or more layers A such as those described hereabove and one or more layers B such as those described hereabove. Typical examples of the platelet-shaped magnetic or magnetizable pigment particles being multilayered structures described hereabove include without limitation A/M multilayer structures, A/M/A multilayer structures, A/M/B multilayer structures, A/B/M/A multilayer structures, A/B/M/B multilayer structures, A/B/M/B/A/multilayer structures, B/M multilayer structures, B/M/B multilayer structures, B/A/M/A multilayer structures, B/A/M/B multilayer structures, B/A/M/B/A/multilayer structures, wherein the layers A, the magnetic layers M and the layers B are chosen from those described hereabove.

[051] The coating composition described herein may comprise platelet-shaped optically variable magnetic or magnetizable pigment particles, and/or platelet-shaped magnetic or magnetizable pigment particles having no optically variable properties. Preferably, at least a part of the platelet-shaped magnetic or magnetizable pigment particles described herein is constituted by platelet-shaped optically variable magnetic or magnetizable pigment particles. In addition to the overt security provided by the color-shifting property of the optically variable magnetic or magnetizable pigment particles, which allows easily detecting, recognizing and/or discriminating an article or security document carrying an ink, coating composition, or coating layer comprising the optically variable magnetic or magnetizable pigment particles described herein from their possible counterfeits using the unaided human senses, the optical properties of the optically variable magnetic or magnetizable pigment particles may also be used as a machine readable tool for the recognition of the OEL. Thus, the optical properties of the optically variable magnetic or magnetizable pigment particles may simultaneously be used as a covert or semi-covert security feature in an authentication process wherein the optical (e.g. spectral) properties of the pigment particles are analyzed.

[052] The use of platelet-shaped optically variable magnetic or magnetizable pigment particles in coating layers for producing an OEL enhances the significance of the OEL as a security feature in security document applications, because such materials are reserved to the security document printing industry and are not commercially available to the public.

[053] As mentioned above, preferably at least a part of the platelet-shaped magnetic or magnetizable pigment particles is constituted by platelet-shaped optically variable magnetic or magnetizable pigment particles. These are more preferably selected from the group consisting of magnetic thin-film interference pigment particles, magnetic cholesteric liquid crystal pigment particles, interference coated pigment particles comprising a magnetic material and mixtures of two or more thereof.

[054] Magnetic thin film interference pigment particles are known to those skilled in the art and are disclosed e.g. in US 4,838,648; WO 2002/073250 A2; EP 0 686 675 B1 ; WO 2003/000801 A2; US 6,838,166; WO 2007/131833 A1 ; EP 2 402 401 B1 ; WO 2019/103937 A1 ; WO 2020/006286 A1 and in the documents cited therein. Preferably, the magnetic thin film interference pigment particles comprise pigment particles having a five-layer Fabry-Perot multilayer structure and/or pigment particles having a six-layer Fabry-Perot multilayer structure and/or pigment particles having a seven-layer Fabry-Perot multilayer structure and/or pigment particles having a multilayer structure combining one or more multilayer Fabry-Perot structures.

[055] Preferred five-layer Fabry-Perot multilayer structures consist of absorber/dielectric/reflector/dielectric/absorber multilayer structures wherein the reflector and/or the absorber is also a magnetic layer, preferably the reflector and/or the absorber is a magnetic layer comprising nickel, iron and/or cobalt, and/or a magnetic alloy comprising nickel, iron and/or cobalt and/or a magnetic oxide comprising nickel (Ni), iron (Fe) and/or cobalt (Co).

[056] Preferred six-layer Fabry-Perot multilayer structures consist of absorber/dielectric/reflector/magnetic/dielectric/absorber multilayer structures.

[057] Preferred seven-layer Fabry Perot multilayer structures consist of absorber/dielectric/reflector/magnetic/reflector/dielectric/absorber multilayer structures such as disclosed in US 4,838,648.

[058] Preferred pigment particles having a multilayer structure combining one or more Fabry-Perot structures are those described in WO 2019/103937 A1 and consist of combinations of at least two Fabry- Perot structures, said two Fabry-Perot structures independently comprising a reflector layer, a dielectric layer and an absorber layer, wherein the reflector and/or the absorber layer can each independently comprise one or more magnetic materials and/or wherein a magnetic layer is sandwich between the two structures. WO 2020/006/286 A1 and EP 3 587 500 A1 disclose further preferred pigment particles having a multilayer structure. [059] Preferably, the reflector layers described herein are independently made from one or more 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 selected from the group consisting of aluminum (Al), chromium (Cr), nickel (Ni) and alloys thereof, and still more preferably aluminum (Al). Preferably, the dielectric layers are independently made from one or more selected from the group consisting of metal fluorides such as magnesium fluoride (MgF2), aluminum fluoride (AIF3), cerium fluoride (CeFs), lanthanum fluoride (LaFs), sodium aluminum fluorides (e.g. NasAIFs), neodymium fluoride (NdFs), samarium fluoride (SmFs), barium fluoride (BaF2), calcium fluoride (CaF2), lithium fluoride (LiF), and metal oxides such as silicon oxide (SiO), silicon dioxide (SiO2), titanium oxide (TiO2), aluminum oxide (AI2O3), more preferably selected from the group consisting of magnesium fluoride (MgF2) and silicon dioxide (SiCh) and still more preferably magnesium fluoride (MgF2). Preferably, the absorber layers are independently made from one or more 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 thereof, metal carbides thereof, and metal alloys thereof, more preferably selected from the group consisting of chromium (Cr), nickel (Ni), metal oxides thereof, and metal alloys thereof, and still more preferably selected from the group consisting of chromium (Cr), nickel (Ni), and metal alloys thereof. Preferably, the magnetic layer comprises nickel (Ni), iron (Fe) and/or cobalt (Co); and/or 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 absorber/dielectric/reflector/magnetic/reflector/dielectric/absorber multilayer structure consisting of a Cr/MgF2/AI/Ni/AI/MgF2/Cr multilayer structure.

[060] The magnetic thin film interference pigment particles described herein may be multilayer pigment particles being considered as safe for human health and the environment and being based for example on five-layer Fabry-Perot multilayer structures, six-layer Fabry-Perot multilayer structures, seven-layer Fabry-Perot multilayer structures and pigment particles having a multilayer structure combining one or more multilayer Fabry-Perot structures, wherein said pigment particles include one or more magnetic layers comprising a magnetic alloy having a substantially nickel-free composition including about 40 wt-% to about 90 wt-% iron, about 10 wt-% to about 50 wt-% chromium and about 0 wt-% to about 30 wt-% aluminum. Typical examples of multilayer pigment particles being considered as safe for human health and the environment can be found in EP 2 402 401 B1 whose content is hereby incorporated by reference in its entirety.

[061] Suitable magnetic cholesteric liquid crystal pigment particles exhibiting optically variable characteristics include without limitation magnetic monolayered cholesteric liquid crystal pigment particles and magnetic multilayered cholesteric liquid crystal pigment particles. Such pigment particles are disclosed for example in WO 2006/063926 A1 , US 6,582,781 and US 6,531 ,221 . WO 2006/063926 A1 discloses monolayers and pigment particles obtained therefrom with high brilliance and color-shifting properties with additional particular properties such as magnetizability. The disclosed monolayers and pigment particles, which are obtained therefrom by comminuting said monolayers, include a three- dimensionally crosslinked cholesteric liquid crystal mixture and magnetic nanoparticles. US 6,582,781 and US 6,410,130 disclose platelet-shaped cholesteric multilayer pigment particles which comprise the sequence A¹/B/A², wherein A¹ and A² may be identical or different and each comprises at least one cholesteric layer, and B is an interlayer absorbing all or some of the light transmitted by the layers A¹ and A² and imparting magnetic properties to said interlayer. US 6,531 ,221 discloses platelet-shaped cholesteric multilayer pigment particles which comprise the sequence A/B and optionally C, wherein A and C are absorbing layers comprising pigment particles imparting magnetic properties, and B is a cholesteric layer.

[062] Suitable interference coated pigment particles comprising one or more magnetic materials include without limitation structures consisting of a substrate selected from the group consisting of a core coated with one or more layers, wherein at least one of the core or the one or more layers have magnetic properties. For example, suitable interference coated pigment particles comprise a core made of a magnetic material such as those described hereabove, said core being coated with one or more layers made of one or more metal oxides, or they have a structure consisting of a core made of synthetic or natural micas, layered silicates (e.g. talc, kaolin and sericite), glasses (e.g. borosilicates), silicon dioxides (SiO2), aluminum oxides (AI2O3), titanium oxides (TiO2), graphites and mixtures of two or more thereof. Furthermore, one or more additional layers such as coloring layers may be present.

[063] The platelet-shaped magnetic or magnetizable pigment particles described herein may be surface treated so as to protect them against any deterioration that may occur in the coating composition and coating layer and/or to facilitate their incorporation in said coating composition and coating layer; typically corrosion inhibitor materials and/or wetting agents may be used.

[064] Further, subsequently to the application of the coating composition described herein on the substrate (x10) surface described herein so as to form the coating layer (x20) (step a)) described herein, the radiation curable coating composition is exposed to the magnetic field of the apparatus (xOO) described herein so as to orient at least a part of the platelet-shaped magnetic or magnetizable pigment particles, wherein the substrate (x10) carrying the coating layer (x20) is arranged above the apparatus (xOO), preferably wherein the apparatus (xOO) faces the substrate (x10), the one or more indentations (x31)/voids (x32) independently face the substrate (x10) and preferably represent the topmost element of the apparatus (xOO) and is exposed to the environment.

[065] Subsequently to or partially simultaneously, preferably partially simultaneously, with the step of orienting the platelet-shaped magnetic or magnetizable pigment particles as described herein (step c)), the orientation of the platelet-shaped magnetic or magnetizable pigment particles is fixed or frozen (step d)). The coating composition must thus noteworthy have a first state, i.e. a liquid or pasty state, wherein the coating composition is not yet hardened and wet or soft enough, so that the platelet-shaped magnetic or magnetizable pigment particles dispersed in the coating composition are freely movable, rotatable and orientable upon exposure to a magnetic field, and a second hardened (e.g. solid or solid-like) state, wherein the platelet-shaped magnetic or magnetizable pigment particles are fixed or frozen in their respective positions and orientations.

[066] Such a first and second states are preferably provided by using a certain type of coating compositions. For example, the components of the coating composition other than the platelet-shaped magnetic or magnetizable pigment particles may take the form of an ink or coating composition such as those which are used in security applications, e.g. for banknote printing. The aforementioned first and second states can be provided by using a material that shows an increase in viscosity in reaction to a stimulus such as for example a temperature change or an exposure to an electromagnetic radiation. That is, when the fluid binder material is hardened or solidified, said binder material converts into the second state, i.e. a hardened or solid state, where the platelet-shaped magnetic or magnetizable pigment particles are fixed in their current positions and orientations and can no longer move nor rotate within the binder material. As known to those skilled in the art, ingredients comprised in an ink or coating composition to be applied onto a surface such as a substrate and the physical properties of said ink or coating composition must fulfil the requirements of the process used to transfer the ink or coating composition to the substrate (x10) surface. Consequently, the binder material comprised in the coating composition described herein is typically chosen among those known in the art and depends on the coating or printing process used to apply the ink or coating composition and the chosen hardening process.

[067] The hardening step described herein (step d)) can be of purely physical nature, e.g. in cases where the coating composition comprises a polymeric binder material and a solvent and is applied at high temperatures. Then, the platelet-shaped magnetic or magnetizable pigment particles are oriented at high temperature by the application of a magnetic field, and the solvent is evaporated, followed by cooling of the coating composition. Thereby the coating composition is hardened, and the orientation of the particles is fixed.

[068] Alternatively and preferably, the hardening of the coating composition involves a chemical reaction, for instance by curing, which is not reversed by a simple temperature increase (e.g. up to 80°C) that may occur during a typical use of a security document. The term "curing” or “curable” refers to processes including the chemical reaction, crosslinking or polymerization of at least one component in the applied coating composition in such a manner that it turns into a polymeric material having a greater molecular weight than the starting substances. Preferably, the curing causes the formation of a stable three-dimensional polymeric network. Such a curing is generally induced by applying an external stimulus to the coating composition after its application on a substrate (step a)) and subsequently to, or partially simultaneously orientation of at least part of the platelet-shaped magnetic or magnetizable pigment particles (step b)). Advantageously the hardening (step c)) of the coating composition described herein is carried out partially simultaneously with the orientation of at least a part of the platelet-shaped magnetic or magnetizable pigment particles (step b)). Therefore, preferably the coating composition is selected from the group consisting of radiation curable compositions, thermally drying compositions, oxidatively drying compositions, and combinations thereof. Particularly preferred are coating compositions selected from the group consisting of radiation curable compositions. Radiation curing, in particular UV-Vis curing, advantageously leads to an instantaneous increase in viscosity of the coating composition after exposure to the irradiation, thus preventing any further movement of the pigment particles and in consequence any loss of information after the magnetic orientation step. Preferably, the hardening step (step d)) is carried out by irradiation with UV-visible light (i.e. UV-Vis light radiation curing) or by E-beam (i.e. E-beam radiation curing), more preferably by irradiation with UV-Vis light.

[069] Therefore, suitable coating compositions for the present invention include radiation curable compositions that may be cured by UV-visible light radiation (hereafter referred as UV-Vis-curable) or by E-beam radiation (hereafter referred as EB). According to one particularly preferred embodiment of the present invention, the coating composition described herein is a UV-Vis-curable coating composition. UV-Vis curing advantageously allows very fast curing processes and hence drastically decreases the preparation time of the OEL described herein, documents and articles and documents comprising said OEL.

[070] Preferably, the UV-Vis-curable coating composition comprises one or more compounds selected from the group consisting of radically curable compounds and cationically curable compounds. The UV-Vis-curable coating composition described herein may be a hybrid system and comprise a mixture of one or more cationically curable compounds and one or more radically curable compounds. Cationically curable compounds are cured by cationic mechanisms typically including the activation by radiation of one or more photoinitiators which liberate cationic species, such as acids, which in turn initiate the curing so as to react and/or cross-link the monomers and/or oligomers to thereby harden the coating composition. Radically curable compounds are cured by free radical mechanisms typically including the activation by radiation of one or more photoinitiators, thereby generating radicals which in turn initiate the polymerization so as to harden the coating composition. Depending on the monomers, oligomers or prepolymers used to prepare the binder comprised in the UV-Vis-curable coating compositions described herein, different photoinitiators might be used. Suitable examples of free radical photoinitiators are known to those skilled in the art and include without limitation acetophenones, benzophenones, benzyldimethyl ketals, alpha-aminoketones, alpha-hydroxyketones, phosphine oxides and phosphine oxide derivatives, as well as mixtures of two or more thereof. Suitable examples of cationic photoinitiators are known to those skilled in the art and include without limitation onium salts such as organic iodonium salts (e.g. diaryl iodoinium salts), oxonium (e.g. triaryloxonium salts) and sulfonium salts (e.g. triarylsulphonium salts), as well as mixtures of two or more thereof. Other examples of useful photoinitiators can be found in standard textbooks. It may also be advantageous to include a sensitizer in conjunction with the one or more photoinitiators in order to achieve efficient curing. Typical examples of suitable photosensitizers include without limitation isopropyl-thioxanthone (ITX), 1-chloro- 2-propoxy-thioxanthone (CPTX), 2-chloro-thioxanthone (CTX) and 2,4-diethyl-thioxanthone (DETX) and mixtures of two or more thereof. The one or more photoinitiators comprised in the UV-Vis-curable coating compositions are preferably present in a total amount from about 0.1 wt-% to about 20 wt-%, more preferably about 1 wt-% to about 15 wt-%, the weight percents being based on the total weight of the UV-Vis-curable coating compositions.

[071] Alternatively, a polymeric thermoplastic binder material or a thermoset may be employed. Typical examples of thermoplastic resin or polymer include without limitation polyamides, polyesters, polyacetals, polyolefins, styrenic polymers, polycarbonates, polyarylates, polyimides, polyether ether ketones (PEEK), polyetherketeoneketones (PEKK), polyphenylene based resins (e.g. polyphenylenethers, polyphenylene oxides, polyphenylene sulfides), polysulphones and mixtures oftwo or more thereof.

[072] The coating composition described herein may further comprise one or more additives including without limitation compounds and materials which are used for adjusting physical, rheological and chemical parameters of the composition such as the viscosity (e.g. solvents and surfactants), the consistency (e.g. anti-settling agents, fillers and plasticizers), the foaming properties (e.g. antifoaming agents), the lubricating properties (waxes), UV reactivity and stability (photosensitizers and photostabilizers) and adhesion properties, etc. Additives described herein may be present in the coating compositions described herein in amounts and in forms known in the art, including in the form of so- called nano-materials where at least one of the dimensions of the particles is in the range of 1 to 1000 nm.

[073] The coating composition described herein may further comprise one or more marker substances or taggants and/or one or more machine readable materials selected from the group consisting of magnetic materials (different from the magnetic or magnetizable pigment particles described herein), luminescent materials, electrically conductive materials and infrared-absorbing materials. As used herein, the term “machine readable material” refers to a material which exhibits at least one distinctive property which is detectable by a device or a machine, and which can be comprised in a coating so as to confer a way to authenticate said coating or article comprising said coating by the use of a particular equipment for its detection and/or authentication.

[074] The coating compositions described herein may be prepared by dispersing or mixing the magnetic or magnetizable pigment particles described herein and the one or more additives when present in the presence of the binder material described herein, thus forming liquid compositions. When present, the one or more photoinitiators may be added to the composition either during the dispersing or mixing step of all other ingredients or may be added at a later stage, i.e. after the formation of the liquid coating composition.

[075] The apparatus (xOO) described herein is configured for receiving the substrate (x10) in an orientation substantially parallel to a first plane and above the first plane allowing at least a part of the particles to be to oriented, wherein said apparatus (xOO) comprises a) the soft magnetic plate (x30) carrying one or more indicia in the form of one or more indentations (x31) and/or one or more voids (x32), and b) the magnetic-field-generating device (x40) comprising the at least one dipole magnet (x40- a), wherein the soft magnetic plate (x30) is placed on top of the magnetic-field-generating device (x40). [076] As shown in Figs. 1A, 1 B and 3A-1 to 3A-4, the substrate (x10) carrying the coating layer (x20) is preferably arranged above the apparatus (xOO) and the soft magnetic plate (x30) is arranged vertically above the magnetic-field-generating device (x40), in particular the at least one dipole magnet (x40-a), in a vertical axis i.e. the direction of their arrangement relative to each other being in essence vertical.

[077] The distance d-a (shown in Figs 1 B and 3A-1 to 3A-4) between the bottom surface of the soft magnetic plate (x30) and the top surface of the magnetic-field-generating device (x40) and the distance d-b (between the top surface of the soft magnetic plate (x30) and the bottom surface of the substrate (x10) during the orientation step (step b)) is adjusted and selected to obtain the desired optical effect layers (OELs). It is particularly preferred to use a distance d-a between about 0 mm and 6 mm and a distance d-b between about 0 mm and 1 mm, preferably about 0 mm. Should the magnetic-field- generating device (x40) consist of a single dipole magnet (x40-a), the distance d-a consists of the distance between the bottom surface of the soft magnetic plate (x30) and the top surface of the single dipole magnet (x40-a). Should the magnetic-field-generating device (x40) consist of a single dipole magnet (x40-a) and one or more additional magnets (x40-b, x40-c, etc.), the distance d-a consists of the distance between the bottom surface of the soft magnetic plate (x30) and the topmost surface of the magnetic-field-generating device (x40).

[078] The soft magnetic plate (x30) described herein carries one or more indicia in the form of one or more indentations (x31) and/or one or more voids (x32). As shown in Figs 5B-1 and 5C-1 , the expression “indentation” refers to a negative recess having a depth (D) in a surface. The indentations (x31) described herein may be produced by adding material to the surface or by taking off material from the surface of the soft magnetic plate (x30). As shown in Figs 5B-2 and 5C-2, the expression “void” refers to a hole or channel which goes through the soft magnetic plate (x30) and connects both sides thereof. [079] According to one embodiment, the soft magnetic metal plate (x30) described herein comprises one or more indentations (x31) having a depth (D). According to one embodiment, the soft magnetic metal plate (x30) described herein comprises one or more voids (x32). Figs 5B and 5C schematically depict cross sections of a soft magnetic plate (530) comprising one or more indicia in the form of one or more indentations (531) in Figs 5B-1 and 5C-1 or one or more voids (532) in Figs 5B-2 and 5C-2, wherein said magnetic plate (530) has a thickness (T) and said one or more indentations (531) have a depth (D). As shown in Figs 5B-1 and 5C-1 , the thickness (T) of the soft magnetic plate (530) comprising one or more indentations (531) refers to the thickness of the regions of the soft magnetic plate (530) lacking the one or more indentations (531) (i.e. the thickness of the non-indented regions of the soft magnetic plate (530)).

[080] The soft magnetic plate (x30) is placed above the magnetic-field-generating device (x40), wherein said soft magnetic plate (x30) is placed at the distance d-a from the topmost surface of the magnetic-field-generating device (x40). The soft magnetic plate (x30) is arranged vertically above the magnetic-field-generating device (x40) i.e. the direction of their arrangement relative to each other being in essence vertical.

[081] According to one embodiment shown for example in Figs 3A-1 to 3A-4, the soft magnetic plate (x30) is above the magnetic-field-generating device (x40), in particular the at least one dipole magnet (x40-a), in a vertical axis and i) partially overlaps (see Figs 3A-1 and 3A-2) ii) fully overlap said device (x40) (see Fig. 3A-4) or ill) does not overlap (see Fig. 3A-3), preferably partially overlaps or does not overlap said device (x40) and faces said device (x40). For embodiments wherein the soft magnetic plate (x30) is above the magnetic-field-generating device (x40) and partially overlaps (Fig. 3A-2), the overlapping distance d-d is preferably bigger than about 0 mm and smaller than about 5 mm.

[082] The term “above” defines the relative position of the soft magnetic plate (x30) and do not limit and define its absolute position. When used during the process for producing the optical effect layer (OEL) described herein, the apparatus (xOO) described herein can be placed in any orientation, preferably an orientation wherein the substrate (x10) faces the soft magnetic plates (x30) and the coating layer (x20) faces the environment, i.e. the opposite side of the plate (x30), as shown in Figs. 3A-1 to 3A- 4.

[083] According to one embodiment, the top surface of the soft magnetic plate (x30) is smaller than the total top surface of the magnetic-field-generating device (x40).

[084] According to one embodiment, the top surface of the soft magnetic plate (x30) is about the same size (width) as the total top surface of the magnetic-field-generating device (x40), said soft magnetic plate (x30) being partially overlapping or not overlapping said magnetic-field-generating device (x40).

[085] The soft magnetic plate (x30) described herein comprises one or more soft magnetic materials, i.e. materials having a low coercivity and a high permeability p. Their coercivity is lower than 1000 Am^-1 as measured according to IEC 60404-1 :2000, to allow for a fast magnetization and demagnetization. Suitable soft magnetic materials have a maximum relative permeability of at least 5, where the relative permeability /JR is the permeability of the material p relative to the permeability of the free space po ( iR - p / po) (Magnetic Materials, Fundamentals and Applications, 2^nd Ed., Nicola A. Spaldin, p. 16- 17, Cambridge University Press, 2011). Soft magnetic materials are described, for example, in the following handbooks: (1) Handbook of Condensed Matter and Materials Data, Chap. 4.3.2, Soft Magnetic Materials, p. 758-793, and Chap. 4.3.4, Magnetic Oxides, p. 811-813, Springer 2005; (2) Ferromagnetic Materials, Vol. 1 , Iron, Cobalt and Nickel, p. 1-70, Elsevier 1999; (3) Ferromagnetic Materials, Vol. 2, Chap. 2, Soft Magnetic Metallic Materials, p. 55-188, and Chap. 3, Ferrites for nonmicrowave Applications, p. 189-241 , Elsevier 1999; (4) Electric and Magnetic Properties of Metals, C. Moosbrugger, Chap. 8, Magnetically Soft Materials, p. 196-209, ASM International, 2000; (5) Handbook of modern Ferromagnetic Materials, Chap. 9, High-permeability High-frequency Metal Strip, p. 155-182, Kluwer Academic Publishers, 2002; and (6) Smithells Metals Reference Book, Chap. 20.3, Magnetically Soft Materials, p. 20-9 - 20-16, Butterworth-Heinemann Ltd, 1992.

[086] The soft magnetic plate (x30) described herein may either be a plate made of one or more metals, alloys or compounds of high magnetic permeability (hereafter referred as “soft magnetic metal plate”) or a plate made of a composite comprising soft magnetic particles dispersed in a non-magnetic material (hereafter referred as “soft magnetic composite plate”).

[087] According to one embodiment, the soft magnetic metal plate (x30) described herein is made of one or more soft magnetic metals or alloys easily workable as sheets or threads. Preferably, the soft magnetic metal plate described herein is made from one or more materials selected from the group consisting of iron, cobalt, nickel, nickel-molybdenum alloys, nickel-iron alloys (permalloy orsupermalloy- type materials), cobalt-iron alloys, cobalt-nickels alloys iron-nickel-cobalt alloys (Fernico-type materials), Heusler-type alloys (such as Cu2MnSn or Ni2MnAI), low silicon steels, low carbon steels, silicon irons (electrical steels), iron-aluminum alloys, iron-aluminum-silicon alloys, amorphous metal alloys (e.g. alloys like Metglas®, iron-boron alloys), nanocrystalline soft magnetic materials (e.g. Vitroperm®) and combinations thereof, more preferably selected from the group consisting of iron, cobalt, nickel, low carbon steels, silicon irons, nickel-iron alloys and cobalt-iron alloys and combinations thereof.

[088] For embodiments wherein the soft magnetic plate (x30) is a soft magnetic metal plate (x30) such as those described herein and comprising the one or more indentations (x31) described herein, said one or more indentations (x31) preferably independently have a depth (D) between about 30% and about 99% in comparison with the thickness (T) of the soft magnetic metal plate (x30), more preferably between about 30% and about 90% in comparison with the thickness (T) of the soft magnetic metal plate (x30). The soft magnetic metal plate (x30) comprising the one or more indentations (x31) described herein has preferably a thickness (T) between about 50 urn and about 1000 .m, more preferably between about 100 .m and about 500 .m still more preferably between about 100 p.m and about 150 p.m.

[089] For embodiments wherein the soft magnetic plate (x30) is a soft magnetic metal plate (x30) such as those described herein and comprising the one or more voids (x32) described herein, said soft magnetic metal plate (x30) preferably has a thickness (T) between about 50 m and about 1000 pm, more preferably between about 50 pm and about 500 pm still more preferably between about 100 pm and about 150 pm.

[090] According to another embodiment, the one or more soft magnetic plates (x30) described herein are made of a composite comprising from about 25 wt-% to about 95 wt-% of soft magnetic particles dispersed in a non-magnetic material, the weight percents being based on the total weight of the one or more soft magnetic plates. Preferably, the composite of the one or more soft magnetic composite plates (x30) comprises from about 50 wt-% to about 90 wt-%, of soft magnetic particles, the weight percents being based on the total weight of the one or more soft magnetic composite plates. The soft magnetic particles described herein are made of one or more soft magnetic materials preferably selected from the group consisting of iron (especially iron pentacarbonyl, also called carbonyl iron), nickel (especially nickel tetracarbonyl, also called carbonyl nickel), cobalt, soft magnetic ferrites (e.g. manganese-zinc ferrites and nickel-zinc ferrites), soft magnetic oxides (e.g. oxides of manganese, iron, cobalt and nickel), soft silicon irons, and combinations thereof, more preferably selected from the group consisting of carbonyl iron, carbonyl nickel, cobalt, soft silicon irons and combinations thereof.

[091] The soft magnetic particles may have a needle-like shape, a platelet-like shape or a spherical shape. Preferably, the soft magnetic particles have a spherical shape so as to maximize the saturation of the soft magnetic composite plate and have the highest possible concentration without losing the cohesion of the soft magnetic composite plate. Preferably, the soft magnetic particles have a spherical shape and have an average particle size (dso) between about 0.1 .m and about 1000 pm, more preferably between about 0.5 pm and about 100 pm, and still more preferably between about 1 pm and 20 about pm, dso being measured by laser diffraction using for example a microtrac X100 laser particle size analyzer.

[092] The soft magnetic composite plate (x30) described herein is made of a composite, wherein said composite comprises the soft magnetic particles described herein dispersed in a non-magnetic material. Suitable non-magnetic materials include without limitation polymeric materials forming a matrix for the dispersed soft magnetic particles. The polymeric matrix-forming materials may be one or more thermoplastic materials or one or more thermosetting materials or comprise one or more thermoplastic materials or one or more thermosetting materials. Suitable thermoplastic materials include without limitation polyamides, co-polyamides, polyphtalimides, polyolefins, polyesters, polytetrafluoroethylenes, polyacrylates, polymethacrylates (e.g. PMMA), polyimides, polyetherimides, polyetheretherketones, polyaryletherketones, polyphenylene sulfides, liquid crystal polymers, polycarbonates and mixtures thereof. Suitable thermosetting materials include without limitation epoxy resins, phenolic resins, polyimide resins, polyester resins, silicon resins and mixtures thereof. The soft magnetic plate described herein is made of a composite comprising from about 5 wt-% to about 75 wt-% of the non-magnetic material described herein, the weight percents being based on the total weight of the soft magnetic plate.

[093] The composite described herein may further comprise one or more additives such as for example hardeners, dispersants, plasticizers, fillers/extenders and defoamers.

[094] For embodiments wherein the soft magnetic plate (x30) is a soft magnetic composite plate (x30) such as those described herein and comprising the one or more indentations (x31) described herein, said one or more indentations (x31) preferably independently having a depth (D) preferably between about 30% and about 99% in comparison with the thickness (T) of the soft magnetic composite plate (x30), more preferably between about 30% and about 90% in comparison with the thickness (T) of the soft magnetic composite plate (x30) in comparison with the thickness (T) of the soft magnetic composite plate (x30). The soft magnetic composite plate (x30) comprising the one or more indentations (x31) described herein has preferably a thickness (T) between about 0.5 mm and about 5 mm, more preferably between about 0.7 mm and about 4 mm still more preferably between about 0.7 mm and about 3 mm. [095] For embodiments wherein the soft magnetic plate (x30) is a soft magnetic composite plate (x30) such as those described herein and comprising the one or more voids (x32) described herein, said soft magnetic composite plate (x30) preferably has a thickness (T) between about 0.5 mm and about 5 mm, more preferably between about 0.7 mm and about 4 mm still more preferably between about 0.7 mm and about 3 mm.

[096] The present invention advantageously uses the soft magnetic composite plates described herein since said plates may be easily produced and treated like any other polymer material. Techniques well-known in the art including 3D printing, lamination molding, compression molding, resin transfer molding or injection molding may be used. After molding, standard curing procedures may be applied, such as cooling down (when thermoplastic polymers are used) or curing at high or low temperature (when thermosetting polymers are used). Another way to obtain the soft magnetic composite plates described herein is to remove parts of them to get the required indentations or voids using standard tools to work out plastic parts. Especially, mechanical ablation tools may be advantageously used.

[097] According to one embodiment shown for example in Fig. 6A-12, the apparatus (xOO) described herein may further comprise an engraved magnetic plate (x80), wherein said engraved magnetic plate (x80) comprises one or more engravings (x81), said engravings (x81) preferably having the shape of indicia, wherein the indicia (x81) of the engraved magnetic plate (x80) may be the same as or may be different from the indicia of the soft magnetic plate (x30). The engraved magnetic plate (x80) described herein is placed on top of the magnetic-field-generating device (x40). According to one embodiment, the engraved magnetic plate (x80) is placed in the one or more regions being free from the soft magnetic plate (x30). Preferably, the top surface of the engraved magnetic plate (x80) is flush with the top surface of the soft magnetic plate (x30) and may partially or fully overlap the one or more regions being free from the soft magnetic plate (x30). Fig. 6A-12 shows an example wherein the engraved magnetic plate (680) comprising the engravings (681) is placed in one or more regions (one region in Fig. 6A-12) being free the soft magnetic plate (630). The engraved magnetic plate (x80) described herein may be adjacent to or spaced apart from the soft magnetic plate (x30). The engraved magnetic plate (x80) described herein is made from a permanent magnetic powder material and a polymer. The engraved magnetic plate (x80) described herein may typically be produced by an injection molding process or by metal or laser engraving. Preferred permanent magnetic powder materials include cobalt, iron and their alloys, chromium dioxide, generic magnetic oxide spinels, generic magnetic garnets, generic magnetic ferrites including the hexaferrites such as calcium-, strontium-, and barium-hexaferrite (CaFe12019, SrFe12019, BaFe12019, respectively), generic alnico alloys, generic samarium-cobalt (SmCo) alloys, and generic rare-earth-iron-boron alloys (such as NdFeB), as well as the permanent-magnetic chemical derivatives thereof (such as indicated by the term generic) and mixtures thereof. Plates made of a composite material comprising a polymer and a permanent magnetic powder are obtainable from many different sources, such as from Bomatec, Hori, CH, ARNOLD® Magnetic Technologies (Plastiform®) or from Materiali Magnetici, Albairate, Milano, IT (Plastoferrite).

[098] According to one embodiment shown in Fig. 5B-1 , the one or more indentations (x31) described herein independently have a V-shaped cross-section. According to one embodiment shown in Fig. 5C-

1 , the one or more indentations (x31) described herein independently have a stepped-shaped crosssection.

[099] According to one embodiment shown in Fig. 5B-2, the one or more voids (x32) described herein independently have a V-shaped cross-section. According to one embodiment shown in Fig. 5C-2, the one or more voids (x32) described herein independently have a stepped-shaped cross-section.

[0100] For embodiment with the one or more indentations (x31) and the one or more voids (x32) described herein independently having a stepped-shaped cross-section, said a stepped-shaped crosssection preferably has an angle (a) shown in Fig. 5B-1 and 5B-2 between about 30° and about 170°, more preferably between about 60° and about 120°.

[0101] According to one embodiment shown in Fig. 5C-1 , the one or more indentations (x31) described herein independently have a V-shaped cross-section. According to one embodiment shown in Fig. 5C-

2, the one or more voids (x32) described herein independently have a stepped-shaped cross-section. The stepped-shaped cross-section comprise at least two steps, wherein said at least two steps either have a same thickness and/or a same width or have a different thickness and/or different width. The Examples provided therein discloses a soft magnetic plate (x30) with an indentation (x31) having a stepped-shaped cross-section and four steps, wherein the four steps have the same width and the same thickness.

[0102] Preferably, the stepped-shaped cross-section of the one or more indentations (x31) and/or the one or more voids (x32) of the soft magnetic plate (x30) comprise between 2 and 20 steps, or in other words, the number of steps of the hard magnetic plate (x30) is between 2 and 20.

[0103] As shown in Figs. 6, the shape of the soft magnetic plate (x30) is not limited. For example, said soft magnetic plate (x30) may have the shape of a regular polygon (with or without rounded corners), an irregular polygon (with or without rounded corners), a disc, an oval, etc.

[0104] The shape of the non-magnetic holder case (x50), when present, is not limited. As an example shown in Figs 1 C, the non-magnetic holder case (x50) has a cross-section having a H-shape, which may be symmetric or asymmetric, preferably an asymmetric H-shape, and comprise a recess for receiving a soft magnetic plate (x30) and an area (for receiving the magnetic-field-generating device x40)). According to one embodiment, the soft magnetic plate (x30) is placed on top of the crossbar of the H-shaped non-magnetic holder case (x50) and the magnetic-field-generating device (x40) is placed below the crossbar of the H-shaped non-magnetic holder case (x50). The top surface of the nonmagnetic holder case (x50) may by curved in at least one direction so as to be adaptable in or on a rotating cylinder of printing assemblies.

[0105] When more than one soft magnetic plates (x30-1 , x30-2, x30-3, etc.) are comprised in the apparatus (xOO) described herein, the combined top surface of said soft magnetic plates (x30-1 and x30-2) is similar or the same as the total top surface of the magnetic-field-generating device (x40) or is smaller than the total top surface of the magnetic-field-generating device (x40) of the apparatus (xOO) to allow the observations of any structure(s) below said more than one magnetic plates (x30-1 , x30-2, x30-3, etc.).

[0106] For embodiments wherein the soft magnetic plate (x30) described herein comprises one or more voids (x32), i.e. said plate (x30) comprises one or more regions lacking any materials, any structure^) below the soft magnetic plate (x30) (such as the magnetic-field-generating device (x40) comprising the at least one dipole magnet (x40-a) and/or the non-magnetic holder case (x50) described herein) may be observed, said observation being carried out from the side of the soft magnetic plate (x30) of the apparatus (xOO) or from the side of the coating layer (x20) during the process described herein. For embodiments wherein the apparatus (xOO) comprises the non-magnetic holder case (x50) described herein, provided that the voids (x32) are not filled up with a non-magnetic non-transparent material, the fact that the top plate (x30) surface is smaller than the top device surface allows the observations of the non-magnetic holder case (x50). For embodiments wherein the apparatus (xOO) does not comprise the non-magnetic holder case (x50) described herein and provided that the one or more empty volumes defined by voids (x32) are not filled up with a non-magnetic non-transparent material, the magnetic- field-generating device (x40) may be observed.

[0107] According to one embodiment, the soft magnetic plate (x30) described herein is flat or planar. According to another embodiment, the magnetic plate described herein (x30) is curved so as to be adaptable in or on a rotating cylinder of printing assemblies.

[0108] The apparatus (xOO) described herein comprises the magnetic-field-generating device (x40) comprising the at least one dipole magnet (x40-a). Alternatively, the apparatus (xOO) described herein comprises the magnetic-field-generating device (x40) comprising a combination of two or more bar dipole magnets (x40-a, x40-b, x40-c, etc.). Depending on the required dynamic movement of the optical effect layer (OEL) upon tilting, different magnetic-field-generating devices (x40) comprising same or different bar dipole magnets may be used.

[0109] According to one embodiment shown for example in Fig. 2A, the apparatus (xOO) described herein is used in combination with a static a magnetic assembly (x60) described herein in the form of a device for producing the OELs described herein, wherein said device comprises the magnetic-field- generating device (x40) comprising the at least one dipole magnet (x40-a) described herein, the soft magnetic plate (x30) described herein and the magnetic assembly (x60) described herein, wherein the magnetic-field-generating device (x40) and the soft magnetic plate (x30) are arranged on or in a cylinder so that, when the cylinder is rotated, the magnetic-field-generating device (x40), the soft magnetic plate (x30) and the magnetic assembly (x60) are moved relatively to each other, or in other words the apparatus (xOO) and the magnetic assembly (x60) move relatively to each other, so that the surface of the apparatus (xOO) faces the magnetic assembly (x60) allowing at least a part of the particles to be bi- axially oriented. Fig. 2A shows such a device in which the apparatus (200) forms the assembly with the substrate (210) carrying the coating layer (220) while being mounted in a cylinder. The cylinder can be rotated so that it moves together with the substrate (210) on which the coating layer (220) is arranged. The cylinder comprises cavities, in which the apparatus (200) is inserted. Alternatively, the apparatus (200) may be arranged on a cylinder or may be only partially inserted. The magnetic assembly (260) is arranged above the cylinder so that the substrate (210) and the coating layer (220) can pass between the apparatus (200) and the magnetic assembly (260). As shown in Fig. 2A, the magnetic assembly (260) may have an arc-shape in the paper plane of Fig. 2A. However, the shape of the magnetic assembly (260) is not limited to such a shape. Any shape is conceivable as long as the substrate (x10) can pass through a space between the magnetic assembly (x60) and the apparatus (xOO) arranged in or on the cylinder and as long as the magnetic assembly (x60) and the apparatus (xOO) allow for bi- axially orienting the particles of the coating layer (x20). As shown in Fig. 2A, after the substrate (210) has passed through the space between the cylinder and the magnetic assembly (260) the so-obtained magnetic orientation of the particles in the coating layer (220) is fixed/frozen by at least partially curing with the curing unit (250).

[0110] According to one embodiment shown for example in Fig. Fig. 2B, the apparatus (xOO) described herein is used in combination with a static a magnetic assembly (x60) described herein in the form of a device for producing the OELs described herein and shown in Fig. 2A, wherein a pre-orientation step is carried out with a magnetic assembly (260-a). According to said embodiment, the platelet-shaped magnetic or magnetizable pigment particles are subjected to pre-orientation step and, subsequently, the apparatus (xOO) described herein is used in combination with a static a magnetic assembly (x60) described herein in the form of a device for producing the OELs described herein, wherein said device comprises the magnetic-field-generating device (x40) comprising the at least one dipole magnet (x40- a) described herein, the soft magnetic plate (x30) described herein and the magnetic assembly (x60) described herein, wherein the magnetic-field-generating device (x40) and the soft magnetic plate (x30) are arranged on or in a cylinder so that, when the cylinder is rotated, the magnetic-field-generating device (x40), the soft magnetic plate (x30) and the magnetic assembly (x60) are moved relatively to each other, or in other words the apparatus (xOO) and the magnetic assembly (x60) move relatively to each other, so that the surface of the apparatus (xOO) faces the magnetic assembly (x60) allowing at least a part of the particles to be bi-axially oriented. Fig. 2B shows such a device in which the apparatus (200) forms the assembly with the substrate (210) carrying the coating layer (220) while being mounted in a cylinder. The cylinder can be rotated so that it moves together with the substrate (210) on which the coating layer (220) is arranged. The cylinder comprises cavities, in which the apparatus (200) is inserted. Alternatively, the apparatus (200) may be arranged on a cylinder or may be only partially inserted. The magnetic assembly (260) is arranged above the cylinder so that the substrate (210) and the coating layer (220) can pass between the apparatus (200) and the magnetic assembly (260). As shown in Fig. 2B, the magnetic assembly (260) may have an arc-shape. However, the shape of the magnetic assembly (260) is not limited to such a shape. Any shape is conceivable as long as the substrate (x10) can pass through a space between the magnetic assembly (x60) and the apparatus (xOO) arranged in or on the cylinder and as long as the magnetic assembly (x60) and the apparatus (xOO) allow for bi- axially orienting the particles of the coating layer (x20). As shown in Fig. 2B, after the substrate (210) has passed through the space between the cylinder and the magnetic assembly (260) the so-obtained magnetic orientation of the particles in the coating layer (220) is fixed/frozen by at least partially curing with the curing unit (250).

[OHl] The OEL described herein comprise magnetically oriented platelet-shaped magnetic or magnetizable pigment particles on the substrate (x10), said optical effect layer (OEL) comprising at least a first area exhibiting a 3D effect in the form of the one or more indicia and at least a second area exhibiting the dynamic movement upon tilting, wherein the dynamic effect is obtained from the assembly (x100) described herein and comprising the soft magnetic plate (x30), the magnetic-field-generating device (x40), the substrate (x10) carrying the coating layer (x20) in combination with the magnetic assembly (x60) described herein. The magnetic-field-generating devices (x40) described herein are not limited and the following examples are provided for illustrative purposes.

[0112] According to one embodiment, the process described herein allows the preparation of OELs wherein at least a second area exhibits the dynamic movement upon tilting said OEL, said dynamic movement being a bright reflective horizontal bar moving in a vertical direction (up/down) when the OEL is tilted around a horizontal axis; wherein the magnetic-field-generating device (x40) is a bar dipole magnet has a magnetic axis oriented to be substantially parallel to the substrate and substantially parallel to the machine feed direction. This effect is the so-called “rolling bar” effect, as disclosed in US 2005/0106367. A “rolling bar” effect is based on pigment particles orientation imitating a curved surface across the coating. The observer sees a specular reflection zone which moves away or towards the observer as the OEL is tilted.

[0113] According to another embodiment, the process described herein allows the preparation of OELs wherein at least a second area exhibits the dynamic movement upon tilting said OEL, said dynamic movement of the OEL being a bright reflective vertical bar moving in a horizontal direction (left/right) when the OEL is tilted around a vertical axis; wherein the magnetic-field-generating device (x40) is a bar dipole magnet having a magnetic axis oriented to be substantially parallel to the substrate and substantially perpendicular to the machine feed direction. This effect is the so-called “rolling bar” effect, as disclosed in US 2005/0106367.

[0114] According to another embodiment, the process described herein allows the preparation of OELs wherein at least a second area exhibits the dynamic movement upon tilting said OEL, said dynamic movement of the OEL being a bright reflective vertical bar moving in a horizontal (left/right) direction when the OEL is tilted around a horizontal axis; wherein the magnetic-field-generating device (x40) is a device such as those disclosed in WO 2020/160993 A1 .

[0115] According to another embodiment, the process described herein allows the preparation of OELs wherein at least a second area exhibits the dynamic movement upon tilting said OEL, said dynamic movement of the OEL being a bright reflective horizontal bar moving in a vertical direction (up/down) when the OEL is tilted around a horizontal axis; wherein the magnetic-field-generating device (x40) is a device such as those disclosed in WO 2014/198905 A2.

[0116] According to one embodiment, the process described herein allows the preparation of OELs wherein at least a second area exhibits the dynamic movement upon tilting said OEL upon tilting said OEL, said dynamic movement being a pattern of bright areas and dark areas moving when the OEL is tilted; wherein the magnetic-field-generating device (x40) is a device such as those disclosed in WO 2013/167425 A1 and WO 2021/083809 A1 .

[0117] According to one embodiment, the process described herein allows the preparation of OELs wherein at least a second area exhibits the dynamic movement upon tilting said OEL upon tilting said OEL, said dynamic movement being a pattern of bright areas and dark areas moving when the OEL is tilted; wherein the magnetic-field-generating device (x40) is a device such as those disclosed in WO 2021/083808 A1.

[0118] According to one embodiment, the process described herein allows the preparation of OELs wherein at least a second area exhibits the dynamic movement upon tilting said OEL upon tilting said OEL, said dynamic movement being a loop-shaped body moving when the OEL is tilted, wherein the magnetic-field-generating device (x40) is a device such as those disclosed in WO 2014/108404 A2.

[0119] According to one embodiment, the process described herein allows the preparation of OELs the process described herein allows the preparation of OELs wherein at least a second area exhibits the dynamic movement upon tilting said OEL, said dynamic movement being a nested multi-loop-shaped body moving when the OEL is tilted; wherein the magnetic- field-generating device (x40) is a device such as those disclosed in WO 2014/108303 A2.

[0120] According to one embodiment, the process described herein allows the preparation of OELs wherein at least a second area exhibits the dynamic movement upon tilting said OEL upon tilting said OEL, said dynamic movement being a loop-shaped body having a size that varies when the OEL is tilted; wherein the magnetic-field-generating device (x40) is a device such as those disclosed in WO 2017/064052 A1 , WO 2017/080698 A1 and WO 2017/148789 A1 .

[0121] According to one embodiment, the process described herein allows the preparation of OELs wherein at least a second area exhibits the dynamic movement upon tilting said OEL upon tilting said OEL, said dynamic movement being one or more loop-shaped bodies having a shape that varies when the OEL is tilted; wherein the magnetic-field-generating device (x40) is a device such as those disclosed in WO 2018/054819 A1.

[0122] According to one embodiment, the process described herein allows the preparation of OELs wherein at least a second area exhibits the dynamic movement upon tilting said OEL upon tilting said OEL, said dynamic movement being a moon crescent moving and rotating when the OEL is tilted; wherein the magnetic-field-generating device (x40) is a device such as those disclosed in WO 2019/215148 A1.

[0123] According to one embodiment, the process described herein allows the preparation of OELs wherein at least a second area exhibits the dynamic movement upon tilting said OEL upon tilting said OEL, said dynamic movement being a loop-shaped body surrounded by one or more loop-shaped bodies having their shape and/or their brightness varying when the OEL is tilted; wherein the is a device magnetic-field-generating device (x40) such as those disclosed in WO 2020/193009 A1.

[0124] According to one embodiment, the process described herein allows the preparation of OELs wherein at least a second area exhibits the dynamic movement upon tilting said OEL upon tilting said OEL, said dynamic movement being a change from dark to light of two areas when the OEL is tilted (effect so-called flip-flop); wherein the magnetic-field-generating device (x40) is a device such as those disclosed in Fig. 1 , 3 and 6 of US 2005/0106367.

[0125] According to one embodiment, the process described herein allows the preparation of OELs wherein at least a second area exhibits the dynamic movement upon tilting said OEL upon tilting said OEL, said dynamic movement being at least one comet-shaped spot rotating around said center of rotation upon tilting said OEL, the magnetic-field-generating device (x40) is a device such as those disclosed in WO 2019/038371 A1 , WO 2019/ 038370 A1 and WO 2019/038369 A1 .

[0126] The assembly (x100) comprising the substrate (x20) carrying the coating layer (x20) and the apparatus (xOO) described herein is moved through the inhomogeneous magnetic field of the static magnetic assembly (x60) described herein so that the platelet-shaped magnetic or magnetizable pigment particles are exposed to a magnetic field which is at least time- varying in direction thus bi-axially orienting at least part of said platelet-shaped magnetic or magnetizable pigment particles while the coating composition is still in a wet (i.e. not yet hardened) state. The distance d-c (shown in Fig. 1 B) between the coating layer (x20) and the magnetic assembly (x60) is adjusted and selected to obtain the desired optical effect layers.

[0127] The movement of said assembly (x100) within the magnetic field of the static magnetic assembly (x60) must allow the magnetic field vector, as described in the reference frame of the substrate, to vary essentially within a single plane at individual locations on the substrate. This can be achieved by rotational oscillations, by complete (360° or more) rotation of the assembly (x100), preferably by a back and forth translational movement along a path, more preferably by a translational movement in a single direction along a path. Particularly preferable are single translational movements that follow a linear or cylindrical path. The soft magnetic plate (x30) described herein acts as a magnetic field guide, very close to the coating composition, when placed into the magnetic field of the external static magnetic assembly (x60), hence deviating the magnetic field from its original direction. At the place of the indentations (x31) and/or voids (x32), the direction and intensity of the magnetic field lines are locally modified so as to cause the orientation of the platelet-shaped magnetic or magnetizable pigment particles to locally change compared to the orientation of the pigment particles that are further away from said indentations or protrusions. This in turn generates, in addition to the dynamic appearance described herein, the desired eye-catching relief and 3D effect.

[0128] Contrary to a mono-axial orientation wherein the platelet-shaped magnetic or magnetizable pigment particles are orientated in such a way that only one of their main axis (the longer one) is constrained by the magnetic field vector, carrying out a bi-axial orientation means that the plateletshaped magnetic or magnetizable pigment particles are made to orient in such a way that both their two main axes are constrained. Such biaxial orientation is achieved, according to the invention, by exposing and moving the assembly (x100) comprising the substrate (x10) carrying the coating layer (x20) and the apparatus (xOO) to and through the inhomogeneous magnetic field of the magnetic assembly (x60). Accordingly, said magnetic assembly (x60)must be configured in such a way that, along the path of motion followed by individual platelet-shaped magnetic or magnetizable pigment particles of the coating layer, the magnetic field lines change at least in direction within a plane which is fixed in the reference frame of the moving assembly (x100). Bi-axial orientation aligns the planes of the platelet-shaped magnetic or magnetizable pigment particles so that said planes are oriented to be locally substantially parallel to each other.

[0129] According to one embodiment, the step of carrying out a bi-axial orientation of the plateletshaped magnetic or magnetizable pigment particles leads to a magnetic orientation wherein the plateletshaped magnetic or magnetizable pigment particles have their two main axes substantially parallel to the substrate (x10) surface and to the first plane (P) except in the regions facing indentations/voids and in the regions submitted to the influence of the magnetic field of the magnetic-field-generating device (x40). For such an alignment, the platelet-shaped magnetic or magnetizable pigment particles are planarized within the coating layer (x20) on the substrate (x10) and are oriented with both their axis parallel with the substrate surface, except in the regions facing the one or more indentations/voids where a wider range of angles is covered.

[0130] According to another embodiment, the step of carrying a bi-axial orientation of at least a part of the platelet-shaped magnetic or magnetizable pigment particles leads to a magnetic orientation wherein the platelet-shaped magnetic or magnetizable pigment particles have a first main axis substantially parallel to the substrate (x10) surface and to the first plane (P) and a second main axis being perpendicular to said first axis at a substantially non-zero elevation angle to the substrate (x10) surface and to the first plane (P) except in the regions facing indentations/voids and in the regions submitted to the influence of the magnetic field of the magnetic-field-generating device (x40), where a wider range of angles is covered. Alternatively, the platelet-shaped magnetic or magnetizable pigment particles have their two main axes X and Y at a substantially non-zero elevation angle to the substrate (x10) surface and to the first plane (P) except in the regions facing indentations/voids and in the regions submitted to the influence of the magnetic field of the magnetic-field-generating device (x40), where a wider range of angles is covered. This is achieved when, seen along the path of motion, the angle between the magnetic field lines of the magnetic-field-generating device vary within a plane that forms a non-zero angle with respect to a plane tangential to the surface of assembly (x100) comprising the substrate (x10) carrying the coating layer (x20) and the apparatus (xOO).

[0131] Suitable magnetic assemblies (x60) for bi-axially orienting the platelet-shaped magnetic or magnetizable pigment particles described herein are not limited.

[0132] Bi-axial orientation of the platelet-shaped magnetic or magnetizable pigment particles may be carried out by moving the assembly (x100) comprising the substrate (x10) carrying the coating layer (x20) and the apparatus (xOO) at an appropriate speed through the magnetic field of the magnetic-field- generating device (x60) such as those described in EP 2 157 141 A1 . Such devices provide a magnetic field that changes its direction while the platelet-shaped magnetic or magnetizable pigment particles move through said devices, forcing the platelet-shaped magnetic or magnetizable pigment particles to rapidly oscillate until both main axes, X-axis and Y-axis, become parallel to the substrate (x10) surface and to the first plane (P), i.e. the platelet-shaped magnetic or magnetizable pigment particles oscillate until they come to the stable sheet-like formation with their X and Y axes parallel to the substrate (x10) surface and to the first plane (P) and are planarized in said two dimensions. As shown in Fig. 5 of EP 2 157 141 A1 , the magnetic assembly (x60) herein comprises a linear arrangement of at least three magnets that are positioned in a staggered fashion or in zigzag formation, said at least three magnets being on opposite sides of a feedpath where magnets at the same side of the feedpath have the same polarity, which is opposed to the polarity of the magnet(s) on the opposing side of the feedpath in a staggered fashion. The arrangement of the at least three magnets provides a predetermined change of the field direction as platelet-shaped magnetic or magnetizable pigment particles in a coating composition move past the magnets (direction of movement: arrow). According to one embodiment, the magnetic assembly (x60) comprises a) a first magnet and a third magnet on a first side of a feedpath and b) a second magnet between the first and third magnets on a second opposite side of the feedpath, wherein the first and third magnets have a same polarity and wherein the second magnet has a complementary polarity to the first and third magnets. According to another embodiment, the magnetic assembly (x60) further comprises a fourth magnets on the same side of the feedpath as the second magnet, having the polarity of the second magnet and complementary to the polarity of the third magnet. As described in EP 2 157 141 A1 , the magnetic assembly (x60) can be either underneath the layer comprising the platelet-shaped magnetic or magnetizable pigment particles, or above and underneath. [0133] Bi-axial orientation of the platelet-shaped magnetic or magnetizable pigment particles may be carried out by moving the assembly (x100) comprising the substrate (x10) carrying the coating layer (x20) and the apparatus (xOO) at an appropriate speed through the magnetic field of the magnetic assembly (x60) described in EP 1 519 794 B1. Suitable magnetic assemblies (x60) include permanent magnets being disposed on each side of the assembly (x100) surface, above or below it, such that the magnetic field lines are substantially parallel to the assembly (x100) surface.

[0134] Bi-axial orientation of the platelet-shaped magnetic or magnetizable pigment particles may be carried out by moving the assembly (x100) comprising the substrate (x10) carrying the coating layer (x20) and the apparatus (xOO) at an appropriate speed through the magnetic field of the magnetic assembly (x60) consisting of linear permanent magnet Halbach arrays, i.e. devices comprising a plurality of magnets with different magnetization directions and cylinder devices. Detailed description of Halbach permanent magnets was given by Z.Q. Zhu and D. Howe (Halbach permanent magnet machines and applications: a review, IEE. Proc. Electric Power Appl., 2001 , 148, p. 299-308). The magnetic field produced by such a magnetic assembly (x60) consisting of a Halbach array has the properties that it is concentrated on one side while being weakened almost to zero on the other side. Linear Halbach arrays are disclosed for example in WO 2015/086257 A1 and WO 2018/019594 A1 and Halbach cylinder devices are disclosed in EP 3 224 055 B1.

[0135] Bi-axial orientation of the platelet-shaped magnetic or magnetizable pigment particles may be carried out by moving the assembly (x100) comprising the substrate (x10) carrying the coating layer (x20) and the apparatus (xOO) at an appropriate speed through the magnetic field of the magnetic assembly (x60) consisting of a spinning magnet, said magnet comprising one or more disc-shaped spinning magnets or magnetic-field generating devices that are essentially magnetized along their diameter. Suitable magnetic assemblies (x60) consisting of spinning magnets or magnetic-field generating devices are described in US 2007/0172261 A1 , said spinning magnets or magnetic-field generating devices generating radially symmetrical time-variable magnetic fields, allowing the bi-axial orientation of pigment particles of a not yet cured coating composition. These magnets or magnetic- field generating devices are driven by a shaft (or spindle) connected to an external motor. CN 102529326 B discloses examples of magnetic assembly (x60) comprising spinning magnets that might be suitable for bi-axially orienting pigment particles. In a preferred embodiment, suitable magnetic-field-generating device (x60) are shaft-free disc-shaped spinning magnets or magnetic-field generating devices constrained in a housing made of non-magnetic, preferably non-conducting, materials and are driven by one or more magnet-wire coils wound around the housing. Examples of such shaft-free disc-shaped spinning magnets or magnetic-field generating devices are disclosed in WO 2015/082344 A1 , WO 2016/026896 A1 and WO2018/141547 A1 .

[0136] Bi-axial orientation of the platelet-shaped magnetic or magnetizable pigment particles may be carried out by moving the assembly (x100) comprising the substrate (x10) carrying the coating layer (x20) and the apparatus (xOO) at an appropriate speed through the magnetic field of the magnetic assembly (x60) comprising a) at least a first set (S1) and a second set (S2), each of the first and second sets (S1 , S2) comprising one first bar dipole magnet having its magnetic axis oriented to be substantially parallel to the substrate during the magnetic orientation and two second bar dipole magnets having their magnetic axes oriented to be substantially perpendicular to the substrate; and b) a pair (P1) of third bar dipole magnets having their magnetic axes oriented to be substantially parallel to the substrate such as those disclosed in WO 2021/239607 A1. Fig. 7 schematically illustrates such an analogous magnetic assembly (x60) being the magnetic assembly (760).

[0137] The process for producing the OEL described herein comprises partially simultaneously with step c) or subsequently to step c), preferably partially simultaneously, a step of hardening (step d)) the coating composition. The step of hardening the coating composition allows the platelet-shaped magnetic or magnetizable pigment particles to be fixed in their adopted positions and orientations in a desired pattern to form the OEL, thereby transforming the coating composition to a second state. However, the time from the end of step c) to the beginning of step d) is preferably relatively short in order to avoid any de-orientation and loss of information. Typically, the time between the end of step c) and the beginning of step d) is less than 1 minute, preferably less than 20 seconds, further preferably less than 5 seconds. It is particularly preferable that there is essentially no time gap between the end of the orientation step c) and the beginning of the curing step d), i.e. that step d) follows immediately after step c) or already starts while step c) is still in progress (partially simultaneously). By “partially simultaneously”, it is meant that both steps are partly performed simultaneously, i.e. the times of performing each of the steps partially overlap. In the context described herein, when hardening is performed partially simultaneously with the step c), it must be understood that hardening becomes effective after the orientation so that the platelet-shaped magnetic or magnetizable pigment particles orient before the complete or partial hardening of the OEL. As mentioned herein, the hardening step (step d)) may be performed by using different means or processes depending on the binder material comprised in the coating composition that also comprises the platelet-shaped magnetic or magnetizable pigment particles. [0138] The hardening step generally may be any step that increases the viscosity of the coating composition such that a substantially solid material adhering to the substrate is formed. The hardening step may involve a physical process based on the evaporation of a volatile component, such as a solvent, and/or water evaporation (i.e. physical drying). Herein, hot air, infrared or a combination of hot air and infrared may be used. Alternatively, the hardening process may include a chemical reaction, such as a curing, polymerizing or cross-linking of the binder and optional initiator compounds and/or optional cross-linking compounds comprised in the coating composition. Such a chemical reaction may be initiated by heat or IR irradiation as outlined above for the physical hardening processes, but may preferably include the initiation of a chemical reaction by a radiation mechanism including without limitation Ultraviolet-Visible light radiation curing (hereafter referred as UV-Vis curing) and electronic beam radiation curing (E-beam curing); oxypolymerization (oxidative reticulation, typically induced by a joint action of oxygen and one or more catalysts preferably selected from the group consisting of cobalt- containing catalysts, vanadium-containing catalysts, zirconium-containing catalysts, bismuth-containing catalysts and manganese-containing catalysts); cross-linking reactions or any combination thereof.

[0139] Radiation curing is particularly preferred, and UV-Vis light radiation curing is even more preferred, since these technologies advantageously lead to very fast curing processes and hence drastically decrease the preparation time of any article comprising the OEL described herein. Moreover, radiation curing has the advantage of producing an almost instantaneous increase in viscosity of the coating composition after exposure to the curing radiation, thus minimizing any further movement of the particles. In consequence, any loss of orientation after the magnetic orientation step can essentially be avoided. Particularly preferred is radiation-curing by photo-polymerization, under the influence of actinic light having a wavelength component in the UV or blue part of the electromagnetic spectrum (typically 200 nm to 650 nm; more preferably 200 nm to 420 nm). Equipment for UV-visible-curing may comprise a high-power light-emitting-diode (LED) lamp, or an arc discharge lamp, such as a medium-pressure mercury arc (MPMA) or a metal-vapor arc lamp, as the source of the actinic radiation.

[0140] The process for producing the OEL described herein may further comprise a step e) of releasing or separating the substrate (x10) carrying the so-obtained OEL from the soft magnetic plate (x30).

[0141] The present invention provides the processes to produce the OELs described herein on the substrate (x10) described herein. The substrate described herein is preferably selected from the group consisting of papers or other fibrous materials (including woven and non-woven fibrous materials), such as cellulose, paper-containing materials, glasses, metals, ceramics, plastics and polymers, metalized plastics or polymers, at least partially opacified plastics or polymers, composite materials and mixtures or combinations of two or more thereof. Typical paper, paper-like or other fibrous materials are made from a variety of fibers including without limitation abaca, cotton, linen, wood pulp, and blends thereof. As is well known to those skilled in the art, cotton and cotton/linen blends are preferred for banknotes, while wood pulp is commonly used in non-banknote security documents. Typical examples of plastics and polymers include polyolefins such as polyethylene (PE) and polypropylene (PP) including biaxially oriented polypropylene (BOPP), polyamides, polyesters such as poly(ethylene terephthalate) (PET), poly(1 ,4-butylene terephthalate) (PBT), polyethylene 2,6-naphthoate) (PEN) and polyvinylchlorides (PVC). Spunbond olefin fibers such as those sold under the trademark Tyvek® may also be used as substrate. Typical examples of metalized plastics or polymers include the plastic or polymer materials described hereabove having a metal disposed continuously or discontinuously on their surface. Typical examples of metals include without limitation aluminum (Al), chromium (Cr), copper (Cu), gold (Au), silver (Ag), alloys thereof and combinations of two or more of the aforementioned metals. The metallization of the plastic or polymer materials described hereabove may be done by an electrodeposition process, a high-vacuum coating process or by a sputtering process. Opacified polymers have been developed with the aim of mimicking the appearance and some properties of conventional paper-based substrates for security document and consist of polymeric transparent substrates which are surface treated typically on one or on both of their sides with opacifying layers so as to form opacified polymer based substrates. Typical examples of composite materials include without limitation multilayer structures or laminates of paper and at least one plastic or polymer material such as those described hereabove as well as plastic and/or polymer fibers incorporated in a paper-like or fibrous material such as those described hereabove. Of course, the substrate can comprise further additives that are known to the skilled person, such as fillers, sizing agents, Whiteners, processing aids, reinforcing or wet strengthening agents, etc. When the OELs produced according to the present invention are used for decorative or cosmetic purposes including for example fingernail lacquers, said OEL may be produced on other type of substrates including nails, artificial nails or other parts of an animal or human being.

[0142] According to one embodiment, the substrate (x10) described herein is a transparent substrate preferably selected from the group consisting of transparent polyolefins (such as polyethylene (PE) and polypropylene (PP) including biaxially oriented polypropylene (BOPP)), transparent polyamides, transparent polyesters (such as polyethylene terephthalate) (PET), poly(1 ,4-butylene terephthalate) (PBT), polyethylene 2,6-naphthoate) (PEN) and transparent polyvinylchlorides (PVC), more preferably biaxially oriented polypropylene; or a partially opacified substrate, in particular an at least partially opacified transparent polymer, preferably selected from the group consisting of transparent polyolefins (such as polyethylene (PE) and polypropylene (PP) including biaxially oriented polypropylene (BOPP)), transparent polyamides, transparent polyesters (such as polyethylene terephthalate) (PET), poly(1 ,4- butylene terephthalate) (PBT), polyethylene 2,6-naphthoate) (PEN) and transparent polyvinylchlorides (PVC), more preferably biaxially oriented polypropylene. According to one embodiment, the OELs described herein are present on a banknote and are present on a transparent substrate such as those described herein and preferably in the form of a window or a foil or on an at least partially opacified substrate such as those described herein, preferably in the non-opacified areas, preferably in the form of a non-opacified area in the form of a window or a foil.

[0143] The substrates (x10) described herein may be in the form of webs, sheets, thread reels, film reels, labels of the roll or label stocks, preferably sheets.

[0144] Should the OEL produced according to the present invention be on a security document, and with the aim of further increasing the security level and the resistance against counterfeiting and illegal reproduction of said security document, the substrate may comprise printed, coated, or laser-marked or laser-perforated indicia, watermarks, security threads, fibers, planchettes, luminescent compounds, windows, foils, decals and combinations of two or more thereof. With the same aim of further increasing the security level and the resistance against counterfeiting and illegal reproduction of security documents, the substrate may comprise one or more marker substances or taggants and/or machine readable substances. According to one embodiment, the substrate (x10) comprises a printed pattern, preferably an offset printed pattern, wherein the radiation curable coating composition of step a).

[0145] If desired, a primer layer may be applied to the substrate (x10) prior to the step a). This may enhance the quality of the OEL described herein or promote adhesion. Examples of such primer layers may be found in WO 2010/058026 A2.

[0146] With the aim of increasing the durability through soiling or chemical resistance and cleanliness and thus the circulation lifetime of an article, a security document or a decorative element or object comprising the OEL obtained by the process described herein, or with the aim of modifying their aesthetical appearance (e.g. optical gloss), one or more protective layers may be applied on top of the OEL. When present, the one or more protective layers are typically made of protective varnishes. These may be transparent or slightly colored or tinted and may be more or less glossy. Protective varnishes may be radiation curable compositions, thermal drying compositions or any combination thereof. Preferably, the one or more protective layers are radiation curable compositions, more preferable UV- Vis curable compositions. The protective layers are typically applied after the formation of the OEL.

[0147] The process described herein may further comprise a step of embossing the OEL described herein using for example an embossing dye or an intaglio printing plate as disclosed in WO 2012/025206 A2 and WO 2019/233624 A1 .

[0148] The OEL described herein may be used in combination with holograms, microlenses and/or micromirrors as described in WO 2020/244805 A1 , EP 3 254 863 A1 , US 2008/0160226, US 2005/0180020 and EP 2 284 017 A1 , said holograms, microlenses and/or micromirrors being applied at a position spaced apart from the OEL or least partially on top or below the OEL.

[0149] The present invention further provides optical effect layers (OELs) produced by the process according to the present invention.

[0150] The OEL described herein may be provided directly on a substrate (x10) on which it shall remain permanently (such as for banknote applications). Alternatively, an OEL comprising the first and second motifs described herein on the same side of the substrate (x10) may also be provided on a temporary substrate for production purposes, from which the OEL is subsequently removed. This may for example facilitate the production of the OEL, particularly while the binder material is still in its fluid state. Thereafter, after curing the radiation curable compositions for the production of the OEL, the temporary substrate may be removed from said OEL.

[0151] Alternatively, in another embodiment an adhesive layer may be present. Therefore, an adhesive layer may be applied after the curing step of the last set of steps described herein has been completed. Such an article may be attached to all kinds of documents or other articles or items without printing or other processes involving machinery and rather high effort. Alternatively, the substrate described herein comprising the OEL described herein may be in the form of a transfer foil, which can be applied to a document or to an article in a separate transfer step. For this purpose, the substrate is provided with a release coating, on which the OEL is produced as described herein.

[0152] Also described herein are substrates (x10) comprising more than one, i.e. two, three, four, etc. OELs obtained by the process described herein.

[0153] Also described herein are articles, in particular security documents, decorative elements or objects, comprising the OEL produced according to the present invention. The articles, in particular security documents, decorative elements or objects, may comprise more than one (for example two, three, etc.) OELs produced according to the present invention.

[0154] As mentioned hereabove, the OEL produced according to the present invention may be used for decorative purposes as well as for protecting and authenticating a security document.

[0155] Typical examples of decorative elements or objects include without limitation luxury goods, cosmetic packaging, automotive parts, electronic/electrical appliances, furniture and fingernail articles. [0156] Security documents include without limitation value documents and value commercial goods. Typical examples of value documents include without limitation banknotes, deeds, tickets, checks, vouchers, fiscal stamps and tax labels, agreements and the like, identity documents such as passports, identity cards, visas, driving licenses, bank cards, credit cards, transactions cards, access documents or cards, entrance tickets, public transportation tickets or titles and the like, preferably banknotes, identity documents, right-conferring documents, driving licenses and credit cards. The term “value commercial good” refers to packaging materials, in particular for cosmetic articles, nutraceutical articles, pharmaceutical articles, alcohols, tobacco articles, beverages or foodstuffs, electrical/electronic articles, fabrics or jewelry, i.e. articles that shall be protected against counterfeiting and/or illegal reproduction in order to warrant the content of the packaging like for instance genuine drugs. Examples of these packaging materials include without limitation labels, such as authentication brand labels, tamper evidence labels and seals. It is pointed out that the disclosed substrates, value documents and value commercial goods are given exclusively for exemplifying purposes, without restricting the scope of the invention.

[0157] Alternatively, the OEL may be produced onto an auxiliary substrate such as for example a security thread, security stripe, a foil, a decal, a window or a label and consequently transferred to a security document in a separate step.

[0158] The skilled person can envisage several modifications to the specific embodiments described above without departing from the spirit of the present invention. Such modifications are encompassed by the present invention.

[0159] Further, all documents referred to throughout this specification are hereby incorporated by reference in their entirety as set forth in full herein. EXAMPLES

[0160] The present invention is now described in more details with reference to non-limiting examples. The Examples below provide more details for the apparatuses according to the present invention and processes for the production of optical effects layers (OELs).

[0161] A UV-curable screen printing composition comprising platelet-shaped magnetic or magnetizable pigment particles has been prepared and is described in Table 1.

Table 1

(*) green-to-blue optically variable magnetic pigment particles having a flake shape of diameter d50 about 9 .m and thickness about 1 LLITI, obtained from Viavi Solutions, Santa Rosa, CA.

[0162] The UV-curable screen printing ink described in Table 1 was independently applied onto a substrate (x10) (fiduciary standard paper BNP 100 g/m², from Papierfabrik Louisenthal, dimensions: 80 mm x 80 mm) described hereabove (step a) of the process described herein, said application being carried out by hand screen printing using a 90T screen so as to form a coating layer (x20) (dimensions: 25 mm x 25 mm) having a thickness of about 20 .m.

Magnetic assembly (760) (Fig. 7)

[0163] The magnetic assembly (760) used to bi-axially pre-orient the pigment particles is disclosed in Fig. 3A of WO 2021/239607 A1 .

[0164] The magnetic assembly (760) comprised a) a first set (S1) comprising a first bar dipole magnet (761 -a) and two second bar dipole magnets (762-a and 762-d), a second set (S2) comprising a first bar dipole magnet (761 -b) and two second bar dipole magnets (762-b and 762-e), a third set (S3) comprising a first bar dipole magnet (761 -c) and two second bar dipole magnets (762-c and 762-f),and b) a first pair (P1) of third bar dipole magnets (763-a and 763-b) and a second pair (P2) of third bar dipole magnets (763-c and 763-f).

[0165] The uppermost surface of the first bar dipole magnet (761 -a, 761 -b and 761 -c) of the first, second and third sets (S1 , S2, S3), of the second bar dipole magnets (762-a to 762-f) of the first, second and third sets (S1 , S2, S3) and of the third bar dipole magnets (763-a to 763-d) of the first and second pairs (P1 and P2) were flush with each other.

[0166] The third bar dipole magnet (763-a) of the first pair (P1) was aligned with the second bar dipole magnet (762-a) of the first set (S1), with the second bar dipole magnet (762-b) of the second set (S2), with the third bar dipole magnet (763-c) of the second pair (P2) and with the second bar dipole magnet (762-c) of the third set (S3) so as to form a line. The third bar dipole magnet (763-b) was aligned with the second bar dipole magnet (762-d) of the first set (S1), with the second bar dipole magnet (662-e) of the second set (S2), with the third bar dipole magnet (763-d) of the second pair (P2) and with the second bar dipole magnet (762-f) of the third set (S3) so as form a line. For each line described herein, the third bar dipole magnets (763-a, 763-b, 663-c and 763-d) and the second bar dipole magnets (762-a to 672- f) were spaced apart by a third distance (d2) of 2 mm. The first bar dipole magnet (671 -a) of the first set (S1) and the first bar dipole magnet (671-b) of the second set (S2), and the first bar dipole magnet (661 - c) of the third set (S3) were spaced apart by a distance (d3) of 24 mm.

[0167] The first bar dipole magnets (761 -a, 761 -b and 761 -c) of the first, second and third sets (S1 , S2, S3) had the following dimensions: first length (L1) of 60 mm, first width (L2) of 40 mm and first thickness (L3) of 5 mm. Each of the second bar dipole magnets (762-a to 762-f) of the first, second and third set (S1 , S2, S3) had the following dimensions: second length (L4) of 40 mm, second width (L5) of 10 mm and second thickness (L6) of 10 mm. Each of the third bar dipole magnets (763-a to 763-d) of the first and second pairs (P1 , P2) had the following dimensions: third length (L7) of 20 mm, third width (L8) of 10 mm and third thickness (L9) of 10 mm.

[0168] The first bar dipole magnet (761 -a) of the first set (S1) and the second bar dipole magnets (762- a and 762-d) of the first set (S1) were aligned to form a column; and the first bar dipole magnet (761-b) of the second set (S2) and the second bar dipole magnets (762-b and 762-e) of the second set (S2) were aligned to form a column; and the first bar dipole magnet (761-c) of the third set (S3) and the second bar dipole magnets (762-c and 762-f) of the third set (S3) were aligned to form a column. For each set (S1 , S2, S3) and each column described herein, the first bar dipole magnets (761-a, 761-b and 761-c) and the two second bar dipole magnets (762-a and 762-d; 762-b and 762-e; and 762-c and 762- f, respectively) were spaced apart by a second distance (d1) of 2 mm.

[0169] The first bar dipole magnets (761-a, 761-b and 761-c) of the first, second and third sets (S1 , S2, S3) had their magnetic axis oriented to be substantially parallel to the substrate (710) and substantially parallel to the substrate (710), wherein the first bar dipole magnet (761-a) of the first set (S1) had its magnetic direction opposite to the magnetic direction of the first bar dipole magnet (761-b) of the second set (S2), and the first bar dipole magnet (761-b) of the second set (S2) had its magnetic direction opposite to the magnetic direction of the first bar dipole magnet (761-c) of the third set (S3). The first bar dipole magnet (761-a) ofthe first set (S1) and first bar dipole magnet (761-b) of the second set (S2), as well as the first bar dipole magnet (761-b) of the second set (S2) and the first bar dipole magnet (761- c) of the third set (S3), were spaced apart by a first distance (d3) of 24 mm (corresponding to the sum of the third length (L7) and the two third distances (d2)).

[0170] The two second bar dipole magnets (762-a to 762-f) of the first, second and third set (S1 , S2, S3) had their magnetic axis oriented to be substantially perpendicular to the substrate (610) surface. The South pole of the second bar dipole magnet (762-a) of the first set (S1), the South pole of the second bar dipole magnet (762-e) of the second set (S2) and the South pole of the second bar dipole magnet (762-c) of the third set (S3) pointed towards the substrate (710). The North pole of the second bar dipole magnet (762-d) of the first set (S1), the North pole of the second bar dipole magnet (762-b) of the second set (S2) and the North pole of the second bar dipole magnet (762-f) of the third set (S3) pointed towards the substrate (710). The North pole of the first bar dipole magnet (761 -a) of the first set (S1) pointed towards the second bar dipole magnet (762-d) of the first set (S1), the North pole of the second bar dipole magnet (761-b) of the second set (S2) pointed towards the first bar dipole magnet (762-b) of the second set (S2) and the North pole of the first bar dipole magnet (661 -c) of the third set (S3) pointed towards the second bar dipole magnet (662-f) of the third set (S3). The South pole of the third bar dipole magnet (763-a) of the first pair (P1) pointed towards the second bar dipole magnet (762- a) of the first set (S1), said second bar dipole magnet (762-a) having its South pole pointing towards the substrate (610); the South pole of the third bar dipole magnet (663-d) of the second pair (P1) pointed towards the second bar dipole magnet (762-e) of the second set (S2), said second bar dipole magnet (762-e) having its South pole pointing towards the substrate (610); the North pole of the third bar dipole magnet (663-b) of the first pair (P1) pointed towards the second bar dipole magnet (762-d) of the first set (S1), said second bar dipole magnet (662-d) having its North pole pointing towards the substrate (610); and the North pole of the third bar dipole magnet (763-c) of the second pair (P2) pointed towards the second bar dipole magnet (762-b) of the second set (S2), said second bar dipole magnet (762-b) having its North pole pointing towards the substrate (710).

[0171] The first bar dipole magnets (761 -a, 761-b and 761 -c) of the first, second and third sets (S1 , S2, S3) and the second bar dipole magnets (762-a to 762-f) of the first, second and third sets (S1 , S2, S3) were made of NdFeB N42; the third bar dipole magnets (763-a, 763-b, 763-c and 763-d) of the first and second pairs (P1 , P2) were made of NdFeB N48. All the magnets (761 -a to 761 -c, 762-a to 762-f and 763-a to 763-d) were embedded in a non-magnetic supporting matrix (not shown) made of POM having the following dimensions: 200 mm x 120 mm x 12 mm.

Apparatuses (xOO)

[0172] The apparatuses (xOO) used to prepare the optical effect layers (OELs) on the substrate (x10) described herein comprised a non-magnetic holder case (x50) schematically illustrated in Fig. 1C-1 and 1C-2 and having a H-shape cross-section (dimensions: 40 mm x 40 mm and the height and cross back being adjusted to have a distance d-a being 1 .7 mm, having a curved surface in one direction), a soft magnetic plate (830) shown in Fig. 8A and a magnetic-field-generating device (840) shown in Figs 8, wherein said apparatuses (xOO) were configured for receiving the substrate in an orientation parallel being substantially parallel to the substrate surface during the preparation process.

Soft magnetic plates (x30) (see Fig. 1-A and 8)

[0173] Three soft magnetic plates (830) made of FeSia granules (Catamold® FeSia from BASF, soft magnetic iron-silicon alloy having a coercivity He = 73 Am ¹ and a permeability pRmax = 5215) injected at about 80 wt-% in polyoxymethylene (POM) were provided. Said engraved soft magnetic plate (x30) (38 mm x 19 mm x 0.9 mm (T)) comprised a 5-shaped (H = 15 mm x W = 11 mm) indentation (x31) (D =: 0.9 mm) or void (x32).

Example E1 : the engraving in the form of a void (532) a cross-section shape in the form of a “V” with an engraving angle a being 90°(see Fig. 5B-2).

Example E2: the engraving in the form of an indentation (531) had a depth (D) of 0.8 mm and a cross- section shape in the form of a stepped-shaped indentation (see Fig. 5C-1), wherein the indentation comprised three steps, each one having a width of 0.5 mm and a thickness of 0.2 mm;

Comparative example C1 : the engraving in the form of a void (532) had a cross-section shape in the form of a “U” with an engraving angle being 90°(see Fig. 5A-2); and

[0174] The engravings in the form of the void (x32) and indentation (x31) was carried out by mechanical CNC engraving machine (Gravotech, model: IS400). The drilling bit was cylindrical with a diameter of 0.4 mm.

Maqnetic-field-qeneratinq device (840) (Figs 8B)

[0175] The magnetic-field-generating device (840) was similar to the first magnetic-field-generating device disclosed in Fig. 6A of WO 2021/ 083809 A1 .

[0176] The magnetic-field-generating device (840) in Figs 8B comprised a bar dipole magnet (840-a) (see Fig. 8B-2) and 61 dipole magnets (840-b and 840-c) (Fig. 8B-2) embedded in a square-shaped non-magnetic supporting matrix (840-d).

[0177] The bar dipole magnet (840-a) had the following dimensions: a length (L1) of about 29.9 mm, a width (L2) of about 29.9 mm, a thickness (L3) of about 6.9 mm. The bar dipole magnet (640-a) had a magnetic axis substantially parallel to its length and substantially parallel to the substrate (x10) surface. The bar dipole magnet (840-a) was made of compressed plasto-NdFeB GMP13 L grade BMNpi-80/48 (from Bomatec, Hori, CH).

[0178] Each of the 61 dipole magnets (840-b and 840-c) was a cylinder having a diameter (L4) of about 2 mm and a thickness (L5) of about 2 mm and having a magnetic axis parallel to the thickness (L5) and perpendicular to the substrate (x50) surface. The 61 dipole magnets (840-b and 840-c) were made of NdFeB N48.

[0179] The square-shaped supporting matrix (840-d) had a length of about 29.9 mm, a width of about 29.2 mm and a thickness of about 3 mm. The square-shaped supporting matrix (840-d) was made of POM. The square-shaped supporting matrix (840-d) comprised 61 indentations for receiving the 61 dipole magnets (840-b and 840-c).

[0180] The 61 dipole magnets (840-b and 840-c) were embedded in the 61 indentations of the supporting matrix (840-d), wherein six sets comprising each six of said 61 dipole magnets (840-b and 840-c) and five sets comprising each five of said 61 dipole magnets (840-b and 840-c) were arranged on eleven substantially parallel straight lines ai-n, wherein of each of said dipole magnets (840-b and 840-c) arranged on an uneven-numbered straight lines a.i (that is the dipole magnets arranged on the lines (ai, a.3, as, a? , ag and an; each of said uneven straight lines ai, as, as, a? , ag and an comprised six dipole magnets 840-b and 840-c) were arranged at the intersections of a grid comprising the eleven substantially parallel straight lines ann and six parallel straight lines pi e, as illustrated in Fig 8B-1. The straight lines ann were parallel with respect to each other, the straight lines Pj were parallel with respect to each other and the straight lines i were perpendicular to the straight lines i-s. The eleven lines an 11 and the six lines ne were equally spaced apart and neighboring lines were separated by a distance of about 2.5 mm.

[0181] Each of said 61 dipole magnets (840-b and 840-c) arranged on an even-numbered straight lines a: (i.e. the dipole magnets arranged on the lines a2. a4. ae, as and io _: each of said even straight lines a2. oc4, oce, as and aio comprising five dipole magnets 840-b and 840-c) were arranged between two neighboring straight lines j as illustrated in Fig. 8B-1.

[0182] On each ofthe eleven straight lines ai and on each of the six straight lines 0i, the dipole magnets (840-b and 840-c) were spaced apart and separated by a distance of 0.5 mm. On each of the eleven straight lines oci and on each of the six straight lines 0i, the dipole magnets (840-b) and the magnets (840-c) were disposed alternatively, i.e. they were disposed with alternating North or South poles facing the substrate (810).

[0183] Each straight line ai-n was substantially perpendicular with respect to the vector H of the first magnetic-field generating device (840-a) (not shown in Figs 8B).

[0184] The bar dipole magnet (840-a) and the square-shaped supporting matrix (840-d) carrying the 61 dipole magnets (840-b and 840-c) were spaced apart by a distance of about 0.2 mm.

[0185] As shown in Fig. 8, the soft magnetic plates (x30) were independently placed above the magnetic-field-generating device (840) and faced the topmost surface of said device (840) (i.e. faced the topmost surface of the square-shaped supporting matrix) and the right edge of the plate (x30) being aligned with the right edge of the magnetic-field-generating device (840). The distance d-a (i.e. the distance between the bottom surface of the soft magnetic plate (830) and the topmost surface of magnetic-field-generating device (840) was about 1.7 mm. The distance d-b (distance between the top surface of the soft magnetic plate (830) and the bottom surface of the substrate (810) was 0 mm. The distance between the coating layer (820) and first magnetic-field-generating device (840-a) was about 5 mm. The distance d-c (i.e. the distance between the coating layer (x20) and the magnetic assembly (x60)) was about 5 mm.

[0186] The assemblies (xOO) comprising the substrate (x10) carrying the coating layer (x20), the soft magnetic plate (x30) and the magnetic-field-generating device (x40) described hereabove and shown in Figs 8 were moved in the vicinity and below the static magnetic assembly (x60) shown in Fig. 7 as described hereabove.

[0187] As shown for example in Figs 1A-B and 8, the substrate (x10) carrying the coating layer (x20) was disposed on an apparatus (xOO) comprising the non-magnetic holder case (x50), the magnetic- fieldgenerating device (x40) and the soft magnetic plate (x30) carrying one or more indicia (x31 or x32) so as to form an assembly (x100) (step b) of the process described herein). As shown in Figs 1A-B, the so- obtained assembly (x100) was moved at a speed of about 1 m/sec in the vicinity and below the magnetic assembly (x60) (step c) of the process described herein) with the coating layer (x20) facing the static magnetic assembly (x60). Immediately after having moved the assembly (x100) below the static magnetic assembly (x60), the coating layer (x20) was at least partially cured at a distance of about 35 mm from the end of the magnetic assembly (x60) using a UV-LED-lamp from Phoseon (Type FireFlex 50 x 75 mm, 395 nm, 8 W/cm²).

[0188] The examples E1-E2, prepared with the apparatus disclosed hereabove, comprising a soft magnetic plate comprising an indentation with a V-shaped (E1) or stepped-shaped (E2) cross-section displayed an indicia with sharp well-resolved edges (right side of the OEL) and a pattern of bright areas and dark areas (left side of the OEL) moving when the OELs is tilted.

[0189] The so-obtained OELs of examples E1-E2 exhibits a bright and eye catching effect compared to the comparive example C1 .

Claims

1 . An apparatus (xOO) for producing an optical effect layer (OEL) comprising magnetically oriented platelet-shaped magnetic or magnetizable pigment particles on a substrate (x10), said optical effect layer (OEL) being made of a single cured coating layer (x20) comprising at least a first area exhibiting a 3D effect in the form of one or more indicia and at least a second area exhibiting a dynamic movement upon tilting, said at least one of said first area and at least one of said second area being adjacent to each other, said apparatus (xOO) being configured for receiving the substrate (x10) in an orientation substantially parallel to a first plane (P) and above the first plane (P) and comprising: a) a soft magnetic plate (x30) carrying one or more indicia in the form of one or more indentations (x31) and/or one or more voids (x32) having a stepped-shaped cross-section or a V-shaped cross-section, b) a magnetic-field-generating device (x40) comprising at least one dipole magnet (x40-a), wherein the soft magnetic plate (x30) is placed above the first magnetic-field-generating device (x40).

2. The apparatus (xOO) according to claim 1 , wherein the soft magnetic plate (x30) carries one or more indicia in the form of one or more indentations (x31).

3. The apparatus (xOO) according to claim 1 , wherein the soft magnetic plate (x30) carries one or more indicia in the form of one or more voids (x32).

4. The apparatus (xOO) according to any one of claims 1 to 3, wherein the stepped-shaped crosssection of the one or more indentations (x31) and/or the one or more voids (x32) comprise between 2 and 20 steps.

5. The apparatus (xOO) according to any one of claims 1 to 4, wherein the soft magnetic plate (x30) is disposed between the magnetic field generating device (x40) and the substrate (x10) in or along a vertical axis.

6. The apparatus (xOO) according to any one of claims 1 to 5, wherein the soft magnetic plate (x30) has a thickness between about 0.5 mm and about 5 mm.

7. The apparatus (xOO) according to any one of claims 1 to 6, wherein the top surface of the soft magnetic plate (x30) is smaller than a total top surface of the magnetic-field-generating device (x40).

8. A device for producing an optical effect layer (OEL) comprising magnetically oriented plateletshaped magnetic or magnetizable pigment particles on a substrate (x10), said optical effect layer (OEL) comprising at least a first area exhibiting a 3D effect in the form of one or more indicia and at least a second area exhibiting a dynamic movement upon tilting, wherein at least one of said first area and at least one of said second area are adjacent, said device being configured for receiving the substrate (x10) and comprises the apparatus (xOO) recited in any one of claims 1 to 7 and comprising the magnetic-field- generating device (x40) and the soft magnetic plate (x30) carrying the one or more indicia in the form of one or more indentations (x31) and/or one or more voids (x32) having a stepped-shaped cross-section or a V-shaped cross-section, and a magnetic assembly (x60), wherein the soft magnetic plate (x30) is placed above the magnetic-field-generating device (x40), and wherein the magnetic-field-generating device (x40) and the soft magnetic plate (x30) are arranged on or in a cylinder so that, when the cylinder is rotated, the apparatus (xOO) and the magnetic assembly (x60) are moved relative to each other so that the surface of the apparatus (xOO) faces the magnetic assembly (x60) allowing at least a part of the platelet-shaped magnetic or magnetizable pigment particles to be bi-axially oriented.

9. A process for producing the optical effect layer (OEL) recited in claim 1 on the substrate (x10), said process comprising the steps of: a) applying onto a substrate (x10) surface a coating composition comprising i) plateletshaped magnetic or magnetizable pigment particles and ii) a binder material so as to form a coating layer (x20) on said substrate (x10), said coating composition being in a first state, b) forming an assembly (x100) comprising the substrate (x10) carrying the coating layer (x20) and the apparatus (xOO) recited in any one of claims 1 to 7, c) moving the assembly (x100) comprising the substrate (x10) carrying the coating layer (x20) and the apparatus (xOO) recited in any one of claims 1 to 7 obtained under step b) through an inhomogeneous magnetic field of a static magnetic assembly (x60) so as to bi- axially orient at least a part of the platelet-shaped magnetic or magnetizable pigment particles, and d) hardening the coating composition to a second state so as to fix the platelet-shaped magnetic or magnetizable pigment particles in their adopted positions and orientations, wherein the optical effect layer (OEL) is made of a single cured coating layer (x20) comprising at least a first area exhibiting a 3D effect in the form of one or more indicia and at least a second area exhibiting a dynamic movement upon tilting the substrate (x10), said at least one of said first area and at least one of said second area being adjacent to each other.

10. The process according to claim 9, wherein the substrate (x10) carrying the coating layer (x20) is arranged above the apparatus (xOO) with the soft magnetic plate (x30) facing the substrate (x10) being a topmost layer of the apparatus (xOO).

11. The process according to any one of claims 9 to 10, wherein the step a) is carried out by a process selected from the group consisting of screen printing, rotogravure printing, and flexography printing.

12. The process according to any one of claims 9 to 11 , wherein the step c) is carried out by UV- Vis light radiation curing, and preferably the step c) is carried out partially simultaneously with the step b).

13. An optical effect layer (OEL) produced by the process recited in any one of claims 9 to 12.